270 MINING INDUSTBT. 



Stetepeldt's Furnace. — The most expensive item in the cost of work- 

 inp- first-class ores by the method just described is the roasting and chlorid- 

 izing operation. This alone is generally estimated at $15 per ton of ore, 

 though it is sometimes less. Any efficient method of obtaining the same 

 results at a less cost is greatly to be desired, since there are many mining 

 districts, not only in Nevada, but throughout our silver-producing regions, 

 the development of vv^hich is hindered by the want of cheaper metallurgical 

 processes. 



"Within the past year a new furnace, devised and introduced by Mr. C. 

 A. Stetefeldt, of Austin, has been put in operation near Virginia, and, judging 

 by the experience thus far obtained, it promises results that will be of great 

 importance to our silver mining districts. It is reported that one of these 

 furnaces is about to be built for the Manhattan Company, in Austin, a region 

 where, as will be shown further on, cheap roasting is very much to be desired. 

 A brief description of the Stetefeldt furnace is given in the following para- 

 graphs. 



This is designed as a desulphurizing and chloridizing furnace. Its oper- 

 ation consists essentially in allowing the very finely pulverized ore, mixed with 

 salt, to fall against a current of hot air that rises in a shaft, during w"hich fall 

 the fine particles of sulphureted metals are decomposed, forming metallic 

 oxides, sulphurous and sulphuric acid. The latter attacking the salt, chlorine 

 is liberated, which combines with the oxides of the metals, or acts upon the 

 still undecomposed particles of sulphuret, thus producing the metallic chlorides. 



The chemical action is in most respects the same as that which takes 

 place in the reverberatory roasting furnace, but as the ore falls in a finely divided 

 condition, or shower of particles, each atom is exposed more freely to the op- 

 eration of the heat and the oxidizing and chloridizing agents ; their efiect is 

 more rapid and complete while the amount of manual labor required is very 

 much less than in the reverberatory. The furnace was invented several years 

 since and an experimental one was built at the mine of the Twin River Com- 

 pany, in Ophir Canon, Nevada; but although aifording results that were in 

 most respects satisfactory, it was not then brought into continued use. During 

 the past year another, designed for regular and permanent operation, was 

 built at Reno, near Virginia, and employed in roasting ores brought from 



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