UPPER THAMES GOLD MINES.

New Zealand Herald, Volume XXXII, Issue 9736, 5 February 1895, Page 6

UPPER THAMES GOLD MINES.

PRESENT ASPECTS AND FUTURE

PROSPECTS. [by OtJR own REPORTER.] KARANGAHAKE DISTRICT.

That there was an improvement in this district was at once " manifested to me on recent visit, by the briskness which was apparent in the township, and it did' nob take long to discover that there was a very large amount of progressive work in hand which will aid in further developing the mineral resources of the district and open up prospects for the future, which will further establish the permanent character of these resources. As a rule, Ido not feel called upon to tender unsolicited to the local governing bodies of districts which I visit, and I do not mean bo make an exception in the case of theOhinemuri County Council, but it was pointed out to me as an anomaly that while all the mines in the district are situated on the Waitawheta and south bank of the Ohinemuri river, there is no traffic bridge across the river. There is a suspension bridge, but it is only available for focb traffic, or for such material as can be conveyed across on a narrow truck. Of course, heavy machinery cannot be conveyed across ib. The Woodstock new planb had to be conveyed across the river by means of a wire tramway ; and no doubt the same course will have to be adopted with the plant now about to be erected for the Talisman, unless the County Council convert the present foot bridge into a traffic bridge. It is said the same suspension ropes and material would meet all requirements, and that at a cheap rate the bridge could be widened so as to make it available for wheel traffic. I am not sufficiently skilled in civil engineering to be able to express an opinion on this head, but the necessity for a bridge of some description must soon force itself on the local authorities.

THE WOODSTOCK. This mine has way v been looked upon as a mosb valuable property, and it has ! proved itself to be a steady gold-producer from time to time, but it has come into greater prominence of late than ever it occupied before. Twelve months ago I referred to the absolute necessity which existed for the erection of a suitable reduction plant with the necessary cyanide plant attached, as all previous experience had proved that mechanical appliances, even of the best description, were incapable of saving even 50 per cent, of the assay value of the gold. The company did, and still does, posse's a little five-stamp mill with the necessary appliances for pan amalgamation, and ore was treated which was comparatively free milling quartz. The returns were sufficient to pay for opening up the mine, but not sufficient to pay dividends. It was wisely decided by the directors of the company during the last year to erect a 10-head battery for dry crushing, and a cyanide plant, and this is now so far completed that it will be ready to start crushing in a few days. The battery is built close to the old one, which has not been dismantled, and is so placed against the side of the hill that,the whole of the operations, except that of raising the ore from the tramway to the kiln, are on the gravitation principle, saving labour as much as possible. The ore is brought along the main tram line leading from the Crown mine through the Woodstock Company, and is then trucked across the bridge over the Wairawheta. at its junction with the Ohinemuri river. Thence the loaded trucks are carried up on an incline tramway, operated by an ingenious contrivance, the motive power being supplied by iron tank trucks which, when filled with water from the race on top of their own incline, are allowed to descend nearly to the creek level, and the weight of these descending tanks which empty themselves automatically when they reach the bottom is sufficient to hoist the laden quartz truck to a platform on a level with the top of the kiln, a height of 50 feet above the .-tonebreaker on top of the battery. The weighting of the tanks and adjustment of the ropes and drums required a great deal of care, but Mr. H. Adams, who has had the erection of the plant and the carrying out of all the details in charge, has proved himself perfectly competent to work everything into good going order. The kiln, where the ore is to be roasted before being delivered into the battery, is 40 feet deep and 17 feet in diameter on top, the bottom being egg-shaped. It is covered with a shed, and is connected by-rail and a travelling tram with the platform on top of the incline tramway. The bottom of the kiln leads into a drive in the face of the hill, and by a tramway the burnt ore is delivered into two hoppers which deliver it automatically as required to the stonebreaker, the whole of the operations being by gravitation. The battery consists of two five-stamp mills, the stampers weighing Bcwt each, having a 5-inch drop, and falling at a speed of 94 per minute. The quartz is delivered from the stone-breaker to the automatic feeders into' the mills, and is in the regular course conveyed as crushed ore to the cyanide vats. The cyanide plant is very complete. The solution comes from the mixing tank by gravitation into the eight percolation tanks. These ar.e square, and each is capable of holding 10 tons of crushed ore, bub it is intended for the present to work only seven ton charges. There are concrete sumps and towers for mother solutions and washings. With the exception, of the square percolation tanks, the whole of the appliances of the plant are of the latest designs, every principle being adopted which has been found to be advantageous in other plants, and speaking of the reduction works and appliances generally the manager, Mr. McCombie, says that Mr. H. Adams deserves the highest credit for the material and workmanship he has put into it. The laboratory and furnaces and weighing room are fitted with all requisite appliances, everything being now ready for a start. Of course, a good deal of firewood will be required for the kilns, and the conveyance of this by the cheapest means has engaged the attention of the manager. To effect this an aerial tramway, 1000 feet span, ! has been extended from the high hill on tho right-hand side of the Waitawheta to the side of the kiln, and along this the wood is delivered over the long span automatically, thus effecting a saving of at least 2s per ton, which is a very material item of saving in a necessary article.

In the mine itself I found that the year's operations consisted more of pushing forward the works then in hand, and opening up the lodes and levels advantageously, than in new workings or investigations. The main or No. 3 level opens on the side of the gorge a considerable height above the creek lovel. The level is connected with a quartz hopper on the opposite side of the creek by means of an aerial tram, and the quartz from this hopper falls into the trucks on the horse tramway for conveyance to the mill. On this No. 3 level the lode known as the Welcome reef, which is only one of three parallel lodes in the mine, has ■ been opened up for a total distance of 420 feet. It varies in size from three to ten feet, widening generally as it is followed into the hill. A leading stope has been carried along the back of the level for a length of 280 feet, and a etope above that for a length of 120 feet, go that it will be seen that it has been well proved, and the manager informs me that throughout it maintains a high percentage of gold and silver, returns and assays from all parts of it being excellent, and at the time of. my visit some very nice ore wai coming to hand, although operations were confined to stripping the reef, there being no room in the hoppers for any more quartz until the mill reduced the quantity on hand. 150 feet in from the crosscut which intersects the reef there is a winze connecting with the No. 2 level, which is 149 feet deep, and with the exception of the two stope3 already referred to, the whole of the reef in this block is intact, while taking the backs from the present face of the drive, which extends 100 feet beyond the corresponding drive on the No. 2 level, the lode is intact for a height of 350 feet to the No. 1 level. A contract has, however, been let now for 100 feet of driving in No. 2 level, in order to split the block to facilitate working. It will thus be seen that on this lode alone there is quartz enough in sight to keep the mill going for years without opening any fresh levels, irrespective altogether of two other splendid lodes, one of which has already yielded extraordinary returns. A peculiar feature is the increasing value of the ore in the deeper levels, the ore from No. 3 level being worth £2 per ton more than that in the No. 2 level. A contract drive is new in progress at the No. 3 level to intersect the reef I known, as Shepherd's lode,£and another

100 feet of driving will cut it under the place where at) the upper level Shepherd and party took out 50 tons of ore, which they shipped to Frieberg for treatment, where ib realised £40 a ton. The crosscut will be continued to intersect what is known as the No. 1, or big 1 reef, fine strong lode varying from 8 to 20 feet in thickuess, and from which a large quantity of gold has already been obtained. On all those reefs additional levels can be opened at a greater depth of 250 feet on the line of the main tramway leading up the gorge, so that the quantity of ore available seems to be unlimited. The manager, however, has still other works in progress. A contract has been let for driving 200 feet in what is known as the Truro section of the mine, on the opposite side of the river, which should bring the level under the rich shoot of ore formerly worked by the Sir. Walter Scott, and giving 150 feeb of backs on the Sir Walter Scott reefs, from which ore can be easily taken to the kilns by a ground tramway 15 chains in length. It will be seen thab the present aspect of the mine is in every respect encouraging, and as to its future prospects, the company have their mine so extensively opened and tested that they can look forward with confidence to steady, profitable returns. Last year I pointed out the necessity for a battery. The company now possesses a very efficient one, bub I think before very long they will find ib necessary to increase it to at least double its present capacity. It was expected that the battery would be ready to start crushing this week, and ib is probable that the directors and leading shareholders in Auckland will visit Karangahake to inspect their mine and battery on that occasion.