Study On Recovery Of Titanium And Iron From High Titanium Slag Dust

Titanium is the important characteristic strategic resource of China, with great enrichment. High titanium slag dust contains 25~30% titanium oxide, about 20% iron, and 180.9 thousand tons of high titanium slag are produced in 2014, accounting for about 36.19% of total output nationwide, with 602 thousand tons of production capacity and 579 million output value, generating 1 thousand dust per 10 thousand high titanium slag, among which only a small part is added to produce Ti-rich slag, the rest isn’t made fully use of, wasting resources as well as polluting the environment. Thus, to utilize high titanium slag dust reasonably and effectively, developing new technology and methods for comprehensive utilization of titanium, iron and other metals cleanly and efficiently, will bring great economic value and social effect.We use chemical analysis, XRD, XRF, laser particle size analysis, SEM and so on to know about element composition, phase and granularity character of high titanium slag dust. Phase transformation of high titanium slag dust was investigated by heat treatment, which provided theoretical basis for enhancing extraction percentage of titanium from high titanium slag dust. Thesis adopts the route of acid-alkali leaching experiment to deal with high titanium slag dust and explore the optimum process conditions to recover titanium and iron.The thermodynamic calculation indicates that the various main components in high titanium slag dust can react with hydrochloric acid spontaneously. Acid leaching experiment investigated the effects of acid concentration, acid volume to dust mass ratio, leaching temperature and leaching time on leaching rate of main components titanium oxide and iron oxide. Orthogonal experiment result shows that the significant order of factors influencing leaching rate of titanium oxide and iron oxide are the same, as follows: leaching temperature, acid concentration, acid volume to dust mass ratio and leaching time. The result of single factor experiment indicates: when acid concentration is 12mol/L, acid volume to dust mass ratio is 1.5, leaching temperature is 100 ℃ and leaching time is 5 hour, a higher leaching rate of iron and a lower leaching rate of titanium of high titanium slag dust can be obtained. Titanium oxide content in acid leaching residue increases to 39.7%.Iron oxide is obtained from hydrochloric acid leaching filtrate by hydrolysis, with 85% content, and hydrochloric acid is recovered through condensation during this process which can be recycled, greatly reducing the amount of hydrochloric acid.During the process of alkali leaching, sodium hydroxide is used to deal with acid leaching residue which titanium components are relatively enriched while most of iron components are removed off. Meanwhile, the parameters of this process are optimized. The optimum dissolution conditions are as follows: alkali concentration 8mol/L, acid volume to dust mass ratio 1.3, leaching temperature 100℃ and leaching time 2 hour. Grade of titanium oxide under the optimum conditions is 56.4%.