11. Elimination of the wasting of slack or fine coal, through more careful methods of mining, through limitations on the excessive use of powder and larger use of wedges, through the abolition of laws for the payment of miners on a run-of-mine basis, and in the case of anthracite through recovery of the "silt" or dust caused by mining and sorting. It has been argued that the excessive use of powder ("shooting from the solid") means loss of coal, owing to the fact that it shatters the coal and makes a relatively large amount of slack, besides being accompanied by increased danger from fire and explosion and from weakening of the roof. Although the excessive use of powder makes a large amount of slack, it does not necessarily result in waste, for this fine coal is carefully saved and for certain purposes is as valuable as the lump coal. So far as the procedure endangers life, it is of course objectionable.
12. Better use of fine coal. It has been recommended that infirm and finely broken coal be washed and compressed, thus avoiding the wasting of slack coal, which was formerly thrown away or burned. However, in recent years there has been comparatively little waste of this kind, for slack coal in general finds nearly as ready a market as lump coal and the use of slack is increasing. There has been much discussion also of the possibilities of using the coal waste on the ground to make power for electric transmission.
13. More careful attention to sorting and sizing of all grades of coal coming from the mine and to preparation of coals for special uses. On the other hand, some operators say that the ends of conservation will be best met by limiting the sorting and sizing now practiced. The large number of sizes now put on the market greatly increases the cost of production.
14. 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:[50]
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 Parker[51] to average 50 per cent, now an extraction of 70 to 90 per cent may be looked for.
Quoting from Smith and Lesher:[52]
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 the coal mined. Significant progress has been made recently in the recovery and use of this silt as powdered fuel for local power purposes.