Method for preparing reduced titanium powder by multistage deep reduction

A method for preparing a reduced titanium powder by a multistage deep reduction, comprising the following steps:

• Step 1:
• placing a titanium dioxide powder in a drying oven, performing drying to obtain a dried titanium dioxide powder, uniformly mixing the dried titanium dioxide powder with a magnesium powder to obtain a mixture,
• adding the mixture in a self-propagating reaction furnace, performing a self-propagating reaction and cooling to obtain an intermediate product of which low-valence titanium oxides TixO are dispersed in an MgO matrix, wherein TiO2:Mg=1:0.8-1.2 by molar ratio, and the intermediate product of which the low-valence titanium oxides TixO dispersed in the MgO matrix is a mixture of non-stoichiometric-ratio low-valence titanium oxides, with x being in the range of 0.6-1;
• Step 2:
• placing the intermediate product of which the low-valence titanium oxides TixO are dispersed in the MgO matrix in a sealed reaction kettle, leaching the intermediate product with a hydrochloric acid as a leaching solution to obtain a filtrate and a leached product, removing the filtrate, washing the leached product, and performing a vacuum drying to obtain a low-valence titanium oxide TixO precursor, wherein a molar concentration of the hydrochloric acid is 1-6 mol/L;
• Step 3:
• uniformly mixing the low-valence titanium oxide TixO precursor with a calcium powder in a molar ratio of TixO:Ca=1:1.5-3, and performing a pressing at 2-20 MPa to obtain block-shaped semi-finished products, placing the block-shaped semi-finished products in a vacuum reduction furnace, performing heating to raise a temperature to 700-1200° C., performing a second-time deep reduction for 1-6 h, after the second-time deep reduction, obtaining the block-shaped semi-finished products, cooling the block-shaped semi-finished products along with the furnace to obtain a deep reduction product;
• Step 4:
• placing the deep reduction product in the sealed reaction kettle, leaching the deep reduction product with a hydrochloric acid as a leaching solution to obtain a leaching solution and filtered residues, removing the leaching solution, washing the filtered residues, and performing a vacuum drying so as to obtain a reduced titanium powder, wherein a molar concentration of the hydrochloric acid is 1-6 mol/L,
• wherein the reduced titanium powder comprises the following components in percentage by mass of 98-99.5% of Ti, 0.1-2% of O, and a balance being unavoidable impurities, with a size of 8-40 μm.