boxes e and ƒ are shown, each tank being divided into two rows of compartments. The box e is for the weaker gold solution. The pump g is placed near the sump tanks for the purpose of forcing the solutions to the various vats, as required. The leaching vats are under a roof 106 feet 9 inches long by 23 feet wide. The remainder of the lixiviating apparatus is under a roof 53 feet 6 inches by 11 feet. The boiler and the engine i are separated from each other and the remainder of the machinery by partitions. The milling machinery is contained in a ground space

44 feet 3 inches long and 26 feet wide. The crusher is represented by j, the ore drier by k, the furnace of the drier by 7. The elevator to the screen is shown at m, the crushing rolls by o and p. When the ore is to be charged in a vat, it is run on to the platform scales q in a car and weighed; from the scales the car runs over the vats a on track r and is dumped into the proper vat. the cars into which the tailings

Other tracks s and are for from the vats are shoveled.

82. Elevation.-In Fig. 9 is shown an elevation of the 25-ton plant whose plan has just been described. The section is taken back of the line shafting x, in order to show the principal machines. The ore is first passed through the crusher into the ore bin a' below. The ore runs down the ore-bin floor and is drawn off into a chute that feeds the ore drier k. From the drier at 7, the ore falls into a screw line n and is conveyed to the boot of the elevator m.

The elevator

k

h

m

FIG. 11

raises the ore to a screen shown in Fig. 10, at p', over which it passes by gravity. The coarse ore passes down the chute w to the rollsp and then down to the elevator, by which it is raised to the screen p' again. The fine ore from the screen passes to a bin, from which it is drawn as needed. By an examination of Fig. 9, it will be observed that advantage is taken of gravity, wherever it is thought desirable, for handling material and disposing of solutions. The lixiviating tanks are above the gold-solution tanks, the latter above the

The

zinc boxes, and they, in turn, above the sump tanks. charging track r has upon it a tram car u above one of the leaching vats.

83. Cross-Section.-The cross-section shown in Fig. 10 was taken through the plan on the line CD. It shows the rolls, elevator m, screen p', chute w to the rolls and chute b' to the elevator boot c'. It also shows the charging car u under the ore-bin chute.

84. The cross-section shown in Fig. 11 was taken through the line AB, Fig. 8. It shows in detail the boiler h, screw conveyer, elevator m, drier k, furnace front 7, crusher j, and ore bin a', with its chute leading to the drier.

It will be noticed that the mill is built on a side hill, at an elevation that permits the ore cars to run direct to the crusher. In some cases the ore is run above the crusher, so that it is' unnecessary to handle it, as in this case.

177.67 17

248.15 18

1,503.62

The number of gallons in a 146.83 16 6 1,600.00 receptacle 1 foot in diameter 1,697.45 and 1 foot high is .7854 × 7.48 211.44 17 6 1,798.76 = 5.87 gallons. 7.48 is found by 1,903.02 dividing the number of cubic 287.80 18 6 2,010.21 inches in a cubic foot by 231, the number of cubic inches in 1 gallon; thus, 1,728 ÷ 231 = 7.48, or the number of gallons

330.38 19

2,120.34 375.90 19 6 2,233.29

33445

6

118.93 16

424.36 20

530.08 21

10

10

11

11

776.77 23

2,349.41

475.75 20 6 2,468.35 in 1 cubic foot. The weight of

2,590.22 1 gallon of water is 8 pounds;

2.000 lb.
8.33 lb.

= 240 gallons

848.18 23 6 3,243.65

917.73 24

992.62 24 6 3,525.59

3,670.95

85. Fig. 12 is a section through the plan at EF and shows the leaching tank a, with the loading track and

unloading tracks s and t; also the gold-solution tank d and the sump tank b. It will be noted that the leaching vats and the gold-solution tanks are placed on a space leveled off on the side of the hill, in order to take advantage of gravity in drainage operations. The car u runs on track r, which is laid upon stringers over the tanks. The stringers are placed upon bents, which are between the tanks, as shown by dotted lines.

TABLE IV

CAPACITY OF LEACHING TANKS IN TONS OF DRY ORE

Diam

eter

Height of Vat

in Feet 3 ft. 3 ft. 6 in. 4 ft. 4 ft. 6 in. 5 ft. 5 ft. 6 in. 6 ft.

50

40 115 140.0 165 190.0 215.0 240.0 265 180 220.0 260 300.0 340.0 380.0

420

86. Calculating the Capacity of Tanks in Gallons and Tons.-The capacity of a cylindrical tank may be calculated as follows: Square the diameter in feet, multiply this product by the depth in feet, and this product by 5.87, which will give the contents of the tank in gallons.

EXAMPLE. What number of gallons will a tank 12 feet in diameter and 10 feet high contain?