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By Susan L. Bednarz

Recent advances in digital cameras and image processing allow photographers to produce excellent high-resolution action shots in low light and high contrast conditions commonly encountered underground. Digital photography is often used for construction and inspection documentation for underground structures. Designers, owners, and contractors benefit from quality photographs that document incremental progress and project milestones. Documentation photos serve as a lasting record of as-built conditions, are an important marketing tool, and help the owner build public support for expensive public works projects. When the project is complete, the only mementos that the participants will hold onto are the photographs.

Jan 1, 2008

By Henning E. Soderberg, Robert Brien, O&apos

Coal may be the answer to US energy problems, but it also has its drawbacks. If it is crushed, screened, dumped, or moved, the environmental engineer is faced with a dust problem. To control coal dust, at both minimum initial cost and reasonable operating cost, demands a working knowledge of dust control equipment design, as well as the coal handling operation. Here are some guidelines to reduce air volume requirements and cut overall system costs.

Jan 10, 1981

By Robert D. Coyle, David L. Emmons

Introduction The Cove gold-silver deposit is located in Lander County, NV about 50 km (30 miles) southwest of Battle Mountain, NV (Fig. 1). The deposit is in the north-central part of the Fish Creek Mountains within the McCoy mining district. Gold was first discovered in the McCoy district in 1914 by Joseph H. McCoy (Vanderburg, 1939). From 1928 to the early 1930s, minor production occurred from shallow underground workings. Total gold production was less than 311 kg (10,000 oz; Stager, 1977). The district was inactive until the mid-1960s when it was explored by Bear Creek Mining, Summa Corp., Houston Oil and Minerals Corp., Gold Fields, and Tenneco Minerals. Tenneco began a detailed reevaluation of the McCoy deposit in the fall of 1984. Tenneco's decision to place the deposit into production was based on a geological reserve of 8.7 t (280,000 oz) of gold (Kuyper, 1987). Subsequent exploration and development drilling of the McCoy skarn deposit has more than doubled the mineable skarn reserves to 19 t (615,000 oz) of gold. In September 1985, Tenneco began development work on the McCoy gold-skarn deposit. The project is an open-pit, heap leach mine. The first gold was poured in April 1986. Echo Bay Mines acquired Tenneco's precious metals properties in October 1986. The mining operation and district exploration started by Tenneco is continuing under the Echo Bay's ownership. The Cove deposit was discovered in January 1987 and production began in February 1988. The deposit will begin as an open-pit, heap leach operation. It will be converted into an open-pit and underground mine with a 9-kt (10,000-stpd) mill. Geologic setting The Cove gold-silver deposit is situated on the east flank of the Fish Creek Range. Surface elevations range from 1460 to 1680 m (4800 to 5500 ft). The deposit is 1.6 km (1 mile) northeast of the McCoy gold-skarn deposit. The Cove deposit is hosted by the Augusta Sequence of Triassic age. Three formations of the sequence are mineralized at the Cove. In ascending order they are the Favret, Panther Canyon, and Augusta Mountain formations. The Favret formation is a gray, locally silty limestone that is commonly fossiliferous. The base of the formation is not exposed. Exposed and drilled intervals are more than 60 m (200 ft) thick. Conformably overlying the Favret formation is the Panther Canyon formation. This formation is 215 m (700 ft) thick and consists of a siliclastic and carbonate sequence of conglomerate, quartzite (sandstone), mudstone, limestone, and dolomite. It is a distinctly coarsening-upward sequence of rocks. The top of the unit is conglomerate with chert and quartzite clasts up to 150 mm-diam (6 in.-diam). The Augusta Mountain forma-

Jan 8, 1988

By R. Tamblyn

Vertically stirred media mills are a highly effective low-footprint solution for the ultrafine grinding of industrial minerals. This work investigates the effect of media density on flow patterns within the mill. Direct irradiation of a media particle leads to decay through positron emission, consequently forming two anti-parallel gamma rays, which allow for the real time tracking of particle position. Grinding media of the same size, but with a range of specific gravities are followed using this method, and the effect on the flow within the mill is revealed. The technique is seen to be an effective method to highlight the velocity profiles within the mill, as well as the zones where grinding is less efficient ? areas of relatively low velocity and high residence time. The changing media is seen to effect the overall flow patterns within the mill, having consequential effects on the efficiency of the grind.

Jan 1, 2009

By J Addai-Mensah, W Skinner, K Quast

The efficiency of any iron ore value-adding operation is closely associated with detailed knowledge of the mineralogy, especially in the processing of lower grade and complex ores. There are a number of physico-chemical properties of iron oxide mineral phases (eg goethite, hematite and magnetite) that can be prudently exploited to enhance their processing efficiency. Recent iron ore studies on the upgrading of high-goethite iron ores have highlighted that the knowledge of the various phases of both iron oxide and gangue minerals is critical to the economic processing of these ores. Appropriate knowledge of this kind can lead to better-designed flow sheets for economically viable production of saleable products. With the increasing use of goethitic materials as blend components of iron ore concentrates for steelmaking, this review paper focuses on relevant beneficiation processes and the pivotal role of mineralogy and petrology in producing saleable iron oxide concentrates from ore blends. For goethites, mineral impurities including silica, phosphorus and alumina are very important. Physical separations, as well as those incorporating higher temperatures, have also been included in this review as potential processes to upgrade high-goethite ores.CITATION:Quast, K, Addai-Mensah, J and W, Skinner, 2017. The importance of mineralogy and petrology on the beneficiation of iron oxide ores, primarily those containing goethite, in Proceedings Iron Ore 2017, pp 233–240 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Phil Thwaites

"The mining industry uses many types of mineral and metallurgical plants to produce saleable product from ore mined. Plant design history has left current operations with a mixture of manual operation and various forms of automated process controls. Consequently, we typically see high variability in the continuous operations together with a shortfall in the attainment of full capacity, or higher utilization of consumables.At a level of best practice, “Operational Performance Excellence” focuses on process control, using automation and control systems to deliver process optimization. This more sophisticated delivery is a great deal more difficult than the first stage of equipment selection / installation. It includes the appropriate selection of the right instrumentation, control system, key process knowledge, individuals with a solid control engineering background/experience, and the essential backing/ support of the operations management team together leading to higher value delivery. Robust solutions can be realized, considerably minimizing process variation, thus leading to process optimization. This approach results in an easier, efficient and safer process while providing considerable returns for the plant owners.How variable are your processes, and do you maintain optimized process performance with dedicated resources, modern instrumentation, ‘best practice’ control systems and performance monitoring tools? In this lecture, these questions and their possible answers are discussed.357"

Jan 1, 2013

By O. F. Brown

The use of quality materials (aggregates and asphalt binder) in optimal proportions is the key to producing optimally performing hot mix asphalt (HMA). The Superpave mix design standard in the US introduced specific volumetric and binder property requirements in HMA design. Different methods for HMA constituent proportioning have been proposed in various guidelines. The design process to determine the HMA blend is currently iterative and engineers rely almost exclusively on experience. This approach is time consuming and often does not result in cost-optimal HMA mixtures. This paper introduces a mixed integer linear programming (MILP) optimization model for hot-mix asphalt constituent proportioning. The MILP model minimizes the total mix cost while satisfying all the volumetric, binder and mix property specification requirements. The model has been successfully validated with real-life example. The aggregates and binder ratios from the model were in close agreement with those from the contractor. The Bailey ratios and the gradation constraints were also satisfied. The cost of the optimal mix was $0.804/Mg less than that of the contractors?. This marginal reduction might make all the difference in an industry that is highly competitive. The MILP model also demonstrated that adding RAP to the contractor?s design would reduce the cost of the blend by $5.74/Mg. The virgin binder content was reduced by 1% because of the recycled asphalt contained in the RAP. This work represents the first successful attempt in incorporating both aggregate and asphalt performance requirements into the optimization formulation. Applying these models will ensure the minimum cost mix that meets all constraints and will increase profit margins for plant operators.

Jan 1, 2012

By Don Thompson

Canada’s oil sands are a controversial topic and virtually every newsmaker and layperson seems to have an opinion about this 179 billion barrel resource. The oil sands represent 97 per cent of Canada’s remaining oil reserves, but misinterpretation and misrepresentation of the facts are threatening development of a resource that generates significant employment and tax revenue for Canadians. Join Don Thompson, president of the Oil Sands Developers Group, as he dispels the top ten myths about Canada’s oil sands and presents an alternative perspective on an industry that can play a critical role in North America’s economic recovery.

Jan 1, 2010

By Ronald Molnar

"High demand for metals is driving the exploitation of lower grade and more complex orebodies. These projects are often the initiatives of junior mining companies with limited financial resources. In addition, existing operations seek to enhance revenue from their existing metal recovery operations, through the production of value-added by-product metals and chemicals. Typically, hydrometallurgical circuits, often with novel chemistry, are required to exploit these new ores, to produce the multiplicity of products that will make a marginal project economical, or to increase the product range of an existing operation. Often, the mineral processing engineer is given the task of coordinating the development of a back-end hydrometallurgical flowsheet for their mineral processing project. This paper discusses the objectives that companies have when they commission the operation of a hydrometallurgical pilot plant. The paper goes on to enumerate some of the principal differences between mineral processing and hydrometallurgical pilot plants and the effect these have on the design, operability and potential pilot plant outcomes. Important factors include working with chemically reactive solutions and pulps, elevated temperatures operation, changing rheological properties of slurries, the complexity of integrated circuit flowsheets with long hold-up times and multiple recycle streams, and the need in some cases for extreme attention to purity and cleanliness. Examples will be drawn from the extensive experience base of SGS Minerals Services at the Lakefield site, in piloting both mineral processing and hydrometallurgical process flowsheets.INTRODUCTIONWe are currently experiencing a period of strong growth in the demand for metals. This in turn is turning the spotlight on a great many smaller mining companies and mining promotion ventures trying to tap into the rising metal demand. Some of these companies want to develop their properties and recover metals while others want to develop to the point that a major company will take an interest, or in some cases buy them out completely.With the heightened interest in metals, many orebodies that have been known about for years are being reconsidered for exploitation. Often, the reason they have not been developed to date is because of difficult metallurgy and marginal grades leading to marginal economic viability. In both cases the key that unlocks the resources is often the application of a novel metallurgical flowsheet, often a hydrometallurgical flowsheet."

Jan 1, 2006

Jan 1, 1967

By R. Romano

Some topics, which difficult the effective use of RMR for dam foundations, are reviewed and a new geomechanics classification system, DMR (Dam Mass Rating), is proposed -as an adaptation of RMR- giving guidelines for several practical aspects in dam engineering and appraisal of dam foundation. On revise quelques problems qui ont fait difficile l’application du RMR pour les fondations des barrages. On propose un nouveau classification système, DMR (Dam Mass Rating)-comme un désarroi du RMR-qui donne recommendations pour quelques problèmes pratiques dans le projet et construction des barrages, et de ses fondations. Es werden einige die praxisgerechte Nutzung des RMR (Rock mass Rating) erschwerende Themen betrachtet und ein neues Geomechanisches Einteilungssystem, das DMR (Dam Mass Rating), eine Anpassung des RMR, vorgeschlagen. Daraus resultieren neue Richtlinien für verschiedene praktische Aspekte beim Dammbau und bei der Beurteilung von Dammunterbauten

Jan 1, 2003

By M. A. Barakat

"Adsorption of heavy metal ions specifically, Cu(II), Zn(II), Mn(II), and Cr(VI) from aqueous solution on synthetic 4A Zeolite was evaluated. The 4A zeolite was synthesized previously by dehydroxylation of low grade Kalabsha Kaolin at 800 °C, and reacted hydrothermally with 2-4 M NaOH solution at 100 °C for 2h. The adsorption capacity of the metal ions were found to be strongly dependent on pH and initial metal ion concentration. At the optimium conditions the adsorption capacity decreased in the order Cu(II) > Zn(II) > Mn(II) > Cr(VI) ions. Almost complete adsorption was achieved for both of Cu(II) and Zn(II) ions at pH > 6, while the adsorption capacity for both Mn(II) and Cr(VI) was 96, and 55.3 % at pH 11 and pH 3, respectively. The results also showed that the grain size of the 4A zeolite has a little effect on the adsorption capacity. The experimental data was compared with two adsorption isotherms, Langmuir and Freundlich isotheroms. The results showed a good agreement of the Langmuir plots with the experimental data.1. IntroductionSeveral industrial wastewater streams may contain heavy metals such as Cr, Cu, Pb, Zn, Co, Ni, Mn, etc. including the waste liquids generated by metal finishing or the mineral processing industries. Heavy metals are considered hazardous pollutants due to their toxicity, even at low concentration, and nonbiodegradability. Increasing level of heavy metals in natural water bodies poses a serious threat to all living species including humans. It is, therefore, essential to reduce the heavy metal concentration in effluents/wastewater before it is discharged into the water bodies [1]."

Jan 1, 2008

By Winton Gale, David Oyler, Jinsheng Chen, Christopher Mark

The National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Research Laboratory (PRL), RAG Pennsylvania and Strata Control Technologies of Australia have collaborated to conduct an extensive study of roof bolt strata interaction at the Emerald mine in Southwestern Pennsylvania. The primary goal of the project was to obtain detailed data on the interaction between the mine roof and the support elements for use in modeling studies. The study site was a longwall tailgate subjected to high horizontal stress. Three arrays of instruments were installed at the site, one in the tailgate entry and two in an adjacent crosscut. Pumpable concrete cribs were present in the tailgate array, and cable bolts were installed in one of the crosscut arrays. The instruments included mechanical and sonic extensometers for measuring roof movement, instrumented roof bolts, and three-dimensional roof stress cells. The study was ultimately successful in determining the magnitude of the horizontal stress concentration, the height of roof failure and the roof failure sequence, and the loading history of the primary roof supports.

A Loss of Strength of Gold Sulfide Concentrate Before Grinding and Cyanidation Using Magnetic Impulse Treatment Gold recovery from sulfide concentrates is going with cyanidation usually. The fine grinding to 95 per cent -0.020 mm is required for refractory concentrates, in which gold encapsulated by sulfides. According energy consumption is 10 and more kW h/ton. At this paper we suggested to use magnetic-impulse treatment with small energy consumption 0.1-0.2 kW h/ton for loss of sulfide strength before grinding and cyanidation. The object of studies was the gold-pyrite flotation concentrate which was produced from ores at the Kumtor Mine, Kyrgyzstan. The concentrate composition, physic-mechanical properties and loss of strength mechanism were studied there. The tested concentrate assayed, per cent: 62.5 pyrite, 10 feldspar, 10 mica, 5 quarts, 5 carbonates, 4 haematite and another. Haematite has intimate intergrowth with pyrite ? partially with quarts. The magnetic susceptibility of haematite and less pyrite causes in these grains and mineral complex the effect of magneticstriction. As a result numbers of deformations are increased and minerals and gold are also exposed. Lateral and longitudinal strains in the minerals by magneticstriction were calculated in this work. By quantitative analysis of pyrite mono fractions were showed next micro impurities: alumina, arsenic, nickel and others elements. These micro impurities are generated a charged dislocation, cracks and micro cracks. The inter-granular links at a boundary of haematite-pyrite, pyrite-quarts, haematite-quarts have disintegrated. The dislocation is depended from mineral modulus elasticity. It was determined an indicator of mineral electro-mechanic sensitivity which characterises a conversion of electro-magnetic energy to mechanic energy. Pyrite has most dielectric constant and electro-mechanic sensitivity as haematite and quarts. The dislocations in pyrite are account for clacks and a loss of mineral strength. Size analysis of the flotation concentrate after magnetic-impulse treatment is shown the increasing the content of thin fractions by comparison no treated concentrate. Magnetic-impulse treatment has increased the effect of the next fine grinding too. The electronic microscopy has confirmed a loss of strength of gold sulfide concentrate. The gold recovery by cyanidation increased too after preliminary magnetic-impulse treatment of concentrate by laboratory tests. The magnetic-impulse concentrate studies at the Kumtor plant have showed that a recovery gold increase in the processing of cyanidation. The consumption of energy also reduced.

Sep 13, 2010

During the lifetime of an open pit mining project, each stage from exploration activities to exploitation and mine closure produces disturbances on the mining region. Mined land reclamation plans establish constructive solutions to rehabilitate the disturbed areas. Open pit mining as an effective method for exploitation of a wide range of orebodies especially for massive reserves of shallow metallic substances has exhaustive and harmful environmental effects on the mining project region. Nowadays, closure and reclamation stage in a mining project is emphatically enforced by the relevant environmental protection regulations in many countries. It is therefore obvious that closure and reclamation costs of an open pit mining project, as costs of other stages of project, must be estimated to enter the planning and design processes in open pit mining. Post-mining land use is the most important factor to recognise closure and reclamation costs. Thus, using a model to define optimal land use in planning phase of an open pit mining project is necessary in this regard. In this project a model was developed to define optimal land use regarding different sections of open pit mines such as pit(s), waste dump(s), tailing pond(s), roads, areas for onsite facilities and free land zones which are not mined. TOPSIS and PROMETHE techniques were applied to create the developed model. Lumber production was recognised as the optimal post-mining land use for the pit area of the case study in this project.

Dec 6, 2010

By D. P. R. Smyth

The limestone reef reservoir at Swan Hills consists essentially of a "buildup" of successively smaller atoll-like layers. Precipitation of calcium carbonate within the lagoonal area of each layer essentially kept pace with growth of the outer organic lattice. Within the reef mass, six de-positional environments characterized by specific suites of fossils (or fossil fragments) and associated limestone textures are recognized as follows: ( 1) Aerated moderately agitated water of normal marine salinity (widespread shelf or submerged reef-built platform). Thamnopora-type corals, Amphipora, "pancake" stroma-toporoids, crinoids, articulate bra-chiopods, rare rugose cup corals, and ostracods occurs in light gray-buff skeletal microgranular limestone of low permeability. (2) Semi-stagnant quiet water of normal marine salinity (leeward side of reef). Crinoids, articulate brachio-pods, rare thamnopora-type corals, Amphipora, pancake and bulbous stromatoporoids, rugose cup corals, ostracods and gastropods occur in impermeable dark brown argillaceous skeletal calcilutite with thin black bituminous shale beds and rare dark chert nodules.

Jan 1, 1961

By John F. Wiss

A series of controlled experiments was conducted at four surface coal mines to study the effects of certain blast parameters upon the ground and air vibration. Preliminary scale-model blasts were conducted at a quarry to provide basic data. It was found that the amplitudes of the ground and air vibration were controlled by the maximum explosive weight per delay. Either cube root or square root scaling could be used for the seismic amplitudes, and cube root scaling could be used for the overpressure amplitudes. Both amplitudes were not significantly affected by the total charge weight per blast, the attitude of the boreholes, or the charge length or diameter. The overpressure amplitudes were affected by the charge depth, the use of cover over surface detonating cord, and the use of adequate stemming. The length of the delay intervals and the spacing of holes were important in determining the potential for reinforcement of the amplitudes in certain directions from the blasts. In downwind directions from the blast, the attenuation of the overpressure with distance decreases. Surface terrain did not significantly affect the overpressure amplitudes within the range investigated. The type of overburden affects the generation of both amplitudes and the propagation of the seismic amplitudes. Spectral analysis of the ground and air vibration is reported. A bibliography of pertinent literature is included as an appendix. A scaled distance of 300 ft/lb1/3 should produce a peak particle velocity of less than 1 ips and an overpressure of less than 128 dB linear peak. For square root scaling, a scaled distance of 75 ft/lbl/2 should limit the ground vibration to less than 1 ips.

Jan 1, 1978

By Janne P. Isohaka, Anssi M. Laaksonen

"Abstract In Scandinavia the use of steel pipe piles in bridge foundations started in the mid-1980s and has increased steadily since. As the piles driven in soft soils are slender, they can fail by buckling. Buckling usually requires taking into account the second order effect in structural and geotechnical design.The purpose of this paper is to derive formulas for demonstrating the theory behind the formulas given in literature for the second order effect of initially bent piles.IntroductionIn Scandinavian countries solid bedrock usually lies at moderate depth. If the bridge site is in an area where the soil above the bedrock is soft, the bridge is usually founded on end-bearing piles resting on the bedrock.The main purpose of the piles is to transfer axial forces into bearing soil. Like columns, piles can lose their stability by buckling when surrounded by soft soil. When axial compression on a slender, initially straight, pile reaches a particular value called the critical load, the pile is subjected to lateral deflection and loses stability. The soil around the pile suffers a corresponding deformation. This soilstructure interaction increases the critical load compared to a pile without surrounding soil.It is very unlikely that piles are ideally straight. Initial curvature along with curvature and deviation caused by the installation of piles causes bending moments to the pile when normal force is applied. These lateral displacements increase when normal force increases. This increase of moment is called asecond order effect.Eurocode and literatureEurocode 7 includes guidelines for the design of piles (Eurocode 3, section 5 includes design of steel piles). However, there are no clear guidelines for considering the second order effects related to piles surrounded by soil. Eurocodes advise doing structural design of piles the same way as in the case of columns. With columns, the second order effect is taken into consideration by multiplying the first order moment with the factor shown below (SFS EN-1992-1-1, 2005):"

Jan 1, 2014

By Timothy W. Beck

Roof bolter occupations in underground coal mines continue to experience overexposure to respirable dust. One potential source of dust in roof bolting operations is the exhaust from the roof bolter dust collection system. A wet exhaust conditioner (?water box?) has been developed to reduce dust emissions from the exhaust of the vacuum dust collection system on roof bolting machines. The exhaust conditioner consists of a muffler chamber and a water chamber with four internal partitions to direct airflow over the surface of the water. The National Institute for Occupational Safety and Health conducted a series of laboratory tests to assess the respirable dust capture ability of this device as compared to the standard exhaust muffler. To determine the dust collection efficiency, both devices were placed in the exhaust stream of a simulated roof bolter dust collection system. Gravimetric samplers were operated upstream and downstream of the exhaust conditioner and muffler to evaluate the ability to capture both respirable coal and limestone dust. Researchers observed a 41 percent reduction in dust concentrations for the water exhaust conditioner in the laboratory configuration. Significant levels of dust deposition in the sampling chambers may have contributed to this effective capture rate.

Jan 1, 2010

Effects of Hydrated Mg2+ on KCl Flotation

Sep 13, 2010