For several years past Colorado metallurgists have been attempting to solve the metallurgical puzzle presented by the low-grade ores of Cripple Creek. Millions of tons of ore running from $3 to $10 per ton have lain on the great dumps for years, while other millions were exposed in hundreds of miles of underground workings.
The Portland company alone had enough low-grade ore in its forty odd miles of workings to materially increase the Cripple Creek gold production provided a method of profitable treatment could be devised.
Shipping the ore to the Colorado Springs reduction plant of the company cost $1 per ton, roasting the ore cost $.76 per ton, and the other milling expenses ate up the small margin of profit.
Thus, for some years previous to 1907, the issues were clearly presented, first, to eliminate roasting the ores if possible, and, second, to eliminate freight charges by building mills at the mines.
It will, of course, be understood that until a way of eliminating the roasting of the tellurium ores was discovered, it would be useless to erect mills at the Cripple Creek mines where roasting costs even more than at Colorado Springs.
During the two years in which the Stratton Independence and Golden Cycle metallurgists have been evolving their plants, those of the Portland company have also been most active.
It is now common knowledge that the widely advertised Moore-Clancy process was given an extended trial at the experimental mill of the company but was evidently found unsuitable. The great amount of experimental work, however, did result in the evolution of what is known as the "Portland process," whose details are as yet unavailable.
It has been thoroughly tried out at the company's Cripple Creek 10-stamp experimental plant, however, with such success that a large mill is soon to be built close to the mines.
The annual report of the company recently issued says that from many tests the company is convinced that the problem of treating the low-grade dump ores has been solved.
The directors have decided to back up their judgment by the expenditure of at least $100,000 for a 300-ton mill, erected near the mine on Battle Mountain, to treat the great company dumps. These contain enough ore to run the mill for many years at an estimated net profit of from $1 to $2.50 per ton.
At the Portland mill, another Chilean mill is being installed driven by a motor, and the transformer station is being enlarged.