Effect of crystallization temperature, stirring rate, and pH on the crystallization of ammonium sulfate in the presence of calcium sulfate

作者：Xinchao Fan, Bangfu Huang, Gaoyong Zi, Zhe Shi, Linjing Yang, Liubin Luo, Yuan Fu, Keying Zhu, Daoping Zhan · 发表于：Phosphorus, sulfur, and silicon and the related elements · 年份：2025 · DOI：10.1080/10426507.2025.2482879 · 被引用次数：4 · 研究领域：Minerals Flotation and Separation Techniques、Calcium Carbonate Crystallization and Inhibition、Phosphorus and nutrient management

This article investigated the effects of crystallization temperature, stirring rate, and pH on the crystallization of ammonium sulfate (NH4)2SO4) mother liquor containing calcium sulfate (CaSO4). This study measured the metastable zone width, average particle size, and coefficient of variation of (NH4)2SO4 after CaSO4 was added. CaSO4 was found to cover the active nucleation sites of (NH4)2SO4, leading to a widening of the metastable zone. The increase in crystallization temperature increased the rate of molecular thermal movement, resulting in a narrowing of the metastable zone. The increase in stirring rate accelerated solute diffusion; thus, the metastable zone width became narrower. When the stirring rate was 250 rpm, crystals with a large average size were obtained, which was conducive to solid-liquid separation. The decrease in pH caused the solution viscosity to increase; thus, the metastable zone width decreased. When the pH was 4.5, crystallization could be controlled within a better metastable zone width, and burst nucleation did not occur easily, which resulted in the formation of regular-shaped crystals.