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Preparation method of sodium bichromate

A kind of technology of sodium red vanadium and crystal seed, applied in the field of preparing sodium vanadium, and can solve the problems of complicated process control, product quality influence, mirabilite and waste residue pollution and the like

Active Publication Date: 2012-08-29
SICHUAN YINHE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method also has the pollution problem of chromium-containing Glauber's salt and waste residue to the environment, and the introduction of phosphate has a certain impact on product quality
Chinese patent application publication CN 1037495 uses sulfuric acid and chromium-containing sodium bisulfate to convert sodium chromate into sodium dichromate. During the production process, a large amount of chromium-containing mirabilite and waste residue are discharged, causing serious environmental pollution.
The process control of the method is complex and the production cost is high

Method used

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  • Preparation method of sodium bichromate
  • Preparation method of sodium bichromate
  • Preparation method of sodium bichromate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] ①Will 0.5m 3 Take Na 2 Cr 2 o 7 2H 2 The concentration of chromium compound in O is 750g·L -1 The aqueous solution containing sodium chromate is added into a single carbonization reactor, and the aqueous solution is obtained by neutralizing the sodium chromate alkaline solution obtained in the industrial process of roasting chromite to produce sodium chromate through carbon dioxide and removing aluminum. Aqueous solution of sodium bicarbonate;

[0051] ② Continuously feed a mixed gas containing 80% by volume of carbon dioxide and 20% by volume of air into the carbonization reactor, control the partial pressure of carbon dioxide in the carbonization reactor to 1.2MPa and the reaction temperature to 95°C, and keep it under this condition for 7.5h;

[0052] ③The carbonized feed liquid obtained in step ② is separated from solid and liquid using a vacuum belt filter to obtain carbonized liquid and sodium bicarbonate crystals. 2 Cr 2 o 7 2H 2 The concentration of chr...

Embodiment 2

[0055] ①Will 0.5m 3 Take Na 2 Cr 2 o 7 2H 2 The concentration of chromium compound in O is 1300g·L -1 The aqueous solution containing sodium chromate is added in three carbonization reactors connected in series, and the aqueous solution is obtained by neutralizing and removing aluminum from the sodium chromate alkaline solution obtained in the process of roasting chromite ore in the industry to produce sodium chromate Aqueous solutions containing sodium chromate;

[0056] ② Continuously feed a mixed gas containing 85% by volume of carbon dioxide and 15% by volume of air into the carbonization reactor, control the partial pressure of carbon dioxide in the three reactors to be 1.0MPa and the reaction temperature to be 30°C, and maintain 1.0h, that is, the total residence time from entering the first reactor to flowing out of the third reactor is 1h;

[0057] 3. The carbonized feed liquid obtained in step 2. adopts a vacuum belt filter to carry out solid-liquid separation t...

Embodiment 3

[0060] ①Will 0.5m 3 Take Na 2 Cr 2 o 7 2H 2 The concentration of chromium compound in O is 950g·L -1 The aqueous solution containing sodium chromate and 45kg sodium bicarbonate seed crystals are added in a single carbonization reactor. And the aqueous solution containing sodium chromate obtained by removing aluminum;

[0061] ② Continuously feed a mixed gas containing 10% by volume of carbon dioxide and 90% by volume of air into the carbonization reactor, control the partial pressure of carbon dioxide in the carbonization reactor to 0.1MPa and the reaction temperature to 15°C, and keep it under this condition for 8.0h;

[0062] 3. The carbonized feed liquid obtained in step 2. is separated from solid and liquid by a membrane filter press to obtain carbonized liquid and sodium bicarbonate crystals. The carbonized liquid is prepared with Na 2 Cr 2 o 7 2H 2 The concentration of chromium compound in O is 950g·L -1 , and the transformation rate of sodium chromate into sod...

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Abstract

The invention provides a preparation method of sodium bichromate. The preparation method comprises the following steps of: (1) adding 700-1,350 g.L<-1> sodium chromate neutral solution of a chromium compound in terms of Na2Cr2O7.2H2O into a carbonization reactor; (2) continuously supplying carbon dioxide into the carbonization reactor, and controlling partial pressure of carbon dioxide to be 0.01-1.5 MPa, reaction temperature to be 15-105 DEG C and reaction time to be 0.5-8.0 h; (3) separating carbonized feed liquid obtained by the step (2) to obtain carbonized liquid and sodium bicarbonate crystals, wherein the concentration of the chromium compound in the carbonized liquid is 700-1,350 g.L<-1> in terms of Na2Cr2O7.2H2O; and (4) crystallizing and dehydrating the carbonized liquid to obtain the sodium bichromate. By preparing the sodium bichromate through the preparation method, the conversation rate from the sodium chromate to the sodium dichromate can reach 95-100 percent, the quality of the sodium bichromate is high, and the sulfate content is less than 0.1 percent by weight.

Description

technical field [0001] The invention relates to a method for preparing sodium rubidium by carbonization. Background technique [0002] Sodium red alum is a basic inorganic chemical raw material, mainly used to manufacture chromium salt products such as chromic anhydride, basic chromium sulfate, chromium oxide green, etc. It is widely used in printing and dyeing, electroplating and other industries, and occupies an important position in the national economy. [0003] At present, the main production methods of domestic red alum sodium include sulfuric acid method, sodium bisulfate method and electrolysis method, among which sulfuric acid method is the main production process adopted. However, the sulfuric acid method consumes a lot of acid and alkali, the utilization rate of sodium ions is low, and a large amount of chromium-containing sodium sulfate is discharged during the production process, causing serious environmental pollution. The sodium bisulfate method uses the wast...

Claims

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Application Information

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IPC IPC(8): C01G37/14
Inventor 李先荣陈宁张国庆王方兵郑远川
Owner SICHUAN YINHE CHEM
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