Abstract
SYNOPSIS The quest for efficiency in comminution is an ongoing concern as comminution usually constitutes a major cost component in the metal production industry. Such improvements can be made by circuit optimization or development of more efficient equipment. A novel crusher, known as the rotary offset crusher (ROC), promises to deliver in this space. The ROC was invented in 2002 by Michael Hunt, Henry Simonsen, and Ian Sinclair, but failed to garner enough support to progress to production. The original design concept was recently rekindled, and a laboratory version of the crusher has been built and commissioned at the University of the Witwatersrand. The crusher is simple in design, with two cylindrical discs that are parallel to each other, and, as the name implies, there is an offset between the vertical axes of the discs. The top disc has a conical section on its lower face, and this creates a crushing zone between the opposite faces of the two spinning discs. Centrifugal motion transports particles through the crushing zone. Batch experiments have been conducted with quartz at various crusher settings (discs offset, rotational speed, and vertical exit gap) for various feed size distributions. The indications so far suggest that the disc speed is a key factor affecting the performance. Size reduction ratios as high as 11 were recorded from experiments with quartz at a speed of 830 r/min. Keywords: rotary offset crusher, comminution, throughput.
Highlights
The mining industry consumes about 7% of global energy (Manouchehri, 2015), of which about 30 to 70% is utilized in comminution circuits (Ballantyne and Powell, 2014; Curry, Ismay, and Jameson, 2014; Jeswiet and Szekeres, 2016; Nadolski et al, 2014; Napier-Munn, 2015; Radziszewski, 2013; Tromans, 2008)
Comminution is, at present, a relatively inefficient process with only a small fraction of the energy, meant for size reduction, being used to effect breakage, with the rest being lost in different forms of energy; such as heat, sound, mechanical losses, and others (Tavares and King, 1998; Radziszewski, 2013; Wills and Finch, 2006)
Innovation to lower comminution costs and effect improvement of the overall efficiency remains a goal for the sustainability of the mineral industry
Summary
The mining industry consumes about 7% of global energy (Manouchehri, 2015), of which about 30 to 70% is utilized in comminution circuits (Ballantyne and Powell, 2014; Curry, Ismay, and Jameson, 2014; Jeswiet and Szekeres, 2016; Nadolski et al, 2014; Napier-Munn, 2015; Radziszewski, 2013; Tromans, 2008). Comminution is, at present, a relatively inefficient process with only a small fraction of the energy, meant for size reduction, being used to effect breakage, with the rest being lost in different forms of energy; such as heat, sound, mechanical losses, and others (Tavares and King, 1998; Radziszewski, 2013; Wills and Finch, 2006). Innovation to lower comminution costs and effect improvement of the overall efficiency remains a goal for the sustainability of the mineral industry. The rotary offset crusher (ROC), under development at the University of the Witwatersrand, has the potential advantage of reducing equipment size as energy can be concentrated in a small space by increasing the rate of rotation of the discs, which aids both particle transportation and comminution frequency
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