Study On The Separation And Extraction Of The Main Components From Air-cooled High Ti-bearing Blast Furnace Slag

The vanadium titanium magnetite in Panxi areas is the world’s leadingmulti-metal deposits in which the iron, titanium, vanadium resource is very rich, sofar, titanium resource utilization is very low, only about15%. The main reason isabout50%titanium in the V-Ti magnetite enter into the concentrate iron ore duringthe mineral separation, after the blast-furnace slag is smelted, which nearly all enterinto the Ti-bearing blast furnace slag containing20～26%TiO₂. At present, more than60million tons Ti-bearing blast furnace slag was deposited by the side of the JinshaRiver, not only wasted a lot of valuable resources of titanium, but also caused seriousenvironmental problems. Despite decades of research, the problem of utilization hasnot been effectively resolved. It is an urgent practical problem to study the separationand extraction of valuable components from the blast-furnace slag.In order to separate and extract effectively the useful component from highTi-bearing blast furnace slag, the paper has studied the chemical composition andstructural characteristics of the air-cooled high Ti-bearing blast furnace slag. It mainlycomposed of Ti, Ca, Si, Al, Mg and Fe, the other trace components of Mn, V, S and P,et al, and the mineral mainly contained pyroxene, perovskite, Ti-rich diopside andMg-Al spinel. Perovskite was dispersed in diopside and spinel minerals. Because ofits dense structure, the slag was difficult to broken.According to the above group of air-cooled high Ti-bearing blast furnace slagstructure analysis, the experimental procedure was divided into three steps. In the firststep, hydrochloric acid and sulfuric acid was used to leach out high Ti-bearing blastfurnace slag, Ti and Si was enriched in the acid leaching residue, Ca, Al and Mg, Fe was enriched in the filtrate. The results showed that the optimum conditions weremixed acid concentration6mol/L （volume ratio of HCl/H2SO4=3:1）, at80℃for5hours, the mass ratio of acid and the slag1.2:1. Under this condition, about64%CaO,88%Al2O3and86%MgO was leached into the filtrate, approximately90%TiO₂wasenriched in the acid leaching residue. In the second step, sulfuric acid was used toextract Ti component from the acid leaching residue by leaching method, the resultsshowed that the optimum conditions were sulfuric acid concentration55%, at100℃for1hour, the mass ratio of acid and the slag4:1. Under this condition, the leachingrate of TiO₂was86%, after calcining, the product was high purity nano-scale titaniumyellow. In the third step, Ca and Mg, Al and Fe components was extracted from theacid leaching solution by precipitation separation method, the product was maturegypsum, magnesium hydroxide, aluminum hydroxide and iron oxide red, while HClgas could be isolated from the acid leaching solution by the distillation method, itcould be collected by the gas collection devices for recycling hydrochloric acid. Theremaining acid leaching solution that mainly contained [（NH）₄]₂SO₄, could be used asthe raw materials which was producted nitrogen fertilizer, non-polluting emissionsfrom the process.