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Method of preparing chromium oxide using precarbonation wet reducing potassium chromate or sodium chromate

A potassium chromate and carbonation technology, applied in the directions of chromium trioxide, chromium oxide/hydrate, etc., can solve the problems of environmental pollution product quality and high production cost, and achieve the improvement of reduction conversion rate, reduction of production cost and shortening of technological process. Effect

Inactive Publication Date: 2003-04-16
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

[0004] The purpose of the invention is to overcome defects such as high production cost, polluted environment and low product quality existing in the existing production of chromium oxide, and to provide a method for preparing chromium oxide by using pre-carbonated wet reduction of potassium chromate or sodium chromate. While reducing production costs and simplifying the production process, realize no pollutant discharge in any form, and achieve the goal of controlling pollution from the source

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Example 1, without carbonation, an intermediate product for preparing chromium oxide was obtained.

[0041] Preparation concentration is 40% potassium chromate aqueous solution, will 333.33g40%K 2 CrO 4 Aqueous solution with 17.67gC 12 h 22 o 11 Placed in a hot-pressed reaction kettle, the sucrose is 120 mol% of potassium chromate according to the stoichiometric ratio, heated to 120°C under electric stirring to start the reaction, stop heating, and the reaction continues to rely on the heat released by itself. The maximum temperature is 160°C, and the maximum pressure is 0.4MPa. It is difficult to filter the slurry after the reaction. The conversion rate was 40.42%.

Embodiment 2

[0042] Example 2, without calcination, an intermediate product for preparing chromium oxide is obtained.

[0043] Preparation concentration is 40% potassium chromate aqueous solution, will 333.33g40%K 2 CrO 4 Aqueous solution with 17.67gC 12 h 22 o 11 Put it in a hot-pressed reaction kettle, the sucrose is 120 mol% of potassium chromate according to the stoichiometric ratio, heat up to 30°C under electric stirring, and pass in CO 2 Gas is carbonated, CO 2 The pressure is 0.4 MPa, the carbonation time is 30 min, and the stirring rate is 1000 rpm. Then heat up to 120°C to start the reaction, stop heating, and the reaction will continue to rely on the heat released by itself. The maximum temperature in the system is 170°C, and the maximum pressure is 0.5MPa. The conversion rate was 68.92%.

Embodiment 3

[0044] Embodiment 3. Obtain the intermediate product of preparing chromium oxide without calcining.

[0045] Preparation concentration is 40% potassium chromate aqueous solution, will 333.33g40%K 2 CrO 4Aqueous solution with 17.67gC 12 h 22 o 11 Put it in a hot-pressed reaction kettle, the sucrose is 120 mol% of potassium chromate according to the stoichiometric ratio, heat up to 30°C under electric stirring, and pass in CO 2 Gas is carbonated, CO 2 The pressure is 0.6 MPa, the carbonation time is 30 min, and the stirring rate is 1000 rpm. Then heat up to 120°C to start the reaction, stop heating, the reaction continues to rely on the heat released by itself, the highest temperature in the system is 190°C, the highest pressure is 0.7MPa, the slurry after the reaction is difficult to filter. The conversion rate was 82.08%.

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Abstract

A process for preparing chromium oxide from potassium (or sodium) chromate by the pre-carbonating and wet reduction method includes such steps as preparing the aqueous solution of potassium (or sodium) chromate, pre-carbonating by CO2 gas, reducing by a reducer to obtain the hydrate of chromium oxide, filtering, drying, high-temp. calcining under protection of inertial gas, washing and drying to obtain the alpha-Cr2O3.

Description

technical field [0001] The invention belongs to the manufacturing technology of inorganic materials, in particular to a method for preparing chromium oxide by adopting a pre-carbonation wet method to reduce potassium chromate or sodium chromate. Background technique [0002] Chromium oxide, also known as chromium trioxide or chromium oxide green, is one of the leading products in the chromium salt industry. It is widely used as a green pigment, a raw material for smelting metal chromium, and a catalyst in organic synthesis. The purpose of its production is also mainly It is carried out around the use of these two aspects. As a pigment, it has higher requirements on the particle size and crystal form of chromium oxide, but less on the purity requirements, and sometimes other substances need to be introduced in order to improve its pigment performance such as coloring power; Chromium has higher requirements on its purity, especially the most stringent r...

Claims

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Application Information

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IPC IPC(8): C01G37/033
Inventor 姚芝茂张懿李佐虎
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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