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By V. V. Morozov, Ganbaatar Zorigt, Delgerbat Lodoy, Y. P. Morozov

"At the processing plant Erdenet, a new facility for advanced ore diagnostics in-stream (at the conveyor), based on optical analyser of mineral composition, was tested. Such systems provide highly accurate in-stream measurements of ore properties. The system provided information on the ore mineralogical composition, the particle size distribution and the impregnation of minerals. A special flatbed facility for optical spectrum-based estimation of fine-crushed ore has been developed, being incorporated into the existing system of ore sampling and analysis. Application of the flatbed facility renders possible a high accuracy of determining ore mineralogical composition. High precision of the optical spectrum-based estimation is achieved using special devices, installed in the sampling and the sample analysis flow sheet, applied by the technical control department. Modern systems for optical spectrum-based estimation of ore grade provide a basis for effective automated control of ore benefication processes, based on the principle of advanced ore grade control. Process management task of grinding and flotation was to choose options that take into account the composition and grade of the ore coming. The calculation data array comprises consumption of reagents, ore processing, grind size etc. The systems implemented at the processing plant contributed to increasing copper and molybdenum recovery. INTRODUCTION In-stream ore grade analysis is a new trend in effective control of ore benefication processes. This is realised based on radiometric measurements in the X-ray and visible spectrum regions, in which mineral components of the initial ore (Sbárbaro and Villar, 2010) or the benefication products become apparent (Hyotyniemi and Ylinen, 1998; Haavisto and Hyötyniemi, 2010). An important advantage of such methods is in-stream measuring ore parameters, including mass fractions of individual minerals, which makes it possible to use the information obtained in the processes of automated control."

Jan 1, 2018

By R. B. Shu

A moderate thermophilic microorganisms, has been isolated (45?) from a typical sulphide mine in the region of Mo Jiang located in the southwest of China. The culture has been used to extract copper from chalcopyrite concentrates obtained from De Xing copper mine. The majority of experiments were carried out in 300mL Erlenmeyer flasks containing 150mL volumes of mineral suspension. Effects of some variable parameters such as solids concentration, pH and the concentrations of inorganic nutrients on the bioleaching of chalcopyrite obtained from De Xing copper mine were investigated. For a given concentrate the most important factor affecting the fractional copper extraction was the size of the mineral particles. The overall rate of leaching was found to be limited by the area of mineral surface. The attack started in cracks and genetic defects and finally reached the whole chalcopyrite surface. As a consequence of this, the ore showed strongly cracks. The additive of ferrous sulfate increases the bacteria activity, but did not improve chalcopyrite bioleaching. The results indicate that the nature and relative proportions of the various minerals present have been shown to be important factors.

Jan 1, 2014

By Dee Bradshaw

"Process mineralogy’ is a form of applied mineralogy which focuses on addressing problems associated with the processing of ores. ‘Mineralogy’ is the scientific study of minerals and ‘mineral processing’ is the production of concentrates from ores. ‘Process mineralogy,’ however can be defined as the practical study of minerals associated with the processing of ores, concentrates and smelter products for the development and optimisation of metallurgical flowsheets, including the waste and environmental management considerations. This hybrid discipline consists of teams that include geologists, mineralogists, samplers, mineral processors and often others, working together. The degree of cross-training, communication and trust dictates the potential capacity of the team and where an appropriate work dynamic is fostered, in which relationships flourish as much as does the ethic of technical excellence, it is possible to develop technical capabilities that surpass those of conventional teams. The world’s demand for metals is ever increasing and ore deposits available for extraction and processing are lower grade and more complex, often containing deleterious elements that require tailored treatment. Generally, in the past, the technical challenges only needed to be overcome and assessed economically to make an ore deposit viable; increasingly and in the future, a more sustainable approach including environmental and societal considerations is needed. Process mineralogical assessment is increasingly providing the critical information that stands between failure or collapse and survival or success of some mining operations. In this paper, selected case studies are used to demonstrate the valuable role of the process mineralogy tools being used to provide the platform for innovative technology development. Their common attributes are discussed and distilled, thus providing some insights and potential guidance for addressing some of the likely future challenges of the mining industry."

Jan 1, 2014

By A. D. Ramirez, L. E. Gutierrez, M. A. Garces

"Scarcity of freshwater in mining operations in arid zones in different parts of the world has led to the mining companies to think about using seawater as an alternative source in mineral processing operations. Examples of this situation are Minera Centinela (AMSA) and Minera Sierra Gorda (KGHM), both plants located in northern Chile. Previous studies showed that molybdenite flotation is depressed at high pH values in seawater as a result of the action of hydroxy-complexes of magnesium and calcium that attach to the faces of the molybdenite particles, reducing its hydrophobicity and as a result flotation recovery. In this work, a study of the interactions between molybdenite and kaolinite is presented. The effect of sodium hexametaphosphate (SHMP) dispersant on the recovery of molybdenite in the presence of kaolinite is studied in different aqueous media and it is correlated with induction time data. The results allow to conclude that kaolinite has a stronger depressing effect on molybdenite in seawater compared to its effect in freshwater. Magnesium and calcium are the cations that have the strongest effect in enhancing the interactions between molybdenite and kaolinite. SHMP reduces the negative effect of kaolinite on the floatability of molybdenite both in seawater and freshwater. The induction time data correlate well with the micro-flotation results.INTRODUCTION The need for water in mining processes in arid and semi-arid zones has led to the search for new alternatives for this resource, among which seawater has gained an important space. In Chile, most of the mining operations are located in the northern part of the country, an area that has limited availability of freshwater for the processing of copper and molybdenum sulfides (Castro and Laskowski, 2011, Castro et al., 2012 a). Seawater is an aqueous solution with high concentrations of ions such as Na+, K+, Mg2+, Ca2+, So42-, Cl-, and other less concentrated species which generate important effects in the flotation process as they modify the properties of the solid/liquid, and liquid/gas interfaces, and also increase the consumption of some important reagents used to depress pyrite such as lime. It has also been proposed that flotation of copper sulfides is negatively affected in seawater because of the reduction of oxygen solubility compared to freshwater (Millero et al., 2002; Duan and Sun, 2003). In contrast, it has been shown that the presence of ions in solution in the process of flotation of natural hydrophobic resources improve recovery as result of the compression of the electric double layer (Laskowski, 1974; Klassen and Mokrousov, 1963, Laskowski and Castro, 2008."

Jan 1, 2018

By Gerke Gilian, Pretz Thomas, Pehlken Alexandra

"The evaluation of health hazards within the treatment of mineral and waste materials is gaining more and more importance in industrial countries. The need to control occupational health and safety has been recognised, and regulations which describe general protective measurements for personnel provide a tool to protect their health. It is the aim of the paper to give an outlook for practical approaches to risk assessment and to present measures for exposure reduction in accordance with the state of the art in Germany.Both the treatment of minerals and of waste materials are described in relation to the risk assessment. The method of evaluating health hazards in the two industries is similar and therefore both examples are presented next to each other.The example presented in the paper is the German “Biostoffverordnung” (the regulation for biological materials) which is important for the waste treatment industry. All kinds of waste treatment facilities (like composting facilities, waste dumps, sorting facilities for packaging materials) are obliged to carry out an assessment of health hazards for a variety of working areas and working places. The possible safety requirements deriving from this regulation are presented and discussed under the aspect of biological hazards."

Jan 1, 2003

By Lawrence Bbosa, Aubrey Mainza, Indresan Govender

"Positron Emission Particle Tracking (PEPT) and the Discrete Element Method (DEM) are used to develop a probability based model for the power draw of a tumbling mill. Experiments are conducted using dry spherical glass bead charge in a laboratory scale tumbling mill, which is mounted with a torque transducer and tachometer to measure mill power. Particle tracking information from PEPT is used to reconstruct the motion of glass beads and infer the overall charge behavior, while DEM is employed to simulate particle motion and interaction, with collision mechanics calculated using the Hertz-Mindlin contact model. For both sets of data, the product of torque and average angular velocities in discrete cells are accumulated to obtain mill power. This method is found to be within statistical agreement with measured power for all tests. The information from both techniques is then used to develop a model for the power draw as a function of particle size, mill speed and volumetric filling. Predictions of the model match well with measured and calculated values. The model is found to predict mill power within close agreement with measurement and follows trends consistent with existing work on tumbling mill modelling."

Jan 1, 2014

By D. Berman, A. Brodt

"Delivery of all volume of mined mass on the terrestrial surface results not only in irrational power expenses on moving of huge volumes of dead rock as a part of initial raw materials (especially vertically) on long distances, but also necessities of storing tailings in open-air. Thus, in bowels of earth, huge volumes of the developed space are formed. However, the nature doesn't suffer emptiness. As consequence, through the process of underground mining works, in earth bowels starts intensive development of rocks dislocation processes involving subsidence of terrestrial surface, and with it, begins irreparable damage every objects which are on that territory. Highly effective new methods of underground concentration of the various minerals, which deliveries of only target component on terrestrial surface integrally connected with transport process in stream and subsequent deliveries to destination in continuous mode by the long distance hydrotransport, allow not only to eliminate a construction of concentrating factories on the surface, but also storing of tailings of concentration process on open-air preventing dislocation of rocks, thanks to operative placing tails in the underground developed space. Surely, the main problem in the development of such gravity dressing technology is the problem of finding the optimal formula for the heavy liquid that will fill such system in close connection with the procedure of its full regeneration. The requirements for such liquid are being non-toxic and cheap. This question was solved successfully."

Jan 1, 2014

Under the AMIRA P9 project the three-product cyclone-an off-shoot of the conventional hydro-cyclone-that produces three distinct products has been developed. The three-product cyclone shows great promise as a classifier in mineral processing. Industrial and pilot plant trials performed to assess its performance in the classification of the UG2 platinum ore, indicate that the presence of an extra overflow product stream that captures the mid-sized particles, provides improved classification efficiency. To assess the split on component density, samples from the feed and product streams were screened and assays by size for chromite (? = 4.8) and silica (? = 2.65) were obtained. Results from tests performed using this type of hydrocyclone in a number of applications indicates that it can be applied successfully in circuit configurations where the conventional hydrocyc-lone is not suitable. Utilising the three-product cyclone to classify the UG2 platinum ore resulted in an intermediate overflow product stream containing the mid-sized low density silicates and relatively fine high density chromite particles while the finer overflow contained mostly fine silicates and chromite particles. The coarse chromite and silicates reported to the underflow. Due to the increased number of products, the method of using efficiency curves was extended to cater for the increased number of products in the three-product cyclone. Although significant differences in the classification performance of the three-product cyclone were noticed with variations in machine variables a consistent method of assessing the performance was applied. The efficiency curve was adopted and applied and separate efficiency curve properties were obtained for each product stream. The methodology was applied to the component data, and efficiency curve proper-ties for each key component were obtained and compared. This paper discusses the application of the efficiency curve to cyclones producing more than two products and extending the methodology to the different components in the feed.

Jan 1, 2014

By M. C. Harris

"In the flotation process the contact angle is an important indicator of the hydrophobicity of a mineral particle. There is considerable literature showing that the contact angle increases when the chain length of the alkyl group associated with the collector molecule used to render the valuable mineral particle hydrophobic increases. The extent to which an alkyl group interacts with surrounding water molecules is quantified thermodynamically by the excess Gibbs energy. In the present paper it is shown that there exists generally a strong linear relationship between the excess Gibbs energy of the alkyl group associated with the collector and the contact angle. The structure-activity of such alkyl groups is in turn related to the total surface area, molecular volume, the molar volume, molecular weight of the functional groups in the molecule and interaction energies. It is proposed that the demonstrated relationship is indicative of the role which the alkyl group component of the collector, which is attached to the mineral particle, plays in increasing the extent to which water molecules at the surface of the mineral are rejected from the surface thus increasing the contact angle. The relationship between excess Gibbs energy and surface tension is further explored with a view to relating the observations quantitatively to the parameters in the Young equation.INTRODUCTIONThe issue of wettability of materials is of great importance to many industrial applications. Wettability studies usually involve the measurement of contact angles which indicate the degree of wetting when a solid and liquid interact. As is well known the contact angle (O) is the angle between planes tangent to the surfaces of the solid and the liquid at the wetting perimeter which is the zone where the air, water and solid phase merge. When the air bubble attaches to the solid surface there is an increase in the air/solid interface area and a decrease in the solid/water interface area. For attachment to occur the cosine of the contact angle should be less than 1 and this will be promoted if the interfacial surface tension between the air and the solid (? SV) is low. Classically the relationship between these parameters has been expressed through the Young equation (1) for a perfectly flat surface:"

Jan 1, 2018

By Bertil I. Pålsson

The most common REE containing mineral that is worked today is bastnäsite. It means that mineral processes are adapted to it and that the metallurgical separation techniques for winning of individual REE are adapted to bastnäsite concentrates. For all other deposit types, suitable mineral processing methods and separation technologies need to be adapted and/or developed. Preliminary mineralogical analyses indicate that slightly less than half of the REE in the tailings dumps at LKAB/Kiruna are associated to apatite. The rest is in the minerals monazite (maybe associated to apatite) and allanite. At least allanite is probably not floatable with reagents commonly used for apatite. Mass and element distributions for the tailings sand reveal that very little apatite is present above 300 µm, and that approx. 30 % is below 20 µm. REE does not follow P2O5 completely and are also present in coarser fractions. Flotation results show that the best condition for both apatite and REE winning is pH 9, high collector addition and low dosage of water glass. Under these conditions, the lab-scale flotation gives an apatite concentrate with at least 30 % P2O5 at 70 % recovery. REE follows apatite in the cleaner steps but only partly. Its recovery is approx. half compared with apatite. The reason for the low REE recovery is likely to be that REE to a large extent is trapped in non-winnable minerals, especially allanite. The REE grades in the concentrate are expected to be in the range 3000 ? 4500 g/ton. Keywords: flotation, REE, apatite, monazite, allanite

Sep 1, 2012

By F. A. V. Guimarães, A. M. Costa

"The moisture in sintering is a very important parameter for the performance of the process. It allows that the granulation takes pace in an efficient way making the water bridges between the bigger particles used as nucleus and the finer particles that perform the coating of those coarse particles. The formation of the micro pellets is extremely important to prevent loss in permeability of the bed in the sintering grate, avoiding excessive fuel consumption and producing a quality sinter. The aim of this project is to use some of the methodologies for determine the saturation degree on ores and coal to determine the optimal moisture for sintering. In the sinter pot grate series, 3 to 4 assays in a series of 10 are required to determine the optimal moisture for the process. The saturation degree curve test has shown that is really viable to use this technique to skip those tests and go directly to the series to determine productivity and the coke / anthracite consumption. In an industrial scale can be used to adjust the water addition in the conventional mixing methods used in the sintering plants to increase productivity in the process.INTRODUCTION Sintering Sintering is a high temperature agglomeration process in which iron ore fines are partially melted and bonded together using fluxes and a source of fuel, usually coke breeze. The agglomerated product, sinter, has improved metallurgical properties making it an ideal ferrous burden that enable the passage of hot gases in the iron-making blast furnace. The sintering process is normally carried out over three basic stages: granulation, ignition/sintering, and product sizing. In the granulation stage, iron ore fines (usually a blend of selected ores), sinter return fines, fluxes and fuel, and are mixed with water and micro-pelletised in a drum or disc before being introduced in the main granulation circuit. (Wang, Teng, & Wang, 2017)."

Jan 1, 2018

By D. Szyszka

During passing gas bubbles through mineral suspensions, some mechanical carryover of fine particles to the froth layer always takes place. The entrainment of mineral particles is influenced by many parameters, mostly by the particle size and the concentration of the frother. The paper deals with influence of selected frothers (methylisobutylcarbinol (MIBC), a-terpineol, and hexadecane tricosaethyleneglycol ether (C16E23)), common laboratory flotation frothers, on the mechanical car-ryover of quartz, a typical gangue mineral component of ores. Entrainment tests were carried out in a laboratory Mechanobr flotation machine with quartz particles suspended in aqueous frother solu-tions. The mechanical recovery of quartz in the presence frother was increasing with time and reached plateau after about 20 minutes of flotation. The plateau level of quartz recovery depended on the frother concentration. Initially an increase of the plateau with frother concentration was observed until the plateau reached the highest level called the maximum recovery emax. The emax can be used as a parameter to characterize the ability of frothers to entrainment. In the studied quartz-frother flotation system the maximum entrainment was 32%, 50% and 80% for methylisobu-tylcarbinol (MIBC), a-terpineol, and monohexadecane tricosaethylene glycol ether (C16E23), re-spectively. A comparison of the maximum entrainment factor emax with other, known from literature, indices such as bubble critical coalescence concentration (CCC), dynamic foamability index (DFI), Jw, e =25%revealed, except DFI, their similarity.

Jan 1, 2014

"The Circular Economy (CE) will play an important role in shaping a resource-efficient society. Enabling this transformation from a linear to a CE requires precise quantification of resource efficiency and thus the economic viability of the system. Based on the development of simulation tools of classical minerals processing and process metallurgy, the Outotec (2018) HSC simulation platform could be further developed (gleaning from many academically published works of the author listed below), permitting the simulation of the CE system and to subsequently calculate its resource efficiency. It enables the estimation of a simulation-based Recycling Index (RI) from a product’s Bill of Material (BoM) and Full Material Declaration (FMD). It is a unique methodology for Design for Recycling (DfR) based on minerals engineering linked to a deep understanding of minerals and metallurgical process engineering. A key to this simulation is a detailed understanding of the mineralogy (both geological and designed) of the CE system and its many products, materials and systems, both in a geological mineral and a product-designer-mineral sense. In addition, a detailed understanding and quantification of the thermodynamic properties of the system (both energy and exergy/entropy) is key to understanding its economics and its limitations. With this approach, the actual losses of the CE system are shown and thus highlights the limits of the CE as defined by minerals and metallurgical process engineering principles. INTRODUCTION From the dawn of the industrial era up to today, many of our products have been created according to the principles of a linear economy: we find resources, make a product, and then dispose of it when we are done using it. But in recent years, there has been a growing awareness of the need to move to a Circular Economy (CE), an approach that aims to maximize the usefulness of products, components and materials across the entire lifecycle. In terms of recycling, this means achieving maximum recovery of materials once products reach the end of their usable life while also maximizing resource efficiency. Of importance is therefore also not only the recovery of critical technology elements that make the CE system run, but also the criticality of the metallurgical infrastructure that must be present to recover these elements economically. Ellen Macarthur (2017) defines the CE as “Looking beyond the current ""take, make and dispose” extractive industrial model, the circular economy is restorative and regenerative by design. Relying on system-wide innovation, it aims to redefine products and services to design waste out, while minimising negative impacts. Underpinned by a transition to renewable energy sources, the circular model builds economic, natural and social capital.” However, when translating this significant message to images, it is striking that the key extractive industry is not depicted in the Ellen Macarthur as well as EU depiction of a CE (EU 2015). Other CE discussions are also wanting in their fundamental detail and description e.g. Accenture (2015) and Beaulieu et al. (2016)."

Jan 1, 2018

By K. Price, G. Wang, L. R. Moore, Y. R. Xiong, J. Gu

"Sand is a naturally occurring granular material that is a result of the physical or chemical breakdown of rocks. Raw/natural sand contains various minerals, and it is this combination of minerals that brings the value to the construction aggregate industry. However, it is the quartz component of sand that is valued in its application as industrial silica in glass, high purity quartz, foundry sand, and oil and gas fracturing. Depending on the industry, the grade requirements can be the concentration of SiO2, particle size or shape, as well as contaminants such as the heavy refractory minerals, clays, fines, and alkali metals. With the ever declining mineral feed grade, processors continue to face challenges making the industry specific concentrate grade. As such, it becomes more important to tailor make the processing reagents to fit the mineral, processing conditions, and desired quality specification. This paper focuses on the application of novel collectors towards the beneficiation of sand for each of the major industrial silica applications. INTRODUCTIONQuartz is a mineral composed of a framework of silicon and oxygen atoms. It is the second most abundant mineral in the Earth’s continental crust. There are many species of quartz, which are defined by the particle size, shape, and color. Silica sand is one of those species, which is the byproduct of the physical or chemical breakdown of quartz containing rocks or crystals. Geologist define silica sand as a silica mineral with a particle size between 0.05 and 2 mm in diameter (Zdunczyk, 2001). Silica sand has significant value to society in recreation (beach sand and toy boxes), construction aggregate (concretes and asphalt), industry (iron & steel casting, fracturing proppants, and glass), as well as specialty products such as semiconductors or silicon wafers used in electronics.The aggregate business is the dominant consumer of silica sand products. Conversely, glass making, foundries (casting material), abrasives, and fracturing proppants are the dominant applications for industrial silica sand. Not much beneficiation is required for sand products going into the construction industry, other than sizing and scrubbing to remove clay. However, the industrial silica sand applications are dependent on particle size, shape, and degree of contaminants, which sets the market value (table 1). Therefore, as the more specialty products are produced, more sophisticated techniques and chemistry need to be applied to ensure the appropriate quality is met."

Jan 1, 2018

By Vladimir Vigdergauz

"Electrochemical studies of metal sulfides in connection with their floatability are discussed. According Frumkin, sorption of electroneutral organic substances has a maximum near the potential of zero charge. This idea initiated attempts of application of electrochemical methods for the controlling of organic collector sorption and mineral flotation. The lecture reviews results of electrochemical studies of the processes taking place during sulfide flotation: redox-state of mineral surfaces and xanthate solutions, xanthate sorption and hydrophobic layer composition, surface wettability and flotation recovery of sulfide minerals. Redox-transitions of minerals, transport of ions and charging of mineral surfaces, electroreduction of dissolved oxygen and accompanying processes of oxidation of minerals and reagents-collectors, - all these matters became the subjects of detailed research. Cyclic voltammetry, rotating disk electrodes, spectro-electrochemical techniques and other modern experimental methods now routinely accompany studies of mineral processing. Relatively new electroanalytical techniques like the voltammetry of mineral particles immobilised on electrodes using polymeric binders have become extremely useful for studying weakly conductive minerals and dispersed flotation products. Full discussion of electrochemical studies of metal sulfides in relation to mineral processing must include bioelectrochemistry and electrocatalysis which open exceptional possibilities for selective leaching of gold and non-ferrous metals. At this time, the paper focuses on the sulfide flotation as a potential-dependent process; the problem of oxygen and its influence on the sulfide flotation; the electrochemical aspects of xanthate oxidation and sorption; theory of suspended electrodes as applied to the mineral slurries and experimental study of the effect of electrochemical pretreatment of flotation pulps."

Jan 1, 2014

By G. W. Zhang

Ultra-fine Stirred Mill is a kind of high energy efficient equipment for ultra-fine grinding, and has been the mainstream equipment in the submicron powder and slurry industry. This paper mainly describes flow-field numerical simulation of the three popular ultra-fine grinding mills: (respective-ly as) Disc Stirred Mill, Pin Stirred Mill and Spiral Stirred Mill, by means of the software Computational Fluid Dynamics (CFD). In the flow-field numerical simulation, the velocity gradient, shear rate dispersion of the flow-field, the viscosity dissipation rate were analyzed with CFD. It is discovered that Pin Stirred Mill has the highest velocity gradient in circular directions and the most homogeneous distribution of shear rate among the three. Flow-field numerical simulation provides a new way (and means to) for the parameter optimization design and project enlargement of Ultra-fine Stirred Mill. The experiments were also carried out, the results are consistent with the results of the simulation analysis. For example, in GCC grinding experiments under the same conditions, the specific energy consumption of Pin Stirred Mill with 3600L in volume is 15%~17% less, and its processing capability is 13%~15% better than Disc Stirred Mill. Now with its optimized structure and excellent performances, more than ten sets Pin Stirred Mill with 3600L in volume have been used in industrial production in Shandong, Guangdong and Hunan province.

Jan 1, 2014

By D. Saramak

"High-pressure grinding technology is considered as one of the most efficient techniques of ore comminution, especially in terms of energy consumption. HPGR devices has been utilized in many mining-related industrial sectors, including iron and non-ferrous metal ores processing (copper, platinum, gold), as well as cement and limestone flour production. Even though the technology well known (introduced into mineral processing circuits in 80’s), there are still examples of ineffective operation of HPGR devices. This is a result of improper application of HPGR into individual crushing circuit. The purpose of the paper was to analyze selected effects achieved in HPGR on the course and effectiveness of beneficiation operations. Investigations were carried out for copper ore, and investigative programme was run for different values of HPGR pressing force, as well as changeable ore characteristics (content of fine size fractions, material moisture). All crushing products were then treated in flotation process, in order to determine useful mineral recovery. Results of investigations show that HPGR operating pressure influences the metal recovery in proportional way, however too extensive pressure values have relatively lower impact on increasing of the metal recovery. Particle size distribution of HPGR feed and its moisture have lower influence on recovery level than HPGR pressure, but too extensive moisture content influences the higher energy consumption of the roller press, together with less effective comminution. The second aspect raised in the paper was a possibility to control and optimize the HPGR-based circuit. There were presented the proposed approach to adjustment of HPGR operating parameters that enables the higher metal recovery.INTRODUCTION The high-pressure grinding technology, invented and developed by Professor Schoenert in 70’s (Schoenert, 1979), is currently regarded as one of the most efficient methods of hard ore comminution. Since then the technology was introduced into raw materials treatment circuits in many mining and mining-related industrial sectors, including iron and non-ferrous metal ores processing (copper, platinum, gold), as well as cement and limestone flour production. Considerable number of works concerning modeling and optimization of HPGR operation were also presented (Daniel & Morell, 2004, Tavares, 2005, Saramak, 2012, Saramak & Kleiv, 2013). Nowadays high-pressure grinding rolls devices are considered as well know technology with over 500 sold machines, according to various sources."

Jan 1, 2018

By Vasile Murariu, William Pate, John Herbst, Dilek Alkac

"Multiphysics models are essentially first principles models capable of providing very accurate micro scale predictions. The computational requirements for Multiphysics Models are extensive, precluding their direct use for flowsheet simulations. Population balance models get their form from theory but the model parameters have to be provided from experiments. The prediction errors for the population balance models are typically significantly higher than those for the Multiphysics Models but the computational effort for Population Balance Models is typically much less than that for the Multiphysics models. The hybrid model described here takes advantage of the strengths of each of the two primary model types and minimizing the weaknesses of each. The Multiphysics Model is used to perform high accuracy "experiments" that are difficult or impossible to conduct in laboratories or plants. The results of these experiments are combined with standard laboratory or plant data to parameterize and further enhance the Population Balance portion of the hybrid model. The creation of a useful Hybrid Model is demonstrated for a MP1000 secondary crusher. The validation of the hybrid crusher model is also presented. Finally the use of the Hybrid Model is illustrated in a full comminution flowsheet simulator."

Jan 1, 2014

By M. M. Bugarin, P. J. van Staden, V. T. Conic, S. S. Dragulovic, R. M. Kovacevic, D. B. Milanovic

"The mineralogical and physico-chemical characteristics of a polymetallic sample from a mine of West Serbia suggest that it can be classified as a SEDEX type of ore. Those ores contain multiple value components, being inter-dispersed as fine grained aggregates. This prevents concentration by gravity or flotation concentration processes. Mineralogically, the valuable metals (Cu;Zn;Pb;Au and Ag) occur as pyrite, sphalerite, galena, tetrahedrite, chalcopyrite, covellite, arsenopyrite, and non-metallic minerals (barite, and waste minerals). Novel technologies are under development within this project for the recovery of all valuable metals from this very complex material. The work comprises the further treatment of solid residue obtained after Cu and Zn extraction by bioleaching, for the subsequent recovery of Pb and the precious metals Ag and Au. The residue is first treated with a saturated sodium chloride solution, whereupon a chloride solution of lead (NaPbCl3) is obtained. From the chloride solution, lead was deposited in the form of lead carbonate, followed by reductive melting, whereupon lead anode was obtained. Electrolytic refining of the lead anode, using a solution of PbCO3 in methane sulphonic acid (MSA-Methanesulfonic acid, min 99.5% CH4O3S, density 1.48 kg/dm3, Manufacturer: Carl Roth) as an electrolyte, yielded refined lead cathode. It should be noted that, after precipitation and separation of lead carbonate, the sodium chloride solution is restored to its original composition by the addition of make-up reagents and returned for another lead-sulfate leaching cycle. The solid residue obtained after leaching lead-sulphate, is leached in thiosulphate solution, with the addition of an activator, a catalyst and lixiviant for gold, to yield a thiosulphate solution of gold and silver. Since the content of gold and silver in solution is low (below 1 mg/dm3), they are first electrolytically concentrated on steel cathode and then refined to pure metals using well-known chemical methods. Note that, after the electrolytic separation of gold and silver, thiosulphate solution is recycled to the leaching step."

Jan 1, 2018

By G. Unland

The sizing of crushers depends on the expected crushing forces. However, the crushing forces develop differently with every individual rock while it is compressed by the working surfaces of the crusher. For sizing, this compression process has to be characterized by the maximum crushing force. The maximum crushing force depends on the strength, shape and size of the rock, the amount and velocity of the imposed displacement of the working surfaces of the crusher on the rock and the conditions of the contact surfaces. From experience it is known that the strength of the material and, therefore, the crushing forces depend on the size of the specimen. This dependence is the so called size effect. The determination is based on compression tests. The force development is recorded during the compression of the specimen and for every individual test the maximum force is determined. The occurring maximum crushing forces of several rocks with the same diameter comminuted under the same conditions can be assessed by a mean value and a variance. The relationship between the mean values of the cross section related maximum crushing forces FAmax and the corresponding sizes d of the specimens can then be described by mathematical functions. They are derived from different approaches (phenomenological, statistical and statistical-physical methods). The phenomenological methods are subjective and yield functions depending on the assumptions of a person, whereas the statistical and statistical-physical methods are based on an evaluated function and the optimization of the parameters.

Jan 1, 2014