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By N. J. Peberdy, C. N. Moreton, K. C. Garner

Introduction During the past decade a major objective of the process industry has been to use digital computer technology to improve plant operating efficiencies. This objective implied some form of optimization, a concept that has various interpretations depending on the view of the prospective user. For the purpose of this paper, optimization of a process plant is defined as the establishment and setting of plant operating conditions that maximize some mathematical yield function, i.e. maximum profit, minimum residue, etc. Analysis of these objectives and the available design and implementation techniques led to the conclusion that digital computer and optimization techniques are not the stumbling blocks, but rather the development and derivation of the mathematical models of the unit operations and process plants to be optimized. Such models should not only describe the optimized (steady-state) objective, but also how one steers to this state (control algorithm). Due to the multidisciplinary nature of the skills associated with the design and operation of process plants, the development of suitable models by a single discipline, such as the process control engineer, was found to be not only difficult but often impossible, due to budget and human resource limitations. To over-come these limitations, a computer aided design (CAD) tool has been developed. It aims to provide a productivity tool to the various disciplines, at the same time coordinating the technical input from each. The system described is but the starting point in an evolutionary development of a tool that, with use, is becoming more efficient and cost effective to use. Development has become an application engineering activity rather than the preserve of the computer specialist. Project phasing The development of a mathematical description of a process plant requires coordination of information from conceptual design to operation management. The activities required to build and operate a process plant are divided into four basic chronological activities or phases. These activities are often undertaken by different organizations and disciplines. As a result, continuity is often lost with the resultant loss of critical design data. The major activities are considered to be: conceptual and flowsheeting; detailing around the P & ID; building and commissioning; and plant operation. The CAD system described provides a design tool to be used for each of these activities, as well as providing continuity between the activities and the disciplines involved. The heart of the system is the dynamic simulation of the flowsheet. Each of the activities will be discussed, leading to two simple examples that demonstrate the use of the simulator. Figure 1 shows a schematic format of the various activities and the path followed by the dynamic flowsheet simulator in the life of a project. Flowsheet development The prime requirements in the design and develop¬ment of a process flowsheet are • selection of the correct unit operations to achieve the most economic (capital and operating) beneficiation of the specified reserve ; • the sizing of the unit operations to achieve the desired results, as a function of the projected feed rates etc., to handle the time related (dynamics) of the process; and • the production of a set of engineering documents showing the drawn and labeled flowsheet with an equipment list and process specification for each of the unit operations. The question may well be asked at this stage why dynamic flowsheet simulation should be considered when steady state modeling has been found to be adequate to date. With the increases encountered in the cost of capital, one often cannot afford the luxury of designing around the compounding worst case technique. Further, a more accurate design of the control surges can be achieved. No information is lost in that the steady state solution is in fact a subset of the dynamic model. In generalized state space modeling, the differential equations describing the process dynamics are illustrated in the following matrix notation: XDOT=A.X+B.U(1) Y =C.X+D.U(2) where XDOT describes the set of first order derivatives of the system state Vector, and X- is the system state Vector; A - is the system matrix operator which in the general nonlinear case is both a function of X and time ; U- is the process input vector; B - is the input mapping matrix; Y - is the set of observations; C - is the output mapping matrix which maps X - onto Y; and D- maps the input onto the observations. Thus, by time integration of the system dynamic equations, described in (1), the dynamic trajectory away from any set of initial conditions can be deter¬mined. Further, by finding the conditions at which XDOT = 0, the steady state solution can be determined.

Jan 1, 1987

By Xiyu Gao, Yi Yang, Mark I. Pownceby, Shuiping Zhong, Miao Chen

In the present study, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray absorption near edge structure (XANES) spectroscopy, and Raman spectroscopy were used to investigate the effect of chloride ions on chalcopyrite bioleaching and chemical leaching at 25 °C. The leaching results show that the addition of chloride ions suppressed the dissolution of chalcopyrite in both chemical and bacterial leaching. In chemical leaching, the solution redox potential in the experiment without Cl− stayed in a range more suitable for chalcopyrite dissolution compared with experiments with Cl− . In bioleaching, the bacteria activity was suppressed by Cl− leading to low dissolution rates of Cu. Surface morphology and chemical speciation studies confirmed the formation of potassium jarosite on the surface of the chalcopyrite leach residues. In addition, S K-edge XANES indicated the formation of trace amount of elemental sulfur and covellite on the mineral surfaces.

By T. Bednarski, T. McCallum, L. Moya, B. Gay

"Molybdenum recovery by solvent extraction has gained interest partly due to advances in concentrate leach technology. Historically, both molybdenum and rhenium have been produced using amine-based extractants with the ability to co-extract both metals. Alternatively, a phosphinic acid-based extractant (CYANEX® 600) can be used depending on the flow sheet. CYANEX® 600 selectively extracts Mo leaving Re in the raffinate, which is a valuable feature in plants which require rejection of the rhenium from the molybdenum circuit. CYANEX® 600 piloting results are reviewed and compared to commercial experiences with an amine-based extractant. INTRODUCTION Molybdenum is most commonly found as molybdenite (MoS2) in primary porphyry deposits (about 59% of global reserves) and copper porphyries (about 39% of molybdenum reserves)[1]. Recovery from molybdenite traditionally involves flotation (concentrates typically containing 85 – 95% MoS2) followed by roasting to produce MoO3. Solvent extraction is also used to recover molybdenum from acidic aqueous solutions resulting from scrubbing of roaster and smelter off gasses and leaching of molybdenite (uranium ores). Molybdenum is also frequently found in low concentrations in copper leach inventories[2]. More recently, pressure oxidation has gained interest to treat molybdenite concentrates. Molybdenum Chemistry The chemistry of molybdenum is complex with a series of extractable species existing dependent on the pH and oxidation state as shown in Figure 1.Under strongly basic conditions, molybdenum primarily exists as MoO42- while under strongly acidic conditions MoO22+ becomes the predominant species. In between, a number of isopolymolybdates such as Mo7O246- and Mo8O264- are dominant. Equations (1) – (3) demonstrate some of the proposed molybdenum equilibrium reactions[1]."

Jan 1, 2017

By Brendan Demich, Linda L. Chasko, Brendan Macdonald, Timothy J. Orr, Jessie J. Mechling, Cassandra Hoebbel, Jason Navoyski, William Helfrich, Jessica Cohen, Paul E. Schmidt, Jennica L. Bellanca

The National Institute for Occupational Safety and Health (NIOSH) in partnership with the Mine Safety and Health Administration (MSHA) developed VR Mine Rescue Training (VR-MRT). It is a training platform that allows mine rescue team members to explore virtual emergency scenarios collaboratively. Team members use a head-mounted display to visualize and interact together with equipment, hazards, and dynamic ventilation. All player actions are recorded and displayed for debriefing. Researchers at NIOSH demonstrated the training platform at various mine rescue competitions, including the International Mine Rescue Competition, and collected feedback. Participants’ responses were overwhelmingly positive. This paper describes the development of the software platform and the results of the usability surveys and interviews.

Jun 25, 2023

By J. Sammarco

Proper illumination is critical to a miner?s ability to detect hazards in underground mines. Moving hazards are often located in the miner?s peripheral field-of-view, while slip/trip/fall hazards are often located in the forward field-of-view. The objective of the research described in this paper was to determine if light-emitting diodes (LEDs) improve visual performance as compared to traditional incandescent (INC) cap lamps. The research presented focuses on comparative studies of a National Institute for Occupational Safety and Health (NIOSH) prototype LED, a commercial LED, and an INC camp lamp. Thirty subjects participated in these studies; ten subjects in each of the age groups: 18 to 25 years, 40 to 50 years, and 51+ years. Visual performance was quantified by the subjects? speed and accuracy in detecting hazards, while visual performance for disability glare was quantified by the use of contrast sensitivity tests. Results suggest that LEDs with a visible spectrum containing a higher concentration of the shorter wavelengths can enable visual performance improvements with respect to disability glare, the detection of moving hazards in the peripheral field-of-view, and the detection of floor hazards in the forward field-of-view. The NIOSH prototype LED cap lamp provided the best visual performance improvements for the older age groups in every test. Disclaimer: The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.

Jan 1, 2009

"Foreword by Lisa SchlinkSuperintendent, operations, Freeport-McMoRan Inc.,Green Valley, AZ, USAThe sixth annual Student Poster Contest hosted by the Mineral & Metallurgical Processing Division of the Society for Mining, Metallurgy & Exploration was held during the 2015 SME Annual Conference and Expo in Denver, CO. The contest had another record-breaking attendance of 31 entries: 27 graduate and four undergraduate. The universities represented were: Colorado School of Mines, South Dakota School of Mines and Technology, University of Kentucky, University of Utah, Southern Illinois University Carbondale, University of Wyoming and West Virginia University.The competition began with an extended abstract review by a panel of judges selected from MPD members. At the SME Annual Conference, all students displayed their posters, highlighting their research. The students with the top abstracts from the graduate and undergraduate divisions presented their research at the MPD Student Poster Session Wednesday morning. The panel of judges then provided tallied scores for the abstract, poster and presentation to determine the winners of the 2015 Student Poster Contest. The first- and second-place winners of both the graduate and undergraduate divisions received $1,000 and $500 scholarships, respectively. The third through seventh places received $200 each, and all other entrants received $100 each and were invited to join the MPD Luncheon.In the undergraduate division, Annette Hein of the University of Wyoming received first place for her research on “Solvent Extraction of Europium from a Nitric Acid Solution.” Second place went to Jennifer Galvin of South Dakota School of Mines and Technology for her research titled “Solvent Extraction of Neodymium Using PC88A.”In the graduate division, Caelen Anderson of the Colorado School of Mines received first place for his research titled “Fundamentals of Rare-earth Flotation Surface Chemistry: Hydroxamate Adsorption on Bastnasite”. This is Caelen’s fourth year placing in the top finisher. Second place in the graduate division went to Seyed Hassan Amini of West Virginia University for his research on “Ultra Clean Coal Production for the Solar-cell Industry.”The 2015 Student Poster Contest was chaired by Lisa Schlink (Freeport- McMoRan Inc.) and Emily Sarver (Virginia Polytechnic Institute and State University). The panel of judges included Aaron Noble (West Virginia University), Nick Gow (FLSmidth), Ren Bryce (Freeport-McMoRan Inc.), David Perkins (Derrick Corp.), Jim Metsa (Weir Minerals) and Scott Shuey (Newmont).A special thank you is extended to the sponsors of the MPD Student Poster Contest, to all the students who participated and to the panel of judges. Watch for more information on the 2016 MPD Student Poster Contest to be published later this year on http://www.smenet.org/mpd/ and in the November issue of Minerals & Metallurgical Processing."

Jan 1, 2015

By Josh Swank

Albert Einstein once said, ?the important thing is not to stop questioning.? In the mining industry, a lack of inquisitiveness may lead to a blissful ignorance but it certainly will not increase efficiencies. While one may claim necessity is the mother of invention, questioning and analyzing how methods and systems can be improved is the catalyst to discovering necessities. Understandably, when working in the middle of Canada?s oil sands, where trucks operate around the clock every day of the year, it is nearly impossible to pull the nose from the grindstone long enough to provide thorough analysis. But, fortunately, some manufacturers/inventors have assisted by examining the process and the ensuing headaches within this application.

Jan 1, 2013

By James D. Reilly

The time-worn adage "an ounce of prevention is worth a pound of cure" was never more applicable than when used in reference to coal mine safety. Many individuals have dedicated many hours to developing effective accident prevention programs, and much has been accomplished. Each production escalation, however, creates new hazards and safety problems which need special study and research. It is a never ending cyle. To study the progress of coal-mine safety is to raise memories of many individuals who have been dedicated to removing the hazards that have developed with increased productivity and deeper penetration into the earth for coal. Some vivid examples of this dedication are the works of the men who pioneered the use of the safety lamp and the use of rock dust in mining.

Jan 1, 1968

By Robert Dunne, John Angove

The physical properties of an ore body require determination for virtually all mining projects, new and existing. The extent and regularity of such determinations being subject to the size and homogeneity of the orebody. Such properties have an impact at the design stage of new plants, with respect to equipment specification, and thus effects capital costs; and also impacts on the operating costs of new and existing plants, with respect to power consumption, production levels and part replacements. All of these can severely alter the bottom line and can be the determining factor in the economic viability of many projects. This paper examines some of the most common properties that are measured, the procedures utilised in determining these properties, and their variability under conditions of reproducibil­ity, and to a lesser extent repeatability. The properties looked at were Impact Crushing Work Index, Abrasion Index, Bond Rod Mill Work Index and Bond Ball Mill Work Index. A number of testing laboratories throughout Australia and the US were utilised in the survey. The results showed up some interesting and important features of the procedures used, all of which have become accepted industry standards, and which had varying effects on the final result. Tests such as the rod and ball mill indices would appear to have reasonably robust procedures which allowed for the determinations of the respective index without the introduction of significant variations, although there were indications that variations could occur. The other tests gave a sufficiently different picture to be able to suggest that an argument could be made for a more intensive investigation to be undertaken, with the possible outcome that a modified test procedure or an alternative test is required.

Jan 1, 1997

By E. A. Domínguez

Kaolin deposits of Patagonia (Argentina) were formed by ?in situ? alteration of volcaniclastic rocks or by erosion, transportation, and deposition of residual clays in small basins. The mineralogy, geochemistry, grain size distribution, and specific surface area of natural and washed kaolins were studied in order to point out the relationships with the ceramic process. Primary kaolins are coarse-grained, kaolinite+quartz±halloysite, with a very low specific surface area. Sedimentary clays are either kaolinitic?smectitic and very fine-grained or kaolinitic with a coarser particle size distribution. An interdependence between mineralogy, chemistry, particle size distribution, texture, surface activity and ceramic behavior was found. Plasticity is strictly dependent on surface activity and expandable clay minerals. Slip rheology is affected by soluble salts, smectite, and tubular halloysite. Kaolinite-halloysite play an opposite role versus smectite-I/S in slip casting and tile pressing. Kaolinite and quartz are beneficial for drying behavior while expandable clay minerals increase drying sensitivity. Firing behaviour is mainly affected by minor components supplying fluxing oxides.

Jan 1, 2010

By Changhong Huang, Y. J. Wang

This paper describes the formulation of mine ventilation network optimization as a standard nonlinear programming problem and the solution of the problem using the generalized reduced gradient (GRG) method. In general, the GRG method is regarded as one of the most effective and efficient methods for solving large-scale nonlinear programming problems. The variables considered in the network optimization include air quantity, regulator pressure loss, and fan pressure for each branch. Each of the variables is constrained by lower and upper bounds. This facilitates proper assignments of ventilation requirements and provides a great flexibility to include various situations encountered in mine ventilation. The objective of the network optimization is to minimize the overall air power consumed by or supplied to the network; whereas the constraints are, in addition to the variable bounds, the two fundamental network laws: Kirchhoffs voltage law and Kirchhoffs current law. A computer program has been developed based on the GRG method for the network optimization. An example of network with 18 branches, 8 regulators and 3 fans is included for illustration.

Jan 1, 1993

By R. Dorey

The Kennecott Ridgeway Mine in South Carolina is scheduled to complete mining and ore processing in the last quarter of 1999. Tailings are disposed in a 300 acre, lined tailings impoundment. To facilitate closure and reclamation, modification of the tailings impoundment operation has been adopted. Mining involved the sequenced development of two open pits. In 1996 mining of the South Pit was completed and backfilling of the pit with waste rock from the North Pit was initiated and will continue until mining ceases. Both pits will be reclaimed as fresh water lakes. This paper presents the physical, geochemical and hydrogeochemical evaluation of the operational and post operational management of the project. Comparison of the operational monitoring data against predicted performance is reviewed.

Jan 1, 1999

By R. K. Singhal

In an underground coal mining environment, a frictional ignition may be defined as the ignition of an explosive air/ methane/coal dust mixture by mining machinery. As the use of power loading equipment has become more widespread, frictional ignition incidents have increased. There have been many fatalities and injuries from this cause including the death of eleven miners in Sydney coalfield of Nova Scotia, Canada in 1979. This paper reports on the findings of a preliminary study carried out under the auspices of the Coal Research Laboratories, Department of Energy, Mines and Resources Canada. The objective of this study has been to identify a Longwall face cutting system that is inherently safer than the conventional shearer loaders used in Nova Scotia.

Jan 1, 1985

By Richard J. Robbins

This paper is presented with particular reference to the findings of the OECD Advisory Conference on tunneling held last July in Washington D. C. A great deal has been said about the Conference in the past few months, but it may be appropriate to review briefly the background and objectives of the Conference to better understand how the mining community can relate its underground excavation problems to the results of the Conference. OBJECTIVES OF THE OECD CONFERENCE The world demand for tunneling (the term tunneling is used here loosely to include almost all forms of underground excavation) is expected to grow at an in- creasing rate. During the decade of the ?70's, the demand is expected to at least double by comparison with the previous decade. Much of this increase in demand will be due to the rapid growth of urbanization around the world. As urban populations grow larger and denser, the conservation of surface land and the quality of the environment become more important. This aspect of the increasing demand poses a difficult challenge to those who must plan and implement urban development.

Jan 1, 1970

By Marcus M. Key

Silicosis among metal miners is an ancient disease, probably as old as mining itself.' However, the primitive forms of mining were not productive of much silica dust, and the short life span of slaves used in mining probably precluded the development of more than a few sporadic cases of silicosis. Early diagnostic terms of miners' asthma and miners' phthisis suggested an occupational relationship and a tubercular component, but little attention was given to silicbsis until the turn of this century when epidemics of silico-tuberculosis arose due to the great expansion of the mining industry in the United States, especially silver and gold mining. The expansion was accompanied by mechanization and the introduction of pneumatic tools, which generated increasing amounts of fine silica dust. Mining communities were crowded and hygiene was poor.' The tubercle bacillus would probably have flourished even without the predisposition of silicosis.' As is so often the case in occupational health, biostatistical analyses first called attention to the problem, and environmental-medical studies later confirmed its existence. The bio-statistical analyses were occupational mortality statistics compiled by the Prudential Life Insurance Company in 1907, showing evidence of excessive mortality from tuberculosis and relationship to dust exposure. I The

Jan 1, 1971

By M. Schreiner, J. Brune, D. Theisen, C. S. -J. Tsai

This study reports that routine mining activities could produce a high number of nanometer sized particles which have not been well characterized and may represent an unacknowledged exposure present in the mining environment. A preliminary survey of the particle emission from the feed-leg drilling activity was conducted in the excavations of an experimental mine. The level of particulate exposure was monitored by real time direct reading instruments include a NanoScan scanning mobility particle sizer (measurement range 10-420 nm) and an optical particle sizer (measurement range 0.3-10 μm). Particulate morphological and structural examination was conducted through transmission and scanning electron microscopy and x-ray dispersive analysis of samples collected by a thermophoretic sampler, and a novel nanoparticle sampler. The real time instrument data revealed high concentrations (> 3.5 x 106 particles/cm3) of ultrafine/nanoparticles generated from the drilling activity. Analysis of particle sampler specimens with energy-dispersive x-ray spectroscopy showed a large amount of submicron silica, spherical primary particles and agglomerated soot particles rich in carbon. Exposure to particles in the nanometer size from various sources within the mining environment may be associated with the poorly understood rise in respiratory and systemic disease among miners. INTRODUCTION Exposures to mine dust have been measured and evaluated for decades. Exposures to aerosolized dust such as coal or silica particles can cause lung and other diseases (1-7). One way that The Mine Safety and Health Administration (MSHA) characterizes inhalation exposures within the mining environment is through measuring the respirable dust mass concentration within the breathing zone of workers (8). Respirable particulate matter (RPM) is of great concern due to its ability to deposit in the alveolar region of the lungs (9-10) where it can affect respiratory function. Interventions championed by MSHA have greatly reduced the prevalence of coal workers pneumoconiosis (CWP) and progressive massive fibrosis (PMF). Although great progress has been made, the prevalence of CWP and PMF appears to be trending upwards and the measured increase in prevalence is not elucidated in RPM measurements (11-12). Though the presence and risk associated with ultrafine particles such as emission from diesel engine within the mining environment has been previously established (13-14). There is suspicion within the mining industry that this resurgence of lung disease may be due to very fine particulate matter from various source that is not properly characterized by current sampling methods. Nanometer sized particles, in the range of ultrafine particles, fall within the RPM size range and have been found to deposit in all regions of the respiratory tract (15). Nanoparticles are commonly accepted as particles that are greater than 1 nm in two or three dimensions but smaller than 100 nm (16). Once in the lungs, nanoparticles can enter the blood stream (17) and selectively affect other target organs such as the heart, liver, bone marrow, lymph nodes, spleen, and brain (15,18-19). The size of nanoparticles has been shown to correlate with their translocation behavior on secondary target organs (20-21). There is strong evidence that the clearance mechanisms used to rid the lungs of particulate matter are not as effective on nanometer sized particles, leading to a greater fraction of never-cleared particles which may enhance disease development (20). Research has demonstrated that nanometer sized particles have unique properties (22) whose adverse health impact is greater than what has been found with micrometer sized particles of the same type (23-26). The large ratio of surface area to mass compared to larger particles is believed to make nanoparticles a greater hazard. Utilizing mass to measure these types of exposure will be very difficult to accurately characterize the quantity of

Jan 1, 2019

By C. Clark, R. Pakalnis, B. Seymour, L. Martin, R. Jacksha, M. Stepan, M. Roworth, C. Caceres

The National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop safe practices for the use of shotcrete as ground support in underground mines, particularly mines operating in weak host rock. As part of this research, a rugged, portable direct tensile test system was developed for measuring shotcrete adhesion strength in underground mines. During the development of this test system, more than 185 direct tensile tests were conducted with a common, commercially available macro-synthetic fiber-reinforced shotcrete that was applied to concrete test panels using a dry mix process and machinery. The average bond strength of the shotcrete to the concrete substrate typically increased as a function of the shotcrete’s curing age, ranging from 0.44 MPa (64 psi) after one day of curing to 1.58 MPa (229 psi) after 90 days of curing. Adhesion strength increased markedly between one and three days of curing, reflecting a similar trend of increasing shotcrete tensile strength with curing time. This robust direct tensile test system can improve mine safety by providing a reliable means of measuring shotcrete adhesion strength and also supplying important information about the quality of the applied shotcrete and the competency of the underlying rock.

Jan 1, 2010

By Ben E. Adams

The Duval Corporation Sierrita copper and molybdenum mining complex is located approximately twenty-three miles south of Tucson, Arizona. The original open pit mine, Esperanza, was put into operation in 1958 and utilized one tailings dam until the Sierrita operation began in 1970, and a second pond was started. Both tailings operations continued to be operated separate and independently of each other until 1977, when the Esperanza Mill was temporarily shut down, and the Esperanza Tailings Dam was retired from service. Except for short periods of use, no new tailings were put on the surface. With the reactivation of the Esperanza Mill in 1979, the Esperanza tailings were combined with the Sierrita Mill tailings and put on the Sierrita Dam, leaving the Esperanza Dam in a retired state.

Jan 1, 1984

By S. Fernández, L. Klinger, T. Vallejo

In the municipality of Rio Quito, department of Chocó, Colombia, alluvial gold has been illegally exploited by suction dredging. The project consists of using geospatial techniques to identify degraded areas and analyze the viability of remediation dredging to mitigate environmental liabilities. The area has sediments contaminated by mercury and cyanide, so it is necessary to reconform the riverbed with the remediated material. The work is part of the Mine Closure Plan that seeks to jointly articulate the communities, academia, the company, and the state

Mar 2, 2022

By Gregory A. Hahn

Explorationists and engineers rarely speak the same language. Explorationists are not cognizant of the information that engineers require to make the appropriate choices and decisions. Engineers can- not "translate"geo1ogic parlance and data into information relevant to proper decision making. This often creates a physical and intellectual "rift" between engineers and geologists that inhibits a smooth transition to development. A transition team leader who is grounded in both disciplines can best facilitate integration and communications between the explorationists, who understand the intrinsic attributes of a given deposit, and the engineers, who have to design for extraction and beneficiation of an orebody.

Jan 1, 2001