海盐苦卤提制光卤石的研究

本文对从一般盐田苦卤（30°Be,MgCl_2/KCl8,MgSO_4/MgCl_20.4）提制光卤石的过程进行了相图分析与实驗测定。 为了避免蒸发过程中在光卤石饱和以前钾盐的析出,苦卤必须掺兌光卤石母液,使混合卤的MgCl_2/KCl比值在10以上（同时MgSO_4/MgCl_2比值在0.4以下）。但兌卤过多则在工业生产上既不经济又无必要。 本文提出了澄清液中光卤石饱和点的相图计算方法,并进行了实驗测定,为保温分离条件提供了依据。 为了制得质量稳定、产量最大的光卤石,必须使原料卤组成、蒸发终止沸点、保温分离温度和冷却温度互相适应。 对冷却析取光卤石过程的固、液相组成进行了相图分析,实驗结果与理论分析是符合的。提出了冷却过程光卤石析出量的计算方法,得出了兌卤法生产氯化钾的理论最大提取率及生产上提高提取率的途径。 最后,进行了工业性现场扩大试驗,结果证明上述分析是正确的。在工厂中从苦卤提取氯化钾总提取率可达87.13％。

THE SEPARATION OF CARNALLITE FROM SEA-SALT BITTERN

The behavior of salting out carnallite from ordinary sea-salt bittern (30°Be,MgCl2/KCl=8, MgS04/MgCl2=0.4) during evaporation has been investigated. In order to avoid separating out of potassium salt during evaporation before the carnallite becomes saturated, it is necessary to keep the ratio MgCl3/KCl in bittern above 10 (at the same time, the ratio MgSO4/MgCl2 below 0.4) by adding the mother liquor of the carnallite to the bittern. But the addition of an excessive quantity of the mother liquor is deemed neither economical nor necessary for industrial production. This paper puts forward a method for calculating the saturation point of carnallite in the settling liquor from the phase diagram, and experiments have been carried out to determine the foregoing saturation point. In order to obtain a stable quality and a maximum yield of carnallite, it is important to keep the settling-separation temperature slightly above the saturation point of carnallite in the settling liquor, and which is, in turn, related to the composition and the final boiling-point of bittern. The solid and liquid components in regard to the cooling method for separation of carnallite have been studied under phase diagram analysis, and the results obtained from experiments coincide with theoretical evaluation. This paper also presents a method for calculating the amount of carallite separated out during cooling and the theoretical maximum percentage of recovery of potassium chloride by adding the mother liquor of carnallite to bittern. It may also be regarded as a proper channel to increase the percentage of recovery of potassium chloride during the process. Finally, the results obtained from plant scale experiments prove that the above statements are correct. As a matter of fact, the yield of potassium chloride from bittern has already reached 87.13% in industrial practice.