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Srichandan, Haragobinda,Pathak, Ashish,Kim, Dong Jin,Lee, Seoung-Won Marcel Dekker 2014 Journal of Environmental Science and Health. Part Vol.49 No.14
<P>A central composite design (CCD) combined with response surface methodology (RSM) was employed for maximizing bioleaching yields of metals (Al, Mo, Ni, and V) from as-received spent refinery catalyst using Acidithiobacillus thiooxidans. Three independent variables, namely initial pH, sulfur concentration, and pulp density were investigated. The pH was found to be the most influential parameter with leaching yields of metals varying inversely with pH. Analysis of variance (ANOVA) of the quadratic model indicated that the predicted values were in good agreement with experimental data. Under optimized conditions of 1.0% pulp density, 1.5% sulfur and pH 1.5, about 93% Ni, 44% Al, 34% Mo, and 94% V was leached from the spent refinery catalyst. Among all the metals, V had the highest maximum rate of leaching (Vmax) according to the Michaelis-Menten equation. The results of the study suggested that two-step bioleaching is efficient in leaching of metals from spent refinery catalyst. Moreover, the process can be conducted with as received spent refinery catalyst, thus making the process cost effective for large-scale applications.</P>
Haragobinda Srichandan,Ranjan Kumar Mohapatra,Puneet Kumar Singh,Snehasish Mishra,Pankaj Kumar Parhi,Kalyani Naik 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.90 No.-
Bioleaching being an economically feasible process is considered as a potential alternative of hydro- and pyro-metallurgical processes of metal recovery. The process can be performed in shake flasks, batch reactors, continuous reactors, columns and heap. As the data and knowledge obtained from both column and heap bioleaching are often similar, the majority of successful small scale (shake flasks, batch reactors and continuous reactors) studies are scaled up to heap after the interpretation of the results in column studies and extrapolation, indicating the importance of column bioleaching. This review is the first in this domain, especially on column bioleaching, elaborating the process operation, applications and the various critical factors viz., ore pretreatment, column bioleaching set-up, microbial adaptation, pH, temperature, size fractions, microbial diversity, irrigation (flow) rate, process optimisation, rDNA technology, etc. affecting column bioleaching. Further, the potential microbial types used in column bioleaching and their mechanism of action have been extensively discussed. The modelling feature to determine bioleaching controlling steps, maximum metal dissolution rate, and additionally a glimpse challenges and future prospects of column bioleaching have been represented.
Chandra Sekhar Gahan,Haragobinda Srichandan,김동진,Sradhanjali Singh,Seoung-Won Lee 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.5
Microbial leaching of a petroleum spent catalyst was carried out using mixed mesophilic iron and sulfur oxidizing acidophiles. Bench-scale batch stirred tank reactors with a working volume of 1 L were used in this study at 35 oC. The pulp density considered for the study was 10% (w/v), while the particle size of the spent catalyst was varied by 45-106, 106-212 and >212 μm. The leaching percentage of Ni from the spent catalyst was found to be highest (97-98%) with varying particle size. However, the leaching yield for rest of the metals like Al, Fe, V and Mo was 70-74%, 66-85%, 33-43% and 22-45%, respectively. Influence of particle size was predominant on the recovery of all metals except Ni. Assessment of the generation of the bioleach residue after bioleaching showed a weight loss of 54-62% due to the dissolution of the metal values from the spent catalyst. The mineralogical study conducted by X-ray diffraction and scanning electron microscopy supports the dissolution of metals from the spent catalyst. Jarosite mineral phase was the dominant mineral phase in the bioleach residue due to the dissolution of the oxidic and sulfidic mineral phases present in the feed spent catalyst.