Abstract: In process of high-temperature crystallization,the effects of feed mass concentration,operating temperature,residence time,and stirring rate on the crystallization efficiency of manganese sulfate were studied by orthogonal and single factor experiments.Results showed that when feed mass concentration was 370.0 g/L,there were no crystals separated out by means of normal-pressure crystallization;while in the high-temperature crystallization process under the conditions of pressure of 1.3 MPa (gauge pressure),operating temperature of 170 ℃,residence time of 14 min,stirring rate of 350 r/min,the crystallization efficiency of manganese sulfate was 84.0%,which reached 88.0% of the theoretical crystallization efficiency at this temperature.Energy consumption of high-temperature crystallization was 60.7% of that of normal-pressure crystallization.Method of high-temperature crystallization could save 2.75 t stream when 1 t MnSO₄•H₂O was produced.This process has an important directive significance in the comprehensive utilization of low-grade pyrolusite and developing new energy saving technology for the production of manganese sulfate.

Key words: manganese sulfate, high-temperature crystallizing process, crystallization efficiency