In the early stage of preparation of potassium sulfate from sea salt brine, there should be a direct conversion method of bitter brine and a bitumen evaporation-flotation method. Later, ion exchange method, extraction method, liquid membrane method and metathesis method appeared successively.

 

The high-temperature salt and potassium chloride preparation potassium sulfate process is a high-temperature salt produced in the production of bitter hail potassium chloride as a raw material, and a high-temperature salt and potassium chloride are subjected to a conversion to obtain a mixture of potassium magnesium salt and sodium chloride. Then, a fatty acid amine collector and a mushroom enol foaming agent and a mother liquor produced by the system are added into the material to prepare a slurry, which is sent to a flotation machine for flotation separation to obtain soft potassium magnesium strontium and an industrial salt. Soft potassium magnesium is divided into two parts in aqueous solution to obtain potassium sulfate;

 

The flotation method of bitter brine and potassium chloride to prepare potassium sulfate is a system of self-produced carnallite and bitter brine to separate bitter salt and then evaporate and concentrate to obtain mixed salt, mixed salt and potassium chloride and system white. The potassium-producing mother liquor is added to the collector and the foaming agent after a conversion, and the soft potassium magnesium and sodium chloride are separated by a flotation machine, and the potassium potassium sulfate is separated from the potassium chloride and water to obtain potassium sulfate:

 

The spin-flow method of bitter brine and potassium chloride to prepare potassium sulfate is composed of bitter brine to prepare potassium chloride, cyclone separation of high-temperature salt, magnesium sulfate and potassium chloride in one step to obtain potassium sulfate. The production method is The high temperature salt in the production of potassium chloride is separated from the magnesium chloride solution by using a magnesium chloride solution as a medium to separate magnesium sulfate monohydrate and sodium chloride, and magnesium sulfate monohydrate is used to prepare potassium sulfate by a two-step conversion method;

 

The high-temperature salting-out method of bitter brine and potassium chloride to prepare potassium sulfate comprises the steps of halogenation, one-stage evaporation, high-temperature salting out, two-stage evaporation, cooling, one-stage conversion, two-stage conversion, drying, and the like;

 

The ion exchange method is to solve the problem of adding potassium chloride in the process of producing potassium sulfate due to the imbalance of potassium ions and sulfate ions in the brine during the preparation of potassium sulfate in the brine, and directly extracting potassium sulfate from seawater. It can open a new path for China's self-sufficiency of potassium fertilizer. The method is to pass seawater through an exchange column containing natural adsorbents, so that potassium ions are adsorbed on the exchanger, and then the circulating liquid of the system is superimposed and adsorbed through the exchange column. The saturated brine is eluted from the potassium ions in the exchange column at a high temperature to obtain a potassium-rich eluent and a circulating liquid, and the potassium-rich eluent is returned to the old halogen, and the composition is adjusted to evaporate to a large precipitation of sodium chloride. When the anhydrous potassium magnesium ruthenium is close to saturation, the solid phase is separated and washed with a potassium-rich eluent to separate and dry to be a fine salt. The clear liquid continues to evaporate until the anhydrous potassium magnesium is precipitated relatively completely, and the potassium chloride does not precipitate and ends the evaporation. The evaporation completion liquid is thermally insulated and settled, and the clear liquid is cooled to obtain the carnallite and the old halogen. The carnallite is decomposed by the potassium sulfate mother liquor to produce potassium chloride and a decomposition liquid, and the slurry is obtained by a flotation method. Potassium chloride and magnesium Rocky separated, after kieserite with water and potassium chloride and potassium sulfate was isolated as the reaction mother liquor, the process is in the development stage;

 

The liquid membrane method for extracting potassium sulfate from brine is to establish a liquid membrane extraction system with stable chemical and physical properties by selecting a high-efficiency carrier for liquid potassium extraction, and to increase the adsorption amount of potassium to meet the requirements of potassium extraction from brine.

 

Although the preparation of potassium sulfate from Haihu salt brine still has certain defects, if some processes need to evaporate a large amount of water, the energy consumption is large, some processes are long, the rate of potassium sulfate is low, the product loss is serious, and both resources are received. Regional restrictions, but in the long run, there are abundant potassium resources in seawater, and seawater potassium extraction technology will be taken seriously.