Method for coproducing sodium chloride, magnesium sulfate and potassium chloride

Abstract

The invention relates to a method for coproducing sodium chloride, magnesium sulfate and potassium chloride. The method for coproducing the sodium chloride, magnesium sulfate and potassium chloride is characterized in that raw material brine is subjected to processes of primary evaporation, cooling and secondary evaporation to gradually extract and separate the sodium chloride and the magnesium sulfate and prepare carnallite; and the carnallite is performed hydrolytic decomposition, and the potassium chloride is produced after washing and dehydration. The method has the advantages of realizing coproduction of three products, namely the sodium chloride, the magnesium sulfate and the potassium chloride. The extraction yield of the sodium chloride is above 85 percent; the extraction yield of the magnesium sulfate is increased to be between 56.95 and 62 percent; the extraction yield of the potassium chloride is improved by over 7 percentage; the quality of the carnallite is improved; and the content of the potassium chloride is between 19 and 23 percent, which provides good-quality raw materials for the next process.

Description

technical field [0001] The invention relates to a coproduction method for extracting sodium chloride, magnesium sulfate and potassium chloride from brine. Background technique [0002] At present, the production process steps of extracting potassium chloride from brine are: mixing brine, evaporating, heat preservation and sedimentation, cooling and crystallizing to precipitate carnallite, decomposing carnallite into crude potassium, washing and dehydrating crude potassium into refined potassium. Bitter bittern, by-product bittern, and old bittern are blended in proportion to make a mixed bittern, so as to ensure the ratio of magnesium to potassium in the mixed bittern, and the content ratio of magnesium chloride to potassium chloride is 9.5-10.5; the evaporation process is to complete the mixed bittern The liquid is heated to 128°C under normal pressure or the termination boiling point is increased correspondingly according to the positive pressure, and the high-temperature ...

AI Technical Summary

Problems solved by technology

Above-mentioned production technique is mainly to produce potassium, and sodium chloride, magnesium sulfate are by-products, and the extraction rate of sodium chloride is 61%, and the extraction rate of magnesium sulfate is 47.2%, and its shortcoming is:

[0003] 1. The extraction rate of potassium chloride is difficult to break through 72%, even if the non-process loss is eliminated, it cannot break through the index of potassium chloride extraction rate;

[0004] 2. Serious empty consumption phenomenon: due to the generation of a large amount of by-product brine, a lot of potassium chloride is entrained, resulting in the loss of potassium chloride; at the same time, when the brine is mixed, the equipment is kept in idle operation for a long time;

[0005] 3. Difficult operation: Due to the high content of sodium chloride and magnesium sulfate in the raw materials, the evaporation operation has a large solid-to-liquid ratio, which makes the material operation difficult, easy to scale, affects heat transfer, and impurity salt crystallization absorbs heat and affects production efficiency;

[0006] 4. The by-product high-temperature salt is seriously lost, with an average of more than 4% before washing: due to the large amount of by-product high-temperature salt, about 10 tons of high-temperature salt is produced per ton of potassium chloride, and the phenomenon of belt loss is serious, further reducing the extraction of potassium chloride The rate also increases the empty consumption;

[0007] 5. The quality of carnallite is low, and the content of potassium chloride is 17%-19%: the quality of carnallite produced by this method is low, which affects the qualified product;

[0008] 6. It is difficult to control the amount of brine rejection: the process produces more potassium chloride by-product brine, all of which are returned to the evaporation system (especially when the high-temperature salt zone loses thick brine), making it difficult for downstream products to operate at full capacity