Separation of Sodium Sulfate by the Flotation Method

Abstract

As regard to the separation process of sodium sulfate from the recovered salt, which can be obtained in the concentration process of diaphragm electrolysis caustic soda solution, the authors studied fundamentally the flotation method. The flotation characteristics of pure sodium sulfate crystal in the saturated solution with both sodium sulfate and sodium chloride were examined. On the basis of results obtained, separations of sodium sulfate from the recovered salts, which prepared from the imitative electrolyte, were carried out by using a FW-50 type flotation test machine. The results summerized as follows:
(1) It was recognized that a sodium dodecylsulfate was selective as a collector for sodium sulfate from paraffin chain salts (Table-1), which exhibit collection properties for nonmetallicminerals.
(2) It was inferred from the adhesion curve of sodium sulfate (Fig.-1) that the pH value of pulp solution was preferable in the alkaline region of 7 to 13.
(3) In case of the sodium sulfate flotation using sodium dodecylsulfate (60mg/l) as a collector, it was found that the concentrate recovery was increased linearly with increase of sodium sulfate in the Na₂SO₄-NaCl mixed sample, and the sodium sulfate grade was in the range of about 94 to99%.
(4) The flotation results of the recovered salt were less good than expectation of the flotation characteristics. But the authors concluded that the sodium sulfate could be separated from the recovered salt by means of the multistage flotation method.