In the vertical roller mill deposit, heavy minerals usually does not exceed 1-3 kg/m3, and the rest are gravel, pebbles, sand and clay. Clay is not good for the fine-grained gold recovery process and should be removed before the gold selection process.

Gold is mostly in the form of granules, flakes and branches in the vertical roller mill deposits, its size generally in the range of 0.2-2mm.Characteristics of vertical roller mill1 Low gold content, generally 0.2-0.3g/m3, and the content of heavy mineral (S>4) is usually 1-3kg/cm3.

The maximum particle size of gangue ore is often several thousand times larger than the minimum grain size of vertical roller mill. That is to say, raw ore of sand gold is in large size, it is necessary to pick out the gold-free gravel and reduce the size of the ore containing ore.