Search Documents

By Fidelis T. Suorineni

The conditions for rockburst occurrence are traditionally identified as: high stress, high extraction ratio, strong brittle rocks, folding, faulting, and unfavourable excavation geometry. Based on a critical review of case histories, this paper identifies oblique loading of orebodies by the major far field principal stress as a cause of rockbursts. Orebodies subjected to this loading condition are termed orebodies in shear. Orebodies in shear are subjected to compressive and shear loads. The case histories presented unambiguously show that the magnitudes of the far field principal stress alone, and a knowledge of the conventional rockburst causing factors are not sufficient for mine planning and design. The orientation of the major far field principal stress, or for that matter the driving stress relative to the orebody axis, should be recognised as one of the causes of rockbursts. It is suggested that since stress orientation is an important factor, and orientations from stress measurements are so variable, orientations from stress measurement data be complemented with underground observations from borehole and excavation breakouts to determine the actual in situ stress orientation, whenever possible. Also stress modelling for the design of critical elements (pillars) should include a sensitivity analysis on the relative critical field stress direction. The paper emphasises that special attention should be paid to or

Jun 1, 2012

By S. M. Chentouf, M. Jahazi, N. Bombardier, T. Belhadj

The main limiting factor in the commercial expansion of superplastic forming (SPF) of thin sheet aluminum alloys is the extent of cavitation phenomenon that takes place during the processing. The severity of the cavitation process is mainly dependent on the uniformity of deformation (i.e. level of local thinning) during processing. In the present paper, correlations are made between thickness variations in several formed sheets and the characteristics of the cavities observed in the material. The 1.4 mm thick 5083 aluminum alloy sheets were hot pre-formed at around 450°C for 4 min and then air-cooled. Opto-digital and Scanning Electron Microscopy were used to examine the microstructure and analyse the cavities. Also, grain size measurements were carried out for different location in the SPF formed piece. The surface and volume fractions of the cavities were measured with the aid of metallography image processing (MIPTM) on as-polished samples prior to etching. The results are analyzed in terms of the influence of applied strain and microstructure conditions on the propensity to cavitation of the alloy.

Jan 1, 2015

By K. J. G Hedges

"Once a health based guidance limits for exposure to diesel exhaust have been established, and as part of a multi-disciplinary team, the program for exposure reduction should incorporate the plan-do-check-adjust cycle. Setting a suitably protective (health based) occupational exposure limit (OEL) for diesel particulate matter (DPM) and nitrogen dioxide is a key driver to reduce exposure. It is important to go beyond regulations and reduce exposure to diesel exhaust, DPM, as low as reasonably achievable (ALARA) such as that prescribed under the Australia, Queensland Mining and Quarrying Safety and Health Regulation 2017 where under section 135 Limiting workers exposure, the workers exposure must not exceed the exposure limit applying to the worker for the hazard; and is ALARA. It appears that previously acceptable OELs are no longer safe. Therefore it is important that the internal responsibility system be implemented and the precautionary principle approach be followed, especially as it may be some time before a suitably protective OEL specifically for DPM is in place. One leading multi-national mining company BHP Billiton has acknowledged a significant lag that exists between regulatory action and the level of science that informs health risk. This company is managing exposure to diesel exhaust to as low as technically feasible. This same company that has set an interim target for managing diesel exhaust to 0.03 mg/m3 is achieving these levels which paves the way for other mining companies and general industry including construction. The Occupational Cancer Research Centre 2017 recommends reducing personal exposure to within 0.02 mg/m3 (EC) for underground mining and 0.005 mg/m3 for other workplaces. Controlling DPM is important to prevent cancer however it is also important that that nitrogen dioxide (NO2) be reduced (ALARA) and that careful selection of control technology be considered such as the proper selection of a diesel oxidation catalyst so that the level of NO2 does not in fact increase. The example from BHP Billiton provides a leading practice including using a multi-disciplinary approach and the importance of controlling emission at source and having an auditable diesel emissions based monitoring program in place."

Jan 1, 2019

By B. N. Nandi

This paper is a study of the application of the science of coal petrology to the use of coal in the iron and steel industry. The petrography of coal is given the most attention, with some mention of coal palynology. The history of the petrographical analysis of coal is first out-lined, with a description of the various coal entities, and then the apparatus and experimental techniques employed for coal evaluation are discussed. The coke stability factor and the relation of coke strength to petrographical data are also covered, and some space is given to the new science of coke microscopy, in particular its use in following the oxidation of coals.

Jan 1, 1966

By S. B. Mishra

Ni-20Cr metallic coating was deposited on a Ni-based Superalloy (3Fe-19.5Cr¬0.3Ti-Balance Ni) by a shrouded plasma spray process; NiCrA1Y was used as a bond coat. Erosion studies were conducted on uncoated and plasma-spray coated superalloy specimens using an air-jet erosion test rig at a velocity of 40 m/s and impingement angles of 30° and 90°. The coating has been characterized for porosity, microhardness and microstructure and X-Ray Diffraction (XRD). An electron probe micro analyzer (EPMA) was used to obtain X-ray elemental mappings of the coating along the cross-section. Scanning electron microscope (SEM) with EDAX attachment was used to analyze the eroded surfaces.

Jan 1, 2005

By Takashi Nakamura, Atsushi Iizuka, Yong Fan, Etsuro Shibata

The level of iron in typical copper slag reaches nearly 40% by mass, in the form of iron silicate. We designed a method to oxidize the nonmagnetic iron silicate to magnetite, permitting the selective recovery of the slag’s iron content by magnetic separation. This would effectively decrease the volume of dumped slag; the reclaimed iron could be used for iron and steel making. The crystallization behaviors of magnetite and hematite were studied as reaction products of the molten oxidation of copper slag. A gas atmosphere of 1% by volume of oxygen was found to effectively precipitate the slag’s iron content as magnetite.

Jan 1, 2015

By A. M. L. Cushing, S. Kelebek

Presently, adsorption is one of the effective methods of removing toxic contaminants from waste waters. The contaminants from metal mining industrial operations include an effluent water containing various types of heavy metal species at concentrations beyond the maximum allowable limits, which are 0.5 ppm and 0.3 ppm for nickel and copper species, respectively. Adsorption behavior of copper ions pre-chelated with diethylenetriamine (DETA) and triethylenetetramine (TETA) onto natural bentonite and peat has been investigated. Both natural bentonite and peat was found to be capable of removing these copper-polyamine complexes from aqueous solutions relevant to process water effluents. However, the adsorption capacity of bentonite was significantly higher than that of peat. Two models were used to study the adsorption kinetics: a pseudo-first-order rate expression and a pseudo-second-order rate expression. For both adsorbents, the data conformed best to the pseudo-second-order rate expression. Representation of the experimental data through adsorption models was also investigated. Out of the four cases considered, namely, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms, it was found that for both bentonite and peat, the copper polyamine adsorption data conformed best to the Dubinin-Radushkevich adsorption model. The Langmuir model also represents the bentonite-copper polyamine adsorption system reasonably well as the second best case, suggesting that the amount adsorbed on bentonite might be a monolayer with strong affinity.

Jan 1, 2015

By R. L. Bishops

This paper discusses some of the materials, processes and systems used in motor insulation. Among the materials mentioned are epoxies, polyesters, mica paper composites and wire enamels. Two processes developed to take advantage of the special characteristics of two of these materials are described, and how these materials are used in several new insulation systems now on the market is discussed. Finally, future trends in motor insulation are outlined.

Jan 1, 1969

By Tom Gaines, G. S. Brant, J. G. Debanne

"AbstractThe Bonnie Glen oil field, one of Canada's largest, lies about fifty miles southwest of Edmonton, Alberta. One hundred and thirty-eight wells have been completed in this field since its discovery in January, 1952. Five different procedures have been used in completing the producing wells.The reservoir is an Upper Devonian biohermal reef with good porosity and uniformly high permeability. The top of the reef is quite flat but the flanks slope at angles approaching 20 degrees from the horizontal. The reservoir has a gas cap with a maximum thickness of 400 feet, an oil column of 300 feet, and a :porcus aquifer of over 300 feet. The reservoir pressure is now 2,400 pounds per square inch gauge at datum ( -4100 M.S.L.).Because of the high permeability and the high •pressure, lost circulation and resultant blowouts are a particular hazard in drilling at Bonnie :Glen field. To reduce the dangers of blowouts, it is general practice to run casing to the top of the reef. If the reef is encountered 'high' it was usual practice to run a liner and perforate for completion. Wells penetrating the •reef below the gas/oil interface were either completed in open hole or through casing perforated opposite the oil pay, with the former method more frequently used. Eight wells were completed by the Humble-Otis permanent-type completion, and recently five high wells were completed open hole with the gas •cap exposed. This latter completion, 'tubing submergence', has proved highly satisfactory thus far.The open-hole type of completion is cheaper than the liner perforation method and results in better well performance. More experimentation and data are needed before the tubing submergence method can be recommended unqualifiedly. but all evidence thus far favours its use in reef reservoirs."

Jan 1, 1955

By Farzad Khodabakhshi, Adrian P. Gerlich

"In this article, cold spraying process was utilized to coat the surface of AZ31 magnesium alloy with a layer of AA7075 aluminum alloy. Thereafter, friction-stir processing (FSP) was employed to enhance the microstructure and consolidate the deposited layer. The grain structure and phase morphology were studied along with indentation hardness before and after cold spraying and friction stir processing. The magnesium substrate had an initial hardness of 74 HV which increased to 102 HV after FSP due to refinement of grains to <2 µm. The aluminum coating layer, provided improved surface hardness up to 160 HV, which further increased to 173 HV after FSP was applied.INTRODUCTION Cold spray is a material deposition process which can be used for surface modification, since it deposits material on a metallic substrate with little heating by way of high velocity ballistic impacts. Using cold spray technology, it is possible to deposit a wide range of coatings with various thicknesses by controlling the characteristics of the feeding powder and metal substrate, gas temperature, gas pressure, powder feeding rate, nozzle geometry, and gun traverse velocity. This process has been recently employed for surface modification in various aircraft and automobile structural applications. This has led to a broad range of research using this process for production and modification of different metallic and non-metallic systems. In the present study, cold spray process was used to deposit a uniform layer of aluminum-zinc alloy (AA7075) on the surface of AZ31 magnesium alloy. This coating was subsequently treated by way of friction-stir processing (FSP) as a new post-spraying modification technique to enhance the structural homogeneity and densification of the coated aluminum layer. This method utilizes a non-consumable rotating tool with a specially designed shoulder and pin that is plunged into the surface of metal to be modified and then moved along the direction of interest. The localized frictional heating between the rotating tool and workpiece leads to softening of the materials around the pin, and material extrusion through a complex flow of material from the advancing toward the retreating side the tool. To the author’s best knowledge, only a few reports discuss the modification of a cold sprayed deposit by FSP process. The microstructure and mechanical properties of the cold sprayed layer and substrate before and after FSP modification were examined using optical observations (OM) and indentation hardness testing. Furthermore, the AZ31 alloy substrate alone was treated with FSP as well, for the aim of comparison to the processed coating."

Jan 1, 2017

By Nelson Hogg

"THE NOR-ACME gold mine is located close to the north shore of Snow Lake, at 54°53' north latitude and 100°03' west longitude. It is about 75 air miles east of Flin Flon, and 36 miles by road from Wekusko at Mile 81 from The Pas on the Hudson Bay Railway.The claims which contain the Nor-Acme orebodies were staked in 1927 by C. R. Parres, who, with his sons, held the ground until 1938 when Nor-Acme Mines Limited was incorporated. In 194 l, on the recommendation of F. Ebbutt (1), this property was optioned by the Howe Sound Exploration Company, Ltd. A program of 50,000 feet of diamond drilling resulted in the outlining of two orebodies containing an estimated 5,000,000 tons with an average grade of 0.15 ounces per ton to a depth of 1,000 feet.A period of inactivity during the war years was followed by the construction of a mining plant capable of treating 2,000 tons of ore per day. Milling started in March 1949, and to the end of 1954 has resulted in the production of 383,793 ounces of gold and 32,906 ounces of silver from 3,331,403 tons of ore.General GeologyThe general geology of the Snow Lake area is described by J. M. Harrison (2), and will not be discussed here except insofar as it affects the Nor-Acme orebodies. The orebodies occur in rocks of Precambrian age that have been classified by Harrison as the Snow group, comprising meta-morphosed sediments interbedded with acid and basic volcanic rocks. The volcanic rocks include pyroclastic types which are unique in the region, a fact which led to their classification in the Snow group rather than the more widespread Missi group that generally occupies the same stratigraphic position above the Amisk group (Figure 1)."

Jan 1, 1949

By J. Zachwieja

As part of a general review on study of surfactant blinding agents to improve gold recovery during cyanide leaching of carbonaceous gold ores, processes of CIL and RIL leaching using surfactants were investigated. When refractory ores were treated by surfactants, CIL and RIL leaching processes yielded significant improvement on gold recovery. This paper will discuss and compare the laboratory results from two different leaching processes on preg-robbing ores, as well as, illustrate the difference of potential fouling of the blinding agents on activated carbon and resins.

Jan 1, 2015

By B. K. Choi, G. E. Kim, S. Noh, T. K. Kim

Oxide dispersion strengthened (ODS) steel has been developed as the most prospective core structural material for next-generation nuclear systems because of its excellent high strength and irradiation resistance. In ODS steel, finely dispersed nano-oxide particles with a high number density in the homogeneous grains can be very attractive to achieve superior mechanical properties at high temperatures, and these favorable microstructures can be significantly changed using process parameters during the mechanical alloying procedures. In this study, the effects of mechanical alloying times on the microstructure of 10Cr-1Mo ODS martensitic steel were investigated. Pre-alloyed powders with Y2O3 powder were mechanically alloyed for various milling times using a high energy horizontal ball-mill apparatus (model: symoloyer CM20). Powder properties such as the mean particle size, size distribution, and crystallite size were evaluated. Uniaxial hot pressing was employed to consolidate the milled powders. The results of a microstructural observation after the MA and UHP processes indicated that the homogeneity of the martensitic structures was considerably increased with the longer milling time. It is thus concluded that the mechanical properties of the ODS martensitic steel are greatly dependent on the mechanical alloying times.

Jan 1, 2015

By J. Guha, A. Gobeil, P. Pilote, A. Tremblay, E. Dimroth

The Mount Bourbeau Lac Berrigan area is located just to the north of the Town of Chibougamau. The axial trace of the Chibougamau syncline borders the northern part of both areas. The area contains Archean rocks of the Roy Group, intruded by the Cummings Complex and the Line Lake tonalite stock. Proterozoic sedimentary rocks occur in a series of outliers. Various Cu, Zn, Pb, Ag, Au and Mo showings are dispersed over the area in a wide range of time and space. Pre-Kenoran (stratiform and stringer) showings related to volcanic activity may be distinguished as well as the syn-or post-Kenoran (vein) types whose nature is imprecisely known. In this area, the stratiform showings occur in the Gilman and Blondeau Formations, whereas the vein type showings occur for the most part in fractures or breccias within or along the contacts of the various sills of the Cummings Complex. Mount Bourbeau is distinguished by the greatest variety of showings as well as the proximal volcanic facies of the Blondeau Formation. A volcanic centre is presumed to lie a short distance north or east of the locality. Locally, the Line Lake stock contains significant silver, molybdenum and gold mineralization. Its role as a metal reservoir, a source of heat for the circulation of hydrothermal fluids and its control of the local tectonic style remains to be determined.

Jan 1, 1984

By Zoë Mullard

Just as a mine has a lifecycle, employees working within the mining sector also make several transitions throughout their career, from initial recruitment to retirement from the industry. Throughout the employment lifecycle, employees bring skills and knowledge that significantly contribute to the global economy. These skills are developed through education, professional training, coaching and through hands-on experience. Despite the current economic conditions and the demand for minerals, the mining industry is facing a substantial skills shortage due to the disparity between the number of new workers entering the mining industry and a largely ?graying workforce?. Although educational programs continue to evolve to attract people with a wide range of skills, the diversity of jobs and the strains of working in remote mining operations continue to present challenges for recruitment and retention of employees. This gap also presents challenges around knowledge transfer at a corporate and mine-site level; employers will require cultural and techno-sociological approaches to ease through these transitions. At the same time, there has been an explosion of social media tools that facilitate information sharing, cross-organizational collaboration, distance learning and knowledge capture. These tools have become increasingly popular in the last few years and their applications vary widely. The mining sector has started to adopt these tools for a number of purposes, including opportunities to harness social media to enhance human resources interactions, outreach and oversight. This paper will outline several case studies that explore leading practices for how the application of new media can assist organizations and individuals as they progress through their careers. This paper will illustrate how new social media communication technologies can be used to increase employee engagement and build organizational capacity in the mining industry. The paper will also include strategies for how to implement social media to enhance human resources applications and will cover ideas for monitoring and evaluation.

Aug 1, 2013

By John C. Luck Jr.

"DEVELOPMENT of oil emulsion mud dates back to the early days of rotary drilling when oil was added to the drilling mud solely for the purpose of freeing stuck drill pipe. After the drill pipe was freed, and drilling resumed, this oil was considered a contaminant. Efforts were made to remove the oil but some of it remained and was emulsified with the drilling mud, thus forming a mechanical emulsion.During the late 1930's, operators found that adding crude oil to drilling muds seemed to alleviate 'sticky-hole' problems and so oil was allowed to remain in the mud. This practice was adopted when it was found that faster drilling rates and longer bit life were obtained. These observations led to the development of emulsion drilling muds. During the past five years their application has become more widespread because of the lower fluid losses obtained, greater lubrication qualities, faster penetration rates, and generally better hole conditions.An emulsion may be defined as a two-phase system consisting of a mixture of either finely divided oil droplets in water or of finely divided water droplets in oil. The surrounding liquid is known as the continuous phase. The emulsifiers reduce the interfacial tension, making the droplets tend to repel each other so that they remain dispersed and stabilized. These emulsions are classified as oil-in-water or as water-in-oil, depending upon whether water or oil, respectively, is the continuous phase. Briefly, close inspection shows that they consist essentially of globules of• the one liquid suspended in a continuous mass of the other liquid. Oil emulsion muds are usually of the oil-in-water type. Two basic types of emulsifiers •commonly used in Canadian muds are soaps and lignites."

Jan 1, 1954

By M. Tardif, F. L. -Lavoie, M. Ruel

"In mineral processing, it is often very difficult to reliably measure several key operation variables. The harsh environment and high temperature encountered in pyrometallurgy processes lead to some difficulties when selecting the instruments, valves and actuators. If an important variable cannot be measured or manipulated adequately, controlling it can really become a big challenge. Sometimes, it is simply impossible to find the perfect equipment for the task. To help overcome these difficulties, a different approach is required. This approach will not correct the inherent problems related to the instruments and valves, but will cope with these problems. This article will demonstrate how modern process control techniques can be used to solve complex problems while remaining easy to implement. In this article we will described how soft sensors and multivariable fuzzy logic control were implemented at Koniambo Nickel to stabilize the furnace feed and allow for safe and reliable operation of an 80 MW DC arc furnace.INTRODUCTION Process Overview The process plant at Koniambo Nickel SAS is located in the North Province of New Caledonia, 310 km north of Noumea. The nickel-bearing ore is mined in the nearby Koniambo massif. After being screened and crushed, the ore is transported to the processing plant using a 12 km conveyor. After stacking in two blending piles, the ore, containing 2.3% nickel, is fed to the processing plant where it will go through the NST process (Nickel Smelting Technology) before being sent to refining and shotting. This article will focus on the improvement to control of the NST processes. The first steps of this process consist of milling the ore and removing all moisture through calcining (Figure 1)."

Jan 1, 2017

By P. R. Brito-Parada, A. Norori-McCormac

Positron emission particle tracking (PEPT) has become an important tool for flotation research, as it is able to resolve directly the behaviour of particles in laboratory scale flotation vessels. The first applications of PEPT to flotation showed only the motion of an individual particle in the pulp and the froth, but nonetheless allowed interpretations of behaviour not previously possible. Since then, PEPT measurement and data analysis techniques have improved significantly and now ensure a high level of confidence in the particle behaviour obtained. In particular, statistical analysis of long-duration experiments allows time-averaged data to be collated, ensuring spatial accuracy and allowing rigorous comparison of different conditions. It will be shown that these PEPT techniques can be used to compare directly the effect of operating conditions and particle properties in a laboratory flotation system. Particle tracks will be illustrated, as well as analyses of particle speeds, average flow streamlines and occupancy that show marked differences in behaviour near the interface and impeller.

Jan 1, 2015

By V. Aitken

Line-of-sight radio control has received widespread acceptance for use in many mining methods because today’s technology offers improved economics and personnel safety. Significant advances in higher autonomy for mining machines are not currently seeing widespread use even though they offer great future potential. With autonomous capabilities being a longer-term goal, a logical sequence of advances based on TeleRemote control is proposed. Under Tele - Remote control, the operator is in direct control of the machine at all times. Three levels of Tele - Remote control systems are presented including line-of-sight, extended line-of-sight, and full load-haul-dump applications. Distributed control and sensing subsystems arranged in a vehicle control area network support incremental system expansion through the three levels of TeleRemote control and prepare the machine for integration of higher levels of automation as mature technology becomes available. This approach allows full exploitation of today’s mining automation technology with a flexible future growth path.

Jan 1, 1998

By N. Ahern, L. Manoukian

"Cyanide is a leaching agent for precious metals commonly used in gold ore processing. Cyanide exists in various forms (including free, complexed as weak or strong complexes, and as ions such as cyanate and thiocyanate), so its detection, speciation and analysis in processing or environmental samples can be complex. This paper will review best practices for cyanide sampling and preservation in the field, interferences and pretreatment methods required prior to sample analysis and analytical methods that are used for cyanide species. Titrimetric, flow injection ligand exchange, spectrophotometric, colorimetric, potentiometric, amperometric, and chromatography techniques will be discussed and their chemistries, detection limits, advantages and limitations will be described.INTRODUCTION Cyanide is well known to be an extremely toxic species. Accurate cyanide measurement in effluent from mines is critical from an environmental perspective. Its measurement is also an important control parameter in the recovery of gold using cyanidation. Cyanide chemistry is diverse and complex, and cyanide analysis can be challenging as a result of and because of limitations in understanding of analytical methods. Various chemical mechanisms can form or destroy cyanide, and the sample matrix or preservation chemicals can also affect analytical results. These interferences make the collection of reliable cyanide measurements challenging and can start as soon as the sample is collected, during laboratory pre-treatment and during analysis. This paper reviews different methods of cyanide measurement. The basic chemistry of cyanide, best practices for sampling and preservation, as well as various methods of analysis will be discussed.CHEMISTRY The complexity of cyanide chemistry is well known (Beck, 1987; Delgado, Botz, Bucknam, Milasovljevic, & Staley, 2008; Botz, Milosavljevic, & Ward, 2013) and is attributed to the ability of cyanide to undergo: •,Volatilization •,Precipitation •,Adsorption •,Complexation with metals •,Oxidation to cyanate, ammonia, or cyanogen chloride •,Reaction with sulfur or sulfide minerals to form thiocyanate •,Redox reactions leading to the formation of cyanogen and cyanate •,Redox reactions (of some cyano complexes) •,Photochemical reactions (of some cyano complexes)"

Jan 1, 2017