Dynamic and static combined stirring system and process for preparing chromium salt by using chromite liquid phase oxidation method

Abstract

The invention discloses a dynamic and static combined stirring system. The system comprises a stirrer and further comprises a plurality of static stirring paddles parallel to a stirring shaft of the stirrer, the static stirring paddles are arranged around the stirring shaft, and stirring blades are installed at the bottom of the stirring shaft. In addition, the invention further discloses a process for preparing a chromium salt through chromite liquid phase oxidation by adopting the dynamic and static combined stirring system. The invention provides a novel process for preparing a chromium salt by using the chromite liquid phase oxidation method, the key process problems of solid-liquid separation in the chromite leaching process, separation of the chromium salt in a high-alkali medium andconversion of an intermediate product into a series of chromium salts are innovatively solved, and the method has a great industrial application prospect.

Description

technical field [0001] The invention belongs to the technical field of hydrometallurgy and multiphase stirring reaction, and in particular relates to a dynamic and static combined stirring system and a process for preparing chromium salt by liquid-phase oxidation of chromite ore. Background technique [0002] Chromium salt is an important inorganic chemical product. my country is the largest producer of chromium salt, with an annual output of 400,000 tons. The traditional chromium salt production process, especially the calcium roasting technology, has been completely eliminated due to the low utilization rate of resources and the production of a large amount of toxic chromium slag containing Cr(VI). At present, the calcium-free roasting process is widely used in the chromium salt industry. Although the amount of chromium slag produced has been greatly reduced, the pollution problem of chromium slag has not been completely solved. For this reason, the research and developme...

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Problems solved by technology

[0003] A method for producing sodium chromate by alkaline leaching of chromite is proposed in CN201010146648, which is a relatively complete clean production process for chromite at present, but the disadvantage of this process is that the reaction temperature is relatively high (180° C. to 320° C. ℃); after leaching, the method of diluting with a large amount of water and then separating the solid and liquid greatly dilutes the concentration of unreacted alkali and seriously affects the recycling of alkali in leaching; the use of calcium oxide to remove aluminum causes calcium-containing waste slag Accumulation, serious environmental pollution problems; the crude product of sodium chromate separated from chromium / alkali is not easy to obtain pure products by evaporation and crystallization process, and consumes energy and time

There are also the following main technical problems in the actual production and application of chromium salts: (1) The reaction system formed by high-concentration alkali and chromite ore with stable structure is complex, resulting in low conversion efficiency of chromium in the process, and it is necessary to analyze the transfer of chromium in the reaction system. (2) In order to achieve high chromium conversion rate, the amount of alkali is extremely large, which makes it difficult to recover later and the process is complicated; (3) The concentration of alkali in the alkali immersion solution is high, while the particle size of the reaction slag is small, resulting in difficulty in solid-liquid separation; (4) It is difficult to separate the chromium salt from the alkali in the leaching solution, the obtained chromium salt has a large alkali content, and the later purification process is complicated

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