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By A. Djebara

Today, indoor air quality, especially in manufacturing industries, is of great interest due to the use of new processes and advanced materials such as those containing nanoparticles. Manufacturing processes generate aerosols (dry or wet) which can be detrimental to occupational health and safety and to the environment. Controlling metallic particle emissions during machining processes should limit their formation at the source, and thus minimize the risk of exposure; this at-source reduction requires the characterization of the particle emitted (size, nature, concentration, etc). The metrics normally used in characterizing fine and ultrafine particles include the mass concentration, the specific surface and the number concentration. Most of these metrics are affected by the size, the geometry and the density of the measured particles. Information about the form and the real size of the particles is thus very important. A procedure for collecting and characterizing fine and ultrafine metallic particles was developed and applied to the study of particles emission during the machining of aluminum alloys. It was found that metallic particles emitted during the machining of aluminum alloys are of various shapes and sizes, and this information must be taken into account when characterizing these particles.

Jan 1, 2011

By H. S. Wilson

"The property owned by the Lamaque Mining Company comprises a group of forty-four claims and fractions occupying an area of about 2,458 acres, in west-central Bourlamaque township, Abitibi county, Quebec. It is on ,the outskirts of the towns of Bourlamaque and Val d'Or, about 70 miles east of Noranda, near the eastern end of the belt of greenstones of Keewatin and Timiskaming age that extends eastward through Kirkland Lake into northwestern Quebec, terminating in Haig and Jurie townships 40 miles to the east.The claims on which the orebodies occur were first staked in 1923; No. 3 vein was discovered the following year. The original discovery was made by R. Clark in 1923. This was a small quartz vein containing a pocket of coarse gold on the north side of a hill near the northwestern corner of block 3. It is said that all the gold was removed in one shot in blasting into the vein; elsewhere it was barren. A picket line was then run west along the strike of the vein, which occupied a narrow shear zone, and about 2,000 feet west, in prospecting on either side of the picket line, a large boulder of quartz and tourmaline containing visible gold was found. This led to more intensive prospecting by trenching in the vicinity with the result that the No. 3, or 'float' vein, about 250 feet north of the boulder, was found. Due to low ground this vein was exposed in only one trench. The only other important vein found on the surface was the No. 1, or H, vein, which was exposed in several places by stripping and trenching, but it did not carry appreciable amounts of gold."

Jan 1, 1954

By T. C. Crosby

"Grinding has a marked effect on concentrator recovery and operating cost, and improved operation through automatic control can enhance plant performance. The correct application of automatic control can only be accomplished after the basic process variables and their effect on mill operation have been defined. This paper develops a control system for a closed circuit grinding system. Typical control systems, such as those for feed, water flow, level and circulating load, are discussed. A method of determining controllability, using the calculated reaction curve technique, is outlined. Various successful automatic grinding control applications are discussed and future possibilities are outlined. Although this paper primarily deals with closed wet grinding• circuits, the principles involved can be readily applied to other processes."

Jan 1, 1967

By H. Q. Fan

Construction equipment is an important type of resources of heavy construction contractors. Since equipment breakdowns can cause project delays and significant financial losses, the contractors are eager to know those factors causing equipment failures directly or indirectly, related to equipment design, maintenance, and operations. Although Bayesian network can be used for diagnostic analysis of failure events or making predictive analysis, building a Bayesian network for such purpose can be difficult as the cause-effect relations can be subjective and their conditional probabilities change with a wide variety of causal factors. A hybrid approach is proposed in this paper to update the Bayesian diagnostic network structures and parameters using real life data, the conditional probabilities and cause-effect relationships can be dynamically updated with observed failure records to reflect the real life situations of a complex equipment system. A case study is conducted to show the benefits of the hybrid approach in construction equipment diagnostic analysis.

Aug 1, 2013

By Kr. N. Karparov

Measurements made with high precision GPS landmarks and geotechnical radar Reutech MSR- 300 associated with the observed movements in the north face of Assarel Mine, where on a horizontal distance of 50 m, 2 groups of landmarks indicated different deformation behavior. Measurements are made in order to confirm the applicability of the radar system in regions of complex geotechnical conditions. The standard deviation of each landmark is used as an accuracy standard between the separate measurements of the deformation vectors made by the high-precision GPS system for each landmark. A very good correlation between the displacement vectors can be seen based on the measurements made with the high-precision GPS system and the measurements made by the radar system MSR-300. Geological, engineering geological and hydro-geological conditions of the area of concern are discussed in this paper. The measured deformations and the FLAC/SLOPE analysis show similar results. In the paper is discussed their local character and their sensitivity to other geotechnical and hydro geological conditions.

Aug 1, 2013

By R. Kumar, A. K. Verma

"In this paper, an anisotropic shear behavior of rock joints is investigated under constant normal load condition (CNL). The natural rock joint roughness is transferred to artificial rock samples using room temperature vulcanizing (RTV) silicon rubber. Artificial cylindrical rock joint samples (90 mm diameter and 50 mm height) are made by mixture of cement, sand, and water in the ratio of 1:1.5:0.45 (by weight). Direct shear tests are conducted on these samples in twelve directions at 30º apart at four different normal stresses (250kPa, 500kPa, 1000kPa, and 1500kPa). Thus, 48 samples are tested in laboratory. Test results shows that the peak shear strength (?) of rock joints is anisotropic in nature due to change in morphological features in particular shearing direction. Joint roughness coefficient (JRC) is determined in each shearing direction by trial and error method using Barton’s model (1973). Further, cohesion ( c) and angle of friction ( ? )of joint surface in each direction is determined. Finally, a relationship between angle of friction ( ? ) and joint roughness coefficient (JRC) is developed. Experimental shear strength and Barton’s shear strength is compared and it is found that effect of anisotropic decreases with increasing normal stress. INTRODUCTIONRock mass is generally composed of discontinuity which refers collectively to joints, faults, bedding plane and folds etc. ISRM (1978) defined joint as a line of break of geological origin along which there is no visible displacement. Joint is three dimensional discontinuity which composed of two matched/mismatched surfaces. The presence of joints in rock mass plays an important role to define its overall shear strength, deformability behavior, in-situ stresses and hydro-geological properties. The shear strength of rock joints is important in the design of near surface/ deep geotechnical works (mining excavation, dam foundation, power plants, underground caverns, and slopes).In last 40 years, many constitutive models are developed to predict shear strength of rock joints under CNL conditions (Patton 1966; Landanyi and Archambault 1969; Barton 1973; Goodman 1976; Barton and Choubey 1977; Plesha 1987; Desai ad Fishman 1991; Amadei and Saeb 1992; Maksimovic 1992; Wibowo et al. 1993; Huang et al. 1993; Amadei et al. 1998; Indraratna 2000; Homand et al. 2001; Wang et. al. 2003; Samadhiya et. al. 2008; Asadollahi and Tonon 2010; Ghazvinian et al. 2012). These constitutive models have limitations to predict shear strength of rock joints in one direction. Till date, among all constitutive models, Barton (1973) model is widely used in practice due its simplicity. It includes parameters such as joint roughness and joint compressive strength (JCS) to quantify joint surfaces."

Jan 1, 2015

By W. D. Mulholland

"I ASSUME that any effort on my part to deal with the question of the importance of the mining industry is going to be largely an exercise in preaching to the converted, but there are one or two aspects that I'd like to particularly mention.The first is that, in terms of almost all factors, the mining industry is a very important industry in Canada. It is important in terms of employment in relation to the gross national product of Canada and it is particularly important in the international trade of Canada. So far from being insignificant domestically, it is also an extremely important factor in the international picture. That's an important point to bear in mind, because as we talk about all the other matters we never can lose sight of the fact that mining management always has to be conscious of its international competitive position. It is something that one forgets at one's peril, and to a somewhat greater extent than is true of many other industries, those managements have to compete in an international context for their markets, to some extent for their people for specialized skills and of course for finance. In the evolution of domestic policies it is a very, very perilous step to take to impair that competitive ability of the domestic mining industry."

Jan 1, 1972

By Adrian Dance

Newmont Mining Corporation?s Carlin (?Carlin?) operation processes roaster feed through a double rotator, dry grinding mill following secondary crushing. Metso Process Technology & Innovation (?PTI?) was involved in a review of crushing and dry grinding circuit operations in August 2009. A number of opportunities for increased throughput were identified in the PTI study. Extended plant trials were conducted in July 2010 to provide justification for possible circuit modifications and if needed, additional equipment. The trials confirmed that a finer crusher product would reduce the build-up of material ahead of the coarse grinding chamber in the double-rotator. Also revealed were material transport and airflow restrictions in the dry grinding circuit that resulted in a high circulating load. The secondary crushing plant demonstrated it was capable of reducing the amount of +¾? material in the mill feed thus increasing dry grinding throughput. However, wet and sticky feed affected screening efficiency resulting in low utilisation of the existing crusher capacity. The open circuit configuration also made it difficult to control crushing circuit product size. For the dry grinding circuit, changes in grinding media size, transfer grate design and increased airflow were recommended to reduce circulating load issues and increase circuit capacity. This paper summarises the crushing and grinding circuit review, the extended site trials performed by PTI and the improvements in dry grinding operation that resulted from this study.

Jan 1, 2012

By W. Keith Buck

This paper defines the discipline of mineral economics. By example, it describes the application of the tools of economic analysis to mineral problems - to problems in the areas of: mineral resource analysis and forecasting, mineral industry activity from exploration to distribution and marketing, mineral commodity analysis, and mineral policy analysis and policy formulation - all in a regional, national or international context.

Jan 1, 1972

By M. J. Latva-Kokko

This paper describes the behaviour of iron and the methods used for iron control in the nickel matte leaching process. OMG Harjavalta Nickel Oy processes approximately 10 000 t/y of iron, which enters the process with the nickel matte raw material. Iron dissolves and precipitates in several different stages of the leaching process. Compounds like ferric hydroxide, parabutlerite, goethite, hematite and jarosite are found. Iron removal is done within the leaching process, and this means that the dissolution of nickel sets the limiting conditions for iron precipitation. A leach residue consisting mainly of the iron precipitates is neutralized and stacked in the waste pond. When iron is precipitated from concentrated nickel sulphate solution, some nickel is lost by co-precipitation. Recent studies have shown that Ni-Fe ratios less than 1%, attributed to co-precipitation, can be obtained with jarosite precipitates, compared to 2-3% ratios typically found with hematite precipitates. Iron can be precipitated as jarosite under the optimal nickel leaching conditions by adding ammonium sulphate to the feed slurry of the autoclave.

Jan 1, 2006

By J. R. Fisher

"Uranium may be leached to some extent in situ from the Blind River conglomerate uranium ores by using the products of bacterial activity from the bacterium Thio-bacillus ferrooxidans his paper describes some of the laboratory techniques used to investigate the characteristics of the bacteria, and to utilize their properties in uranium leaching. The application of some of the laboratory results underground at the Milliken mine of Rio Algom Mines Limited are de-scribed, along with the method of uranium recovery from the mine waters."

Jan 1, 1966

By P. A. Peach, W. H. Gross

The modern economic geologist in Canada is well equipped to apply geological, geochemical or geophysical techniques in the exploration for ore. Recently, great advances have been made in geophysics and geochemistry, and a large number of new orebodies have been discovered by these methods. An attempt is made in this paper to show that there has also been a considerable advancement in geological knowledge and that the most effective application of geophysics and geochemistry often occurs in areas already considered geologically favourable for the occurrence of ore. Ali exploration methods sooner or later suffer from diminishing returns. Therefore, as time goes on, one can expect to see the application of some of the more subtle or refined geological techniques that are presently being developed.

Jan 1, 1967

By A. Hayatdavoudi, K. G. Sawant, F. Boukadi

"In this work, we found that contact between shale and water results in development of micro fractures. Based on results of experiments on Pierre shale, we conclude that appearance of micro fractures begin with saturation of capillaries, ionic and diffusive transport of water into the shale clays and once capillaries are saturated, the cause of micro fracture propagation is the conversion of ionic activity/exchange to excess pressure that did not exist before fracking. Based on these findings, the spread of micro fractures appear to be a time-dependent phenomenon which has not been addressed in the existing macro/micro fracture models.INTRODUCTIONShale has often been involved as a hazard in drilling operations. This hazard can be defined as “destabilization” of shale. When contacted with water-based drilling fluids, some shales readily swell and sometimes, cause the wellbore to cave-in, slough, wash-out, close, and pack-off, impeding the drilling by sticking the drill-pipe. However, once drilling reaches the desired depth or length, the casing is set, cemented, and perforated, and then actually we wish to initiate fractures and destabilize the shale formation, using hydraulic fracturing.Clays constitute a major portion of minerals in shale. These clays contain a large amount of free energy which is the main factor for “slick” water adsorption/absorption. In fact, the reason for using “surfactants” in hydraulic fracturing fluids is to make the penetration of the fluid into the capillaries much easier, thus water meets with less resistance to enter the small capillaries. Also, the result of high capillary suction pressure is due to small Angstrom size capillaries, smaller pores and presence of ions and hydrateable metal atoms. The free energy is thus, related to all the above mentioned and other affects. Capillary pressure, osmotic pressure and other pressures are responsible for creating the micro-fractures in shale, thus, increasing the network of micro-fractures which leads to more gas production. The objective of this study is to evaluate the pressures of the individual ions which are released by the diffusing “slick” water into shale. These pressures would be added to the above mentioned capillary pressure, osmotic pressure, bacterially-induced pressures, chemically-induced reaction pressure, pressure due to exchangeable ion-transport, pressure due to release of free energy of solvation and eventually to the pore pressure as suggested by Terzaghi’s equation."

Jan 1, 2015

By Grant S. Diamond

THE BIBLIOGRAPHY on the use of static electricity in mineral beneficiation consists largely of patents. Some references are found in mineral textbooks, but very little data on flow-sheets of commercial installations are known to the writer. As a matter of fact there have been relatively few successful commercial applications of importance. Johnson prepared and published a Table showing the polarity and static field intensity requirements of many minerals. There have been reports of successful beneficiation of rutile, zir-con, coal, potassium chloride, and phosphate rock. Otherwise, the field of success has been very limited. This may be due to three reasons: first, the mining industry has been averse to dry processes, be-cause of dust nuisances in dry crushing; second, the electrostatic processes used in the past apparently developed no substantial economic advantages; and third, because flotation or other . methods have proven successful on many minerals, the industry has not felt the need for a radically different process. In the feldspar industry there was ?an attempt at electrostatic beneficiation about twenty years ago which was based on the use of fluoride fuming of the pegmatite head feed, in order to make the mineral reactive in a static field. This process was originally said to be successful, but was discontinued because of corrosion damage to machinery. Another effort by use of a chemical additive such as an or-ganic hydroxyl compound has also been attempted. Neither of these processes is known to be in use today.

Jan 1, 1957

By B. Dubreuil, J. -M. Lalancette, D. Lemieux

A gold bearing pyrite concentrate was treated at the pilot scale for the extraction of gold. Mineralogical analysis of the concentrates identified gold to be mainly present in the form of a solid solution in pyrite. Gold distribution resulted in a poor extraction yield of 55 % by direct cyanidation. A piloting campaign including an oxidative pre-treatment by roasting in a fluid bed was followed by treatment with halogens for gold extraction and has led to a gold extraction yield of 94%. Sulphur removal during the oxidation was very efficient at >99.5% and gold extraction by the halogens was completed within a 1 hour contact time. The piloting was performed on a 300 kg sample and used a diluted solution of hypohalites as the oxidizing agent for gold extraction. Sulphuric acid was injected in the reactor during the halogens treatment to lower pH to 2. The diluted solution of hypohalites (1-3%) was generated by electrolysis during the piloting campaign in a diaphragm-less electrolysis cell. The extracted gold was recovered via adsorption over silica and the gold depleted brine was treated for impurities removal. This brine was recycled for further gold extraction. With the recycling of water and brine, the regeneration of hypohalites and with a barren solid that is inert and stable, the Nichromet Extraction technology is a green process where the protection of the environment does not preclude profitability.

Jan 1, 2014

By F. W. Guernsey

Of all the elements, sulphur occupies a place by itself. It is mined in situ, in such quantities and of such purity that, as regards the tonnage produced, it is the first of any element on the list. Iron and coal the great tonnage producers, are combinations of elements, while sulphur is mined and marketed almost chemically pure. It is sold, in large quantities, commercially, calling for a purity of 99.5 per cent while for medicinal purposes, the Pharmacopoeia requires only 99 per cent. purity. It is a very common commodity, and like many common things is of extreme importance, in the progress of our civilization. The substance has been known from the earliest times, the word sulphur being derived from the Sanskrit Culvari", hence the Latin Sulphur. Commercially it is also called brimstone, this word being a derivative of the Anglo-Saxon Bryne Stane or burning stone. From our younger days, we have been more or less familiar with the mineral. On the spiritual side being threatened, if we did not behave ourselves, with an ultimate consumption in a lake of fire and brimstone, (which in moments of reflexion was not pleasant to contemplate) while our bodily ills were taken care of by inward applications as a spring medicine. In both instances, the effect required, was generally attained. Sulphur occurs in nature, both free and in the combined state, it being estimated that it forms, over one tenth of one per cent of the first ten miles of the earths surface. (I do not know who did the estimating and it is not guaranteed).

Jan 1, 1923

By E. Gaucher, M. St-Amant

"Among the electromagnetic surveys performed by SOQUEM in the last three years, a certain number of the more instructive cases have been chosen to illustrate the theory of electromagnetism by field examples of: (a) The depth penetration of the TURAM as compared to the SLINGRAM (Ronka) method. (b) The limitations of the TURAM as compared to the SLINGRAM method when a conductor dips the wrong way, or when it is small in size. (c) The expression of a shallow-dipping conductor in a SLINGRAM survey. (d) The effect on the SLINGRAM survey of deep ditches or reef structures.(e) A comparison between the CRONE and the SLING-RAM method in the Abitibi clay belt, by means of field and model studies, indicating a usually better signal-to-noise ratio for the SLINGRAM method. From the above and from other experiments, different electromagnetic methods are now being used by SOQUEM, depending on field conditions."

Jan 1, 1970

By T. Urbancic, Eric von Lunen, G. Viegas, A. Baig

"The characterization of the failure process of induced fractures by hydraulic stimulation is fundamental to understanding the generation and evolution of the discrete fracture network within the reservoir. A more detailed analysis of the fracture mechanism can be a powerful tool for identifying fluid flow paths and proppant placement within the reservoir. For example, during the rupture process the energy release is partitioned into different physical processes for which the relative ratio is changed by the presence of fluids or rotations in the local stress field with relation to the frictional resistance in the fracture plane. Fractures occurring in the same host rock under the same stress conditions are expected to rupture similarly, independent of their size (self-similarity). Changes in the scaling relationships of fractures are indicative of a change in the failure process, host rock or in-situ stress. Correlation of failure process data with reservoir rock properties and the in-situ stress field will help identify regions within the reservoir with characteristic types of failures. Further correlation with hydrocarbon production data can be used to develop efficient treatment plans and production diagnostic tools.In this study we investigate the failure process of ~27,000 microseismic (M < -1) fractures induced during a hydraulic fracturing shale completion program in NE British Columbia, Canada by estimating static and dynamic source parameters, such as dynamic and static stress drop, radiated energy, seismic efficiency, moment tensor, fracture plane orientation, slip direction and rupture velocity. On average, the microseismic events have low radiated energy, low dynamic stress and low seismic efficiency, consistent with the obtained slow rupture velocities. Events fail in overshoot mode (slip weakening failure model), with fluids lubricating faults and decreasing friction resistance. Events occurring in deeper formations tend to have faster rupture velocities and are more efficient in radiating energy. Variations in rupture velocity tend to correlate with variation in depth, fault azimuth and elapsed time, reflecting a dominance of the local stress field over other factors.Further identification of spatial and temporal distribution of families of events with similar characteristic rupture behaviors, based on either rock formation, depth, source type, fracture plane orientation, stress drop, pad or proppant stage, may be used as a proxy for specific fracture network development and hydrocarbon production. This information may be used to determine reservoir properties, constrain reservoir geo-mechanical models with measured physical parameters, classify dynamic rupture processes for fracture models and improve fracture treatment designs. These will be the focus of future studies."

Jan 1, 2015

By T. R. Kostecki, K. V. Jessu

"Roof bolts are subjected to axial stresses, shear stresses, or both. Axial and shear stresses were compared between roof bolts machined with two and three slots. Shear stresses perpendicular to and at an angle to the shear planes were evaluated by analyzing a three-slot instrumented roof bolt, performing laboratory tests on two- and three-slot roof bolts, and conducting in-situ test analyses. Threeslot bolts appear to provide a complete bending strain profile, requiring no prior knowledge of the estimated shear-plane orientation. Minimum displacements occur in roof bolts installed perpendicular to rather than at an angle to the shear planes.RÉSUMÉ Les boulons d’ancrage dans le toit d’une mine sont sujets à des contraintes axiales, des contraintes de cisaillement ou les deux. On a comparé les contraintes axiales et de cisaillement de boulons d’ancrage usinés avec deux ou trois fentes. Les contraintes de cisaillement perpendiculaires et à angle aux plans de cisaillement ont été évaluées en analysant un boulon d’ancrage de toit à trois fentes, en effectuant des essais en laboratoire sur des boulons d’ancrage de toit à deux et à trois fentes et en effectuant des analyses de tests in situ. Les boulons à trois fentes semblent fournir un profil complet de résistance aux contraintes de flexion, sans avoir besoin de connaître l’orientation estimée du plan de cisaillement. Des déplacements minimums ont lieu dans les boulons d’ancrage de toit installés perpendiculairement, plutôt qu’à un angle, aux plans de cisaillement."

Jan 1, 2016

By L. H. Chen, Y. C. Chen, Leo Benyamin, W. C. Chen

"To investigate the evolution of fluid-driven fracture of rock-like material subjected to borehole fluid pressure and its consequential damage with regard to post-peak stabilization, micro-seismic activities have been monitored using nondestructive technique of acoustic emission (AE) corresponding to the macro-scale complete history of loading curve by setting the hollow cylindrical external circumferential strain to be a closed-loop feedback signal during servo-fluid-driven tests. Development of a novel fluidinduced loading system injected from internal borehole as well as monitoring system were equipped such that the initiation and propagation of micro-cracks enable to analyze experimentally. By programming/controlling either injection rate or fluid pressure, synthetic sandstones with low-permeability made by cement mortar were conducted in this study. It found that both the growth of macro-crack initialized intensively as reaching the breakdown pressure and the micro-seismic activities represented by AE locations show nice agreement. The experimental results in this paper provide better understandings of fluid-driven fracture mechanism.INTRODUCTIONFluid-driven fracture is a process of generating cracks by injecting viscous fluid into solid material. Conventionally, fluid-driven fracture tests have been performed by mining industry to measure the in situ stress (Haimson & Fairhurst, 1969) and fluid-driven fracture has been employed by the petroleum industry to recover oil and gas. Additionally, the mechanism of crack growth or the extension of existing cracks is important to the evolution of volcanic dikes over distances of a few kilometers (Lister & Kerr, 1991; Rubin, 1995), crack propagation in dams (Bolzon & Cocchetti, 2003) and the disposal of radioactive waste (Sun, 1969)."

Jan 1, 2015