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By Jens Markowski

The EU Directive 2000/53/EC on end-of life vehicles (ELVs) states that in 2015 at least 85 wt.-% of a vehicle has to be reused or recycled. This result in the obligatory need to separate additionally metallic and other components of the automotive shredder residues (ASR), so that they can be professionally prepared for recycling and reuse further. Currently the iron-containing fines of ASR are deposited as it is not possible to process in blast furnaces due to its particle size (< 4 mm), composition and material properties. Additionally problems are also caused in handling and transportation (dust) of the material. This work focuses mainly on the ASR materials utilization in blast furnaces. Material was further separated into two consecutive fractions by carrying out repeated crushing and magnetic separation twice. The two fractions have significantly higher iron content (up to 75 wt.-%) compared to the initial material mixture. The materials were assessed for their usage in blast furnaces based on the possible pelletisation with and without binders, stability of pellets, shape and size of pellets, etc. Pelletisation of the material was carried out with a single mould pellet press. Further lignite coal was added to the mixture as additive which improved the pelletisation behavior and the mechanical stability of pellets. Lignite coal was chosen as a reducing agent in the blast furnace process contributing towards additional savings in energy supplied. The experiments reveal that the production of pellets from iron-containing fines is possible with a lignite coal admixture of about 15 wt.-%. These pellets displayed good mechanical stability and can be used in blast furnace processes in recovery of the recyclable metals which are currently not recycled. The recycling of not yet recyclable metals would reduce the deposition and can be easily adopted into the economic cycle by their utilization. Keywords: Automotive shredder residue (ASR), FE-fines, pelletisation

Sep 1, 2012

By Charlene Gokhale

Geopolymerisation has emerged during the last few years as an industrial and ecological approach to construction and waste management. By utilizing waste materials and their reactive properties, it is now possible to create geopolymers systems that not only mechanically durable enough to be used as construction materials but are also potential stable immobilisation systems for toxic waste. Previous studies by Van Jaarsveld et al. (1997) and Van Jaarsveld et al. (1998) have reported on the numerous applications of geopolymers in the immobilisation of toxic metals. Research into the possible utilisation of geopolymers as an encapsulation media for organic waste has however been rare. This paper therefore provides an insight into the possible utilisation of geopolymers as a binder for hazardous organic materials.

Jan 1, 2003

By Di Liu, Yongjun Peng

"It was identified that clay minerals adversely affect fine coal flotation through slime coatings. In the study, it was interesting to find that an anionic polymer dispersant, lignosulfonate, successfully mitigated the negative effect of clay minerals in coal flotation using fresh water, but in saline water, it exacerbated coal flotation.In order to understand the mechanisms underpinning the different behaviour of lignosulfonate in coal flotation using fresh and saline water, the adsorption isotherm, and dynamic light scattering (DLS) measurements were conducted in this study. While DLS monitored the molecular conformation change (swelling or shrinking) of the polymer in fresh and saline water, adsorption isotherms enabled polymer adsorbed amount on clay and coal mineral surfaces to be determined. It was found that lignosulfonate adsorbed on the coal and clay mineral surfaces providing effective electrostatic repulsions and resulting in a mitigation of clay minerals from coal surfaces in deionised water. In the presence of saline water, however, polymer molecular conformation changed. Polymer molecules were compressed and adsorbed in form of aggregates. The adsorption amount of lignosulfonate on clay minerals increased in saline water. A low dosage of lignosulfonate could not provide sufficient electrosteric repulsion to disperse clay minerals. Moreover, the high adsorption amount of the polymer on coal and clay surfaces led to a more hydrophilic coal surface, and coal flotation was therefore depressed in saline water. This study provides a new insight into understanding the role of anionic polymeric dispersants in mineral flotation using different quality water."

Jan 1, 2014

By Carlos de F. Gontijo

The flotation of quartz particles was studied over the particle size range from 0.5 µm to 1000 µm and for advancing water contact angles between 0º and 83º. Flotation was performed in a column and in a Rushton turbine cell. Particle contact angle threshold values, below which the particles could not be floated, were identified for the particle size range 0.5~1000 µm, under different hydrodynamic conditions. The flotation response of the particles, either in a column or in a mechanically agitated cell with a similar bubble size, was comparable. Turbulence plays a role, as does bubble-particle aggregate velocity and bubble size. The stability of the bubble-particle aggregate controls the maximum floatable particle size of coarse particles. For fine particles, the flotation limit is dictated by the energy required to rupture the intervening liquid film between the particle and bubble. Flotation of very fine and large particles is facilitated with small bubbles and high contact angles. These results greatly extend our earlier observations and theoretical predictions.

Jan 1, 2014

By Gülay Bulut, Ünzile Yenial

"Water composition has a significant effect on flotation. A better understand the role of water composition in flotation is very important for process quality and performance. Based on source of process water, the concentrations of the dissolved ions, hardness, contaminants and residual composition of reagents can varied in the process water. The various water resources employed during lead and zinc flotation caused activation, depression or selectivity effects on minerals due to the presence of different ions in solution. Metal ions in these water resources were adsorbed on the ore, whilst ions associated with gangue minerals were released into the flotation pulp.This paper includes a research for the effect of different water compositions on lead and zinc sulphide flotation. Experiments were carried out five types of water such as tap water, recycling water, tailing dam water, underground mine water and sea water. The ore sample was obtained from Esan Balikesir-Balya mine. The mineralogical study of ore sample shows that it contains mainly galena, sphalerite, pyrite, hematite, quartz, diopside, epidote, calcite, and chlorite. It is found that recycling water and tailing dam water has a positive effect on recovery of lead and zinc minerals and detrimental effect on content of both minerals. This result may explain with remaining reagents in these waters. Underground mine water and tap water gave nearly the same recoveries of zinc. Sea water affects the recovery lead and zinc negatively."

Jan 1, 2014

By A. Sand

Within stamp-charged coke making a large volume of coal is compacted to one single coal cake before entering the coke oven chamber. This is done by means of several falling stampers in a stamping machine having a mold nearly of the oven?s dimensions. Producing a high quality coke also from inferior coals requires a cake density of approximately 80% of the coal density. Besides that the industrial stamp-charging process demands a minimum mechanical strength of the coal cake to move it from the stamping mold into the oven chamber without failure. Densification and the build-up of cake strength were investigated earlier in stamping tests using a micro-stamping device. The quantities derived from these tests (as e.g. cake density or porosity) represent average values for the entire cake. Statements describing the local compaction state at different heights are difficult to achieve without destructing the cake. In order to gain better insight into the densification process and the inner structure of the coal cake a computational model based on the discrete element method (DEM) has been set up using 2 and also 3-dimensional simulation software. The stamper?s position and velocity as well as the force acting on the stamper were monitored and the model?s response was compared against measurement data from laboratory stamping tests. It was possible to reproduce the force and displacement pattern of the stamper in response to the viscoelastic properties of the cake using standard DEM bonding and contact models. Furthermore, the rearrangement of particles in response to the compaction by the stamper was tracked by calculating their displacement at the point the stamper hit the coal surface. The latter can also be used as indicators of particle deformation or breakage. By defining control points at different heights the particle displacement, stress and strain rates, porosity could be studied at different heights. Keywords: coke making, coal stamping, compaction, agglomeration, DEM, simulation

Sep 1, 2012

By Carlos Collado, Oscar Jimenez, Francisco Diaz, Rodrigo Bernal, Carmen Salinas

Water is a strategic resource for the mining industry. The rising cost has forced the industry to become more efficient in their use, reduce and recycle waste as much as possible. The importance of having a reliable water balance is increasingly urgent, because the resource is scarce and vital to the sustainability of human life, animal and ecosystem. Conventional flowmeters can suffer disruptions or failures by corrosion, fouling, presence of elements in the water as acids, salts and suspended solids. Use of radiotracers is advantageous to determine fluid velocities that are transported through pipes, as they are detectable by means of the radiation emitted, the same way for surface flows, such as natural watercourses and drainage from tailings dams, fluorescent tracers are those with the best advantages. For velocity measurements in pipelines a Iodine-131 tracer solution, around 5 mCi was injected into the suction of the pumps. The technique used is the transit time between detectors at known distances and determining the time of passage of the radiotracer. For measurements of surface fluxes using the fluorescent tracer Rhodamine WT by tracer dilution technique, injecting the tracer at a constant rate and measuring it known concentration diluted downstream. This work has been performed in Minera Los Pelambres, located in the IV Region of Chile, measuring the flow rate pumped from 12 pools with 1-7 pumps operating, obtaining speeds of 0.56 to 2.62 m/s. In pumping wells three facilities have been measured at speeds of 0.111-0.223 m/s, plus six surface flows with flow rates of 8.45 to 357.2 L/s.

Jan 1, 2014

By Yu. Gurevich, M. Teremova, I. Prokopev, A. Razvjaznaya, N. Algebraistova

"The objective of this work is the scientific justification and development of efficient and environmentally-friendly method of bulk concentrate preparation for selection with application of microbiological practices. This research suggests to apply Pseudomonas Japonica bacterial culture to the bulk concentrate before the selection circuit in order to clear the surface of sulphides from the xanthate skin. It is also suggested to apply bacterial consortium Ochrobactrum ?nthropi and Pseudomonas aeruginosa JCM 5962 for desorption of diesel residual concentrations. High-efficient and environmentally friendly method of copper-molybdene and lead-zinc bulk concentrate selection was developed based on theoretical and experimental research work with application of microbiological practices. In comparison with conventional methods (steaming, sodium sulphide washing) the above suggested bio-technological method of bulk concentrate preparation before selection cycle will allow to reduce material and power expenditures, and it is also environmentally friendly. INTRODUCTION High-efficient selection of sulphide bulk concentrate is gained exclusively after collecting agent is removed from mineral surface. Therefore, the problem of bulk concentrate preparing before the selection cycle is acute, since the further technological parameters of the subsequent separation depends on the effectiveness of pulp preparation. Existing traditional ways of bulk concentrate preparation. such as washing or steaming, are characterized by high energy and material costs in industrial conditions [1,2]. The microbiological treatment before separation of the bulk concentrate into different kind of concentrates appear one of perspective processes for treatment of bulk concentrates [3,4]. At the present time, the world practice of processing mineral raw materials demonstrates the wide application of technologies using microorganisms: bacterial leaching and oxidation, purification of industrial wastewater. This is due to the fact that biotechnological methods are environmentally safe, low-cost, and suitable for refining complex ores and raw materials of industrial origin."

Jan 1, 2018

By Zhongxue Li, Cuiping Li, Xiaoyun Hu, Yiqing Zhao, Huaying Wang

"Under the auspices of World Federation of Engineering Organizations’ Committee on Engineering and the Environment (WFEO-CEE) and Society for Mining, Metallurgy and Exploration (SME) Task Force on Sustainability and Mining (TFSM), and aimed at helping raise global understanding on and promote capacity building of risk management, this paper presents a framework and prototype of toolbox or knowledge warehouse for facilitating the application of risk analysis, mitigation and management techniques (RAMT) in the mining and minerals sector. The conception, design and implementation of the intended system of knowledge warehouse of risk analysis, mitigation and management techniques (KWoRAMT) are outlined. The system architecture of KWoRAMT is based on a browser/server (B/S) structured platform with web oriented interfaces and composed of data base, knowledge warehouse, searching mechanisms, and risk assessment methodologies. The knowledge sources for KWoRAMT will come from the TFSM expertise and Internet, including laws and regulations, codes of practice, standards, guidelines and best practices. The functions and outcomes of KWoRAMT consist of guided navigations with web links, categorized risk tools, annotated best practices with cases, and integrated risk approaches and solutions based on typical risk methods. Risk categories include those impacting on mine safety, mine occupational health, and mine community environment throughout the whole of mine life cycle from exploration, construction, and exploitation and processing to post-mining closure. Mining associated hazards will be identified and linked by vulnerability onto risk receptors through pathways. Risk management techniques for assessing impacts and consequences of mining induced hazards will be categorized with their pros and cons or strengths and weaknesses. Best practices and significant cases including experiences and lessons with problems, solutions, and recommendations on how solutions would be derived will be illustrated. Integrated risk approaches based upon typical methods will be developed for alternatives and actions."

Jan 1, 2014

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 Hiroshi Sasaki, Herman D. Mendoza

"The surface-chemical property of nickel slag fiber was modified in aqueous media in order to act as an active and efficient collector of colloidal amorphous silica from geothermal effluent. Colloidal amorphous silica (0.05 µm) from geothermal wastewater causes operational and ecological problems. It clogs geothermal pipes and waterways, and when disposed to the environment poses hazardous effects on both the flora and fauna ecology. Because colloidal amorphous silica is extremely fine and remains in suspension in aqueous media, conventional solid/liquid processes to remove colloidal silica from its bulk liquid are rendered ineffective.A rapid separation technique is then developed to remove effectively amorphous colloidal silica from its bulk liquid by attaching the extremely fine particles of silica onto a nickel slag fiber coated with magnesium hydroxide, Mg(OH)2. The nickel slag fiber has the following characteristics: a high surface area and predominantly possesses negative charge in aqueous media with an iso-electric point at pH ~2.5. When soaked and saturated with Mg(OH)2 solution, the surface of the nickel slag fiber becomes coated with fine and compacted Mg(OH)2 precipitates. This modifies the surface- chemical property of nickel slag fiber transforming the negatively charged surface into a positively charged surface in aqueous media with an iso-electric point of around pH 11.8, which corresponds to the iso-electric point of Mg(OH)2. When geothermal effluent containing negatively charged colloidal amorphous silica particles (i.e.p. of silica is pH 2) is passed through a column-bed packed with surface-chemically modified nickel slag fibers under natural pH conditions, the colloidal amorphous silica particles are recovered by attachment onto the surface of the surface- modified nickel slag fiber. The recovery of colloidal amorphous silica by attachment is 97-99%, resulting in the production of a relatively clean and silica free output. Aluminum hydroxide, Al(OH)3, was also used to modify the surface –chemical property of the nickel slag fiber. In the same way, it also exhibited a positive response with the collection of colloidal amorphous silica from its bulk liquid, but yielding a lower recovery of 90%. This may be attributed to the lower surface potential and iso-electric point of pH 9.3 for Al(OH)3. The separation process was evaluated and analysed using existing potential energy theories. Figure 1 shows a micrograph of the surface of an unmodified and the Al(OH)3 –modified surface of nickel slag fiber."

Jan 1, 2003

By Markus A. Reuter, Jacques J. Eksteen

"The modelling of bath type furnaces tends to be either fundamental in nature or total empirical ""black box models"". While models of the first kind are robust, they tend to lack accuracy, in cases where they are to be used for process control, and may take an overly long in development time. On the other hand, black box models tend to lack robustness of prediction for all circumstances and tend to be limited to interpolate based on historical data. While this may very often provide short-term accuracy, the models may have problems with stability in the long term. Moreover, the model structure may not reflect any of the fundamental properties of the system and remains opaque to fundamental analysis. The aim of the model development is in obtaining a model that have robustness, high accuracy, a short development time and which is adaptive to a changing environment. The models are specifically developed for on-line decision support or control of furnaces. The modelling approach is evaluated for a chromite bath smelting furnace. The role of systems analysis, mass balance smoothing, thermodynamic analysis are integrated into one generic algorithm for bath type furnaces. Not only are fundamental process relationships such the mass and energy balances satisfied through a scientific method of data reconciliation; the proposed modelling approach allows adaptive prediction, the first step towards predictive control or metallurgical decision support.It is shown that neither an ARMAX model only, nor a purely equilibrium model only, could predict the dynamics of the process very well. However, a combination of the two approaches more than doubled the accuracy as measured by the R2. It was noted for carbon dissolved in the alloy, that the improvement in R2 in using a hybrid modelling approach was more than the sum of the R2 of the individual traditional approaches. Similar improvements in modelling performance were noted for all other species.It shows further that process dynamics may totally overshadow the effect of thermochemical equilibrium (even when the thermochemical equilibrium prediction includes the recycled alloy and slag heels as additional feeds). The exclusion of process dynamics therefore leads to erroneous results."

Jan 1, 2003

By Han Long, He Fayu, Sun Chuanyao

In global mining sector, when people mention "China Factor", usually they refer to China’s huge demands for mineral commodities, which had been driving the world mining industry into late "Super Circle". Few people pay attention to Chinese research capabilities and resources, which actually grows with Chinese economics in last three decades in such a soaring speed that you can simply feel it by the number of papers and attendees in recent IMPCs. In China, currently there are 33 universities and colleges where mineral processing discipline is established, and more than 20 research institutes dedicated in mineral processing area, with the largest number of students, teachers and researchers in the world. Due to the characteristics of Chinese mineral resources, Chinese researchers have made tremendous efforts on R&D of the process and reagents for those low grade, fine dissemination, and complex minerals resources, such as low grade hematite, diaspore, complex poly-metallic sulphides, as well as those minerals rich in China, including scheelite, cassiterite, and rare earth etc. with a special emphasis on the comprehensive utilization. Those research achievements not only successfully commercialized in China, but also have great potential for international cooperation. With continuation of globalization , Chinese government has been encouraging the international R&D cooperation in various areas at all levels, and the funding mechanism is well established with more 400 projects were sponsored in last year,in which,however, the mineral processing related projects are very few. Considering the fact that a large number of Chinese companies or Chinese capitals investing in the mining sector worldwide, more opportunities for international cooperation in this filed wouldbe emerging and increasing, while the factors like complementary, IP, government policy, system and culture difference still need to be addressed properly.

Jan 1, 2014

By Paul W. Cleary

"Particle scale simulation of industrial particle flows using DEM (Discrete Element Method) offers the opportunity for better understanding the flow dynamics leading to improvements in equipment design and operation that can potentially lead to large increases in efficiency, throughput or product quality. DEM has been used for modelling many industrial applications, particularly milling. This includes ball and rock motions and power consumption in ball mills, AG and SAG mills, vibrational segregation, flows in rotating drums, operation of dragline excavators and hopper flows. In mineral processing, DEM has been concentrated on mills because of their critical importance. However DEM also offers the opportunity to improve many other parts of mineral processing operations. These areas often do not receive the attention that the key comminution equipment commands, but can become critical when they fail or under-perform. Importantly their assessment/improvement using DEM is often much more feasible because of smaller problem sizes and the absence of poorly understood physics such as breakage. In this paper we describe DEM simulations of four important pieces of non-comminution equipment that are commonly found in or near mineral processing plants (these are shown in Figure 1):"

Jan 1, 2003

By Sanggono Adisasmito

"The quality of the higher education in Indonesia is being improved by implementing a program financed by the World Bank under a project named QUE (Quality for Undergraduate Education). The investments are provided to selected study programs through a competitive selection process. The grant finances staff development, the purchase of equipments, textbooks, consumables, technical assistance, and incentives for outstanding faculties such as teaching grants, project grants, lecture note awards, and educational policy studies. These additional investments are provided to produce chemical engineering graduates that will compete beyond the national market.Chemical Engineering Department of Institut Teknologi Bandung in Indonesia has been selected to receive the QUE grant beginning the year 2000 and ending the year 2004. The department is actively involved in the mineral processing issues, particularly in the aspects of energy supply and the environmental protection. The activities are distributed in different laboratories and areas of expertise, such as: thermodynamics and utility systems, process equipment, chemical reaction and catalysis, microbiology and bioprocess engineering, process control, ceramics, as well as polymer and membrane technology. The main objectives of the QUE project are to improve the undergraduate program in the following aspects: Relevance, Academic atmosphere, Institutional management and commitment, Sustainability, as well as Efficiency and productivity, or abbreviated as RAISE. At the end of every fiscal year, the progress of the program is evaluated to measure the effectiveness of the project.The achievement of the QUE project objectives were assessed using performance indicators developed during the program design. There are six indicators to measure the performance of the individual program of study, such as: (1) Admission Test score, (2) average students' Grade Point Average (GPA), (3) average graduates' length of study, (4) graduates' waiting time before getting first job, (5) Test of English as Foreign Language (TOEFL) score, (6) Graduate Record Examination (GRE) score. Essentially, the RAISE evaluation criteria will be used to perform three main functions, such as (1) to measure the achievement through the six quantitative performance indicators, (2) to support the progress of evaluation and reporting throughout the implementation of the program, (3) to provide a universal framework for qualitative evaluation."

Jan 1, 2003

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 Claudio Bisso, Javier Vargas, Charles Lozano

"This paper summarizes the activities performed to predict SAG milling throughput at Minera Esperanza. Having highly reliable geometallurgical models aided by the new computer tools and specific metallurgical testing to rely on has become a major issue in recent times due to their impact on the business. Minera Esperanza’s SAG throughput model was constructed by characterizing the ore feed and operational parameters of the plant. Producing a robust model required satisfying number of requirements for the parameters used for both the ore and the plant as follow: 1) geologic and geometallurgical characterization parameters; and 2) parameters of a plant running at the rated production under optimum operating conditions. Obtaining these parameters required increasing the quantity of samples and metallurgical testing through drilling campaigns, mapping the drill holes and putting samples through various comminution tests while sampling all operational flows at the plant to obtain the metallurgical information for the operational parameters. The information was entered on the JKSimMet software to enable a throughput model to be developed to output SAG mill throughput predictions that are very close to actual throughput figures, i.e., accurate within a range of 2% on a monthly basis."

Jan 1, 2014

By Bern Klein, Givemore Sakuhuni, Libin Tong

The use of continuous discharge centrifugal concentrators introduced in the early 1990’s for recovery of gold associated with sulphides has introduced a novel application niche for gravity concentration which could not be realized with the low mass yield batch and semi-continuous concentrators. A typical application is scavenging gold associated with sulphides from flotation tails which has potential to increase productivity by reducing gold loss to tailings and lower grinding cost by using a coarser grind. However, the full potential of this technology has not been fully exploited partly due to the lack of reliable small sample procedures to demonstrate applicability. This paper introduces a bench-scale procedure developed to characterize the Knelson Continuous Variable Discharge concentrator (CVD) for scavenging gold from flotation tails. The procedure code named gravity release analysis was derived from standard flotation release analysis. It is a modification of the gravity recoverable gold and gravity amenability test in order to best simulate continuous centrifugal concentration. Based on this iterative procedure, a gravity release index similar to the flotation rate constant, for measuring individual mineral gravity susceptibility for an ore is introduced which can be a useful quantitative measure to both predict application of centrifugal concentration and for plant design. The gravity release analysis procedure was tested on a polymetallic flotation plant tailing at Myra Falls, BC, Canada and results show that it can predict CVD performance. The gravity release index for gold was observed to decrease with each successive cleaner stage showing that the initial stages recover liberated gold whilst successive runs recover gold associated with sulphides and or gangue. The difference in magnitude of the gravity release index for different mineral species shows the species separable by centrifugal concentration.

Jan 1, 2014

By Gideon Chitombo

"Mining is a "continuous" process of dependent breakage and materials handling stages, from the initial breakage of the in-situ rock, extraction from the pit or underground, and finally to the surface stockpile and downstream processing. Over time, underground and in-pit mining activities diverged into two separate disciplines, each using a variety of in-situ breakage techniques and surface activities, with processing techniques dependent on mineralogy or grades. This artificial separation of underground and open pit activities was exacerbated when the two became increasingly managed as separate cost centres rather than as an integrated unit. Mass mining essentially began in 1903 when metallurgist Daniel Jackling initiated the world’s first open pit, mining system at the Bingham Canyon porphyry copper deposit in Utah. The term mass mining has since been construed to mean large open pits and cave mining methods, including their variants. These methods are largely non-selective, involving the mass extraction of a deposit irrespective of the uneven distribution of grade and mineralogy. The advantages of mass mining have historically applied mostly to low grade, large scale deposits. With the depletion of mineral reserves closer to the surface, however, new deposits are deeper, lower grade and mixed with more impurities. These and other factors make extraction more difficult and costly. Mass mining is moving rapidly into a new and less certain environment where revolutionary changes are required to effectively deal with future challenges which are technical, economic and environmental (licence to operate). This keynote address presents current initiatives being considered for the next generation of both underground and surface mass mining systems in order to significantly reduce lead times and mining costs (CAPEX and OPEX), substantially increase productivity and meet license to operate requirements. The address is designed to solicit discussion on how better integration of mining and processing can become a platform for these next generation of mass mining systems and can also help the industry deal with the future challenges."

Jan 1, 2014

By B. S. Moroney

Elemental distribution varies widely in the ores, minerals and beneficiated products depending on the constituents. Accurate analysis of each element present in various beneficiated products is utmost required to assess the grade in view of zero waste technology. Hence, the suitable methods and instrumental technique is of prime importance as the distribution of various elements differs in the beneficiated products. Conventional classical technique of analysis is absolute and due to this, it has not become obsolete. Besides, it is much needed for making standards for various relative techniques. Instrumental techniques comprising of X-ray fluorescence, Induced Coupled Plasma Analyzer, Carbon-Sulphur Analyzer, Atomic Absorption Spectrometer etc. are important for quick and accurate analysis. However, the selection of these instruments depend on the nature of material to be analyzed. This paper highlights the importance and use of various methods/techniques and instruments involved in the analysis of various ores, minerals and beneficiated products. Keywords: wet classical, x-ray fluorescence, induced coupled plasma analyzer, atomic absorption spectrometer

Sep 1, 2012