Method for separating potassium oxide from potassium-containing sodium aluminate solution

Abstract

The invention relates to a method for co-producing potassium sulfate by separating potassium oxide from a potassium-containing sodium aluminate solution while producing aluminum oxide from minerals, containing an aluminum element and a potassium element, such as non-soluble potassium ores or bauxite. The method is characterized by comprising the steps of adding one or the mixture of sodium sulfate, aluminum sulfate (alkaline aluminum sulfate), potassium (sodium) alum and alunite ores (pure alunite) into the potassium-containing sodium aluminate solution for introducing SO4<2-> to convert potassium oxide in the sodium aluminate solution into potassium sulfate, precipitating and separating potassium sulfate in a glaserite form, and purifying glaserite into potassium sulfate by virtue of methods of variable temperature dissolution and separation, potassium chloride conversion and potassium aluminate replacement. According to the method, the precipitation is carried out under conditions of high caustic alkali and low temperature, so that the residue of sodium sulfate in the solution can be avoided, and the solution is purified. A Bayer process is not influenced, accumulated potassium oxide can be recycled from a circulating mother solution for the production of aluminum oxide, and aluminum oxide and potassium sulfate can be produced by virtue of the non-soluble potassium ores such as nepheline and potassium feldspar as well as alunite ores or artificial pure alunite by a parallel-combined process.

Description

technical field [0001] A method for separating potassium oxide from a potassium-containing sodium aluminate solution, which relates to a method for producing alumina from ores containing two elements of aluminum and potassium such as water-insoluble potassium ore or bauxite; A method for separating potassium oxide from sodium aluminate solution to realize co-production of potassium sulfate. Background technique [0002] Potassium salt is an important chemical raw material and agricultural fertilizer. In industry, potassium chloride is produced through water-soluble potassium-containing resources such as salt lake water and potash mines, and then part of it is converted into other potassium salt products such as potassium sulfate. Water-soluble potassium resources in my country The reserves are small and only concentrated in individual provinces in the west, far from meeting the requirements of industry and agriculture, and a large amount of potassium chloride needs to be impo...

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Problems solved by technology

[0002] Potassium salt is an important chemical raw material and agricultural fertilizer. In industry, potassium chloride is produced through water-soluble potassium-containing resources such as salt lake water and potash mines, and then part of it is converted into other potassium salt products such as potassium sulfate. Water-soluble potassium resources in my country Reserves are small and only concentrated in individual provinces in the west, far from meeting the requirements of industry and agriculture, and a large amount of potassium chloride needs to be imported

Water-insoluble potassium ore is another potassium-containing resource. The domestic reserves are huge, widely distributed, and of good quality. In order to extract alumina and potassium oxide from insoluble potassium ore, domestic and foreign technical personnel have done a lot of research for a long time and developed a thermal method. , Alkaline method, acid method and many other effective processes, but there are disadvantages such as high processing cost or unreasonable product structure.

Russia uses nepheline ore to produce alumina, potassium sodium salt and cement by soda lime sintering method. This process first carbonates and decomposes potassium-containing sodium aluminate solution to convert caustic soda into carbon soda and separates alumina, and then according to potassium carbonate The difference in the solubility of sodium carbonate and sodium carbonate can be separated by evaporation. Since the solubility of potassium carbonate is much greater than that of sodium carbonate, in order to obtain potassium carbonate, it is necessary to evaporate all the mother liquor of the carbon fraction to dryness, and a large amount of potassium and sodium carbonate are precipitated during the evaporation process. Mixture, high separation cost, complicated process, and limited market capacity of the produced potassium carbonate product

[0003] There are a small amount of potassium-containing minerals in bauxite and lime. Under the conditions of alumina production, most of the potassium is dissolved and accumulated in the solution cycle. Due to the lack of effective separation technology, it cannot be recovered. Finally, it can only be allowed to pass through red mud, carbon soda, and solidification. In recent years, with the continuous reduction of ore grades, the content of impurity potassium in alumina products in some places has gradually increased, which has brought troubles to electrolysis

Although potassium oxide provides caustic for the process, it accumulates as an impurity in the product and aggravates evaporation scaling. More importantly, the price is much higher than that of sodium oxide. It is a pity to lose it

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