Chromium salt production method with recyclable auxiliary materials

Abstract

The invention discloses a chromium salt production method with recyclable auxiliary materials. The method comprises the following steps that 1, raw materials are prepared; 2, oxidation roasting transformation is carried out; 3, clinker ammonium salt is leached; 4, impurity removal and crystallization are carried out; 5, ammonium chromate is decomposed; 6, ammonia gas and / or carbon dioxide obtainedafter the second step, the fourth step and the fifth step are / is absorbed by a solution, and the obtained chromium salt solution serves as a leaching agent for recycling. According to the chromium salt production method, the mode that carbonate or a hydroxide of alkali metal serves as an auxiliary material for oxidative decomposition of chromite is abandoned, and low-cost easy-to-recycle calciumcarbonate and other calcium-containing materials and ammonium salt serve as the auxiliary materials for chromium salt production, so that the situation that a large amount of alkali is consumed duringchromium salt production is avoided, the emission problem of chromium-containing waste residues including chromium-containing mirabilite is solved, recycling of the auxiliary materials in the chromium salt production process is economically and efficiently realized, the material consumption in the chromium salt production process is reduced, the production cost and environmental pollution are reduced, and obtained chromium salt products are high in quality.

Description

technical field [0001] The invention belongs to the technical field of chromium and chromium salt production, and in particular relates to a chromium salt production method with recyclable auxiliary materials. Background technique [0002] Chromium salt series products are widely used in electroplating, leather tanning, pigments, anti-corrosion and other fields due to their special properties, and are indispensable and important raw materials. The main methods of producing chromium salts in industry are calcium roasting method, calcium-free roasting method, molten salt liquid phase oxidation method, etc. These methods all use sodium carbonate, sodium hydroxide or potassium hydroxide, etc. to decompose chromite under an oxidizing atmosphere, and oxidize and convert the insoluble trivalent chromium compound in chromite into soluble sodium chromate or potassium chromate. Aqueous leaching separates chromate from the main impurities in the ore. The obtained sodium chromate or p...

AI Technical Summary

Problems solved by technology

Due to the strong alkalinity of sodium and potassium, the combination of sodium / potassium ions and chromate ions in the solution is strong, and weakly acidic CO 2 The process of converting chromate to bicarbonate and separating bicarbonate often requires high CO 2 Partial pressure (>10atm), low temperature (<30°C) and other harsh conditions, resulting in complex process technology and low production efficiency

In the process of reducing chromate or dichromate by carbon or hydrogen, the sodium / potassium carbonate or sodium / potassium hydroxide formed by the reaction is very easy to have a side reaction with the chromium trioxide product to form the corresponding chromite. In the process of separating alkali, chromite is easily hydrolyzed to form chromium hydroxide, which seriously affects the quality and performance of the product

To sum up, sodium or potassium alkali is mainly used as auxiliary materials in the production of existing chromium salts, and the circulation and regeneration of these alkalis are relatively difficult; the existing recycling and regeneration schemes generally can only realize the circulation of part of the alkali, and the production process requires Control harsh conditions, there are problems such as low production efficiency, high cost, and difficulty in guaranteeing the quality of the obtained products

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