THE TREATMENT OF TAILINGS.

Grey River Argus, Volume XXXI, Issue 5344, 14 November 1885, Page 4

THE TREATMENT OF TAILINGS.

[THAMES ADVERTISER.]

Our readers will recollect that a short time since the l^ew Zealand Smelting Company decided, on the recommendation of Mr Lane, to telegraph to America for one of "Frue's Ore Concentrators" to enable them to render the battery tailings more suitable for treatment at their furnace, which has been erected on the foreshore.^ It the concentrator referred to can be made to operate as satisfactorily here as ; t has evidently done in California, our circumstances will be considerably improved, for we will be enabled thereby to not only utilise what is running away to waste just now, but will also be in a position to profitably treat the hundreds of thousands of tons of valuable tailings that have accumulated on oar foreshore sfnce *he opening of the field. In writing of this machine, Mr G. Thureau in his report on m ning in California and Nevada in 1879, says : — "The result of ampies of raw sands washed in my presence in San Francisco for concentration were most satisfactory. Both tailings and black aand, as thrown up by the Pacific Ocean, ■were tested with equally convincing results as to the capabilities of this concentrator. The black sand, which was urixed with 'itaniferous iron-sand, and was more difficult to separate than fine gold and pyrites from tailings, gave, on systematic tests by assay, an average value of 8 dollars and 27 cents per tr.n of un concentrated sand as found in situ at the coast. This sand, after treatment in Frue's concentrator, had been enriched to 1035 dollars 43 cents per ton, with but a slight trace of gold in the tailings," There can be no doubt but that the subjpct of concentration of tailings is a mos* important one, and denr ands greater attention at our hands than it has hitherto received. The product of the concentrator will be saleable for the purposes of the La Monte furnace, or it can be shipped to Swansea, as is now being done by the Bank of New Zealand and others, or to Germany, where the Swansea authorities forward it, after they have dealt with it, and for which they obtain a good price.

The following description of Frue's Ore Concentrator is obtained from Mr Gordon's report : — This machine is simply an improvement in many respects upon the well-known endless blanket first brought under notice by Mr Thomas Carpenter, M.E. Its Calif ornian prototype is on the same principal as a revolving and endless blanket, oniy the materials used are of greater durability, and show some additional improvements in working, which have aided in the perfection of the machine. Two principal rollers at each end of the machine carry th<- belt or end blanket these rollers are made of galvanised sheet iron, rivetted together, 13 inches in diameter and 51 inches in length ; and a large roller, 24 inches in diameter i 3 placed midways, and a few jnches below the line of the lower periphery of the two end rollers, so that the belt "bands" on the top of the end and beneath the intermediate roller. A fourth roller is also provided, made of hard wood, which is geared tn a movable plummer-block by a screw. This screw is also used to take up the slack on the belt caused by the weight of stuff and water, thus preventing the bagging of the belt. This belt is 4ft wide by 27 feet 3 inches long, and it travels on a number of intermediate rollers, so as to keep an even surface. It is made of vulcanised rubber and Al three ply navy canvas, and it has two rims at the sides, raised to 1£ inches, ;hus forming an even narrow channel. The sand (crushed or otherwise) is run through a distributor uoon this revolving belt 'in this way, that the belt travels towards the feed and at the same time an additional supply of water, arranged in irregular drops or jets, is thrown in so as.to prevent the sand from forming ridges or grooves. When working not less than half an inch of sand should cover the belt ; and in order to improve thft action of the belt as a concentrator still further, three flat springs are provided, which are worked by cranks of

the roller. These springs communicate a quick lateral motion, about 190 per minute, to the belt, thus inducing a kind of wavy motion, which results in bringing the lighter sand on the belt to the surface to be washed away. As the belt travels along carrying the sand, the result is as follows :— " The concentration takes place just beneath the feed where the metalliferous and concentrated parts of same are carried in the opposite direction of the* feed, whereas the waste remains on the belt until it falls into a launder at the opposite end. The concentrated pyrites on the belt are immersed in the vessel provided below in the order to be collected. These machines wo::k very eaiily : one lad can attend to more than half a-dozen of them, the only thing that wants regulation being the additional supply of pure water during the process. They maybe placed immediately beneath the tailing shoots, where they can treat from six to ten tons per day. Some kindred concentrators require an inordinate amount of motive power, in some cases up to three or more horse-power each ; but in this in-stan-e from a quarter to half a horsepower is ample for the purpose. This machine is eminently suited for reworking old tailings^