CARBOTHERMAL REDUCTION AND NITRIDATION OF ILMENITE CONCENTRATES AND CHLORINATION OF THE REDUCED SAMPLES

摘要

Metallic titanium and titania white pigment are produced from titanium tetrachloride which isobtained by carbochlorination of natural or synthetic rutile at 800 - 1100℃. Chlorination of titaniumoxycarbonitride can be implemented at 200 - 400℃. Low temperature chlorination can improveefficiency of production of titanium tetrachloride. The paper discusses carbothermal reduction ofilmenites of different grades (primary, secondary and HYTI 70) and synthetic rutile and chlorinationof titanium oxycarbonitride in reduced samples.The main phases of primary and secondary ilmenites were Fe_2Ti_3O_9 and FeTiO_3; HYTI 70 gradealso contained TiO_2; synthetic rutile consisted of titania with traces of metallic iron and sub-oxides.Temperature programmed and isothermal reduction experiments were conducted in a fixed bedreactor in hydrogen-nitrogen gas atmosphere. Iron oxides were reduced by hydrogen to metalliciron. Titania was reduced to sub-oxide Ti3O5 which was converted to titanium oxycarbonitride.In chlorination experiments, titanium oxycarbonitride, metallic iron, and unreduced Ti_2O_3 werechlorinated. Chlorination of Ti_2O_3 was slow relative to titanium oxycarbonitride and iron. Chlorinationof impurity oxides such as silica, magnesia, and alumina was not observed. Degree of chlorinationof both iron and titanium oxycarbonitride at 235℃ was 95 - 98 per cent; chlorination of iron wasfaster than that of titanium oxycarbonitride. The removal of iron by leaching increased the titaniumoxycarbonitride chlorination rate; it was close to completion at 235℃ in 35 min.