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Method for preparing pigment grade chromium hemitrioxide green by using gaseous reducing agent to reduce chromate salt under low temperature

A technology of chromium oxide green and reducing agent, which is applied in the direction of chromium oxide/hydrate, fibrous filler, etc., can solve the problems of complex reaction equipment, high reaction temperature, and large energy consumption, and achieve simple equipment, mild process conditions, and realization of The effect of zero emissions

Inactive Publication Date: 2011-06-01
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

However, the reaction temperature of this method is too high, so that the energy consumption is very large; moreover, it is necessary to feed gas that can form salts with the reaction by-products, and the reaction equipment is complex

Method used

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  • Method for preparing pigment grade chromium hemitrioxide green by using gaseous reducing agent to reduce chromate salt under low temperature

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] The reduction of 100kg of potassium chromate is carried out in an electrothermal rotary reduction furnace, using hydrogen as the reducing gas, the reduction temperature is 450°C, the reduction time is 2h, and the hydrogen flow rate during the reduction process is 40Nm 3 / h.

[0015] After the reduction product is cooled, three-stage countercurrent washing is used. The liquid-solid volume ratio during the washing process is 1.00-1.05, and the washing temperature is 60°C. After washing, use a plate and frame filter press to filter, the moisture content of the filter cake is about 25%, and the filtered liquid recovers KOH for recycling. filter cake with 0.5wt% P 2 o 3 、HBO 3 , Zn(NO 3 ) 2 , SiO 2 、TiO 2 Ball milling and mixing in a ball mill, and the mixed material enters a rotary kiln for activation and sintering at a sintering temperature of 900°C and a sintering time of 3 hours. After sintering, the material is countercurrent washed, spin flash dried, and after ...

Embodiment 2

[0017] The reduction of 100kg of sodium chromate is carried out in an electrothermal rotary reduction furnace, using natural gas as the reducing gas, the reduction temperature is 400°C, the reduction time is 1.5h, and the natural gas flow rate during the reduction process is 60Nm 3 / h.

[0018] After the reduction product is cooled, three-stage countercurrent washing is used. The liquid-solid volume ratio during the washing process is 1.00-1.05, and the washing temperature is 70°C. After washing, use a plate and frame filter press to filter, the moisture content of the filter cake is about 25%, and the filtered liquid recovers NaOH for recycling. filter cake with 1.0wt% Al 2 o 3 、H 3 PO 4 , SiO 2 、K 2 TiO 3 , Sb 2 o 3 , ZnO is ball milled and mixed in a ball mill, and the mixed material is sent into a rotary kiln for activation and sintering at a sintering temperature of 950°C and a sintering time of 2.5 hours. After sintering, the material is countercurrent washed, ...

Embodiment 3

[0020] The reduction of 100kg of potassium chromate is carried out in an electrothermal rotary reduction furnace, using coal gas as the reducing gas, the reduction temperature is 500°C, the reduction time is 1h, and the gas flow rate during the reduction process is 80Nm 3 / h.

[0021] After the reduction product is cooled, three-stage countercurrent washing is used. The liquid-solid volume ratio during the washing process is 1.00-1.05, and the washing temperature is 80°C. After washing, use a plate and frame filter press to filter, the moisture content of the filter cake is about 25%, and the filtered liquid recovers KOH for recycling. filter cake with 1.5wt% H 3 PO 4 , Al(OH) 3 、TiO 2 , SiO 2 , ZnO is ball milled and mixed in a ball mill, and the mixed material is sent into a rotary kiln for activation and sintering. The sintering temperature is 1000°C and the sintering time is 2h. After sintering, the material is countercurrent washed, spin flash dried, and after dryin...

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Abstract

The invention discloses a method for preparing pigment-grade chromium oxide green. The method comprises the steps of taking reducing gas as a reducing agent, allowing chromic salt to react with the reducing gas for 1-2 hours at a temperature between 300 and 550 DEG C, cooling, using water to wash and hydrolyzing a reaction mixture, mixing the reaction mixture with additives at a temperature between 900 and 1,100 DEG C, activating and sintering the reaction mixture and the additives for 1-3 hours, washing, drying and grading the sintered material to obtain the pigment-grade chromium oxide green, wherein the chromic salt is chromate or bichromate; the reducing gas is hydrogen, natural gas, ammonia gas, coal gas or a mixture thereof; and the additives are silicon compounds, titanium compounds, boron compounds, phosphorus compounds, aluminum compounds, barium compounds, zinc compounds and other compounds, such as SiO2, TiO2, K2TiO3, HBO3, H3PO4, P2O3, Al2O3, Al(OH)3, BaO, Ba(OH)2, ZnO, Zn(NO)3, Sb2O3, Sb2O3 and other substances.

Description

technical field [0001] The invention relates to a method for preparing calcined metal oxide pigments, in particular to a method for preparing pigment-grade chromium oxide green by reducing chromium salts with a gas reducing agent at low temperature Background technique [0002] Pigment-grade chromium oxide green is mainly used in coatings, paints, plastics, rubber, chemical fibers, textiles, ceramics, colored cement and other fields, as well as cosmetics, tapes, food, adhesives, electrostatic copying, etc. The chromium oxide green product used as a pigment has high quality requirements and must have good pigment performance, including shade, tinting strength, hiding power, etc. [0003] The production of chromium oxide green pigment mainly adopts ammonium sulfate-sodium red alum thermal decomposition method (US4,040,860) and chromic anhydride thermal decomposition method. The preparation of pigment-grade chromium oxide green by thermal decomposition of ammonium sulfate-sodi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G37/02C09C1/34
Inventor 徐红彬李平张懿李佐虎白玉兰
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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