ELECTRIC SHOVELS

Evening Star, Issue 19775, 27 January 1928, Page 2

ELECTRIC SHOVELS

USE IN NITRATE MINING CHILEAN DEVELOPMENT For the first time in the history of nitrate production in Chile poweroperated shovels are to be used on a commercial scale for stripping the overburden and for mining the nitratebearing rock. This is boing done by the Anglo-Chilcan Consolidated Nitrate Corporation, which is now building a plant at the mines at Coy a Norte, on the Chilean Pampa, about 5,000 ft above sea level and forty miles inland.

One of the first steps is the partial electrification of the railway running from the seaport, Tocopilla, to the mine. At present the heavy grade section of the railway only will be electrified. Power will bo obtained from the generating plant situated on the desert, and will bo transmitted by a three-phase sixty-cycle transmission line at 33,000 V. There will bo two automatic railway sub-stations, each containing two 750 k.w. synchronous motor generators and automatic switchboard control for converting the 33,000 V power to 1,500 V d.c. ' Trains will bo handled initially with sixty-tou locomotives, built by the G.B.C. of America, These will be arranged for multiple-unit operation, and later, as traffic increases, trains will be double beaded. The locomotives will bo provided with regenerative braking for controlling tho speed of descending trains without using the air brakes. The locomotives will derive power from an overhead copper trolley wire supported by standard catenary construction. The two sub-stations will bo fully automatic and directly under the control of the Train dispatcher by means of the company's supervisory control system.

As the ore is mined it will be handled by six full revolving shovels. Each shovel will have a dipper capacity of three cubic yards, and will be driven bv a motor generator consisting of a 190 h.p. motor and three generators, having a total output of 150 k.w. to tho three-man motors on each shovel. Alternating current supplied to the driving motor of the motor generators will be changed by them to direct current to operate the shovel motors. The oro will be loaded by tho shovels into trains pulled by electric locomotives. There will he thirteen thirtyton combination trolley and storage battery type locomotives for this purpose, one of which is to be equipped with a side-arm trolley for use at a later date, and all of which wall have both pantograph and third rail shoes. These locomotives will be used on 500 V trolley and 190 V battery service, 42in gauge track. The majority of the locomotives will he used in hauling the ore from the workings to the mill, where it is treated. Others will haul tho waste to the dumping loop.