Energy‐efficient comminution and coarse particle liberation of Au‐Ag‐Zn‐Pb ores from Fresnillo’s Cienega Mine, Mexico, by VeRo Liberator® technique

Gregor Borg, Oscar Scharfe, Felix Scharfe, Pablo Gonzalez Jimenez, Salvador Gomez

Physical Separation 2019, June 13-14, Falmouth, UK


Efficiency improvement in the comminution of ores has been on the international agenda of the mining industry for some time but substantial advances are still relatively scarce. It is generally agreed upon that major goals include a substantially reduced energy consumption, improved particle liberation, and the move from ultra‐fine grinding to coarse particle liberation and flotation.

The innovative VeRo Liberator® applies a mechanical high‐velocity comminution principle, where numerous hammer tools rotate clockwise and anti‐clockwise on three levels around a vertical shaft‐ in‐shaft (hollow shaft) system. The resulting high‐frequency, high‐velocity impacts cause a highly turbulent particle flow and trigger fracture nucleation and fracture propagation preferentially at and along mineral boundaries. Breakage of coarser particles occurs from the high‐velocity stimulation of bulk ore particles, where the elasticity and compressibility modules control differential particle behaviour.

The improved breakage behaviour results in a drastically reduced energy consumption of only 3 to 13 kWh/t and very high degrees of particle liberation in the relatively coarse fraction of the product. On an industrial scale, Anglo American applies already two VeRo Liberators® in their South African operations and Penoles and Fresnillo, Mexico, have carried out advanced test‐comminution of ores from several of their gold‐silver‐zinc‐lead mines in Mexico.

The current paper describes results from test‐comminution by VeRo Liberator® of ores from Cienega Mine, Durango Province, Mexico, in comparison to Cienega’s conventional comminution by SAG milling and ball milling. The results show that the VeRo Liberator® achieves a similarly high degree of particle liberation compared to the SAG mill, but at a drastically coarser particle size. This is achieved at significantly lower energy consumption and thus energy costs and allows for more efficient dewatering of comminuted waste material and, consequently, for potentially more stable slimes dams. The mechanical high‐velocity impact comminution by VeRo Liberator® hence overcomes the notorious problems of inefficient breakage in conventional ball and SAG mills.


Gregor Borg (1,2), Oscar Scharfe (1), Felix Scharfe (1), Pablo Gonzalez Jimenez (3), Salvador Gomez (3)

1. PMS GmbH, Abteistrasse 1, D‐20149 Hamburg, Germany. Email: This email address is being protected from spambots. You need JavaScript enabled to view it.‐

2. Economic Geology and Petrology Research Unit, Martin Luther University Halle‐Wittenberg Germany

3. Fresnillo plc, Zacatecas, Mexico

This abstract was published by Research Gate. An article on the VeRo Liberator® was posted by Paul Moore in International Mining on 13 June 2019.