272 
The N.Z. Journal of Science and Technology. [Sept. 
ELECTRICITY APPLIED TO GOLD-MINING. 
. 
By W. P. Gauvain, of the Waihi Gold-mining Company (Limited). 
The application of electricity to the gold-mining industry has been the 
means of effecting large savings in the power department, and has resulted 
in the possibility of the treatment of low-grade ores which formerly were 
not capable of being treated at a profit. The results are more noticeable 
in large mining districts, such as those of South Africa, where central power 
companies have been formed and very large stations erected for the purpose 
of supplying power to the mines. 
In a short article it is not possible to deal with this subject in great 
detail, because in gold-mining the uses to which electricity can be put are 
numerous ; it is only proposed to review the subject as far as space will 
permit, and to give some facts which may be of interest. 
Gold-mining may be rated as one of the unstable industries—an industry 
full of possibilities, of anticipations, and, alas ! of failures. In the course of 
the development of a gold-mine it is necessary to move cautiously, and it is 
sound practice to delay heavy capital expenditure on a power plant when 
a plant that is cheaper but not so economical in running-costs will suffice 
until sufficient work has been done to prove the property. Even when the 
producing stage is reached the amount of ore reserves does not always 
warrant large capital expenditure, and consequently the power plants are 
often crude and wasteful. If development proceeds satisfactorily and opens 
good payable blocks of ore, placing the mine on a sound financial basis, 
then it is sound policy to install a modern plant and scrap the original 
plant. Allowances for depreciation and sinking fund must of necessity be 
high on a gold-mining plant, and far greater than are required in a stable 
industry. 
So far as the mine itself is concerned, there are, apart from the expense, 
considerable engineering difficulties to be encountered in the application of 
electricity to the various problems : in the mill the problem is usually much 
simpler. 
When hydro-electric power is available for a reasonable capital expendi¬ 
ture a distinct saving may be effected ; if, however, steam is the motive 
power, and the amount of power required is not large, then electricity 
is probably only economical for operating what may be termed the 
auxiliaries of the mine and mill. 
When steam turbines came into extensive use some years ago a number 
of companies decided to electrify their plants, not appreciating the fact that 
the steam turbine in the small sizes could not compete in economy with 
the high-class compound mill-engines driving direct. The result was that 
the electric drive got rather a bad name, due not to the use of electricity 
but to the unfortunate misapplication of it. 
The. Mine. 
To deal first with the use of electricity at the mine. Power is required 
for the following purposes : Pumping, winding, air-compressing, ventila¬ 
tion, underground haulage, &c. 
Pumping .- — The history of the application of mechanical power for the 
purpose of raising water is an intensely interesting one, and is closely allied 
