Weekly journal-miner., 1918-03-20
1T n.Ik
sample of { pounds per ton, which


 sample of I pounds per ton, which drops to the sample safe.
 The smelter proper contains a roaster plant Ga new installation of four Wedge Roasters, each ZO feet 6 inches diameter with seven roast ing and one drying hearths. equipped with individual Cottrell dust precipi- tators). one blast furnace 70x48 feet at the tuyeres: and three barrel type converters 7H feet by 10 feet, de- signed for acid Innings, but now using basic innings. EC
 The blast furnace is charged alter nately from either side using Ana conda type charge cars tilted by air hoists. A charge consists of lO,Oo pounds of ore, limerock and conver- ter slag skulls with II per cent coke. The blast pressure is 26 ounces and the furnace smelts 300 tons of charge per day.
 Conveyor belts running under the fine ore bins and concentrates bins pick up the feed for the roaster plant. The belts carry the feed to the top of the roaster building where it is discharged by tripper into the storage bins, one above each of the four roasters. Each bin has capa> city of 125 tons. Two roasters arc now operating. the other two being still in course of construction. The ak cent copper and 26 per. cent sulphur; the calcines average 6 to per cent sulphur. Practically no oil IS used in roasting. the sulphur in the feed providing sufficient fuel.
 The dust-laden gases from the roasters are passed through Cottrell electric precipitation treaters located above the roasters. There IS no settling chamber, the gases going di- rectly to the treatcrs. There IS separate treater, divided into two sec tions, for each roaster; each section containing forty l2-inch diameter steel tubes, Is feet long. In each tube is suspended an insulated chain which serves as the discharge cleo trodc for the 75,0O current. The tube. which is grounded, forms the negative clectrode.
 The dust precipitation takes place as follows: The solid particles car ricd by the gases passing upwards through the tubes are electrified with a charge of like size as the chain, and arc drawn to the tube. In like man. ncr a small portion of the particles are charged by the tube and drawn to the chain A rapping device is provided to jar the particles loose from the tubes and chains. The feed particles drop in a mass to the hop pcrs beneath the tubes. From these hoppers the dust is conveyed to l0-inch helicoil conveyor to the end of the building, where it drops I-through chute into irebrick lined hopper at the bottom of the building. A similar hopper, of IS tons capacity. receives the calcines from each roaster These hoppcrs discharge into standard gauge calcine cars carrying the calcines to the reverbcra- tory furnace 250 feet distant.
 The reverberatory furnace CoxlOO feet treats 250 to 300 tons per day solid charge, of which $ per cent is hot calcines and the balance free ores used for fettling. The furnace also receives all the molten converter Slag. Nearly all the charge is dropped from overhead hoppers along the sides of the furnace. California crude oil, IA degrees Baume, is used for fuel Back of the furnace are two I 35O-H. F. Stirling water tube boilers utilizing the heat in the waste fur mace gases for the production Of steam. Enough steam is generated by waste heat to run the converter blowing engine with some slight ex- cess tor other purposes. Most of the power used generally throughout the plant at the mines, however, IS hydro-elcctric power purchased from. the Arizona Power Company.
 The blast furnace and rcverbera- tory mates each average 5 per cent copper Two 30-ton cranes serve the three 7Tl-foot by l0-foot converters. two of which are kept in the stack continuously producing about l,S0O.- 900 pounds copper per month. The convcrtcrS arc of the old acid lining type though now operated with basic lining. Their work is not very sat isfactory, however, and makes for high costs in labor and Innings. It is hoped that within the year they can be replaced with one or more larger and modern convcrtcrs.