Method for treating chromite by sulfuric acid leaching

Abstract

The invention discloses a method for treating chromite by sulfuric acid leaching, which comprises the following steps of: grinding the chromite into mineral powder, adding sulfuric acid into the mineral powder, stirring the mixture, and adding an oxidant into the mixture, wherein the oxidant is chromic anhydride, potassium chlorate or ammonium persulphate, and the adding amount of the oxidant is 0.2 to 7 percent of the mass of the mineral powder; heating the mixture at the temperature of between 120 and 190 DEG C for 30 to 90 minutes under the pressure of between 0.2 and 1.2MPa, filtering the reaction products after the reaction is finished, and performing solid-liquid separation, wherein the filter residue is directly used as a raw material for melting silicon iron; and removing iron from the filtrate to obtain chromium sulfate solution, and further preparing chromium sulfate by a direct crystallization method. Compared with the prior art, the method has the most remarkable characteristics of short process flow and no 'three-waste' emission. The filter residue does not contain hexavalent chromium, and the weight of the filter residue is light and only about 10 percent of the weight of the chromite, so the filter residue can be used as the raw material for melting the silicon iron.

Description

technical field [0001] The invention belongs to the technical field of mineral processing, and relates to the processing technology of chromite, in particular to a method for treating chromite by sulfuric acid leaching. Background technique [0002] At present, the preparation process of chromium salt mostly uses chromite as raw material, adopts calcification roasting process, not only the process is long, but also a large amount of Cr 6+ waste, and this waste has been listed as the top priority of solid waste management by countries all over the world. The main production processes of chromium salts are as follows: [0003] (1) Calcium roasting of chromite - soda ash leaching - impurity removal - concentration - acidification - denitrification - crystallization - sodium dichromate - reduction - chromium sulfate solution (not only the production of 1 ton of sodium dichromate contains Cr 6+ The waste residue is about 2.5 tons, and a large amount of hexavalent chromium solut...

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Problems solved by technology

[0003] (1) Calcium roasting of chromite - soda ash leaching - impurity removal - concentration - acidification - denitrification - crystallization - sodium dichromate - reduction - chromium sulfate solution (not only the production of 1 ton of sodium dichromate contains Cr 6+ The waste residue is about 2.5 tons, and a large amount of hexavalent chromium solution is also produced, and the recovery rate of chromium is as low as 75%~82%);

[0004] (2) Calcium-free roasting of chromite - soda ash leaching - impurity removal - concentration - acidification - denitrification - crystallization - sodium dichromate - reduction - chromium sulfate solution (not only the production of 1 ton of sodium dichromate contains Cr 6+ The waste residue is about 1 ton, and a large amount of hexavalent chromium solution is also produced, and the chromium recovery rate is as low as 70%~82%);

[0006] (4) Chromite sulfuric acid leaching under normal pressure, the main component of tailings is silica, and the consumption of oxidant and sulfuric acid is large (not industrialized production)

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