Sulfuric acid method is to hydrolyze titanium iron powder and concentrated sulfuric acid to produce titanium sulfate, then hydrolyze to produce metatitanic acid, and then calcine and crush to obtain titanium dioxide product. This method can produce anatase and rutile titanium dioxide. The advantage of sulfuric acid method is that it can use cheap and easily available ilmenite and sulfuric acid as raw materials, with mature technology, simple equipment and easy solution of anti-corrosion materials. Its disadvantages are long process, mainly intermittent operation, wet operation, high consumption of sulfuric acid and water, more waste and by-products, and great environmental pollution. Chlorination and chlorination method is to mix rutile or high-titanium slag powder with coke and chlorinate it at high temperature to generate titanium tetrachloride, and then oxidize it at high temperature, filter it, wash it with water, dry it and crush it to obtain titanium dioxide product. Chlorination can only produce rutile products. The advantages of chlorination method are short process, easy expansion of production capacity, high degree of continuous automation, relatively low energy consumption, less three wastes and high product quality. Its disadvantages are large investment, complex equipment structure, high requirements for materials, high temperature resistance and corrosion resistance, difficult equipment maintenance and difficult research and development.