| Iron ore sintering is used as an important preparation process of blast furnace burden in iron and steel production.The process can produce a lot of flue gas, which is dedusted by the ESP and form sintering head ESP dust. The ESP dust is referred sintered ash, which contains high levels of potassium and lead. Because these two elements are harmful to steel production, the sinter dust is not suitable for direct return to the sintering ingredients, therefore, It is imperative to develop new processing to treat the dust. In this paper, basic research of sintering ash was carried out, such as chemical composition, mineralogical properties and dispersion in water. Based on the research, a new process for comprehensive utilization of sintering ash was developed, which contained water washing, magnetic separation and chloride leaching.Basic research on comprehensive utilization of sintering ash showed that, in the secondary electric field sintering ash, the content of potassium and lead is high(> 6%). Iron in the dust exist mainly in the form of magnetite and hematite, and magnetic iron content is high. Potassium and lead in the dust exist mainly in the form of KCl and PbOHCl respectively. Adding a small amount of inorganic acid and surface active agent could significantly improve the sintered ash dispersion in water.The dust suspension could well disperse aqueous solution by the addition of 2 % sulphuric acid and 2‰LAS.In the removal of potassium by water washing, at leaching temperature 30℃, solid-liquid ratio 1:4 and stirring speed 100 rpm, 97.57 percent of the potassium could be removed within 30 min. After purified by carbon dioxide gas, decolorized by active carbon and added ammonium sulfate into the leachate to carry out double decomposition reaction, and then by condensation and crystallization, agricultural potassium sulphate was prepared. The agricultural potassium quality met the requirements of GB20406-2006 requirements in agro-qualified products.It was appropriate to recycle iron from sintered ash by wet gradient magnetic separation(weak magnetic strength of 2000 oersted, magnetic strength of 16000 oersted). It could get the coarse concentrate with 55.23 percent iron content, iron recovery close to 71.34 percent. The lead content in the tailings increased to 11.52 percent. The enrichment ratio of lead was 1.93. The preparation of highly dispersed suspension of sintering dust and and the magnetic field strength of magnetic separator were key to the magnetic separation process, which decided concentrate grade of iron ore and iron recovery.In chloride leaching experiment, the factors that affect the leaching rate of lead were found with the following order: NaCl concentration> amount of hydrochloric acid> reaction temperature> reaction time> solid to liquid ratio. Optimum leaching conditions were as follows: NaCl concentration 260 g/L, hydrochloric addition 20 mL/100 g(tailings), leaching temperature 85℃, leaching time 30 min, the ratio of tailings to sodium chloride solution 1:2. In this condition, the leaching rate of lead could achieve 97.65 percent. Lead oxide were prepared from the lead leachate by oxidation and hydrolysis of iron followed cooling and dilution, precipitation transformation and high-temperature calcination. the purity of lead oxide was over 99.3 percent.A pilot scale test on comprehensive utilization of iron and potassium in sintering ash shows that, the recovery process of potassium and iron, the main process parameters , pilot equipment design and equipment selection were feasible. The quality, technologies and economic index of these three products such as iron ore , agricultural potassium sulfate and mixed crystal products have reached the research project targets.
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