Prepn of chromium subsulfate

Abstract

The preparation process of chromium subsulfate with chromite as material includes grinding; reacting with sulfuric acid at 110-170deg.c via stirring and under the presence of catalyst for 1-8 hr; filtering to separate filtrate and slag silica; regulating the free acid value of the filtrate with alkali to 0.8-3.1 %, adding crystal seed calcium salt, magnesium salt or chromium oxide and ferric oxide under stirring at 130-190 deg.c for 30-120 min; filtering to eliminate iron-containing slag, neutralizing the filtered mother liquid with sodium carbonate to base content of 33 %, and drying the mother liquid to obtain product chromium subsulfate; with the iron-eliminating filtered slag being produced into iron oxide red via conventional technological process. The said process is short, exhausts no toxic effluent, no slag and no waste gas, and has no environmental pollution.

Description

technical field

[0001] The invention relates to a preparation method of chromium salt, in particular to a preparation method of chromium sulfate. Background technique

[0002] At present, most of the preparation methods of basic chromium sulfate at home and abroad are based on dichromate as raw material. There are mainly the following methods: the organic matter reduction method is to use sulfuric acid or (NaHSO 4 Solution) after acidification, it is made by reduction with organic matter reducing agents such as sucrose, maltose or sawdust: sulfur dioxide reduction method, SO2 is passed into the solution of sodium dichromate 2 Production: In addition, there are carbon ferrochrome method, neutralization method, recovery method, formaldehyde method, chromium salt preparation method from waste chromium leather slag, etc. The traditional sodium dichromate production method is to calcinate chromite, sodium carbonate and lime powder in a certain proportion, after water immersion a...

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