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Method for preparing pigment-class chrome oxide green by adopting microwave heating

A microwave heating, chrome oxide green technology, applied in fibrous filler, dyeing physical treatment and other directions, can solve the problems of affecting quality and content, difficulty in industrialization, harsh production conditions, etc., to improve material properties, improve energy utilization, The effect of short sintering time

Inactive Publication Date: 2015-03-11
SICHUAN YINHE CHEM
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  • Abstract
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Problems solved by technology

[0003] In the CN101475218A document, a method for directly preparing pigment-grade chromium oxide green with chromium hydroxide is disclosed. The method uses additives to be calcined together with chromium hydroxide, which involves complex processes and is easy to introduce impurities, which affect the quality and content.
In the CN103449521A document, a method for preparing chromium oxide green pigments by hydrated chromium oxide is disclosed. The method controls the quality of chromium oxide green products by adjusting the preparation method of hydrated chromium oxide and the calcination process, and the quality requirements for hydrated chromium oxide are relatively high. High, and generally use high-quality sodium chromate or red alum sodium products as raw materials, and use special processes such as high-temperature hydrothermal environments to prepare hydrated chromium oxide green. The process is difficult, the production conditions are harsh, and industrialization is difficult.

Method used

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  • Method for preparing pigment-class chrome oxide green by adopting microwave heating

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Sulfur powder and water with a weight ratio of 1:1 are wet ground into slurry, take 40kg of sulfur slurry and 100kg of sodium chromate alkaline solution, heat them to 150°C in the reactor, stir and react, and take samples during the reaction to detect the reaction solution When the content of hexavalent chromium in the medium is less than 0.05g / L, the reaction is stopped, and then aged for 0.5h, the reaction solution is filtered, and the filter cake is washed in multi-stage countercurrent with 90°C water until The content of sodium thiosulfate in the filtrate is less than 0.05g / L, neutralize the washed precipitate with sulfuric acid to a pH value of 7.0, and then wash with a filter, remove the supernatant after the washed slurry is precipitated, and then centrifuge Dehydration to obtain chromium hydroxide, chromium hydroxide was calcined at 1300°C for 3 hours, then washed and dried to obtain chromium oxide.

[0027] Put 2.5kg of chromium oxide in a microwave sintering f...

Embodiment 2

[0029] Using the same method as in Example 1 to prepare chromium oxide, place 1.9kg of chromium oxide in a microwave sintering furnace, using a microwave frequency of 2450MHz, first raise the temperature to 100°C at a heating rate of 100°C / min, and then use 100°C as the temperature increase range , 50°C / min is the heating rate for heating and heating. Each temperature point is kept for 10 minutes until the temperature rises to 1000°C, and the heat is kept for 85 minutes. Dry to obtain 1.8kg pigment grade chromium oxide green, after testing its Cr 2 o 3 The content is 99.1wt%, meeting the standard of pigment-grade chromium oxide green.

Embodiment 3

[0031]Using the same method as in Example 1 to prepare chromium oxide, put 3.2kg of chromium oxide in a microwave sintering furnace, using a microwave frequency of 915MHz, first raise the temperature to 100°C at a heating rate of 50°C / min, and then use 100°C as the temperature increase range 100°C / min is the heating rate for heating and heating. Each temperature point is kept warm for 5 minutes until the temperature rises to 1200°C, and the heat is kept for 60 minutes. Dry to obtain 3.0kg pigment grade chromium oxide green, after testing its Cr 2 o 3 The content is 99.5wt%, meeting the standard of pigment-grade chromium oxide green.

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Abstract

The invention discloses a method for preparing pigment-class chrome oxide green by adopting microwave heating. The method comprises steps as follows: (1) placing chromic oxide into a microwave sintering furnace, heating the furnace to the temperature of 950-1,300 DEG C through microwave heating, and keeping the temperature for 1-2.5 h; (2) naturally cooling a product obtained in the step (1) to the temperature of lower than 100 DEG C, then leaching the product with distilled water for 3-5 times, and drying the product at the temperature of 60-100 DEG C to obtain the pigment-class chrome oxide green. The raw material, that is, the chromic oxide, is prepared by high-temperature calcination of chromic hydroxide, and the amorphous state of the chromic oxide can be recombined through microwave heating, so that the structure and the size of chromic oxide crystal particles are optimized, the chromic oxide turns dark green required by the pigment class from greyish green and yellowish green, meanwhile, the particles are enlarged, the washing efficiency is improved, the product purity is increased, and the pigment-class chrome oxide green with the content of the chromic oxide higher than 99wt% can be obtained. The method is simple in technology, low in cost and widely applicable to preparation of the pigment-class chrome oxide green.

Description

technical field [0001] The invention relates to a method for preparing pigment-grade chromium oxide green, in particular to a method for preparing pigment-grade chromium oxide green by heating chromium oxide with microwaves. Background technique [0002] Chromium oxide green is one of the four major products in the chromium salt industry. It has excellent chemical properties and thermal stability. It is mainly used in coatings, ceramics, art pigments and camouflage materials. The pigment industry is the most widely used field of chromium oxide green. . The industrial production of pigment-grade chromium oxide green often adopts ammonium sulfate-sodium red alum thermal decomposition method and chromic anhydride thermal decomposition method, but the requirements for equipment are relatively high, and impurities are easily generated and pollute the environment. At present, chromium oxide green is often produced by calcining chromium hydroxide. The process is simple, the cost i...

Claims

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Application Information

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IPC IPC(8): C09C1/34C09C3/04
Inventor 李先荣陈宁董明甫王方兵黄先东杨红梅
Owner SICHUAN YINHE CHEM
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