Recovery of Fluorite and Garnet from Tungsten Tailings

In September and November 2011, Zhu Yimin and Zhou Jing of the Hunan Research Institute of Nonferrous Metals carried out experimental studies on recovering fluorite and garnet from the tungsten flotation tailings of Huangshaping. A flotation process was used for fluorite recovery, employing a flowsheet of one roughing stage, two scavenging stages, regrinding of the rough fluorite concentrate, re‑treatment of the scavenger concentrate from cleaning, sequential return of the remaining middlings to the cleaning stages, and high‑intensity magnetic separation of the final concentrate. A final fluorite concentrate assaying 97.36% CaF₂ was obtained at a recovery of 57.23%. For garnet recovery, both single magnetic separation and a combined gravity‑magnetic process were tested; both yielded garnet concentrate products. The magnetic separation method produced a garnet concentrate with a grade of 76% at a high recovery of 87.78%.

The Shizhuyuan polymetallic deposit is a world‑class superlarge complex deposit containing multiple valuable components such as tungsten, bismuth, molybdenum, fluorite, garnet, etc. The associated fluorite reserves account for 74% of China’s associated fluorite reserves and 5% of the country’s total fluorite reserves. The fluorite content in the tungsten flotation tailings is generally 18%–22%, corresponding to about 140,000 tonnes of fluorite. Garnet is one of the main rock‑forming minerals in this deposit, with reserves exceeding 54.41 million tonnes, accounting for approximately 27% of the ore in the deposit, representing a very abundant resource. Numerous research institutions and universities in China have conducted extensive studies on recovering fluorite and garnet from the Shizhuyuan tungsten flotation tailings. In September 2011, Li Ji of Shizhuyuan Nonferrous Metals Co., Ltd. carried out experimental research on the comprehensive recovery of fluorite from Shizhuyuan scheelite flotation tailings using collector 733, sulfuric acid as activator, and sodium silicate as depressant. A flowsheet of one roughing stage, two scavenging stages, and five cleaning stages yielded a fluorite concentrate assaying 94.31% CaF₂ at a recovery of 70.06%. In March 2005, Shen Shaohua et al. of Hunan University of Science and Technology, targeting the characteristics of the garnet resource in the Shizhuyuan polymetallic ore, tested a flotation‑magnetic‑flotation main flowsheet as well as a process using spiral chute pre‑concentration followed by high‑intensity magnetic separation and shaking table treatment of the pre‑concentrate middlings to recover garnet from tailings. A garnet concentrate grade of 89% was achieved at a recovery of over 40%.