INJURY TO VEGETATION AND ANIMAL LIFE BY 

 SMELTER WASTES. 



INTRODUCTION. 



PROCESS OF EXTRACTING METALS FROM ORES. 



Before considering the injurious effects which wastes from plants 

 smelting sulphid copper ores may have on vegetation and animal life, 

 a brief account will be given of the process generally used to extract 

 the metal from the ores, ^or this purpose an outline of the process 

 followed at Anaconda, Mont., will be given, which, though differing 

 in some details from the process used at other plants, is based on the 

 same general principles and produces similar waste products. 



The ores when they arrive at the plant are graded as first and second 

 class, the former being sent to the bins of the blast furnaces and 

 the latter to the concentrator bins. The second-class ores are next 

 sampled, crushed, and passed over jigs, by Avhich process a product 

 richer in copper, known as the " concentrates," is obtained. 



The reject from the jigs is crushed again and passed over jigs fitted 

 w^ith finer screens, " concentrates " being again obtained. After ex- 

 tracting all that can be taken out by the jigs, the ore is again crushed 

 and passed over the Wilfley tables, thus giving rise to the " table con- 

 centrates." The concentrates are sent to a bin at the foot of the 

 concentrator. There remain in the water used for concentration some 

 fine particles of valuable material, and this is allowed to flow into 

 ponds outside the plant, where the fine particles settle out in the form 

 of " slimes " and the water is finally drawn off. The slimes are 

 briquetted and blast-smelted. The waste products from the con- 

 centration are known as " tailings." These tailings, consisting princi- 

 pally of silica, iron, etc., with small quantities of copper and arsenic, 

 in case the latter is present, are discharged on the dump heap. 



The concentrates are dumped into roasting furnaces, where large 

 quantities of sulphur and arsenic are driven off, the former as 

 sulphur dioxid and trioxid and the latter in volatile form. The 

 residue, now known as " calcine," is transferred to reverberatory 

 furnaces. This process yields (1) a slag consisting principally of 

 silicates of iron and calcium with very small quantities of copper; 

 (2) a product richer in copper known as " matte;" and (3) volatile 



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