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By R. J. Hundermark, S. Sun

The oxidation state dependence of the electrical conductivity of a calcium ferrite slag with 25 wt% CaO was measured at 1300°C using a shallow slag layer and two-electrode technique. The experiments were started in air and the slag was sequentially reduced by means of a controlled gas atmosphere using CO2and CO. The electrical conductivity in air was approximately 300 S/m and increased with reduction to approximately 1900 S/m at a pO2of 10-10atm. The interest in the oxidation state dependence of the conductivity of calcium ferrite slags was to provide a comparison with the conductivity of iron silicate slags and to establish the effect of slag basicity on the electrical conductivity and its oxidation state dependence. The results obtained are discussed in terms of the slag structural information available in the literature. The co-ordination of the ferric ions appears to play a large role in determining the electrical conductivity. Keywords: calcium ferrite, slags, electrical conductivity.

Jan 1, 2004

By I. A. Minaev

The conditions of a stability of metallurgical films on a surface of solid on the basis of classical regularities of a thermodynamics are considered. For specific conditions of metallurgical processes the basic equations relevant to non-metallic inclusions (product of steel killing) migration and transfer through the interface boundary of metal-slag are obtained. The basic criteria equations of conditions of stability of metallurgical dispersed systems are developed in view of films formation. The probable thermodynamics reason of wetting due to formation of stable films are discussed. The experimental measurement of thin and thick films elastic resistance for metallurgical systems are carried out and the results are discussed. The presence of a wetting thick film increases stability of dispersed systems (facilitates an inverse implication of non-metallic inclusion in a melt) due to a barrier effect of wetting films. The quantitative evaluations of non-metal inclusion stability for steel in contact with any metallurgical slag are carried out. The results are in accordance with technological experience. Keywords: Inclusion removal, Film thermodynamic, Slag-metal dispers system

Jan 1, 2004

By R. Grimard, M. Gamache, L. -P. Bigras, P. Cohen

This paper describes a real-time fleet management system for an undergroun mine. Dispatching, routing and scheduling are handled simultaneously, taking into account the mine status, operational constraints and vehicle location information. Each assignment decision takes into account the traffic on the road segments of the mine network, whether road segments are bi-directional or uni-directional, and ensures that each LHD (load-haul-dump) vehicle arrives at loading and dumping points with the correct orientation. Such a system can be used either as a simulation tool for strategic planning or as a real-time managing and optimizing system for operations. In the simulation mode, the system can accurately estimate the impact on productivity of decisions such as the development of waiting areas (bays, sidings), or the addition (elimination) of vehicles to the fleet in operation. When used for real-time dispatching, routing and scheduling of vehicles, the system can optimize production with respect to various assignment criteria such as cycle-time minimization or deviation from a target production plan.

Jan 1, 2004

By R. H. Widmyer, G. M. Wood

This investigation was prompted by the absence of a simple, accurate method to predict optimum second stage separation pressure in three stage separation operations. Three stage separation as used here includes two separators plus the stock tank. The first stage pressure is usually fixed by gas sales conditions and the third stage is at atmospheric pressure. Thus, the second stage pressure is the only one that may be varied in-discriminantly during production operations. No variations in temperature were considered in this study, even though it will vary among systems, for a change in temperature has little effect on the optimum pressure. Optimum pressures may be determined from flash calculations, but these are tedious unless a computer is available. An early attempt to develop a simpler method&apos; yielded an equation which gave the optimum pressure only as a function of initial and final pressure. Experience, however, confirms theoretical relationships which show that composition as well as pressure and temperature must be a factor. This indicates that the basic relationship should be an equation of the form, where P, is second stage pressure, P, is first stage pressure, A is a function of P. (stock-tank pressure) and the system composition, and n is a function of the number of stages and the system composition. Fig. 1 shows the basic variation of P2 with P for a fixed system composition. A series of such figures clearly showed the effect of composition. The peak of each curve reflects that second stage pressure at which the stock-tank recovery (gal/MMcf) residue gas is a maximum value. DEVELOPMENT OF NEW CORRELATION Wellstreams having 17 different analyses, ranging from low gravity crude to condensate, were used to determine the effect of composition. Each wellstream was flashed through three stages to determine the optimum second stage pressure for each first stage pressure. Equilibrium vaporization ratios proposed by Latham and Campbell were used throughout. The heptane plus fraction, for simplicity, was assumed to have the properties of octane. The results were subjected to an empirical analysis in an attempt to develop a correlation- that would be (1) simple, (2) accurate, and (3) eliminate the need for any flash vaporization calculations. This analysis yielded two equations, one for wellstreams having a specific gravity greater than one (air = 1.0) and one for those less than one. For crude streams (specific gravFor condensate (specific gravity < 1.0),

By C. Larsen, D. Fragomeni, A. Vien, D. G. Fisher

"MOCCA is a Multivariable Optimal Constrained Control Algorithm developed specifically for non-square industrial control applications with practical difficulties such as interactions, time delays, constraints, modelling errors, etc. MOCCA consists of an off-line simulation/translation module, for tuning the control parameters, and an on-line module that implements the designed control law.This paper describes an evaluation of MOCCA on the Hemlo grinding circuit which comprises one open circuit ball mill and two closed circuit ball mills in series. In this case a 4x4 unconstrained control problem was considered. The manipulated variables included the fresh ore feed rate and three pump box water additions. The controlled variables were the grinding circuit product particle size and three pump box levels. In this application soft constraints were implemented through control action and control error weighting. The feedforward capability of MOCCA was used to compensate for a measured water flow disturbance to one of the pump boxes. MOCCA performed very well during plant evaluations when compared to the original classical multi-loop control strategy and proved to be quite robust. Perhaps most importantly, the process engineers and plant operators have a high level of comfort both in understanding MOCCA's general operating principles, and with its demonstrated performance."

Jan 1, 1991

By S. D. Bearden

Color enhances expression and communication in all physical objects experienced in life. Pigments provide color and in some applications have a specific additional function. Natural iron oxides are widely distributed throughout the world but only a few deposits are sufficiently pure and possess acceptable color and brightness properties to merit their processing into pigment form. Ochre, the common name for goethite ore, is the best and most under used material in the buff colored pigment market. The geological occurrence of ochre in the basal Shady Formation of the Cartersville Mining District (Georgia) is described. Exploration, processing, and product applications of New Riverside Ochre Company, Inc. are discussed. An overview of the worldwide pigment market is presented with emphasis placed upon the North American activity in iron oxide production and application. The purpose of this paper is to increase the awareness of ochre and its potential market in the colored iron oxide pigment industry, encourage research on the origin of ochre deposits, and stimulate interest in new applications of this unique substance.

Feb 27, 2013

By F P. Hao

Organo-sulphur-based collectors (eg xanthates, dithiocarbamates and dithiophosphates) are widely used in the flotation of sulphide minerals. Xanthates (ROC(=S)Sû), for example, adsorb strongly at sulphide mineral surfaces, in a reaction that is electrochemically coupled with the reduction of dissolved oxygen. One of the oxygen reduction products, hydrogen peroxide, reacts directly with dissolved xanthate, leading to its oxidative decomposition. Experimental work has been conducted, using ethyl xanthate, to understand the molecular mechanism by which hydrogen peroxide reacts with xanthates. A number of degradation products have been identified, some of which have not been reported previously. This oxidative decomposition reaction pathway is discussed in the broader context of xanthate decomposition in flotation systems. One of the identified ethyl xanthate decomposition products, ethyl perxanthate (ROC(=S)SOû), has been observed in the process water of a number of mineral processing operations. The interaction of this molecule with goethite (&alpha;-FeOOH) particles, typical of that found in tailings dams, has been studied in more detail using attenuated total reflectance (ATR)-FTIR. The ethyl perxanthate molecule has been found to coordinate to iron (FeIII) at the goethite surface, and undergo a surface-catalysed decomposition process. In the presence of both PbII and goethite, a ternary surface complex is formed, where ethyl perxanthate is coordinated directly to surface adsorbed PbII atoms. The results obtained give some insight into the environmental fate of ethyl xanthate in tailings streams, and a basis on which to consider the environmental importance of such species in tailings dams. Strategies for the destruction of residual xanthate levels in waste water streams are discussed in terms of the likely reaction products.

Jan 1, 2002

The purpose of this paper is to outline current research on the Paparoa and, at the request of conference organisers, to present a general introduction to the geology of the Greymouth Coalfield as background to more specialised papers. Few results of my present work will be given; these can be presented at the next conference. Briefly, the research aims for an understanding of the controls which depositional environment has exerted on coal character, to be reached by a study of coal type and thickness, shape and extent of seams, integrated with a basinal analysis of the coal measures. An accurate description of the coalfield in these terms should facilitate prediction of subsurface trends, with possible application to the planning of drilling programs, and to mine development. Although study of Paparoa coal types is included here as only part of the research, coal type should be recognised as an important concept which has until revently been almost entirely neglected in New Zealand.

Jan 1, 1979

SAG Mill Grinding Design Versus Geometallurgy - Getting it Right for Competent Ores Smarter processing for the future, in the area of SAG mill design involves accurate grinding test data, completing final mill design in less than three months, and at a cost of less than US$80 000. More detailed variability testing on the other hand takes longer, is more expensive, and is used for throughput optimisation for an existing or newly purchased mill. This paper shows that SAGDesignTM testing is excellent for new SAG plant design due to relatively low cost per test and the ability to do more testing for a limited budget on larger projects. It also briefly examines a way to develop proper geometallurgical ore hardness information on every block in the mine model, from the more detailed analysis data.

Sep 13, 2010

By K S. Fisher, J D. Pease

The installation of the George Fisher flowsheet in the lead/zinc concentrator at Mount Isa Mines Limited has recently been completed. The George Fisher flowsheet involved moving flotation capacity from the lead circuit to the zinc circuit and changes in zinc circuitry, changes in the reagent regime and increased regrinding capacity, using IsaMills, to regrind some streams to 80 per cent passing seven microns. The project was highly successful, delivering a five per cent increase in zinc recovery within a fortnight of commissioning. The George Fisher flowsheet was developed over six years. Laboratory work built upon the knowledge gained from investigating and processing the Mount Isa and Hilton orebodies. The engineering design and construction for the brownfield expansion of the existing lead/zinc concentrator had significant involvement from the operational, maintenance and technical personnel. Experienced personnel were seconded from the concentrator to the design and construction groups to ensure smooth integration of the new flowsheet into the existing concentrator with minimum downtime, and maximising the reuse of existing equipment. The combination of thorough design, good project integration with operations, and a good commissioning plan allowed almost immediate delivery of project gains. The project was highly successful, the full design improvements were achieved within two weeks, allowing the focus to move to developing future improvements.

Jan 1, 2000

By Michael Cruickshank

Bob Woolsey was born in 1936 in the state of Georgia and grew up to be a man of great integrity, vitality, wisdom and charm, totally neutral on matters of race, gender, and religion. A true Southern Gentleman in every sense of the word. His passing on July 9, 2008, the victim of an automobile collision, left an empty space in the hearts of his family, and his many friends and colleagues throughout the globe. The posthumous award of the Moore Medal of the International Marine Minerals Society, to Dr. J. Robert Woolsey for Excellence in the Development of Marine Minerals, is a well deserved tribute to this man who spent the last 30 years of his professional career heavily involved in research and development of marine minerals on an international basis. He first came to my attention in Burma in 1979 where, as a newly appointed technical advisor to the United Nations Development Program Offshore Exploration for Tin, I had to fill the shoes of an almost legendary figure "Dr. Bob", who accompanied by his wife Maxine had spent the previous two years initiating the program. Bob had planned to completion the construction in Singapore of a unique drilling vessel the RV Sea Drill, a spud anchored, twin-hulled barge, mounted with a Becker Drill, and designed for sampling alluvial tin deposits in the coastal waters of the Mergui Archipelago in the Andaman Sea, off Tenasserim. He had also designed and built, with the help of his side -kick Bruce Jernigan, a barge mounted dressing plant for reducing and concentrating the drill samples. The adventures of Dr. Bob in transporting the equipment to the drilling site in monsoon weather and the transfer of the drill barge from the Malaysian port of Ranong across the strait to Victoria Point in Burma with a mutinous crew will remain in the hearts and minds of his Burmese colleagues for many a long year. On his return to the States he joined, in 1980, the faculty of the University of Mississippi (UM) as assistant Professor of Geology and Geological Engineering. His prior experience in private industry and the United Nations had focused on marine mineral resources and related environmental engineering projects in Africa, South America, the Mediterranean, the South Pacific as well as south east Asia, working with dredges, mining for alluvial tin, gold, diamonds and industrial minerals. He continued to work in the area of marine minerals at UM, making a name for himself as Director of the Mississippi Mineral Resources Institute (MMRI).

Jan 1, 2008

By D. J. Hallbom

This paper presents a novel methodology for the hydraulic design of mine backfill distribution systems. The ?operating range? method uses the concepts of the hydraulic grade line and equivalent pipe length to determine flows and pressures as the pipeline route and static head change over the life of the mine. The operating range method is easy to learn because it is semi-graphical and uses well-known design concepts (e.g., the hydraulic grade line) and slurry design models (e.g., the Durand deposition velocity model). However, by changing the paradigm in which these concepts are used, the operating method allows all potential pipeline cases to be analysed simultaneously without the need to know the exact pipe routing. It also allows the hydraulics engineer to quickly identify ?pinch points? and ?slack flow? zones, to estimate the effect of changing the size or length of any given section of pipe, to assess the impact of changing the material properties of the backfill slurry, to size the slurry pumps, and to size and locate rupture discs when required.

May 1, 2007

By A. M. Hill

"This is an account of the expansion of Texasgulf's Timmins concentrator by the building of a fourth circuit.The original capacity of the mine and concentrator was 3.6 million tons per year of ore. In 1974, Texasgulf decided to increase that capacity by about one third to 4.8 million tons per year. It was planned that the increased capacity would be available by mid-1978.The expansion involved work at the rninesite, increased railroad capacity, and a new circuit in the concentrator, and it is the concentrator expansion which is described here.In 1974, the minesite drew its ore from the open pit. The pit was being phased out and was to be replaced by No. 1 mine. To allow for the expansion, a second mine was required. The railroad was capable of handling 18 car trains. Its capacity had to be increased to 27 cars per train and this, in turn, required two new locomotives. Each of these alone cost half a million dollars.The concentrator building in 1974 contained the concentrating equipment and miscellaneous services (such as machine shop, warehouse, analytical lab). The grinding and flotation sections were divided into three circuits ('A', 'B', & 'C'). 'A' and 'B' circuits treated copper-zinc ore and 'C' circuit treated the much more difficult copperzinc- lead ore. This 'C' circuit had been modified over the years to implement improvements in the metallurgy."

Jan 1, 1979

By Matteo Montesi

Deep foundation elements are often used as discrete elements in externally supported earth retaining structures such as soldier piles and lagging walls, secant/tangent pile walls, anchored walls, etc. These structures can be designed using different approaches such as conventional limit equilibrium methods, finite element/difference analyses, and soil spring (p-y) analyses which are contained in various commercially available computer programs used by engineers worldwide. Although these programs usually undergo various degree of verification and validation, users must be aware of each program’s limitations and conditions in which each design approach should or should not be used. These programs may incur difficulties when non-continuous deep foundation elements are used as part of the retaining system and in cases of non-uniform geometry where closed-form solutions are not available. Design input parameters such as passive arching width, wall-to-soil friction, and p-multipliers (pm) are not always given enough attention which may result in potential design deficiencies. This paper presents the main features of various earth retaining structure design approaches and discusses their advantages/disadvantages. The paper addresses some of the limitations and difficulties that may be faced with when utilizing non-continuous discrete deep foundation elements and identifies key elements that are sources of potential deficiencies and errors. An example comparing the design outcomes using different design approaches is presented. INTRODUCTION Earth retaining structures are used to retain soil and create or maintain a difference in ground elevation between grades in front and behind the retaining structure. Deep foundation elements have been used for decades to support earth retaining structures. Earth retaining structures that are supported by deep foundation elements are typically referred to as externally stabilized system (O’Rourke and Jones, 1990). An externally stabilized system uses an external structural element, in contrast to internally stabilized systems which rely on reinforcements installed within and extending beyond the potential failure mass. The design of externally supported retaining structures can be accomplished using different approaches, which can be challenging under certain conditions. Each approach has been discussed extensively in available literature, and is well summarized in the and Federal Highway Administration (FHWA) guidelines. The objective of this paper is to present the most widely used design approaches and discuss their limitations and difficulties in one concise and brief document, giving the reader a good source for comprehensive understanding of the various design approaches, supported by a technical example. This paper is not intended to be a comprehensive review of all available design methods and formulations available in the literature.

Jan 1, 2018

By Irving Palmer

DURING the past 15 years in this country there have been few additions to the literature of lead smelting. After the consolidation of the principal smelting companies at the beginning of this period it became the policy of the larger company not to permit the publication of details in regard to many of its metallurgical processes. This led to similar action on the part of some of its competitors. The result, of course, was a decided decrease in the number of papers written upon the practical side of the subject. Even upon the theoretical side the contributions have been few. It would seem that the industry as a whole has suffered from this general unwillingness to exchange information. While it is true that a given company is entitled to the reward that may come from its own development of a new process, it is also true that a still greater reward might be the result of a free exchange of ideas with other plants. This principle has been recognized for a long time in other metallurgical industries, notably those engaged in the smelting of iron and the manufacture of steel. It is pleasing to note that the leading lead-smelting company has very recently decided to modify its policy of secrecy, and to permit the publication of papers covering some details of its metallurgical methods. The statement has been made that there has been but little progress in lead smelting during the period just referred to. This impression is due in part to the scarcity of papers written on the subject. There has been, it is true, some discussion of the new sintering processes, but with little reference to detail, and to the effect that blast roasting has had upon the industry as a whole. In spite of the prevailing belief, it may be said that lead smelting, in common with other metallurgical industries, has made steady and substantial progress. It is the purpose of the present paper to discuss briefly some features of the industry as it is now conducted, with special reference to the blast-furnace practice in the larger silver-lead smelting plants of the United States and Mexico.

Jan 7, 1914

Coal has been mined in the central Appalachian coalfields of southern West Virginia, western Virginia, and eastern Kentucky for more than a century. The dwindling reserve base consists in large part of coal that would have been considered unmineable by earlier generations. Nearly every current operation is working on a property where coal has been extracted in the past, from seams either above, below, or both. NIOSH is conducting research aimed at helping mine planners prevent hazardous conditions due to multiple seam interactions. To-date, more than 300 case histories have been collected from underground mines, mainly from central Appalachia. This paper focuses on several of the more challenging situations that have been encountered, including: • Room-and-pillar development 20 ft (6 m) beneath full extraction workings at a depth of 1,000 ft (300m) of cover (Virginia) • Pillar recovery 45 ft above full extraction workings at 900 ft (270 m) of cover (Virginia) • Near-simultaneous room-and-pillar mining with pillar recovery with 40 ft (12 m) of interburden and 1,500-2,000 ft (450-600 m) of cover (Kentucky) • Longwall mining directly beneath main entries in overlying seams (West Virginia) • Some of these operations have been highly successful in overcoming the challenges, others less so. The lessons learned from their experience will help ensure that these and similar difficult reserves can be mined safely.

Jan 1, 2006

By Dean Workman

Located in downtown New York City, this project necessitated an innovative conveyor design for successful muck removal. This paper will discuss the technical challenges and engineering solutions of the muck transport system which consists of every commonly recognized version of a belt conveyor. The elaborate system includes a TBM conveyor integral to the back-up system, a wall-mounted extensible conveyor, a crown-mounted transfer conveyor, a floor-mounted fixed-length conveyor, a pocket-belt vertical conveyor, three cascading overland conveyors, and one radial stacker. The most challenging design element was an over-land conveyor featuring a box truss for muck transportation over Northern Boulevard while simultaneously going under the Queens Plaza railroad viaduct. An overview of the project is provided along with the following topics: developing final plans from the proposal concept, interfacing with existing works, communication with the joint venture, and complying with local regulations.

Jan 1, 2008

By Jesse Paegle

Um grande esforço foi realizado por diversas empresas, visando à melhoria de nosso parque industrial e, nos últimos 10 anos, o nível de investimento no setor foi importante. Este cenário, fez com que novas tecnologias surgissem por aqui, facilitando ao corpo técnico avançar com soluções mais eficazes para carroçarias. A disponibilidade local de todos os estágios da cadeia produtiva, desde a matéria-prima, até a adequação das linhas de manufatura das montadoras, afasta o efeito da variação cambial. A ideia que ficou impregnada no mercado brasileiro, é que novos materiais e tecnologias são caros para nossa região. O que não é verdade. Estudos de caso realizados antes de 2005, incluíam no preço, taxas de câmbio e internação, pois consideravam o produto importado. Com a localização este custo extra reduz. Ações governamentais atuam, hora incentivando localizações, hora definindo objetivos de emissões e segurança. O programa INOVAR AUTO estabelece algumas metas importantes de emissões, percentual de localização e promove o P&amp;D local. Todos estes ingredientes têm auxiliado no aumento da utilização de AHSS (Advanced High Strength Steel) nas estruturas veiculares. Usando os aços de alta resistência como base, temos um crescimento significativo. Em 2001 não passavam de 2% das carrocerias. Em 2008 chegaram a importantes 8%. Atualmente, estão próximo dos 15%.

Aug 17, 2017

By Ioannis K. Kapageridis

The lignite deposits of the Kozani-Ptolemais-Amyntaio basin in western Macedonia (North-West Greece) present a difficult modelling problem. Each deposit consists of several thin lignite layers ranging from a few centimetres to a few tens of centimeters in thickness, and thin intercalated sterile layers of marly limestones, marls, clays, and sands. These layers are practically impossible to model individually due to fast lateral transition of lignite layers to humus clay and vice versa and the lack of reliable and detailed stratigraphic correlation, leading to compositing methods being applied prior to any interpolation and modelling. The complexity of the deposit is further increased by the presence of a number of faults. This paper presents the modelling and estimation procedures applied during the most recent study of the South Western Field ? a new deposit that is considered for development and lignite production over the next years and will support the operation of a new power station in the area. Special focus is given to drillhole database structuring, fault modelling, stratigraphic correlation, mineable lignite intervals compositing, and resource estimation. The use of specialised mine planning software in all stages of modelling and estimation is thoroughly explained.

Oct 1, 2009

By Anand Raman, Steve Dixon

"Industry practice for defining acid consumption is based on column tests. Freeport-McMoRan (FCX) has adopted a practice of leach operation using a defined pH or gpl acid in the raffinate based on the column test program. The acid consumption can be easily calculated using the leach operating parameters of SX-EW efficiency, lift height, bulk density, irrigation rate, primary leach cycle time, acid cure dose and acid concentration in the raffinate. The column leach test results and a column to heap efficiency factor are used to define the copper extraction. The maximum acid consumption will occur when zero acid is contained in the raffinate. The term Net Extracted Value (NEV) is to define the maximum extracted value relative to acid consumed.This paper presents the operating logic and method used to calculate acid consumption based on column tests and operating parameters.INTRODUCTIONIndustry practice for defining acid consumption is based on column tests. This may result in lower economic value if the tests are not designed to account for operating variables. A test program is described to assist in defining lift height and the influence of gangue on solution chemistry. A simple spreadsheet is presented that will use the leach operating parameters of SXEW efficiency, lift height, bulk density, irrigation rate, primary leach cycle time, acid cure dose and acid concentration in the raffinate to calculate the acid consumption for a proposed operation.A review of current leach operations solution chemistry will help to define acid consumption. This is recommended for all current leach operations.DISCUSSIONThe current practice at Freeport-McMoRan (FCX) is the use of column test results to define operating parameters. The monitoring of operational solution chemistry and copper production addresses any changes needed in operational parameters. This practice maximizes the value extracted from each tonne of ore leached."

Jan 1, 2008