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"Foreword by Emily SarverAssistant professor, Mining and Minerals Engineering, Virginia Tech, Blacksburg, VAThe Mineral Processing Division hosted its fifth Student Poster Contest during the 2014 SME Annual Meeting and Exhibit in Salt Lake City, UT – and, by all accounts, it was a huge success! This year, the contest more than doubled in numbers of individual entries and schools represented. A total of 30 students participated, including 23 graduates and 7 undergraduates, representing 13 US and international institutions: Colorado School of Mines, Michigan Tech, Missouri University of Science and Technology, Montana Tech, New Mexico Tech, South Dakota School of Mines, University of Kentucky, University of Utah, Virginia Tech, West Virginia University, Autonomous University of Chihuahua (Mexico), UNAL Medellin (Colombia), University of British Columbia (Canada). In addition to constructing their posters, students submitted abstracts and gave short oral presentations highlighting their research. Based on tallied scores from all three components of the contest, the judging panel selected 1st, 2nd and 3rd place winners at the undergraduate and graduate levels, which were announced during the MPD Luncheon on February 26.In the undergraduate division, University of Utah’s Lucas Pich was awarded the 1st place prize for his poster “Solid-liquid mixing studies in lab-scale flotation tank using electrical resistance tomography.” His extended abstract is included in this issue of Minerals & Metallurgical Processing. Joshua Chidester, also of Utah, won 2nd place for his poster presenting “Evaluation of detectors for radiotracer RTD measurement by MCNP.” And Lucas Rojas-Mendoza, of UNAL Medellin, took 3rd place for his poster on “Preg-robbing in Colombian gold ores.”In the graduate division, 1st place went to Caelen Anderson, of the Colorado School of Mines, who also placed in this contest in 2012 and 2013! The 2nd and 3rd place prizes were awarded to Jacob McDonald and Joseph Halt, respectively, both of Michigan Tech. Extended abstracts describing the work of these up-and-coming researchers are also included in this issue.The 2014 Contest was chaired by Emily Sarver (Virginia Tech) and Lisa Schlink (Freeport-McMoran Copper and Gold, Inc.). Aaron Noble (West Virginia University), David Perkins (Derrick Corporation) and Derek Novotny (Eriez) graciously served on the judging panel this year.Special thanks are extended to all sponsors of the 2014 MPD Student Poster Contest, and to all student participants. Please watch for upcoming details on the 2015 Contest. We look forward to seeing you in Denver!"

Jan 1, 2015

Sequential and evolutionary changes through time are recognizable in many, perhaps most major families of ore deposits and their geological environments. These changes are additional useful indicators of the evolutionary history of the earth and its tectonic processes. They are important in mineral exploration because they involve consideration of time as a fourth dimension, thereby indicating the most favorable ages, rather than types of rock for investigation. Many of the changes are analogous to those recognized in faunal evolution. Some primitive, unspecialized types of ore deposits occur nearly unchanged through rocks of widely differing age. Others diversify into several, more specialized variants, whereas still others become extinct. The place of these is taken by new, younger types, some of which undergo sudden proliferations and later diversifications of their own. In Archean greenstone belts irrlportant iron, nickel, gold, and base metal deposits occur co-regionally, but in different stratigraphic positions in the same, thick volcano-sedimentary successions. Here their close temporal and spatial associations suggest common genetic exhalative hydrothermal processes. The massive base metal sulfide family of ore deposits provides an excellent example of evolutionary changes, exhibiting distinct variations through both time and space. Deposits belonging to this family span the entire range of time, occurring in rocks of ancient Archean to Recent age, and specific types within the family also span the entire range of spatial environments from ensimatic to ensialic. Moreover there are possible evolutionary metallogenic links between certain types of massive base metal sulfide deposits and other important base metal ores, noteably Mississippi Valley-type and porphyry copper deposits.

Jan 1, 2013

By B. G. White

Traditional interpretations of vein ore deposits in the Coeur d' Alene Mining District, such as the view that these deposits formed in a transcurrent tectonic regime during the Precambrian, are being supplanted by the view that the deposits (1) formed in low-grade metamorphic shear zones similar to those that host an important type of gold deposit, (2) display features, such as wall rock carbonate zoning and vein zoning, that are common to ore deposits elsewhere, and (3) are probably Mesozoic and possibly related to emplacement of the Idaho batholith. In recent years, new interpretations have led to major ore discoveries that are likely to extend the life of the district for decades.

Jan 1, 1998

Clean Diesels fuel-borne catalyst, Platinum Plus, helps improve fuel economy for all engines up to 10 percent while reducing particulate emissions by up to 25 percent. When used with a simple diesel oxidation catalyst, particulate emissions can be reduced by 30 to 50 percent. The use of Platinum Plus enhances combustion in the cylinder, burning fuel more completely. This reduces CO2 and other greenhouse gases and lowers total operating costs by improving fuel economy.

Jan 1, 2007

By D. J. Pandelis, W. J. Schlittler

Auxiliary Equipment pumping systems to support primary, secondary and regrind grinding circuits will be the primary focus of this paper. Every grinding system is unique and requires special design considerations for proper application of pumps to transport mill discharge. To satisfy the majority of applications, a new series of pumps has been developed by Svedala, known as World Class Pumps. Selection of these newly developed pumps for each type of grinding circuit will be presented. Specific components of selection are materials of construction, piping system, classification method, material characteristics and slurry characteristics. Both horizontal and vertical pump applications will be reviewed with emphasis on rules of pump piping and sump design.

Jan 1, 1999

By Paul B. Valenti

The Nevada Moly Operation of Anaconda Minerals Co., (a molybdenum/copper ore body) was initiated in 1978, with a contract to Bechtel Civil and Minerals Inc. for construction of a mining and milling facility near Tonopah, NV. Ground was broken on the concentrator portion of the project in August 1979$ with a multi-phased startup of the mill beginning in June 1981. Processing design tonnage of 20 000 t/d (22,000 STPD) was reached in early 1982. Major pitfalls of rapid design and implementation of engineering, construction, and startup are considered. The operation of the concentrator including SAG milling, ball milling, bulk rougher flotation, copper/moly separation, moly regrinding and cleaning, thickening, and product loadout are discussed.

Jan 1, 1983

By R. Venugopal, V. K. Saxena, S. K. Tripathy

"This study was carried out to understand the impact of variation in material morphology on the efficacy of microwave pretreatment. Three different types of mineral matter – coal, iron ore and manganese ore – were treated with microwaves at different energy levels, from 180 to 900 W, for different time durations of one to five minutes. The treated samples were subjected to microscopic, milling and liberation studies. Coal is a porous and amorphous material with low dielectric constant, and grinding of the microwave-pretreated coal samples resulted in an 18.18 percent reduction in the 80 percent of passing particle size, or d80, and a 17.1 percent increase in carbon recovery. The microwave-pretreated soft and friable manganese ore samples showed a 47.82 percent reduction in d80 during grinding and higher manganese recovery of 42.46 percent during liberation analysis. The microwave pretreatment and milling of hard and banded iron ore reduced the d80 by 20.83 percent, but no improvement was observed in mineral liberation. Coal showed better results during treatment at lower energy levels of 180 W for one to three minutes, whereas the minerals needed higher energy of 900 W for five minutes. Particle size analysis indicated rapid size reduction up to an energy input of 25 Wh. This effect diminished with increased energy input.IntroductionComminution is an important unit operation in mineral processing plants for the purposes of size reduction and mineral liberation. But most comminution technologies are energy inefficient and only a small amount of energy is consumed in real size reduction, with the rest wasted. High-grade mineral resources have been exploited on a large scale for the last century, and the upgrading of low-grade resources is now required to fulfill the needs of industry. Pretreatment methodologies for comminution will play a crucial role in the upgrading of low-grade mineral resources. Researchers have studied various pretreatment methods to develop an energy-efficient and techno-economically viable solution to improve mineral liberation and product fineness with minimum energy consumption. Most of these studies were focused on the use of chemical additives, thermal, ultrasonic and microwave treatment, and electric disintegration (Klimpel and Austin, 1982; Norgate and Weller, 1994; Gaete-Garreton, Vargas-Hermandez and Velasquez-Lambert, 2000; Wilson et al., 2006; Kumar et al., 2010; Wang, Shi and Manlapig, 2011; Singh et al., 2012)."

Jan 1, 2017

By Donivan L. Gordon

One of the several problems facing society today is that of disposing of its solid waste. Each year this nation spends approximately 4.5 billion dollars to collect, transport and dispose of some 360 million tons of domestic and industrial solid waste. Although considerable sums of time and money have been spent in researching various techniques for solid waste disposal, it is presently agreed that sanitary landfilling represents the most economic and universally adaptable solution to the problem of solid waste disposal. However, regardless of the factors favoring sanitary landfilling as the waste disposal method of choice, it should be recognized as carrying with it a potential for the degradation of ground- and surfacewater resources. Through an interdisciplinary effort regulations were promulgated during 1971 in the State of Iowa to govern sanitary disposal projects. Consistent with a set of rationales developed to preserve environmental quality, these regulations set forth hydrologic and geologic standards designed to protect Iowa's water resources. Minimum requirements have been outlined in the regulations through which the natural favorability of potential landfill sites may be evaluated. Natural favorability is primarily defined in terms of the hydrologic and geologic relationships between a proposed landfill site and those in the locality of the site. The regulations specify that leakage from a landfill to a subcropping aquifer must be less than 0.04 cu ft/day/sq ft at the base of the landfill. This factor is offered to quantify the maximum allowable leakage for all sites in unconsolidated sequences underlain by subcropping bedrock aquifers, Based on groundwater research in Iowa, the assumption is made that 50 feet of till will be sufficient to inhibit the downward flow of liquids from a landfill into bedrock aquifers. This assumes a difference of no greater than 40 feet in hydrostatic head between the water table in the unconsolidated sequence and that in the bedrock aquifer. Owing to the fact that bedrock aquifers in many areas of the state are mantled by less than 50 feet of till the regulations provide for site modification, through engineering, to meet the specified leakage standard, In such instances the leakage factor is evaluated by means of the generalized Darcy's Law Q = PIA where:

Jan 1, 1974

By D. Meadows, P. Carrato, E. Wingate, K. Churchill

Extracting lunar ice, to be processed into pure water or hydrolyzed into oxygen and hydrogen, faces many challenges. On the Moon icy-regolith deposits that contain up to 10% water are found within Permanently Shadowed Regions (PSR) at both lunar poles, where temperatures approach -220 ⁰C. NASA has identified several technology gaps that exist in developing these resources including: • Excavating large quantities of icy-regolith • Delivering large quantities of acquired resources • Hardware that is lightweight and energy efficient • Hardware that is reliable and durable. NASA uses public challenges to incentivize innovative approaches to closing these gaps. The Break the Ice Lunar Challenge provides over three million dollars in prize money to teams that compete in developing solution to mining the Moon. This paper describes the rules for this challenge and presents some of the proposed solution.

Feb 1, 2023

By M. E. Smith

Waste rock dumps, tailings impoundments and spent leach heaps are common features at mine sites. Many of these waste disposal facilities contain sulfide-rich minerals, which generate acid mine drainage (AMD) when they oxidize. Control of AMD can be achieved by removing one or more of the three essential components in the acid-generating process (sulfides, air, or water). One AMD prevention measure is to cap the waste with an engineered cover system to minimize the infiltration of water and diffusion of air into the system. Possible cover designs include: ? Earthen ?store-and-release? covers (also known as evapotranspiration (ET) or water balance covers), including capillary barriers. These covers require climate conditions where there is both modest to little rainfall and significantly greater evapotranspiration than precipitation, both annually and seasonally. ? Low-permeability compacted clay liners (CCLs) employing fine-grained soils typically compacted at wet of optimum water content. ? Geosynthetic composite covers, comprised of a geomembrane liner placed over and in direct contact with either a CCL or a geosynthetic clay liner (GCL). These systems have been commonly used for base liners for leach pads as well as covers and base liners at municipal solid waste (MSW) landfills in the US for more than 20 years. Comparisons of these different cover systems, both in terms of performance and cost, are presented later in this paper. First, however, a review of the typical mine closure approaches, and the possible rationale behind them, is warranted.

Feb 27, 2013

By P. Tong-jiang

We studied mineralogical characteristics of the vermiculite samples from seven mines in China. We found three types of interstratified structures in the investigated samples: 1:1 regular interstratified structure, segregated interstratified structure, and random interstratified structure. The vermiculite samples from six mines are mainly composed of phlogopite?vermiculite interstratified minerals, and the samples from the other mine are composed of chlorite?vermiculite interstratified mineral. The samples with phlogopite?vermiculite structure have high contents of K2O, TiO2 and Na2O. The samples with chlorite?vermiculite structure have the highest contents of MgO and Al2O3. The cation exchange capacity of the samples is 17.3?99.0 mmol/100g.The exchangeable cations of phlogopite?vermiculite samples from Weili Mine mainly include Na+ and Ca2+, while those of phlogopite?vermiculite samples from Tongguan Mine mainly include Mg2+ and Ca2+. The thermal expansion ratio of the samples is between 9 and 32. The exfoliated vermiculite products from Weili Mine have the best mechanical strength.

Feb 27, 2013

By Bauer, Steve, Colin Goodwin, Gerald, Randy Dempsey, Courtland

"The City of Ottawa’s Combined Sewage Storage Tunnel consists of two interconnected tunnels totaling 6.2 km with a diameter of 3m including access shafts and hydraulic structures which connect to the City’s most critical sewers. This tunnel will be built 15m to 30m below ground in the downtown core adjacent to, and crossing below, the Light Rail Tunnel, which introduces additional considerations in terms of sequencing and risk mitigation. The City embarked on a unique Procurement Process to address the risks involved with a large tunnel project and those associated with tunneling below downtown, underneath and adjacent to UNESCO World Heritage Sites, and connecting to live critical sewers. This paper describes the unique procurement approach employed and the contractual risk mitigation measures developed to provide the best value while minimizing risk. Specific features include Market Sounding, using a Fairness Commissioner, Contractor Prequalification and Risk Mitigation Measures in the Tender documents. INTRODUCTION This paper describes how the City of Ottawa (the City) and the project design team developed a strategic Procurement Process and Tender that incorporated industry best practices for technical and contractual risk management for the Combined Sewage Storage Tunnel (CSST) project. The process was unique in that, while it employed a systematic review of project risks, it also solicited input from industry, stakeholders and provincial and federal partners to develop the request for Tender for this traditional design-bid-build project. Key drivers for this approach were initiated from the City’s concerns for cost control, cost certainty and overall project risk mitigation. To address these concerns, the City implemented the risk review and mitigation process right from the project design team selection. It was critical that the project design team embraced this risk management philosophy and carried it through each phase of the project. This paper serves as an excellent resource for municipalities or other owners embarking on a similar tunnel project, on how to properly apply industry best practices and the benefits of using them."

Jan 1, 2016

By C. Okrusch, C. Roos, M. Akers, S. Rosenthal

Modern mining consistently faces controversy. Public sentiment impacts the permitting and development of mines, so a quality public relations (PR) program for mining companies may improve society’s impression of the mining industry. Developing mines face more permitting challenges than operating mines, which stems from a lack of societal trust given the history of mining and its impact on the environment. Two case studies were selected based on the type of public controversy they face to demonstrate how pervasive permitting issues are in industry. Both Pebble Mine, owned by Northern Dynasty Minerals (NDM), and Black Butte, owned by Sandfire Resources America Inc (SRA), experienced difficulties with their water permitting due to potential risks their mine developments posed to local fish populations. Pebble has, to date, failed in all of their attempts to become permitted due to concern for the water and the fish. Black Butte dealt with the same problems, on a smaller scale, but was able to become permitted. These two mines will be discussed in detail including local history, mine setting, mining history in America, prevalent culture groups, technology development, and intercultural communication competence (ICC). The mining industry needs to evaluate its ICC skills since ICC directly determines the effectiveness of PR. Based on Barna’s Stumbling Blocks for intercultural communication, methods for improving the mining industry’s PR will be suggested in the hope of easing the permitting process for future mines by developing ICC.

Mar 2, 2022

By Peter Shuttleworth, Chris Fesq, Eddie Woods

Precast concrete segmental linings for tunnels have traditionally been designed with conventional steel bar reinforcement. In many cases, this has been satisfactory in service, but in others, major problems have occurred with the durability of the linings. Commonly this has resulted from corrosion of the reinforcement, mainly from chloridesin ground water, causing spalling of the concrete and leading to very expensive and disruptive repair programs. This paper discusses the relative merits of designing tunnel linings with steel fiber reinforcement to provide long-term durability, improved impact resistance and toughness for greater load capacity across joints, enhanced robustness during transportation and erection, plus improved fire resistance with the addition of polypropylene fibers. Guidance is also given in the selection of the correct fiber type, mix design and testing methods to establish the optimum dosage required and production techniques to ensure even distribution and compaction.

Jan 1, 2005

By Chris Lynagh, Collin Schroeder

Determining the best excavation method is a critical step in successful tunnel construction. In rock tunneling, several factors can dictate the excavation method, such as: (1) rock characteristics, (2) tunnel size and length, (3) nearby utilities/infrastructure, and (4) contractor’s preferred means and methods. This paper discusses the various rock tunnel excavation methods utilized on the Doan Valley Storage Tunnel Project (DVT), a project constructed as part of the broader Project Clean Lake in Cleveland, Ohio. The differences between each method’s initial and final lining, geology, and cycle sequence will be analyzed and compared.

Jun 13, 2023

By J. R. Kunkel, V. Lishnevsky

At mine sites, the operational and required storage volumes of solution and water storage ponds and reservoirs are usually calculated based upon a water-balance approach. Many climatological variables including precipitation, air temperature, solar radiation, pan evaporation and relative humidity along with operating parameters, are used in the water-balance model. The water-balance model often seeks to find a “critical period” of wet or dry climatological sequences which result in a “maximum” pond storage volume or water demand. The problem with this approach is that the designer usually does not know when the project will come on line in relation to the historical record. To avoid this pitfall, we use a more robust approach. In the more robust method, the water-balance calculations begin in each year of the historic climatological record. This method results in the same number of water-balance runs (or realizations) as the number of years of climatological record. Results of this type of analysis guarantee that the critical period or maximum required pond volume will be found if it is assumed that the historical climatological record repeats itself or if a synthetic time series is used. In addition, this method permits calculation of the likelihood (probability) that a given pond volume will be equaled or exceeded in any given month of the operational life of the facility. In this paper, the results of the sizing of a heap leach pad solution pond are presented along with the probabilities of a given solution pond size being equaled or exceeded based on the robust water-balance approach.

Jan 1, 2002

By S. Hadley, M. Placha, M. Mishra, V. Choudhry

Under a DOE-funded project, four advanced flotation technologies (the Jameson cell, the Outokumpu HG Tank Cell, an open column and a packed column) were evaluated at the benchscale to identify the technology or combination of technologies that best improved fine coal recovery and reduced processing costs. The results indicated that two-stage application of the Jameson and packed column cells provided the optimal performance. Subsequently, proof-of-concept scale testing was conducted at the Cyprus Emerald Coal Preparation Plant. The results confirmed that levelized production costs were lower using two-stage cleaning with the Jameson cell followed by the packed column.

Jan 1, 1999

By F. Warnaars

Historically, this area produced gold and silver from many well-known vein deposits, like Tayoltita, Topia, and San Jose de Gracia. Modern exploration identified three categories of deposits: 1) low grade porphyry golds in shallow level dacite porphyries; 2) batholith-related deposits; and 3) those formed in volcanic sequences of Late Cretaceous to Late Tertiary. At least four porphyry golds have been identified, of which Metates is best known. These are formed by and within daciteporphyries, associated hydrothermal breccias and sometimes within surrounding meta sediments. Their ages are from mid-Cretaceous to Early Tertiary. Precious metal deposits associated with batholiths occur as veins, contact haloes in meta sediments or volcanics, skarns, tectonic breccias, hydrothermal tourmaline breccias, dacite dikes or as disseminated or stockwork deposits such as La Fortuna.Several new gold discoveries were made in older EarlyTertiary Volcanic Sequences and in the younger Tertiary volcanics within prominent structures exceeding 3 to 5 km in lengths. Some of these are open-pittable but most have to be mined by underground methods.

Jan 1, 1999

By Syd S. Peng

Is the laboratory sized coal specimen much stronger than underground coal pillars? The answer to this question has a profound implication to many coal operators. It will decide how much of the coal reserve can be recovered. Or, in many cases, it will determine whether it can be mined economically. Recent trends in several eastern states to establish regulations regarding coal pillar design to prevent surface subsidence long after mining heighten the debates. And, in some cases, these trends highlight the existing practices that seriously question the conventional wisdom. Currently, nearly all researchers and practitioners agree that as the size of rock specimens increases, its strength decreases. This concept has been universally adopted as the basic principle for coal pillar design in the United States. Several formulas have been derived to account for this effect. The reduction factor for underground coal pillars ranges from one-half to one-sixth of the strength obtained in the laboratory, depending on the formula selected. Recent case studies indicate that the reduction factor is not justifiable, at east in some cases. The use of a reduction factor is based on the assumption hat smaller rock specimens as tested in he laboratory contain none or fewer fractures or planes of weakness than larger specimens or underground coal pillars. In other words, the larger the rock materials, the more fractures it contains and subsequently weaker in strength. Do all underground coal pillars have more fractures than laboratory sized coal specimens? Not necessarily. All coal contains cleats. Some are con¬spicuous but others are not. In terms of cleat density (number of cleats per unit area), there is no difference between an underground coal pillar and a laboratory sized specimen, provided the specimen size is larger than the cleat spacing, which is mostly 25 to 75 mm (1 to 3 in.).

Jan 1, 1993

By R. D. Lawrence

Suggestions have been made that the appraisal of mining assets using discounted cash flow techniques should be based solely on proven and probable reserves in reliance upon the widespread international recognition of uniform resource definitions. Following a review of general accepted valuation principles, a survey of the literature and, most importantly, a review of real transactions in the open market, it is clear that valuators should not be constrained by the growing acceptance of modern mineral resource codes. On the contrary, valuation practitioners should be encouraged to examine all classes of mineralization and, after making due allowance for risk, to utilize all mineral resources as a basis for determining fair market value.

Jan 1, 2000