Known for its exceptional strength and high melting point, tungsten is a vital metal in various industries. Tungsten is essential in producing many important products, from aerospace engineering to electronics manufacturing. However, this versatile metal does not occur naturally in its pure form and is found in almost every kind of rock, from which it must be extracted through a complex process.
As the demand for this versatile metal continues to increase, so does the need for efficient extraction methods from the ore. Extracting tungsten from the ore involves complex processes to separate it from other minerals and impurities before it can be converted into valuable products. Therefore, we use highly efficient beneficiation methods for extracting tungsten from ore while ensuring high purity and minimizing environmental impact.
Type of Tungsten
It is a tungsten-containing mineral ore widely used in various industrial and military fields because of its high melting point, high density, good corrosion resistance and excellent electrical conductivity. Types of tungsten ores are usually classified based on the main minerals and components within them.
- Scheelite: Also known as tungstate ore, it is one of the most common tungsten ores. Its chemical formula is CaWO4, and its main component is calcium tungstate. Scheelite is an important tungsten ore widely distributed all over the world.
- Wolframite: Also known as tungstate ore, its chemical formula is FeWO4. Wolframite is another important type of tungsten ore with a high tungsten content.
- Cassiterite type tungsten ore: The type is associated with cassiterite deposits and contains tungsten-containing stannate minerals.
- Quartz Vein Tungsten Ore: This type of tungsten ore is associated with quartz vein deposits, where tungsten occurs in quartz veins.
The composition and mineral composition of tungsten ore may vary depending on the geological conditions of the deposit. Different beneficiation and smelting methods may be used in mining and extracting tungsten depending on the specific ore type. Among them, scheelite and wolframite have high mining value and are also the main source types of tungsten resources.
Tungsten Ore Extraction Method
It mainly includes physical methods such as flotation, gravity, and magnetic separation. For refractory medium ore and low-grade concentrates, chemical beneficiation is preferred.
- Flotation: Flotation is one of the most commonly used tungsten ore extraction methods. It is based on the density difference between tungsten minerals and other minerals and uses flotation agents and air bubbles to separate tungsten minerals from ores. This method is suitable for ores containing higher tungsten sulfide minerals.
- Gravity separation: Gravity separation is a method of sorting according to the difference in specific gravity between tungsten and impurity minerals. Commonly used gravity separation equipment includes centrifuges, shakers, etc. This method suits ores with finer grain sizes and more non-tungsten sulfide minerals.
- Magnetic separation: Magnetic separation processes ores containing magnetic tungsten minerals. Magnetic tungsten minerals are separated from ores by a magnetic field. This method is often used for ores containing magnetic tungstenite.
These methods are mainly used in combination according to the characteristics of the ore and the requirements of the beneficiation process to obtain a higher extraction rate and purity of tungsten. At the same time, in practical applications, steps such as pretreatment, ore crushing, and ore grinding may also be involved to optimize the beneficiation process.
Wolframite Extraction Process
Wolframite is a common tungsten ore whose main component is calcium tungstate (CaWO4). The main flow includes as follows:
- Crushing and grinding: The original wolframite ore is crushed and ground to make it smaller into smaller particles, which is convenient for subsequent beneficiation.
- Gravity separation: This process utilizes the density difference between wolframite and waste materials such as quartz and feldspar. By applying centrifugal force or using a shaker, the heavier wolframite particles settle to the bottom while lighter impurities are removed.
- Flotation separation: use flotation to separate tungsten minerals in wolframite from other impurity minerals. The wolframite concentrate obtained through flotation may still contain certain impurities, and further concentrate treatment is required to improve the purity of tungsten minerals.
- Magnetic Separation: Wolframite separated by washing is subjected to magnetic separation to remove any remaining magnetic minerals such as magnetite or hematite. This step ensures a higher concentration of pure wolframite for further processing.
In addition, some wolframite ores may contain other valuable metal minerals, which can be extracted and separated by beneficiation methods such as electric separation.
Scheelite Extraction Process
Scheelite is an important tungsten ore, mainly containing tungsten oxides. Scheelite has good buoyancy, but it is often associated with fluorite, calcite, apatite, barite, gangue and other minerals with similar buoyancy to calcium and barium, which increases the difficulty of separation. To improve the flotation selectivity of scheelite and calcareous gangue minerals, ferric sulfate and other polymetallic salts are often combined with sodium silicate to enhance the flotation effect of scheelite. The following is the general extraction process of scheelite:
- Rough separation: After the scheelite ore has undergone ore crushing and grinding steps, most of the impurities and non-tungsten minerals in the ore are removed by gravity separation to obtain relatively pure scheelite rough concentrate.
- Concentration: Further separation of scheelite crude concentrate; commonly used methods include gravity separation, flotation and magnetic separation. Among them, gravity separation is the most widely used method. By using heavy media or centrifugal force to separate minerals of different densities in the ore, the purpose of improving tungsten grade and recovery rate is achieved. Flotation is to separate tungsten minerals from impurity minerals by air bubble adsorption. Magnetic separation uses magnetic differences to separate magnetic minerals from non-magnetic minerals.
- Washing: After being selected, the scheelite ore may still contain certain impurities and needs to be cleaned. Commonly used methods are water washing, pickling and alkali washing to remove impurities and oxides on the surface.
- Concentrate treatment: The cleaned scheelite concentrate is subjected to ore heat treatment or smelting to obtain the final tungsten product. Common heat treatment methods include roasting, reduction and smelting, etc., which can remove residual sulfur, oxygen and other impurities. Smelting is usually used for high-grade scheelite, and tungsten products with higher purity can be obtained through high-temperature smelting.
Extracting tungsten from ore is a complex process involving multiple stages and techniques. Among them, the extraction process of wolframite and scheelite is a complex and labor-intensive operation that requires careful planning and execution. From the initial ore crushing and grinding to the separation of tungsten minerals from gangue materials, the extensive use of gravity separation, magnetic separation, flotation and electric separation processes is helpful for the further purification and concentration of tungsten. Ensure a steady supply of this valuable resource while minimizing its environmental impact using our tungsten extraction processes and equipment.