Search Documents

By Felicia F. Peng

The plant data were collected from three streams around a dense medium drum for coarse coal cleaning operated at various volumetric ratio of medium-to-feed. The effect of the volumetric ratio of medium-to-feed (MF) and particle sizes on the performance criteria, g50 and Ep, of the dense medium drum. These measured data were adjusted and calculated for the yields and balanced relative density distributions by mass balanced method based on the statistic principle. These balanced data were then used to formulate the mathematical models of the separation distribution curves for the various feed size intervals. The correlation equations for the g50 and Ep as the function of inverse of the feed size, and MF and total throughput were established. A numerical algorithm utilizing the Secant method, based on the root searching principle, was developed for yield optimization and simulation of dense medium drum separation to improve the separation efficiency and hence the product yield. The relationships between the direct ash content and relative density of the particles in feed and the products were established and incorporated into the numerical algorithm for predicting the product quality.

Jan 1, 1996

By D. Jenkins

THE Franklin Laboratory was designed mainly for the analysis of the products from the two concentrating mills situated at Franklin and Sterling Hill, the most important determinations being the zinc, iron, manganese, lime, moisture and silica contents of the ores. Within the last 4 years, however, it has been found advisable to examine most of our supplies, and therefore additional space and equipment was allotted for the examination of such substances as oils, greases, soaps, alloys, fuels, paints, explosives and water. The building as shown in elevation (Fig. 1) and plan (Fig. 2) consists of a main or routine laboratory, an experimental laboratory, a water FIG. 1.-WEST ELEVATION. analysis room and the other accessories such as stock room, library, sampling and drying rooms and office. The main laboratory is further divided into a balance room and zinc analysis room. As the greater part of our determinations are volumetric, good light is a very important factor and with this in view the interior walls of the building were constructed of white enameled brick laid in Keene cement. These also have the additional advantage that they give a clean and attractive appearance to the room. The windows are large, being 76 by 44 in. and even on very dark days the light is good throughout the whole laboratory. Our zinc titration requires a constant light and as, on many days, especially in winter, the light is variable, we installed two Artificial

Jan 8, 1917

By Jean Vavrek, Rob Barber

"What is CIM’s role on a planet-wide scale?That question has been coming back to the forefront of many discussions regularly in the months since we came on board as Executive Director and Vice- President International. CIM, by its name and by the nature of its history and make up, has mainly been a Canadian entity. It has been created by an act of Canadian Parliament and it is set up to work within the Canadian federal and provincial framework.Yet the name CIM is one well known and recognized for quality and professionalism worldwide. One could say that CIM has established a level of brand recognition that transcends it name and its origin. CIM has also evolved with the times, as the world has evolved and more so as the world of mining has evolved. So we stand today with a fairly large portion of our membership residing outside Canada and outside the United States. We also stand today looking back at the role CIM has played in events that we have been partners in organizing outside Canada; and for a long time CIM has provided insights into what is going on in the rest of the mining world by inviting authors and by featuring topics from around the globe.Today, Canada is still a leader in the mining industry. Canadian mining companies are involved in exploration and operations around the world. Canadian operations serve a good portion of the global demand of many metals and minerals, recently adding diamonds to the slate. Canadian expertise in various areas also makes Canada a good base for exporting a wide range of products and services around the world."

Jan 1, 2004

By C. K. Leith

GENERAL GEOLOGY OF THE LAKE SUPERIOR IRON-BEARING AND COPPER-BEARING SERIES. THE geology of the Lake Superior region is of general interest, both from an economic and a scientific standpoint. The presence of large and rich iron- and copper-deposits has made a knowledge of the geology of the region necessary for purposes of exploitation and exploration. The ores of the region are contained in rocks of pre-Cambrian age, 'pith for most of the country up to recent years have usually been referred to as « crystalline schists " or " crystalline complex;" and regarded principally as metamorphosed basement-unit upon which the sedimentary rocks, beginning with the Paleozoic, were laid down. In the Lake Superior re¬gion this pre-Cambrian complex presents an unusual variety of rocks with determinable relations. It has been possible, with the large expenditures which-the magnitude of the iron-mining industry warrants, to work out their stratigraphy to a larger extent than has been possible in almost any other area of pre-Cambrian rocks. The real complexity of Lake Superior geology, the confusion of names and the multiplicity of reports covering small parts of the region, are such that interested persons, other than. geologists directly engaged in the work, may well hesitate to attempt to comprehend the geology of the region as a whole. The following paper is a somewhat elementary outline of the geology of the Lake Superior region with special reference to new developments not yet covered in published reports. Geological information concerning the region has been gath¬ered by mining companies, and by the geological surveys of Michigan, Wisconsin, Minnesota, Ontario, Canada, and the United States.. Perhaps in no other part of the country have the mining men themselves spent such large sums in purely geological work. This has made possible the publication of ,reports and maps by the State and Government surveys in much less time and at far less cost than would have been otherwise possible. The. U. S. Geological Survey is the only organization which has covered all of the region on the United 'States side of the boundary, and as its reports include the in¬formation gathered by the mining companies and State organi

Mar 1, 1905

By J. Duran

Mining at Newmont Mining?s Phoenix?s Mine is currently done by surface operation in the Fortitude and Bonanza pits at a combined rate of approximately 100 kt/d (110,000 stpd). A portion of the orebodies targeted by these pits was mined previously by underground mining methods, dating back to the mid-to late-1800s. Most of the underground workings (voids) are located in the west central area of the Bonanza pit. The surface operation requires excavation through voids, and there is a risk of pit floor subsidence that has to be addressed. This article presents a review of the risk mitigation measures that were implemented to reduce risks to people and equipment working in the area.

By Yan Yang

The Jinfeng gold mine is one of the three gold mines that Eldorado Gold has in China and it is the second largest gold mine in China. The mine is located in a relatively remote and mountainous area in the southwestern Guizhou province. The orebody is similar to the Carlin type deposit in Nevada. The mill throughput was designed to treat 3,600 tones per day. The ore comes from open pit mining and underground mining, and is fed to one-stage jaw crushing. The crushed ore is stockpiled, reclaimed and then fed to the SABC grinding circuit. After classification with hydrocylones, the ore is floated, and the resultant concentrate is oxidized biologically in a process known as BIOX®. The oxidized concentrate is then washed in a CCD circuit and finally leached with cyanide in a CIL circuit for gold extraction. Jinfeng produces about 180,000 oz of gold per year. This paper introduces operations and modifications of SABC circuit over the past three years, and then describes some technical characteristic of the SAG mill and other circuits in the processing plant. Major modifications and improvements on the SABC circuit are described in the paper, including: 1. Impacts of grinding ball and mill liner with respect to material selection, quality, hardness, manufacturing methods, and interactions between mill liner and grinding ball. 2. Effect of milling operation parameters on milling efficiency. 3. Impacts of SAG mill scats and modifications of grate size to improve mill throughput. 4. Design and construction of a pebble crushing system, and recycle the crushed scats to the SAG mill to improve mill throughput. With the above-mentioned modifications, 20% increase over the design in mill throughput has been realized over the past three years, and operating cost has been significantly reduced. However, some issues still remain, and thus process modifications and technical innovations are still needed.

Jan 1, 2012

By M. Fiset, D. Belley

"In a country with a cold climate like Canada, the cost of replacing worn parts of snowplow equipment such as blades, is enormous. A great number of these blades, with different mechanical properties, are available, but few studies have been made to facilitate their selection according to the optimum ratio of wear resistance to cost. To attain this objective, laboratory tests have been developed to correlate test results with those obtained from various road service conditions. The test materials, 1080steel in different states, 1090steel and D2 tool steel were chosen to cover a large range of hardness as well as different microstructures. Comparison of the wear resistance of the test materials relative to a standard revealed, in general, a good correlation between the results of laboratory cement wheel tests and those from the road tests. Scanning electron microscope wear scars of laboratory and road test specimens were compared to determine if similar removal material mechanisms were active. IntroductionThe correlation between wear tests in service and those performed with the aid of laboratory equipment is of considerable interest. As a matter of fact, when correlation exists, it allows one to evaluate the performance of a material more easily and at a lesser cost.Several authors have been interested in simulating various wear circumstances, especially abrasive wear. In particular, the simulation of wear on implements working the soil, has been tried by several researchers. The test using the rubber wheel seems to be the one giving the best correlation if the soil is rather sandy and its moisture content is low.However, little work has been done concerning wear on the plates, skids and blades attached to trucks used for levelling and snowplowing; such equipment being used to keep roads clear in northern countries. Now each year, companies introduce new steels by claiming that the y are superior in performance to their predecessor s and invariably they demand a higher cost. The study presented here was undertaken with the goal of making a more judicious choice of these steels by simulating their behaviour in the laboratory. Moreover, the examination of abraded surfaces in situ and in the laboratory have also allowed us to compare the respective wear mechanisms."

Jan 1, 1988

By Robert H. Essenhigh

A stirred reactor (SR) combustion system has been developed to gather information on the mechanisms of ignition and flame propagation of coal dust under conditions similar to those found in coal dust explosion flames. The prime scaling variable considered in this study is that of rapid particle heating (between 105 and 106°K/sec) which is accomplished by means of turbulent mixing during combustion. The SR combustors tested in this study have consisted basically of spheres hollowed in the centers of refractory housings. Coal and air mixtures have been injected into the spherical combustion chambers through a single jet, two opposed jets or four opposed jets. The diameters of the jets have ranged from 0.63 to 0.22 cm. The volumes of the combustion chambers have ranged from 1.0 to 0.2 liters. The reactors have been equipped with thermocouples embedded in the combustion chamber wall as well as a thermocouple located in the exhaust gas stream. In the latter versions of the SR, provisions were made for both solid sampling and gas sampling of the reactant stream exiting from the combustion chamber. Experiments have been carried out using pulverized bituminous coal. The coal has been reacted in an SR in mixtures of air and air/nitrogen. These experiments have provided information on the mode of ignition of the coal as well as yielding information on the kinetics of coal pyrolysis through the use of SR theory. Ash tests performed on the reacted samples collected from the SR indicated that the majority of the values of weight loss percentage were between 60 and 70 percent. The percentages of weight loss were relatively unaffected by changes in temperature which varied between 1100 and 1700°K and by changes in residence time which varied between 10 and 20 millisec. Volatile matter tests performed on the samples indicated that the volatile matter left in the char ranged from 3 to 20 percent of the original content. By assuming that all the mass loss was due solely to pyrolysis with no combustion occurring at the particle surface, Q-factors for each test have been calculated. The results of these calculations indicate an average value of Q equal to 1.88. This finding shows that the majority of mass loss can be attributed to pyrolysis. The fact that the extent of reaction varies only slightly over the range of test conditions has been examined in the context of the two component hypothesis of coal constitution. This approach leads to the conclusion that the reaction of the "easily evolved" component VMI is extremely rapid and that the majority of it is removed from the coal in times less than the residence time in the system. This means that the volatile residue remaining in the char can be considered to consist of component II, VMII. If the mass fraction of VMI = 0, then an activation energy of 18.0 kcal is obtained for the pyrolysis reaction. If the mass fraction is assumed to be 0.75, the activation energy increases to 31.2 kcal.

Jan 1, 1978

By W. B. Coker

A helicopter-mounted lake-sediment and lake-water survey was carried out over Grenville rooks in the Renfrew area (parts of Renfrew and Lanark counties) during four days of October, 1975. In the course of this survey. 1150 square kilometers were covered, with 246 lake-sediment and 276 lake -water samples collected from every body of water on which the helicopter could land. Sample sites, which averaged one per 4.6 square kilometers, included lakes, ponds, beaver ponds, swamps and marshes. Lake-sediment samples were taken using a G.S.C. sampler. Waters were collected directly into polyethylene bottles. At each sample site , surface and bottom-water pH, dissolved oxygen content, conductivity and temperature were measured using a Martel. Water Quality Analyzer. The lake sediments were air dried and then ball milled to pass a minus 80-mesh sieve. Lake sediments were analyzed for U by delayed neutron activation and for Mo, Cu, Zn, Pb, Fe, Mn, Ni and Co by atomic absorption techniques. The organic content of the sediments was determined by loss on ignition at 450 °C. Lake waters were acidified with nitric acid on the day of collection. The U content of the water s was determined by fluorometry; the Cu, Zn, Pb, Fe, Mn , Ni and Co contents of the waters were determined by solvent extraction - atomic absorption techniques. A close relationship was found between bodies of granitic, syenitic and pegmatitic bedrock and elevated U levels in the lake sediments. The Hurd Lake and White Lake granitic intrusive were encompassed by an annulus of higher U activity. Field inspection revealed that the U concentrations occur within a zone which may represent a contact metamorphic aureole. Within these complexes, anomalous concentrations of U appear to be associated with Mo. Information derived from the lake-water data reinforces the geochemical distributions outlined by the lake-sediment survey . This survey was carried out in order to develop optimum sampling and analytical procedures for geochemical reconnaissance of the Grenville Province that may be carried out under the auspices of the Uranium Reconnaissance Program.

Jan 1, 1977

By SAMUEL GOMPERS

THE name engineer makes a very strong appeal to one who appreciates the mechanism underlying the fabric of our civilization. Engineers are scouts of civilization. We send them ahead into the lone 'places-the wilderness, the jungles, the great watery expanses, to build the highways necessary for civilized man. The engineers must deal with Nature, with that mysterious dynamic thing we call "force," with materials. It is their function to direct the human activity necessary to coordinate these forces and material in order to make them serve the needs and aspirations of men. Because of my high conception of the engineering profession I was glad to accept the invitation to address The American Society of Mechanical Engineers to voice my understanding of the possibilities of your work as engineers of industry, and to suggest what seems to me the responsibility of the-engineer to the whole modern industrial system.

Jan 1, 1921

Jan 1, 1984

By Ernest W. Johnson

In most underground iron mines in the Lake Superior district the active workings are at considerable depth. When additional openings into such. nines are needed, operating officials are eager to discover more efficient methods of constructing them. In recent years, openings into two mines in the district were made by the borehole method,-which employs chilled-iron shot as the cutting medium. Others were made by the churn-drill method, in which pilot hole is churn-drilled and subsequently reamed to a desired but relatively small diameter. Both methods are comparatively new and unique, at least in some phases and in their application.

Jan 1, 1946

By Finch. J. A., C. Perez, J. M. Ortiz, G. Cortes, A. B. Yañiez, F. Coddou, P. Morales, H. Elgueta

A campaign to perform characterization tests in a TankCell®-300 flotation cell installed at Chuquicamata Codelco's concentrator was conducted. The campaign included integrated gas dispersion measurements (gas velocity radial mapping and single point gas holdup and bubble size) and determination of frother concentration. Cell streams were sampled to assess metallurgical performance at the same time. The experimental program was designed to establish the bubble surface area flux operating range and its effect on performance, and the effect of using longer residence times and of a device designed to enhance mixing in the collection zone (FlowBooster(TM)). The gas dispersion results and their relationship to metallurgical performance are discussed.

Jan 1, 2009

By D. Van Orden, Y. Kamiya, R. Lee, E. Ilgren

Crocidolite is a well-known causative agent for mesothelioma. However, studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width although this has never been formally confirmed. To date, crocidolite appears to be the only asbestos mineral for which an epidemiological study comparing the risk of mesothelioma in a population exposed to ‘thin’ fibers with another exposed to ‘thick’ fibers of the same species may be carried out. Finnish anthophyllite, South African amosite, and African Transvaal crocidolite can also be classified as thick fibers, and there is a paucity of mesotheliomas in populations exposed to them compared to those exposed to thin Cape crocidolite. No thin occurrences of these minerals are known. Our previous study looked at crocidolite from several sources. The present study considers the amphibole anthophyllite found in many places in the world. This mineral, regardless of source, does not show the same variation in fiber width found with crocidolite from different areas. All anthophyllite fibers that have been mined may be classified as thick and populations exposed show very low levels of mesothelioma. We suggest the most likely explanation is related to the fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By Jianmin Qin, Raja V. Ramani, Wilson Miola

"The number of underground work entities operating under reduced dust standards in U.S. coal mines has been increasing since the start of the decade of the 80s and is currently approaching 10,000. The concern for controlling the quartz levels in airborne respirable dust in coal mine has manifested itself in several improvements in equipment selection and operation, face ventilation practices, and dust control procedures. At the same time, fundamental studies have been initiated on determining the source-sink relationships of the airborne quartz dust. The P-7 method is the prescribed method for the determination of quartz in the respirable airborne dust samples from coal mines. Questions have been raised on the reliability of the P-7 infrared spectrometry method for quartz analysis in powders. No specific method has been defined for quartz determination in bulk samples from the mine.In a recent study on the relationship between quartz in the airborne dust and that in the materials being mined, both infrared (IR) and x-ray diffraction (XRD) methods were used on a suite of samples from several coal mines. These samples encompassed airborne respirable dust samples, airborne total dust samples, the oversize fraction from the respirable samplers, ROM samples, channel samples, and chip samples from the face, roof, and floor materials. In this paper, the sample preparation and analysis procedures for the samples are discussed. The data, analysis results, and comparisons of the P-7 and XRD results are presented. The quartz percent determined for the same sample by the two methods are different. In 85% of the samples analyzed, the quartz percents determined by the XRD method are higher than those obtained by the P-7 method. However, there is a strong linear relationship between the results from the two methods. Further, the XRD method indicates an average of 20 percent more quartz than that from the P-7 method. The reasons for the differences in the results and the need for additional studies are explored.Since the enactment of the Federal Coal Mine Health and Safety Act of 1969 and the Federal Occupational Safety and Health Act of 1970, the prevalence of free silica as an occupational hazard in dusty work environments has been a matter of increasing concern. In underground coal mining, sometimes, roof, floor, clay veins and other non-coaly material must also be mined along with the coal. Mining these materials may increase the amount of quartz in the airborne dust (Pimentel and Adam, 1985; Taylor et al., 1984; Colinet et al., 1985). The problem of high quartz levels in the respirable airborne dust is widespread in continuous miner sections. In addition to the need for controlling the silica amount in mine atmosphere, a need for a sensitive, easily performed method for the determination of free silica in airborne dust samples was also recognized."

Mar 1, 1992

By Slavoljub D. Maksimovic

At some coal mines, methane gas is released during raise drilling. At the request of the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, the Bureau of Mines conducted ventilation surveys at different raise drill sites to assess various methods of reducing methane concentration. The resulting data indicate that raise drill shaft cavities are ventilated by air compressors, vacuum pumps, auxiliary blower fans, and free intake air from the surface. The compressors, pumps, and fans operate simultaneously or separately. At the bottom of the shaft cavities, ventilation is controlled by regulators and airlocks. Methane is monitored, measured, and periodically sampled on the surface, at the bottom, and at different levels in the shaft cavities. Maximum concentration of 3.5 percent was measured in one shaft in West Virginia. Air velocity down the raise drill shafts is always very low, Maximum recorded air down the drill stem was 3,000 cfm, which can be increased by adding air compressors. The best way to ventilate shaft cavities is through the simultaneous use of air compressors and vacuum pumps. If the methane concentration cannot be reduced with additional compressors, then the inside diameter of the drill rod should be increased, or larger pilot hole drill bits should be used.

Jan 1, 1981

By Jean Cayouette, Paul Blatter, Paul Cousin

"The Laronde mill was commissioned in 1988 and has been treating the Laronde Penna ore since 2000. The Laronde plant, situated in the Abitibi region of Quebec, has experienced mill expansions to accommodate 7500 mtpd and to recover gold and silver as well as important amounts of base metals (Cu, Zn, Pb). Ten sequential metallurgical and environmental processes are responsible for metals recovery and process viability. Over 200,000 ounces of gold, 4,5 million ounces of silver, 7000 tonnes of copper, and 78,000 tonnes of zinc are produced annually.In 2008, the Goldex plant began trucking high grade (35-45 g/t Au) pyrite sulphide concentrate (TCGO) for gold extraction at a newly constructed treatment plant, increasing gold output at Laronde by 40,000 ounces. In 2009, the high gold grade Lapa ore processing facilities were annexed to the Laronde plant increasing output by 120,000 ounces of gold. TCGO and Lapa productions are forecasted until 2018 and 2015 respectively, with known reserves of each mine.Today, up to 140 permanent employees run and optimise the Laronde plant operation. As a result, Laronde has intricacies intrinsic to a large and varied operation. The paper will outline the metallurgical highlights, challenges, and future outlook related to the treatment of each ore type (Laronde, TCGO, and Lapa).INTRODUCTIONFollowing the 2000 to 2003 expansions, the Laronde plant evolved into a mature milling complex with developed processing, man power, and water treatment capabilities able to accommodate the complex Laronde ore. The ore requires a series of grinding, copper/lead flotation and separation, zinc flotation, zinc tails precious metals leaching, followed by a counter-current decantation circuit and Merrill Crowe precipitation. A paste backfill and SO2-air cyanide destruction operate intermittently. The tailings area has a dedicated cyanide destruction and metals precipitation plant prior to water recycling to the mill. A biological water treatment plant was put into service in 2004 to address the build-up of thiocyanate in the tailings ponds at Laronde. This was the result of the high sulphide content of the Laronde ore and 90% recirculation of the process water. The plant uses bacteria to oxidize and destroy thiocyanate, and removes phosphate from the water before it is released to the environment."

Jan 1, 2011

By Rodrigo Zambra

El presente texto señala las funciones del geólogo minero moderno -en tanto aporte al sistema de control y pueda registrar las observaciones sobre geología y otros aspectos de la mina. En ese sentido, los cambios más importantes son: Base de datos digital, uso de un programa GMP para procesar e interpretar datos de ensayos, determinación de ensayos en mayor volumen y a menor costo y mayor inspección de la productividad

Oct 1, 2014

By J. L. Johnson

Remediation of small-arms firing ranges is being investigated by the Naval Civil Engineering Laboratory and the U.S. Bureau of Mines. Scheduled closures of military installations, as well as the management of active ranges, require the development of methodologies for heavy metals removal to prevent their entering the surrounding environment. The impact berms contain high concentrations of metals, and the soil and vegetation surrounding the berms were found to have slightly elevated levels. The heavy metals characterized are in the form of whole bullets, a wide size distribution of free fragments, smeared lead on the surface of the soil grains, and very finely attached particles. Gravity beneficiation can remove liberated metal contamination effectively. Weak acetic acid leaching shows promise in lowering the final metal contamination to allow the soil to pass the Environmental Protection Agency's (EPA) Toxicity Characteristic Leaching Procedure (TCLP) criteria.

Jan 1, 1991

By Julián Andrés Ortiz González

Este estudo apresenta novos resultados que comprovam a confiabilidade e a repetibilidade das medições de cargas de abertura de trincas de fadiga obtidas em estudos anteriores [1,2], que foram usadas para questionar a hipótese proposta por Elber em 1970 de que a força motriz das trincas é a gama efetiva do fator de intensidade de tensões (?Kef). Para isto, dois corpos de prova DC(T), um fino com 2 mm e o outro grosso com 30 mm de espessura, foram usados em ensaios de propagação de trincas por fadiga sob ?K e Kmax quase constantes, para simular condições dominadas por tensão ou deformação plana. Medições redundantes de ?Kef foram feitas usando uma série de extensômetros colados ao longo do ligamento residual à frente da ponta da trinca, por outro extensômetro colado na face traseira do DC(T), e por um sistema independente de correlação digital de imagens (DIC), que mede o campo de deslocamentos na face do espécimem. As cargas de abertura medidas pelos três sistemas independentes foram similares, comprovando assim que suas variações significativas observadas durante o crescimento da trinca são metrologicamente confiáveis. Este resultado comprova que a propagação daquelas trincas por fadiga não foi controlada por ?Kef. As consequências desta conclusão são detalhadamente discutidas neste trabalho.

Aug 17, 2017