Basic Research On Preparation Of Titanium Powder By Multistage Depth Reduction Process

Titanium is a kind of new structure functional materials,emerged in the 20th century.It’s on the landmark in the history of mankind.Titanium had been widely used in aerospace,chemical industry,metallurgy,light industry and construction industries.Titanium powder is an important titanium material,which is mainly used for advanced fireworks,anti-corrosion coating additives,vacuum getter,aluminum additives,powder metallurgy and 3D printing materials.Now mainly using titanium sponge as raw material prepares titanium metal powder by physical method or hydrogenation-dehydrogenation process Impurities of titanium sponge seriously affected the performance of titanium powder,and restricted development of titanium industry.Because titanium powder preparation methods exist technical problems,this paper systematically analyzed valence evolution in titanium oxide reduction process.and a new idea of multistage depth thermal reduction to prepare titanium powder directly was put forward.First,initial reduction as manner of rapid self-propagating reaction was raised,and initial reduction product(combustion product)was got.and then intermediate was subjected to multistage depth reduction,and depth reduction product was got.Finally,depth reduction product was subjected after leaching impurity,and titanium powder was afforded.Two national invention patent was formed.In this paper,thermodynamic behavior of somd key steps in the process of rapid reduction,deep reduction-deoxidation and leaching,multistage reduction process,leaching process were studied.The main conclusions are as follows:(1)In Mg-TiO2 system,reduction of TiO2 is in accordance with the order of TiO2→Ti3O5→Ti2O3→TiO→Ti,ang Ti/Mg composite oxides may exists.such as 2MgO·TiO2.Mg can react with 2MgO·TiO2.and generate Ti.Adiabatic temperature of Mg-TiO2 system is 2065.92K,so its self-propagating reaction can be performed.Within 1115～1380K,the reduction ability to TiO in the order of Ca(g)、Ca、Mg、Mg(g)decreased in turn.(2)The leaching results showed that at the temperature of room,,leaching time of 120min,solid-liquid ratio of 1:70,leaching times of once,leaching rate of Mg was 96.77%,the recovery rate of Ti was 81.14%.The content Ti of was 79.1%and the content Mg of was 0.83%in leaching product.Its phases were TiO,and a small amount of Ti2O and Ti.(3)The SHS reaction results showed that,overall heating can get lower oxygen content product than local ignition.With magnesium ratio incresing,TiO2,Ti2O3 phase decreased,and Ti and Ti2O increased in the product,the oxygen content in the product decreased.When magnesium excess 30%.spontaneous phenomenon appeared at room temperature,its product main phases was TiO2.When the material was not repression,TiO2 phase appeared in the product,when the system pressure range was 10～40MPa,oxygen content decreased from 20.7%to 19.6%in the product,and irregular mass particles increased in product.Heat preservation process can further reduce oxygen content in the product.With the increase of initial pressure,oxygen content decreased from 17.1%to 13.3%in product,when atmosphere pressure range was 0-0.2MPa.(4)The depth reduction results showed that,leached product and self-propagating product were used as depth reduction materials,and the oxygen contents of two kinds products reduced to 0.235%and 1.22%from 4.11%and 6.82%,when reduction temperature increased from 700 ℃ to 1000℃.Extend reduction time and sintering phenomenon among product particles was intensified.Increasing usage amount of reducing agent,oxygen content of product was further reduced.Minimum oxygen content of self-propagating reaction product was 13.3%,magnesium content was 1.65%;minimum oxygen content of depth reduction product was 0.235%,its impurities(calcium,magnesium,oxygen,nitrogen)content was less than 0.76%.