S.K. Biswal

Preparation of graphene oxide by dry planetary ball milling process from natural graphite

Graphene oxides (GO) with different degrees of oxidation have been prepared by an in-house designed horizontal high energy planetary ball milling process. The prepared graphene oxides have been studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) with selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), micro Raman spectroscopy, Fourier transform infrared (FTIR) spectra, Brunauer–Emmett–Teller (BET) test and thermogravimetric analysis (TGA). XPS study shows an increasing trend of atomic concentration ratio of O/C with increasing ball milling time duration from 2 to 24 h of high purity graphite sample (FEED). This result is attributed to the formation of more oxidation in the graphite sample, produced due to the increasing time duration of milling. From micro Raman analysis it is also noted that ID/IG ratio increases with increasing milling time of FEED, which further supported the preparation of graphene oxide. In this study the graphene oxide prepared by 16 h of milling may be considered as the optimized sample as far as the degree of oxidation, time and energy consumption factors are concerned.

Performance evaluation for selectivity of the flocculant on hematite in selective flocculation

Increased demand for iron ore necessitates the utilization of low-grade iron ore fines, slimes, and existing tailings. Selective flocculation can be an alternative physico-chemical process for utilizing these low-grade fines, slimes, and tailings. In selective flocculation, the most critical objective is the selection of proper reagents that will make floc of desired minerals. In present study, selective flocculation was applied to ultra-fine synthetic mixtures of hematite and kaolinite, and the Fe value was upgraded up to 65.78% with the reduction of Al2O3 and SiO2 values to 2.65% and 3.66%, respectively. Here, degraded wheat starch was used as a flocculant.In this process, separation occurs on the basis of the selectivity of the flocculant. The selectivity of the flocculant can be quantified in terms of separation efficiency. Here, an attempt was also made to develop a correlation between separation efficiency and major operating parameters such as flocculent dose, pH value, and solid concentration to predict the separation performance.

Settling characteristics of ultrafine iron ore slimes

The slurry settling characteristics are the most important to design a thickener in process industries. In this work, the iron ore slurry from the screw classifier overflow was used for the settling study. It was observed that the original slurry exhibited a low settling velocity and a turbid supernatant during the settling process. Commercial flocculating agents with anionic, cationic, and nonionic characters were used to improve the settling behavior of suspensions, which were added into the slurry at different ranges of slurry pH values, respectively. The settling results show that the use of flocculants increase the settling rate by several times. Compared with the cationic and nonionic flocculants, the anionic flocculant is more effective in enhancing the slurry settling rate. The small dose of the anionic flocculant is found to be more effective, but the other flocculants are less effective even at higher dosages. The simulation of an industrial thickener was carried out based on the laboratory settling data, and the appropriate design and selection parameters of the industrial thickener were estimated.

Performance Optimization of a Coal Preparation Plant Using Genetic Algorithms

A coal preparation plant typically has multiple cleaning circuits based on size of coal particles. The traditional way of optimizing the plant output and meeting the product constraints such as ash, sulfur and moisture content is to equalize the average product quality from each circuit. The present study includes multiple incremental product quality approach to optimize the clean coal recovery while satisfying the product constraints. The plant output was optimized at the given constraints of 7.5% ash and 1.3% sulfur. It was observed that utilizing incremental product quality process gives 2.13% higher yield which can generate additional revenue of

Artificial neural network approach to assess selective flocculation on hematite and kaolinite

4,260,000 per annum than that obtained by using the equal average product quality approach in this particular case. This paper introduces a novel approach for optimizing plant output using Genetic Algorithms (GA) while satisfying the multiple quality constraints. The same plant product constraints were used for GA based analysis. The results showed that using GA as an optimization process gives 2.23% higher yield that will result in additional revenue generation of

Recovery of Ultra-Fine Iron Ore from Iron Ore Tailings

4,460,000 per annum than average product quality approach. The GA serves as an alternative process to optimize the coal processing plant yield with multiple quality constraints.Copyright

Microbe–Mineral Interactions: Exploring Avenues Towards Development of a Sustainable Microbial Technology for Coal Beneficiation

Because of the current depletion of high grade reserves, beneficiation of low grade ore, tailings produced and tailings stored in tailing ponds is needed to fulfill the market demand. Selective flocculation is one alternative process that could be used for the beneficiation of ultra-fine material. This process has not been extensively used commercially because of its complex dependency on process parameters. In this paper, a selective flocculation process, using synthetic mixtures of hematite and kaolinite in different ratios, was attempted, and the adsorption mechanism was investigated by Fourier transform infrared (FTIR) spectroscopy. A three-layer artificial neural network (ANN) model (4-4-3) was used to predict the separation performance of the process in terms of grade, Fe recovery, and separation efficiency. The model values were in good agreement with experimental values.

Differential desulfurization of dibenzothiophene by newly identified MTCC strains: Influence of Operon Array

Many attempts has been taken for further utilisation of the tailings and slimes through different routes i.e. beneficiation, agglomeration etc. Though the slimes and tailings contain huge ultra fines, conventional beneficiation methods many not be much effective for handling because of particle size limitations. Physicochemical method i.e. selective flocculation is a process for handling the ultrafine particles present in the tailings. Review shows that selective flocculation technique have very limited commercial application. Here the study focuses on the application of selective flocculation process for beneficiation of synthetic mixtures of iron ore and kaolinite as well as iron ore tailings. Results show that it is possible to achieve 65.78(%) of Fe, with 2.65% Al2O3, 3.66 SiO2 (%) in the concentrate using synthetic mixture feed and more than 60% of Fe is obtained from natural iron ore tailings.

Kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor

Microbe–mineral interactions are very pervasive in nature. Since coal is a chief source of nonrenewable energy and finds its application in a wide variety of sectors, the importance of microbe–mineral interaction is indispensible for developing a sustainable microbial coal biotechnology. The underlying necessity of microbe–mineral interaction is also linked with acid mine drainage that is a universal environmental problem in iron- and sulfur-rich environments. In the view of the fact that microbes act as a storehouse of several novel biomolecules or enzymes, they can be used for bioprocessing on an industrial scale incorporating innovative ideas and advanced technologies. The coal mines comprise of several synergistic interactions occurring between microbes and minerals which vary according to pH, temperature, mineralogy, and metal concentration, ultimately forming a viable microbial community.

Study on particle dynamics in different cross sectional shapes of air dense medium fluidized bed separator

Since the sulfur specific cleavage is vital for the organic sulfur removal from fossil fuel, we explored potential bacterial strains of MTCC (Microbial Type Culture Collection) to desulfurize the Dibenzothiophene (DBT) through C-S bond cleavage (4-S pathway). MTCC strains Rhodococcus rhodochrous (3552), Arthrobacter sulfureus (3332), Gordonia rubropertincta (289), and Rhodococcus erythropolis (3951) capable of growing in 0.5 mM DBT were examined for their desulfurization ability. The presence of dsz genes as well as the metabolites was screened by polymerase chain reaction (PCR) and HPLC, respectively. All these strains showed > 99% DBT desulfurization with 10 days of incubation in minimal salt medium. From the HPLC analysis it was further revealed that these MTCC strains show differences in the end metabolites and desulfurize DBT differently following a variation in the regular 4-S pathway. These findings are also well corroborating with their respective organization of dszABC operons and their relative abundance. The above MTCC strains are capable of desulfurizing DBT efficiently and hence can be explored for biodesulfurization of petrochemicals and coal with an eco-friendly and energy economical process.