DENVER & RIO GRANDE WESTERN ROUTE. 



253 



From Garfield the route lies almost south along the eastern foot 

 of the Oquirrh Range. At Arthur and Magna there are large mills 

 for- crushing and concentrating the copper ores of the Bingham dis- 

 trict. The Magna plant (see PI. XCVI, A) has a capacity of 14,000 

 tons daily of low-grade ore, and the Arthur plant of 10,000 tons. 

 From Magna southward the train runs over the tracks of the Bing- 

 ham & Garfield Railway, which was built in 1911 for the sole pur- 

 pose of transporting ore from Bingham to Garfield. This road is 

 said to handle a greater tonnage of freight to the mile than any 

 other railroad in the United States. 



After leaving Magna the track winds up the slopes of the moun- 

 tain, but as it traverses mainly the sand and gravel deposited in 

 ancient Lake Bonneville, there are few rock cuts. In this interval 

 the traveler has several excellent views of the terraces of Lake Bonne- 

 ville (see PL XCVI, B), and as the track enters the mouth of Bing- 

 ham Canyon the road has attained about the level of the highest or 

 Bonneville shore line. 



ers are circular, about 22 feet in di- 

 ameter, and have a number of hearths 

 on which the ore is slowly " rabbled " 

 or raked by arms that extend from 

 the center. After entering at the top 

 and passing over the hearths it has 

 been relieved of most of its sulphur 

 and is then dumped into cars. An- 

 other type of roaster produces a co- 

 herent mass called sinter, which natu- 

 rally makes a less dusty charge for the 

 blast furnace. In some places a series 

 of pots are used in which the sulphur 

 is burned off by the aid of a blast 

 after the introduction of burning coal. 

 Years ago at Butte, Mont., the ore was 

 roasted in the open air on piles of 

 cordwood, but the farmers objected to 

 a process which permitted the escap- 

 ing gases to destroy vegetation. In 

 most places, therefore, the smoke and 

 gases are now carefully diverted and 

 treated. The result is that farms now 

 thrive close to smelter stacks, and the 

 smelters make a much better saving 

 of metal. 



The blast furnace in common use is 

 upright and has a rectangular cross 

 section. It is cooled by a water jacket, 

 and the charge on the hearth receives 

 an air blast, as its name implies. For 



the best results the charge must be 

 carefully calculated and weighed. It 

 usually consists of about 75 per cent 

 of ore that has been previously 

 roasted, mixed with coke, limestone, 

 and old scrap iron or slag. After 

 smelting has been in progress several 

 hours lead bullion forms in the cru- 

 cible, if the charge consisted of lead 

 ores, and slag and matte flow into 

 special cars. The bullion is skimmed 

 to remove the dross or impurities and 

 then cast into bars, which are shippetl 

 to refineries where the gold, silver, 

 and lead are separated. The slag, 

 which contains iron, silica, and other 

 substances, is discarded, and the matte, 

 which contains gold, silver, copper, 

 and lead, is either crushed and re- 

 turned to the blast furnace or shippeil 

 to a refinery. Som.e plants use rever- 

 batory furnaces in smelting lead ores 

 that contain little silica. These fur- 

 naces are horizontal and combine 

 roasting with reduction. The product 

 is lead bullion and a residue which 

 may be treated in a blast furnace. In 

 all these operations, but especially in 

 the operation of the blast furnace, the 

 draft of air takes up small particles of 

 ore, and the intense heat volatilizes 



