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| KINETICS OF THE LEACHING OF COPPER SLAG IN AMMONIA SOLUTION UNDER HIGH OXYGEN PRESSURE |
| Liu;S.P.;Chow;Y.H.and Shieh;N.T.Kunming Research Station of the Institute of Metallurgy and Ceramics;Academia Sinica |
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Cite this article:
Liu;S.P.;Chow;Y.H.and Shieh;N.T.Kunming Research Station of the Institute of Metallurgy and Ceramics;Academia Sinica. KINETICS OF THE LEACHING OF COPPER SLAG IN AMMONIA SOLUTION UNDER HIGH OXYGEN PRESSURE. Acta Metall Sin, 1958, 3(2): 99-110.
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Abstract The copper slag under investigation contains chiefly of metallic copper,matteand copper oxides.In order to dissolve both metallic and Cu_2S contained in matte,it is necessary to provide an oxidation condition for the leaching process in highpressure autoclave.The purpose of our investigation was:1.To study the kineticsof the leaching processes;2.To find the most efficient leaching conditions.The kinetics of the leaching process were investigated over a wide range ofNH_4OH and(NH_4)_2CO_3 concentrations,oxygen pressures,temperatures of the solu-tion and stirring velocities.The experimental results show that the leaching processes were diffusion con-trolled reactions,in other words,velocity of diffusion determines the over-all rateof the leaching process and by increasing the speed of agitation of the reactants,the % of Cu extraction is increased.All the experimental results show that the rate of leaching process obeys para-bolic law,that is,the % of copper extraction against time is parabolic functioThe parabolic constant K_P,and the slope of the parabolic were calculatedagainst velocities of stirring,oxygen pressures,concentrations of NH_4OH and(NH_4)_2CO_3and temperatures of the solution.The influence of pH values against the % of copper extraction is a straight-line relationship,but reaches a maximum at some definite pH value.The effect of temperatures upon the efficiency of copper extraction is alsostudied and the plot of log K_P against 1/T gives a straight line relationship.Theactivation energy of this diffusion controlled process was 3.1 kcal/mol.At 60℃,speed of stirring of 360 r.p.m.O_2-pressure of 5 atmospheres and0.65 N of NH_4OH+0.12 N of(NH_4)_2CO_3,the % of copper extraction of this slagwhich contained only 0.96% total copper,is 75% with a leaching time of 8 hours.
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Received: 18 February 1958
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