135 



RECENT COPPER-EXTRACTING PROCESSES. 



Br S. L. Benstisax. 



[^Read before the Royal Society of N.S.W., 4 Oc'oler, 1876.] 



In the following paper I propose to make special reference to 

 some of the new and improved methods known as " wet " pro- 

 cesses for the extraction of copper from its ores. 



Among the new methods which have been introduced, a 

 variety of conditions exist, under which one or other has main- 

 tained its claims to the possession of some advantages over its 

 competitors ; in the main, however, they all aim at the extraction 

 of the metal by processes requiring the smallest outlay in plant, 

 &c., coupled with the minimum expenditure in chemicals and 

 labour. Some metallurgists have sought to utilize bye products, 

 as an auxiliary to other sources of profit ; some have directed 

 their attention to the simultaneous extraction of valuable metals 

 sometimes associated with copper ores ; a few have studied to 

 perfect processes which are only available under certain special 

 conditions, wherein the usual methods are not capable of being 

 employed ; and in cases where complicated mixtures have existed 

 of metals, the extraction of one of which alone would not pay, 

 many and ingenious devices have been resorted to, for utilizing 

 and turning to profitable account portions of the constituents 

 of the mineral which hithero have been a source of actual loss. 



In the Australian Colonies the j^rincipal considerations which 

 appear to suggest themselves, in connection with this subject, 

 are, — the adoption of processes which do not . necessitate the 

 usual large outlay, and the utilization of such as are most 

 available for particular districts, and to meet special conditions. 

 One great desideratum is necessarily to make the modus operandi 

 so clear and intelligible that it may be easily understood by most 

 persons not possessed of special metallurgic knowledge. In a 

 country like this, where the population is so scattered, and in 

 which so much metallic treasure is known to exist, it is most 

 desirable that a resume of all that is generally known on the 

 subject should be diffused ; and while each inventor or discoverer 

 of any new process only aims at the publication of his particular 

 views and theories, and doubtless does much good, it is hoped 



