CONVEYING AND GRINDING CLAY.
Shale clays are commonly mined by blasting, and the plastic clays by digging or " throwing " the face of the bank, which gives a good mixture, and after a sufficient quantity of the material is secured, it is automatically let down an inclined plane in dump cars, attached to a wire cable which winds around a grooved wheel. By this arrangement, the car laden with clay, as it passes down the incline, pulls the empty car up to be refilled at the bank. When the dump car with its load of clay reaches the bottom of the incline, the material is auto matically discharged from the car into a 9 foot dry pan, in which the material is thoroughly reduced and pulverized.
Fig. 65 illustrates the dry-pan made by the Frey-Sheckler Co. This pan is built in three sizes, viz.: 7, 8 and 9 foot diameter. For strength and solidity it has no equal. It is designed for grinding fire clays, shale, quartz, cement, lime, flint, sand, spar, 'ochre, calcine, grog, plaster rock, plaster paris, bones, coal, or any hard substances.
This pan has from io to 20 per cent. greater screening capacity than any other pan of same size ; it is also balanced so that a great speed can be obtained. It will readily be seen that additional centrifugal power is obtained to throw the material outward over the screening plates, and the screens are of such increased area that the reduction is increased in the same ratio.
These pans are built entirely of iron and steel. The vertical shaft has a hole through the center from top to bottom, through which the oil passes to lubricate the bottom bearing with unfail ing regularity. The special arrangement of the bottom bear ing, having an oil reservoir under and around it, revolving on the hardest chilled plates, with distributing oil grooves, saves friction, heating and wear.
Every joint is planed square, every hole is drilled, and each bolt is fitted with lock-nuts. Each roller has its own shaft, the ends of which are provided with blocks that move in guides in the frames, also in guides in the shrouds encircling the main shaft. The rollers move always square on the face of the bed,
whereas if both rollers are on one shaft, if one is lifted, the other follows to some extent, so that only the corners touch the bed. One side of each vertical guide at the end of the roller is re movable, which allows the shaft and roller to be taken out with out delay. The ends of the roller shafts are supported by heavy coil springs, so that they are close to but do not touch the floor plates when the pans are empty.
The space between the rollers and floor plates can be nicely adjusted to suit each material by means of adjusting screws and rubber springs in the frames and shroud, which encircle the vertical shaft. The rollers have deep, hard chilled tires, which can be readily removed from centers when the substitution of new tires is necessary. The floor plates and screen plates are both chilled.
The scrapers are hung on universal joints, so that they can be adjusted in any direction; they are also provided with inter changeable chilled face plates, which render the wear of the scrapers four times as long as that of the ordinary scraper.
These dry-pans are driven with a friction clutch pulley 48 inches diameter, 12 inch face; speed, 150 revolutions per minute.
Approximate weight of 7-foot pan, 21,000 pounds. Approximate weight of 8-foot pan, 26,000 pounds. Approximate weight of 9-foot pan, 30,00o pounds. This machine is fully protected by patents.
Fig. 66 illustrates the No. 12 Improved Tailings Crusher made by the Frey-Sheckler Co.
This machine is adapted for reducing the tailings of shale, fire-clays, or any refractory or silica clays. It is also adapted for crushing soft or alluvial clays.
The rolls, zo inches in diameter, 26 inches long, are made of charcoal chilled iron, with steel shafts through them. The rolls are ground to a smooth bearing surface and are run at differential speed.