US20030196517A1 - Method of treating heavy metal and/or organic compound - Google Patents
Method of treating heavy metal and/or organic compound Download PDFInfo
- Publication number
- US20030196517A1 US20030196517A1 US10/396,516 US39651603A US2003196517A1 US 20030196517 A1 US20030196517 A1 US 20030196517A1 US 39651603 A US39651603 A US 39651603A US 2003196517 A1 US2003196517 A1 US 2003196517A1
- Authority
- US
- United States
- Prior art keywords
- heating
- furnace
- organic compound
- heavy metal
- soil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G7/00—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals
- F23G7/14—Incinerators or other apparatus for consuming industrial waste, e.g. chemicals of contaminated soil, e.g. by oil
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
- B09B3/40—Destroying solid waste or transforming solid waste into something useful or harmless involving thermal treatment, e.g. evaporation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/06—Reclamation of contaminated soil thermally
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2201/00—Pretreatment
- F23G2201/50—Devolatilising; from soil, objects
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2201/00—Pretreatment
- F23G2201/60—Separating
- F23G2201/602—Separating different sizes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2201/00—Pretreatment
- F23G2201/70—Blending
- F23G2201/701—Blending with additives
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2209/00—Specific waste
- F23G2209/30—Solid combustion residues, e.g. bottom or flyash
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23G—CREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
- F23G2900/00—Special features of, or arrangements for incinerators
- F23G2900/50209—Compacting waste before burning
Definitions
- the present invention relates to a method of purifying soil and/or burned ash containing heavy metals and/or organic compounds. Particularly, the present invention relates to a method of removing or detoxifying heavy metals and/or organic compounds contained in soil and/or burned ash.
- the pollutants include heavy metals such as cadmium (Cd), lead (Pb), hexavalent chromium (Cr 6+ ), arsenic (As), mercury (Hg), and the like, organochlorine compounds such as dioxines, and the like, other organic pollutants (volatile organic compounds VOC and persistent organic pollutants POPs), and the like.
- a heat treatment method for purifying soil polluted with an arsenic compound a method is used, in which a mixture of the soil and a-reducing agent is heated, or the soil is heated in the presence of a reducing gas to reduce and evaporate the arsenic compound from the soil at a low temperature.
- carbon or ammonium sulfate is used as the reducing agent
- carbon dioxide, carbon monoxide, ammonia, or methane gas is used as the reducing gas.
- a rotary kiln is used as a waste reclamation furnace.
- residual soil is molded by an extrusion granulator, burned by an outside heating type or inside heating type rotary kiln, and used as burned modified soil.
- Another method is disclosed, in which a reducing agent containing a formic acid and/or oxalic acid salt is added to a material to be treated, and the resultant mixture is heated to reduce heavy metals or organochlorine compounds, to remove or detoxify the heavy metals or organochlorine compounds.
- a fluidized bed type heating furnace can be used.
- this method requires a relatively expensive formic acid and/or oxalic acid salt to increase the treatment cost, causing a problem of practicability.
- heat is mainly transferred by convective heat transfer between a heated gas and a material to be treated, and a heat transfer area is extremely larger than the rotary kiln to permit the realization of rapid uniform heating.
- the material to be treated contains a lump material, the material must be previously ground because the material to be treated, which can be used in the fluidized bed, is limited to a powdery material.
- the fluidized bed type has low handleability and thus has the problem of increasing the treatment cost.
- the present invention has been achieved in consideration of the above-described situation, and an object of the present invention is to provide a method of purifying soil and/or burned ash with a higher throughput than a conventional method, the method comprising heat-treating soil or burned ash containing heavy metals and/or organic compounds.
- a method of treating heavy metals and/or organic compounds comprises a heating step of heating a material containing heavy metals and/or organic compounds, in a radiant rapid heating furnace to purify the material.
- a method of treating heavy metals and/or organic compounds comprises an agglomeration step of agglomerating at least a portion of a material to be treated, which contains heavy metals and/or organic compounds, to form agglomerates, and a heating step of heating the agglomerates and the unagglomerated residue of the material in a radiant rapid heating furnace to purify the material.
- a method of treating heavy metals and/or organic compounds further comprises a screening step of screening a material to be treated to separate the material into an oversize portion and an undersize portion before an agglomeration step, the undersize portion being supplied to the agglomeration step, and the oversize portion being supplied to a heating step without the agglomeration step.
- a method of treating heavy metals and/or organic compounds comprises a mixing step of mixing a carbonaceous reducing agent and an metal oxide-containing material with a material to be treated, which contains heavy metals and/or organic compounds, and a heating step of heating the resultant mixture in a heating furnace to purify the material.
- a method of treating heavy metals and/or organic compounds comprises heating a material to be treated at an ambient temperature of 700° C. or more at least in the second half of a heating step.
- a method of treating heavy metals and/or organic compounds comprises heating a material to be treated at an ambient temperature of 700° C. or less in the first half of a heating step.
- a radiant rapid heating furnace is a rotary hearth furnace.
- the radiant rapid heating furnace comprises a hearth (or grate) continuously or intermittently horizontally moved, and a heating furnace body which covers an upper portion of the hearth (or grate).
- a heating furnace body which covers an upper portion of the hearth (or grate).
- soil and/or burned ash as the material is placed on the hearth (or grate), and mainly radiantly heated from above by passing through the heating furnace body together with the hearth.
- Another furnace may be used, in which the soil and/or burned ash placed on the hearth is moved by a scraper without movement of the hearth.
- Examples of the radiant rapid heating furnace include a moving-bed furnace, a tunnel kiln, and the like, and examples of the moving-bed furnace include a circular rotary hearth furnace, and a linear or grate-type furnace.
- a multi-hearth furnace is also included in the radiant rapid heating furnace.
- a heat transfer mechanism of the radiant rapid heating furnace includes radiant heat transfer from a space (combustion gas and the furnace wall) above the material to the surface of the material, and conductive heat transfer in the material from the upper surface of the material to the lower surface thereof.
- the radiant heat transfer rate is proportional to a difference between the fourth powers of the absolute temperatures of the heated material and the material to be heated, while the conductive heat transfer rate is proportional to a temperature gradient from the upper surface and the lower surface of the material. Therefore, conductive heat transfer is generally a rate-determining step.
- the material By using the radiant rapid heating furnace as the heating furnace, the material can be thinly placed on the hearth (or grate).
- the thickness of the material placed on the hearth (or grate) depends upon the type of the charger used, but the thickness can be generally minimized to about 10 mm. Therefore, the area (the upper surface area of the material) of radiant heat transfer from the heated material (combustion gas and the furnace wall) in the upper space to the material can be increased to significantly increase the amount of radiant heat transfer.
- the layer of the material to be heated is thin, and thus heat transferred to the upper surface of the material by radiant heat transfer is transferred to the lower surface of the material layer to be heated by conductive heat transfer in the rate-determining step within a short time, thereby achieving rapid uniform heating of the material. Therefore, the whole material is uniformly rapidly heated to remove or detoxify the heavy metals or organic compounds adhering to the surface of the material (soil or/or burned ash) within a short time.
- the inside of the radiant rapid heating furnace is divided into zones by the furnace walls so that the temperature and atmosphere of each of the zones can easily be-controlled. Consequently, the heavy metals can easily be reduced and evaporated by suppressing an oxidizing atmosphere in the furnace.
- the ratio (occupancy ratio) of a sectional area of the material to the total sectional area of the kiln is 5 to 17% in an ordinary operation.
- the maximum thickness of the material in the kiln reaches 95 to 230 mm (average thickness of about 50 to 150 mm).
- the heat transfer area (the upper surface area of the material) relative to the amount of the material staying in the kiln, is extremely smaller than that in the radiant rapid heating furnace.
- the rate-determining step of conductive heating is absent from the radiant rapid heating furnace because the material is agitated by rolling the kiln, the heating rate is significantly lower than that in the radiant rapid heating furnace, and thus a long time is required for heating.
- At least a portion of the soil and/or burned ash containing the heavy metals and/or organic compounds is agglomerated to form agglomerates, and the agglomerates and the residue of the soil and/or burned ash are placed on the hearth (or grate) of the radiant rapid heating furnace.
- Agglomeration of at least a portion of the soil and/or burned ash increases the packing density of particles of the soil and/or burned ash in the agglomerates, and thus the packing density of the whole layer of the material is also increased as compared with a case in which the whole of the soil and/or burned ash is placed on the hearth (or grate) without agglomeration, thereby further increasing the conductive heat transfer rate.
- handling after heating, such as transport or the like is facilitated, and the agglomerates having high strength are preferably used as a roadbed and an aggregate.
- the soil and/or burned ash containing the heavy metals and/or organic compounds frequently contains a large amount of moisture, and is thus difficult to handle without any treatment. Therefore, at least a portion of the soil and/or burned ash is preferably dried before the agglomeration.
- the soil and/or burned ash containing the heavy metals and/or organic compounds frequently contains large lumps, and thus the large lumps are preferably previously removed by a screen having a predetermined screen mesh (for example, 10 mm) for protecting an agglomerator used for agglomeration.
- a screen having a predetermined screen mesh for example, 10 mm
- the resultant agglomerates and the oversize portion containing the large lumps are preferably charged in the radiant rapid heating furnace.
- most of pollutants such as the heavy metals and/or organic compounds adhere only to the surfaces of the lumps, and thus the pollutants can easily be removed or detoxified by heating without grinding, to cause no problem.
- the radiant rapid heating furnace preferably has at least two exhaust gas discharge ports so that the exhaust gas is separately discharged from the discharge ports. Therefore, the exhaust gas containing heavy metals having different evaporation temperatures can be separately discharged, thereby facilitating a subsequent treatment of the exhaust gas and reclamation of recovered materials.
- a carbonaceous reducing agent and a metal oxide-containing material are preferably mixed with the soil and/or burned ash containing the heavy metals and/or organic compounds, and then the resultant mixture is charged in the heating furnace. Therefore, in heating in the heating furnace, a carbon content (C) in the carbonaceous reducing agent reacts with the metal oxide (M x O y ) to activate the generation of CO gas, as shown by the following reaction formula (1):
- the heating furnace is not limited to the radiant rapid heating furnace.
- the method can also be applied to a conventional rotary kiln.
- the ambient temperature in the heating furnace is preferably 700° C. or more. Therefore, As and Hg which evaporate at relatively low temperatures, and Pb and Cd which evaporate at higher temperatures, can be evaporated and removed from the material.
- the ambient temperature in the heating furnace is preferably 700° C. or less. Therefore, low-temperature volatile metals such as As and Hg, and high-temperature volatile metals such as Pb and Cd can be separately evaporated and removed in the first half and the second half, respectively, and thus the low-temperature and high-temperature heavy metals can be separately recovered, thereby facilitating final treatment and reclamation after recovery.
- a rotary hearth furnace is recommended as the heating furnace.
- the agglomerates can be treated without pulverization, and the inside of the furnace can easily be divided, thereby facilitating separated recovery of the volatile materials removed by evaporation from the treated material.
- FIG. 1 is a drawing schematically showing a construction of an apparatus used in example 1;
- FIG. 2 is a vertical sectional view of a rotary hearth furnace used in example 1.
- FIG. 3 is a graph showing the relation between the elapsed time from sample charging and the CO concentration of an atmosphere gas for heating each sample containing polluted soil in example 2.
- FIG. 1 is a drawing schematically showing a construction of an apparatus used for a method of treating heavy metals and/or organic compounds according to an embodiment of the present invention.
- reference numeral 1 denotes a dryer for drying polluted soil A 1 as a material to be treated
- reference numeral 2 a screen for screening soil A 2 dried by the dryer 1
- reference numeral 3 an agglomerator for agglomerating an undersize portion A 3 put through the screen 2
- reference numeral 4 a radiant rapid heating furnace for heating agglomerates A 5 produced by agglomeration by the agglomerator 3 and an oversize portion A 4 put through the screen 2 .
- reference numerals 5 a and 5 b denote exhaust gas discharge ports provided at two positions of the radiant rapid heating furnace 4
- reference numerals 6 a and 6 b denote dust collectors connected to the exhaust gas discharge ports 5 a and 5 b, respectively, through exhaust gas ducts (not shown).
- polluted soil A 1 soil containing pollutants such as heavy metals such as cadmium (Cd), lead (Pb), hexavalent chromium (Cr 6+ ), arsenic (As), mercury (Hg), and the like, organochlorine compounds such as dioxines, and the like, and other organic pollutants is treated.
- pollutants such as heavy metals such as cadmium (Cd), lead (Pb), hexavalent chromium (Cr 6+ ), arsenic (As), mercury (Hg), and the like
- organochlorine compounds such as dioxines, and the like, and other organic pollutants is treated.
- the moisture content is preferably previously decreased to 5% by mass or less, more preferably 3% by mass or less, by drying with the dryer 1 . This is because handling is facilitated by drying. Also, screening is also facilitated by drying. Furthermore, drying before agglomeration has not only the effect of preventing the occurrence of excessive bursting even when the agglomerates A 5 are charged in the heating furnace 4 , but also the effect of decreasing the time required for drying the agglomerates A 5 in the heating furnace 4 to improve a throughput, and saving the fuel required for drying in the heating furnace 4 . Of course, the dryer 1 is unnecessary for treatment of soil A 1 having a low moisture content.
- the drying step may be omitted according to a treatment scale, and thus the soil may be dried in the heating furnace.
- a treatment without agglomeration has the low probability of bursting, but drying is preferably performed to an extent which causes no trouble such as clogging in charging in the heating furnace.
- more preferably the density of the soil A 1 is increased by compression with a press after charging in the furnace to improve a heat transfer efficiency, or a groove is, formed in the surface of the soil A 1 by a scraper or the like to increase a heat receiving area.
- the type of the dryer 1 is not limited, and any one of a rotary dryer type, a fluidized bed dryer type, and the like may be used. However, in this example, a simple rotary dryer with rich performance is used (drying step).
- drying of the agglomerates A 5 after agglomeration has the effect of suppressing bursting in the heating furnace 4 , improving productivity and decreasing fuel consumption.
- the soil containing a large amount of moisture is difficult to agglomerate.
- a relatively expensive apparatus such as a moving-bed dryer or the like is required for drying the agglomerates A 5 in a stationary state after agglomeration so as to prevent bursting and powdering.
- the large lumps are preferably removed by the screen 2 after drying in order to protect the agglomerator 3 .
- a vibrating screen can be used as the screen 2 , and the screen mesh is 10 mm in consideration of the protection of the agglomerator and the screening efficiency.
- the large lumps A 4 on the screen 2 are ground, and then mixed with the undersize portion A 3 or used for other applications.
- the large lumps A 4 are charged in the heating furnace 4 together with the agglomerates A 5 after agglomeration described below (screening step).
- the undersize portion A 3 from which the large lumps A 4 are moved by the screen 2 is preferably agglomerated by the agglomerator 3 to produce the agglomerates A 5 having a predetermined size.
- the type of the agglomerator 3 is not limited, and any one of a press molding machine, an extrusion molding machine, tumbling granulators such as a dish-shaped granulator and drum granulator, an agitating granulator, a fluidized bed granulator, and the like may be used.
- the press molding machine, the extrusion molding machine, or the tumbling granulator, which can produce agglomerates with a high density is preferably used.
- a press agglomerator capable of achieving a high density is recommended. Furthermore, a binder and moisture may be added to the undersize portion A 3 before agglomeration according to demand.
- the shape and size of the agglomerates A 5 are not limited, a pillow-shaped briquette of 39 mm ⁇ 20 mm ⁇ 12 mm (volume of about 6 cm 3 ) is formed by compression molding using a press agglomerator, and used in this example (agglomeration step).
- FIG. 2 is a vertical sectional view showing the rotary hearth furnace 4 used in this example.
- the rotary hearth furnace 4 comprises a doughnut-like hearth 41 which horizontally rotates, a heating furnace body 42 which covers the upper portion of the hearth 41 , a charger 43 for charging the agglomerates A 5 and the large lumps A 4 (generically named a “material A 6 ” to be heated) onto the hearth 41 , and a discharger 44 for discharging the heated material A 6 (purified soil A 7 ) after heating from the hearth 41 to the outside.
- the material A 6 is charged onto the hearth 41 by the charger 43 so that the thickness is about 1 to 2 times as large as the thickness (in this example, 12 mm) of the agglomerates A 5 .
- the heating furnace body 42 is divided into four zones (I, II, III, and IV zones) along the movement direction of the hearth 41 , and a combustion burner (not shown) is provided in each of the zones so that the ambient temperature of each zone can be precisely controlled.
- the ambient temperatures (the temperature near the material A 6 ) of the two zones (I and II zones) in the first half are 700° C. or less
- the ambient temperatures (the temperature near the material A 6 ) of the two zones (III and IV zones) in the second half are 700 to 1250° C.
- the exhaust gas discharge ports 5 a and 5 b are provided in the first zone (I zone) and last zone (IV zone), respectively, so that exhaust gas from the two zones (I and II zones) in the first half, and exhaust gas from the two zones (III and IV zones) in the second half can be separately discharged.
- the material A 6 is heated to 700° C. or less in the two zones (I and II zones) in the first half to first remove As and Hg which evaporate at relatively low temperatures.
- the material A 6 is heated to the maximum temperature of about 1250° C. to remove Pb and Cd which evaporate at higher temperatures.
- fly ash containing a high concentration of As can be recovered from the dust collector 6 a connected to the exhaust gas discharge port 5 a in the first half, and fly ash containing a high concentration of Pb can be recovered from the dust collector 6 b connected to the exhaust gas discharge port 5 b in the second half.
- the inside of the furnace cannot be divided into zones from the viewpoint of structure, and thus, unlike in this example, the temperature cannot be easily precisely controlled in each zone in the furnace, and exhaust gas cannot be discharged from a plurality of positions. Furthermore, in the conventional method, the gas atmosphere in the furnace cannot be controlled to cause difficulties in evaporating heavy metals by reduction.
- the material A 6 passes through the IV zone in the heating furnace body 42 , the material A 6 is discharged as the purified soil A 7 to the outside by the discharger 44 . In this example, when the retention time of the material A 6 at an average ambient temperature of 1200° C.
- hexavalent chromium (Cr 6+ ) in the material A 6 is detoxified to a valence state (a metal, bivalent, or trivalent) other than a hexavalent state, which is hard to elute, and the organochlorine compounds such as dioxine are also detoxified by heating decomposition (heating step).
- the polluted soil A 1 can be highly purified within a short time, as compared with the conventional rotary kiln.
- the ambient temperatures in the first half and second half of the heating furnace are set with a boundary at 700° C.
- setting of the ambient temperatures is not limited to this, and the temperatures can be appropriately changed according to the composition of the material to be treated, and the evaporation temperature of the material to be separately recovered, etc.
- the first half and second half simply mean the front part and back part of the heating step, not strictly mean the first half and second half of the heating step. Therefore, the passage time (retention time) of the material to be treated in the first half of the heating furnace is not necessarily equal to that in the second half thereof.
- the first half of the heating furnace can be set to longer than that of the second half.
- the second half of the heating furnace can be set to longer than that of the first half.
- the ambient temperature of the heating furnace is set in the two steps on the front and back parts.
- the temperature can be set in the three steps of the front part, an intermediate part, and the back part.
- the front part, the intermediate part and the back part are set to 500° C. or less, 500 to 800° C. and 800° C. or more, respectively, Hg, As and Cd, and Pb can be separately recovered in the front part, the intermediate part and the back part, respectively.
- the intermediate part means a part between the front and back parts.
- Each of single soil (Comparative Example 1), a mixture (Comparative Example 2) containing 97 parts by mass of soil and 3 parts by mass of coke power serving as the carbonaceous reducing agent, a mixture (Example 1 of this invention) containing 82 parts by mass of soil, 3 parts by mass of coke powder serving as the carbonaceous reducing agent, and 15 parts by mass of an iron ore composed of an metal oxide was formed in a pillow-like briquette sample of 39 mm ⁇ 20 mm ⁇ 12 mm (volume of about 6 cm 3 ) by compression molding using a press agglomerator. Each of the samples was heated at 1200° C. (constant) in a N 2 atmosphere in a small tubular furnace for about 12 minutes to measure changes in the CO concentration in the atmosphere gas with time.
- FIG. 3 shows the relationship between the elapsed time from sample charging in the tubular furnace and the CO concentration of atmosphere gas.
- the briquette of Example 1 of this invention has a crushing strength of 530 N after heating, and is thus suitable as a roadbed, an aggregate, and the like.
- the material to be treated is soil, burned ash also can be treated as a material containing heavy metals and/or organic compounds to produce the same effect as described below in Example 3.
- Burned ash is heated by using the same apparatus as that used Example 1.
- Each of two samples including single burned ash (Example 2 of this invention), and a mixture (Example 3 of this invention) containing 82 parts by mass of burned ash, 3 parts by mass of coke powder serving as a carbonaceous reducing agent, and 15 parts by mass of iron ore composed of a metal oxide was molded in a tablet of 20 mm in diameter ⁇ 15 mm in length, and then heated at an average ambient temperature of 1200° C. in a rotary hearth furnace for a retention time of 12 minutes.
- Table 1 shows the Pb concentrations of the tablet before and after heating, and crushing strength of the tablet after heating.
- Table 1 indicates that the heavy metals of the burned ash can be removed by treatment. TABLE 1 Crushing Pb concentration Pb concentration strength after before heating after heating heating (mg/kg) (mg/kg) (N/tablet) Example 2 of 530 120 590 this invention Example 3 of 740 50 Unmeasured this invention
- iron-making dust containing an iron oxide such as blast furnace dust, converter dust, electric furnace dust, mill scales, mill sludge, pickling sludge, sintering dust, and the like
- nonferrous oxides such as nickel oxide, manganese oxide, and the like
- coke powder, coal, petroleum coke, waste carbides, RDF carbides, carbonaceous sludge, scrap tires, blast furnace dust, and the like may be used as the carbonaceous reducing agent.
- the blast furnace dust is preferred because it contains an ion oxide (metal oxide) and a carbon content (carbonaceous reducing agent).
Abstract
The present invention provides a method of purifying polluted soil and/or burned ash containing heavy metals and/or organic compounds with a higher throughput than a conventional method. In this method, polluted soil and/or burned ash is dried by, for example, a rotary dryer so that the moisture content is 5% by mass or less, preferably 3% by mass or less, and then large lumps having a particle diameter of 10 mm or more are removed by a vibrating screen. Only an undersize portion is formed into a briquette having a volume of about 6 cm3 by a press molding machine. The briquette is charged in a rotary hearth furnace together with the large lumps, and heated in the furnace to remove or detoxify the heavy metals and organic compounds by evaporation with high efficiency.
Description
- 1. Field of the Invention
- The present invention relates to a method of purifying soil and/or burned ash containing heavy metals and/or organic compounds. Particularly, the present invention relates to a method of removing or detoxifying heavy metals and/or organic compounds contained in soil and/or burned ash.
- 2. Description of the Related Art
- In recent years, various heat treatment methods have been proposed as methods of removing or detoxifying pollutants contained in soil and/or burned ash. Herein, the pollutants include heavy metals such as cadmium (Cd), lead (Pb), hexavalent chromium (Cr6+), arsenic (As), mercury (Hg), and the like, organochlorine compounds such as dioxines, and the like, other organic pollutants (volatile organic compounds VOC and persistent organic pollutants POPs), and the like.
- As a heat treatment method for purifying soil polluted with an arsenic compound, a method is used, in which a mixture of the soil and a-reducing agent is heated, or the soil is heated in the presence of a reducing gas to reduce and evaporate the arsenic compound from the soil at a low temperature. In this method, carbon or ammonium sulfate is used as the reducing agent, and carbon dioxide, carbon monoxide, ammonia, or methane gas is used as the reducing gas.
- However, when only the reducing agent such as carbon is added, the amount of the CO gas generated is limited, and thus reduction of the arsenic compound is not sufficiently promoted, thereby quite possibly failing to achieve a high rate of removal.
- A rotary kiln is used as a waste reclamation furnace. For example, residual soil is molded by an extrusion granulator, burned by an outside heating type or inside heating type rotary kiln, and used as burned modified soil.
- However, in the use of the outside heating type rotary kiln, heat is mainly transferred by conductive heat transfer through the furnace wall, causing difficulties in rapid heating. On the other hand, in the use of the inside heating type rotary kiln, heat is mainly transferred by radiant heat transfer, but a heat transfer area is small as compared with the ratio of the occupied area of a material in the furnace, thereby causing difficulties in rapid heating. Therefore, both the inside and outside heating types have a fault that heat treatment requires a long time, and the apparatus used is greater than enough as compared with its throughput. Also, in a rotary kiln, a gas discharge port is limited to one position, and thus the harmful materials removed by evaporation cannot be separately recovered according to the types of the materials.
- Another method is disclosed, in which a reducing agent containing a formic acid and/or oxalic acid salt is added to a material to be treated, and the resultant mixture is heated to reduce heavy metals or organochlorine compounds, to remove or detoxify the heavy metals or organochlorine compounds. Besides the rotary kiln, a fluidized bed type heating furnace can be used.
- However, this method requires a relatively expensive formic acid and/or oxalic acid salt to increase the treatment cost, causing a problem of practicability. In the use of the fluidized bed type heating furnace, heat is mainly transferred by convective heat transfer between a heated gas and a material to be treated, and a heat transfer area is extremely larger than the rotary kiln to permit the realization of rapid uniform heating. However, when the material to be treated contains a lump material, the material must be previously ground because the material to be treated, which can be used in the fluidized bed, is limited to a powdery material. Also, a large amount of dust contained in the exhaust gas must be treated, a countermeasure against abrasion of the furnace wall is required, and the temperature cannot be set to high because adhesion easily occurs. Therefore, the fluidized bed type has low handleability and thus has the problem of increasing the treatment cost.
- The present invention has been achieved in consideration of the above-described situation, and an object of the present invention is to provide a method of purifying soil and/or burned ash with a higher throughput than a conventional method, the method comprising heat-treating soil or burned ash containing heavy metals and/or organic compounds.
- In a first aspect of the present invention, a method of treating heavy metals and/or organic compounds comprises a heating step of heating a material containing heavy metals and/or organic compounds, in a radiant rapid heating furnace to purify the material.
- In a second aspect of the present invention, a method of treating heavy metals and/or organic compounds comprises an agglomeration step of agglomerating at least a portion of a material to be treated, which contains heavy metals and/or organic compounds, to form agglomerates, and a heating step of heating the agglomerates and the unagglomerated residue of the material in a radiant rapid heating furnace to purify the material.
- In a third aspect of the present invention, a method of treating heavy metals and/or organic compounds further comprises a screening step of screening a material to be treated to separate the material into an oversize portion and an undersize portion before an agglomeration step, the undersize portion being supplied to the agglomeration step, and the oversize portion being supplied to a heating step without the agglomeration step.
- In a fourth aspect of the present invention, a method of treating heavy metals and/or organic compounds comprises a mixing step of mixing a carbonaceous reducing agent and an metal oxide-containing material with a material to be treated, which contains heavy metals and/or organic compounds, and a heating step of heating the resultant mixture in a heating furnace to purify the material.
- In a fifth aspect of the present invention, a method of treating heavy metals and/or organic compounds comprises heating a material to be treated at an ambient temperature of 700° C. or more at least in the second half of a heating step.
- In a sixth aspect of the present invention, a method of treating heavy metals and/or organic compounds comprises heating a material to be treated at an ambient temperature of 700° C. or less in the first half of a heating step.
- In a seventh aspect of the present invention, in a method of treating the heavy metals and/or organic compounds, a radiant rapid heating furnace is a rotary hearth furnace.
- The radiant rapid heating furnace comprises a hearth (or grate) continuously or intermittently horizontally moved, and a heating furnace body which covers an upper portion of the hearth (or grate). In the radiant rapid heating furnace, soil and/or burned ash as the material is placed on the hearth (or grate), and mainly radiantly heated from above by passing through the heating furnace body together with the hearth. Another furnace may be used, in which the soil and/or burned ash placed on the hearth is moved by a scraper without movement of the hearth.
- Examples of the radiant rapid heating furnace include a moving-bed furnace, a tunnel kiln, and the like, and examples of the moving-bed furnace include a circular rotary hearth furnace, and a linear or grate-type furnace. A multi-hearth furnace is also included in the radiant rapid heating furnace.
- A heat transfer mechanism of the radiant rapid heating furnace includes radiant heat transfer from a space (combustion gas and the furnace wall) above the material to the surface of the material, and conductive heat transfer in the material from the upper surface of the material to the lower surface thereof. The radiant heat transfer rate is proportional to a difference between the fourth powers of the absolute temperatures of the heated material and the material to be heated, while the conductive heat transfer rate is proportional to a temperature gradient from the upper surface and the lower surface of the material. Therefore, conductive heat transfer is generally a rate-determining step.
- By using the radiant rapid heating furnace as the heating furnace, the material can be thinly placed on the hearth (or grate). The thickness of the material placed on the hearth (or grate) depends upon the type of the charger used, but the thickness can be generally minimized to about 10 mm. Therefore, the area (the upper surface area of the material) of radiant heat transfer from the heated material (combustion gas and the furnace wall) in the upper space to the material can be increased to significantly increase the amount of radiant heat transfer.
- Furthermore, the layer of the material to be heated is thin, and thus heat transferred to the upper surface of the material by radiant heat transfer is transferred to the lower surface of the material layer to be heated by conductive heat transfer in the rate-determining step within a short time, thereby achieving rapid uniform heating of the material. Therefore, the whole material is uniformly rapidly heated to remove or detoxify the heavy metals or organic compounds adhering to the surface of the material (soil or/or burned ash) within a short time.
- The inside of the radiant rapid heating furnace is divided into zones by the furnace walls so that the temperature and atmosphere of each of the zones can easily be-controlled. Consequently, the heavy metals can easily be reduced and evaporated by suppressing an oxidizing atmosphere in the furnace.
- On the other hand, in a heating system using a conventional inside heating type rotary kiln, radiant heat transfer from the heated material (combustion gas and the furnace wall) in the upper space to the surface of the material is mainly performed. However, in heating by the rotary kiln, the ratio (occupancy ratio) of a sectional area of the material to the total sectional area of the kiln is 5 to 17% in an ordinary operation. For example, in the kiln having an inner diameter of 1 m, the maximum thickness of the material in the kiln reaches 95 to 230 mm (average thickness of about 50 to 150 mm). Therefore, the heat transfer area (the upper surface area of the material) relative to the amount of the material staying in the kiln, is extremely smaller than that in the radiant rapid heating furnace. Although the rate-determining step of conductive heating is absent from the radiant rapid heating furnace because the material is agitated by rolling the kiln, the heating rate is significantly lower than that in the radiant rapid heating furnace, and thus a long time is required for heating.
- Preferably, at least a portion of the soil and/or burned ash containing the heavy metals and/or organic compounds is agglomerated to form agglomerates, and the agglomerates and the residue of the soil and/or burned ash are placed on the hearth (or grate) of the radiant rapid heating furnace. Agglomeration of at least a portion of the soil and/or burned ash increases the packing density of particles of the soil and/or burned ash in the agglomerates, and thus the packing density of the whole layer of the material is also increased as compared with a case in which the whole of the soil and/or burned ash is placed on the hearth (or grate) without agglomeration, thereby further increasing the conductive heat transfer rate. Furthermore, handling after heating, such as transport or the like, is facilitated, and the agglomerates having high strength are preferably used as a roadbed and an aggregate.
- Furthermore, the soil and/or burned ash containing the heavy metals and/or organic compounds frequently contains a large amount of moisture, and is thus difficult to handle without any treatment. Therefore, at least a portion of the soil and/or burned ash is preferably dried before the agglomeration.
- Also, the soil and/or burned ash containing the heavy metals and/or organic compounds frequently contains large lumps, and thus the large lumps are preferably previously removed by a screen having a predetermined screen mesh (for example, 10 mm) for protecting an agglomerator used for agglomeration. After the large lumps are removed, only un undersize portion is agglomerated, and the resultant agglomerates and the oversize portion containing the large lumps are preferably charged in the radiant rapid heating furnace. In the large lumps, most of pollutants such as the heavy metals and/or organic compounds adhere only to the surfaces of the lumps, and thus the pollutants can easily be removed or detoxified by heating without grinding, to cause no problem.
- The radiant rapid heating furnace preferably has at least two exhaust gas discharge ports so that the exhaust gas is separately discharged from the discharge ports. Therefore, the exhaust gas containing heavy metals having different evaporation temperatures can be separately discharged, thereby facilitating a subsequent treatment of the exhaust gas and reclamation of recovered materials.
- Furthermore, a carbonaceous reducing agent and a metal oxide-containing material are preferably mixed with the soil and/or burned ash containing the heavy metals and/or organic compounds, and then the resultant mixture is charged in the heating furnace. Therefore, in heating in the heating furnace, a carbon content (C) in the carbonaceous reducing agent reacts with the metal oxide (MxOy) to activate the generation of CO gas, as shown by the following reaction formula (1):
- MxOy+zC→MxO(y-z)+zCO (1)
- As a result, reduction of the heavy metal oxides is promoted to bring the heavy metals into a volatile state, thereby accelerating evaporation removal.
- In this method, reduction can be promoted without an increase in the heating rate, and thus the heating furnace is not limited to the radiant rapid heating furnace. Thus, the method can also be applied to a conventional rotary kiln.
- At least in the second half of heating, the ambient temperature in the heating furnace (heating step) is preferably 700° C. or more. Therefore, As and Hg which evaporate at relatively low temperatures, and Pb and Cd which evaporate at higher temperatures, can be evaporated and removed from the material.
- Furthermore, in the first half of heating, the ambient temperature in the heating furnace (heating step) is preferably 700° C. or less. Therefore, low-temperature volatile metals such as As and Hg, and high-temperature volatile metals such as Pb and Cd can be separately evaporated and removed in the first half and the second half, respectively, and thus the low-temperature and high-temperature heavy metals can be separately recovered, thereby facilitating final treatment and reclamation after recovery.
- Furthermore, a rotary hearth furnace is recommended as the heating furnace. In this case, the agglomerates can be treated without pulverization, and the inside of the furnace can easily be divided, thereby facilitating separated recovery of the volatile materials removed by evaporation from the treated material.
- FIG. 1 is a drawing schematically showing a construction of an apparatus used in example 1;
- FIG. 2 is a vertical sectional view of a rotary hearth furnace used in example 1; and
- FIG. 3 is a graph showing the relation between the elapsed time from sample charging and the CO concentration of an atmosphere gas for heating each sample containing polluted soil in example 2.
- An embodiment of the present invention will be described in detail below with reference to examples.
- FIG. 1 is a drawing schematically showing a construction of an apparatus used for a method of treating heavy metals and/or organic compounds according to an embodiment of the present invention. In FIG. 1,
reference numeral 1 denotes a dryer for drying polluted soil A1 as a material to be treated;reference numeral 2, a screen for screening soil A2 dried by thedryer 1;reference numeral 3, an agglomerator for agglomerating an undersize portion A3 put through thescreen 2; andreference numeral 4, a radiant rapid heating furnace for heating agglomerates A5 produced by agglomeration by theagglomerator 3 and an oversize portion A4 put through thescreen 2. Also,reference numerals rapid heating furnace 4, andreference numerals gas discharge ports - As the polluted soil A1, soil containing pollutants such as heavy metals such as cadmium (Cd), lead (Pb), hexavalent chromium (Cr6+), arsenic (As), mercury (Hg), and the like, organochlorine compounds such as dioxines, and the like, and other organic pollutants is treated.
- When the polluted soil A1 has a high moisture content, the moisture content is preferably previously decreased to 5% by mass or less, more preferably 3% by mass or less, by drying with the
dryer 1. This is because handling is facilitated by drying. Also, screening is also facilitated by drying. Furthermore, drying before agglomeration has not only the effect of preventing the occurrence of excessive bursting even when the agglomerates A5 are charged in theheating furnace 4, but also the effect of decreasing the time required for drying the agglomerates A5 in theheating furnace 4 to improve a throughput, and saving the fuel required for drying in theheating furnace 4. Of course, thedryer 1 is unnecessary for treatment of soil A1 having a low moisture content. The drying step may be omitted according to a treatment scale, and thus the soil may be dried in the heating furnace. A treatment without agglomeration has the low probability of bursting, but drying is preferably performed to an extent which causes no trouble such as clogging in charging in the heating furnace. In a treatment without agglomeration, more preferably the density of the soil A1 is increased by compression with a press after charging in the furnace to improve a heat transfer efficiency, or a groove is, formed in the surface of the soil A1 by a scraper or the like to increase a heat receiving area. The type of thedryer 1 is not limited, and any one of a rotary dryer type, a fluidized bed dryer type, and the like may be used. However, in this example, a simple rotary dryer with rich performance is used (drying step). - Instead of drying before agglomeration, drying of the agglomerates A5 after agglomeration has the effect of suppressing bursting in the
heating furnace 4, improving productivity and decreasing fuel consumption. However, in this case, the soil containing a large amount of moisture is difficult to agglomerate. In addition, while drying can be carried out with a simple dryer such as a rotary dryer or the like before agglomeration, a relatively expensive apparatus such as a moving-bed dryer or the like is required for drying the agglomerates A5 in a stationary state after agglomeration so as to prevent bursting and powdering. - When the soil A1 (A2) contains large lumps, the large lumps are preferably removed by the
screen 2 after drying in order to protect theagglomerator 3. For example, a vibrating screen can be used as thescreen 2, and the screen mesh is 10 mm in consideration of the protection of the agglomerator and the screening efficiency. In a conventional technique, the large lumps A4 on thescreen 2 are ground, and then mixed with the undersize portion A3 or used for other applications. However, in this example, the large lumps A4 are charged in theheating furnace 4 together with the agglomerates A5 after agglomeration described below (screening step). - The undersize portion A3 from which the large lumps A4 are moved by the
screen 2 is preferably agglomerated by theagglomerator 3 to produce the agglomerates A5 having a predetermined size. The type of theagglomerator 3 is not limited, and any one of a press molding machine, an extrusion molding machine, tumbling granulators such as a dish-shaped granulator and drum granulator, an agitating granulator, a fluidized bed granulator, and the like may be used. Particularly, the press molding machine, the extrusion molding machine, or the tumbling granulator, which can produce agglomerates with a high density, is preferably used. Particularly, a press agglomerator capable of achieving a high density is recommended. Furthermore, a binder and moisture may be added to the undersize portion A3 before agglomeration according to demand. Although the shape and size of the agglomerates A5 are not limited, a pillow-shaped briquette of 39 mm×20 mm×12 mm (volume of about 6 cm3) is formed by compression molding using a press agglomerator, and used in this example (agglomeration step). - The agglomerates A5 agglomerated as described above are charged in the radiant
rapid heating furnace 4 together with the large lumps A4 remaining on thescreen 2. As the radiantrapid heating furnace 4, a rotary hearth furnace is used in this example. FIG. 2 is a vertical sectional view showing therotary hearth furnace 4 used in this example. Therotary hearth furnace 4 comprises a doughnut-like hearth 41 which horizontally rotates, aheating furnace body 42 which covers the upper portion of thehearth 41, acharger 43 for charging the agglomerates A5 and the large lumps A4 (generically named a “material A6” to be heated) onto thehearth 41, and adischarger 44 for discharging the heated material A6 (purified soil A7) after heating from thehearth 41 to the outside. The material A6 is charged onto thehearth 41 by thecharger 43 so that the thickness is about 1 to 2 times as large as the thickness (in this example, 12 mm) of the agglomerates A5. In this example, theheating furnace body 42 is divided into four zones (I, II, III, and IV zones) along the movement direction of thehearth 41, and a combustion burner (not shown) is provided in each of the zones so that the ambient temperature of each zone can be precisely controlled. In addition, the ambient temperatures (the temperature near the material A6) of the two zones (I and II zones) in the first half are 700° C. or less, and the ambient temperatures (the temperature near the material A6) of the two zones (III and IV zones) in the second half are 700 to 1250° C. Furthermore, the exhaustgas discharge ports heating furnace 4 with rotation of thehearth 41, the material A6 is heated to 700° C. or less in the two zones (I and II zones) in the first half to first remove As and Hg which evaporate at relatively low temperatures. Then, in the two zones (III and IV zones) in the second half, the material A6 is heated to the maximum temperature of about 1250° C. to remove Pb and Cd which evaporate at higher temperatures. The conceivable reason why the heavy metals can easily be evaporated only by simply heating the material A6 is that in heating the material, the organic materials contained in the soil are decomposed to generate CO gas, and thus the heavy metal oxides are converted to a volatile state by reduction, as described below with reference to example 2. In this example, fly ash containing a high concentration of As can be recovered from thedust collector 6 a connected to the exhaustgas discharge port 5 a in the first half, and fly ash containing a high concentration of Pb can be recovered from thedust collector 6 b connected to the exhaustgas discharge port 5 b in the second half. In a treatment method using a conventional rotary kiln, the inside of the furnace cannot be divided into zones from the viewpoint of structure, and thus, unlike in this example, the temperature cannot be easily precisely controlled in each zone in the furnace, and exhaust gas cannot be discharged from a plurality of positions. Furthermore, in the conventional method, the gas atmosphere in the furnace cannot be controlled to cause difficulties in evaporating heavy metals by reduction. After the material A6 passes through the IV zone in theheating furnace body 42, the material A6 is discharged as the purified soil A7 to the outside by thedischarger 44. In this example, when the retention time of the material A6 at an average ambient temperature of 1200° C. is 12 minutes, the Pb concentration of the material A6 of 160 mg/kg before heating is decreased to the Pb concentration of the purified soil A7 of 20 mg/kg after heating. Although not confirmed at present, it is thought that hexavalent chromium (Cr6+) in the material A6 is detoxified to a valence state (a metal, bivalent, or trivalent) other than a hexavalent state, which is hard to elute, and the organochlorine compounds such as dioxine are also detoxified by heating decomposition (heating step). - Another soil containing 6800 mg/kg of Pb and 59 mg/kg of As was heated by the same method as described above, and then an elusion test was carried out based on Notification No. 13 of Environment Agency. As a result, the elusion amounts of Pb and As were as low as <0.01 mg/l (quantitative lower limit) and 0.007 mg/l, respectively.
- As described above, by using the radiant rapid heating furnace as the heating furnace, the polluted soil A1 can be highly purified within a short time, as compared with the conventional rotary kiln.
- In this example, the ambient temperatures in the first half and second half of the heating furnace (heating step) are set with a boundary at 700° C. However, setting of the ambient temperatures is not limited to this, and the temperatures can be appropriately changed according to the composition of the material to be treated, and the evaporation temperature of the material to be separately recovered, etc. The first half and second half simply mean the front part and back part of the heating step, not strictly mean the first half and second half of the heating step. Therefore, the passage time (retention time) of the material to be treated in the first half of the heating furnace is not necessarily equal to that in the second half thereof. For example, when the material to be treated contains large amounts of Ag and Hg which evaporate at relatively low temperatures, the first half of the heating furnace can be set to longer than that of the second half. Conversely, when the material contains large amounts of Pb and As which evaporate at higher temperatures, the second half of the heating furnace can be set to longer than that of the first half.
- Furthermore, in this example, the ambient temperature of the heating furnace is set in the two steps on the front and back parts. However, in an operation, the temperature can be set in the three steps of the front part, an intermediate part, and the back part. In this case, for example, when the front part, the intermediate part and the back part are set to 500° C. or less, 500 to 800° C. and 800° C. or more, respectively, Hg, As and Cd, and Pb can be separately recovered in the front part, the intermediate part and the back part, respectively. The intermediate part means a part between the front and back parts.
- In order to confirm the effect of a method comprising mixing a carbonaceous reducing agent and a metal oxide-containing material with the polluted soil A1 as the material to be treated, and heating the resultant mixture, the experiment below was carried out.
- Each of single soil (Comparative Example 1), a mixture (Comparative Example 2) containing 97 parts by mass of soil and 3 parts by mass of coke power serving as the carbonaceous reducing agent, a mixture (Example 1 of this invention) containing 82 parts by mass of soil, 3 parts by mass of coke powder serving as the carbonaceous reducing agent, and 15 parts by mass of an iron ore composed of an metal oxide was formed in a pillow-like briquette sample of 39 mm×20 mm×12 mm (volume of about 6 cm3) by compression molding using a press agglomerator. Each of the samples was heated at 1200° C. (constant) in a N2 atmosphere in a small tubular furnace for about 12 minutes to measure changes in the CO concentration in the atmosphere gas with time.
- FIG. 3 shows the relationship between the elapsed time from sample charging in the tubular furnace and the CO concentration of atmosphere gas. An increase in the CO concentration is observed in the sample of single soil of Comparative Example 1, and this increase in the CO concentration is possibly due to the fact that the organic materials contained in the soil are decomposed by heating to generate CO gas. Therefore, when rapid heating of the material can be achieved, the heavy metals can be evaporated by reduction with high efficiency without the addition of a CO gas generating source to the material to be treated, like in the present invention. In the sample of Comparative Example 2 containing the soil and the coke powder, the CO concentration is less increased as compared with Comparative Example 1. Therefore, oxides of the heavy metals as the pollutants in a portion in direct contact with the coke powder are reduced, while reduction does not sufficiently proceeds in other portions out of direct contact with the coke powder. On the other hand, in the sample of Example 1 of this invention containing the soil, the coke powder and the iron ore, the CO concentration of the atmosphere gas is significantly increased, as compared with Comparative Examples 1 and 2. It is thus confirmed that a large amount of CO gas is generated. Therefore, reduction of the heavy metal oxides through the gas is promoted to permit removal of the heavy metals by reduction evaporation, and detoxification by insolubilization with high efficiency.
- The briquette of Example 1 of this invention has a crushing strength of 530 N after heating, and is thus suitable as a roadbed, an aggregate, and the like.
- Although, in this example, the material to be treated is soil, burned ash also can be treated as a material containing heavy metals and/or organic compounds to produce the same effect as described below in Example 3.
- Burned ash is heated by using the same apparatus as that used Example 1. Each of two samples including single burned ash (Example 2 of this invention), and a mixture (Example 3 of this invention) containing 82 parts by mass of burned ash, 3 parts by mass of coke powder serving as a carbonaceous reducing agent, and 15 parts by mass of iron ore composed of a metal oxide was molded in a tablet of 20 mm in diameter×15 mm in length, and then heated at an average ambient temperature of 1200° C. in a rotary hearth furnace for a retention time of 12 minutes. Table 1 shows the Pb concentrations of the tablet before and after heating, and crushing strength of the tablet after heating. Table 1 indicates that the heavy metals of the burned ash can be removed by treatment.
TABLE 1 Crushing Pb concentration Pb concentration strength after before heating after heating heating (mg/kg) (mg/kg) (N/tablet) Example 2 of 530 120 590 this invention Example 3 of 740 50 Unmeasured this invention - Besides the iron ore, iron-making dust containing an iron oxide, such as blast furnace dust, converter dust, electric furnace dust, mill scales, mill sludge, pickling sludge, sintering dust, and the like, nonferrous oxides such as nickel oxide, manganese oxide, and the like may be used as the metal oxide. Besides the coke powder, coal, petroleum coke, waste carbides, RDF carbides, carbonaceous sludge, scrap tires, blast furnace dust, and the like may be used as the carbonaceous reducing agent. Particularly, the blast furnace dust is preferred because it contains an ion oxide (metal oxide) and a carbon content (carbonaceous reducing agent).
- As be seen from the above description, according to the present invention, heavy metals and/or organic compounds contained in polluted soil and/or burned ash can be sufficiently removed or detoxified with a high efficiency, as compared with a conventional method. Also, the apparatus used can be simplified to decrease apparatus cost and treatment cost.
Claims (7)
1. A method of treating a heavy metal and/or organic compound comprising a heating step of heating a material containing a heavy metal and/or organic compound, in a radiant rapid heating furnace to purify the material.
2. A method of treating a heavy metal and/or organic compound comprising an agglomeration step of agglomerating at least a portion of a material containing a heavy metal and/or organic compound, to form agglomerates, and a heating step of heating the agglomerates and the unagglomerated residue of the material in a radiant rapid heating furnace to purify the material.
3. A method of treating a heavy metal and/or organic compound according to claim 2 , further comprising a screening step of screening the material to separate the material into an oversize portion and an undersize portion before the agglomeration step, the undersize portion being supplied to the agglomeration step, and the oversize portion being supplied to the heating step without the agglomeration step.
4. A method of treating a heavy metal and/or organic compound comprising a mixing step of mixing a carbonaceous reducing agent and a metal oxide-containing material with a material containing a heavy metal and/or organic compound, and a heating step of heating the resultant mixture in a heating furnace to purify the material.
5. A method of treating a heavy metal and/or organic compound according to claim 2 , wherein the material is heated at an ambient temperature of 700° C. or more at least in the second half of the heating step.
6. A method of treating a heavy metal and/or organic compound according to claim 5 , wherein the material is heated at an ambient temperature of 700° C. or less in the first half of the heating step.
7. A method of treating a heavy metal and/or organic compound according to claim 2 , wherein the radiant rapid heating furnace is a rotary hearth furnace.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002-114884 | 2002-04-17 | ||
JP2002114884 | 2002-04-17 | ||
JP2002238371A JP2004000882A (en) | 2002-04-17 | 2002-08-19 | Method for treating heavy metal and/or organic compound |
JP2002-238371 | 2002-08-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
US20030196517A1 true US20030196517A1 (en) | 2003-10-23 |
Family
ID=28677652
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/396,516 Abandoned US20030196517A1 (en) | 2002-04-17 | 2003-03-26 | Method of treating heavy metal and/or organic compound |
Country Status (5)
Country | Link |
---|---|
US (1) | US20030196517A1 (en) |
EP (1) | EP1354646A1 (en) |
JP (1) | JP2004000882A (en) |
KR (1) | KR20030082476A (en) |
TW (1) | TW200404101A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080216346A1 (en) * | 2005-07-25 | 2008-09-11 | Flo-Dry Engineering Limited | Method of Drying Pasty Materials and/or Apparatus for Drying Pasty Materials |
US20080261477A1 (en) * | 2006-11-15 | 2008-10-23 | Semiconductor Energy Laboratory Co., Ltd. | Method for collecting metal |
WO2013101838A1 (en) * | 2011-12-27 | 2013-07-04 | Tronox Llc | Methods of producing a titanium dioxide pigment and improving the processability of titanium dioxide pigment particles |
US20180340240A1 (en) * | 2017-05-26 | 2018-11-29 | Novelis Inc. | System and method for briquetting cyclone dust from decoating systems |
US11079105B2 (en) * | 2016-11-07 | 2021-08-03 | Reset S.R.L. | Woody biomass cogeneration plant for the continuous production of heat and electricity |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2005305305A (en) * | 2004-04-21 | 2005-11-04 | Kobe Steel Ltd | Cleaning treatment method for arsenic containing contaminated soil and its apparatus |
JP2007069178A (en) * | 2005-09-09 | 2007-03-22 | Sanyu Plant Service Kk | Dechlorination method for waste incineration ash |
TWI483918B (en) * | 2008-03-10 | 2015-05-11 | Taiheiyo Cement Corp | Cement manufacturing method |
JP5684001B2 (en) * | 2011-03-01 | 2015-03-11 | 中外炉工業株式会社 | Powder continuous firing equipment |
JP6299942B2 (en) * | 2013-02-07 | 2018-03-28 | 富士電機株式会社 | Contaminated soil treatment system and contaminated soil treatment method |
JP2019019346A (en) * | 2017-07-12 | 2019-02-07 | Dowaエコシステム株式会社 | Recovery method of noble metal from incineration ash |
CN112619019B (en) * | 2020-12-18 | 2021-11-02 | 中国民航大学 | Method for preparing rare earth element composite high-efficiency superfine powder fire extinguishing agent by using elution crystallization method |
CN114798715B (en) * | 2022-07-01 | 2022-09-16 | 山西交控生态环境股份有限公司 | Soil remediation equipment and using method thereof |
Citations (26)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4667609A (en) * | 1986-09-08 | 1987-05-26 | Robert Hardison | Apparatus and method for treatment of soil contaminated with hydrocarbons |
US4802424A (en) * | 1988-05-26 | 1989-02-07 | Nass, Inc. | Furnace for hazardous materials |
US5612008A (en) * | 1995-07-27 | 1997-03-18 | Kirk; Donald W. | Process for treating solid waste containing volatilizable inorganic contaminants |
US5865875A (en) * | 1995-08-25 | 1999-02-02 | Maumee Research & Engineering, Inc. | Process for treating metal oxide fines |
US5885521A (en) * | 1994-12-16 | 1999-03-23 | Midrex International B.V. Rotterdam, Zurich Branch | Apparatus for rapid reduction of iron oxide in a rotary hearth furnace |
US5989019A (en) * | 1996-08-15 | 1999-11-23 | Kabushiki Kaisha Kobe Seiko Sho | Direct reduction method and rotary hearth furnace |
US6063156A (en) * | 1996-12-27 | 2000-05-16 | Kabushiki Kaisha Kobe Seiko Sho | Production method of metallic iron |
US6129777A (en) * | 1998-03-24 | 2000-10-10 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing reduced iron agglomerates |
US6149709A (en) * | 1997-09-01 | 2000-11-21 | Kabushiki Kaisha Kobe Seiko Sho | Method of making iron and steel |
US6152983A (en) * | 1997-12-18 | 2000-11-28 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing reduced iron pellets |
US6241803B1 (en) * | 1999-01-20 | 2001-06-05 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Method for manufacturing reduced iron pellets |
US6251161B1 (en) * | 1998-08-27 | 2001-06-26 | Kabushiki Kaisha Kobe Sieko Sho (Kobe Steel, Ltd.) | Method for operating moving hearth reducing furnace |
US6254665B1 (en) * | 1998-04-11 | 2001-07-03 | Kobe Steel, Ltd. | Method for producing reduced iron agglomerates |
US6258149B1 (en) * | 1998-03-23 | 2001-07-10 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing reduced iron agglomerates |
US6296479B1 (en) * | 1999-05-06 | 2001-10-02 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Direct reduction method and rotary hearth furnace |
US6319302B1 (en) * | 1999-01-18 | 2001-11-20 | Kobe Steel, Ltd. | Method for manufacturing reduced iron agglomerates and apparatus there for |
US6334883B1 (en) * | 1998-11-24 | 2002-01-01 | Kobe Steel, Ltd. | Pellets incorporated with carbonaceous material and method of producing reduced iron |
US6368379B1 (en) * | 1999-10-15 | 2002-04-09 | Kobe Steel, Ltd. | Apparatus and method for producing reduced metal |
US6413295B2 (en) * | 1998-11-12 | 2002-07-02 | Midrex International B.V. Rotterdam, Zurich Branch | Iron production method of operation in a rotary hearth furnace and improved furnace apparatus |
US6500381B1 (en) * | 1999-08-30 | 2002-12-31 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Method and apparatus for supplying granular raw material for reduced iron |
US6503289B2 (en) * | 2000-03-30 | 2003-01-07 | Midrex International B.V. Zurich Branch | Process for manufacturing molten metal iron |
US6511316B2 (en) * | 2000-06-29 | 2003-01-28 | Kabushiki Kaisha Kobe Seiko Sho | Method of operating a rotary hearth furnace |
US6517770B1 (en) * | 2000-03-30 | 2003-02-11 | Kobe Steel, Ltd. | Temperature control device and temperature control method for high-temperature exhaust gas |
US6521171B2 (en) * | 2000-05-19 | 2003-02-18 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Processing method for high-temperature exhaust gas |
US6569223B2 (en) * | 2000-03-31 | 2003-05-27 | Midrex International B.V. Zurich Branch | Method of manufacturing molten metal iron |
US6579505B2 (en) * | 1997-10-30 | 2003-06-17 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing iron oxide pellets |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO1996005002A1 (en) * | 1994-08-15 | 1996-02-22 | Shinmaywa Industries, Ltd. | Heavy metal-containing waste treating process and apparatus |
JPH1080675A (en) * | 1997-08-18 | 1998-03-31 | Mitsui Eng & Shipbuild Co Ltd | Treatment of incineration ash from trash incinerator and device therefor |
JP2001259607A (en) * | 2000-03-17 | 2001-09-25 | Sumitomo Heavy Ind Ltd | Treatment method and apparatus for heavy metal or organic chlorine compound |
-
2002
- 2002-08-19 JP JP2002238371A patent/JP2004000882A/en active Pending
-
2003
- 2003-03-24 TW TW092106438A patent/TW200404101A/en unknown
- 2003-03-25 EP EP03006754A patent/EP1354646A1/en not_active Withdrawn
- 2003-03-26 US US10/396,516 patent/US20030196517A1/en not_active Abandoned
- 2003-04-16 KR KR10-2003-0024107A patent/KR20030082476A/en not_active Application Discontinuation
Patent Citations (27)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4667609A (en) * | 1986-09-08 | 1987-05-26 | Robert Hardison | Apparatus and method for treatment of soil contaminated with hydrocarbons |
US4802424A (en) * | 1988-05-26 | 1989-02-07 | Nass, Inc. | Furnace for hazardous materials |
US5885521A (en) * | 1994-12-16 | 1999-03-23 | Midrex International B.V. Rotterdam, Zurich Branch | Apparatus for rapid reduction of iron oxide in a rotary hearth furnace |
US5612008A (en) * | 1995-07-27 | 1997-03-18 | Kirk; Donald W. | Process for treating solid waste containing volatilizable inorganic contaminants |
US5865875A (en) * | 1995-08-25 | 1999-02-02 | Maumee Research & Engineering, Inc. | Process for treating metal oxide fines |
US5989019A (en) * | 1996-08-15 | 1999-11-23 | Kabushiki Kaisha Kobe Seiko Sho | Direct reduction method and rotary hearth furnace |
US6063156A (en) * | 1996-12-27 | 2000-05-16 | Kabushiki Kaisha Kobe Seiko Sho | Production method of metallic iron |
US6149709A (en) * | 1997-09-01 | 2000-11-21 | Kabushiki Kaisha Kobe Seiko Sho | Method of making iron and steel |
US6579505B2 (en) * | 1997-10-30 | 2003-06-17 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing iron oxide pellets |
US6152983A (en) * | 1997-12-18 | 2000-11-28 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing reduced iron pellets |
US6302938B1 (en) * | 1997-12-18 | 2001-10-16 | Kabushiki Kaisha Kobe Seiko Sho | Reduced pellets |
US6258149B1 (en) * | 1998-03-23 | 2001-07-10 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing reduced iron agglomerates |
US6129777A (en) * | 1998-03-24 | 2000-10-10 | Kabushiki Kaisha Kobe Seiko Sho | Method of producing reduced iron agglomerates |
US6254665B1 (en) * | 1998-04-11 | 2001-07-03 | Kobe Steel, Ltd. | Method for producing reduced iron agglomerates |
US6251161B1 (en) * | 1998-08-27 | 2001-06-26 | Kabushiki Kaisha Kobe Sieko Sho (Kobe Steel, Ltd.) | Method for operating moving hearth reducing furnace |
US6413295B2 (en) * | 1998-11-12 | 2002-07-02 | Midrex International B.V. Rotterdam, Zurich Branch | Iron production method of operation in a rotary hearth furnace and improved furnace apparatus |
US6334883B1 (en) * | 1998-11-24 | 2002-01-01 | Kobe Steel, Ltd. | Pellets incorporated with carbonaceous material and method of producing reduced iron |
US6319302B1 (en) * | 1999-01-18 | 2001-11-20 | Kobe Steel, Ltd. | Method for manufacturing reduced iron agglomerates and apparatus there for |
US6241803B1 (en) * | 1999-01-20 | 2001-06-05 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Method for manufacturing reduced iron pellets |
US6296479B1 (en) * | 1999-05-06 | 2001-10-02 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Direct reduction method and rotary hearth furnace |
US6500381B1 (en) * | 1999-08-30 | 2002-12-31 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Method and apparatus for supplying granular raw material for reduced iron |
US6368379B1 (en) * | 1999-10-15 | 2002-04-09 | Kobe Steel, Ltd. | Apparatus and method for producing reduced metal |
US6503289B2 (en) * | 2000-03-30 | 2003-01-07 | Midrex International B.V. Zurich Branch | Process for manufacturing molten metal iron |
US6517770B1 (en) * | 2000-03-30 | 2003-02-11 | Kobe Steel, Ltd. | Temperature control device and temperature control method for high-temperature exhaust gas |
US6569223B2 (en) * | 2000-03-31 | 2003-05-27 | Midrex International B.V. Zurich Branch | Method of manufacturing molten metal iron |
US6521171B2 (en) * | 2000-05-19 | 2003-02-18 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Processing method for high-temperature exhaust gas |
US6511316B2 (en) * | 2000-06-29 | 2003-01-28 | Kabushiki Kaisha Kobe Seiko Sho | Method of operating a rotary hearth furnace |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20080216346A1 (en) * | 2005-07-25 | 2008-09-11 | Flo-Dry Engineering Limited | Method of Drying Pasty Materials and/or Apparatus for Drying Pasty Materials |
US20080261477A1 (en) * | 2006-11-15 | 2008-10-23 | Semiconductor Energy Laboratory Co., Ltd. | Method for collecting metal |
US8128727B2 (en) | 2006-11-15 | 2012-03-06 | Semiconductor Energy Laboratory Co., Ltd. | Method for collecting metal |
US8435793B2 (en) | 2006-11-15 | 2013-05-07 | Semiconductor Energy LaboratoryCo., Ltd. | Method for collecting metal |
WO2013101838A1 (en) * | 2011-12-27 | 2013-07-04 | Tronox Llc | Methods of producing a titanium dioxide pigment and improving the processability of titanium dioxide pigment particles |
US8663518B2 (en) | 2011-12-27 | 2014-03-04 | Tronox Llc | Methods of producing a titanium dioxide pigment and improving the processability of titanium dioxide pigment particles |
TWI492901B (en) * | 2011-12-27 | 2015-07-21 | Tronox Llc | Methods of producing a titanium dioxide pigment and improving the processability of titanium dioxide pigment particles |
US11079105B2 (en) * | 2016-11-07 | 2021-08-03 | Reset S.R.L. | Woody biomass cogeneration plant for the continuous production of heat and electricity |
US20180340240A1 (en) * | 2017-05-26 | 2018-11-29 | Novelis Inc. | System and method for briquetting cyclone dust from decoating systems |
Also Published As
Publication number | Publication date |
---|---|
EP1354646A1 (en) | 2003-10-22 |
KR20030082476A (en) | 2003-10-22 |
JP2004000882A (en) | 2004-01-08 |
TW200404101A (en) | 2004-03-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
KR100411832B1 (en) | Process of recovering elemental iron from an iron-bearing material | |
US20030196517A1 (en) | Method of treating heavy metal and/or organic compound | |
CN107159678A (en) | Agglomeration for iron mine collaboration processing garbage flying ash process bioxin control methods | |
EP1408124B1 (en) | Method for producing feed material for molten metal production and method for producing molten metal | |
EP1165845B1 (en) | Method and apparatus for removing undesirable metals from iron-containing materials | |
JP3635256B2 (en) | Reduction method of iron oxide | |
JP3339638B2 (en) | Method and apparatus for removing lead and zinc from casting dust | |
US6797034B2 (en) | Method of producing reduced metals and apparatus for reducing metal oxides | |
KR100703112B1 (en) | Method for reduction treatment of metal oxide or ironmaking waste, and method for concentration and/or recovery of zinc and/or lead | |
CA1239020A (en) | Method for recovering zinc from substances containing a zinc compound | |
JP2003213312A (en) | Method for manufacturing metallic iron | |
CN115325551A (en) | Method for cooperatively treating arsenic-containing polluted soil by rotary kiln | |
JP2015196896A (en) | Method of regenerating oil-containing waste to useful material | |
JPH06330198A (en) | Method for recovering zinc in dust | |
JPH1112619A (en) | Production of reduced iron | |
Cavaliere et al. | Sintering: most efficient technologies for greenhouse emissions abatement | |
JP4177995B2 (en) | Method for reducing wet dust | |
JP2003129140A (en) | Method for manufacturing molded article designed for reducing rotary hearth | |
JPH11197629A (en) | Treating method for incinerated fly ash | |
JP3723521B2 (en) | Reduced iron manufacturing method and crude zinc oxide manufacturing method using blast furnace wet dust | |
JPH0477054B2 (en) | ||
JP2002167613A (en) | Method for repairing rotary furnace hearth for reduced iron | |
CN115947550A (en) | Method for cooperatively treating arsenic-containing waste residues by using rotary kiln | |
Sloop | EAF Dust recycling at Ameristeel | |
JP2003190926A (en) | Method for treating carbon-containing waste and treatment equipment therefor |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD), Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HARADA, TAKAO;MICHISHITA, HARUYASU;TANAKA, HIDETOSHI;AND OTHERS;REEL/FRAME:014193/0743 Effective date: 20030310 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |