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BELL SYSTEM TECHNICAL JOURNAL 



kept as low as practicable to minimize "carrying out losses" ^ during 

 the pickling operation. About 775 pounds of acid and 430 pounds of 

 copper are recovered per day from the electrolyte. The anodes are 

 operated at a current density of 5 amperes per square foot with a rate 

 of deposition of about .00261 pound of copper per ampere hour. 



120° F 



no" F 



100° F 



90° F 



Max. Temperature without 

 excessive evap. and fuues 



MiN. Temp, of Solution caused by 

 Electrolytic and Cheuical Action 



20 25 30 55 40 45 50 55 



Minutes 



Fig. 8 — Rate of pickling at practical acid concentrations 



The heat generated in the plating tanks under normal operating 

 conditions maintains a minimum temperature of about 90° F., through- 

 out the acid system, and the maximum temperature is obtained through 

 steam heating coils in the pickle tanks. Faster pickling would result 

 from the use of higher temperatures but experience has shown that the 

 additional steam and gas released above 120° F. results in unsatis- 

 factory operating conditions. 



^ Pickling solution carried out when coils are removed from tank. 



