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Method for reducing trivalent chromium in sodium dichromate acidizing fluid

A technology of sodium dichromate and trivalent chromium, applied in chromate/dichromate and other directions, can solve the problem of inability to reduce trivalent chromium, and achieve the effect of low free moisture, improved product quality, and improved product quality

Pending Publication Date: 2021-01-01
GANSU JINSHI CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above methods still cannot reduce the trivalent chromium formed due to factors such as insufficient oxidation and corrosion of iron containers.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Present embodiment provides a kind of method that reduces sodium dichromate acidification solution trivalent chromium, comprises the steps:

[0018] S1. Calcium-free roasting is carried out on the chromite, and the roasted product is leached to obtain a sodium chromate solution. After the sodium chromate solution is neutralized to remove aluminum and vanadium, it enters the pre-acidification process;

[0019] S2. Pre-acidification: add sulfuric acid to the sodium chromate solution finally obtained in step S1 to make the acidification rate of the sodium chromate solution reach 62.5%. The content of trivalent chromium in the detection solution is 1.86g / l, 50m 3 Add 15kg of industrial phosphoric acid to the feed liquid according to the ratio of 1.2 times of the theoretical amount, and keep it at 62°C for aging for 6 hours. The feed liquid obtained by filtering cannot detect trivalent chromium, and then transfer to step S3 for processing;

[0020] S3, the qualified feed li...

Embodiment 2

[0025] Present embodiment provides a kind of method that reduces sodium dichromate acidification solution trivalent chromium, comprises the steps:

[0026] S1. Calcium-free roasting is carried out on the chromite, and the roasted product is leached to obtain a sodium chromate solution. After the sodium chromate solution is neutralized to remove aluminum and vanadium, it enters the pre-acidification process;

[0027] S2. Pre-acidification: add sulfuric acid to the sodium chromate solution finally obtained in step S1 to make the acidification rate of the sodium chromate solution reach 68.4%. The content of trivalent chromium in the solution was detected to be 1.34g / l, 50m 3 Add 20 kg of industrial phosphoric acid to the feed liquid according to the ratio of 1.5 times of the theoretical amount, and keep it at 75° C. for 6 hours of aging. The feed liquid obtained by filtering cannot detect trivalent chromium, and then transfer to step S3 for processing;

[0028] S3, the qualified...

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PUM

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Abstract

The invention discloses a method for reducing trivalent chromium in a sodium dichromate acidizing fluid. After roasting, and neutralizing for removing aluminum and vanadium, a pre-acidification procedure is added, a sodium chromate solution (the acidification rate is 62.5-68.4%) is partially acidized, phosphoric acid is quantitatively added according to the content of trivalent chromium in the sodium chromate solution, heating curing is performed to make trivalent chromium in the feed liquid form a chromium phosphate precipitate, filtering is performed to remove chromium phosphate slag, the trivalent chromium in the feed liquid is detected, the result is unqualified, and sulfuric acid is added again to acidify to make the acidifying rate reach a theoretical acidifying rate value of 100.4-101.7% sodium dichromate production. After the trivalent chromium impurity removal process, the finally produced commodity potassium dichromate is low in sulfate, high in content and low in free moisture, and the product quality is improved. According to the method, trivalent chromium generated by various factors can be effectively removed, and the quality of the sodium dichromate product is improved.

Description

technical field [0001] The invention relates to the technical field of chromium salt production chemical technology, in particular to a method for reducing trivalent chromium in sodium dichromate acidification solution and improving the quality of red vitriol products. Background technique [0002] The production process of sodium dichromate includes calcium-free roasting of chromite to produce sodium chromate, leaching sodium chromate solution, neutralization and removal of aluminum, devanadium, sulfuric acid acidification, evaporation and denitrification, sedimentation and denitrification, crystallization and other processes, and finally produces Sodium dichromate is a commodity. Sodium dichromate is a product of hexavalent chromium salt. Due to factors such as insufficient oxidation and corrosion of iron containers in the production process, sodium chromate solution is very easy to produce trivalent chromium, and trivalent chromium salt is very easy to form a solid soluti...

Claims

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Application Information

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IPC IPC(8): C01G37/14
CPCC01G37/14C01P2006/80
Inventor 张忠元陈立军陈荣朱紫谢希智孔红霞李录星秦龙
Owner GANSU JINSHI CHEM