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Method for preparing sodium chromate

A sodium chromate and acid technology, applied in chromate/dichromate and other directions, can solve the problems of low product quality, environmental degradation, aggravated greenhouse effect, etc., and achieve the effect of reducing production cost and improving product quality

Active Publication Date: 2014-11-26
SICHUAN YINHE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this type of method has high production efficiency and simple production process, because there is no impurity removal process, the quality of the obtained product is very low and lacks market competitiveness
[0006] Exhaust gas from industrial kilns contains a certain amount of carbon dioxide gas, and direct emission of it will aggravate the greenhouse effect and lead to further deterioration of the environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] will be 1m 3 The sodium chromate alkaline solution obtained by roasting chromite and leaching is heated to 100°C and kept constant, wherein the concentration of sodium chromate alkaline solution is 537g L -1 (in Na 2 CrO 4 4H 2 O meter).

[0058] 1000m under stirring 3 Wherein, the cement kiln tail gas with a carbon dioxide concentration of about 15% by volume is passed into the sodium chromate alkaline solution until the pH of the solution is reduced to 9.3, and then filtered with a plate and frame filter press to obtain a transparent and clear solution.

[0059] To the above solution at pH 9.3 was added 0.3m 3 From the pre-carbonization solution in the carbonization process to produce sodium rufium, the pH of the solution is adjusted to 8.3, wherein the concentration of the pre-carbonization solution is 357g L -1 (in Na 2 Cr 2 o 7 2H 2 O meter), the pH is 6.6.

[0060] The above solution with a pH of 8.3 was evaporated to a concentration of 1099 g L -1 (in...

Embodiment 2

[0063] will be 1.1m 3 The sodium chromate alkaline solution obtained by roasting chromite and leaching is heated to 90°C and kept constant, wherein the concentration of sodium chromate alkaline solution is 452g L -1 (in Na 2 CrO 4 4H 2 O meter).

[0064] 550m under stirring 3 The tail gas of the lime kiln with a carbon dioxide concentration of about 31% by volume is passed into the sodium chromate alkaline solution until the pH of the solution is reduced to 9.0, and then filtered with a plate and frame filter press to obtain a transparent and clear solution.

[0065] To the above solution at pH 9.0 was added 0.15m 3 From the carbonization solution in the process of carbonization to produce sodium red alum, the pH of the solution is adjusted to 7.8, wherein the concentration of the carbonization solution is 925g L -1 (in Na 2 Cr 2 o 7 2H 2 O meter), pH is 5.8.

[0066] Evaporate the above solution with pH 7.8 to a concentration of 1015 g L -1 (in Na 2 CrO 4 4H 2 ...

Embodiment 3

[0069] will be 1.0m 3 The sodium chromate alkaline solution obtained by roasting chromite and leaching is heated to 95°C and kept constant, wherein the concentration of sodium chromate alkaline solution is 517g L -1 (in Na 2 CrO 4 4H 2 O meter).

[0070] 1800m under stirring 3 Wherein the chromite ore oxidation roasting rotary kiln exhaust gas with a carbon dioxide concentration of about 12% by volume is passed into a sodium chromate alkaline solution until the pH of the solution is reduced to 9.4, and then filtered using a plate and frame filter press to obtain a transparent and clear The solution.

[0071] To the above solution at pH 9.4 was added 0.1m 3 From the electrolytic solution in the process of carbonization to produce sodium red alum, the pH of the solution is adjusted to 8.0, wherein the concentration of the electrolytic solution is 983g L -1 (in Na 2 Cr 2 o 7 2H 2 O meter), the pH is 0.8.

[0072] Evaporate the above pH 8.0 solution to a concentration ...

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Abstract

The invention relates to a method for preparing sodium chromate. The method comprises the following steps: firstly, neutralizing sodium chromate alkaline solution obtained through chromite baking and leaching by using carbon dioxide gas or gas containing carbon dioxide; secondly, separating and removing solid impurities; and thirdly, adding acidic chromium-containing solution to the solution obtained through the separation in the second step to adjust the pH. Through the method disclosed by the invention, the product quality of sodium chromate is improved, and the production cost is further greatly reduced. The tail gas of industrial stoves is used as the neutralizing impurity removing agent of the sodium chromate alkaline solution so that the carbon dioxide gas is recycled and the production cost of sodium chromate can be further reduced.

Description

technical field [0001] The invention relates to a method for preparing sodium chromate. Background technique [0002] As the basic raw material of chromium salt industry, sodium chromate is the basic raw material for the production of sodium dichromate, potassium dichromate, chromic anhydride, chrome green, etc. It is widely used in electroplating, leather making, printing and dyeing, medicine, oil refining, synthetic rubber , spices and stainless steel manufacturing and other industrial fields. With the development of global industrialization, the demand for sodium chromate is gradually increasing. [0003] High-quality sodium chromate is a yellow translucent monoclinic crystal (Na 2 CrO 4 4H 2 O), obtained by cooling crystallization and dehydration of sodium chromate solution at a temperature of 25.9-68°C. [0004] The traditional preparation method of sodium chromate first neutralizes the alkaline solution of sodium chromate by using the mother liquor of sodium chrom...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/14
Inventor 李先荣陈宁王方兵黄先东
Owner SICHUAN YINHE CHEM