A NEW QUARTZ-GRUSHING MACHINE.

Inangahua Times, Volume VIII, Issue 1282, 10 August 1883, Page 2

A NEW QUARTZ-GRUSHING MACHINE.

+ A model of a new quartz-crushing machine and gold-saving appartus, now on view at the Dunedin Lyceum, presents many points of interest which should recommend it to the attention of quartz-miners. The inventor of the machine is Mr G. Ashcroft, of Wellington, who has submitted a larger and improflpd machine, on the same principle as the model, to severe and continued trials. This machine was exhibited and tested at Wellington some time ago before Sir Willian Jervois, Dr Hector, and a number of practical men, who pronounced themselves astonished at the amount of work performed in a given time by the machine. The model in Dunedin consists of a circular iron trough, the bottom of which is round, and into which are placed two iron balls fitting the rounded trough, allowing no more play than is required for the free circulation of the balls. Two arms, fitted each with a revolving conical wheel, are turned round by a vertical revolving axle to which they are fixed. The object of the conical wheels or cones is to take advantage of the centrifugal tendency of the balls so as to give them another motion on their own axes, and so greatly increase their grinding and crushing power, and also to prevent them from jumping, keeping them firmly on the bottom of the machine. To effect this, the arir.s to which the conical wheels are attached have a lever adjustment, by which they can be raised to a certain level above the greatest bulge of the balls. The conical wheels are, of course placed with their greatest circumffe! rence to the periphery of the trough, which, it may We mentioned, is stationary. Round the trough runs an outward and upward sloping flange, like that_ of a gold-wash dish. This flange consists Almost wholly of wire gauze, except the narrow frames which keep

it in position. Through this gauze the crushed quartz escapes by means of the rotatory motion of the water in the pan, its exit being assisted by two revolving streams of water, which prevent the sloping gauze fro.ti choking by playing constantly upon it. The discharged quartz tailings are caught in a rim outside the machine, and are carried through a tube to the gold-saving apparatus. This consists of a box 3ft long by lft wide, and about 3ft deap, in the bottom of which the quicksilver will be placed. At the bottom of the box are two re\ olving Archimedean screws nearly covering the bottom, which will bring every particle of the stuff into contact with the quicksilver. The discharge from the box is up .hill, and outside the box is attached a tube through which the s<a"e of the amalgam may be tested. The model on view weighs about 3 cwt., and its trough is 1 8in in diameter. Allowing one revolution for each per second, would give a travelling speed of 860 ft per ball per minute. This illustration gives an idea of the crushing power of the machine. With a 2ft pan the motion at 100 revolutions per minute would be equal to 1500 ft per minute, or 25ft per second ; and as machine would be about 1 cwt. each, the crushing power would be very great. One-horse power would be amply sufficient to drive the model machine at the above speed, and also work the gold-saving apparatus. This model would be excellently adapted for prospecting in hilly country, on account of its. portability and the ease with which it is put into operation, as no heavy foundation is required for the efficient working of the machine. The larger machine, which was tested at Wellington, measures, sft in diameter, and, is it stated, capable of reducing 25cwt of quartz per hour, which must be pronounced a very satisfactory result. This invention would admirably suit Otago quartz-miners, as the reefs here, to a very great extent, consist of mullock united with quartz, the machine effecting its work chiefly by the grinding process, although it possesses also, a very considerable crushing power. These two processes combined reduce the quartz to an exceedingly fine and almost impalpable powder in a surprisingly short time. - The effective power of the machine is such that its principle will sooner or later be accepted, and its Usefulness and praticability recognised. The attached gold-saving apparatus is still in a very crude state, and its efficacy has not yet had a chance of establishing itself. The principle upon which it is constructed is one which does not readily commend itself to the practical miner. There is, however, nothing to prevent the amalgamating process taking place in the trough by quicksilver being placed in it, the discharged tailings being turned directly on to blanket-strakes. The cost of a full-sized machine would be about £300 ; and no expensive foundations are required, the machine being complete in itself, portable, and capable of being erected at very short notice at the miue. The inventor spent about two years of spare moments in perfecting it, and no doubt will still improve upon it. Mr James Davidson is the Dunedin agent.