WAIHI G.M. CO.

New Zealand Herald, Volume XXXIV, Issue 10416, 14 April 1897, Page 5

WAIHI G.M. CO.

THE RECENT DEVELOPMENTS. WET VERSUS DRY CRUSHING. [fbom our own correspondent.] Paeroa, Monday. Before passing from the treatment of the ore, I may state that the question which at present appears to bo agitating the minds of the mill managers in the district is wet versus dry crushing, and experiments are now being made by some of the lending experts with a view to solving the problem as to which method of treatment will give the best results. These experiments were, as already known to the readers of the Herald, commenced some time ago at the New Zealand Crown Mines' reduction works at Karangahake, and the success achieved there has induced the New Zealand Exploration Company, who tire the owners of the mines in question, to permanently adopt the wet system of treatment, preparations for which are already well m hand. In common with other managers Mr, Barry has also the same problem to work out in connection with the ore won from tho Waihi mine, and if it is found, after a thorough trial, that the wet method of treatment is the best for his particular kind of ore, it is, I understand, to be put into practice in tho new mill, consequently several re-arrangements from the original design may yet be made at the new Owharoa works, MOTIVE POWER. Of course, to drive such a large and extensive plant, a great amount of power will be necessary, but this most valuable concomitant has been well attended to, and the requisite water is to be brought in by means of two water-races. The first one has a much higher level than the other, and it has altogether a length of about six miles. This race commences at a point on the Waitokauri stream, a short distance below the Waitokauri Gold Mining Company's mill, and the water is then brought through ,i tunnel 23 chains in length under the kauri bush ; thence over the Mangakura stream, and along the main road to the penstock on the top of what is known as Earl's Hill -overlooking the battery site. Its height at this point is 191 feet above the mill floor, and the pressure pipes from hero convey tho water across tho Ohinemuri River to tno battery. This race will work two Pelton wheels, each of which will be capable of developing MO horse power. The second or low level race commences on the Oliiiicimui River, about four miles above tho mill site, and a costly dam is being constructed to dam the river. Tliis dam is about 110 feet in length, 13 tcet 6 inches in width, with a slight batter on the inner face, and is built of stone masonry and cement mortar, with a stone apron, also set in cement, so that it will be scon a thoroughly permanent job has been made of the construction. The race itself is eight feet at tho bottom, four feet deep, and I'2 feet wide at top, and is estimated to carry 00 sluice-heads of water, whilst it will provide a fall of about 52 feet fiom the dam to the mill. This raco will work two large turbines, supplied by Messrs. liilkia, Gilbert, and Co., of Kenilal, and these two wheels will be capable of developing something like '200 lioran power each, so that it will be soon that, as far as water power is concerned, the company's superintendent has left no stone unturned in order that the necessary power might be available for tho successful working of these immense reduction works. I may state that it was for some time a matter of much consideration with the company whether the power of the water moos should be generated by means of oleotricity and transmitted up to the present mill at Waihi, which, of course, would be still further enlarged, or whether the new mill at r<i'\ should he undertaken and connection effected with tho mine by means of a tramway. It was thought in conneotion with the first proposal that the electric current generated, would lose a considerable amount of power before reaching 'its destination, so that after mature , and careful study, Iho battery proposal at Owlwrua was adopted and the works commenced, This, of course, made the connecting tramway a necessity, anil somo twelve months ;i«o tho tram was commenced. This line was pushed ahead with expedition during the fine weather, with the result that it is now completed with the exception of ballasting, etc., co within I.J miles of the mine. The gaugo of the tramway is 2 foot 9 inches (this boing the ordinary mining gauge, allowing trucks to be easily handled), and is worked by ouo of Messrs. Manning and Wardle's saddle tank locomotives of 0 inch cylinder and 18 inch stroke, weighing altogether about 10 tons. Tho total length of the lino is about l>l miles, and I understand the cost of formation and permanent way was something like £1500 per mile.

Tho tramway and water-races were executed by contract, but all the works at iifcsont in haud are being exocuted by day labour under Mr. Harry's immediate supervision, though he is ably assisted in this work by soveral competent and thoroughly qualified overseers. When this great crushing plant will be ready cannot prcoisoly bo fixod, but I have no doubt it will not bo far off completion by the end of the year. There i« no doubt that the good fortune of Ohinemuri, is closely identified with the operations at tho Waihi Company's mine, and while that great gold producer continues to yield such remunerative returns as it has done in the past, and with increaaii in the bullion production of other properties, Ohinemuri will surely forgo ahead.