The El Oro lining developed

The El Oro lining developed at the plants of the El Oro Mining and Railway Co., Mexico, consists of plates, usually of hard iron, having ribs lengthwise of the shell of such form as will cause thus throwing the wear on the pebbles. These liners in sections may be put in the mill without bolts and worn until the iron is so thin that it falls out. In 12 hr. a new lining can be put in place. In operation, when a pebble becomes fractured or worn and escapes from the corrugation, another will take its place and the effect is to maintain what is practically a flint lining to the mill.

The rough surface presented entirely avoids the tendency of the whole charge to skid on the lining. Fig. 22 shows the inside of a tube mill with El Oro lining; while Fig. 23 shows the dimension of the lining at the Lluvia de Oro mill.

The El Oro lining illustrated in Figs. 24 to 27 is made by the Stearns Roger Mfg. Co. and is held in place with keys without being bolted to the shell of the mill. The method of placing this liner is here described:

The liners are held in place by means of taper metal keys D. A number of different widths of keys are provided so that the one fitting the space may be selected. These keys must be driven home tight so that they will not shake loose after the mill goes into operation.

Commence lining at each end of the mill and work toward the center. Place the flange side of the lining next to the head so that the teeth face toward the center of the mill. This will bring two sections near the center with the teeth facing each other.

Each ring of lining is intended to occupy a space of 6 in. in the length of the mill. To allow for inequalities and roughness in the casting some clearance is allowed. This clearance should be distributed throughout the length of the mill so that when you come to the closing section the space will be correct. It will be convenient to divide the shell lengthwise into 6-in. spaces with a chalk and tape line.

The closing joint can be made near the center of the mill where the sections come with the teeth facing: See detail of " closing joint." The space CC admits short keys A and B which can be driven to place by means of a bar and sledge. After the keys A and B are driven, the space C is filled by filing one of the short key blocks to fit the place and driving it between the teeth. This will prevent the keys from backing out.

When starting the mill with the El Oro lining, a liberal load of assorted pebbles not larger than 3 in. should be used. The mill should be revolved for about 2 hr. with water and pebbles, using no ore so that the pebbles will have a chance to be imbedded in the meshes of the lining. The regular service is then started.

The Globe lining, Fig. 28, is an adoption of the El Oro idea with the ribs transversal instead of longitudinal and is used in several mills in Ontario, Canada.

The Osborne, liner Fig. 29, used extensively on the Rand, South Africa, is another modification of the El Oro lining.

"It consists essentially of two bars placed in such a manner that with the aid of cement concrete they lock themselves in the interior of the tube mill. The horizontal bar is about 2 in. long and about % in. wide. The other bar, at right angles to the first, is practically of the same section as a grizzly bar, and is 4 in. long and % in. in thickness at the end projecting into the mill, and \y% in. in thickness at the base. Concrete is laid on the bottom and part of the sides of the tube mill, with the bars placed in position, as shown in the sketch."