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Method for preparing mixed-valence (Cr(IV) and Cr(VI)) chromate Ca5Cr3O12

A mixed valence, ca5cr3o12 technology, applied in the direction of chromate/dichromate, etc., can solve the problems of residue, large calcination temperature span, low yield, etc., to achieve increased yield, convenient reaction process, and high output rate high effect

Pending Publication Date: 2021-04-02
CHANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First of all, this method needs to add a large amount of CaO, and the finished product contains a lot of CaO impurities
And because the method of high temperature oxidation is adopted, the calcination temperature span is large, and Cr(III) will be oxidized into other chromium salts with different valence states in the process, and a mixture product with complex composition is obtained, and Ca is removed from the product. 5 Cr 3 o 12 Also contains Cr 5 o 12 , Ca 3 (CrO 4 ) 2 , Ca 5 (CrO 4 ) 3 o 0.5 and other chromium salts, among which Ca 5 Cr 3 o 12 The content is below 50%, the yield is low
Moreover, some chromium salts contained in the product are not ideally cleaned with deionized water and organic acid, and there will still be a large amount of residue, so Ca 5 Cr 3 o 12 Unable to meet the requirements in terms of purity

Method used

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  • Method for preparing mixed-valence (Cr(IV) and Cr(VI)) chromate Ca5Cr3O12

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] CaO and CaCrO 4 The mixture is mixed with a ball mill, the mass percentage of CaO in the raw material is 40%, CaCrO 4 The mass percentage is 60%, and the mixed raw materials are calcined at a high temperature in an atmosphere box furnace in a mixed atmosphere of oxygen and nitrogen (oxygen partial pressure is 10kPa), the calcination temperature is 1300 ° C, and the calcination time is 5h. The calcined product is cooled in a mixed atmosphere, and the product is washed with deionized water, and then the cooled product is washed with formic acid with a pH value of 5. The solid-to-liquid ratio of the acid to the washed sample is 1:15. After 1 hour of separation of the product, use a suction filter to separate, pickle the filter residue once more according to the above process, wash the filter residue with deionized water and filter. The filter residue obtained after suction filtration was dried in an oven for 5 hours, the drying temperature was maintained at 200°C, and the...

Embodiment 2

[0023] CaO and CaCrO 4 The mixture is mixed with a ball mill, wherein the mass percentage of CaO is 30%, and the mixed raw material is calcined at a high temperature in an atmosphere box furnace in a mixed atmosphere of oxygen and nitrogen (oxygen partial pressure is 15kPa), and the calcining temperature is 1400°C. Calcination time is 6h. The calcined product is cooled in a mixed atmosphere, and the product is washed with deionized water, and then the cooled product is washed with formic acid with a pH value of 6. The solid-to-liquid ratio of the acid to the washed sample is 1:10. After 1 hour of separation of the product, use a suction filter to separate, pickle the filter residue once more according to the above process, wash the filter residue with deionized water and filter. The filter residue obtained after suction filtration was dried in an oven for 5 hours, the drying temperature was maintained at 250°C, and the obtained product was Ca with a purity of 89%. 5 Cr 3 o ...

Embodiment 3

[0025] CaO and CaCrO 4 The mixture is mixed with a ball mill, wherein the mass percentage of CaO is 50%, and the mixed raw material is calcined at a high temperature in an atmosphere box furnace in a mixed atmosphere of oxygen and nitrogen (oxygen partial pressure is 13kPa), and the calcining temperature is 1400°C. Calcination time is 8h. The calcined product is cooled in a mixed atmosphere, and the product is washed with deionized water, and then the cooled product is washed with acetic acid with a pH value of 5. The solid-to-liquid ratio of the acid to the washed sample is 1:20. After 1 hour of separation of the product, use a suction filter to separate, pickle the filter residue once more according to the above process, wash the filter residue with deionized water and filter. The filter residue obtained after suction filtration was dried in an oven for 6 hours, the drying temperature was maintained at 300°C, and the obtained product was Ca with a purity of 86%. 5 Cr 3 o ...

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Abstract

The invention provides a method for preparing mixed-valence (Cr(IV) and Cr(VI)) chromate Ca5Cr3O12, which comprises the following steps: uniformly mixing CaCrO4 and CaO, and carrying out high-temperature calcination in a mixed atmosphere (oxygen partial pressure is 10kPa-15kPa) of oxygen and nitrogen to reduce part of Cr(VI) in the mixture into Cr(IV) so as to generate Ca5Cr3O12; and using deionized water and organic acid (such as dilute acetic acid or formic acid) for washing an obtained product, and then heating and drying filter residues to remove moisture and other impurities. The Ca5Cr3O12 is prepared by adopting a reduction method, the process is simple, required raw materials can be purchased or prepared in a laboratory, the cost is relatively low, the purity of the prepared Ca5Cr3O12 can reach 80-97%, and the yield reaches about 90%.

Description

technical field [0001] The invention relates to the field of chromium salt preparation, in particular to a method for preparing mixed valence state (Cr(Ⅳ) and Cr(Ⅵ)) chromate Ca 5 Cr 3 o 12 Methods. Background technique [0002] Chromium salts are one of the important raw materials of my country's chemical industry, among which Cr(III) and Cr(Ⅵ) salts are the most widely used, Cr(III) salts are widely used in leather tanning, ceramic pigments, electroplating and other industries, Cr(Ⅵ) ) salt is widely used in electroplating, various chromium salt production, preservative manufacturing and other industries. With the expansion of research on chromium-containing materials, the properties of some other valence Cr salts (such as Cr(IV) and Cr(V) salts) have gradually attracted the attention of researchers, and related research on their applications has also been favored. However, the chromium salts in the valence state between Cr(III) and Cr(VI) are often not stable enough, a...

Claims

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Application Information

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IPC IPC(8): C01G37/14
CPCC01G37/14C01P2006/80
Inventor 毛林强王嘉胡林潮张文艺彭明国
Owner CHANGZHOU UNIV
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