Study On Preparation Of High-grade Synthetic Rutile

In this work,the titanium slag produced from Yunnan province was taken as raw material, the process of preparing synthetic rutile was investigated.Based on the currend research results at home and abord,a new process route of electric titanium slag-alkaline leach-preoxidization-modification-acid leach was explored.Through exploration of each process,the optimum parameters and relevant principles were investigated,at last the titanium-rich materials-synthetic rutile was obtained,it is excellent quality titanium-rich materials through identificated and analysised,which can be meet the requirement of chlorination route producing TiO2.The conclusion of study in the experiment were as follows.(1) The content of titanium slag produced from Wuding region in Yunnan province is relative low,but the purities of Fe,SiO2,Al2O3 content was up to 21%,moreover the titanium slag with high content of Si,Al,low content of Ca,Mg and trace of S,P,C.The particle size distribution was focused on<75μm,96 120μm,150～180μm,nearly 50% focused on 180-830μm, D50=49.5μm.The particle size was uneven,in addition,there were much coarse granularity particle,So it is not suitable for the production of titanium dioxide materials in chlorination route, the further treatment need to research.(2) The mechanism of silicon, aluminum removed from electratic furnace titanium slag was studied, the effect of single-factor which contains stirring speed, particle size, temperature, NaOH concentration, liquid-solid ratio, alkaline reagent on the leaching ratio was examined.The leaching rate of SiO2 and Al2O3 as high as 75%, 50%. The effection sequence of temperature, NaOH concentration, ratio of liquid to solid, time factors was invested by orthogonal experiment, the results showed that the leaching effect is well under the conditions of NaOH concentration of.1.5 mol/L, liquid-solid ratio of 8, the boiling temperature, leaching time of 1 hour.There are 60% of the rutile TiO2 crystallized from the slag whichafter alkaline leaching by pre-oxidatived, the process was controled by the interfacial chemical reactionnd under the temperature of 800℃, the velocity of diffusion is faster, the apparent activation energy is 12 kJ/mol.(3) The effects of modifer,the ratio of S/M,activing temperature,activing time,particle size of the preoxidation slag and acid leaching system on the content of TiO2 in the synthetic rutile were investigated.The results show that the agent of NaOH was relatively ideal modifier,the activing reaction process was carried out under the conditions of temperature 900℃,activing time 120min and slag-to-modifier 5,it can be obtained high purity synthetic rutile assying about 92% TiO2 after high pressure acid leaching-washing-hydrolysis-calcation process from activing product,which meet the requirement of chlorination process in the industry of titanium dioxide pigments.(4) Through the microcosmic structure,phase structure,chemical composition analysised, the obtained synthetic rutile was excellent titanium-rich materials with content of 93.5% suitable for the production of titanium dioxide materials in chlorination route.Based on the rational utilize of electric titanium slag and further perfect reconstruction of existing technology, the new process of electric titanium slag-alkaline leach-preoxidization-modification-acid leach in the preparation of artificial rutile was put forward.this process route has better applicability.The study has opend up new way for efficient use of titanium resources.