GB748610A - Improvements in or relating to a method for treating alkali metal chromates - Google Patents
Improvements in or relating to a method for treating alkali metal chromatesInfo
- Publication number
- GB748610A GB748610A GB16910/53A GB1691053A GB748610A GB 748610 A GB748610 A GB 748610A GB 16910/53 A GB16910/53 A GB 16910/53A GB 1691053 A GB1691053 A GB 1691053A GB 748610 A GB748610 A GB 748610A
- Authority
- GB
- United Kingdom
- Prior art keywords
- chromate
- hydrogen
- reduction
- reaction
- sodium
- 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.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G37/00—Compounds of chromium
- C01G37/02—Oxides or hydrates thereof
-
- 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
- C01P2006/80—Compositional purity
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
Alkali metal chromates are partially reduced by passing a stream of hydrogen in contact with a dry granular mass of the chromate particles initially maintained at a temperature within the range of 300 to 350 DEG C. and thereafter maintaining the temperature above 300 DEG C. and below the fusion point of the reaction mass up to a maximum of 600 DEG C. and continuing the contact of hydrogen with the chromate until the reaction is substantially complete as determined by the amount of hexavalent chromium remaining in the reaction mass. The fusion point of the mass rises as the reaction proceeds and the temperatures are such that fusion is at all times avoided. The reduced product after washing to remove impurities may be employed after drying as a chromium containing material for use in metallurgical exothermic alloying mixes, or alternatively the reduced materials after washing may be calcined at above 600 DEG C. in an oxidizing atmosphere for example air, whereby the chromium complex resulting from the reduction treatment breaks down to a mixture of chromic oxide and alkali metal chromate. The latter may be removed by leaching with hot water leaving a solid residue of high purity chromic oxide. The raw material employed, preferably sodium chromate, may be either pure crystalline anhydrous salt or crude sodium chromate for example, crystallized from leach liquors obtained from the alkaline oxidation roasting of chromite ores, which crude product contains as impurities sodium aluminate, hydroxide, carbonate, sulphate and silicate. The aluminate, carbonate, sulphate and silicate impurities are removed by water leaching of the reduced reaction product but the sodium hydroxide content of the starting material is preferably reduced to below 15 per cent by weight either by treating the crude material with carbon dioxide or by extraction with a low molecular weight aliphatic alcohol. Alternatively if the sodium hydroxide is not removed diluents such as the leached reaction product or purified chromic oxide may be added to prevent fusion of the reaction mass. The hydrogen employed is preferably pure but carbon dioxide may be tolerated as a diluent since it reacts with any free sodium hydroxide present to form leachable sodium carbonate. The reduction reaction which is preferably effected at 300 to 400 DEG C., may be carried out in a tubular reactor preferably with agitation, the solid and gas preferably passing in counter current. Examples compare reduction with hydrogen at 315 DEG C. according to the invention, whereby 99.5 per cent of the initial chromate is reacted, with reduction with hydrogen at 650 DEG C. when fusion occurs and only 50 per cent of the initial chromate reacts. Further examples illustrate the effect of sodium hydroxide concentration in the initial material and compare the reduction with hydrogen according to the invention with reduction employing sawdust, sawdust and a hydrogen stream, and reduction with charcoal. Chromates of Li, Na, K, Rb and Cs may be so treated.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US748610XA | 1952-07-16 | 1952-07-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB748610A true GB748610A (en) | 1956-05-09 |
Family
ID=22122104
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB16910/53A Expired GB748610A (en) | 1952-07-16 | 1953-06-18 | Improvements in or relating to a method for treating alkali metal chromates |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB748610A (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2030510A1 (en) * | 1970-06-20 | 1971-12-30 | Bayer | Process for the production of low-sulfur chromium (III) oxide |
WO2007082447A1 (en) * | 2006-01-16 | 2007-07-26 | Aluminum Corporation Of China Limited | Method for improving cycle efficiency of bayer process alumina production |
WO2011117274A1 (en) | 2010-03-23 | 2011-09-29 | Lanxess Deutschland Gmbh | Method for producing chromium(iii) oxide |
WO2012076564A1 (en) | 2010-12-08 | 2012-06-14 | Lanxess Deutschland Gmbh | Process for preparing chromium(iii) oxide |
EP2565162A1 (en) | 2011-09-05 | 2013-03-06 | LANXESS Deutschland GmbH | Method for producing chromium (III) oxide |
-
1953
- 1953-06-18 GB GB16910/53A patent/GB748610A/en not_active Expired
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2030510A1 (en) * | 1970-06-20 | 1971-12-30 | Bayer | Process for the production of low-sulfur chromium (III) oxide |
WO2007082447A1 (en) * | 2006-01-16 | 2007-07-26 | Aluminum Corporation Of China Limited | Method for improving cycle efficiency of bayer process alumina production |
AU2006336147B2 (en) * | 2006-01-16 | 2011-05-12 | Aluminum Corporation Of China Limited | Method for improving cycle efficiency of Bayer process alumina production |
WO2011117274A1 (en) | 2010-03-23 | 2011-09-29 | Lanxess Deutschland Gmbh | Method for producing chromium(iii) oxide |
US9663383B2 (en) | 2010-03-23 | 2017-05-30 | Lanxess Deutschland Gmbh | Process for preparing chromium(III) oxide |
WO2012076564A1 (en) | 2010-12-08 | 2012-06-14 | Lanxess Deutschland Gmbh | Process for preparing chromium(iii) oxide |
EP2565162A1 (en) | 2011-09-05 | 2013-03-06 | LANXESS Deutschland GmbH | Method for producing chromium (III) oxide |
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