Preparation
Flotation
The method of using flotation agent to produce potassium chloride from potassium-containing ore pulp. Based on the fact that the surface of potassium chloride and sodium chloride crystals are wetted by water to different degrees, when the flotation reagent is added, their surface properties can be changed, and their surface wettability differences can be enlarged. Bubbles, potassium chloride crystals adhere to small bubbles to form bubbles and rise to the surface of the slurry.
The flotation agents used include:
① Collector, fatty amine containing 16-18 carbon atoms.
②Regulators, adjust the functions of collectors and foaming agents, and improve flotation conditions. Generally, there are three types: inhibitors, such as starch, aluminum sulfate, etc.; activators, such as lead salts, bismuth salts, etc.; regulators, such as carbonic acid Sodium, sodium sulfate, etc.
③Foaming agent, monoatomic and diatomic alcohols of pine oil, dioxane and pyran series. [3]
Carnallite method
When the raw material is carnallite ore, the methods are as follows:
①Total melting method
Dissolve carnallite with brine of saturated sodium chloride heated to 105°C, separate sodium chloride and insoluble matter, and cool the resulting clear liquid to 25°C to precipitate potassium chloride crystals, which are obtained by washing and drying. The mother liquor is concentrated by evaporation, and after the potassium chloride is recovered, part of it is discharged and part is returned to the leaching carnallite mine. The products obtained by this method are of good quality, but high energy consumption.
②Cold decomposition method
Dissolve carnallite with brine or water at room temperature to obtain potassium chloride with a small particle size. Separate the potassium chloride by gravity or centrifugal force, and then wash and dry to obtain a product with a potassium chloride content of 90%. The fineness is less than 200 mesh.
The methods for producing potassium chloride using Yantian carnallite as raw materials include:
① Cold decomposition flotation method
The flotation reagent is used to enrich potassium chloride, and the product obtained is of poor quality and small particle size, which has tended to be eliminated.
②Cold decomposition hot melt crystallization method
Similar to the full solution method, the product obtained is of good quality but high energy consumption.
③Cold crystallization method
In the process of cold decomposition of salt field carnallite, the rate of addition of carnallite is controlled to maintain the supersaturation of potassium chloride, and then sodium chloride and magnesium chloride are separated to obtain potassium chloride product. The product of this method has large particle size, good quality, low energy consumption and cost, but requires less sodium chloride in the raw material of carnallite.
Dissolution crystallization method
A method of separation using the difference in solubility of potassium chloride and sodium chloride in potash mines at different temperatures. The potassium chloride mother liquor (brine) is leached by heating to 100～110℃ to crystallize and separate out the potassium chloride mother liquor ( brine liquor). Potassium chloride is transferred into the solution, sodium chloride and other insoluble substances remain in the insoluble residue, and the residue is separated by centrifugation., After cooling the clarified liquid, potassium chloride crystals are obtained. The product obtained by this method has good quality and strong adaptability to ore. It is suitable for potassium chloride crystal monomer separation of potassium salt mines with small particles and complex components, but with high energy consumption. [4]
Heavy medium separation
Using the difference in the relative density of potash and rock salt in potash mine, adding a medium with a density between rock potash and rock salt to separate them. The heavy medium suspension can be prepared with pyrite powder (or ferrosilicon powder) or saturated brine . This method is suitable for the separation of large-particle, high-grade potash salt ore. If the particle size is less than 1mm, this method cannot be used due to the non-selective agglomeration between the particles due to internal adhesion. Potassium chloride for food and medicine is prepared by dissolving industrial grade potassium chloride and distilled water into a saturated solution, adding a decolorizing agent, an arsenic removing agent and a heavy metal removing agent for solution purification, precipitation, filtration, cooling and crystallization, centrifugal separation , and drying.
