Study on Gravity and Magnetic Separation Process of an Iron-containing Low-grade and High Slime Tin Ore in Changning

The main useful metal mineral in the tin ore from Changning is cassiterite, followed by limonite, the main gangue mineral is quartz, and tin mainly exists in the form of cassiterite and acid soluble tin. The tin ore with tin grade of 0.166% and yield of −0.074 mm fine slime of 24.61% (−0.019 mm fine slime of 14.27%) belongs to an iron-containing, low grade, high slime and refractory tin ore. Based on the study of the properties of a refractory tin ore from Yunnan, the beneficiation process of the ore was studied. Test results showed that: the raw ore was crushed to −12 mm and classified by washing with 0.212 mm particle size. After the + 0.212 mm coarse grains were crushed to −3 mm and ground to −0.074 mm occupying 55.85% and then merged with −0.212 mm fine grains as raw ore, separation flowsheet of pre-discarding tailings by spiral chute - separation of chute concentrate by shaking table -iron removal from shaker concentrate by high intensity magnetic separator was adopted to separate the raw ore .Tin concentrate with yield of 0.21%, tin grade of 41.32%, tin recovery of 52.27%, tin rich middling with yield of 0.75%, tin grade of 4.750%, tin recovery of 21.46%, and cumulative recovery of tin concentrate and tin rich middling of 73.73% was obtained. The quality of tin concentrate, which realized separation of tin from the raw ore, meets the concentrate level of grade VII category I of YS/T 339-2011 standard.