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By E. A. Hartsook

Since World War II we have all been treated to repeated public and private evaluation of the population explosion. Improvements in medicine and agriculture have brought greater life expectancy and a decreasing infant mortality rate. This has brought boom conditions to some areas-and pressures everywhere for the amenities of life: a little elbow room, a tree or a pot of flowers, space to hike or swim with some freedom have all become premium commodities. With this wish for privacy and attractive surroundings, people are being forced to move to once sparsely populated areas. Suburbs expand or sprawl, depending on the point of view. New country is touched by a freeway and houses and stores spring up overnight. Entire new cities are born to meet the increasing mobility of industry and its work force.

Jan 6, 1965

By S. Goto, S. Yamashita, K. Hata

"The average consumption of zinc dust for purification of zinc leaching solution is more than 25 kg per tonne of electrolytic zinc. Authors proposed to remove impurities in zinc leaching solution by electrolysis instead of cementation by zinc dust. The effects of copper and arsenic on electrodeposition of cobalt in zinc sulfate solution were examined fundamentally using a potentiostat. It is observed that cobalt is easily deposited on a cathode at potentials under -480mV with arsenic. Mesh cathodes of stainless steel and lead anodes were used in a small electrolytic cell and the electrolyte was circulated through 'the electrodes during the electrolysis. The effect of electrolyte circulating rate , pH, cell temperature, current density, and concentration of copper and arsenious ions on removal of cobalt were studied. Removal of Cd and Ni are also examined.IntroductionCobalt is difficult to remove from a zinc leaching solution by a simple cementation reaction using zinc dust. However, it is easily precipitated by zinc dust with co-addition of arsenious or stibinous oxide and copper ion in practical operations(I), (2), (3). The consumption of zinc dust for purification is 16-152 kg per tonne of electrolytic zinc and 65% of this zinc dust consumption is used for cobalt purification. The average retention time for purification of cobalt is 4.5 hours (1). A more economical process for purification is desired instead of zinc dust. The mechanism of this acceleration effect of copper and arsenious oxide on removal of cobalt are explained by the authorsas follows; a galvanic cell is formed between zinc dust and copper which is precipitated firstly, and cobalt is reduced on copper as Co-As alloy by this galvanic current(2). This assumption was confirmed in experiments using a galvanic cell with a membrane( 4). The following galvanic reactions occur between zinc dust and copper precipitate; on copper cathode,2H+ + 2e -= Hz(g)2Coz+ + 2HAs02 + 6H ++ 10e -= 2CoAs + 4HzOand on zinc anode,Zn = Zn = 2+ 2e –This galvanic current becomes almost zero in a zinc sulfate solution which includes only cobalt and no arsenious oxide, and cobalt is weakly deposited on a copper cathode. Cobalt deposition requiers a high degree of cathodic polarization. However, the galvanic current flows almost constantly in an electrolyte, which includes arsenious oxide, and the cathode potential is kept at about -500mV. Cobalt is precipitated as Co-As on the cathode.The authors assumed that cobalt may be removed by electrolysis at a very low current density instead of zinc dust and the following experiments were carried out. In the first part of this paper, the fundamental experiments using a potentiostat on the behaviour of cobalt in zinc sulfate solution are described. In the second part, the results of the electrolysis are reported. Cobalt is removed by a new type of an electrolytic cell, which was desigoed to <Iccelerate the rate of deposition of cobalt. The removal of cadmium and nickel in a solution which includes cobalt and arsenic are also examined."

Jan 1, 1997

For the mineral industry, sustainability seems to mean socially positive and ecologically neutral mineral extraction. Mines are financed and developed in response to demand for their products. The purpose of my paper is to indicate the potential dimension of demand. As part of an unrelated study which I undertook ten years ago, it became apparent that there is a persistent relationship within communities between infant mortality and mineral use; greater mineral use corresponds to a lower rate of infant mortality. This comes as no surprise; sufficient potable water, a reliable supply of food, hygienic waste disposal, hot water and refrigeration all improve the chances of survival of the more vulnerable members of any community. The predictable provision of these facilities requires the application of minerals. This relationship is supported by a table (Appendix 1) included in the UNICEF publication, æThe State of the WorldÆs Children 2001Æ. This table lists regional infant mortality rate (IMR) statistics from around the world, including a listing for æindustrialised countriesÆ. Such countries experience an IMR lower by an order of magnitude than any other region. æIndustrialisedÆ inevitably involves the use of metallic and energy minerals. The principal use of copper is in the generation and distribution of power; it is fundamental to any industrialisation. IMR is a valuable connection because it quantifies caring for the young, a vital strategic driver of human behaviour independent of time, place, fashion or economic circumstances. I have tabulated the population, IMR and the copper demand per head of population for countries containing over 99 per cent of the population of the world in the years 1950, 1960, 1970, 1980, 1989, and 1999. These countries have been consolidated into four groups, Very High, High, Medium and Low rates of infant mortality (UNICEF has used this terminology; the Low group includes all the æindustrialised countriesÆ). The purpose of this consolidation was to reduce the volume of work, to dampen out the impact of regional wars and business cycles, and to dampen out the variable quality of information. Based on the pattern of the copper demand, population and IMR over the last 50 years, I have projected the likely copper demand in 50 years time. A dominant feature of my tabulation is the increase per decade in copper use per head and a corresponding reduction of the IMR. The word æuseÆ is preferred to æconsumptionÆ because it is estimated that over 80 per cent of all the copper ever mined is still in circulation There are two major influences at work; one is the absolute increase in population (UN estimates for 2050 are updated periodically) and the second is the movement of countries into a higher pattern of use and lower IMR. For example the Medium group in 1989 had an infant mortality rate approximating that of the Low group in 1960. With the population of the Medium group (which includes Russia and China) forecast to reach 2.6 billion in 2050, the world copper demand in that year will be significantly greater than the present figure. Nevertheless it will not be as great relatively as the increase of over 300 per cent in the last 50 years.

Jan 1, 2002

By J. W. Town

Recrystallization studies on chrome-bearing spinel materials were made by the Bureau of Mines to determine the effects of certain fluxing agents and cooling rates on the chromium-to-iron ratio of recrystallized spinel. Statistically designed and evaluated tests showed that the ratio of chromium to iron in naturally occurring chrome spinel could be increased from 1.5 to 1 to over 7 to 1 and that the ratio of chromium to iron in the chrome-spinel in a stain-less steel slag could be raised to over 18 to 1. Silica, magnesia, and lime had significant positive effects, while alumina had a significant negative effect. Cooling rates of 200 C per hour in a programmed spiral globar electric furnace were satisfactory for growing crystals of recoverable size.

Jan 1, 1967

By Chas. L. Emery

"The laws of rock mechanics apply equally well to all rock structures, and open pits are not exceptions. The concepts and some arguments about the emphasis to be placed on various aspects of open-pit design are discussed in this article.RocksROCK can be described as a granular material consisting of grains and glue. The grains may be fragments of other rocks or polycrystalline aggregates. The glue may be ferruginous, calcareous, argillaceous, siliceous or other material connecting the grains. In a crystal intergrowth, the outer layers of the crystals in contact with each other may be considered to act as a glue. Water may be a glue in clay or a grain in a crystal structure. Air and other fluids or gases are grains if they occupy spaces in a granular mass. Such grains are functional either chemically or mechanically or both."

Jan 1, 1966

By Peter D. Warwick

Recent investigations conducted by Federal, State, and industry organizations suggest that significant coalbed gas resources may exist in the Cretaceous and Paleocene-Eocene coal beds of the Gulf of Mexico Coastal Plain. Exploration efforts have focused on three areas which are in south Texas, north-central Louisiana, and south-central Mississippi (Figure 1). Coal-bed gas production is currently underway in south Texas and in north-central Louisiana. In Mississippi, several test wells have been drilled but no data are available on their production potential.

Jan 1, 2005

By R. Venkateswar, G. C. Sresty

Size measurement is important in characterization of fine particles. Commonly employed size measurement techniques such as sieving, microscopy, and sedimentation are discussed in this paper. Operating principles, advantages and limitations of these techniques are discussed based on the published information and working knowledge with several of these instruments at the authors&apos; laboratories. A brief description of the recently developed equipment for fine particle characterization is also included. At the end of the paper, a rationale is presented for selection of the size analysis equipment based on specific requirements.

Jan 1, 1980

Topography, location of coal bearing land and existing built-up areas severely restrict locations for overburden disposal and dumping sites north of the Latrobe River clear of the coalfields are assumed until internal dumping areas can be established.

Jan 1, 1982

By John A. Herbst, Per-Olaf Samskog, Jan Bjorkman, Yi Chang Lo

The study described here is concerned with the development of a model for the simulation and optimization of a rod milllpebble mill circuit. A series of laboratory tests was conducted to investigate the effect of critical operating variables. The pebble mill model structure used was a population balance type which accounta for impact breakage and fines production from pebble wear. Model parameterization and verification were performed using data obtained in batch tests and in a plant test campaign. The model developed was found to provide accurate predictions of plant-scale grinding. The prediction errors are less than 21 for the product size and 31 for the mill power required to achieve that product with a mill volume scale-up of 14,000 to 1. These results indicate that accurate extrapolations from laboratory batch data to plant scale performance are poaaible using the population balance model and scale-up prediction procedures for pebble mill circuits as well as ball mills. Preliminary indications are that the new model developed here will provide vital input for pebble mill optimization and process control as well as pebble mill design.

Jan 1, 1990

By Felix Shay

THE Agua Fria mine is in eastern Honduras at Lat. 140° 06&apos; N., Long. 86° 36&apos; W. Danli, the seat of the local municipal government, is the nearest town. The property is approximately 44 miles east of Teguci-galpa, the terminus of a truck road from the Pacific coast. The mine lies at an altitude of 3300 ft. with surrounding elevations as high as 6000 feet. For 20 years the oxidized croppings of the Agua Fria vein had been worked intermittently when in 1927 an attempt was made to open the property. A shaft was sunk 300 ft. and considerable ore was blocked out, but before a mill could be installed financial difficulties arose and the mine reverted to the original owners. Erle P. Halliburton, of Los Angeles, purchased the property in 1934. At that time a careful consideration of all factors involved showed that air transport was the only practical method of moving the equipment and machinery necessary to commence production. The other alternative was by muleback, which required sectionalizing all equipment to a maximum load of 200 lb., and during the rainy season this type of freighting was subject to serious delays. It was decided to purchase a trimotor Ford powered by three Pratt and Whitney Wasp B motors developing 400 hp. each. There were several reasons for the choice: (1) this type of plane was available at a reasonable price, owing to its replacement by faster models on most of the airlines in the United States; (2) the ship was capable of carrying a pay load of 3000 lb. over the required distance; (3) since this airplane had been widely used there would be no difficulty in securing competent personnel or in purchasing spare parts. It was necessary to rebuild the plane for cargo service. The windows were removed and the fuselage was entirely covered. A hatch was cut in the top of the fuselage to receive heavy crane loads and pieces of freight that were too large or too long to go through the rear door. The seats were removed and the interior of the plane was lined with Duralumin sheets. A heavy-duty landing gear was installed and the floor was reinforced.

Jan 1, 1940

By H. R. Grau

NIOSH’s Pittsburgh Research Laboratory is currently involved in research to identify silica dust generation in underground metal/nonmetal mines. The ultimate goal of this research is to develop control technologies to reduce worker exposure to respirable silica dust. Commodities and job classifications with the highest silica dust exposure have been identified through analysis of the Mine Safety and Health Administration (MSHA) compliance dust sampling database. Dust surveys were conducted in an underground limestone and gold mine to investigate silica dust sources, generation levels, and controls being used. A summary of the mining operations, sampling procedures, resulting data, and suggested methods to improve the dust control will be provided.

An assessment of methods currently available for the accurate determination of low concentrations of platinum in ores and mineral concentrates indicated that prior treatment of the sample by fire assay procedures is necessary. To enable rapid determinations to be carried out, instrumental methods applied to the metallic bead produced from the fire assay treatment have been evaluated, considering maximum flexibility for concentration variations, minimum chemical operations, and adequate sensitivity.Atomic absorption spectrometry proved suitable, giving solution determination limits of 0&#183;4 p.p.m. Pt, 0&#183;1 p.p.m. Pt, or 0&#183;06 p.p.m. Pt under various extraction conditions using aqueous and organic agents. Thesedetermination limits related to 1 assay ton of sample (32&#183;67 g) produced easily readable and accurate readings within the range of platinum contents (0&#183;03-2&#183;0 p.p.m.) of economic interest in deposit evaluation and prospecting. The technique shows promise of also being suitable for determination of palladium and gold.

Jan 1, 1970

By Raffaella Granata

The paper deals with the remediation of two areas formerly utilized for the disposal of hazardous wastes in a petrochemical plant. The works, designed on the basis of the criteria of maximum safety and minimum environmental impact, consisted in the confinement of the contaminated soil and groundwater within surface caps and perimetrical cut-off walls embedded in the underlying clay layer. The cut-off wall is 0.8 m thick and has a maximum depth of 33 m: it was designed to guarantee, as a minimum, the level of safety for a landfill for hazardous wastes, in accordance with the applicable National Standards. It was constructed with self-hardening mud and with the installation of an HDPE geomembrane. The HDPE liner of the cut-off wall was then sealed to that of the capping to obtain the complete encapsulation of the contaminated soil. A system of piezometers allows the monitoring of the cut-off efficiency measuring the fluctuations of the groundwater table and testing the chemical contents. Some wells installed within the contaminated areas will contribute to guarantee the full efficiency of the system in case of state of emergency, controlling the water-table level inside the confined areas.

Jan 1, 2006

Jan 1, 1923

By R. T. Hukki

The purpose of this paper is to present an analysis of the unit operation of grinding and the circulating load, of the unit operation of classification and the circulating load, and of the two superimposed into one operation to clarify the overall trend of events relating the circulating load to the capacity of the closed circuit grinding system, to the specific surface area of the final fine product, and to the energy consumption in the closed circuit grinding process. The capacity of the closed circuit is frequently, if not always, determined by the classifier, not by the mill." With these words a startling idea was expressed in 1934 by Dorr and Anable.1 Today, some 30 years later, grinding in closed circuit is universally accepted. The basic curve presenting the capacity factor versus circulating load by Dorr and Anable has obviously been so convincing that not a single authoritative investigation regarding its validity seems to have been conducted. The only major subject of discussion appears to have been the relative merits of the &apos;high&apos; and &apos;low&apos; circulating loads. It seems to be universally agreed that much still remains to be hoped for regarding sharpness of classification. BASIC CURVES FOR CONSTANT MILL LOADING Fig. 1 presents a series of basic curves for constant mill loadings in function of new feed rate and circulating load. The mill loading indicated by each curve is the sum of hourly tonnages of new feed and circulating load. For example, at point 0 where the new feed rate is 100 t/h and the circulating load 300%, or 300 t/h, the mill loading is 400 t/h. In closed circuit grinding, the new feed rate corresponds to the rate of finished classified material produced. Although at this stage the effect of classification is excluded in construction of the basic curves, the trend indicated by these curves is strongly in favor of closed circuit operation under relatively small circulating loads. A study of the curves reveals that, e.g., a mill operating under a load of 200 t/h at point P where the new feed rate is 50 t/h and the circulating load 300% will also operate under the same total load at point Q where the new feed rate is 100 t/h and the circulating load 100%. In other words, a reduction of circulating load from 300% to 100% would lead to doubling of the new feed rate and doubling of the rate of production of finished material, without a change in the total mill loading. The obvious question is, is it also possible by a reduction of the circulating load in a closed industrial grinding circuit to increase the production of finished classified material and, if so, how and to what extent? GRINDING TESTS BY DORR AND ANABLE In a series of open circuit grinding tests reported by Dorr and Anable1 limestone was ground at various feed rates in a 3-ft ball mill. The original data are reproduced in Table I. It can be seen that with the increased feed rate production of -65-mesh material increased and the energy consumption per unit weight of the -65-mesh product decreased in the reverse ratio. The data shown in Table I have been reproduced for our purposes in Table II for a scale corresponding to grinding in a large industrial mill. This reproduction

Jan 1, 1968

By T. Egleston

For several years 1 have been engaged in studying the behavior of iron and steel under varying conditions of tension and compression, as well as of shock and abrasion. Some of these observations have been communicated to the Institute at various times. Within the past year I have been looking at the various observations that I have made as a whole, and have been led to the conclusion that there is a regular law of fatigue and refreshment of metals, and that the change which produces either the fatigue or refreshment, is a. chemical one, which is, however, in almost all cases accompanied by physical and molecular changes at the same time. That metals under conditions that were more or less well understood became worthless, has been known for many years. It has been known to blacksmiths that iron and steel, when improperly treated in their fires, become "burned," as they call it, and could no longer be used, and some of them have had a scrap heap into which such material was thrown. A few of them knew that after a period more or less long the iron or steel recovered some of its original properties and could, with many precautions, again be used, but that these phenomena followed any law has not to my knowledge been announced. My attention was first attracted to the varying conditions under which iron and steel rails break in service. It was not long before I became convinced that there was a general law applicable to all metals which allowed of their being used with safety within certain limits, and caused their rupture when the use extended beyond these limits, and this law I have called the law of fatigue- of metals. When me observe the causes of deterioration in iron and steel rails, we find that they are principally shocks, either slight and frequent, like those produced by the passing of a train over a road-bed in good order, which produces a vibration sensible to the ear laid on the rail, for very long distances, but distinctly audible for only a short one; or from sudden and heavy blows, like the descent of the locomotive and each car successively from a high to a low rail.

Jan 1, 1880

By David Martell, Wilf Ingram

For over 100 years mine hoists have been used in Cape Breton Coal mines which are situated on the eastern coast of Canada. Most of the coal seams have been inclined and as the mine advanced, longer lengths of haul were required. This paper describes the successful operation of slope hoists with rope capacities of up to 6100 m (20,000 ft.) at Cape Breton Development Corporation. A general description of the hoists is given. The braking systems, controllers and man riding cars used are discussed. The operational problems of using such long lengths of rope are described.

Jan 1, 1981

By P. R. Taylor

Three refractory gold concentrates have been tested to evaluate the effect of roasting with hydrated lime followed by cyanidation. The results indicate that it may be possible to roast in such a manner as to contain nearly all of the sulfur, arsenic and antimony in the roaster calcine. Cyanidation results indicate that the gold recoveries are greater than 80% for all three concentrates.

Jan 1, 1993

"Standing 92 stories high and just over 1,362 ft tall, Chicago’s Trump International Hotel and Tower is perfectly positioned at the center of one of the world’s most impressive skylines.The Tower serves as a link between its famous predecessors, Willis Tower (formerly, the Sears Tower) to the south and the John Hancock Building to the north. Originally planned to be the world’s tallest building, the project was scaled back when the developers started questioning the need for super-tall buildings after the September 11, 2001 terrorist attacks. In its River North neighborhood, Trump Tower dominates the skyline as a symbol of Chicago’s last great building boom, standing triumphantly over other high-profile projects that have been postponed due to current economic realities.It is often said that the three most important factors in real estate are location, location and location. This maxim was not forgotten by The Trump Organization when the site was selected for the International Hotel and Tower. Located two blocks west of Michigan Avenue and Chicago’s famed Magnificent Mile, the site is bound by the historic Wrigley Building to the east, Wabash Avenue to the north and west, and the Chicago River to the south. The building’s position along a bend in the Chicago River allows visitors and residents unobstructed views to the mouth of the Chicago River and Lake Michigan. Site ChallengesUnderneath the site there are approximately 10 to 20 ft of sand and urban fill underlain by soft Chicago blue clay. At 75 ft in depth, the soft clay transitions into Chicago hardpan, a very hard till that was consolidated by the glaciers over 10,000 years ago. Below the hardpan, the till turns granular with cobbles, boulders and water under pressure. Bedrock is about 100 ft below existing grade and has a weathered surface with fractures and clay seams. Unweathered limestone bedrock is sound and hard with unconfined compressive strengths of 10,000 to 20,000 psi."

Jan 1, 2009

By P. Worley

With Utah Power & Light Mining Division&apos;s commitment to operate the safest and most productive mines possible, a decision was made to purchase and install mine-wide monitoring systems for use in the mines. After review of several different systems the Conspec Senturion 200 system was chosen. Three separate systems were ordered to fulfill the monitoring requirements of the six mines in operation: one system for the Deer Creek Mine one for the Wilberg/Cottonwood complex, and one for the Deseret, Beehive and Little Dove complex.

Jan 1, 1989