Method for preparing anhydrous sodium sulfate from chromium-containing mirabilite

Abstract

The invention relates to the field of a chemical industry and particularly relates to a method for preparing anhydrous sodium sulfate from chromium-containing mirabilite as a by-product in the production process of sodium dichromate. The method comprises dissolving a certain concentration of chrome-containing mirabilite in chromium-containing waste water, adding quantitative sodium thiosulfate into the waste water to promote reduction of hexavalent chromium into trivalent chromium under 0.1-1 Mpa at 80-190 DEG C, wherein the trivalent chromium in a form of chromium trioxide hydrate is precipitated, adding a small amount of sulfuric acid to neutralize, filtering to acquire the chromium trioxide hydrate, removing impurities, carrying out decoloration, evaporating to precipitate anhydrous sodium sulfate crystals, and carrying out continuous centrifugal separation and drying. The method is simple and easy, utilizes cheap raw materials, has low energy consumption and a high automation degree and is suitable for large-scale production. The quality of the industrial anhydrous sodium sulfate product obtained by the method meets the requirements of class I products in the GB / T 6009-2014 industrial anhydrous sodium sulfate standard.

Description

technical field

[0001] The invention relates to the field of chemical industry, in particular to a method for preparing anhydrous sodium sulfate by utilizing chromium-containing Glauber's salt, a by-product in the production process of sodium dichromate. Background technique

[0002] Before 2000, the total annual production of sodium dichromate in my country's chromium salt enterprises was less than 100,000 tons, and the total amount of by-product chromium-containing Glauber's salt was about 130,000 tons. Sodium sulfate water, but due to the small production scale of sodium dichromate and the low output of by-product chromium-containing Glauber's salt, the cost of using chromium-containing Glauber's salt to prepare industrial anhydrous sodium sulfate is higher than the cost of directly using natural Glauber's salt to produce anhydrous sodium sulfate. This kind of research was terminated, and the dried chromium-containing Glauber's salt was used as a cement accelerator instead....