COPPER SMELTING 



The determinations called for in the laboratory of a copper 

 smelter do not vary a great deal from those required in lead 

 smelter practice; except for the fact that copper in some form or 

 other, will be found in all samples, solutions, etc., with which we 

 have to deal. Where this element interferes to any extent, the fact 

 will be noted and the remedy suggested. 



Slags, ores,* sulphurs, zinc, lead, etc., are analyzed or deter- 

 mined by one of the methods already given in the chapter on 

 Lead Smelting. 



Copper. — All samples containing more than 2 or 3$ copper, 

 such as mattes, ores, copper cakes, etc., are run for copper by the 

 electrolytic method, as follows: 



Weigh out from | to 1 gram of ore in a No. 3 beaker; just 

 moisten with a drop or two of water, then add from 10 to 15 cc. of 

 strong nitric acid, and 5 to 8 cc. of sulphuric acid, and heat until 

 white fumes of sulphuric acid are given off. Be sure that all of the 

 ore (which is soluble in acids) has been dissolved, then dilute to 

 about 80 cc. heat again just to boiling, to disintegrate the mass; 

 filter off the residue in which the lead and silica may be deter- 

 mined if necessary. Filter the solution into a No. 2 beaker, add 

 1 or 2 strips of heavy aluminum foil, boil for 10 or 15 minutes, 

 which is generally sufficient to insure complete precipitation of 

 the copper. Pour off the solution and wash 3 times by decantation 

 with hot water. Then add 3 or 4 cc. of strong nitric acid to the 

 contents of the beaker, allowing the acid to flow over the alum- 

 inium. Boil to expel the nitrous fumes, decant into another beaker 

 (a long narrow one) and rinse the alumnium with a few drops of 

 water; just neutralize the solution with ammonia, and add about 



* Copper interferes with the determination of Fe by the bi-chromate method. Either pre- 

 cipitate the iron with NH 4 0H, filter off, and redissolve or use test lead to reduce the 

 iron after the insoluble residue has been removed. (Furman, page 180B.) 



