The first is divided into high temperature melt extraction and gas injection carbonization.

High temperature melt extraction

    The tungsten concentrate (black tungsten concentrate or a mixture of scheelite concentrate and black tungsten concentrate) is mixed with Na2SiO3 and NaCl, and melted at 1050 to 1100 °C, and the following reaction occurs:

The obtained Na2WO4·8NaCl phase is immiscible with the silicate phase, so it is layered according to density, the base layer is a chloride-tungstate phase, and the upper layer is a silicate phase.

Gas injection carbonization

    After the chloride-tungstate phase is supplemented with NaCl to adjust the fraction, at 1050 to 1090 °C, the natural gas attack is as follows:

WC, WC was washed with 10% HCl and 3% NaOH.