WO2000051939A1 - Microsilice a densite volumique etroitement controlee, procede et appareil de production associes - Google Patents

Microsilice a densite volumique etroitement controlee, procede et appareil de production associes Download PDF

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Publication number
WO2000051939A1
WO2000051939A1 PCT/NO2000/000058 NO0000058W WO0051939A1 WO 2000051939 A1 WO2000051939 A1 WO 2000051939A1 NO 0000058 W NO0000058 W NO 0000058W WO 0051939 A1 WO0051939 A1 WO 0051939A1
Authority
WO
WIPO (PCT)
Prior art keywords
microsilica
enclosed space
weight
bulk density
recorded
Prior art date
Application number
PCT/NO2000/000058
Other languages
English (en)
Inventor
Kunio Yamamoto
Ottar Laerum
Egil Messelt
Svein Gitlestad
Original Assignee
Elkem Asa
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Elkem Asa filed Critical Elkem Asa
Priority to AU28340/00A priority Critical patent/AU2834000A/en
Publication of WO2000051939A1 publication Critical patent/WO2000051939A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B18/04—Waste materials; Refuse
    • C04B18/14—Waste materials; Refuse from metallurgical processes
    • C04B18/146—Silica fume
    • C04B18/147—Conditioning
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/10—Solid density
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

  • the present invention relates to the production of microsilica with a closely controlled bulk weight.
  • silicon dioxide In the production of materials having a high silicon content such as silicon, ferrosilicon, silicon carbide and other silicon-containing alloys in smelting furnaces, there is generated a substantial amount of silicon monoxide which is converted to silicon dioxide.
  • a similar form of silica is also retrieved from the production of fused oxides such as mullite, zirconia and zircon mullite.
  • the silicon dioxide is in a very fine form and it is normally referred to as microsilica.
  • microsilica Because of the very light nature of microsilica, it does not remain in the smelting process but rather is carried up with the off gases from the smelting process into the furnace flue. Because escaping dust would be an environmental pollutant, it is necessary that the dust be recovered from the smoke from the smelting furnace. Typical dry methods employed in this regard involve bag house filters and the like.
  • microsilica recovered which has a typical weight by volume of 150 - 300 kg/m 3 must then be disposed of.
  • Various utilities for microsilica are known such as in refractory ceramics, as a filler in concrete and rubber and as an anti-caking material for fertilizers. When the material is used in these particular applications, it is, of course, usually necessary to transport it to the end user. Because the microsilica is so light and powdery, transportation costs are inordinately high. From US patent No.
  • 4,126,424 it is known a reversible waterless process for increasing the bulk density of microsilica comprising charging microsilica to an enclosed space and injecting pressurized air from below into the microsilica at a flow rate that causes fluidization for a period of at least five hours in a batch process.
  • the main object of the present invention is to provide a continuous method for producing microsilica with a closely controlled bulk density.
  • the present invention relates to a process for production of microsilica with a closely controlled bulk density where microsilica is continuously or substantially continuously supplied to and continuously or substantially continously discharged from an enclosed space and where pressurized air is injected from below into the microsilica contained in the enclosed space at a flow rate that causes fluidization of the microsilica, said method being characterized in that the weight of microsilica in the enclosed space and the level of microsilica in the enclosed space are continuously recorded and that the bulk density of microsilica in the enclosed space is calculated based on the recorded weight of microsilica in the enclosed space and the recorded level of microsilica in the enclosed space, that the weight of microsilica charged to the enclosed space is recorded and that the discharge of compacted microsilica from the enclosed space is regulated in order to maintain a preset bulk weight of microsilica in the enclosed space.
  • the microsilica is discharged from the enclosed space when the bulk weight of the microsilica in the enclosed space is controlled in the range from 425 kg/m 3 to not more than 550 kg/m 3 .
  • microsilica is charged to the top part of the enclosed space and is discharged at or near the bottom of the enclosed space.
  • the weight of microsilica in the enclosed space is recorded by placing the enclosed space on weighing cells, and by weighing the enclosed space when its empty, whereby the weight of microsilica in the enclosed space easily can be recorded as microsilica is being charged to the enclosed space.
  • the level of microsilica in the enclosed space is recorded in conventional way by for instance by use of ultrasonic sound measurement devices.
  • microsilica When starting the process microsilica is charged to the enclosed space and the flow of compressed air through the fluidizing bottom is started.
  • the bulk weight of the microsilica is then monitored by recording the weight of microsilica in the enclosed space and the level of microsilica in the enclosed space.
  • the bulk weight of the microsilica in the enclosed spaced has reached a predetermined value one starts to continuously or substantially continuously discharge microsilica from the enclosed space and at the same time starts to continuously or substantially continuously charge further microsilica to the enclosed space where the weight of discharged microsilica over a certain time interval is equal to the weight of microsilica supplied to the enclosed space.
  • Figure 1 shows a process outline for the process according to the present invention.
  • FIG. 1 there is shown a silo 1 having a fluidizing bottom 2 and means 3 for supply of fluidizing air to the fluidizing bottom 2.
  • a part A of the wall of the silo is removed in the drawing.
  • the silo 1 is placed on load cells 4 in order to record the weight of the silo.
  • the signals from the load cells 4 are registered in a computer 5.
  • On the top of the silo 1 there is arranged a level indicator 6 for recording the level of microsilica in the silo 1.
  • the level indicator is preferably an ultrasonic sound measurement device.
  • the signals from the level indicator are also registered in the computer 5. Based on signals from the weighing cells 4 and the level indicator 6, the bulk density of the microsilica in the silo is calculated at short intervals.
  • Untreated microsilica having a low bulk density is charged to the silo 1 through an inlet opening 7.
  • the weight on microsilica charged to the silo 1 is recorded in the computer 5.
  • Microsilica having a controlled bulk density is discharged from the silo 1 through a discharge opening 8.
  • the weight of microsilica discharged through the discharge opening 8 is recorded in the computer 5.
  • the silo 1 is on its top equipped with a filter 9 and an outlet opening 10 for air from the silo 1.
  • the microsilica removed from the air in the filter 9 is returned to the silo 1.
  • air is supplied through the air supply pipe 3 to the fluidizing bottom 2 and microsilica is charged to the silo through the microsilica inlet opening 7 until a fluidized bed of microsilica having a preset level 11 is established in the silo.
  • the recording of the weight of the microsilica and the level of microsilica in the silo 1 is started and the bulk density is then calculated and monitored by the computer 5. In an initial period microsilica is not discharged until the calculated bulk density of microsilica in the silo 1 has reached a predetermined value.
  • microsilica When this predetermined value for microsilica is reached, discharging of the microsilica with a controlled bulk density through the discharge opening 8 is started and the weight of discharged microsilica is recorded. At the same time further charging of untreated microsilica is started through the microsilica inlet opening 7.
  • the weight of microsilica charged to the silo is kept at about the same level as the weight of microsilica discharged from the silo. If the calculated bulk weight of microsilica during discharging of microsilica tends to decrease the discharging rate of microsilica is reduced as well as the charging rate of untreated microsilica. If the calculated bulk weight of microsilica during discharging tends to increase the discharging rate of microsilica is increased as well as the charging rate of microsilica. In this way and by controlled variations in the flow of fluidizing air, it is obtained a steady state process with continuous or substantially continuous charging of untreated microsilica and simultanously or substantially continuous discharging of microsilica having a predetermined closely controlled bulk density.
  • Microsilica obtained from the production of silicon in an electric smelting furnace having a bulk density of 250 kg/m 3 was charged to the silo 1 shown in figure 1 through the inlet opening 7.
  • pressurized air at room temperature was supplied to the fluidizing bottom 2 through the air supply means 3.
  • the flow of air was regulated in order to fluidize the microsilica in the silo.
  • a starting amount of microsilica was supplied to the silo 1 to obtain a level of microsilica shown at 11.
  • the weight of the silo 1 was measured by means of the weighing cells 4 before supply of microsilica and the measuring of the weight of the silo was continued throughout the test.
  • the level of microsilica was measured by means of the level indicater 6 and when the level 11 of microsilica was lowered further microsilica was supplied to the silo 1.
  • the bulk weight of the microsilica in the silo was calculated in the computer 5 based on the recorded weight of microsilica and the level 11 of microsilica. This calculation was made at very short time intervals. In this example it was the aim to produce microsilica with a bulk density of 450 kg/m 3 . Thus when the bulk density of the microsilica in the silo 1 had reached this value, discharging of treated microsilica having a bulk density of 450 kg/m 3 was started through the discharge opening 8.
  • the weight of discharged microsilica was continuously recorded and a weight of microsilica corresponding to the weight of discharged microsilica was charged through the inlet opening 7.
  • the amount of microsilica was discharged according to the calculated bulk weight of microsilica in the silo 1 , such that the bulk weight in the silo 1 was kept as close to 450 kg/m 3 as possible. It was obtained a steady state operation to continuously produce microsilica having a bulk density of 450 kg/m 3 .
  • microsilica having bulk density in the range from 425 kg/m 3 to not more than 550 kg/m 3 .
  • microsilica having the bulk density in the specific range the microsilica can be easily dispersion added homogeneously to the mixtures for various products, and it is possible to reduce the transportation and storing costs of the microsilica.

Abstract

La présente invention concerne une microsilice présentant une densité volumique étroitement contrôlée comprise entre 425 kg/m3 et au maximum 550 kg/m3. L'invention concerne aussi un procédé de production de microsilice à densité volumique étroitement contrôlée dans lequel la microsilice est chargée et déchargée, de manière continue ou sensiblement continue, d'un espace clos dans lequel de l'air sous pression est injecté sous la microsilice à un débit qui permet de fluidiser la microsilice. Le poids et le niveau de microsilice dans l'espace clos sont enregistrés de manière continue et la densité volumique de la microsilice est calculée sur la base des poids et des niveaux de microsilice enregistrés. Le poids de microsilice contenu dans l'espace clos est enregistré et la sortie de l'espace clos de microsilice présentant une densité volumique prédéterminée est régulée afin de maintenir un poids volumique préétabli. Enfin, l'invention concerne un four à lit fluidisé destiné à la production de microsilice présentant une densité volumique étroitement contrôlée.
PCT/NO2000/000058 1999-03-04 2000-02-17 Microsilice a densite volumique etroitement controlee, procede et appareil de production associes WO2000051939A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU28340/00A AU2834000A (en) 1999-03-04 2000-02-17 Microsilica with a closely controlled bulk density, method and apparatus for production thereof

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO19991083A NO314542B1 (no) 1999-03-04 1999-03-04 Fremgangsmåte for fremstilling av microsilica med kontrollert bulktetthet
NO19991083 1999-03-04

Publications (1)

Publication Number Publication Date
WO2000051939A1 true WO2000051939A1 (fr) 2000-09-08

Family

ID=19903052

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO2000/000058 WO2000051939A1 (fr) 1999-03-04 2000-02-17 Microsilice a densite volumique etroitement controlee, procede et appareil de production associes

Country Status (4)

Country Link
AU (1) AU2834000A (fr)
EG (1) EG22637A (fr)
NO (1) NO314542B1 (fr)
WO (1) WO2000051939A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1405705A1 (fr) * 2001-06-20 2004-04-07 Obayashi Corporation Equipement de pesage de constituant de beton
US7537653B2 (en) 2005-01-31 2009-05-26 Gcc Technology And Processes S.A. Microsilica materials with improved pozzolanic activity

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4126424A (en) * 1976-04-27 1978-11-21 Elkem-Spigerverket A/S Method of compacting silica dust
US5160470A (en) * 1992-05-20 1992-11-03 Dow Corning Corporation Method for compacting silica fume
FR2753110A1 (fr) * 1996-09-12 1998-03-13 Pechiney Electrometallurgie Poudre dense a base de poussieres de silice

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4126424A (en) * 1976-04-27 1978-11-21 Elkem-Spigerverket A/S Method of compacting silica dust
US5160470A (en) * 1992-05-20 1992-11-03 Dow Corning Corporation Method for compacting silica fume
FR2753110A1 (fr) * 1996-09-12 1998-03-13 Pechiney Electrometallurgie Poudre dense a base de poussieres de silice

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1405705A1 (fr) * 2001-06-20 2004-04-07 Obayashi Corporation Equipement de pesage de constituant de beton
EP1405705A4 (fr) * 2001-06-20 2006-11-29 Ohbayashi Corp Equipement de pesage de constituant de beton
US7537653B2 (en) 2005-01-31 2009-05-26 Gcc Technology And Processes S.A. Microsilica materials with improved pozzolanic activity

Also Published As

Publication number Publication date
EG22637A (en) 2003-05-31
NO991083L (no) 2000-09-05
NO314542B1 (no) 2003-04-07
AU2834000A (en) 2000-09-21
NO991083D0 (no) 1999-03-04

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