METHOD OF PROCESSING LOW-POTASSIUM SODA POTASH SOLUTION AT HIGH CONTENT OF SULFUR Russian patent published in 2007 - IPC C01D5/00 C01D7/00 

FIELD: processing of low-potassium soda potash solutions contaminated with considerable amount of sulfate salts.

SUBSTANCE: proposed method includes preliminary concentrating evaporation of starting soda potash solution followed by evaporation till saturation with sulfate salts at precipitation of pure monohydrated soda, separation of commercial potassium sulfate from mother liquor of monohydrated soda by mixing it with mother liquor of anhydrous soda and cooling to temperature of 35-40C, separation of anhydrous soda with admixtures from mother liquor of potassium sulfate and re-crystallization of it into pure monohydrated soda. Sulfur is withdrawn from process by hydro-chemical re-crystallization of part of commercial potassium sulfate in two stages in succession. At first stage, glaserite salt (Na₂SO₄·3K₂SO₄) settles-out due to re-crystallization of commercial potassium sulfate in circulating mother liquor obtained at second stage during re-crystallization of glaserite salt. At second stage, berkeyite salt (Na₂CO₃·2Na₂SO₄) due to re-crystallization of glaserite salt in newly prepared saturated solution of pure monohydrated soda proportioned for obtaining circulating mother liquor after re-crystallization of glaserite salt at molar potassium index not exceeding 17%.

EFFECT: possibility of complex processing of soda potash solutions contaminated with considerable amount of sulfate salts.

1 dwg