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By George S. Rice

The following paper was presented at an International Conference on Mine Safety Research held at Dortmund, Germany, September 23-28, 1935, inclusive. This conference was attended by representatives of Belgium, France, Germany, Great Britain, and the United States ands by invitation, Czechoslovakia, Poland, Spain, and Russia. The first international conference of representatives of mine-safety, research stations was held the United States Bureau of Mines Pittsburgh Experiment station in 1912 .4/

Jan 1, 1936

By Donald A. Bruce

The paper reviews aspects of the construction and performance of prestressed ground anchors installed in soils and weak rocks. Attention is focused on good practice for drilling, tendon fabrication and handling, grouting, stressing and testing. Regional variations - not always logically justified - are described. The performance of anchors in a variety of geological conditions is illustrated with reference to recent full scale test programs. 1. Introduction In the United States there has been steady growth in the use of prestressed anchors in materials other than competent or hard rock, in the years since their introduction in the late 1960's. This expansion has to a large extent been driven by specialty geotechnical contractors who both imported foreign developments and conducted their own basic researches, in locally prevailing conditions. With such data and experience, these engineers have had the confidence to promote "alternative solutions" for difficult earth support problems to receptive designers and owners. In turn, being engaged in the details of design and performance monitoring has given these parties the close exposure necessary for the real transfer and understanding of the technological concepts, and this knowledge has generated positive feedback for the contractors.

Jan 1, 1991

By Steven J. Page, John A. Organiscak

The amount of airborne respirable dust generated from break- age of different coals varies widely. This research was conducted to identify the facets of airborne respirable dust liberation from the coal product. Laboratory crushing experiments were conducted on a range of low to high volatile bituminous coals to investigate the various factors influencing airborne respirable dust generation. Bituminous coal samples from 8 mines (5 U.S. and 3 Polish) were uniformly prepared and processed through a double roll crusher located in a low air velocity wind tunnel. Experimental factors studied included inherent coal seam constituents, specific energy of crushing, product size characteristics, dust cloud electrostatic field, and specific quantity of airborne respirable dust generated. The results of this investigation build upon previously published results, which indicated that a combination of several factors are associated with the generation of airborne respirable dust. One factor involved is the effect of coal rank, described by the inherent moist fuel ratio, on the product size characteristics, defined by Schuhmann size function parameters. However, since coals of high moist fuel ratio (high rank) are generally more extensively cleated, it is suggested in the present work that the degree of cleating is directly responsible for the quantity of respirable-sized particles produced in the crushed product material for eastern U.S. coals. This is implied by the relationship of ash content and at least one mineral constituent (pyrite, determined from pyritic sulfur analysis) to the percentage of airborne respirable dust. To validate this hypothesis, a description is offered that is based on known coal petrography. Another key factor is the effect of air dry loss moisture in the coal seam on the breakage-induced electrostatic field of airborne dust. The air dry loss moisture factor appears to control the amount of airborne respirable dust that is liberated from the product. The resultant effect of these factors is that different percentages of coal particles smaller than 10 µm are dispersed as airborne respirable dust with a well-defined peak in the normalized airborne respirable dust for a narrow range of air dry loss moisture - ash ratios. A clear delineation of coals, based on well-known proximate analysis characteristics, that generate the most respirable dust appears to be possible. It was also shown that the dust-generating characteristics of coals could be reasonably described by both the moist fuel ratio

By J. D. Steenkamp

In a paper presented at the Heavy Minerals Conference 2001 a laboratory scale investigation on the beneficiation of an ilmenite containing waste stream by magnetizing roasting was reported1.This waste stream contained a high concentration of ilmenite, which was contaminated by chromite and other gangue minerals. Interpretation of the results of the investigation was based on the assumption that during magnetizing roasting of an ilmenite concentrate, under the oxidizing conditions, the magnetic properties of the chromite would remain constant. In this article the following hypothesis was tested: The magnetic susceptibility of chromite would remain constant during magnetizing roasting of an ilmenite concentrate under the oxidizing conditions reported by Gouws and Van Dyk1. The results of this study indicated that the hypothesis is not true. The increase in the magnetic susceptibility is not significant though and it is expected that it will not influence the final ilmenite quality to a large extent. Based on the assumptions that the bulk magnetic susceptibility of the waste stream samples represents that of the ilmenite in the waste stream, and the bulk magnetic susceptibility of UG1 chromite that of the chromite in the waste stream, the results also served to confirm that the waste stream with a high chromite content should be roasted under oxidizing conditions, in a reactor with a well-defined retention time distribution (i.e. a fluidized bed reactor), at a roasting temperature of 750°C (rather than the higher temperature ranges of 800°C and 850°C).

Jan 1, 2003

By Joseph J. Wallace

1. The Investigation shows that there are six coal beds of major importance in McDowell County from the standpoint of present production - Pocahontas No. 3, Pocahontas No. 4, Pocahontas No. 5, Sewall, Beckley, and Pochontas No. 6 - and five beds of minor importance - Iaeger, Douglas, Welch, Pocahontas, No. 9, and Eagle. The Pocahontas No. 3 bed contains the largest remaining, known reserves. 2. Known measured, and indicated reserves in all beds, based on a minimum thickness of 174 inches and on 1,800 tons per acre-foot of coal in place, are estimated at 2,217 Trillion short tons as of January 1, 1951. Of this total, 1,731 million short tons are in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics are too meager to make an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these area, such reserves should be added to he total estimated reserves.

Jan 1, 1952

Probably no other country or coutinent has so many rich deposits of various different minerals as Australia. Long ago in the days of my boyhood in the old land the marvellous discoveries of high percentage copper at Burra Burra, Peak Downs, Yudanamutana, and other mines, was one of the principal themes of conversation in mining circles whilst the specimens of malachite, azurite, etc, brought home by returning miners were the admiration of my boyish eyes.Later on the WalIaroo and Moonta mines still further helped to heighten the reputation of Australia as a copper-producing country. During the 21 years that the writer has been resident in the Australian colonies, other mineral deposits have sprung into prominence, and with a Mount Bischoff for tin, a Broken Hill for silver and lead, and a Mount Morgan for gold, Australia can now boast that it has had within its borders the leading mines of the world, in four different minerals, and still at least maintains that pre-eminence in gold, silver and tin. To the miner from the old land, Australian mining is at first a revelation and a wonder. In very many instances he looks in vain for the regular strike and dip of the veins he has been accustomed to'Smooth hanging and foot alls are often wanting. 'Huge irregular deposits, like those mentioned above, viz., Burra Burra, Mount Bischoff, Broken Hill, and Mount Morgan, are mysteries that will take time to fathom-if, indeed, they are ever thoroughly understood and in many a smaller deposit there is much to interest alike the professor in the college and the miner in the mine.

The addition of cement to underground backfill at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited, Broken Hill commenced in 1967. A deterioration in metallurgical performance at each concentrator occurred as a result, with increased loss of lead and zinc to residues. Investigations to determine the reasons for this problem and methods to counteract it have been undertaken. This paper outlines the effects of cement on lead-zinc beneficiation at Broken Hill and presents an interim report on attempts to overcome the metallurgical deterioration.

Jan 1, 1971

By Howard W. Wainwright

This bibliography was compiled by the Bureau of Mines as part of an investigation into the possible utilization of low-temperature coal-tar bases. The bibliography consists of literature and patent references from about 1945 to 1961 and is divided into the following headings: Analysis and Composition; Production, Synthesis, Reactions, and Utilization; and Separation, Purification, and Properties. Although over 1,000 references are included, no attempt was made to insure a comprehensive survey. The literature and patent references are arranged alphabetically by author or patentee. When several publications have the same author they are listed in reverse order of age, with the newest first. An author index is included because secondary authors are not cross-indexed. In almost every instance, the entry is accompanied by a Chemical Abstracts reference for those interested in locating an abstract of the original paper.

Jan 1, 1962

By P. I. James, M. R. Baker

Este artículo analiza la nueva producción de cobre a partir de "minerales de desecho" de baja ley usando la tecnología de Blue Planet Strategies DEMET™ (Dynamic Electrode Mining Effluent Treatment, por sus siglas en inglés), que tiene como objetivo salvar la brecha de procesamiento entre la solución débil de lixiviación en operaciones de extracción por solventes/electrowinning (SX/EW), removiendo electroquímicamente los metales a partir de corrientes débiles y a la vez generando productos concentrados en metales objetivo en un análogo funcional de extracción por solventes (SX). Se estudió el tratamiento de la débil solución de lixiviación pregnant (PLS por sus siglas en inglés) y se usó para estimar los impactos económicos y de producción para una hipotética lixiviación en pilas de cobre brownfield y una operación aumentada DEMET usando SX/EW para tratar el "mineral de desecho." Se presenta la remoción de cobre a un 86% de eficiencia en las placas por debajo de 0,1 g/L de cobre con un consumo de energía de 0.55 kWh/lb de cobre y una concentración del producto mayor a 10 g Cu/L. El modelamiento arrojó aproximadamente $2/ lb para la producción total de cobre y costos de tratamiento menores o iguales a $1/lb con un inmediato aumento del margen bruto de operación del 12% para el brownfield incrementado. Se indicó también un aumento de la vida de la mina con un margen bruto promedio de 38% en la producción aumentada de "mineral de desecho" con valores de cobre de $3.25/lb.

Jan 1, 2014

By Shahid Islam, Lucian Bogdan

There is a rapid expansion of world’s infrastructure and simultaneously existing infrastructure is aging. The maintenance of infrastructures has been of particular concern to the engineering community. Monitoring and evaluating the structures have become more significant than ever. Ground anchor is an important part of the structure where it is installed. Unfortunately there are limited testing methods available to assess the force in the pre-stressing steel. High cost, complicated equipment and limitation of space often prevent these methods from being implemented. DYNA Force sensors have been developed to measure the force in the pre-stressing steel during construction and at any time during the lifetime of the structure. These sensors make use of the magneto-elastic properties of ferrous materials. A readout unit is designed to magnetically energize the steel through the sensor and measure the response of the steel to the process. The readout unit then converts the response into a direct force reading. They can be used for bare, epoxy- coated, galvanized and greased-sheathed steel in the bonded, un-bonded, grouted or un-grouted length of the tendon. It measures the force of the steel element at the location where it is installed and can be recorded manually, automatically, or remotely. The sensor is robust, requires no maintenance and it is expected to have a similar service life to that of the surrounding structure. Sensors have received attention in terms of accuracy, performance, ease in installation, durability, and cost effectiveness. Sensor readings provide a second measurement, in conjunction with the jack pressure gauge, of the post tensioning force during initial testing procedure for ground anchors. This paper describes its application in tie-back and tie-down anchors and force monitoring of retaining walls, bridge abutment and dams where the data were collected manually, automated and remotely. INTRODUCTION Our infrastructure is expanding and the existing infrastructure is aging. Some structures are expensive to maintain and some occasionally fail. There is a large demand for implementing health monitoring of structures. Many tie-backs, retaining walls, dams and other geotechnical structures are post-tensioned and many of them need repair using a post-tensioned system. On many occasions during construction and service life of the structure, it is useful to know the force in the post-tensioning and anchor system. Many piles and drilled shafts are designed using reinforcing steel and the compressive forces in reinforcement are unknown. Although there are many methods to measure the tendon force, most of them are cumbersome, expensive, and the accuracy varies depending on the method used.

Jan 1, 2018

By C. R. Edwards

"The Cigar Lake project will develop the world’s second largest high grade uranium deposit. The Cigar Lake Phase 1 orebody contains approximately 226 million pounds U3O8 at an average grade of 20.7% U3O8. The mine, to be operated by Cameco Corporation, will use a unique water jet boring mining method to cut previously frozen ore. A distinctive ore handling design is required to handle the high grade ore slurry exiting the mining machines. The ore will be crushed and ground underground, with the ore slurry then pumped to surface. Loaded into purpose-designed containers on tractor-trailer units, the ore slurry will be trucked to Cogema Resources Incorporated’s McClean Lake mill. McClean Lake will leach all of the ore. Forty-three percent of the resulting uranium solution will remain at McClean Lake for processing into yellowcake. The other 57% of the uranium solution will be shipped to Cameco’s Rabbit Lake mill for processing into yellowcake there. Detailed design for the Cigar Lake project is now underway. Barring regulatory or market delays, production could start up as soon as early 2005.INTRODUCTIONThe Athabasca Basin in northern Saskatchewan hosts a number of large uranium mining and milling operations, including Cluff Lake, Key Lake, McArthur River, McClean Lake and Rabbit Lake. (Edwards 1988, Edwards 1992, Fielder 1998, Edwards and Oliver 2000, Edwards 2001) The latest project in the Athabasca Basin is the Cigar Lake project."

Jan 1, 2002

This report describes the development of training materials for the operators of underground mining equipment in the underground metal and nonmetal mining industry. The objective was to determine the effectiveness and acceptability of these training materials and to provide the validated training materials to the industry. Ten modules were developed, based on industry need according to accident frequency, accident severity and exposure to the equipment. The final modules were an average of 20 minutes in length and used slides with synchronized narration on cassette tapes. Testing materials are included for use by the mines.

Jan 1, 1984

By Browner R, Lincoln F. J

The activity of silver in solid gold-silver alloys (electrum) has been measured with an electrochemical concentration cell based on the super ionic conductor silver-i3-alumina in the temperature range 200 to 80oaC.The measurements of the silver activity in the range 0.5 to 90.0 atom per eent silver were found to be highly reproducible although there is some disagreement with an earlier study which used a similar technique. At temperatures above 400° the silver activity exhibits both positive and negative deviations from ideality in the silver rich region.This method suggests a simple technique for the nondestructive determination of silver in electrum alloys.

Jan 1, 1983

With the advent of the environmental "green" movement of the 1960s, eventually leading to Earth Day 1970, Congress responded by passage of the National Environmental Policy Act (NEPA), 1970. NEPA gave impetus to a flood of federal acts and laws in the subsequent three decades. Many of those protecting man's environment, health, and well-being also affect mining. For purposes of this chapter, a current mineral law summarization lends itself to a division into two parts: viz., Part I, General Mining Law, and Part II, Enviromining Law. The word enviromining has been coined by the author and is defined and used herein as those federal and state statutes and regulations that were created to provide protection and preservation of man's environment, health, safety, and welfare, and they have particular application to and affect on mining activities. They are listed and treated under Enviromining Laws in Part II. Mining, as a basic industry to provide the essential minerals for mankind's necessities and well-being, truly reflects the mining industry's slogan, "If it can't be grown, it must be mined." Without the basic minerals and rocks won from the earth by mining and mineral processing for their valuable physical properties or chemical constituents, man would soon be forced to revert to the cave-dwelling age. Unfortunately, for man to survive in the "manner of life to which he has become accustomed," he is caught between the demands of cleaning up his deteriorating environment and a continued supply of his basic requirements and amenities for daily living supplied by mining of the earth's minerals. He must have "clean living" at the same time with "good living;" neither is expendable. A very high pricetag accompanies this essential and critical choice which must be paid by society. The United States is internationally recognized as the world leader in environmental matters. Many countries are following suit, principally the other Anglo nations. Because US law is founded and based on English law, on occasion, Anglo-American law is referred to and cited as authority in litigation anywhere in the Anglo-American world of jurisprudence. For this reason, and because mining and the industry is international in nature and operations, some British Commonwealth cases will appear in various topics. If the case is of interest to the reader, further inquiry at a law library may be made through use of the case's style and citation given. "Style" refers to the name of the litigating parties. "Citation" refers to the law publication in which the case and decision may be found, as well as the jurisdiction and court of decision. Citation of cases from the United States and British Commonwealth nations is explained under Case Citation Explanation. Space and time limit exhaustive treatment of subjects and covering all geographic and jurisdictional areas. This chapter is intended as a broad outline and is based on the author's master's thesis at the University of Missouri-Rolla, 1992. The following Case Citation Explanation provides guidance on formatting of citations.

Jan 1, 1994

By Elmer Vidal Sánchez

Dado que la voladura de rocas en minería y construcción genera vibraciones de terreno, ocasionando daños a las instalaciones cercanas a la operación, se ha visto necesario realizar un control de las vibraciones por medio del criterio de velocidad pico de partículas. De acuerdo a este criterio, para toda voladura existe una mínima cantidad de explosivos a detonar dentro de un intervalo de 8 milisegundos. Sin embargo, no considera la variable "frecuencia" como parte del control de vibraciones. En este sentido, el presente texto describe una alternativa diferente para el control de las vibraciones denominada "análisis de frecuencias", cuya técnica se basa en un modelo computarizado que controla y predice las vibraciones en un lugar específico, considerando las condiciones geológicas existentes entre el lugar de la voladura y el punto de interés.

Aug 26, 1988

In a previous paper the author showed that silver considerably delayed the recrystallisation of lead after cold work. The effect of antimony on the rate of recrystallisation of distorted lead was studied next, and the experiments performed, and the results obtained, are described in this paper. Electrolytic lead was used as a standard of comparison.It was also used to make the lead antimony alloys.This electrolytic lead contained 0.0005% total impurities.It was prepared from commercial lead by fire refining, followed by electrolysis and finally by vacuum casting. The process was described in the previous paper and the description need not be repeated here. PREPARATION OF LEAD - ANTIMONY ALLOYS.The steps taken to procure pure antimony are outlined in the appendix. To make the lead antimony alloys a mother alloy was prepared thus:-A quantity of the antimony (it was received in the powdered form) was placed in a pyrex glass tube, which was closed at one end. The antimony was washed with hot hydrochloric acid (1: 1), then with more dilute acid, then with distilled water, and finally with absolute alcohol; it was dried by warming and evacu,ating the tube. This should leave the antimony more nearly free from surface oxides.The amount of antimony was determined by weighing quickly; the appropriate amount of vacuum-cast electrolytic *Research Fellow, Dept. of Metallurgy, University of Melbourne.

Jan 1, 1936

By Kenneth C. Stewart

The overall purpose of this study was to develop and evaluate, in the laboratory, instrumentation and procedures which might allow for the use of physical measurements of earmuff attenuation which would yield results equivalent to those obtained from psychophysical measures of attenuation. The ultimate goal was to evaluate techniques which might subsequently prove feasible for physical measurement of earmuff attenuation in the field. Current instruments were modified to have a response similar to differrences observed in earmuff attenuation as observed in Volume 1 of the current contract. Mining noise spectra were selected and presented to a single subject seated in a diffuse noise field. The subject wore one of the muffs evaluated in the earlier study and was also fitted with two physical sound measurement systems. A linear system measured the "outside" noise level and a linear system plus "correction" filter measured the "in-side" noise level. These measurements indicated that, under the procedures presented in this report, a laboratory method for measuring earmuff attenuation is feasible and yields results comparable to an extensive psycho-physical procedure.

Jan 1, 1980

By Jean-Marc Lulin

"Depuis 1906, pres de 130 gisements ont ere decouverts dans la inture archeenne polymetallique (Cu, Zn, Au, Ag) du nord-ouest becois. Une etude regionale du developpement du potentiel inier est presentee puis detaillee pour quatre secteurs: RouynDranda, Val d'Or-Malartic, Bousquet-Cadillac et Matagami.L' analyse est conduite a l' aide des parametres suivants: temps, ethodes de decouverte, profondeur des gisements et poids metal. ~~ courbes cumulatives illustrant le nombre de gisements decouverts fonction du temps montrent une forme generale en ""S"" dont les i'iations de pentes correspondent aux variations dans les taux de ~ouverte. Initiation, realisation et stabilisation des cycles de decourte sont ainsi mis en evidence. Deux ""bourns miniers"", de 1922 a ~5 et de 1955 a 1965, rassemblent 72 % des mines identijiees squ' a present.La plupart des mines sont trouvees en subsurface: 90% ont leur fmet entre 0 et 100 metres de profondeur dont 70 % entre 0 et 10 etres. Dans le temps, il y ad' abord recolte par prospection puis par fphysique et enjin, developpement progressif du potentiel en proeur avec des methodes composites. Environ 80% du poids metal extrait de 4 camps miniers, couvrant 8% de Ia surface regionale quelques gros gisements dominent /a production.Ces donnees permettent de proposer une nouvelle approche pour lysed' une region miniere:La distribution de Ia profondeur des gisements en fonction du temps est indicatricede /amaturite d' uncampminieret peut servir a evaluer son potentiel residue/.L' analyse des courbes en ""S"" permet d' extrapoler les taux de succes relies aux differentes methodes et met en relief le role crucial de I' innovation dans I' exploration.ABSTRACTSince 1906, some 130 deposits have been discovered in the Archean polymetallic belt of northwestern Quebec. In this paper, the development of the mining potential is analyzed at the regional scale and for the following mining camps: Rouyn-Noranda, Val d'OrMalartic, Bousquet-Cadillac and Matagami.The analysis is based on the following parameters: time, discovery method, depth and weight of metal extracted. Curves showing the cumulative number of deposits discovered as a function of time are ""S"" shaped with slope variations corresponding to changing discovery rates. Initiation, realization and stabilization of discovery cycles are thus well represented. Two ""mining booms"", 1922 to 1945 and 1955 to 1965, account for 72% of the mines identified to date.Most exploitable orebodies have been found near the surface: 90 %have their top between 0 and 100 meters, including 70% between 0 and 10 meters. Early discoveries were made by prospecting, followed by geophysics while the progressive development of the depth potential is being realized by a combination of methods. Approximately 80 %of the metal extracted comes from four mining camps which cover 8% of the area, but most of the production can be allributed to only a few large deposits. Based on these data, a new approach to the analysis of a mining region is proposed:1) The distribution showing deposit depth versus time is indicative of the maturity of a mining camp and can serve to evaluate its remaining potential.2) The ""S"" curve analysis can be used to extrapolate the success rate of a specific exploration method and also stresses the crucial role of innovation in exploration."

Jan 1, 1990

By Jean-Marc Lulin

"Depuis 1906, près de 130 gisements ont été découverts dans la inture archéenne polymétallique (Cu, Zn, Au, Ag) du nord-ouest québécois. Une étude régionale du développement du potentiel inier est présentée puis détaillée pour quatre secteurs: Rouyn-Dranda, Val d'Or-Malartic, Bousquet-Cadillac et Matagami.L' analyse est conduite a l' aide des paramètres suivants: temps, méthodes de découverte, profondeur des gisements et poids métal. Les courbes cumulatives illustrant le nombre de gisements découverts fonction du temps montrent une forme générale en ""S"" dont les i'iations de pentes correspondent aux variations dans les taux de couverte. Initiation, réalisation et stabilisation des cycles de décourté sont ainsi mis en évidence. Deux ""bourns miniers"", de 1922 à 1945 et de 1955 à 1965, rassemblent 72 % des mines identifiées sqú à présent.La plupart des mines sont trouvées en subsurface: 90% ont leur mmet entre 0 et 100 mètres de profondeur dont 70 % entre 0 et 10 êtres. Dans le temps, il y a d' abord récolte par prospection puis par ophysique et enfin, développement progressif du potentiel en proeur avec des méthodes composites. Environ 80% du poids métal extrait de 4 camps miniers, couvrant 8% de Ia surface régionale quelques gros gisements dominent /a production.Ces données permettent de proposer une nouvelle approche pour analyse d' une région minière:La distribution de Ia profondeur des gisements en fonction du temps est indicatrice de la maturité d' un camp minier et peut servir a évaluer son potentiel résiduel.L’analyse des courbes en ""S"" permet d’extrapoler les taux de succès relies aux différentes méthodes et met en relief le rôle crucial de I' innovation dans I' exploration.ABSTRACTSince 1906, some 130 deposits have been discovered in the Archean polymetallic belt of northwestern Quebec. In this paper, the development of the mining potential is analyzed at the regional scale and for the following mining camps: Rouyn-Noranda, Val d'OrMalartic, Bousquet-Cadillac and Matagami.The analysis is based on the following parameters: time, discovery method, depth and weight of metal extracted. Curves showing the cumulative number of deposits discovered as a function of time are ""S"" shaped with slope variations corresponding to changing discovery rates. Initiation, realization and stabilization of discovery cycles are thus well represented. Two ""mining booms"", 1922 to 1945 and 1955 to 1965, account for 72% of the mines identified to date.Most exploitable orebodies have been found near the surface: 90 %have their top between 0 and 100 meters, including 70% between 0 and 10 meters. Early discoveries were made by prospecting, followed by geophysics while the progressive development of the depth potential is being realized by a combination of methods. Approximately 80 %of the metal extracted comes from four mining camps which cover 8% of the area, but most of the production can be allributed to only a few large deposits. Based on these data, a new approach to the analysis of a mining region is proposed:1) The distribution showing deposit depth versus time is indicative of the maturity of a mining camp and can serve to evaluate its remaining potential.2) The ""S"" curve analysis can be used to extrapolate the success rate of a specific exploration method and also stresses the crucial role of innovation in exploration."

Jan 1, 1989

By Arthur Notman

In view of the alarm expressed in many quarters over the increased production of copper to come from Canada and Africa in the future, it is of interest to study the history of the principal producing districts of the world and to attempt to forecast the future part to be played by them. Tables 1 and 2 record the world production and that of the United States, together with their respective rates of increase, both in percentage and actual amounts. The important point in this record is the decline in rates of increase for both the world and the United States, but more particularly in that of the latter, since 1881. The increase for the United States in the last decade is less than that for any decade since 1881, and is only 20 per cent of that for the decade 1911-20. The increase for the world is less than that for the two preceding decades, and is only about 65 per cent of the war decade 1911-20. Referring to Table 1, the decade 1871to1880 showed an increase of 32.l per cent in the world's production, which was the low until the last decade, ending 1930, which shows an increase of only 24.5 per cent. These decades both represent periods of economic stress following wars. In the first case the recovery was very sharp, the percentage increase in 1881-90 reaching a high of 86.4 per cent. It would seem dangerous, however, to assume that a similar high will be reached in the next ten years, because of the severity of the depression brought about by the Great War and the probability of its influence extending well into the next decade.

Jan 1, 1931