Richard Mozley's legacy lives on with the MGS

Richard Mozley, one of Cornwall's great innovators, died 23 years ago (posting of 4th June 2015). His Redruth company, Richard Mozley Ltd, initially concentrated on the development of small hydrocyclones for desliming feeds to gravity concentrators, but I particularly remember Richard talking enthusiastically, over a few beers, about his latest invention, a shaking table wrapped through 360 degrees into a circular drum which was not only shaken, but rotated to produce a high-G force - one of the first of the enhanced gravity concentrators, which competed with the Knelson and Falcon concentrators. The Mozley Multi Gravity Separator (MGS) was tested at the Wheal Jane mine and then showcased at the 1988 IMPC in Stockholm.

Richard Mozley (2nd right) with the first MGS, Stockholm 1988

The device has since been used successfully around the world for the recovery of ultrafine heavy minerals and is still manufactured in Redruth by a small one-man business, Gravity Mining Ltd, run by a talented and very enthusiastic engineer, Treve Mildren, who has taken Richard Mozley’s initial concept of the Multi Gravity Separator and re-engineered and remodelled some of the internal mechanisms.

Treve invited me over to his premises recently to see the four MGS machines which were being prepared for shipment to Minsur's San Rafael tin mine in Peru for its tailings treatment project. It was also good to see the interest shown by other Cornish mineral processors, with representatives from Wardell-Armstrong (WA), Physical Separation '19 sponsor Holman-Wilfley (HW), and Comminution '20 sponsor Grinding Solutions (GS) being present.

Treve (4th left) with BW, Phil King (WA), Nick Wilshaw (GS), Ben Simpson, Dominic Conybeare (WA),
Dave Goldburn (HW), Joe Marley (WA), Adam Bailey (HW) and Garfield Stuart (WA)

I asked Treve how the current MGS differed from the original Mozley MGS and he said "a lot of R&D, collaboration and advances in material science has produced measurable MGS improvement. The physical separation now happens during the scraping period rather than in between. The scraper blade system used by Richard worked well with low feed rates but quickly became overwhelmed when pushed hard. By using the latest video technology we managed to actually get inside the machine and really see what was going on and how we could improve on it. We quickly discovered the artefact which was limiting the capacity of the MGS and set about correcting it. Now instead of having giant scraper blades pulling everything in their path to concentrate, we use our " Pure Select" blades which can only pull a limited amount, with the rest free to flow over the top, just like a riffle on a shaking table. Our original design intent was to simply improve feed capacity but we have also made massive improvements to produce achieved grades and recoveries on our journey. Our modifications also lend themselves very nicely to a rougher/cleaner configuration in a single pass of a machine, which I believe to be a first for any enhanced gravity device".

Minsur already own and operate quite a number of MGS machines in their main mill, some of which have been in operation for at least 10 years. So why the MGS rather than other well known enhanced gravity devices, manufactured by Knelson, Falcon, Gekko and Kelsey?   Treve said "Minsur have extensively tested all of these technologies at San Rafael mine over the past few years and declare each has its own benefit and downfall. The Senior Metallurgist Jorge Diaze once said to me that the MGS was the best technology for ultra-fine tin. Some of the competition can certainly compete on recovery and capacity but cannot achieve the upgrades of the MGS". 

Treve is doing a grand job here in Cornwall, and I am sure that Richard Mozley would have been very proud.

Twitter @barrywills