Process for producing sodium chromate from chromite through dissolution in acid and oxidization

Abstract

The invention discloses a process for producing sodium chromate from chromite through dissolution in an acid and oxidization. The chromite is dissolved in an acid and thus oxidized into hexavalent chromium; and then the hexavalent chromium is extracted from the mixed solution to obtain the sodium chromate product, and meanwhile other chemical material components in the chromite can be extracted and prepared into a series of chemical products. The whole process flow has no slag discharged and causes no secondary pollution; and the whole process is clean, energy-saving and environment-friendly, so that the economic benefit and social benefit of an enterprise can be greatly improved.

Description

technical field [0001] The invention relates to a process for preparing sodium chromate by oxidizing acid-soluble chromite, which belongs to the technical field of directly preparing sodium chromate by using chromite as a raw material, dissolving and oxidizing chromium into hexavalent chromium by adding acid. Background technique [0002] Chromium salt production has generally adopted several production methods since its birth: calcium roasting, calcium-less roasting, calcium-free roasting, potassium-based sub-molten salt liquid-phase oxidation, pneumatic fluidized tower continuous liquid-phase oxidation, etc. These methods Both use chromite as raw material to prepare sodium chromate through roasting or high-temperature oxidation with alkali. In fact, the biggest shortcoming of all these methods for producing chromium salts is the difficult problem of processing the chromium slag produced in the production process. [0003] Calcium roasting produces a large amount of chromi...

AI Technical Summary

Problems solved by technology

In fact, one of the biggest disadvantages of all these methods for producing chromium salts is the difficulty in handling the chromium slag generated during the production process.

[0003] The amount of chromium slag produced by roasting with calcium is large, causing serious environmental pollution, so it should be eliminated or banned from use

The chromium slag produced by calcium-free or calcium-less roasting is generally treated by: one part is returned as chromium salt production and roasting, and the other part is used for ferrochrome production, and every ton of chromium slag is lost more than 1,000 yuan, and there is Some untreated chromium slags are piled up, and the amount of chromium slag increases sharply over time, which has a huge impact on the environment

[0004] The chromium slag produced by the potassium-based sub-molten salt liquid-phase oxidation method and the pneumatic fluidized tower continuous liquid-phase oxidation method also needs to be treated. It is used for smelting ferrochromium or used as an additive for cement production after high-temperature detoxification. The treatment capacity is limited and the investment is large. , high energy consumption, easy to cause secondary pollution to the environment, and large losses