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Red mud is a residual substance generated as a waste in the refining of bauxite to produce alumina. The handling and disposal of red mud present significant challenges for the alumina industry due to its large volume of production and associated environmental risks, which include high pH, slow settling, and prolonged stabilization time in Tailings Storage Facilities (TSFs). Currently, annual red mud production levels are estimated to range between 0.1 and 0.15 billion tons, depending on the specific bauxite variety and the parameters employed during the digestion process. In general, red mud is composed of several constituents, including silica (SiO₂), gibbsite (Al(OH)₃), boehmite and diaspore (AlO(OH)), anatase and rutile (TiO₂), calcite (CaCO₃), and various iron-bearing minerals such as goethite (FeOOH), hematite (Fe₂O₃), and magnetite (Fe₃O₄). Iron concentrations in red mud demonstrate significant variability, with a range extending from 6% to 60%. These components present potential for further utilization. Owing to the generally fine particle size of red mud, selective flocculation has been proposed as a viable method for the treatment of stockpiled red mud or as an iron separation technique. Compared to chemical extraction methods, selective flocculation is more effective in managing fine particles and offers a less complicated approach. Current research efforts are focused on enhancing the selectivity of the process to yield higher iron content in the concentrates. One such technique involves the development of novel reagents. Bioreagents, derived from living organisms, are being designed to provide an environmentally friendly alternative. Certain microorganisms, such as bacteria and fungi, produce substances that are analogous to the chemical compounds commonly employed in conventional selective flocculation processes or other compounds that are suitable for selective bioflocculation applications. The objective of this review is to provide an overview of the current status of iron concentrations and extraction techniques from red mud, as well as the advancements in iron-selective bioflocculation research to date. It is expected that a comprehensive understanding of the selective bioflocculation method for iron extraction from red mud will be achieved, thereby facilitating the potential for further development of the method. [ABSTRACT FROM AUTHOR]

Hydrogenated oils are commonly used as solvents in the petroleum resin industry. The separation of particulate matter from hydrotreating oil is critical to product quality and the service life of the catalyst in the downstream fixed bed. Conventional separation methods, represented by diatomaceous earth filtration, suffer from low separation efficiency, high material consumption, generation of large amounts of hazardous waste, and cumbersome operation. Therefore, a physical method of microchannel separation coupling hydrocyclone was proposed. A 1 m3/h pilot pretreatment device was established to comprehensively evaluate the particle removal in hydrogenated oil. The high separation efficiency and long operation cycle were achieved by a microchannel separator with 0.5–1 mm particle size quartz sand. The single cycle of the microchannel separator was 75 h. The turbidity was decreased by about 64.3%, which was better than that of the traditional separation method (49.9%). The particle removal in hydrogenated oil by microchannel separator was about 75.0%, while the removal of diatomite separator in the same period was only 44.7%. In a 40 m3/h petroleum resin plant based on a microchannel separator, the operating cost and the hazardous waste emissions are reduced by 1,815,000 CNY/year and 208 tons/year, respectively. It is hoped that this study can not only promote the energy-saving and cleaner production of hydrogenated oil but also provide useful guidance for other petrochemical industries. [Display omitted] [ABSTRACT FROM AUTHOR]

Rare earth elements (REE) are indispensable for industries such as magnetic, phosphorus, metal alloys, catalysts, ceramics, glass, polishing and defense systems due to their unique physical and chemical properties. Currently, China is the largest supplier in the world, accounting for production of more than 95% of the world's rare earth oxides (REO). To reduce the influence of China on the REE market, some countries have started to develop their own national strategies for the production and use of REE-bearing resources. Within the scope of this study, particle size, chemical, MLA, XRD, and SEM-EDS analysis were performed for material characterization, and shaking table, centrifugal, and magnetic separations were carried out for the beneficiation of Malatya/Kuluncak rare earth ore. The XRD analysis indicated that the representative sample consisted of major minerals such as albite, calcite, montmorillonite, muscovite, titanite, kaolinite, clinochlore, and aegirine. Parisite, bastnaesite, Zr-REE-Silicate, Fe-REE-Oxide, and Ca-Ti-Nb-REE-Oxide were detected as REE-bearing minerals by MLA. The chemical analysis resulted in a ∑REO grade of 3628 g/t, and the ore consisted mostly of light REEs. According to the results of the gravity separation for the coarsest fraction, about 11.3% by weight of the total feed was concentrated as a heavy product with 6437 g/t ∑REO content. As a result of magnetic separation, magnetic products with 5561 g/t and 6013 g/t ∑REO were obtained as coarse and fine fractions, respectively. Finally, the characterization studies and enrichment results were correlated, and very important and meaningful indications about the behavior of REE-bearing minerals were obtained. [ABSTRACT FROM AUTHOR]

Summary: Reclaimed asphalt pavement (RAP) has significant recycling value because it contains nonrenewable resources including asphalt and aggregate. However, thus far, only a small part of RAP materials can be used in the construction of recycled asphalt pavement, and the usage is regarded as a low-value utilization in the underlying layers. One of the most important reasons for this shortcoming is the problem of false particle size and pseudo gradation of RAP materials. Therefore, identifying suitable asphalt-aggregate separation technology is essential for improving the utilization of RAP materials in recycled asphalt mixture and enhancing the construction quality of recycled asphalt pavement. To address this, the paper performed a systematic review of asphalt-aggregate separation technologies for processing RAP materials and their prospects. Firstly, based on the composition of the asphalt mixture and the characteristics of RAP materials after aging, the key RAP separation technologies were proposed. Then, the concept, principle, and implementation methods of physical, chemical, and biological separation methods of RAP materials were comprehensively analyzed. Moreover, the advantages and disadvantages of various separation technologies were discussed by comparing them with the related technologies in the petrochemical industry. The application prospects of various asphalt-aggregate separation methods for RAP materials can provide a reference for upgrading and expanding solid waste recycling technology for asphalt pavement.

The paper evaluates all important aspects related to V present in coal and its behaviour during coal combustion with particular attention paid to its potential extraction from ash and slag wastes. Due to great environmental benefits of co-combustion of coal and wastes, these alternative fuels and corresponding ash and slag counterparts were also taken into evaluation. Specifically, the paper summarizes V levels in world coals, in other related materials (alternative fuels, additives etc.) and in ash and slag residues including V speciation and discussion of its valence states. Theoretically predicted (equilibrium-based) calculations and species are compared with experimental results; due to a significant effect on mitigating CO 2 emissions, attention is paid also to oxy-fuel combustion conditions. With the aim to extract V out of the ash and slag residues, physical, chemical, and biotechnological separation methods are discussed in detail along with dominant affecting factors. The paper includes also concluding remarks and highlights the most promising trends and limitations thereby providing suggestions for future research. [Display omitted] [ABSTRACT FROM AUTHOR]

The presence of suspended contaminants in water and wastewater, such as algae, colloids, fats and oil, necessitates the use of systems such as dissolved air flotation (DAF) for their removal. In the current study, a novel setup has been proposed for bubble enhancement. An industrial scale (pilot) DAF system was tested at saturator pressures of 3–7 atm and flow rates of 5–20 L/min in three different configurations, namely, empty, packed, and the innovative two-stage (TS) configuration. In the TS system, after the nucleation of micro bubbles, the water is returned to the saturator to undergo pressurization for a second time before it is passed through the nozzle once more and is released. The results show that the highest volume of released air as well as the smallest microbubbles are seen in the TS configuration, followed by packed mode, with the empty configuration showing the least favourable results. Moreover, the bubbles produced at the lowest residence time and pressure (3 atm) with the novel setup are better than the bubbles produced by the standard configuration, even with pressures as high as 7 atm. Thus, the novel TS setup can allow for significantly lower energy requirements and lower capital costs. For real-world application of the TS system, the feed for the saturator could be extracted from within or near the contact zone, i.e. where the bubbles are released in the DAF tank. [ABSTRACT FROM AUTHOR]

Spent automobile catalysts are the most important secondary resource for platinum group metals (PGMs), and their recycling is essential not only to ensure a steady supply of PGMs but also to preserve the natural environment. However, several factors limit the efficiency of PGM recovery in current recycling processes. Specifically, PGMs represent a small proportion of the entire catalyst and are difficult to dissolve in aqueous solutions for subsequent separation. In recent decades, multiple technologies have been developed to make the recycling of PGMs more efficient and environmentally-friendly. Herein, we introduce the typical industrial processes for recovering PGMs from spent catalysts, along with established and emerging trends in the technological development of PGM recycling. Furthermore, we review novel recycling techniques for converting PGMs in spent catalysts into more soluble states and/or physically concentrating PGMs from spent catalysts. [ABSTRACT FROM AUTHOR]

This study reports the design and development of microbial fuel cell (MFC) assisted floating wetlands and compares treatment removal performance with a normal (without electrodes) floating wetland. Both types of floating wetlands were planted with Phragmites plant and evaluated for real municipal wastewater treatment. The effective volume of each floating wetland was 0.5 m3. The floating wetlands were operated under variable hydraulic load rates, i.e., 20 and 60 mm/day. Mean 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammoniacal nitrogen (NH4-N), total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), and coliform removal percentages ranged between 71 and 96%, 72 and 94%, 62 and 86%, 58 and 75%, 82 and 97%, 64 and 92%, and 72 and 93%, respectively within the normal and electrode-assisted MFC integrated floating wetlands. The electrode-integrated floating wetlands showed better pollutant removal performance than the normal system under unstable input pollutant loading conditions. Nitrogen and organic matter removals were achieved through both electrochemically active and inactive microbial removal routes. Physical separation processes, such as filtration and sedimentation, contributed to phosphorus, solids, and coliform removal. Plant uptake contributed to micro-scale nitrogen (≤ 1%) and phosphorus (≤ 0.1%) removal. Increment of hydraulic/pollutant load improved organic removal but decreased nutrient removal performance of the normal, electrode-integrated floating wetlands. The electrode-integrated floating wetlands produced power densities ranging between 0.7 and 1.4 mW/m3, and 0.2 and 2.3 mW/m3 during lower, upper input loading ranges, respectively. Bioenergy production of the electrode-integrated floating wetlands varied within the two operational periods due to a wider range of electrochemically inactive microbial populations in real wastewater that interfered with electrochemical organic matter oxidation. The positioning difference of the anode electrodes was a significant factor that improved pollutant removal within the electrode-integrated floating wetlands compared to the other variable, i.e., anode electrodes surface area. [ABSTRACT FROM AUTHOR]

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Recent natural disasters, such as typhoons in South Korea and other countries around the globe, have resulted in loss of human life and damage to property, often causing contamination of nearby soil environments. This study focused on the emergency recovery of soil contaminated by heavy metals following a disaster such as typhoon flooding by applying a soil washing technique that used high-pressure water rather than chemical cleaning agents. Artificially contaminated soil containing 700 mg/kg Cu, 530 mg/kg Pb and 900 mg/kg Zn, was used. All three metals were present at levels higher than the Korean Warning Standards (500 mg/kg Cu, 400 mg/kg Pb, 600 mg/kg Zn) for region 2 (miscellaneous area). A high-pressure soil washing device was designed to treat 0.6 tons/h and optimal treatment was sought for varying levels of pressure (1, 3, 5 MPa), solid to liquid ratios (S/L) (1:1, 1:3, 1:5), and number of washing cycles (1, 2, 3). The high-pressure soil washing results showed that a 5 MPa washing pressure, 1:1 solid-liquid ratio, and one washing cycle were the optimum conditions to generate the highest heavy metal removal rates. Under optimal conditions, high-pressure soil washing attained removal efficiencies of Cu (37.7%), Pb (36.6%), and Zn (45.1%), and the residual concentrations of heavy metals in the remediated soil satisfied the Korean Warning Standard (Region 2). A comparison of the changes in particle size showed that after high-pressure washing, the mass fraction of coarse sand (CS, 2–0.42 mm) decreased by 23.3%, while that of fine sand (FS, 0.42–0.074 mm), silt, and clay (SC, <0.074 mm) increased by 4.2% and 19.1%, respectively. In addition, 31.1–34.6% of the CS heavy metal mass loading shifted to FS and SC fractions after washing. A comparative analysis of the soil surface morphology before and after washing using scanning electron microscopy (SEM) showed that the particles in the remediated soil became noticeably cleaner after high-pressure washing. This study demonstrated the feasibility of emergency recovery of heavy metal-contaminated soil using high-pressure washing without a chemical cleaning agent. [ABSTRACT FROM AUTHOR]

The Ganges-Brahmaputra river system at the Bengal Basin carries large amounts of sediments on the way to finally deposit at the Bay of Bengal. Those river-transported sediments form bar deposits during dry season in many areas of Bangladesh and accumulate economic mineral depositions at suitable geological environments. Dredging is a must for most of those rivers for proper navigation, as well as protecting bank erosion, which generates millions of tons of waste sand. The dredged materials from river beds are mostly composed of silicate minerals, especially quartz and feldspar along with several dark colored heavy minerals. Like the industrial processing of heavy minerals from bulk sands, various physical separation techniques can be utilized for the beneficiation of silica from those river-born silicate minerals in dredged sands. Those silica have been successfully upgraded to near-glass sand grade in the laboratory, however, they have yet to be utilized for any kind of commercial venture. The present study attempts characterization of several river sands through physical separation and laboratory analysis. The upgraded silica was successfully compared with several quality glass sands and laboratory production of glasses. This experimental production of glass from upgraded silica could potentially be economical considering its industrial application with positive environmental consequences through minimizing the dredging cost, increasing the navigability of the river and ecological balance along the flood plain.

Critical metallic elements in coal gangue have great utilization potential, especially due to the current shortage of these metals. This paper focused on examining the feasibility of physical separation (screening and float-sink tests) and calcination treatment for the enrichment of critical elements (Li, Ga, and rare earth elements plus yttrium (REY)) from coal gangue. The impacts of these enrichment methods on the acid leaching recovery of these elements were then studied. Screening tests indicated that Li and Ga were enriched in >0.125 mm size fraction and the content of REY was highest in <75 μm size fraction. Float-sink tests showed that high-density fractions were enriched in Li and Ga, and low-density fractions were enriched in REY. Physical separation cannot significantly improve the leaching rate of Li, Ga, and REY. Notably, Li, Ga, and REY were enriched significantly, and their acid leaching recoveries were increased by 54~68% after calcination under 400 °C. Sequential chemical extraction tests showed that the majority of insoluble Li, Ga, and REY was converted into soluble forms at the above temperature, which is attributed to the formation of amorphous metakaolinite and the decomposition of organic matter. Based on the results, a conceptually combined flowsheet was proposed for the extraction of Li and Ga from coal gangue. [ABSTRACT FROM AUTHOR]

In this study, a combination of physical and chemical separation processes was used to recover the metallic components of red mud. At first, the impact of carbothermal reduction on magnetic separation of iron was studied. Low magnetic properties of iron minerals resulted in insignificant separation of iron from other components in the non-carbothermally reduced sample. Various carbothermal reduction parameters were optimized to maximize iron separation from other components. The optimum conditions were found T = 1350 °C, t = 120 min, coal/red mud ratio of 3, reaction time of 120 min, and the soda ash/red mud ratio of 0.2. Under the optimum condition, the iron recovery of the magnetic product was observed 91% with 81% Fe content, while the non-magnetic product has contained 90% of Ti and Al and 80% of rare earth elements (REEs). Following the physical separation of iron, the chemical separation of remaining red mud components was investigated using leaching with sulfuric, hydrochloric, and nitric acids. The leaching experiments were performed on two samples, treated red mud with carbothermal reduction and an untreated sample. The untreated sample had a higher dissolution efficiency for Ti and REEs than the carbothermally reduced sample. Different dissolution behavior of the red mud components was explained by samples' mineralogy. In the end, considering the obtained results, various scenarios for the recovery of red mud components were evaluated from technical and environmental aspects. [ABSTRACT FROM AUTHOR]

Oily wastewater has been recognized as a threat to the environment due to its hazardous nature and it can negatively affect the ecosystem, and threaten wildlife and human health. Physical, chemical, and biological technologies demonstrated a mixed performance in oily wastewater treatment, and, therefore, a proper treatment technology for oily wastewater needs to be addressed. Membrane filtration using a hollow fiber (HF) membrane is a promising alternative to remove emulsified oil from oily wastewater. This review discusses different sources of oily wastewater, various treatment methods, and membrane technology. The assessment has been focused on the parameters affecting HF membrane performance and applications of HF membrane-based technology to treat oily wastewater. This review paper reveals that HF membrane filtration systems have been previously used for the treatment of oily wastewater in bench-scale studies and few pilot-scale applications, which proved to be favorable in the treatment of recalcitrant wastewater containing oil and high salinity. Limitations associated with membrane fouling and the reduction of membrane permeability and membrane lifespan can be tackled and alleviated through modifying membrane chemistry and adjusting operational parameters. The compilation of studies showed that a low food/microorganism (F/M) ratio, long solid retention time (SRT) with high sludge age, long hydraulic retention time (HRT), and moderate aeration were the preferred operational parameters when treating oily wastewater. Based on this review, future studies should focus on optimizing the hydrodynamic conditions of the HF system, the commercialization of modified HF membranes, and the utilization of green technology in HF membrane construction to broaden HF membrane technology applications. [ABSTRACT FROM AUTHOR]

The Ganges-Brahmaputra river system at the Bengal Basin carries large amounts of sediments on the way to finally deposit at the Bay of Bengal. Those river - transported sediments form bar deposits during dry season in many areas of Bangladesh and accumulate economic mineral depositions at suitable geological environments. Dredging is a must for most of those rivers for proper navigation, as well as protecting bank erosion, which generates millions of tons of waste sand. The dredged materials from river beds are mostly composed of silicate minerals, especially quartz and feldspar along with several dark colored heavy minerals. Like the industrial processing of heavy minerals from bulk sands, various physical separation techniques can be utilized for the beneficiation of silica from those river-born silicate minerals in dredged sands. Those silica have been successfully upgraded to near-glass sand grade in the laboratory, however, they have yet to be utilized for any kind of commercial venture. The present study attempts characterization of several river sands through physical separation and laboratory analysis. The upgraded silica was successfully compared with several quality glass sands and laboratory production of glasses. This experimental production of glass from upgraded silica could potentially be economical considering its industrial application with positive environmental consequences through minimizing the dredging cost, increasing the navigability of the river and ecological balance along the flood plain. [ABSTRACT FROM AUTHOR]

With the rapid population growth, economic development, and technological progress around the world today, energy consumption levels are becoming increasingly huge. Most of the energy consumed comes from coal, oil, natural gas, and other primary energy sources that lead to the greenhouse effect, acid rain, photochemical smog, and other environment problems. Therefore, the identification of greener energy resources has become humanity’s great challenge. To reduce the use of primary energy sources, new types of energy have been proposed that are associated with decreased environmental pollution. However, these new energy sources typically require effective storage equipment to facilitate the use of solar, wind or water-driven energy. Lithium-ion batteries (LIBs) were developed to store electrical energy, and due to their unique advantages, today they are widely used in portable devices, electric vehicles, and all kinds of electronic equipment. The advantages of LIBs include a high specific capacity, good cycle performance, and long lifespan. Although life on Earth is greener by the use of LIBs, with the rapidly increasing energy consumption, more spent LIBs are being produced, which contain a range of valuable metals (Cu, Al, Co, Mn, Ni, Li) and harmful substances (HF, organic substances). If these materials are not treated properly, much harm will result to both human beings and the natural environment, and this would also be a great waste of valuable metals. The recovery of spent LIBs has become a research hotspot among the scientific and business communities. To support the discovery of new methods and concepts in the recovery of spent LIBs, in this paper, we reviewed the various methods available and discussed their advantages and disadvantages in detail. Based on this review, we consider the approach that uses a combination of chemical and physical technologies for the recovery of spent LIBs to be the most promising.

Impurities, such as copper and tin, have been identified as barriers limiting the use of recycled steel scrap for producing certain grades of steel product. Their accumulation during the whole recycling process could induce detrimental effects on the surface quality of downstream steel products, resulting from the formation and penetration of Cu-enriched liquid phase into grain boundaries, which would appear at 0.1wt% Cu content or above during hot working. In order to eliminate such detrimental effects, impurity removal methods have been researched considering the physical separation and chemical treatment at different stages of steel scrap recycling. For physical separation, apart from regular shredding and magnetic separation, common types of sensor-based sorting technology are discussed referring to the feasibility and efficiency. For chemical treatment, different technologies are introduced and classified according to the existent state of steel scrap during the removing process. As a result, in this review, possibilities and limitations of these methods have been presented and evaluated based on their removal mechanism to weigh their applicability. It becomes evident that sensor-based sortation would be feasible for impurity removal if specific physical or chemical characteristics can be identified and applied to distinguish impurities from Fe shreds. Considering the chemical treatment, most of the reviewed technologies were explored with laboratory scale, demonstrating limited industrial applicability due to the involving either high temperature or vacuum or complex process. [ABSTRACT FROM AUTHOR]

Recent natural disasters, such as typhoons in South Korea and other countries around the globe, have resulted in loss of human life and damage to property, often causing contamination of nearby soil environments. This study focused on the emergency recovery of soil contaminated by heavy metals following a disaster such as typhoon flooding by applying a soil washing technique that used high-pressure water rather than chemical cleaning agents. Artificially contaminated soil containing 700 mg/kg Cu, 530 mg/kg Pb and 900 mg/kg Zn, was used. All three metals were present at levels higher than the Korean Warning Standards (500 mg/kg Cu, 400 mg/kg Pb, 600 mg/kg Zn) for region 2 (miscellaneous area). A high-pressure soil washing device was designed to treat 0.6 tons/h and optimal treatment was sought for varying levels of pressure (1, 3, 5 MPa), solid to liquid ratios (S/L) (1:1, 1:3, 1:5), and number of washing cycles (1, 2, 3). The high-pressure soil washing results showed that a 5 MPa washing pressure, 1:1 solid-liquid ratio, and one washing cycle were the optimum conditions to generate the highest heavy metal removal rates. Under optimal conditions, high-pressure soil washing attained removal efficiencies of Cu (37.7%), Pb (36.6%), and Zn (45.1%), and the residual concentrations of heavy metals in the remediated soil satisfied the Korean Warning Standard (Region 2). A comparison of the changes in particle size showed that after high-pressure washing, the mass fraction of coarse sand (CS, 2–0.42 mm) decreased by 23.3%, while that of fine sand (FS, 0.42–0.074 mm), silt, and clay (SC,

Oily wastewater has been recognized as a threat to the environment due to its hazardous nature and it can negatively affect the ecosystem, and threaten wildlife and human health. Physical, chemical, and biological technologies demonstrated a mixed performance in oily wastewater treatment, and, therefore, a proper treatment technology for oily wastewater needs to be addressed. Membrane filtration using a hollow fiber (HF) membrane is a promising alternative to remove emulsified oil from oily wastewater. This review discusses different sources of oily wastewater, various treatment methods, and membrane technology. The assessment has been focused on the parameters affecting HF membrane performance and applications of HF membrane-based technology to treat oily wastewater. This review paper reveals that HF membrane filtration systems have been previously used for the treatment of oily wastewater in bench-scale studies and few pilot-scale applications, which proved to be favorable in the treatment of recalcitrant wastewater containing oil and high salinity. Limitations associated with membrane fouling and the reduction of membrane permeability and membrane lifespan can be tackled and alleviated through modifying membrane chemistry and adjusting operational parameters. The compilation of studies showed that a low food/microorganism (F/M) ratio, long solid retention time (SRT) with high sludge age, long hydraulic retention time (HRT), and moderate aeration were the preferred operational parameters when treating oily wastewater. Based on this review, future studies should focus on optimizing the hydrodynamic conditions of the HF system, the commercialization of modified HF membranes, and the utilization of green technology in HF membrane construction to broaden HF membrane technology applications.

Spent automobile catalysts are the most important secondary resource for platinum group metals (PGMs), and their recycling is essential not only to ensure a steady supply of PGMs but also to preserve the natural environment. However, several factors limit the efficiency of PGM recovery in current recycling processes. Specifically, PGMs represent a small proportion of the entire catalyst and are difficult to dissolve in aqueous solutions for subsequent separation. In recent decades, multiple technologies have been developed to make the recycling of PGMs more efficient and environment-friendly. Herein, we introduce the typical industrial processes for recovering PGMs from spent catalysts as well as established and emerging trends in the technological development of PGM recycling. Furthermore, we review novel recycling techniques for converting PGMs in spent catalysts into more soluble states and/or physically concentrating PGMs from spent catalysts. [ABSTRACT FROM AUTHOR]

Revalorization of mining residues is of central concerns to the mining industry and the environment. Specifically, environmental management of residual products from the exploitation of chrysotile in the Thetford Mines region is one of the government concerns in Quebec and Canada. This work uses mining wastes in a second resource generation for production of magnesium from cheap and health-friendly mineral sources; the goal being to produce chrysotile-depleted pre-concentrates for a use as precursors in the leach off extraction of magnesium. The concentration of lizardite/antigorite from chrysotile containing serpentine rock mine tailings originating from the Carey Mine site in East-Broughton (Québec) was carried out using a suite of hydrocyclone, settling/decantation and magnetic separations. Four size classes of the mining residue, namely (−3150,+1580), (−1580, +600), (−600, +300) and (−300, +150) μm, were tested with an aim to reduce the level of objectionable asbestos fibers to allow access to the safer Mg-bearing minerals contained in the mine waste sources. The asbestos fibers clean-up consisted of subjecting the sieved fractions to two hydrocyclone steps, six settling/decantation steps and two magnetic separation steps. The best results were achieved when the hydrocyclone separators led to Mg recovery of 85% (±4) for the coarsest size fraction size. Both hydrocyclone underflow streams underwent settling/decantation separations. The settling tests lasted 30 min and led to Mg recoveries of 82.5% (±1.8) of Mg in the ultimate concentrate. SEM characterizations revealed that it was possible to reduce substantially the amount of chrysotile fibers to render the coarse-sized fraction in the mining waste usable while significantly lowering the health risk of the fibers. A two-step magnetic separation was applied to the final settling/decantation underflow to remove magnetic minerals such as magnetite from the lizardite/antigorite concentrate. The final quasi-non-magnetic chrysotile-depleted lizardite/antigorite concentrate allowed sample recovery of 62.5% (±0.9) wt. of Mg. These preliminary results are intended as a first compulsory step in support of viable restoration and sustainable development scenarios for the Thetford Mines mining sites as second-breath sources for valuable magnesium. [ABSTRACT FROM AUTHOR]

This study focuses on the recovery of valuable metals, such as gold, silver, and copper, from the printed circuit boards of waste computers, using physical separation followed by leaching methods. Characterization studies revealed that resins and glass fibers were attached as grain together with base and precious metals. A hammer mill was employed as a second stage crusher to disintegrate the different components of the printed circuit board, thus improving the selectivity and recovery of metals. Separation studies using a laboratory-scale shaking table showed that 33% of the feed was removed as a light product and 96.8% of Au, 96.7% of Ag, and 97.7% of Cu were recovered in heavy fraction. Leaching the light fraction using 3 M H2SO4 and 0.33 M HNO3 at 80°C for two h resulted in greater than 90% extraction of Cu. Au and Ag were dissolved at room temperature with a leaching solution of 0.2 M S2O32-, 0.02 M CuSO4, and 0.2 M NH3.H2O, which provided a recovery of more than 59% of Au and 98% of Ag within eight h. Direct leaching tests using optimized conditions were also implemented on the crushed sample, and 45% of Au, 87.6% of Ag, and 70.8% of Cu were extracted. [ABSTRACT FROM AUTHOR]

The volume of spent photovoltaic (PV) panels is expected to grow exponentially in future decades. Substantial material resources such as silver (Ag), copper (Cu), aluminum (Al), silicon (Si), and glass can potentially be recovered from silicon-based PV panels. In this paper, we targeted the recovery of Cu and Ag from a cell sheet separated to a glass panel from a spent PV panel. The technical feasibility of a novel electrical dismantling method was experimentally studied. This method employed a pulsed power technology that releases high energy in a short time. It allowed a selective separation of the Cu/Ag wires from the sheet once per discharge in water. The experimental results indicated that 95.6% of the total Cu and 17.2% of the total Ag in the sample were successfully separated from the cell sheet using a 3.5-kJ capacitor bank circuit. Moreover, 3.66% of the total Si in the sample was contaminated by the separated Cu/Ag particles from the cell sheet, mainly by shockwaves generated by plasma expansion, and some of them formed a compound with Cu and Ag by eutectic melting, resulting in low liberation. At the lower energy of 3.5 kJ, eutectic melting of Cu and Ag with Si was more suppressed than 4.6 kJ, and 94.3% of Cu and 77.5% of Ag in the separated particles were liberated, which would be acceptable for further wet gravity and/or shape separation of Cu and Ag. [ABSTRACT FROM AUTHOR]

In this study, the beneficiation performance of chrome from the high carbon ferrochrome slag (HCFS) was evaluated. The mineralogical characteristics of HCFS was investigated first, and then HCFS was treated by magnetic separation, gravity separation, magnetic-gravity combined separation, and gravity separation after grinding respectively, to recover the Cr2O3. Finally, the Fuerstenau upgrading curves were used to evaluate the separation performance of different separation processes. The results indicated that the gravity separation process with a proper grinding condition gave the optimum beneficiation performance. A concentrate product with 30.18% Cr2O3 grade and 22.52% recovery was obtained from the HCFS. [ABSTRACT FROM AUTHOR]

This study investigated the suitability of mechanical pre-treatment methods (mechanical abrasion and treatments of heat, laser, and plasma) together with a hydrometallurgical process comprising leaching and cementation for recovering indium from used LCD screens. With mechanical abrasion pre-treatment, 96.2% of indium was recovered and black mass with an indium content of 15.6 wt percent was obtained. Following the mechanical recovery, sulfuric acid leaching was used to produce leachates with an indium purity ranging from 86.3 to 98.0% with an 88.7–100% yield for indium. Indium was recovered from the leachate by cementation with zinc powder, but also the impurity metals were cemented. The suggested mechanical pre-treatment involving the indium recovery process was seen as a viable option since it dramatically reduces the mass fed to the hydrometallurgical purification process (by roughly a factor of 1000), and up to 97.1% pure indium product can be obtained with a simplified process. The purity of the indium product can be further increased by additional purification steps. Image 1 • Novel pre-treatment methods for recovering indium from LCD screens are discussed • Mechanical grinding recovered indium with 96.16% yield • Purity of indium in the resulting black mass was 86–98% • Indium was further recovered from the black mass by acid leaching and cementation • Laser treatment vaporized the indium tin oxide film totally from the LCD surface [ABSTRACT FROM AUTHOR]

The removal of multiple-ring aromatics from the petroleum fractions in general and lubricating oil feedstocks particularly have been conventionally done either by solvent extraction or hydrotreatment processes. Both techniques however, they could attain reasonable rates in removing aromatic and sulfur compounds, they suffered from certain drawbacks. Specifically, the elevated operating costs of both routes due to the long operational time and its dependent massive energy consumption are a big issue. In an attempt to overcome such restrictions, the current research study introduces a novel approach in the removal of condensed aromatic compounds by using microwave supported solvent-extraction process. The process of microwave-assisted extraction (MAE) was performed in parallel to the conventional extraction process to precisely compare the features of the obtained products out of each of process. Time of exposing the extraction system to the microwave radiation, the intensity of radiation power and solvent to feed ratio are the main investigated parameters during the microwave-assisted extraction. Promising results have been detected at the end of the presented research study. Extreme reduction in the operational time by applying microwave technology, 15 min, compared to the conventional extraction (90 min) was successfully attained. This reduction could be associated with extra-low energy consumption in the case of microwave-assisted extraction (MAE) in comparison to the conventional route. Specifically, the energy consumption was reduced by 99.75% than that in the case of conventional solvent extraction. In addition, an enhancement in the percentage of aromatics removal, 12.5%, was achieved in the microwave-assisted extraction compared to the conventional route. Furthermore, the sulfur removal has come up to nearly 60% in the case of MAE while it was about 50% for the conventional solvent extraction process. • Microwave assisted extraction (MAE) is introduced as a novel refining technique. • New engineering design for an extraction unit is presented in this study. • Effect of MAE on aromatic and sulfur compounds removal was studied. • Investigating the removal of carcinogenic compounds was carried out. • Comparison between conventional extraction and MAE is presented. [ABSTRACT FROM AUTHOR]

• A physical-chemical treatment scheme for mobile phone recycling was evaluated. • Au was separated from base metals and recovered in coarse fraction by jig separation. • Au was recovered by hybrid jig and flotation in fine fractions. • Au extraction increased by 15-fold with physical pretreatments. As technology advances, consumers are looking to buy new phones. This phenomenon leads to decrease in life-cycle of mobile phones (ca. 2–3 years), resulting in increase of waste mobile phones. In waste mobile phones, it contains various components including display unit, battery, cases, and printed circuit boards (PCBs). PCBs alone contain variety of materials such as gold (Au), copper (Cu), and iron (Fe) as well as aluminum (Al) with plastics, which causes difficulty in recycling. The coexistence of Cu and Al in crushed mobile phones has been recently reported to cause very low Au extraction efficiency in ammonium thiosulfate medium due primarily to enhanced re-deposition of extracted Au ions via galvanically induced cementation. To limit this antagonistic effect of Cu and Al coexistence on Au extraction, Au-containing components were separated from Cu- and/or Al-bearing parts using a two-step crushing approach in tandem with various physical separation techniques (i.e. jig, hybrid jig, magnetic separation, flotation, and sink-float separation) that were applied on appropriate size fractions. The results showed that over 96% of PCBs, the primary Au-containing material in mobile phones, were recovered after jig separation. These concentrated PCBs were collected and further crushed to liberate Au-containing parts and then treated by diverse physical separation techniques such as magnetic separation, jig separation, hybrid jig separation, flotation, and sink-float separation depending on the crushed particle sizes. Ammonium thiosulfate leaching of the mixed Au-concentrated products from various physical pretreatment techniques showed that Au extraction improved by about 15-fold, indicating that the physical separation scheme proposed in this study is very promising. [ABSTRACT FROM AUTHOR]

Abstract: This study mainly examines the effects of combined sieving and washing process by remediation equipment for heavy metal decontamination at a historically contaminated site. The laboratory results showed that the optimum parameters for the washing process were pH 2, 30 °C, and 10:1 liquid/soil ratio. The results from field remediation proved that the overall removal of arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn) could reach 37.1–51.1%, 44.3–78.1%, 21.2–64.3% and 29.2–59.4%, respectively, in various particle fractions. To prevent secondary pollution, coagulating sedimentation and adsorption processes were used to treat the wastewater, with removal rates of 99.4% As, 99.9% Cd, 93.5% Pb and 99.1% Zn. A composite material was adopted to solidify the fine clay that was enriched with a large amount of metals and form it into non-fired bricks. As seen from the mass balance, 23 kg of stone and 140 kg of gravel were separated, and 367 kg of fine clay with a 45% soil moisture content was treated by solidification and stabilization, achieving a volume reduction of approximately 36.5%. In conclusion, the presented method can be applied to heavy-metal-contaminated sites to greatly reduce the amount of pollutants in soils while at the same time minimizing the environmental risk. Graphical abstract Image 1 Highlights • Combined sieving and washing successfully facilitated metals extraction and volume reduction. • A mobile and automated equipment for soil remediation was manufactured and successfully applied. • Technological parameters of soil washing for different soil particles were optimized. • The removal efficiency can be enhanced by increasing the washing cycles. • Secured disposal was conducted for wastewater and sludge generated from the washing process. [ABSTRACT FROM AUTHOR]

Nanostructured TiO2/ZrO2 composite membranes with varying compositions were obtained by sol-gel technique. The influence of 0-30 mol% zirconia doping on microstructure, water permeability, photocatalytic and physical separation properties, removal of methyl violet of textile industries wastewater and thermal and mechanical stability of titania/zirconia composite membranes was described. Firstly, alumina supports were coated with TiO2 intermediate layers using the colloidal sol-gel route. The TiO2/ZrO2 composite sols were prepared via a polymeric sol-gel method and dip-coated on TiO2 intermediate layer. The samples were characterized by DLS, TG-DTA, XRD, FTIR, BET-BJH, UV-visible, SEM, TEM and AFM. It was shown that zirconia retards the phase transformation of anatase to rutile until at least 700 °C. The minimum pore size and maximum surface area obtained were 1.2 nm and 153 m2/g, respectively, attributed to the sample with 20 mol% zirconia. The mechanical strength of titania membranes was significantly improved by addition of zirconia. The most methyl violet removal efficiency obtained, with and without UV-irradiation, is 80.8 and 72.6%, respectively, attributed to the sample with 20 mol% zirconia. [ABSTRACT FROM AUTHOR]

The paper exploits the content of a very important document, found in the National Archives of the Republic of Moldova. Its valuable information enhances the insight into the private life of the late eighteenth century. The case study – which is the subject of the article - is based on a divorce act of 1795. It shows not only the law of the time, but also the particularities of the social and legal position held by women. In other words, this article identifies new aspects of private life, which can be analyzed both in terms of mentalities and that of gender relations.

The article makes an effort in consolidating the developments in the field of advanced gravity separation techniques for processing fine particles over the last few decades. The application potentials of various unit operations and the influence of process variables and feed characteristics on the process performance are identified. Fundamentals of advanced gravity separators are discussed from theoretical and applied perspectives. Comparative analyses of various related unit operations are incorporated including the advantages and short falls of different advanced gravity separation techniques. A general guideline is presented that will help designing new mineral processing flow sheets with better efficiency indices. [ABSTRACT FROM AUTHOR]

Nickel-metal hydride (NiMH) batteries contain high amount of industrial metals, especially iron, nickel, cobalt and rare earth elements. Although the battery waste is a considerable secondary source for metal and chemical industries, a recycling process requires a suitable pretreatment method before proceeding with recovery step to reclaim all valuable elements. In this study, AA- and AAA-type spent NiMH batteries were ground and then sieved for size measurement and classification. Chemical composition of the ground battery black mass and sorted six different size fractions were determined by an analytical technique. Crystal structures of the samples were analyzed by X-ray diffraction. Results show that after mechanical treatment, almost 87 wt% of the spent NiMH batteries are suitable for further recycling steps. Size classification by sieving enriched the iron content of the samples in the coarse fraction which is bigger than 0.25 mm. On the other hand, the amounts of nickel and rare earth elements increased by decreasing sample size, and concentrated in the finer fractions. Anode and cathode active materials that are hydrogen storage alloy and nickel hydroxide were mainly collected in finer size fraction of the battery black mass. [ABSTRACT FROM AUTHOR]

The main goal of the present study is synthesis, characterization and performance evaluation of an optimized photocatalytic ceramic membrane for wastewater treatment. It consists of three layers including alumina (Al 2 O 3 ) macroporous support, colloidal titania (TiO 2 ) mesoporous intermediate layer and polymeric TiO 2 mesoporous top layer in order to obtain a pore gradient from the support through the top layer of membrane. The colloidal and polymeric TiO 2 layers were prepared via the sol-gel method and coated using sol dip-coating approach. In order to optimize the membrane, physical separation and photocatalytic degradation capabilities of each colloidal and polymeric layer as a function of time were evaluated using Rhodamine B (RhB) aqueous solution. Thus, optimum coating number of intermediate layer and top layer were determined. Also, the performance of the optimized membrane was investigated via oily wastewater treatment using crude oil and water emulsion. Based on the performance results, two consequence colloidal layers and one polymeric layer were considered as the optimum layer number. Also, RhB photocatalytic degradation was 24.7% and RhB physical separation and permeation flux were 40.4% and 25.7 kg m −2 h −1 , respectively. Furthermore, based on the oily wastewater treatment experiments, permeation flux and chemical oxygen demand (COD) rejection at the best-operating conditions (pressure of 5 bar, the temperature of 30 °C and cross flow of 600 l h −1 ) were 29.1 kg m −2 h −1 and 78.4%, respectively. The prepared membrane was found efficient and exhibited high industrial potential due to its multifunctional capability and thus can be employed as an advanced material for wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Numerous studies on microplastics (MPs; Ø < 5 mm) in the aquatic environment have been published, but knowledge about the occurrence and ecological risks of MPs is limited. This is in part because current data on the distribution of MPs are comparable only to a limited extent, due to the many different methods of investigation. In addition, sample preparation is often difficult such that standard procedures are lacking. The aim of this work was to simplify the preparation of different kinds of MP samples. Our method makes use of the electrostatic behavior of plastic particles to facilitate their separation from sample matter, with up to 99% of the original sample mass removed without any loss of MPs. To determine the efficacy of this approach, four different materials (quartz sand, freshwater suspended particulate matter, freshwater sediment, and beach sand) were spiked with MPs (size: 0.063–5 mm from the seven most common types of plastics, one bioplastic type, polyethylene fibers, and tire wear. A modified electrostatic metal/plastic separator was used to reduce the sample mass and concentrate the plastics based on their physical separation. The recovery achieved with this method was as high as nearly 100% for each type of material. The method was then tested on plastic particles of different shapes and types isolated from the Rhine River. These were successfully electroseparated from the four materials, which demonstrated the utility of this method. Its advantages include the simplified handling and preparation of different field samples as well as a much shorter processing time, because after the last separation step there is hardly any biological material remaining in the sample fraction. [ABSTRACT FROM AUTHOR]