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By Foster Fraas

The electrical conductivity of minerals increases with increase in temperature as a result of the thermal activation of the electrons. Some oxidizable minerals have a change in the stoichiometric proportions after heating in air, and the conductivity does not return to the original value after cooling. Similar changes occur in reducing atmospheres. Other minerals, such as carbonates and hydrates, are completely decomposed. Electrical resistivity measurements on single particles when compared to standard separation measurements show that minerals having resistivities above 1013 ohms respond as nonconductors. Those below 1011 respond as good conductors.

Jan 1, 1956

By Tim Chapman

This general report considers what promoters of deep basement projects want from their teams and whether they get it often enough. Most large projects are based on complex financial models where the funding is related to a future income stream. Project delays and cost over-runs can critically affect the financial model. Too often, delays and cost over-runs originate in the substructure and foundations. We must take positive steps to improve our industry's reputation for reliability.

Jan 1, 2006

By John Campbell, E. S. Baker, G. W. Jones

"INTRODUCTION In previous reports 5,6./ results were given showing the amount of natural ventilation that takes place in manholes (capacities, 74.1 to 308 cubic feet) when the number of ventilation openings in the manhole cover ranged from no openings to a maximum of 4g.The tests warranted the general conclusion that the ventilation or air changes taking place in, a manhole increase as the area of openings in the cover of the manhole is increased, and are proportional (with the exception of a few erratic tests) to the area of the openings in the cover. The area of the openings was the chief factor that affected ventilation.The results did not show any marked change in rate of ventilation due to increased capacity or shape of manhole, when the results were expressed in terms of air changes per day versus area of ventilation openings in square inches per 100 cubic feet of manhole space.It was observed during these investigations that in certain tests that showed erratic results (that is, did not agree with the general average for a given set of test conditions) the wind velocity during the test period was also abnormal. In view of these findings it was decided to conduct a series of tests in which the wind velocity across the openings in the manhole cover could be controlled accurately to determine the effect of wind velocity on ventilation rate."

Aug 1, 1938

By John H. Soulé

"INTRODUCTION The Mining Branch of the Bureau of Mines has used the wagon drill to sample mineral deposits in New Mexico. This method of sampling was successful and con¬stituted an important phase of the work on five exploratory projects undertaken in 1943, 1944, and 1945. The deposits varied in topographic features, geology, mineral content, and in the physical characteristics of the rocks drilled. The altitudes ranged from 630 to 7,800 feet. Three hundred and seventeen holes totaling 6,852 feet were drilled. The deepest hole was 66 feet; the average depth was a little less than 22 feet.The results of the above-mentioned work form the basis of this report. Special attention is given to the later and more improved techniques used. This report was written with the expectation that the procedures might prove advantageous to others in the exploration and sampling of near-surface mineral de¬posits, and that a more extended use of the technique might result.AcknowledgmentsAcknowledgment is due Charles H. Johnson, chief of the Rolla Division, Mining Branch, for helpful suggestions in starting this work, and to J. H. Hedges, chief of the Tucson Division, Mining Branch, W. R. Storms, engineer-in-charge of the Silver City, N. Mex., Field Office, and Donald H. Mullen, mining engineer attached to that office, for assistance in preparing and editing this report."

May 1, 1947

By J. R. Mackie

Reserve Mining Company, the first large-scale taconite pellet producer in the United States, mines it's crude ore at the Peter Mitchell Mire located on the eastern end of the Mesabi Iron Range near Babbitt, MN. The ore is processed at Reserve's beneficiation plant on the north shore of lake Superior at Silver Bay, M. The mine and plant are linked by a 47 mile, double track, railroad which is owned and operated by Reserve. (see Fig 1). At rated capacity, the mine can produce 33 million It/yr of crude ore, 15 million It/yr of waste rock and 1.0 - 1.4 million yd3/yr of glacial till stripping. Haulage of all mined material is accomplished using trucks. Ore is transported by tractor-trailer side dump units which have capacitys ranging from 83 to 110 long tons. Waste rock and glacial till is transported in end dump units of 50 to 120 LT capacity. Loading is accomplished by 11/13 yd3 power shovels and 7/10 yd3 front-end loaders.

Jan 1, 1985

By Y. S. Li

The life cycle assessment method is applied to investigate the environmental impacts of cop-per-slag and copper-ore concentration process. Some environmental load data of copper production are obtained. The result indicates that damage level of human health, ecosystem quality and re-sources respectively is 0.174, 0.0203, 0.246 in the copper-slag concentration and 0.112, 0.0136, 0.299 in the copper-ore concentration. Environmental impact of copper-slag production (0.44) is more than that of copper-ore production (0.42), but can meet the environmental protect demand. With domestic copper concentrate supply gap enlarging, recovering copper from slag will lead to a significant improving of resource utilization and development of circulation economics.

Jan 1, 2014

By Susanne Pignolet-Brandom

Flash smelting products of a copper sulfide concentrate collected at successive levels in an experimental reactor have been studied by reflected light microscopy, scanning electron microscope - energy dispersive analysis and electron nicroprobe analysis. Chalcopyrite, intermediate solid solution, bornite, chalcocite, metallic copper, magnetite, iron-copper spinel, pyrrhotite, hematite, delafossite and cuprite have been identified in the product samples. The detailed reflected light microscopy study of these phases and their abundance in the samples has resulted in the identification of the series of reactions during flash smelting.

Jan 1, 1985

By Izabela Diniz Duarte

O controle da temperatura do aço líquido desde o refino secundário até o lingotamento é condição essencial para alcançar alto nível de qualidade do produto final e economia de energia, o que permite ressaltar a importância de se determinar as perdas térmicas na panela. Entre outros fatores este trabalho buscou identificar a importância relativa das perdas térmicas para o revestimento refratário e através da escória. A temperatura, espessura da camada de escória, temperatura do revestimento refratário, propriedades físicas e características de convecção foram os fatores considerados. Cálculos numéricos que quantificam essas perdas.

Jul 30, 2018

By M. J. Russell, W. E. Stephens, D. B. Mohamad, A. B. MacKenzie

Redox front processes in rocks are important in the context of both radioactive waste disposal and the development of orebodies. Results are presented from a study of the distribution of uranium and thorium and the natural decay series equilibrium about redox fronts in a granite at the Criffel pluton and Craignair quarry, Dalbeattie in southwest Scotland. The results are considered in the context of large scale uranium aqueous transport in the region and compared with those from a previous study of highly developed redox fronts at Pocos de Caldas, Brazil. Results show that the Criffel pluton has experienced a recent and rapid removal of uranium from the uppermost section of the granite whereas thorium has remained relatively immobile. The radium and uranium distributions indicate that diffusion processes probably control the distribution of radionuclides about the front. These processes are similar to those observed at Pocos de Caldas. The trends of concentration and activity ratio about the Dalbeattie redox front are less pronounced than those at Pocos de Caldas owing to the shorter time available for the process and the lower intensity of weathering at Dalbeattie.

Jan 12, 1992

By J. C. Yannopoulos

The quest for a continuous copper smelting and converting process, which has been going on for a long time, has not as yet reached its objective. The most recent efforts for the development of a continuous copper?making process started about two decades ago. Among the contending proposed processes, four have been piloted and three of them are currently in operation: the WORCRA process., the NORANDA process, the MITSUBISHI process, the OUTOKUMPU process. The WORCRA process, after some long pilot plant tests, failed to develop as an industrial process: The NORANDA process, as currently operating, is a smelting process and not a continuous copper?making reactor as initially conceived. The MITSUBISHI, although the only continuous process, has not been widely accepted. The OUTOKUMPU process can be applied only to a low iron concentrate feed and co?produces blister and high in copper slag. The thermodynamics of these "continuous" systems and the practical problems of their industrial application are reviewed and discussed. The achievement of efficient and inexpensive environmental control should' be the primary objective of any new process development. A review of the environmental problems of the copper industry indicates that the quest for a continuous smelting and converting furnace should be intensified.

Jan 1, 1983

Jan 1, 1980

By A. Çelik

Wheel loaders are widely used in many sectors due to their mobility, operational flexibility, and low costs. The literature is mainly focused on improving the hydraulic, mechanical, and electronic subsystems of these machines in terms of efficiency or developing strategies for controlling these systems. In this study, the effects of the loader operator and different working conditions on the loading performance were investigated. The study was carried out at the Can Lignite Enterprise (CLI), which is a major coal producer in Turkey. In the study, which lasted approximately four months, a total of 808 measurements were performed to investigate seven different scenarios. The effect of a single parameter on loading performance was investigated in the first six scenarios. The results showed that the biggest impact on loading performance was caused by the operator's experience with 63.4%. On the other hand, the worst and most ideal working conditions determined from the first six scenarios were tested in the seventh scenario. It was tested as a script. The test results showed that the loading performance was 285.5% more effective under the most ideal operating conditions compared to the worst operating conditions. In addition, in the study, the loading performances of five loaders with four different capacities were examined in terms of energy efficiency and it was determined that the Kawasaki 115 work machine, which has a higher model and lower engine operating hours, was more advantageous. In the study, various suggestions were developed in parallel with the research results. The most prominent and easiest to implement of these suggestions is related to the selection of the loader operator.

Nov 27, 2024

By R. W. Nash, A. E. Schwaneke, V. R. Miller

The Bureau of Mines developed a detector for controlling sorting devices to separate the copper-bearing fragments from the barren portion of Michigan native copper and western prophyry copper ores. A successful sorter could be used to preconcentrate the ore and eliminate costly hoisting or hauling of waste. An induction balance unit was developed and used in sorting tests on crushed sized - 2.5 + 1. 3-cm (- 1 + 1/2- in.) ores from the Kingston (0.9% Cu) and Centennial (1.6% Cu) mines of Upper Michigan. Concentrates of 4.0% and 7.5% Cu, respectively, were obtained at recoveries of 85 and 80% of

Jan 8, 1978

By F. H. Mertens

The costs of an open-pit operation can be classified according to the following hierarchy : -overall cost of production (per ton of ore) -costs of basic operations and functions -costs of auxiliary operations -costs of machines and equipment -maintenance costs. Production cost is a measure of the open-pit mine performance and should be the final target of the management control. It is also a measure of the share of the mine in the processing stages.

Jan 1, 1990

By Clinton Birch

The multiple-criteria decision analysis is a technique that helps to find an optimal solution by evaluating conflicting criteria. In this study, an approach to perform multiple-criteria decision analysis for cut-off grade optimization, which considers the diverse stakeholder groups prevalent in the mining industry, is presented. The optimization model developed in this approach links the resource block model to the financial model, enabling the process to either maximize profit, net present value, revenue to the State, or extend the mine's life. To identify the optimal cut-off grade in each case, the Excel Solver function is utilized. Although it has limitations, the Solver function can still be modified to handle models with thousands of block values for determining input variables based on the target value. Following stakeholder engagement and dialogue, a single weighted average cut-off grade can then be determined. This approach is demonstrated for nine South African Witwatersrand gold mines.

Jun 25, 2023

By Thomas M. Barczak

The performance characteristics of Mobile Roof Supports (MRS's) were evaluated through full-scale testing in the Strategic Structures Testing Laboratory at the National Institute for Occupational Safety and Health, Pittsburgh Research Center. Safety issues pertaining to the operation and design of these supports for pillar extraction during retreat mining are examined. A unique load frame, called the mine roof simulator, provided a realistic simulation of mining conditions by inducing vertical, horizontal, and lateral loading on the support. The purpose of these experiments was to determine the capabilities and limitations of the supports and to investigate factors that influence the measurement of loading and loading rate. An evaluation of the support design and load conditions that can cause support failure or loss of support capacity are discussed relative to the laboratory tests. In general, lateral loading perpendicular to the longitudinal axis of the canopy is most severe, although horizontal loading in the direction of the long axis of the canopy can also produce critical loading in some cases. The experiments indicate that both setting force and leg pressure measurements are influenced by the staging of the leg cylinders. The implications of these factors on load rate measurement are evaluated. A comparison of MRS capacity and stiffness characteristics is made to conventional timber supports.

Jan 1, 1997

By B. S. A. Tatone

The surface roughness of unfilled rock discontinuities has a major influence on the deformational and hydraulic behaviour of discontinuous rock masses. Although it is widely recognized that surface roughness is comprised of a large-scale (waviness) and small-scale (unevenness) components, most investigations of surface roughness have been restricted to small fracture surfaces (< 1m2). Hence, the influences of the large-scale components of roughness are often neglected. Furthermore, these investigations typically focus on analyzing roughness in terms of two-dimensional profiles rather than the complete three-dimensional geometry, which can lead to potentially biased estimates of roughness. This contribution demonstrates the use of a new optical digital measurement system, based on the principle of triangulation, to digitize a large-scale natural rock discontinuity surface at both outcrop-scale (~6m x 2m) and lab-scale (~100mm x 100mm). Subsequently, the digitized surfaces are systematically analyzed using the three-dimensional roughness methodology proposed by Grasselli to investigate the dependency of roughness on sample window size and measurement resolution.

May 1, 2009

By Sara J. Davenport

Hydrogen sulfite has been listed (1)3/ as a possible hazard in 50 occupations, many of which are in the mineral industries. The effects of its occurrence in the petroleum industry made themselves felt more than two decades ago, resulting in a comprehensive study (2) of the toxic gases from Mexican and other high-sulfur petroleum products. The mining industry, likewise, has had cause to guard against this gas. Enough hydrogen sulfide has been found in coal and some noncoal mines during normal operations to cause severe eye irritation, some serious illness, end even fatalities. It is usually a product of the decomposition of sulfur compounds and may be produced by burning explosives containing sulfur; the gas in harmful qauntities is formed by the use of block blasting powder or by the use of dynamite in blasting sulfide ores. Hydrogen sulfide is readily soluble in water, and enough may be released from water streams in coal and noncoal mining to cause fatal poisoning it is found sometimes in stagnant water underground, particularly where ventilation currents are absent, and great care must be exercised when accumulations of such waters are disturbed, as exposure to comparatively low concentrations of the gas evolved therefrom has caused fatal accidents.

Jan 1, 1945

By N. Dufresne

"The evolution of mining methods at Brunswick Mining and Smelting shows that, in the case of a large deposit, technology must adapt itself to changing conditions. As problems are encountered, management must modify their approach if they hope to meet production quotas. This search for new and better ways started with the opening of the No. 12 orebody and is still going on today.From large-scale open stoping, the Brunswick Mining and Smelting operation went to transversal cut-and-fill, then to longitudinal cut-and-fill, which is the main mining method now employed. However, to solve certain problems experimenting with Avoca methods was initiated. Rebar grouting and prepinning have also made significant contributions toward securing relatively poor ground in the hanging wall and holding badly fractured backs in wide stoping areas. Introduction In 1952, M.J. Boylen had incorporated Brunswick Mining and Smelting Corporation Limited to develop his recently found No.6 and No. 12 orebodies near Bathurst, New Brunswick. Between 1953 and 1957, St. Joseph Lead Company was brought in to try and initiate mining . During those years, St. Joseph Lead sunk two shafts at No. 12-No. 1 to 425 feet below surface and No.2 to 982 feet. They also developed the 200 and 350 levels to sample the ore at depth and operated a 100-tpd pilot plant at the No.6 mine. However, due to low recoveries and depressed metal prices. the project was shut down in 1957.A group including M.J. Boylen. K.C. Irving. Maritime Mining Corporation and Patino Corporation reacquired the property from St. Joseph Lead Company in 1961. New financing was arranged involving La Societe Generale des Minerais, S.A . of Belgium and Engineering Consultants Limited of Saint John. New Brunswick. During the years 1962 and 1963, construction of surface and underground facilities progressed rapidly."

Jan 1, 1981

By F. Segobia, H. Lozano, M. Portal, F. Ysla, L. Goicochea

This case study evaluates the long- term physical stability of various historical mining structures remediated by the Center for Mining Environmental Research and Studies (CIEMAN) in Hualgayoc, Cajamarca, Peru. The region has a long history of mining activity, with remnants dating back to pre-Inca times. CIEMAN has assumed responsibility for remediating 286 environmental liabilities in the area, including adits, shafts, pits, tailings, and waste rock dumps. The study analyzes the methods employed to stabilize these structures, including geotechnical engineering techniques and revegetation. Long-term monitoring results are presented, assessing the effectiveness of remediation measures and predicting the future stability of the structures. This study highlights the importance of responsible remediation of mining environmental liabilities to ensure the safety and sustainability of communities and ecosystems affected by historical mining.

Feb 1, 2025