Introduction
Tungsten is an important construction material that has a wide range of applications in high temperature, corrosive, and special temperature resistance processes. It is a strong, rare metal with the highest melting point of metals and one of the densest elemental metals. In addition, tungsten is used as an alloy in manufacturing tools, such as drill bits, as well as in medical and other equipment. In order to extract tungsten from its ores, a variety of processes are used, including hydrometallurgical processes.
Hydrometallurgical Processing
Hydrometallurgical processes are used to extract metals from ores and concentrates that contain high levels of the desired element. For tungsten extraction, a sodium hydroxide solution is often used, although other solutions, such as sodium carbonate and sodium bicarbonate, may also be used. The method chosen for tungsten extraction depends on the ore type and the equipment available.
Sodium hydroxide solutions are generally used in acidic and neutral pH tungsten ores. In this process, the ore is crushed to a size suitable for leaching, usually around 0.1 mm. It is then heated to a temperature of around 80-90°C and then mixed with the sodium hydroxide solution until the desired extraction level is achieved. The resulting leach solution is then filtered to remove any solid matter, and tungsten is then extracted from the solution.
The extraction of tungsten from alkaline tungsten ores is typically carried out using alkaline systems such as sodium hydroxide and potassium hydroxide. In this case, the alkaline solution will dissolve the tungsten ore into tungstate ions. The tungstate ions are then separated from other ions by solvent extraction, and tungsten is extracted from the solution as an insoluble salt.
The tungstate ions can also be separated from other ions by precipitation. This is done by adding a strong acid such as hydrochloric or sulfuric acid to the tungstate ions, causing the tungsten to be precipitated out of solution as an insoluble tungstan oxide.
Conclusion
The extraction of tungsten from ores and concentrates is typically done using hydrometallurgical processes. These processes involve the use of either alkaline or acid solutions, depending on the type of ore and the desired extraction level. Sodium hydroxide is the most common alkaline solution used in the extraction of tungsten, although other alkaline solutions, such as sodium carbonate and sodium bicarbonate, may also be used. Once the tungsten has been extracted from the solution, it is then separated from other ions by either solvent extraction or precipitation. This process produces a tungsten oxide, which can then be further processed for use in a variety of applications, such as in steel, high temperature, and special temperature resistance processes.
