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Today, with the ever-increasing concerns about the widespread environmental impact of the mining industry, the movement of the mineral processing sectors, which heavily rely on various chemical and petroleum-origin reagents, to the green industry is imperative. Due to the advantages biotechnological approaches provide, bioprocessing is considered a benign alternative to conventional mineral processing techniques. Recent fundamental research works have directed the attention to the development of biotechnology and using microorganisms in the new field of biobeneficiation, especially bioflotation. The current review categorizes bioflotation methods into direct and indirect processes giving an in-depth insight into their concepts. Furthermore, this study provides a comprehensive review of research on different aspects of bioflotation, such as the effects of operating (mainly solid content and pH) and biotechnological parameters, potential mechanisms, and unexplored points, but from different, and practical viewpoints. Recent studies were summarized by categorizing microorganisms based on their wall structures, and growth temperature. It was disclosed based on the literature data that the nutritional requirement of variant microorganisms was only chemolithotroph. Further, the conducted researches in investigating optimum conditions for maximization of contact angle and adhesion forces to reach the maximum recovery were reviewed. In addition, existing problems and challenges of this field were investigated and it was found that economic barriers and obscurities were the main obstacles of industrial application in mining and mineral processing industries. Finally, new perspectives and suggestions were presented to shed light on future research and help to solve the challenges currently facing its application. [ABSTRACT FROM AUTHOR]

This investigation assessed the influence of a cationized pyrolysis oil (PO) produced by the pyrolysis of used car tires on coal flotation using an extended Historical Data (HD) design. The effect of operating factors, including pulp solid content, diesel oil, pine oil, and pyrolysis oil dosages, was examined using experimental and statistical analyses. Fourier Transform Infrared Spectroscopy (FTIR) measurement showed that PO contains hydrocarbons and their oxides (alkane, ester, or carboxylic acid). Statistical analysis using analysis of variance (ANOVA) revealed that concentrate ash content is influenced by solid content and pyrolysis oil concentration through a non-linear trend such that maximum ash removal may be obtained at the middle level of solid content and in the absence of PO. The solid content and diesel oil had a significant impact on process yield. Maximum yield was achieved at the low and middle levels of solid content and collector dosage, respectively. A comparison of individual and interaction effects of significant operating variables showed their complicated effects on process responses. Overall, the PO affected the coal flotation efficiency adversely, which can be due to the interaction between hydrophilic groups in the PO structure and the oxide nature of non-combustible materials in coal particles. [ABSTRACT FROM AUTHOR]

Flotation process is the most common beneficiation method of almost all types of minerals. The desirable result of the process is dependent on various factors. One of the most effective parameters in this regard is the particle size. Generally, acceptable results can be obtained by adjusting particle size in an optimum and specific range, and flotation of coarser or finer than this range is always intricate and problematic. Specifically, in the case of fine and ultra-fine particles, this complexity becomes more aggravated most importantly because of the massive specific area and the reduction of particle-bubble collision and attachment probabilities. There is a vast amount of literature on fine particles flotation using micro- and nanobubbles, intensified flotation machines, and different chemical reagents, however, the most promising procedure in this regard can be considered as the increment of particle sizes via agglomeration and flocculation techniques combined with flotation. This technique provides great opportunities for recovering fine and ultra-fine particles economically and increment of sustainable processing. However, there are some gaps and obscure points such as the exact mechanism of bubble-floc adsorption, interaction between flocs and reagents, pulp properties variations due to flocculation, and its effects on flotation behavior. This paper categorizes and describes diverse aspects of this combined novel technique in detail and provides a comprehensive source for readers to have a deeper insight into this intricate process. First of all, the physicochemical characteristics of the process have been described thoroughly from perspectives including the type and structure of applied chemicals, influential parameters, and involved adsorption mechanisms. It is followed by a detailed interpretation of different floc-flotation techniques as well as their cons and pros, effective parameters, and possible improvement and optimization approaches. Further, some similar techniques such as oil agglomeration, hydrophobic-hydrophilic Separation, and carrier flotation were described and compared with present technique of floc-flotation. Technological aspects of the process as well as an industrial case study of this technique were other areas which have been investigated in this paper and finally, scientific and technical gaps in this branch of flotation technology were extracted to open-up new horizon ahead of researchers active and/or interested in this field. [ABSTRACT FROM AUTHOR]

Many reagents are used as frother in flotation process, however, a general reference for their identification and characterization is not available. The present work categorizes the commonly used frothers and evaluates the available methodologies to determine their properties. In this paper, frothers properties such as molecular weight, viscosity, boiling and freezing point, hydrophile-lipophile balance number, solubility, surface activity and critical micelle concentration were discussed. The commonly used measurement methods for froth structure and dynamic and static frothability were also presented along with water recovery index and critical coalescence concentration (CCC). Results showed that the practical identification of frothers properties has not been thoroughly evaluated and therefore, there is a need for developing novel and easy-to-apply experimental methods in this area. For example, it was found that there is no promising single process to measure the CCC value. This review revealed that the 2D froth structure measurement methods are associated with a considerable bias, while 3D techniques can effectively represent the actual froth properties. It was also found that the potential interactions between various frothers properties and how they can influence the flotation performance in an industrial environment are not yet understood and needs further investigation. It was also identified that there is no standard instruction to provide a reliable connection between both manufactures and frothers consumers. In our opinion, the current review paves the path for the elaboration of knowledge and technology to provide promising methods for determining conventionally used and complex frothers properties. [ABSTRACT FROM AUTHOR]

In this paper, an extended Historical Data (HD) design was applied for evaluating the effect of an acetonized pyrolysis oil (PO) produced by pyrolysis of spent-car tires in coal. Experimental and statistical analyses were applied for examining the influence of some operating variables such as concentration of diesel oil (0, 10, and 20 L/t), pine oil (0.55, 0.1, and 1 L/t), and the pyrolysis oil (0, 10, and 20 L/t) as well as solid content of pulp (5, 10, and 15% (w/w)) on the yield and ash content of final concentrate. Fourier Transform Infrared Spectroscopy (FTIR) measurements showed that PO contained hydroxyl, aldehyde, aliphatic, and aromatic compounds. Based on the results of Analysis of Variance (ANOVA), the main effect of all variables, except concentration of pine oil, on the flotation responses were found significant. Batch flotation experimental results indicated that using pyrolysis oil resulted in a 2% increase in ash content and a 35% decrease of the yield, through a nonlinear trend. The curved behavior of flotation measures was due to the possible competitive adsorption between PO and diesel oil and nonselective interaction between pyrolysis oil and other reagents. The negative effect of PO on coal flotation efficiency was also ascribed to the interaction between hydrophilic groups in PO structure and the oxide nature of non-combustible materials of coal particles. [ABSTRACT FROM AUTHOR]

Recent attempts to produce effective adsorbents for wastewater treatment purposes have led to development of multiphase nanocomposite consisting of a bed, nanoparticle enhancer(s) and one or more polymeric modifiers. However, availability and final price have been always prohibitive factors challenging the wide application of many of multiphase adsorbents. In this research work, a novel bipolymeric/Fe3O4 nanocomposite loaded on coal tailings was synthesized using a two-step procedure and evaluated as a potential low-cost adsorbent for treating synthetic wastewater polluted by heavy metals. Starting material and synthesized quadriphase nanocomposite were characterized using different instrumental analysis techniques. The adsorptive capacity of the nanocomposite was assessed using response surface methodology (RSM) by considering the nanocomposite-to-cadmium ratio (7–233) and initial pH of solution (3–11) as operating factors and cadmium removal as process response. The significance of the effect of operating variables on removal efficiency was assessed and confirmed using analysis of variance (ANOVA) method. The maximum cadmium removal of 99.30% was obtained under optimum conditions including pH of 10 and quadriphase nanocomposite/cadmium ratio of 40 after 2 h of adsorption. Kinetics and multistep adsorption studies showed that an optimum adsorption of 97% could be obtained only after 1.2 min following a first-order single-step process. Isotherm plots revealed that cadmium adsorb as monolayer on the surface of synthesized quadriphase nanocomposite based on Temkin model with the highest correlation coefficient of 97.67% and the least relative error of 16.15%. [ABSTRACT FROM AUTHOR]

Although column flotation cells have been extensively studied in the literature, the hydrodynamic impact of orifice properties has not been adequately addressed yet. This paper initially investigates the effect of sparger orifice diameter on hydrodynamic behavior of coal particles in a pilot-scale column flotation. The metallurgical responses (i.e., ash, yield and recovery contents) were evaluated for four different sparger orifice sizes including 1, 3, 5, and 7 mm under constant operating conditions by experimental measurements associated with computational fluid dynamics (CFD) simulations. A numerical model of a two-phase air-water flow in the column (3 m × 0.5 m) was chosen and the turbulence patterns inside the collection zone and at the pulp-froth interface were simulated by employing the Volume-Of-Fluid (VOF) model. The experimental results indicated that desiring concentrated product i.e., ash content of 8.8% and yield of 57.2% could be obtained using the 3 mm orifice size. Simulation results revealed that as the sparger orifice size decreased to 1 mm, the reduced carrying capacity of the bubbly regime led to the poor flotation performance. In contrast, the turbulence condition intensified as the sparger orifice size was increased to 7 mm. Another negative consequence of the 7 mm orifice was attributed to the exceeded entrainment of high ash fines due to a bubble swarm mechanism. The 7 mm sparger orifice diameter showed a concentrate of 17.1% ash and 12.5% yield. Finally, according to the obtained results in this work and literature studies, several necessary highlights were suggested for future works in this scope. [ABSTRACT FROM AUTHOR]

Even though vibrating screens have been used in mining industries for over a century, their use has often been cited as challenging in terms of understanding its dynamic responses to different operating factors, particularly those that affect the structural aspects. Among the various aspects of screen design, the control of vibrational energies imposed on various parts of the screen is of particular importance because these vibrations directly affect the separation efficiency and useful life of the screen. This study proposes the use of vibration absorbers to control the adverse effects of severe screen vibrations. The dynamic behavior of a medium-sized vibrating screen utilized in the aggregate industry was investigated using the finite element method for both spring/dashpots and conventional solely spring systems. The modeling process was performed in loaded and unloaded conditions and in three frequencies of 15, 23, and 27 rad/s. Numerical simulation results showed that the use of dashpots can significantly reduce the maximum stress in the screen, such that the maximum stress in the center of gravity of the screen at the optimal frequency of 23 decreased from 237 to about 97 MPa. Also, sieve modal analysis showed that the stress in the sieve equipped with the spring/dashpots system had a more uniform distribution. The results revealed that the use of vibration absorbers can be a promising solution to prevent damage caused by high vibrational energies in screens. [ABSTRACT FROM AUTHOR]

Design of experiments (DOE) is an effective method providing useful information about the interaction of operating variables and the way the total system works by using statistical analyses. However, its industrial application is limited because it is almost difficult to maintain variables in DOE matrix at desired constant levels in industrial environment. Thus, this paper aims to present a new mixed modeling method which is a combination of fuzzy logic and design of experiments methods to overcome such practical limitations. The method first uses a fuzzy model which is trained by practical data gathered from industry to predict DOE response corresponding to each run in DOE matrix. Then, a statistical parametric model is constructed for the prediction of process response to any change of operating parameters under real industrial conditions. The proposed mixed method was successfully validated by using data obtained from a coal hydraulic classifier at Zarand Coal Washing Plant (Kerman, Iran). The method also seems to be a promising tool for modeling all devices and processes in real industrial environment and allows researchers to benefit from all the advantages of experimental design and fuzzy logic methods simultaneously. [ABSTRACT FROM AUTHOR]

Inthis research, the potential of cadmium removal from aqueous solutionby foam flotation with a rhamnolipid biosurfactant sample was studied.The effects of different major operating conditions, such as rhamnolipidand cadmium concentrations, solution pH, aeration rate, and frothertype and concentration, on the cadmium removal were investigated.The selectivity coefficients in the presence of rhamnolipid maintaineddefinite orders as follows: cadmium > zinc, cadmium > copper,and zinc > copper. The selectivity coefficient of cadmium overcopper was the highest one. The maximum removals of Cd from cleanand Zn- and Cu-contaminated solutions were about 57%, 36%, and 48%,respectively. Kinetic studies indicated that ion flotation of cadmiumfollows a first-order equation with a kinetic rate of 0.0071 min–1. Although the removals are rather low, it seems thatthe use of rhamnolipid biosurfactant can be promising in heavy-metalremoval from wastewaters by foam flotation with some modifications. [ABSTRACT FROM AUTHOR]