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By Michel David

"The usual complaint of mines is that grade does not match exploration expectations. Quite often, more tons are mined than expected but at a lower grade. This can be seen as dilution. Geostatistics can help predict which dilution can be expected both in terms of grade and tonnage for different mining methods.The usual vocabulary of geostatistics speaks of block distribution; block variance, size effect, information effect, all terms which say very little to the practitioner. In f act, all this can be rephrased in terms of dilution .In this paper, the following is presented - an example which shows how reserves change with the size of selection units and number of samples taken, and tables which show the dilution that are bound to happen when dealing with the commonly encountered log-normal distribution. Finally, the paper shows how grade tonnage computations should be made in the case of an arbitrary distribution. IntroductionGeostatistics progresses more and more rapidly if one judge s by the number and quality of papers published in Mathematical Geology or at APCOM meetings. More and more case studies describing successful applications are published (David et al., 1986)(Kwa and Mousset-Jones, 1987). It is estimated that more than 270/0 of the gold mines around the world use geostatistics. There is still, however, a lot of resistance from the remaining 73%. Geostatistics has more formulae and equations than it needs to reach year 2000. We will be well into the third millenium before all the models available now are actually used. The progress may come in the form of finding better ways to present known statistical results and getting away from the jargon of geostatisticians. One example may be in trying to explain how we can answer the most common plea of the mining industry: production grade is not what was expected in the feasibility study."

Jan 1, 1988

By Jack G. Hazan

The Critical Path Method is the modern scientific answer for solving the planning and scheduling problems inherent in today's complex projects. With this method, nothing is left to chance. All resources are controlled and kept to the minimum. The various phases are properly planned and strategically determined. Optimum conditions are evaluated for the most economical and fastest way to complete a definite project. The method must be fully understood and implemented with positive data and continuous feedback to obtain the best results. This paper covers the various aspects of the Critical Path Method and mentions some of its applications in the mining and metallurgical fields. T 0 progress to a higher state of human welfare necessarily involves sacrifices. The greatest sacrifice is to relinquish social freedom in favour of economic freedom. In the old days, for example, a cobbler was free to work at whatever time of the day he chose; today, he can't. He is now forced to adapt himself to environment and to work at stand-

Jan 1, 1965

By Andrzej Luszczkiewicz, Magdalena Duchnowska, KGHM Polska Miedz S. A., Witold Pawlos, Jan Drzymala, Alicja Bakalarz, Przemyslaw B. Kowalczuk

A pre-flotation process of the Kupferschiefer ore with only frothers produces a concentrate enriched in carbonaceous matter and tailings for further upgrading steps. A partial removal of easy-to-float components of the feed before the main enrichments steps by flotation (rougher, scavenger) improves overall efficiency of separation of valuable elements from the ore. Since the types and doses of frother used for pre-flotation effect the process, the aim of this study was to determine the influence of selected frothers on the efficiency and selectivity of the Kupferschiefer ore processed by KGHM Polska Miedz S.A. A series of pre-flotation tests in the presence of different poly(propylene glycols) ethers, poly(ethylene glycols) ethers and aliphatic alcohols were conducted. The obtained results indicated that the types and doses of frother determine the flotation selectivity of copper and total organic carbon. The evaluation of the pre-flotation process was based on the analysis of selectivity parameters calculated from the recoveryrecovery Fuerstenau upgrading curves as well as the values of copper and organic carbon grades in the flotation products. It was shown that pre-flotation performed in the laboratory scale using a suitable frother provides higher overall flotation selectivity of organic carbon with lower overall flotation recovery of copper in comparison to flotation without the pre-flotation step. Thus, the pre-flotation process improves the quality and quantity of the final concentrates produced from the Kupferschiefer ore.

Jan 1, 2016

By R. B. Casault, J. D. Boyd, D. R. Bell

"Full-scale sections of three different types of Grade 483 line pipe have been evaluated extensively. The variations in chemical composition, optical microstructure, tensile properties, hardness and Charpy impact toughness with specimen orientation and location were determined. Significant variations in several properties, notably Charpy shelf energy, impact transition temperature, inclusion content and ferrite grain size, were observed for different locations in the pipes. The results indicate that current specifications call for test samples for the most conservative locations, except for impact tests. Minimum Charpy impact values generally occur at the II2-width location, which may be a more appropriate specified test location than the present I/4-width location. The anisotropy of impact toughness, and the importance of low sulphur content and inclusion shape control for adequate toughness in the transverse/rolling-direction orientation were demonstrated. The orientation of impact specimens is critical for spiral-weld pipe, and the current specification test is non-conservative in that it can give results which are two to three times higher than the minimum value for the steel.IntroductionThis report presents the results of an extensive metallurgical evaluation of three different Grade 483 line-pipe steels. The sample material came from full-scale sections of line pipe, which represented current commercial practice at the time of manufacture (1975-1977). Since then, significant improvements have been made in the manufacturers' procedures for producing skelp and pipe, and the line-pipe specifications have been revised. Hence, the information in this report is dated in terms of current design, but it is unique and significant in several respects:"

Jan 1, 1982

By Jozef S. Stachula

"INCO Limited operates eleven under-ground mines in the Sudbury area. The mines are located on the rim of the Sudbury Basin, an oval with the axis in the range of 27 km and 60 km. The ore dips to at least 3000 m below surface. The ores are mined primarily for nickel and copper. Total ore production from underground is in excess of 55 000tonnes per day.Over 40 surface fans have been installed since the late 1960s. All of the fans are adjustable pitch, axial flow units. A major factor influencing ventilation design in the last 30years has been the introduction of diesel equipment underground. Volumes per fan have ranged from 60 m3/sec. to 330 m3/sec., with motors from 100 hp to 2500 hp.Fans of the axial flow type have been commonly used for main fan installations at Canadian mines for many years. The standard arrangement has been to mount these fans horizontally, i.e. with the fan shaft and the long axis of the housing horizontal. This is a natural arrangement for an underground fan, but for a surface installation, a vertically mounted fan has definite advantages.The surface area taken up by a typical vertical fan installation is generally about one quarter that of a horizontal fan of the same capacity (Rutherford, 1957). This is not a problem with isolated fans and fat surface out crop sites, but where the installation is to be near existing buildings, or where there are poor surface soil conditions, space and cost considerations greatly flavour vertical fans."

Jan 1, 1996

By L. Yaun

In underground coal mining operations, gas content in a coal seam is used to assess the risk of coal and gas outbursts. To estimate the gas content, a number of systems have been developed, however issues remain about the rapidness and accuracy of these systems. To address these issues, a new and improved system has been developed that includes a sampling-while-drilling unit for coal sampling, a coal canister, an underground-based portable measurement unit, a surface-based measurement apparatus, and gas content calculation software. The system has been successfully applied in underground coal mines at Huainan, China. This new, rapid and accurate system, its main components and field trials are described in this paper.

Aug 1, 2013

By J. F. Hazzard, R. J. Chalaturnyk, C. Khazaei

"Various measurement, monitoring and verification (MMV) techniques are used to ensure the safety of operations in petroleum projects. One of these techniques is microseismic (MS) monitoring of the caprock. A challenge in MS monitoring of caprock is that unlike projects such as tunnelling in hard rocks, the number of recorded events are much smaller and also wide spread through the rock mass which makes interpretation of the physical meaning behind the events very difficult.In this paper, a numerical technique is introduced and validated for coupling a finite difference code, FLAC3D (Fast Lagrangian Analysis of Continua), with a discrete element code, PFC3D (Particle Flow Code). Then, a similar approach is adopted for modeling microseismic events in the caprock. For this purpose, the underburden, reservoir and overburden layers are modeled by FLAC3D. A rather small section of caprock above the reservoir is nulled in the FLAC3D model and substituted by a PFC3D inclusion. The reservoir pressures are then applied to the reservoir section of FLAC3D. Once the FLAC3D cycles, there will be induced pressures in the caprock due to its undrained response to the change in pressures within the reservoir. These induced pressures are transferred to PFC3D as boundary velocities. Then the PFC3D cycles and sends back the boundary forces to FLAC3D. This back and forth process continues until equilibrium is reached. During this process, there will be bond breakages within the PFC3D inclusion that can be regarded as MS events. An algorithm for recording the microseismic energies based on a change in local strains is also implemented. The results are then compared with real data. The effect of injection fluid temperature is also studied. No significant appearance of microseismic events was observed due to injection of CO2 in both cases (i.e. with or without considering temperature). However, this continuum/discontinuum approach seems promising for understanding the microseismic response of caprock in more detail and also using the MS data for validation of geomechanical models."

Jan 1, 2015

By P. K. Kaiser, F. Amann

"Rock mass characterization for deep underground construction and mining offers many challenges. This paper first describes some of the key challenges when characterizing highly stressed brittle rocks and then offers some guidance on how to arrive at reliable rock mass strength parameters for deep mining applications. Focus is placed on characterization for rock mass strength determination. It is illustrated how the common use of currently available rock mass characterization systems tend to underestimate the strength of rock at depth. Modifications to currently adopted approaches, i.e., the use of Geological Strength Index GSI for rock mass strength determination, are presented.INTRODUCTIONFor green fields projects, the first challenge of rock mass characterization stems from a lack of access to examine the rock mass at scales larger than typical core sizes (i.e., ~63mm in diameter) until late in the mine design when the flexibility for making changes is constrained. Hence, rock mass characterization often has to rely on information derived from boreholes alone (e.g., core, logs, etc.). This challenge is lessened when mines are expanded from existing operations. A second challenge is related to changing rock mass behaviour with increasing depth and stress. At depth, the rock is highly stressed, thus closer to failure, and often highly confined which leads to a higher interlocking with elevated strength but more brittleness. The goals of rock mass characterization are to be tailored to the technical goals of an investigation. For example, for cave engineering, the workflow includes the assessment of five key engineering aspects (Brown, 2007): Caveability; fragmentation; cave performance; extraction level stability; and mine construction (rock support). Each engineering aspect has to address specific engineering questions and each design component is influenced by different rock mass behaviour aspects and thus is dominated by different rock mass properties, e.g., the vulnerability to stress fracturing (spalling), the bulking characteristics for flow control and support selection, and the confining stress impact on pillar or support design. An effective rock mass characterization program, including logging, mapping and laboratory testing, thus has to collect and interpret features that are relevant for the above listed purposes. Some of the predominant factors are: block volume of defected and non-defected rock; spalling strength; tensile strength of defects; rock mass modulus; and rock mass strength parameters for application to low and high confinement design aspects."

Jan 1, 2015

By Marcel Laflamme, N. R. Rillette

"In 1982, a study was initiated to investigate relationships between bonus and accidents in Quebec underground mines. In 1983, the study was expanded to include the impact of age and experience on accidents.The paper will describe the methodology followed in gathering information at ten mines from three mining camps in the Province of Quebec, and its transfer to data banks for subsequent treatment. Multifactorial analysis of nine variable files for the ten mines has shown: that age, experience and seniority are linked; that total working hours are tied with overtime; that bonus is linked to the main activity of the miner, and not to accidents. The most tangible factors affecting accidents seem to be the introductory training and subsequent retraining at regular intervals."

Jan 1, 1989

By C. Beaudry

Outline ? General Geology of Frieda River Project Area ? Exploration History ? Geology of Porphyry Deposits ? Porphyry Resource ? Update of Nena Deposit and High-Sulfidation Mineralization ? Nena Resource

May 1, 2006

By Shahé Shnorhokian

Numerical modeling is increasingly being used as a tool to examine complex geomechanical issues related to rockmass behaviour and stability of underground openings. The in-situ stress regime and the evolution of mining-induced stresses during the life of an operation, taking into account the planned stope sequence, are topics that can only be handled through the use of a realistic and calibrated numerical model. This paper presents a case study of a deep underground Canadian mine in northern Ontario. A FLAC3D model was constructed and calibrated based on in-situ stress measurements. In the first stage, the evolution of stress regime was studied and compared with the occurrence of rockburst events during a period of three years. The locations of clusters were examined and compared to the mining sequence during that period. In the second stage, stresses within a diminishing ore pillar were examined based on the planned stope sequence and compared to levels deemed acceptable to the mine. Based on the results, an alternative sequence was arrived at to reduce stress accumulation in the pillar, or induce it to occur at a further distance from a brittle dyke in the vicinity of the orebody.

Aug 1, 2013

By F. M. Waldie

THE 2,538-foot belt conveyor recently installed underground at the Sullivan mine hoists ore from the 3,350-foot level to the 3,900-foot or main haulage level, a vertical distance of 680 feet. The design and planning of development work, under the direction of Mr. R. H. Stewart, Consulting Engineer, was begun in the spring of 1941. Development work was started in July of that year from the 3,350-foot level, and headings were started on the 3,650-foot and 3,900-foot levels later in the same year. It was the intention at that time to keep three headings going on development work necessary for the installation of the system: two on the conveyor incline, and one on the 3,900-foot level. This programme was modified in 1942 when there was some doubt whether the material for construction could be obtained. This problem of supply was eventually solved and the development work was pushed to completion in December, 1943. Construction was started in December, 1943, "'under the supervision of Mr. G. H. McKay, Superintendent of Construction and? Maintenance, and was completed in November, 1944.

Jan 1, 1945

By N. Bakhshizadeh

In this investigation, the aging effect on creep behavior of A12024-10%SiC composite fabricated by powder metallurgy was studied. P/M bars were manufactured by hot powder extrusion method at 450°C with a ratio of 16 to 1. Creep specimens were over-aged at 187 ºC for 43 h. It was found that almost full density composite with relatively homogenous distribution of reinforcing particles throughout the aluminum alloy matrix could be attained by direct powder extrusion process. Creep tests were conducted at temperatures from 275 to 325°C under stresses from 25 to 60 MPa. The analysis of the creep mechanism determined that dislocation glide was the predominant mechanism of plastic deformation. The activation energy of the creep process was found to be higher than that of lattice self-diffusion in pure aluminum.

Jan 1, 2007

By S. Xu

Magnesium alloy AM50 is of interest to automotive cradle application because of it excellent castability and good ductility. In this work, microstructure and mechanical properties of both low pressure die cast (LPDC) and high pressure die cast (HPDC) AM50 test bars are characterized. Microstructure was examined using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Phase identifications were performed using energy dispersive x-ray spectrometer (EDS) and TEM diffraction. It has been found that LPDC produces much coarser microstructure than HPDC. At the same time, the HPDC samples are more heterogeneous in microstructure and composition close to grain boundaries. Particles with various dimensions and morphologies of two different intermetallic phases, Mg17A112 and A18Mn5, were found in all the samples. Mechanical tests were performed under conditions similar to those related to an engine cradle application. LPDC samples show lower strength but better creep resistance than HPDC mainly due to the difference in grain sizes and grain boundary microstructure between LPDC and HPDC. Creep curves are well described by the empirical Andrade equation. Tensile-compressive yield and creep asymmetries were found in AM50, i.e. better deformation resistance in tension than in compression. The average yield asymmetry ratio for all the samples is 0.87. Microstructural examinations on the samples tested in tension, compression and creep showed that the deformation mechanisms in AM50 were slip plus twining at temperatures up to 125°C. The examinations indicate the important role of twining in the asymmetry phenomenon. The creep results indicate that dynamic precipitation of the Mg17A112 phase during testing is not the mechanism directly responsible for the creep asymmetry in AM50.

Jan 1, 2004

By A. J. Keen

"Cominco's Polaris Mine is an underground lead/zinc operation located on Little Cornwallis Island in the Canadian High Arctic. Polaris is the world's most northerly base metal mine, situated at about latitude 75°N and longitude 97°W (Fig. 1). The closest community is Resolute Bay about 100 km to the southeast.During the construction and development phase Cominco adopted a unique scheme to save time and money. Many facilities including concentrator, powerhouse, shops and warehouse were built on a barge in southern Canada. The barge was towed 4800 km to the site in August 1981. Production at Polaris began in November 1981. The current mining rate is 1 million tonnes per year. The mine employs 250 people with about 190 on site at any time.GeologyThe deposit is a Mississippi Valley type orebody and lies near the top of the Ordovician Thumb Mountain Formation. Ore minerals consist of sphalerite and galena with the gangue being predominantly dolomite with calcite and marcasite. The orebody is situated completely within permafrost, consequently the voids frequently found in the ore are filled with ice. The orebody strikes north-south, dips approximately twenty degrees to the east and takes up an area about 400 m wide by 700 m long. The upper portion of the orebody (60 m to 150 m below surface) lies in an area called the Panhandle Zone. The deeper portion of the orebody known as the Keel Zone extends to 300 m below surface (Fig. 2). The deposit is strongly zoned with a high grade zinc/lead and iron-rich tabular core overlain and underlain by vein, stringer and breccia mineralization. The ore reserves at January 1991 were 14.6 million tonnes at 3.6% Pb, 13.7% Zn, 3.2% Fe, after producing 8 million tonnes at 3.9% Pb and 14.2% Zn since November 1981"

Jan 1, 1992

By E. Gaucher, D. C. Gagnon

"The paper refers to methods and concepts used in the computer treatment of banks of geophysical, geochemical and geological data, relating to the exploration of massive sulphides. In particular, a data bank of 400 drill holes on independent conductors can be used to calculate probability levels of intersecting a certain quantity of sulphides according to the characteristics of the conductor. Inversely one can, using the data bank and some cost assumptions, simulate and optimize the cost of intersecting a certain quantity of sulphides by selecting drill targets among conductors according to conductivity, magnetism or gravity. Problems of noise, inherent in any simulation, are illustrated in this paper by the results of a study of the nomenclature of volcanic rocks of 27 drill holes by forty geologists. Compilations of data banks are long and timeconsuming, and it would help to standardize to allow exchange of data. We believe that such efforts may result in the discovery of more mineral deposits and at a lower cost. The present study is supported jointly by SOQUEM The New Jersey Zinc Co. and Cominco Ltd."

Jan 1, 1973

By T. Lamb, T. Aston

"The Gays River Mine is located within a complex hydrological regime and underground mining environment. Early in the mine history, the operation was' affected by an inability to control mine water inflows. More recently, the reopened mine operation had been unable to maintain consistent drainage of groundwater to the mine workings and sustain low groundwater levels.In 1992, a series of investigations were completed, which in part Were funded under the Canada-Nova Scotia Mineral Development Agreement. The studies undertaken included: hydrochemical and drainhole well screen assessments, an air photo study of sinkhole features, numerical modelling studies and a major piezometer installation and overburden soil study. The results indicate that the water draining to the underground workings is comprised of two distinct components: precipitation over the drawdown cone catchment area and seepage from the nearby Gays River. In addition, a third ""balance"" component was' also found, which represents uncertainties in the areal extent of the drawdown cone and river seepage components.After outlining the history of the groundwater problems experienced at the Gays River Mine, this paper examines the various studies undertaken during 1991-1992 and concludes that control of groundwater levels in the mine area is achievable. A number of recommendations are also proposed for future study ."

Jan 1, 1993

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 R. Kumar, A. K. Verma

"In this paper, an anisotropic shear behavior of rock joints is investigated under constant normal load condition (CNL). The natural rock joint roughness is transferred to artificial rock samples using room temperature vulcanizing (RTV) silicon rubber. Artificial cylindrical rock joint samples (90 mm diameter and 50 mm height) are made by mixture of cement, sand, and water in the ratio of 1:1.5:0.45 (by weight). Direct shear tests are conducted on these samples in twelve directions at 30º apart at four different normal stresses (250kPa, 500kPa, 1000kPa, and 1500kPa). Thus, 48 samples are tested in laboratory. Test results shows that the peak shear strength (?) of rock joints is anisotropic in nature due to change in morphological features in particular shearing direction. Joint roughness coefficient (JRC) is determined in each shearing direction by trial and error method using Barton’s model (1973). Further, cohesion ( c) and angle of friction ( ? )of joint surface in each direction is determined. Finally, a relationship between angle of friction ( ? ) and joint roughness coefficient (JRC) is developed. Experimental shear strength and Barton’s shear strength is compared and it is found that effect of anisotropic decreases with increasing normal stress. INTRODUCTIONRock mass is generally composed of discontinuity which refers collectively to joints, faults, bedding plane and folds etc. ISRM (1978) defined joint as a line of break of geological origin along which there is no visible displacement. Joint is three dimensional discontinuity which composed of two matched/mismatched surfaces. The presence of joints in rock mass plays an important role to define its overall shear strength, deformability behavior, in-situ stresses and hydro-geological properties. The shear strength of rock joints is important in the design of near surface/ deep geotechnical works (mining excavation, dam foundation, power plants, underground caverns, and slopes).In last 40 years, many constitutive models are developed to predict shear strength of rock joints under CNL conditions (Patton 1966; Landanyi and Archambault 1969; Barton 1973; Goodman 1976; Barton and Choubey 1977; Plesha 1987; Desai ad Fishman 1991; Amadei and Saeb 1992; Maksimovic 1992; Wibowo et al. 1993; Huang et al. 1993; Amadei et al. 1998; Indraratna 2000; Homand et al. 2001; Wang et. al. 2003; Samadhiya et. al. 2008; Asadollahi and Tonon 2010; Ghazvinian et al. 2012). These constitutive models have limitations to predict shear strength of rock joints in one direction. Till date, among all constitutive models, Barton (1973) model is widely used in practice due its simplicity. It includes parameters such as joint roughness and joint compressive strength (JCS) to quantify joint surfaces."

Jan 1, 2015

By T. Xue

429 As part of Inco's S02 abatement project for its Sudbury operations, a weak acid treatment plant (W ATP) was commissioned at the Copper Cliff smelter in August of 2004 to treat the weak acid streams generated by the flash furnaces, the MK reactor and the fluidized bed roaster (FBR) gas cleaning plants. The W ATP process was developed by Inco Technical Services Limited (ITSL) by means of laboratory and mini-pilot plant programs. In the W ATP process, the feed solution containing arsenic, sulphur dioxide, iron and other impurities is treated by oxidation and neutralization to form a stable precipitate for disposal in Inco's tailings impoundment area. During the commissioning of the WATP, a team of operations, maintenance, engineering, project and R&D personnel was formed, and the designed capacity was achieved in less than a month. Since then, the W A TP has been operating smoothly and the impurities, specifically arsenic, in the Copper Cliff smelting process have been effectively removed.

Jan 1, 2006