322 Scientific Proceedings, Royal Dublin Socieiy. 



Process of Sterry Hunt and Douglas. 



In the process of Hunt and Douglas,* the solvent used for 

 lixiviating is a solution in brine of ferrous chloride (Fe G\), 

 this decomposes cupric oxide forming cuprous and cupric chloride, 

 which pass into solution (the former, although insoluble in water 

 dissolves in brine) while ferric oxide separates. 

 . The dissolving bath is made by adding ] 20 parts of salt (or 

 112 parts of calcic chloride), and 280 parts of sulphate of iron 

 to 1,000 parts of water, then 200 parts of salt are added, 

 ferrous chloride is formed, with this the crushed and roasted 

 ore is treated when the cupric oxide is converted into chloride 



3 Cu + 2 Fe CI, Cu CL + Cu, CL + Fe, O3. 

 but if cuprous oxide be present, metallic copper is deposited, 



3 Cu, + 2 Fe C],=2 Cu, CI, + Fe, O3 + Cu, 

 the solution, when the reaction is complete, is drawn off and 

 treated with scrap-iron to precipitate the copper, ferrous chloride 

 being thus reformed, so that the liquors may be used repeatedly 

 to dissolve the copper from the roasted ore. 



At the Knob Copper Reduction Works, Carolina, the crushed 

 and roasted ore is treated with the solution of ferrous chloride 

 and salt for eight hours at 1G0° F., it is then allowed to settle for 

 four hours, when the clear liquors are run to the precipitating 

 tanks (the muddy portions having been allowed to subside), where 

 they are treated with scrap-iron for twelve or eighteen hours at 

 160° F., when all but a trace of copper has been precipitated, the 

 liquors are then run on to a fresh supply of roasted ore. 



This process seems to be specially applicable to ores containing 

 oxide of copper, it may, however, be applied to carbonates and 

 sulphides after grinding and roasting, the objection has been 

 raised that poor ores will not bear this preliminary treatment. 

 But it seems to have been successfully applied at the Ore Knob 

 Works and at Chile. 



* For a full account of this process, see "Engineering," Vol. xxii., page 419>; 

 " Chemical News'," (1870), Vol xxi., page 177. For a description of the Ore Knob 

 Mine and the working of the process, see " Transactions American Institute of Mining 

 En"-ineers." Vol. iii., page 391. Other improved processes are described in "American 

 Journal of Science," Vol. xliii., page 305, and one by W. A. Dixon, f.c.s., "Journal 

 Royal Society," New South Wales, 1877, Vol. xi., pp. 93-111 ; and " Chemical News," 

 1878, Vol. xxxviii , pp. 281, 293, 301. 



