8 INJURY BY SMELTER WASTES. 



arsenic and sulphur products which are carried to the flue. The slag 

 is granulated in water and passed to the dump. The '' matte " is 

 carried to the converters, where it is treated in the same way as 

 " matte " from the blast furnaces. 



The blast furnace receives a charge consisting essentiall}^ of the 

 high-grade ores, converter slag, briquettes of siliceous fines and 

 slimes from the concentrator, limestone, and coke. A large part of 

 the sulphur passes off to the flue as sulphur dioxid and trioxid, 

 and large amounts of arsenic are volatilized. The iron and silica 

 in the ore, together with the lime, form a slag (containing a very 

 small amount of copper) which is granulated in water and carried 

 to the dump ; the copper forms a " matte " consisting principally 

 of a combination of copper, iron, and sulphur. This, together Avith 

 the " matte '' from the reverberatory furnaces, is next carried to the 

 converters, the lining of which is a siliceous material that lasts for 

 several runs. 



In the converter the sulphur which is present in the '• matte '' is 

 oxidized to sulphur dioxid and trioxid and escapes up the flue, the 

 remaining arsenic is volatilized and also goes np the flue, while the 

 iron unites with the siliceous lining to form a slag which is returned 

 to the blast furnaces, since it is a good flux and also contains con- 

 siderable quantities of copper. The copper obtained by this process 

 is carried to the preliminary refining apparatus, where air is passed 

 over the molten mass to remove traces of sulphur and the small 

 amount of slag Avhich was not taken out in the converters is also 

 eliminated. During this process some copper oxid is formed, but 

 upon stirring this is again reduced to copper by the carbon of the 

 converter poles. In this condition the copper is cast into ingots, 

 which are sold to refineries not situated at Anaconda. 



The fumes from these processes are passed through long cooling 

 chambers in order to condense the volatilized compounds of arsenic 

 as far as possible, but in spite of this precaution large amounts of 

 arsenic escape from the toj^ of the chimney. Xo attempt is made to 

 recover any of the sulj^hur compounds. 



RESULTANT WASTES. 



From this brief description of the process used at Anaconda, it 

 will be evident that four wastes arise which may be injurious to plant 

 or animal life. 



(1) The sulphur contained in the ore is gradually given off dur- 

 ing the various processes of smelting, as sulphur dioxid and a little 

 sulphur trioxid, which would have their injurious action on vegeta- 

 tion. 



