Tungsten is one of the strategic metals produced from tungsten ores through sodium tungstate. The hydrometallurgical process is a common technology for extracting sodium tungstate from high-grade tungsten concentrates. The grade of tungsten ore is decreasing, and the mineral processing to produce a high-grade concentrate suitable for the hydrometallurgical process is becoming more difficult. It is desirable to develop a new technology to effectively recover tungsten from the complex low-grade tungsten ores. A fundamental study on the pyrometallurgical processing of wolframite was carried out through thermodynamic calculations and high-temperature experiments. The wolframite was reacted with Na₂CO₃ and SiO₂ at 1050–1200 °C and then leached with water to obtain a sodium tungstate solution as a feed for the traditional process of APT (Ammonium paratungstate). The factors affecting the extraction rate of tungsten from wolframite were investigated in air and neutral atmosphere. The extraction rate of tungsten was found to increase with increasing Na₂O content and decrease with increasing SiO₂ addition and temperature. The extraction rate in argon was higher than that in air for wolframite.

Tungsten is a high-value resource with a wide range of applications. The tungsten metal is produced via ammonium paratungstate, which is a multi-stage process including leaching, conversion, precipitation, calcination, and reduction. A short process to produce tungsten metal from the electrolysis of molten sodium tungstate has been demonstrated. However, sodium tungstate cannot be directly produced from wolframite in the conventional hydrometallurgical process. There was no information reported in the literature on producing sodium tungstate directly from tungsten concentrates. The present study proposed a simple and low-cost process to produce sodium tungstate by high-temperature processing of wolframite. The mixtures of wolframite, sodium carbonate, and silica were melted in air between 1100 and 1300 °C. High-density sodium tungstate was easily separated from the immiscible slag, which contained all impurities from wolframite, flux, excess sodium oxide, and dissolved tungsten oxide. The slag was further water leached to recover sodium tungstate in the solution. Effects of Na₂CO₃/Ore and SiO₂/Ore ratios, temperature, and reaction time on the recovery of tungstate and the purity of sodium tungstate were systematically studied. Sodium tungstate containing over 78% WO₃ was produced in the smelting process, which is suitable for the electrolysis process. The experimental results will provide a theoretical basis for the direct production of sodium tungstate from wolframite. The compositions of the WO₃-containing slags and sodium tungstate reported in the present study fill the knowledge gap of the tungsten-containing thermodynamic database. Further studies to use complex and low-grade tungsten concentrates to produce sodium tungstate are underway.

Tungsten is a high-value resource with a wide range of applications. The end-products of tungsten industry are tungsten metal and alloys that are produced through many steps from high-grade concentrates. Pyrometallurgical extraction of tungsten from complex and low-grade ores has great potential to overcome the problems associated with the hydrometallurgical process. In this study, sodium carbonate and silica were used to extract tungsten from wolframite at high temperatures. Sodium tungstate can be obtained directly from the smelting reaction between 1100 and 1300 oC. The smelting slag is further water-leached to recover sodium tungstate in the solution. The effects of Na2CO3/Ore and SiO2/Ore ratios, temperature and reaction time on the recovery of tungstate and the purity of sodium tungstate were systematically studied, which provides a theoretical basis for the pyrometallurgical smelting process of tungsten extraction.