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By D. Gendzwill, N. Martin

"In early 1987, the Patience Lake potash mine near Saskatoon, Saskatchewan, was closed due to uncontrollable floodingWater inflows were first encountered during routine mining in 1975 at the south boundary of the mine lease. Underground grouting and construction of bulkheads limited the flo but did not completely stop it. Subsequent seismic surveys showed that the mine had approached the edge of a large collapse structure in which the salt and potash had been partly dissolved and removed by groundwater.In 1986, the small flow into the mine started to grow. Despite renewed grouting, the flood increased and outstripped pump capacity. The grouting program temporarily slowed the inflow but was unable to stop it. Eventually, from seismic and drilling evidence, it became clear that the water source was an extensive system of vertical fractures which would be impossible to seal by drilling and grouting from underground. A new plan to install 14 bulkheads underground would have sealed the water source from the rest of the mine but the construction program could not be completed before rapidly increasing inflow threatened to fill the mine. The underground mine was closed and a new solution mine started in 1988."

Jan 1, 1996

By J. B. Scott

"A computerized cost estimating program developed with the use of the Lotus 1-2-3 spreadsheet program has produced dramatic savings in preparing estimates for operating costs, equipment fleet size and manpower requirements for underground mines.The program is used by Dynatec to support its consulting engineering projects, particularly feasibility studies. The 'first principles' approach is used to prepare detailed estimates under direct labour and supplies categories and maintenance costs for each mining operation . User notes have been developed to guide the estimator and ensure appropriate consideration is given to the specifics of the particular mine.A typical case history is illustrated and the ease by which alternatives and sensitivity analyses can be prepared is demonstrated. IntroductionHistorical MethodsMining engineers have used one or a combination of methods to prepare operating cost estimates for new or existing mine s. Operating companies have access to historical cost data and generally use this for preparing estimates. Consulting engineers do not usually have direct access to such information and must rely on mining companies (the present or previous clients); publications (text books, equipment manufacturers manuals, CMJ reference manual, etc.); annual reports (applicable to public companies); previous studies (to be used with caution as conditions change from mine to mine); and first principles (the subject of this paper), for cost information:Definition of First PrinciplesA first principles approach to cost estimating considers individual primary work elements of an operation. Quantities of work items are developed from the mine plans, production rates, geographic and physical layouts etc. The knowledgeable estimator, assisted by experienced operations personnel, can assign appropriate resources (equipment, labour, supplies and services) to each work element and establish productivities. Completion of the cost estimate is then largely arithmetic."

Jan 1, 1988

By E. Roman, M. Brissette

"For its end of life, Kemess Mine processed its difficult-to-treat hypogene ore from the east pit, which is a lower grade copper and higher pyrite content gold ore. Metallurgical testwork showed that improvement was possible with finer grinding. In July 2010, small grinding media were introduced into the regrind mill resulting to a nearly 50% decrease of the power draw with a finer grind, an increase of 1.1% in the final copper grade, an increase of 1.2% in copper and 2.9% in gold recoveries at the cleaners. The overall recoveries of copper and gold increased by 0.6% and 1.3% respectively.INTRODUCTION Kemess Mine was located at 430 km North West of Prince George in North Central British Colombia. Its production started in May 1998 by Royal Oak Mines and was acquired by Northgate Exploration in 2000. Kemess reached its end of life production with its last of production on March 9th, 2011. The concentrator nominal capacity was 56,000 TPD consisting of a primary gyratory crusher feeding two identical conventional SAB circuits totalizing 35,840 kW available for grinding. Rougher flotation consists of four parallel rows of eight 130 m³ tank cells to produce a concentrate of 2% Cu and 6 gr/t Au which was pumped to a 5 m x 10.8 m regrind ball mill. The regrind installed power was 4,480 kW to generate a final grind of 80% passing 40 microns. This product fed the two stage cleaner flotation circuit, first stage being two parallel rows conventional 17 m³ Denver cells and second stage, two 3.3 m x 11.0 m flotation columns in series, designed and constructed by Kemess, to produce a 22% copper concentrate grade. The cleaner flotation middlings were returned back to the regrind mill (Froehling, Mohns, Roman & Grady, 2005; Froehling, Mohns, Rajwani & Fullam, 2007). The large copper-gold porphyry deposit was composed of 15% of oxidized supergene and leach cap ore and 85% of hypogene ore having three major alteration zones, mainly characterized by their sulphur/sulphide content. Chalcopyrite is the main copper mineral species with minor bornite. Gold was mainly present as free gold or electrum. The first alteration zone consisted of a phyllic alteration characterized by moderate and intense sericite alteration which had the highest mill throughput and twice the mine grade when in contact with the supergene horizon. The second zone consisted of a potassic alteration characterized by more competent groundmass and moderate to intense quartz stockwork which had a slightly lower mill throughput. Finally, a third alteration found beneath and on the east side of the deposit having almost no quartz stockwork and hardened groundmass, sulphide content is two to four times more. This zone had the lower mill throughput with significant drop in the mine average gold and copper grade. Through its mine life, the average life of mine copper head grade was 0.21% Cu and 0.64 gr/t Au. Head grades began to decrease from 2008 to be substantially lower in 2011 as shown in Table 1."

Jan 1, 2012

By Maya Kamenetsky, Khoi Nguyen, Natalee Bonnici, Steve Walters, Claire McMahon, Julie Hunt, Ron Berry

"The analysis of meso- and micro-scale textural attributes has been undertaken on ore samples from the Ernest Henry iron oxide-copper-gold (IOCG) deposit in NW QLD. Quantified textural data including grain size, shape and mineral association have been extracted from classified images of core with the aim to better predict potential mineral processing behaviours such as comminution, liberation and flotation. Data have been extracted from images of intact core at meso- and micro-scales using high resolution continuous images collected using automated core-logger technology, SEM-based and optical microscopy platforms.The results of this study will show examples of quantified size, shape and mineral association data from meso- and micro-scale classified images. Analysis of the data shows that there are domains of variable grain size and mineral association that can potentially be related to crushing and liberation behaviour. The trends that are observed at the drill-core (meso-) scale are consistent with those at the micro-scale. The results from the micro-scale analysis show that the domains defined at the core-scale have clearly different chalcopyrite sizes and shapes as well as variable bulk mineralogy.INTRODUCTIONInnovations in technology have allowed automated extraction of information about mineral shape, grain size and mineral association, i.e., texture, from meso- and micro-scale images of intact rocks. The overall aim of this research is to investigate trends in quantified textural data that can potentially give an early view of processing parameters such as predicted grind size and liberation behaviour."

Jan 1, 2009

By Mark Fernald, Christian O’Keefe, John Viega

"In this presentation, the SONARtrac™ technology platform will be described. CiDRA's proprietary clamp-on, passive sonar array-based flow meter technology performs two independent measurements – flow rate and fluid characterization. Firstly, the meter provides the volumetric flow rate of the mixture by measuring the speed at which naturally occurring turbulent structures convect with the flow past an axial array of sensors. Secondly, the meter uses similar sonar-based processing techniques and naturally occurring sound in the process fluid to measure entrained air levels. The result is a unique ability to measure the flow rate and entrained air level of most fluids – clean liquids, high solids content slurries, and liquids and slurries with entrained air.Also to be presented is the application of the sonar-based technology platform in a variety of oil sands processes, hydrotransport, and minerals beneficiation applications. In particular, difficult slurry flow measurement and control in the areas of comminution and flotation such as mill discharge, hydrocyclone feed/overflow, final concentrate, thickener discharge, and tailings will be discussed. In addition new real time maintenance free process measurement capability will be presented in the areas of entrained air in slurry, collection zone gas holdup (?g), and slurry velocity profiling. The operational advantages and value of these measurements, even in the presence of scale buildup, will be discussed.INTRODUCTIONFlow measurements in the mineral processing and oil sands industry suffer from the limitations placed by previously available flowmeters including the commonly used instruments such as ultrasonic meters, magmeters, turbine meters, orifice plate meters, vortex flow meters, Coriolis flow meters, and venturi meters. The desire or requirement to make a non-contact measurement that is accurate and robust, and can be performed on practically any type of fluid within practically any type of pipe has driven the creation of a new class of flowmeters. This new class of flowmeter technology utilizes sonar-based processing algorithms and an array of passive sensors to measure not only flow, but also fluid composition."

Jan 1, 2007

By S. F. Featherby

"This paper traces briefly the historical development of coal handling systems to meet the needs of a rapidly developing thermal power generation technology. The wide range of operating requirements is demonstrated by comparing and contrasting the Wabamun GS of Calgary Power Ltd. and a typical modern Ontario-Hydro thermal plant. The problems of safe storage of large tonnages of coal in stockpiles are discussed, together with recommendations for stockpile management. The development of coal bunkers and their management is discussed in detail, together with future trends in the industry."

Jan 1, 1966

By Fabian Mohr

The methyl substituted binuclear cyclometallated gold(I) complexes [Au2(?-n-MeC6H3PPh2)2] [n = 4, 5 and 6] all undergo oxidative addition reactions with halogens and, in the case of the 4- and 5-methyl substituted analogues, with dibenzoyl peroxide to give metal-metal bonded digold(II) complexes [Au2X2(?-C6H3-n-MePPh2)2]. The 4- and 5-methyl substituted digold(II) compounds on warming or exposure to light undergo carbon-carbon coupling reactions to give gold(I) complexes containing the corresponding 2,2'-n,n'-biphenylyldiphenylphosphines. The 6- methyl substituted digold(II) complexes rapidly isomerise above ca. -20° C to binuclear heterovalent gold(I)/gold(III) compounds [XAu(?-2-Ph2PC6H3-6-Me)AuX{?2-(6-MeC6H3-2-PPh2)}], containing a fourmembered cyclometallated ring on a gold(III) centre. Surprisingly, no carbon-carbon coupling could be induced for any of the 6-methyl substituted compounds, even under forcing conditions. This difference in reactivity of the 6- methyl derivative, compared to that of the 5-methyl and unsubstituted analogues was studied by ab initio calculations using a series of model compounds. The results are in excellent agreement with the experimental findings and suggest that the key-step in the C-C coupling reaction is the partial opening of the Au(III)-P bond in one of the transition states. In the 6-methyl system this transition state is energetically inaccessible and hence no C-C coupling occurs.

Oct 1, 2003

By G. Danha, D. Glasser, D. Hildebrandt, N. Hlabangana

"In this work, we apply a method known as the attainable region (AR) technique in order to optimize the milling and leaching process of a low grade gold ore. No work on the application of the AR optimization technique has been done yet on a joint milling and leaching process. The advantage of the AR approach lies in its ability to simplify the optimization problem, as searching over a defined set for the maximum of an objective function is a fairly standard procedure. The objective function we selected was that of optimizing a linear function of the value of the recovered material minus the cost of both milling and leaching. Using the three variables (milling time, leaching time and recovery), we constructed a 3D plot and used it to obtain all the possible recoveries from the different milling and leaching times. The optimum for our chosen objective was then found by overlaying a contour plot of the objective function on the 3D plot. Our results show that the optimum was obtained at 90 % recovery with a profit value of 600, milling time of 30 minutes and leaching time of 1750 minutes.INTRODUCTIONAfrican countries are facing a general increase in demand for electrical power. In South Africa, the demand is now surpassing the supply from ESKOM, the main electric power provider of the country. This has resulted in load shedding strategies being implemented in many local communities in an attempt by ESKOM to cope with the high demand. A potentially better approach is to propose use of energy efficient technologies in the country’s largest power consuming industry; the mineral processing sector.In mineral processing, milling is the highest consumer of energy. The objective of carrying out milling is not merely to reduce the particle size of the feed material, but also to liberate the constituent minerals that make up an ore. This is done so that valuable minerals can be separated from the gangue, in downstream processes, such as leaching. However, the milling process is generally performed relatively poorly, and at a considerable expense in terms of electrical power utilization. Tomanec and Milovanovic (1994) estimated that milling accounts for more than 50 % of the total power used in the concentration process, but this can rise to as high as 70 % for hard or finely dispersed and inter-grown ores. Apart from being relatively wasteful of energy, the milling process is also inefficient with regard to mineral liberation because of the indiscriminate nature of the grinding force."

Jan 1, 2016

By G. P. Contractor

Medium and low carbon steels, modified with uranium, were studied in order to evaluate the influence of uranium on forge ability, mechanical 11roperties, response to heat treatment and microstructure. Uranium contents ranged up to 0.70 per cent. The medium carbon steels are hot short if the uranium content exceeds about 0.35 per cent. More uranium can be tolerated in low carbon steels. The hot shortness is caused by the formation of intergranular phase UFe2. Critical transformation temperatures, Jominy hardenability, and resistance to tempering are not significantly affected by the 11resence of uranium. Similarly, uranium has little or no effect on the tensile properties of carbon steels. The addition of uranium has a favourable effect 11n the stress-rupture characteristics and some beneficial effect on fatigue properties. However, more results are required for verification. In the steels investigated, it seems that most of the uranium carbide combines to form complex inclusions of U (0, C, N) or (C, N), rich in oxygen or nitrogen or both.

Jan 1, 1963

By Erwin L. Zodrow

"The neglect of including the toxic metal mercury in the list of escaping elements (Zodrow, CIM Bulletin, September 1982, pp. 138-140) was pointed out to the author in a private letter by J.E. Rehder, dated September 21, 1982. I welcome this opportunity to present my preliminary mercury research data based on coal investigations supported by N.S.E.R.C and the University College.As mercury is a volatile element and liquid at room temperature, special analytical techniques are required to determine concentrations in whole coal. In the investigation, the coal is analyzed by flameless atomic absorption with a lower detection limit of approximately 10 parts per billion, which, however, is a function of the ash contents of the coals (personal communication, J.L. Brooker, XRAL, 1981).Coal seams of the Sydney Coalfield studied so far include: the Point Aconi, a thin shaly coal, the Upper Bonar, an overrider of the Harbour seam, and the Harbour, Shoemaker and McAulay seams, all of which are shown in stratigraphic succession in Figure 1. The seams have been channel-sampled taking 15-cm coal intervals as one sample for analysis. One channel sample has been investigated from each of the seams listed (two channels were taken from the Point Aconi seam), resulting in 38 samples. Table 1 shows the results, which include mercury contents, ash and total sulphur per sample interval. Figure 2 is a frequency distribution of the 38 determinations."

Jan 1, 1982

By Martin Murenbeeld

Outlook: Nine Bullish Arguments 1. Global fiscal and monetary reflation: PIIGS, US, etc. 2. Global imbalances: the dollar must decline 3. Global FX reserves are ?excessive?: diversification 4. Central bank attitudes to gold: now positive 5. Gold is not in a bubble: room to rise 6. Mine supply is flat: ?peak? gold? 7. Investment demand: long-run uptrend 8. Commodity price cycle: many years to run 9. Geopolitical environment: positive

May 1, 2010

By J. C. Loretto

"OPENING REMARKS Yesterday and today we have heard some very interesting papers on operating matters and some of you are probably wondering what we are now doing talking about Communications in Plant Design. Let me tell you! Before the techniques we have heard being discussed can be used, there has to be a properly operating plant. It is certainly a fact that many mineral processing plants achieve only limited success and a number of them can even be said to be failures. Some of you sitting here are probably living with operating problems that are clue to errors in the design.If the histories of these problem plants are examined, it will be found that in many cases, the necessary skills were available during the period of the plant design. There was extensive operating know¬ledge together with a full range of project expertise. Why then the failures? In a substantial number of cases it can be traced to the old, old problem of communications. As plants get bigger, money costs more and smooth startups become more important, it becomes less and less economic to fix up any design errors during plant operations.During our careers in mineral processing, nearly all of us will be involved in at least one plant design and I feel that it is as well if we understand some of these communication difficulties that can lead to a problem plant. There is little point in us being experts in mineral processing if the knowledge we have acquired doesn't somehow get incorporated into the plant.I would, therefore, like to present this short paper that mentions a few of the significant communication problems that can occur during the design of mining and mineral processing plants, together with some thoughts on answers to these problems."

Jan 1, 1973

By Tom Shumka

"All mineral processing facilities that use girth gear driven mills need to inspect the gear teeth on a routine basis, whether it be every six months to every three years. The inspection frequency depends on gear tooth condition, and the objective is to ensure the operational integrity of the gear teeth. Conventional methods such as magnetic particle testing, visual inspection or dye penetrant examinations rely heavily on operator interpretation. At best, these techniques can determine whether a defect exists, but are unable to provide information on defect severity. This paper describes the use of combining combined eddy current array (eca) and alternating current field measurement (acfm) to provide a complete survey of all surface breaking indications on the whole gear tooth depth. This method accurately determines the size, length and depth of any cracks found on the surface.INTRODUCTION In order to gain a fundamental understanding of the evolving operational and production behavior of a piece of machinery over a specified time period as part of an effective condition monitoring program, a robust data collection process must be firmly established and adhered to. To be effectively implemented within an organization, a condition monitoring program must have support of not only the maintenance, production and engineering staffs, but also executive management support to ensure successful roll out to realize the maximum productivity of the machinery and subsequent cost-savings. One of the key elements of a mineral processing facility that use gear driven SAG Mills as a primary stage for grinding solution, is the integrity of the critical gear unit that drive the mill. For the maintenance team, condition monitoring on the gear unit is crucial for preventative maintenance. A catastrophic failure in the critical gear unit would require a minimum of ten days to replace the gear set, depending on the damage occurred. This, of course, would only be applicable if the client had a spare critical gear set in inventory. If a gear set had to be ordered, it could take from four months to two years to receive a new gear set. For example, in 2007, there was a global backlog of these types of gears sets resulting in a two year delivery. The maintenance costs associated with a catastrophic failure of this type would easily cost in the millions."

Jan 1, 2012

By C K. Bell, L. S. Collett

An AFMAG survey was flown in 1968 over the Upper Nelson River area, Manitoba. The flight direction was northwest-southeast and flight spacing was 2 miles. In the Cross Lake Subprovince, AFMAG showed that an isolated peridotite outcrop was part of a dike that extended over 80 miles. Diabase dikes are not always marked by an anomaly, but isolated cross-overs, when used in conjunction with geological and magnetic data, permit their extrapolation. Anomalies coincide with areas of sulphide mineralization. In the Flin Fion Subprovince, known and unknown northeast-trending faults are detected. The Berry Creek fault was extended south through Tramping lake, then under the Paleozoic cover. Conductors were detected at, or near, the axes of major synclines within Amisk and Snow Group sediments. Granitic terranes have low conductivity and, because they are characterized by smooth AFMAG profiles, they can be delimited. AF.MAG is being recognized as a geophysical method that can aid geological mapping and interpretation. Its most important contribution to the geologist will be in regions where out-crops are sparse.

Jan 1, 1971

By Mark McComb, Geoffrey R. Lane

"Over the years many differing approaches have been developed to clearly understand the nature, mode of occurrence, associations and deportment of both free-milling and refractory gold in a wide variety of differing geologic environments and plant products. Many approaches can be taken to characterize the ore which may occur as complex fine grained gold, ultra-fine grained gold, coarse nuggetty gold, complex Asrich refractory gold and double-refractory gold. The approach taken in assessing small drill core composites from Novo Resources Beaton Creek Paleoplacer gold project located in the Pilbara region of Australia was complicated by the nature of the ore, the small amount of sample available from current exploration work, and the gold grade and the grain size distribution. In this case the scope of the study was limited by sample availability although significant amounts of valuable information was also gained. This gold characterization study included the following elements:??Size fraction assays??Ore microscopy??Preparation of heavy mineral concentrates from sized fractions (screening) of crushed or milled head using heavy liquids and Superpan table.??Systematic scans of the heavy mineral concentrate, middling, and tailing fractions using TIMA Automated Scanning Electron Microscopy integrated with an Energy Dispersive Spectrometry to provide semi-quantitative elemental analysis of the individual grains found in the sample.The unique methodology employed to detail the gold deportment was the combination of the Tescan Integrated Mineral Analyser (TIMA) and the Oxford INCA GSR software. This technique not only allowed us to document the deportment of gold but recognize other associated minerals, which included gersdorffite, chalcopyrite, uraninite, coffinite, brannerite and several Rare Earth-bearing minerals.INTRODUCTIONGold deportment studies are commonly carried out on preliminary gold exploration projects in order to determine the various limitations, which may effect processing of the potential ore. This is often because it may be expected that there may be a refractory component to the gold, which may limit physical separation techniques and suggest more costly hydrometallurgical techniques. Often when carrying out gold deportment studies the mineralogical methods may be limited to assuming that the gold will be fine and easily found using standard techniques of optical microscopy or Scanning Electron Microscopy. This may not always be the case as various geological environments may pose their own individual problems to determining the deportment of the gold grains."

Jan 1, 2015

By Y. Guglielmi, C. Gout, P. Henry, P. Dick

The key questions about fault reactivation in shales concern the potential enhanced fluid displacement through a previously low-permeability aseismic shale formation. Here we selected a critically-stressed fault cross-cutting the underground research facility of Tournemire (France) which is located in Toarcian shales. Several inclined boreholes were drilled across the 8.5 m thick fault zone characterized by a fractured damage zone (FDZ) and a central 2.4 m thick complex core (FC) made of multiple shear bands with gouge intercalated with highly fractured lenses. The fault was pressurized using a straddle packer system defining a 2.4m long injection chamber normal to the fault surface. Three fault zone intervals were tested, two in the fault damage zone and one in the fault core. A three-dimensional displacement sensor set in the chamber allowed continuous synchronous coupled monitoring of fault movements, injection pressure and flow rate. An anticlockwise 0.22-to-0.05 mm fault slip was captured associated with a 10-to-100 hydraulic aperture increase of the fault. Preliminary analyses of the experiments show that leakage in the fault zone is controlled by strength and stress magnitude contrasts between the fault core and the fault damage zone. Fault damage zone discontinuities display a much higher peak static friction angle than the fault core shear zones, respectively of 34 and 22° that could be related to complex interactions between healing and sealing processes. Fault core leakage is much more dependent on strain than on effective stress variations. Discontinuous, pulse-like leakage, develops following complex failure processes that may simultaneously take place in the gouge zones and along the large pre-existing discontinuities. Such results may be of importance in evaluating fault seal integrity in oil and gas exploration, production or CO2 storage or underground excavations monitoring.

Jan 1, 2015

By Steve Massman, Edward Wipf, Gary Beerkircher

"As mine size and tonnage continues to increase, material handling/processing equipment has also increased in size with 400 MT haul trucks, 2000 KW crushers, 12 M SAG/AG mills, 8.5 M ball mills, 3000 M3 flotation cells and 12.5 MW HPGR’s all with planned designs to increase in size further. Related equipment including vibrating screens have also increased in size with screens seeing feed rates of 3000 MTPH. Open circuit SAG Pre-Crush and closed circuit HPGR flowsheets are becoming more common with large screening requirements. Large multi-slope (banana) or horizontal screens are commonly used for these applications, however as the size of these screens has increased, the number and size of the brute force/overhead exciters has increased but with limitations. An example is a SAG discharge screen that will see surges of material from the SAG mill which overload the screen, reducing the screen stroke or throw causing a large reduction in screen efficiency with excessive fines & moisture in the screen oversize feed to the pebble crushing circuit. This paper will present some actual examples of the use of Two-Mass screens as a solution to these overloading problems and the advantages of Two-Mass screens in other high tonnage applications.Brute Force Drive Compared to Two Mass Drive Vibrating ScreensThe standard single mass screen as depicted by figure 1 is generally recognized in the mining industry. It is characterized by the screen body – labeled as the single mass (Mt) that is supported by isolation springs (Kiso). The stroke needed to process material is obtained by incorporating large eccentric wheels and/or drive boxes (Fb) directly mounted to the screen body via a drive tube."

Jan 1, 2017

By F. D. Ford, Z. Dai, A. Byers

Manitoba Mining and Milling operations consist of three underground mines (Thompson T1, T3 and Birchtree), feeding the Thompson Mill. Three years ago, a collaborative effort involving Mines Exploration, Mines Project Development Group, Mill Technical Services and Vale Base Metals Technical Excellence Center was initiated to establish and verify the cause of high variability in concentrate quality and Ni recovery at the Thompson Mill. One outcome of this work was a program to systematically characterize the mineralogy and metallurgical performance of current and future orebodies feeding the mill. Mineralogy results show that high value enabling ores typically have a high pentlandite to pyrrhotite ratio and benign silicate mineralogy (mostly quartz and feldspar from sedimentary host rocks), while metallurgically challenging ores contain some combination of pyrite and/or hexagonal (non-magnetic) pyrrhotite and/or elevated quantities of talc (with associated carbonates) derived from altered ultramafic host rocks. The metallurgical performance of these two ore types has been simulated by an Excel particle flotation model, which calculates the relative floatability of particles based on the particle’s mineral composition and mineral locking determined from MLA images. The relationship between these mineral properties measured by MLA and metallurgical performance was established using 13 monthly composite samples from Thompson Mill. The model was then validated with results of laboratory flotation experiments on individual orebodies submitted for evaluation. The validated model can be used to predict plant metallurgical performance based on individual ore bodies feeding the mill. Individual orebody’s grade-recovery curves are assumed to be additive, and can be weighted in proportion to the mill feed to predict mill recovery over the same time period. The ore mixing can be done with a simple Excel spreadsheet and comes with a graphical output for easy visualization of the resulting grade-recovery curve.

Jan 1, 2015

By A. A. Beland, R. J. Dawson, S. Shewchuk

"Shovel buckets, scraper blades, dipper teeth, mine car wheels and hammermills are examples of equipment which require routine maintenance due to abrasion. Service life can be extended by the use 0/hard/acing and buildup materials. Mining and milling applications are described and field welding procedures discussed.A high-stress abrasion test used to select hard/acing and buildup materials/or hammers in a hammermill is described in detail. Field tests of the selected alloys confirmed their performance, and maintenance records showed a significant saving in down time and cost.The relationship between the abrasion resistance of the alloys and their hardness, work hardening, composition and microstructure is summarized. IntroductionLarge volumes of ore are handled daily by the mining industry. The abrasive nature of most ores results in extensive wear to both handling and processing equipment. If such wear is neglected it may cause lost production time and also, in extreme cases, require the complete replacement of expensive equipment. The well-planned maintenance of components subject to abrasive wear by means of buildup materials and hard facing can result in substantial economic benefits. Such benefits can , however, only be realized through the correct choice of welding process, consumables and deposition methods available to maintenance personnel. Hardfacing MethodsHardfacing is applied by a variety of methods; the three most widely used being arc welding, oxyfuel gas and thermal spraying. Table 1 summarizes the major processes used within each method. Filler metals in the form of rod, wire or powder are necessary to fulfill the individual requirements of each process. The filler rods are available in the cast form or, in the case of ductile metals or alloys, as wrought rod or tube. All types are supplied bare or flux covered. Wire is supplied in two forms, drawn flux cored and drawn solid. Powder filler metals are available in many metals or alloys; they may be simple mechanical mixtures or prefused and atomized alloys made to a specific size range and shape for optimum results for each applicable process."

Jan 1, 1980

By N. Shi, T. G. Joseph

ABSTRACT: A prototype test dipper (at 1/20th volume and a geometric operating scale of 2.85) was compared during field trials against a conventional dipper with the same tare weight using the same test shovel. Both dippers followed similar dig trajectories, invoked by the shovel operator. A Microsoft® Visual Basic-embedded spreadsheet was used to interpret qualitative visual and quantitative numerical loading data collected on the hoist and crowd dig response. Overall the concept dipper, even with a 50% greater capacity, provided indications of a smoother dig cycle with lower peak hoist loading events and a lower energy per unit excavated.

Jan 1, 2011