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By D. M. Avant, A. J. Solomon, S. M. Pickering, W. R. Fox

Introduction Most high purity silica is produced from crystalline quartz, generally from sand. However, there is a small area of southern Illinois where a porous, friable white chert rock is found that is very different in physical form from quartz sand. This microcrystalline material, commonly referred to as tripoli, is more easily ground to micron sizes than sand. Although of similar Moh's hardness, microcrystalline tripoli is less abrasive than either ground quartz sand or many synthetic abrasives. Location The southwestern corner of Illinois is underlain by extensive deposits of very porous chert; in some places the material is quite white. Two companies, Illinois Minerals Co. and Tammsco Inc., mine and process this white material. The Illinois Minerals plant is located at Elco, and the Tammsco plant is in Tamms, IL. Both companies mine from various locations within a 10-mile truck haul of their plants. Production from this district has been continuous since at least 1915. Malvern Minerals Co. mines and processes a generally similar microcrystalline, friable novaculite near Hot Springs, AR. Geology The southern Illinois white tripoli area is on the southern flank of the Illinois Basin. The commercial silica zone is a facies of the Clear Creek chert of Lower Devonian Age. To the north, where it occurs deep in the basin, the Clear Creek is a siliceous limestone. In the mining area, thin overburden has allowed access by surface ground water, which has leached away the carbonate content and left a quite pure silica residue. Fossils characteristic of sea bottom deposition, such as brachiopods and trilobites, are occasionally encountered in mining. The structure of the mining area is poorly known, due to infrequent outcrops. Strata in most mines are inclined at dips of 5° to 20°. There appear to be occasional high angle normal and reverse faults, but these are seldom of any significance in mining. The friable white silica zone mined in the Clear Creek chert is overlain by dark brownish-red chert and siliceous shale. Exploration drilling to date has not encountered the base of the microcrystalline tripolitic zone. Chemical content Leaching by ground water solution has removed virtually all the carbonate from the original siliceous limestone. Impurities encountered are red to yellow iron oxides, aluminous clays, and occasional black manganese oxides. The silica has no detectable formula water. A typical chemical analysis and physical properties are listed in Tables 1 and 2. Mineralogy and crystallinity Southern Illinois friable tripoli appears amorphous under the polarizing microscope. No crystal structure and only occasional, vague, patchy anisotropism is evident. However, the material gives an excellent quartz X-ray diffraction pattern. Thus, so far as X-ray mineralogy is concerned, the material is clearly

Jan 12, 1986

By A M. Ebbels

"Underground mine scheduling decision-making has been based on production requirements, equipment productivities and the mine planner’s instincts on the best scheduling strategy for the mine to optimise the net present value (NPV) of a project.In the last few years, innovative software has been developed to optimise underground schedules based on NPV. The schedule optimisation tool (SOT) allows the user to set up scenarios based on grade, metal content, capital and operating costs.This paper discusses the results of two case studies undertaken using the SOT software to optimise the NPV of the projects.In each case study, the SOT software has been applied in two ways:using the original mine planner’s scenario and determining whether the NPV could be improved by changing resource capacitieschanging the scheduling goals to determine whether a different mining strategy would have a better NPV outcome.The outcomes of the case studies demonstrate that the mine layout and design were contributing factors to the overall improvement of the NPV and that SOT has a more noticeable impact on the NPV of projects where less sequence constraints are required, such as geotechnical sequencing and access development.CITATION:Ebbels, A M, 2016. Optimising underground mining strategies, in Proceedings Project Evaluation 2016, pp 60–65 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By Serge Rudchenko

A study to determine the potential use of retaining structures in open pit backfilling. Research and review of the open pit mine environment, mine waste disposal, and past and current use of retaining structures. A development of specific structures, the culvert/ tunnel concept, and an anchor block retaining concept. The cost benefit of retaining structures used for in-pit backfilled waste.

Jan 1, 1981

By R. W. Stahl

A survey of firefighting facilities and practices in coal mines conducted by the Bureau of Mines3/ showed such variations in equipment and apparent attitude toward fire protection that a comparison with other industry seemed advisable. Although other industry is confined generally to surface operations and the hazards probably are not as great, the same general methods of extinguishment are employed, so that the cost and protection at least should be comparable. An investigation of industry other than mines revealed a generally greater emphasis placed on fire-combating equipment, fire-brigade training, fire-fighting facility inspection, and fire-hazard elimination, as well as a greater average expenditure for fire protection.

Jan 1, 1959

The day after I reached New York, on January 30th, John Ryan of Anaconda told me where they wanted me to go. Late in 1916 the Russian Czar, desperate for money and supplies with which to carry on his unhappy share In the first World War, sent emissaries to the United States to see if our great mining companies might be interested in trying to find mines and to bring them to production in the millions of acres of the Imperial Estates in Russia and Siberia. It looked like a long chance as no one knew whether or where there might be important ore bodies. Even if they found them it might be a hopeless task to equip them under wartime conditions But the American copper companies had plenty of money and they were used to taking risks. They made a supersecret agreement with the Czar's deputies to send an exploring expedition to Russia at once I never learned the names of the other companies but Anaconda was to man- age the venture. Horace Winchell, then the leading mine geologist In the United States, was to be in charge of operations. Charles Janin, an eminent placer and dredge expert, was to study chances for producing gold and platinum. Though at 33 years of age I was much younger than the others, I was chosen to hunt for copper and other valuable metals. Charles Boynton, a business man who had lived in Russia and had married an attractive Russian woman, was to join the party and carry on any necessary financial or diplomatic affairs. He had gone on ahead to arrange for our reception Finally a graduate student from Ann Arbor named Steinberg was to go along as Interpreter. We soon found out that if his Russian was no better than his English his interpretlng couldn't be trusted too much I knew nothing about the millions of square miles In Russia and Siberia, and even less about what mineral deposits might be found, but I was delighted at the prospect. I was treading on air for the few

Jan 1, 1976

By Alan R. Gadberry

To resolve drilling and blasting problems, rather than treating symptoms and allowing problems to grow, the mine operator needs to change the way he operates. When a mine operator discovers a drilling and blasting result that he doesn't like, it is easy for him to think of that disappointing result as a problem. More often than not, however, that result is only a symptom of a problem, and the real, underlying problem cause can be seen when the operator looks in the mirror. Symptoms and problems relating to drilling and blasting are resolved when the mine operator makes appropriate changes in the way he manages his operations.

Jan 1, 1985

By A A. Puhalovich

The placement of chemically reactive mine wastes in mined out pits (æpit backfillingÆ) is increasingly seen by industry as best practice to manage long-term environmental risks. This is primarily because leaving wastes at the surface, or allowing pit lakes to develop, can result in unacceptable environmental risks. The costs and practicality of mitigation options such as installation of covers and community expectations of landform re-construction to achieve a post-mining, beneficial land use are also important drivers for pit backfilling.Pit backfilling can significantly reduce the post-closure risks to receiving environments, by minimising seepage due to tailings, acid/solute generating waste rock and/or salts derived from mine water treatment. Environmental risks are often highest where wastes are located close to the ground surface, due to relatively high rates of groundwater movement in near-surface aquifers and/or failure of engineered structures due to rainfall/erosion processes. Placement of these wastes at significant depth in pits, subject to mine planning and environmental assessment, can address these risks by increasing the path length and resistance from contaminant source to receptor, thus enhancing encapsulation of the wastes.Pit backfilling can also be cost-effective for mining companies. This is because existing pits are developed on the basis of an economic return and thus provide an opportunity to store tailings in an existing æengineered structureÆ at little or no incremental cost when compared with building and operating a new tailings or waste rock storage facility, often encompassing complex cover/drainage management systems. Key issues for consideration are mine planning, the long-term geotechnical behaviour of the wastes (eg consolidation of tailings which leads to release of acid/solutes in tailings porewaters), seepage rates to downstream receptors/agreed end point criteria and potential resource sterilisation. Internationally, mine closure guidelines are also showing a greater recognition of pit backfilling in the context of allowing mining companies to meet agreed post-closure land use objectives.In summary, pit backfilling can enhance the encapsulation of chemically reactive mine wastes and environment protection, and with agreement on post-closure beneficial land use, can also help to deliver post-closure benefits to communities.CITATION:Puhalovich, A A, 2012. Pit backfilling - Managing chemically reactive mine wastes and achieving rehabilitation objectives, in Proceedings Life-of-Mine 2012 , pp 279-286 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By George J. Simchuk

The selection of a stripping method and subsequently, the stripping equipment, are two of the most important decisions confronting a project engineering staff during the initial feasibility study of a new coal stripping operation. The selected stripping units average from 60 to 70 percent of the total capital outlay for mine equipment and their selection will affect the type, size, and quantity of the attendant equipment, such as loading shovels, drills, haulage trucks, and bulldozers. This paper is intended to report on an in depth study by Utah's Technical Services Staff regarding the selection of stripping equipment for the Goonyella Coal Mine in Queensland, Australia. We will touch briefly, on the objectives considered in this selection; the various alternatives which were explored; the general assumptions that were followed throughout the engineering and design of an appropriate stripping system; and computations necessary to determine the amount and size of stripping equipment. INITIAL EXPLORATION Utah Development Company (presently 90% owned by Utah Construction & Mining Co. and 10% by Australian investors) commenced systematic geological studies of the Bowen Basin coal fields of Central Queensland in 1961. The Blackwater Mine as shown in Figure 1 has since been established in this area and is now producing 3.0 million tons per annum of washed coking coal. Geological reconnaissance was then extended to the northern part of the Bowen Basin and in 1963 Utah's coal prospecting area covered 2444 square miles of Central Queensland. The authority to prospect north of Blackwater has since been trimmed to 810 square miles by relinquishments to the State.

Jan 1, 1971

By Oliver Bowles

The Bureau of Mines issued three Information Circulars on marble many years ago (5), (6), (7).2/ They have long been out of print; furthermore, conditions have changed considerably in the industry in succeeding years. A presentation of current data is therefore desirable. This report furnishes general information on marble, including its properties, distribution of domestic and foreign deposits, methods and equipment used in quarrying and milling, economic and marketing problems, and recent advances in marble technology. INTRODUCTION Most marbles are crystallized limestone. The term "marble" is derived from a Greek word meaning to sparkle or flash, because the calcite crystals in marble sparkle as they reflect light. The word "marble" is employed frequently to mean a small ball used in the game of marbles with which nearly every child is familiar. Although the little spheres were originally of marble, few of those made in recent years contain that material; nevertheless, the expression "playing marbles" has persisted.

Jan 1, 1958

By L. Nell

Bateman, like other engineering contractors, carries out or participates in many studies of potential projects in the Minerals Industry. This paper aims to explain the contracting approach to feasibility studies as practiced by Bateman, particularly where this differs from a traditional mining company approach. A brief description is provided of the usual phases of a project and the types of estimate needed to proceed from one phase to the next. Possible organizational structures involving different forms of association between owner, contractor and consultants are then outlined. The bulk of the paper then demonstrates that the cost estimates prepared stem directly from the mining plan, metallurgical process design and engineering design philosophy. The steps to be followed in order to prepare a credible estimate which accurately reflects the design constraints are described. The importance and the methodology of carrying out value engineering and of preparing contingency estimates based on a thorough risk analysis exercise are then discussed. Financial modelling techniques are described briefly. The paper concludes with short summary case studies of two recent investigations of potential projects in Africa.

Jan 1, 1999

By Geo. E. Cole

A GREAT deal of time and energy is now being devoted to the study of post-war reconstruction and rehabilitation, in spite of the fact that as yet we have not won the war in which we are presently engaged. If you feel that the study of post-war problems takes our thought away from the problem immediately before us, you may well query, "Well! What has all that to do with winning the war, our most urgent problem today?" The answer has been given by Principal James of McGill University, Chairman of the Cabinet Committee on Reconstruction: "Reconstruction is something which must be thought of in advance, partly for the purpose of recognizing exactly the influence of war-time activities, controls, and regulations on the post-war Canadian scene. Many people are acutely interested in this great problem. It is not that they are not interested in the war itself, or epochal events that are taking place from day to day. They have a vision of that future which they hope will be Canada's, and this vision inspires them to even greater efforts at the present time". The trend of events would indicate that changes, economic and industrial, after this war will be greatly out of line with those that followed previous wars in history, for the present struggle has involved every nation in the world. In the peace that will come, every engineer will have a task in bringing the most desirable order out of the most distressing chaos. We certainly are living in a changing world; we are witnessing geo-graphical and economic readjustments that no other generation in world's history has ever witnessed. And there is an opinion gaining strength in our Dominion, as in other lands, that after this war we shall live in a world in which our process of thinking and our very way of life will have to undergo drastic changes to cope with the new order of things. Sadly our world of today has had to revise the sublime vision that nation shall not lift up sword against nation, while salvage operations continue to beat ploughshares into tanks and the peaceful pruning-hook into a weapon for the deviltry of the commando.

Jan 1, 1943

By Peter Zhang, Todd Minoski, Gabriel Esterhuizen, Jack Trackemas, Berk Tulu, Morgan Sears

Longwall mining is a highly productive and efficient coal mining method used in the USA. During longwall retreating, the belt entry must be maintained stable, and any roof fall in the belt entry would jeopardize mine safety and substantially interrupt the continuous production of coal in the longwall face. Past experience of longwall mining has shown that belt entry stability was the greatest challenge in longwall ground control, and the occurrence of roof falls in belt entries was largely associated with high horizontal stress. To properly support the roof in the belt entry, it is important to understand how longwall-induced horizontal stress changes affect roof stability in belt entries and to strategically install supplementary support to prevent any potential roof falls. Researchers from the National Institute for Occupational Safety and Health (NIOSH) performed horizontal stress measurements in the immediate roof of the belt entries for two Pittsburgh seam longwall panels oriented unfavorably to high horizontal stress. Hollow inclusion cells (HICells) were installed in the immediate roof at the intersection in each of the belt entries, and stress changes were monitored as the longwall face was approaching and passing the intersection. Numerical models were set up to calculate the longwall-induced horizontal stress changes in the roof at the monitoring sites. With the verified model, investigations were made of how horizontal stress is concentrated and relieved in the belt entry roof near the face under different panel orientations. Both measurements and modeling results showed that high horizontal stress is concentrated in the roof in the belt entry within about 15 m outby the face when a longwall panel is unfavorably oriented to the major horizontal stress. The study demonstrated that longwall-induced differential horizontal stress can be used as an indication of the degree of horizontal stress concentration. Roof support strategies are discussed on how to maintain the stability of belt entry under high horizontal stress concentration.

Jun 14, 2022

By Gaifeng Xue, Xiaohong Xu, Meng Liu, Yijie Song, Guotao Xu, Jixiong Liu

BN (Boron Nitride) based composites were prepared with hot-pressing by using h-BN as main material in ceramic preparation process. The relative density, bending strength, vickers’ hardness, thermal shock resistance, thermal expansion coefficient, thermal conductivity, phase composition and microstructure were tested and analyzed by using modern testing technology. The results indicate that the best formula is B, the relative density is 97%, the bending strength is 260 MPa, the hardness is HV5 343kg/mm2, the thermal expansion coefficient is 2.8×10-6℃-1, the thermal conductivity is 22 W/(m.K) and have no crack after thermal shock for 20 times by water cool. XRD analysis indicates that the main phase compositions are h-BN, β-Si3N4 and sialon. SEM studies show that the grains wrapped up by solid solution.

Jan 1, 2015

By Peter A. Allen

INTRODUCTION Lac Minerals Ltd., a significant North American producer of gold and other metals for over three decades, recently completed the financing for its third discovery in an eight year period. From 1975 to 1982, three important gold deposits in Quebec and Ontario: namely Bousquet, Doyon and Hemlo, were located and tested by company geologists. When current development plans are complete, Lac will have injected $400 million into these deposits. A discussion of these projects and their financing reveals some extraordinary challenges faced by top mining management. Responses to these challenges developed by Lac management may interest executives planning to proceed with new North American gold or base metal mines. MINE DE BOUSQUET In 1976, we explored a property containing a large low grade surface gold deposit. The geologial setting was exciting and we tested recent rethinking about the volcanigenic genesis of gold and base metal occurrences. These ideas helped pus to persist in drilling a nearby conductor and 600,000 ton, 0.22 ounce/ton orebody was outlined. With gold at $Cdn.150 per ounce the feasibility was approved and work started February 1978. Availability of a company custom mill 35 miles away reduced our immediate capital needs to $8.5 million. First of all, understanding the geological significance of results at Bousquet was critical. Mine and surface exploration geologists at Lac are continually and closely working together to better understand the nature of gold deposits in the Shield. This management emphasis on both pure and mine geology meant that a much larger ore reserve could confidently be predicted. (A proposal to quickly develop and ship the ore to a nearby company mine was discarded.) Instead of designing just for the initial plan of 500 tons per day we therefore included headframe, shaft and hoisting capacity for 1,700 tons and provided a compartment for future shaft deepening. These prebuilt additions were welcomed within two years. The type of collaboration whereby surface and mine geologists make study and field projects of each other's problems sets the foundation for this predictive ability. At Lac, the traditional responsibility for and supervision of the mine geologist by the mine manager is modified by this collaboration. This adds interest and scope to the geologist's work and lets him think beyond production requirements. Besides such management considerations, dedicated, professional geologists with integrity and lots of practical experience are needed to plan successful developments like Bousquet. Second, projecting future bullion revenue was critical and our experience selling production for future delivery gave us a way to ensure that loan repayment at term would not be jeopardized by falling metal prices. Output from a single mine is often reduced or curtailed for numerous reasons, so "selling forward" is done best and with least risk by companies like Lac with more than one or two producing locations for that metal. At first, a forward marketing program was considered unwise, speculative and unorthodox by analysts and other producers. Declining markets in the early 1980s prolonged gold project capital recoveries however, and critics were better able to appreciate the usefulness of such a tool. The notion that gold miners shouldn't sell forward is rooted in the belief that long-run gold prices will rise as modern social theory implementation in democracies inevitably erodes currency values. Selling against this trend goes against this industry belief or "ethic" and is at odds with the company shareholder who expects the gold price to rise not fall. Nonetheless, an efficient tool is available to the gold producer (not to most other metal producers) to quickly disengage from adverse price trends or to lock in spot prices instantaneously for two years or more of profits. Gold had recently retreated from U.S.$200 to $104 and now had reversed to $150. Lac had been forced to close several of its producers during the late 1960s because central bank-controlled

Jan 1, 1985

By Jr. Raleigh

Three run-of-mine bituminous coals, which ranged in rank from low volatile to high volatile A, were floated at nominal -28 mesh (590 µ m), -100 mesh (150 µ m), and -400 mesh (37 µ m) feed particle sizes with selected pyrite depressants and a dispersant. For the coals tested, pyrite and ash-forming minerals were usually rejected best at a -100 mesh feed particle size. Depressant additions tended to improve flotation selectivity between pyrite and coal. When joint dispersant-depressant systems were used at -100 mesh (150 µ m) feed particle sizes, the total sulfur content of the clean coal decreased further. For a comparable coal yield, less fuel oil collector was required for the flotation of -100 mesh coal than was required for the flotation of either -28 or -400 mesh feed.

Jan 1, 1990

By F. G. Heivilin

There will be 3 billion people moving into cities by 2050. Permitting is both the biggest obstacle and the biggest opportunity for mining. The problem is not if we have the right minerals, but how we can permit and produce it in a ?Sustainable? manner. A ?Permit? and a ?Sustainable Development Plan? may soon be the same thing. How do we produce the minerals we need with: 1. The lowest possible carbon footprint. 2. Social license from community outreach by being a catalyst and not a problem in a ?Green World.? 3. Enhanced water supply during all stages of production. 4. Meeting requirements of our customers for service, quality, & cost. How important is it to have a complete ?Sustainable Development Program?? First, no plan is complete!!! It is a work in progress subject to continuous improvement. We need to work together to get the results we want. The goal of the world communities is to become carbon neutral by 2050. What is the mining community?s goal? Do we have one???? When a Clorox, Colgate Palmolive, Wal-Mart, Toyota, or Caterpillar buys a product, what are your chances of getting an order without a good program in place? The answer is it will be difficult or impossible shortly and you will be requiring the same thing with your suppliers. This is an opportunity if you are in the lead and it soon will be a necessity for most mining and processing companies requiring much extra effort to catch up. For some mines it was a necessity to get most of the SD plan to get permitted. The number of companies in the extractive industries with a full Sustainable Development Programs is expanding rapidly as shareholder demands for transparency continue to grow.

Feb 27, 2013

By P. R. La Pointe, J. Clark

"Studies have shown that the roof in coal mines is nearly twice as likely to fail at intersections as at entries due to enlarged roof spans, stress redistribution and other factors. However, the relative stability of intersections in a mine varies, and an improved understanding of what factors impact roof instability can lead to efficient, proactive mining practices that both enhance stability and mining efficiency.A study was undertaken at an underground longwall coal mine to develop a model to predict the stability at the intersections of entries and cross-cuts. The statistical analyses relied upon observational and measured data regarding the development of tension cracks, seepage, intersection geometry, mining practices, geological attributes and geomechanical factors at 783 intersections. Each intersection was given a NIOSH roof. Common data mining techniques, such as multivariate linear regression, multinomial logistic regression, decision trees and probabilistic neural nets, were considered and evaluated to establish correlations and associations between stability and the other variables. Two of the more successful techniques were Decision Trees and Multinomial Logistic Regression. The analyses showed that a number of factors impacted stability:• Overburden thickness (impact on stress concentration magnitudes)• Initial opening area (impact on stress concentration magnitudes)• Sulfur content (depositional environment & impact of mechanical properties, leaching effects)• Intersection type (impact on stress concentrations)• Gob distance (impact on stress concentrations)• Presence or proximity of a particular sandstone (impact on mechanical properties)• Roof bolt type and diameter (impact on reinforcement)Some factors showed no statistically significant relation to stability. These included:• Total area• Supported areaSeepage was a more problematic variable in assess. Seepage is associated with instability, but it is not clear whether seepage occurs as a consequence of instability, for example, through the creation of tension cracks, or whether the intersection has been excavated where water already exists and has degraded the rock prior to excavation, leading to greater instability.Seepage appears related to the geology of the roof rock mudstones, not the sandstones. Tension cracks in the intersections occur preferentially where the Sulfur content is below 0.9%. The Sulfur may relate to mechanical differences in the roof rock, and where the Sulfur is low, the roof is less stable, there are more tension cracks, and seepage is greater. This suggests that the weaker mudstones may be more prone the development of tension cracks, not because these rocks are more brittle, but possibly weaker.2-way and 3-way intersections appear to have less seepage than 4-way, although very few intersections overall have any seepage. This is similar to the roof stability, in which the 2-way and 3-way are more stable. 2-way and 3-way intersections have fewer-than-expected tension cracks, while 4-way have more than expected. These results suggest that four-way intersections are weaker and more prone to tension crack development, also suggesting that increased seepage results from weaker roof conditions, rather than the converse. Thus seepage appears to be mostly a consequence of instability rather than a cause and is higher where there are 4-way intersections, mudstone geology and external loading factors like depth of cover and proximity to gob that promotes crack development. The study also indicated that a better understanding of the mudrock facies could reduce uncertainty."

Jan 1, 2015

By Keith Spence

"The notion of ""value"" has always been a subjective and contentious issue. Indeed, Value is in the eye of the beholder. There are varied methods and practices for valuing property, as there are industries in which they are applied. For example, there are ""replacement value"", ""insurance value, ""salvage value"", ""appraised value"", ""book value"" and ""fair market value"", to name a few, although in the mining industry, valuations usually refer to fair market value.In the Canadian mining industry, at present, there are no comprehensive regulations or guidelines that specify which approaches or methods are appropriate for use in the valuation of mineral projects. In January 1999, The Mining Standards Task Force of the Toronto Stock Exchange and the Ontario Securities Commission recommended that the Canadian Institute of Mining, Metallurgy and Petroleum establish a committee to review and advise on approaches and methodologies for the valuation of mineral properties. Among the approaches to be considered, are included the following: the Discounted Cash Flow Approach, the Cost Approach, the Option Pricing Approach and Market Comparables Approach. In addition, methodologies differ depending on whether the project is at the exploration stage or the producing stage.The CIMVal committee expects that its final report will form the basis for a standard Canadian Code for the valuation of mineral properties."

Jan 1, 2003

By Herty, C. H.

One of the numerous requirements of many grades of present- day steel is that the steel shall be free from non-metallic inclusions. These inclusions may be composed of oxides, sulphides, complex oxy- sulphides, and nitrides, which enter the steel with the furnace charge, result from sulphur absorption from the furnace gases, or are formed in the steel during the deoxidation process. Although few' data are available which indicate in any quantitative manner the specific effects of inclusions in steel, there is a large mass of circumstantial evidence which points to the advisability of producing steel free from these impurities for many purposes. At the present time there is a growing feeling among metallurgists that non-metallic inclusions should be divided into two distinct types: (I) those readily visible under the microscope at ordinary magnifications; and (2) those in colloidal suspension or in solid solution. Both types are profoundly influenced by the character of the charge, the manipulation of the furnace slag, and the method of deoxidation. The work described in this bulletin deals primarily with inclusions visible under the microscope at ordinary magnifications, but the steels made by the various methods of deoxidation are being used LO study certain effects which may be ascribed to the second classification, named above. This latter work will be the subject of further bulletins on the effect of deoxidation practice on the physical properties of the steels involved.

Jan 1, 1957

By D. R. Gagnon

Mining companies are continually looking for product-ivity and efficiency improvements with their equipment to reduce operating costs. This paper will review the results of a productivity analysis conducted at the Luscar Ltd. Boundary Dam and Bienfait mines near Estevan, Saskatchewan using a Computer-Aided Earthmoving System (CAES) installed on a track-type dozer. The CAES TTT system is a Global Positioning System that provides the operator with constant survey guidance. The study includes a productivity comparison between two similar test sites, one with the aid of the CAES system and the other, without. The CAES TTT system shows a productivity improvement of between 20 and 35% in the reclamation slope leveling application. Even with the CAES TTT system deactivated, some of the advanced features of the system were used to: retain terrain data for volume calculations; track the equipment position; and, accurately record and separate idle time from working time.

Jan 1, 2002