Method for preparing chrome green by two-stage process

Abstract

The invention relates to a method for preparing chrome green, in particular to a two-stage process technique for preparing chrome green by heating and roasting chromic anhydride. The method comprises the following steps: weighing chromic anhydride by using weighing equipment and placing in a material vehicle; delivering the material vehicle to a tunnel furnace, and heating at 450 to 530 DEG C for1 to 3 hours; cooling and grinding the material, wherein the particle size is kept between 2 and 6 millimeters; delivering the material into a rotary kiln and roasting at 1,000 to 1,100 DEG C for 1 to 2 hours; and cooling the roasted material and grinding to obtain chrome green powder with a particle size between 0.01 to 0.1 millimeters. The two-stage process technique for preparing chrome green has high heat utilization rate, short reaction time and high automation degree, reduces emission of chromium-containing tail gas and makes the tail gas reach standards more easily for discharge.

Description

technical field [0001] The invention relates to a method for producing chrome green, specifically a two-stage process for producing chrome green by heating and roasting chromic anhydride. Background technique [0002] The scientific name of chrome green is chromium trioxide, also known as chromium oxide, which is a green powder specially used for pigments. Chrome green has good pigment properties (shade, coloring power, oil absorption, hiding power, specific surface area, etc.); chromium oxide for abrasives has regulations on particle size, polishing power, surface roughness, etc. [0003] At present, domestic and foreign roasting equipment that uses thermal decomposition of chromic acid to manufacture isolation is generally earth furnace, reverberatory furnace, tunnel kiln, and the thermal efficiency of the equipment is only 35-50%. The fuel used is coal, oil, etc., and the raw material used is chromic acid. Although it can achieve the purpose of roasting and preparing chr...

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Problems solved by technology

Although it can achieve the purpose of roasting and preparing chrome green, it has the following problems in actual use: 1. Due to the direct contact between the raw material and the fuel, the temperature of the tail gas containing chromium is high, and the amount of tail gas is large, which is difficult to handle; 2. The reaction time of raw materials Long, generally 8-12 hours, the productivity of the equipment is low; 3, the raw materials entering the roasting equipment are fed manually, the degree of automation is poor, and the labor intensity of the employees is high