SLIME-WASIIING MACHINES.—The FrueVanner (Fig. 6) is an endless inclined rubber belt, supported by rollers so as to form a plane inclined rubber surface, 4 ft. wide, 12 ft. long, and bounded on the sides by rubber flanges. The belt travels up the incline and around a lower drum, which dips into a water tank where the mineral is collected. In addition to the travel of the belt, the latter receives a steady shaking or settling motion from a crank shaft along one side, the shake being at right angles to inclination and travel of belt. The best motion is found to be from 180 to 200 strokes per minute, with about 1 in. throw. The ore is fed on in a stream of water about 3 ft. from the head of the belt, and flows slowly down the incline, subjected to the steady shaking motion, which deposits the mineral on the belt. At the head of the belt is a row of water jets. The slow upward travel of the belt, varying from 2 ft. to 12 ft. per minute, brings up the deposited mineral, and the water jets wash back the lighter sand, letting only the heavy mineral pass and deposit in the water tank below. The inclination of the upper surface of the belt varies from in. to 1- in. in 1 ft. The capacity of the machine is from 5 to 12 tons, according to character of the ore treated, but practice has demonstrated that 6 tons of 40-mesh stuff per 24 hours is as much as it is advisable to treat. A depth of a in. toy in. of sand and water is constantly kept on the belt.. The average amount of water required is from 1 to 11 gallons per minute at the head, and from 1+ to 3 gallons per minute with the pulp.
The Morse-Frite 'Tanner is a modification of the old type of Frue vanner, the essential difference being in the rubber belt, the surface of the latter being roughened in the new ma chine, with fine transverse corrugations. The corrugated belt being heavier than the plain belt, extra supporting rollers on the shaking frame are necessary. The surface of the corru gated belt is given a slightly greater inclination, a fall of from 3 in. to 5 in. in 12 ft. being
commonly used, instead of 3 in. to 4 in., as in the case of the plain belt. The water distribu tor consists of two rows of waterjets, U. in. apart, the back ones alternating with the front ones, the distance between the back and front rows being 2.i in. The distributor is placed from 1 in. to 2 in. higher up towards the head of the belt than in the old machines, and is also raised somewhat higher above the belt, so as to give a drop of about 1,4 in. from the spouts to the belt surface. More water is required than with the old belts. The revolutions of the crank shaft vary from 194 to 210 per minute, and the forward motion of the belt from 23 ft. to 33 ft. per minute, according to the character of the ore treated. The capacity of this machine is considerably greater than that of the ordinary Frne yammer, and it. can be used for the treatment of coarser slimes. Indeed, these belts have given excellent results at some places on material that is usually washed on meal jigs.
The Embrey Concentrator is very similar to the Erne vanner in construction and opera tion, but the belt is given an end shake instead of a side shake.
The Triumph Table is also a belt machine, resembling the Frue vanner and Embrey con centrator, and, like the latter, the belt has an end shake.
The Lnrig Fanner is an end-shake belt machine which is very similar to the Frue run ner in construction, and works upon the same principle.
The Gamier Concentrator is a belt machine, in which the belt is given a peculiar palming motion. The belt frame is supported at the rear end on a sliding bearing, and at the front by a vertical eccentric shaft. By means of the eccentric a circular movement is imparted to the forward part of the belt, which becomes approximately a simple back and forth throw at the other end. The belt has a continuous forward movement, as in other machines of this class, and is fed and adjusted in similar manner.