Preparation Of Ilmenite Oxide Pellets And Research Of Titanium Slags Melting Technology

In recent years,titanium industry developed rapidly in our country,and ilmenite will become the main raw material for titanium industry production in the future.90%of the titanium resources in China are mainly distributed in Panxi area,but most of them are mainly low-grade ilmenite,which needs to be concentrated by beneficiation.In the beneficiation process,multi-stage fine grinding is the most used technology,which causes 80%of ilmenite become fine-grained flotation ilmenite（particle size<0.074 mm）.In this case,transportation and smelting of ilmenite are1 difficult which cause the high-titanium slag cannot be directly prepared.Besides,the ilmenite structure is dense and the impurity element is solid-solubilized,which go against the reduction of iron oxide.Recently,research and practice reveal that oxidized roasting of ilmenite can destroy the structure and change the crystal state of ilmenite,which is beneficial to ilmenite reduction.Therefore,the fine-grained ilmenite utilization in Panxi area to prepare high-quality titanium slag is of great significance to increase the available amount of titanium resources and improve the comprehensive utilization of titanium resources.In this work,the oxidized pellets consolidation mechanism,thermodynamic theory,X-ray diffraction,electron microscopy,and other modern test methods were used to develop oxide pellets for fine-grained ilmenite.Then,the ilmenite oxide pellets were used as raw materials to prepare titanium slag by the carbon-thermal reduction in an electric furnace.The main work and achievements are as follows:（1）Carbothermal reduction thermodynamic of ilmenite oxide pellets was calculated by HSC Chemistry software（the temperature range:473²073 K）.The results showed that iron-compounds can be reduced to iron,while titanium-compounds can’t be reduced to titanium.The titanium-compounds are in the form of low-valent titanium,and the other metallic oxides,such as Ca,Mg,and Al do not undergo a reduction reaction.（2）The suitable process conditions for rolling the ilmenite into pellets are 1%binder and 8%moisture.Non-isothermal oxidation roasting method,when the oxidation temperature is raised to 1000°C,the oxidation degree is 98.75%,and the oxidation reaction ends.The suitable calcination system is calcination temperature1250°C,roasting time 15 min,air flow rate 5 L/min,heating rate 6 L/min,and the compressive strength can reach 482.9 N/ball.（3）In natural alkalinity,the ilmenite oxide pellets were reduced.We found that the suitable smelting temperature should be above 1540℃,the smelting time was30-45 min,and the coke ratio was 8%-10%.The optimum reduction process was obtained by orthogonal experiment.The smelting temperature was 1560℃,the smelting time was 38 min,and the coke ratio was 8%.In this condition,the recovery of iron was increased to 73.34%;the content of TiO₂ in titanium slags was74.86%;.and the reduction degree was 89.34%.（4）The pilot test was carried out by DC arc furnace.When the coke ratio was 6%and 8%,the iron slags were released smoothly and separated well.The grades of TiO₂were 74.2%and 77.9%.Respectively,the FeO content was greater than 4%,which accorded with national and industry standard about acid-soluble composition of titanium slags.S content of the obtained pig iron is controlled to be below 0.07%,which can be further processed to prepare high quality steel.