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By S. R. Borrowman

This investigation by the Bureau of Mines was undertaken to develop information on the extractive metallurgy of thorite ores because potential ore bodies of this mineral have been found recently in Colorado, Idaho, and Montana. Basic information on thorite ore treatment that would be useful in appraising the potential of these and other domestic thorium resources was developed. The work was done mainly on thorite ore containing 3.87 percent ThO2 from the Powderhorn district, Colo., and on a composite sample containing 0.52 percent ThO2 from the Wet Mountains district, Colo. Limited tests of d corroborative nature subsequently were made on a sample containing 2.30 percent ThO2 from the Lemhi Pass area on the Idaho-Montana border.

Jan 1, 1962

By Geo. S. Krueger

This paper, describing mining methods and costs at the Judge mine Park City, Utah, is one of a series being prepared by the Bureau of Mines on mining practices in the United states. ACKNOWLEDGMENTS The writers acknowledge the assistance of E. D. Gardner, supervising engineer, Southwest Experiment Station, Bureau of Mines; Paul H. Hunt, mine manager, Park Utah Consolidated Mines Co.; Wm. Osika, chief mine accountant; and Eric Neilson, assistant master mechanic of the mine.

Jan 1, 1938

Because of complex geological environments, a number of coal reserves occur in inclined or dipping coal seams in certain parts of the world. Longwall top coal caving using split-level a singleentry panel system (SSPS) has been widely used for extracting such coal seams with large thicknesses (greater than 6 m) in China because SSPS can reduce or mitigate problems of coal outbursts, gate road deformations, overturning of shields, downhill sliding of shearer and armored face conveyor (AFC), and so forth, during mining of inclined coal seams. Depth of yield is the range of yield coal from the rib of the pillar to the boundaries where yield ends. It plays a significant role in maintaining the gate pillar stability. This paper presents a study on the stability of an unconventional water-obstruction gate pillar (UWGP) formed by SSPS to prevent water inrush in mining of an inclined thick coal seam in a coal mine in China. As the shape of this pillar is non-cuboidal, nonparallelepiped, a conventional empirical or analytical method is not applicable for studying its stability.

Jan 7, 2020

By Yong Pan, Srivatsan Jayaraman Sridharan, Purushotham Tukkaraja

Block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate gas dilution situation when the source is located in the extraction drifts.

May 12, 2022

"El presente trabajo expone las pautas para la realización de un proyecto de fábrica de cemento, como los factores que influyen en su ubicación respecto al centro de distribución y el tipo de combustible que se emplea para la combustión. El impulso a la creación de una fábrica de cemento, se basa en la existencia de depósitos calcáreos, los cuales estratégicamente ubicados, permiten un mayor progreso económico del país y eliminan la limitación del suministro. Para tal fin, es necesario realizar un estudio económico del consumo considerando el período donde el abastecimiento y costo fueron normales. Otro estudio posible estriba en la comparación de la zona prevista de lde la fábrica con otras áreas de características económicas similares, basándose en la población, movimiento económico y otros elementos de comparación. Una vez determinada la zona, se fija el precio de la venta al público a través de tres elementos: precio de venta en fábrica, costo del transporte y la utilidad del distribuidor. Otros estudios a considerar son los basados en los yacimientos, los cuales complementan mejor la información de la instalación. Entre estos, tenemos a los estudios geológicos, levantamiento topográfico, muestreo sistemático, estudio químico de los minerales y pruebas térmicas y físicas de los productos. La ubicación de la fábrica dependerá si se decide instalar en el sitio de la cantera o en el mismo centro de distribución. Como estudio final, se prevee que la materia prima esté constituída por elementos que químicamente y mineralógicamente sean los más idóneos para así recurrir a materiales de complemento cuya dificultad o facilidad para mezclarlos íntimamente, determine el proceso a utilizarse. En consecuencia, la instalación de dicha manufactura, es el resultado del estudio global de las condiciones provistas en un zona, para así constituirse dentro de un mercado económicamente lucrativo. "

Jul 20, 1957

By K. Madhusudan Reddy

Pile response under combined uplift and lateral load is very important and it is imperative to evaluate the effect of combined loading and only few studies were reported on pile behavior under combined uplift and lateral loads. Model pile made-up of aluminum having an outer and inner diameter of 25.4 mm and 19.4 mm respectively is used. Dimensions of the model steel tank are fixed as 1.0 m x1.0 m x 1.2 m (depth) to avoid the boundary effects under combined lateral and uplift loads. Experiments were carried out on single piles at isolated uplift, isolated lateral loading and combined lateral and uplift loading, embedded in sandy soil. Results indicate that load?deflection behavior is nonlinear for isolated uplift and lateral load tests as well as in case of combined loadings. It is also observed that the behavior of piles under isolated loadings is substantially different when compared to combined loading.

Scenario reduction is designed for selecting a representative subset of geostatistical simulations out of a much larger set. Three steps are involved: measuring the dissimilarity between two simulations; finding a metric to measure the distance between any subset of k simulations and the full set of N simulations; and finding an efficient algorithm for selecting the subset that minimizes the metric. This paper focuses on the third question. We show that genetic algorithms are an efficient way of approaching the minimum when the population of subsets to be sampled is large. Two case studies based on the Walker Lake data-set are presented: firstly choosing k=4 simulations out of a total of 100, and secondly choosing 20 out of the same 100 simulations. In the first case it was possible to compute all possible combinations exhaustively and hence to demonstrate that the algorithm converges to the true minimum. This was not possible in the second case. Instead we demonstrate that it outperforms the random draw algorithm used in earlier work. A procedure for tracking individual selections during the iterative procedure was developed. This allows us to measure the evolution in the percentage of progeny resulting from crossing-over and from mutation that survived in the next generation. It gives valuable insight into how to choose the parameter values in the algorithm. Another key finding is that there is a trade-off between the number of individuals per generation and the number of generations required for the algorithm to converge.

Jan 1, 2014

By P. G. Corser

A gold and silver open-pit mine located in northwestern Chile contracted ACZ in 1991-92 to assess the stability of their spent ore pile and to determine the cause and magnitude of cyanide contamination associated with leaching operations. The mine is a conventional open-pit located at an elevation of approximately 4,800 meters (m.) (15,744 feet). A spent ore pile is located approximately 2,000 m. southwest of the mine and approximately 1,000 m. northeast of the active pad and plant facilities. The pile was constructed on a gentle northwest slope dipping 12 to 13 degrees. The pile is bordered by a small river to the northwest and by a larger river to the northeast. Both rivers eventually flow into Bolivia. Heap leaching and processing commenced at the mine in 1988. Since 1988, nearly 6.0 million tons of ore at an average grade of 1.96 grams/ton (0.07 ounces/ton) of gold and 52 grams/ton (1.83 ounces/ton) of silver have been treated by cyanide heap leach methods with zinc (Merrill Crowe) precipitation. In approximately three years of operation, the mine has yielded more than 225,000 ounces of gold and over 1.5 million ounces of silver. Currently ore is agglomerated and hauled to the leach pad by truck and is top loaded to produce a 5-meter lift height. Four contiguous reusable (on/off) leaching pads were constructed with an asphalt layer above a carefully compacted sub-base of High Density Polyethylene (HDPE) liner and screened fines. Leach solution of pH 10-11 containing 1.2 to 1.5 gram/liter of cyanide is applied to the heap at a rate of 10 liter/hour/square meter for a total active application period of 30 days. Leached (spent) ore is transferred to the spent ore pile located approximately 1,000 meters to the northeast. The pile currently contains approximately 6 million tons of spent ore. The pile liner, which has been constructed over a prepared sub-grade consists of three geosynthetic layers (geotextile/flexible membrane liner/geotextile). Long term objectives include washing the pile to recover an additional 3 to 4 percent gold and silver.

Jan 1, 1993

By S. Yaw Amponsah, E. Ben-Awuah, P. M. Takouda, P. Eme

Mining production scheduling is the process of determining the sequence of block extraction over a period of time that will yield the maximum net present value for a mining operation. The block extraction sequence needs to occur under certain resource constraints which presents an NP-hard problem that is computationally intractable and complex to solve for large scale problems using exact mathematical models such as Mixed Integer Linear Programming (MILP). In this paper, we used a metaheuristic optimisation model based on a Genetic Algorithm (GA) to solve the production scheduling problem. The problem definition and resource constraints are formulated using a mining specific GA that enforces block extraction precedence and mining capacity constraints through a normalisation method. A case study is implemented with the GA model, and the results and computational time are compared with that of a MILP model with CPLEX solver which is based on a branch-and-cut algorithm.

Sep 1, 2021

By Edward W. Parker

IF one is to place any credence at all in the reports published in the daily press, the subject of conservation has been a very lively topic of conversation during the past 60 days, and it does not appear that the temperature of the summer months has been in any way moderated by the discussion. It is a subject in which we are all vitally interested and to which, so far as our mineral resources are concerned, both the Institute and the Geological Survey have liberally contributed. The report of the National Conservation Commission, appointed by President Roosevelt, contains a series of papers on the conservation of mineral resources, all of which were prepared by members of the Geological Survey and were compiled largely from information previously collected by that Federal bureau in the performance of its regular duties. It is not the purpose of this paper to reiterate in extenso any of the material already published. The contributions of the Survey officials to the Commission's report have been published in a separate document as Bulletin No. 394. This docunient is for free distribution and may be obtained upon application to the Director of the Survey. In the preparation of this paper I desire merely to make a few suggestions regarding the possible necessity of some restraint upon or control of one branch of the mining industry with which I have been somewhat closely associated for the past 20 years-that of coal. Most of the members of the Institute are cognizant of the suits brought by the government against the anthracite-operators in Pennsylvania, or the combination of interests commonly known as the ? hard-coal trust." No defense of any illegal combination in restraint of trade is intended, but there are some facts which should not be lost sight of, and unfortu-\

Nov 1, 1909

By Francisco de Assis Altera

Os custos com reparos e substituições de peças, que são submetidas a trabalhos que proporcionam desgastes dos mesmos significam elevadíssimos gastos para as empresas. Os testes de campo geralmente são caros, além de necessitarem de um longo tempo para serem completados. A partir do momento que se notou a necessidade do desenvolvimento de materiais com maiores resistências ao desgaste começou a ser feitas várias pesquisas na área de desgaste abrasivo. De acordo com trabalhos realizados, pode-se concluir que existe uma grande variedade de parâmetros que influenciam os mecanismos de desgaste de maneira geral. Neste trabalho estudou-se o coeficiente de atrito bem como a resistência ao desgaste por abrasão em dois tipos de materiais, sendo uma amostra com revestimento de níquel e uma amostra revestida com liga binária de níquel com 7,3% de cobalto. O enfoque principal foi centrado na taxa de desgaste por abrasão, caracterizado pelo atrito de partículas entre dois corpos em contato. Como material abrasivo foi utilizado uma suspensão de diamante com diferentes granulometrias e foram aplicadas cargas diferentes, totalizando oito ensaios. Nestes, foi possível observar que maiores desgastes estão diretamente relacionados com material de maior dureza, abrasivo de maior granulometria e menor carga aplicada.

Aug 16, 2017

The ultraviolet spectrum of isopropyl ethylthionocarbamate (the principal constituent of Dow flotation collector Z-200) in water and of Z-200 itself in water was found to have an absorption peak at 242 nanometers(nm). The height of this peak was found to be directly proportional to isopropyl ethylthionocarbamate concentrations up to 15 p.p.m. Z-200 contains about 90 per cent isopropyl ethylthionocarbamate and the heightof the peak was proportionately lower, but obeyed the straight line relationship up to 15 p.p.m. This showed the potential value of spectrophotometric measurements for the determination of Z-200 residuals in flotation liquors.Methyl ethyldithiocarbamate (an impurity in Z-200) increased the peak height slightly, but other impurities in Z-200, xanthates, and most inorganic salts present in flotation liquors do not interfere. However nitrate ion and thiosulphate ion have absorption peaks which overlap the isopropyl ethylthionocarbamate peak.The simplest general method to overcome this effect is to extract the isopropyl ethylthionocarbamate into cyclohexane and to measure the absorbance of the extract.The maximum absorbance of the cydohexane extract was at 247 nm and the peak height at this wavelength was found to be directly proportional to the isopropyl ethylthionocarbamate or Z-200 concentration in the original aqueous solution. An alternative method is to measure the spectrum of the original aqueous solution using the aqueous raffinate from extraction as a reference solution. This gives the spectrum due to isopropyl ethylthionocarbamate alone and measurement of the absorbance at 242 nm gives the concentration in the original aqueous solution. Both methods give the same value for the concentration of isopropyl ethylthionocarbamate in the original solution.

Jan 1, 1969

By R. E. Cole, A. M. Gaudin

OLEIC acid, a standard flotation reagent, has generally been preferred to other fatty acids. Because oleic acid differs from saturated fatty acids by the presence of one carbon-to-carbon double bond and because the flotation operation is one in which extremely intimate exposure of the reagent to oxygen is obtained, it appeared possible that the value of oleic acid as a flotation collector was related to the oxidizability of its double bond. To test this hypothesis, the floated mineral, fluor-ite, was leached with a solvent capable of extracting the adsorbed reagent and the extract was analyzed.' Results show that oleic acid is not oxidized during flotation, although some oxidation can be obtained if the flotation operation is repeated many times and if oxygen in place of air is employed as the gas during flotation. Incidentally, it was found that lino-leic acid which has two nonconjugated double bonds is not affected appreciably more than oleic acid. Linolenic acid which has three nonconjugated double bonds is measurably altered even during one flotation step, using air. The fatty acids used, from the Hormel Foundation, were of the highest purity. The quantity of fatty acids employed in each test was sufficient to float the mineral, but less than the theoretical amount required to form a monolayer at the mineral surface. The purpose of this limitation was to eliminate droplets of oil smeared on the adsorbate-covered mineral surface. The mineral was dried in vacuum at about 60 °C. Effective leaching was obtained by use of a solution of 1 pct hydrochloric acid in absolute alcohol. The extract was separated from the solvent by distillation, with final recovery of the extract in carbon tetrachloride. The identity of the extract was tested by a combination of analytical procedures including infrared spectroscopy, saponification number, iodine number, and index of refraction. At the outset, great hopes for accurate quantification of oleic acid oxidation had been entertained in regard to the method of infra-red spectroscopy. Unfortunately, because the double bond in the oleic acid is so sym- metrically located at the center of the molecule that it provides very weak absorption bands, accurate quantitative analyses were not obtained. Nevertheless, infra-red spectrograms suggested the absence of double-bond oxidation during flotation. Iodine number, semi-micro method, provided a critical test of the extent to which fatty acids oxidized during flotation, see Table I. The index of refraction was used in a qualitative rather than quantitative fashion, and its findings corroborated those obtained by the iodine-number method. It is concluded, in the case of fluorite and C-18 fatty acids having one or two nonconjugated double bonds, that there is practically no change of the fatty acid molecule or ion during the flotation operation. It would appear, therefore, that the extraordinary utility of these reagents is related to some property of the compounds other than the oxidizability of their double bonds. Acknowledgment The research reported herewith was sponsored by the Research Division, U. S. Atomic Energy Commission, and for this help the authors express their appreciation. Reference 'R. E. Cole: "Double-Bond Reactivity of Oleic Acid During Flotation." Thesis submitted in partial fulfillment of the requirements for the degree of M.S. at the Massachusetts Institute of Technology.

Jan 1, 1954

By B. F. Naylor

"INTRODUCTION Investigation of the physical properties of electrolytic manganese and its alloys has constituted a part of the program of the Bureau of Mines for several years, and already extensive data have been reported. 3-14/ Heat-content measurements above 25° C. of pure manganese 15/ were completed recently at the Pacific Experiment Station of the Bureau, and the results obtained removed many of the inconsistencies in previously reported data. This paper reports heat-content data of seven manganese-copper alloys, varying in composition from 25 to 90 percent man-ganese. The alloys, obtained from the Salt Lake City Station, 16/ had been quenched from 850° C, and cold-worked. Without further heat treatment, heat-content measurements of each of these alloys were made at 100° or less temperature intervals from 450° to 850º C., as it was considered likely that any abnormal behavior of the specific heat would be found in this temperature range. Also, a portion of each alloy was heat-aged at given temperatures for periods of time thought sufficient to reach phase-equilibrium; then the heat-contents above 25° C. were determined at the aging temperatures. (Heat-aging was done at approximately 450°, 550°, 650°, 750°, and 850° C.)METHOD AND MATERIALSThe heat contents were determined by the ""drop"" method in a previously described apparatus. 17/ The calorimeter was cali-brated with electrical energy, measured in international joules, and the results were converted to the conventional thermochemical calorie by the relation, 1 cal. = 4.1833 int. joules."

Jan 1, 1946

By Gerald H. Luttrell, Seyed Hassan Amini, Aaron Noble

One of the most important processing engineering tools for designing mineral processing facilities is linear circuit analysis. This technique, originally conceived and developed by Meloy, Williams, and Fuerstenau nearly four decades ago, provides fundamental insights regarding how unit operations interact and respond when arranged in multi-stage processing circuits. Researchers have successfully utilized this tool to improve the operating performance of industrial processing circuits incorporating coal spirals, magnetic separators, mineral spirals, and eddy current separators. More recently, advanced versions of this tool have also been developed to provide a standardized framework for circuit mass balance calculations, to output exact analytical solutions to mass yield and value-based efficiency expressions, and to estimate uncertainty propagation in separation circuits. This article reviews the historical development of linear circuit analysis, describes how the technique has evolved to address more complex circuit design problems, and presents industrial case studies that highlight the importance of this process engineering tool.

By Bruce C. Trent

In order to effectively model subsidence caused by underground openings, a two-dimensional computer code has been developed which couples near- and far-field response. The near-field is simulated by a discrete element block code and a finite difference code represents the continuum region in the far-field. The explicit equations allow rapid and inexpensive solutions to geometries which may lead to subsidence. Two sample problems are presented which illustrate the important features of the code.

Jan 1, 1979

By Guillermo Florez Pinedo

Si bien la explotación de los recursos minerales influye en el desarrollo económico nacional, es necesario revisar el significado de la minería en el aspecto social y económico en el Perú a través de un plan maestro de desarrollo minero. En este sentido, el presente texto describe la estructura de este programa minero donde se evalúa los objetivos permanentes, las medidas de corto y mediano plazo, los recursos humanos, economía, tiempo, la estrategia de implementación y la acción empresarial del Estado respecto al desarrollo prioritario de la riqueza minera.

Nov 20, 1978

By M. J. Shulman

An algorithm used by the US Coast Guard to find lost objects is utilized to optimally allocate exploration efforts during initial stages of an exploration program. Based on classical search theory, the algorithm assumes a target probability distribution function, a detection func¬tion, and a cost function. The three Junctions are analogous to delineating areas of possible mineralization, choice of exploration methods, and exploration budget. Application of the algorithm is shown for a hypothetical target distribution. Using the maximum number of field days available as the cost function, the optimal allocation of effort is shown for different exploration methods, e.g. electromagnetic survey and induced polarization. The adaption of the algorithm for the exploration process is discussed.

Jan 3, 1984

By B. Swarbrick

Today’s mining occurs in a dynamic world of conflicting objectives. Mining companies have to look further than a traditional cash flow analysis to determine the potential value of developing a mine. In particular, proposals for new mine developments undergo rigorous scrutiny by a variety of stakeholders including regulators, NGO’s, and the local communities. From a business risk perspective, how mining companies address stakeholder concerns can have a dramatic impact on the success of the project. In today’s mining environment mining companies must continue to ‘walk the talk’ to stay in business, particularly during downturns in the business cycle. Falconbridge’s Raglan Mine is an example of a project that was successfully developed in a region that is sensitive from many perspectives, including environmental, socio economic, and regulatory. Close working relationships with local stakeholders along with strong environmental management systems are necessary elements of continued success for the project.

Jan 1, 2000

By M. M. Fine

"INTRODUCTION One of the principal activities of the Bureau of Mines during the recent war was to help to increase the supply of strategic and critical minerals. Fluorite was one of the most critical of the nonmetallic minerals because of the increased demand for it as a flux in basic open-hearth and electric steel furnaces and as a raw material for the production of artificial cryolite used in the aluminum industry. Wartime developments in the technology of hydro-fluoric acid, such as the use of the anhydrous acid as a catalyst in high-octane-gasoline production and the use of organic fluorides as carriers for insecticides, also increased the demand for acid-grade fluorspar. 2/ In 1943 the consumption of acid-grade fluorspar was advancing at a more rapid rate than production and was only slightly less than production during the latter half of the year.The outlook for the postwar market for fluorspar is encouraging. Steel production is expected to remain high until the domestic demand for commodities not manufactured during the war is satisfied. The uses for hydrofluoric acid also are expected to increase under the impetus of war-initiated research. In consideration of these and other factors some authorities predict a new peacetime demand for fluorspar equal to 60 to 75 percent of the war production, 5/ 6/ and others believe that the fluorspar industry will be permanently expanded. 7/"

Dec 1, 1947