Clean production method of potassium chromate

A clean production and potassium chromate technology, applied in the direction of chromate/dichromate, etc., can solve the problems of serious environmental pollution, low yield of potassium chromate, high energy consumption, etc., achieve dust-free waste gas, and improve chromium recovery The effect of rate and reaction process enhancement

Inactive Publication Date: 2003-04-16
中蓝义马铬化学有限公司
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  • Abstract
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Problems solved by technology

[0004] The object of the invention is to overcome the defects of high energy consumption, serious environmental pollution and low yield of potassium chromate that exist in the existing potassium chromate production method, and provide a kind of clean production method of potassium chromate with industrial operability, To replace the existing high-temperature sodium-alkali roasting method, and replace sodium chromate with potassium chromate as the raw material for the production of other chromium series chemical products

Method used

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  • Clean production method of potassium chromate

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Effect test

Embodiment 1

[0030] Please see attached image. Circulate the KOH solution returned to the reactor to remove part of the water, then heat up to 250°C, add 95% chromite with a particle size of less than 200 mesh, add potassium peroxide, and react for 6 hours under complete mixing conditions, wherein KOH and ore The weight ratio is 2:1; a mixed reaction product containing lye, chromium salt and iron slag is obtained; the conversion rate of chromium is above 99%. The mixed reaction product is leached with iron slag washing solution, and the temperature after leaching is 80°C; the leaching slurry is separated at 60°C to separate the coarse crystals of potassium chromate, and the iron slag and lye are separated by filtration; the coarse crystals of potassium chromate are added with water Dissolve and filter to remove a small amount of iron slag; add carbon dioxide to the potassium chromate solution to adjust pH = 6, separate and remove impurities to obtain pure potassium chromate solution; the p...

Embodiment 2

[0032] Please see attached image. The KOH solution that circulates back to the reactor removes part of the water and heats up to 320°C. Add 95% of the chromite with a particle size of less than 200 meshes, introduce air, and react for 3 hours under complete mixing conditions. Among them, the weight ratio of KOH to ore The ratio is 4:1, and the mixed reaction product containing lye, chromium salt and iron slag is obtained; the conversion rate of chromium is over 99%. The mixed reaction product is leached with iron slag washing solution, and the temperature after leaching is 140°C; the leaching slurry is separated at 110°C to separate the coarse crystals of potassium chromate, and the iron slag and lye are separated by filtration; the coarse crystals of potassium chromate are added with water Dissolve and filter to remove a small amount of iron slag; add potassium dichromate to the potassium chromate solution to adjust the pH=7, filter and separate to remove impurities to obtain...

Embodiment 3

[0034] Please see attached image. Circulate the KOH solution returned to the reactor to remove part of the water, then heat up to 400°C, add 95% chromite with a particle size of less than 200 mesh, add potassium nitrate, and react for 1 hour under complete mixing conditions, wherein the weight ratio of KOH to ore The ratio is 6:1, and a mixed reaction product containing lye, chromium salt and iron slag is obtained; the conversion rate of chromium is above 99%. The mixed reaction product is leached with iron slag washing solution, and the temperature after leaching is 180°C; the leaching slurry is separated at 120°C to separate the coarse crystals of potassium chromate, and the iron slag and lye are separated by filtration; the coarse crystals of potassium chromate are added with water Dissolve with the crystalline mother liquor of Example 2, remove a small amount of iron slag by filtration; add chromic anhydride to the potassium chromate solution to adjust pH=8, filter and sep...

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Abstract

A clean process for preparing potassium chromate includes such steps as reaction of chromite on oxidant in the aqueous solution of KOH to obtain a mixture of alkali solution, chromium salt and iron dregs, immersion extracting, separating coarse crystal of potassium chromate from ion dregs, and alkali solution, dissolving the said coarse crystal, removing impurities and crystallizing. Its advantages are low reaction temp. (250-400 deg.C), high Cr recovering rate (20%) and reduced quantity of Cr dregs.

Description

technical field [0001] The invention belongs to the field of production methods of chromium salts, in particular to a clean production method of potassium chromate. Background technique [0002] Potassium chromate is mainly used in enamel, leather tanning, dyes, pigments, medicines, metals and anti-corrosion and analytical reagents, and can also be used as a raw material for preparing chromium series chemical products such as potassium dichromate, chromium oxide and chromic anhydride. [0003] The production of chromium salts from chromite is an important basic raw material industry intersecting chemical industry and metallurgy, involving more than 10% of the national economy. The production methods of existing potassium chromate include potash-alkali roasting method, neutralization method, decomposition method and double decomposition method, referring to Cheng Siwei's treatise "Chromium Salt Production Technology". The production method of chromium ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/14
Inventor 郑诗礼张懿李佐虎王志宽齐涛
Owner 中蓝义马铬化学有限公司
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