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By Sean Gallagher, Rhys Llewellyn, Jay Mattos

This paper contains the results of an examination of accident, injury, employment, and production information reported to the U.S. Department of Labor's Mine Safety and Health Administration (MSHA) and provides information on some of the measures longwall mine operators are using to prevent accidents In all industries, technological advances play a key role in determining those who will survive as competitive participants in an increasingly global marketplace. While mining is among the most basic of industries, technological change is neither unfamiliar nor unwelcome to miners. Historically, technological advances in mining, particularly coal mining, have tracked closely with fluctuations in demand. In the early 1900's, coal accounted for more than three quarters of all the fuel consumed in the U.S. To meet this tremendous demand, underground cuffing machines were introduced, resulting in faster, more efficient coal extraction. Transporting coal to the surface, however, remained labor intensive. In the 1920's, nearly all underground coal was still being hand loaded. Demand for coal then declined as the price of oil, natural gas, and electricity became competitive. In the late 1930's and throughout the duration of World War II, coal demand and production was high. By 1940, more than half the coal mined was being mechanically conveyed to the surface. In 1948, the continuous mining method was introduced in the U.S., further accelerating the extraction process. By the 1950's and 1960's, however, coal production again declined as railroads converted to diesel fuel and gas and oil provided a larger share of the home heating market. Underground coal mines required even more mechanization to remain competitive as an energy source. The first longwall system was introduced in 1960. By 1995, longwalls were producing more than 189 million tons of clean coal annually, surpassing continuous mining production for the second straight year. The mining of coal and other materials has not come without a huge loss of life and considerable human suffering. More than 103,000 workers died from injuries in U.S. mines in the last 85 years. Between two and three thousand miners died each year from the turn of the century until 1931, many from underground fires and explosions. The U.S. has witnessed a tremendous drop in fatalities in underground coal mines. Credit for that is due to safety inspections and enforcement activities, better safety awareness and practices among management and labor, improved ventilation, the use of safer equipment, and increased mechanization which removed many miners from the hazards at the face and also reduced the size of the mining work force. There is little doubt that longwall mining has greatly increased underground coal mine productivity. The degree to which longwall mining has contributed to a safer work environment for underground miners is more difficult to ascertain.

This paper reviews ore pass practice in some Canadian mines in Quebec and Ontario. In particular it reviews ore pass configuration, flow control mechanisms and monitoring practice. A review of the type of problems encountered and the tools to restore flow is also presented.

Jan 1, 2005

By R. Abela

In over ninety per cent of mineral sand plants, the most commonly used equipment is the spiral concentrator. The tonnage treated over typical spiral plants can range from as low as 200 ton per hour up to 6 000 tons per hour. Due to the limited capacity of each spiral, plants consist of multiple spirals assembled into banks. The mixture of minerals present in the sand feed requires several spiral stages to achieve the desired mineral recovery. Due to the complexity of the spiral circuits, there are always some design and operating problems that present themselves in plants. These range from slurry distribution, spirals operating at incorrect design parameters and feed variations. The material being treated is difficult to maintain in suspension due to its high density, resulting in segregation and preferential flow in pipelines, distributors and sumps. The objective of this paper is to highlight common problems associated with spiral installations to designers and operators of plants. Practical solutions are recommended in order to prevent and minimize these mistakes in the design. These solutions may be used to improve performance on operating plants.

Jan 1, 2003

By Graham Speirs

La minería del siglo XXI requiere que ingenieros, consultores y proveedores brinden apoyo a promotores, desarrolladores y operadores para lograr una extracción y procesamiento de minerales segura, eficaz y con el menor costo posible. Este artículo técnico muestra el diseño, construcción y mantenimiento de un eje vertical, con una forma más rápida, económica y productiva de izar con cables guía, buzones de aluminio y sistemas de izado diseñados con tecnología de vanguardia.

Sep 30, 2017

It was customary formerly to publish an index of the Transactions about every fifth volume, but since the Institute began in 1913 to publish three volumes instead of one volume per year, this has been deemed impracticable and unnecessary. No collective index has been published since the one covering Volumes I to XXXV inclusive, excepting a short one covering Volumes XXXVI to XL inclusive. The Board of Directors, therefore, upon the recommendation of the Committee on Papers and Publications, decided to publish this index of Volumes XXXVI to LV inclusive, and thus enable members to have in condensed space the collective indexes of all the volumes of the Transactions.

Jan 1, 1918

By Jun Zhu, Jilai Xuel, Tao Li

"Coal gangue is industrial waste containing Al2O3 and SiO2 with great recycling and reuse values. This work is aimed at extracting Al2O3 content in the coal gangue by a process of carbonthermal reduction - alkaline leaching. The Al2O3 and SiO2 contents first became a mixture of SiC and Al2O3 in the process of carbonthermal reduction, and then Al2O3 was separated by leaching in NaOH solution, thus producing the sodium aluminate solution for Al(OH)3 precipitation. The products generated at various stages in the process were inspected using XRD and chemical analysis. The effects of parameters such as reduction temperature, carbon ratio, NaOH concentration, leaching time, leaching temperature, stirring speed, etc were investigated in details.IntroductionCoal gangue is an industrial residue resulted from the process of coal mining and washing, accounting for 100 - 150 kg with 1 ton raw coal mined. The existence of coal gangue in large quantities has become a serious problem for environment pollution. On the other hand, the chemical compositions of coal gangue are Si02 and Ah03 primarily. In China, the accumulation storage capacity of Ah03 in coal gangue is not less than 600 million ton at a rough estimate, which should be considered as an abundant second resource [1]. If the alumina can be recycling and reused effectively from coal gangue, it will not only reduce the imperilments caused by coal gangue, but also yield good economic returns.Generally, the processes of extracting Al2O3 from coal gangue can be divided into acid leaching (vitriol or hydrochloric acid) and alkaline leaching (mostly NaOH) [2]. The acid leaching processes have many problems, such as lower leaching ratio, corroding the equipments, recycling the spent acid hardly, etc. The primary matter of alkaline leaching process is silica dissolving with alumina, which brings perplexing desilication process, alumina loss seriously and higher energy consumption."

Jan 1, 2011

By G. A. Apell, E. G. Howe, S. W. Hazen

"INTRODUCTION As a small amount of manganese was produced from the Lake Valley mining district of Sierra County, N. Mex., during the First World War, the district was reexamined in March 1941 by John H. East, Jr., an engineer of the Bureau of Mines, as a possible source of manganese for use during the Second World War. Preliminary examination indicated a substantial reserve of 25 percent ore, so it was recommended that an exploratory program of mapping and sampling be undertaken by the Bureau.The program was started in the fall of 1941 and was completed the middle of 1942. The project 3/ was divided into two parts: The first, an underground sampling program, formed the basis for the second, or churn-drilling program. Mapping and sampling of old underground workings were begun in October and finished in November 1941, whereas churn drilling was begun in February and completed in June 1942."

Jun 1, 1947

By Abid Adekunte

"Whilst safety is considered to be of high priority in every aspect of engineering projects, it is equally important for designers and contractors to be continually aware of their obligations to the immediate environment and the society as a whole. These include responsibilities to minimise the amount of nonrenewable natural resources and energy used on projects, to reduce carbon foot prints on projects, to minimise the quantity of wastes produced on projects, to minimise the level of pollution on construction sites and to reuse materials and waste products whenever and wherever possible.In other words, professional engineering practice needs to be accompanied by an underlying fundamental objective to improve, restore and sustain the environment. However, achieving this objective requires continuous collaborative interaction and effective communication between the different specialists involved on every project from the early stages. In addition, developing a well-thought-out economical solution is key to achieving the sustainability aspect of the above objective.This paper focuses on the design, construction and management of a recently completed large multi-level basement scheme in Central London, with greater emphasis on collaborative approaches taken by the design engineers, commercial managers, construction managers and site operatives to deliver the most reasonably economical and sustainable solutions to the client. Solutions were based on combinations of general and specialist engineering knowledge, with due considerations for health & safety, sustainability, cost, practicality, time and community requirements.INTRODUCTIONUnderground structures have become vital components of urban life worldwide e.g. tunnels serve many water, wastewater, highway and railway schemes, basements have been incorporated into many urban commercial, institutional and residential developments, while many public underground car parks have been built to deal with the incessant problem of insufficient surface parking spaces in busy urban centres.The safe design, construction and maintenance of underground structures have been well-mastered by the deep foundation industry over the years. However, just like many other areas of engineering, aside the need to satisfy safety requirements, underground construction practice is now faced with a new set of requirements; the demand for more sustainable and cost-effective solutions, with reduced environmental and societal impacts. Designers and managers of underground construction schemes are now compelled to minimise the use of natural resources and energy, to minimise the amount of waste produced, to minimise the level of environmental pollution, noise and disruption to traffic and normal societal life at ground level around underground construction sites. In addition, the recycling of site wastes and reuse of materials have now become important aspects of underground space development. Considerable effort is being put into promoting sustainable development across the industry."

Jan 1, 2017

By Robert W. Bartlett

A computer model for predicting the rate of oxidative leaching of copper from fragmented low grade sulfide ores is presented. The model involves the kinetics of the dissolution of chalcopyrite grains and solution diffusion of oxygen within rock pores. Adjustable curve fitting parameters are not used. The model was tested by comparing computed extraction curves with experimental results for a -11 inch ore obtained by block caving and leached at 90°C and 400 psi oxygen for one year at the Lawrence Livermore Laboratories.

Jan 1, 1973

By R. J. Henry

This paper describing the mining practices at the Teck-Hughes mines at Kirkland Lake, Ontario, is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in various mining districts. HISTORY Prospecting was begun in the neighborhood of Kirkland Lake in 1906, but staking did not take place until 1911. Gold-bearing veins were discovered by surface trenching in 1913 on the mining claims which now make up the Teck-Hughes Gold Mines (Ltd.). A small mill was erected in 1916 after the completion of some underground exploration. A transmission' line was built in 1917 to the camp to provide adequate power for a vigorous underground campaign. Also in 1917 the present management took control operations since 1916 have been continuous,' with a steady increase in production to date.

Jan 1, 1930

By L. S. Kolbert, C. H. Baab

Introduction In June 1981, the Electric Power Research Institute (EPRI) issued a report titled "Control Systems in Coal Preparation Plants" to determine the status of instrumentation and automation systems in the coal preparation industry. EPRI concluded that the control systems presently being employed in the US coal preparation plants "are relatively primitive compared with those in other mineral processing industries; and analytical instrumentation is virtually non-existent." With tighter specifications on the quality of steam coal, interest is increasing in more sophisticated control systems. One type of device that is currently assisting the preparation plant operator optimize and control the coal cleaning process is nuclear based instrumentation. Nuclear instrumentation includes methods for measuring weight, level, and density as well as for performing elemental analysis on coal. Major Features and Benefits of Nuclear Measurement and Analysis Systems There are many features and benefits of nuclear instrumentation. The major benefit is that nuclear instrumentation is non-contacting. The measuring heads do not contact the process materials. This enables measurements of corrosive, abrasive, or high temperature materials with no loss of performance, reliability, or useful life. Also, there are no moving parts to wear or be fouled by dust or corrosion. Installation is simple and inexpensive. For instance, density gauges are simply clamped onto existing pipe runs. Weigh scales and level switches usually require nothing more than welding brackets to customers' equipment. Once installed, routine maintenance can be performed without interrupting the process. Thus, nuclear instrumentation is highly reliable and easily installed and maintained. The operating life of the instrumentation is virtually unlimited. Principle of Operation Nuclear belt weigh scales, point level switches and density gauges all operate on the gamma-ray transmission principle. A beam of gamma radiation from a radioisotopic source is projected through the process material either on a belt, in a vessel, or in a pipe. Opposite the source is a radiation detector whose electrical output is proportional to the intensity of the radiation it absorbs. Gamma radiation is part of the same electromagnetic spectrum that encompasses light, infrared, and x-rays. In many respects, gamma radiation behaves much like light. However, it is far more penetrating and can be transmitted through considerable thickness of materials that are opaque to visible light, e.g., several inches of steel. Types of Nuclear Instrumentation in Coal Preparation Plants There are four types of nuclear instrumentation presently being employed in coal preparation plants. They are: •Belt Weigh Scales •Point Level Switches •Density Gauges •Coal Analysis Equipment. Each type of instrumentation has a number of potential applications within the plant. What follows is a discussion of three different types of devices and their applications. Weigh Scales In coal preparation plants, weighing instruments are used for measuring material throughput, totalized weight, and batch weight on conveyor belts and other transport equipment. They are also used on drag chain conveyors, vibrating conveyors, and screw conveyors. Weighing is important for receiving the run-of-mine coal, controlling mass flow, scheduling production, and loading and shipping the washed coal to market. There are two basic types of weighing instruments: gravimetric and nongravimetric devices. Gravimetric devices are units which measure the pull of gravity on the material being weighed. Nongravimetric devices are not dependent on the force of gravity on the sample. Nuclear weigh scales are the most prevalent nongravimetric devices used. The nuclear weigh scale works on the same basic principle as other nuclear gauges. The greater the quantity of material placed in the path of a radiation beam, the more radiation will be absorbed by the material. In weigh scales, Cesium 137 source is generally placed above the moving stream of material so that the radiation is directed through the material. An ion chamber radiation detector is on the opposite side of the material. The radiation passing to the detector generates a signal which is inversely proportional to the weight of the material present. This signal is amplified and integrated with the speed of the process flow yielding the weight. The weight is indicated and can be totalized for throughput, batch control, etc. In conclusion, radiation weighing methods have become well established in the coal preparation industry throughout the world. As mentioned before, this device finds its most

Jan 1, 1985

By Joseph Zwierzycki

By an extension of drilling activities in 1938, the Polish oil industry succeeded not only in maintaining production but even in increasing it slightly. This increase, however, was from present oil reserves and not due to the discovery of any new fields. Most of the new wells were drilled in the Jaslo district, particularly in the Lipinki-Libuszal oil field, because of the shallow depth of the producing sands. At the Boryslaw field the 12,332 meters drilled could not compensate for the steady drop in production. A drilling campaign similar to that of the previous year in the Stanislawow district resulted in a slight decline of production. A number of the new wells have been subsidized by the Fund for the Advancement of Drilling2 in Poland. As the present sums at the disposal of this fund are insufficient for a great exploration program, they are chiefly used for the maintenance of the actual production. New wells on known folds, but more than 1000 m. outside the present productive areas, are entitled to a subsidy. Applications for wildcats outside the known productive areas have not been received in 1938. Even when the Polish oil industry was prosperous, wildcatting was not frequent and in their present impoverished condition the oil companies are no longer able to bear such financial burdens. The only way to start a large-scale drilling campaign on the still existing promising areas seems to depend on the granting of new substantial subsidies from the Treasury. Such measures are being considered by the Polish Government. It has been suggested that a fund for wildcatting might be raised by a small increase in the price of benzine. An advance of one grosz per liter of benzine would raise, on present home consumption of 108,000 kilogram-tons, about 1.3 million zloty, an advance of 5 grosze more than 6 million zloty.3 This small increase in price would hardly be felt by the motor-car owners, as it would mean an extra expense of 80 to 400 zloty in a year.

Jan 1, 1939

By V Lishchuk, C Lund

"Geometallurgy aims to improve resource efficiency by creating a spatial model of an orebody in order to forecast ore processing behaviour. This enables calculation of the economic value of each ore block and the use of this information for production optimisation and hence an improved economic return. Modelling uses different approaches to link geological information with mineral processing: traditional approach uses chemical elements; proxy approach – small-scale geometallurgical tests; and mineralogical approach – minerals.A geometallurgical model is obtained during execution of a geometallurgical program encompassing the entire value chain of ore processing. Available methods for establishing a geometallurgical model are in many cases limited and not yet comprehensively validated. Some of the limitations include: sampling density, assaying methods and quality, forecast accuracy block model content, geostatistical solutions for non-additive components, blending and assessment of positive impact of geometallurgy on the project. Synthetic ore models combined with process simulations and production scheduling, based on strong case studies, present a viable way to address these shortcomings. Such synthetic ore models will have realistic elemental and mineral distribution, textural attributes and 3D variability for input into the design of an appropriate geometallurgical program.A synthetic orebody was created for an apatite-bearing iron deposit. Variability in modal mineralogy was described by geostatistical parameters combined by a set of linear and trigonometric functions. The generated synthetic deposit model was used to develop a mine production plan to generate a simulated process feed. The process feed had detailed information required for beneficiation process simulation: modal mineralogy, chemical composition of minerals, grain size and specific gravity. The synthetic system was used to measure benefits that a geometallurgical program developed for real cases could provide, compared to production where only head grade is optimised. These include a reliable sampling strategy and confidence in the feed-quality forecast for economic evaluation.CITATION:Lishchuk, V, Lund, C and Lamberg, P, 2016. Development of a Synthetic Ore Deposit Model for Geometallurgy, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 275–286 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By V. L. Jr. Davis, F. L. Stanley, P. J. Bethell

Fwe 3 m (10 ft) diameter Microcel™ flotation columns were installed at Clinchfield Coal Company's Middle Fork preparation facility in order to reduce product ash and increase recovery and plant capacity. The Middle Fork facility is utilized for the recovery of fine coal from a feed stream that consists primarily of 1 .5 mm x 0 material. The columns replaced conventional flotation cells for the treatment of the minus 150 pm fraction while spirals are used to upgrade the plus 150 pm material in the plant feed. The addition of the column flotation circuit resulted in an increase in plant capacity in excess of 20 percent while reducing the flotation product ash content by approximately 7 percentage points. Flotation circuit combustible recovery was increased by 17 percentage points. This paper discusses circuit design, commissioning, and sparging system design. Circuit instrumentation, level control, reagent system control, performance comparisons with conventional flotation, and general operating procedures are also discussed.

Jan 1, 1995

Mainland China To Pay Japanese Company On Contract Claim. - Mitsubishi will receive $39 million from Red China, half of what was asked, for China's having, curtailed work on a 5369 million steel rolling mill at Baoshan near Shanghai. Copper Found in Chile. - Utah International Inc., in conjunction with Getty Oil Co., has discovered a cooper deposit in northern Chile. Early drilling reveals an enriched zone grading 1.2% to 2 3% copper. Chile already has tie world's largest Cu reserve base. Soviets To Aid Laotian Tin Industry. - The U.S.S.R. has agreed to help strengthen the tin industry in Laos, a client state. In the past, Laos has only produced small amounts of tin concentrate, 500 tons to 1,000 tons per year presumably shipped to smelters in Singapore or Penang, Malaysia. Under the agreement made in June, the Soviets are to supply equipment to increase the out put of tin from the Phontieu, Neng, and Nongsen mines and help Laos with the construction of a tin smelter. The U.S.S.R. itself is a net importer of tin, although a substantial producer of the metal.

Jan 1, 1981

By Charles T. Chislaghi

An economical, remotely operated (automated), temporary roof support (ATRS) has been developed by the Bureau of Mines for use on a single, fixed-head roof-bolting machine (squirmer) that operates in low coal seams (less than 42 in thick). The ATRS eliminates the need for squirmer operators and helpers to go under unsupported roof to set or remove temporary support prior to or during the roof-bolting cycle--a task that annually accounts for approximately 20 pct of all roof fall fatalities. The ATRS can be adapted to any squirmer used in the U.S. low coal fields. A prototype ATRS was field-tested at Imperial Colliery Co.?s Mine No. 20 in Eskdale, W. Va. The Mine No. 20 amended roof- control plan, which requires the use of the Bureau?s ATRS as temporary support during face bolting, has been approved by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor.

Jan 1, 1982

By Cesar Montoya, Yarmin y. Taborda

Indagar sobre la operatividad de la minería en Colombia es una acción mayúscula, pues esta no se observa solo desde la arista económica para la generación de beneficios a determinada población, sino también de acuerdo con su historia, personas que la operan, formas de desarrollo y otros. La investigación se desarrolló en 15 minas artesanales ubicadas en los sectores: La Ferrería y la Cancha del municipio de Amagá en Antioquia. Se ejecutó con un enfoque cuantitativo no experimental de tipo correlacional y permitió la descripción de características propias de las minas y la identificación de los niveles de desarrollo frente al Sistema de Gestión de Salud y Seguridad en el Trabajo.

By Robert A. Melton

Since many of the easily mined, continuous, thick coal seams in the Appalachian Region have been exhausted, new exploration and mining is being directed toward less continuous seams that are under more cover and are more difficult to mine. The direct results of this are that more money and time and more expertise and data are needed to plan and open new coal mines today. It is also becoming apparent that the old methods of assimilating and preparing information needed for mine planning are inadequate to meet the needs of today's modern mining engineer, especially in the areas of data gathering, storage, retrieval, preparation, and interpretation. The system described here allows assimilation of old and new core data in a relatively quick, accurate, and efficient manner. The system is a set of computer assisted procedures consisting of the following four basic steps: 1) raw data collection, computer input, storage, and graphic preparation, 2) geologic profile correlation and establishment of seam continuity, 3) computerized data posting of important seam parameters, 4) geologic and planimetric analysis for mine planning.

Jan 1, 1977

By S. Floreen, R. M. Pilliar, H. W. Hayden

The fracture behavior of a 50 pct Cu-50 pct Fe mi-croduplex alloy, laminated composites of copper and iron and an extruded 50-50 Cu-Fe elemental powder composite was studied. Very low ductile-brittle transition temperatures were achieved in all cases, but for different reasons. In the microduplex alloy both the initiation and also the propagation of cleavage fractures appeared retarded by the very small in-terphase distances. In the composites, crack propagation through the sumples was prevented in most cases by delamination fractures perpendicular to the advancing cracks. These delaminations occurred at different regions and by different mechanisms in the various composites. In the extruded powder composite, de-lamination appeared to take place along preexisting flaws. In the crack arrest geometry of the laminated plates, delamination took place by localized shear fractures within the copper near the Fe-Cu interfaces. In this case delamination was enhanced by thicker laminate layers, and by having the resistance to shear failure of the copper sufficiently low compared to the toughness of the iron. BRITTLE fracture in engineering materials has long been a problem, and many different ways of preventing it have been considered. One method that has been of growing interest lately is to prevent crack propagation by the introduction of mechanical discontinuities into the structure. These discontinuities may act in several ways. They may simply act as crack stoppers. They may introduce secondary fractures such as de-laminations that deflect the initial crack into new, less damaging directions. Alternatively, they may subdivide a fairly large bulk sample that would have been loaded in plane strain, for example, into a number of subunits that are individually loaded in plane stress and thus are more resistant to fracture. Other mechanisms, or combinations of mechanisms, are also feasible. A number of methods exist for introducing mechanical discontinuities into a structure. Composites by their nature have discontinuities in structure, and numerous studies have shown that fracture propagation in materials of this type can be radically changed by suitable control of the composite parameters. Of particular significance to the present work are recent investigations of layered composites made by joining high strength steel sheets by various means.'-4 These studies have shown that through proper control of the mechanical properties of the bonds joining the sheets it was possible to introduce delamination fractures that markedly improved the overall toughness of the composites and in some cases completely prevented through-the-thickness fractures. Another technique for introducing structural discontinuities is simply to use a two-phase alloy. It has been recognized for many years that a small amount of a second phase may improve toughness either by homogenizing plastic flow and thus preventing localized stress concentrations that nucleate fracture, or by interacting with an advancing crack. In most of these studies of two-phase materials, the decreases in ductile-brittle transition temperatures produced by the second phase were relatively small. More recently, work on two-phase stainless steels having a very fine grain microduplex structure has shown that the presence of on the order of 40 to 50 pct of a tougher second phase may lower the ductile-brittle transition temperature of the brittle phase by approximately 300°F. 5-7 In these alloys delaminations were seldom observed. The tougher second phase appeared to minimize the ease of both the initiation and the propagation of cleavage fractures. These results show that both the composite approach and the microduplex alloy approach are effective methods of preventing brittle fracture. Therefore, it was of interest to compare the fracture behavior of a microduplex alloy with composites made from the two-phases that were present in the alloy. To simplify this comparison the 50 pct Cu-50 pct Fe system was selected for study. At low temperatures the equilibrium tie line phases in this system are essentially pure ferrite and pure copper. A 50-50 alloy was cast and hot worked to produce a microduplex structure. Two types of composites were studied; laminated structures prepared by roll bonding iron and copper sheets of the tie line compositions, and an extruded powder composite made from high purity elemental powders. The fracture behavior of these materials was then compared. EXPERIMENTAL PROCEDURE Alloy Preparation. The 50-50 Fe-Cu alloy and the components for the roll bonded composites were prepared by vacuum induction melting 30-lb heats using electrolytic grades of iron and copper as charge materials. A carbon boil was used to deoxidize the melts. Small additions of copper and iron were made to the iron and copper heats, respectively, to approximate

Jan 1, 1970

By John G. Myers, William A. Vogely, Harold J. Barnett

INTRODUCTION, CONCEPTS, AND MEASUREMENT Introduction Periods in the history of man, from his earliest appearance to the present, are often characterized by the principal materials used. In nearly all cases, the material or fuel is of mineral origin-stone, copper, bronze, iron, coal, and so forth-indicating the principal ingredient of the tools or source of power of the period. Each of these periods represented great improvement over the preceding one in terms of human well-being, as measured by population growth and other indicators (Cipolla, 1978). A major reason for the improvements in production and well-being was the nature of the material or fuel, each successively superior to the preceding, which made it possible to produce more food, fuel, shelter, and clothing with a given amount of labor. If we accept this well-documented description of economic progress as accurate, we may then turn to the consideration of two related questions concerning this development. The first, easily answered,-is why man spent long periods of time (millenia, in many cases) making tools from inferior materials, such as copper, instead of passing directly to superior materials, such as iron and steel. The second, closely related question, concerns the relation between the rate of economic growth and the quantity of mineral reserves available at any time. For the first question, the answer is that the technology required to discover, extract, and process each successive material had to be discovered and developed before the material could be used. Once the technology was available, the new material could be and was exploited widely, raising productivity-output per unit of labor- and consequent consumption per person. This familiar idea underlies a fundamental principle of the economics of resources, namely, at any time, available resources depend upon available technology. No mineral or other raw material is a resource unless the technology has been developed to utilize it. But once the technology is at hand, the new resources associated with it provide the means for economic growth and rising levels of living. This principle is subject to certain conditions. For example, governments or other institutions may prevent a mineral from being used, even though the technology is available. And, if a mineral is located in a remote place, transportation charges may make it uneconomic to exploit. Such minor qualifications do not, however, change the thrust of the argument that technology is the overriding determinant. With respect to the second question, it might seem apparent that the greater the quantity of reserves available, up to some point, the more economic growth will be facilitated. This line of reasoning leads to the conclusion that as re- serves are consumed the quantity available will be reduced and economic growth will eventually be restrained. Reasoning of this sort underlies much popular (and scholarly) thought, in which depletion of mineral and other resources is assumed to lead to constraints on economic growth, through higher materials costs and absolute limitations on materials use. Two important qualifications must be made to this explanation, however, which together

Jan 1, 1985