Two picked men line the mill in three shifts
"Two picked men line the mill in three shifts. The lower half is lined in one shift. Live steam is then turned in for 8 hr., and the mill is allowed to cool by draft for 8 hr. more. Next the mill is given a quarter-turn, and one-quarter more of its lining is put in, followed by the same heating and cooling. On the third day the lining is completed, and it is afterward steamed for 12 hr. loaded with pebbles and then cut into service.
"Where the cement is uncertain or slow setting, or where it is necessary to use it on minor repairs, soda ash is added to the to be put into use in 8 or 10 hr. The ribs are laid in mortar only, and no bolts are used in the lining. Experience has not developed any difficulties in holding the ribs or the lining by this method. No timbering is used in putting in the lining."
We find a general tendency to reline mills with discarded steel or iron from mine or mill such as old rails, rock-drill bits, stampmill liners, etc. The illustration, Fig. 34, shows how semi-steel battery liners are being utilized at the Plymouth Con. mill.
The plates were broken into pieces roughly 4 in. wide and 12 to 36 in. long. These pieces were set in cement with the pebbles, the liner pieces being set lengthwise of the mill and from 8 to 12 in. apart. They were, on the whole, about flush with the pebbles, though some points projected as much as % in. above the general pebble surface.
The lining as described, and as shown in the sketch, was installed in an 8-ft. by 22-in. Hardinge pebble mill and has every appearance of wearing well, although it has not been in use long enough to wear it out.
The Britannia lining, so-called because it is used at the Britannia mill, B. C., is made with rail-sections 5 in. long set on ends laid in neat cement. The grouting between the rails is made by embedding short pieces of drill steel in the cement. These pieces of rails present a rough surface and are said to give good service. Such a lining used on the Rand, South Africa, was found to add as much as 400 to 500 oz. amalgam to the output by the recovery of the amalgam collected between the pieces of rails.
The ends of cylindrical tube mills are lined with cast-iron plates, preferably chilled. Fig. 35 illustrates such a lining. Manganese steel has been used for end plates with decreased cost per ton of ore ground.
The preceding table will give an idea of the character and cost of liners in tube mills and while accurate as to figures at the time, some of the mills have since changed from silex to metal liners.
