IMPORTED MINING MACHINERY AT BLUE SPUR.

Otago Witness, Issue 1856, 17 June 1887, Page 12

IMPORTED MINING MACHINERY AT BLUE SPUR.

The experience of mine managers at Blue Spur during some years past has forced upon them the Unwilling conclusion that the days of batteries have been numbered, for it will no longer pay to crush the cement with stampers in the old way. While the richer ground could be worked at easy distances from the machine house, it was profitable enough to put the stuff through the batteries, but now that the under stratum has been worked out it has been [ demonstrated that some machinery capable of reducing a very much larger quantity of material in a given time than is possible with stampers is what is required at Blue Spur in order to make mining a paying venture. For some years now the mine owners have been closely watching the development of mining machinery, but among all the improvements in the direction of quartz crushing, nothing suited to the requirej ments of Blue Spur has been invented. Mr ' Adams, manager of the Gabriels Tailings Company, with considerable ingenuity planned a machine, a model of which was made by the Mines Department and exhibited at the Wei* lington Exhibition. The machine was made I with cylindrical corrugated rollers, two sets of which reduced the cement to sufficient fineness; but it was thought that the machine would be too ponderous and too costly for the work required. Mr Malfroy reported in favour of some modification of the ordinary stone-crushing machine. The Great Extended Company have a stone crusher at work, but the results, while in a measure successful, are not altogether satisfactory. It wus reserved for the firm of M'Queen and Co. to solve the problem, which they appear to hays fully accomplished in a cement-crushing machine erected on the Nelson Company's claimat Blue Spur. The crushing part of the machine conI sists of two sets of wheels revolving towards each other at a high rate of speed. The machine site has been chosen near the centre of the I claim, and consequently in a position where the material can be obtained with the least amount of labour. Two lines of rails are laid to convey the cement in trollies from the faces, and immense quantities of Btuff can be brought down by the aid of powder and dynamite. A turbine winds the trollies up to the machine house and tips their contents into a hopper, whence the stuff drops upon the first pair of crushing wheels. These wheels are 6ft in diameter, and 12in wide at the rim. Three steel tires, 4in by 3in, set side [ by side, form tho crushing face of each wheel. The large wheels are set about 3m apart. From thehopper the cement falls into a revolving cylindrical screen, Gt'L by 3§ft, perforated with holes an inch in dianii'f.c.r. This allows the loose and finer stuff to fall into the race direct, while the unbroken lumps are carried on down the incline of the screen and dropped between the wheels. The roughly brok-en stuff next falls into a smaller cylindrical revolving screen with finer perforations, and is carried on to the second pair of wheels set an inch apart, where it' its reduced finally and delivered into the race. The second set of wheels differs only from the first in diameter, which is 4Mt. The machine is

driven from a turbiue, and in order to f convert the high velocity of the turbine into the reduced speed required in the crushing machine, a combination of pulleys with rope belting is employed. The water power available in the meantime represents 140 in, with a pressure equal to 551b to the square inch. The machine cost about £2000, but the work it is capable of performing would soon make it pay for itself. Mr Johnstone, the working manager, estimates that the machine can easily crush from 250 to 300 tons of cement in eight hours ; while with a further supply of water it is considered the machine is capable of reducing a ton of cement per minute.

One man can attend to the machine and wind up the trucks at the same time. The stuff requires no further handling after it is loaded into the trucks, so that the saving in labour alone is material. In the days of batteries as many men were generally employed to break the lumps for the stampers as were engaged in filling from the drives and faces ; but with this machine one man is able to keep at least a dozen going in the faces. It is not necessary^ to break the lumps below a convenient size for placing in the trucks, as the large wheels will break any size of material likely to fall into them, and they are sufficiently powerful to crush anything likely to be encountered, short of iron itself. The smaller wheels are set lin apart, for the reason that an occasional steel gad from tbe old workings passes through the machine, and were the wheels set closer there would be some danger of shattering them in such a case. On one occasion, however, a gad l^in in diameter passed through, and came out flattened to lin. Still there is great risk were the machine going at a high rate of speed when one of these steel tools passes through. It will be necessary therefore to devise some powerful springs, or have some lever arrangement attached to the smaller wheels to meet the difficulty mentioned. This is only one of several minor details which the experience of working will reveal; but the principle is correct, and the main difficulty has been overcome. Could the Blue Spur claims be amalgamated or worked in one company, with three or four machines like the one working on the Nelson Company's claim, mining at Blue Spur would be a first-class investment, which it certainly is not at present with obsolete methods of cement crushing. It is the intention of M

M'Queen, we understand; to take out a" pa^eiit for his machine, which in every respect appears to fulfil the requirements of the miners engaged upon the refractory Blue Spur cement.