- Wider use of the lower-grade fuels of the west, particularly with the aid of briquetting.
Progress in above methods. Methods of mining and preparation of coal have been improved. Campbell and Parker state:9
A much greater proportion of the product hoisted is now being sent to market in merchantable condition. Part of this is due to better and more systematic methods of handling, and part to the saving of small sizes which formerly went to the culm banks. The higher prices of coal and the development of methods for using these small sizes have also made it possible, through washing processes, to rework the small coal formerly thrown on the culm banks, and these are now furnishing several millions of tons of marketable coal annually.
In general there is increase in the percentage of recovery of coal. Whereas in the past the loss in mining was said by Campbell and Parker10 to average 50 per cent, now an extraction of 70 to 90 per cent may be looked for.
Quoting from Smith and Lesher:11
Observation of the advances made in mining methods in the last decade or two affords slight warrant for belief in any charge of wasteful operation. As consumers of coal we might do well to imitate the economy now enforced by the producers in their engineering practice. In the northern anthracite field machine mining in extracting coal from 22- and 24-inch beds, and throughout the anthracite region the average recovery of coal in mining is 65 per cent., as against 40 per cent. only twenty years ago. Nor are the bituminous operators any less progressive in their conservation of the coal they mine.
In anthracite mining, powdered coal or "silt" has accumulated in stockpiles and in stream channels to many tens of millions of tons. It is estimated that this constitutes nearly 6 per cent of