TN643 : Zinc recovery from low grade zinc oxide ores of Esfahan Bama (Goushfil) mine by using acidic and basic leaching methods
Thesis > Central Library of Shahrood University > Mining, Petroleum & Geophysics Engineering > MSc > 2016
Authors:
Seyedmahyar Seyedghasemi [Author], Asghar Azizi[Supervisor]
Abstarct: Zinc leaching from low grade oxide ores of Esfahan Bama Goushfil mine tailings was investigated by various leaching reagents including sulfuric acid, hydrochloric acid, nitric acid, citric acid and sodium hydroxide. Also, the effect of important factors including leaching agent concentration, liquid to solid ratio, stirring speed, temperature and leaching time were determined on the zinc recovery. The results show that, the leaching in sulfuric acid and hydrochloric acid solutions is strongly affected by acid concentration. Liquid to solid ratio and leaching time had the greatest influence on the zinc dissolution in the nitric acid solution, while the concentration and temperature had the most effect on zinc leaching by citric acid. In addition, concentration, stirring speed and temperature had a significant impact on the recovery of zinc by sodium hydroxide solution. Meanwhile, sulfuric acid had the lowest recovery of zinc (61.37%) under optimum conditions. Zinc leaching kinetics of Goushfil low grade oxide ore were studied baxsed on the shrinking core models, which the results showed that the leaching rate of zinc was controlled by the liquid film diffusion model with activation energies of 17.33, 11.33, 4.38, 15.6 and 13.92 kJ/mol, for sulfuric acid, hydrochloric acid, nitric acid, citric acid and sodium hydroxide, respectively. In addition, the zinc leaching process modeling from low grade oxide ores to obtain the mathematical relation between effective factors and leaching rate, to determine the interaction factors and to maximize the zinc recovery was performed on nitric and citric acid leaching process baxsed on the response surface methodology-central composite rotatable design. The results indicated that maximum recovery of zinc at citric acid leaching was achieved to be of 94.5% under optimum conditions: acid concentration of 0.99 mol/L, temperature of 79.66 °C, stirring speed of 412.74 rpm, liquid to solid ratio of 20.61 mL/g and leaching time of 81.76 min. Whereas optimum conditions suggested using software DX 7 for leaching of nitric acid found to be acid concentration of 14.02%, temperature of 76.68 °C, stirring speed of 499.94 rpm, liquid to solid ratio 20.61 and leaching time is 90 min. Under these conditions the recovery of zinc was determined to be 90.89%. Finally, the effect of additives such as Na2EDTA and NaCl was investigated in the zinc dissolution from low grade oxide ores using leaching agents of sodium hydroxide, citric acid and hydrochloric acid. It was found that these additives have a positive effect on increment of dissolution of zinc and lead.
Keywords:
#Low grade oxide ore #Goushfil mine tailings #Zinc leaching #Dissolution kinetics #Activation energy #Response surface methodology #Additives Link
Keeping place: Central Library of Shahrood University
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