Waterjetting 37e - Using Cavitation to disintegrate rock

In most mines the main objective is to recover as much of the valuable minerals contained within the host (or gangue rock) while minimizing cost. When miners have to go underground and haul the ore to the surface before the minerals are recovered then there is a considerable expense both in hauling all the rock, including the large otherwise valueless host rock, to the surface, and then crushing it to a small size so as to liberate and separate the valuable components.

The work at MS&T, for a number of years, has looked at ways in which rock can be disintegrated, as it is mined, so that the different components are separated as they are freed from the vein. While this work has progressed significantly since it started, this video (of poor quality for which I apologize, but it was what was available at the time) describes where we started the work.

Figure 1. Tom Fort explains the work on cavitation disintegration of rock

  The work was carried on in a number of ways after that, some of which has been described in an earlier post.

Perhaps most relevant to the video at the top of the piece, we were able to develop a more continuous mining process where the material would be mined from the solid in the mine, rather with small hand samples in the lab. While the technology could be easily developed from existing machines now used for hydro-demolition, a more telling picture is to show, by running the product from a test on a sample of dolomite hosting a vein of galena, where the product was run over a Wilfey table.

Figure 2. Mined sample run on a Wilfey table.

The result shows that clear fragmentation of the galena particles and their liberation so that they form a separate (silver) stream on the table from the darker dolomite particles that lie closer to the riffles. It is not quite as easy to see the larger particles of galena which were also separated, but would be more easily recovered perhaps with a screen, since they are not quite as easily streamed from the dolomite.