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Method for producing sodium chromate and co-producing chrome-containing cast iron by three-stage process through un-calcium roasting

A calcium-free roasting and sodium chromate technology, applied in the direction of chromate/dichromate, etc., can solve the problems of low roasting efficiency and large energy loss

Inactive Publication Date: 2014-11-12
INNER MONGOLIA CHROMIUM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a three-stage calcium-free roasting method for producing sodium chromate and co-producing chromium-containing cast iron, so as to solve the problems of low roasting efficiency and large energy loss in the existing calcium-free roasting production of chromium salt

Method used

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  • Method for producing sodium chromate and co-producing chrome-containing cast iron by three-stage process through un-calcium roasting

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] A, one stage roasting process: with 1000 tons of South African chromite (main chemical composition is: Cr 2 o 3 42.8%, Fe 2 o 3 26.57%, MgO8.22%, Al 2 o 3 18.62%, SiO 2 3.46%, V 2 o 5 0.33%) ground to 200 mesh pass rate greater than 95%, and 250 tons of Jinchang soda ash (Na 2 CO 3 Content: 98.62%) mixed evenly, mixing accuracy 99%,

[0018] B. Put the material into the rotary kiln at a rate of 5 tons per hour and roast at a temperature of 1100 ° C. The residence time of the material in the kiln for roasting is 120 minutes, and the material does not form a wall. The chromium conversion rate of one-stage roasting is 42.3%,

[0019] C. When the clinker obtained by roasting is cooled to 300°C, it enters the wet ball mill for grinding, and the liquid-solid ratio is controlled to be 65:35. The leached slurry is directly filtered through a belt filter, and the filtrate is a section of sodium chromate Alkaline liquid, obtains the sodium chromate alkaline liquid 1175...

Embodiment 2

[0025] After storing and drying the filtered chromium slag of the three-stage roasting in step E of Example 1, after mixing according to the ratio of chromium slag: silica: lime: coke = 68:10:5:17, pass through a high-temperature electric arc furnace according to the existing process Smelted into chromium-containing cast iron, the quality of chromium-containing cast iron is qualified. No hexavalent chromium was detected in the smelted ferrochrome slag, and the ferrochrome slag was piled up.

Embodiment 3

[0027] A, one stage roasting process: with 1000 tons of South African chromite (main chemical composition is: Cr 2 o 3 42.8%, Fe 2 o 3 26.57%, MgO8.22%, Al 2 o 3 18.62%, SiO 2 3.46%, V 2 o 5 0.33%) ground to 200 mesh pass rate greater than 95%, and 266 tons of Jinchang soda ash (Na 2 CO 3 Content: 98.62%) are mixed evenly, and the mixing accuracy is 99%.

[0028] B. Put the material into the rotary kiln at a rate of 5 tons per hour and roast at a temperature of 1250 ° C. The residence time of the material in the kiln for roasting is 120 minutes, and the material does not form a wall. The chromium conversion rate of one-stage roasting is 42.93%,

[0029] C. When the clinker obtained by roasting is cooled to 400°C, it enters the wet ball mill for grinding, and the liquid-solid ratio is controlled to be 65:35. The leached slurry is directly filtered through a belt filter, and the filtrate is a section of sodium chromate. Alkaline liquid, obtain 1192m sodium chromate alka...

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Abstract

The invention discloses a method for producing sodium chromate and co-producing chrome cast iron by a three-stage process through un-calcium roasting, aiming at solving the problems of low roasting efficiency and high energy consumption in the existing method for producing chromic salt by un-calcium roasting. The method for producing sodium chromate by the three-stage process through un-calcium roasting comprises the following steps of: A, mixing roasting material in a first stage, mixing chromite and sodium carbonate in proportion; B, roasting in the first stage, putting the mixed material in the first stage into a rotary kiln and performing oxidizing roasting; C, leaching and filtering in the first stage; D, performing second-stage roasting technology; and E, performing third-stage roasting technology. The leaching of clinker after roasting for three times is same as the roasting leaching in the first time and the second time, the grinding leaching is performed to the clinker by a wet grinding ball mill, the clinker is filtered by a belt type filter and the filtered chromium slag by three-stage roasting is obtained by filtering of the belt type filter, the filter liquor is sodium chromate alkali solution. Compared with the traditional un-calcium roasting technology, the method in the invention adopts the three-stage process un-calcium roasting technology and effectively reduces the mine consumption and the alkali consumption and has the energy-saving and emission-reducing effect.

Description

technical field [0001] The invention belongs to the field of inorganic salt chromium salt production, and relates to a method for producing sodium chromate by three-stage calcium-free roasting and co-producing chromium-containing cast iron. Background technique [0002] The traditional chromium salt production process mainly includes calcium roasting process and calcium-free roasting process. The biggest difference between calcium-free roasting process and calcium roasting process is whether to add calcium-containing substances. [0003] The calcium-free roasting process is compared with the calcium roasting process. Due to the small amount of slag discharge, high leaching rate, and low hexavalent chromium content in the slag, the calcium-free roasting process has incomparable advantages in environmental protection compared with the calcium roasting process. Calcium-free roasting process, on the premise of not adding calcium-containing substances, in order to reduce the comp...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/14
Inventor 邢永强
Owner INNER MONGOLIA CHROMIUM
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