Abstract:Aiming at the dust of rotary hearth furnace, a high efficient recovery process of potassium and sodium by heating and water leaching was proposed. The effects of various factors on the recovery of potassium and sodium during water leaching were investigated, and the leaching conditions of harmful elements fluoride and thallium were analyzed. The results show that under the conditions of water leaching temperature of 80 ℃, liquid-solid ratio of 6, time of one hour and stirring speed of 500 r/min, the leaching rate of potassium and sodium is both above 99%, and the leaching rate of zinc, fluorine and thallium is 10.03%, 18.35% and 81.89%, respectively. The optimal conditions for zinc deposition from water leaching solution are as follows: the temperature is 40 ℃, the time is 60 min, the stirring speed is 350 r/min, the dosage of Na2CO3 is 12 g/L, and the pH value of the solution is 8.37. At this condition, the zinc content in the purification solution is 0.3 mg/L with the zinc removal rate of 99.99%, and the contents of impurity calcium and magnesium are 5.72 mg/L and 1.3 mg/L, respectively. The purified solution was evaporated and crystallized to prepare potassium chloride, and the product meets the national standard (GB 6549—2011) for industrial potassium chloride superior product standard.