PROCEEDINGS OF SECTION B. 355 



From this it will be seen that two-thirds of the antimony present 

 remained with the regulus. On melting this calcined regulus, however, 

 the antimony present was considerably reduced, as shown by the follow- 

 ing result : P^j. ^ Per lOO parts of 



Copper present. 



Copper in rich regulus 68-6 — 



Antimony in rich regulus 0"35 '510 



The total elimination of antimony from the regulus during calcining 

 and subsequent smelting amounted to nearly 72 per cent. The experi- 

 ment on the elimination of antimony from this rich regulus up to rough 

 copper was not at all satisfactory. The anode copper which was pro- 

 duced contained more antimony than the rich regulus per 100 parts of 

 copper. This may have been accounted for if more copper in proportion 

 to antimony were carried off in the roasting operation ; but I think 

 the most probable explanation is that the regulus during the roasting 

 picked up extra antimony from the furnace bottom, as the furnace had 

 been in use for some time treating this class of material. 



In the electrolytic refining of copper containing antimony when 

 this latter is present to any extent it is always possible to find this 

 impurity in the cathode copper produced. The anode copper being 

 refined was exceptionally impure, running at times to between 2 per 

 cent, and 3 per cent, of antimony. The amount of antimony that will 

 come down with the cathode copper varies tremendously, being depen- 

 dent on so many things — such as the composition of the anode copper, 

 amperage employed, composition of the electrolyte. 



As a rule, by careful refining, the amount of antimony in the cathode 

 copper may be kept low, even with very impure anodes ; but still it 

 is always possible to find small amounts present, however carefully the 

 refining is done, when this element is there in appreciable quantities 

 in the anode copper. 



Very much depends on the composition of the electrolyte when 

 dealing with copper containing antimony, it being absolutely essential 

 that the strength in acid and sulphate of copper be maintained in the 

 solution, for if either is allowed to drop to any extent the amount of 

 antimony that will plate out is enough to condemn the refined copper. 

 The subsequent treatment of the slime from the anode copper is com- 

 plicated considerably by the presence of this impurity, owing to the 

 antimony being probably in combination with the silver and copper, 

 which renders the extraction of the latter metal difficult. A partial 

 analysis of two samples of slime might be of interest : — 



Cu 30-03 .. 36-6 



Bi 2-36 .. 0-75 



AS2O3 1-86 .. 1-99 



Sh 6-75 ., 5-91 



FeaOg 0-9.5 .. 1-40 



PbSO* .... 4-12 .. 23-32 

 S 10-16 .. 8-81 



Bismuth. — This element is probably the worst one to be present in 

 copper to any extent, but, fortunately, one process used in treating the 

 copper matte or regulus produced from smelting operations has over- 

 come the question of its elimination very satisfactorily. I refer to the 

 Bessemerising of copper matte, this process being far more effective in 

 getting rid of bismuth than the older process by the treatment in the 



