光卤石原矿品位对其冷分解结晶氯化钾过程影响浅析

Analysis of effect of carnallite raw ore grade on its cold decomposition and crystallization of potassium chloride

光卤石冷分解结晶是国内生产氯化钾的主要工艺,但随着光卤石原矿品位的下降,原有技术生产的氯化钾产品出现了粒度变小、易聚结、纯度差且收率低等问题,已成为困扰氯化钾行业发展的难题。对比了不同地区钾盐原矿品质,结合Na^(+)、K^(+)、Mg^(2+)∥Cl^(-)-H_(2)O四元体系及其子体系的热力学相平衡规律,概述了原矿品质对分解结晶过程析盐规律的影响,从分解-结晶耦合过程动力学角度,总结了不同品位光卤石冷分解结晶制备氯化钾过程的产品粒度及形貌调控关键因素及其作用机理。结合产品现行标准,提出低钠光卤石、含钠光卤石和高钠光卤石的新分类方法和对应的工艺选择策略,并对不同品位光卤石原矿的冷分解结晶新工艺进行展望,以期为行业健康发展提供理论指导与参考。

Cold decomposition of carnallite is the main process of producing potassium chloride in China.However,the de‐clining grade of carnallite ore has posed a challenge to the industrial development of potassium chloride.The resulting pro‐cess produces potassium chloride with issues such as smaller particle size,increased tendency to aggregate,lower purity,and reduced yield.In this review,the quality of potassium ore in different regions was compared at first.The effect of raw ore quality on the salt precipitation order of the decomposition process was overviewed based on the thermodynamic phase equi‐librium of the quaternary system(Na^(+),K^(+),Mg^(2+)∥Cl^(-)-H_(2)O)and its sub‐systems.From the kinetic perspective of the decom‐position‐crystallization coupling process,the crucial factors and underlying mechanisms for regulating the particle size and morphologies of potassium chloride crystals during the cold decomposition‐crystallization process(CDCP)of different grades of carnallite raw ore were summarized.In addition,combined with the current product standards,a novel classifica‐tion method and corresponding process‐selection strategy for low‐sodium carnallite,sodium‐containing carnallite,and high‐sodium carnallite were proposed.And the new CDCP for different grades of carnallite raw ore was prospected,in the hope of providing theoretical guidance and references for the sustainable development of the industry.