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During the same years wherein the industry was concerned with development of larger and still larger types of primary rock crushers, anther member of the family was born: the Allis-Chalmers Co. entered this field in 1911, building two sets of 36-in. dia X 60-in. face single roll crushers for the Fairmount, Ill., flux limestone plant of the Casparis Stone Co. Taking the name of its proving ground, this machine was christened the “Fairmount crusher”. The machine quickly achieved a high degree of popularity, and although its field of application is relatively limited, quite a number of them were installed for primary crushing service. The line was expanded to include smaller sizes, as well as the big 60-X 84-in. machine.
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Development of concentration and cyanidation in the mining industry called for finer crushing tan was feasible in the gyratory or jaw crushers then available. This requirement was met for a number of years by the double smooth-face crushing rolls, originally known as “Cornish” rolls. As the mining industry during the period we ¿are discussing was a very active one, the development in this type of crusher had reached a fairly high stage before the end of the century, and some excellent heavy-duty rolls were available at
that time. That this machine was not used to any considerable extent in the commercial crushing plants of that period was due simply to the fact that there was no demand for the smaller sizes of crushed stone, at least not any more than could be taken care of by the crushing methods then in such plants.
This brings us to the rather significant fact that, while all of the interesting and rather remarkable development we have outlined was going on, very little, if anything, was being done to develop special crushers for secondary and a fine-reduction work, other than the work on crushing rolls just described.
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