Chromium-containing material strong oxidizing roast technique

A strong oxidation and material technology, which is applied in the field of inorganic salt production and resources and environment, can solve the problems of production efficiency limitation, chromium slag pollution, etc., and achieve the effect of improving production efficiency, effective treatment, and not easy to form rings

Inactive Publication Date: 2009-06-17
CENT SOUTH UNIV
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  • Summary
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AI Technical Summary

Problems solved by technology

Chinese patent (CN1104258) adopts the technique of calcium-free granulation and roasting to produce chromate, adding accelerator in the furnace charge, which solves the problem of kiln ring formation in the roasting process and reduces the roasting time; but this process still needs more than 70% of the The leaching slag is returned to the roasting system as filler, and the production efficiency is limited
This method can reduce the total chromium content in the chromium slag, but the chromium leaching rate in the slag is only about 60%, and the slag still needs further treatment, and the pollution problem of the chromium slag has not been solved

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Using a chromite ore in my country as raw material, the main chemical composition is: Cr 2 o 3 41.4%, MgO 8.63%, Fe 2 o 3 22.29%, Al 2 o 3 22.95%, SiO 2 4.24%. Chromite, soda ash and monazite (RE 2 o 3 52%) ground to less than 74μm, the dosage of soda ash is according to [Na 2 O] / [Cr 2 o 3 ] The molecular ratio is 2, and the amount of monazite added is 0.6% of that of chromite, and no return slag is added. Mix the materials evenly on the double-roller mixer; the mixed materials are sprayed with water to make pellets, the diameter of the pellets is 8-10mm, and the water content is 8%. Air oxidation for 90 minutes, the material does not form a wall. The chromium oxidation rate in the clinker is 99.2%. After the clinker is leached, filtered and washed with water, the hexavalent chromium content in the slag is less than 0.04%, and the total chromium content is about 0.65% (based on Cr 2 o 3 meter, the same below).

Embodiment 2

[0014] The raw materials, proportioning and pelletizing are the same as in Example 1. Wet pellets are put into the cold end of the rotary kiln, and after being gradually dried, they are oxidized and roasted in air at a high temperature section of 1150°C for 40 minutes. The material rolls well and does not form a wall. The chromium oxidation rate in the clinker is 99.1%. After the clinker is leached, filtered and washed with water, the hexavalent chromium content in the slag is 0.06%, and the total chromium content is 0.74%.

Embodiment 3

[0016] Raw material, pelletizing and roasting system are identical with embodiment 1, and difference is that the allotment amount of soda ash is changed into [Na 2 O] / [Cr 2 o 3 ] The molecular ratio is 2.2. When the pellets are oxidized and roasted in the rotary kiln, they will not form a wall. The chromium oxidation rate in the clinker is 99.5%.

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Abstract

The invention relates to technology for strongly oxidizing and roasting chromium-containing materials, which mainly comprises: adding calcined soda and a catalyst into the chromium-containing materials for uniform mixing; performing strong oxidizing roasting on mixed material pellets after using water to perform granulation on the mixed materials; and leaching oxidized and roasted clinker to obtain chromium lixivium and leached slag. The technology has the advantages of high oxidation rate and conversion rate of chromium, complete separation of the chromium and the slag, low content of the chromium in the leached slag, easy comprehensive utilization and so on, overcomes the defects of low chromium recovery rate, large chromium slag amount, high chromium content and heavy pollution in the prior process for producing chromium salt, can safely, economically and effectively treat a great deal of the prior high-toxicity chromium-containing waste, realizes harmlessness of the chromium-containing materials when simultaneously reclaiming the chromium, eliminates chromium pollution during production, and has obvious social, environmental and economic benefits.

Description

technical field [0001] The invention relates to a method for producing chromate by using chromium-containing materials through strong oxidation roasting technology, and belongs to the field of inorganic salt production and resource environment. Background technique [0002] Chromium-containing materials mainly include chromite ore, chromium slag, and chromium mud from the tanning process. Chromite ore is the main raw material for the production of chromium and chromium salts, chromium slag is the chromium-containing waste discharged from the production process of chromium and chromium salts, and chromium sludge is the chromium-containing waste discharged from the tanning process. The existing methods for producing chromium salts using chromium-containing materials all have problems such as low chromium conversion rate and recovery rate, serious chromium pollution, and the like. [0003] At present, the main production methods for producing chromium salt from chromite are di...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14
Inventor 李小斌齐天贵彭志宏刘桂华周秋生
Owner CENT SOUTH UNIV
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