The Prisbee-liNeop Wet-crushing 3-B11 is constructed upon the same principle as the dry crushing. It has double screens at each end—coarse ones on the inner side, which take the wear of the coarse rock, and fine screens beyond (which may be of any mesh), to finish ; nothing can leave the mill until fine enough to pass the outer screen, the coarse stuff passing the inner screen going back under the rolls. The annular die, or ring, on which the rock is crushed, is of rolled steel, 24 in. inside diameter, 3 in, thick, with 6 in. face. The rollers are in. in diameter by 6 in. face, with a tire of forged steel. The capacity of this mill is claimed to be 3 tons per hour of hard quartz to 40-mesh, up to twice that amount for soft material and coarse pulp.
The Bryan is a modifi cation of the well-known Chile mill, arranged for the continu ous wet-crushing of either gold or silver ores, eliminating, it is claimed, all that is objectionable in the Chile mill. It consists of an annular mortar, contain ing fixed segmental steel dies arranged in the path of its three crushing rollers. The axles of the rollers are jonrnaled in a central revolving table attached to and driven by the belt pulley directly. The 4-ft. mill has a similar arrangement of dies, but smaller rollers, whose weight is increased as desired by the load carried in the pulley drum, which rests on their periphery, thus adding to their weight, and driving them by friction. The pulverized ore is discharged through screens in the side of the annular mortar. This mill has a peculiar advantage, inasmuch as its weighting, upon which its crushing capacity, like other mills, depends, can be done at the mine by placing either shoes, dies, or even stones in the pulley, virtually a pan which bears upon the rollers. Thus heavy transportation is avoided in comparatively inac cessible districts, Jordan's Reducer, sometimes used in crushing gold ores for amalgamation in connection with Jordan's amalgamator (see GOLD MILLS), is a revolving pan, set at an angle, and carrying three massive balls of white iron, which work in a suitably shaped bed, also of white iron, round the greatest circumference of the pan. The ore and water are fed automatically into the bed of the pan, and by the rotary motion of the latter, are conveyed under the rapidly revolving balls, whereby the comminution of the ore is effected. The inner half of the floor of the pan rises as a shallow dome surrounding the central shafts, and is fitted with movable frames carrying wire screens of any required mesh. The feeds of ore and water, and the inclination of the screens, are so adjusted that, as the ore is reduced to a suffieient degree of fineness, it is washed over the screens and passed away into a launder for conveyance to the amalga mator. It is claimed that this machine has reduced 20 tons of ore in 24 hours, so as to pass
an 80-mesh screen.
The lliortinryton Mill (Fig. 1 n consists of a spindle, G, carrying a circular frame, B, at its top, from which are suspended four steel rollers, E, which are rotated against a ring, forming the base of a mortar or pan. The ore and water being fed into the mill at the hopper, A, the rotating rollers and scrapers throw the ore against the ring die, where it is crushed to any desired fineness by the centrifugal force of the rollers as they pass over it: The water and pulverized ore are thrown against and through the screens when flue enough. The rollers are suspended, leaving a space of 1 in. between them and the bottom of the mill, thus allowing them to pass freely over the quicksilver and amalgam, without grinding it or throwing it from the mill, while it agitates it sufficiently to insure amalgamation. This mill is used for crushing and amalgamating gold ores, with excellent results. It is also employed for fine-crushing in dressing works, but its use for that purpose is not to be rec ommended, as it slimes the ore excessively. The manufacturers furnish the following data : The Ciriffen NM consists of a shallow cast-iron ring or mortar, which is surmounted by a tall sheet-iron cone, with an opening at the apex. through which a vertical shaft works. This shaft, which is driven by a horizontal pulley. has a universal-joint at its upperend—i.e., just below the driving pulley : while at its lower end is rigidly fixed a heavy cast-iron roller. The shaft and roller being free to move by means of the universal-joint, the roller is thrown against the side of the mortar or crushing ring by centrifugal force, and the rock or ore, which is fed in through an opening in the side of the case, is thus pulverized. The crushing roll swings several inches above the bottom of the mortar, but upon its lower side there is a plow which stirs up the ore in the bottom, and throws it against the ring die, where it may be acted upon by the roller, The crushed ore is discharged through screens in the case just above the ring die, fan attached to the shaft above the roll causes the air to draw strongly into the mill, and prevents the escape of dust. This mill is extensively used for fine grinding, such as pulverizing phosphate rock, but is not adapted to work where the formation of an undue proportion of slimes is to be avoided. it is stated that it will grind 4 tons of South Carolina phosphate rock per hour, so that 75 per cent. will pass a 75-mesh screen.