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By Fu Ping-Hao, Sergio Mauricio Vianna, Ewen Silvester, Emmy V. Manlapig

"Over the last 5 years, an ambitious project has been undertaken at the Julius Kruttschnitt Mineral Research Centre (JKMRC) aiming to isolate, study and, if possible, model the effect of particle size, liberation and collector adsorption density on the floatability of mineral particles. As part of this project, we have conducted highly controlled flotation test-work, combined with state-of-the-art solution and surface analytical techniques such as High Performance Liquid Chromatography (HPLC), Time of Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) and detailed mineralogical analysis to fully characterize the flotation behavior of a natural ore.The flotation tests were undertaken using a high-grade lead-zinc ore from BHP-Billiton’s Cannington mine (Australia) in a specially designed continuously operated laboratory scale flotation rig. Solution and adsorbed collector concentrations were measured independently during the course of the flotation tests using HPLC based ex-situ techniques. Liberation studies were performed using the JKMRC Mineral Liberation Analyser (MLA) on selected size intervals of different streams to estimate the specific surface area of galena. These results were used to calculate the collector adsorption density (collector coverage) on galena particles, with the eventual aim of developing a mathematical model describing the relationship between pulp chemistry, feed mineralogy, and floatability of galena particles."

Jan 1, 2003

By G. K. Nimal Subasinghe

The establishment of grind size that optimally liberates the valuable mineral for efficient down-stream processing is of great importance for most mineral processing operations. Reasonably accurate comminution models as well as models of downstream separation processes may be found in the literature but their use in optimizing grind size is limited without an associated liberation model. In this work, an attempt has been made to address the above shortcoming by demonstrating how the effective parameters of the downstream flotation process may be predicted from the liberation characteristics based on the ore texture data for a disseminated nickel ore. In this regard, the liberation model based on linear intercept distributions of mineral and gangue proposed by King (1979) and its application to predict the flotation performance of an industrial plant demonstrated by Schaap (1979) may be considered useful contributions. However, while the model proposed by Schaap is simplistic enough, it is based on several assumptions due to the non-availability of intercept length measurements on the parent rock, in particular, on the extent of mineral exposure on the surface of comminuted particles. In this work, the linear mineral and gangue intercepts on polished specimens of a binary ore, comprising darker pentlandite as the valuable mineral and lighter barren host rock were measured using an image analyser. The resulting intercept distributions followed negative exponential distributions. Using the mean sizes of mineral and gangue intercepts, the proportion of liberated, compo-site and mineral occluded particles of a given size, the extent of mineral exposure on the surface of particles and their mean mineral contents were calculated using principles of renewal theory. The rock was then crushed and ground and different size fractions were floated. It has been shown that the parameters of observed recovery data based on 1st order kinetics such as the associated rate constant and ultimate recovery agrees well with those predicted from the quantities calculated above. This work has important practical implications since it can indicate variations in flotation performance arising from changes in mineralization within a large ore body.

Jan 1, 2014

By Edson Charikinya, Pierre-Henri Koch

"The extraction of mineral values from ore requires liberation followed by separation steps. Liberation is achieved by size reduction operations which are energy inefficient processes typically dominating the energy consumption in a mineral concentrator. As the grade of ore reserves declines, future viability of mineral operations will be determined by energy costs of comminution. The application of high power microwave energy to secondary crusher products has been suggested as a possible commercially viable thermal treatment method for reducing comminution energy and improving value mineral liberation. Recent studies have shown that microwave pre-treatment of coarse sphalerite ore particles (> 5mm) at specific microwave heating energies (1-3 kWh/t), induces microfractures and creates new crack surfaces. This suggests that subsequent crushing of these microwave treated particles could yield enhanced liberation. However, limited studies have been carried out investigating the mode of breakage and the extent of enhanced liberation in that case. The objective of this study is to develop numerical methods for quantifying the extent of enhanced liberation and mode of breakage in crushed microwave treated and untreated particles. Sphalerite ore particles representing small (-5+4.75) mm, medium (-16+9.5) mm, and large (-25+19) mm HPGR and cone crushed particles were microwave treated at specific energies between 1-3 kWh/t. Cracks in the ore particles before and after microwave treatment were analysed with QEMSCAN and numerical models of the measured particles (before and after microwave treatment) were developed in MATLAB. The propagation of random and non-random cracks was investigated by simulating comminution of the modelled treated and untreated particles. Results of this study demonstrate that the breakage mechanism and the liberation of valuable minerals from gangue in microwave treated and untreated particles is significantly different. This study contributes to the development of numerical tools to quantify crack propagation in heterogeneous ore particles."

Jan 1, 2018

By G. M. Wolfaardt, B. C. Qi

"From a lifecycle point of view, biologically digested sludge is a valuable product that should be reused if possible. In contrast to landfill and incineration, application of digested sludge comprises the recycling nutrients and organic matter and reflects the policy of resource conservation and sustainability in waste management. Sludge may be applied to agricultural land for further sludge treatment and improvement of the characteristics of the soil. The characteristics of sludge that affect its applicability for soil conditioning include moisture content, pathogens, nutrients and metals. In this paper, the use of solid anaerobic digestion sludge of the lignocellulosic residues to condition soil was investigated in regards to nutrient composition, water content/retention capacity, hygienic quality (contamination of pathogenic bacteria) and heavy metal adsorbing/releasing characteristics of the sludge.The digested sludge had approximately 44.5% free and immobilized water and 46.9% bound water. The water-holding capacity of the sludge was high. This was the first merit to apply the sludge to agriculture in dry areas. Secondly, the sludge was rich in macro-nutrients (N, P, K) and a series of micro-nutrients (Ca, Mg, Mn, Na, Fe, Cu, Zn, B). The water-soluble fractions of macro-nutrients in the sludge were found considerably low. This implied that the loss or leaching of the macro-nutrients from the anaerobic sludge to the aqueous environment be slow. The nutrients loss owing to leaching could be reduced. However, because of a lower macro-nutrient content of the anaerobic sludge, comparable to the chemical fertilizer, it is advisable that the anaerobic sludge be applied together with commercial fertilizer to the agriculture land. Thirdly, the anaerobic sludge had strong selective adsorption affinity for heavy metal ions; non-heavy metal ions such as K(I) and Ca(II) could be released easily from the sludge in a wide pH range, such as pH from 1.0 to 8.0. Since the metal toxicity to the environment mainly comes from the mobile heavy metal ions, the selectivity to adsorb heavy metal ions of the anaerobic sludge can be utilized to reduce the availability of heavy metal ions to plants and humans in aquatic environment. Fourthly, the anaerobic digestion under thermophilic conditions showed a promising disinfecting effect to the sludge, in contrast to the landfill digestion."

Jan 1, 2003

By Vladimir G. Kochnev

"Autogenous and semi-autogenous grinding (AG and SAG) have been considered a step forward in comparison to conventional grinding circuits with several stages of crushing and using ball (and/or rod) grinding mills. However, existing AG and SAG technologies still can be improved and have an immense potential from the viewpoint of economic benefits.Experience gained by the Technics & Technologies of Disintegration Ltd. (TTD) in the research of grinding processes shows that comminution in AG and SAG mills can be performed in a more effective way. The company’s approach comprises the following elements:- Novel mill design- New liners and lifters- Novel discharge grid design- Technique of treating material of critical particle sizeA novel mill of the cantilever type capable to operate in the AG and SAG mode has been developed. The cantilevertype mill has a high diameter to length ratio, which dramatically increases the throughput rate, and is characterised by high reliability, fast installation and low capital and operating costs.Tests of the new heel-shaped liners, originally aimed at improving the intact condition of diamond, indicated that they play an important role in the grinding process. Tests performed by TTD jointly with ALROSA, MINTEK and Anglo-American Corporation, demonstrated that the heelshaped liners provided the increase in the throughput rate varying from 30 to 80 % and the decrease in power consumption in the range 30-55 % for grinding of kimberlite and platinum-containing ores.Investigation of the influence of the main grid parameters on the efficiency of grinding led TTD to a special design of a mill discharge grid, with a radial location of openings, the slot width varying from the periphery to the centre and the grid surface provided with “heels”. The design allows one to control the particle size distribution of the ground product without affecting the grid throughput rate."

Jan 1, 2003

By Ghislain Bournival, Seher Ata, Yesenia Saavedra Moreno

"In froth flotation, frothers are commonly added to the pulp to modify the interfacial properties of bubbles. These properties may be modelled using commercial software packages. The volume of fluid (VOF) method was used to track the interface motion during the post-rupture oscillation of the newly formed bubble. The aim of this research was to provide an insight into the modelling of viscoelastic phenomena through the coalescence dynamics of two bubbles in solutions of various surface tensions using a three-dimensional computational study. Different surface tensions were used to simulate changes in methyl isobutyl carbinol (MIBC) concentration. The computational results were evaluated by comparing the oscillatory motion of the newly formed bubble for the different MIBC concentrations. For known MIBC concentrations, the deviations of the computational damping constants from the experiments were quantified, revealing possible deviations in the VOF surface tension model. In addition, the analysis provided insight into the flow patterns of the fluids and the effect of frother concentration on the velocity magnitude in the liquid and air phases. This analysis provided a further understanding of coalescence dynamic and post-rupture oscillation in froth flotation. Such a process is believed to affect the stability of particles at the interface due to the release of surface energy when the bubble surface is reduced.INTRODUCTIONIn froth flotation, bubble coalescence is an important phenomenon that is highly dependent on the interfacial properties of the liquid film between bubbles. It is known that the frother adsorption at the liquid-air interface changes the interfacial properties, resulting in an increase of surface elasticity and reduction of surface energy (Pugh, 2016). However, in a two-phase system, it is the frother type, concentration, frother molecule conformation at the interface and viscoelasticity properties that dictate film stability (Pugh, 2016). The viscoelasticity phenomena can be explained in terms of surface viscosity, which quantifies the energy dissipation at the interface and surface elasticity that represents the energy absorbed at the interface as result of bubble oscillation (Pugh, 2016). In the case of systems stabilized by nonionic frothers, it has been shown that surface forces alone do not account for film stability, but the viscoelasticity represents the ability to damp external disturbances in the thin film separating the bubbles and prevent coalescence (Santini et al., 2007)."

Jan 1, 2018

By Saveliy F. Kaplan, Valeriy N. Tsyplakov, Vasily N. Kovalev, Igor A. Agapov, Nikolai V. Vorob’ev-Desyatovskii

"Based on the experiments, a possibility of successful processing of double-refractory gold sulphide concentrates with a high content of natural organic carbon, which has a high sorption capacity toward gold chloride complexes, has been demonstrated. The proposed approach involves deep burnout of sorption-active organic carbon in an autoclave at a higher temperature and a longer retention time. INTRODUCTION It is known that one of the reasons why gold-bearing ores and concentrates are refractory is the occurrence of fine gold in sulphides (usually in pyrite and arsenopyrite) in ores and concentrates. In addition, refractory gold-bearing ores and concentrates also contain an organic carbonaceous material, which has a sorption capacity towards gold chloride complex, making the ore or concentrate even more refractory. In pressure oxidation, metallic gold is oxidized by Fe (III) aqua-ions and complex Au(Cl)4- ions are formed at temperatures over 180°C, in the presence of chlorides contained in ores. Complex gold anion is adsorbed on the organic carbon surface and then reduced to Au0; the chloride ion is regenerated and gold, adsorbed on organic carbon microparticles, is ultimately transferred to tailings (preg-robbing). Currently, there are several suggestions how to suppress preg-robbing (Simmons, 1998, Pyke, 1999, Rees, van Deventer, 2000, Zhao Jun-wei, 2008). It can be done by reducing the organic carbon content by processing (flotation, etc.),reducing chloride ion concentration by preliminary washing of concentrates in thickeners, reducing the adsorption capacity of organic carbonaceous material by introducing some organic substances that are strongly adsorbed on its surface (blanking agents), and reducing the redox potential of the slurry liquids by introducing neutralizing agents (limestone)."

Jan 1, 2018

By Edgar Schach, Tom Leistner, Markus Buchmann, Urs A. Peuker, Martin Rudolph, Marius Kern

"In this study, the flotation characteristics of a cassiterite-bearing fine-grained and complex skarn ore from a deposit in the Ore Mountains is investigated. The tests are performed using an oil-assisted column flotation approach to process very fine ore fractions and avoid losses of cassiterite into the tailings. First, process parameters are obtained for a finely ground artificial mixture of quartz, magnetite and cassiterite, simulating the real ore. Thereby, magnetite is used, as iron oxides can have a detrimental effect on the flotation due to a similar flotation behavior. In addition, they can act as a source of multivalent ions, which are known to reduce the concentration of collector molecules, active for flotation. Based on the results, selected parameters are further tested for cassiterite skarn ore from the Hämmerlein deposit including a pre-conditioning and a water exchange step to remove ionic contaminants. The process response is analyzed in detail by XRF (X-ray fluorescence) and MLA (mineral liberation analysis) to get a better understanding of the behavior of the single ore components. Sulfosuccinamate type surfactant is utilized as the collector, emulsifier and to reduce the froth destabilization through nonpolar oil. Sodium hexafluorosilicate is added as the depressant.INTRODUCTION Complex skarn ore deposits containing considerable amounts of tin, indium and other metals are located in the Ore Mountains region (Germany). In this study, a skarn ore from the Hämmerlein deposit was investigated. Due to the finely disseminated nature of this ore, past beneficiation attempts failed, and the ore was considered economically unprocessable. However, increasing resource demands brings it back into focus (Schuppan and Hiller, 2012). Cassiterite is the main tin bearing mineral in this ore. Due to its high density (~7 g/cm³), the predominant beneficiation technique is gravity separation (Angadi et al., 2015). Tin ores from disseminated deposits have to be extensively comminuted to reach a sufficient degree of liberation of the cassiterite grains. As cassiterite has a brittle nature, it is preferable enriched in small size fractions, during comminution (Angadi et al., 2015). Gravity separation methods become more and more inefficient for particles smaller 40 µm (Falcon, 1982), causing tin losses of up to 30 to 40wt.-% (Angadi et al., 2015). Thus, froth flotation of cassiterite was first utilized in Altenberg in the Ore Mountains as an additional processing step to reduce the cassiterite losses into gravity separation tailings (Bulatovic, 2010; Gruner and Bilsing, 1992). Although the reported lower size limits for an effective cassiterite floatability are often smaller compared to other minerals, the flotation performance is in general decreasing for small particle sizes < 10 µm (Trahar and Warren, 1976). Therefore, different approaches have been already investigated for the flotation of such fine cassiterite fractions to overcome the limits in particle size. Bilgen et al. investigated the shear flocculation of cassiterite with a sulfosuccinamate collector (Bilgen et al., 1994). The agglomeration flotation of cassiterite has been tested by Schubert et al. (Schubert et al., 1966), in which the selective coagulation of fine hydrophobic particles and oil droplets leads to an increase of the effective particle size. Recently, Leistner at al. investigated an oil-assisted agglomeration flotation for ultra-fine cassiterite ore fractions (Leistner et al., 2016). However, a poor response due to an increased concentration of Fe and Ca ions, unselective oil/gangue coagulation and froth instability, that is caused by oil/frother interactions, has been observed."

Jan 1, 2018

By Shankar Narasimhan

Data Reconciliation is a technique that has been developed more than fifty years ago and has been refined over the past few decades and is now being deployed routinely in several process industries such as refining, petrochemicals, mineral processing and hydro-metallurgy. The main aim of data reconciliation is to obtain accurate estimates of all process variables and parameters using plant measurements that are invariably corrupted by random errors and may also contain biases and other gross errors. These reconciled estimates are subsequently used either in offline exercises such as simulation, retrofitting, and de-bottlenecking or in online optimization and control applications. In this presentation, a brief history of data reconciliation, its assumptions, and uses are reviewed. New developments in this area are highlighted such as robust data reconciliation to handle model uncertainties, and reconciliation using identified models derived purely from operating data. Several case studies in the mineral processing industries reported in the literature are also highlighted to indicate the potential benefits of this technique.

Sep 1, 2012

By Stoyan N. Groudev, Ioannis Paspaliaris, Irena I. Spasova, Kostas Komnitsas

"Acid mine drainage waters generated in the uranium deposit Curilo, western Bulgaria, were treated by means of a constructed wetland located in the deposit. The waters had a pH in the range of about 2.5 - 4.1 and contained uranium, radium, some heavy metals (iron, manganese, copper, zinc, cadmium, cobalt, nickel, lead), arsenic and sulphates in concentrations much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The wetland covered an area of about 140 m2 and was characterized by an abundant water and emergent vegetation and a diverse microflora. Typha latifolia, Typha angustifolia and Phragmites australis were the prevalent plant species in the wetland but species of the genera Juncus, Eleocharis, Scirpus, Carex and Poa as well as different algae were also well present.The water treatment was started in July 2001 and until now (August 2002) the wetland effluents were characterized by pollutants concentrations decreased below the relevant permissible levels. The water flow rate through the wetland during this period varied in the range of about 0.2 - 1.0 l/s. The water clean-up markedly depended on the temperature but was efficient even in the cold winter months at air and water temperatures close to 0oC. The removal of pollutants was due to different processes but the microbial dissimilatory sulphate reduction and the sorption of pollutants on organic matter (viable and dead plant and microbial biomass) and clay minerals played the main role. Negative effects of the pollutants on the growth and activity of the indigenous plant and microbial communities were not observed."

Jan 1, 2003

By Kyle P. Flynn, Frank J. Hrach, James D. Bittner

ST Equipment & Technology, LLC (STET) has developed a processing system based on tribo-electrostatic belt separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. In contrast to other electrostatic separation processes that are typically limited to particles greater than 75µm in size, the triboelectric belt separator is ideally suited for separation of very fine (<1µm) to moderately coarse (300µm) particles with very high throughput. The high efficiency multi-stage separation through internal charging/recharging and recycle results in far superior separations that can be achieved with a conventional single-stage free-fall tribo-electrostatic separator. The triboelectric belt separator technology has been used to separate a wide range of materials including mixtures of glassy aluminosilicates/carbon, calcite/quartz, talc/magnesite, and barite/quartz. An economic comparison of using the tribo-electrostatic belt separation versus conventional flotation for barite / quartz separation illustrates the advantages of dry processing for minerals.

Jan 1, 2014

By L. J. Li, Q. Zhang, Z. H. Liu, Q. L. Chen

Phosphogypsum (PG) is an industrial waste from the production of phosphate fertilizer. The utilization of PG is restricted by its containing impurities, and the pretreatment is crucial to eliminating these impurities. The purpose of the research is to recycle pretreatment PG as raw material for preparation of a-calcium sulfate hemihydrate (a-HH) by salt solution method. The effect of pretreatment technologies of lime neutralization and washing on dehydration rate, phase composition and morphology evolution of a-HH were investigated by crystal water content analysis, XRD and SEM. Furthermore, the change of pH in the reaction process was also discussed in detail. The results show that the dehydration rate of conversion PG to a-HH increases and the corresponding induction period, crystal growth period and total time decrease with an increase in CaO dosage from 0.2% to 0.6%. In the presence of 0.4% CaO or 0.6% CaO, the a-HH presents a long hexagon-prism-shaped crystal with a purity of 94%, and the end face of a-HH presents polyhedron. The system pH sharply decreases with the reaction time under different CaO dosage, and the pH variation from the initial alkalinity to acidity. The main reason is that as the co-crystallized phosphorus dissolved and released HPO42-, and with the pH decreasing to 4-5, HPO42- transformed into H2PO4-. The dehydration rate of washing PG is lower than that of original PG. Compared with the original PG, a-HH with the larger width and smaller aspect ratio can be achieved from the pretreatment PG subjected to lime neutralization and washing, meanwhile the crystal surface is more smooth.

Jan 1, 2018

By Fedotov Pavel

One of the efficient means of ore disintegration during the processing is its volume breakage in such machines as roller-presses. Up to date neither the ore disintegration mechanism in roller-presses nor the reasons of their high efficiency are thoroughly investigated. In this work, the mathematical model of Finite Element Method of bad material disintegration in roller-press is discussed. The mechanism of the interparticle ore disintegration is traced.

Sep 1, 2012

By I. Gombköto

Mining and mineral processing operations are usually generating huge amount of tailings. These tailings often gives lots of maintenance work in order to protect environmental resources from heavy metals slowly leaching out of tailing are due to Acid Rock Drainage (ARD) process. Handling leakage could be active or passive such as using of Permeable Reactive Barriers (PRB). PRB?s are used worldwide treating underground contaminations, using different type of matrix materials. All generally used matrix material has its advantages and disadvantages such as selectivity, sensitivity of precipitation generation or not satisfying hydraulic conductivity. Nowadays cheap and effective matrix material which is ignorant to pore plugging caused by precipitation within the PRB could be one solution to the demands of the industry. The authors have been carried out an investigation at University of Miskolc on lignite as high humid acid containing material for determining the ability of heavy metal adsorption and pore plugging resistance. Moreover, using hydraulic and chemical simulation methods, complete PRB dimensioning protocol based on new lignite matrix had been introduced. Within the frame of this paper the results are going to be discussed.

Sep 1, 2012

By C. Stollberg

The recovery of valuable materials from electronic waste is of growing importance for the re-source management not only in the industrialized nations. Being a significant step in an innovative automated process for recycling of metals and plastics from used electric and electronic equipment, the results of the work introduced below, prove the applicability of microbial leaching of metals from printed circuit boards (PCBs) at industrial scale. Within the first project step, which started in March 2005, experiments in shaking flasks with a mixed culture of chemolitotrophic bacteria (mainly Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans) were carried out to study the solubilization of non-ferrous metals present in the electronic waste. It was found that the best results were achieved by means of a two-stage process in which leaching of these metals was carried out by acidified ferric sulphate solutions generated as a result of the prior bacterial oxidation of ferrous ions to the ferric state. Special reactor systems for bacterial generation of such solutions and for the subsequent leaching of non-ferrous metals from the waste were developed, constructed and tested under laboratory and pilot scale conditions. The optimum technological parameters such as concentration of iron ions, pH-value, temperature and presence of nutrients were established for both reactor systems. Parameters such as particle size, pulp density and flow rate of the suspensions being leached were established for the leaching process carried out under continuous-flow conditions. The complex flow sheet reflects a highly efficient technology on the basis of metal recovery, environmental effect and economical acceptance. The process was successfully implemented into an industrial demonstration unit.

Jan 1, 2014

By G. Weingrill, H. Flachberger, J. Neubacher

The so called Bublon®-process is an innovative process for the controlled expansion of volcanic glasses such as Perlite and for thermal treatment of other minerals. In this manner, functional light fillers with astonishingly altered physical properties can be manufactured. In contrast to conventional Perlite expanding processes no fossil fuels are burned in order to achieve the expansion. Instead, the feed material is heated electrically mainly by radiation based on heat transfer from heating elements. The main advantage is the better controllability of the production process. Therefore, the heating elements are segmented along the flow of the particles, hence in direction of the ongoing expansion. Overheating of the particles, which ultimately leads to the destruction of the particle surfaces and consequently decreasing the quality of the expansion product, can be reduced significantly. Due to flow characteristics and settling behaviors of fines the lower particle size limit of the feed in this process is restricted to not less than 100 µm. Otherwise process instabilities are to be expected. Manufacturing industry demands light and fine hollow microspheres. Therefore, a proven cooperation between Montanuniversität Leoben and Bublon GmbH was formed to develop a new process called ‘Bublite’. This issue was addressed by changing the conveying principle into a pneumatically conveying system transporting particles from the bottom to the top of the kiln by the means of a drag flow. This approach makes it possible to handle the difficult flow patterns in the kiln and to control the retention time of the particles in the heat transfer zone. As a result, it is now possible to expand very fine Perlite particles into a high quality functional lightweight filler with a glazed-closed surface. The dependence of the polymer industry on importing this kind of fillers from overseas can be reduced by producing it close to sites of demand. Also the Perlite mining and processing companies benefit from this technology because the mine lifespan and the output of the processing plant can be increased.

Jan 1, 2018

By E. V. Mezentseva, S. M. Okunev

"In the article there is set forth a development experience of JSC LEBEDINSKY GOK Beneficiation Plant concerning the plan of increase in the production volumes of the iron ore concentrate with Fe content more than 69.5%. There are considered the issues regarding implementation of the updated process scheme of the concentrate beneficiation using fine screening operation, its industrial tests have shown an exploitability of this development direction. There are described the issues relating to the ceramic filters for dehydration of the additionally-beneficiated concentrate, there are given the production and process figures achieved during the exploitation. The methods of the research. In the paper there have been used the following scientific research methods: the methods of system analysis, mathematical statistics, classification, comparison, modelling, observance, experiment. INTRODUCTION JSC LEBEDINSKY GOK is the largest leading enterprise for iron ore beneficiation and the unique RF producer of the merchant hot briquetted sponge iron (HBI) highly demanded by the consumers. Raw materials for hot briquetted iron production are fluxed pellets produced from iron ore concentrate with Fe content more than 69.5% (additionally-beneficiated concentrate). Strategic program of the plant’s development foresees expansion of production of the highly demanded products that imposes a necessity of expending capacity of the enterprise and implementation in production of modern processes and equipment having low resource intensity and ensuring in addition a high efficiency. Construction of the third stage of the HBI Plant became one of directions for the strategic development of JSC LEBEDINSKY GOK implemented in 2017 that caused a demand in the production volumes and filtration of the iron ore concentrate with Fe content more than 69.5%. Purpose of the work – to develop and to provide a rationalization for efficiency of the production process and filtration of the iron ore concentrate with Fe content more than 69.5% ensuring increase of production volumes and its prime cost."

Jan 1, 2018

By H. Araneda

Throughout Chile?s history, mining has consistently been a leading industry in the country. The 1990s marked the beginning of a boom in Chile?s mining industry, especially in copper mining, due to both foreign and local direct investment in the sector. Mining?s contribution to the GDP was 15.6% at current prices in 2009, and it accounts for 56% of the country?s exports. Chile?s copper market share reached 35% in 2009. The investment portfolio in mining in Chile for the coming decade has been estimated at 90 billion US dollars. The acute scarcity of human resources currently experienced by the mining sector in Chile will be accentuated in the coming decade as a result of this scenario of investments. The situation is, additionally, similar to the one confronted by other countries involved in the mining industry such as Australia, South Africa, Canada, and in Latin America includes, Peru, Colombia and Brazil. A study carried out by Fundacion Chile, ¨Labor Force in the Chile Mining Industry, Diagnostic and Recommendations, 2011-2020? shows the projected labor shortage for the operation of projects in the development stage, considering only the requirements of the process of extraction, processing, and maintenance. The demand, accumulated incrementally, will be around 115,000 technically skilled workers, professionals, and qualified workers. This figure refers to the operational work force, and does not include the human resources that will be required for the prior stage of the engineering and construction of the projects (brownfield and greenfield). The demand for technically skilled workers and professions for the stages of engineering and construction of the projects that have already received investments is estimated to be 190,000 people for the period 2012-2020. The peak of the demand for engineering is 2012, with a figure that surpasses the 12,000 professionals for all of the engineering specialties. The analysis of the formation of human resources at the tertiary level (where tertiary includes technical/vocational and academic degrees at the undergraduate level) for mining and related majors demonstrates that the programs are scarce with a bias toward theoretical contents and that they are excessively long (40% longer than comparable programs in Australia, Canada, and in OECD countries). The completion rates are low, especially in the technical-vocational programs, which have a completion rate of only around 30%. Finally, the rates of attraction of technically skilled labor and professionals towards careers in mining are insufficient to reduce the identified skill gaps. In the case of university professionals such as geologists, mining engineers and engineers in metallurgy, 80-90% will work in mining. In the case of graduates of relevant majors, that cover skills also utilized by other industries, not only mining?such as maintenance workers, operators of fixed and mobile equipment, etc.?the mining sector appears to be unattractive for reasons such as shift schedules, geographical location of work sites, and other factors. On the basis of the available diagnosis a strategy for the sector has been developed (Workforce Development and Skills Strategy) whose objective is (i) to define a Mining Qualifications Framework to identify the critical roles to be filled (ii) to start, with public resources, a ¨fast-track? training program to assure the availability of at least 28,000 operators (machinery operators, truck drivers, etc.) and maintenance specialists in 2015 (iii) to promote the development of training hubs for mining with learning technologies to train technical labor and professionals on the basis of world class standards (iv) to design and implement a campaign oriented toward the perception of mining as an attractive field of employment opportunity (v) to develop curricular innovations for tertiary education programs, on the basis of international benchmarks. Keynotes: Chile, mining, copper mining, skilled human resources

Sep 1, 2012

By Erico Tabosa, Kym Runge, Peter Holtham

"The distribution of turbulence in an industrial scale mechanical flotation cell and its effect on flotation kinetics was studied using a fully instrumented 3m³ cell. The cell was operated at a copper concentrator in Australia with different combinations of airflow rates, impeller speeds and sizes and cell aspect ratio providing a wide range of hydrodynamic conditions. An analysis of the overall flotation cell performance showed that the overall copper recoveries were very similar for the conditions tested. However, by decoupling pulp effects from froth effects it was possible to evaluate whether the changes made affected the pulp zone and/or froth zone responses. The analysis showed that the overall recovery has the potential to be up to 7% higher, if not limited by froth recovery. The cell hydrodynamics were characterised by the overall energy dissipation rate and, to understand the distribution of turbulence within the cell, localised measurements were made using a piezoelectric vibration sensor. By comparing the metallurgical performance of the cell with the different hydrodynamic conditions it was found that the collection zone flotation rate constant was not directly related to overall energy dissipation, as is commonly observed at laboratory scale, where energy is usually only changed by varying impeller speed. In this study, energy dissipation rate was varied using not only impeller speed, but also the size of the impeller and the cell aspect ratio. In these circumstances, the best correlation was found to be between the collection zone flotation rate constant and the distribution of turbulence, i.e. the size of the turbulent zone."

Jan 1, 2014

By Thomas Mütze, Anja Hirte, Ursx Peuker, Thomas Kuhn

"The comminution behavior of two ferromanganese nodules samples of the equatorial northeast Pacific has been examined as a basis for the separation of two kinds of metal-rich layers. Those layers were finely grown together during nodule formation and are one reason that the exploration of deep-sea minerals calls for the development of new mineral processing concepts. Therefore fundamental analyses of the fracture behavior have been made under compressive and impact stress. Further experiments took focus on the crushing behavior in a jaw crusher and a small scale impact crusher as well as the milling behavior in a dry vibrating mill, a wet planetary ball mill, and a wet agitated ball mill. The comminuted products were characterized by PSD, particle shape, particle density, and porosity. The experiments show a low stress resistance of the ferromanganese nodules. Compared to compressive stress, impact stress turned out to be the more effective for crushing. Both samples showed no significant difference in the comminution behaviour which makes differing mechanical treatments unnecessary. In both cases particle sizes below 1 µm were achieved by wet grinding. This particle size is necessary to separate the two kinds of metal-rich layers which is part of continuative studies."

Jan 1, 2014