Search Documents

Shafts are the most important workings in the underground mines. Their technical state to a large extent determines the safety and efficiency of mining operations. However, in many cases periodically performed inspections show unsatisfactory technical state of the shaft lining (local defects, cracks, cavities, losses of the outer surface of the lining or, in case of the bricks, losses of the masonry). The most common cause of these types of damage is progressive deterioration of the lining material, impact of aggressive mine waters, impact of mining operations, deformation of the lining due to the rock mass saturation, seismic activity or periodic freezing of the lining in the upper part of a shaft. The paper presents legal requirements associated with the use of mine shafts in Polish coal mines as well as the ways and range of their control. Furthermore, examples of typical damage to shaft lining and ways to repair it, such as additional bolting, filling cavities or a wire mesh and shotcrete installation, are shown. In the final part, the paper presents a short example of a shaft, in which damage to the lining was one of the main causes of the shaft's failure. Due to the damage to the shaft lining, at the depth of approx. 65.0 m, the shaft was spontaneously filled with overburdened soil material. It resulted in a large crater to come to the surface, which, in turn, caused damage to the buildings and facilities present in the impact zone. On the surface the diameter of the crater was approx. 60.0 m, its depth approx. 11 m and the estimated volume was of about 30,000 m³. The disaster also caused disturbance in the ventilation of two neighbouring mines and the increase in methane hazard. Given the size of the crater, the measures to eliminate consequences of the catastrophe were undertaken in several stages.

Aug 1, 2013

By Stavros A. Argyropoulos, Radhakrishna Valiveti, Bernard Closset

"The use of microprocessors in metallurgy is currently increasing at a very fast rate. A large number of companies are offering systems ""off the shelf"" which are aimed at the data acquisition and process control market. There are two main drawbacks to these systems: first, they are usually quite expensive, and second, they are not completely compatible with the target metallurgical application. An alternative is to develop a microcomputer-based system "" in lab "".A dedicated microcomputer system has proved to be very useful in many metallurgical research applications(1,2)). However, in this system the analog input signals had to be transferred over long distances , and significant noise was introduced despite the use of shielded cables. In order to overcome this problem a network of low pass-filter s was designed and built. The usage of the abovementioned system brought the need to digitize the analog signals in-situ and transfer the digital signals, which are much less susceptible to noise over very long distances. This distinctly different design philosophy has become a reality with the evolution of microprocessor technology over the last few years. This design philosophy is utilized in this development."

Jan 1, 1984

By John E. Udd

The stability of a rock mass is influenced by the presence of discontinuities. In assessing stability, it is required that one should know the frictional and cohesive properties of these contained weaknesses. In the study performed by the authors, a number of samples of diamond drill core containing open discontinuities were tested in shear. The results obtained were compared with values which resulted from back analyses of instabilities in the field.

Jan 1, 1979

By Norman Lecuyer, Jacque Nantel

"The Chadbourne Project, located within the limits of the town of Noranda, Quebec, will make use of backfill materials to fill the voids left by the mining of stopes and pillars. A series of tests were conducted on different mixtures of slag and pyrrhotite tailings materials to evaluate their properties. The tests are described and some pertinent results are given in the paper.IntroductionThe Chadbourne Project is located in the centre of the Town of Noranda, Quebec, with houses as close as 120 m from the blasting operations. The ore is mined using the vertical crater retreat method. The voids left by mining activities will be filled. A program of pillar recovery will follow.Considering the proximity of houses and the need to recover pillars, the backfill program must be carefully laid out. No subsidence can be tolerated on surface.With these objectives in mind, a test program was undertaken by Nantar Engineering Limited and Queen's University to evaluate the possible ba ckfilling alternatives available to Chadbourne. One of the possibilities retained was the use of a backfill composed of broken slag material from the Horne Smelter and pyrrhotite tailings deposited on the Horne's pond a number of years previously.The back fill used at the Horne Mine until the mine closed in 1975 was composed of a mixture of 97% granulated slag and 3% pyrrhotite tailings. The tests leading to its use underground at the Horne Mine were described by Patton in 1952. The structural properties of the Horne backfill were ""intuitively"" known; it was agreed by all at the Horne Mine that the backfill was behaving remarkably well. Some were labeling it ""the best backfilling material in the world"". Its strength was said to be that of a weak concrete. All of the preceding indicate that the Horne backfill had never had its structural and other properties determined in the laboratory."

Jan 1, 1983

By W. Baranek

The paper describes activities undertaken for intensification of copper cathodes production in electro-refining plants of the Polish copper smelters: 'Legnica', `Glogów I' and `Glogów II'. In the 'Legnica' smelter, Outokumpu?Wenmec machine was used for preparation of copper anodes. Intensive studies were conducted in order to optimise copper electro-refining conditions. As the result of them, spacing between the electrodes was reduced to 99 mm, which enabled placing forty-one cathodes in each tank and increasing amperage from 10.8 to 13.0 kA. This modification resulted in the increase of electro-refining capacity to 103,000 tons/y. Intensification of the copper production at `Glogów II' by 18,000 tons/y became possible after development of new electro-refining procedures, including application of a regime of changes in electrolyte level during the cathode cycle, implementation of the changes in location of starting sheets relative to anodes, and in dimensions of the sheets, and modification in the shape of the anodes. Similar works have been performed at `Glogów I', which were concentrated mainly on defining of a new method of anodes preparation, modification of their geometry, determination of optimum current density, composition of a set of inhibitors and of a method of their introducing. The implemented solutions resulted in the increase in electro-refining capacity at `Glogów I' from 207,000 to 240,000 tons/y.

Jan 1, 2007

By Dallas W. Davis

"Since May 1980, New Brunswick has called separate tenders for the right to explore and develop several potash prospects, as well as areas underlain by Alberta oil shale. These tender calls had in common the provision for a basic ad-valorem royalty, combined with sharing of cash flow after exceeding a 15-20% discontinued cash flow rate-of-return threshold. In the case of potash, the bidding variable was a share of cash flow, but for oil shale it was exploration expenditures committed, with the cash flow sharing to be negotiated at the time of application for a production lease. The Millstream potash occurrence, previously discovered by government drilling, received five bids (21.1% highest), the Dorchester ""grassroots area"" with four surmised drill targets apparently received no bids, and in the case of oil shale there were only two bids on the one block previously subjected to the most exploration.It is concluded that New Brunswick will not be successful in awarding the potash or oil shale rights in return for a comparable level of basic royalty and cash flow share as in the case of Millstream, unless it spends money in discovering prospects or sharing the exploration risk with companies. The approach is likely to work for oil shales only if current exploration proves the existence of much high-quality material or a definite trend of real increases in the price of oil is again established. Undoubtedly, it continues to be desirable to assure an on-going stable investment climate through award of potash and oil shale rights under terms which provide for a return that the public and future governments will consider fair. This could mean that some form or risk sharing with companies would be advisable."

Jan 1, 1983

By J. Lee, K. B. Min, J. Rutqvist

Shear slip of fractures in fractured rock masses is a critical issue for many geological engineering applications, such as the design of underground nuclear waste repositories, enhanced geothermal systems (EGS), and geosequestration of CO2. This paper presents new development of the TOUGH-UDEC simulator for analysis of coupled thermal-hydraulic-mechanical (THM) processes in fractured porous media. As an alternative to developing a single coupled THM code in discontinuum, two existing wellestablished codes, namely TOUGH2 and UDEC, are coupled to cover coupled THM analysis of multiphase fluid flow, heat transfer, and deformation in fractured porous media. TOUGH2 is widely used for modeling heat transfer and multiphase, multicomponent fluid flow, and UDEC is a well-known discrete element code for rock mechanics, which have been verified and used by many groups all over the world. Although a sequential coupling of two codes is less efficient than having a single code in principal, a big advantage with coupling of TOUGH2 and UDEC is that both codes are well tested and widely applied in their respective fields. When linking two codes, the coupled equations cannot be solved simultaneously; they should be solved sequentially, with coupling parameters passed to each equation at specific intervals. After solving thermal-hydraulic equations through the TOUGH2 model, pressure (P) and temperature (T) information is delivered to UDEC model. Pressure information is directly stored at the center of each UDEC zone and domain, however, temperature information is interpolated from zone-centers to the corners nodes. After solving the mechanical equation through the UDEC model—considering new pressure and temperature—calculated fracture apertures are converted to equivalent permeability and porosity for TOUGH2 flow analysis. The solution was calculated by iteratively following an explicit sequence for numerical efficiency. Verification examples are presented to demonstrate the capabilities of the coupled TOUGH-UDEC simulator.

Jan 1, 2015

By Rufus L. Chaney

A new technology is available to the Ni mining and remediation community to “phytomine” Ni from mineralized or contaminated soils using rare plants which hyperaccumulate Ni to over 1% of shoot dry matter. Research has identified useful plant species, and even bred improved cultivars of Alyssum murale and Alyssum corsicum for commercial phytomining in temperate regions. All agronomic practices (fertilization, soil amendments, planting and harvest methods) needed for economic phytomining were identified to attain high yields and high Ni concentration in the biomass. In tropical regions, other species are available such as Phyllanthus which accumulate over 1% Ni in dry shoots. These species are perennial so they regrow after annual cutting to harvest biomass. Expiration of our patents on the technology opens the opportunity for other organizations which control Ni rich natural soils or contaminated soils requiring remediation to commercialize the technologies. Inexpensive methods to remediate/revitalize Ni contaminated phytotoxic soils using agronomic approaches have also been developed and demonstrated at Port Colborne, Ontario, but adoption is delayed until formal agreements with government are completed. These new simple remediation and profitable phytomining technologies can obtain Ni from soils which contain Ni well below levels considered economic for current mining technologies, and the plants biopurify the Ni so it is easy to recover Ni metal from plant ash by pyrometallurgical or hydrometallurgical technologies. Although increasing pH decreases the solubility of Ni in all soils, raising pH increases Ni accumulation by Alyssum species. Hence usual chemical extraction methods for phytoavailable soil metals such as the DTPA- or NH4-OAc-extraction cannot predict Ni accumulation by Alyssum species.

Jan 1, 2016

By F. H. Samuel, P. Burke, F. Mucciardi, J. Gruzleski, S. A. Musmar

A new thermal analysis technique has been developed and tested. It utilizes the enhancement in heat transfer characteristics associated with a recent advancement in heat pipe technology. Heat is extracted from a liquid sample of a melt taken in-situ within a vessel or furnace. The rate of heat extraction is such as to cause the sample to solidify. The technique was tested in both laboratory scale and industrial scale (Grenville Castings, Perth, Ontario). A 356 Al Alloy, subjected to various melt treatments was used to perform the tests. Classical thermal analysis was also performed simultaneously using a preheated graphite cup and at the same melt conditions. The comparison showed the potential of the new technique over classical thermal analysis. The major advantages of the new method are that it conducts the analysis inside the melt (i.e. a physical sample is not removed from the melt), it consumes less time and the cooling rate can be precisely controlled during the solidification process. Moreover, the resolution of the results is better than that of conventional techniques. Aluminium

Jan 1, 2006

By Rashid Bashir

Shaft sinking through solid rock, which contains little or no water, poses little difficulty. However, when loose, water-bearing strata have to be contended with, water control measures, and pumping facilities are needed. Shaft sinking in Athabasca Basin requires sinking through water bearing sandstone which can be highly fractured. Intersection of local zones of extensive fracturing results in the potential for high water inflows with pressures up to 5 Mpa. Grouting is carried out ahead of each shaft sinking interval as water control strategy. In the grouting method, liquid cement is forced into the water-bearing earth under very high pressure. Shaft sinking performance which can be quantified in terms of rate of advance is highly dependent on the days spent at each interval grouting before sinking can advance to the next interval. This paper presents the shaft sinking experience in Athabasca basin and how some of this is translated into Geoscientific Investigations for Future Shafts. A comparison of Geoscientific data collected from future shafts at McArthur River and Millennium Mines is compared to historical data collected from pilot holes, where shafts have already been sunk. The paper concludes with the strategies for better integration of hydrogeological, geotechnical and geophysical data.

Aug 1, 2010

"These standards were developed by the CIM for use with the value or worth of a Mineral Property as opposed to “evaluation” where the key objective is an economic assessment or determination of the economic merit of a propertyP1 .0 BACKGROUNDPl.1 There are at present no comprehensive standards for valuation of Mineral Properties in the Canadian mining industry. The Mining Standards Task Force (MSTF) of the Toronto Stock Exchange and the Ontario Securities Commission in its Final Report (January 1999) specifically recommended that the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) form a committee of valuation practitioners to review and advise on approaches to valuation of Mineral Properties.Pl.2 On May 5, 1999 at the Calgary Annual General Meeting, CIM Council approved the formation of a Special Committee on Valuation of Mineral Properties (CIMV al) to be co-chaired by Keith Spence (Chairman of the CIM Mineral Economics Society) and Dr. William Roscoe (Roscoe Postle Associates Inc.).Pl.3 The mandate of CIMVal is to recommend Standards and Guidelines for Valuation of Mineral Properties to be used by the mining industry in general and to be adopted by Canadian securities regulators and Canadian stock exchanges.Pl.4 The members of CIMVal represent of a mix of professional disciplines and experience in the field of Mineral Property valuation:Keith N. Spence (Co-chair), Alliance Pacific Resources Inc., TorontoWilliam E. Roscoe (Co-chair), Roscoe Postle Associates Inc., TorontoMichael J. Bourassa (Secretary), Aird & Berlis LLP, TorontoChristopher R. Lattanzi, Micon International Limited, TorontoRoss D. Lawrence, Watts, Griffis and McOuat Limited, TorontoPaul E. Lunney, Noranda Inc., TorontoCraig A. Roberts, Pacific International Securities, VancouverDavid A. Scott, CIBC World Markets, TorontoIan S. Thompson, Derry, Michener, Booth & Wahl Consultants Ltd., VancouverWilloughby A. Trythall, retired Placer Dome executive and consultant, Vancouver"

Jan 1, 2003

By H. J. Glass, J. G. L. Bekkers

"In order to determine the feasibility of a hydraulic ore hoisting installation, the optimal operating conditions were calculated for applying such a system at the Detour Lake Mine of Placer Dome Ltd. Next, a financial analysis was conducted in order to estimate the cost per tonne for hydraulic hoisting of the ore. Subsequently, the cost per tonne was compared with the hoisting costs associated with a new borehole hoist. Installing a hydraulic ore hoist at Detour Lake Mine was found to be feasible with considerably lower costs per tonne of ore. The applied research method appears to be very functional and can be used to do similar research for other mining operations. IntroductionThe principle of hydraulic ore hoisting is well known, yet hardly accepted in hard rock mining. Application of the system would result in a smaller diameter shaft requirement and a flexible, easily expandable system. However, underground ore size reduction might be necessary and practical experience with the system is limited. Following recent innovations in the field of pumping hardware, e.g. new GeHo and Siemag Transplan equipment, hydraulic ore hoisting should be seriously considered for certain mining operations. As a case study, a design was made for the development of the newly found QK-Zone at Placer Dome Ltd.’s Detour Lake Mine. Hydraulic ore hoisting has been compared with conventional skip hoisting by establishing the optimal operating conditions and pumping equipment requirements for similar capacities at a selected mining operation. Generally accepted equations for slurry transport were used to predict the variation of pressure and power requirements as a function of hourly production and pipeline diameter. These data are used to select suitable equipment and estimate cost figures in order to make a financial assessment."

Jan 1, 1998

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 Walter Curlook

"With Inco recording record profits over the past year, most people have forgotten the painful years of the last recession/depression when Inco was losing up to a million dollars a day for a short period . While high nickel prices have contributed to the exceptional recent profits, the real achievements stem from the tremendous advances in productivity and cost improvements that make Inco one of the lowest cost nickel producers.Some of the major advances in productivity have occurred in the mines. The establishment of Mining Research Departments in both Thompson and Copper Cliff in 1979/80 provided the stimulus and the opportunity to dedicate personnel to specific research projects, on a full-time basis; and more particularly to concentrate on the efficiency of the total mine system. The Copper Cliff North Mine was brought back into production as a research mine dedicated to the development and testing of new mining methods and equipment. A shop facility known as the ""Murray Shop"" was set up as the centre of innovation for the development and construction of prototype equipment required for new bulk mining methods. While other expenditures were being curtailed , investment in mining research was being increased. An early success was an ""in the hole"" drill that could be broken down into small components to access even the remotest sectors of a mine to convert labour intensive undercut-and-fill mining to "" vertical crater retreat "" , VCR, bulk mining. A new mine manufacturing company-Continuous Mining Systems-was incorporated with the objective of building innovative mining equipment, with strong focus on automated continuous sytems. Continuous Mining Systems has now grown to a $25 million per year business. With these synergistic thrusts, the VCR bulk mining method was implemented in all of the Ontario Division mines, raising the percentage of ore mined by bulk mining techniques from 320/0 in 1981 to over 90% today. Coupled with re-designed job responsibilities, sup- ported by appropriate training, mine productivity more than doubled. It was discovered that VCR mining could be adapted to the narrower Thompson mine ores with identical improvements in productivity. Development of the Thompson Open Pit North had an additional favourable impact on production cost s in Thompson. The timing of the open pit development could not have been better. It permitted Inco to rapidly increase production at high productivity and low cost, in years of record demand and prices."

Jan 1, 1990

By G. Kachaniwsky, M. Bédard

"The Noranda Continuous Smelting Process at the Home smelter was commissioned in March 1973. The ability of the process to handle a wide variety of feed materials and a steady stream of technical innovations in recent decades has served to maintain the Home as an efficient and versatile custom smelter. This paper reviews recent technological development and capabilities in areas such as sampling and preparation of secondary and complex materials, as well as the smelting and related environmental control issues. Future trends and improvements are also addressed.IntroductionThe Noranda Home smelter commenced operations in 1927. It was originally designed to treat 910 tonnes per day of copper concentrates and ores coming from the new Home mine site. In the 19305, the company opened its doors to other mines in northwestern Quebec. Treatment of feed materials on a custom basis has, therefore, always been an important factor in the operation of the Home smelter. Throughout the years, the Home gradually increased its custom smelting capacity, while maintaining its production from the Home mine. By the early 1950s, 65% of the materials processed was from outside customers, and by 1974, this figure had increased to more than 85% . With the closure of the Home mine in 1976, the company extended its smelting operations beyond ore and concentrate, and began to treat more scrap metals and residues rich in copper and precious metal content.Corresponding with the ever-changing pattern of feed sources, the Home smelter has adopted technological improvements to meet new and challenging business conditions. The technology of the original smelter of 1927has been completely replaced over the years in the quest for improvement. One of these major changes occurred in 1973 with the start-up of the Noranda Process Reactor. This extremely efficient smelting system has been exploited to treat a wide variety of copper and precious metal (PM) containing custom materials. This paper reviews recent developments and improvements achieved at the Home smelter, in the receiving, sampling and treatments of copper and PM scrap and secondaries, with particular emphasis on the development of new technology and equipment in complex feed materials treatment."

Jan 1, 1991

By M. Carvalho

The primary motivation underlying the proposal of polygeneration systems for mine sites is to increase the efficient use of natural resources by combining different technologies and energy resources while satisfying energy service demands. For many mineral producers, particularly in Canada?s mining extremes of climate and depth, energy in support of mineral production can be the second largest cost centre after labour. A generic methodology is proposed for the design of energy supply systems in mine sites, based on a search for the minimum discounted cost of energy supplied for all feasible different plant configurations. These configurations can be represented within a connectivity matrix which corresponds to a network representation. A Mixed Integer Programming formulation is set out for the multiperiod synthesis and operational planning problem. This is characterized by i) binary variables for the selection of technologies, ii) integer variables for the determination of the number of units installed, and iii) by continuous variables for the representation of energy and economic flows. Through the integration of particular energy supply strategies matching specific mine circumstances (on-grid, remote, degree days, etc) and consideration of technologies that improve energy efficiency, hitherto not considered new technologies and demand management systems or new perspectives on optimal mine site energy supply can be investigated. Some of these investigations identify the economic conditions through which biomass energy feedstocks should be used, for direct heat production, for gasification and providing for Fischer-Tropsch syndiesel manufacture. As well as integrating demand from mobile diesel-fuelled plant into an optimization procedure that hitherto has only been considered for static energy production and consumption plant, this analysis shows how the techniques can be used to explore economic conditions of threshold prices for biomass (purpose-grown biomass and peat are considered herein) and trucked-in diesel. The methodology also allows for electricity and syngas storage and diesel and biomass bunkering. Within the paper the energy demands for a remote, open pit mining operation located in Northern Ontario are considered as a case study to illustrate the technique and investigations. As expected, for mines close to electricity, natural gas, and diesel distribution infrastructures, the optimal choice is to connect. When a constraint is applied specifying that connection is not possible, as would be for the case exemplified, the optimal choice includes some of the more exotic options for mine site energy supply.

Aug 1, 2013

By Y. Mitsuda, Y. Kayanuma, T. H. Okabe, M. Miyake

A new process to recover platinum group metals (PGMs) from automotive catalyst scrap using metal vapor was developed. To improve the efficiency of the acid dissolution process of PGMs, metal vapor of reactive elements such as magnesium or calcium were contacted with spent automotive catalyst. It was expected that metal vapor would react with metal selectively and form intermetallic compounds. The specimen of the spent catalyst was treated at 1173 K for 3 h, and it was then dissolved in aqua regia for 1 h to recover PGMs. After the reactive metal treatment, 88% of Pt, 81% of Pd, and 72% of Rh in the catalyst scrap was dissolved, while only 77% of Pt, 69% of Pd, and 38% of Rh was dissolved from untreated scraps.

Jan 1, 2004

By Fidelis T. Suorineni

HydraboltTM is a Swellex-type dowel support element developed and manufactured by New Concept Mining in South Africa. Like Swellex, the HydraboltTM is a folded tube which can be inserted into a larger diameter hole without pushing. It is then activated by injection of high pressure water which inflates the folded tube to intimate contact with the walls of the borehole at a set pressure, normally 25 MPa. Unlike Swellex however, the set water pressure at the end of the inflation is maintained throughout the life of the dowel. An integral non-return valve makes this possible. The HydraboltTM is being investigated as a possible stress change measuring cell. This paper presents the results of closed form solutions, numerical modeling and laboratory test to date. Preliminary results indicate that the HydraboltTM can be used as a stress change monitoring cell in addition to its conventional role as a rock mass reinforcing element. If successful, the HydraboltTM will supplement microseismic monitoring systems in rockburst-prone ground conditions where they will give quantitative stress change data for both mine design model calibrations and means for proactive safety measures.

Oct 1, 2010

By Ken Major, Anita Marks, Craig Sams

In 2007 Copper Mountain Mining determined that there were sufficient resources to consider reopening the Similco Mine near Princeton, BC. The mill facility that had been built by Newmont Mining in 1972 was closed in 1996 and all of the process equipment removed. The mill had been built on the west side of the Similkameen River to facilitate mining of the Ingerbelle Deposit. In 1980 construction was completed on a primary crusher and cable belt to deliver ore across the Similkameen River from the Copper Mountain deposit to the Ingerbelle mill. With the decision to restart mining of the Copper Mountain deposit, the decision was made to design and build a 35,000 tpd grinding and flotation mill near the mining operations. This paper discusses the application of historical operating data for the selection of the mills for the new grinding circuit and provides an overview of the grinding circuit design.

Jan 1, 2012

By Shantanu Patel, C. Derek Martin

"The objective of this work is to develop a practical numerical approach for applying the confining pressure to discrete element cylindrical triaxial tests. A layer of membrane particles with very low stiffness and extremely high contact bond strength was created around the lateral boundary of the cylindrical numerical specimen. To prevent the membrane particles from penetrating into the rock specimen on application of confining forces and to provide a smooth boundary surface, the space between the membrane and rock particles was filled using small-diameter packing particles. The results of this method were compared with those of rigid boundary method with confining pressure of 20MPa. The results obtained show that new approach gives both peak strength and post peak response that are in closer agreement with laboratory findings. BACKGROUNDThe discrete element method (DEM) has become the cornerstone for simulating both intact material and discrete fractures for low porosity strong rocks (ISRM Classes R3 to R6). Despite the advances in its application, simulating realistic behaviour of intact rock using the DEM remains a challenge. The bonded particle model was introduced as a potential solution for simulating the complex mineral grains in strong rock and other granular materials (Potyondy and Cundall, 2004; Utili and Nova, 2008; Salot et al., 2009). While some issues were resolved, a remaining challenge is the lack of the bonded particle model to simulate the brittle response commonly observed in strong rocks during the triaxial compressive test. Such behaviour is shown in Fig. 1 for Lac du Bonnet Granite at a confining pressure of 20MPa."

Jan 1, 2015