At present, 50 to 60% of the world's tungsten is used for the manufacture of tungsten carbide. Among them, rock drills in mining tools, three-cone drills in oil extraction, and coarse-grain tungsten carbide used in the hobs of tunnel shield machines account for a considerable part of tungsten carbide.
As the main product of tungsten resource consumption, tungsten carbide can be used as the raw material to synthesize tungsten carbide directly. The tungsten carbide particles can greatly shorten the smelting process, and the ultra coarse grain tungsten carbide particles are widely used in mine rock drilling tools, which have higher added value than the general tungsten carbide.
Some scholars have proposed a method for preparing coarse grained tungsten carbide directly from tungsten ores. The main process is as follows:
Synthetic scheelite was synthesized from pure sodium tungstate and calcium chloride. Spare after drying.
According to the mass ratio of 33:43:8:9:7 to weighing artificial scheelite, reduced iron powder, graphite powder, alumina and silica, the vacuum induction furnace is placed in the vacuum induction furnace, the vacuum degree is less than 10Pa, the 30min is heated to 1600 ℃, and the heating is kept for 1 hours. After natural cooling, the crucible is removed from the induction furnace.
The slag phase and the metal phase are removed from the crucible, then the two phases are separated and the metal phase is removed. The 1:1 hydrochloric acid is added until the metal phase is completely dissolved, and the tungsten carbide is enriched at the bottom of the container.
The WC powder was separated from the solution, washed with water, and then concentrated with hydrochloric acid to remove impurities. After repeated washing, the purified tungsten carbide powder was obtained after drying.
The new method is made of tungsten ore as the main raw material, which is accomplished by reduction of carbonization at high temperature. The molten iron is melted and formed into a metal molten pool. Tungsten enters the molten iron and forms tungsten carbide with its carbon (tungsten is reduced to form tungsten carbide; raw carbon is used as reducing agent to reduce the oxide of tungsten, and tungsten carbide is formed with tungsten). The calcium in the ore will form slag with raw material alumina and raw material silica, and the impurity enters into the slag phase. After rinsing after acid leaching, the coarse grain tungsten carbide particles from several microns to several hundred microns can be obtained. It has low impurity content, complete crystalline form and complete carbonization. It can be used in the production of hard alloy and has great competitive potential.