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By J. Dupre, A. Gontcharov, H. Pepin

Produced by the conventional TIG welding CMSX-4 welds had been studied. It was demostrated that microstructure of welds depended on filler materials, welding parameters and joint design. Epitaxial solidification of CMSX-4 clad deposits produced a directionally solidified structure while welding with the similar filler material. Defects free clad welds were obtained by TIG welding without preheating using similar and dissimilar filler materials.

Jan 1, 2006

By David C. Cook

The milling complex, situated just east of the Cassiar townsite, receives raw ore from the tramline and processes it into 105,000 tons per year of milled asbestos fibre. The ore is passed through a concentrator, where a barren rock fraction is removed. The concentrated ore, representing 70% of the feed, is dried, stored and then milled into nine separate fibre classifications. The finished product is packaged into 100-lb bags and loaded into trucks in one-ton units. New air-handling facilities were added in 1977to provide additional air for environmental control.

Jan 1, 1978

By D. J. Parker, G. B. Tupper, I. Govender

Positron-Emission-Particle-Tracking (PEPT) has enabled the non-invasive observation of charge and slurry transport in model mills under operational conditions. We use high quality PEPT data to infer that the charge motion can be effectively described by a non-Newtonian granular fluid. An improved theory for slurry transport, including inertial effects, is presented.

Jan 1, 2012

By Y. Hou, E. Arinaitwe, L. Tong

A series of dense medium separation (DMS) tests were performed on four low-grade copper ores from Mount Polley mine in order to determine their amenability to pre-concentration. The tested ores contained disseminated sulphides, mostly chalcopyrite with low copper grades (0.15% - 0.2%) and relatively high iron grades (4.76% - 5.63%). The samples were screened into different size fractions ranging from 9.5 mm to 50.8 mm and DMS tests were performed on each size fraction at various separation densities. The pre-concentration efficiency at different size fractions and separation densities was evaluated in terms of metal upgrading and distribution. Mineralogical tests were also performed on selected DMS sink and float samples in order to understand the influence of mineralogy on the pre-concentration efficiency. The results showed that significant copper upgrading was achieved for intermediate size fractions only at the highest separation density tested. The copper recoveries generally increased with particle size at all separation densities. However, it was impossible to upgrade the copper content in the ores and achieve acceptable recoveries and mass rejections at the same time. Copper recoveries and grades showed a strong correlation with iron recoveries and grades indicating that it is possible to pre-concentrate copper by recovering magnetite and other iron-containing minerals in the ore. Overall, the results suggest that the optimum separation density and pre-concentration efficiency is a function of particle size, and that the ore mineralization properties limit the performance of DMS as a pre-concentration technology for such low-grade disseminated ores.

Jan 1, 2014

By M. R. MacIver, M. P. Pawlik

"An image analysis method based on chord length distributions is applied to the batch settling of polyacrylamide flocculated kaolin suspensions. Two features of the interaggregate void space, the void chord length distribution mean and the white-to-black distribution ratio are extracted from an image series obtained over the two hour settling experiments. This approach produces three signal values, from two different probability distributions that can be measured as an indication of underlying sediment bed density and aggregation state. Further work is required on the physical interpretation of the signal, the image acquisition conditions, and the parameter selection methods. It is suggested that this chord length based feature extraction technique may be a useful signal to monitor during batch settling or thickening.INTRODUCTIONFew in situ techniques are available that can be used to directly measure aggregate properties within sediment beds in thickeners or secondary settlers. Typical process variables monitored include rake torque and height, bed level and pressure, feed rate and density, underflow rate and density, settling rate, and overflow turbidity; yet these process variables are only weakly related to process dynamics (Concha et al. 2014). Additional process monitoring signals, based on the direct measurement of aggregate properties could improve solid-liquid separation control and allow the extraction of more detailed information from batch settling experiments.Several optical methods exist for measurement of moving suspensions of aggregated solids in the dilute concentration regime, such as focused beam reflectance measurement (Peng and Williams 1994), and the turbidity fluctuation method (Gregory 1985). In the more concentrated region of a thickener, acoustic backscatter penetration and attenuation measured with an acoustic probe and changes in the underlying solid concentration in the highly concentrated, near-bed region of a thickener as a function of height and time (Hunter et al. 2012). While machine vision for froth monitoring has been thoroughly studied with at least five commercialized technologies (Aldrich et al. 2010), its’ application to the study of thickening has been limited."

Jan 1, 2016

By M. Pötsch, A. Kluckner, P. Söllner, W. Schubert

"The in situ block size is a key parameter in the geomechanical characterization of rock masses. It describes the fracturing of the rock mass and thus is a measure for the degradation of the rock mass strength. Several classification systems use the in situ block size. For instance, the Geological Strength Index (GSI) requires the “blockiness” and joint surface condition factor as key input parameters. The “blockiness” has recently been related to the in situ block volume (Cai et al., 2004). Due to the limited information about the internals of a rock mass, it is not possible to determine the in situ block size directly. Currently, the in situ block size is determined by calculations using oversimplified models, vague estimations or, due to the lack of relevant information, it is neglected. As remote measurement systems have become available for rock mass characterization, a more comprehensive record of discontinuities can take place. Measurements can be performed on exposed rock outcrops and in particular on tunnel faces and walls, delivering the location, orientation, spacing and persistence of discontinuities at an arbitrary number and locations. An estimation of the in situ block size at the same level of sophistication is still not available. This paper aims at examining the relationship between visible and measureable information at the rock surface, and the in situ block size. Three-dimensional block model simulations were performed using the block model engine of the distinct element code 3DEC. Initial investigations focussed on the minimally required observation area in order to obtain reliable block size distributions. Based on a representative volume element, a reference distribution of the block area at the observation area for a specific discontinuity system was determined. Subsequently, the size of the observation area was decreased stepwise and each new distribution was compared to the reference distribution. For all analyzed systems, it turned out that the mean block area must be smaller than 1% of the observation area to achieve a reliable block size distribution. Further simulations focussed on discontinuity systems with three non-persistent sets. The results were compared to the formula proposed by Cai et al. (2004). A transformation factor T was introduced which replaces the persistence terms in Cai et al.’s proposed formula. The factor describes the correlation between block volumes generated by persistent and corresponding non-persistent discontinuity sets. The simulations included the variation of the discontinuity set spacing, persistence, and orientation. The mean and additionally the 25%-, 50%- and 75%-quantiles of the block size distribution were analyzed. Examining all values for the transformation factor the distribution can be described by a power function with a negative exponent. The function depends on the persistence only. Finally, the results of random simulations were compared to the analytical formula using the transformation factor. The predicted mean and selected quantiles show a good agreement with the simulation results. It gives a comprehensive picture about the block size distribution in discontinuity systems with three non-persistent sets."

Jan 1, 2015

By W. Petruk

A study was undertaken to determine whether interrelations between mineral grains affect ore breakage during grinding, and to establish a correlation between ore breakage and mineral liberation. A base metal ore from the Brunswick No. 12 deposit in New Brunswick was ground for different periods of time in a laboratory ball mill, and both the unbroken ore and the ground products were analysed by image analysis. The results show that the mode of breakage is strongly influenced by the behaviour of pyrite. Similar size distributions were obtained for material from the 15 minute grind in a laboratory ball mill, for the grinding circuit discharge from a commercial mill, and for pyrite grains in the unbroken ore. This similarity indicates that a 15 minute grind breaks poorly bonded pyrite grains along grain boundaries, and represents the limit of easy breakage for the ore. Such a grind liberates both large separate grains of ore minerals and poorly bonded mineral grains that occur in interstices among pyrite. On the other hand the 15 minute grind does not separate moderately bonded mineral grains nor release moderately bonded interstitial minerals from pyrite; a 45 minute grind in a laboratory ball mill is required. It is assumed that, for Brunswick No. 12 ore, a 45 minute grind in a laboratory ball mill is equivalent to regrinding in a commercial mill. Grinding beyond 45 minutes in a laboratory ball mill breaks the ore by fracturing pyrite across grain boundaries and by chipping grain edges. Such intense grinding does not markedly increase sphalerite liberation from Brunswick No. 12 ore, because most of the sphalerite that can be released was liberated at the 45 minute grind. In contrast the intense grinding increases galena liberation because a significant proportion of the galena occurs as minute inclusions in pyrite. These findings show that ore breakage and coincident liberation depend upon size distributions, intergrowths, and mode of occurrence of the minerals in an ore.

Jan 1, 1988

Presentation Overview ?WRDC Purpose and Activities ?Women in Trades, Technology and Operations (TTO) Occupations ?Factors in Successful Recruitment / Retention of women (VBNC) ?Recruitment and Retention Strategies ?Conclusion Women in Resource Development Committee (WRDC) ?Incorporated in 1999 as a Not for Profit Organization ?Based in Newfoundland and Labrador ?Works to Increase the Participation of Women in Natural Resource Industries ?Research (Using Gender-Based Analysis) ?Career Exploration Programs for Women and Girls ?Outreach and Advocacy ?Policy Development ?Public Awareness and Education ?Gender Sensitivity Training ?WRDC Educational Resource Centre

May 1, 2006

By BARRY BANNATYNE

Non-swelling bentonite has been quarried in Manitoba by Pembina Mountain Clays Limited since 1941. It occurs in several thin layers near the base of the Pembina Member of the Upper Cretaceous Vermilion River Formation, and is quarried from the narrow outcrop belt along the slope of the Manitoba Escarpment. It is marketed both as natural and activated bentonite for a variety of specialized uses. Percolation of acidic water through bentonite has produced a naturally activated bentonite with good absorbent properties; these properties are enhanced by treatment with sulphuric acid to produce an activated bentonitefor decolourizing petroleum and vegetable oil.

Jan 1, 1984

By K. Sinding, R. Poulin

"Recent land-use decisions in British Colwnbia, and the publication of a report on compensation for expropriations of resource interests, have highlighted the nature of land use policies. Landuse decisions, such as the creation of large new parks, raise three principal issues which have implications for how land-use policy is conducted and how it impacts on the mining industry. The first is the identity of the parties advocating different land-use policies and their motives for doing so, the second is the changing nature of benefits derived from land, and the third is the change of property-rights regime which is devised to accommodate the (changing) benefits from using land and natural resources, as well as the interests of the different parties involved.Involved Parties and BenefitsThe process of establishing or modifying property rights depends on the interest groups involved. Three distinct categories, each with distinct incentives which can influence the process, must be distinguished: private claimants, politicians and bureaucrats (Libecap, 1989).The first groups claim rents and management powers through asset ownership. They may be incumbent owners seeking enforcement of the status quo, new claimants seeking redistribution of assets, or third parties who depend on the distribution of assets (e.g. lenders, labour suppliers and contractors). Some infonnal property arrangements can be negotiated within the group whereas others requires action in the political arena through lobbying politicians for (re)allocation of property rights and influencing bureaucrats for favourable administrative decisions. The second category is politicians, who direct the powers of the state to change or enforce property rights. Both incwnbents and office-seekers fall in this category and their actions and opinions are shaped by their constituencies and financial backers. However, not all causes can be championed and trade-offs have to be made, resulting in decisions that maximize political benefits. The third category of parties in the process is the bureaucrats. The power to manage has been delegated by politicians but bureaucrats also have opportunities and incentives to further their own interests. These can include maintaining or expanding jurisdictional turf or increasing operating budgets (Libecap, 1989)"

Jan 1, 1994

By James F. Archibald

Testing has been accomplished to substantiate recent laboratory trials which have demonstrated that thin liner membranes, applied to rock core samples, can significantly enhance the structural performance of such rock materials. A range of Canadian polymer liner materials (MineguardTM, RockguardTM and RockWebTM) have been tested side-by-side to evaluate strength and other physical property improvements generated for two highly homogeneous, though differently sourced, granodioritic rock materials. Tests were conducted on physically similar core materials, utilizing 104 to 113 samples of each respective rock type. For both rock sample populations, cores were coated using linings at thicknesses varying between 1 and 7.3 mm, typical of the application range currently used underground by mines contemplating use of such membrane agents. Results of rock failure tests, following application of passive lining covers upon the very large sample populations of each rock type, have indicated that noticeable strength improvement and enhancement of post-yield failure characteristics can be developed by the entire range of spray-on liner materials evaluated. It is shown that all of the tested liner agent materials currently available can and do act to positively reinforce rock support capabilities of modeled core pillars. Where liner materials can be effectively placed underground, it is anticipated that they may provide similar benefit and be successfully used in partial replacement for either screen or shotcrete to provide advantageous area support for rock.

May 1, 2001

By Roy EI. Durr, Glen R. Davidge

"This paper presents the results of structural analyses and full-scale destructive tests conducted on liner plate culverts. The purpose of this work was to establish a design method and evaluate the suitability of using these structures in potential roof-fall areas for a rehabilitation application in lower stress and relaxed mining environments. Field evaluation of the design is currently in progress.Theoretical ultimate resistance functions were established for two different culvert shapes and were found to be representative of their experimental behaviour. The ultimate resistance function was used to determine their plastic behaviour to a rapidly increasing deflection condition, to determine the energy absorption capacity of these structures, and to predict their response to impact loading.IntroductionThe Kidd Creek mine of Falconbridge Limited is located justnorth of Timmins, Ontario. The area under rehabilitation for which this program was developed is the 2600 level of the No. I mine. The problem of effectively securing selected drifts at the 2600 level in NO.1 mine, for access to a high-grade ore block, is key to the economics of the operation. Diamond drill test holes had indicated a loosened rock mass above the 2600 level of about 7.5 m thick in response to the extensive mining operation below this level. This level forms the arbitrary boundary between the No. I and No. 2 mines, and has extensive volumes of cemented rock fill below it and largely untouched ore above it to the 2000 level in the North orebody. The walls at that level were showing relaxed ground conditions typical of de-stress: sub-horizontal joints opening up, and peeling.Due to the ground conditions, the consequent safety risks, the high grade of the ore, the potential production delays, and the likelihood of several phases of rehabilitation, regularly used drift rehabilitation employing rock bolts, cable bolting, or shotcrete was not practical. Two options were deemed possible alternatives to suit these conditions, steel sets with blocking and lagging, and liner plate culverts with backfill. Culverts were chosen."

Jan 1, 1995

By David L. Sprott

This paper presents an evaluation of underground-to-surface haulage options for a relatively large deposit. Specifically, it presents a recommended haulage option to provide the greatest value to the Project. Options considered included conventional truck, trolley-truck, conveying and shaft hoisting. The work was done at the level of a preliminary assessment as input to an internal pre-feasibility study. The Base Case for the analysis in this study was a Long Hole Open Stoping option (LHOS) using conventional truck haulage. Two scenarios were considered for the evaluation and included: 1. The current resource to ~700 m depth. 2. An expanded resource to ~825 m depth. The haulage options evaluated included three trucking options, three conveyor options and two shaft options. The paper presents the results from evaluating these options within the two mining scenarios using a Discounted Project Cost (DPC) comparison. Recommendations are made for the options that will provide the greatest overall value to the project.

May 1, 2008

By K. Wood, L. Duval

"The paper discusses the approach used to add a new, separate 5000 t/d copper-zinc treatment circuit to an existing, 1650 t/d copper circuit, essentially within the existing mill building. Temporary installation of new equipment allowed renovation and expansion within existing operating areas. Production in the original circuit was maintained at rated capacity throuqh0ut the construction period through close co-ordination between operating and construction groups. Downtime for circuit and service tie-ins was minimal. Both circuits are described briefly.For presentation at Canadian Mineral Processors Conference Ottawa, January, 1987.INTRODUCTIONLes Mines Selbaie is located in the Abitibi region of northwestern Quebec, in what has recently become better known as the Casa-Berardi-Joutel area. Les Mines Selbaie is operated as a joint venture project managed by Selca Division of BP Canada Inc. and owned 55% by BP Canada, 35% by Esso Minerals Canada and 10% by Trans Canada Pipelines."

Jan 1, 1987

By L. Yuan, J. H. Rowland, R. A. Thomas, D. Bahrami, G. P. Cole

"The past several decades have seen a steady increase in the use of atmospheric monitoring systems (AMS) in underground mines as sensor technology has advanced and costs for this technology have decreased. The AMS is a reliable tool for early mine fire warning by detecting gaseous products of combustion in underground mines. During a mine fire emergency, mine decision makers rely heavily on the prompt and accurate knowledge of the ventilation and fire situation in the mine, such as fire location, fire size, and the spread of smoke to make effective and efficient decisions on firefighting strategies and miner evacuation. Meanwhile, a prediction of the potential for fire development at a later time, such as whether the currently designated mine escapeways will be contaminated by smoke and toxic gases with the progress of the fire, is critical for effective decision-making to save lives that are in danger. The AMS monitoring data, including carbon monoxide (CO) concentration, airflow rate, smoke, etc., can provide information as to whether the smoke has reached the locations where AMS sensors are installed and if a mine-wide smoke spread has occurred. The National Institute for Occupational Safety and Health (NIOSH) has undertaken a task to integrate real-time AMS monitoring data with the mine fire simulation program, MFIRE, to simulate and predict the spread of smoke and toxic gas in a ventilation network based on the real-time AMS data. This paper reports the developed real-time method for characterizing the size and location of an underground mine fire and for predicting the spread of contaminants throughout the mine ventilation network using sensor data from the AMS.INTRODUCTIONNIOSH conducts research to develop workplace solutions to improve detection of and reduce the risk of hazardous conditions in underground mines. The advancement of senor technology and the increasing demand for real-time mine parameters monitoring have led to extended applications of atmospheric monitoring systems (AMS) in underground mines worldwide. In the United States, AMS is primarily used for early mine fire warning by detecting carbon monoxide (CO) in fire hazard areas, such as belt entries. Mine fires can grow rapidly, and time is the critical element. Prompt detection, timely and accurate warnings to those miners potentially affected, and a proficient response by underground miners can have a tremendous impact on the social and economic consequence of a small underground mine fire (Conti et al., 2005). The early detection of a mine fire could gain time for the first responders to put out the fire before it develops into a disaster. An AMS system with CO sensors has especially played an important role in the early detection of mine fires. The continuous monitoring of an underground mine atmosphere with an AMS could generate a large amount of data in a mine fire event. However, the current application of AMS is mainly limited to sending out an alarm when monitored CO concentration exceeds a certain level. An opportunity arises as to whether these data can be further used in fire emergency response. In order to make effective decisions on firefighting strategies, mine workers’ seeking refuges, evacuation and escape, and the timing on when to send rescuers, decision makers need accurate and timely knowledge of the ventilation and fire situation in the mine. Information about the fire intensity, where in the mine the smoke and toxic gases have spread, and whether designated mine escapeways have been compromised by smoke and toxic gases from the fire would greatly increase the effectiveness of these decisions. However, the monitored AMS data only provides atmospheric conditions in the vicinity of sensor locations. What is concluded from the monitored AMS data highly depends on the decision makers’ capability and experience. Predictive insight into fire growth and smoke transport would greatly help decision makers during a fire emergency."

Jan 1, 2019

By J. Fixter, P. Prangnell, Z. Pinter, E. Eimer, B. Chehab

"High deposition rate Wire and Arc Additive Manufacture (WAAM) can provide benefits to the aerospace industry, including a reduction in lead time, reduced material waste and, through higher solidification rates, refinement of the as-built microstructure relative to a cast material. However, candidate 2xxx series high strength alloys for this process normally require a solution treatment, which is problematic for large near-net-shape components, and age hardening to achieve maximum mechanical properties. With each layer being subject to multiple thermal cycles, exploiting the thermal conditions in the WAAM process to avoid post-build solution treatment is therefore of interest. A solutionisation model has been developed for the WAAM process, based on diffusion controlled dissolution using DICTRA, which was validated through thermal simulations combined with 2D and 3D image analysis. The model has subsequently been used to simulate the solutionisation behavior during a typical WAAM thermal cycle and to explore what could theoretically be achieved by, for example, refining the starting microstructure.INTRODUCTION There is currently great interest in exploiting additive manufacturing (AM) in the aerospace sector due to several benefits it can potentially provide; including reduced material waste, shorter product lead times and greater design freedom (Herzog, Seyda, Wycisk, & Emmelmann, 2016). However, with aluminium alloys the material properties obtained are generally inferior to those of conventional high-strength wrought products; therefore more research is required to explore the potential for exploiting the unique process conditions in AM to improve the as-deposited microstructure. A range of AM techniques are now available (Debroy et al., 2018), which differ in terms of the feedstock type and power source and it is necessary to match the appropriate technology to a particular application. This generally requires a compromise between the build rate and shape resolution. Wire and plasma-arc additive manufacturing involves using an electric arc to melt wire onto a substrate, and fabricates a part by building up overlapping layers of deposited weld beads (Addison et al., 2015; Williams et al., 2015). The benefits of this process over other AM methods are the much higher deposition rates (e.g. kg’s/hour) achievable and lower capital equipment costs relative to powder bed techniques, which makes it suitable for large scale applications. However, limitations include a lower part complexity, lower solidification rates and a greater need for post-process machining (Frazier, 2014)."

Jan 1, 2018

"With the plethora of cable bolts on the market, geotechnical engineers can be baffled by the differences in performance claims from the manufacturers but perhaps more importantly they are sometimes at a loss in making an optimal selection matching behaviour with a particular site condition. To this end a new testing methodology has been developed that can cater for the varying types of cable bolt behaviours. The methodology is based on the laboratory short encapsulation pull test (LSEPT) as recommended in the British Standard and overcomes several deficiencies such as cable rotation. Of most significance however, is its inability to measure the post-peak residual performance of high load transfer capacity cables and consequently, there is an inference that these cables may be susceptible to sudden anchorage failure with relatively little yield. This paper details the results of anchorage performance tests of a range of cable bolts and the differences in performance with rock strength and drill hole diameter.INTRODUCTIONA research project was undertaken to develop a new laboratory-scale test apparatus to study the axial performance of fully grouted cable bolts that are used in the Australian underground coal mining industry. Work by Thomas (2012) and others in recent years found there were a number of deficiencies in the testing methodologies making it difficult to determine and compare the performance of the dozen or more different types of cable bolts on the market. This has meant that geotechnical practioners have been hamstrung in optimizing the design of ground support systems in underground environments that are increasingly more arduous.A cable bolt is a flexible tendon consisting of a quantity of wound wires that are grouted in boreholes at defined distances between holes in order to provide ground reinforcement of excavations (Hutchinson & Diederichs, 1996). They were initially introduced into the underground hard rock mining industry in the 1960s (Thorne & Muller, 1964) and since the early 1970s have been brought to coal mining operations."

Jan 1, 2015

By H. Weissenbaeck, B. Nowak, M. Oesterreicher, R. Stastny

The producers of certain metals like nickel and cobalt increasingly face a shortage of easy-to-mine and easy-to-process ore bodies. Their focus is shifting towards alternative raw materials which in turn demand new, different extraction techniques. One potential route for processing a ferrous ore with a non-ferrous target metal is atmospheric leaching with hydrochloric acid followed by purification of the pregnant leach solution (PLS). For the separation of iron from the PLS, and, in turn, the extraction of the non-ferrous compounds, the following flow sheet is proposed. Pre-concentration of the PLS, oxidation of ferrous (if present) to ferric chloride, hydrolysis of ferric chloride leading to the precipitation of hematite and the evaporation of hydrochloric acid, followed by crystallization of non-hydrolysable metal chlorides by means of sparging hydrogen chloride into the solution. Hydrogen chloride required in the latter step is produced internally by super-azeotropic distillation of regenerated hydrochloric acid. The liquid filtrate from the crystallization step is recycled to hydrolysis. Depending on the specific composition of the PLS, the hematite produced contains only traces of other impurities, whereas the crystallized mix of non-hydrolysable metal chlorides – containing also the target metal in enriched form – contains ferric chloride only in an amount referring to the filter cake moisture. These crystals can then undergo further hydrometallurgical separation and extraction processes. As an example, this flow sheet is proposed for treating nickel laterite ores. Experiments related to the demonstration of crucial assumptions in the flow sheet are presented. Based on those experiments a mass and energy balance of the flow sheet was calculated and is presented here together with a table of the major consumables in order to provide a basis for an operating cost estimate and other process economics.

Jan 1, 2016

AGENDA ? Company Overview ? Industry Direction ? Technology to support maintenance ? data access, connectivity, process historian, downtime & production reporting. ? Case Studies Company Overview Corporate Offices Client Base ?16 consecutive years of growth & profitability ?#39 of Top 50 Control Companies (Worldwide) ?470 employees ?TSX: MTK Industry Direction Improved visibility into the business so they can: ? Reduce cost through better understanding of where costs are being incurred and making timely decisions. ? Optimize operations while leveraging existing assets. ? Have a single version of the ?truth? ? Deliver reliably to stakeholders on the demand for increased accountability (safety, environmental, regulatory performance etc?). ? Respond quicker to market conditions in order to out perform the competition ? Best in Class approach. Web is becoming the standard user interface.

Apr 1, 2005

By Kristie D. Tarr

Ideally, in situ monitoring would supply the input data for numerical modeling of backfill material property requirements. However, clue to production requirements and costs of conducting field tests, input data are often based on small-scale laboratory tests. The size of test samples is known to play an important role in the laboratory assessment of the behaviour of geotechnical materials, including backfill. There are observed differences between the mechanical properties of laboratory-scale samples and those of in situ materials, and these are generally attributed to the differences in scale. Various scaling factors have been proposed for converting laboratory observations to anticipated in situ conditions for soil and rock materials. With regard to mine backfill, very limited studies exist which have involved the effects of sample size on material properties. The literature indicates that reported backfill strength data are based on a variety of test sample sizes and in some cases, specimen geometries. Carefully determined laboratory scale effects could play an important role in estimating the potential backfill behaviour in the field, especially when developing new backfill systems. Laboratory studies were conducted with sample diameters ranging from 50 to 300 mm. Scale factors relating specimen size to strength were developed wherever possible, and are presented in this paper

May 1, 2008