Arizona republican., 1909-03-26
MESA MAYS DEVICE
 FOR MILLING ORE
An Invention Said to Be Working Satisfactorily at Bull Dog Mine and
 Promising Much.

Mesa, but now being tried at actual
 work for the first time, promises, if the present success attending its op- leration continues, to revOlutioniZe the methods of milling ores in the preci- ous metal mining industries. While the machine has been covered by a sufficient number of patents for the past two years to completely protect the inventor from competition with improved similar devices, yet there may be be several changes made in the minor details of the machine dur ing it's present trial, before it is
 placed in the hands of a manufac
 turer. The model machine, which was built by Mir. Johnson himself for the
 purpose of experimentation, and which is being used by the Shattuck- Nim-
 mo company in its work at the Bull
 Dog mine near Goldfield, Ariz., is
 giving satisfaction and Is much
 cheaper and more effectual than a
 stamp mill of the same capacity.
 The new machine differs radically | in principle from the prevailing stamp mills. the grinding forces be- ! ing the centrifugal force imparted to
 the ore by the revolution of the cyl | finder in which it is contained and
 the action of rapidly revolving smaller drum placed inside the cy- finder into which the ore is fed.
 ! The new machine may be briefly described as follows: A small circu- lar drum filled with concrete or some solid material to prevent its being crushed by the impact of the heavy
 ore is placed on horizontal bearing. { The outside surface of this drum is covered with lengths of railroad iron. This drum is to be revolved at a speed of from one to three thousand revolutions per minute. Outside this
 drum, and bearing upon its upper circumference, is a large drum, the inside of which was, according to
 original specifications, covered with
 railroad iron. However, practice has
 shown that the armoring of the out side drum is unnecessary and in the
 future the grinding surface of the outer drum will be left smooth.
 Motion is imparted to the outer
 drum by the friction of the smaller drum within. which is geared directly
 10 the engine, the outer drum thus
 travelling at considerably slower ate than the one within. The ore is
  Tate of revolution of the entire ma ..inc is sufficiently great to throw
 t-e material between the drums at their point of contact. Besides being thrown between the drums the major portion of the rock is finely ground
 before coming in contact with the rollers by impinging upon other rock in the revolving receptacle. At
 ia na mesh screen through which the ground material will pass. The pas sage is facilitated and the mechanism cooled at the same time by the pas sing through the outer cylinder of current of water. That portion or the gold. or concentrate, which does not pass through the screen will, be- cause it is of greater weight than the rougher material, be found in the coating of the outer drum and can De
 secured by the removal of the outer cylinder This finely ground matter also furnishes a grinding surface ar ter the machine has been in operation for about one minute by forming deposit on the metal inside surfaces and thus preserving them from any wear or friction.
 IL Is estimated that the new Coh- trivance, equalling in capacity a lOO- stamp mill can be operated by a SO- horse power gasoline engine, since after the full speed is once attained the inertia of the heavy drums tends to continue the revolution and very little power is required to maintain the speed.
 In development work the machine may prove of especial value since they are to be made of only one size, a large one having been found to be no more expensive to manufacture than one of smaller capacity. By running a shorter or longer time the new invention can be economically adapted to the needs of any property which requires from ten to one hun dred stamps.
 A small plant can thus increase its milling capacity without any increase of expenditure of money other than that required to keep the machinery in motion. The assembling of the contrivance is complete and it can be separated into a number of small parts. thus making its freighting comparatively easy. A mechanism is provided which automatically regu- | lates the feed and while in operation the machine requires very little at tention.
 It is expected that after a thorough l test at the Bull Dog that the inven-
 tion will be placed in the hands of a | manufacturer, since the saving it will | effect and the convenience it will af |