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WO1997029047A1 - Production d'alumine - Google Patents

Production d'alumine Download PDF

Info

Publication number
WO1997029047A1
WO1997029047A1 PCT/GB1997/000280 GB9700280W WO9729047A1 WO 1997029047 A1 WO1997029047 A1 WO 1997029047A1 GB 9700280 W GB9700280 W GB 9700280W WO 9729047 A1 WO9729047 A1 WO 9729047A1
Authority
WO
WIPO (PCT)
Prior art keywords
adsorbent
red mud
digestion
liquor
adsorbent material
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.)
Ceased
Application number
PCT/GB1997/000280
Other languages
English (en)
Inventor
Stephen John Adkins
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ciba Specialty Chemicals Water Treatments Ltd
Original Assignee
Allied Colloids 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
Application filed by Allied Colloids Ltd filed Critical Allied Colloids Ltd
Priority to AU16081/97A priority Critical patent/AU1608197A/en
Publication of WO1997029047A1 publication Critical patent/WO1997029047A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

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
    • C01F7/46—Purification of aluminium oxide, aluminium hydroxide or aluminates
    • C01F7/47—Purification of aluminium oxide, aluminium hydroxide or aluminates of aluminates, e.g. removal of compounds of Si, Fe, Ga or of organic compounds from Bayer process liquors
    • C01F7/473—Removal of organic compounds, e.g. sodium oxalate

Definitions

  • PRODUCTION OF ALUMINA This invention relates to the reduction of hu ate and other organic impurities in Bayer process liquor.
  • the Bayer process for producing alumina comprises digesting bauxite in aqueous caustic digestion liquor in a digestion stage to form a digestion product, separating the digestion product in a primary separating stage into a sodium aluminate liquor and red mud, recovering alumina from the separated sodium aluminate liquor in an aluminium recovery circuit and cycling caustic from the circuit to the digestion stage, subjecting the separated red mud to counter-current washing with wash liquor in a first and subsequent washing stages and thereby producing a used wash liquor and a washed red mud, cycling the used wash liquor into the primary separating stage or in the digestion stage, and depositing the washed mud, for instance by dumping in a red mud lake or in a stack.
  • the bauxite tends to be contaminated with humic matter and some degradation of this to materials such as oxalic acid occurs primarily in the digestion stage.
  • the presence of oxalic acid, humic matter and other organic residues can interfere with the recovery of alumina, in particular it can interfere with the crystallisation of aluminium hydrate from the caustic liquor. It is therefore well known to include steps in the overall process that are designed to remove humic matter and organic residues.
  • Some methods include adsorption. See, for instance, US4275043.
  • Another process in which the separated sodium aluminate liquor is treated is described in US4578255 in which organic impurities are coated onto dispersed solids in the separated sodium aluminate liquor and the coated solids are removed.
  • organic impurities are coated onto dispersed solids in the separated sodium aluminate liquor and the coated solids are removed.
  • magnesium and aluminium hydroxides are precipitated in the aluminate liquor and then removed from the liquor with organic impurities.
  • the separation of the organic components from the bauxite wash liquor can be by adsorption onto an adsorbent such as bone char or fly ash and then filtration, flocculation or other removal of the loaded adsorbent (carrying the organics) from the wash liquor, followed by the recycling of the wash liquor from which the adsorbent and organics had been separated.
  • an adsorbent such as bone char or fly ash
  • filtration, flocculation or other removal of the loaded adsorbent (carrying the organics) from the wash liquor followed by the recycling of the wash liquor from which the adsorbent and organics had been separated.
  • the Bayer process is conducted for months or years on end without interruption with continuous charging into the process of fresh bauxite ore and with an accompanying minimum loss of liquor from the process. Accordingly, irrespective of the effectiveness of any particular humate removal stage, there remains a tendency for humate and other organics to accumulate in the process. This has an undesirable effect on the process, and in particular the separation by crystallisation of alumina from the separated sodium aluminate liquor, and it would be desirable to provide an alternative or additional cost effective way of reducing humate and other organic contamination in the
  • organic contamination in the separated sodium aluminate liquor is reduced by contacting the digestion product or the red mud with adsorbent material during the counter-current washing and thereby adsorbing organic contamination by the adsorbent material, and separating the loaded adsorbent material from the digestion product or wash liquor.
  • the separation of the loaded adsorbent is effected by depositing the loaded adsorbent with the washed red mud.
  • the adsorbent becomes loaded with organic contaminants (by adsorption) during the contact with the digestion liquor or the red mud wash liquor, and the loaded adsorbent is removed from the system.
  • the adsorbent material is particulate.
  • the loaded adsorbent is deposited with the washed mud and thus takes the organic contamination (which is adsorbed onto it) out of the Bayer process as a mixture of the red mud and the adsorbent carrying the organic contamination.
  • the adsorbent When the adsorbent is to be contacted with the digestion product, this can be effected in the digestion stage, for instance by including adsorbent with the bauxite which is fed to the digester and/or by adding particulate adsorbent to the materials in the digester and/or by immersing a support carrying adsorbent into the digester.
  • the conditions in the digester may tend to degrade the adsorbent and it is generally more efficient to contact the digestion product with adsorbent by contacting the adsorbent with the digestion product in the primary separation stage.
  • the preferred way of making the contact with the digestion product is by adding particulate adsorbent to the primary settler or to other processing equipment in the primary separation stage.
  • the red mud with the adsorbent is a particulate material which is added into the primary settler or into the first or second washers.
  • the adsorbent material must have porosity such that it is effective in the invention. Preferably it has a significant porosity due to the presence of macropores, having a pore size (diameter) above 50nm and often above lOOnm or even above 500nm. It may alternatively, or preferably additionally, have a significant porosity due to the presence of mesopores (e.g., 2 to 50nm) and/or micropores (e.g., below 2nm) .
  • mesopores e.g., 2 to 50nm
  • micropores e.g., below 2nm
  • the preferred material is bone char. This has a wide range of pore sizes (diameters) typically ranging from around lnm or less up to several thousand nm, for example 6500nm.
  • Activated carbons can also be used in the invention. Macroporous carbons having a pore size of greater than 50nm are more effective than mesoporous carbon having a pore size of 2 to 50nm or microporous carbons having a pore size of less than 2nm, by virtue of pore diameter, but a mixed activated carbon of varying pore size is preferred.
  • Fly ash can be used, provided it has appropriate pore sizes, typically macroporous preferably with some mesoporosity and/or microporosity.
  • the adsorbent material is bone char (bone charcoal) . So far as we are aware all normal grades of bone char are suitable irrespective of the pore size distribution and so precise measurement of the pore size is not essential.
  • the particle size of the particulate adsorbent can be selected from very fine (for instance 90% below lOO ⁇ m but generally above 30 ⁇ m) up to a size of 90% 0.1 to lmm. Particles having a size above lmm can be used.
  • the amount of adsorbent which is used to contact the liquors can vary widely. When adsorbent is added continuously throughout prolonged operation of the process, adequate adsorption can be achieved by the addition of, typically, at least 0.2 and generally at least 0.5 grams bone char or other adsorbent per litre of suspension being treated. Typically the dose is 0.5 to 5g/l. However when the bone char or other adsorbent is added intermittently the rate at which it is added can be higher, for instance 5 to 50g/l.
  • the adsorbent It is particularly desirable to contact the adsorbent with the digestion product or the red mud which is being washed while the product or mud has an elevated temperature, for instance above 50°C and preferably at least 90°C, and/or a relatively high content of sodium hydroxide, for instance at least lOOg/1 and preferably at least 200g/l. Rapid adsorption of the organics occurs onto the adsorbent under such conditions and yet the organic impurities do not significantly de-adsorb from the particles at lower temperatures and caustic levels, ie as the particles move down the series of washers to the final washing stage.
  • an elevated temperature for instance above 50°C and preferably at least 90°C
  • a relatively high content of sodium hydroxide for instance at least lOOg/1 and preferably at least 200g/l. Rapid adsorption of the organics occurs onto the adsorbent under such conditions and yet the organic impurities do not significantly de-adsorb from the particles at lower temperatures and caustic levels
  • the overall Bayer process may be conducted in conventional manner except for the addition of the adsorbent described above.
  • Example 1 The following are examples. Example 1
  • a synthetic slurry was prepared to simulate a primary thickener slurry and was made up as follows:
  • 500cm samples were taken in 500cm cylinders and placed in a water bath and allowed to reach a temperature of 90°C.
  • the humate level was determined by measuring colour absorbance at 420nm and comparing with a set of standards.
  • the synthetic slurry was prepared as in Example 1. 100cm samples were taken in 150cm beakers and stirred mechanically. Various dose levels of bone char were added and stirring continued for the time indicated. After this elapsed time, a sample was removed, filtered to remove the solids and the filtrate was analysed for humate as in Example 1. Sodium Humate content (mg/1) at time (mins)
  • a synthetic slurry was prepared to simulate a final washer slurry as follows:
  • test method used was identical to that in Example 2 except that only the 240 minute conditioning time was used.
  • a sample of first washer feed was taken from plant and used as test substrate. Tests were conducted by adding the appropriate weight of bone charcoal to each 250cm plastic bottle. 200cm of first washer slurry was added and the contents shaken by hand. The bottle was placed in a rotating water bath set at a temperature of 95°C. At the appropriate time, 25cm of sample was extracted, filtered to remove the solids and the absorbance measured at 690nm. The lower the absorbance the lower is the colour (humate) intensity.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)

Abstract

Dans un traitement de boues rouges Bayer visant à la production d'alumine, on réduit la contamination organique de la liqueur d'aluminate de sodium en mettant en contact le produit de digestion ou la boue rouge avec du charbon d'os, du carbone macroporeux ou des cendres volantes macroporeuses, ou un autre adsorbant, et en séparant l'adsorbant chargé ainsi obtenu du produit de digestion ou de la liqueur de lavage.
PCT/GB1997/000280 1996-02-06 1997-01-31 Production d'alumine Ceased WO1997029047A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU16081/97A AU1608197A (en) 1996-02-06 1997-01-31 Production of alumina

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB9602343.7A GB9602343D0 (en) 1996-02-06 1996-02-06 Production of alumina
GB9602343.7 1996-02-06

Publications (1)

Publication Number Publication Date
WO1997029047A1 true WO1997029047A1 (fr) 1997-08-14

Family

ID=10788175

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1997/000280 Ceased WO1997029047A1 (fr) 1996-02-06 1997-01-31 Production d'alumine

Country Status (3)

Country Link
AU (1) AU1608197A (fr)
GB (1) GB9602343D0 (fr)
WO (1) WO1997029047A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2226174C1 (ru) * 2002-12-30 2004-03-27 Открытое акционерное общество "Всероссийский алюминиево-магниевый институт" Способ получения глинозема из боксита
RU2229440C1 (ru) * 2002-11-22 2004-05-27 Открытое акционерное общество "Всероссийский алюминиево-магниевый институт" Способ получения глинозема
RU2232715C1 (ru) * 2002-12-30 2004-07-20 Открытое акционерное общество "Всероссийский алюминиево-магниевый институт" Способ переработки бокситов
CN102951667A (zh) * 2012-11-26 2013-03-06 中国铝业股份有限公司 一种铝酸钠溶液脱硅的方法
CN109824072A (zh) * 2018-05-08 2019-05-31 内蒙古蒙西鄂尔多斯铝业有限公司 利用工业废渣制备氧化铝的方法
CN114735736A (zh) * 2022-03-28 2022-07-12 广西田东锦鑫化工有限公司 氧化铝生产中去除铝酸钠溶液中多种有机化合物的方法
US12145856B2 (en) 2021-02-12 2024-11-19 Ecolab Usa Inc. Purification of ores using boronic acid-functional compounds

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2111722A1 (fr) * 1970-10-20 1972-06-09 Kaiser Aluminium Chem Corp
US4275043A (en) * 1979-01-31 1981-06-23 Alcan Research And Development Limited Removal of oxalate from bayer process liquor
US5093092A (en) * 1991-02-28 1992-03-03 Aluminum Company Of America Purification of bayer process liquor with alumina coated with a layer or carbon

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2111722A1 (fr) * 1970-10-20 1972-06-09 Kaiser Aluminium Chem Corp
US4275043A (en) * 1979-01-31 1981-06-23 Alcan Research And Development Limited Removal of oxalate from bayer process liquor
US5093092A (en) * 1991-02-28 1992-03-03 Aluminum Company Of America Purification of bayer process liquor with alumina coated with a layer or carbon

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, vol. 97, no. 12, 20 September 1982, Columbus, Ohio, US; abstract no. 94760, ANASHKIN, V. S. ET AL: "Effect of organic substances on the crystallization of vanadium salts from industrial aluminate solutions" XP002030789 *
CHEMICAL ABSTRACTS, vol. 99, no. 12, 19 September 1983, Columbus, Ohio, US; abstract no. 90323, NI, L. P. ET AL: "Removal of organic matter from alumina production solutions using inorganic sorbents" XP002030788 *
IZV. VYSSH. UCHEBN. ZAVED., TSVETN. METALL. (1982), (2), 44-6 CODEN: IVUTAK;ISSN: 0021-3438, 1982 *
KOMPLEKSN. ISPOL'Z. MINER. SYR'YA (1983), (5), 77-8 CODEN: KIMSDD, 1983 *

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2229440C1 (ru) * 2002-11-22 2004-05-27 Открытое акционерное общество "Всероссийский алюминиево-магниевый институт" Способ получения глинозема
RU2226174C1 (ru) * 2002-12-30 2004-03-27 Открытое акционерное общество "Всероссийский алюминиево-магниевый институт" Способ получения глинозема из боксита
RU2232715C1 (ru) * 2002-12-30 2004-07-20 Открытое акционерное общество "Всероссийский алюминиево-магниевый институт" Способ переработки бокситов
CN102951667A (zh) * 2012-11-26 2013-03-06 中国铝业股份有限公司 一种铝酸钠溶液脱硅的方法
CN109824072A (zh) * 2018-05-08 2019-05-31 内蒙古蒙西鄂尔多斯铝业有限公司 利用工业废渣制备氧化铝的方法
US12145856B2 (en) 2021-02-12 2024-11-19 Ecolab Usa Inc. Purification of ores using boronic acid-functional compounds
CN114735736A (zh) * 2022-03-28 2022-07-12 广西田东锦鑫化工有限公司 氧化铝生产中去除铝酸钠溶液中多种有机化合物的方法
CN114735736B (zh) * 2022-03-28 2024-05-03 广西田东锦鑫化工有限公司 氧化铝生产中去除铝酸钠溶液中多种有机化合物的方法

Also Published As

Publication number Publication date
AU1608197A (en) 1997-08-28
GB9602343D0 (en) 1996-04-03

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