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By Kosta Fytas, Nour-Eddine Chaouai

"Selection of the appropriate kriging plan during indicator kriging estimations is of a paramount importance to the precision of ore reserve estimation. However, very little is known on the sensitivy of indicator kriging results when changing the kriging plan parameters (mainly search distance and number of samples). This paper evaluates the effect of the search distance and number of samples on indicator kriging results using a gold deposit as a case study.IntroductionBlock estimation using kriging is based on the autocorrelation function (variogram) on one hand and on the kriging plan on the other. As far as the variogram is concerned it is more or less subjectively adjusted and this is reflected on its parameters (range, sill, nugget effect and anisotropy). The effect of a poor estimation of these parameters on the kriging variance of ordinary kriging has been proven very important (Brooker, 1986). Choosing a kriging plan is generally a difficult matter depending on the estimation type (global or local). Generally there is not a unique kriging plan be cause there is not a unique structural analysis (variogram). There are no rules or dogmas in choosing a kriging plan but it is rather a function of the sampling pattern (David, 1982).Structural analysis requires the hypothesis of quasistationarity but very often either the data available within the zone of quasi-stationarity are too many so that the search distance is reduced during kriging or the data are too few to satisfy a stationary kriging system (Journel and Huijbregts 1978). As a rule, the larger the neighbourhood, the more precise the estimates should be , but for large neighbourhoods the hypothesis of stationarity does not always hold (Rivoirard 1987; Armstrong and Champigny 1989)."

Jan 1, 1991

By P. L. Lehoux, R. F. Lopes

"Unanticipated low recovery or extraction of gold from heap leachable are can often be attributed 10 phenomena such as non-uniform percolation (channelling) of solution through heaps, excessively slow percolation rates due to densification of ore during stacking on the pads and parasitic or competing reactions of the cyanide solution with undesirable elements or geochemical ""impurities"" in the ore. The nature and causes of these phenomena are discussed in this paper, and it is suggested that geotechnical and geochemical expertise can contribute significantly to a better understanding of the relationship between laboratory results and actual field performance of the leaching process. Recommendations are made for bench-scale metallurgical testing to be complemented by geochemical and geotechnical laboratory evaluations, to ensure more successful heap leach projects. IntroductionHeap leaching is a simple, low-cost method of recovering metals from low grade ores which has now come into widespread application particularly for gold and silver metals in the United States.The heap leach process involves percolating a lixiviant (leaching agent) solution through broken or crushed ore (Chamberlain and Pojar, 1984). In the case of gold a dilute sodium cyanide solution is used and crushed ore is ""heaped"" on specially prepared impervious pads.The potential for use of heaping leaching methods for northwestern Ontario gold deposits was discussed by Beard (1983), who suggested that the use of this extraction technique in Canada should grow significantly for low grade ores as well as for small high grade deposits which cannot justify the installation of a new mill or the use of remote custom milling facilities. Two other potential situations for lise of a heap leaching extraction method are : as a low capital cost cash generator in the opening phase of a larger new project, and as a low cost output augmenter to complement a milling operation."

Jan 1, 1989

By Kurt D. Mitchell

"This paper discusses general application for A C variable frequency drives in the mining industry. A review of induction motors characteristics, adjustable frequency controller fundamentals, and three commonly used controllers is presented. General application guidelines for the three different types of controllers; variable voltage input , current source input and pulse width modulated are then reviewed in detail, and an example of the economic benefit of this technology is discussed. IntroductionSoon after static DC variable speed drives were well established in industry, a need for static AC variable speed drives was seen. The first technical papers describing possible systems appeared in the mid-1960s, with commercially available units arriving in the early 1970s. Without exception, static AC drives are substantially more complex than their DC counterparts, but they have some very desirable properties. As compared to DC motors, AC motors are less costly, physically smaller, more reliable, require less maintenance , easily sealed, have good load regulation, are able to run at higher operating voltages, and have little danger of over-speed runaway . These properties are particularly desirable in explosion-proof, submersible or difficult accessibility applications.Variable speed AC drives are now a proven technology. available in packages from Sub-horsepower to hundreds of horsepower, from 115VAC to 4160 VAC. This paper covers the principles of operation of three common types of controllers, application criteria, motor consideration and finally an example of how an AC variable speed drive can pay for itself in terms of energy savings."

Jan 1, 1986

By R. L. Guerguerian, Eugene Bercel

"Grinding mill hydrostatic trunnion bearings require an external pumping source to provide and maintain the oil film between the bearing members. In order to guarantee a predetermined minimum film thickness, the lubrication system tends to be oversized. The oil film is ""indirectly"" controlled by flow, pressure and temperature monitors with fixed settings on the conservative side. This can lead to excessive maintenance and abbreviated life for the lubrication system components. A reliable method of monitoring actual film thickness would not only provide greater mill availability, but also minimize maintenance costs.This paper describes the instrumentation installed in Dominion hydrostatic bearings, and presents results of field tests where the output of that instrumentation was recorded under various operating conditions.IntroductionThe trend toward larger and more sophisticated grinding mills has made the operators of these machines increasingly vulnerable to financial loss, as the cost of downtime and repairs has increased directly with machine size. In order to guard against such losses, it is becoming imperative that large, sophisticated grinding mills be equipped with protective instrumentation to monitor some of the critical operating parameters and to identify events and trends which, if they go unnoticed, can lead to excessive maintenance costs and machine downtime. The idea of protective monitoring systems is not new. The operators of certain types of machinery where a high degree of safety is required or where machinery health can deteriorate very rapidly, as in the case of high-speed turbo-machinery, have long been using protective instrumentation on their machines. The increased awareness of the benefits of monitoring machinery conditions and the availability of reliable and relatively low-cost instrumentation of a large range of sophistication is making the practice now widespread. Traditionally, grinding mills have not been considered as high-risk machinery requiring instrumented protection. However, the trend, mentioned earlier, toward employing fewer, but larger capacity, mills increases the risk of significant disruption of production, and therefore measures to minimize the risks are desirable."

Jan 1, 1981

By Edward Martinez

Laboratory studies had shown that the magnetite contained in serpentine asbestos ore was not uniformly distributed. Ore particles containing chrysotiye fiber responded to a magnetic f field; particles containing little or no chrysotile were essentially non-magnetic. Larger-scale tests, run with a magnetic pulley being fed various asbestos samples ranging in size from 1/4 inch to 5 inches, confirmed that magnetic separation could be used as a concentration step in an asbestos mill. Magnetic concentration was installed at the Black Lake and National mills of Lac d'Amiante du Quebec and has allowed the extraction of lower-grade ore, increasing the life of the mines. In addition, preconcentration early in the flowsheet increased the value of the feed to the fiber recovery section. An increase in fiber production was achieved, as well as a decrease in maintenance costs due to removal of flow-grade tailings early in the flowsheet. Magnetic concentration of a coarse tailings from the mill resulted in recovery of additional fiber previously discarded to tailings.

Jan 1, 1979

By P. R. A. Andrews

"Areas of bubble contact were delineated for cassiterite in the presence of chloride, fluoride, sulphate, phosphate, oxalate and citrate ions using dodecylamine hydrochloride collector. The limits of pH, and the minimum collector concentration were established using the bubble pick-up technique.Bubble contact did not occur below the p.z.c. (point of zero charge), estimated to be 4.7, in the presence of chloride ion, and fluoride ion showed only a weak response in the same pH range. These anions are considered to act as indifferent electrolytes. Activation at pH values below the p.z.c. was obtained with sulphate, phosphate, oxalate and citrate ions; the greatest response was by oxalate and phosphate ions extending pick-up to between pH 2.0 and 2.5.Activation appeared to be strongest when anionic protonated species were in maximum concentration. Strong activation also corresponded to the formation of very stable metal ion species, thought to be formed on the surface of cassiterite, between exposed stannic ions and modifying anions; dodecylammonium ions being absorbed on the surface so modified."

Jan 1, 1991

By D. F. Sangster

"Eight volcanogenic massive sulphide districts in Canada and Japan, ranging in age from Archean to Miocene, were selected for analysis. The study revealed that: {I) each district has an average diameter of 32 km; (2) the districts contain 4 to 20 deposits each, with an average of /2 deposits; (3) the average total base metal content per district is 4.6 million tonnes, with a coefficient of variation of32%; (4) ranked in order of size, the largest deposit in each district contains, on average, 67% of the total metal and the second largest about 13 %. The remaining deposits range downward in decreasing proportions. Empirical observations such as these may be used f or evaluating the undiscovered potential of new districts as well as contributing to a better understanding of the distribution and genesis of this important class of base metal deposits. Previous WorkThe characteristic geological features o f volcanogenic massive sulphide deposits have been described by numerous authors over the past fifteen years and it is now widely accepted that these deposits comprise a major ""deposit-type."" In addition to these geological parameters, however, it is now becoming apparent that volcanogenic massive sulphide deposits show several distinctive grade-tonnage relationships. For example, Singer et al. (1975) demonstrated a slight negative correlation between copper grade and ore tonnage in their sampling of 146 volcanogenic deposits. In a study of 110 Canadian Precambrian deposits of this type, Boldy (1977) showed that the size of the modal deposit is 0.39 million tons, that of the median deposit is 1.40 million tons and the arithmetic average is 6.85 million tons. Moreover, Boldy's data show that the average grade of combined base metals (Cu + Zn + Pb) for each of the se three deposit-sizes is, respectively, 6.25%, 5.35% and 6.47%. Because the lead content of Canadian Precambrian volcanogeni c deposits is most frequently less than 1%, the total metal grade is effectively Cu + Zn . From Figure 2 in Bold y (1977), it can be seen that 83% of the deposits fall in the range of 0.l to 10 million tons ."

Jan 1, 1980

By C. J. Mwenifumbo

Preservation of groundwater quality is a major environmental concern. The disposal of hazardous material from urban waste dumps, milling wastes in tailings ponds, and industrial wastes in injection wells may contaminate potential sources of potable groundwater. The containment or migration of contaminants in the subsurface depends on bedrock characteristics and type of overlying sediments. Fractured bedrock and permeable sediments that may provide pathways for the transport of potentially harmful contaminants should be avoided when selecting a disposal site. The role of borehole geophysics in hazardous waste-site investigations is reviewed in three categories: (I) site selection; (2) determination of the extent of contamination at existing sites; and (3) long-term monitoring of migration of contaminants. In the first category, borehole geophysical techniques developed for lithology and fracture identification, and for porosity determination, provide some of the necessary information for understanding the subsurface hydrogeology. Lithological information can be obtained from gamma-ray, electrical resistivity, induction, magnetic susceptibility, and sometimes induced polarization logs; fracture detection and characterization can be accomplished with the use of caliper, density, resistivity, temperature, and acoustic televiewer logs. Estimates of porosity are derived primarily from neutron-neutron, resistivity, density, and soniclogs. Borehole geophysical techniques used in water quality determinations include self-potential, fluid resistivity, Eh (redox potentials) and pH measurements, and these can be used to map the extent of contamination at an existing waste site. Cross borehole and borehole-to-surface electrical methods can also be used in this application. Long-term monitoring of contaminant migration in boreholes can be accomplished with techniques that respond to changes in electrical conductivity, temperature and fluid chemistry caused by the presence of contaminants.

Jan 1, 1993

Objectives ? New deposits can be found in mature Mining CampsNew Camps ? Volcanogenic Massive Sulfide (VMS) deposits ? polymetallicpolymetallicexamples are desirable exploration targets examples ? Genetic and exploration models for VMS deposits are robustrobust ? subtle but important differences exist between deposits and districts ? sometimes ??neglectedneglected??in resource modeling and exploration efforts ? ReRe-evaluation of a prominent existing camp is rewarding ? update on the exploration strategies currently being applied on a practical level The Falconbridge-Alexis approach includes GoCAD modelling

May 1, 2006

By Louis Tellier

SIDBEC commenced detailed planning of major capital expenditures to install integrated steelmaking facilities in 1969. Today, less than IO years later, SIDBEC and its subsidiaries have completed major mining, concentrating, pelletizing, direct reduction ? electric furnace steelmaking and continuous casting plants. The total cost of these projects was almost 1 billion dollars. The philosophy behind the project planning and the evolution of management control are explained. These extensive projects were undertaken during a period of exceptional inflation and a disturbed labour climate, but were nevertheless completed with only modest overruns, with good control of timetables and with exceptionally good start-up performance. Project planning, relations with consulting engineers, introduction of new technology, purchasing and field management and cost control are discussed.

Jan 1, 1979

By A. Chieregato, C. G. Oñate Salazar, D. Martinelli, D. Peila, M. Barbero

This paper is aimed to confirm the possibility to excavate fractured rock masses by using EPB shields, even in presence of relevant water tables. This verification is based on laboratory test experiences carried out at TUSC laboratory of Politecnico di Torino, where the natural material is tested in order to verify the suitability of a certain conditioning technique in particular conditions. This is due to the fact that every case should be studied apart from existing studies on a certain rock type, as other factors such as fragmentation of the rock mass, natural water content and porosity of the rock can considerably influence the final result of the conditioning process. The most important aspects that allow to consider the conditioning of fractured rock masses as suitable are: possibility to create a plastic paste that can transmit the pressure at the front in a effective way; reduce the permeability of the spoil material in order to reduce the possibility of water leakage inside the chamber and eventually in the tunnel; verify the consistency of the conditioned material for the extraction through the screw conveyors and the belt conveyors. For this research an argillitic schistose rock mass, with some quartzitic and calcareous inclusions, has been studied by using different level of conditioning in order to verify the suitability of an eventual EPB excavation through this formation.

Jan 1, 2015

By D. V. Krefting, D. R. Bennett

"The Cyprus Anvil Mining Corporation established a lead-zinc mine and concentrating plant at Faro in Yukon Territory in 1969. Following some 12 years of continuous operation from a single pit adjacent to the concentrator, the company decided to expand operations into two additional areas on the Vangorda Plateau. The two new deposits, known as Grum and Vangorda, are located some 15 kilometres from the existing concentrator.Confirmation of mining feasibility was followed by determination of the most practical and economical method of transporting the raw ore from the new mine sites to the existing concentrator. This analysis was carried out in two phases. The first phase reviewed the feasibility of alternative transportation systems on an 'order-of-magnitude' cost basis. This work identified systems worthy of more detailed examination. The second phase examined the preferred alternatives in greater detail.Initially, operating principles and parameters were established and catalogued. Then, based on these criteria, complete systems were developed utilizing alternative modes of transportation . In the overview analysis, some transportation modes were judged impractical and discarded, 'order-o f-magnitude' costs were developed for other systems and the most costly were eliminated . In the detailed study, the favourable systems were examined in depth which required development of accurate capital and operating costs, consideration of environ- mental impacts and an assessment of intangibles associated with the operation of a new development."

Jan 1, 1984

By M. Beech-Jones

The increased emphasis on the efficient utilization of capital and mineral resources has led to several new advances in the science of mineral separation. One example of a recent development is the application of high-capacity high-intensity wet magnetic separators to fine hematit e recovery by a leading Canadian iron ore producer. The iron ore recovery feasibilit , flow-sheet development, circuit operation and metallurgical performance are reviewed.

Jan 1, 1979

By Brian McIntrye, Bo Trygg

"The need for grinding mills of ever increasing capacity and greater feed openings has tended toward mill trunnion diameters being beyond the size limits for roller bearings.Hydrodynamic plain bearings need to be wide enough to achieve the necessary bearing pressure in order to obtain an oil film with sufficient carrying capacity at low rotational speeds. This greater width increases edge loading resulting from the deflection of the mill under load.Because of the high surf ace pressure involved, the life of support rollers and girth rings is often inadequate-fatigue leads to flaking on the contact surfaces. Heat treatment of the girth rings also has its problems.The hydrostatic shoe bearing permits unlimited trunnion diameter and a high carrying capacity. The self-aligning shoes compensate automatically for radial deviations and large deformations can be tolerated at the girth ring.The sliding surfaces are completely separated by oil under pressure, enabling negligible starting torque and good damping capacity to be achieved together with low rotational speeds.IntroductionHydrostatic bearings have been known within machine technology since 1865, when the Frenchman Girard received a patent for such a bearing. During the following 75 years, these types of bearings were used sporadically for thrust bearings, primarily in water turbines. The first usable radial bearing was not designed until 1938. Since the 1950s, when hydrostatic bearings started to come into use within the field of machine tools, extensive research and development work has been carried out at various institutions and research centres throughout the world. Many support problems are now solved by means of hydrostatic plain bearings and the primary factor in deciding to use them is their unique characteristics:• ability to carry high loadings• no starting torque• large damping capacity• no wear• large running accuracyThe hydrostatic shoe bearing has been developed specially for use in the heavy machine industry, with the requirements for high loadings and large support diameters which this market demands."

Jan 1, 1982

By K. Woo

"With ever-increasing global demand for mineral resources, mining companies are considering developing deeper, more complex and lower grade ore bodies. Recent years have seen the transition from surface to underground mass mining operations to access deeper resources, with mass mining methods such as block and panel caving being favoured due to the tonnages and economics achievable when dealing with lower grade ore. However, the rock engineering interactions involved with such plans are complex and challenging given the significant disturbance caused to the surface environment. If not properly accounted for, the unexpected propagation of a cave breaking through to surface or the differential surface displacements otherwise produced may threaten the safety and integrity of overlying mine and civil infrastructure.This paper reports the findings of a comprehensive research programme focussed on investigating and integrating new developments in remote sensing characterization and monitoring technologies with state-of-the-art numerical modelling to better manage the challenges and geo-risk associated with the transitioning from open pit to underground mass mining. Procedures were developed to integrate discrete fracture networks (DFN) into finite-element/discrete-element analyses to simulate the influence of rock mass fabric on cave propagation and the evolution of caving-induced surface subsidence and step-path failure of large open pit slopes through the progressive failure of rock bridges. The results clearly showed that caving-induced surface deformations tend to be discontinuous and asymmetric due to large movements around the cave controlled by geologic structures, rock mass heterogeneity and topographic effects. Although parallel investigations of empirical design charts used to predict caving-induced deformations were found to be moderately sufficient for assessing the extent of macro deformations directly above the undercut (i.e. caving collapse features), numerical modelling was found to provide the only means to confidently estimate the lateral extent of smaller strain subsidence.These results were further supported by the use of high-resolution synthetic aperture radar (SAR) data to monitor the ground deformations associated with block caving production, and to use these to calibrate and constrain a series of predictive 3-D numerical models focussed on Rio Tinto's Palabora mine in South Africa. The InSAR data was obtained from Canada’s recently launched RADARSAT-2. The close fit achieved between the predictive 3-D numerical model and InSAR monitoring data demonstrates the significant value of InSAR calibrated 3-D numerical models applied to subsidence prediction.Collectively, the results from this research programme have helped to further the characterization, assessment and understanding of mass mining-induced subsidence, and its evolution, by addressing existing limitations in the use of empirical and numerical design methods. The limitations and uncertainty arising from mine site data were detailed, specifically the representation of mine geology, rock mass properties, in-situ stresses and cave propagation, together with means to constrain these inputs and calibrate sophisticated 3-D numerical models through back analysis and integration with high resolution monitoring data."

Jan 1, 2015

By M. Walmsley, D. Maynard

"This paper describes the use of terrain and soil information in the planning of mine developments, particularly in satisfying many of the existing provincial regulatory requirements. It is also noted that, if properly used, this will provide a solid data base for cost-efficient and environmentally acceptable land use.IntroductionIn planning the development or expansion of a new or existing mine, engineering alternatives are judged on many factors, one of which is the environmental influence. Ecological investigations, ensuring consideration of a rational approach to managing land use and environmental impacts, should be carried out prior to a final decision being made on mine development. The Pit Slope Manual (CANMET, 1976) suggests that both baseline aquatic and terrestrial data be collected and interpreted in such pre-mining surveys. In British Columbia, planning procedures now exist which incorporate biophysical studies to help identify, assess and manage major environmental impacts associated with mine development.Methods outlined in the Guidelines for Coal Development (E.L.U.C., 1976) have been successfully applied in recent years. Following this example, the Inspection and Engineering Division of the B.C. Mineral Resources Branch prepared guidelines to help expedite the development of new base metal mines (Procedures for Obtaining Approval for Metal Mine Development; Ministry of Energy, Mines and PetroleumResources, 1979).The metal-mine guidelines require the proponent of a new mine development project to prepare a two-stage assessment proposal which systematically moves from a preliminary feasibility study (Stage I) to a final project design (Stage II), including application for regulatory approvals. One purpose of the Stage I report is to provide a description of the existing environmental conditions that could be affected by the proposed development. A preliminary environmental impact assessment should also be reported. The Stage II report will contain detailed assessment and management of environmental impacts."

Jan 1, 1981

By Tony B. Szwilski

"The efficiency of operation and life of an advancing longwall coalface depends, to a great extent. on the face-end roof strata conditions and the stability of the gateroads. The factors that influence the rate of closure of gateroads are examined, in particular the gateside pack and the coal rib (crush) pillars. The performance of mechanized packing systems is briefly discussed. Gateroad deformation surveys were carried out at two coal mines to determine the influence of the rib pillar width on gateroad stability; also, the influence of the gateside pack on the immediate roof and floor strata is analyzed based on strata bed displacement measurements from instruments installed in the gateroad and pack-hole of a longwall advancing face operating in a thick seam (7.55 m). Concluding, an evaluation of the fac e-end systems examined is given and recommendations made f or the most suitable rib pillar width. face-end geometry and roof strata reinforcement.IntroductionKevword s: Coal mining, Pillars, Rib pillars, Ground control, Longwall mining, Gateroads , Packing systems, Roof control. The face-end region of a longwall advancing face is the center of mining activity, being the turn-around point for the coal cutting machine. and the place of gateroad formation and movement of special face-end supports. The design of face-end layouts can be aided by knowledge of strata control parameters, such as the effective loading of the immediate roof strata , convergence of the roof and floor, magnitude and distribution of fractures in the roof strata around the face-end , optimum placement of supports, coal seam thickness and strength characteristics, geometry of layout and interaction from neighbouring workings. Generally, the gateroad is formed by one of three face-end methods: (a) advanced headings, (b) in-line system (gateroad formed at the face) or (c) conventional ripping with or without stable elimination (also halfheading). The quality of gateroad is influenced principally by the face-end system employed, standard of gateside pack and width of pillar. A good standard of gateroad is generally achieved by employing the half-heading face-end system, the gateside pack and coal rib pillar having comparative support/ yield (stiffness factor) characteristics. However, the halfheading is often not favoured due to face operation restrictions."

Jan 1, 1981

By S. C. Tadolini

"Roof bolts are the primary means of roof support in underground mines in the United States. Presently, post installation loads are measured on about 10% of the expansion anchor and combination bolts by using standard torque wrenches that Unit the accuracy of the measurements to about ±30%. No system has been available for measuring the loads generated on full-column resin grouted bolts. Mine roof bolts are long, slender, non-uniformly sized, roughly forged, and placed in a corrosive environment, creating obstacles for researchers trying to utilize ultrasonic reflection techniques to measure strain. A complete measurement system has now been developed by the U.S. Bureau of Mines, Denver Research Center. This system is being used successfully in determining loads measured on expansion anchor and combination bolting systems, examining the transfer mechanics of full-column, resin-grouted bolts, and measuring loads generated on bolts in an underground roadway support system.IntroductionMillions of roof bolts are used each year to provide structural support in underground U.S. metal, non-metal, and coal mines. Approximately 45% of the bolts used are expansion anchor, 45% are resin-assisted combination or full-column resin-grouted, and 10% are friction anchored. The effectiveness of these bolting types is dependent on a number of factors including rock density, bolt length, in situ stresses, rock properties, bolt pattern, installation tension, etc. When implementing expansion anchor and resin assisted combination bolts , installation and post-installation tension, or load, is a major determinant of support quality and subsequent behaviour of the reinforced roof. The method by which these systems carry roof loads is well understood and documented(1,2).The importance of these installation and long-term bolt tension measurements is well recognized and are required in the federal government regulations(3). A statistical sample of the bolts, lout of 4 during installation and lout of 10 inby the last open crosscut, is required to be measured using current torque wrench technology. The disadvantages of this system are the disturbance and weakening of the anchorage and limitations of accuracy to approximately ± 30%. The method by which resin-grouted bolting systems carry roof loads is much less understood, mainly because testing procedures used to evaluate point-anchor systems are not effective on resin-grouted bolts.Due to these problems, the U.S. Bureau of Mines designed a measurement technique that provided a highly accurate, low cost-per- bolt system that led to the development of ultrasonic pulse echo instrumentation. The original system was designed to measure the tension only on expansion anchor bolts. Recent developments and system modifications have permitted measurements on resin-assisted and full-column resin-grouted bolts. The use of these types of support systems has been increasing steadily in underground coal mines.The development of this instrumentation has provided laboratory and field results that help to explain the mechanics and relationships between the applied loads and the interaction between the grouted bolt system consisting of the bolt tendon, grout, and rock."

Jan 1, 1990

By G. Grant Smith

In situ bulk density of coal is a variable applied to various aspects of coal resource evaluation, such as compositing ply analyses of coal attributes that are expressed on a weight per cent basis, and determining tonnages from volume estimates. Its value is a function of composition and porosity of the in situ material. When densities of ash-free coal, ash and water are fixed, in situ bulk density of a coaly mix can be expressed as a function of proportionate weight of ash in the mix. Correlations between in situ bulk densities and weight per cent ash contents of coaly mixes have been estimated for four general rank classes of coal (low medium volatile bituminous, high volatile bituminous, subbituminous, and lignitic).

Jan 1, 1991

By D. L. Churcher, R. J. Perry

"In recent years much work has been don e to examine alternate underground backfill support systems with the objectives of improving ground support and reducing mining costs. This report deals with the work conducted at Placer Dome Inc.’s Dome Mine to develop a high density backfill system, taking advantage of the unique properties of this fill material, to address a backlog of large open stopes to sustain stable minewide ground conditions for future generations of Dome miners.IntroductionDome Mine began its existence in 1909 with the discovery of visible gold on a dome shaped outcrop located west of Porcupine Lake in northern Ontario. The orebody beneath this outcrop has supported one of Canada’s premier gold mining operations for 80 years. Production during this time of over 46 000 000 tons of ore has resulted in the recovery of II 500 000 ounces of gold and 2 000 000 ounces of silver. Mining continues today at a production rate of 3500 tons per day, with ore coming from both underground and open pit operations.During the life of the mine, different underground mining methods have been used to extract the ore from a complex deposit consisting of single and multiple vein structures.Cut-and-fill mining was introduced in the 1930s using sand fill and later hydraulic fill for support and to provide a working platform. A total of 1 800 000 tons of sand fill and 7 300 000 tons of hydraulic fill have been placed underground in cut-and-fill stopes. Until the late 1960sshrinkage mining was used extensively, particularly in narrow, steeply dipping zones. Bulk mining with small diameter longholes was introduced about this time, to take advantage of low production costs. Longhole blasting has often been used to recover low grade ore from the walls or sills of old shrink stopes, resulting in large open stopes. Backfilling of these open holes has been restricted to smaller stopes and associated with local ground conditions.In the late 1970s it was recognized that the number of large open holes which were being generated presented serious regional and minewide stability problems for future operations. With higher gold prices, economic ore reserves were being tied up in areas adjacent to multi-level open stope complexes. To stabilize these stopes and allow access, backfilling would be required."

Jan 1, 1990