WO2011072323A1 - Procédé pour le traitement de boues rouges - Google Patents

Procédé pour le traitement de boues rouges Download PDF

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Publication number
WO2011072323A1
WO2011072323A1 PCT/AU2010/001674 AU2010001674W WO2011072323A1 WO 2011072323 A1 WO2011072323 A1 WO 2011072323A1 AU 2010001674 W AU2010001674 W AU 2010001674W WO 2011072323 A1 WO2011072323 A1 WO 2011072323A1
Authority
WO
WIPO (PCT)
Prior art keywords
mill
grinding
grinding media
desilication product
red mud
Prior art date
Application number
PCT/AU2010/001674
Other languages
English (en)
Inventor
Katie Elizabeth Barns
Voltaire Villadolid
Michael Matthew Hourn
Original Assignee
Xstrata Technology Pty Ltd
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
Priority claimed from AU2009906091A external-priority patent/AU2009906091A0/en
Application filed by Xstrata Technology Pty Ltd filed Critical Xstrata Technology Pty Ltd
Priority to AU2010333699A priority Critical patent/AU2010333699B2/en
Publication of WO2011072323A1 publication Critical patent/WO2011072323A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/04—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom
    • C01F7/06—Preparation of alkali metal aluminates; Aluminium oxide or hydroxide therefrom by treating aluminous minerals or waste-like raw materials with alkali hydroxide, e.g. leaching of bauxite according to the Bayer process
    • C01F7/066—Treatment of the separated residue
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/16—Mills in which a fixed container houses stirring means tumbling the charge
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18—Details
    • B02C17/20—Disintegrating members

Definitions

  • the present invention relates to a process for treating red mud or for treating a concentrate containing desilication product from red mud.
  • the Bayer process is widely used in the manufacture of alumina.
  • the Bayer process involves contacting bauxite with a strongly alkaline digestion solution at elevated temperatures and pressures.
  • the most commonly used alkaline digestion solution is caustic soda.
  • the alkaline digestion solution dissolves aluminium compounds in the bauxite to form a pregnant digestion liquor.
  • the pregnant liquor is separated from undissolved solids in a clarification or settling stage.
  • Alumina is subsequently recovered from the pregnant liquor by passing the pregnant liquor through a precipitation stage to recover aluminium hydrate precipitates.
  • the aluminium hydrate precipitates are subsequently calcined in a calcining stage to form particulate alumina.
  • red mud contains iron oxide compounds (which give it the characteristic red colour), other metal oxide compounds and silica compounds.
  • the red mud also contains quantities of entrained alkaline digestion solution.
  • the red mud Once the red mud has been separated from the pregnant liquor, it is washed to remove some of the entrained alkaline digestion solution. The red mud is typically then discharged to tailings dams or to red mud pans.
  • Bauxite ore typically contains aluminium compounds, iron oxide compounds, clay, silt and silica compounds. During the digestion process, the alkaline digestion solution dissolves the aluminium compounds. However, silica compounds are also readily soluble in alkaline digestion solutions and therefore the free silica compounds and clay materials in the bauxite are also dissolved during digestion. This causes increased consumption of alkaline material.
  • the bauxite is subjected to a desilication step prior to the digestion step.
  • the desilication step the bauxite is contacted with alkaline solution at atmospheric temperature and elevated pressure in a desilication leaching vessel. This results in dissolution of silica compounds and some aluminium compounds.
  • the residence time of the liquor in the desilication vessels is controlled such that a desilication product precipitates out in the desilication vessel. This reduces scale buildup in the digestion vessels.
  • the desilication product (which is also referred to as sodalite) is a product that contains sodium, silica and alumina.
  • the desilication product is normally discharged with the red mud and it represents a significant loss of both soda and alumina from the Bayer process.
  • Suitable reagents include oxides and hydroxides such as CaO, NaOH and Ca(OH) 2 .
  • the present invention provides a method for treating red mud containing a desilication product or for treating a desilication product-containing concentrate obtained from red mud, the method comprising grinding the desilication product for a period of less than 15 minutes.
  • the desilication product is subject to grinding in a high intensity mill having a power input of at least 50 kW/m 3 , more preferably between 50 to 600kW/m 3 , even more preferably between 80 to 500 kW/m 3 , even more preferably around 100 to 500k W/m 3 , even more preferably 150 - 500 kW/m 3 , even more preferably 200 to 400 kW/m 3 , most preferably about 250 to 350 kW/m 3 .
  • the desilication product is subject to grinding for a period of from 0.5 minute to 15 minutes, preferably from 0.5 minute to 10, even more preferably from 0.5 minute to 5 minutes.
  • the method of the present invention utilises a horizontal shaft grinding mill.
  • a suitable horizontal shaft grinding mill is a horizontal shaft grinding mill as described in some embodiments of United States patent 5,797,550, or such as a horizontal shaft grinding mill as manufactured and sold by Xstrata Technology under the trade name IsaMillTM .
  • Other horizontal shaft grinding mills or modified IsaMills, or vertical stirred mills may also be used.
  • the IsaMill utilizes circular grinding discs that agitate the media and/or particles in a slurry. A classification and product separator keeps the grinding media inside the mill, allowing only the product to exit.
  • the mill used in the present invention may have a power of at least 500kW. More suitably, the mill has a power of at least 750kW. Even more suitably, the mill has a power of 1MW or greater. Preferably, the mill has a power from 1MW to 20 MW. In this regard, the power of the mill is determined by the power draw of the motor or motors powering the mill.
  • the grinding mill comprises an IsaMill (as described above).
  • IsaMill a series of stirrers are positioned inside the grinding chamber and these stirrers are rotated by an appropriate driven shaft.
  • the high power intensity is achieved through a combination of high stirrer speed and compression of the media arising from back pressure applied in the grinding mill.
  • the tip speed of the rotating stirrers falls within the range of 5 to 35 meters per second, more preferably 10 to 30 metres per second, even more preferably 15 to 25 metres per second.
  • stirrers used in an IsaMill are typically discs. However, it will be appreciated that an IsaMill may be modified to use different stirrers and the present invention encompasses use of such modified mills. It will also be appreciated that other horizontal or vertical stirred mills may also be used in accordance with the present invention where those other stirred mills incorporate appropriate rotating structures, for example, peg mills, mills that are stirred by a rotating auger flight, tower mills etc. The tip speed of those rotating apparatus preferably falls within the ranges given above.
  • mills may also be used, provided that the mills have the minimum power input as specified above.
  • mills that may be used in the present invention include vertical or horizontal stirred mills such as those produced by Deswik, Metso Minerals (Verti Mill and Stirred Mill Detritor (SMD)), Nippon Eirich Co. as well as Union Process Inc
  • SMD Metal Organic Chemical Vapor
  • the mill used in the present invention suitably utilises a grinding media.
  • the grinding media is a man-made grinding media.
  • man-made grinding media that may be used in the present invention include ceramic grinding media, steel or iron grinding media or grinding media based upon metallurgical slags.
  • man-made grinding media it is meant that the grinding media has been manufactured by a process that includes a chemical transformation of a material or materials into another material.
  • the term “man-made grinding media” is not meant to encompass materials that have been treated solely by physical means, such as tumbling or screening of natural sands.
  • the grinding media may have a specific gravity that falls within the range of 2.2 to 8.5 tonnes per cubic metre.
  • the method of the present invention utilises a ceramic grinding media.
  • the specific gravity of the ceramic grinding media preferably falls within the range of 2.4 to 6.0 tonnes per cubic meter. More preferably, the specific gravity of the grinding media is greater than 3.0 tonnes per cubic meter, even more preferably about 3.2 to 4.0 tonnes per cubic meter, yet even more preferably about 3.5 to 3.7 tonnes per cubic metre.
  • the ceramic grinding media may comprise an oxide material.
  • the oxide material may include one or more of alumina, silica, iron oxide, zirconia, magnesia, calcium oxide, magnesia stabilized zirconia, yttrium oxide, silicon nitrides, zircon, yttria stabilized zirconia, cerium stabilized zirconia oxide or other similar hard wearing materials.
  • the ceramic grinding media is preferably generally spherical in shape although other shapes may also be used. Even irregular shapes may be used.
  • the present invention utilises iron or steel grinding media.
  • the grinding media is suitably in the form of spheres or balls, although other shapes may also be used.
  • the specific gravity of steel or iron grinding media normally is greater than 6.0 tonnes/m 3 , more preferably about 6.5 to 8.5 tonnes/m 3 .
  • Other embodiments of the present invention utilise metallurgical slags or other byproducts available to the operator as the grinding media.
  • the metallurgical slag or other byproducts may be used in the form of irregular shaped particles or, more preferably, as regular shaped particles . If regular shaped particles are used, those particles are suitably of generally spherical shape. However, it will be understood that the present invention also extends to using other shapes.
  • the grinding media may be added to the grinding chamber such that it occupies from 60% to 90% by volume of the space within the grinding chamber, or even from 70 to 80% by volume of the space within the grinding chamber.
  • the present invention also encompasses a grinding method in which the grinding mill has a volumetric filling of less than 60% of grinding media.
  • the grinding media may be present in an amount such that the weight ratio of grinding media to red mud or the ratio of grinding media to desilication product-containing concentrate obtained from red mud in the mill (calculated on a dry basis) falls within the range of 1 to 15, more preferably within the range of 5 to 15, even more preferably within the range of from 5 to 10. These ranges are significantly lower than used in international patent application number PCT/AU97/00073, which used a weight ratio of grinding balls to red mud of 20.
  • the present invention includes further step of removing a slurry from the mill and separating a liquid component from the slurry.
  • the recovered soda and/or alumina will report to the liquid fraction.
  • the liquid fraction may be further treated to recover soda and/or alumina therefrom. Alternatively, the liquid fraction may be returned to the Bayer process circuit.
  • the desilication product is treated in the milling step in the presence of one or more reagents.
  • Suitable reagents include those that are capable of reacting with the desilication product to solubilise soda and/or alumina.. Some examples include oxides and hydroxides, such as CaO, NaOH and Ca(OH) 2 .
  • the reagents are present with the desilication product in the milling step.
  • the reagents may be added to the mill as a separate stream to the stream containing the desilication product. More preferably, the reagent(s) is mixed with the stream containing the desilication product prior to feeding the desilication product stream to the mill. This is desirable in that separate feeding arrangements to the mill for the reagent stream are not required.
  • the present inventors believe that, somewhat surprisingly, utilisation of very short grinding times, optionally in conjunction with high specific power inputs during grinding, can result in the recovery of significant amounts of soda and/or alumina " contained in the desilication product.
  • the grinding time of the desilication product in the present invention is minimised, large throughputs can be achieved and the large quantities of desilication product generated in the Bayer process can be efficiently treated to recover soda and/or alumina from the desilication product.
  • a lower ratio of grinding media to red mud is used than in previous attempts to treat red mud.
  • the present invention provides a method for treating red mud to enable it to be used for remediation purposes by reducing or eliminating the desilication product present in the red mud.
  • remediation it is meant that the red mud is treated to enable vegetation of some type to establish itself on the treated red mud and stabilise it.
  • the treated red mud to be used for remediation will be discharged to a tailings dam or red mud pans, and may be used by itself, or with materials such as mulch, fertilizers, chemicals, gypsum, soil modifiers or the like, either added to the red mud during processing or post processing, to enable the red mud to be used for remediation.
  • red mud is treated to enable the remediation of the red mud to take place.
  • the red mud may also be treated by itself, or with reagents that are capable of reacting with the desilication product to solubilise soda and/or alumina, as described previously, to ensure the treated red mud can be used for remediation.
  • the priority of the process is to enable the red mud to be used for remediation purposes, and the soda and/or alumina that is removed from the mud may be retreated in the Bayer process, or transformed into alumina and/or soda and/or other useful products, or in some cases be treated as a waste product.
  • the present invention provides a method for partial treatment of red mud as it is produced, prior to discharging to dams or ponds.
  • the red mud may only be partially neutralised of the desilication product, and, while not being fully remediated to allow vegetation to be established on it, the treated red mud will contain less desilication product than red-mud that has not been treated by the invention.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
  • Treatment Of Sludge (AREA)

Abstract

L'invention porte sur un procédé pour le traitement de boues rouges contenant un produit de désilicification ou pour le traitement d'un concentré contenant un produit de désilicification obtenu à partir de boues rouges consistant à broyer le produit de désilicification pendant une durée inférieure à 15 minutes. Le broyage peut se faire dans un broyeur à haute intensité ayant une puissance absorbée d'au moins 50 kW/m3 et/ou ayant un rapport pondéral des corps broyants aux boues rouges ou au concentré contenant un produit de désilicification inférieur à 15.
PCT/AU2010/001674 2009-12-14 2010-12-10 Procédé pour le traitement de boues rouges WO2011072323A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2010333699A AU2010333699B2 (en) 2009-12-14 2010-12-10 Process for treating red mud

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2009906091 2009-12-14
AU2009906091A AU2009906091A0 (en) 2009-12-14 Process for Treating Red Mud

Publications (1)

Publication Number Publication Date
WO2011072323A1 true WO2011072323A1 (fr) 2011-06-23

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU2010/001674 WO2011072323A1 (fr) 2009-12-14 2010-12-10 Procédé pour le traitement de boues rouges

Country Status (2)

Country Link
AU (1) AU2010333699B2 (fr)
WO (1) WO2011072323A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102500596A (zh) * 2011-10-20 2012-06-20 安徽理工大学 一种适用于拜耳法的赤泥无害化综合回收利用工艺
CN102989581A (zh) * 2012-09-29 2013-03-27 贵州绿水青山环保科技有限公司 一种消除赤泥放射性的方法
CN105129827A (zh) * 2015-08-27 2015-12-09 河南兴浩新材料科技股份有限公司 一种拟薄水铝石的生产方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993016003A1 (fr) * 1992-02-06 1993-08-19 Alcoa Of Australia Limited Procede de traitement des boues rouges
US5328501A (en) * 1988-12-22 1994-07-12 The University Of Western Australia Process for the production of metal products B9 combined mechanical activation and chemical reduction
WO1997029992A1 (fr) * 1996-02-15 1997-08-21 Queensland Alumina Limited Traitement des boues rouges
US5797550A (en) * 1994-04-11 1998-08-25 Mount Isa Mines Limited Attrition mill

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5328501A (en) * 1988-12-22 1994-07-12 The University Of Western Australia Process for the production of metal products B9 combined mechanical activation and chemical reduction
WO1993016003A1 (fr) * 1992-02-06 1993-08-19 Alcoa Of Australia Limited Procede de traitement des boues rouges
US5797550A (en) * 1994-04-11 1998-08-25 Mount Isa Mines Limited Attrition mill
WO1997029992A1 (fr) * 1996-02-15 1997-08-21 Queensland Alumina Limited Traitement des boues rouges

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102500596A (zh) * 2011-10-20 2012-06-20 安徽理工大学 一种适用于拜耳法的赤泥无害化综合回收利用工艺
CN102989581A (zh) * 2012-09-29 2013-03-27 贵州绿水青山环保科技有限公司 一种消除赤泥放射性的方法
CN105129827A (zh) * 2015-08-27 2015-12-09 河南兴浩新材料科技股份有限公司 一种拟薄水铝石的生产方法

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Publication number Publication date
AU2010333699B2 (en) 2013-11-21
AU2010333699A1 (en) 2012-07-05

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