Search Documents

By Peter A. Bevan

"In massive and semi-massive deposits, it is essential to take samples continuously for specific gravity determination as well as for assays of the various metals of interest. Failure to use specific gravity in mixed deposits of high density contrast will result in incorrect determinations of the average grade.Graphs and linear equations of specific gravity against the grade of one metal are not considered accurate enough in a multi-mineral deposit, but appear to be very satisfactory in a theoretical one-sulphide/gangue mix. Specific gravities based on base-metal values only in massive sulphide deposits will result in underestimating the effect of low grade areas on the average grade and also cause a reduction in the calculated tonnage.IntroductionBy definition, a base-metal assay is the percentage of metal by weight contained in a sample, whether it be a soil or silt sample, a grab, chip or channel sample, or a section of diamond drill core.In those cases where there is a series of contiguous samples, say in diamond-drill core, the average grade may be required of the various assays that are above a desired or required cutoff grade.Internal low grade or waste can be included if the assays one side or the other are used to ""carry"" the lower grade material and the resulting average grade is above the cut-off grade. To determine the average grade, the individual assays are ""weighted"" by multiplying these values by their respective lengths, adding up the cumulative assay times length and dividing by the total length. This method is essentially a weighting by volume, because the core diameter is constant and is common to all the samples being considered for estimating the average grade . If some of the core samples have much higher specific gravities than others, and the specific gravities are not used in the weighting process, the resultant average grade will be over-estimated or underestimated, depending on the grade of the heavier sections. When core assays of approximately the same specific gravity or weight are averaged by length, the error in the weighted estimation of the average grade is negligible."

Jan 1, 1993

By Robert B. Parsons

"Canadian income tax legislation contains a number of provisions which serve to facilitate the structuring of business arrangements, including mineral resource ventures. These rules are often fairly complex and not easily understood. This article attempts to explain in plain and understandable language the mechanics and benefits of one of the more frequently encountered provisions, the ""Section 85 election"".IntroductionThe Canadian resource industries are probably singled out for more special attention under this country's tax legislation than any other industry. This special treatment is, of course, not always welcomed by the industry, such as where unnecessarily restrictive taxation is perceived to exist or where agonizingly complex tax legislation must be dealt with. On the other hand, certain provisions in the tax legislation treat the industry in a relatively favourable manner, including a number of rules which, in recognition of the high risk and capital requirements of the resource sector, serve to facilitate the structuring of resource ventures."

Jan 1, 1984

At the end of a century of mining education in South Africa, it is appropriate to reflect on the past, take stock of the present and ponder the future of mining education. While it is likely that changes in the mining industry will generate an increased demand for mining graduates, the number of suitably qualified applicants to study mining is worryingly small. While good progress has been made in unifying the educational system that previously provided schooling on a racially separate basis, it appears that a decade or more will be required to raise competency levels in mathematics, science and English, and this paper describes the process as it affects mining engineering programs. It also describes the initiatives currently being undertaken by the University of the Witwatersrand and the mining industry to ensure that the South African industry receives an adequate flow of well-qualified mining graduates, despite more than 70% of the intake coming from severely disadvantaged educational backgrounds.

Jan 1, 1999

By J M. Gibbs

Craigmont Mines Limited mine 50,000 tons of ore and waste per day from the open pit at Merritt, British Columbia. An electric-powered "down-the-hole" drill, a diesel-powered rotary drill and two electric-powered rotary drills have been used. All primary drilling, as a result of cost and operating experience, is now performed with two electric-powered rotary drills. Trials with various loading techniques have increased the amount of AN-FO and decreased the amount of commercially prepared slurries used for primary blasting. Approximately 95 per cent of the primary blasting is accomplished with AN -FO, mixed at the hole. Introduction THE Craigmont mine is located near the village of Merritt, B.C., 240 miles northeast of Vancouver. The concentrator has been in production since September of 1961. Craigmont is a combined open-pit and underground operation. To date, slightly more than 95 per cent of the mill feed has been mined from the open pit. As underground development proceeds, the ore requirements from the open pit will decrease. The average milling rate from September, 1961, to April, 1964, was approximately 4,900 tons per day.

Jan 1, 1965

By J. Palarski

In the Polish coal mining industry, the use of mine waste in underground backfill has been the most common means of providing ground support to minimize surface subsidence, increasing extraction ratios, and reducing the quantity of waste for surface disposal. Over the last decade attention has been focused on the use of different waste as filling material of underground workings and grouting of roof fall rocks in caving area. In the paper, a brief history of the development of fill technology in Polish coal mining industry is presented. Next, the paper discusses various criteria that should be taken under consideration in the preparation process of a fill slurry and grout, fill distribution systems, mining geometry and placement methods. Moreover, in the paper evaluation of the potential of utilizing coarse and fine waste as a resource material in the production of a backfill slurry and grout for filling and injection in abandoned mines is presented.

May 1, 2007

By A. Zarei-Hanzaki, S. M. Fatemi-Varzaneh, M. Haghshenas

The microstructure in modified semi-solid ALTHIX (A356) alloy consists of aAl phase with Al/Si eutectic structure. Silicon phase in eutectic structure is coral like with fine fibers. The lack of good ductility in this alloy is related to the presence of silicon fibers. Accordingly many investigations have been recently conducted to modify the Si morphology through Thermomechanical processing on this alloy. In the present work an ALTHIX (A356) alloy was deformed at 450°C, 500°C and 540°C through different strain rates. Consequently the silicon fibers were broken into small particles. The results indicated that the Si particles may coarsen according to Ostwald ripening mechanism at 540°C deformed by rate of0.0005 sec-1 & 0.0001 sec-1-

Jan 1, 2006

By I. Lazaro Roche, J. Brunner, J. Busto, X. Martin, J. B. Decitre, S. Gaffet, F. Hivert

"Muon tomography allows investigating the subsurface. Muons being penetrative, the attenuation of the muon flux depends on the quantity of matter the particles travel through, hence on the rock density and thickness. For the Temporal Tomography of rock Density using Muon Measurements (T2DM2) project, the muon flux measurements are performed in LSBB URL (http://www.lsbb.eu) in order to study the hydrogeological processes in the unsaturated area of Fontaine-de-Vaucluse karst aquifer. The suitability of the muography for this study is here numerically demonstrated. In parallel to these simulations, muon flux measurements are carried out in the LSBB galleries by means of a set of four scintillator tanks and Micromegas detectors are developed. These detectors, here described, are adapted for underground and confined spaces as well as other environments. Their performances are particularly interesting and should contribute to the expansion of muon tomography in new application fields. INTRODUCTIONMuon tomography or muography is a method to image large volumes by measuring the absorption of cosmic ray muons. It uses, in a passive way, a natural radiation source: the muons which are charged particles produced in the atmosphere. Primary cosmic rays interact with atmospheric nuclei and produce a huge number of secondary particles, including muons. Due to their important mass compared to electrons, they are highly penetrating, reaching several hundreds of meters below the surface. Their attenuation depends on the quantity of matter they cross. That's why they are used to investigate the subsurface, muon absorption measurement allowing to estimate the in-situ density of the rock.Georges (Georges, 1955) proposed in 1955 to use the muons in order to study the density variations caused by the overburden over an Australian tunnel. In 1970, Alvarez (Alvarez, 1970) imaged the internal structure of Chephren Pyramid thanks to this method. The muon tomography has been particularly developed for volcanology (Nagamine, 1995; Tanaka, 2007; Lesparre, 2010; Carloganu, 2013) over the last twenty years. Since the beginning of the 2010's, a growing amount of projects that proposed to use the muons in various fields get underway: the CO2 storage (Kudryavtsev, 2012), the exploration of Mars (Kedar, 2013), etc."

Jan 1, 2015

By Hung-wei Liu, Kevin Plucknett

Early attempts to manufacture titanium aluminides using blended elemental powders, through powder metallurgical processes, have been obstructed due to serious swelling during sintering. Although the use of pre-alloyed powder can avoid this undesired expansion problem, there are limited commercial powder sources available. Therefore, in the present research, fundamental studies on the synthesis of dual-phase (? plus a2) Ti48Al intermetallic materials is undertaken, in particular assessing powder manufacture. In order to produce pre-alloyed powders, highly porous Ti48Al pieces are initially sintered from elemental Ti and Al powder blends, and subsequently pulverised into powders. The powder size is then further reduced by use of either dry or wet milling processes (i.e. shatterbox grinding, attrition, or ball milling). Among these methods, shatterbox grinding has shown the highest efficiency, with a slight mechanical alloying effect observed. The manufactured powder morphologies and phases, as well the sintered material, will be discussed.

Jan 1, 2015

By K. Hashiba, Y. Z. Liang, K. Fukui, M. Koizumi

"Efficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Development and modification of the rock drills based on test data are timeconsuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved. The objective of our research project is to construct a new realistic numerical model of continuous percussive drilling, which is based on the previous Okubo-Nishimatsu’s model. In this study, the parts of the previous model involved in stress wave propagation and attenuation were modified. The two models were prepared for HD712 hydraulic rock drill mounted on crawler drills and HD210 hydraulic rock drill mounted on drilling jumbos. Stress wave propagation was computed with the discretized one-dimensional wave equation. The calculated results were compared to the stress waves measured on a rod during percussive drilling. In both models for HD712 and HD210, the measured stress waves can be reproduced with the one-dimensional model of the same acoustic impedance as the actual piston, shank rod and rod combined with the CI+spring model as a rod joint. The calculated results indicate that the spring constant in the model of a rod joint needs to be set appropriately depending on drilling conditions. INTRODUCTIONEfficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Components related to the percussive drilling are a drill body, a piston, a shank rod, rods, rod joints, a bit and rock. The piston in the drill body is reciprocated by hydraulic pressure and collides with the shank rod a few thousand times per minute. Stress waves generated by the collision propagate and attenuate in the rods and rod joints, and then reach the bit. The bit penetrates and crushes rock. During percussive drilling, the components mutually affect each other and self-induced oscillation occurs. The number of blows and the rate of penetration are determined by the practical drilling conditions such as hydraulic pressure, thrust force, number of rods and mechanical properties of rock. Development and modification of the rock drills based on test data are time-consuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved."

Jan 1, 2015

By S. L. Gula

"Effective and timely communication during routine operations, and especially during emergency situations, is no easy task in any underground mine. At Cominco Fertilizers, Potash Operations, where 150people are employed underground to produce 3.1 million tonnes of potash per annum at a depth of 1100 m (3600ft), this is no exception. The over-all mine workings underlie an area of approximately 20 km 2 with average travel time to the active mining areas being approximately 30 to 40 minutes by light vehicle, and significantly longer than this for heavy equipment.In a mine of this size, the deployment and management of personnel and materials on a day-to-day basis, and during mine emergencies, is an important exercise. The Personal Emergency Device (PED) system has provided the Potash Division a means to achieve improvements in this area and reduce the communications bottleneck.The MineAt Cominco Fertilizers Potash Operations, approximately 30 km southwest of Saskatoon, the orebody is the same horizon being mined by other potash producers in the Saskatoon area and extends over 300 km in an east-west direction, and approximately 150 km in a north-south direction. Mining operations are carried out with approximately 150 employees operating on a continuous-shift basis, seven days a week.Mining is presently being done from Block 6 which takes the mine to its northernmost boundary and contains reserves of approximately 50 million tonnes. Production is from one level by five twin rotor continuous mining machines, each capable of cutting a face up to 5.5 m wide and 3.3 m high . All ore is transported to the shaft via approximately 20 km of conveyor where it is removed to surface by two 24 tonne skips.After the ore is conveyed to the mill for processing, the finished product is shipped by rail car or trucks to other parts of Canada, the United States or through Vancouver to other parts of the world."

Jan 1, 1993

In most instances, the preferred mining methods in steeply dipping narrow vein deposits are selective methods such as cut and fill or shrinkage. The main advantage of these methods lies in the higher degree of control over dilution that can be achieved. However, where ore body geometry lends itself to it, high yield bulk methods can also be attractive. Higher productivity (and the associated lower costs) and lower worker exposure are some of the significant advantages that have made such methods so popular. The Lapa gold mine located in North-Western Quebec uses the long hole mining method (with cemented rock fill) very successfully despite challenging ground conditions. This paper focuses on the experience of the mine with regards to drilling and blasting practices. Firstly, the reasons that prompted the selection of this mining method at Lapa are examined. Secondly, the challenges that the difficult ground conditions found at Lapa pose to drilling and blasting are discussed. Finally, the results of trials of different drilling and blasting strategies that were performed at the mine are presented with particular emphasis on the lessons learned.

Aug 1, 2013

By J. R. Levin, E. J. Schelter

"We present some of our recent efforts in the development of predictive, directed oxidation chemistry of cerium(III) complexes under non-aqueous conditions. The electrochemistry of cerium(III)- alkali metal heterobimetallic aryloxide complexes is reported and compared with cerium aryloxide complexes that are kinetically stabilized by hydrogen bonding cations that span between the complexed aryloxide ligands. Comparative electrochemical measurements reveal differences between the heterobimetallic complexes and the hydrogen-bonded complexes.INTRODUCTIONThe rare earth elements comprise the lanthanides, La–Lu, and the element yttrium (Aspinall, 2001). Rare earth ores such as monazite, LnPO4, and bastnäsite, LnFCO3, typically bear mixtures of light rare earths: La–Sm while monazite, LnPO4, contains mixtures of heavy rare earths (Eu–Lu) (Cotton, 2006). Pure rare earth elements typically are isolated using a liquid-liquid separations process.(Bautista, 1995) The hydrometallurgy of these elements is a difficult problem because the separation factors between neighboring rare earths, which are predicated on the small differences in the sizes of the trivalent ions, are quite small (Cox, 1992). The element cerium, with its 4f1 electronic configuration in the trivalent state, is unique among the rare earth elements due to a relatively accessible 4f0 electronic configuration. The accessibility of the 4f0 configuration underlies the chemistry of cerium(IV), the only rare earth ion with molecular chemistry in the tetravalent oxidation state (Cotton, 2006). Cerium is trivially separated from mixtures of light rare earths by making use of its unique oxidation chemistry. In an effort to extend separations chemistry by oxidation reactions to other rare earth elements such as terbium and praseodymium, the solution electrochemistry of well-defined cerium complexes is of interest."

Jan 1, 2012

By P. C. Lightfoot, J. M. Duke, A. J. Naldrett

"The segregation of magmatic sulphides from mafic and ultramafic silicate magmas, in many circumstances, leaves the magma with a lower-than-normal Ni/MgO ratio, which is characteristic of both lavas erupted from the magma chamber and olivine crystallizing within it. Two end members of the segregation process are discussed; i) batch segregation and ii) fractional segregation.In the former, the critical factor is the magma/sulphide ratio. Computer modelling suggests that where this ratio has been less than 1000, the magma will be recognizable as anomalously low in Ni, due to sulphide segregation, and thus a good target for exploration. In fractional segregation, the critical factors are the proportion of sulphide to silicate being segregated and the degree of fractionation.Samples believed to represent the liquid portion of komatiitic lava f lows from a series of unmineralized sequences in the Abitibi greenstone belt, Canada. Belingwe belt, Zimbabwe, and Barberton Mountainland, South Africa coincide with the sulphide-free fractionation model. They are in marked contrast to samples from the ore-bearing districts of Kambalda and Scotia. Western Australia in which distinct Ni depletion, corresponding to fractionation of olivine plus sulphide in a ratio of between 100 and 200:1 is recognizable. Ni-depleted olivines also mark the sulphide-bearing Dumont intrusion of the Abitibi belt.The Moxie intrusion of northern Maine has distinctly Nidepleted olivines, as does the nearby and petrologically related Katahdin body. In both of these intrusions, the composition of the olivine allows reasonable predictions to be made of the Ni tenors of sulphide showings within them. At Katahdin, the Ni depletion is so widespread that little hope is help out for the presence of economic concentrations of sulphide. At Moxie. the olivine compositions suggest that the best chance of economic sulphides lies in the southern lobe of the intrusion.Ni-depleted olivines also characterize certain rock units within intrusions of the Insizwa complex, Transkei, Southern Africa. Many millions of tonnes of Ni have apparently been removed by sulphides from these rock units, many more than are contained within the single mineralized occurrence so far identified at Waterfall Gorge."

Jan 1, 1984

By K. G. (Ken) Thomas

"This paper gives an insight into the various processes available to treat gold ores. A brief overview is given of the various types of refractory gold ores. Particular emphasis is given /0 comparing the costs of oxide vs refractory gold ore processes, inclusive of grinding through to dore bar.HistoryThro ugh time gold has been recovered from the earth's crust by various mean s. Five major historical steps can be identified for metallurgical processing as shown in Table I .Gravity concent ration started with, for example, river bed panning and developed to more sophisticated processes such as the Johnson concentrator, belt concentrator and jigs. The South African gold fields were a major developer of gravity concentration processes during the first half of the twentieth century.As coarse free gold became depleted, stamp milling, in conjunction with amalgamat ion , was developed. Basically, rock was crushed under large mechanical hammers an d the gold collected in mercury . The mercury was then evaporated in a retort to leave sponge gold for further fire refining.As deposits became deeper and gold finer, the gold became more difficult to recover ; fine grinding was required to liberate the gold. In the 18905, MacArthur and the Forrest Brothers of Glasgow, Scotland, introduced the cyanide pro cess for dissolution of gold and its subsequent precipitaiton by means of zinc. This process, in vogue until the early 1970s, was commonly referred to as the Merrill-Crowe process for recovering fine gold .Activated charcoal was used as a means of recovering gold from solution in the 1880s, especially in chlorination plants in Australia( l). Two factors probably retarded the development of carbon instead of zinc-based processes during those year s. First , there was no satisfactory procedure for the elution of carbon to allow its recycling and, second, the development of the Merrill-Crewe process for gold recovery by zinc cementation probably discouraged any further work on the use of carbon"

Jan 1, 1991

By P. Hanniala, S. Harkki, B. Andersson

"The Outokumpu Flash Smelting Process was put into commercial operation in 1949. The original process was based on the use of preheated air. The adoption of oxygen enrichment of the flash smelting process air in 1971 was a crucial improvement, especially for smelter capacity. Oxygen use according to the Outokumpu method means selection of the most suitable oxygen content for the process air on the basis of the concentrate composition, capacity and matte grade. The furnace is not bound to only one fixed degree of process air oxygen enrichment; the oxygen content may vary from 21% to 100%.The degree of oxygen enrichment and the matte grade are the most important process parameters in reducing the operating costs of the whole system, including smelting, converting and acid production. Raising the matte grade allows more efficient use of the reaction heat in the smelting stage. Sulphur is recovered in a high-strength, constant-flow gas stream. The blowing time in the converters is reduced considerably.Oxygen enrichment and high matte grade improve the energy efficiency of the plant complex as long as the surplus heat from the system is not wasted. When the operating costs and investment expenditure of the total plant complex are taken into account, a reasonably high degree of oxygen enrichment (35-80°/0) is the best alternative in practice. Existing operating smelters have achieved single-stream thoughputs of over one million t/yr of concentrates.HistoryLocal capital and operating costs as well as lower energy consumption per unit of metal produced are now the crucial factors in determining the choice of process. In the late I940s, the same reasons prompted Outokumpu to develop the original flash smelting process in Finland. Between 1900 and 1940, very few technical changes in pyrometallurgical copper production took place. However, the commercial use of the flash smelting technique began a new era in metal extraction from sulphide concentrates. The characteristic feature of the method is that the concentrate is smelted in suspension: this offers the most favourable conditions for heat and mass transfer, and thus high reaction velocities. Outokumpu was the first to exploit the known advantages of flash smelting in a commercial installation at Harjavalta in 1949."

Jan 1, 1982

By G. J. Arseneau

Mineral resource statements are reported as tonnage and grades. While great care is placed on generating a reliable estimation of grade, the determination of bulk density for resource estimation is often overlooked. Often mineral resource statements are prepared using a simple average value of bulk density. While a simple average estimate of bulk density can be appropriate for some deposit types, an over simplistic estimation of bulk density can result in serious errors in tonnage estimates and consequently to an over or under estimation of metal content. The construction of a reliable bulk density model requires an adequate bulk density database in order to develop a good understanding of the variability of bulk density with grade and geology. A reliable bulk density database is also essential in determining the appropriate modeling technique to minimize the errors in mineral resource statements caused by incorrect bulk density determinations. This paper summarizes bulk density measuring techniques and draws on examples from various deposit types examining the basic principles of bulk density modeling and domain construction for each deposit type. Examples are presented of simple bulk density domains and more complex grade variable bulk density domains with a discussion of best approaches for minimizing errors in density estimation.

Aug 1, 2013

By Y. Lizotte

"This paper examines the application of blasthole sloping to narrow vein mining in Canada, for ore deposits where widths are less than two metres. While the technique has now been utilized for more than ten years, it remains in the experimental stage and on-site testing is necessary for its adoption at new mining operations or in differ¬ent geological settings. It is intrinsically a safer method than other narrow vein methods in current use.The investigation describes the main operating parameters for mines recently surveyed. The criteria for method applicability are defined and the problems encountered are studied. It is concluded that blasthole sloping for narrow vein mining is a viable modern method which promises to gain popularity and that emerging fragmentation technology and blasting research can be used to further increase applicability of the stoping method."

Jan 1, 1991

By T. H. Patching, D. F. Coates

The Sub-Committee on Rock Classification, Canadian Advisory Committee on Rock Mechanics, has evolved a classification of rocks which should prove useful in studies of rock mechanics. Considered in two stages -actual rock substance and rock mass -the five-point classification involves the geological name of the rock, the rock strength and rock deformation, and, in the second stage, the gross homogeneity of the rock mass and the formation continuity.

Jan 1, 1968

By John E. Udd

In early 2000, CANMET-MMSL was engaged by the Ontario Ministry of Labour (OMOL) to conduct an international study of the practices, in several key mining jurisdictions, of determining the criteria that are used to decide when the wire ropes used in mine hoisting are to be retired from service. Subsequently, the writer visited key officials and institutions in Canada, the USA, the Republic of South Africa, the United Kingdom, Germany and Poland. Material from the Australian province of New South Wales and Hungary was also included. The report that resulted included, among other sections; (1) the history of wire rope and trends in manufacturing technology; (2) a review of mine hoisting practices; (3) the requirements as regards safety factors; (4) a review of the players and the inspection practices; (5) the criteria for rope replacement; (6) a look into the future to outline the developments that could take place in both hoisting and rope inspection practices in Canada; (7) recommendations. Subsequently, the report was issued as a book by OMOL, and as a CD-ROM by the Mining and Mineral Sciences Laboratories, Natural Resources Canada. In this paper the author presents the key findings and the recommendations made in the study.

May 1, 2003

By M. E. Holter

"Five main lignite seams occur in the Tertiary Ravenscrag Formation in the Eastevan area, at depths of 100 feet or less. They are named, in ascending order: the Boundary, Estevan, Souris, Roche Percee and Short Creek seams. A total sequence of approximately 250 feet is represented by the coal beds and interstratified clays, silts and sands. Strata dip to the southeast at 25 feet per mile or less and trike northeast. Large areas underlain by coal seams at shallow depths are delineated. Reserve calculations are dependent on detailed information on seam thicknesses and feasible stripmining depths. The stratigraphically higher seams are thinner on the average than lower seams and this, together with the increase in elastic size fractions in higher strata, suggests a retreat of a Tertiary marine margin to the south during the closing depositional history of coal seams and associated strata."

Jan 1, 1972