RU2264985C1 - Method of reprocessing of a sodium-potash solution - Google Patents

Abstract

FIELD: nonferrous metallurgy; methods of reprocessing of a sodium-potash solution.

SUBSTANCE: the invention is pertaining to the field of nonferrous metallurgy, in particular, to reprocessing a sodium-potash solution produced from a nepheline ore with a low molar index of potassium alkali. The method provides for a concentrating evaporation of the initial sodium-potash solution, a subsequent its evaporation with separation in sediment of monohydrate sodium, separation of a potassium sulfate from a monohydrated soda mother liquor with a dosing in it of a sodium sulfate or sulfuric acid to convert a superfluous in the production process potash into a potassium sulfate, separation from the potassium sulfate mother liquor of the waterless soda polluted with impurities of potash, potassium sulfate and potassium chloride. The waterless soda polluted with impurities of potash, potassium sulfate and potassium chloride is subjected to conversion by a solution a concentrated evaporation at the temperature of 60-70°C within 2.0-3.0 hours with a dosage of 1.2-1.5 m³ of the concentrated evaporation solution per one ton of the waterless soda with production of the monohydrated soda purified from of impurities of a potash, a potassium sulfate and a potassium chloride. The invention allows to reduce a specific consumption of a vapor in the production cycle and the flow of the solution and soda at conversion and separation of monohydrated soda.

EFFECT: the invention allows to reduce a specific consumption of a vapor in the production cycle and the flow of the solution and soda at conversion and separation of monohydrated soda.

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Description

A method of processing soda-potash solution relates to non-ferrous metallurgy, specifically to the processing of soda-potash solution obtained from nepheline ore, with a low molar index of potassium alkali.

There is a method of processing soda-paste solution with a low molar index of potassium alkali according to patent for invention No. 2223913 dated July 15, 2002, considered as the closest prototype of the proposed new method. According to the known method, a soda-paste solution obtained from nepheline ore with a low molar index of potassium alkali is subjected to concentrating evaporation in a mixture with anhydrous soda obtained in the next stage of the technological cycle contaminated with impurities of potash, potassium sulfate and potassium chloride. The concentrated soda-paste solution is then subjected to the second stage of evaporation with the release of monohydrate soda purified from impurities at a density of one stripped off solution equal to 1.34-1.35 t / m ³ .

The mother liquor, after the separation of monohydrate soda from it, is mixed with the mother liquor of anhydrous soda to bring the molar index of potassium in the mixed solution to 50-54%. A solution of sodium sulfate or sulfuric acid is metered into the mixed solution to convert excess potash in the mixed solution to potassium sulfate, and then the mixed suspension is subjected to vacuum crystallization cooling to a temperature of 35-40 ° С with precipitation of potassium sulfate at a density of the cooled solution equal to 1 , 40-1.41 t / m ² .

The mother liquor of potassium sulfate is then subjected to the third stage of evaporation with the release of anhydrous soda contaminated with impurities at a density of an evaporated solution of 1.47-1.49 t / m ³ . The anhydrous soda precipitated in the sediment, contaminated with impurities of potash, potassium sulfate and potassium chloride, is returned to the head of the technological cycle, where it is mixed with the original soda-potash solution at the stage of its concentration evaporation.

The mother liquor of anhydrous soda is mixed with the mother liquor of monohydrate soda at the stage of separation of potassium sulfate from the mixed solution. The technological scheme of the known method is shown in figure 1.

Figure 2 held the technological balance of the practical implementation of the known method of processing soda-potting solution obtained from the Kiya-Shaltyr nepheline ore.

The main disadvantage of this method is the overestimated specific consumption of steam in the technological cycle and the overestimated material flow of the solution and soda at the redistribution of the allocation of monohydrate soda, due to the dissolution of anhydrous soda in the initial soda-paste solution at the stage of its concentration evaporation.

An object of the invention is to reduce the specific consumption of steam in the production cycle and to reduce the flow of solution and soda in the redistribution of the allocation of monohydrate soda.

This goal is achieved by the fact that in the method of processing soda-potash solution obtained from nepheline ore with a lower than 20% molar index of potassium alkali, including concentrating evaporation of the original soda-potash solution, its subsequent evaporation with precipitation of monohydrate soda, the allocation of potassium sulfate from the mother liquor of monohydrate soda with a dosage of sodium sulfate or sulfuric acid into it to convert excess potash in the technological cycle to potassium sulfate, isolation of potassium sulfate from the mother liquor anhydrous soda contaminated with impurities of potash, potassium sulfate and potassium chloride, characterized in that the obtained anhydrous soda contaminated with impurities is subjected to conversion with a solution of a concentrated residue at a temperature of 60-70 ° C for 2.0-3.0 hours with a dosage of 1, 2-1.5 m ^{3 of a} solution of concentrating residue per ton of anhydrous soda, to obtain monohydrate soda, purified from impurities of potash, potassium sulfate and potassium chloride.

Anhydrous soda in the conversion process in an evaporated soda solution of concentrating residue at a temperature of 60-70 ° C for 2–3 hours is recrystallized into monohydrate soda and purified of impurities of potash, potassium sulfate and potassium chloride. If the temperature of the soda solution is above 70 ° C, the process of recrystallization of anhydrous soda to monohydrate slows down or practically does not occur if the temperature of the soda solution rises above 100 ° C. If the temperature of the soda solution drops below 60 ° C, the cleaning of the monohydrate soda from impurities of potash, potassium sulfate and potassium chloride deteriorates.

Reducing the duration of the conversion process below two hours leads to incomplete recrystallization of anhydrous soda and to incomplete purification of the resulting monohydrate soda from impurities. A decrease in the amount of concentrate dosing dosed to the conversion of the soda solution below 1 m ³ per ton of anhydrous soda does not ensure the complete recrystallization of anhydrous soda and its purification from impurities of potash, sulfate, potassium and potassium chloride. An increase in the dosage of a soda solution per conversion above 1.5 m ³ per 1 ton of anhydrous soda leads to an increased dissolution of anhydrous soda during its conversion and to a decrease in the yield of monohydrate soda.

Figure 3 shows the technological scheme of processing soda-paste solution of the claimed method.

Figure 4 shows the technological balance of the practical implementation of the claimed method of processing soda-cultivating solution obtained from Kiya-Shaltyrsky nepheline ore.

As follows from the Figures 2 and 4 practical technological balance of processing 500 m ³ solution of soda and potash, the known method in step concentrating evaporated residue 224 ^m3 of water for monohydrate soda recovery stage evaporated 128 m ³ of water.

In the inventive method, 300 m ^{3 of} water is evaporated at the stage of concentrating evaporation, 78 m ^{3 of} water is evaporated at the stage of separation of monohydrate soda. Evaporation of the solution at the concentration concentration stage is carried out in five-cell evaporator batteries with a specific steam consumption of 0.26 tons per ton of evaporated water. Evaporation of the solution at the stage of separation of monohydrate water is carried out in three-case evaporator batteries with a specific steam flow rate of 0.5 tons per ton of evaporated water. Therefore, when processing soda-potting solution of the claimed method due to the predominant evaporation of water at the stage of concentrating evaporation of the solution, the specific steam consumption in comparison with the known method is reduced by 10%. From the above technological balances it also follows that the flow of the solution and soda at the stage of separation of monohydrate soda in the present method in comparison with the known method is reduced by 30%.

Claims (1)

A method of processing a soda-paste solution obtained from nepheline ore with a molar index of potassium alkali below 20%, including a concentrated evaporation of a soda-paste solution, its subsequent evaporation with precipitation of monohydrate soda, the allocation of potassium sulfate from the mother liquor of monohydrate soda with a dosage of sodium sulfate for the conversion of excess potash in the technological cycle to potassium sulfate, the allocation of anhydrous soda contaminated with potash sulfate, potassium sulfate and chlorine from the mother liquor of potassium sulfate potassium chloride, characterized in that the separated anhydrous soda contaminated with impurities of potash, potassium sulfate and potassium chloride, is subjected to conversion with a solution of concentrating residue at a temperature of 60-70 ° C for 2.0-3.0 hours with a dosage of 1.2-1 , 5 m ^{3 of a} solution of concentrating residue per ton of anhydrous soda to obtain monohydrate soda, purified from impurities of potash, potassium sulfate and potassium chloride.

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