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By Diana Pérez Escobar

O efeito do caminho de solidificação de um aço High Temperature Processing (HTP) API 5L X65 com 0,09 %Nb, 0,039%C e 0,54% Mn (percentagem em massa) na segregação, microestrutura e distribuição dos precipitados de Ti,Nb(C,N) foi estudado por microscopia ótica, eletrônica de varredura (MEV) e simulação computacional (ThermoCalc e DICTRA). Os resultados foram comparados com os de um aço microligado comercial com 0,04 %Nb, 0,09%C e 0,97 %Mn. Foi encontrado que o principal parâmetro que influencia no caminho de solidificação é o teor de C, o que está de acordo com a maior micro e macrossegregação observada no aço microligado comercial, em comparação ao aço HTP.

Oct 30, 2017

By Dave Stefanuto

Voisey?s Bay Project Components ? Mine/Mill Port In Labrador ? Mini Plant in Mississauga ? Demonstration Plant in Argentia ? Supply Vessel (Umiak1) ? Transshipment Facility (Quebec) ? Concentrate Handling & Transport to Sudbury/Thompson ? Cobalt Refinery Upgrade (Thompson) Project Setting ? The Project is on the traditional lands of the Labrador Inuit and the Labrador Innu ? Canadian courts have held that Aboriginal peoples in Canada possess special rights to traditional Aboriginal lands Those rights can include requiring resource developers to enter into Impacts and Benefits Agreements (IBAs) on traditional lands to set forth how lands can be used and benefits to be received by Aboriginal people

May 1, 2006

Most types of nuclear power reactors use uranium dioxide fuel. Power reactors using natural uranium dioxide fuel are of special interest to countries such as Australia that have their own uranium supplies. A wide range of uranium dioxide powders can be fabricated and the ideal one flows readily, presses without the need for binders or lubricants, sinters to the required density and gives low reject rates at all fabrication stages. Sinterable uranium dioxide is usually produced via the ammonium diuranate route.The Australian Atomic Energy Commission is aiming to demonstrate production of nuclear grade uranium dioxide from Australian concentrates, improving technology where possible. Details are given of the dissolution, solvent extraction, precipitation, filtration, drying, and· calcination-reduction steps. Solvent extraction from sulphate media is also under study with a view to developing a process to produce a nuclear grade product at the mine treatment plant site.

Jan 1, 1970

By Steve Colburn

The CRITERION Survey Systems utilize both theodolite mounted and hand held reflectorless distance meters. These are eye safe, easy-to-use, and specifically designed to endure the harsh environments characteristic to the mining, quarry and explosives industries. Survey data collected by the systems is digitally stored in a ruggedized data collector and then processed with a specialized, Windows-based, interactive software program which can be run on’ any standard PC.

Jan 1, 1998

By A. P. Gize, J. F. W. Bowles, D. J. Vaughan, S. J. Norris

Paper presented at the IAGOD international symposium on mineralization related to mafic and ultramafic rocks held in Orleans, France, 1-3 September 1993. Geological evidence from tropical laterites indicates clearly that platinum group metals are taken into solution and precipitated to form grains larger than those in the source rocks. Platinum and palladium move differentially in the surface environment, with Pt partitioning into soils and eluvial or alluvial deposits while Pd remains more mobile in natural waters. Natural organic acids, particularly humic acid, can interact with platinum-group elements and concentrate them even in areas where their content in rocks is very low. Experimental work has confirmed that Pt and Pd can be taken into solution by humic acid at room temperature and in geologically short time-spans. Solubility and deposition may be controlled by physicochemical conditions, reaction kinetics or an adsorption effect, or there may be two competing reactions, solubilisation assisted by organic matter and a kinetically slower metal precipitation

Apr 1, 1994

By A. Takala, B Nielson, J. Schunicht

"Pre-concentration in minerals processing presents clear advantages in energy efficiency, water efficiency, reduction of consumables and minimization of capital and operating costs. Outotec’s sorting solutions are powered by Tomra Sorting in order to achieve pre-concentration of concentrator feed in a variety of mineral processing applications. Sensor based sorting combines advanced sensors with rapid computational evaluation and mechanical separation of valuable material from waste and/or gangue. Modern sensor based sorting machines typically use fine air jets to propel individual rocks, thus optimizing recovery and minimizing “mis-sorting”.Gold is generally present in such low concentrations that sensors suitable for ore sorting cannot directly detect it. Therefore, in order to sort gold ore, properties of associated host rock are used. Free and sulphidic gold is often hosted on the quartz-host rock contact zone. Laser scattering effect can be used to detect the surfaces of quartz and composite quartz-host rock particles for subsequent sorting with very high recovery of 95 to 99%. In addition, ore often preferentially fractures along the quartz-host rock contact zone in the crushing circuit. This behavior helps because it liberates more quartz for detection.The feasibility of sorting is investigated for four gold projects in Northern Europe with similar mineralogy. This includes geometallurgical evaluation, amenability testing, small scale “mini-bulk” factory testing in full scale sensor based sorting. The results of the various tests are presented and basic feasibility demonstrated with information on flow sheet development. In addition, the amenability process is evaluated and recommendations made for future projects."

Jan 1, 2017

Komatsu America International has introduced two new hydraulic excavators. They can work in congested and confined areas. The tight tail swing radius of the PC128US-2 and PC22-8USLC-2 enables the excavators to minimize the work space. The units can operate in confined work settings that are inaccessible or counterproductive to traditional machines. Even the door is designed for tight working conditions. A convex door slides open along the exterior curve of the cab, rather than swinging out on hinges past tracks. And the excavators’ tight tail swing design allows them to load within the track width of the machine.

Jan 1, 2000

By John Parianos

"Seafloor mining provides significant potential economic benefits for many Pacific nations that may be "land poor" but "coastline rich," meaning they have the potential to utilize and profit from the mineral wealth within their Exclusive Economic Zones that extend 200 nautical miles (360 km) out from their coastlines. The Independent State of Papua New Guinea (the State) recognizes this tremendous opportunity and is taking a leadership role in this emerging industry by becoming a 15% partner in Solwara 1 (with an option to increase their investment to 30%).The Solwara 1 Project has been gaining momentum since Nautilus Minerals and the State signed an Agreement on April 24. This new agreement with the State in which they have staked a minimum 15% interest as a meaningful partner, underscores the State’s continued and widespread support for the Project. Signing of this Agreement was a historical occasion and a milestone achievement for Nautilus Minerals and the people of PNG.The machinery being built for the Solwara 1 Project is taking shape. The Seafloor Production Tools are now over 90 percent complete. Assembly of the biggest tool, the Bulk Cutter, was completed in April this year and assembly work on the Collecting Machine and the Auxiliary Cutter commenced in May and June this year respectively. The Riser and Lifting system, which will be used to transfer the mined material from the seafloor to the surface within an enclosed system, is over 50 percent complete. The critical path for the Solwara Project is to secure a suitable vessel arrangement. Nautilus aims to have this completed by the end of this year."

Sep 1, 2014

By B. M. Larsen, J. W. Campbell

Several articles have recently been published discussing the conditions necessary for accurate measurements of temperatures in the open-hearth steel furnace. In the course of a study of refractories service conditions in steel furnaces, the present writers have taken temperatures in several open-hearth shops in the Pittsburgh district. The conclusions, as to conditions necessary for accurate measurements of temperature, are somewhat at variance with those of other investigators. The subject is closely connected both with the close control of steel-making and the prevention of overheating of the silica refractories used in roofs and walls. It is becoming more and more important to obtain furnace temperatures of fairly definitely known accuracy. At present, the most useful instrument for such measurements is the disappearing-filament type of optical pyrometer. This method of measurement has formed the basis of most other discussions on the subject and was also used by the writers. Previous Investigations In 1916, Burgess' made perhaps the first systematic series of measurements in steel furnaces. The emissivity figures of 0.40 for liquid steel and of 0.53 to 0.65 for liquid slags had been determined by the Bureau of Standards and were used by Burgess in this work. These correction factors are still being used and are regarded as fairly accurate, so that the tapping and teeming temperatures on metal streams given by Burgess should be very nearly correct. Most of his temperatures of furnace roofs and slag surfaces were taken while flames were present in the furnaces and include a few roof temperatures above 1700' C. (3100' F.).

Jan 1, 1927

The design/optimization of the pump and cyclones to maximize grinding circuit efficiency first requires a concise understanding of, and clearly defined specifications for, desired grinding circuit performance. Subsequently, the pump and cyclone performances that provide the desired grinding circuit performance can be defined. Once the performance requirements of each process unit are determined, selection of physical equipment parameters that will deliver those performances can be carried out. The Functional Performance Equation shows that there are two distinct efficiencies in closed circuit ball milling. One of these, ?Circuit Classification System Efficiency? (CSE), is the fraction of ?coarse? material inside the ball mill upon which grinding energy is deliberately expended, versus the remaining fraction of ?fines? or finished size material inside the mill, upon which grinding energy is wasted (on over-grinding). The role of the pump and cyclones is to maximize CSE, which is the desired grinding circuit performance. The obtainable, target CSE for any given circuit can be estimated, for example by referring to a plant data base of CSE?s. Design/optimization guidelines then allow us to specify the pump and cyclone performances that will achieve the target CSE. This paper outlines the step-by-step, systematic method of pump and cyclone selection which maximizes CSE. Numerous examples of its successful application are provided.

Jan 1, 2011

By George H. Willis

In the second half of the nineteenth century, bimetallism progressively replaced by gold standard. After World War I and 1931-33 depression, gold mainly reserved for official international transactions and internal use restricted. Changes since 1971 have shrunk official international use of gold. International payments deficits and surpluses now financed by private and official credit, rarely by gold. Historical review covers evolution of: (1) internal and external private use, (2) internal official use, (3) external official use, (4) role in IMF and (5) use as unit of account.

Jan 1, 1978

By Nathaniel Arbiter

Flotation’s earliest patent was issued in 1860. However, the process was first applied commercially in Australia until 1904, and in Montana in 1911. Major advances followed both in reagent treatment and in cell design, with resulting process improvements. Mechanical cells have seen the widest use and with the major increases in plant capacities (Fig. 1) their volumes have also increased (Fig. 2). In 1991, the principal use for the process was to produce copper concentrates for smelting. It was applied to 243 Mt (268 million st) of copper ore. The total of all ores floated that year was 426 Mt (470million st). In 1997, US mines produced 257 Mt (284 million st) of copper ores for flotation, yielding1.75 Mt (1.94 million st) of copper.

Jan 1, 2000

By B. J. Kloppers, J. V. Z. Visser, C. J. Horn

"The long-term plan (LTP) in a mineral resource company is defined by the quality of the mineral resource and represents the result of a series of trade-offs to fulfil internal organizational as well as external business and legislative requirements, ensuring ultimate delivery on the defined organizational strategy.The LTP should as a whole align to a coherent and well-defined organizational strategy, working towards a clearly defined objective while still allowing a tactical response to short-term requirements of the organization. The ability to respond tactically to changes in environment, like the unprecedented five-month strike in 2014 on the platinum belt following the 2012 Marikana incident, is a measure of the flexibility of the plan given the agreed strategy.This paper describes the Lonmin process of linking company strategy with long-term planning, tactical planning, and the execution of the plan through an annual planning cycle to maximize organizational flexibility. This flexibility enables mining companies to respond to the many internal and external forces that impact on both strategy formulation and delivery of results that meet shareholder expectations."

Jan 1, 2015

By F. Seitz

STAFF: Editor, Gerhard Derge Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Managing Editor, James J. Burke THE METALLURGICAL SOCIETY: John Chipman, President; W. R. Hibbard, Jr., Post-President; C. C. Long, Vice-President; T. D. Jones, Treasurer; R. W. Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: R. Maddin, Chairman; Dennis Carney, J. C. Fulton, J. H. Hollomon, T. B. King, C. C. Long, W. 0. Philbrook, J. D. Sullivan, David Swan, and F.L. Vogel. Review and selection of manuscripts is under the supervisian of the following Publications Committees: Extractive Metallurgy D ivis ion: T. 0. King, Chairman; S. J. Dick inson, R. P. Hermsdorf, R. Schuhmann, Jr., and H. H. Kel logg. Institute of Metals Division: F. L. Vogel, Choirmon; R. L. Smith, Vice Chairman; R.W. Balluffi, J. H. Bachtold, A Servi, C.D.Graham, Jr., C. G. Goetzel, F. E. Joumot, Jr., G. E. Pellissier, Paul Gordon, Jock Washburn, Harold Margol in, A. U. Seybolt, I. R. Kromer, R. A. Meussner, R. W. Guard, M. Harmon, J. N. Hobstetter, Dean Starr, P. Shewmon, R. Gordon, J. 0. Betterton, and E. Morgan. Iron and Steel Division: W. 0. Philbrook, Chairman; F. C. Langenberg, C. W. Sherman, J. Wagstaff, and E. J. Whittenberger. Published bimonthly by the American lnstitute of Mining, Metallurgical, and Petroleum Engineers, Inc., 29 West 39th Street, New York 18, N. Y. Telephone: PEnnsylvania 6-9220. Subscription $20 per year for non-AIME members in United States and North, South, and Central America; $25, foreign; $5 for AlME members. Single copies, $4.00, single copies foreign, $5.00. The AlME is not responsible for any statement made or opinion expressed in its publications . . . Copyright 1959 by the Americon Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address, AlME New York ... Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts . . .Second class postage paid at New York, N. Y. , ond Ann Arbor, Mich. Volume 215, Number 3

Jan 1, 1960

By Daniel Mallette, Richard Goodridge, C M. Lownds

Despite a world of mobile devices that has many of us taking the ability to communicate wirelessly for granted, an in-hole wireless initiation system was thought to be not viable. The known and common wireless communication techniques are not suited to this application. To overcome this, we have developed cutting edge technology to communicate to our initiating devices more than 1km through solid rock.

Jan 1, 2016

By Rethel L. Hubbard

Fourteen straight-run asphalts were prepared in the laboratory from bitumens obtained from three sources: (1) native bitumen from Rozel Point, Utah, (2). bitumen extracted from Athabaska bituminous sandstone at Canada, and (3) bitumen extracted from Edna bituminous sandstone outcropping in San Luis Obispo County, to seven asphalts with penetrations ranging from 19 to 287 at 77 F. were prepared from each of the bitumens. The yields of the prepared asphalts ranged from 74.5 percent for a 27-penetration asphalt from the Athabaska bitumen to 99.5 percent for a 271-penetration asphalt from the Rozel Point bitumen.

Jan 1, 1949

By M Armstrong, S J. Coward, A Galli

Mine management is often expected to make rapid evaluation decisions at different stages of projects based on limited and uncertain data. The challenge is exacerbated by having to distil technical complexity into a financial model that is usually designed to produce only one or two key indicators, eg net present value (NPV), internal rate of return (IRR). Mining is a complex environment with many sources of uncertainty ranging from sampling to economics. In order to optimise investment decision-making, an appropriately structured evaluation framework must be utilised. An evaluation framework should be designed to encapsulate and integrate the complexity across the evaluation cycle, ie sampling, resource estimation, mine planning and treatment, and financial and economic modelling. This complexity is diverse and ranges from sampling support, scale effects to understanding the impact of variability, uncertainty and flexibility on operational efficiency and economic viability. These complexities, combined with time and capital constraints, usually do not allow all facets of evaluation to be integrated into the model. The model must strike a balance between simplified estimation techniques and sufficient incorporation of aspects of the project that will make a material difference to the investment decision. This paper demonstrates the impact of the scale of measurement on the valuation of a mineral project. Comparisons are made between global estimation averages using a top-down approach and local estimates using a bottom-up approach. Three sampling campaigns were conducted on a virtual orebody to compare the relative NPV accuracies. Stochastic forward models were run on foreign exchange rates and are compared with the results from a fixed foreign exchange rate model.

Jan 1, 2006

By Earl F. Hastings

The Pilgrim mine, operated by the Pioneer Gold Mining Co., is 9-1/2 miles west of Chloride in the Pilgrim mining district on the eastern slope of the Black Mountains, or River Range, Mohave County, Ariz. In March 1937, 100 tons of gold ore per day were being mined and milled at the property by a total force of 5i men. Climatic conditions allow year-round operations. Due to present activity in the county there is an ample supply of labor for the requirements of the mine. The Pilgrim is the only producing property within s radius of 6 miles; recently, however, the South Pilgrim Mining Co. has launched a development campaign on claims that adjoin the Pioneer Co. property to the south.

Jan 1, 1937

Pillars in underground limestone mines are required to support the overburden and provide a safe, stable working environment for mining personnel and equipment. Pillar stability was assessed by the National Institute for Occupational Safety and Health in underground limestone mines in the Eastern and Midwestern United States. It was found that current mine layouts have been successful in providing support to the overburden, while a small number of isolated pillar failures were observed. The stable pillar layouts and failed pillars were plotted on a chart that demonstrates the relationship between pillar width-to-height ratio and pillar stress. The results show that pillar failures occurred at the lower range of width-to-height ratios and can occur at relatively low stress levels. Zones indicating the potential risk of pillar instability are shown on the chart, based on hazards associated with the onset of rib spalling, large angular discontinuities and unconfined pillars. The chart can assist limestone mine planners to evaluate potential instability in current or new pillar layouts that are similar to those included on the stability chart.

Jan 1, 2008

By X. Bai

A new heuristic sublevel mining stope optimizer is presented. The optimizer seeks the best locations and lengths of a series of vertical raises that, together with the blocks linked to each raise, define a mining stope. Five design constraints ? the footwall angle, the hangingwall angle, the number of raises, the maximum distance of a block from a raise, and the minimum width required to move the farthest block towards the raise ? allow the shape of the sub-stopes associated with each raise to be controlled. The optimization is done on the locations and lengths of raises using a genetic algorithm to efficiently sample the parameters? space. For each raise, a local network is defined in cylindrical coordinates around the raise such as to impose the design constraints. A maxflow algorithm on the local network is used to determine the optimal sub-stope for each raise. All substopes are combined to define the global stope for the entire deposit. The best global stope is obtained using a genetic algorithm to find the raise parameters providing the best profit over the entire deposit. Two synthetic cases and one real deposit are used to evaluate the new algorithm and compare the results with the single-raise optimizer. The multiple raises approach leads to significantly improved economics compared with the single-raise stope optimizer, and the dilution is also substantially reduced compared to the single-raise case.

Jan 1, 2014