Research On Preparation Of Potassium Chloride In Thermal Decomposition Of Carnallite

Potassium chloride is an important potash resource, whose application is extremely extensive. Its products are mainly divided into agricultural potassium chloride and industrial potassium chloride, In the chemical industry, potassium chloride can be used as the manufacture of other potassium raw materials, and also is an important raw material for the manufacture of gunpowder, and is one of the compositions of electrolyte to produce metal. In agriculture, potassium chloride can be used in the preparation of compound fertilizer. Potassium chloride is available potassium, and also is an essential nutrient for crop growth. It can be used as base fertilizer or top dressing. Throughout the market of potassium chloride, potassium chloride market demand is stable; the future will be a supply and demand prosperous situation.The production of potassium chloride is mainly using the method of carnallite cold decomposition in coastal area. Carnallite is added water to decomposition, washing, and centrifuged to obtain potassium chloride products. Solution is evaporated and crystallized to produce magnesium chloride products. The addition of water in the production process not only affects the yield and purity of potassium chloride, but also affects the energy consumption of magnesium chloride production.By using Hangu salt field carnallite as raw material; the main research contents have the following aspects:Studying on the technological parameters for the decomposition of carnallite through the comparative study with the common cold decomposition process for production of potassium chloride in this article.The better carnallite decomposition process conditions are as follows:the reaction temperature is 75 ℃ and the amount of water is 1.1 times theoretical content. The yield of potassium chloride is 69.97% and the purity of the product is 97.57%. Compared with the cold decomposition (25℃), the amount of water is reduced by 13.36% and the percentage content of magnesium chloride in liquid phase increases by 2.33%.Kinetics studies can provide an important basis for mould design and optimization of crystallization process. Intermittent dynamic method was used to study the crystallization kinetics of potassium chloride in K+, Mg2+//Cl-—H2O system. The size-independent model and the moment transform method were chosen to deal with the kinetic data, and the model equations of the nucleation rate and the crystal growth rate of potassium chloride were finally obtained.Study on the factors influencing the size of potassium chloride crystallization, including feed rate, adding seed crystal, super saturation, stirring intensity. The results of the study found that, these factors have important influence on the potassium chloride crystal growth:Lower super saturation, lower feed rate, and lower stirring intensity, higher crystallization temperature, adding seed crystal, can increase the size of crystal.