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By F. Samimi Namin

During the process of developing surface or underground mines, some sites are considered for dumping of surface soils, while others are applied to reclaiming surface and waste disposal. For each kind of overburden, whether it be waste rock, low-grade material, or process tails, a separate storage site is considered so that it becomes possible to transport or recover the overburden separately. Decision-making must be completed by means of a selection process which takes into account the best methods of alternative sets in order to achieve these goals. This decision- making involves many parameters that are inter-related in that changes in some parameters affect the others. There are many methods of decision-making, however, Fuzzy Multi-attribute Decision-making (FMADM) and its functions are studied in this paper. The advantages of this method lies in its theoretical background, formulation, revising capability, unlimited alternatives, and consideration of the counteraction of the different parameters upon one another.

Jan 1, 2007

By C. Bazin, D. Hodouin

"A flexible model involving perfect mixers, stagnant zones, plug flow, material bypassing and recycling zones has been developed for interpreting mixing phenomena in mineral processes. The mixing properties are described by the residence time distributions which can be subsequently interpreted by the flexible model. User-friendly computer programs (for 1MB-PC or compatible) have been developed for simulation and modelling of RTDs using the proposed model. Seven mineral processing case studies are discussed in terms of experimental procedure, model calibration results and application of the estimated mixing model to process modelling, diagnosis, and performance evaluation. IntroductionIn any mineral processing plant there are continuous-flow machines that transform or separate the ore components. Grinding mills, flotation cells, conditioning and leaching tanks are examples of such machines. The performances of these vessels or reactors are controlled by the rate at which the reaction proceeds and the time spent in the environment where the reaction occurs. This paper deals with the latter aspect of mineral processes operation.Since most of the reactions occurring in mineral processing units are time dependent, knowledge of the residence time of the material in process vessels is important for modelling and diagnosis purposes. Due to the random mixing phenomena involved in the process equipment, there is a distribution of the residence time of the ore particles and the fluid in the vessel. The probability density function E(t) that a micro-element of the material flowing through a processing unit stays a time t in the vessel, is the residence time distribution (RTD) of the corresponding component."

Jan 1, 1988

By Alain Bouchard, Germain Labonté, Jim Barrett

"Mill feed materials that are not run-of-mine ore are often a challenge for mineral processors and tend to accumulate in stockpiles, where they remain unprocessed for many years and become “slow moving inventories”. During a complete re-evaluation of the Clarabelle Mill operation (38,000 ton/day capacity) in 2000, it was concluded that there was an opportunity to assemble a 5,000 ton/day custom circuit to treat such stockpiles in the equipment that remained available during regularly scheduled maintenance shut-downs.This project was part of the larger Mill Redesign Project and involved testing the intended flowsheet under a number of operating scenarios for the first material to be treated: spent refractory bricks. The laboratory focus was on how to maximize returns using the available equipment and reagents.The circuit was successfully commissioned in the fall of 2000. As the brick stockpile was depleted, other potential feeds were evaluated at the laboratory, as well as in the new custom circuit itself. Processing of the spent refractory brick has yielded a significant contribution to the profitability of INCO. Significant opportunities lie ahead for generating more value from other slow moving inventories.INTRODUCTIONIntegrated mining operations tend to have slow moving inventories along the path from the mines to the finished products. Spent refractory bricks from furnaces and converters and furnace bottoms are materials that often end up in long-tern stockpiles. Such stockpiles are a challenge, although they represent small tonnages on an annual basis, because they are unique materials, which cannot be readily brought into the process at a rate anywhere near that at which they are produced, due to the high contents of deleterious components such as chromite or magnesia. Accumulation over years will eventually yield a metal inventory worthy of consideration given the right opportunity, such as availability of spare equipment or peak metal prices."

Jan 1, 2002

By Moe Momayez

Shotcrete is a practical and economical support system in many Canadian underground mines. Although shotcrete technology has gained acceptance in the mining industry, there are some problems that have emerged with respect to quality assessment and thickness measurement of the liner. This paper presents recent tests performed with a miniature seismic reflection device developed primarily for thickness measurement of this heterogeneous liner. Work was performed on site in an underground mine in Ontario, Canada. This paper also presents the results from laboratory tests performed on fibre reinforced and non-reinforced shotcrete panels that were used to assess the P-wave velocity in both materials. The results of these tests were used in a second on site investigation. The NDT thickness measurements showed good agreement with direct thickness measurement such as coring.

May 1, 2001

By J. Hu, F. Lin, R. Chen, F Peng, S. Yang, W. Yu

"Microseismic monitoring technology has become one of the most effective method of mine ground pressure monitoring after decades of development. But safety assessment of mine ground pressure by using microseismic monitoring is still in the development stage, it needs to be perfected continuously in practice, and choose the optimal assessment indexes and methods. The definitions and physical meanings of wave velocity, b value, and EI-VA value are introduced in this paper. Statistical calculation of the microseismic events in Luomu Mine is finished by using these indexes, then the functions and calculation results of V, b value, and EI-VA value with the variable of time are also given in the paper. The preliminary safety assessment method is established in Luomu Mine, and it has achieved good results in practical application.1.1 Engineering background The Luomu Mine is a super large molybdenum and tungsten production base in China, ore reserves is up to 2 billion tons, first in Asia and third in the world. It begins mining since the 1960. and bases on underground mining until 2002. In order to recover resources more effectively, it began to use opencast mining method and formed a production of 30000t/d in the early 1990. After about 30 years of underground mining, a large mined out spaces was formed under open pit mine, up to area of 1.2 million m2 and volume of 18 million m3, as shown in figure 1. The large number of mined out spaces seriously affects the normal production, mining and handling of mined out spaces are in the high risk. In the past years, several rock mass collapsions happened, and it caused a serious security threat to persons and equipments. According to the distribution characteristics of mined out spaces, Luomu Mine is divided into A, B, C, D and E mining area. The stability of D mining area is studied in this article. D mining area mainly includes 1376,1350,1340,1317 mined out spaces and 1280 deep large mined out area, as shown in figure 2. The mined out spaces of D mining area is extremely complex and high-risk. Therefore, a microseismic monitoring system was built to monitor the stability of D mining area, a large number of valuable datum has been obtained, and it has a striking effect (Cheng & Peng, 2013; Peng et al., 2013)."

Jan 1, 2015

By Peter L. Sheehan, David A. Fawcett, Dennis C. Martin

"Smoky River Coal Limited has successfully completed a major program involving the pattern rock anchoring of a high, steeply dipping footwall slope. The slope dips at approximately 65 to 70 degrees to the north, is benched for the upper 200 feet, is supported with rock anchors for another 240feet, and is unsupported at the pit bottom. In addition to the height and steepness, several structural features including shears, rolls and stratigraphic pinch- outs complicate footwall stability.This paper presents an overview of the project with descriptions of the engineering geology and footwall design, anchor installation, instrumentation and monitoring and a cost summary.IntroductionSmoky River Coal's mines are located in the foothills of the Rocky Mountains near Grande Cache, Alberta, approximately 200 miles west of Edmonton. The Smoky River coal leases were initially developed in the late 1960s and, except for minor shutdowns, have been in continuous operation since 1969 producing a low volatile metallurgical coal, mainly for the export market. Initial coal production was from underground mines; sur face mining started in 1971, and a large surface mine, No.9 Mine, was opened in 1974. Since that time, a number of open pits have been mined within the No.9 Mine area. Surface mining is by conventional shovel-truck method s with the use of a backhoe for mining the narrow pit bottoms.Coal recovery is mainly from the No.4 seam, which has a typical unstructured thickness of 20 feet. The most attractive opportunities for open-pit mining exist in areas of over thickening of the coal seam in the hinge zones of synclines and anticlines and in dip-slope situations. The mining of the more structurally complex pits and steeply-dipping footwall slopes requires that consideration be given to footwall stability."

Jan 1, 1988

Improved Process & Practices Result In: ? Reduction of undesirable downtime, & expensive secondary damage ? Improved equipment performance & health ? Extension of equipment life, & reduction of operating costs ? Safety and environmental performance improvement Equipment knowledge capture and consistently applied

May 1, 2010

By Paolo Toscano, Dave Hall

"This paper discusses the project history, process design and layout of the Rainy River Gold Project mill. The circuit consists of a 55 x 83 primary crusher, 15 MW SAG mill and 15 MW ball mill. Both mills are twin pinion with LSS and VFD drives. A pebble crusher is located in the process plant with bypass and stockpile options. Gravity concentration followed by 30 hours of leach residence, carousel CIP, carbon recovery, cyanide destruction and tails disposal in a 1,428 hectare tailings management area (TMA).The Rainy River Gold Project is located approximately 65 km northwest of Fort Frances in north western Ontario. The project is scheduled to be commissioned and reach commercial production in mid-2017. Expected cost is $US877M and is comprised of an open pit mine, process plant, tailings management area and supporting infrastructure. The process plant is designed to produce gold/silver Dore’ bars.The project has been developed on the following timeline:• 1967 – First exploration• 1994 – 17 zone discovered• 2004 – 433 Zone discovered• 2005 – Rainy River Resources Ltd. purchases property • 2006 - ODM zone discovered• 2007 - Cap Zone discovered• 2008 - First NI-43-101 Resource completed• 2012 - PEA completed & Intrepid Zone discovered• 2013 - New Gold acquires Rainy River Resources• 2014 - Updated feasibility study completed & Environmental Assessment report submitted• 2015 - Detailed Engineering >95% complete, EA approved and construction commencesThe property is accessed by provincial highway 600 and is within 17 km of 230 kV power line and railway sidings. Key project criteria are summarized as follows:"

Jan 1, 2016

By Walter S. Bergholz, Michael L. Schreder

"Since Escondida began operations in fiscal 1991, a series of aggressive expansion projects have enabled market share to be increased and ever larger profits to be realized. This was possible due to the very large size of the ore body and its high grade - averaging 2.7% copper from startup through fiscal 1997. The situation has now changed: ore grade is falling rapidly and is projected to be only 1.55% by 2003. Since revenue is directly proportional to ore grade, while costs are proportional to quantity of ore processed, profits will begin to fall dramatically. The Phase IV Expansion Project is intended to forestall this drop in profits by increasing ore processing capacity by over 85%.The Phase IV concentrator is designed for a nominal capacity of 110,000 MTPD and the key to achieving this value is through the proper design of the grinding circuit. This paper presents the general design criteria for the grinding circuit, as well as a description of the facility.INTRODUCTIONThe Phase IV Expansion Project consists of a new copper concentrator located 8.5 km south of the existing operations, a new tailings disposal and water reclaim system, a new concentrate slurry pipeline to the coast, and added concentrate handling capacity at the port of Coloso. The new concentrator has a nominal capacity of 110,000 tonnes per day (MTPD), compared to the existing concentrator’s capacity of 127,500 MTPD. The Laguna Seca concentrator is based on using the largest and most efficient ore grinding mills now available.The concentrator has been designed for a 110,000 MTPD nominal capacity. The process design criteria for the Phase IV project were established from in-house operating information and from test work. Unlike a green field project, Escondida already had an operating plant and it processes ore from the same pit that feeds the Phase IV plant. It is expected that the current mineralization will be similar for the first 6 years of operation of the new project. Therefore, some of the current plant operating conditions were incorporated directly into the design criteria."

Jan 1, 2004

By Roussos Dimitrakopoulos

Conventional approaches to estimating reserves and optimizing mine planning and production forecasting result in single, often biased forecasts. This is largely due to the non-linear propagation of errors in understanding orebody attributes from a limited finite number of drilling data, throughout the chain of mine planning and mining. A new mine planning paradign is considered herein to include two interacting and potentially fusing elements: stochastic simulation and stochastic optimization. These two elements provide an expanded mathematical framework that allows the modelling of orebody uncertainty and its direct integration to mine design, production planning and valuation of mining projects and operations. This stochastic framework has shown to increase the value of production schedules in the order of 25%. In addition, case studies show that stochastic optimal pit limits are about 15% larger in terms of total tonnage, compared to the conventional (deterministic) optimal pit limits. This difference extends life of mine and adds approximately 10% of net present value (NPV) to the NPV reported above from stochastic production scheduling within the conventionally optimal pit limits. Furthermore, results suggest a potential new contribution to the sustainable utilization of natural resources.

Oct 1, 2009

"The success or failure of coal mining operations in Western Canada may hinge on the ability to extract thick coal under a variety of geological and mining circumstances and conditions. The paper presents, in who-where, what- how pattern, the current status of undergrounud mining of thick coal seams based on a review of foreign technical literature. The underground production of coal from what are considered to be thick seams is over 300 million tons per year. Methods of mining have evolved, through years of trials and tribulations, capable of meeting the requirements of a modern mine: high bulk outputs from a limited number of mining faces by concentrating in the horizontal (mechanization) and in the vertical (increased working lift)."

Jan 1, 1972

By V. K. Alves, P. Lacoste-Bouchet

"In order to improve ball milling efficiency in pellet plants, Companhia Vale de Rio Doce (CVRD), experiments new technologies in Santa Luzia (M.G. – Brazil) research center facility. Pilot grinding tests have been conducted with small grinding media, size distributed from 5 to 12 mm (millpebs). Tests have been conducted on an ore from CVRD’s Usina 5 Nibrasco, in Vitória, Brazil. A sample of the regrind circuit feed was obtained and used in comparative grinding tests with two types of grinding charges: 100% balls and a blend of 70% balls and 30% millpebs by weight. According to the balls charge, the grinding media mixture has showed the following benefits: reduction of the power draw, increase of the mill capacity, reduction of the circulating load and a slight increase of the ore blaine. Following the results obtained, CVRD is going to further explore the regrinding potential of millpebs.INTRODUCTIONCompanhnia Vale de Rio Doce (CVRD) is the largest mining company in Brazil. CVRD is involved in iron, base metals, gold and bauxite industries. Moreover, CVRD operates several pelletizing plants in Brazil and in other countries.CVRD’s Center for Mineral Development (CDM) is equipped with a comminution laboratory where studies are carried out that are aimed at the optimization of existing plants at several mining sites as well as the technical and economical feasibility of new projects. The laboratory is equipped with a complete pilot plant with several mills and classifiers, enabling continuous grinding tests in grinding circuits of almost any capacity and characteristics.In January 2004, CVRD undertook to conduct pilot tests at CDM for evaluating the effect of small grinding media on ball milling efficiency. Generally speaking, it is not unusual for operators to add oversize grinding media in a conventional regrind mill. This fact originates mainly from prohibitive prices of grinding media below 25 mm due to a production capacity decrease of grinding media producers. The size of the grinding media is an important variable affecting ball milling efficiency. Use of oversize balls decreases the number of contact surface between which particles can be caught and broken."

Jan 1, 2005

By D. W. McDonald, L. M. Heaman, R. A. Creaser, T. Davies, T. Chacko, A. Simonetti

"The Three Bluffs gold deposit is located in the Committee Bay greenstone belt, which forms part of the Rae domain of the western Churchill province, Nunavut, Canada. Gold mineralization is hosted by iron formation of the Neoarchean volcanosedimentary Prince Albert Group, and is associated with silicification (quartz veining) and sulfidation of magnetite and other Fe-rich minerals. Conventional U-Pb zircon dating of a conformable dacite unit within the volcanosedimentary host-rock sequence and a crosscutting diorite intrusion confirm a ~2.7 Ga age for deposition of the supracrustal package. U-Pb monazite dates and Pb isotopic analyses of sulfides were obtained by laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS). A subset of U-Pb monazite (1813.8 ± 8.7 Ma) and Re-Os arsenopyrite (1822 ± 21 Ma) dates, combined with a Pb-Pb secondary errorchron age for pyrite and arsenopyrite (1829 ± 77 Ma), suggest that gold mineralization associated with sulfidation of the iron formation occurred at ~1815 Ma, prior to high-grade (upper amphibolite facies) tectonometamorphism in the Three Bluffs area (D2TB/(M2TB). An ~1815 Ma age for deposit formation is broadly consistent with evidence from elsewhere in the western Churchill province and to the southwest in Manitoba and Saskatchewan for a late Trans-Hudson (1.9-1.8 Ga) gold mineralizing event. The majority of U-Pb monazite ages form a second population at 1780.6 ± 4.2 Ma, similar to the age of the majority of Re-Os arsenopyrite analyses (1763 ± 11 Ma). These dates are thought to reflect the timing of peak M2TB metamorphism. 40Ar/39Ar dating of amphibole, biotite, and muscovite yielded plateau ages ranging from 1723.8 ± 9.0 Ma to 1710 ± 17 Ma, which are interpreted to record the timing of postpeak metamorphic cooling to below the respective closure temperatures for Ar diffusion in these minerals. Le gîte aurifère de Three Bluffs est situé dans la ceinture de roches vertes de Committee Bay, laquelle appartient au domaine de Rae dans l’ouest de la province de Churchill, au Nunavut, Canada. La minéralisation aurifère est encaissée par des formations de fer d’âge Néoarchéen appartenant aux roches volcanosédimentaire du Groupe de Prince Albert; la minéralisation est associée à de la silicification (veines de quartz) ainsi qu’à la sulfidation de la magnétite et d’autre minéraux riches en Fe.Les résultats de la géochronologie U-Pb conventionnelle sur une unité de dacite concordante au sein de la séquence volcanosédimentaire ainsi que d’une intrusion de diorite qui les recoupe indiquent que ces roches supracrustales ont un âge de ~2.7 Ga. Les âges U-Pb de la monazite ainsi que les analyses des isotopes du plomb des sulfures ont été obtenus par ablation laser (LA-MC-ICP-MS). Certains des âges U-Pb obtenus à partir de la monazite (1813.8 ± 8.7 Ma) et des âges Re-Os retournés par l’arsénopyrite (1822 ± 21 Ma), en association avec l’âge indiqué par une isochrone à données dispersées « errochron » secondaire Pb-Pb pour la pyrite et l’arsénopyrite (1829 ± 77 Ma), suggèrent que la minéralisation aurifère associée à la sulfidation de la formation de fer s’est formée vers ~1815 Ma, avant que l’événement tectonométamorphique (D2TB/(M2TB) de niveau élevé (faciès des amphibolites supérieures) affecte le secteur de Three Bluffs. Un âge de mise en place de ~1815 Ma pour ce gîte est compatible avec les données en provenance de l’ouest de la province de Churchill ainsi que plus au sud-ouest au Manitoba et en Saskatchewan qui indiquent la mise en place de minéralisations aurifères à la fin de l’orogénèse Trans-Hudsonienne (1.9-1.8 Ga).La majorité des âges U-Pb de la monazite constituent une seconde population formée à 1780.6 ± 4.2 Ma, ce qui est similaireLà l’âge obtenu pour la plupart des analyses Re-Os sur l’arsénopyrite (1763 ± 11 Ma). Ces âges reflètent probablement l’atteinte du pic métamorphique M2TB.La géochronologie 40Ar/39Ar de l’amphibole, de la bio"

Jan 1, 2009

By J. G. Henning

Following completion of planned mining operations at the Goldcorp Dome Open Pit Mine, a high-grade Shaft Pillar located in the pit highwall was recovered. Mining of this Shaft pillar faced numerous rock engineering design and implementation challenges due to its remote position on the highwall and the presence of mine workings within the wall. The case example presented in this paper discusses the geotechnical investigation performed at the site, novel measures undertaken for installation of ground support required for rockmass reinforcement and for worker protection, as well as operational challenges to successful mining of the Shaft Pillar.

May 1, 2009

By G. I. Mathieu, R. W. Bruce

Flotation schemes for the separation of molybdenite from other minerals are based on utilizing the Inherent hydrophobicity of molygdenite (Fuerstenau1). This natural floatability was attributed to the crystalline structure of molybdenite by Gaudin et al.2 who suggested that any surface formed by the rupture of van der Wall's bonds should be hydrophobic and, therefore, naturally floatable. Other authors argued that "natural floatability" is dependent of adsorption of hydrocarbon ions and/or molecu1es on the surface of the minerals. This theory, albeit-c questioned 1,2 has long been recognized in actual practice of molybdenite flotation as the latter in carried out with hydrocarbons, such as fuel oil, kerosene and stove oil. Although conferring ready floatability to molybdenite, these presents generally have little effect on other sulphides and silicates. However, talc is a noteworthy exception because of its innate floatability4. Not withstanding the reason for this behavior which has also been attributed to crystal structure2 its end results as in the case of molybdenite is an immediate flotation response to frothing oils arid kerosene, as was observed by Baranovski5, Sutherland and Wark6.

Jan 1, 1974

By Philippe Angers

This article analyzes the social acceptability process of a mining project located in an existing city. It will explore how the principles of sustainable development have been integrated in the project of the Canadian Malartic open pit mine held by the Osisko Mining Corporation, and the corporate social responsibility (CSR) initiatives proposed to strengthen the social acceptability of the project. This mine is located on the ancient south quarter of Malartic and has required the displacement of hundred of houses and five institutions. The location and the inherent social impacts generated by the relocation of the citizens of the south quarter makes this case particularly interesting to understand social dynamics in an era of environmental consciousness. These major constraints of the mine generate high expectations within the urban population with regard to the social and economic benefits it will receive from the project. In a context where society demands higher CSR from the corporation, Osisko is closely followed regarding their actions toward the sustainable development principles to see if they respect the environment and the desires of the community. From the beginning, the company had to be a model of sustainable development in various aspects reflected by the manifold interest of the population. To understand the endeavor made by the company to fulfill the demand of CSR, we will analyze how the company understood sustainable development principles and what CSR initiatives Osisko company put forward. We will explore the involvement of the company in various social aspects like employment, employee satisfaction, and the level of commitment to non-discrimination policy in employment, notably with the native populations. We will also take a closer look at the relationship built by the company with the community and the level of commitment with the various stakeholders of the community. In this way, we will be able to seize the level of involvement of the company in the fulfillment of the principles of sustainable development toward a higher CSR, and to specify the trajectory adopted to build social acceptance.

Aug 1, 2013

By Dina M. Aloi

In today?s evolving and globalized world, mining companies are being pressured to move beyond compliance towards long-term sustainability and sustainable development. Companies are expected to ?engage? communities without a clear understanding of ?how? to do this or to what end. This move, away from compliance, develops more of a focus on ?Community? Social Responsibility and sustainability. This shift leads to the development of world-class projects that provide sustainable development for people, reduce the incidence of costly delays, and promote good global citizenship for companies. The process of ?engaging? communities in mining project design and development leads to a stronger license to operate, and a reduction in social and political risk. To create this mutually beneficial relationship between communities and companies, communities must be ?engaged? in the project development and risk assessment processes as early as possible, preferably during the exploration or the concept phases. How to create this ?engagement? and manage this risk will be discussed.

May 1, 2007

By J. Chlopas, D. J. Barratt, M. V. Sharp

"This paper describes the modifications made to the Fox Mine copper concentrate bin in order to obtain a continuous flow condition. The design of these modifications is based on test results obtained on Fox Mine concentrate using the flow factor testing machine in the research facilities of Cominco at Trail, B.C.The original design consisted of a cylindrical steel bin on a concrete slab with two slot-discharge openings. Based on predictions of the maximum mass flow hopper angle for conical and wedge shaped hoppers for the concentrate on various potential bin lining materials, Ultra-High Molecular Weight (UHMW) Polymer was selected as a liner.Using the recommended angles for conical and wedge shaped hoppers, the profile of the bin base was changed to suit the existing slot openings.The initial method of fastening the liner resulted in failure of the connections. Subsequent modification to the zinc concentrate bin fastener system proved satisfactory and it has now been in operation for over one year without any separation of the lining material.Utilization of flow testing procedures on concentrate samples has demonstrated that proper design of storage bins or hoppers to achieve continuous flow can be incorporated into the design of new plants."

Jan 1, 1978

By J. M. Gregg, C. J. Persellin, I. D. Somerville, E. A. Atekwana, K. L. Shelton

"Zn-Pb sulfide mineralization at Abbeytown mine and Twigspark quarry comprise the only known car¬bonate-hosted base metal sulfide deposits in the Sligo syncline, northwest Ireland. Limestone sedimentation occurred uniformly throughout the region during the Early Carboniferous (Mississippian) as observed by field relationships and lithofacies; however, petrographic and stable isotope evidence indicate that host-rock dolomitization occurred under different conditions at localities to the west and east of the Ox Mountains inlier, suggesting significant uplift and geologic isolation of these areas prior to dolomitization. Localized fluid flow systems are thought to be responsible for sulfide mineralization and associated epigenetic carbonate cements. West of the Ox Mountains inlier at Abbeytown, evidence of three geochemically distinct fluids are observed: (1) a lower-temperature, lower-salinity fluid (70°-130-°C, 4-9 wt.% equiv. NaCl); (2) a lower-temperature, higher-salinity fluid (70°-140°C, 15-24 wt.% equiv. NaCl); and (3) a higher-temperature, moderate-salinity fluid (165°-220°C, 8-14 wt.% equiv. NaCl). Similar fluid types were observed at the Twigspark deposit. The source of the higher-salinity fluid is likely seawater evaporated to near the point of halite precipitation. The higher-temperature fluid is thought to have been derived from deep circulation of basinal brines. It is speculated that mixing of the higher-salinity fluid with the high-temperature fluid was vital for ore formation at Abbeytown because fluid inclusions in sphalerite have homogenization temperatures and salinity values that fall along a mixing trajectory of these end member fluids. Also, areas where the high-salinity end member fluid is absent are barren of sulfides. Less complex fluid systems are indicated for sites east of the Ox Mountains inlier where no sulfide mineralization was observed. Data from base metal sulfide prospects in northwest Ireland indicate no connection with the regionally extensive flow system thought to be responsible for Zn-Pb deposits throughout the Irish Midlands.Les minéralisations en sulfures de Zn-Pb de la mine Abbeytown et de la carrière Twigspark sont les seules gîtes de métaux usuels à encaissant carbonaté connus dans le synclinal de Sligo, au nord-ouest de l’Irlande. Ces carbonates se sont déposés d’une manière uniforme dans la région au Carbonifère inférieur (Mississippien) tel que l’indiquent les relations de terrain et les lithofaçiès; les données pétrographiques et d’isotopes stables indiquent toutefois que la dolomitisation de l’encaissant s’est faite sous des conditions différentes aux localités situées à l’ouest ou à l’est de la boutonnière des Ox Mountains, ce qui suggère un soulèvement et une isolation géologique significative de ces secteurs avant la dolomitisation. L’action de systèmes de circulation locaux sont considérés être à l’origine de la minéralisation sulfurée et des ciments carbonatés épigénétiques qui leur sont associés. À Abbeytown, à l’ouest de la boutonnière des Ox Mountains, on note les effets de trois fluides géochimiquement distincts: (1) un fluide à basse température peu salin (70°-130°C, 4-9% poids équivalent NaCl); (2) un fluide à basse température fortement salin (70°-140°C, 15-24% poids équivalent NaCl); and (3) un fluide formé à plus haute température et salinité modérée (165°-220°C, 8-14% poids équivalent NaCl). Des fluides similaires ont été observés au gîte Twigspark. La source présumée du fluide le plus salin est de l’eau de mer amenée par évaporation près du point de précipitation de la halite. Le fluide à plus haute température est probablement dérivé de la circulation profonde de saumures dérivées d’un bas¬sin sédimentaire. Il est possible que le mélange du fluide à haute salinité avec celui à haute température ait joué un rôle central dans la genèse de la minéralisation d’Abbeytown parce que les températures d’homogénéisation et les valeurs de salinité des inclusions fluide"

Jan 1, 2009

By T. P. R. de Jong, H. Harbeck

"This contribution reports recent mineral sorting experience and lists the opportunities of the newest generation of automatic sorters with a special focus on electromagnetic detection and Xray transmission. With the available sensor resolutions and actuator systems that are available today sorting of minerals down to 2 mm size and up to 250 mm lump size is technically feasible. In industry, ore as well as coal is still hand-picked and current automation potential only utilised in a handful of specific applications. Recently a number of technological developments took place that may increase sorting potential, save mill costs and lead to lower overall tonnage costs.They are:??High speed and high resolution sorting systems based on X-ray transmission imaging??High speed on-line image processing and further development of advanced data processing??Modular multi-sensor automatic sorting units (using one or more sensors such as colour, electromagnetic and X-ray in a single device)??Sensitive electromagnetic sensors for sorting based on differences in magnetic susceptibility and electric conductivityThe above enables compact dry separation, insensitive for moisture fluctuations and at high separation sharpness, as well as “electronic” high gradient magnetic separation for larger particles. Besides conventional X-ray transmission (XRT), dual-energy XRT (DE-XRT) is now being redesigned to meet the requirements of the mining industry. The mentioned technologies provide automatic dry separation of minerals and rock as alternative for conventional processing."

Jan 1, 2005