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By Ning Yu

There are about 1.341 trillion tons (t) of proven coal reserves in China, of which 279.58 billion t are available for mine well construction basis. Thick coal seams are 44% of the reserves. The production of thick coal seams exploitation is over 45% of the total coal production. Full-seam mining and fully-mechanized mining for large mining height is the technology development direction of thick and extra thick seam mining. It is also the important way to achieve efficient and intensive mining with the characteristics of high production, high mechanization, high efficiency and low energy consumption, etc. Complete set of technology and equipment of fully-mechanized top caving for large mining height of full-seam (7m) mining and extra thick seam ( 14-20m) has been gradually mature and for demonstration application by the joint research of government, enterprises, universities, scientific research organizations and users. It has solved some technical problems of coal face for large mining height (over 7m) such as the coal wall spalling control, stability of support, wall rock coupling, cooperation work of mining and caving, full roadway support for super large section, end support, equipment matching of coal shearers, hydraulic support and scraper conveyor. It has developed key equipments including powerful hydraulic support of fully-mechanized mining and fully-mechanized top caving for large mining height, electrically-driven coal shearer with high speed and reliability, scraper and belt conveyer with big capacity, soft-start and high reliability, automatic control system of coal face with the core of electric-hydraulic control, bolting drill boom large section coal roadway shearer, heavy auxiliary transport equipment. The operation rates of fully-mechanized top caving equipment for full-seam and large mining height are 94% and 92.1%, and recovery ratios are 93.6% and 88.9% respectively. The annual raw coal production of single work face is over 10 Mt. The automation and intelligentization level have been clearly improved. The exploitation of thick and extra thick coal seam that is safe and efficient has been achieved in China.

Aug 1, 2013

By Werner W. Scholz

A corrosion-resistant lining is, quite often, selected on the merits of its corrosion resistance only. This paper demonstrates the effects of temperature, pressure, weather, design aspects and variances of physical properties within the scope of the generic designation of a corrosion-resistant material or materials. The base for the study is a rubber- and brick-lined steel vessel, with unchanged chemical conditions. Graphs and sketches illustrate the various effects of physical influences on the selected lining specifications.

Jan 1, 1979

By Ahmad Ghahremaninezhad, Noelene Ahern, Yeonuk Choi

Arsenic (As) is a toxic element and is a major contaminant in the extraction processes of some metals (e.g. gold and copper). Due to the toxicity of arsenic species, its removal from As-containing streams from extractive metallurgy processes and safe disposal is absolutely necessary. For nearly complete removal of waste arsenic species from metallurgical process streams, it is required to have arsenic in its pentavalent state (As5+ species). This study presents an oxidation process for arsenic species with air or oxygen gas as oxidant. Activated carbon (AC) or other carbon based materials are used to catalyse the oxidation reaction. Air or oxygen gas is the only consumed reagent which makes the economy of the process very attractive. The oxidation reaction can be carried out at ambient conditions (room temperature and atmospheric pressure) in less than 24 hours.

Jan 1, 2014

By R. Spring

"Soft-sensors are a computer software alternative to inadequate hardware instrumentation. Filters are averaging methods that reduce the noise in any sensor's signal. This paper introduces these topics and places them in a mineral processing context using then-product formula.Soft SensorsAs their name implies, ""soft-sensors"" are computer programs that estimate values for process variables (Tham, 1991). This approach is useful when the appropriate hardware sensor does not exist, is deficient, supplies only infrequent values, etc. For example, in mineral concentrators the traditional magnetic flowmeter/ nuclear density gauge instrumentation for measuring slurry flows costs $5,000 or more per flow and requires frequent maintenance. However, metal assays are commonly available from online X-ray fluorescence analyzers and application of the n-product formula (Taggart, 1945) to these assays conveniently provides software estimates of the flowrates (albeit only when the circuit is in steady-state).Soft-sensors are used by inferential controllers that base their control actions on the process values ""inferred"" by the soft-sensor. Such was the case at Brenda Mines where the rod mill feed tonnage controller used an inferred value of the cyclone overflow particle size (Bradburn, 1976). It was also the case at Brunswick Mining where reagent controllers adjusted reagent addition rates throughout the plant according to the various ore flowrates inferred by an expert system (Spring, 1991). A unique feature of the expert system soft-sensor was its dynamic flow models which compensated for residence times, material transport lags, etc. Thus the soft-sensor values were valid under both steady-state and nonsteady- state conditions."

Jan 1, 1992

By M. Dotto, T. G. Joseph, M. Curley

"Equipment selection is a key decision in mine planning. Equipment size affects decisions from pit size to the total operation cost. Particularly when replacing haulage fleets for long-life surface mining operations, mining operations focus solely on haulage productivity. Road width and specifically ramp width are significantly affected by an increase in hauler size in terms of overall strip ratio through required highwall set-backs or sterilizing of lower ore access due to required overlying ramp fill structures. In addition, in light of ever increasing regulatory and reporting emissions requirements, bigger equipment may not translate into lower emissions per tonne moved. This study analyzes hauler-scale impacts on aspects not currently incorporated into conventional mine planning, including expansion of roads to accommodate larger equipment, road layer thickness variation depending on hauler size, and fuel consumption and emissions. Results indicate that such relationships have a large impact on cost. Therefore, an expanded consideration of the capacities of increasing equipment size in mine planning is highly recommended. ¦ KEYWORDS Equipment selection, Grade resistance (GR), Haul road, Haul truck, Mine planning, Payload, Rolling resistance (RR), Total resistance (TR) RÉSUMÉ La sélection du matériel est une décision importante dans l’aménagement des mines. La taille de l’équipement a une incidence sur la prise de décisions, depuis la taille de la fosse jusqu’aux coûts totaux des activités. L’exploitation minière se concentre uniquement sur la productivité des moyens de transport, particulièrement lorsqu’il s’agit de remplacer les parcs de camions de transport dans les exploitations à ciel ouvert à longue durée de vie. La largeur des routes, et spécifiquement la largeur des descenderies sont considérablement affectées par une augmentation de la taille des camions de transport en termes du coefficient global de recouvrement qui dépend de la taille requise des parois (si les descenderies sont agrandies, les parois devront être creusées de haut en bas afin d’agrandir la taille du fond de la fosse). Il faut aussi pouvoir procéder à l’excavation des gradins les plus profonds de la mine et ainsi préserver l’accès à cette zone, ce qui pourrait devenir difficile si la quantité de stériles utilisés pour la structure des descenderies augmente et s’ils occupent une trop grande partie du fond de la fosse. En outre, au vu des exigences de plus en plus strictes en matière de réglementation et de déclaration des émissions, un équipement plus volumineux ne sera pas nécessairement synonyme d’une réduction des émissions par tonne déplacée. Cette étude analyse l’incidence de la taille des camions de transport sur des aspects actuellement non intégrés dans l’aménagement classique des mines, notamment la création de routes permettant le passage d’un équipement plus volumineux, la variation de l’épaisseur de la couche d’asphalte des routes en fonction de la taille des camions de transport, ainsi que la consommation de carburant et les émissions. Les résultats indiquent que ces relations ont des répercussions importantes sur les coûts. Ainsi, on recommande d’accorder une attention accrue aux capacités d’augmentation de la taille de l’équipement dans l’aménagement des mines. ¦ MOTS CLÉS aménagement des mines, camion de transport, charge utile, résistance au roulement, résistance due aux rampes, résistance totale, route de transport, sélection du materielINTRODUCTION Over the past five decades, the mining industry has progressively attempted to increase production rates through the use of larger haulage equipment. Each new generation of mine is designed to operate with the most recent and often bigger equipment iteration, while older mines are re-evaluated to keep pace with upgraded mixed fleets. Whereas production gains are often realized with larger equipment, there are additional aspects to consider when evaluating the feasibility of mo"

Jan 1, 2019

By P. E. Mather, M. J. M. Krane

Uncertainty quantification is a means of articulating the reliability of model estimations. Models of copper pyrometallurgical processes have been published for decades but discussion of their reliability has typically been terse and qualitative, mitigating understanding of their exact applicability to industrial situations. This presentation shows basic uncertainty propagation and Bayesian model calibration, two powerful uncertainty quantification tools, applied to a reduced order model of copper fire/anode refining. The implications of the uncertainty quantification analyses on the applicability of the model results to industrial practice are then discussed. Finally, other possible applications of uncertainty quantification to copper extractive metallurgy are explored. INTRODUCTION Modern copper production operations, including mining operations through wire drawing factories, are ubiquitously heavily instrumented. Most mine-sites and smelters have large repositories of historical data. That said, much of this data is not exploited to its maximum effect. This proceeding provides examples of using uncertainty quantification (UQ) to maximize the informational yield of the data collected from a fire-refining operation. Anode/Fire Refining is the final pyrometallurgical step in the production of copper anodes; it is an essential and universally employed processing step at smelters (Schlesinger, King, Sole, & Davenport, 2011). Much like the smelting and converting furnaces further up the process stream, anode furnaces are difficult to instrument due to their high temperature and the corrosive and/or caking quality of their offgas. This makes continuous and accurate measurement of the streams leaving the unit operation, e.g. liquid copper, slag, and offgas very difficult. As an example, offgas flowmeters, while providing continuous draft values, could miss the actual draft value by tens of percent due to caking or corrosion. UQ methods account for the uncertainty in process measurements and parameter values; they use a process model with measurements of performance indices to provide better and better estimations of process performance. This proceeding will first introduce a surrogate model for copper fire refining, made from a 1D, transient, reacting flow model of the process presented elsewhere in these proceedings (Mather & Krane, 2019). Discussion of the data used to make the surrogate model, as well as the creation of the surrogate model, will be included. Then, a Monte Carlo simulation will be performed, showing the expected soot production rate based on the surrogate model and assumptions about the uncertainty in the model’s parameters. Finally, the surrogate model parameters will be calibrated in a Bayesian way; this will tell what the actual uncertainty in the parameters are, given a set of observed industrial data and prior assumptions of the observations’ and parameters’ uncertainty.

Jan 1, 2019

By V. Cvetkovic, L. Zou, L. Jing

"Sorption process plays a significant role for solute retardation in rock fractures. In this paper, for the aim to investigate the effect of sorption on solute transport in a single rough fracture, a 2D model of representative single rock fracture was built and its roughness was statistically characterized based on the measured data of rock surface topography by laser scanning. A Finite Volume Method (FVM) code was developed to solve the Navier-Stokes (NS) equations and transport equation for numerical modelling the process of fluid flow and solute transport in the rock fracture model. Two groups of simulations were conducted: with and without the consideration of the sorption process with different average flow velocities. The results show that the surface roughness increased the complexities of flow fields, and the non-linear sorption process plays a significant role in the retardation of solute transport through rock fractures. The sorption process caused an obvious lagging time in both the solute concentration fields (plumes) and corresponding breakthrough curves. This lagging time increases with the distance from the inlet boundary, and relatively decreases with the increase of mean velocities. INTRODUCTIONFluid flow and solute transport in fractured rocks is an important research topic for performance and risk assessments for rock engineering projects concerning geo-environment safety, such as radioactive waste disposal, mining, geothermal extraction, reservoir engineering and other contaminant transport processes in geosphere (Berkowitz 2002).The solute transport in the rock fractures mainly involve the advection, surface sorption, matrix diffusion, dispersion, radioactive decay and chemical reactions, governed by general transport equations (e.g. Bodin et al., 2003). Among these transport phenomena, the sorption on the fracture walls can alter solute migration between the fractures, and play an important role in natural retention of solute transport (Weber et al., 1991; Wels et al., 1998; Kumar 2007; Dai et al., 2012). The aim of this study is to investigate the effect of sorption on the solute transport in a single rock fracture with rough surfaces. More complex transport processes, such as matrix diffusion, dispersions, radioactive decay and chemical reactions, are not included in this study."

Jan 1, 2015

By Xianglin Yang, Hong Zhong, Jingjing Xiao, Guangyi Liu

"The selective adsorption of a flotation collector to a mineral plays a crucial role in enhancing the hydrophobicity of targeted mineral particles for attaching air bubbles in pulp. The recent progress of the structure-reactivity relationship of flotation collectors, the characterization methods for mineral surfaces with adsorbed collectors and their commercial application are reviewed in this paper. Particular emphasis is placed on the density functional theory (DFT) for understanding the reactivity of new collectors, the surface analysis techniques including time-of-flight secondary ion mass spectrometry (ToF-SIMS), in situ scanning electrochemical microscopy (SECM) and atomic force microscope (AFM) to characterize mineral/collector interface, and the flotation technologies for optimizing recovery of valuable minerals. Especially, the recently developing collectors such as Gemini, alkoxyalkylthiourea, dithiourea, amide-hydroxamate and oximido-thiol surfactants, and their specificity to given minerals are evaluated. Based on this crucial review, it is evident that the structural modification approaches for minerophilic or hydrophobic groups, and combined surface analysis approach for further understanding the adsorption mechanism of collectors on mineral surfaces will lay a solid foundation for the future development of flotation collectors. INTRODUCTIONIn mineral processing, flotation is the main process for separation and recovery of valuable minerals from the ores contained them (Fuerstenau et al., 2007). One of the key requirements in flotation process is to increase selectively the surface hydrophobicity of the targeted minerals by collector adsorption so that these mineral particles can preferably attach to air bubbles in a slurry or pulp (Fuerstenau et al., 2007). Flotation collector is a kind of functional surfactant, which is composed of polar and non-polar groups (Somasundaran, & Wang, 2006). Non-polar portion, commonly being linear, branch or ring hydrocarbon group, is termed hydrophobic group. The polar portion, exhibiting strong affinity to mineral surfaces, is known as minerophilic group (Nagaraj, 1988). According to mineral types including saline, oxide and sulfide minerals, flotation collector divides into sulfide and oxide mineral collectors. For efficient recovery of valuable minerals from the refractory complex ores, insights into the adsorption mechanism, hydrophobic model and subsequent flotation approach of flotation collectors have been regarded as an indispensable issue in mineral processing."

Jan 1, 2016

By H. Deveci, E. Y. Yazici, A. D. Bas

The leach solutions of waste of printed circuit boards (WPCB) may contain a wide range of base and precious metals with different concentrations due to heterogeneity of these wastes in composition. Therefore, selection of a suitable metal recovery method is of practical importance for downstream processing of pregnant leach solutions of WPCB. Sulphuric acid leaching of WPCB in the presence of a suitable oxidant is capable of dissolving base metals as well as precious metals such as silver. In this study, cementation of silver from sulphuric acid leach solutions of WPCB using metallic copper, aluminum and zinc was studied. The WPCB sample was assayed to have a silver content of 694 g/t. A synthetic leach solution containing 20 mg/L Ag in sulphuric acid solution (0.51 M H2SO4) was prepared based on the silver concentration in pregnant leach solutions of oxidative sulphuric acid leaching tests. Total sulphate concentration ([SO4 2-]T) was kept constant using sodium sulphate at 1 M. Metallic powders of copper (-850 +600 µm), aluminum (-425 +45 µm) and zinc (-45 µm) were used in the cementation tests. The effects of metal type (Cu, Al or Zn), dosage of metal powders (above the stoichiometric ratio by up to 2000-fold) and temperature (20-80°C) on the rate and extent of silver extraction from the solution was investigated. The effect of presence of copper on the cementation performance was also tested. Under suitable conditions high silver recoveries (>90%) was achieved using metallic copper and zinc while aluminum yielded the lowest silver recovery (i.e. 40% Ag). The kinetics of cementation by zinc was comparatively higher than that of other metals. Increasing the temperature was observed to significantly enhance both the rate and extent of silver cementation. SEM-EDS studies were performed to characterise the metallic powders after cementation.

Jan 1, 2016

By Jeremy P. Richards

Key inputs are volatiles and heat: Slab dehydration: Breakdown of amphibole and serpentine in hydrated oceanic crust releases fluids into mantle wedge, causing metasomatism.

May 1, 2008

By Robert B. Parsons

"The mining industry is adjusting its sights to take a shot at the rising level of non-profit taxes which threaten to handicap the industry 's competitive advantage. In the case of this particular expedition, the industry evidentally has a strong ally - the country's mines ministers. It appears that an initiative is under way to assess the impact of non-profit taxes on mining in Canada as compared to other mining nations.IntroductionSeventy-five years ago, Canadians were unceremoniously introduced to something called income tax. Since then, income tax has been identified as the source of countless evils ranging from the common cold (attributed to stress) to the demise of the economy. Some years later, the provinces jumped on the bandwagon with their own income taxes, and later on with mining taxes. These profit-based taxes had some appeal to elected officials and to a segment of the populace. The onus of the taxes varied directly with the ability to pay (in theory, at least). Previously, the principal sources of government revenues had been property taxes and customs duties, which were viewed as possibly being somewhat regressive in nature.The mining industry has always had concerns about different aspects of income and mining taxes - the tax rate is too high or the depreciation rate is too low, and so on. Recently, though, the industry has turned its sights on the expanding array of taxes which are not based on profit, including payroll taxes, capital taxes, water taxes, sales taxes, fuel taxes, property taxes, environmental levies and user fees. The industry is seriously concerned that the rising level of non-pro fit-based taxes is not only hampering the industry 's ability to reinvest in Canada, but is also placing Canada at a disadvantage in terms of trying to attract new investment capital."

Jan 1, 1992

By Rodrigo Serna, Nora Schreithofer, Zoltan Javor, Kari Heiskanen

"Mineral floatability is a function of mineral properties such as size, liberation, shape, surface composition, reagent coverage on the surface, level of oxidation on the surface, etc.; pulp chemistry: Eh, pH, temperature, DO, reagent type, etc. and hydrodynamic conditions: turbulence, gas dispersion, D32, etc. The biggest challenge with predicting the floatability of an ore is finding a measurement method that would take into account the effect of all of the variables on the floatability of the minerals. The particle-bubble attachment time measurement is considered as an alternative way to predict the floatability of minerals instead of using expensive and time consuming flotation tests because it takes into considerations both surface chemistry and hydrodynamic parameters present in the froth flotation. The existing particle-bubble attachment time method is suitable for studying some significant flotation variables such as pH, temperature, particle size, reagent type and concentration. Nevertheless, measuring the attachment time as a function of collector coverage or surface oxidation is much more challenging. This paper introduces a new induction timer designed to measure the effect of galvanic interaction on the attachment time of particles. The new setup employs an array of needles to create 6 bubbles with the average size of 2.1 mm. Imaging system is used to set the initial distance between the particle bed and the array of bubbles. The attached particles are collected and sent for further analysis. One of the main benefits of the new experimental setup is that the attached particles can be physically separated from the unattached particles therefore many of the particle properties can be analysed and evaluated.INTRODUCTIONSchumann (1942), and Tomlinson and Fleming (1963) proposed that the flotation rate constant is dependent on four probabilities: particle-bubble collision (PC), particle-bubble attachment (PA), particlebubble aggregate stability in turbulent environment (PE), and particle-bubble aggregate stability in froth phase (PF). Any change in any of these probabilities will affect the overall flotation rate constant. All of the above-introduced probabilities are influenced by stream- variables and mechanical variables but their extent of influence vary. The stream variables are particle properties that have been shown to affect flotation rate constant such as size, shape, liberation, mineralogical composition, reagent surface coverage, surface oxidation, etc. The mechanical variables are the direct and indirect properties of the flotation unit affecting flotation rate constant such as cell and impeller geometry, air rate, impeller speed, air holdup, bubble size, residence time, hydrodynamics, froth depth, etc. For instance, the probability of collision is affected by many mechanical variables (bubble size, hydrodynamics, bubbles holdup etc.) but only one stream variable (particle size) has a major effect on it. On the other hand the probability of attachment is affected by much more stream variables: particle size, shape, liberation, surface composition, particle surface oxidation and collector coverage, Eh, pH, etc."

Jan 1, 2016

By Z. D. Hora

Sev_eral dozen si lica occurrences have been reported from various parts of Brit ish Columbia. Some represent hydrothermal veins or parts of pegmatite bodies; other are recrystall ized sandstones. Several vein type deposits were mined for smelter flux and as a source of white chips for stucco dash and simi lar products. Some quartzites were studied as potential sources of high-grade silica for ferrosilicon and silicon metal production. The province's only production of silica for ferrosilicon has come from a pegmatitic quartz plug near Oliver in southern British Columbia. Its reserves are now practically depleted.

Jan 1, 1984

By Jaana Romppanen, Satu Jyrkönen, Tiina Ranki, Peter Björklund, Markku Lahtinen, Kaj Eklund, Päivi Suikkanen

Outotec is continuously developing our existing process equipment and new equipment solutions to enhance the Flash Smelting process. Thanks to the long operating history of the Outotec Flash Smelting process feedback from the numerous operating references are available and is utilized. The general goals for development work are to improve equipment performance, thus realizing savings in Smelter plant operation costs by increasing the process efficiency and online availability. Digitalization also opens new possibilities for the feeding equipment and furnace operation monitoring. These solutions will improve the safety and performance of the smelter, and provide process and equipment related information which has not been available earlier. INTRODUCTION The year 2019 marks the 70th anniversary of Flash Smelting. The technology was operated on industrial scale for the first time at the Outokumpu Harjavalta copper smelter in Finland in 1949. The Flash Smelting technology, is now owned and developed by Outotec Oyj and the first plant, is now owned by Boliden Harjavalta Oy. The two companies have been evolving throughout history by optimizing the process for various feeds and raw-materials, as well as through developing the equipment and operating practices. Even though sustainability was not a hot theme/topic during the first days of Flash Smelting, it has nevertheless been the key principle in guiding the development. This is well proven by the wide adoption of Flash Smelting for the processing of copper and nickel concentrates, mostly due to its ability to fulfil the economic and resource efficiency criteria demanded by its operators. Along with the process technology development, also development of the equipment has taken place over time. Outotec is continuously working on developing our equipment to better suit the changing need of our customers in the continuously changing operational environment. Orebodies are getting more challenging with lower ore grades and more impurities. Achieving high recoveries for all valuable elements becomes more difficult with high slag quantities and with the need to tackle the high impurity concentrations. There is a need for higher capacities in greenfield and brownfield smelters. The role of the Loss-in-Weight Feeder, the Air Slide and Concentrate Burner is to ensure even feed into the reaction shaft of the Flash Smelting Furnace, and to enable controlling the process well, thereby enabling the best performance for the customers smelter. The design of the Flash Smelting Furnace aims for high availability, long campaign and safe operation.

Jan 1, 2019

By W. S. (Steve) Vaughan

The Origins of Joint Ventures in Canada?s Mining Industry ? Among the most important financing structures used in our mineral industry today ? Virtually unheard of in the Canadian industry prior to the 1970s ? Borrowed from the U.S. oil and gas sector where it came into prominence in the late 1930s ? The Securities Acts of 1933 and 1934 in effect killed the sale of (equity) shares for financing oil and gas wells and start up mining companies

May 1, 2013

By A. Singh

"The flotation of fine minerals less than 10 µm in size is an age old challenge spanning both the precious metal and industrial mineral sectors across a range of commodities. This problem has been brought into sharper focus by the emergence of the practice of fine grinding of flotation feed to effect better liberation of the targeted minerals. However, the ability of conventional flotation cells to effectively float the liberated fines remains questionable. In order to overcome this problem, Gold Ore postulates the “Bringing the Mountain to Mohamed” hypothesis which comprises the steps of gas nucleation on particle surfaces, aggregation of particles and levitation of aggregates. Testing of this hypothesis at Mintek, South Africa, showed a ~180% increase in the Kelsall kfast factor coupled with a projected recovery improvement of ~4 % for the Mach Reactor case coupled with a final concentrate grade of ~2 times that of conventional flotation. These fundamentals were then extrapolated to plant scale with Mach Reactors installed on the flotation feed at Platmin’s Tailings Scavenger Plant (TSP) with the objective of scavenging the fine minerals lost to tailings by the main plant. This paper details the theory, pilot plant results as well as key aspects of the full scale plant design supplemented by operational plant observations after commissioning. This game changing application is regarded as being pivotal to future flotation plant design whilst providing the technology leverage required for the survival of mineral operations in an economically unfriendly environment.INTRODUCTION - THE CONUNDRUM OF FINE PARTICLE FLOTATION“If the mountain won't come to Mohamed then Mohamed must go to the mountain” is an age old saying written into the book of proverbs in 1670. Legend has it that Mohamed promised his people that he would summon a mountain to come over to him so that he could offer up his prayers from its summit. After numerous attempts at moving the mountain went in vain, Mohamed, quite unabashed, said “Well if the mountain will not come to Mohamed, then Mohamed will go to the Mountain.” In this analogy, Mohamed is a fine particle <10 µm and the mountain is a bubble within a flotation system. The age old challenge is how to bring these two together to achieve attachment?"

Jan 1, 2016

By N. W. D. Davis

"As I have recently carried out some further research on the Navan lead-zinc deposit data while working in Michel David's research team, I should like to add a few comments on the paper- ""Universal Kriging for Ore-Reserve Estimation- Conceptual Background and Application to the Navan Deposit"", by M. Dagbert and M. David (CIM Bulletin, pp. 80-92, February 1976). The first comment is that since this research has been carried out, important new theoretical advances have been made which make for an easier application of geostatistics to the non-stationary case (see Matheron0l). This is the theory of intrinsic random functions of order k. With the aid of this theory, it has been possible to write computer programs which can carry out automatically universal kriging, although so far such applications have been largely confined to automatic contouring and not to mining problems. However, if approached with care there is no reason why these methods should not be applied to mining problems and, in this case, an automatic study has been done on this data."

Jan 1, 1976

By W. F. J. Cosser

AN agreement having been arrived at in 1935 whereby McIntyre Porcupine Mines would purchase gravel for back-filling purposes from Hollinger Consolidated Gold Mines, the aerial gear as described below was installed. As originally discussed, the plan called for installation of a loading bin at the junction to the Hollinger tram, so making the McIntyre tram an entirely separate unit. The experience of the Hollinger engineers, however, went to prove that the operation of a bin (remote from sources of heat) should be avoided if possible, owing to the severe winter conditions (35° to 40° F. below zero).

Jan 1, 1938

By C. B. Ndimande, C. Ntsele, M. Lisso, L. Arlow

"In the processing of UG2 platinum ore, stirred milling technologies are dominating regrind applications that require grinding the particles to P80s’ in the region of 45 µm. For this application stirred mills are 30–40% more energy efficient and require a smaller foot print compared to traditional tumbling mills. In this work a study was carried out using a batch pin mill and three scales of Stirred Media Detritors. A laboratory scale pin mill, a pilot scale Stirred Media Detritor with an installed power of 18.5 KW and two industrial scale Stirred Media Detritors in continuous operation, with an installed power of 355 KW and 1,100 KW were used. The industrial scale SMDs were in the secondary grinding section of a mill floatmill float (MF2) UG2 processing plants. The tests were focused on assessing the effect of feed rate and percent solids on power consumption and product fineness at lab scale, floatation response of the SMD product at pilot scale and on an industrial scale, the effect of feed rate on energy consumption and product fineness. The measurements obtained were feed flow rates, mill power and from the samples cut, particle size distribution of both feed and product. Specific energy was observed to increase with increasing percent solids over the 30wt% to 80wt% studied. Floatation response tests of the pilot scale SMD products show improvement in grade. Specific energy and reduction rations are observed to decrease with an increase in feed rate.INTRODUCTIONThe purpose of comminution in most mineral processing applications is to liberate the valuable minerals from gangue so that they can be recovered in subsequent separation stages. Most precious and base metal plants treat low grade fine-grained ores which require a higher degree of size reduction to yield the necessary degree of liberation (Partyka & Yan, 2007). Many authors have shown that the relationship between product size and grinding energy consumption is exponential, the finer the product from the comminution device, the higher the energy consumption (Gao & Weller 1993; Napier-Munn, Morell, Morrison & Kojovic, 1996; Jankovic, Valery & La Rosa, 2003). The suggested reason for this kind of relationship is that smaller particles have fewer flaws and higher strength than larger particles. Particles with fewer flaws and higher strength require higher energy for breakage to occur. One of the challenges most plants face is that of efficient energy utilisation in the liberation of the mineral from these complex ores. Conventional tumbling mills are not energy efficient in fine and ultra-fine grinding applications because some of the energy is spent on moving the charge and does not go directly into breakage. Stirred mills have been found to be about 30% to 40% more efficient and require a smaller foot print compared to traditional tumbling mills for regrind applications that require product size with P80s’ in the sub 45 µm regions (Radziszewski & Allen, 2013). Stirred mills are able to produce fine product because they can achieve a high number of stress events per unit time and volume compared to tumbling mills (Kwade, 1999a). To minimise energy usage without compromising product quality, the mining industry has adopted stirred milling technologies for fine and ultra-fine grinding (Radziszewski & Allen 2014; Kwade, 1999b). The south Africa platinum group metal (PGM) industry alone had over 40 stirred media mills installed by 2011 (Rule, 2011). Of that 40, 13 were in the ultra-fine grinding (UFG) application and the rest in main stream inert grinding (MIG)."

Jan 1, 2016

By D. Kao, J. Gogal, S. Humphrey, T. Byrne, M. Davoodi

"High total and dissolved uranium values were noted in the process water at the Cigar Lake Operation (CLO) during early production start-up period, whereas significant levels of dissolved uranium had not been observed previously at similar operations. The excess dissolved uranium resulted in higher demands on the water treatment plant, along with higher operating costs, environmental risks and some unrealized revenue potential. A species balance indicated that uranium was leaching into solution in the grinding, dewatering, and storage circuits under normal operating conditions. Jet boring, water recycle, ball milling, and the use of Pachuca tanks for ore storage results in a highly oxidative environment, which is favourable to leaching.This paper will outline the testwork performed to identify the conditions under which the uranium leaches into solution and to determine required conditions for uranium precipitation. Maximum uranium leaching was found to occur under normal operating conditions (pH ranging from 7.0 to 8.5); testwork indicated that both lowering and raising the pH can significantly reduce the uranium leaching. Analytical results combined with the batch scale testwork indicate that the uranium solubility is associated with carbonate species in the ore. Uranium precipitation was maximized at pH values greater than 10.5 or less than 6, corresponding well to carbonate leaching and precipitation values from literature. Higher precipitation efficiencies were noted at high pH ranges.As a result of this work, a pH control system has been implemented in the Pachuca storage vessels and thickener prior to water treatment plant on a trial basis. Caustic soda is recommended for pH control due to ease of operation, economic viability and material requirements and downstream constraints."

Jan 1, 2016