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By P. Condori

In spite of the importance of the slurry transport and discharge in autogenous and semiautogen-ous (AG/SAG) mills, it is evident that a more comprehensive and useful model is still required. Semi-empirical models used up to now have many limitations and cannot be used beyond the ranges in which they were developed. The breakage of particles as they are transported along a mill com-plicates the experimental analysis and the modelling of the transport process within the mill. The interaction of the grate discharge and the pulp lifters, with the added issue of backflow from the pulp chamber into the mill, makes the discharge modelling process difficult. In order to overcome these difficulties, a mechanistic approach has been applied. The general transport and discharge model was subdivided into four independent models: Flow through the charge, flow through the grate, flow in the pulp lifter, and flow-back. This paper gives an overall description of the modelling approach and discusses in particular the modelling of transport of fluids through the charge. In order to evaluate and calibrate the model, experimental work was carried out. To evaluate the gradient pressure under different conditions of charge packing and flow rate, a specialised experimental rig with a highly sensitive pressure gauge was used. Preliminary results identify the differences of the charge and grate on the restriction of flow. The existence of a dynamic voidage in our particular system was more evident and as a result, a semi-empirical correlation for the voidage was developed. In general, results show that the me-chanistic model derived from Ergun?s equation for flow through a packed bed can be satisfactorily adapted.

Jan 1, 2014

By F. Z. Dong

The paper is mainly about a study on the techniques of separating iron from pyrite cinder of a certain sulfuric acid plant in Shandong province. The main components of the cinder are Fe2O3 and SiO2, and the degree of liberation of iron mineral and gangue is very high. So the iron concentrate with higher degree of iron and lower grade of silicon and sulfur can be achieved by reverse flotation. The iron grade of the concentrate reaches 63% and the recovery of iron is no less than 63%. And the most important influencing factor of the flotation is the temperature of the pulp. A better guideline can be achieved by magnetic separation. The cinder is magnetizing roasted for 15 minutes with temperature of 800?, and the concentrate with the iron grade 64%, sulfur grade 0.2% and iron recovery 85% can be obtained by two stage magnetic separation. A rotary kiln has been built to deal with the pyrite cinder, and the result of the industrial magnetizing experiment and magnetic separation is satisfying.

Jan 1, 2014

By C. R. Mambote

Vanadium is an important metal that is used mainly in ferrous and non-ferrous alloys due to the high tensile strength, hardness, fatigue resistance and corrosion resistance. Vanadium consumption in the steel industry represents about 85% of the vanadium-bearing products produced worldwide. The primary sources of the metal are patronite, roscoelite, and mottramite. Vanadium has also been produced as a by-product of the uranium production program which uses carnotite ores as a source of uranium. Vanadiferous magnetite iron ores are used for producing vanadium as well. In addition, it is known that vanadium can be recovered from the ashes of crude oil and petroleum coke. The process for treating boiler residues, fly ash and petroleum coke is similar to the process used to treat spent catalysts and ores. However, some of these materials may contain high carbon that must be removed at specific stage of the operation. Several processes are available for obtaining vanadium from fly ash, such as roasting vanadium bearing materials in the presence of sodium salt. The salt roasted calcine is subsequently leached with an alkaline or acidic solution. To obtain a cal-cine from which the vanadium can subsequently be recovered, the carbon in the source materials has to be eliminated prior to the roasting process. Other processes use the conventional hydrometallurgical route, in which fly ash is leached with sulphuric acid to obtain an impure vanadium pentoxide. The impure vanadium pentoxide is then treated with a sodium carbonate solution under atmospheric conditions to subsequently precipitate vanadium as ammonium metavanadate. Actually, the salt roasting process is the only process used commercially. In the present study, the progress in the technology of vanadium extraction from secondary materials is reviewed. The perspectives and the challenges for new process development are discussed.

Jan 1, 2014

By S. F. Kaplan, A. S. Dolotov, V. N. Kovalev

"The proportion of refractory sulphide ores and concentrates in world gold mining industry is growing every year. Pressure oxidation of these materials (in autoclave) allows to oxidize gold hosting minerals. Traces of halides and pseudohalides present in the slurry liquids contribute to formation of complex gold compounds. Sorption-active carbon present in ores leads to irreversible adsorption of complex gold compounds and their loss. The objective of the research is to study gold extraction dependence on the concentration of chloride-, cyanide- and thiocyanate-ions in the slurry liquids during pressure oxidation. Double refractory flotation concentrate of the Bakyrchik deposit was used for the testwork. The research was planned on the basis of a full factorial experimental design with additional refining experiments. Ligand concentrations (0 – 1000 mg/l Cl-, 0 – 600 mg/l CN-, 0 – 1200 mg/l of SCN-), temperature (200 – 240 °?) and retention time (1 – 6 h) were used as variables of pressure oxidation process. It was determined that sulfide minerals oxidize much faster than ""organic"" carbon. Under the conditions of T = 240 ?C, t = 2 h, sulphide sulfur oxidation was 95.6%, while ""organic"" carbon oxidation was 46.1 %. Each of the examined ligands has a significant adverse impact on gold extraction. Analysis of the experimental data demonstrated that with a high degree of confidence (R2 = 0.883) gold extraction does not depend on the ligand type, but only on its concentration and the ""organic"" carbon oxidation degree. In case of complete oxidation of ""organic"" carbon, the presence of the ligand (L = Cl-, CNS-, CN-) in the liquids at a concentration of up to 20 millimole/L does not significantly affect gold extraction. The assumption that the main factor of preg-robbing in ???-CIL treatment of double refractory concentrates is the natural ""organic"" carbon sorption-active to gold has been confirmed. INTRODUCTION In recent decades, placer gold mining has been gradually declining and hardrock gold mining, including ""refractory"" gold mining, has been growing all over the world, as well as in the Russian Federation (http://www.miningworld.ru, 2015). One of the main reasons why gold ores are refractory is gold adsorption on natural carbonaceous materials (""organic carbon""). Only a few technologies are suitable for processing such ore concentrates (a significant amount of gold is contained in refractory hardrock ore both in Russia and worldwide) (Vorob'yev-Desyatovskiy N.V., Yepifanov A.V., 2014)."

Jan 1, 2018

By N. Acarkan

Beneficiation of the pyrite concentrate of the Kastomonu-Küre (Northern Turkey) copper ore seems to be attractive due to its high Cu, Co, and Zn contents. Pyrite concentrate were used in the experimental studies. Cu, Co, and Zn were recovered from the concentrate by the sulphatizing roasting, leaching and the precipitation using H2S. Sulphatizing roasting experiments were carried out in a rotary furnace and the optimal roasting conditions were found to be at 650°C roasting temperature and 3.0 h roasting period and addition of Na2SO4 of 3 % for the concentrate containing 0.58% Cu, 0.22% Co, and 0.04% Zn. Then, the roasted product was repeatedly leached with 10 g/L H2SO4 solution. Optimal conditions were found to be 60 oC leaching temperature, 2 h leaching period, and 30% pulp density. Leaching efficiencies for Cu and Co were over 99 %. The valuable metals in the pregnant solution were selectively precipitated by H2S as sulfides. Selective precipitation of Cu, Zn, Co was achieved by adjusting the pH and the temperature of the leach solution. Final metal recoveries of 99.20% Cu, 99.40% Co, and 95.60% Zn were attained. The precipitated sulphides are marketable products. Roasting gases with their 15% SO2 content are suitable for the production of H2SO4 and the leach residues can be integrated with the iron ore processing plant as they contain 57.50 % Fe, 17.70% gangue (SiO2, CaO, etc.), 0.04% S, and 0.06% non-ferrous metals.

Jan 1, 2014

By Peter N. Holtham, Geoffrey J. Lyman, Matthew S. Brennan, Vijay Subramanian, Rui X. Rong, Tim Napier-Munn

Studies of the dense medium and classifying cyclone have been conducted using the Fluent computational fluid dynamics code. Experimental measurements of the segregation of medium in a DM cyclone by gamma-ray tomography and the performance of a novel classifying cyclone design have been used to test and interpret the 3D CFD predictions. The predictions of the CFD models were generally plausible, though more work is required to incorporate turbulent mixing of the slurry in the cyclone. The benefits of the novel cyclone design were explained by the model in terms of conditions favouring reduction of short-circuiting at the vortex finder, and the removal of the air core from the wall at the apex. Work is continuing.

Jan 1, 2003

By C. Hazotte, M. -O. Simonnot, V. Houzelot, B. Laubie, M. Guilpain, B. Jally

"More than 400 plants in the world are able to accumulate nickel (Ni) in their aerial parts at concentrations higher than 10 g per kg of dry biomass. Then, Ni can be recovered from the biomass of these hyperaccumulator plants. Agromining is a chain consisting in growing such plants and producing metal. It has been developed thanks to the combined know-how of agronomy and hydrometallurgy. Hydrometallurgical processes have been designed; two different pathways were developed: i) acid leaching of ashes after biomass combustion and ii) direct Ni water extraction after biomass grinding. Experiments with 2 species of Ni hyperaccumulators (A. murale from the Balkans and R. bengalensis from Malaysia) have shown that the first process is very robust and transposable. For the second one, the way Ni is stored in the plant has a strong influence on extraction. A. murale transformation was explored in more details from the lab scale to the pilot scale. Results proved that Ni is totally transferred into the aqueous phase after 2 hours at 90 °C. A life cycle assessment has clearly shown the environmental interest of this approach (especially by detoxifying agricultural soils). INTRODUCTION Agromining is an emerging phytotechnology aiming at recovering metals thanks to hyperaccumulating plants (van der Ent et al., 2018). These plants are able to accumulate very high concentrations of metal in their aerial parts. For example, for nickel, the hyperaccumulation threshold is 0.1%, i.e. 10 grams of metal per kilogram of dry biomass. There are some advantages to use this technology instead of conventional mining techniques: •,Treating unconventional metal resources: they can be (i) natural soils with low concentrations but also low fertility because of the metal presence (like serpentine soils for Ni) (Bani et al., 2015), (ii) mine tailings or (iii) industrial wastes (like surface treatment sludge) after soil construction (Rue, 2017);"

Jan 1, 2018

By S. M. Viduka

This paper presents a numerical investigation of solid separation in jigging device, which is a gravity separation method widely used in ore processing. Separation is recognized as being heavily dependent on fluid motion in the jig. This study explores the effects of the inlet time dependent velocity profile on jigging performance. Modelling of the liquid-solid system is performed through a combination of computational fluid dynamics (CFD) to simulate liquid flow and discrete element method (DEM) to resolve particle motion. The initial packing conditions consist of a binary-density particle system of 1130 particles each 1 cm in diameter. A variety of jigging profiles are implemented in jigging. The saw tooth pulsation profile is selected with three variations in both amplitude and frequency. The performance of each profile variant is compared in terms of solid flow patterns, separation kinetics, energy, and mean particle position. These quantitative comparisons demonstrate significant differences in the segregation rate, energy, and solid phenomena, helping find an alternative optimum operating setting for the system.

Sep 1, 2012

By S. L. Gao

Based on the differences in hardness and density of diaspore and aluminosilicate minerals which usually exist in Chinese diasporic bauxite, It is analysed that bauxite of this kind is difficult to be separated effectively by classification and normal gravity separation, and cyclonic centrifugal field was thus proposed to be carried out, in which classification can take place according to the size difference resulted from selective grinding, what?s more, the separation function according to density difference is expected to take effect at the same time, and then cyclonic separation tests for diasporic bauxite of A/S 4.39 and grinding 61.90% -0.074mm were carried out tentatively. The results showed that the accretion of feed pressure can offer strong enough centrifugal force for cyclonic separation with result that separation function according to density difference is effectively intensified, by the increasing of this parameter, underflow and overflow of A/S 7.64 and 2.18 can be processed at the same time, and the recovery of Al2O3 in underflow is 71.78%; judging by the flow ratio, the spatial locality envelope of zero vertical velocity do constringe to the vertical axis by the enlarging of diameter ratio of apex to vortex, overflow and underflow of A/S 2.08 and 6.5~7.0 can be processed by controlling this structural parameter, which is possible to offer a technological method for low-grade bauxite to de-sliming beforehand.

Jan 1, 2014

By Ljudmil S. Grigorov, Eric Forssberg, Hanumantha Rao Kota, Robert J. Pugh, Lidia B. Alexandrova

"We have used the microscopic thin balance developed by Scheludko at al. (1970) technique to study the stability and interactions within the thin film between the silica surface and air bubble with (i) a long chain C10 amine and (ii) a cationic/anionic surfactant systems consisting of mixtures of a long straight C10 chain amine with long straight chain C8, C10 and C12 sulfonates. It was found that the mixed surfactants caused lower contact angles, lower rates of the thin aqueous film rupture and longer film lifetime, compared to the pure amine system.This behavior was explained by the initial strong adsorption of positively charged interfacial complexes from the mixed surfactant system at the air/solution interface followed by adsorption at the silica interface. It was also shown that the chain length compatibility between the anionic and cationic surfactants controls the strength of the interfacial complex, determining an inhibition in the thin film rupture and dewetting of the film. The rupture mechanism was explained by an earlier established heterocoagulation mechanism between the positively charged air/solution interface and the solution/silica interface which remained negatively charged. The formation of the interfacial complex at the air/solution interface was confirmed by using surface tension data."

Jan 1, 2003

By Mohsen Hashemzadehfini

Nowadays heap leaching has become established as a mineral processing technology for treatment of some low grade minerals such as copper, gold, and zinc, etc. Heap height, particle size, leach reagent consumption, and metal recovery are four important metallurgical parameters in a hydrometallurgical process like heap leaching. This paper investigated the effects of heap height and particle size on copper recovery as well as acid consumption. Three heap heights of 2, 4 and 6 meters and two particle size fractions of less than 25.4 mm and 50.8 mm were selected as variables in the experiments. The research results showed the inverse relation between heap height and copper recovery as well as acid consumption. Under given conditions, the copper recoveries of minus 25.4 mm ore are 78.63%, 66.27% and 52.88% higher than that of minus 50.8 mm samples for the heap heights of 2, 4, and 6 m, respectively. Both copper recovery and acid consumption increase with decreasing particle size. Keywords: heap leaching, heap height, particle size, acid consumption

Sep 1, 2012

By Jochen Petersen, David G. Dixon

"Although heap leaching may be perceived as a somewhat low-tech route for the extraction of low-grade minerals, the underlying physical, chemical and biological processes are in fact extremely complex. There has been increased interest in heap leaching of sulphide minerals in recent years with the advent of controlled bio-heap leaching, and the need to mine more marginal ore deposits.A detailed investigation into the dynamics of heap leach processes has provided much insight into the underlying complexities, and has led to the development of a sophisticated modelling tool. Some of the features include mineral kinetics, particle level effects, bacterial growth, oxidation and adsorption, gas adsorption, pore diffusion, bulk advection, gas balance and heat conservation.Two case studies are presented which illustrate specific features of the model for different applications and how these have helped to identify key areas of concern. In each case the model has proved as an invaluable tool either for the improvement of existing heap leach practice or for the development and assessment of novel applications."

Jan 1, 2003

With the ambitious target of adding another 2,00,000 MW of power generation by the year 2017 in India the demand for coal is bound to grow. The non-coking coal deposits in India are characterized as high ash and difficult-to-wash coals. Quality improvement by beneficiation is almost mandatory due to MoEF notification to use <34% ash coal for all power plants except those located at pithead. Most of the coal washeries in India are based on wet process, where the coal fines are allowed to settle in thickeners. The coarser particles settle faster leaving the fine particles suspended for longer period. The dispersed fine coal particles contain some surface charge, which leads to the development of electrical repulsion between the particles, and as a result of this, the suspension becomes more stable. In order to destabilize the colloidal suspension, flocculants are usually added, so that the settling rate of the fine particles also increases. These flocculants are of cationic, anionic and non-anionic depending upon the type of charge released when dispersed in water. The flocculants may act partly for charge neutralization and partly for inter particle bridging and electrostatic patch formation. The effectiveness of any type of flocculants depends upon the molecular weight and charge density of the polymer. The paper discusses the settling behavior of non-coking coal fines suspension by using different flocculants. Keywords: floculent, coal fines, sedimentation rate, effluent

Sep 1, 2012

By Mohammad Kor, David Beattie, Agnieszka Mierczynksa-Vasilev

The selectivity of polymer adsorption in mixed mineral systems is the basis for polymer depression of gangue minerals in flotation. Effective polymer depressants not only reduce gangue mineral recovery, they also have minimal effect on the recovery of the value phase, presumably through targeted adsorption on the gangue phase, and minimal uptake on the value phase. Traditionally, polymer depressant design has been guided by single mineral phase adsorption tests, with affinity and maximum adsorbed amount determined for gangue and value phases separately. However, there is a need to determine the actual extent of adsorption on the gangue phase while in the presence of the value phase. In this work, we report on the development of in situ atomic force microscopy (AFM) imaging for determination of polymer depressant coverage and morphology on mixed mineral surfaces. Our group has previously used AFM imaging on single minerals to connect adsorbed layer characteristics with bubble-particle attachment and flotation outcomes. Two sample types were used to test the methodology: (i) a mixture of two crushed/ground minerals encased in resin; and (ii) a composite mineral sample containing macroscopic regions of three different mineral phases. The samples have been used to probe the selective uptake of two modified dextrin polymers (octenyl succinate anhydride dextrin). AFM images acquired in situ (while all surfaces are immersed in the same polymer solution) of each mineral phase have revealed the natural selectivity of the polymer for the mineral surfaces. In all cases, the polymers adsorb on the all mineral surfaces present, but to a varying extent.

Jan 1, 2014

By Y. Foucaud, C. Eswaraiah, L. Filippov

Enhanced gravity separators such as Falcon concentrator which uses additional centrifugal force, are the most common gravity concentration techniques used for fine particles processing. Hence, understanding the kinetics and separation mechanisms within these separators is of paramount interest. Recent research yielded a predictive physical model for the Falcon Ultra Fine (UF) which however does not explain some results obtained with industrial ores. This study aims to identify the mechanisms involved in Falcon UF separation with the objective of confirming or rejecting the hypotheses on which the current model is built and suggesting potential points of improvement. The Falcon UF kinetics is investigated through the processing of complex low-grade and fine-grained ores from the Altenberg tin deposit (Germany), the Tabuaço tungsten deposit (Portugal) as well as a synthetic iron ore. Saturation tests are performed on the Falcon UF by controlling the separation efficiency in terms of recovery and enrichment ratio with time or feed mass. Results show an evolution of Falcon UF performance with time in contradiction with the stationary separation hypothesis on which the physical model is based. Observation of the concentrate bed suggests the presence of erosion figures in furrows which may play locally an active role in the separation. In terms of Falcon UF separation timing, three phases can be distinguished. First, upon initial feeding of the bowl, a bed quickly grows unselectively and ultra-fine particles are ejected from the bowl until the bed reaches its final profile. Next, actual separation occurs with selective concentration of dense particles. Finally, capture sites saturate and recovery drops. The evolution of partition curves over time confirms the existence of two separation mechanisms. First, differential particles settling within the flowing film responsible for the ejection of small size particles during the whole separation cycle which is already accounted for in the physical model. The second mechanism involved may be explained by the action of lift force, neglected in the physical model, which acts preferentially on coarse particles deposited at the surface of the bed resulting in coarser particles being rejected in the tailings. Hence, the addition of a lift force component to the existing model is suggested to account for this second separation mechanism.

Jan 1, 2018

By Garren Edwards, van der Westhuizen. Andre

"Due to the depletion of easily treated coarser ores, more mineralogically complex ores with smaller valuable mineral grain sizes are treated, the means to liberate these minerals lies in grinding finer (Partyka & Yan, 2007). Grinding to these fine sizes is energy intensive, and using standard ball mills are energy inefficient at these sizes (P80 < 75µm). Therefore, stirred mills are becoming increasingly prevalent in the mineral processing industry. In order to optimize these mills, the effects and mechanisms of the significant variables need to be understood. This paper investigates a laboratory scale vertical stirred mill (Deswik mill) in an ultra fine grinding application of a South African platinum ore. The operating variables that are considered are stirrer speed, media size, media filling, and slurry density. The resulting grinding efficiencies are considered in two ways. Firstly, a statistical model is fitted to identify the effect of the significant variables on grinding efficiency, and secondly, the grinding efficiencies are also considered in terms of a stress energy model to determine whether this can partly explain the grinding mechanism in this mill. A factorial design of experiments was used on three levels for each variable, such that only linear interactions, second order interactions and two variable interactions are included in the statistical model. The results show that tip speed, media size, percent solids and mill filling are all significant to the grind, at differing energy inputs in the grinding process. The interaction effects of these variables are also dependent on the energy inputs. The results also found that the Kwade stress energy model is applicable to this mill and can be very useful to find the most efficient operating conditions for this system. The most energy efficient operating conditions in terms of mill speed and media size were typically somewhat below the standard operating conditions and it is expected that this is most probably done in order to increase the grinding rate, but at the expense of sacrificing some grinding efficiency."

Jan 1, 2014

By E. R. Bobicki

"Low-grade ultramafic nickel ores, while representing a large potential nickel resource, are difficult to process due to their serpentine content. Microwave treatment is proposed as a technique to improve the beneficiation of ultramafic nickel ores by converting the constituent serpentine to olivine. The present paper reviews the microwave heating response of ultramafic nickel ores and resultant changes in mineralogy, as well as effects on grinding and slurry rheology. Beyond nickel extraction, microwave treatment improves the mineral carbon storage capacity of ultramafic ore tailings, providing a potential source of additional revenue via the sale of carbon credits. The combined positive effects, considered in the context of the whole operation, suggest an economically viable process is possible.INTRODUCTIONAs high-grade deposits become depleted, the processing of low-grade ores has become increasingly important. One such resource is low-grade ultramafic nickel ores. While representing a large source of nickel, these ores are difficult to process due to their serpentine content. Serpentine is a phyllosilicate mineral consisting of 1:1 stacked sheets of silica tetrahedra and magnesium hydroxide octahedra. There are three primary polymorphs: lizardite (platy), antigorite (corrugated) and chrysotile (coiled, fibrous). The anisotropic nature and non-spherical morphology of serpentine particles leads to complex rheology. Suspensions of serpentine minerals, especially those of chrysotile, exhibit high viscosity and yield stress, which can have a negative effect on comminution, flotation and dewatering operations. In flotation, serpentine is known to slime-coat pentlandite, a valuable nickel mineral, and form bubble-fibre aggregates that report to the froth, reducing nickel concentrate grade and recovery. Methods used to counteract the effects of serpentine in processing include desliming, the addition of chemical dispersants, salts or acid, and dilution (Bobicki et al., 2014a). Microwave pre-treatment has been proposed as an alternative way to eliminate the deleterious effects of serpentine in ultramafic nickel ore processing by converting the serpentine to olivine via dehydroxylation, which occurs at 600-700oC (Reaction 1). Olivine is isotropic, consisting of isolated silica tetrahedra linked by octahedrally coordinated magnesium ions, and has the same surface potential as pentlandite at the pH of flotation (~pH 9). Furthermore, since olivine is more reactive to CO2 than serpentine, microwave pre-treatment creates an opportunity to store more CO2 in tailings, an attractive option for mining operations looking to increase their bottom line where carbon pricing exists."

Jan 1, 2018

By D. J. Zhao

The reduction of ilmenite pellets was investigated at 950°C and 1000°C under a CO-N2 gas mixture with 10 L/min gas flow rate. All the reducing reactions were conducted in a furnace with a thermogravimetric analysis system. The reduction rate is higher at 1000°C than that at 950°C. At the early stage of the reactions, with the CO concentration increasing in the gas mixture, the reduction rate increased at 1000°C. In addition, at the early stage of the reactions, a rapid temperature increment and a rapid conversion of oxygen were observed on the curves of temperature versus time and conversion of oxygen versus time under different experimental conditions. The solid reaction products obtained in these experiments were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometers (EDS). Metallic Fe with small amount of Ti dissolved in it and oxides of Ti were found in the solid reaction products, but the formation of any nitride phases was not found under the prevailing conditions.

Jan 1, 2014

By G. Bulut, Ü. Yenial

"Heavy metals contamination in aqueous systems can be found in a variety of industries, in particularly mining, metal processing, finishing and plating. Water containing more than 0.5 ppm heavy metal considered as a toxic due to harmful effects on health. The major techniques employed for heavy metal removal from industrial wastewaters include precipitation, reduction, ion-exchange, and adsorption. Adsorption is a heavy metal removal method for aqueous systems. As a common adsorbent, activated carbon has been used in treatment but it is ineffective on some elements. Thus, there has been a research for developing highly effective and selective adsorbents. In this study the adsorption of lead and arsenic ions on to coal waste and red mud waste was studied. The experimental parameters were determined as pH, equilibrium time and the initial concentrations, activation by heat treatment and the blend of adsorbents. According to their adsorption capabilities, red mud was found to adsorb lead and arsenic ion with high efficiency but coal waste did not adsorb arsenic ion. However the binary adsorptions of these ions were enhanced the adsorption efficiencies. In addition the blend of coal waste and red mud affected the adsorption efficiency. INTRODUCTION As a result of rapidly developing industry and excessive use of water resources, the need of clean water and wastewater management appear as a problem. Wastewater recycling activities and researches come to the fore for an effective use of wastewater. Recycling of wastewater, which contains heavy metals harmful to the environment and human, is a difficult process. Heavy metals are generally divided into three categories: toxic metals, precious metals, radionuclides. Wastewaters from various industries, containing heavy metals, are the main polluters of water and soil. Although their toxic structures, heavy metals are used extensively in industry as they have technological significance. Usually mining industry, metal industry and industrial organizations produce heavy metal containing wastewaters (Volesky 1990, Ting and Lawson 1991, Bishop 2002)."

Jan 1, 2018

By Katarina Theander, Robert J. Pugh

The generation of froth with a critical degree of stability and height is an important aspect of the froth flotation. In this paper we have studied the synergism and anti-synergism in frothing behaviour in a mixed flotation collector/frother mixture (a model fatty acid; sodium oleate and a model frother; nonionic (polyethyleneoxide alkyl C14E6). Values of the collector / frother molecular interaction parameters (the ß-parameters) were determined from the surface tension data using regular solution theory. The frothing characteristics of the system were evaluated using a glass column equipped with a series of conductivity electrodes, which enabled the water content of the froth to be determined. From these measurements, the dynamic frothability and static froth stability were determined. It was concluded that the synergism/anti-synergism in frothability was depended on the molecular composition of the surfactant system, the diffusion of monomer to the thin film interface and on the breakdown of the mixed nonionic/anionic micelles.

Jan 1, 2003