I20 THE RAND GOLD MINING INDUSTRY. 



worker owes to his fellows of contributing to the common 

 stock* his quota of information in return for the far greater 

 amount which he has received from others has hitherto weighed 

 with a sufficient number of those concerned to very fully justify 

 the Society's activities for the benefit of the gold-mining industry. 



The existence on the Rand of a number of groups under 

 different controls has also been a factor in progress, since the 

 friendly competition for better results, and the diversity of 

 opinion and methods employed to attain this end, have prevented 

 the paralysing effect upon varied advance, which extreme con- 

 centration of technical control might cause. At the same time 

 the group system, embracing several mines in each group, allows 

 the cost of trials to fall lightly upon individual mines, as well as 

 affords a ready means of ensuring the prompt adoption of any 

 improvement on all the mines of the group. The group system 

 and organisation, which is more highly developed on the Rand 

 than on most mining fields, facilitates the provision of capital 

 for opening up new mines or extending the scale of operations on 

 producing mines, as well as renders available for each mine a 

 specialised technical staff', whose cost would be an unwarrantable 

 expense for any individual mining company. 



The scale of operations on the Rand may perhaps be best 

 realised by a few concrete illustrations. For instance, the addi- 

 tional refining charge of one penny per ounce of bullion recently 

 imposed on the Rand output by the London refiners amounts to 

 about £40,000 per annum. The previous costs of transport, 

 insurance and refining the Rand bullion production of about 

 one ton daily amounted to about i per cent, of its value, or, say, 

 £350,000 per annum. A penny (0.02 dwt.) per ton of ore in- 

 creased or decreased working cost, or variation in gold extrac- 

 tion, is equivalent to £100,000 on the tonnage of ore milled 

 yearly on the Rand. In a plant such as the Knights Deep, 

 Limited, crushing 3,500 tons of ore daily, twelve times this 

 weight in all is elevated and transported as pulp, and the gold 

 precipitated daily from i-/4 million gallons of gold-bearing solu- 

 tion. A slime charge of four hundred tons of solids with suffi- 

 cient solution to form a fluid pump is pumped within an hour 

 to make room for a succeeding charge, and in general, cheap 

 and speedy transport of solids, fluids and pulp constitutes one of 

 the main factors in the efficient and satisfactory operation of a 

 modern reduction plant. 



A feature of the development of ore treatment, which has 

 not been generally realised, is the great decrease in the capital 

 cost of reduction plant. Plants erected in 1903 cost about £215 

 per ton of ore treated per working day, which was much less 

 than previously ; but the increased scale of operations, larger 

 size of all units — stamps, tube-mills, vats, pumps, and piping — 

 and simplicity of design have reduced the cost in recent years 



* Dr. Jas. Douglas: "Secrecy in the Arts," in Proc. of Aiitcr. Inst, of 

 Minima Eiig.. 38 (1907), 455-. 



