| ABSTRACT:With the depletion of high-quality titanium resources, low-grade ilmenite has become the main raw material of titanium industry in China. Due to the characteristics of ilmenite resources and the deficiency of available technology, the overall industrial utilization rate of low-grade ilmenite is very low, and production cost is relatively high. Therefore, investigation on the efficient and comprehensive utilization of low-grade ilmenite resources has important strategic significance.Element content, mineral composition and content, as well as mineral dissemination size characteristics of an ilmenite from Gansu province were investigated by some methods, such as XRD, XRF, SEM, chemical composition and laser particle size analysis. The results show that TFe and TiO2content in this low-grade acidic ilmenite ore are only12.23%and3.80%, respectively. Fe distributed in magnetite that can be easily utilized accounts for only37.86%, and the rest is distributed mainly in silicates and ilmenite. Ti distributed in the purpose mineral, namely ilmenite, accounts for70.26%, and the rest is distributed in magnetite and silicate. The gangue minerals are mainly feldspar, hornblende, followed by pyroxene, chlorite, montmorillonite, mica, epidote, spinel, apatite, etc.Based on the mineral characteristics and the fact of serious water shortage status in mining area, a joint technology solution of "dry magnetic preselection-low intensity magnetic separation after regrinding-high gradient magnetic separation and flotation" was designed. The optimum process conditions determined by experiments are: magnetic induction intensity of dry magnetic separation is0.40T, and ore particle size is below3mm; particles below0.074mm in the grinding fineness of dry magnetic separation concentrate account for88.4%, magnetic induction intensity of weak magnetic separation is0.075T; magnetic induction intensity of high gradient magnetic separation of weak magnetic separation tailings is0.90T; high gradient magnetic separation concentrate is separated by flotation under the condition that H2SO4and Na2SiO3are used as adjusting agent, MOH is used as collecting agent, a circuit of one roughing, two scavenging, and four concentrating is adopted as flotation flowsheet. By the technology above, the obtained iron concentrate had a grade of60.57%and the recovery of35.14%, and titanium concentrate had a grade of46.15%and the recovery reached66.19%, the comprehensive recovery rate of Fe in the whole process was up to52.89%.The preparation of synthetic rutile using the obtained ilmenite concentrate under milder conditions by hydrochloric acid leaching was studied. The results show that the optimum process conditions are as follows:HC1stoichiometry is1.2, HC1concentration is20%, reaction temperature is the boiling temperature110℃, stirring intensity is300r/min,2%(relative mass fraction of ilmenite concentrate) Fe powder is added after30min (may be added more than once to prevent instantaneous violent reaction in a time interval of half an hour, depending upon the situation), react time is6hours, releach the obtained leaching residue with a HC1stoichiometric ratio of0.3(calculated from the pre-leaching ilmenite concentrate) and concentration of20%under110℃and stirring intensity of300r/min for1h, leaching solution returns to the first leaching step. Through the above process, a synthetic rutile with TiO2grade of92.34%and recovery of more than97%was achieved. |
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