Separation and recovery of potassium chloride from sinter dust of a steel plant

Abstract

Many companies return sinter dust to sintering directly, resulting in circulation and accumulation of harmful elements, which will affect the collection efficiency, sinter quality, and the grade of blast furnace seriously. A new separation and recovery process of potassium from the dust was proposed, which included water leaching, solid liquid separation, purification, vacuum evaporation and cooling crystallisation. The results showed that the optimum conditions were as follows: the ratio of solid to liquid = 1:3, leaching time = 40 min, and leaching temperature = 80°C, leaching rate of potassium chloride reaches 99.99%. When solution weight loss is 97.5%, the evaporation of potassium chloride product reaches 97.96%, purity of potassium chloride in the crystal can be 75.15%. Based on experiment results, a mathematical model of leaching kinetic of potassium chloride including stirring temperature and leaching ratio is proposed.