SODIUM SULPHATE FROM DRY MIXED SALTS OF LAKE KARAUMBET

Abstract

The results of the processing of dry mixed salts of lake Karaumbet and the isolation of mirabilite are presented. It was shown that the maximum solubility of dry mixed salts in water at 25°C is observed at T:W = 1:(2.5-3) and amounts to 91.08-93.02% of the total initial mass. The degree of dissolution of the main components of the salt at T:W = 1:3 after 5 minutes reaches 89.25%, and after 15 minutes 93.02% at a temperature of 25°C and 92.5% after 5 minutes and 91.61% after 10 minutes and 93.02% after 15 minutes at a temperature of 50ºС.

When sedimentation (clarification) of suspension proceeds most intensively in the first 15 minutes and after 30 minutes the degree of clarification at 20°C reaches 94.59%. At temperatures of 40, 60 and 80ºС, the degree of clarification is 95.51%.

At cooling of the clarified solution to temperature -5°C, the sodium sulfate content in the solution decreases from 15.31% to 2.23%. The maximum yield of sodium sulfate is 85.43% of the initial content of dry mixed salts in the solution. The filtration rate of the thickened sediment by mirabilite reaches 2743 kg/m²•h.

With an increase in frequency rate of return of the mother liquor, the sodium sulfate content decreases from 30.81% to 30.08%, the magnesium sulfate content increases from 0.68% to 1.33%, sodium chloride from 0.31% to 0.73% and sulfate calcium from 0.08% to 0.11%.

It was shown that by returning the mother liquor from the sodium sulfate filtration stage to the stage of mirabilite dissolution with juice pairs and the subsequent introduction of sodium hydroxide and sodium carbonate, the highest grade sodium sulfate yield reaches a maximum value with a main product content of at least 99.4%.