A MINING ROMANCE.

Dominion, Volume 7, Issue 1927, 9 December 1913, Page 9

A MINING ROMANCE.

C REFRACTORY ORES, NEW USE FOR GUM TREES. The discovery of the oil Illation proof treaiiny refraetorv ores is one of tiio most important developments in the milling history of .Australia. It means the rescue ol milho-.is of pounds worth of minerals and th<» utilisation of tho gum trees for oil extraction: on a lmpi sca»o, Out- rabbit-canning iYic'iorv. snvs the ''Sydney Horning Herald," ' is already being tiirneii into an establishment, lor this purpose. I'or many years a high extraction of' the metal contents of the Broken Hill shver-lentl-aino ores defied tho siiillcd onMincers and scientiiiesllr-trninefl metallurgists of the "Hill." Numerous K-'iiemes vrere tried- —some incchanical, soiiio a combination of mccha.uism ami chemistry, and some purely chemical— but all failed to achieve a high extraction at a reasonable cost. It was no u?e spending: 13d. to rccovor Is. worth of metal. Laboratory schemes that gave good results iritis a few pounds weight of crushed ore failed to give equally good results when hundreds of tons had to lie treated per week. Broken Hill ;s the grave of an imrnenso amount of money lost- in theso futile experiments. It is estimated that machinery 'and appliances costing over a million of money was "scrapped" in different places before the discovery was made that tho finely-ground particles of metal sulphides could be ir.ado to float to tiie surface of a water tank, whilst the worthless ganguo sank to tho bottom.

What Minss Lost. During ihe years of research experiments wero being made millions of toas oi tailings accumulated, with their valuable metal contents (principally zinc), lu the absence of a cheap and effective method oi l concentration, She huge dumps wero practically valueless, but to-day, owing, to the success of oil flotation; those big tailings heaps are veritable jiokl mines to tne companies that produced them. But .before this goal was reached many thousands of pounds worth of iiiiic and lead must have been literally blown awav iu tho Broken Hill dust storms, liau tho Barrier mines ocen on tho sea coast, like those of Corrimal, tho tailings would have gone into the ocean. It is stated that the pioneer of the hoiatiou process was Potter, who "used sulphuric acid without.oil, Tho Elsmore process, said to have been started some years before, used oil (residual) without sulphuric acid. Then came tho De llavay process, which at first used neither oil nor sulphuric acid, but water with carbonic acid gas, for preparing tho ore for flotation.

Tiic Sulphide Corporation als; evolved n process, based on the use or oil and acid. -There was likewise the acid or oil process!of ill. Delprnt, general manager of the Broken. Hill 'Proprietary, finally, there was the Minerals Sspetatioll Company, with its use of eucalyptus oil, and its amalgamation in Australia with the Do Havay system. The latter process is also a combination of oil and acid, hut is mostly distinguished by replacing crude or residual petroleum v.'ith eucalyptus oil. .Most oils have a strong affinity for minerals. The cleaner aim blighter the particles the more affective the dotation. Tho acid serves two purposes—it cleans the metal particles', and helps the oil to make gaseous bubbles, ©u wl.iieh they lloat to the surface. Use of Eucalyptus. The success of tho mineral:; separation process by the use of eucalyptus oil, instead of ordinary residual or crude oils, iias practically established a new and-important industry in Australia (more particularly in New' South Wales), namely, tho distillation of eucalyptus oil on an enormous scale. It lias been found that the best eucalyptus oil for flotation purposes is obtained from tho peppermint gumtrce, although there are several factories making oil in tho far west from inallco scrub.

Seeing that over a year ago the Minerals Separation Company alone was using 100 tons of oil a year, it may be safely said that, owing to the great oxtension of their system ail over Australia, the consumption now must bo over ions a year, llenco the distillation of oil is likely to become an important industry, for while the mineral separation process is rapidly extending itself all over the world, the production of eucalyptus oil on tho necessary scale and cost must bo confined to Australia. t''or a quarter of a century Broken Hill was a lion-productor of zinc. Now it is one of the world's greatest producers ; simply because of the oil flotation process. Millions of tons of tailings, containing moro actual mineral value than had been extracted from the crude ore. once forming the tailings, accumulated almost as so much waste material, but now they arc being turned into millinns of money by the use of theoil flotation process.