Thermally Assisted Grinding of Cassiterite Associated with Pollimetallic Ore: A Comparison between Microwave and Conventional Furnaces

We investigated the influence of microwave and conventional heating pretreatments on the grinding of cassiterite associated with pollimetallic ore. The minerals that exhibited a stronger microwave absorption ability crushed first, which is the main difference between the microwave and the traditional heating pretreatments. The distribution of Fe, Pb, Zn, and Sn increased in the fine size range (−0.425 mm). The Fe and Pb grades in the size ranges of −3.2 + 2 mm and −2 + 1 mm after the microwave pretreatment (6 kW, 1 min) were lower than those of the traditional heating (12 kW, 400 °C, 20 min), indicating that the microwave selective heating was beneficial for pyrite and jamesonite. The grade and distribution of Sn decreased significantly in the size ranges of −3.2 + 2 mm and −2 + 1 mm and increased in the size ranges of −0.425 + 0.15 mm and −0.15 + 0.074 mm. Microwave heating treatment promoted the grinding of sulfide ore and reduced the cassiterite overgrinding.