Search Documents

By G. R. Fitterer

In the manufacture of steel by any process the refining period involves the partial elimination of the metalloids carbon, manganese, phosphorus, and silicon, by virtue of their reactions with ferrous oxide. At the end of this refining stage the metal consists chiefly of iron in which small amounts of these materials are dissolved. Unless some deoxidizer is added to the steel at this time, the reaction between carbon and ferrous oxide will continue with such force that it is impossible to form sound steal in the ingot molds. Instead, the product will exhibit a marked porosity due to the formation and trapping of carbon monoxide-the product of the reaction mentioned. However, if deoxidizers are added, steel may be obtained which is dense and free from gas bubbles. At the same time the deoxidation products will remain in the steal as impurities. For example, silicon additions form Si02 or combinations of Si02 and FeO. Additions of manganese form deoxidation products consisting of various proportions of MnO and FeO. It is also quite obvious that simultaneous additions of manganese and silicon will form oxide combinations either in the binary system MnO-SiO2 or in the ternary system FeO-MnO-SiO2. Work at the Pittsburgh Experiment Station of the United States Bureau of Mines, in cooperation with the Carnegie Institute of Technology and the Metallurgical Advisory Board, involved the study of such deoxidizing reactions and their products. In this connection considerable information is necessary concerning FeO, MeO, Si02, and Al 203, and their various combinations. Some of the most needed data are the melting points of all of these materials. At the outset of this work ordinary methods of melting point determinations were found to be inadequate for various reasons, and the procedure finally selected involved the use of the micropyrometer with occasional corroboration by quenching methods, The reasons for this selection, together with a description of the apparatus, are given in the following pages.

Jan 1, 1932

By Alfonso Rizo-Patrón Remy

El presente texto señala la importancia de los fosfatos en la cuenca del Pacífico. En ese sentido, se describe las condiciones favorables en la cuenca del Pacífico para el planteamiento del manejo de los recursos naturales a través de la infraestructura concentrada en el área de Bayovar, Piura. Así también se revisan los hidrocarburos, los programas de acción, los recursos de agua potable, las condiciones climáticas, el puerto de aguas profundas, pesquerías y otros recursos minerales.

May 1, 1972

By Donald O. Capstick

The U.S. Bureau of Mines conducted an inventory of the prospects and mineral resources in the Scodies RARE II area (No. 5212) in 1982. No mineral production is recorded from the area, and no mines are being developed. The Scodies RARE II area is comprised primarily of light colored granodiorite with minor inclusions of mafic granitic rocks. Late stage differentiates of magmas resulted in quartz veins and pods. Metasedimentary rocks which have been mineralized in some parts of the Sierra Nevada were not observed within the study area during this investigation but small inclusions have been reported.

Jan 1, 1983

By Neo Molelekeng, Jocelyn Bouchard, Rebecca Monnapula, Martin Émond

"Xstrata Alloys – Eland Platinum concentrator (South Africa) has recently been commissioned and is now initiating a challenging optimisation program encompassing the entire operation. Process control improvements are key elements of the program and initial results have demonstrated how leveraging from current assets can bring significant improvements through overall reduction of variability. This paper gives a brief overview of the operations and details how Eland is striving to become a top tier leader with advanced regulatory control strategies recently implemented. Results reveal that what can be achieved in a standard control system (PLC or DCS) should not be underestimated as the first interventions led to a steadier operation of the primary ball mill circuit. Following the improvements, significant and sustained reductions of standard variation were observed for key process variables around their set-point: primary ball mill feed rate (72 %), rougher feed density (58 %), and rougher feed flow rate (47 %). A path forward has been identified to tackle further opportunities around the primary grinding circuit: water balance management, throughput optimisation as well as charge and power draw control.INTRODUCTIONThere are numerous approaches to mineral processing plant optimisation. As the benefits of determining the right reagent types, mix, dosage and addition points, or the proper charge of grinding media in a mill are fully appreciated, there is still nowadays some misunderstanding and misconceptions about process control in general and how it can contribute to the whole optimisation process. The confusion between the various disciplines involved, i.e. instrumentation, control system programming, automation and process control, certainly does not serve the best interest of the industry with this regard."

Jan 1, 2010

By W. G. Brunner

The slurry wall technique has undergone an evolution from its invention to its today’s status. In the early stages slurry walls were built with cable grab, later on with much stronger hydraulic grab and last but not least with the use of the cutter technique. The cutter allows thick walls with high verticality to extreme depths through hard soil and rock formations. With the rising demand of the construction of watertight diaphragm walls different joint systems have been developed. In addition to the rapid development of excavation systems it was necessary to improve slurry treatment and desanding plants, especially in conjunction with high performance trench cutters. Deep mixing methods can be used economically for the construction of cut-off or excavation support walls where other systems such as traditional soldier beams and lagging walls would yield unsatisfactory performance, where the installation of vibrated or driven sheet piles could cause vibration induced settlements and where concrete diaphragm walls would be time consuming and expensive. The new CSM method can largely replace the more conventional single or multiple auger methods of soil mixing or jet grouting. The cutter tool is similar to a cutter used in diaphragm walls or cut-off walls and is operated with a Kelly mounted on a drilling rig or rope suspended on a crane jib or mast of a base carrier. With this system much deeper walls can be installed and even hard soil layers can be penetrated.

Jan 1, 2007

By Clayr Alexander

Stillwater Mining Co. (SMC) is engaged in developing, extracting, processing and refining palladium, platinum and associated metals (PGM)from the J-M Reef. This geological formation is located in Stillwater, Sweet Grass and Park counties in southern Montana. Associated byproduct metals include rhodium, gold, silver, nickel and copper. SMC’s current mining operations are near Nye, MT. The company is currently developing a second underground palladium and platinum mine, the East Boulder project, about 21 km (13 miles) west of the Nye operations. A 5,650-m (18,550-ft) tunnel is required to gain access to the ore-bearing horizon (J-M Reef).

Jan 1, 1999

By Robert H. Peters

Groundfall accidents have been the leading cause of fatalities in the underground coal mining industry for many years. Statistics from the Mine Safety and Health Administration (MSHA) indicate that approximately half of the victims of these fatal accidents were in an area where no devices had been installed to support the mine roof. This report was prepared by the U.S. Bureau of Mines to provide guidance to operators of underground mines concerning the use of techniques that may help to keep miners from going under unsupported mine roof. The report is divided into two major sections. The first section reviews the findings from several areas of empirical research pertaining to strategies for convincing employees to avoid unsafe acts and/or adopt self-protective behaviors. The strategies are (1) incentives and feedback, (2) disciplinary actions, (3) training (primarily fear communications and behavioral modeling), and (4) nondirective techniques. This literature review has a broad focus and should be helpful in making decisions about how to encourage a wide variety of types of self-protective behaviors. The second major section of the report presents an analysis of each strategy's potential for keeping miners away from unsupported roof.

Jan 1, 1991

The Federal Coal Mine Health and Safety Act of 1969 requires that each operator of a coal mine shall take accurate samples of the amount of respirable dust in the mine atmosphere to which each miner is exposed, a measure designed to prevent the development of coal workers' pneumoconiosis. This textbook manual is used in the training of personnel to operate respirable dust sampling devices and to conduct sampling programs. It contains the portions of the act applicable to respirable dust standards, the procedures to be followed to insure compliance with Federal regulations, and descriptions of sampling devices.

Jan 1, 1971

By Graham Speirs

La minería del siglo XXI requiere que ingenieros, consultores y proveedores brinden apoyo a promotores, desarrolladores y operadores para lograr una extracción y procesamiento de minerales segura, eficaz y con el menor costo posible. Este artículo técnico muestra el diseño, construcción y mantenimiento de un eje vertical, con una forma más rápida, económica y productiva de izar con cables guía, buzones de aluminio y sistemas de izado diseñados con tecnología de vanguardia.

Sep 30, 2017

By J. Wagner, P. Eger, G. Melchert

In 1991, LTV Steel Mining Company decided to close an open pit taconite mine in northeastern Minnesota, using a passive treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. Over 50 million metric tons of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages, and prior to closure annual median concentrations ranged from 1.5-50 mg/L. Copper, cobalt and zinc are also present but are generally less than 5% of the nickel values. Median pH ranges from 5.0 to 7.5, but most of the stockpile drainages have pH greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential a stockpile had to produce acid drainage, the lower the permeability of the capping material required. Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to over 90% for the plastic liner. Five constructed wetlands have been installed since 1992, and have removed 60-90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1% of those for an active treatment plant. Since mine drainage problems can continue for over a hundred years, the lower annual operating costs should pay for the construction of the wetland treatment systems within seven years.

Jan 1, 1999

By W. Mackenzie

The development of a resource project inevitably requires the investigation of a vast range of issues across most engineering disciplines - mining, metallurgical, chemical, civil, electrical, mechanical and environmental - as well as the geosciences. It is also a characteristic feature of the resource industry that no two orebodies - and hence no two development projects - are the same. So these technical issues have to be addressed to a greater or lesser extent in evaluating any resource project's development potential. Not surprisingly then, technical issues tend to predominate when assessing the development potential of a project in the process typically referred to as `doing a feasibility study'. But the principal purpose of a `feasibility study' is to determine whether a development opportunity makes good business sense, not just whether it is technically possible. Resolution of technical issues is often seen as the primary focus of a feasibility study, whereas in reality, these technical issues are the basis upon which an asset delivery and business plan is built. This is not to say that technical issues are unimportant - they are a prerequisite to the demonstration of a project's viability. The feasibility study process must therefore demonstrate that not only have the technical issues been satisfactorily addressed, but also that the broader commercial, economic and social issues have been considered in the development of a comprehensive business plan, which includes an assessment of the risk-reward profile of the proposed development. This paper will present a framework for the conduct of `feasibility studies' and provide guidance to minimum standards and best practice.

Jan 1, 2007

By José A. Rios, José A. Vidalôn

The case study of a highland area in the Central Andes of Peru, where many abandoned polymetallic mines are found, is presented. Some of these mines generate metal leaching and acid rock drainage (ML/ARD) or have potentially ARD generating (PAG) tailings/waste rock storage. Effluents are discharged into the first of two lakes in line, which act as reservoirs for irrigating an important valley in the desert coastal region. Drainage fees, their relationship with the deposit and the solid-wastes mineralogy are discussed, as well as variations in water and sediments composition, the benthos, and the aquatic/riparian flora/fauna in these lakes.

Jan 1, 2000

By S. Schina

Part of the Imittos Western Peripheral Motorway in Athens is the twin road tunnel in the vicinity of American College, with 20m excavation diameter. In the paper, the environmental and other requirements, the geometry and the geological – geotechnical characteristics of the rock formations in the construction area are given. Information regarding the modeling and analysis methods that are used for the design of the temporary support, the final lining and the wedge and slope stability analysis is described thoroughly. Finally, the results of the analyses are compared with these of measurements and general remarks during the construction of the tunnels.

Jan 1, 2001

Alkaline leaching with sodium carbonate solution adjusted to pH 9·5 to 10·0 preferentially dissolves thorium from a mixture of rare earth and thorium hydroxides. Rare earth sodium carbonates form in the alkaline leaching stage.These are converted to rare earth oxides for use as optical and ophthalmic polishing agents. Quadrivalent cerium is extracted under similar alkaline leaching conditions.INTRODUCTIONAustralia has made significant contributions to mineral chemistry and mineral dressing. As often happens with an industrially immature country, research investigations often outstrip the ability or desire of commerce to exploit them. It is wrong to think exclusively in terms of export of raw materials. Imagination assists in developing world trends. The chemical utilization of mineral sands has interested a group of investigators, chiefly at the Commonwealth Scientific and Industrial Research Organization (C.S.I.R.O.) and, more recently, in the mining industry itself. From an international point of view the highlight of this work was Newnham's (1960) process for the separation of hafnium from zirconium. Earlier work at C.S.I.R.O. investigated the chlorination of rutile, zircon, and monazite. Assuming that titanium tetrachloride would be available in large quantities in the post war years, extensive work was done by Kraitzer, McTaggart, and Winter (1948) on organic compounds of titanium. This work led to the development of heat resistant paints, plastic compositions, and improved organic protective coatings that predated overseas work by up to seven years. (Post, Shiihara and Schwartz, 1961; Anon, 1955). Contributions were made to the production of refractory hard metals (Kraitzer, 1949; Kraitzer and Newnham, 1956). Pilkington and Wylie (1947) and Urie (1947) investigated the production of rare earths from monazite by an acid process.

Jan 1, 1963

By B S. Utting, W J. Cowie

The alluvial gold industry of New Zealand is based on the placer deposits in Otago and on the West Coast. Production from these since discovery in the 1850s has been an estimated 480 t (15 Moz) of gold. Annual output has expanded continuously since 1980 and is expected to be over 2 t of gold for 1989. Following a historical review, the characteristics of typical operations, which use hydraulic excavators and mobile trommel units are discussed. Descriptions are then given of alluvial activities in Otago and on the West Coast.

Jan 1, 1990

By Regina Krachler, Herbert Ipser

"The principles of the derivation of statistical-thermodynamic models to interpret the compositional variation of thermodynamic properties in non-stoichiometric intermetallic compounds are discussed. Two types of models are distinguished: the Bragg-Williams type, where the total energy of the crystal is taken as the sum of the interaction energies of all nearest-neighbor pairs of atoms, and the Wagner-Schottky type, where the internal energy, the volume, and the vibrational entropy of the crystal are assumed to be linear functions of the numbers of atoms or vacancies on the different sublattices.A Wagner-Schottky type model is used for the description of two examples with different crystal structures:For B'-FeAl (with B2-structure) defect concentrations and their variation with composition are derived from the results of measurements of the aluminum vapor pressure; the resulting values are compared with results of other independent experimental methods.For Rh3~ (with an NiAs-derivative structure) the defect mechanism responsible for nonstoichiometry is worked out by application of a theoretical model to the results of tellurium vapor pressure measurements. In addition it is shown that the shape of the activity curve indicates a certain sequence of superstructures.In principle, there are no limitations to the application of statistical thermodynamics to experimental thermodynamic data as long as these are available with sufficient accuracy, and as long as it is ensured that the distribution of the point defects is truly random, i.e. that there are no aggregates of defects."

Jan 1, 1996

By Wm. Mark Hart

High horizontal stresses and shear failure have been considered the major reasons that cause entry roof failure and falls for underground mining. Therefore, reorientation of the current mining systems or layouts or using angular crosscuts in mains or gate entries becomes more popular if a greater than normal horizontal stress is measured. However, reorientation of the current mining systems or layouts is always expensive and use of the angular crosscuts may weaken the pillar structure at corners. Therefore, cautions must be taken before any decision related to reorientation of the current mining systems or layouts or use of angular crosscuts is going to be made. In order to prevent entry roof failure and falls, the following two issues must be carefully examined and fully understood: 1. Which one, shear stress or tensile stress, is going to be blamed for entry roof failure? 2. Which one, horizontal stress, vertical stress, or local geological weakness plays a major role in entry roof failure and falls? This paper analyzes the mechanisms of entry roof failure and falls for underground mining in general examines the roof fall history at Springvale Colliery, and proposes the means of preventing roof failure and controlling roof falls for Spingvale Colliery in particular.

Jan 1, 1996

By Cory G. Rice

A significant portion of the piling industry has long felt relying on soil setup to gain the required capacity is a complexity that would rather not be dealt with. Instead, the pile are driven to the required capacity on the initial drive and the potential gain of capacity due to soil setup is simply considered an added bonus or safety factor. There appears to be an attitude that if one did not put in the energy required to develop the full capacity on the initial drive, then one should not expect to gain anything from Mother Nature for free. However, substantial savings in time and materials can be realized by properly accounting for setup. This paper will show the impacts and ramifications this rationale can have on required labor and material costs and illustrate a case history with significant soil setup and the savings realized on a project currently being constructed.

Jan 1, 1992

By G W. Wilson, M Aubertin

A desulfurised tailings cover was installed at the Detour Lake Mine in Ontario, Canada, to reduce oxygen penetration into the underlying sulfidic tailings. The cover ranges from one to 1.5 m in thickness and was intended to maintain high water saturation to reduce oxygen diffusion and consume oxygen by oxidation of the residual sulfide minerals. The tailings impoundment was instrumented to measure climatic parameters, water levels and water content profiles within the tailings and single-layer cover. One year of monitoring data was collected. Additional tailings samples were obtained for geotechnical and geochemical characterisation. The average grain size of the cover material was found to be coarser than the underlying tailings. Monitoring also indicated that air entry values of the cover material were lower than the tailings. Numerical modelling was conducted on the cover to predict water content profiles under varying climate conditions together with the depth of oxygen penetration and diffusive oxygen fluxes. Estimates of the diffusion coefficient and kinetic oxidation rates from field data compared well with values obtained by laboratory measurements. Numerical simulations indicate water saturations of less than 85 per cent can be expected under varying climate conditions. Predicted oxygen flux rates through the desulfurised cover over tailings with high acid potential indicate low flux rates reaching these tailings due to either consumption of oxygen by residual sulfur within the cover or saturation of the underlying tailings.

Jan 1, 2003

Ultrasonic Extinction for High Resolution Particle Size and Concentration Analysis

Sep 13, 2010