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By T. E. Hill

The Bureau of Mines investigated the possibility of physically separating Missouri and Minnesota granites into commercially usable fractions of feldspar, quartz, and mica by mineral dressing techniques. The probability of r covering a feldspar fraction from raw granite suitable for commercial uses was developed through correlation of the iron oxide content by extensive petrographic studies. This probability evaluation also included Wisconsin granites and a high-feldspar iron ore concentration tailing from Missouri. Laboratory recoveries of feldspar and quartz were on the order of 80 percent. Mineral content of each fraction was generally over 95 percent, indicating excellent response to separatory techniques, Acid leaching of feldspar and quartz concentrates to remove iron oxide improved the grades chemically; however, occluded iron oxide particles in the leached products prevented attaining top grades of feldspar. Mica was removed as scrap grade at low recoveries. Each concentrate conformed to some category of commercial feldspar, quartz, or mica.

Jan 1, 1969

By Ish Grewal

"Batch centrifugal gravity concentrators, which produce very high ratios of concentration, have become common place for recovering free gold within milling circuits. Their effectiveness has proven to be especially useful in recovering finer gold particles. The knowledge related to testing, modeling and scale-up of these systems has been well established over the recent decade mostly due to the efforts of the late Dr. Andre Laplante.Gravity separation technologies such as jigs, spirals and shaking tables can provide the increased mass yields required for minerals that occur at higher concentrations than gold, however their effectiveness tends to diminish at finer particle sizes. The development of high mass yield centrifugal concentrators has provided the opportunity to be able to recover a wide range of minerals at finer particle size classes when compared to the more traditional gravity concentration devices. These concentrators also provide additional benefits such as smaller unit footprint and automated operation.This paper discusses the background, current practices and future applications for high mass yield centrifugal concentrators in base metals, sulfides and industrial minerals. Bench scale, pilot scale and plant practice examples are also presented.INTRODUCTIONGravity concentration, one of the oldest mineral beneficiation processes, has evolved over the decades and continues to play an important role in modern mineral processing operations. The development and growth of froth flotation in the early part of the twentieth century led to a decline in the importance of gravity concentration. However, gravity concentration continued to be used for ores that are difficult to beneficiate using froth flotation; such as tin, tungsten, niobium/tantalum, iron, industrial minerals and oxidized coal. In recent decades, many operations have begun to employ a combination of both gravity concentration and froth flotation Since flotation relies on surface chemistry and gravity concentration relies on specific gravity differences, putting these techniques in series provides today’s metallurgist with unprecedented opportunities to maximize grade and recovery of many of these minerals."

Jan 1, 2009

By J. A. Botín

Traditional risk quantification methods provide little information on the sources of risk, and tend to produce static over-conservative evaluations, which do not account for changes in the performance of the project. Capital investment decisions for large mining projects require of more complex risk evaluation models, that include the value of flexibility and the different risk levels associated with uncertainty on project variables (price, grade, dilution, production rates, among many other). In this context, Real Option Valuation (ROV) methods have proven potential to quantify the risk associated with such variables and integrate alternative scenarios and management strategies into the evaluation process. In this paper, a risk quantification model is developed, which successfully quantifies the risk associated to dilution, as a function of production rate. This model is then validated in a case study on the Chuquicamata Underground Mining Project.

Feb 27, 2013

By F. Albayrak

This report is a study of the impact of Federal laws and regulations on the domestic supply of metallic and nonmetallic minerals. The study was confined to pertinent environmental legislation and the recently enacted Federal Mine Safety and Health Act of 1977. Emphasized were the legal requirements placed on individual selected mineral industries, and the economic impact of these requirements. A certain amount of attention was also directed to the particular environmental and health and safety problems generated by selected mineral industries. The study also pinpointed a list of major problem areas having significant impact on the domestic mineral supply.

Jan 1, 1978

By A. B. Hooker, L. C. IlsLey

Explosives have been fired electrically for several decades. Mountains have been tunneled, deep shafts sunk, extensive coal and metal mine workings excavated and, in times of war, railroads, buildings, bridges, and fortifications have been destroyed by means of electrically fired explosives. Modern engineering depends so much on explosives that their safe and efficient handling and especially their detonation are of prime importance to all those connected with the use of explosive agents. Electric shot-firing is only one method of igniting explosives, but it is rapidly spreading and because of certain inherent safety features should be encouraged. Data collected by the Bureau of Mines indicate that in the United States a large percentage of the blasting in quarries, shafts,· and tunnels, and from 15 to 25 per cent of the blasts in mining operations, are set off electrically. The Bureau of Mines is interested in electric shot-firing because of its use in mining, and especially because electric methods, when properly applied, are undoubtedly safer than other methods commonly used. Electrical problems of many kinds must be solved in dealing with the various phases of electric shot-firing. Success in using an electric detonator is closely linked with the resistance of its bridge, the resistance of its leg wires, and the insulation of its current-carrying parts. The proper layout of a circuit where a number of shots are to be fired simultaneously depends not only on the types of detonators that are used and their arrangement and interconnections, but also on the size and insulation of the wire leading back to the source of power, and even on the source of power itself. Various types of electric shot-firing machines have been developed, and these offer still another field for study. In investigations of electric detonators and electric blasting equipment, the oscillograph is valuable because it can record electrical activity over very short intervals of time. By its use more complete information about electrical performance can be obtained than by any other means.

Jan 1, 1926

By Guilherme Liziero Ruggio da Silva

Uma marcha estável do alto-forno (AF) está ligada à consistência das propriedades químicas, físicas e metalúrgicas das suas matérias-primas (MP), especialmente, as do coque. As propriedades do coque são reflexos das propriedades dos carvões que lhe deram origem. Em termos de propriedades ligadas à natureza do carvão, a qualidade do coque é bastante influenciada pelo rank dos carvões, que compuseram sua mistura, ou seja, quantidades de macerais reativos e inertes, bem como suas propriedades coqueificantes, que é, exatamente, a habilidade inerente aos carvões aglutinantes de quando aquecido, amolecer, tornar-se plástico e solidificar em uma massa coerente. Neste contexto, o presente trabalho se propõe a evidenciar as mudanças no modelo de britagem de carvões da Gerdau Ouro Branco, bem como a operacionalização do padrão criado. Após a implantação, verificou-se a elevação de 1.8% em DI.

Aug 17, 2017

By Geo. D. Furse

"The information that has accumulated regarding the geology of the McIntyre mine is the result of work by several geologists and, as might be anticipated, their conclusions have varied. The writer has been at the mine only a few years and due to wartime conditions has not been able to study and review the mine's geology as thoroughly as his predecessors. Where the writer's conclusions differ from those of previous authors, it should be noted that he has been unable to re-map all the workings in which flow contacts are exposed, but has endeavoured to describe the structure as indicated by the evidence he has been able to observe. He wishes to thank H. G. Skavlem and H. S. Robinson for their constructive criticism of this paper, and McIntyre Porcupine Mines, Limited, for permission to present it. A list of references is appended.The McIntyre mine is in the central part of the Pearl Lake section of the Porcupine gold area. It includes the ""bed of Pearl lake, twenty-two claims to the north of the lake, and the Platt Vet lot to the southeast. It is bordered on the west by the Hollinger and on the east by the Coniaurum property. The chief ore-bearing veins on the upper levels lie very close to the north shore of the lake, but some occur under the lake, and others of lesser importance are found to the southeast. The most important veins are Nos. 3, 5, 7, 10, and 25. Some of the veins extend into the Hollinger. on the west and others cross the east boundary into the Coniaurum. The total production since the commencement of milling in 1912 to the end of March 1947 has been $168,448,218 in gold and silver from the milling of 17,690,963 tons of ore."

Jan 1, 1954

By Gautam Benerjee, Veera Reddy Boothukuri, Bhattacharjee Ram Madhav, Panigrahi Durga Charan

"India’s tryst with mechanized longwall coal mining started with the introduction of the first self-advancing powered support longwall (PSLW) face at Moonidih Colliery of Jharia Coalfield in 1978 and at Godavarikhani (GDK)7 Incline of Singareni Collieries Company Limited (SCCL) in 1983. During the last 37 years, about 30 longwall units in Coal India, Ltd., (CIL) and 10 longwall units in SCCL have been introduced with powered roof supports of varying capacity, ranging from 280 to 800 tonnes, in many mines in India under varying geological and geotechnical conditions. The majority of the longwall faces in India have been worked under relatively shallow cover (up to 200m), and significant strata control problems have been encountered due to poor caveability of the roof, inadequate capacity of the supports, a lack of knowledge on longwall caving mechanisms, less than adequate strata monitoring systems, and the non-availability of quality spare parts, etc. This has resulted in structural damage to supports and increased downtime of the equipment, thereby making longwall mining in India a case of technology failure. Energy demand for a developing country like India with a population of 1.2 billion is huge, and the thrust on increasing coal production continues. However, the share of coal production from underground mines in India continues to decline (current share is around 6%) because of absence of successful mass production technology in underground coal mining. Under this backdrop, a high-capacity longwall with state-of-the-art technology was introduced in 2014 at Adriyala Longwall Project (ALP) of SCCL for the first time in Indian Coal Mining Industry. The first longwall panel (LWP) has been completed successfully. This paper highlights the major geotechnical challenges encountered during development of the longwall gate roads due to the presence of two overlying clay bands, significant in-situ horizontal stresses and the experience of using rigid (welded) steel wire mesh with resin-anchored roof bolts. Efforts have been made to analyze longwall weighting and caving behavior, such as main and periodic weightings, the effect of front and side abutment pressures, and the behavior of gate roadway support systems under immediate friable weak roof with overlying massive sandstone."

Jan 1, 2017

By Vladimir Adamek

This paper describes the Bureau of Mines development of a novel subsidence prediction methodology suitable to the mining and geologic conditions in the Northern Appalachian Coal Region. It describes the computation of vertical and horizontal movements, inclination, curvature, and horizontal strains. The substance of this method is the separation of the effects of lithology by introducing a correlation between hypothetically homogeneous overburden and existing lithologic conditions, while providing for different mining conditions, i.e., underground geometry and overburden thickness. The effects of lithology have been expressed in the form of a variable subsidence coefficient within the subsidence trough. The subsidence co-efficient is considered a constant for other predictive methods. Field data from 16 test sites at 11 Bureau longwall panel studies were used in the analysis. For each panel, the characteristics of the variability of the subsidence coefficient were defined. Regression analysis of the subsidence coefficients from all test sites on their locations relative to the edges of their respective panels yielded a third-degree polynomial equation. The results from additional longwall panel studies, not included in the regression analysis, were used to prove the validity of this method. To facilitate the use of this precalculatlon methodology, a computer program was written in BASIC for use on a personal computer.

Jan 1, 1987

By Danny Hagood

The drilling of horizontal boreholes as a means of degasification in advance of mining has been tried at Jim Walter Resources, Inc., No. 4 Mine. In a joint venture with the U.S. Bureau of Mines, a series of horizontal drainage boreholes have been drilled in the panels of an advancing continuous miner section with impressive results. The combined methane gas production rate has ranged from 205,000 to 680,000 cfd (cubic feet per day} with individual "in-seam" horizontal holes producing up to 332,000 cfd. The methane liberation from the ribs for the entire panel length has decreased from an average of 8.75 cfm (cubic feet per minute) per 100 feet of entry to 4.05 cfm per 100 feet, a 54 per cent reduction. The actual gas concentration as measure at the surface discharge point normally ranges from 85 per cent to 95 per cent methane. As a consequence of the significant reduction in methane liberation rates from the panels of the section, a 50 per cent increase in productivity from the section has been realized.

Jan 1, 1983

By E. H. Burroughs

This bulletin is the fifth in the series of petroleum bibliographies publis:\:l.ed by the Bure.au of Mines, Bulletins 149, 165, 180, and 189 being compilations for the years 1915, 1916, 1917, and 1918, respectively. In this bulletin the same general plan has been followed in arranging the references, but a few changes and additions have been made in the classification.

Jan 1, 1923

Strategic planning in mining is an important value accretive process. One of the most important aspects during the planning phase is determining the correct mine and plant design. The traditional mine site design (mine, plant, stockpiles, dumps) develops a fixed system for one set of conditions or expected values. A robust design is a fixed system that is designed to deal with a large range of conditions without changing the system design. A flexible design changes the system dynamically in response to changes in uncertainties. It is hypothesised that a robust design generates less value than a flexible design as it fails to realise the value of actively managing the operation. One of the most critical aspects in creating strategic value from a project is embedded in the design of the system. A flexible design has components that allow the design of the system to change over time. An operational plan is proposed as a hybrid of a robust and flexible design. This paper seeks to compare these different design methodologies. An analysis of the same case study is undertaken to compare these approaches, showing an a traditional net present value (NPV) of $1678 M, robust design NPV of $1787 M and an operational plan NPV of $1867 M - an increase of $170 M.

Dec 6, 2010

By J. W. Wang

This article first explains the mechanism of forming strength in the Jet grouting reinforced foundation, and points out the function of cement hydrates and clay minerals in clayey soil, the reinforced body with the character of long-term growth of strength. Secondly, regarding the strength and the deformation characteristics of compound foundation, the article points out that the stress-strain curve of the jet grouting pile is approximate to hyperbolic curve. Finally, the article cites three examples of application in the construction of the metallurgical industry.

Jan 1, 2010

By Micheal Mitariten

The recovery of natural gas (primarily methane) from coalbed deposits is an established and growing source for the U.S and accounts for over 7% of its total production. The gas from on-purpose degassing is often pipeline quality and requires only compression and dehydration before being admitted to the pipeline grid. However, the raw gas is sometimes contaminated with nitrogen (N2) and/or carbon dioxide (CO2) that can make the gas inadmissible to the transportation pipeline. In general, the N2 must be 4% or less and the CO2 should be 2% or less. In treating gas produced from virgin coal bed or from degassing operations where CO2 is present, amine systems are traditionally used for its removal. Engelhard’s Molecular Gate® adsorption system offers an attractive alternative due to its skid-mounted equipment, low pressure and unattended operation, cost and high on-stream reliability. Natural gas can also be sourced from the residual coal, after the coal has been mined. This source can be the GOB or gas remaining in abandoned coal mines. This source is almost universally contaminated, often with a combination of CO2 and N2. If the source is from air intrusion, the source can also be contaminated with O2. In treating CO2 / N2 contaminated feeds, the Molecular Gate adsorption system removes both of the impurities along with a level of O2 within a single processing step. To date, ten Molecular Gate units are underway with three systems having been installed for upgrading gas from abandoned coal mines. The technology consists of specialty adsorbents and advanced PSA processes that are jointly offered as fabricated packaged equipment by Engelhard Corporation and Guild Associates, Inc. Upgrading requirements, project challenges and project arrangements are discussed in this paper.

Jan 1, 2005

By S. Niyomwas, R. G. Reddy

"A mathematical model was developed to describe the plasma gas and particle dynamics and conversion yields. The velocity and temperature fields in the plasma were calculated by solving 1 the Navier-Stokes equations and the thermal energy balance equations. Conservation equations for the system species consider the multi-component diffusion and chemical reactions. Through the application of this model, temperature distribution, flow fields, and production rates were computed. The model was used to study the thermal decomposition of ilmenite in the non-transferred arc plasma reactor. The computed production rates of TiN from ilmenite using nitrogen and methane gas mixtures, are in the range of 5 to 100 x 104 kg/m3/s at 2500 KIntroductionThe widespread interest in thermal plasma processing has stimulated a great deal of research effort into the various aspects of this process, including plasma' spraying, thermal plasma chemical vapor deposition, plasma synthesis of fine powders, thermal plasma decomposition, plasma melting, and plasma extractive metallurgy.In the plasma synthesis of fine powders, the earlier experimental and theoretical studies aimed at predicting the final products1-5. Then it was followed by more recent investigation concerning the profile of plasma gas velocity, plasma temperature and concentration. In this regard, useful plasma processing models have been reported by numerous investigation6 -11 which were increased by both theoretical analysis and measurement.As a result of this work a reasonable plasma-processing model is proposed. It is to be noted that all the thermal analysis that has been made neglected the fluid -flow effects. Also, in the analysis aimed at the quantitative description of the fluid-flow field, the effect of heat transfer was not taken into account."

Jan 1, 2000

By James Paone

Land utilized by the mining industry from 1930 through 1971 amounted to 3.65 million acres, or 0.16 percent of the land mass in the United States. Land reclaimed during the same period was 1.46 million acres, or 40 percent of the land utilized. This report includes data on land use for wastes from underground and surface mining, for wastes from mill operations, and on subsidence. Data on land use and reclamation were obtained from operating companies, mining organizations, appropriate State agencies, and others concerned with such activities. The 10 leading States in land used for mining in 1971 were, in decreasing order, Kentucky, Pennsylvania, Arizona, Ohio, California, Florida, West Virginia, Illinois, Minnesota, and Indiana. Mineral commodities accounting for a major portion of land use are, in decreasing order, bituminous coal, sand and gravel, stone, copper, phosphate rock, iron ore, and clay; for coal, these commodities are produced principally by surface mining operations. Reclamation over the 42-year period was largely on lands utilized for surface mining of bituminous coal. New surface mining methods, particularly for coal, incorporate some form of land restoration.

Jan 1, 1974

By Stephen Chung

The quality of a blast design can be evaluated in many ways. It may involve fragmentation, muck profile, environmental effects in terms of vibration and the excavation of the blasted material. To assist and ensure an achievable cost effective design, numerical modeling techniques are often applied as part of the operating procedure. While excavation is one of the mining operations which has a direct influence on the bottom line cost of productivity, the characteristics of a pile of blasted material deserves a closer look in terms of diggability. This paper reviews the current diggability techniques available for application to the blasting operation. To help better understand the involvement in digging, this paper also introduces an evaluation approach based on a discrete element method. The model presented in this paper deals with many variables that are considered to directly affect digging. They are the density and cohesion of material, fragment shape and size distribution as well as the swell of a muck pile. To help visualize the analysis approach, sample runs and animations are given in the paper to show the setup of muck piles produced in bench blasting as well as in sub-level caving. The computed forces experienced by the bucket during each mucking cycle are also discussed.

Jan 1, 2008

By C. Bazin

The separation of rare earth elements is a complex process that is industrially carried out using liquid/liquid extraction. Detailed flow sheets of solvent extraction plants for the separation of rare earth elements are rarely available in the literature which limits the opportunity to teach and test the application of data reconciliation, process optimization and control to these types of plants. The basis of a simulator for a rare earth elements separation plant is described in this paper. The simulator is used to adjust the organic phase and stripping acid flow rate in a separation circuit of heavy rare earth elements from light one?s.

Feb 27, 2013

By David Shatwell

Recent epithermal gold discoveries in Chile and Bolivia provide increasing evidence of a belt of intermittent, epithermal, precious metal mineralization east of the main Andean porphyry copper belt. This relationship may be the result of an easterly decrease in the age of magmatism and erosional levels, in¬crease in depth above the underlying Benioff zone and consequent changes in magma chemistry, or some other unrecognized factor. Examples are: • The Choquelimpie gold-silver mine in Chile and numerous other epithermal prospects (such as La Riviera, Bolivia) in late Tertiary volcanics along the Chile-Bolivia border. These lie east of the belt that contains the Toquepala, Quellaveco and Cuajone porphyries in southern Peru and the Cerro Colorado, Copaquire and Quebrada Blanca porphyries in northern rhila

Jan 1, 1990

By Rameshwar Sah, Somasekhar Pitchika, Akhil Singh, Seenivasan Rajiah, C. B. Dayanand, G. Balachandran

In the sintering of iron ores, the partial substitution of anthracite coal for coke breeze has been considered to be an effective way of reducing emissions and improvement in sintering properties. In the present study, the combustion characteristics of the anthracite coal and coke breeze were investigated and its influence on product sinter quality and sinter flue gases is being monitored. Pot trials are carried out with different coke breeze ratios, 0%, 40%, 50%, 60%, and 100%. It is found that as the percentage of anthracite coal is increased from 0 to 100%, the sintering time decreased from 24 to 20 min, and the productivity increased from 2.25 to 2.60 t/h/m2. Up to 60% anthracite coal substitution Tumbler index (+ 6.3 mm%), Product yield (+ 5 mm%), and fines generation (− 5 mm%) is found 62.29%, 85.17%, and 15.33%; moreover, hematite ( Fe2O3), magnetite ( Fe3O4), calcium ferrite phases ( CaFe2O4, CaFe3O5), and Silico ferrite of calcium and aluminum (SFCA) are major mineral phases found during microstructural analysis of product sinter. Keywords Sintering · Anthracite coal · Combustion rate · Productivity

Jun 2, 2022