NEW MINING METHODS

Evening Star, Issue 21010, 26 January 1932, Page 9

NEW MINING METHODS

TO BE APPLIED AT NOKDMAI THE DRAG-LINE'EXCAVATOR One of the most interesting developments in the present mining revival is the attention which is being paid to new and up-to-date methods. It has long been recognised that many auriferous areas exist which only require the use of economical methods to make them highly productive. Such a development is not peculiar to New Zealand. • In Western Australia large areas of low- grade quartz, are now being worked more profitably on mass production principles. In Queensland low grade silver lead zino deposits are being worked on a prodigious scale. In New Zealand the application of drag line bucket and scraper excavators to claims hitherto considered too. costly to develop by sluicing and elevating will probably bring into production large areas of auriferous gravels. In view of that development the Dunedin public will be interested in a working model at present on view in the Vulcan Steel Construction Company’s shop in Broadway. The Vulcan Company, whose head office is in Auckland, has made this model, and holds the contract to supply and deliver a very large drag-line excavator (with other plant) for use by the Nokomai Gold Mining Company on its claim near Parawa. The drag-line excavator is a wellknown contrivance for handling gravel and other material in mass at a low cost, but this is the first time that it is being tried out for gold mining in New Zealand. Its adaptability for that purpose is due to improvements thought out by Mr J. S. Whittaker (general manager of the Vulcan Steel Construction Company), aided by Mr Charles Medley (an experienced worker of such scoops). . , • ,^ A demonstration by means or \ the model was given this morning for the benefit of the directors of'the Nokomai Gold Mining Company,, and an hour later representatives of the Press were invited to see the working. The device consists of a bucket that scrapes up and lifts the gravel and drops it on to a “ grizzly (or Sieve), the big stones being thrown out and the finer stuff deposited on a conveyer belt which delivers into a hopper, another belt carrying the stuff to a screen for treatment in the ordinary way. Mr Whittaker states that the plant to be installed at Nokomai is based on standard principles, but is being specially strengthened to meet any contingency, and provided with many special features to meet the particular iequirements of the Nokomai claim. It is designed to carry a 5 cubic yard drag line scraper bucket, and its guaranteed capacity is 120 cubic yards per hour. It is being equipped with very modern controls, automatic devices and brakes to enable it to operate at high velocity, and the whole of the operations of the machine are recorded on indicators m the control room. The generator set which was being installed will develop over 500 h.p. The greater part of the plant is to be manufactured in New Zealand, but certain special parts it will be necessarv to import from overseas. Mr Whittaker anticipates that the plant can bo manufactured and delivered in six months. He forcasts that within the next two years many dragline equipments will be operating successfully on the gold hearing wash ot Otapo Central. , , The model worked quite satisfactorily this morning. _ The newspaper men were impressed with the safety appliances. which ensure (1) that the bucket does not run to the tower, (-) that the carrying rope is not overstrained, (•>) that all the action is indicated on the switch hoard, so that the operator has continuous and perfect control. The Nokomai Company has command of 200 heads of water, and it was explained by Mr G W. Thomson, the mining engineer, that this water will lie adequate for generating the power to produce the required driving electricity besides being available, when spent of power, for the washing that is a necessary sluicing operation. Mr Thomson also called attention to the fact that this Nokomai dredge will bo essentially a dryland dredge, so that no gold found will slip away unseen.