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By D W. MacFadgen

THE operating advantages of the longwall retreating system of mining, as opposed to longwall advancing, have been well known for many years. Although retreat walls have been successfully worked in the past in some of the collieries of the Dominion Steel and Coal Corporation in the Sydney, Picton and Cumberland areas, the adoption of longwaIl retreating as the general sys-tem of mining has not been attractive in the Sydney field, due to the time and expenditures required to drive roadways to the boundary. In addition. difficulties in maintaining effective ventilation on the faces, especially under conditions of low barometer, have made the operators in the field hesitant to adopt this as the general system of mining. The development of a machine capable of rapid entry drivage has made possible the driving of the necessary road ways to the boundary at a moderate cost, completely changing the picture and making a retreat system more attractive.

Jan 1, 1961

By Kathy S. Kalenchuk

Damages have been observed in shafts, backfill infrastructure and the slick line at the Leeville Mine. Shaft damage (shearing and spalling of the concrete liner) is attributed to mine-induced rock mass deformations concentrated where regional faults intersect the shafts. Aggregate bin, mixer station and conveyor drive damage (shotcrete shearing, heave of concrete floor slabs and bending of a vertical steel beams) is attributed to rock mass squeezing induced by elevated magnitudes of the vertically orientated major principal stresses. Separation of the slick line has occurred do to extension of the stressshadowed rock mass immediately above the mined out areas. Three-dimensional numerical models have been developed and calibrated to simulated rock mass deformations with magnitudes similar to those believed to have produced the observed damages. By stepping through the mine sequence, models reproduce deformations at the same mining stage as when damage has occurred. Calibrated models have been used to forward project further damage over the remaining mine life.

Jun 1, 2012

By S. A. Kenzap

Risk & Uncertainty ? Uncertainty about a situation can often indicate risk, which is the possibility of loss, damage, or any other undesirable event. Most people desire low risk, which would translate to a high probability of success, profit, or some form of gain. Risk = Likelihood x Consequence Risk is the possibility of loss, damage, or any other undesirable event.

Oct 1, 2010

By Eduardo A. Pérez, Alejandro R. Alonso, Rosa María Luna-Sánchez, Gretchen T. Lapidus

Rare earth elements have been widely used in various sectors, from the aerospace and steel industries, to electronic applications, particularly in displays and batteries for portable devices. The high demand for newer and better equipment, such as cell phones, tablets and lap tops, has increased the consumption of the rare earth elements and at the same time the need for its recovery from electronic wastes. For that reason, the recycling of batteries is important, principally the Ni-HM batteries, due to their elevated content of rare earths elements, in addition to the high concentrations of cobalt and nickel. The current processes are based on dissolution in strong acid solutions (sulfuric acid concentrations from 2 to 4 mol/L), and temperatures from 30 to 90°C. In the present work, electrodes from spent Ni-HM batteries were leached using 1 mol/L H2SO4, in the presence of ozone as the oxidant, where recoveries of 96% for La, Ce and Nd were obtained at room temperature. The separation of Ni and Co from the leach solutions was performed using an electrochemical reactor, after which rare earth elements were precipitated, obtaining a mixture of its hydroxides with impurities below 1%, according to EDS analysis.

Jan 1, 2014

By James Kear, Romain Prioul, Robert G. Jeffrey, Andrew P. Bunger, Dimitry Chuprakov

"Unconventional gas and geothermal reservoirs are typically naturally fractured and therefore the challenging problem of hydraulic fracture (HF) growth through naturally fractured rocks is an important issue especially for the development of accurate predictive HF models. This paper presents results from laboratory experiments in which HFs have been created in both sandstone and crystalline (gabbronorite) rock specimens such that they impinge either orthogonally or at an oblique angle on an unbonded, machined frictional interface. Depending on the conditions of each experiment, the fractures either cross or are blunted at the interface. The growth behavior was ascertained for these experiments based on a synthesis of the injection pressure record, active ultrasound monitoring, and direct post-experiment inspection of fractured specimens. From these experiments we observe: 1) A contrast between direct crossing and crossing with an offset for orthogonal and oblique intersection, respectively, 2) Apparent independence of crossing/blunting behavior on the friction coefficient for orthogonal intersection, 3) Dependence of the stresses required to promote crossing on the intersection angle between the HF and NF, 4) Existence of cases in which the hydraulic fracture crosses but then essentially ceases propagation such that all fluid is diverted to the interface. INTRODUCTIONHydraulic fracturing is a vital technology used to increase the productivity of oil, gas, and geothermal wells. Predicting hydraulic fracture (HF) growth is, in turn, critical to design of hydraulic fractures that grow to the desired length, accept the desired amount of proppant, and remain contained in the reservoir without unwanted height growth into surrounding layers (e.g. Economides and Nolte, 2000). The importance of HF modeling has prompted 6 decades of research during which simulators have become more efficient, more accurate, and have addressed a growing range of complexities (see review of e.g. Adachi et al., 2007).One of these complexities is the interaction between HFs and mechanical discontinuities such as natural fractures (NFs). Efforts in this area have been mainly driven by development of unconventional (i.e. low permeability) oil and gas resources because essentially all viable low permeability reservoirs, including shale gas/oil reservoirs, are naturally fractured to some degree (King, 2010). One of the most important questions for developing effective HF stimulation strategies in these reservoirs is whether the hydraulic fracture(s) is/are expected to be single-stranded or whether interaction with the NFs will lead to network-like growth. The basic building block for numerical simulators that can address this question (such as Kresse et al., 2013 and Weng et al., 2014) is whether an HF that intersects an NF will cross the NF or whether its growth will be captured by the NF so that additional fluid injection pressurizes the NF but does not generate ongoing growth of a new HF. These scenarios, including subcategories such as crossing with an offset, have been recognized for several decades (Daneshy, 1974; Warpinski and Teufel, 1987, and as recently reviewed and expanded by Chuprakov et al., 2013)."

Jan 1, 2015

By Will S. Pettitt

Fracture Network Engineering (FNE) is the engineering design of rock mass disturbance through the use of advanced techniques to model fractured rock masses numerically, and then correlate field observations with simulated fractures generated within the models. Microseismic (MS) monitoring is a standard tool for evaluating the geometry and evolution of the fracture network induced during a hydraulic treatment, principally by source locating MS hypocenters and visualizing these with respect to the treatment volume and infrastructure (Figure 1). The integrated use of Synthetic Rock Mass (SRM) modeling of the hydrofracturing with Enhanced Microseismic Analysis (EMA) provides a feedback loop in which the SRM is constrained by the information provided by the MS data and the in-situ behavior of the fracture network is better understood, leading to informed decisions on future field operations. This paper discusses the technologies used in FNE and some of the developmental challenges we face in order to provide a more efficient and robust application of the approach. One particular challenge is the accurate representation of MS source data within the models (locations, magnitudes and mechanisms), and the ability to correlate these data effectively with field results. This challenge is being overcome by the development of more efficient numerical modeling algorithms, providing simulations in three dimensions at reservoir scale, combined with validation of these algorithms using laboratory and field case studies.

Jun 1, 2012

By M. B. M. Monte, M. L. Torem, E. R. Pecanha, A. G. Merma

The recent literature has unveiled the potential use of microbial strains in mineral bioprocessing. This study presents the use of a Gram-positive bacterium (Bacillus subtilis) as bioreagent for hematite flotation. The bacterium presents the ability to modify the properties of mineral surface (electrophoretic mobility and hydrophobicity). It was studied the electrokinetic behavior of hematite particles, before and after the interaction with the bacterial cells. The results revealed a shift of the isoelectric point (IEP) of the hematite after interaction with bacterial cells, suggesting a chemical adsorption mechanism. Moreover, after bacterial conditioning, the zeta potential curve of hematite presented high values in the alkaline pH range. The hematite and the bacterial surfaces presented contact angle values around 27.4° and 41.0°, respectively. According to the results, the B. subtilis strain was capable of modifying the hematite surface, and after interaction the hematite surface presented a contact angle value around 46.0°. The flotation tests were carried out in a modified Hallimond tube. The experiments revealed a significant increase in hematite flotability using the Gram-positive strain as bioreagent. The tests pointed out a maximum recovery of hematite in the presence of 600 mg/L and pH 5. Therefore, the results from this study showed the potential use of the B. subtilis strain as a biocollector for hematite flotation, and its possible application in the mineral flotation industry.

Jan 1, 2016

By Peter S. Jack

"IntroductionTHE ORES treated at the concentrator of the Britannia Mining and Smelting Company, Limited, Britannia Beach, B.C., have always contained some lead, but it was not until 1950 that the combination of lead headings and lead price was such that recovery of this metal at Britannia became worthwhile. In that year, with the mining of a new orebody, the lead in the mill feed was raised from 0.07 per cent to 0.15 per cent. Chalcopyrite, sphalerite, and pyrite concentrates are produced by flotation at Britannia, •and 95 per cent of the lead in the mill feed reports with the chalcopyrite concentrate, so that the rise in lead headings was reflected almost wholly in the lead content of the copper concentrate. In 1950, investigation was started to determine if some of this lead could be recovered economically."

Jan 1, 1953

By Kent Zehr

Suncor Energy Inc. is an integrated producer and refiner of oil and gas headquartered in Calgary, Alberta. The bulk of revenue comes from the Oil Sands Group (OSG) operating in the McMurray formation of the Athabasca Oil Sands. Located some 25 kilometers north of Fort McMurray, Suncor OSG began life in 1967 as Great Canadian Oil Sands, the first operator to successfully enter commercial production of synthetic crude oils from the area. For most of the last decade, dramatic growth has been the standard mode of operation for Suncor OSG. Production of synthetic crude first reached 100,000 barrels per day in 1997 and less than five years later is averaging in excess of 200,000 barrels per day. Within this dynamic organization, Suncor Extraction is the business unit that processes run-of-mine ore into clean diluted bitumen for Upgrader feedstock. Extraction also delivers and places the barren sand and process affected water into tailings storage in one of several ponds from which water is recycled to support the various processes. For reference purposes, Extraction on a typical day currently receives more than 400,000 metric tons of oilsand ore, which is all processed to water based slurry for separation in one of two extraction plants. Separated tailings are disposed of as a slurry and the cleaned bitumen froth is diluted with naphtha and sent to tankage for storage until required by the Upgrading Unit. As a consequence, on a typical day Suncor Extraction pumps more than 1,000,000 tonnes of aggressive slurry into and out of the two extraction plants.

May 1, 2003

By Gordon A. Irons, H. Y. Hwang

An impinging gas jet on a water surface was studied to understand momentum transfer in oxygen steelmaking. Depth, width and oscillation frequency of the jet cavity were measured and the splashes interpreted with Kelvin-Helmholtz instability and combined Rayleigh-Taylor and Kelvin-Helmholtz instability theory. A model to calculate separate gas and liquid velocities, applying the exact momentum boundary condition, is proposed.

Jan 1, 2004

By J. Dubinski

Poland is the ninth largest coal producer in the world and Coal Company is the largest Polish producer of this deposit yielding 51% of national production. Coal Company mines are located in the Upper Silesian Coal Basin. These are underground mines which operate in difficult geological conditions at great depths of up to 1200 m. One of the most common natural hazards in Polish mines are rockburst and seismic hazard impacting on surface infrastructure and habitants. In the assessment of the rockburst and seismic hazard methods of mining seismology play a leading role. This paper presents progress that was achieved in the last few years in the implementation of new seismic monitoring systems and seismic interpretation methods for the prevention of hazard deriving from seismicity induced by mining. This progress in assessment of rockburst hazard and impact of seismic activity on the surface infrastructure was achieved through close cooperation between the Coal Company and Central Mining Institute ? the country?s leading scientific institute in the field of mining seismology. New theoretical solutions are in the process of testing in mines of Coal Company where seismic monitoring systems are installed and controlled by well-qualified personnel. Some directions of further joint actions to increase the effectiveness of rockburst and seismic hazard assessment are presented as well.

Aug 1, 2013

By Matthew S. Hall

Gold/iron oxide catalysts have been prepared and their catalytic performance evaluated for low temperature CO oxidation. The method and temperature used to dry the sample has a significant effect on their catalytic activity. Analysis by TEM revealed the catalysts contained Au particles, although catalysts with high and low activity did not always differ in their microstructure as evidenced by TEM. Catalysts were characterised using XPS and the difference between the Au(4d) and C(1s) binding energies measured; in general the greater the difference, the higher the catalytic activity of the material.

Oct 1, 2003

MR. J. F. MYERS, Consulting J3eneficiation Engineer, Greenwich, Conn.: In the written discussion contributed by Mr. F. C. Bond in item ( 2) (page 515), speaiking about the significance of the ratio of mill diameter to the make-up ball diameter, he states: "When this ratio exceeds 100 the power and capacity of the mill are de-creased"; and the paragraph ends with a reference to the 30 per cent ball volume "with some de-crease in mill capacity". I believe this broad statement is incorrect. When we are dealing with a non-cataracting mill, pre-ceded by a good rod mill, there is a slight increase in capacity, but the power does drop. The second point that I consider needs consideration is Mr. Bond's item (8), Proper Mill Speed (page 516). This paragraph should be qualified to cover single-stage mills only. It does not apply where a rod mill is followed by a non-cataracting ball mill. The statement as is, with no qualification, gives an erroneous idea of proper mill speeds.

Jan 1, 1957

By S. G. Shabestari

In the metal casting industry an improvement of component quality mainly depends on better control over the production parameters. Thus, thermal analysis cooling curve of the alloy is used for process control in aluminum casting industry. Cooling rates of the alloy during solidification process affect microstructure, grain size, eutectic silicon morphology, and dendrite arm spacing (DAS). In this research, effect of cooling rate on the microstructure and solidification parameters of 319 aluminum alloy that is a widely used alloy in automotive industry, has been investigated by means of thermal analysis. Seven different cooling rates have been obtained by using CO2-bonded silica sand molds with two different wall thicknesses, hot-work tool steel molds (H13) with and without coating, thin-wall steel molds with different coatings. In each case, cooling curve and first derivative cooling curve have been plotted by use of very accurate thermal analysis equipment. Effect of different cooling rates on solidification parameters e.g. Nucleation temperature (TN,a), nucleation undercooling (ATN,a), recalescence temperature (TR,a), solidification range (AT,s), and total solidification time (t 0 have been studied in the liquidus region. Microstructural evaluation has been carried out and DAS were measured in all solidification conditions. A numerical equation was proposed to predict cooling rates via measuring DAS in 319 aluminum alloy. Nucleation process and the effect of cooling rate have been interpreted by using thermal analysis cooling curves and microstructural study.

Jan 1, 2004

By J. Keith Haddock

"IntroductionThe Bienfait Mine is operated by Bienfait Coal Company Ltd., one of the Luscar Limited group of companies. Situated 5 km southeast of the town of Bienfait, Saskatchewan, it can produce 2.0 million tonnes of lignite annually in addition to 158,000 tonnes of char from a carbonization plant located on the property. Geology The economically mineable coal seams of the Estevan area are found in the Ravenscrag Formation. The lignite-bearing sands, silts and clays were deposited in Early Tertiary age, in an inland sea centred in the Williston Basin of North Dakota. The top of the Ravenscrag is an erosional surface, overlain by Tertiary or Quarternary sands and gravels or glacial till. The regional structure is a gently plunging syncline which dips to the southeast at about 0.3 degrees. There are minor undulations in the Bienfait area which are due to differential subsidence during deposition. Sporadic faulting is probably a result of glacial pressures, and preglacial and glacial channels are responsible for washout zones and the abrupt irregular subcrop found in the area. There are two economic coal seams in the Bienfait area, an uppe; seam locally known as the Roche Percee, and a lower seam, the Estevan. Both seams have been extensively mined since lignite mining began in the area in the late 1800s. The Roche Percee remains only in a small portion of the Bienfait Mine and comprises a very minor portion of the reserves. It averages 1.74 m thick under 8.1 m of overburden. The till rests on top of the Roche Percee and due to weathering the seam is generally of poorer quality. The Estevan seam comprises the majority of reserves at Bienfait. The main seam which is being worked on consists of an upper bench averaging 2.75 m, a carbonaceous parting of 0.21 m, and a lower bench of 0.92 m. Overburden depth above this seam varies from 21.0 m to 38.0 m."

Jan 1, 1985

By Matej Petružálek, Václav Vavrycuk, Tomáš Svitek, Tomáš Lokajícek

The most common type of waves used for probing anisotropy of rocks in laboratory is the direct P wave. Information potential of the measured P-wave velocity, however, is limited. In rocks displaying weak triclinic anisotropy, the P-wave velocity depends just on 15 linear combinations of 21 elastic parameters, called the weak-anisotropy parameters. In strong triclinic anisotropy, the P-wave velocity depends on the whole set of 21 elastic parameters, but inversion for 6 of them is ill-conditioned and these parameters are retrieved with a low accuracy. Therefore, in order to retrieve the complete elastic tensor accurately, velocities of S waves must also be measured and inverted. For this purpose, we developed a lab facility which allows the P- and S-wave ultrasonic sounding of spherical rock samples in 132 directions distributes regularly over the sphere. The velocities are measured using a pair of P-wave sensors with the transmitter and receiver polarized along the radial direction and using two pairs of S-wave sensors with the transmitter and receiver polarized tangentially to the spherical sample in mutually perpendicular directions. We present an inversion method for elastic parameters describing general triclinic anisotropy. We demonstrate on synthetic tests that the inversion becomes more robust and stable if the S-wave velocities are included. This applies even to the case when the velocity of the S waves is measured in a limited number of directions and with a significantly lower accuracy than that of the P wave. Finally, we analyze velocities measured on a rock sample from the Outokumpu deep drill hole, Finland, including the error analysis for several levels of confining pressure.

Jan 1, 2015

By Alan Bauer

IN RECENT PAST YEARS, the mining industry has expanded rapidly and mining engineers have not been generated in sufficient numbers to sustain this growth. Canada has not been alone with this problem, which has resulted in considerable soul-searching as to what the solution might be. Because of the unfavourable economics of running small departments such as mining, metallurgy, ceramic engineering, etc., one approach in some cases has been to put these departments together to form a department of mineral science which now has a broader base structure. Another solution has been the "conversion kit" program which has been conducted both at universities and in industry. At universities, such programs have consisted of converting graduates of other engineering disciplines into mining engineers. In some of the large mining corporations, extensive training programs have been used with the same aim.

Jan 1, 1972

By W. A. Bell

The Carboniferous system of rocks in the Maritime Provinces include as workable mineral and organic substances, gypsum, anhydrite, salt, coal, building stones, grindstones, limestones, brick-clay shales, fire-clay shales, oil shales, etc. The system is, therefore, pre-eminently of economic value to the provinces in which it occurs, and the more knowledge we may gain concerning it, the more we may be prepared to aid in the development of these useful substances. For this purpose it is not sufficient to state that the ground upon which we stand is underlain by Carboniferous rocks. In-discriminate digging or drilling will not open many new mines of wealth, however difficult it may be to dampen the optimism of gamblers. For mineral wealth has not been scattered in the rocks haphazard, now here, now there, but its distribution has been the result of natural earth forces acting at intervals throughout the countless millions of years that have elapsed since our planet was born. As regards the majority of metalliferous deposits, the earth forces involved have resulted in the penetration of surface or sub-surface rocks by molten rock-matter and associated mineral solutions from deep-seated sources. But the economic Carboniferous deposits that have been mentioned are themselves types of bedded surface rocks rather than immigrant deposits, and their formation and geological history is closely related to that of the rocks with which they are interbedded.

Jan 1, 1924

By Graham Sim

Agenda ?The Water Challenge ?Examples from Three Case Studies ?Mine Drainage, 99% recovery ?Mine Drainage, 80% recovery ?Road Dust Control ?Technology Development ? Conclusion Global water challenges Assuring sustainable quantity Improving water quality Reducing energy consumption

May 1, 2011

By Abhinav Karanam, Lukas Bichler

Yttria Stabilized Zirconia (YSZ) is a promising thermal insulator for high temperature environments due to its thermal stability and chemical inertness. As was demonstrated with other technical ceramics (e.g., Alumina), addition of Single-Wall Carbon Nanotubes (CNTs) to a ceramic matrix may significantly enhance the mechanical properties of the composite ceramic. In this work, 8 mol% YSZ with 0.2, 0.5 and 1wt% CNTs composites were prepared via Spark Plasma Sintering process. The densification, Vicker’s microhardness, specific gravity and microstructure evolution of the composites were investigated. The results suggest that the addition of up to 1wt% CNTs to YSZ yielded optimal combination of the studied properties. At higher addition levels, the specific gravity decreased and clustering of CNTs occurred, leading to poor densification and a relative loss of performance.

Jan 1, 2014