Improving scheelite grade: exploring effective beneficiation methods

Tungsten ore, as the main source of tungsten element, has extremely important industrial value worldwide. There are two main types of tungsten ore: scheelite (wollenite) and wolframite (oxide of tungsten). Although scheelite reserves are large, its rich ore is less and of lower grade, which makes its beneficiation process relatively difficult.

Scheelite often coexists with a variety of calcium and magnesium phosphates, sulfates, carbonates, fluorides and other minerals. The floatability of these minerals is similar, so it is a challenge to select qualified concentrates from these complex ores. In order to obtain ideal tungsten concentrate, scheelite enrichment must be achieved through effective processing technology.

The beneficiation process of scheelite usually includes two main steps: gravity separation and flotation. The combined use of these two methods can effectively improve the recovery rate and concentrate quality of scheelite.

Gravity separation process of scheelite

The high specific gravity of scheelite (5.0 to 6.0 g/cm³) allows it to be effectively separated from lighter vein-like materials by gravity separation methods. When the density difference between scheelite and chalcopyrite minerals is significant, gravity separation can be performed using jigs, shakers or spiral chutes. This process first requires the scheelite particles to be released from associated minerals through crushing or grinding, and then effective stratification and recovery of the particles through jigs or shakers.

Flotation process of scheelite

The flotation of scheelite is a crucial step in the mineral processing process. Selecting the appropriate collector is the key to improving flotation efficiency. Fatty acid-based collectors are the traditional choice for scheelite flotation, but new biosurfactants also show potential to improve selectivity by reducing slime coatings on mineral surfaces. Additionally, selective inhibitors targeting specific chalcopyrite minerals can further optimize the flotation process. The flotation equipment for scheelite includes mechanical agitation flotation machine, air-filled agitation flotation machine or flotation column. The specific choice of equipment depends on the characteristics of the ore and the beneficiation requirements.

In the 500 tons/day scheelite flotation process, the ore is first crushed to a size less than 20mm, and then further ground through a ball mill. The ground materials are classified through a spiral classifier, and the coarse particles are returned to the ball mill for grinding again, while the fine particles enter the flotation process. The flotation process is divided into three stages: the first stage of flotation removes sulfide, the second stage of flotation removes easily floatable impurities, and the third stage of flotation removes calcium-containing gangue. After these three stages of flotation, impurities can be effectively removed, and high-grade scheelite concentrate is finally obtained.

Finally, the flotated scheelite concentrate is dehydrated through a thickener and a disc vacuum filter to obtain a dry concentrate product. The entire scheelite flotation process requires precise equipment selection and configuration to ensure the best beneficiation effect.

To sum up, the scheelite beneficiation process is a complex but efficient tungsten concentrate extraction process. Through carefully designed gravity separation and flotation processes, the recovery rate and concentrate quality of scheelite can be significantly improved to meet the needs of industrial production. With the continuous advancement of mineral processing technology, the processing methods of scheelite are also constantly optimized to adapt to higher industrial standards and environmental protection requirements.