Process for preparing sodium dichromate

A technology of sodium bauxite and seed crystals, which is applied in the field of preparation of sodium bauxite, can solve problems such as high cost, high energy consumption in electrolysis, and consumption of sulfuric acid, and achieve the effects of reducing equipment corrosion, reducing environmental pressure, and reducing emissions

Inactive Publication Date: 2010-04-14
SICHUAN YINHE CHEM
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Problems solved by technology

The sulfuric acid method is the method adopted in my country and most countries, but the disadvantage of the sulfuric acid method is the consumption of sulfuric acid, the by-product sodium sulfate contains 0.1% hexavalent chromium, and the cost is relatively high
Compared with the sulfuric acid method, the product quality of the electrolysis method is high, and the by-products can be recycled, but the electrolysis method has high energy consumption and high cost

Method used

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  • Process for preparing sodium dichromate

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Effect test

Embodiment 1

[0013] Embodiment 1: a kind of preparation method of red vitriol sodium carries out according to the following steps:

[0014] ① Feeding, put 500g / L neutral liquid into the carbonization tower;

[0015] ②Temperature control, adjust the temperature of the carbonization tower at 20-80°C according to the number of carbonization stages, and control the final carbonization temperature of the high-concentration carbonization tower below 40°C.

[0016] ③ Ventilation, adjust the carbonization pressure of the carbonization tower to 1.5Mpa, and the carbon dioxide concentration is 80%.

[0017] ④ Control the carbonization time, and control the carbonization time to 10 hours. After carbonization until the carbon dioxide in the solution reaches saturation, add sodium chromate carbonized seed crystals to the carbonization tower to facilitate the crystallization of sodium bicarbonate and the conversion of sodium chromate into dichromate sodium.

[0018] ⑤ Separation, use a plate and frame ...

Embodiment 2

[0021] Embodiment 2: a kind of preparation method of red vitriol sodium carries out according to the following steps:

[0022] ① Feeding, put 600g / L neutral liquid into the carbonization tower;

[0023] ②Temperature control, adjust the temperature of the carbonization tower at 20-80°C according to the number of carbonization stages, and control the final carbonization temperature of the high-concentration carbonization tower below 40°C.

[0024] ③ Ventilation, adjust the carbonization pressure of the carbonization tower to 1.5Mpa, and the carbon dioxide concentration is 90%.

[0025] ④ Control the carbonization time, control the carbonization time to 8 hours, add sodium chromate carbonized seed crystals to the carbonization tower after carbonization until the carbon dioxide in the solution reaches saturation, so as to facilitate the crystallization of sodium bicarbonate and the conversion of sodium chromate into dichromic acid sodium.

[0026] ⑤ Separation, use a plate and f...

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Abstract

The invention provides a process for preparing sodium dichromate, namely producing the sodium dichromate through a carbonization method comprising: converting sodium chromate into the sodium dichromate via carbon dioxide under pressurizing condition; delivering sodium chromate neutral liquor with impurities removed to a carbonization tower after a cascade reaction of more than three continuous towers; obtaining carbonizing liquor by controlling different gradient parameters (concentration and temperature of the carbonizing liquor, partial pressure of the carbon dioxide, carbonizing time and the like), continuously carbonizing and separating under pressure; obtaining sodium dichromate finished products through concentrating, filtering, evaporating, crystallizing and centrifugal dehydrating.

Description

technical field [0001] The present invention relates to the preparation method of red vitriol sodium in chromium salt industry. Background technique [0002] Sodium red alum (sodium dichromate) is an important basic chemical raw material, mainly used in the production of chemical products such as chromic anhydride, chrome yellow, chromium oxide green and potassium dichromate. It is used as an auxiliary agent in the printing and dyeing industry, electroplating industry and leather industry, and also as an oxidizing agent in the chemical industry and pharmaceutical industry. It has a wide range of applications. [0003] At present, the methods of making red vitriol sodium from sodium chromate in various countries in the world mainly include sulfuric acid method, electrolysis method and carbonization method. The sulfuric acid method is the method adopted by our country and most countries, but the disadvantage of the sulfuric acid method is the consumption of sulfuric acid, the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14
Inventor 李先荣张国庆马顺友陈宁秦龙董明甫尹天平王方兵张建军
Owner SICHUAN YINHE CHEM
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