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Clean production method for preparing potassium chromate from chromic iron

A technology of potassium chromate and chromite, applied in the direction of chromate/dichromate, etc., can solve problems such as reducing KOH, and achieve the effect of reducing corrosion, improving industrial operability, and reducing the requirements for corrosion resistance.

Inactive Publication Date: 2009-07-15
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The addition of KNO proposed in this patent 3 It is original to control the properties of KOH sub-molten salt, thereby reducing the amount of KOH, and there is no report in this area at home and abroad.

Method used

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  • Clean production method for preparing potassium chromate from chromic iron
  • Clean production method for preparing potassium chromate from chromic iron

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] KOH-KNO recycled back to the reactor 3 -H 2 O medium, heat up to 300°C after adding KOH, 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 the weight ratio of KOH to ore is 2: 1. KNO 3 The weight ratio with ore is 0.5:1. Finally get KOH-KNO 3 -H 2 The mixed reaction product of O medium, chromium salt and iron slag, the conversion rate of chromium is 99%. The mixed reaction product is leached with water, and the temperature after leaching is 90°C; the lye containing potassium nitrate is first separated from the leaching slurry, and then the iron slag is separated from the potassium chromate leaching solution; the impurity content to be removed is 1.5 times Calcium oxide was added into the potassium chromate solution, and the precipitate was removed by filtration after the reaction was completed; the pure potassium chromate solution was evaporated and crystallized, and...

Embodiment 2

[0030] KOH-KNO recycled back to the reactor 3 -H 2O medium, heat up to 330°C after adding KOH, add >95% chromite with a particle size of less than 200 mesh, feed oxygen, and react for 4 hours under the condition of complete mixing, wherein the weight ratio of KOH to ore is 1.5: 1. KNO 3 The weight ratio with ore is 1:1. Finally get KOH-KNO 3 -H 2 The mixed reaction product of O medium, chromium salt and iron slag, the conversion rate of chromium is 99%. The mixed reaction product is leached with water, and the temperature after leaching is 150°C; the lye containing potassium nitrate is first separated from the leaching slurry, and then the iron slag is separated from the potassium chromate leaching solution; the impurity content to be removed is 1.5 times Calcium oxide is added into the potassium chromate solution, and the precipitate is removed by filtration after the reaction is completed; the pure potassium chromate solution is evaporated and crystallized, and the crys...

Embodiment 3

[0032] KOH-KNO recycled back to the reactor 3 -H 2 O medium, heat up to 390°C after adding KOH, add >95% chromite with a particle size of less than 200 mesh, feed air, and react for 1 hour under the condition of complete mixing, wherein the weight ratio of KOH to ore is 1: 1. KNO 3 The weight ratio with ore is 1.5:1. Finally get KOH-KNO 3 -H 2 The mixed reaction product of O medium, chromium salt and iron slag has a chromium conversion rate of 99%, and the chromium content in the slag is 0.06%. The mixed reaction product is leached with water, and the temperature after leaching is 90°C; the lye containing potassium nitrate is first separated from the leaching slurry, and then the iron slag is separated from the potassium chromate leaching solution; the impurity content to be removed is 1.5 times Calcium oxide was added into the potassium chromate solution, and the precipitate was removed by filtration after the reaction was completed; the potassium chromate solution was e...

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Abstract

The invention belongs to the field of a method for producing chromic salt, in particular relates to a method for producing and cleaning potassium chromate. The method comprises the steps that chromite is reacted with oxidant with a chemical dose inside KOH-KNO3-H2O medium to obtain a mixed resultant of reaction containing alkali liquor, potassium chromate and slag after reaction, wherein the mass ratio of KOH and chromite is 1:1 to 2:1, and the mass ratio of KNO3 and chromite is 0.5:1 to 2:1. Through the leaching of the mixed resultant of reaction, the phases of potassium chromate macrocrystal-alkali liquor containing potassium nitrate-slag are separated, foreign matters in the solution are removed, the mixture is evaporated and crystallized, the obtained potassium chromate crystal is eluted and the pure product of potassium chromate is obtained. The percent conversion of chromium is higher than 99 percent and the rate of containing chromium in slag is less than 0.2 percent.

Description

technical field [0001] The invention belongs to the field of production methods of chromium salts, and in particular relates to a clean production method of potassium chromate. Background technique [0002] Potassium chromate is an important industrial chemical, mainly used in enamel, leather tanning, metal anticorrosion and analytical reagents, and can also be used as a raw material for the preparation of other chromium compounds. [0003] The existing production methods of potassium chromate mainly include neutralization method, decomposition method, double decomposition method and potash-alkali roasting method, etc. For details, see Ding Yi and Ji Zhu's treatise "Production and Application of Chromium Compounds" and Cheng Siwei's treatise "Chromium Compound Production and Application" Salt Production Process". And in actual industrial production, the production method that generally adopts at home and abroad is the preparation technology that takes sodium chromate as raw...

Claims

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Application Information

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IPC IPC(8): C01G37/14
Inventor 郑诗礼孙峙张洋张懿
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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