WO1996018454A1 - Method and apparatus for slurrying pulverized materials into a liquid - Google Patents
Method and apparatus for slurrying pulverized materials into a liquid Download PDFInfo
- Publication number
- WO1996018454A1 WO1996018454A1 PCT/FI1995/000675 FI9500675W WO9618454A1 WO 1996018454 A1 WO1996018454 A1 WO 1996018454A1 FI 9500675 W FI9500675 W FI 9500675W WO 9618454 A1 WO9618454 A1 WO 9618454A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- mixer
- solids
- slurry
- liquid
- mixing
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/50—Mixing liquids with solids
- B01F23/53—Mixing liquids with solids using driven stirrers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/50—Mixing liquids with solids
- B01F23/59—Mixing systems, i.e. flow charts or diagrams
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
- B01F27/27—Mixers with stator-rotor systems, e.g. with intermeshing teeth or cylinders or having orifices
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F2025/91—Direction of flow or arrangement of feed and discharge openings
- B01F2025/912—Radial flow
Definitions
- the present invention relates to a method according to the preamble of claim 1 for the preparation of slurries with high solids content and high viscosity from differ ⁇ ent kinds of pulverized materials and liquids.
- the invention also concerns an apparatus according to the preamble of claim 11 for implementing the method.
- Paper industry uses large quantities of various coating materials that are applied on the paper web to achieve desired properties of the sheet.
- Such coating formulas comprise water slurries of pulverized pigments, fillers and other additives. While similar mixtures are also used in other industries, the prepared quantities generally remain much smaller than in the paper industry.
- the solids content of the slurry is high, and correspondingly, the water con ⁇ tent low.
- the slurry must occasionally be transported over a longer distance in the paper mill, whereby high water content increases the batch volume of the slurry, and resultingly, the workload in its transportation.
- paper coating typically aims at applying a maximum coat weight on the web using one applicator unit only.
- the applied wet coat must be dried prior to further processing of the sheet, whereby the evaporation of excess water consumes abundant energy and is difficult at current web speeds if the web is allowed to wet excessively.
- the drying speed becomes a limiting factor in the con ⁇ struction of high-speed machines requiring a longer path in the dryer, whereby the paper machine becomes longer.
- the solids content of the coating affects many aspects of paper machine design and paper manufacture.
- dispersion into a slurry is carried out in a dissolver-type mixer in which a rotating disk resembling a circular saw blade imposes large shearing forces local ⁇ ly in the slurry causing wetting of the pigment particles and adherence of dispersing agents on the surface of the particles.
- the coating mix may consist of, e.g., kaolin, talc, titanium oxide or modified forms or combinations thereof.
- the slurry is made up of several agents to achieve desired properties of the mixture.
- a mixer of improved degree of slurrying and specific energy efficiency is described in, e.g., FI Pat. No. 91,602.
- the apparatus disclosed in this publication comprises a pin- mill-type mixer equipped with special-design agitating blades that impose extremely high shearing forces on the mix to be agitated.
- the mixing action involves difficulties which become more serious when the viscosity of the mix increases.
- the degree of mixing efficiency can be estimated by means of a cor ⁇ rection factor K (K > l) of the mixing time.
- the correc ⁇ tion factor can be determined from formula ( 1 ) obtained by experimental methods:
- V is the ratio of viscosities of liquids being mixed, and ratio of densities of liquids is expressed by the ratio in parentheses.
- a typical dissolver mixer slurries, e.g., kaolin or calcined kaolin down to 50 % solids in about 45 min in a batch of 6 - 7 m 3 . Then, the mixer power input is approx. 250 k making the specific energy consumption to be at approx. 22 k h per ton slurry. Not- withstanding the long slurrying time, the raw slurry must be screened to remove unbroken lumps.
- FI Pat. No. 91,602 describes a partial solution to the slurrying problems.
- the shearing forces are made so large as to achieve good breaking-up of even the putty-like lumps.
- a disadvantage of cited embodiment is in that the shearing forces and the statistical distribution thereof are not necessarily sufficient to provide a homogeneous slurry when the water and the pulverized or ground material are fed directly into the slurrying apparatus.
- Another problem in such an apparatus is related to consistent dosing of the materials to be mixed, because herein the amounts to be mixed simultaneously are small and the mixing time is short.
- This concept was tested by slurrying a portion of cal- cined kaolin up to approx. 40 - 45 % solids content in a first step using an apparatus resembling a pin mill. In a second step, into this slurry of already relatively high density and high viscosity was dispersed more kaolin until a 52 % solids slurry was obtained. It was found that this two-step arrangement results in easy preslurry- ing and final slurrying as the two-step method can avoid large density and viscosity differences in the slurrying action.
- the goal of the invention is achieved by virtue of per ⁇ forming the preparation of the slurry in at least two steps so that the first step comprises preparing a mix ⁇ ture having a solids content lower than that of the final product, and to this slurry is mixed in at least one subsequent step more solids until the desired solids content of the slurry is attained.
- the slurrying is performed using a slurrying apparatus resembling a pin mill in which the mixture is slurried with a portion of the solids up to such a solids content that corresponds to approx. 70 - 85 % of the desired final solids content and the rest of the solids is slurried into this high- density, high-consistency slurry of already high homo ⁇ geneity.
- the second slurrying step is advantageously carried out using again a similar pin mill apparatus.
- the pin mill used in the first step has stator vanes and rotor vanes
- the pin mill of the second step has the pins advanta ⁇ geously replaced by lug vanes, and both vane-carrying rotors are arranged to rotate in opposite directions.
- the solids feed to both slurrying steps is brought in contact with water only after the solids have first been passed through a similar pin-mill-like apparatus preceding the mixing step with the water.
- all above-mentioned solids agglomerations are eliminated as they are disinte ⁇ grated in the pin mill.
- This concept is based on the fact that disintegration of agglomerations is easy either a) as entirely dry, or, b) as wet in the dry solids range 0-45 %, while difficulties will arise with dry solids exceeding 45 % and extreme difficulties will be involved in the dry solids range of 55-75 %.
- the slurrying apparatus comprises advantageously one or more steps, each advantageously incorporating an apparatus in which the slurry is subjected to a conti ⁇ nuous series of impacts and is chiefly in such a loading state in which the slurry can be thrown in a free space in the inside of the mill.
- the apparatus incorporates a pin mill or similar equipment in which dispersion in water is replaced by dispersion in air, whereby agglomer ⁇ ations and lumps are broken into a steady flow. Then, the solids discharged from the outlet of the disintegrating equipment are dosed directly via, e.g., a hopper feed pipe into the gap of the dispersing mill.
- the invention offers significant benefits.
- Solids can be dispersed to form a slurry in water or other liquid under such conditions in which lumps typical of the slurrying process are prevented from forming putty-like, high-solids agglomerations with water. Addi ⁇ tionally, such conditions can be created in which such putty-like agglomerations are disintegrated optimally.
- the invention makes it possible to disintegrate difficult-to-handle putty-like agglomerations with the help of a high-consistency slurry complemented with preceding disintegration of pigment solids in air prior to the slurrying step.
- the above-described approach also offers an improved sol- ution to the dosing problem.
- the slurry is transfer ⁇ red from the first step to either the second step or an intermediate storage, its density can be easily deter- mined by means of, e.g., a continuously operating density gauge which directly indicates the dry solids.
- a continuously operating density gauge which directly indicates the dry solids.
- the viscosity is increased to multiple value relative to that of the first step.
- Figure 1 is a diagrammatic illustration of an embodiment of the slurrying method according to the invention.
- Figure 2 is a diagrammatic illustration of another embodiment of the slurrying method according to the invention.
- Figure 3 is a diagrammatic illustration of a third embodiment of the slurrying method according to the invention.
- FIG. 4 shows an embodiment of the apparatus according to the invention.
- FIG. 5 shows another embodiment of the apparatus according to the invention.
- the method illustrated therein implements the two-step mixing by means of a single mixer 1.
- the two-step mixing action in this arrangement is implemented by virtue of a return circuit 2.
- Into the mixer 1 is fed high-viscosity product taken from the product discharge line 5 of the mixer via the return circuit 2, whereby water is simultaneously added from line 4 and more solids from line 3.
- the return flow is diluted with water from the line 4 prior to its feed back into the mixer thus facilitating the mixing of more solids into it.
- the mixer is utilized for effective two-step mixing. In the method shown in Fig.
- the mixing is implemented using two mixers la and lb in a manner which is easier to control.
- Into the mixer la are fed water and solids via lines 3 and 4, respectively, in such a ratio that the solids content of the slurry discharged from the mixer la along a connecting line 6 is lower than that of the desired final solids content.
- the slurry contains the final amount of liquid.
- the second mixer lb the remaining amount of solids is mixed in the slurry and the final product is discharged from the mixer along a product outlet line 5.
- the method shown in Fig. 3 is otherwise identical to that illustrated in Fig. 2 except that, besides the feed of solids, additional water is fed into the second mixer lb via line 8.
- a benefit of this arrangement is that the qualities of the slurry and particularly its solids content can be controlled in a more flexible manner.
- FIG. 4 and 5 two apparatuses suited for implementing the invention are shown.
- the reference numerals denoting the elements of the apparatus in these drawings are for equivalent parts the same as those used in Fig. 2.
- the two mixers la and lb of the apparatus are adapted on a framework 11, and the mixers are driven by means of electric motors mounted on the framework 11.
- the mixers la and lb are located on the framework 11 so that the mixer la of the first mixing step is situated above the mixer lb of the second mixing step.
- To the infeed nozzle of the first mixer la is connected a water line 4 and a solids feed arrangement 3.
- the solids feed arrange ⁇ ment 3 comprises a feed hopper 9 and an auger feeder 10 driven by an electric motor.
- connection line 6 to the inlet nozzle of the second mixer lb, and to the connec ⁇ tion line is attached a second feed arrangement 7 of dry solids, similar to the feed arrangement of the first mixing step.
- a product discharge line 5 along which the prepared slurry is taken to a storage tank 13.
- a slurry outlet nozzle with an auger feeder 14 for pumping the slurry to the point of use.
- the apparatus shown therein is otherwise similar to that of Fig. 4 except that in the latter embodiment the first dry solids feed arrangement 3 is complemented with a mixer 15 suited for homogenizing the consistency of the dry solids through grinding the solids into a pulverized form.
- This approach prevents solids lumps from getting into the water and makes mixing easier.
- the homogenization of solids particle size is advantageously carried out using a pin-mill-type mixer similar to that used for slurrying, and in fact, such a mixer may also be connected to the solids feed arrange ⁇ ment 7 of the second mixing step.
- the particle size of the solids can be homo- genized using various screening equipment. Homogenization of dry solids is particularly important when hygroscopic materials are mixed that easily agglomerate into lumps under humidity.
- the invention may be implemented using a plurality of other kinds of appa ⁇ ratuses.
- the number of the mixers may be increased.
- the second mixer is advantageously complemented with a water feed connection, whereby the consistency of the slurry may be controlled as required by adding water.
- the slurrying operation is implemented using different variants of pin-mill-type mixers having at least two con ⁇ centric rings carrying vanes and pins that impose large shearing forces on the material to be mixed.
- a portion of the rings with vanes may comprise nonrotating stator rings, or alternatively, the perimeters can be arranged to rotate at different speeds in the same direction or in opposite directions.
- the proportional amounts of dry solids to be fed in the different mixing steps are determined by the properties of the materials to be mixed. For instance, several mate ⁇ rials used for coating a paper web behave during mixing so that when the solids content of the slurry exceeds a certain limit, the viscosity of the slurry suddenly jumps drastically. Obviously, such anomalities must be taken into account in the preparation of a slurry. Some materials are optimally mixed by a method in which the solids are advantageously mixed in either mixing step divided into half and half of the total dry solids to be mixed.
- the amount of solids feed in the first mixing step should not be selected smaller than 50 % of the total solids, because otherwise the viscosity and density of the slurry remain insufficiently small and mixing in the second step may become difficult.
- the amount of solids to be mixed in the second step should preferably be less than 30 % of the total solids to be mixed.
- the present method is also suited for preparing other slurries than water slurries alone.
- a slurry was prepared of calcined kaolin marketed under the tradename Norcal.
- the kaolin was slurried using an amount that made the solids content of the slurry to be 40 %.
- Slurrying was carried out in a pin mill having the pins replaced by radially aligned impact stop vanes having a radial length of 4 cm.
- the mill had a total number of 5 concentric rings, of which 3 were rotor rings and 2 stator rings.
- the rotational speed was 1500 r/min and the outer diam- eter of the outermost ring was 450 mm.
- the slurrying action was achieved using one through-pass with a retention delay in the order of 0.1 s.
- the product was passed into a mixing tank where its con ⁇ sistency was homogenized as it was difficult to perform continuous dosing accurately at said extremely short mixing delay. Power input to the mill of the first mixing step was 5.5 kW.
- the second mixing step was carried out using a mixing apparatus having two rotors rotating in opposite direc ⁇ tions and in which the outer diameter of the outer rotor was 350 mm and the outer diameter of the other rotor was 300 mm. Both of the rotors had 3 rings. Besides the added kaolin, 0.5 % alkali (NaOH) and 0.12 % polyacrylate (Fennodisp) was added. The outer rotor of the second step mixer was run at +1500 r/min while the other rotor was run at -2200 r/min.
- Kaolin was fed in both the first and the second step by a total amount corresponding to a slurry preparation capacity of 1200 kg/h dry kaolin.
- the input power to the rotor motors of both mixers was 5.5 kW and 5.5 kW, which corresponds to a specific energy consumption of 3.8 kwh per ton mixed dry solids.
- the final product was a slurry having a viscosity of
- Example 2 80 cP measured in the Brookfield viscometer using rotor no. 3 and having a solids content of 54.4 %.
- Example 2 80 cP measured in the Brookfield viscometer using rotor no. 3 and having a solids content of 54.4 %.
- a slurry was prepared by virtue of the method illustrated in Fig. l using a single-mixer appa- ratus operated with the same rotors as in the first example, and similarly, with the same input power to both rotor motors at 5.5 kW and 5.5 kW.
- the slurry was pre ⁇ pared by mixing conventional kaolin (trademark Komolco) in water to form a slurry having a final solids content of 74 %.
- the preparation of the slurry was carried out by branching half of the slurry flow discharged from the mixer aside into a sigmoidal hose pump which returned the recycled half back to the inlet nozzle of the mixer.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU41188/96A AU4118896A (en) | 1994-12-16 | 1995-12-11 | Method and apparatus for slurrying pulverized materials into a liquid |
EP95939306A EP0797478A1 (en) | 1994-12-16 | 1995-12-11 | Method and apparatus for slurrying pulverized materials into a liquid |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI945945 | 1994-12-16 | ||
FI945945A FI100860B (en) | 1994-12-16 | 1994-12-16 | Process and apparatus for slurrying of finely divided substances in liquid a |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1996018454A1 true WO1996018454A1 (en) | 1996-06-20 |
Family
ID=8542000
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FI1995/000675 WO1996018454A1 (en) | 1994-12-16 | 1995-12-11 | Method and apparatus for slurrying pulverized materials into a liquid |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0797478A1 (en) |
AU (1) | AU4118896A (en) |
FI (1) | FI100860B (en) |
WO (1) | WO1996018454A1 (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2005000454A1 (en) * | 2003-06-27 | 2005-01-06 | Mmd Design & Consultancy Limited | Apparatus and method for mixing particulate material with a fluid to form a pumpable slurry |
US6843886B1 (en) | 1999-11-24 | 2005-01-18 | Megatrex Oy | Method for handling filled reject flows in a paper or paperboard mill |
WO2005121033A1 (en) * | 2004-06-14 | 2005-12-22 | Fractivator Oy | Method and apparatus for manufacture of a useful product from sludge, and its use |
WO2006040391A1 (en) | 2004-10-13 | 2006-04-20 | Fractivator Oy | Method and apparatus for treating materials or mixtures of material |
WO2008122691A1 (en) | 2007-04-10 | 2008-10-16 | Fractivator Oy | Impact mill |
WO2010055199A1 (en) | 2008-11-14 | 2010-05-20 | Fractivator Oy | Method and apparatus for the preparation of finely divided calcium hydroxide |
US8282780B2 (en) * | 2003-07-15 | 2012-10-09 | Fp-Pigments Oy | Method and apparatus for pre-treatment of fibre material to be used in the manufacture of paper, board or the like |
WO2016162466A1 (en) * | 2015-04-09 | 2016-10-13 | Akzo Nobel Coatings International B.V. | Continuous process for dispersing solid material in a liquid |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0079300A1 (en) * | 1981-10-23 | 1983-05-18 | Water-Line S.A. | Apparatus to continuously mix and homogenize powdered substances with liquid substances |
FI83897B (en) * | 1988-10-20 | 1991-05-31 | Finnminerals Oy | FOERFARANDE FOER FRAMSTAELLNING AV EN PIGMENTBLANDNING FOER BRUK VID YTBELAEGGNING AV PAPPER. |
-
1994
- 1994-12-16 FI FI945945A patent/FI100860B/en not_active IP Right Cessation
-
1995
- 1995-12-11 AU AU41188/96A patent/AU4118896A/en not_active Abandoned
- 1995-12-11 EP EP95939306A patent/EP0797478A1/en not_active Withdrawn
- 1995-12-11 WO PCT/FI1995/000675 patent/WO1996018454A1/en not_active Application Discontinuation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0079300A1 (en) * | 1981-10-23 | 1983-05-18 | Water-Line S.A. | Apparatus to continuously mix and homogenize powdered substances with liquid substances |
FI83897B (en) * | 1988-10-20 | 1991-05-31 | Finnminerals Oy | FOERFARANDE FOER FRAMSTAELLNING AV EN PIGMENTBLANDNING FOER BRUK VID YTBELAEGGNING AV PAPPER. |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6843886B1 (en) | 1999-11-24 | 2005-01-18 | Megatrex Oy | Method for handling filled reject flows in a paper or paperboard mill |
WO2005000454A1 (en) * | 2003-06-27 | 2005-01-06 | Mmd Design & Consultancy Limited | Apparatus and method for mixing particulate material with a fluid to form a pumpable slurry |
US8282780B2 (en) * | 2003-07-15 | 2012-10-09 | Fp-Pigments Oy | Method and apparatus for pre-treatment of fibre material to be used in the manufacture of paper, board or the like |
US8480855B2 (en) | 2003-07-15 | 2013-07-09 | Fp-Pigments Oy | Method and apparatus for pre-treatment of fibre material to be used in the manufacture of paper, board or the like |
WO2005121033A1 (en) * | 2004-06-14 | 2005-12-22 | Fractivator Oy | Method and apparatus for manufacture of a useful product from sludge, and its use |
WO2006040391A1 (en) | 2004-10-13 | 2006-04-20 | Fractivator Oy | Method and apparatus for treating materials or mixtures of material |
WO2008122691A1 (en) | 2007-04-10 | 2008-10-16 | Fractivator Oy | Impact mill |
WO2010055199A1 (en) | 2008-11-14 | 2010-05-20 | Fractivator Oy | Method and apparatus for the preparation of finely divided calcium hydroxide |
WO2016162466A1 (en) * | 2015-04-09 | 2016-10-13 | Akzo Nobel Coatings International B.V. | Continuous process for dispersing solid material in a liquid |
US20180085718A1 (en) * | 2015-04-09 | 2018-03-29 | Akzo Nobel Coatings International B.V. | Continuous Process for Dispersing Solid Material in a Liquid |
Also Published As
Publication number | Publication date |
---|---|
AU4118896A (en) | 1996-07-03 |
EP0797478A1 (en) | 1997-10-01 |
FI100860B (en) | 1998-03-13 |
FI945945A0 (en) | 1994-12-16 |
FI945945A (en) | 1996-06-17 |
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