Method for removing magnesium in manganese sulfate solution through double salt crystallization process

Abstract

The invention discloses a method for removing magnesium in a manganese sulfate solution through a double salt crystallization process. According to the method, a crystallization device is additionallyarranged in an electrolytic manganese production system, and the concentration of ammonia sulfate in the manganese sulfate solution is controlled to be 80-140 g / L; the magnesium ion concentration is10-30 g / L; then, the pressure is controlled to be 3-20 Mpa, the initial temperature is 50-90 DEG C, ammonia sulfate magnesium crystals are added, the temperature is reduced to 30-70 DEG C within 45-180 min, the ammonia sulfate magnesium crystals are obtained, the crystals are taken out, and accordingly magnesium removal can be achieved. The method has the advantages that the method is economical and feasible, and no pollution is caused to an electrolytic manganese system.

Description

technical field [0001] The invention relates to the production of manganese sulfate in the fields of metallurgy and chemical industry, in particular to a method for removing magnesium in manganese sulfate solution by double salt crystallization. Background technique [0002] As an important metallurgical and chemical raw material, electrolytic manganese has made great contributions to the regional economy of our province and even the industrial development of the whole country. The general method used in the electrolytic manganese production system is: rhodochrosite sulfuric acid leaching, then neutralization to remove iron, then SDD to remove heavy metals, after filtration, adjust the pH to about 7.2, start diaphragm electrolysis, return anolyte + sulfuric acid leaching, and continuously add catholyte The previously treated leachate can realize circular production. On January 22, 2016, the 103 Geological Brigade of the Guizhou Provincial Bureau of Geology and Mineral Resou...

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Problems solved by technology

[0008] It is generally qualitatively believed that an increase in the concentration of magnesium ions will cause the following hazards: ① Magnesium sulfate is easy to crystallize with the product, causing a large loss of active ingredients such as manganese sulfate and ammonium sulfate, reducing product quality, increasing the density and viscosity of the solution, and filtering Difficulty, which increases the voltage and resistance of the electrolytic cell, resulting in a decrease in the current efficiency of the electrolytic cell, thereby reducing the production efficiency of the electrolytic cell

②Dense and hard crystals are formed on the surface of the equipment in contact with the solution, which blocks the solution channel, reduces the passing capacity of the solution, and increases the pressure of the solution delivery. At the same time, magnesium crystals also increase the thermal resistance of the pipeline, affecting the heat transfer of the liquid, making the heat transfer Significantly lower efficiency

③Magnesium ions will occupy the ionic space in the sulfuric acid system, which will indirectly lead to a decrease in the leaching rate of rhodochrosite

④As the concentration of magnesium ions increases, it will occupy a certain position in the solution, which will inevitably hinder the mass transfer of manganese ions and ultimately affect the current efficiency. In actual production, in order to improve the current efficiency as much as possible and reduce the impact of impurities on the system, most The concentration of manganese ions in the manganese sulfate electrolyte is maintained at a low concentration (20g / L), and the concentration of manganese ions in the anolyte after electrolysis is 15g / L-18g / L, the difference between the two is very small, the solution flow rate is large, and the production low efficiency

This method is only applicable to pyrolusite, and now most of the electrolytic manganese industry uses rhodochrosite. During the treatment of rhodochrosite with dilute sulfuric acid, a large amount of manganese will also be dissolved and cause loss. Therefore, this method has certain limitations.

[0014] According to previous studies, there are many ways to remove magnesium ions, but they still have their own shortcomings. So far, there is no industrialized way to remove magnesium, which hinders the sustainable development of the electrolytic manganese industry.

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