Recycling of Mother Liquor from Reaction Conversion of Picromerite for K₂SO₄

During the reaction crystallization of picromerite for potassium sulphate, a large amount of potassium-containing mother liquor is produced. In order to improve the utilization of potassium resources, different crystallization strategies performed under different vacuum degrees were used to investigate the recovery and utilization of potassium resources in reaction mother liquor at 108, 75, 35 ℃. The purity, morphology and particle size distribution of the three routes of evaporation crystallization were systematically studied using XRD, chemical analysis, particle size distribution and other analytical methods. The ending point of evaporation water for potassium resource recovery under metastable conditions was determined. The experimental results show that the products of the evaporation crystallization process at 108 ℃ are langbenite and potassium chloride, and the crystal products at 75 ℃ and 35 ℃ are potassium chloride. At 35 ℃, the potassium content and potassium recovery rate of the products reach the highest within the same time, which are 44.64% and 78.73%, respectively. Meanwhile, combined with the characteristics of drought and little rain in the western salt lake area, it is determined that the evaporation crystallization at room temperature is the best process for potassium resource recovery in the mother liquor of reaction of picromerite. The experimental results provide relevant basis and reference for the further improvement of utilization of potassium resource in the resource-type potassium sulfate production process.