A method for reducing hexavalent chromium content in chromium oxide green

A technology of chromium oxide green and hexavalent chromium, which is applied in the direction of chromium oxide/hydrate, can solve the problems of narrow application range of additives, increased energy consumption, high equipment and operation requirements, etc., so as to solve the problem of yellowing of product color and improve recovery rate , The effect of reducing the content of water soluble matter

Active Publication Date: 2020-08-11
HUBEI ZHENHUA CHEMICAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the method has high requirements on equipment and operation, additives and returned materials increase energy consumption in the production process, and additives have a narrow scope of application

Method used

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  • A method for reducing hexavalent chromium content in chromium oxide green
  • A method for reducing hexavalent chromium content in chromium oxide green
  • A method for reducing hexavalent chromium content in chromium oxide green

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] Raise the temperature of the muffle furnace to 950°C, put 15g of chromic anhydride 1 into it, and thermally decompose it for 1h. When the temperature of the muffle furnace is lowered to 400°C, add 2.5mL of saturated ammonium chloride solution, and cool naturally to room temperature. According to the methods of GB9760-88 and GB20785-2006, the hexavalent chromium in chromium oxide green was extracted and analyzed, and the results are as follows:

[0045]

[0046] ICP was used to analyze the chromium content. After adding ammonium chloride during the decomposition and cooling process of chromic anhydride, the soluble chromium content in the chromium oxide green product can be changed from 779 mg kg without adding -1 down to 254mg·kg -1 .

Embodiment 2

[0048] Raise the temperature of the muffle furnace to 950°C, put 15g of chromic anhydride 1 into it, and thermally decompose it for 1h. When the temperature of the muffle furnace is lowered to 100°C, add 0.2mL of ethanol solution and let it cool naturally to room temperature. According to the methods of GB9760-88 and GB20785-2006, the hexavalent chromium in chromium oxide green was extracted and analyzed, and the results are as follows:

[0049]

[0050]

[0051] ICP was used to analyze the chromium content. After adding ethanol in the process of decomposing and cooling chromic anhydride, the soluble chromium content in the chromium oxide green product can be increased from 779 mg kg without adding. -1 Dropped to 178mg·Kg -1 .

Embodiment 3

[0053] Raise the temperature of the muffle furnace to 950°C, put 15g of chromic anhydride 2 into it, and thermally decompose it for 1 hour. When the temperature of the muffle furnace is lowered to 400°C, add 2.5mL of saturated ammonium chloride solution, and let it cool naturally to room temperature. According to the methods of GB9760-88 and GB20785-2006, the hexavalent chromium in chromium oxide green was extracted and analyzed, and the results are as follows:

[0054]

[0055] ICP was used to analyze the chromium content. After adding ammonium chloride during the decomposition and cooling process of chromic anhydride, the soluble chromium content in the chromium oxide green product can be increased from 260mg kg without adding -1 down to 31mg·kg -1 .

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Abstract

The invention provides a method for reducing the content of hexavalent chromium in chromium oxide green. The method includes the step: adding reducing agents into the chromium oxide green with the discharging temperature of 60-400 DEG C in a production process to obtain a chromium oxide green product. According to the method, the hexavalent chromium in the chromium oxide green can be reduced, thecontent of water soluble objects in the chromium oxide green product is reduced, the problem of yellowing of the product is solved, the recovery rate of chromium metal is increased, the method is simple to operate and less in reducing agent dosage, the reducing agents are added in the cooling process, an original process cannot be affected, and the reducing agents are volatilized and decomposed inthe reducing process, so that the purity of the chromium oxide green cannot be affected.

Description

technical field [0001] The invention belongs to the technical field of chromium salt production and relates to a method for reducing the content of hexavalent chromium in chromium oxide green. Background technique [0002] The hexavalent chromium in chromium oxide green not only increases the content of water-soluble substances, but also makes the product yellow, which has a great impact on the use of the product. At present, the main ways to reduce the content of hexavalent chromium in chromium oxide green are: [0003] (1) Roasting after mixing chromic anhydride with a small amount of boric acid, or adding a small amount of boric acid to dichromium trioxide containing hexavalent chromium and then burning; (2) Chromium oxide green obtained by thermal decomposition of chromic anhydride is put into a container while it is hot, and the container is sealed and cooled. Prepackage urea in advance; (3) after chromium oxide green is washed to remove water-soluble matter, suspend i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/02C22B34/32
CPCC01G37/02C22B34/32
Inventor 张红玲周飞龙李会强刘静文庆朋辉石义朗徐红彬蔡再华张懿程西川
Owner HUBEI ZHENHUA CHEMICAL CO LTD
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