Mineral Processing
Sasan Mirshekari; Mehdi iranajad; Hossein Kamran Haghighi
Abstract
In recent years, the use of microorganisms in the flotation of sulfide minerals has gained significant attention, particularly in processes requiring reduced chemical consumption and the utilization of saline water. The targeted application of microorganisms can improve flotation process conditions. ...
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In recent years, the use of microorganisms in the flotation of sulfide minerals has gained significant attention, particularly in processes requiring reduced chemical consumption and the utilization of saline water. The targeted application of microorganisms can improve flotation process conditions. Halophilic bacteria, as salt tolerant species, can be beneficial in selectively depressing pyrite during flotation. This study aimed to investigate the effect of the halophilic bacterium Bacillus mojavensis on enhancing the separation of chalcopyrite from pyrite in froth flotation using seawater. Experiments were conducted at five pH levels, and changes in recovery, flotation kinetics, and contact angle were evaluated. The results showed that the presence of the bacterium improved process selectivity and enhanced chalcopyrite flotation behavior at pH values between 6 and 10, while bacterial performance decreased at pH 4 and pH 12. The maximum recovery improvement was observed at pH 8, where chalcopyrite recovery increased from 55.11% to 62.04%, and the kinetic constant K was higher than that of the bacteria free sample. Contact angle measurements indicated that the bacterium significantly reduced pyrite hydrophobicity (from 73.73° to 46.7°) without causing noticeable changes in chalcopyrite (~75.8°); this behavior was attributed to the selective adsorption of EPS and bacterial cells on the pyrite surface, leading to its surface deactivation. The findings suggest that Bacillus mojavensis, due to its salt tolerance and stability in neutral to alkaline pH ranges, is a suitable candidate for use in seawater-based flotation circuits and low chemical consumption processes involving pH regulators.
S. Mirshrkari; V. Shojaei; H. Khoshdast
Abstract
A coal waste sample loaded with Fe3O4 nanoparticles is employed as an efficient adsorbent to remove Cd from synthetic wastewater. The synthesized nanocomposite is characterized using the Fourier transform-infrared (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. ...
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A coal waste sample loaded with Fe3O4 nanoparticles is employed as an efficient adsorbent to remove Cd from synthetic wastewater. The synthesized nanocomposite is characterized using the Fourier transform-infrared (FT-IR), X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The visual analysis of the microscopic image shows that the mean size of the magnetite nanoparticles is about 10 nm. The effects of the operating variables of the initial solution pH (3-11) and nanocomposite to pollutant ratio (7-233) are evaluated using the response surface methodology on cadmium adsorption. The process is also optimized using the quadratic prediction model based on the central composite design. The statistical analysis reveals that both factors play a significant role in Cd adsorption. The maximum Cd removal of 99.24% is obtained under optimal operating conditions at pH 11 and nanocomposite/cadmium ratio of 90 after 2 h of equilibrium contact time. A study of the adsorption kinetics indicates that the maximum removal could be attained in a short time of about 2 min following a first-order model. The isotherm investigations present that the Cd adsorption on the Fe3O4/coal waste nanocomposite has a linearly descending heat mechanism based on the Temkin isotherm model with the minor applicability parameters than the other isotherm models. The overall removal behaviour is attributed to a two-step mechanism including a rapid adsorption of cadmium ion onto the active sites at the surface of nanocomposite followed by a slow cadmium hydroxide precipitation within the pores over the nanocomposite surface.
