Metallurgical Product Description

Ferro tungsten is delivered in blocks with a block size ranging from 10 to 130mm, less than 10×10mm. The amount of broken pieces should not exceed 5% of the total weight of the batch. The maximum size of individual blocks allowed in one direction is 150mm. The surface of the tungsten iron block should be smooth and clean, with no obvious non-metallic inclusions and rust spots on the cross-section and surface.

Product Parameters

Product Advantages

Characteristics of ferrotungsten

High-density, high weight

high melting point

good mechanical properties

Corrosion resistance

Electronic and electrical applications

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Ferrotungsten is produced from tungsten manganese ore by reducing it with carbon in an electric furnace. Mainly used as an alloying element additive for tungsten-containing alloy steel (such as high-speed steel).

There are three varieties of ferrotungsten produced in my country: W701, W702, and W65, which contain about 65% to 70% tungsten. Due to its high melting point, it cannot flow out in liquid form, so it is produced by the agglomeration method or the iron extraction method.

An iron alloy whose main components are tungsten and iron. It also contains manganese, silicon, carbon, phosphorus, sulfur, copper, tin, and other impurities, and is an alloying agent used in steelmaking. According to the different tungsten content, ferrotungsten is divided into: FeW75 (containing W70%~80%, C≤0.20%, P≤0.04%, S≤0.08%, SAi≤0.5%, Mn≤0.25%) and FeW80 (containing W75.0%～85.0%, C≤0.20%, P≤O.04%, S≤0.08%, Si≤0.7% and Mn≤0.25%).

Tungsten is a silver-gray metal. The atomic weight is 183.85. Density (20℃) 19.3g/cm3. Melting point 3400℃. Boiling point 5555℃. Tungsten forms a solid solution with iron and two intermetallic compounds Fe2W and Fe3W2 or Fe7W6, but they are unstable at high temperatures. The melting temperature of ferrotungsten containing 75% to 85% W is higher than 2500°C, so it cannot be discharged from the furnace and can only be produced by the block method or the iron extraction method. The density of industrial ferrotungsten is about 15.3g/cm.

Method of producing ferrotungsten

The agglomeration method uses an open electric furnace that can be moved on rails and the upper section of the furnace body is detachable, and carbon is used as the reducing agent. The mixed charge composed of refined tungsten ore, pitch coke (or petroleum coke), and slagging agent (bauxite) is added to the furnace in batches. The metal refined in the furnace is generally viscous. As the thickness increases, the lower part gradually solidification.

When the furnace is full, stop the furnace, pull out the furnace body, and remove the upper section of the furnace body to allow the agglomerates to condense. Then the clots are taken out, crushed, and finished; the edges, slag, and unqualified parts are picked out and returned to the furnace for remelting. The product contains about 80% tungsten and no more than 1% carbon.

The iron extraction method is suitable for smelting ferrotungsten containing 70% tungsten with a lower melting point. Silicon and carbon are used as reducing agents; the operation is divided into three stages: reduction (also known as slag depletion), refining, and iron extraction. In the reduction stage, there is slag containing more than 10% WO3 left after the iron was extracted from the previous furnace.

Multiple batches of tungsten concentrate charge are added successively, and then ferrosilicon containing 75% silicon and a small amount of pitch coke (or petroleum) are added. Coke) is reduced to smelting, and the slag is discharged when the WO3 content of the slag drops below 0.3%. Then it moves to the refining stage, during which tungsten concentrate and pitch coke mixture are added in batches, operated at a higher voltage, and impurities such as silicon and manganese are removed at a higher temperature.

After taking samples for inspection and confirming that the ingredients are qualified, iron extraction begins. In the past, steel ladles were used to manually dig out iron blocks and put them into the pool. In the early 1960s, Jilin Ferroalloy Factory switched to mechanical iron extraction devices, which improved working conditions.

During the iron extraction period, tungsten concentrate and asphalt coke materials are appropriately added according to the furnace conditions. The smelting power consumption is about 3,000 kilowatt hours/ton, and the tungsten recovery rate is about 99%.

Thermite method In recent years, to use waste cemented carbide powder tungsten cobalt to separate regenerated tungsten carbide after cobalt extraction, the thermite ferrotungsten process has been developed, using regenerated tungsten carbide and iron as raw materials, using aluminum as the reducing agent, and utilizing The thermal energy of the combustion of carbon and aluminum in tungsten carbide converts the tungsten and iron in the raw material into ferrotungsten, which can save a lot of electrical energy and reduce costs.

At the same time, since the impurities in the raw material tungsten carbide are far lower than those in tungsten concentrate, the product quality is higher than that of ferrotungsten based on tungsten concentrate. The recovery rate of tungsten is also higher than that of processes using tungsten concentrate as raw material.

Tungsten is expensive. In the production process, attention must be paid to improving the recovery rate. Unqualified products and slag iron must be collected and returned to the furnace. The electric furnace should have high-efficiency furnace gas dust removal facilities to recover tungsten-containing dust.