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By Renato S. Costa, Afonso H. Martins, Flávia D. Mendes

"This paper presents some important aspects regarding the ion exchange treatment of an Ni and Co sulphate acidic liquor using chelating resins. Chelating resins possessing iminodiacetic or bis-picolylamine functional groups were compared in terms of nickel and cobalt recovery. The experimental resin with bispicolylamine functionalities (Dowex M4195) was evaluated with respect to Ni and Co uptake, and compared with Rohm &Haas commercial chelating iminodiacetate acid resin. The Rohm & Haas chelating resin, Amberlite IRC 748, with its weakly acidic groups, did not work in acidic solution but exhibited good results at pH 4 and above. The resin that efficiently removed metals from high acidic solutions was the bis-picolylamine resin. Maximum nickel uptake values ranged between 85 g and 112 g Ni per Kg of resin.The experimental part dealt with the working conditions, resin characteristics and the influence upon the resin maximum exchange capacity of the following factors: nickel concentration, temperature, pH and resin-to- solution ratio. Based on the experimental data obtained, it has been proposed a innovative technological treatment."

Jan 1, 2003

By Sashnee Raja, Mehdi Nemati, Ashley Sissing, Susan T. L. Harrison

"Extreme thermophiles, operating at 65 - 90°C, are finding increasing application in biohydrometallurgy These microorganisms have the advantage of exhibiting better oxidation kinetics in terms of reaction rate and extent of mineral solubilisation. These extreme thermophiles are Archae, characterised by a different cell envelope structure perceived to provide reduced structural strength in comparison to bacterial envelopes, and customised metabolic pathways.The active tank bioleaching process, used for high rate leaching, is conducted in a slurry bioreactor. Here sufficient energy dissipation is required to ensure suspension of the mineral phase as well as to sustain high rates of gas liquid mass transfer. It is well known that subjection to hydrodynamic stress of sufficient magnitude may alter the physiological state of a range of micro-organisms through changed viability (ability of the microbes to grow), metabolic activity and integrity.In this paper, we report on studies carried out to quantify the ability of the extreme thermophile Sulfolobus to withstand the hydrodynamic stress environment generated at high pulp densities in the slurry bioreactor. Both a pyrite system (as a model system) and a chalcopyrite system (as an application) were studied. In laboratory reactor systems, the nature of biological responses to stress induced at high pulp density have been identified in terms of ability of the microbes to grow, their metabolic activity and rate of leaching and cell integrity. Critical operating conditions within the laboratory reactor are identified and the mechanism mediating reduced performance considered."

Jan 1, 2003

By Peter Scales, Ricardo Jeldres, Fernando Concha, Pedro Toledo, Shane Usher, Anthony Stickland

The impact of several electrolytes present in seawater on the rheological properties of flocculated mineral suspensions was assessed using the creep test. Flocculated suspensions were obtained by adding polymer flocculant to a cylinder of mineral suspension and aggregating the suspension using the plunger method. The suspension was allowed to sediment and the supernatant liquid decanted prior to tests for the viscoelastic properties of the resulting sediment. The solid used was alumina AKP-30 both, below and above the isoelectric point. The polymer used was AN934SH, an anionic flocculant with high molecular weight. Salts analyzed were MgCl2, CaCl2 and NaCl, known as water structure makers, and KI and KCl, known as water structure breakers. A high salt concentration of 0.5 M was used to approach the ionic strength of seawater. For both pH’s studied, the sediments demonstrated a viscoelastic non-linear behavior observed as a non-linear relationship between yield strain and applied stress. In the absence of flocculant, it was observed that the viscosity and yield stress of a suspension increase in the presence of structure maker salts for the case of both silica suspensions and alumina suspensions. These results were explained using hypernetted chain statistical mechanics models describing the interaction of ions with solvated surfaces. In contrast, with the presence of flocculant, the shear yield strain of alumina suspensions increases with the breaker character of the salts, however, this result has been explained by an extension of the results from the models. The work has significant implications for the flocculation of mineral suspensions in the presence of seawater.

Jan 1, 2014

By Christopher Robben, Alexander Mosser

"X-ray transmission (XRT) sorting has been introduced into the minerals industry in 2006 and has found various applications in diamonds, industrial minerals and metal ore processing since. The technology offers planar projections of the atomic density of single particles similar to the principle known from airport scanners, but being capable of treating up to 150tph per metre working width. In 2010, a pilot operation using a belt-type sensor-based sorter went into production at the Mittersill mine to treat the fraction 16-28mm. After an optimisation phase, the results were superseding expectations and therefore in 2012 a bigger production plant was set up. Two XRT-based sorters are parallel in operation since. One is treating the fine fraction 16-30mm while the other one is treating the coarser fraction 30-60mm after the secondary crushing stage. The XRT sorters are operated with the objective to reject barren waste before it enters the mill and flotation plant. 105,000tpa of waste material are rejected per year and can be sold as aggregate for road construction. This means that about 22% of the run-of-mine ore are rejected at an early stage with a waste reject grade lower than 0.03wt%WO3. The installation has not only led to lower specific operating costs but also led to reduced tailings disposal in an environmentally sensitive area. This allows the mine to reduce its headgrade which allows for a longer mine life. Alternatively it is possible to produce more tungsten concentrate, which is delivered to the smelter. This article will introduce the technological principle of XRT-based sorting and will discuss the flow-sheet of the Mittersill mine. Experiences that have led to the current plant design are described as well as the impact it has on the operation."

Jan 1, 2014

By O. A. Bascur

It is difficult to analyse the economics without an integrated view of mine transactions, stockpile inventories, process flows and assays. The lack of integration of mining and metallurgical information with sufficient detail to analyse and act is a problem. However, to take action requires real time information from manufacturing assets, corrected for gross errors from trucks, shovels, conveyors, faulty sensors, bad instrument calibration. Validation methods use process models to identify inconsistent information in the case of corrupt actionable information. This paper presents new strategies that transform the data into business information for continuous improvement and optimization. This technical presentation will review recent implementations enabling large metallurgical complexes to improve their data quality for overall production and energy management. A competence center emerges as an enabler for implementing operational intelligence. The evolution of Web services to troubleshoot plant information and to collaborate at the enterprise level is presented.

Jan 1, 2014

By Wei Zhang, Jinhong Zhang

"In froth flotation, the adsorption of collector on mineral surface is critical for a successful flotation process. In present work, an atomic force microscopy (AFM) has been applied to study the adsorption of potassium amyl xanthate (PAX) on copper sulfides, i.e., chalcopyrite, chalcocite and bornite. The in-situ collected AFM images show that PAX adsorbs on chalcopyrite mainly in the form of oily dixanthogen; while it strongly adsorbs on chalcocite and bornite in the form of insoluble metal xanthate, which binds strongly with the mineral surface. The information obtained from the AFM study shed lights on the collectivity and therefore the selection of specific collector for different copper sulfide minerals in industrial practice.INTRODUCTIONFroth flotation, which treats the highest throughput in mining industry and produces the maximum economic outcome of any surface chemistry process, has been widely applied for the concentration of copper sulfide minerals, i.e., chalcopyrite, chalcocite and bornite. In flotation, collectors are added into the pulp (mixture of water and fine-grained minerals) to selectively adsorb onto the target mineral and render its surface with high hydrophobicity, which is generally beneficial for a strong mineral-bubble attachment and thus a high flotation recovery. Therefore, the adsorption of collector on mineral surface is vital for a successful flotation process and it has been studied by applying various surface analysis techniques, such as IR (Infrared Spectroscopy), CV (Cyclic Voltammetry) and XPS (X-ray Photoelectron Spectroscopy). (Poling, 1963; Allison et al., 1972; Mielczarski et al., 1984; Leppinen et al., 1989; Kartio et al., 1996) These studies have revealed a lot of information, such as the reaction, product and mechanism, of the adsorption of chemicals on mineral surface. It is also of great interest to directly get the image of adsorbed collectors on mineral surface changing with pulp chemistry, such as pH, redox potential, ionic strength and chemical’s dosage."

Jan 1, 2018

By Thi Hien Tran, Ngoc Anh Tran, Thi Thu Hien-Dinh, Duy Anh Dao

"Natural graphite exists mainly in three types of amorphous graphite, flakes graphite and lump graphite. Graphite from Bao Ha mine, Lao Cai province is with 11.8 carbon-graphite %, forms in flakes and dense crystals. The paper presents the comparison among enrichment of Bao Ha’s graphite by two types of froth flotation with 90 g/t kerosene oil as collector, 50 g/t montanol 800 as frother, in natural pH, and at 20 wt.% of solid. The differences among three flow charts indicated that using middling flotation and re-middling flotation for the cleaning tails and the scavenger concentrates, the final concentrate was improved and containing up to 94 carbon-graphite % of flakes graphite, up to 82 carbon-graphite % of fine graphite with 93.48 % total recovery, moreover, carbon-graphite in the final tail is 0.86 % with 6.52 % recovery. However, a refining mill and a classification stage were applied before doing the middling flotation stages.1. INTRODUCTIONGraphite (black lead or plumbago) is used in many industrial applications due to its high electrical and thermal conductivity, lubricity, and chemical inertness. High quality graphite can be used in metallurgy, molding, brake linings, batteries, and fuel cells. Graphite, composed exclusively of the element Carbon, is rather common mineral, but fine crystals are rare. Graphite is soft (hardness: 0.5-1 Mohs scale); has a layered, planar structure; occurs in platy or acicular (occasionally) morphology (Minerals.net; Pierson, 1993).USGS (2017) reported, global consumption of natural graphite continuing increase in the period of 2012-2016. In 2016, China used up 35% while produced 66% of the world’s graphite. Graphite mining are being developed in Madagascar, Mozambique, Namibia and Tanzania, but production reduced in Canada from 2015. Based on the statistic of Statista.com shows from 2011 to 2014 and a forecast to 2020, the global graphite demand is mostly in refractories, batteries, others, lubricant/crucible, foundry and pencil, and that is increase every year.Graphite Vietnam lies on the fault of the Red river from Yen Bai to Lao Cai, the reserves is estimated around 29.3 million ton and mostly in Lao Cai province where has Nam Thi graphite mine and Bao Ha graphite mine (MOIT, 2008). Vietnamese graphite products could reached to ~92% graphite carbon (Cg) (Tran Thi Hien et al., 2008). Studied samples was collected in Bao Ha graphite mine, is located in Lao Cai province. Graphite Bao Ha exists in two types as graphite flakes and amorphous (Hoang Thi Minh Thao et al., 2017)."

Jan 1, 2018

By Herman D. Mendoza

A rapid recovery/recycling process was introduced utilizing the surface-chemical properties of finely dispersed mercury and alumina (Al2O3) fibers in aqueous environment. The conventional method of amalgamation or .ball milling. involves the mixing of a substantial amount of mercury to collect free gold during the grinding stage. In effect, a portion of the mercury is transformed into minute droplets that readily float and disperse in the amalgamation effluent. The fine droplets of mercury in the dispersion readily attached onto the positively charged macroscopic alumina fibers (i.e. = pH 9.8) at conditions pH 3 to 10. When an effluent from settling procedure after an amalgamation-grinding stage is passed through a column-bed packed with alumina fibers, maximum collection of negatively charged finely dispersed mercury occurred at pH 3 to 6. The collection/attachment efficiency was 99.5%. The collected droplets of mercury, which are left in the column-bed of alumina fibers, were subsequently rinsed with alkaline solution at pH 10 to 11.5. At these conditions, both mercury and alumina fibers carry negative surface potentials and resulted in the partial detachment of mercury from the alumina fibers. The detachment efficiency was only 30-35%. The attachment/detachment mechanisms in this study were analyzed using the DLVO theory.

Jan 1, 2003

By Mike Hollitt

The first decade of the 21st century was one of fundamentally changed dynamics for the minerals industry. Following intense globalization commencing in the late 20th century production is now concentrated into large businesses that can compete across geography in diverse commodities. Asian industrialization and urbanization is now the main driver of growth in demand for energy and materials. Demand for the output of these industries has risen sharply, reversing decade long trends to reduced real commodity prices. Supply responded with expansions of existing mining and processing operations, and large investment in new resource development. Development of new, lower grade or more remote resources was stimulated. Resource development by global entities in frontier environments reinforced the importance of effective forms of social contract, and of stronger environmental performance. The worst economic shock in decades provoked no significant pause despite large impacts on corporate ownership. State owned enterprises commenced unprecedented foreign direct investment in minerals and energy resources. A thrust towards resource nationalism re-emerged as governments sought to ensure that the export of state owned resources contributes more strongly to government revenue, reducing the burden of trade in scarce resources on other trade-exposed sectors. The unprecedented combination of forces at work has made future predictions difficult, with day-by-day volatility in anticipated corporate fortunes, and investment plans. The challenge for process innovation (and for exploration) has been to keep up, maintaining a lid on costs as lower grade and more challenging ore bodies are brought on quickly in a context of competition for land use, community expectations and continued care for natural and living environments. While new projects have provided the necessary platforms for implementation of innovative approaches, there is evidence that a gap may have emerged between the pace of growth and the pace of innovation. The history of a century of process innovation in the context of growth of output, declining resource grades and commodity prices is presented. The necessary conditions for accelerated process innovation are considered, and future needs and approaches are discussed. Keywords: process innovation, resource development

Sep 1, 2012

By M. Saghaeian, R. Hejazi, H. Abedini, M. Zare

Water recovery in mineral processing plants is one of the most important subjects because water supply is a critical matter economically and environmentally, especially in desert areas. In this paper, the filtration behaviour of two iron ore tailing sample has been investigated using laboratory scale vacuum and pressure filtration units. These samples including tailing from Sirjan and Zarand concentrate production plants with the d80 of 94 and 41 micron, respectively. The results show that by using vacuum filtration the cake moisture content of Sirjan sample would be about 24%. But the filtration time is too long and vacuum belt filter cannot be used in industrial scale. Adding about 40 g/ton of flocculant would decrease the filtration time by about 30% and make the vacuum belt filter appropriate for dewatering of this sample. For Zarand tailing sample, the vacuum filtration would produce a wet cake by about 31% moisture content. Filtration time is too long and adding flocculant would not improve the results very much. So pressure filtration must be used for dewatering of this sample. The results of laboratory tests show that using pressure filter would reduce the cake moisture content to 21%. The filtration time is logical, so this process can be used for Zarand tailing dewatering.

Jan 1, 2014

By D. Govender

Theoretical flotation models suggest that there is a positive relationship between bubble-particle collision rates and turbulent kinetic energy dissipation. Fine particle flotation performance is generally enhanced by increased collision frequency and hence higher energy dissipation. Contrarily, increased turbulence in the rotor-stator region is related to higher detachment frequency of the coarser size range. Therefore, the optimal modes of recovery for the ?fine? and ?coarse? size classes are diametrically opposed. Industrial applications have previously confirmed that applying greater power to flotation slurries yields significant improvements in fine particle recovery. However, recovery of the coarser size class favors a different flotation environment. An improvement in the kinetics of the fine and coarse size classes, provided there is no adverse metallurgical influence on the intermediate size ranges, is obviously beneficial to the overall recovery response. Managing the local turbulent kinetic energy dissipation, and hence the power imparted to the slurry, offers the benefit of targeting the particle size ranges exhibiting slower kinetics. FLSmidth recently introduced the practical implementation of this concept. In principle, it decouples flotation regimes where fine and coarse particles exhibit preferential recovery. In the case of naturally aspirated machines (Wemco®), it is referred to as Hybrid Energy Flotation? and incorporates at least three phases: ? Standard flotation machines (standard energy input, rpm, rotor size/type) at the beginning of the row, where flotation is typically froth phase limited and operational, and set-up parameters have a limited influence on the recovery. ? Higher-powered flotation machines (high rpm, high power rotor size/type) at the end of the row to improve fine particle recovery. ? Lower-powered flotation machines (low rpm, low power rotor size/type) to enhance coarse particle recovery. In evaluating the effect of turbulent kinetic energy on flotation performance, the spatial distribution and its effect on size denominated recovery needs to be evaluated. The mean energy dissipation rate is a measure of the bulk energy input, but CFD-based models offer a more introspective view of flotation sub-processes. A CFD-based flotation model is used to highlight the effect of turbulent dissipation energy on attachment and detachment rates. Preferential collection zones for ?fine? and ?coarse? particles are predicted for both forced air and naturally aspirated machines. Keywords: CFD-based model, attachment, detachment, energy dissipation, hybrid energy flotation?, forced air, naturally aspirated

Sep 1, 2012

By A. Shibayama

Soil contamination by organic compounds is one of the most concerned issues on polluted soil. It is well known that there are limited methods to remediate the contaminated soil on site. Especially, the in-situ method for contaminated soil is too difficult to de-contaminate the organic pollutant. In this study, the fundamental ability of soil remediation, which aimed to decrease oil concentration in, in-situ process, have been researched by using a high pressure gas generated from ?crush composition? on artificially oil contaminated soil. The n-hexadecane (n-C16H34) and other organic compounds were selected as soil oil contaminators, gravimetric analysis by soxhlet extraction and GC-MS were used as qualitative and quantitative analysing methods. For the experimental examination, the influences on the difference in the concentration of n-hexadecane (and other organics), the tamping amount, position and repetition of crush composition in soil, and scale (size) of experimental model were investigated. The n-hexadecane concentration reduced by the explosive effect of crush composition showed a reasonable decrease of about 30 wt%~60 wt% compared to the initial n-hexadecane. The removed amount of n-hexadecane and distance from explosion point of the crush composition was related in scale and model of contaminated soil.

Jan 1, 2014

By Q. Shi

An investigation into the hydrophobic aggregation of ultrafine smithsonite in surfactant solution has been undertaken through a combination of hydrophobic flocculation experiments, zeta potential measurements, surface tension measurements, and contact angle measurements. The experimental results have revealed that the behaviors of hydrophobic aggregation were closely correlated with the particle hydrophobicity, but they were not lowered byte change of the particle surface charges due to surfactants adsorption. On the other hand, the liquid (solution) surface tension (?LV) plays an important role in hydrophobic aggregation, and the hydrophobic aggregation could not occur below the critical liquid (solution) surface tension (?c). Meanwhile, this flocculation has been observed to require sufficient stirring strength and magnitudes of kinetic energy input to achieve the maximum aggregation degree. From the microflotation results, it has been found that the flotation kinetics response of smithsonite fines is markedly improved due to sufficient stirring strength, and the stirring strength influenced the floc flotation in a manner quite similar to their influence on the hydrophobic aggregation, suggesting that the formation of hydrophobic flocs is a promising means to recover smithsonite in the fine size range.

Sep 1, 2012

By B. Rai

Processing of dolomitic phosphate ores remains one of the most challenging problems in phosphate ore beneficiation. The beneficiation plant at Jhamarkotra in Rajasthan, India for example is currently using a conventional double stage flotation process which involves first a fatty acids flotation to produce a combined dolomite-apatite concentrate (bulk concentrate) from associated silicate gangue. Dolomite is then separated from this bulk concentrate by flotation with fatty acids collectors and depressing apatite with phosphoric acid and sulphuric acid. This process requires addition of large dosages of reagents (H3PO4 and H2SO4) to depress apatite and to maintain highly acidic pH during flotation. Furthermore several cleaning and scavenging stages are needed to obtain the product of desired quality. We have developed and employed a molecular modelling based methodology of designing selective reagents for apatite-dolomite separation. We have been able to take into ac-count the differences in the distribution of calcium cations on these two surfaces in our design and hence develop novel phosphonic acid based depressants for apatite-dolomite separation with con-ventional fatty acids as flotation collectors. We have demonstrated the utility and power of molecular modelling based reagents design approach through this work on beneficiation of Jhamarkotra dolomitic phosphate ore using our novel phosphonic acids based depressants at pH?s close to natural pH. It was possible to reduce the MgO content of the ore from as high as 13.3 % to 1.5% in a single stage flotation. Our flotation separation results on Jhamarkotra ore with these new phosphonic acids based tailor-made depressants for apatite-dolomite flotation separation are discussed in this paper along with results of corresponding molecular modelling computations on the same system.

Jan 1, 2014

By C. R. Mambote

One of the processes developed for vanadium recovery from the fly ash of crude oil is through acid leaching. In the process, iron is one of the impurities that should be removed before vanadium precipitation, due to the fact that iron tends to co-precipitate with vanadium. The mechanism of iron precipitation is understood in terms of ferric hydrolysis, followed by the dimerization and subsequent polymerization of the crystalline iron compound. In order to develop a new approach for the fly ash processing, in the present paper the precipitation of iron from the liquor after the leaching process was studied with addition of NaOH or NH4OH in the presence of H2O2 or Na2C2O4 at 80°C. The objective was to investigate the feasibility of the selective precipitation which could be applied to vanadium and nickel recovery from the fly ash. The experimental results show the difficulties of removing iron by precipitation without co-precipitating nickel and vanadium.

Jan 1, 2014

By U. S. Chattopadhyay

The estimated requirement of the nation by the year 2020 is approx. 80 Mt of steel and more than 0.2 million MW installed capacity of the electricity, thereby increasing the consumption of the coking and non-coking coal, which is expected to be in tune of about 75 Mt & 500 Mt respectively. One of the major deleterious factors in achieving the goal is the deteriorating quality of the feed coal used in both steel and power industries. Indian coking coals, in general, are typified by high ash, high inert (both organic and inorganic), low rank, low reactive macerals content, heterogeneous petrographic make-up, inferior coking properties and poor amenability to washing, thereby necessitating suitable washing measure. Coke-based steel industries in India require washed coking coal containing ash % varying between 17-19. The situation demands taking on immediate challenges to fill up the gap between the requirements and supply of coking coal. This paper reviews the R&D attempts in this laboratory and throws light on the key measures as long-term solution to the problem. Search for alternative source of coking coal, like LVC coal and their judicious preparation technology. The low volatile coking coal (LVCC) constitutes about 50% of the total coking coal reserves in India. These coals are characterized by high raw coal ash content (37 to 40%) and very difficult washability potential. If these coals are treated in the existing washeries, which are generally 2 or 3-product systems, the cost of clean coal is high as the byproduct sale value is low. It has been proposed to produce a new type of by product, which enjoys high demand and good coking properties.

Sep 1, 2012

By A. V. Rasskazova

"The oxidized and mixed ores are processed by heap leaching. Primary ores with high gold content are floated. In recent years mining of primary ores with the low gold content (up to 4 ppm) has increased. Extraction of gold from these ores by floatation is technologically ineffective. Gravity concentration is ineffective for fine gold particles because of their floatability. The research objective was assessment of the viability of processing gold-bearing ore with combined gravitational and hydrometallurgical methods and testing of recovery of metals from a gold-copper oxidized ore chloride-hypochlorite leaching solution. The advantage of chloride-hypochlorite lixiviant is the low cost of reagents which is produced by the electrochemical synthesis of NaCl solution with the addition of HCl. The adsorption of chlorine compounds by a mineral matrix and its ability to oxidize the refractory ore components and allows for the application of chloride-hypochlorite systems for gold recovery for both oxidized and primary ores. The complexity and problem in using a gold–chloride system is the strong adsorption of gold–chloride complexes onto mineral surfaces, such as goethite, quartz, and alumina. In preliminary testing, gold recovery from gravity circuit gold bearing concentrates processed by agitation leaching in chloride-hypochlorite solution, gold recovery has reached up 82% after 4 hours of leaching. Chloride-hypochlorite leaching of copper-gold oxidized ore with preliminary processing by sulfuric acid provided for 94 % gold recovery to solution. Understanding of ecological hazard of cyanides is the motive power of researches in the field of search non-cyanic chemistries to provide for technologically and economically effective solvents of gold. Soluble compounds of chlorine with a suitable oxidizer are one of the alternatives to cyanides. Basic researches of gold extraction by chloride-hypochlorite solution have shown high rates of gold recovery.INTRODUCTION Because of the continued and growing environmental concern for the use of cyanide for gold processing, interest for the use of non-cyanide lixiviants, especially with halides has renewed recently (Tran et al., 2001; Ferron et al., 2003; Bhaghalha, 2007). Leaching solutions based on halides (chloride, bromide and iodide) are viable alternative to cyanide (Kwang et al., 2008). The major disadvantage of the chlorine–chloride system is the high reactivity of chlorine in reaction with sulfide and gangue carbonate minerals. It is believed that only high grade materials may be treated by chlorine–chloride systems economically (Baghalha, 2007). Another important problem of the application of gold–chloride complex is that it tends to be rather unstable and may re-precipitate upon contact with a reductant, such as sulfidic minerals of ore. It is well known that Au(III)–chloride hydrolysis species are strongly adsorbed by goethite, quartz, and alumina (Machfsky et al., 1991). To minimize adsorption of gold–chloro complexes, it works best to minimize the adsorption time."

Jan 1, 2018

By S. Owada

A national project of ?Establishing ?Green-Hydrogen (G-H)? Society in Honjo-Waseda Area? is now being developed by Waseda University together with four other universities and ten companies. The project involves three tasks of technological development of, (1)?G-H? production, (2)?G-H? refining, transportation and storage, and (3)?G-H? utilization. This paper focuses the first task of ?G-H? production from aluminium dross. We developed the physical treatment process by combining selective grinding with vibrating rod mill and electrostatic separation, in order to produce two kinds of materials, one is metal aluminium concentrate to recover it and the other is raw material to produce ?G-H? and aluminium hydroxide which can be generated by the treatment with sodium hydroxide aqueous solution. Here, we described the concentration mechanism of metal aluminium in the selective grinding and electrostatic separation and proposed a separation flowchart for optimizing the ?G-H? system in Honjo-Waseda area.

Jan 1, 2014

By A. G. Bulaev

Biohydrometallurgical technologies based on activity of acidophilic microorganisms oxidizing ferrous iron, sulfur, and sulfide minerals are widely used to extract base and noble metals from sulfide ores and concentrates. As sulfide minerals oxidation is exothermic, industrial processes are usually preformed at 40–50°C. Moderate thermophiles predominate under these conditions. Most of moderately thermophilic acidophilic microorganisms that oxidize metal sulfide are mixotrophic, i.e., they use both organic nutrients and CO2 as carbon sources. Carbon availability is crucial for microbial activity and affects efficiency of biohydrometallurgical processes. Aeration with CO2-enriched air is often used to increase microbial activity in biooxidation reactors. Organic nutrients can be used as alternative carbon source for moderately thermophiles performing biooxidation of sulfide concentrates. We performed several experiments with different sulfide concentrates to study effects of organic carbon sources on biooxidation efficiency and demonstrated that application of such organic nutrients as yeast extract (YE) and molasses made it possible to increase biooxidation efficiency. For example, addition of 0.02% YE in the nutrient medium increased biooxidation rate of pyrite–arsenopyrite gold bearing and chalcopyrite concentrates in batch mode at 45°C. YE addition increased oxidation rate of sulfide sulfur and gold recovery level from 65 to 87% and from 73 to 81%, respectively. Similarly, YE addition increased copper extraction from 47 to 54%. At the same time, YE addition increased efficiency of biooxidation of pyrite–arsenopyrite gold bearing concentrate in continuous mode. Without YE addition, oxidation rates of pyrite and arsenopyrite were 65.7% and 94%, while gold extraction was 71%. YE addition (0.02%) made it possible to oxidize 74% and 95 % of pyrite and arsenopyrite and extract 78% of gold. Addition of molasses (0.02%) similarly affected biooxidation efficiency. Thus, addition of organic nutrients in nutrient media is a promising strategy for improvement of biohydrometallurgical processes.

Jan 1, 2018

By U. A. Peuker

"Steam Pressure Filtration (SPF) is a modified cake filtration process and is characterized by both washing and excellent de-watering of the filter cake. Compared to conventional gas differential pressure filtration, the filter cake is treated with saturated or superheated steam replacing pressurized air. Invented in the early last century, Steam Pressure Filtration has reached technical maturity in the 1990ies for inorganic particle systems, fine chemicals and coal. Especially the de-watering performance for fine particles systems below 50 µm make Steam Pressure Filtration an excellent option for the processing of fine tailings streams, to produce a stable material, which can be described by the methods of solids mechanics instead of paste rheology. The washing, which is due to the condensing steam, is able to reduce the ion load of the solid. This additional effect is able to generate a dry tailings material, which shows a reduced leaching potential of mobile ions, which originally derive from the process water. INTRODUCTION Steam Pressure Filtration is a process concept especially of hyperbaric filtration, which started its market entry in the 1990ies (Bott 1996, Bott 2002). Even though there have been many attempts to apply steam on filters before, the success story began with the combination of hyperbaric filtration and steam application and the technical solution to limit the steam treatment to a defined zone on the filter. This resulted from the scientific findings that steam mainly enhances the de-watering during the mechanical filtration (Gerl 1999). There are no or minor positive effects of steam application to a filtration process during cake filtration and after the steam breakthrough has occurred. Furthermore that time a sufficient control technology to regulate the steam consumption as well as suitable filter cloths became available. There is a growing need for de-watering technology in the mining industry, not only for the concentrate but also for the tailings streams. Several reasons argue against the established solution of damping the tails as suspension or paste into tailings ponds. There are ecological, political, societal and economic reasons, which question the tailings ponds more and more. Due to the increasing costs in the building and monitoring of tailings dams, which contain the tailing ponds, the concept of dry stocking using filtration technology comes into the game (Jansson 2016). Dry stocking converts the tailings stream form the suspension or paste state, into a material, which can be stockpiled. The latter typically is a moist flowable disperse particle system. The conversion involves a de-watering step, in which different types of filter equipment can be used, e.g. filter presses, membrane filter presses, automatic press filters or hyperbaric filters. For coarse products also vacuum filter can be applied. Due to its excellent de-watering performance and the easy scale-up properties Steam Pressure Filtration is further option for dry tailings stacking."

Jan 1, 2018