MANUFACTURING PROCESS AT ZTMC Ltd.
Kroll process forms the basis of the titanium sponge manufacturing method. Manufacture of titanium by magnesium-and-thermal reduction with vacuum distillation involves the process of cooling of sponge (obtained by magnesium reduction of titanium tetrachloride) before the following heating for vacuum distillation.
Titanium Sponge Manufacturing Process Flow Description
Titanium sponge manufacturing flow chart includes the following basic process stages:
– Titanium slag production by the method of ilmenite concentrate melting in ore-and-thermal furnace;
– Titanium-containing charge preparation;
– Commercial titanium tetrachloride production;
– Commercial titanium tetrachloride rectification;
– Titanium production via magnesium reduction of titanium tetrachloride;
– Vacuum separation;
– Titanium sponge blocks processing.
Titanium Slag Production by the Method of Ilmenite Concentrate Melting in Ore-and-Thermal Furnace
Titanium slag is produced by ore-and-thermal reduction electrosmelting of ilmenite concentrate that contain not less than 63 % of TiO2 and carbonaceous reducer, such as coal, coke or anthracite. The ilmenite concentrate and carbonaceous reducer, pregrinded into blocks under 10mm in size, are melted in the ore-and-thermal furnace (OTF) at 1650-1800оС. Thereafter, slag is discharged and, after cooling-down, is routed for titanium-containing charge preparation. A by-product generated as the result of melting is removed to a storage facility for sale. OTF waste gases are routed to gas purification.
Titanium-Containing Charge Preparation
Titanium-containing charge is produced by blending titanium slag, pitch coke, and sodium chloride (common salt). Before blending titanium slag and pitch coke are crushed. Finished titanium-containing batch is routed to a chlorination area for commercial titanium tetrachloride production.
Commercial Titanium Tetrachloride Production
Commercial titanium tetrachloride is generated by chlorination of titanium-containing charge in molten salt in a salt chlorinator, and by further condensation of the gas-vapor mixture that escapes from the chlorinator to the condensation apparatus system. Titanium-containing charge chlorination process is carried out in a salt chlorinator.
Salt chlorinator is a continuously working apparatus. The casing is cylinder-shaped, the bottom is flat, and the arch is of spherical form. Titanium-containing charge is continuously fed onto the surface of molten salt by the feed bin auger. Chlorine gas is fed into the melt through chlorinator side tuyeres located on its lower part. Two products are discharged from the chlorinator, namely, gas-vapor mixture (GVM) of chlorination products and used melt. Used melt is discharged from the chlorinator intermittently and partially, after cooling-down it is removed to a wastedump. GVM is discharged from the chlorinator continuously and goes to the apparatus system for GVM cleaning and commercial titanium tetrachloride (CTT) condensation. GVM cleaning apparatuses consists of dust chamber, spray-type scrubber. CTT condensation apparatuses consists of two tandem spray-type condensers wherein CTT condensates in the process of cooling. After sedimentation in sediment boxes the generated commercial titanium tetrachloride is routed to the rectification area for purification.
Commercial Titanium Tetrachloride Rectification
Commercial titanium tetrachloride is purified from vanadium, low boiling and high boiling admixtures. Vanadium is removed in a first distillation column cube by lower titanium chlorides (LTC). Rectification process consists of titanium tetrachloride purification from low boiling impurities – first distillation, and from high boiling impurities – second distillation. The process is carried out at a temperature (120-142)оС in distillation columns. In the process of titanium tetrachloride distillation cube remains assemble in evaporator cubes. The remains are periodically removed from the cubes, hydrolyzed, and then are evaporated in an electric pulp evaporation furnace (PEF). As a result a vanadium-containing cake is generated, which may be utilized for vanadium concentrate manufacture.
Magnesium Production by Electrolysis of Magnesium Chlorine
Magnesium is produced by the method of electrolytic decomposition of magnesium chlorine melt and anhydrous carnallite in diaphragm-free electrolyzers. Magnesium dichloride, anhydrous carnallite, fluorspar concentrate, and common salt are used as a process melt for electrolyzers. As the result of the electrolysis process metal magnesium is produced, which, following afterpurification, is routed to titanium production. Chlorine gas is routed to the salt chlorinator, and waste products, namely, slime and slime electronic mixture, are routed to a wastedump or to a Customer.
Titanium Production via Magnesium Reduction of Titanium Tetrachloride
Magnesium reduction of titanium tetrachloride is carried out in reduction apparatuses. Liquid magnesium is fed into a prepared reduction apparatus. A magnesium-containing apparatus is installed into a reduction furnace, and titanium tetrachloride is fed into the apparatus. In the process of interaction of titanium tetrachloride and magnesium MgCl2 is produced. Magnesium dichloride is periodically discharged into a ladle and routed to electrolysis for magnesium production. After completion of the reduction process the apparatus that contain a reaction mass is installed into a condenser for cooling. Cooling lasts not less than 12 hours.
Vacuum Separation
Vacuum separation process is carried out by the following method. A separation apparatus is installed into a separation furnace and furnace heaters are turned on. In the process of heating-up of the separation apparatus a five-hour soaking at a temperature 850оС is carried out. As the apparatus containing the reaction mass is heated-up a turbulent sublimation of magnesium and magnesium dichloride vapors starts and goes on. High temperature soaking (980-1020 оС) begins after completion of apparatus heating-up period. Process time is determined by the grade of a reaction mass and residual pressure in apparatus. After completion of the separation process furnace heaters are turned off, apparatus is filled with argon and cooled at first in a separation furnace, and then in a condenser. After cooling the separation apparatus is disassembled, and the retort containing titanium sponge block is routed for processing.
Titanium Sponge Blocks Processing
Titanium sponge blocks are processed in the following steps:
– Extraction of a titanium sponge block from a retort;
– Determination of titanium sponge block quality class;
– Titanium sponge block separation into parts (bloom and skull);
– Cleanout of titanium sponge remains from a retort (retort sweepings);
– Cleaning of bloom from surface contamination and low-quality constituents (lower cut, side cut, sweepings);
– Determination of bloom and skull quality class and separation by quality class for the following separate processing;
– Crushing of titanium sponge bloom and skull with presses and mills;
– Screening of crushed titanium sponge and separation of commercial fractions;
– Sorting of titanium sponge commercial fractions and defective pieces removal;
– Sampling, packaging into qualified packages (containers, drums), weighing, marking, sealing.
Packed titanium sponge is batched according to contracts and sent to customers.