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By David Verrelli, Melissa Kistner, Leanne Smith, Chris Aldrich, Lidia Auret, Warren Bruckard

In this investigation, different mixtures of realgar and orpiment particles were floated in a laboratory batch flotation cell and multivariate image analysis was used to estimate the arsenic content in the froths. The analysis was based on the froth colour, as well as extraction of three groups of textural features, namely those based on grey level co-occurrence matrices (GLCMs), wavelets and local binary patterns (LBPs). Collectively, these features provided better information on the arsenic content of the froths than any one of the individual groups of features. Partial least squares models could explain approximately 78% of the variance in the arsenic by using all the features combined. The colour content, particularly the green component in the red-green-blue (RGB) features, provided almost as much information as each of the three sets of texture-base features individually.

Jan 1, 2014

By Juan B. Yianatos

"After almost 100 years, since the first commercial application began in Australia, flotation has shown an extraordinary growth and nearly 2 billion tons of ore per year are presently treated by flotation processes. During this time flotation has promoted a wide scope of research activities ranging from fundamental chemistry and hydrodynamic studies to studies of industrial operations. In general, fundamental studies have been mainly related to ideal situations. In recent years, however, large efforts have been focusing on achieving a better insight into the actual sub-processes provided by the development of new and more sophisticated instrumentation. Since the massive incorporation of flotation columns, around 15 years ago, a renewed interest in flotation fundamental studies, process modelling and new cell designs have been observed worldwide. The key role of the froth has been recognized as an independent and sometimes rate limiting process step. Thus, separation of pulp and froth process stages seems the most appropriate in terms of process modelling, diagnostic, design and scale-up purposes.In relation to flotation equipment development, until the middle of the 1970?s, only the sub-aeration mechanical cells were dominant. Since the 1980?s, the use of pneumatic cells and forced air mechanical cells has emerged strongly. Also, in the last decade, flotation equipment has shown a dramatic increase in size, reaching values of 200m3 in unitary mechanical cells and more than 300m3 in columns. The general feeling, however, is that, despite the great advance observed in terms of process knowledge, the mechanisms and principles of industrial flotation cells design and scale-up are still not fully understood.Advances in process instrumentation and control now in use allow for more efficient operations, both in metallurgical performance and savings in operating costs.INTRODUCTIONFlotation is a widely used process within the minerals processing industry, as well as being used for water treatment and de-inking of recycled paper. Froth flotation started in Australia at the beginning of the 20th century and since then flotation technology has made significant advances. Flotation was firstly applied to sulfide ores. The largest tonnages treated by flotation are copper and copper/molybdenum ores, handling about 50% of the total ore processed. Also significant are phosphate, iron ore and coal treatments. At present, Chile is the foremost copper producer in the world with around 35% of the world?s production. Figure 1(a) shows the evolution of copper production in Chile over the last decade. The total amount of fine copper produced in year 2001 was 4.7 million tons, from which 3.2 million tons was processed by flotation while 1.5 million tons went through LIX-SX-EW processes, which also showed significant development during the same period (Anon, 2001). The total flotation treatment of copper ores in Chile is about 325 million tons per year (Anon, 2002), so the world treatment of copper ore by flotation can be estimated at about 1 billion tons per year. Consequently a total of nearly 2 billion tons of ore per year is presently processed worldwide by flotation (Fuerstenau, 2001). In order to handle the higher tonnage of low-grade ore, a worldwide trend towards the development and use of larger flotation machines began in the 1960?s. Figure 1(b) shows that the trend became extremely marked from the beginning of the 1990?s, which is consistent with the strong increase in copper production during the same period."

Jan 1, 2003

By V. Grujic, M. Grujic, D. Salatic

"Two areas are involved in the research work of the comminution process (crushing and grinding). The first one involves the changes of the size class distribution values that are definded by the differential equations in the function of the ore property and working conditions. The second area involves the comminution of the different levels in order to optimize the working parameters and to decrease the operational costs in the grinding process.We have studied, in detail, the possibility of functioning the crusher at the maximal loading, over 4500 kN, ball mills with diameters larger than 5.0 m and semiautogenous mills with diameters larger than 10.0 m.Using the computers, we have achieved the maximal loading range of the crusher, over Fc ? 4500 kN in the crushing process. In the grinding process, using the adequate differential equations in the automation process, we have established the correlation between the pulp mass capacity in the mill, pulp dencity, ore fineness in the pulp and recirculating ore charge.With the appopriate text, equations and graphs, this paper shows the results of our several years research work in the laboratory and in the ore comminution plant of Majdanpek Copper Mine."

Jan 1, 2003

By N. S. Phala

Declining gold grades, mineralogical complexity of ore bodies, increasing input costs, more stringent conditions in the licenses to operate, and uncertain gold price dynamics combine to exert significant ongoing pressure on margins of gold producers. Innovative approaches of extracting the metal from its ores are required to realize value from existing and future assets. In a conventional gold processing plant, size reduction of mined ore to produce floatable or leachable product is a significant cost contributor. A step change in cost reduction will be attained if radically energy efficient grinding approaches can be developed, replacing tumbling mills. In the path towards that goal, some quick wins are possible through waste rejection before grinding, and pre-treatment of mill feed to reduce grinding energy demands. Gold locked in complex mineralizations puts pressure on margins by increasing cost per oz (typically high $/t and low metal recoveries) in the hydrometallurgical steps. Gold miners are primarily price takers. The current narrow range of gold uses (predominantly investment and jewellery) is not an entirely desirable state. Some diversification into commercial uses would potentially be a price stabilizer. In this paper, promising research directions, some not always fully explored in the gold metallurgy research space, are highlighted to stimulate radical innovation for substantial value enhancements. The author strongly believes a shift from a traditionally conservative and incremental innovation approach to a more aggressive one, across all aspects of the gold metallurgy value stream (processes to products), is what the industry needs. Keywords: gold metallurgy value stream, thiobaccilus ferroxidants, HPGR

Sep 1, 2012

By Larry A. Cramer

"Three primary drivers are setting the trend for base and precious metal processing . they are: continued low real base metal prices, environmental concerns, and continued high prices for PGM.s. Low base metal prices are increasing the search for economies of scale and company consolidation as well as the development of some hydrometallurgical technologies. Environmental concerns are pushing for continued reductions in SO2 emissions and hydrometallurgical technologies. The high prices for PGM.s are driving major expansions and a focus on minerals processing recoveries and, to a lesser extent, reductions in the refining metal lockup.In nickel, HPAL operations on laterites have failed economically but Inco is still pursuing some alternatives. BHP-Billiton and others are developing bioleaching alternatives for nickel laterites and sulphides.Copper continues to be dominated by the hydrometallurgical and pyrometallurgical debate; new hydrometallurgical developments are being tested at several sites whilst the pyrometallurgists continue to make competitive cost and environmental improvements.Gold processing developments are dominated by the use of improved gravity recovery equipment and by the development of thiosulphate as a more environmentally acceptable lixiviant.PGM processing trends are the use of fine grinding technologies, higher power input flotation cells, and new pyrometallurgical technologies. Hydrometallurgical options for some applications are being sought.OVERVIEW The metals industry has remained under price pressure for some time; low and decreasing real prices for most metals have become an expected scenario. Occasional price spikes give some relief but invariably bring expansions and new entrants into an already oversupplied commodity market, thus leading to the continued price pressure. Technical innovation, economies of scale, and improved work systems are continually sought, so as to improve the competitive position of each individual company in such a climate; however, these developments add to the downward price pressure. In such a situation the application of scarce funds to research and development is a difficult task. Excess funding is not available in tight economic times and yet the main route to higher profits is clearly the application of technical developments to lower the cost of producing a metal commodity. Many technical centers have closed as a cost saving exercise and some have coalesced to obtain economies of scale. The Australian based AMIRA research organisation has grown to serve the R&D part of the market well in Australia and in South Africa by acting as the catalyst to form research partnerships between a number of industry players and as an administrator to direct the funding of research projects towards the various applicable research institutions. AMIRA has developed closer ties to Camiro (Canadian Mining Research Organisation) through the appointment of Camiro.s metallurgical processing research director as AMIRA.s North American based director. AMIRA is continuing discussions with MIRO (Minerals Industry Research Organisation) in regard to a merger, with a report outlining the merger proposal expected in March of 2003. Company focused research centers continue to be effective at Anglo American Research Labs, Teck-Cominco Research, Falconbridge Research center, Inco Research and some others."

Jan 1, 2003

By Dominic Howarth, Diana Drinkwater, Don McKee

"The pressures on mining and minerals education at the tertiary level are well known. Within Australia, for example, the number of undergraduate mining engineering courses with 30 or more students in each year has reduced to three (University of Queensland, University of New South Wales and Curtin University). Similar declines in both student numbers and participating institutions are evident in many other parts of the world, and notably in USA and most countries in Europe.An in depth study of the Australian sector was conducted in 1997/1998, resulting in the Back from the Brink report (Carter 1998). The Australian situation was summarised as follows.Australia’s minerals education system, in its current form, is fragile and is in no position to seize the opportunity (i.e. world leadership in minerals education) and is more likely to succumb to the threat.Current trends include:- an acute shortage of talented academic staff, as a result of University remuneration packages having become hopelessly uncompetitive with those in the minerals industry;- small student populations and high relative costs, making mineral specific courses vulnerable to closures, when Universities are under extreme cost pressures; this situation will be exacerbated if enrolments drop in response to, say, a cyclical down turn in the industry; and- under-resourcing of minerals departments because of their comparatively small size, making these departments incapable of delivering top class teaching in all aspects of their courses, despite being excellent in some areas.Most of the Australian issues identified above have direct parallels in other countries.The most common response of institutions to the threats is to seek strength, and in some cases survival, through various forms of linkages and networks. A number of these associations, which are frequently defensive in nature, are outlined in the paper."

Jan 1, 2003

By David Yang

Commercially available flotation technologies for recovery of mineral fines have remained essentially unchanged for several decades. Recent studies have focused simply on improving mechanical and open column cells. Such studies have explored different control strategies and have aimed to improve reagent selectivity, fine air bubble generation and particle-air contact. However, no study has questioned whether current techniques are the most efficient technology for recovering mineral fines. Given that both mechanical and open column cells have a widely accepted carrying capacity limitation, the lack of extensive research into an alternative technology is surprising. Most recently, open column flotation has become an entrenched technology, and it is undermining the efficient recovery of mineral fines worldwide. An alternative exists. Packed column flotation overcomes the above-stated problems as the technology surpasses the carrying capacity limitation of current means by several-fold and almost always achieves the best performance in many comparative pilot tests and full-scale plant operations. Filling a column with packing plates creates a network of sloped walls capable of supporting a froth bed many times deeper than conventional machines. Having froth up to 75 percent of the total column volume tolerates all feed changes encountered in the plant environment and permits maximum flexibility in concentrate quality control. Furthermore, its scale-up is straightforward by increasing column volume or the number of interconnected small cells. As the air breaks upon rising and is distributed horizontally through packing plates, the air spargers can be replaced with a simple blower, resulting in considerable savings in operation and maintenance costs. Packed flotation technology provides a break-through solution for the separation of fine and ultra-fine minerals. Its simplicity, superior performance, and low cost structure make it an appealing alternative to current technologies and allow greater flexibility in downstream processing. Future industrial applications include a wide variety of metallic and non-metallic ores. This paper focuses on some recent scale-up campaigns for nickel and copper sulphide flotation applications compared directly to conventional equipment.

Jan 1, 2014

By P. Matias

The study involved two projects that will produce copper concentrate and may have their operations integrated. Transport by trucks, conveyor belt, and the equipment called RopeCon were evaluated as options for the ore transport between the sites. A rainforest stretch, that Vale S.A. demands to preserve, is situated between the projects. It was suggested to further review RopeCon because it presents minimal interactions with the environment. To design the preliminary system layout, a research was done on the rainforest cover height data, but the information found was scarce and imprecise. For preserving the local forest, the use of this data would conduct to the oversizing of RopeCon towers and, consequently, overestimation of its costs. For the acquisition of reliable information, a method was developed using local data acquired through airborne laser survey. The volume between the digital surface and terrain models was calculated to generate a surface representing the forest cover height. It was revealed, by plotting the points obtained from this surface, that 85% of the vegetation is below 25 m. This height is suggested to review the preliminary project with a more accurate design of the equipment towers, thus reducing its costs estimates. The method permits the precise location of the large trees, making easier to find a pathway, for linear-shaped facilities, that would minimize the creation of vegetation-free zones as a measure to protect equipments against falling trees and forest fires. Keywords: forest cover, mining projects facilities, digital models, airborne laser survey

Sep 1, 2012

By R. T. Dec

Current industrial compacting and briquetting practices are largely based on trial-and-error techniques. This paper introduces a two-dimensional finite element model of briquetting process in the roller press. Compared with other modeling techniques used in the past, finite element method offers the most versatile approach because it incorporates adequate information about powder behavior, geometry and frictional conditions and offers predictions for the density distribution, the velocity field, the stress distribution, roll force and torque. More over, when the model includes elasticity, it offers predictions on the internal stress state in the briquette after its exit from the roll. This enables to perform realistic computer experiments which are helpful for establishing the forming cavity geometry and process conditions necessary to produce briquettes with the desired properties. Three forming cavity profiles are analyzed. Results from model are verified on experimental roller press and best cavity profile is recommended for briquetting of sub bituminous coal fines.

Jan 1, 2014

By Takashi Furuyama, Sukeyuki Mori, Takafumi Okuma, Norio Hashiguchi

The Tower mill KD-3 is an improved version of the laboratory mills VD-1, KD-1 and KD-2 in which the classifying column has been modified to ensure a quick discharge of products from the comminution section and, on the other hand, a better separation of coarse and fine particles; the latter being collected in a cyclone with a central spiral ribbon. To level the circling airflow through the classifying column and have a strict control over the maximum size of collected particles, a series of experiments was carried out, modifying the internal structure of the column: insertion of a vertical plate, a cone, or a horizontal net. The relationship established between the maximum size of products collected in the cyclone and the duct airflow rate indicates that, independently of the latter, the insertion of a cone in the classifying column could stabilize the maximum size of products collected in the cyclone around 15.1 - 17.5µm. With a horizontal net, the maximal size could be reduced to 8.4 - 11.3µm. This occurrence might result from the collision of coarse particles blown from the comminution zone with the base of the inserted materials and their settling down the bottom of the classifying column.

Jan 1, 2003

By S. K. Dutta

Enormous amount of iron ore fines is generated, due to partly soft and friable nature, during mining. Coal fines are also produced during their processing. These fines cannot be used directly in ironmaking reactors. Utilization of these fines for extracting metal is of vital concern for resource conservation and pollution control, and therefore, a novel concept of agglomeration by cold-bonding is developed. Composite briquettes/pellets of iron ore fines with coal fines were prepared in the laboratory by cold-bonding technique. Various binders such as lime, Ca(OH)2, slaked lime, dextrin, molasses, fly ash etc were employed either alone or in combination in different proportions for making composite briquettes/pellets. It was possible to obtain dry strength of composite briquettes more than 300 N/briquette in some cases and more than 200 N/briquette in many trials. The combination of fly ash with slaked lime and molasses produced the highest strength, more than 400 N/briquette. Drop strength and shatter index values of composite briquettes/pellets were also measured. In briquettes, best compressive strength (978 N/briquette) is observed by using polyvinyl alcohol (PVA) binder. In pellet, best compressive strength (362 N/pellet) is achieved by PVA; shatter index (0.1%) and dry drop strength (158 numbers) are also good. Compressive strength above 200 N/pellet is obtained by fly ash, slaked lime and molasses combination.

Sep 1, 2012

By C. Kleine

Coal sorting with an x-ray-transmission (XRT) sensor has experienced a lot of development since first described by Jekinson et.al. in 1974. Powerful computers and increasingly sensitive X-ray scintillation counters enabled the development of high-performance sensor-based sorting machines. The first industrial installation of a belt-type XRT-sorting for coal is in operation since 2004. It is upgrading high quality coal from 1% ash to 0.7% ash for cathode production. In comparison to the high quality coal which is treated with a belt-type sorter, the chute type sorter has been successfully optimized for high volume coal treatment of lower quality coals. This project was funded by the German Environmental Fund (Project Nr.244444). In cooperation with the RWTH Aachen University and Isambane Processing, CommodasUltrasort(now Tomra Sorting Solutions) conducted extensive pilot test work under production conditions in 2010 for the destoning of power station coal at Arnot Power Station in South Africa. The experience gained during this pilot test phase led to an optimized, redesigned PRO Secondary XRT Chute sorter which is now in operation at a South African coal mine. This flexible semi-mobile modular destoning plant is treating a size range of -120 mm +30 mm at a throughput of 150 tph. The implementation of this plant not only reduces the ash content, abrasiveness index and sulfur content significantly, but also reduces royalties, water treatment and transport costs.

Sep 1, 2012

By Mary Stewart, Jim G. Petrie, Geoff Brent

"Life Cycle Assessment (LCA) is gaining increasing acceptance as a decision-support tool by which to evaluate the environmental performance of a product, process or service. This is evidenced by its inclusion in international policy documents (for example in the European Union’s Integrated Product Policy) and in environmental management standards (the ISO 14 040 series of environmental management codes relate to LCA). In response to this, the minerals industry has conducted a number of commodity-specific LCAs. These include studies for global production of a number of commodities including copper, nickel, aluminium and steel. In addition, a number of minerals companies profess to use LCA as part of their suite of project and technology assessment tools. Often, this collected use represents more a situation of “we do this because we’re told it’s good for business” rather than from any demonstrable evidence of this fact. This has led to a situation of much confusion and disillusionment within the industry, exacerbated by the obvious current limitations of LCA to accurately reflect the environmental performance of minerals and metals.Our point of departure here is that LCA, conforming as it does to the tenets of environmental systems analysis, is a valuable starting point, and that there is merit in exploring to what extent the methodology can be enhanced to better reflect the environmental performance of minerals and metals. Specifically, we explore here the further development of LCA to address the following:• Land Use issues• Consumption of Abiotic Resources including metallic and non-metallic minerals, water and soil)• Human and Eco-toxicity issues relating to mobility and bio-availability of metals• Salinityand address these through selected experimental and simulation case studies relating to energy- and base minerals production. Advances resulting from the United Nations Environment Programme/Society for Environmental Toxicology and Chemistry Life Cycle Initiative are presented in that they directly affect the application of LCA to mining, minerals and metals. Comments are offered on how best the mining and minerals industry might interface with future developments resulting from this Initiative in order that the Initiative can deliver outcomes which render LCA a useful tool for decision making in mining and minerals processing."

Jan 1, 2003

By A. Demirag, F. Burat

"The most important metals in the jewelry sector are undoubtedly gold and silver. As a result of workmanship work done in the jewelry industry, the tiny metal and jewel fragments and metallic powders are scattered. Given the prices of gold and silver on the market, the dust that emanates from these workshops is of great importance. Gold recycling has become as important as raw material production within the mass market and gold production industry. In 2016, 29% of the world gold supply has been obtained through recycled gold production. Waste derived from jewelry activity is included in this category, and represents an essential component of this percentage. In the scope of this study, the recovery possibilities of Au and Ag from jewelry sweeps floor sample was investigated using flotation method. In the experiments, optimum pH value, particle size, the effect of dispersant, type and amount of reagent were investigated. As a result of these studies, it was determined that the optimum pH value was 6.5 and the particle size was -212 microns. It was observed that the most suitable reactive combination was Aero 242 and Aerophine 3418A and Na2SiO3 has no positive effect on recovery of Au and Ag as a dispersant agent. As a result of tests, a final concentrate containing 268 ppm Au and 2122 ppm Ag was obtained with 81.4% and 74.5% recovery respectively. INTRODUCTION Because of the softness of pure gold, it is usually alloyed with base metals for use in jewelry, altering its hardness and ductility, melting point, color and other properties. On the other hand, gold has some special chemical properties which in normal conditions, don’t react with water, dry or humid air, oxygen, ozone, nitrogen, hydrogen, fluorine, iodine, sulfur and hydrogen. In these days, gold is used in different sectors like jewelry, electronics, finances and investing, dentistry, medicine, aerospace, awards & status symbols. According to Deutsche Bank Research, the primary usage of gold is jewelry. It has been used to make ornament and jewelry for thousands of years. In this sector craftsmen learned that alloying gold with other metals like copper, platinum and silver to increase gold’s durability. Alloying gold with other metals changes the color of the products. Another significant sector of gold is electronics. Modern electronics want the use of noble metals, like gold, especially in the areas of information processing, telecommunications, and military and space electronics (Habashi, 1997). Electronic devices use very low voltages and currents which are easily interrupted by corrosion or tarnish at the contact points. Gold is the highly efficient conductor that can carry these tiny currents and remain free of corrosion. Electronic components made with gold are highly reliable. Gold is used in connectors, switch and relay contacts, soldered joints and connecting wires. Every sophisticated electronic device have a considerable amount of gold. This includes cell phones, calculators, personal digital assistants, GPS units, and other small electronic devices. Most large electronic appliances such as television sets also contain gold. Humankind has known silver since prehistoric times like gold because silver occurs in native form. The metal is found in the Earth's crust in the pure, free elemental form native, as an alloy with gold and other metals, and in mineral such as argentite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining. Silver is very soft metal like gold also, it is the highest electrical conductivity, thermal conductivity, and the lowest electrical contact resistance of all metals (Habashi, 1997). Silver is used in different sectors like industry, jewelry, electronics, photography silver good, and coins. The main usage of silver is supplied by electronics. Silver's unsurpassed thermal and electrical conductivity among metals means it cannot easily be replaced by cheaper materials. In addition to silver is using in ener"

Jan 1, 2018

Optimising flotation designs and innovations is a complex process involving many parameters, one of which is ensuring sufficient testwork is carried out at plant level before these innovations are launched in the marketplace. This paper will describe how modern design tools are utilized, what are testwork phases at various plants and how results and observations have helped to validate and optimise flotation design innovations. Scale-up of equipment has long been the prevalent trend, but how long can it continue? Are there other means for pushing the boundaries of present technology? Some present challenges and future directions are given in the light of theoretical criteria for scale-up and how it has been applied in practice. Very large flotation cells of 300 m3 size have been installed in New Zealand, and relevant results from the metallurgical and mechanical aspects are presented and discussed. Utilization of the cell volume is also important. New innovations in the hydrodynamic domain are presented and discussed. Means to enhance flotation of coarse and fine particles are shown with results from plant testwork. Accurate control of large flotation cells is vital to optimize yields and grades. Froth image analysis and intelligent level control are presented ? again - with relevant plant results.

Jan 1, 2014

By Paulo Braga, Carlos Junior, Silvia França

"Lithium is the lightest of the metals, with high reactivity and great electrochemical potential. It has a low thermal expansion coefficient and high caloric value, and it forms very light and resistant aluminium alloys. These properties make lithium an attractive element for use in battery manufacture and glass and ceramics production, in addition to its applications in the aeronautic industry. Today, two sources of raw material are economically viable for lithium production: pegmatite rocks and brine. The world production, in 2012, was approximately 150,000 tons of LCE (lithium carbonate equivalent), almost triple the production in 2000. The forecasted consumption for the current year, 2013, was approximately 162,000 tons of LCE, and for 2020, it could be as much as 280,000 tons of LCE, stimulated essentially by the growth of world production of electric (EV), hybrid (HEV) and hybrid plug-in vehicles (PHEV), the batteries of which are based on Li-ions. With the growth of world demand and increasing prices, lithium minerals such as spodumene, petalite and amblygonite, once considered uneconomical for the production of lithium carbonate, are regaining their economic value. New projects to produce lithium compounds based on mineral sources are being developed in many countries, aiming to produce battery-grade lithium carbonate (99.95% Li2CO3). Although Brazil has large lithium pegmatite reserves, the domestic production of lithium carbonate and hydroxide is very low, at approximately 600 tons of LCE, which represents 0.4% of the world production. The application of these products is mostly in the grease and ceramic industries. The national lithium market is under government protection due to its potential use for nuclear purposes. Thus, the industrialization activities and import and export of ores and lithium minerals, as well as organic and inorganic products, such as metallic lithium and lithium alloys, are controlled by the National Commission for Nuclear Energy (Comissão Nacional de Energia Nuclear - CNEN). The objectives of this work to quantify the real lithium demand in the Brazilian market, considering that a large amount of lithium is indirectly imported in the form of the Li-ion batteries used in equipment such as mobile phones, cameras, tablets, notebooks and e-bikes, and to compare this demand with the current national production of LCE. Finally, some technological alternatives will be discussed, with the aim of increasing the competitiveness of the lithium industry in Brazil."

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 J. Y. Liu

The comminution in a high-pressure roller mill is modeled by an energy-based population balance approach considering three aspects of breakage taking place in the active zones of the mill: the interparticle breakage in the high-compression zone, the breakage at the edges of the rolls, and the pre-breakage in the acceleration zone. Together with an appropriate model of classification, this model can be used to simulate steady-state performance of closed-circuit grindings with high-pressure roller mill. After a brief description of the basic modeling approach, the algorithm of the steady-state calculation for a generalized grinding-classification circuit is presented, from which the circuit configurations commonly met in industrial practice can be derived. With an iron ore as feed material for example, simulation results are shown and discussed in respect of circulating load, specific energy consumption and product fineness for closed-circuit grindings under various operating conditions. The effects of stressing intensity, working gap, classifier parameters as well as circuit configuration on the overall circuit performance are investigated systematically by means of computer simulation.

Jan 1, 2014

By Markus A. Reuter, Bernardete Castro, Antoinette van Schaik, Han Remmerswaal

This paper describes the inseparable relation between product design, liberation, and metallurgical recovery in the optimisation of the recycling of passenger vehicles. This is illustrated by the use of an optimisation model that uses among others a material combination matrix based on metallurgical process data, which depicts the consequences of the quality of intermediate recycling products on the metallurgical material recovery and final alloy metal quality. Various simulations will illustrate the effect of changes in product design and hence liberation on the recycling of end-of-life vehicles. Although this paper focuses on cars, the discussion is equally valid for any end-of-life product. Calibration of the model will be discussed with reference to experiments carried out in order to study the optimal recovery of aluminium applications used in passenger vehicles.

Jan 1, 2003

By Ralph J. Holmes, Victor Sharp, Steven J. Spencer, Kevin J. Davey, Jonathan J. Campbell, Peter L. Phillips, David G. Barker

"Improved measurement tools for monitoring and control of AG/SAG mill performance have a high level of interest in industry. Historically, acoustic emission monitoring has been widely used on SAG/AG/ball mills and hydrocyclones to provide new information on the conditions inside these devices affecting their performance. The current work was focused on a new technique using surface vibration monitoring of a number of pilot-scale and production-scale AG/SAG mills to yield insights into the events occurring in the mills. The development of relationships between signal analysis outputs and mill operating conditions can be used for soft-sensor measurement of mill process variables. The technique used an array of accelerometers mounted on the mill lifter bolts linked to a fast data acquisition system which monitored the surface waves generated during operation. Details of the system are presented. Mill operating variables were adjusted systematically to provide a wide range of operating conditions for surface vibration signal collection. The experimental approach is discussed.The signals acquired during the experiments were analysed using a range of techniques. The results show that strong relationships exist between measured vibration power (both total power and within certain frequency bands) and mill load level/power and mill speed. A new method for extraction of power spectral density and band power information on features of interest in a mill rotation cycle is also presented.These results show that single sensor analysis information from the surface vibration system can be used as soft sensor inputs for monitoring process variables such as mill load that until now, have not been reliably measured. System outputs also show considerable promise in the area of condition monitoring. An example of the signal analysis output is presented showing elevated vibration levels in an area with higher resultant wear. Eventually, it is considered that outputs from this system for process variable and wear condition monitoring will be key new inputs to an online AG/SAG mill monitoring and control system."

Jan 1, 2003