| Sintered ash is a kind of iron and steel metallurgical dust with large output,prom-inent environmental pollution problems,and serious harm to iron and steel production processes and equipment.It contains a variety of elements such as alkali metals,heavy metals and precious metals.Resource utilization is of great significance.This paper takes the sintered ash produced by a steel plant as the research object,and develops a potassium chloride separation and recovery process suitable for this kind of iron and steel metallurgical dust.The whole process includes:sintering ash washing,filtrate pu-rification,evaporation concentration,solvent crystallization and solvent recovery Re-cycle.Its main contents are as follows:（1）The elemental composition and physicochemical properties of sintered ashes were systematically analyzed by means of ICP-OES,XRD and laser particle size.The results show that the sintered ash mainly contains elements such as Fe,K,Ca and Na,and the corresponding phase compositions are Fe2O3 and Fe3O4,KCl,Ca CO3 and Na Cl.The particle size（D50）of the cumulative mass fraction of 50%is less than 5.51μm,and the particle size（D90）of 90%of the particles is less than 60.26μm,and the parti-cle size distribution is uniform.The content of potassium in sintered ash accounts for18.11%of the total mass of sintered ash,far exceeding the industrial grade（6%）of conventional potassium ore,and has extremely high recycling value.（2）According to the self-designed potassium chloride recovery process,the potas-sium element in the sintered ash sample is leached by water washing.The optimal leaching process conditions are:solid-liquid ratio 1:4 g/m L,dispersant-sodium do-decylbenzenesulfonate 0.08 g/（100 g sintered ash）,leaching temperature 20～30°C,stirring speed 400 r/min,the reaction time was 40 min,the leaching rates of K,Na,Ca,Mg,Pb,Zn and Cu were 93.97%,85.92%,11.55%,32.09%,6.14%,5.94%and 0.57%,respectively.%.In order to ensure the quality of the product,the light yellow leaching solution was decolorized and impurity-removed.0.04 g of activated carbon and 4 g of potassium carbonate were used to treat 400 m L of the leaching solution,and the chro-maticity was reduced to below 10 Hazen.The total ion concentration of Pb was less than 100 mg/L,and the concentration of potassium chloride in the obtained purified liquid was 67.22 g/L,which was concentrated to 287 g/L by evaporation.（3）The KCl crystallization effect of various organic solvents was simulated by Aspen,and methanol,ethanol and acetone with better crystallization effect were se-lected for comparative experiments.The results show that:compared with other sol-vents,ethanol is the best crystallization solvent,and the best ratio of ethanol to concen-trate is 2:1.By analyzing the ethanol crystallization product,it can be known that the potassium chloride precipitation rate in the concentrated solution is 87.91%,and the product purity is 94.10%,reaching the requirement of the first-class product of the na-tional standard GB6549-2011 agricultural potassium chloride,and the whole process flow potassium chloride is recovered The rate was 72.59%.（4）The ethanol used in the crystallization process was recovered,and the loss rate of ethanol and the effect of secondary crystallization were determined.The ethanol loss rate recovered by distillation at 60°C was 8.44%,the precipitation rate of potassium chloride in the concentrated solution was 61.09%,and the purity of the potassium chlo-ride product was 95.44%.On this basis,in order to further explore the equilibrium re-lationship of each component in the solvent crystallization process,the equilibrium phase diagram of the potassium chloride-sodium chloride-water-ethanol quaternary system at the critical crystallization point was obtained through crystallization experi-ments.,and revealed the basic law of each component change in the process of potas-sium chloride leaching and separation in sintered ash and ethanol crystallization to re-cover potassium chloride products from the phase diagram.scientific basis. |
