Note: Ferrotungsten belongs to ferroalloy series (tungsten content: 70% - 80%), which is an alloy composed of tungsten and iron, and is used as an alloy additive for steelmaking. The commonly used ferrotungsten contains 70% and 80% of tungsten. Ferrotungsten is smelted by electric furnace. Due to its high melting point, it cannot be released in liquid state, so it is produced by agglomeration method or iron extraction method. Before the 1930s, small-scale (100~500 KVA) single-phase electric arc furnace was generally used for agglomeration smelting. Later, three-phase electric furnace was used, and iron making method was developed.