Monday, 19 August 2013
A few months ago Stephen Grano made some interesting observations on froth flotation, and why it is still so intensively researched (posting of 11th April). He implied that journals may be publishing work similar to that carried out in the past, but now lost in the mists of time. Are we to some extent going round in circles?
In the many comments on this posting Liza Forbes of CSIRO agreed that older pieces of research (especially those older than 30 years) are not known as they should be. She feels that many young researchers base the majority of their knowledge on more recent work, resulting in a progressively increasing lack of citations of older work. She suggested that senior researchers should invest more time with junior staff, to make sure that they are aware of the work that took place decades earlier and of its significance. She even suggested that Minerals Engineering might publish an annual special issue, where people nominate and discuss an old piece of work which they consider to be important, yet largely overlooked, thus reviving/highlighting some golden oldies.
Gravity separation is perhaps the oldest method of concentration, but enhanced ‘centrifugal’ gravity separators began to be commonly used in the 1980s and 90s. My old friend and colleague Tony Clarke send me this description of one of these devices:
The device consists of a cone, working at a minimum 200 r.p.m. (and up to 400 or 600 r.p.m. to increase throughput) with the operating conditions being capable of adjustment to suit. The feed is introduced into the top of a rapidly rotating vertical cylinder, within which there is a set of vanes, rotating in the same direction but at a lower speed. The centrifugal action ‘beds’ the heavier particles against the inner cylindrical surface, while the relative action of the vanes creates a washing motion, to help carry away the lighter gangue. All heavies are trapped within the cone, by centrifugal force, while the waste passes out over the rim. It is said to take less than a minute to stop, clean and restart and will treat 2 tons per hour, at a claimed recovery of 98 to 99 %, with little power and water consumption.
A description of an early Knelson or Falcon concentrator? No, this is an extract from the Mining Journal, of 28th June 1902, describing the Maurice centrifugal gold separator, which was in use at the time in
France on gold-bearing sands! This technique was resurrected many years later, in a laboratory separator marketed by Magstream, while Richard Mozley introduced centrifugal separation to Cornwall on a plant scale, with his MGS separator in the 1980s. Outside of the , other centrifugal separators such as the Knelson and Falcon concentrators for fine gold, and the Kelsey jig also made an appearance. When one compares the description and operating instructions for some of these devices, one is immediately struck by the similarity to the description of the Maurice separator of 1902. county of Cornwall
What do you think? Does the 1902 device highlight valid comments made by Stephen and Liza? Should we be trying to educate young researchers in the need to extend literature searches to way back in the mists of time?