Recycling of Titanium Production Waste with the Extraction of Valuable Components

Abstract

Chloride wastes of the Ust-Kamenogorsk Titanium-Magnesium Plant of the Republic of Kazakhstan are formed in the production of titanium spongy by reduction of titanium tetrachloride with metallic magnesium. Multi-tonnage waste contains a number of rare and alkaline earth metals, including titanium. A significant part of this waste in the form of chlorides is neutralized with milk of lime and stored in sludge ponds, the reserves of which can be attributed to technogenic. The studies of this work were used to develop a technology for the integrated processing of sludge accumulator sludge with the extraction of titanium dioxide and calcium nitrate. When sludge is leached with nitric acid, calcium transforms into soluble calcium nitrate, and titanium compounds into a precipitate. Purified solutions of calcium nitrate are used to crystallize calcium nitrate. The titanium-containing sediment is subjected to fluoroammonium treatment with ammonium bifluoride. First, the precipitate is sintered with ammonium bifluoride at a temperature of 200 °C for an hour. Ammonium hexafluorosilicate was sublimated from the obtained cake at a temperature of 300 °C for 6 hours, and silicon fluorides were converted into silicon dioxide by alkaline hydrolysis of ammonia water. Then the cinder, in which the titanium compounds remained, is sintered again at a temperature of 200 °C for an hour to convert the remaining titanium into titanium tetrafluoride. Titanium tetrafluoride was sublimated from the cake at a temperature of 800 °C for 4 hours, and titanium fluorides were converted into titanium dioxide by alkaline hydrolysis of ammonia water. By drying and calcining, titanium dioxide was obtained in chemical composition close to that of pigment titanium dioxide.