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Percolation bacterial leaching of low-grade chalcopyrite using acidophilic microorganisms
Karanam Srinivasa Rao,Amrita Mishra,Devbrata Pradhan,Gautam Roy Chaudhury,Birendra Kumar Mohapatra,Trupti Das,Lala Bihari Sukla,Barada Kanta Mishra 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.3
Bioleaching studies were carried out in percolation columns using low-grade copper containing rock (granite). The lixiviant consisted of acidified ferric sulfate containing acidophilic microorganisms. The iron oxidizing strain was isolated from Malanjkhand mine water and after adaptation the iron oxidation observed to be 500 mg/L/h. Leaching parameters studied were lixiviant flow rate, particle size and bed height. It was observed that leaching efficiency increased with decrease of particle size and lixiviant flow rate. The precipitation of iron during leaching observed to be low as pH was maintained at 2. Based on the leaching kinetics, a unified rate equation was developed and shown as ra(dp)[−0.61 (F)−0.76 (Hb)0.97.]수식
Karanam Srinivasa Rao,Shashi Anand,Paladugu Venkateswarlu 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.5
Syzygium cumini L. leaf powder and Cd(II) loaded samples were characterized using FTIR and SEM techniques. The biosorption of cadmium ions from aqueous solution was studied in a batch adsorption system as a function of pH, contact time, adsorbate, adsorbent, anion and cation concentrations. The biosorption capacities and rates of transfer of cadmium ions onto S. cumini L. were evaluated. The kinetics could be best described by both linear and nonlinear pseudo-second order models. The isothermic data fitted to various models in the order Freundlich>Redlich-Peterson>Langmuir>Temkin. The maximum adsorption capacity of S. cumini L. leaves at room temperature was estimated to be 34.54 mg g−1. The negative values of ΔG0 indicated the feasibility of the adsorption process. The endothermic nature was confirmed by the positive value of the enthalpy change (ΔH0=3.7 kJ mol−1). The positive value of entropy change (ΔS0=16.87 J mol−1 K−1) depicted internal structural changes during the adsorption process.
Lala Bihari Sukla,Mousumi Mishra,Sradhanjali Singh,Trupti Das,Rabi Narayana Kar,Karanam Srinivasa Rao,Barada Kanta Mishra 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.3
Bioleaching involves the use of iron and sulfur oxidizing microorganisms to catalyze the dissolution of valuable metals. In this investigation, lagoon material contains 0.39% Cu, in which the major copper bearing mineral is chalcopyrite associated with other minerals present as minor phase. Leaching experiments were carried out using an adapted strain of Acidithiobacillus ferrooxidans with various parameters such as presence/absence of iron, pH, pulp density and temperature. Base of the medium was 9 K (without ferrous) Bio-dissolution of copper was found to be maximum, i.e., 80.9% with 9 K+ (with ferrous) at pH-2.0, 10% pulp-density and 35 oC within an incubation period of 30 days.