Wastes in Mining. 321 



III. — The Waste of Material. 



In considering the third kind of waste in mining, that of 

 material, the subject divided itself naturally into two sub-heads : — 



ist. — The waste of the mineral sought for. 



2nd. — The waste of materials used in the process of acquiring 

 the mineral. 



On the Witwatersrand enormous strides have been made in reduc- 

 ing the first-named waste. In 1891, on one of the better managed 

 Companies of those fields, a close inspection of the gold returns 

 showed that only 57 per cent, of the assay value of the ore was 

 recovered. In other words, for every sovereign's worth of gold con- 

 tained in the ore treated, only 11 shillings and fivepence worth were 

 recovered ; whereas under the latest metallurgical practice on those 

 fields by the use of tube mills, 95 per cent, of the assay value of the 

 ore has been banked. This means that out of every sovereign's worth 

 of gold contained in the ore treated, 19 shillings were put into the 

 Bank. 



Of course, the difference between 11 /5 and 20/- was not all 

 lost. A large portion of this difference was contained in the tailings 

 which were stored and treated in subsequent years. None the less, 

 an immense advance in metallurgical practice has been made ; so 

 great indeed has this advance been, that on the best equipped mines 

 little remains to be done in the direction of reducing waste of the 

 comjpnodity sought for. The ingenuity of the engineer is exercised in 

 bringing older plants into line with the newest practice at the least 

 cost for capital expenditure. 



The waste of stores used on the Gold Mines of the Transvaal 

 has been great in the past and continues at an excessive figure. This 

 is a case where the directing brain is practically at the mercy of the 

 performing hands. Large reductions have been made in the cost of 

 coal, explosives, cyanide and candles^ which form the four largest 

 items of expenditure of the gold mines. In the case of coal, this 

 reduction has been achieved by decreasing the railway rates, and also 

 by a slight reduction in the price at the pit's mouth. The cost of 

 dynamite has been reduced nearly one-half through the freeing of 

 the country from the grip of the former monopoly. Through 

 improvements in manufacture, and by the competition of manufac- 

 turers, the cost of both cyanide and candles per unit consumed has 

 been greatly reduced. As far as coal and cyanide are concerned, a 

 close supervision of their consumption has taken place and continues 

 to occupy much of the energies of the engineering and metallurgical 

 talent on the Witwatersrand. I estimate that if all the plants could 

 be run with as small a consumption of coal per ton of ore crushed 

 as the most economical plant uses, then the consumption of coal 

 would be reduced by about one-third of the present amount. While 

 it is quite out of the question, owing to the heterogeneous design of 



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