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By Robert B. Parsons

"The February 18, 1987, Federal Budget contains a proposed amendment which would simplify somewhat the ""successor corporation"" rules in the Income Tax Act. Despite this amendment, though, the important successor rules will continue to be relatively complex.IntroductionThe February 18, 1987, Federal Budget papers propose an income tax amendment whereby the so-called ""successor corporation"" rules would be revised by removing the present provision which limits the application of these rules to a maximum of two ""successions"". The successor corporation rules represent one of the most complicated sets of rules in the Income Tax Act. This month, Tax Notes seeks to explain these rules and the proposed amendment in simplified terms.Basically, the successor rules provide a mechanism for transferring unused exploration and development expenses from one taxpayer to another , in specified circumstances. The aforementioned limitation of two successions refers to the rule which allows a maximum of two such transfers with respect to any particular pool of deductions."

Jan 1, 1987

By V. Schenk

Dust exposure resulting from the exploitation and winning of natural resources below ground has presented a serious health problem since the beginning of mining. The boom phase of the German hard coal mining industry after World War II with at times up to 500,000 employees saw an increase of dust exposure of miners below ground as the mechanization of road heading and mining increased significantly. More and more miners were diagnosed with coal-workers-pneumoconiosis (CWP), a chronic and irreversible lung disease resulting in a significant impairment of pulmonary function. This realization led to a reduction of CWP in the German hard coal mining industry in the 1960s. The successful fight against CWP began with the introduction of technical dust prevention measures. By infusing the coal seam with water before mining, sprinkling and spraying of heading and mining machines as well as canopies with water, aspiration in places with high amounts of dust and the suppression of dust with chemical substances it is possible to significantly reduce the miners? dust exposure. All operating points below ground are checked and measured regularly with regard to dust exposure. Through the combination of these values together with the individual shift data a relatively precise profile of individual dust exposure can be obtained. This profile allows the targeted work assignment when certain predetermined limits have been reached, moving the miner to a work place with less dust exposure and thus reducing the chronic dust exposure. The state of health of the individual is known because since about 60 years ago extensive occupational health checks have been carried out regularly at least every two years which means that work restrictions can be imposed depending on the findings. Since the beginning of the 1980s more value has been attached to not only situational but also behavioral prevention. Given the comprehensive provision of protective masks, having a protective effect as well as the required comfort when being worn, each miner has the opportunity to protect his respiratory organs depending on the specific dust exposure. Through a combination of all these measures the German hard coal mining industry has succeeded in beating the classic coal miner?s disease CWP. For mines in the Ruhr valley this means that a miner who started work after 1978 will no longer develop CWP.

Aug 1, 2013

By A. Galibois, R. Singhal

"This paper highlights some of the potential application areas of knowledge-based systems in the mining industry. The basic theoretical principles associated with knowledge-based systems are discussed and the justification for mining applications is given. The paper concludes with a brief description of a prototype knowledge-based system applied to scraper selection that was developed at Université Laval on a LISP machine. IntroductionThe beginning of Artificial Intelligence coincided with the conception and development of the first computer systems some thirty years ago. At that time researchers were euphoric about the possibility of modelling the human reasoning process. Soon, however, they discovered that the combinatorial aspect of the set of possible solutions to a particular problem did not permit an in-depth evaluation.In the mid-60s researchers started to look at the heuristic approach because it was more suited to human behaviour with its congnitive abilities (i.e. representing, reasoning, problem solving and advising). The heuristic approach allows possible results rather than exact solutions and it is more rapid and cost effective than the exhaustive combinatorial analysis. The heuristic approach did allow some noticeable progress in the seventies with the development of the first expert system called MYCIN with the objective of diagnosing blood infection diseases."

Jan 1, 1988

By Lawrence Devon Smith

What is a Failed Project? For mining projects, some key indicators of a ?failed? project are: ? Cost is more than it should be (particularly capital) ? Schedule ? It takes longer to build than expected ? It takes longer to ramp-up than expected ? It does not do what it is supposed to do ? Poor performance; output, product specifications; ? Low revenue ? High costs ? No one is happy about it: Management, Shareholders, Bankers ? Does a project fail if it does not meet expectations that were unrealistic and unattainable? ? Caution: Failure may not become evident until years later

May 1, 2010

By P. E. Cavanagh

Abstract Many investigators have been interested in developing some non-destructive method for detecting or determining the changes in physical properties in steel occurring during endurance tests or normal service life of a part which fails in fatigue. This paper presents a broad discussion of some of this work and the possibilities of developing useful test procedures based on some of the information obtained in the past. Changes in magnetic properties, electrical resistance, damping capacity, X-ray diffraction patterns, and remaining fatigue life at load different from service load have all been investigated as possible means for following the sequence of events during fatigue failure. In some special instances, tests such as these may be used to predict fatigue failure. As an in stance of practical application of the continuous determination of changes in magnetic properties during fatigue, a brief account is given of work done in non-destructive inspection of mine hoist-rope. As a result of extensive experiments and field crisis, it has been found possible to detect the beginnings of failure in a wire rope in service. The test method used will detect plastic deformation in a wire rope, no matter what its cause. There is no possibility of determining the remaining useful life of a rope by calibrating changes in magnetic properties in terms of remaining fatigue life. A change in magnetic properties at a point in a rope may indicate a decrease or increase in fatigue life, depending on the overload history of the rope. A continuing change in magnetic properties ac a point, however, does reliably indicate a developing weak point which will eventually lead to failure. The important point about any change in magnetic properties is not the magnitude of the change, but whether or not it continues.

Jan 1, 1947

By G. A. Sutton

This paper, describes a case example from San Manuel mine, where in situ copper leaching of the supergene zone was done over a 14 year period (1986–1999) in conjunction with underground and open-pit mining operations of a copper porphyry deposit. In 1993–1994, testing of well fields was done to determine the amount of copper that would be recovered from in situ leaching of the supergene zone, which was composed primarily of chrysocolla and copper-clay minerals. It was determined that the leach fluid would reach 70% (‘sweep efficiency’) of the copper minerals and that 75% of them would be leached for a recovery of 52% of the acid soluble copper. However, the final results from Zone 6, which had the longest leach history, showed that approximately 42% of the acid soluble copper was recovered, indicating that the `sweep efficiency’ was closer to 55%. Comparison of drill-core assay data from two holes, one drilled before (ARM158) and the other after (SMO9607) leaching, also indicate that approximately 42% of the acid soluble copper was recovered. The discrepancy between the predicted (52%) and actual (42%) recovery is probably related to a combination of factors, including difficulty in maintaining fluid saturation, channeling effects and gypsum precipitation. INTRODUCTION In situ copper leaching at the San Manuel mine, Arizona, was initiated in 1986. It was recognized that some of the copper oxide resource was not going to be economically recoverable by conventional open pit and heap leach methods using solvent extraction and electrowinning (SXEW). A high stripping ratio would be required to access part of the resource. At the time, in situ leaching was becoming popular in the uranium industry but the approach was virtually unknown in the copper industry, especially not at a large scale.

Jan 1, 2019

By Kosta Fytas, Nour-Eddine Chaouai

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

Jan 1, 1991

By V. S. Sastri, G. R. Doey, R. W. Revie

"Different forms of corrosion, the various corrosive environments encountered, the mining equipment subject to corrosion and the methods to control corrosion in the mining industry are briefly reviewed along with the savings that could be achieved by corrosion control. IntroductionCorrosive conditions in mines and metallurgical plants, lead to deterioration and wastage of equipment and of materials. The cost of corrosion in the mining industry can be significant, and measures to minimize corrosion must be taken to reduce this cost(l-3). Although the data in Table I are twenty years old they indicate the significance of corrosion costs in four industrialized countries. The costs of corrosion in the U.S. metallic ores sector and in the Canadian mining industry are presented in Tables 2 and 3, respectively. Significant savings in the mining industry can be achieved by using corrosion control methods. For example, corrosion in the Canadian mining industry in 1991 cost $1460 million of which $97 million was avoidable. Indirect costs of corrosion associated with plant shutdown, lowered efficiency of equipment and overdesign are additional to the direct costs cited here."

Jan 1, 1994

By L. J. Visentin, J. G. Rickaby

"Audiometric testing is a key element in hearing conservation in the mining environment. This paper gives the history of the audiometric testing program carried out by Inco Metals Company, including the program objectives the personnel and equipment involved, calibration and testing, the test procedure, and the classification and evaluation of the test results.IntroductionThe operations of the Ontario Division of Inco Metals Company are located primarily in the Sudbury District. They also include a refine ry at Port Colborne and a mine and concentrator at Shebandowan near Thunder Bay.The company operates nine underground mines, and one open pit, while maintaining six underground mines on a standby basis. Ore from these operations is processed in four concentrators. The metallurgical facilities include a smelter, a matte processing plant, a copper refinery, a nickel refinery and an iron ore recovery plant at Sudbury, and a nickel refinery at Port Colborne. Inco Metals currently mines roughly 9,000,000 tons annually and produces IS elements.Excessive noise in the work place has been a serious problem in the mining industry since the introduction of compressed-air-powered machinery in the last century. At the same time, growing levels of noise inherent in our social environment can threaten the hearing of employees and their families.Only in the last 20 years, however, has the extent of this problem and its implications for people working in the industry and their families been recognized. Since the industry has become aware of the situation it has taken steps to implement comprehensive noise reduction and hearing conservation programs."

Jan 1, 1982

By D. Purdie

"This paper aims to remind researchers, designers, operators, and managers about the benefits of seeding in the design of precipitation stages in their flowsheet. Including a high density solids (HDS™) process encourages the precipitating solids to form on the surface of existing precipitated particles. This paper discusses the application of the HDS technology at Kennecott Smelter, where the authors have witnessed significant improvements in settling and filtration rates. The authors have also applied this technology at various smelter bleed treatment plants worldwide with similar improvements in precipitation and filtration rates. HDS is a registered trademark of De Nora Water Technologies. RÉSUMÉ Cet article a pour objectif de rappeler aux chercheurs, aux concepteurs, aux exploitants et aux administrateurs les avantages de l’ensemencement dans la conception des étapes de précipitation de leur schéma de traitement. L’introduction d’un procédé des boues haute densité (procédé HDS™, de l’anglais high density sludge) encourage la formation de substances solides précipitantes à la surface des particules précipitées existantes. Cet article porte sur l’application de la technologie HDS à la fonderie Kennecott, où les auteurs ont observé des améliorations importantes au niveau de la vitesse de sédimentation et de filtration. Ils ont également appliqué cette technologie à diverses usines de traitement des rejets liquides des fonderies dans le monde entier, et ont constaté des améliorations similaires en termes de vitesse de précipitation et de filtration. Le procédé HDS est une marque de commerce déposée du fabricant De Nora Water Technologies.INTRODUCTION In 1966, the lead author worked as an assistant smelting metallurgist for the Tsumeb Corporation Limited copper and lead smelter in Tsumeb, Namibia. The smelter produced copper and lead, as well as cadmium and arsenic trioxide as byproducts. The cadmium was concentrated in the lead blast furnace off gas dust, and was collected by a baghouse. The baghouse dust was leached with dilute sulfuric acid (H2SO4) in a batch process. The iron and arsenic in the solution were oxidized with potassium permanganate (KMnO4) and basic ferric arsenate (BFAS; Fe(AsO4)x(SO4)y(OH)z·wH2O) was precipitated using milk of lime. The cadmium was cemented from the purified solution using zinc dust."

Jan 1, 2018

By E. H. Holm

"This paper is a market-oriented review of the industry's present and forecasted performance, considering some of the principal factors influencing natural resource development. The author illustrates the steady consumption growth of nickel, and stresses the need for a quantitative long-range approach to production, consumption and the supply/ demand balance on a worldwide basis. Objective consideration of this data exposes some popular misconceptions. The possibility of near-term undersupply of nickel is discussed in relation to historically rapid changes in inventories and demand patterns. What is the significance of the increasing reliance on lateritic sources? New• facilities, new processing methods and new product forms are illustrated as further evidence of the industry's determination to satisfy the needs and preferences of nickel consumers. Examples indicate how product forms must accommodate to fast-evolving end-use technology. A review of nickel's price performance is used as a base from which to explore tomorrow's price trends."

Jan 1, 1972

By D. A. Barr

"Most of the lode and placer gold production in the Canadian Cordillera has been derived from mines and placers in the Intermontane and Omineca belts. Gold has been produced from rocks of Precambrian to Eocene age, but the preferred host environment contains Upper Paleozoic to Upper Jurassic eugeosynclinal or arc-type sedimentary and volcanic rocks adjacent to plutonic complexes which have a wide variety in both size and composition. Auriferous quartz lodes occur in fissures and shear zones which are commonly subsidiary to strong fault zones. In common with most vein-type deposits, structural complexities are an essential part of the mine environment.Gold production from the Canadian Cordillera to the end of 1978 totals 35.0 million ounces, of which 47 per cent has been produced from placer mining, principally in the Klondike and Cariboo districts. The balance has been derived from lode gold (80 per cent) and base metal (20 per cent) mines.Gold reserves in producing mines and deposits committed for production as of January 1, 1978 were 87.4 tons, or 21.6 per cent of total Canadian gold reserves contained in all types of deposits. Although more than 100 lode mines have operated in the Canadian Cordillera since the turn of the last century, over 75 per cent of the lode gold produced by 1978 was recovered from five mining camps, namely the Rossland, Hedley, Bridge River, Premier and Barkerville.The average grade of the principal producers in these camps was about 0.45 ounce of gold per ton. Individual camps yielded from 3 to 8 million tons during their operating lives, which varied from 28 to 43 years. The last of these mines ceased operating in 1971.Most of the total lode gold production has been derived from quartz veins, frequently with associated carbonate and ankerite, occupying fractured and faulted zones in Mesozoic volcanic and sedimentary rocks closely associated with a variety of intrusions. A review of the literature suggests that several deposits may have evolved by remobilization of ore constituents from earlier concordant gold-bearing formations. The principal metallic minerals in the deposits are native gold, electrum, tellurides, pyrite, arsenopyrite, pyrrhotite, sphalerite, galena and chalcopyrite.As the mineralogy suggests, many of the Cordilleran lode gold deposits have yielded important co-products or byproducts, including silver, copper, lead, zinc, cadmium and tungsten. Significant by-product gold production has also been derived from porphyry copper, volcanogenic, replacement and pyrometasomatic deposits, particularly in recent years.No major lode gold discovery has been made in the past 67 years, although little exploration activity for gold has taken place during the last 30 years. Several relatively small lode gold and gold replacement deposits have been discovered in recent years, either serendipitously (Chappelle) or on very low initial budgets (Northair and Carolin). Based on well-established precedents, one or more of these may eventually be developed into a large mine.A detailed study of the Canadian Cordillera gold deposits based on recent genetic models could prove rewarding, not only in up-dating information on their origin and depositional characteristics, but in stimulating the search for undiscovered gold deposits, in the Cordillera and other parts of Canada."

Jan 1, 1980

By P. Woo, N. Brodusch, R. Gauvin, H. Demers

For developing new technologies, it is important to characterize the microstructure of materials with high spatial resolution at the nanoscale. To achieve high resolution, field emission scanning electron microscopes (FE-SEM) were developed. These microscopes allow working at low accelerating voltage, below 5 kV, to take advantage of the reduction of the interaction volume with accelerating voltage. Furthermore, their higher gun brightness compared to conventional thermo-electronic emitters, allow a probe size at the nanoscale. At low accelerating voltage, the emission volume of backscatter and secondary electron (SE) of the type II signals approach that of SEI signals. However, it is not enough to reach the highest resolution. A magnetic field above the sample improves the spatial resolution by collecting mostly high-resolution signals. In addition, the energy-filtration of the electron signals allows selecting the type of contrast detected: topographic, compositional, or crystallographic. The development of these new technologies permits to extend the imaging capabilities of the SEM towards new nanoscale applications.

Jan 1, 2014

By J. Boulton

"Nuclear energy is an established and proven energy source. Today, CANDU-PHW nuclear-electric generating stations produce over one third of Ontario's total electrical supply: safely and economically. In many parts of Canada, where economic hydro resources do not exist or are fully developed, coal and nuclear energy are the only alternatives for future large-scale electrical generating capacity.Recent analyses have suggested that, in the f ace of increasing energy demands and decreasing reserves of hydrocarbon fuels, Canada must depend on electricity to provide an expanded fraction of its energy budget. Nuclear energy is likely to play an increasing role in the generation of electricity; there are also potential applications as a supplier of process heat in industry and in the in-situ recovery of bitumen fro m tar sands.The future supply of nuclear fuel, reactor safety and radioactive waste management are briefly discussed. In each case, the benefits to be gained from a controlled expansion in the use of nuclear energy outweigh any uncertainties which may exist."

Jan 1, 1981

By M. K. Aly

"ABSTRACTThis paper briefly describes the mining method proposed for the iron ore deposits in Wadi Shatti, western Libya. The iron ore produced will be used in the steel plant at Misurata on the Mediterranean coast. GeologyThe Wadi Shatti is located in the central part of western Libya. Flat iron-bearing sedimentary rocks are exposed with remarkable regularity in this valley. It occupies an area 200 km long by approximately 20 km wide trending in an eastnortheast direction between Jabal Fazzan in the north and Zel1af Sand Dunes in the south (Fig. I). Only a part of this valley has been ful1y explored by drilling on a 400- by 200-m pattern in an area of 18 km2 south of the town of Taroot. Farther to the south, no exploration by drilling can be done due to the presence of sand dunes .The iron-bearing bed is about 10to 15m thick, with a dip of 2 to 4 degrees in a southerly direction . The overburden consists mainly of clayey sandstones, 4 to 5 m thick, in the northern part, increasing to 35 m in the southern part. The iron ore bed consists of three different layers, from the floor upward: (1) Lower Reduced Ore (LRO), having a varying thickness of 1 to 7 m; (2) Magnetic Ore (MO), with a thickness varying from 4 to 12 m mainly in the central part of the area; and(3) Upper Reduced Ore (URO), with a bed thickness varying from 0 to 7 m."

Jan 1, 1980

By W. A. Green

Introduction While pilot-mill operations were being carried on at Flin Flon, as described by R. E. Phelan (1), a detailed topographic map was being made of the area in the vicinity of the ore-body for later use in laying out plans for the final plant. The area covered by this survey was 6,600 feet by 6,600 feet, with contours on 2-foot intervals. As mentioned by Mr. Phelan, it was definitely decided at the end of November, 1927, to take up the option on the Flin Flon property and to proceed immediately with the plans for construction of a metallurgical plant at Flin Flon to treat 3,000 tons of ore per day, and of a hydro-electric power plant at Island Falls, Saskatchewan, to supply power for the future operations at Flin Flon. Railway Built From The Pas to Flin Flon Just as soon as the decision was made to go ahead with the construction work and opening-up of the property, it was of course essential to give immediate attention to the building of a railway to the mine. Many years previously, a preliminary survey had been made for a railway to branch off the Hudson Bay railway at a point 4.7 miles northeast of The Pas, and, during certain negotiations in 1925, the Provincial Government of Manitoba had agreed to guarantee the railway bonds necessary to finance the building of the line, so that it was possible to organize for this work immediately. A contract was let by the newly organized Manitoba Northern Railway Company to the Dominion Construction Company, Ltd., and Tomlinson, for the building of the railway to the mine, a distance of approximately 87 miles (see Figure 1). The Manitoba Northern railway is a subsidiary to the Canadian National railway, and all engineering and supervision of the contractors was done by the Canadian National engineers. Actual construction work was started in January, 1928. The first 52 miles of the railway from The Pas to Cranberry Portage is over fairly level, although slightly rolling, country, and a considerable portion of the route is over muskeg area. Rails were laid on top of the frozen muskegs. Gravel deposits were opened-up along the line and, before warm weather; sufficient ballast .was distributed in the muskeg areas to prevent thawing under the track, and thus give the necessary support to allow uninterrupted transportation over the line.

Jan 1, 1935

By T. Alan O'Hara

"The decision to invest capital in developing a mine and constructing a mineral processing plant and services is usually made after a feasibility study shows 'that the estimated future cash flow from mine operations will yield an adequate return on the estimated capital expenditures.The actual return on investment may differ substantially from that estimated in the feasibility study, because of the probabilities of errors in estimating capital costs, ore reserves, operating costs, mineral revenue and operating productivity. This paper outlines the R.S.S. (root sum of squares) risk analysis procedure of computing the overall probability of the actual project D.C.F. (rate of discounted cash flow), differing from that estimated in the feasibility study.Variation in Project D.C.F.It is assumed that a feasibility study of the project has been completed which has defined the estimated values for all the project parameters, such as ore reserve tons and grade, capital cost, concentrate recovery, metal revenue, daily milling capacity and operating costs.The financial analysis of the mining project will have determined that the cumulative cash flow will yield an expected D.C.F. on the capital cost if all project parameters attain the estimated values. If, however, the actual value of any parameter varies from that estimated, the actual project D.C.F. will vary from the estimated D.C.F. Risk analysis methods attempt to determine the overall effect of probable variations in the estimated values of all project parameters on the D.C.F. of the mining project. This overall effect is expressed as a probability profile, which shows the likelihood of actual D.C.F. values greater or less than that estimated.Thus, a completed risk analysis of a mine project, with an expected D.C.F. of 15.51%, would display the characteristics shown in the preceding diagram."

Jan 1, 1982

By I. Osvath, I. Gombköto, G. Mucsi, Z. Molnár

"In the present research, a deposited brown coal fly ash was used as raw material for geopolymer. The reactivity of the fly ash was altered using mechanical activation, which is one of the promising methods to improve bulk and surface reactivity. The mechanical activation experiments were carried out in a high energy density mill using 5 m/s circumferential speed, and various residence times (1, 3, 5, 10, 15 and 60 min). The effect of mechanical activation on particle size distribution was measured by a laser particle size analyzer and structural changes using FT-IR. Geopolymer samples were prepared from mechanically activated fly ash with an alkali solution. The progress of geopolymerisation was monitored using an Isothermal Conduction Calorimeter. The heat flow curve obtained indicated that reactions were more prominent and started much earlier in the mechanically activated samples. This observation is further supported by the compressive strength results which also improved in geopolymers using mechanically activated fly ash. Based on the obtained results, it can be inferred that mechanical activation is a possible way to enhance the reactivity of fly ash and consequently properties of resulting geopolymers.INTRODUCTIONCoal fired power plants generate fly ash and slag in huge amount worldwide, about 780 million tons/year (Heidrich et al. 2013). Due to the relatively low utilization rate, enormous quantities of these wastes are landfilled in ponds. The fly ash is the finest grained particle fraction of the solid ash, which is transported with flue gas, and removed by electrostatic or bag filters. The fly ash has pozzolanic activity, it does not react with water, but in the presence of calcium hydroxide solution hardens and solidifies, producing a reaction product practically insoluble in water (Opoczky, 2001). The most important property of the fly ash regarding geopolymerization is its reactivity, which depends on the chemical and phase composition, the dispersity (specific surface area, particle size distribution), and the morphology of the fly ash particles, and determined by the physical properties and chemical composition of the fly ash. Geopolymers concerning their chemical structure are polysialates, where the sialate (silicon-oxoaluminate) network is built up from the bonds of Si-oxide and Al-oxide by sharing oxygen atoms (Davidovits, 1988)."

Jan 1, 2016

By W. B. Morrey

"In recent years, the major effort in detonator development has been concentrated on ""non-electric"" systems. Existing types all involve some form of explosive reaction to transfer ignition energy from outside the borehole to the pyrotechnic delay element contained within the detonator. These may be based on low-energy detonating cords having grained or plasticized explosive cores, shock tube energy transmission principals and explosive gas ignition systems. Each has properties of internal and external effects not present in electric conductors.The MAGNADET System introduces transformer coupling into electric blasting circuits. Safety features with respect to current leakage, stray currents of AC or DC source, electrostatic energy and radio-frequency radiation are comparable to ""non-electric"" systems, with advantages in simplicity, speed of hook-up and range of application.The transformer device used is a small ferrite ring or toroid which is an integral part of each specialized detonator. The detonator legwires form the secondary side of the transformer winding. The primary side is a single wire loop common to all units within the circuit. Power is supplied from a frequency-tuned portable exploder with unique circuit-sensing features.The MAGNADET System is expected to have particular application to shaft sinking, raising and tunnelling where the protective features as well as speed and efficiency are critical factors. Applications of the 'MAGNA' booster in quarries, open pits and longhole deck charges offer control over vibration problems and elimination of surface noise.IntroductionFor many years, electric detonators and electric blasting systems dominated surface and underground applications where controlled delay times were required. Control over the instant of detonation by blasting machines or power-line switches is the major safety feature.Electrical energy exists in many forms. It may originate from many sources. Electrical energy can be difficult to contain. It may enter or escape through a variety of conductive paths. It may fluctuate, concentrate or dissipate to pose a most elusive potential hazard."

Jan 1, 1982

By Phil Molloy

"In March, 1968, Skega Ruh her Liners were used to reline the shell of an 8' x 12' Allis Chalmers ball mill.This mill is used to regrind the cyanided pulp from 58i -200 mesh to 92% -200 mesh prior to this pulp passing to the flotation circuit, at approximately 450 tons per day.Before the use of rubber liners, the regrind ball Mill shell had been lined with single wave ni-hard liner!'. These liners had an average life of five years. Ni-hard end liners were used both prior to and during the use of rubber liners, as the life of the ni-hard end liners was about seven years, and it was thus felt that little economic benefit would be realized by lining the ball mill ends with rubber.The rubber lining used has a thickness of 57.15 millimeters and the square shaped lifter bars which are spaced at 14~ inch centres, have a 4"" x 4"" cross-sectional dimension.With the use of ni-hard liners, the consumption of 1 1/4 forged steel balls averaged 1.062 pounds per ton, Using rubber liners the consumption of l~"" forged steel balls increased to 1.368 pounds per ton. Also the level of the ball load which previously had been kept at approximately 18 inches below the mill discharge, had to be increased to approximately 8 inches below the mill discharge in order to effect the same grind.The initial gri4ding performance of the newly relined mill was also poor, until the leading edge of the rubber lifter bars, which were square shaped in cross-section had been worn to a rounded profile. These lifter bars were replaced after 4 years and 3 months of operation.The advantages of rubber liners in our opinion is as follows:"

Jan 1, 1974