Halifax Paper - Improvements in Ore-Crushing Machinery

In connection with perfecting a system of pneumatic concentration I had in view the improvement of machines for crushing and pulverizing ores. A study of the whole subject convinced me that the principle upon which the construction of the Blake crusher, and that of rolls, is based, possessed the mechanical elements which, if perfected and simplified, would make these machines the successful rivals of every other device. It is well-known that until very recently the stamp-battery held undisputed possession of the field; and mill-men and mill-builders almost universally believed that stamps would not be superseded by any other machine for fine crushing. The first step to drive stamps from the field was the introduction of rollers in the Bertrand and the Mt. Cory mills. In both of these mills the great superiority and economy of a system of crushing with rollers instead of stamps has been fully demonstrated. While perfecting the rollers, I had the fact confronting me that they had frequently been tried without success. In fact, the universal opinion prevailed that rollers could be used only for coarse, and not for fine crushing. The secret of the difficulty I discovered to lie in the imperfect and weak character of the rolls heretofore used, due to a misconception of the requirements for a machine for such work, and a failure to appreciate the advantages of continuous, rolling, crshing- surfaces, operating on the toggle-lever principle, which gives the greatest crushing pressure with the least power. expended, and the minimum of wear.