Vertical roller mill usually in coarse size, with high grade and low water content, it is a good source of gold production, but a shortage in small scale.Karst vertical roller mill often produced in karst tunnels and caves.

The width of vertical roller mills is generally 50-300m or wider, and the length can reach several kilometers or even tens of kilometers; generally it is made up of soft sandstone; the buried depth of the ore is generally 1-5m, some would 20-30m even deeper; the thickness of the gold-bearing ore layer is usually 1-5m; the bottom of gold layer is mostly granite, shale, limestone.

In addition to gold, vertical roller mills also contain a variety of heavy minerals, which associated with gold, magnetite, ilmenite, rutile, garnet, zircon, hematite, chromite, olivine, epidote, pyrite, monazite, limonite, platinum, antimony, cinnabar, wolframite, scheelite, cassiterite, corundum, diamond, mercury paste, galena, etc.