OTAGO GOLD MINING

Evening Star, Issue 20999, 13 January 1932, Page 14

OTAGO GOLD MINING

AN INNOVATION IN METHODS DRAG-LINE DREDGING [From Ode Correspondent.] WELLINGTON, January 13. The familiar dredging and sluicing methods of winning gold on alluvial claims in Central Otago are to be superseded on a largo area at Nokomai, inland from Gore, by an innovation in New Zealand mining. A drag-line excavator is to be used to lift the gravel to the extraction tables, and it is claimed that this is the cheapest known process of working. Within a few days a contract is being placed for hydro-electric equipment for the claim, and full use will be made of the existing pipe lines which had been constructed for sluicing purposes. Power will the be available for the drag-line excavator, which is being built in Auckland, and will be capable of picking up live cubic yards per hoist. It is estimated that tho material which can bo handled by this new equipment will be at least 540,000 cubic yards per annum, and the owners of the claim have already completed a contract for excavation at a cost of sixpence per cubic yard. Another Otago gold-mining development which is m the active stage is in connection with an improved method of working the gold-bearing cement conglomerate on the Golden Crescent Sluicing Company’s holding at Lawrence. A skilled staff has been engaged, and a start made with the provision of equipment for handling this somewhat intractable material. Modern automatic cutting tools are to be used, and tests will be made on a large scale to ascertain tho best method of crushing for the extraction not only of the gold, but the recovery of pyrites. The latter are of substantial 'value in the manufacture of sulphuric acid, for. which there is a good demand in New Zealand from artificial manure manufacturers. At present the makers of superphosphate manures have to import sulphur for this purpose. The intentions of the owners of this large area are ,to erect a plant capable of mining 4,000 cubic yards per day, and from tho analyses of the couglomera this would produce about forty tons of pyrites. The Mines Department has co-operating fully in the two developments described, and for the past three and a-lialf years has been subsidising prospecting operations in these areas. The mining regulations have been modified so that large scale operations can be conducted, as the areas are more suitable for working on an extensive basis.