Method for producing sodium chromate from potassium chromate

A technology for the production of sodium chromate and potassium chromate, applied in the direction of chromate/dichromate, etc., can solve the problems of polluted water body, soil and atmosphere, backward technology, and resource utilization rate of less than 20%, and it is easy to achieve engineering scale-up , simple equipment requirements and mild conversion conditions

Inactive Publication Date: 2014-04-02
INST OF PROCESS ENG CHINESE ACAD OF SCI
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Problems solved by technology

The current production technology of chromium chemical industry is backward, and it still follows the traditional process of high-temperature calcium roasting in the 1950s. The conversion rate of the main metal chromium is only 75%, and the resource utilization rate is less than 20%. Processing 1 ton of ore will produce 1.6 to 2.5 tons of high Toxic chromium slag, containing carcinogenic hexavalent chromium is thousands of times the national discharge standard, seriously polluting water, soil and air

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  • Method for producing sodium chromate from potassium chromate

Examples

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Effect test

Embodiment 1

[0020] Mix potassium chromate crystals and sodium nitrate crystals in a mass ratio of 2:1 to prepare an aqueous solution, raise the temperature to 90°C, and stir at a speed of 150min -1 After 30 minutes of complete dissolution and stability, the temperature began to drop, and the temperature was kept at a constant temperature for 30 minutes after dropping to 20°C. The liquid and solid phases were separated, and the coarse crystals of potassium nitrate were separated. Evaporate and concentrate the resulting crystallization mother liquor, repeat the cooling and crystallization process, raise the temperature to 90°C, and stir at a speed of 150min -1 , after lowering to 20°C, keep the constant temperature for 30min, vacuum filtration to separate the solid and liquid phases, and conduct multi-step vacuum evaporation and crystallization of the obtained crystallization mother liquor at 90°C to obtain Na 2 CrO 4 crystals.

Embodiment 2

[0022] Mix potassium chromate crystals and sodium nitrate crystals in a mass ratio of 1:1 to prepare an aqueous solution, raise the temperature to 70°C, and stir at a speed of 150min -1 After 30 minutes of complete dissolution and stability, the temperature began to drop, and the temperature was kept at a constant temperature for 30 minutes after dropping to 20°C. The liquid and solid phases were separated, and the coarse crystals of potassium nitrate were separated. Evaporate and concentrate the resulting crystallization mother liquor, repeat the cooling and crystallization process, raise the temperature to 70°C, and stir at a speed of 150min -1 After dropping to 20°C, the constant temperature was maintained for 30 minutes, and the solid-liquid two phases were separated by vacuum filtration, and the obtained crystallization mother liquor was subjected to multi-step vacuum evaporation and crystallization at 80°C to obtain Na 2 CrO 4 crystals.

Embodiment 3

[0024] Mix potassium chromate crystals and sodium sulfate crystals in a mass ratio of 1:2 to prepare an aqueous solution, raise the temperature to 60°C, and stir at a speed of 350min -1 After 60 minutes of complete dissolution and stability, the temperature began to drop, and the temperature was kept at a constant temperature for 60 minutes after dropping to 0°C. The liquid and solid phases were separated, and the coarse crystals of potassium sulfate were separated. Evaporate and concentrate the obtained crystallization mother liquor, repeat the cooling and crystallization process, raise the temperature to 60°C, and stir at a speed of 350min -1 , keep the constant temperature for 60 minutes after dropping to 0°C, vacuum filtration to separate the solid-liquid two phases, and the obtained crystallization mother liquor is subjected to multi-step vacuum evaporation and crystallization at 75°C to obtain Na 2 CrO 4 crystals.

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Abstract

The invention provides a method for producing sodium chromate from potassium chromate, which belongs to the technical field of inorganic salt production. In the method, sodium chromate is produced from potassium chromate through double decomposition and selective separation, and after potassium chromate and a certain sodium salt are dissolved and mixed in a certain ratio, KX is separated out through cooling crystallization, and then a Na2CrO4 product is obtained through evaporative crystallization. The method realizes efficient transformation from potassium chromate to sodium chromate and deep separation. In the method, potassium ions are first separated out through cooling crystallization, and then sodium chromate is separated out through evaporative crystallization, and evaporative crystallization mother liquor and low-purity sodium chromate coarse crystals are returned to a system for circulation and transformation. The method has the advantages of realizing the transformation from potassium chromate products to sodium chromate products by adopting an efficient clean energy-saving crystallization process, along with mild transformation conditions, strong operability, simple requirement on equipment and easy engineering amplification.

Description

technical field [0001] The invention belongs to the technical field of inorganic salt production, and in particular relates to a method for producing sodium chromate from potassium chromate, in particular to a method for producing sodium chromate through clean conversion of potassium chromate. Background technique [0002] Chromium salt industry is a key industry intersecting inorganic chemical industry and metallurgical materials. Chromium salt series products are important basic raw materials for chemical industry-light industry-advanced alloy materials. , leather, pigments, printing and dyeing, ceramics, anti-corrosion, catalysis, medicine and other departments, involving 10% of the national economy. The current production technology of chromium chemical industry is backward, and it still follows the traditional process of high-temperature calcium roasting in the 1950s. The conversion rate of the main metal chromium is only 75%, and the resource utilization rate is less t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/14
Inventor 徐红彬张翊高毅颖李平肖清贵张懿李佐虎
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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