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By K. Awuah-Offei

An aggregate plant may have difficulty balancing product stockpile inventories if hot mix asphalt (HMA) design engineers do not account for aggregate inventory during mix design. Yet HMA design engineers do not, often, take this into consideration during asphalt mix design. This is due to the lack of tools that enable the lab technician or engineer to optimize the mix for good performance while helping the aggregate plant manage its stockpile inventory levels and reducing the aggregate cost. This work presents a linear programming model of the asphalt mix design problem that helps aggregate plants manage their inventory levels while meeting HMA customer demands. The algorithm is implemented in MATLAB as an Asphalt Mix Design Optimization (AMIDO) program. The program is successfully validated with real-life data. The results show that AMIDO can be used to successfully produce any mix design while reducing the cost of aggregates by using the cheapest stockpile materials. The application of AMIDO will increase aggregate plant profitability when serving HMA customers and could potentially be modified for concrete aggregate customers too.

Jan 1, 2009

By Jean Habimana

The Detroit Upper Rouge Tunnel CSO Control Project will capture and store up to 201 MG of combined sewer overflow from 28 outfalls in Detroit, Dearborn Heights and Redford Township during wet-weather events. The history of rock tunneling in the area is associated with high groundwater inflows, artesian pressure, and hazardous and combustible gases. This paper presents the geotechnical considerations for designing the 11.28-km (7-mile) long, 9.14 m (30-ft) finished diameter tunnel and its associated adits, chambers and shafts, including the discussions of geotechnical investigations, rock mass characterization, estimated groundwater infiltration during construction, and the selections of excavation methods and lining system based on anticipated ground behavior to be encountered.

Jan 1, 2008

Simulator technology has advanced to the point where the cost of mining equipment simulators is beginning to make commercial sense. Simulator-based evaluation allows operators or potential employees to be assessed in a pseudo-real environment under surface and underground mining conditions. Simulator training also allows operators to be exposed to emergency and advanced situations such as brake or steering failure or a tireblowout. ThoroughTec, of South Africa, provides simulator equipment to the mining industry. The company’s various packages of simulator products provide an unbiased evaluation score that removes human error from the assessment process. This same evaluation score is also presented at the end of normal training or refresher training sessions. In this way, the simulator helps eliminate bad habits and improve efficiencies.

Jan 1, 2003

Many investigators measured surface forces between hydrophobic macroscopic surfaces using atomic force microscope (AFM). Some investigators observed long-range attractions and attributed them to the presence of hydrophobic forces, while others suggested that they are artifacts of the nano-bubbles and cavities associated with the hydrophobic surfaces. Still others suggested that the long-range attractions are due to the electrostatic interactions between charged patches present on opposing surfaces and hence are unrelated to surface hydrophobicity. In the present work, we have measured long-range attractions between gold- (or silver-) coated surfaces hydrophobized in potassium ethyl xanthate (KEX) solutions at pH 9.2 under controlled potential conditions. The results of our AFM force measurements are consistent with those of the contact angle and voltammetry experiments, indicating that the long-range attractions are hydrophobic forces.

Jan 1, 2012

By A. M. Tonnos

Underground mining has yet to see an industry wide solution for control of their ventilation systems due to the complexity and sensitivity of the underground environment. Complexity arises from multi-level, multi-zone operations and sensitivity is associated with the impact that changes in equipment status and output have on air flows and quality throughout the mine. Our approach to solving this challenge incorporates system modeling and industrial control systems in a unified architecture. Although this approach can be applied to other processes and industries, this paper will cover the theoretical and practical aspects of an integrated model-control system (MCS) as it applies to underground mining ventilation.

Jan 1, 2009

By M. Moats

Copper electrowinning operations have dramatically improved their ability to produce high quality copper at low costs over the past several decades. Even so, some fundamental understandings are still lacking, which could allow operates to run more efficiently. For example, a rule of thumb exists that estimates a current efficiency loss of 2-3% per gram per liter of iron in the electrolyte. While several laboratory studies have been performed that demonstrate this rule of thumb is likely true, no definitive relationship exists. In this paper, the first steps in developing a definitive relationship are presented. The effective diffusivity of ferric ions in synthetic copper electrowinning solutions was measured using chronoamperometry and the Cottrell equation. The effective diffusivity of ferric ion was determined as a function of electrolyte concentration and temperature. Synthetic electrolytes were then used in laboratory scaled copper electrowinning experiments where relationships were found under stagnant conditions between current efficiency and solution composition.

Jan 1, 2009

By Don Reining

The sand and gravel industry in Southern California has made a sizeable contribution to the construction development of the 15 County area in this part of the State. Facing this mineral extraction industry, in the next decade, is a problem of meeting the market demand. The question is, "how can sand, gravel and rock operations be made compatible with goals for sound and attractive community development?" Three basic principal characteristics of the land needed for this-mining industry are: 1. The land must have workable sand, gravel or stone deposits. 2. The land must be properly located for transportation purposes close to the market in order to sell the aggregate at a minimum cost. 3. The land must be zoned so that it will be permissible to mine.

Jan 1, 1967

By C. Guria

A modeling, simulation and optimization study of a complex industrial fluorspar beneficiation plant (Kadipani, Gujarat, India) with fourteen/ten flotation banks is carried out to find an optimum/near-optimum circuit for the given quality of feed ore. The phenomenological flotation model developed by Mehrotra and Kapur (1974) is used for circuit optimization. Two different optimization problems are formulated and solved. The first optimization problem involves a single objective function, which uses available plant data to estimate the feed-characterizing parameters, i.e., the flotation rate constants, by minimizing the weighted sum-of-square errors between the computed and plant values. The second optimization problem involves two objective functions to obtain several simplified circuits. The number of non-linking streams and the overall recovery of the concentrate, i.e., the acid-grade product, are maximized simultaneously in this problem. The single-objective variant (SGA-II-mJG) of the binary-coded elitist non-dominated sorting genetic algorithm with the jumping gene adaptation, NSGA-II-mJG, is used for the first problem, while NAGA-II-mJG (Guria et al., 2005 a) is used for the second problem. Simplified circuits with a few split streams are proposed on the basis of the present optimization study, which enhance the recovery of the acid-grade product without affecting its quality, for a given total volume of the flotation cell-bank. Even though the optimal solutions have certain drawbacks, they suggest a meaningful direction in using an iterative fitting of parameters to such optimal circuits, followed by re-optimization. Key words: Froth flotation, Mineral processing, Industrial fluorspar beneficiation, Feed identification, Circuit/network optimization, Global optimal, Jumping gene, Genetic algorithm, Multi-objective optimization

Jan 1, 2009

This geometallurgical study examines the gangue mineral variability at the Bingham Canyon porphyry copper mine in Utah. Understanding an orebody?s mineralogy is important for mine and mill planning because it provides information on the size, texture, and distribution of ore minerals, the relationship between ore and gangue minerals, and the extent and type of alteration. Quantification of the mineralogical variability and properties of an orebody provides valuable input to the ore model and may have a significant effect on recovery optimization. This study was designed to be carried out on an initially detailed scale in order to develop a robust methodology for measuring and quantifying specific parameters, such as the distribution of mineral phases, alteration assemblages and fractures from key ore domains at the Bingham Canyon mine (Figure 1). Details of the methodology are reported below. This technique can be applied to testing the impact of mineralogy on a number of processing parameters. [ ] Figure 1. Ore domain map of Bingham Canyon (Kennecott Utah Copper, 2003) showing the 33 geometallurgical ore domains. The samples for this study were collected from the northwest part of the deposit circled on the map. PROJECT BACKGROUND Geology The Bingham Canyon deposit is a large porphyry Cu-Mo-Au deposit with associated skarn and base-metal replacement deposits mined in an open-pit mine measuring about 2.5 miles across and 4,000 feet deep. The deposit is hosted by the Bingham Stock, a Late Eocene to Mid-Oligocene intrusive complex. The skarn is hosted by the Late Carboniferous-age Bingham Mine Formation, which is comprised of quartzites and basal limestones (Babcock Jr. et al., 1998). The Bingham Stock is a composite intrusive complex that was emplaced over a period of about two million years. The oldest phase is described as a fine-grained equigranular monzonite (MZ), which intruded the country rocks at 39.8 ± 0.4 Ma (U-Pb zircon TIMS age) (Parry et al., 2001). Subsequently, the quartz monzonite porphyry (QMP) was emplaced, followed by intrusion of a latite porphyry (LP). The final intrusive phase, which forms narrow dikes that crosscut the Bingham Stock, is represented by a quartz latite porphyry (QLP), which is dated to 37.5 ± 0.4 Ma by 40Ar/39Ar dating of sanidine (Deino and Keith, 1998). Also present, are a minette dike in contact with a QLP dike (Waite et al., 1998; Deino and Keith, 1998), and a biotite porphyry (BP), a quartz latite porphyry breccia (QLPbx), and a pebble dike (Redmond, 2002). The copper orebody is centered above the Bingham Stock and forms an inverted cup shape with three high-grade copper zones extending to depth. Molybdenite mineralization occurs within and extends below the copper orebody, but is not correlated with copper mineralization. The main sulfide assemblage is chalcopyrite, bornite, molybdenite, and pyrite. Gold is locally intergrown with chalcopyrite and bornite (Babcock Jr. et al., 1998; Phillips et al., 1998). The surrounding country rocks host skarn deposits with three main ore types - garnet skarns, massive sulfides, and iron oxides. The garnet skarns contain chalcopyrite and pyrite with magnetite veins. In the massive sulfides chalcopyrite and pyrite occur either in banded sulfides or in unconsolidated microbreccias. The iron oxides contain disseminated chalcopyrite with minor chalcocite and bornite (Harrison and Reid, 1998). The deposit is overprinted by several stages of alteration. Potassic alteration is concentrated at the center of the deposit. It is surrounded and partially overlapped by a propylitic alteration zone. Both zones are overprinted by sericitic alteration. In the northern part of the deposit evidence for argillic alteration can be found (Bowman et al., 1987). Similarly, the skarn deposit was also overprinted by several stages of alteration: wollastonite, idocrase, and garnet in cherty limestones, and quartz and diopside forming in calcareous quartzites. Distally, diopside was replaced by talc, tremolite, dolomite, secondary calcite, and pyrite, and quartz and sulfide veinlets with biotite and actinolite selvages are present. Andradite garnet, diopside, quartz, magnetite, hematite, and copper sulfides were overprinted by wollastonite (Babcock Jr. et al., 1998). Because the monzonite, quartz monzonite porphyry, latite porphyry, and quartz latite porphyry host the bulk of the mineralization, our research is focused on these lithologic units. Geometallurgy On the basis of geological (lithology, alteration assemblages, fracture density, copper mineralization) and metallurgical properties, the deposit has been divided into 33 ore domains by mine geologists and metallurgists (Figure 1). In map view, these domains cross geologically defined boundaries (MZ, QMP etc.). These domains reflect regions of the deposit that have particular, mapable attributes or properties. They reflect a combination of geological and mineralogical characteristics that combine to impact processing. Alteration, for example, as shown by talc mineralization, is one such key feature. Hardness may reflect the absence of sericitic but presence of potassic alteration. Structural discontinuities such as faulting, fracturing, or development of void

Jan 1, 2009

By W. K. Hitchcock

Hydrogen is regarded as being a high temperature indicator of spontaneous combustion. It is currently used in underground coal mines to detect advanced heating?s. Previous work has mostly consisted of small scale tests with high air flow to mass ratios. A large-scale test rig has been used to investigate the gas indicators of coal self-heating. In particular, the relationship of gas evolution, the location of its evolution and the temperature at which it is evolved has been examined. It has been found that there are two distinct zones of hydrogen production: one at the hot spot and the other in an oxygen deficient moist zone downstream from the hot spot which is at a relatively low temperature of approximately 100°C. This has implications for the interpretation of mine atmospheres.

Jan 1, 2009

By W. C. Morgan

The Federal Surface Mining Law enacted in 1978 is now being translated into regulations which must be followed in future coal mining. Substantial change to mining procedures is required to maintain stricter air and water control while mining and to return the mined out land to equal or better use than before. These changes do not come easy; and in most cases, they create a substantial additional cost. Based on field observations and mining studies, Caterpillar has been making suggestions on the use of their types of equipment to conform to the new standards at the least cost. This paper will be a brief review of some of the overburden stripping and reclamation methods suggested by Caterpillar. A production and cost comparison of dragline, scraper/dozer and truck, loader systems in 20 to 150 ft. Overburden conditions illustrates potential cost savings using mobile equipment.

Jan 1, 1980

By J. Barrett

State-of-the-art wireless communication and location-tracking technologies will dramatically change the face of mine worker safety. The MineTracer System developed by a Liberty Lake Washington company is a broad capability wireless sensor network based on a new breed of technologies known as wireless mesh systems. In this paper, R&D Manager Jim Barrett summarizes the balance of engineering tradeoffs that result in a system that (1) performs well, (2) is survivable against many types of mine accidents, (3) operates for many hours post-accident on battery power, (4) meets stringent MSHA requirements for intrinsic safety, and (5) is economically affordable for the mines.

Jan 1, 2009

By M. Alley, P. Schroeder, L. Zelazny, S. Nagle

The Old Hickory mineral sands ore body in Virginia (>2000 ha) currently supports a productive rowcrop agriculture. Reclamation experiments were implemented on pilot-scale mining pits from 1995 to 1998. Half of each mining pit was topsoiled (25 cm) while the remaining half was left as either (1) mixed tails/slimes or (2) re-graded subsoil over tails/slimes treated with 112 Mg/ha yardwaste compost. Post-mining productivity was estimated to be reduced by 23%, 3%, 27%, and 20% for each crop (wheat/soybeans/corn/ cotton) in sequence when compared to undisturbed soils. Variability in surface texture and compaction limit restoration of soil productivity.

Jan 1, 2002

By J. A. Botín

Traditional risk quantification methods provide little information on the sources of risk, and tend to produce static over-conservative evaluations, which do not account for changes in the performance of the project. Capital investment decisions for large mining projects require of more complex risk evaluation models, that include the value of flexibility and the different risk levels associated with uncertainty on project variables (price, grade, dilution, production rates, among many other). In this context, Real Option Valuation (ROV) methods have proven potential to quantify the risk associated with such variables and integrate alternative scenarios and management strategies into the evaluation process. In this paper, a risk quantification model is developed, which successfully quantifies the risk associated to dilution, as a function of production rate. This model is then validated in a case study on the Chuquicamata Underground Mining Project.

Feb 27, 2013

By Bruce Hebblewhite

This paper focuses on the recent achievements and practices developed through the Minerals Tertiary Education Council (MTEC) initiative of the Minerals Council of Australia (MCA), in conjunction with the three partner universities involved in mining engineering education – University of New South Wales (UNSW), West Australian School of Mines, Curtin University (WASM), and University of Queensland (UQ). The collaboration between these partner universities and industry has led to the development of shared course material, cross-institutional teaching arrangements, and development of a number of flexible, distance-based delivery programs. The paper will then move on to future initiatives. Importantly, the exciting challenge is the future initiative planned to cement this collaboration by the formation of a “virtual” national school of mining engineering – Mining Education Australia (MEA). This will provide a common 3rd and 4th year program to all three universities from 2007, involving innovative teaching and learning arrangements, greater student exchange potential and a more significant input by industry into the education process. Such an initiative is not without its challenges, and has a long way to go, before becoming a reality. However, it offers greater attractiveness and marketing potential to prospective students, as well as economic efficiencies, whilst delivering a better quality, and hopefully greater quantity of graduates to industry. It can also form a launching platform for a much greater level of international collaboration, through a proposed International Mining Education Network (IMEN) which is currently being floated amongst a number of international educators.

Jan 1, 2005

By K. Holmberg, D. Herriot

This paper by Mr Mclvor is yet another contribution to the eternal controversy surrounding the benefits, or otherwise, of high circulating loads in closed circuit grinding. Throughout the paper it is difficult to establish whether the author is referring to effects relating to the mill, classifier, or to the overall circuit. Table 1 is put forward as indicating the advantage of operating at high circulating loads. From the two (it would be interesting to see more) product sizing points provided in each case, the conclusions to be drawn are that cases one and two have very similar size analyses. The third case, however, indicates a much flatter curve, that is to say, higher fines production and a very wide spread of size ranges. If the objective of this circuit is to provide a closely sized product with minimum overground slimes to the downstream process, then it would appear to be the less "efficient" by far. No data is given for product pulp densities either. The term "efficiency" should never be used without a careful and clear definition. In this case, "efficiency" is used to express an apparent percentage reduction in operating work index (Bond) from the measured "standard" at 250% circulat¬ing load operation. The Bond calculation is itself based upon

Jan 1, 1989

By Magno Rodrigues Ribeiro, Alexandre Cabral Stelzer, Cacio José da Silva, Leonardo Nogueira Ferri, Marcelo Ciminelli Mendes, Christophe Bouché, Marco Aurélio Soares Martins, Evenilson Soprani Lopes, José Xavier da Silva Filho, Sérgio Luiz Dalvi

Since 2001, CVRD is carrying out a modernization project in it’s pelletizing plant’s automation systems, that comprehends instrumentation, control and information systems. In addition, the project includes implementation of advanced control systems, using artificial intelligence techniques, including fuzzy logic, expert systems and dynamic physical models, to increase production, reduce fuel and energy consumption and improve quality. This paper reports CVRD’s experiences in carrying out an optimization project.

Jan 1, 2005

By B. K. Mishra

In order to maintain higher grinding efficiency in tumbling mills the mill interior and dynamics must be known. For this purpose, several different types of non-intrusive methods have been proposed and are being tried in the industry. We have made an effort to develop a diagnostic tool based on vibration signal. Here we discus results of our experiments pertaining to ball as well as SAG mill. In each case, a triaxial accelerometer was used to capture mechanical vibration generated due to the tumbling action of the charge. The vibration signal was transmitted to a remotely placed computer and the signals were analyzed by standard signal processing technique. In case of a ball mill (5m diameter), qualitative mill information could be obtained by correlating the vibration signal to feed rate and mill filling. An effort was also made to identify different motion characteristic of the charge by analyzing its vibration signal. In case of the SAG mill (10m diameter), liner wear was estimated by comparing the vibration signal emitting out of a freshly lined mill with that of a worn out mill.

Jan 1, 2011

On Nov 1, 2007 House Resolution 2262 ? The Hardrock Mining and Reclamation Act of 2007 ? was passed by the U.S. House by a vote of 244-166. HR-2262, among other things, would impose a 4-per-cent royalty on existing mines with commercial production and an 8-percent gross royalty on all new claims. Not surprisingly, this possible new law was one of the hottest topics of discussion at the Northwest Mining Association?s conference that this year returned to Spokane, WA for its 113th annual meeting on Dec. 3-7. More than 1,800 delegates attended the conference that was held under the banner theme of ?Mining ?. For today and tomorrow.? Northwest Mining Association executive director Laura Skaer was one of many speakers during the three-day conference to respond to the threat to the industry posed by HR-2262 with a presentation titled ?Potential changes to the 1872 Mining Law.? In the presentation that she first unveiled at the Alaska Miners Association?s convention and trade show on Nov. 8, Skaer laid out a comprehensive list of problems with HR-2262. In addition to the association?s obvious concerns about the proposed royalty, Skaer noted that the bill includes a mine veto provision that would allow the Secretary of the Interior the authority to deny an operations permit to a project if the secretary determines that the operation would cause undue degradation to public lands and resources. Potential massive withdrawals from mineral entry are also included in HR-2262. Among the lands that could be off limits to miners under HR-2262 are wilderness study areas, areas of environmental concern and 23.6 hm2 (58.5 million acres) identified as Roadless Rule. States, political subdivisions and Indian Tribes would also have more authority to withdraw lands, she said. To combat the proposed changes, Skaer made 10 trips to Washington D.C. on behalf of NWMA members in 2007. In her presentation at the annual meeting, she also objected to provisions that include no life-of-mine permits and uncertain permit renewals and new and duplicative environmental standards that she said are vague, ambiguous and inconsistent with current federal and state environmental laws. Debra W. Struhsacker, an environmental permitting and government relations consultant, also spoke on the issue of HR-2262 with a presentation titled ?The House mining law bill ? Rip van Winkle is back ? and he?s meaner than ever.?

Jan 1, 2008

In practice, frothers are selected following general guidenlies and verification by laboratory and/or plant flotation tests. The terms “powerful” or “selective,” which are commonly used to characetrize frothers, have intuitive rather than scientific meaning. A research program has been set out to study fundamental properties of the flotation frothers and to identify the tests which can provide information needed to characterize and classify such flotation agents.

Jan 1, 2004