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At the 25th Peruvian Mining Convention, the start-up of Antamina was called ?the mining event of the year.? Antamina, one of the largestcopper-zinc mines in the world, began operations in May 2001.Augusto Baertl is Executive Chairman of Compañía Minera Antamina, the operating company. He said in a convention address that Antamina would be in full production in 2002. ?I would like to stress that Antamina is, in every respect, a highly stringent operation, as it intends to be the Peruvianmine of the future,? Baertl said. ?Antamina has set the target of being, and remaining throughout time, a model mine as to technology, environmental practices and social responsibility.? [ ] In the areas of technology and operations, Baertl noted that ?we have incorporated the best engineering design available and state-of-the art technology for mining, grinding and transportation processes, among others.? In the environmental area, he said that ?we have carried out careful environ-mental impact studies and have incorporated modern technologies and methods to control and minimize any environmental impact.? In the social field, Baertl noted that ?our relationship with neighboring communities is being developed under the premises of the social responsibility philosophy.? These include popular consultation processes, environmental committees and conciliation discussion committees. The purpose, he said, is to encourage communities located within the area of influence of the project to find and lead by themselves their path toward sustainable development, beyond the life of the operation itself.?

Jan 1, 2001

By Sergio Neves Monteiro

In the present work, a ceramic foam elaborated with illitic clays was characterized. Properties related to density and compression strength were determined in samples fired at 1300oC, a temperature that permits the clay structure to generate and retain gases that will produce the foamy structure. The microstructure of the ceramic foam was studied by X-ray diffraction, scanning electron microscopy and mercury porosimetry. The results showed that the ceramic foam presents a bulk density of 0.38 g/cm3. The microstructure is formed by large open pores, quartz particles and vitreous phase.

Jan 1, 2006

By Kevin J. Ashley

Coal is deposited at a mine site in several thin seams which outcrop in rolling hills and dip at about 8° to the northeast. The deposit is located in the northeast area of the State of New Mexico in the Southwest of the United States. A drilling program was undertaken and was quite irregular. Not all of the seams appear in all of the drill holes. Some of the holes did not go deep enough, while others were drilled below the outcrop of some seams. Occasionally a seam would pinch out and not be seen in a drill hole. Also, the outcrops of the seams are buried in many places by several feet of alluvium. All of these factors make correlation of the seams between drill holes difficult. The drawing of cross sections in three directions and at many locations across the mining area have been necessary to assure the accuracy of the input data.

Jan 1, 1982

By J Lyons, S Baker, D MacHunter, D Pepper

Mineral processing plants require a storage buffer to bridge differences in production rates between mining and processing. Where coarse ores are processed, such as coal or hard rock, this buffer may be an ore stockpile or silo. For wet-mining processes, eg dredging or hydraulic mining, or where fine ores are slurried close to the mining face, a surge-bin is used to contain the plant feed and smooth out the variations in mining rates. These bins have gradually evolved from simple storage vessels to units that are now frequently part of the mineral separation process itself, such as providing a desliming function to remove deleterious ultrafine gangue. This feed conditioning is often essential to achieve the levels of plant performance required in times of declining ore grades and or where inherent ore characteristics make separations harder to achieve. To achieve these dual roles requires careful consideration of bin design factors such as geometry and lining selection and increased use of instrumentation and advanced, or remotely supervised, control systems. All this ensures they provide capacity to smooth out variations in mining rates and guarantees that when conditioning ores or adjusting slurry densities ahead of the plant it is achieved without loss of valuable minerals. This paper examines the evolution of the modern surge-bin from a simple, so called, constant density tank with its inherent mass-flow compromises, limited feed preparation and beneficiation abilities, and footprint penalty, to a current state-of-the-art surge-bin, the LFCU, with a control system which provides demonstrable steady outputs, while conditioning and in some cases beneficiating the ROM material and all from a highly compact unit. It further discusses their use in other applications around the world, for example providing the necessary security for long distant high-density pumping systems; constant high density, low water usage, tailings disposal pipelines and high capacity ultrafine iron ore beneficiation.

Aug 24, 2022

There is a significant amount of historical mining and exploration information available. This information is often distributed throughout a number of reports or plans, available from a variety of sources, and in many differing formats. The ability to capture paper-based historical information in a modem digital format provides mining and exploration companies with valuable information that can be used in a number of ways; for example, reassessments of exploration or mining work previously undertaken, or used in conjunction with current exploration information.   The purpose of this paper is threefold. Firstly, to present the paper-based historical information; highlighting some of the problems encountered, solutions to those problems, and any assumptions used. Secondly, to present the historical data in digital format, and demonstrate the tools available to analyse geological and associated information, and finally, to illustrate some of the potential future applications of the information, including mining optimisation, mine design and scheduling.   The Glenorchy scheelite/gold prospect has been used as an example. Within the overall prospect two smaller areas were selected. The Mount McIntosh and surrounding areas, focuses on exploration and surface excavation information. The Mount Judah area (State and Kelly-Taylor workings) focuses on underground mining and exploration information.  

Jan 1, 2001

By J. A. Finch

Individual mineral cyclone performance curves were determined for the four major minerals at two lead-zinc concentrators. Sizing was by screen and cyclosizer down to approximately 10 um, with lead , zinc and iron as saying of each size fraction. The performance curves were similar in shape and located according to the mineral specific gravity, Pm. The curves displayed a discontinuity at the fine end and a magnitude of short-circuiting of fines to the underflow which increased with Pm. Mass fraction of water to the underflow was only a guide to this short-circuiting. Sharpness of separation seemed in dependent of Pm. An inflection in the over-all performance curve was shown to be a consequence of the individual component mineral performance. A general relationship was observed showing that the flow regime of classification changed from laminar/ intermediate to turbulent with increasing cyclone feed size. Individual mineral size reduction for the four major minerals at one of the concentrators was also determined. Size reduction of the silica was greater than that of the galena, in contradiction to their accepted relative grind-ability. The observation did correlate with silica being much coarser than the galena in the feed to the ball mill. It is suggested that the silica acted as a buffer to the galena.

Jan 1, 1977

By Frank Rausche, Scott D. Webster, Rozbeh B. Moghaddam

"Pile foundation driveability is a function of several variables such as subsurface characteristics, hammer type, hammer efficiency, pile type, and plugging conditions. One important phenomenon occurring during pile driving, and yet not well documented and published, is the friction fatigue, where a reduction of shaft resistance is observed as the pile is driven to greater embedment. This paper introduces current soil models developed for the assessment of friction fatigue, and further presents a comparison between predicted driveability obtained from Wave Equation Analysis Program (GRLWEAP) and field driving records. From a literature survey, and review of technical articles, a widely-used soil model known as AH-01 has been selected to analyze the friction fatigue concept. Using a WEAP software, two driveability analysis were completed using the standard approach with setup factors, and adapting the AH-01 model into the WEAP input file. Driveability predictions were compared to the driving records corresponding to a 1676-mm x 44- mm open-ended pipe pile with a total and embedment lengths of 180-m and 119-m, respectively. Results from analyses and the comparison presented in this paper provide further information regarding existing methods for the incorporation of the friction fatigue concept to the driveability analyses, and contributes to a better prediction of driveability of open-ended pipe piles. IntroductionDynamic measurements during pile installation provide more dependable information as compared to results obtained from predictive models used for design. Despite uncertainties associated with a specific project site and foundation type, measured data provides a reliable understanding of the soil resistance and its distribution throughout the length of the pile. Back-calculations or back-analyses based on a series of measured data from a pile driving process could help to obtain reliable models to better predict events related to pile installation process in spite of all variability related to fitted models. One of the widely-used analysis regarding pile driving during the design phase is the “driveability analysis” where capacity, blowcounts, maximum stresses in the pile element, and transferred energy from the hammer to the pile element are predicted using mathematical models along with a software. Such analysis requires relevant information regarding soil, pile, and hammer properties combined with a deep understanding of the level of impact each one of these properties could have on the analysis."

Jan 1, 2017

By Xubo Chen, Zhiqiang Hu, Zhijian Sun, Gaoyun Zhou

"The research aimed at developing an efficient and environmental frother,which was applied in the flotation of sulfide ores. The flotation properties of an efficient frother and pine oil have been studied relatively by flotation tests of lead and zinc sulfide ores. At the same time, the biodegradability of two kinds of frother has been studied by the method of biological respiratory curve. The test results show that the flotation properties of new frother are superior to pine oil such as flotation rate, dosage etc. and its biodegradability is superior to pine oil. INTRODUCTION Frother is a kind of important agent in flotation reagents.In practice, the criterion of the foaming performance of the frother is what is high and low according to flotation indexes. The difference of different minerals and flotation technologies has great influence on the foaming performance of frother, and it is very important to choose the corresponding frother. The type, dosage and selectivity of frother in flotation process must be considered carefully. In today's society, environmental protection and ecological protection are becoming more and more important, and the environmental and ecological damage from mine development has aroused increasingly more attention. The use of mine agents has promoted the development of mineral resources, greatly improves the recovering utilization of mineral resources, at the same time, the production and use of mine reagents also inevitably bring about pollution, and result some influence or damage in the ecological environment.The frother is a common kind of reagent in the flotation process of the concentrator. In many cases, the waste water in the concentrator can not be let out in the natural water because the higher content of the frother in the waste water results in higher index of COD.This will inevitably increase the cost of waste water treatment in the mine.Therefore, the choice of frother should not only consider its influence on the flotation index, but also consider its influence on environmental protection. Waste water treatment is a way to solve the waste water pollution, but it needs to cost a lot of fund, manpower and material resources.And the development of high efficiency pollution-free reagent is a good way to reduce the production cost of mining enterprises and reduce the environmental pollution."

Jan 1, 2018

By S Dorrington, J Olsen, N Kinkaid

Several studies have been conducted on the economic analysis of mining near-Earth asteroids for resources for use in Earth orbit. While these studies use detailed economic figures of merit, they often use many invalid assumptions in the trajectory design. Factors such as the energy and propellant requirements are estimated with analytic methods, however, the stay-time at the asteroid and the spacing of repeated launch opportunities are not taken into account. The work outlined in this paper attempts to combine detailed trajectory design methods with newly defined economic figures of merit to improve the economic assessment of asteroid mining missions. The study focuses on asteroid 2014 EK24, a near-Earth asteroid with very Earth-similar orbital properties.CITATION:Dorrington, S, Kinkaid, N and Olsen, J, 2015. Trajectory design and economic analysis of asteroid mining missions to asteroid 2014 EK24, in Proceedings Third International Future Mining Conference, pp 281–288 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By B Y. Luan, Y Tian, W Zhou, X Lu, Q X. Cai

The unmanned driving technology in open pit coalmines is an important technology that relies on innovation to drive the development of the open pit coal mining industry in China’s transformation of growth drivers and industrial structure upgrading. It is an important path to solve the shortage of mine truck drivers in the future mining, an important way to improve the working environment of open pit mining personnel, and an important foundation for achieving flexible production capacity in open pit mining to cooperate with the coordinated development of new energy. The communication rules at intersections are key to ensuring the safety and efficiency of unmanned driving in open pit coalmines. This paper proposes a collaborative traffic strategy between unmanned trucks for the single bucket unmanned truck intermittent process system in open pit coalmines. Based on the gap theory, this paper analyses the conflict characteristics and establishes a coordinated traffic strategy for the common intersection and merging conflicts of unmanned truck trucks in open pit coalmines, A multi-agent system simulation platform was built to evaluate the coordinated traffic efficiency under different initial average gap sizes of vehicles, with intersection traffic density, vehicle speed, and gap changes as key indicators. The results show that under the simulation conditions of this article, when the initial average gap of vehicles reaches three (four) times or more of the safe distance, the coordinated traffic performance of intersection conflicts (merging conflicts) is better, and the traffic capacity of intersections is close to the traffic capacity without conflicts.

Sep 1, 2024

By Wayne Trudel, Lloyd McEvers, Lori Clarke, Eric Saderholm, Charles Lynn Bolin, Leroy Schutz

Newmont mine geologists in Nevada are most proficient when applying technical expertise with multi-departmental teams in three main settings. The first is value creation through near-mine discovery, development and reserve conversion. Since 1986, geologists have created substantial net asset value in developing more than 1.35 kt (43 million oz) into quality Nevada surface and underground gold reserves. The second setting is value realization by supporting mine operations with ore control, selective mining, reconciliation investigations and strategic planning. The investment of technical research on reconciliation investigations led to new concepts and practices that highlighted opportunities for large revenue and reserve gains. In 2002, more than $65 million in projected revenue was added to the Gold Quarry south layback. Kriged mine polygon construction and controlled blast heave at the Lone Tree Mine provided millions of dollars in mining efficiencies. High-quality geologic advice in selective mining at the Twin Creeks Mine helped obtain $4.3 million revenue gains throughout 2002-2003.

Jan 1, 2004

By K. Tangri, M. Chaturvedi

On water-quenching from within the (a + ß) phase region Zr-2.5 Nb and Zr-2.5 Nb-0.5 Cu alloys can undergo w transfirmation. This transformation has been attributed to the enrichment of ß Zr phase, at the solution-treatment temperature, by the solute atoms. The ß—w transformation is accompanied by a hardening 01 the alloys and in the optimum condition w-bearing specimens of the ternary alloy are about 14 pct harder than those bearing only a' phase. On aging crl reverls thermally to more stable phases, which results in a considerable softening of the specirnens, as follows: w quenched -waged + ß Zr (enriched) waged - a + ß Nb The high-temperature bcc ß Zr in certain zirconium alloys can transform to a metastable w phase which has a primitive hexagonal structure. In the Zr-Nb alloy system w phase has been observed in the composition range of 7 to 15 wt pct Nb by a number of investigators.'-' In this composition range w can form by water-quenching ß Zr or by aging. known as athermal and thermal w, respectively. Hatt and Roberts' have found that thermal w has a constant c/a ratio of 0.622 +0.002 regardless of the composition and tha: the lattice parameters are of the order of a = 5.02A and c = 3.0 ?. The actual lattice parameters depend upon composition and the temperature of aging. The lattice constants of athermal w. however, depend upon alloy composition.3 The presence of w phase in zirconium alloys can cause substantial strengthening which has been attributed as probably due to the coherency between w and parent ß Zr phase. Robinson et al.' found that the presence of w can raise the strength of Zr-5.0 Nb-2.0 Sn and Zr-5.0 Mo-2.0 Sn alloys to about 170.000 psi: however. the ductility is considerably reduced. With the growing use of Zr-2.5 Nb and Zr-2.5 Nb-0.5 Cu alloys in the nuclear reactors, and the significant effect of w transformation on the mechanical properties of zirconium alloys studies were undertaken to study the w transformation in Zr-2.5 Nb and Zr-2.5 Nb-0.5 Cu alloys. This paper is concerned with the formation and reversion of w phase in these alloys. 1) MATERIALS AND EXPERIMENTAL TECHNIQUES The following two alloys were studied: 1) Zr-2.5 Nb-0.5 Cu (referred to as the ternary alloy): 2) Zr-2.5 Nb (referred to as the binary alloy). The chemical analysis of the alloys is given in Table I. The alloys, in the form of 3/8-in.-diam rods and 1/8-in.-thick sheets, were supplied by the Chalk River Nuclear Laboratories of the A.E.C.L. Initial fabrication for preparation of various specimens was carried out by cold rolling and swaging with intermediate anneals at 1000°C. All the heat treatments were carried out after the specimens were wrapped in zirconium foils and encapsulated in silica tubes under a vacuum of 5 x 10-% m of Hg. For optical metallography and hardness measurements disc specimens + in. diam by + in. thick were used. After the required heat treatments the specimens were mechanically and then chemically polished in a 45 pct HNO3, 45 pct H20. and 10 pct HF solution. The hardness measurements on the chemically polished specimens were carried out on a Vickers hardness tester using a 10-kg load. For each specimen at least fifteen indentations were made in order to obtain a representative hardness value. The phase identification and structural analysis were carried out using X-rays and electron diffraction techniques. Wires of 1.5 mm diam reduced to 0.12 mm diam by chemical etching were used for making Debye-Scherrer powder patterns using copper K-a radiations in 114.6-mm-diam camera. Thin films for transmission electron microscopy were prepared by electropolishing heat-treated a by 7 by 0.005-in.-thick strips using a modified Bollmann-Window technique. The 10 pct perchloric acid-90 pct methyl alcohol electropolishing bath was kepl at -5OCC and polishing was done at 5 to 10 v. The thinned specimens were washed in ethyl alcohol at -30" to -40°C and dried between filter papers. The thin films

Jan 1, 1970

By Guo Xueyi

The method of Substance Flow Analysis (abbreviated as SFA) provides a helpful tool for the study of the industrial metabolism of a certain metal within a regional level. In this work the flow of lead in China, 2006, was traced within the STAF model, and the situation of production, consumption and recycling of lead resources in China were introduced. The SFA is performed on lead flows during its one year life cycle in detail. As one of the biggest producer and consumer of lead in the world, China is facing a problem depletion of lead resources. How to increase the resource efficiency is a significant issue for lead industry of China. Based on the result, several suggestions were proposed in the paper, aiming to contribute important reference information for the industrial metabolism and resource management and recycling of lead industry in China.

Jan 1, 2009

By Frederick Bacorn

THE paper of Reno H.. Sales on Ore Deposits at Butte, Mont.,' is a careful and painstaking work, an important contribution to the literature of the subject. As is almost inevitable in a work of such magnitude, a few misstatements occur; and some of these I shall endeavor to point out. Mr. Sales has also fallen into error, as I think, in the application of his theory of ore deposition; and while the modification which I venture to suggest is a minor one geologically, it is of great economic importance. I refer to Mr. Sales's idea of an outward migration of mineralizing solutions from a supposed central copper zone. In order that I may make myself plain, I must first epitomize the theory as a whole, which I understand to be this: All of the Butte ore deposits (save those along the Continental fault, not herein considered) are derived from solutions of magmatic origin, which, at the beginning of their ascent from a great depth, were, acid in reaction, hot, and were carriers of copper, zinc, manganese and other metals. As they departed from their point of origin they lost heat, and, because of reactions with the wall rock, became more and more alkaline. The metal deposited from these solutions in their hot condition was principally copper; and, as they cooled, they deposited less and less copper and more and more manganese and zinc, until the copper practically disappeared. With this theory in general I have no fault to find, nor have I, it must be stated, the qualifications necessary to enable me to pass upon it critically; but it seems to me to be reasonable and probable, and is one which I am quite willing to accept.

Jan 8, 1914

By Stephen H. Stow

The relationships between the amount of light reflected off 21 samples of Florida phosphate and the chemical, composition of the samples were examined. It was found that the reflectivity of a rock is directly related to its chemical composition and that darker phosphates (less light reflectance) have relatively high amounts of iron, organic C and sulfate while lighter-colored rocks were rich in phosphorus, fluorine and aluminum. The use of reflectivity measurements could have economic applications in the phosphate rock industry: color specifications for rock shipments could he met, beneficiations by optical sorting could be performed and semi-quantitative analyses could be made rapidly and inexpensively.

Jan 1, 1971

By K. Awuah-Offei, A. U. Rehman

"Information diffusion potential of a social media user affects how quickly information about a mineral project can diffuse through that user. If management can use social media and network analysis, in community engagement program, to understand how fast and how far information will diffuse to communities and followers of particular social media users, it can selectively focus on the most influential users. This paper proposes a method to examine the information diffusion potential of social media accounts. The work uses Gephi, an open source software, to extract and analyze data from different Twitter handles to predict their information diffusion potential. The work uses case studies of real Twitter users (e.g. mining news organizations and bloggers) associated with mining to illustrate the approach. The case study results show that there are significant disparities in information diffusion potential that will demand selective attention. This research will help mines develop effective social media engagement strategies. INTRODUCTION The mineral industry provides raw material for industrial activity to support our society (Martens and Rattmann, 2001). Mines have changed conventional mining practices to sustainable ones because of the negative impacts of mining and increased public awareness (Wang et al 2016). The concept of sustainable mining is getting mature as stakeholders (e.g., governments, investors and host communities) are getting involved in mining projects (World Economic Forum, 2014). The failure of mining companies to address the demands of these stakeholders might result in failure to acquire social license to operate (Thomson and Boutilier, 2011). The social license to operate (SLO), if granted, is mutually beneficial to all stakeholders. Mines prefer being granted SLO and keeping it to avoid any kind of social unrest due to their operation (Prno, 2013; Moffat and Zhang, 2014). Mining communities can grant different levels of SLO; ranging from withholding SLO to psychologically identifying with the project (Joyce and Thomson, 2000; Thomsan and Boutilier, 2011). Most of the previous work to understand community perceptions and SLO in mining is generally qualitative (ICMM, 2012a; Thomson and Boutilier, 2011; Prno, 2013; Moffat and Zhang, 2014; IFC, 2014). In particular, there is limited work on how community perceptions change over time due to information diffusion (Boateng and Awuah-Offei, 2017). However, SLO changes with respect to time (Yates and Horvath, 2013), which can result in risks that are not easy to predict. Mine managers and engineers have a desire to understand these changes so as to mitigate these risks (Que and Awuah-Offei, 2014; Que et al., 2015)."

Jan 1, 2018

By O. Lopez

"Stringent regulations and increased arsenic presence in ore bodies being exploited have created the need for cost effective and environmentally compliant technologies to remove selenium and arsenic from mine waters and metallurgical waste streams. Existing treatment methods have high life cycle costs and/or produce residues that, due to their unknown stability over the long-term, may represent future liabilities. This results in high compliance costs and uncertainties which negatively impact existing operations and projects in permitting. Selen-IX™ is a new ion exchange based process that selectively removes selenium from mine impacted waters down to 1 ppb while producing a stable inorganic iron-selenium product. Results of piloting completed on streams generated from coal and copper-gold deposits are presented along with preliminary equipment sizing and life cycle costs of full scale treatment. An example of a commercially available system for arsenic removal using sulphide precipitation is presented. The benefit of this treatment method is discussed based on recently completed technical feasibility assessment including laboratory testing and preliminary engineering design. INTRODUCTION Selenium Due to the chemical similarity between selenium and sulfur, selenium substitutes sulfur in many minerals that can be found in a wide range of deposits including coal, base metal, precious metal, phosphate, and uranium. One of the main environmental challenges facing the industry in North America today is related to the removal of hexavalent selenium, e.g. selenate, to ultralow levels, typically between 1 to 10 ppb, from large flows of often cold water containing less than 1,000 ppb of selenium. Recent studies commissioned by the industry identified biological selenium reduction systems as the best available technology. Although the biological selenium reduction process is commercially proven in certain applications to remove selenium to ultralow discharge levels, the technology has been primarily applied to relatively low and constant flows of warm water produced by the Flue Gas Desulfurization (FGD) scrubbers in the power generation industry. The wide spread adoption of this treatment method by the mining industry is hindered by high capital and operating costs associated with treating large flows of cold water, lack of data and knowledge about the long term stability of solid residues produced by this treatment, and limited capacity of biological systems to respond to sudden changes in flow and/or mass load of contaminants. Furthermore, it has been reported that reaching discharge limits less than 3 ppb could be a challenge and that polishing treatment for the removal of BOD and phosphate maybe required to avoid the impact of the biological treatment which requires organics and nutrients, on aquatic environment downstream of treatment plants. Alternate treatment systems are being developed to overcome and/or completely avoid some of the challenges of biological systems. One such treatment system is BioteQ’s Selen-IX™ process which is purely physico-chemical treatment system."

Jan 1, 2015

By Douglas R. Burns

Complying with SARA-Title III and the Emergency Planning and Community Right-To-Know Act as a Non-Manufacturing Facility. As of August 23, 1988 non-manufacturing facilities storing end using chemicals which require MSDS (Materia1 Safety Data Sheets) must fi1e with SERC (State Emergency Response Commission), the LEPC (Loca1 Emergency Planning Commission), and the loca1 Fire Department a list or copies of all MSDS sheets with the Tier I and Tier II forms completed.

Jan 1, 1989

By Richard L. Bullock, Bruce Kennedy

Vince Lombardi once said, "Practice doesn't make perfect, perfect practice makes perfect." When it comes to building a mine that will operate at the optimum level for the set of geologic conditions from which it was developed, Lombardi's remark might be paraphrased to describe the problem: planning won't guarantee the best possible mine operation unless it is the best possible mine planning. Any sacrifice in the best possible mine planning introduces the risk that the end results may not reach the optimum mine operation desired. This section addresses many of the factors to be considered in the initial phase of mine planning. These factors have the determining influence on the mining method, the size of the operation, the size of the mine openings, the mine productivity, the mine cost, and, eventually, the economic parameters used to determine whether or not the mineral reserve even should be developed. A little-known fact, even within the metal-mining community, is that room-and-pillar mining accounts for most of the underground mining in the united States. According to a 1973 study on noncoal mining (Anon., 1974), more than 76% of the producing mines [of over 1089 t/d (1200 stpd) capacity] produced approximately 70 000 000 t (77,000,000 st) or 60% of the nation's underground tonnage of material by room-and-pillar mining. That same year, 96.8% of the nation's under- ground coal mines produced 262 950 000 t (289,911,000 st) of coal extracted from room-and-pillar mines (Anon., 1976). Thus, nearly 333 000 000 t (367,000,000 st) of the United States' raw material is produced from mines using some form of the room-and-pillar mining system. Because approximately 90% of all mining in the United States is done by some variation of room-and- pillar mining, it is appropriate to give special emphasis to the effects of the various elements of mine planning on room-and-pillar mining. The relationship of these elements to other mining methods will become apparent as the elements are described in later sections herein. TECHNICAL INFORMATION NEEDED FOR PRELIMINARY MINE PLANNING Assuming that the reserve to be mined has been delineated with diamond-drill holes, the items listed in the following paragraphs need to be established with respect to mine planning for the mineralized material. Geologic and Mineralogic Information The geologic and mineralogic information needed includes the following: 1) The size (length, width, and thickness) of the areas to be mined within the overall area to be considered, including multiple areas, zones, or seams. 2) The dip or plunge of each mineralized zone, area, or seam, noting the maximum depth to be mined. 3) The continuity or discontinuity within each of the mineralized zones. 4) Any swelling or narrowing of each mineralized zone. 5) The sharpness between the grades of mineralized zones within the material considered economically minable. 6) The sharpness between the ore and waste cutoff, including whether this cutoff can be determined by observation or must be determined by assay or some special tool; whether this cutoff also serves as a natural parting resulting in little or no dilution, or whether the break between ore and waste must be induced entirely by the mining method; and whether or not the mineralized zone beyond (above or below) the existing cutoff represents submarginal economic value that may be- come economical at a later time. *7) The distribution of various valuable minerals making up each of the minable areas. 8) The distribution of the various deleterious minerals that may be harmful in processing the valuable mineral. 9) Whether or not the identified valuable minerals are interlocked with other fine-grained mineral or waste material. 10) The presence of alteration zones in both the mineralized and the waste zones. Structural Information (Physical and Chemical) The needed structural information includes the following: * 1 ) The depth of cover. 2) A detailed description of the cover including: the type of cover; * the structural features in relation to the mineralized zone; * the structural features in relation to the proposed mine development; and * the presence of and information about water, gas, or oil that may be encountered. 3) The structure of the host rock (back, floor, hanging wall, footwall, etc.), including: * the type of rock; * the approximate strength or range of strengths; * any noted weakening structures; * any noted zones of inherent high stress; noted zones of alteration; the porosity and permeability; * the presence of any swelling- clay or shale interbedding; the rock quality designation (RQD) throughout the various zones in and around all of the mineralized area to be mined out; the temperature of the zones proposed for mining; and the acid generating nature of the host rock. 4) The structure of the mineralized material, including all of the factors in item 3 plus: * the tendency of the mineral to change character after being broken, i.e., oxidizing, degenerating to all fines, recompacting into a solid mass, becoming fluid, etc.; * the siliceous content of the ore; the fibrous content of the ore; and the acid generating nature of the ore. Economic Information The needed economic information includes: *1) The tons of the mineral reserve at various

Jan 1, 1982

By K. A. Smith, X. Cheng

Introduction The separation of minerals from complex sulfide ores by flotation requires careful control of the surface chemical behaviors of the minerals constituting the ores. When the minerals in the ore are finely disseminated, extremely fine grinding is needed to liberate the minerals. Fine grinding is not only an energy-intensive operation, but also influences the flotation behaviors of liberated minerals. Steel balls are commonly used for grinding. Galvanic interactions occur not only between sulfide minerals and grinding media but also among the different sulfide minerals themselves. The electrochemical characteristics of chalcopyrite and pyrrhotite when they are independently coupled with steel grinding media and the relevance of these characteristics to the flotation behavior of these minerals have been exten¬sively studied (Cheng and Iwasaki, 1992: Li and Iwasaki, 1992). These studies dealt with reactions in two electrode combinations, simulating mineral-grinding medium and mineral-mineral interactions. In practice, however, it is more common to involve more than one sulfide mineral. In a study of a pyrite-pyrrhotite-mild steel system, Pozzo et al. (1989) provided evidence that a mineral having an intermediate potential could behave differently, depending on the condi¬tion of galvanic contact. This investigation was undertaken to study a chalcopyrite-pyrrhotite-mild steel system to gain better in¬sight into the mechanism of multiple galvanic interactions. A three-electrode system was chosen to simulate a typical copper sulfide ore. The sulfide minerals were represented by chalcopyrite and pyrrhotite. The grinding medium was rep¬resented by mild steel. The nature of galvanic interactions involving these minerals and grinding medium in an oxygen atmosphere was investigated in a three-electrode combina¬tion, and an attempt was made to relate the laboratory flotation results of pyrrhotite-chalcopyrite ores. Possible implications to the differential flotation of complex sulfide ores are discussed. Key words: Electrochemistry, Flotation, Sulfide ores Experimental The pyrrhotite (57.74% Fe, 0.09% Cu, 4.84% Ni and 36.54% S) sample was obtained from Falconbridge Ltd.'s Strathcona mine, Ontario, Canada, and the chalcopyrite (26.00% Cu, 28.57% Fe, 0.05% Ni and 31.52% S) sample came from Transvaal, South Africa. Mild steel (AISI 1020, 0.2% C) was chosen to represent grinding media. A conventional three-electrode cell was used in the elec¬trochemical measurements. The working, counter and refer¬ence electrodes were, respectively, sulfide minerals or mild steel, graphite rod and saturated calomel electrode (SCE, 0.245 V vs. standard hydrogen electrode). The exposed areas of the sulfide minerals and grinding medium electrodes were approximately the same (0.17 to 0.19 cm2). The preparation methods of working electrodes, the reagents used, the experi¬mental procedures and the instrumentation were the same as those described previously (Cheng and Iwasaki, 1992). Rest potentials of pyrrhotite, chalcopyrite and mild steel were measured individually in 0.05-M sodium sulfate solu¬tions. Combination potentials and galvanic currents of the sulfide minerals and grinding medium were measured in short-circuited two- and three-electrode systems. All poten¬tials in this study are quoted in volts with respect to the standard hydrogen electrode (SHE). To simulate the constantly abrading conditions in a ball mill, rest potentials, combination potentials and galvanic currents were also measured by rotating a porcelain ball against chalcopyrite, pyrrhotite and mild steel electrodes in

Jan 1, 2000