Although tungsten is a strategic mineral, it is also a minor metal. The demand for tungsten is low relative to base metals like nickel, zinc or lead. As a result, commodity exchanges do not trade tungsten ores and concentrates. Trading occurs on a negotiated basis between the parties involved.
Tungsten ore is mainly in the form of wolframite ((Fe,Mn)WO4) or scheelite (CaWO4). Mines are typically underground hard rock mines. Up to 80% of the world’s tungsten ore today comes from China. There are active mines throughout the world in Africa, Asia, Europe and South America.
Tungsten ores and concentrates sell on the basis of their tungsten oxide (WO3) content. The ore undergoes gravity separation to concentrate it at the mine. A chemical flotation process can remove additional impurities to increase the concentration before shipping. The industry standard for first grade tungsten concentrates is a minimum of 65% WO3.
The trade in tungsten concentrates has decreased since many of the companies controlling the mine output have vertically integrated to produce tungsten intermediates. The most common of the intermediates are ammonium paratungstate (APT) and tungsten oxides such as yellow tungsten oxide (YTO) and blue tungsten oxide (BTO).
Price references for tungsten are based on private transactions. Companies such as Argus Media and Metal Bulletin have regular contact with industry sources to ask for current offer prices in the market and report a range with a high and low price. The price of APT is the most common reference material. Many long term contracts will be based on one of these published references.
In international markets the unit of measurement for tungsten concentrates is the metric ton unit, or mtu. An mtu is 1% of a metric ton. Both tungsten concentrates and intermediates such as APT, BTO and YTO use the mtu as the standard measure.
One Metric Ton (MT) = 1000 kg
One Metric Ton Unit (mtu) = 10 kg