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By C. J. Coulson, G. A. McKay, A. M. Cormie

"The Leitch mine, in the Beardmore area, Thunder Bay district, Ontario, is a part of the Leitch estate. It includes a group of patented claims, staked by P. A. Leitch of Port Arthur early in the century, along bands of jasper, hematite, iron-bearing slates, carbonatized schists, and greywacke, commonly known as 'iron formation'. The folding and shearing in these variably interstratified beds is a striking structural feature. The vein pattern is very definitely related to these structures.ROCKSThe rocks in the area are typical Keewatin lavas-greenstone-overlain by a series of Timiskaming sediments consisting of arkosic greywacke, iron formation, slate, greywacke, conglomerate, and greywacke, in this order from the contact. The sedimentary beds are generally conformable with the older rock contact except on local folds.Small intrusions of diorite occur as nearly vertical dykes and are believed to be of Algoman age. To the northwest of the mine there are larger intrusions of granodiorite belonging to the same period.Several dykes of quartz diabase up to 100 feet in width, striking generally north and south, with a vertical dip, cross the property. These have been classified by W. C. Laird as pre-Keweenawan in age. One of these dykes in particular is of importance for it cuts through the No. 2 vein and serves as a pillar when stoping. It is approximately 6 feet wide.The youngest rock type represented is a sheet of olivine diabase that extends over an area of thousands of square miles in and around lake Nipigon. It underlies most of this area and its outcrops form some of the most interesting topographical features, with fault scarps rising hundreds of feet. In the vicinity of the mine shaft the sheet is about 600 feet thick and extends from a depth of 1,871 feet to approximately 2,470 feet. It has a dense, hard, chilled margin and a sharp, tight contact. It intruded the sediments with very little lateral disturbance. The chief effect was baking, which darkened and hardened the greywacke near the contact. The sheet dips flatly to the cast."

Jan 1, 1954

By Jochen Petersen, Alison Lewis, Cledwyn Mangunda

Run-off and waste water streams high in dissolved metal content are generated in all mining operations. The metals pose a threat to life due to their persistent bio-accumulative toxic (PBT) characteristics. Hence, there is a need to treat mine waste water effectively. Lime precipitation is the technology of choice through which Fe, as the major metal species, is removed as Fe (III) oxyhydroxides with other metals co-precipitated and/or adsorbed. Sulphates are removed as gypsum or incorporated into the Fe phases. The resulting sludge has poor dewatering characteristics and is deposited in landfills, with an inherent risk of returning the Fe back into the water cycle through leaching. This study seeks to understand the mechanisms behind the formation of this sludge in terms of product quality. The relationship between process conditions and product characteristics has been investigated through exploring the effect of Fe (III) concentration on the precipitate product characteristics (particle size distribution (PSD), size, morphology and structure) and quality (in terms of filterability, settling ability, etc.) in a simplified system. Neutralisation of acidic synthetic aqueous Fe (III) sulphate streams containing 50, 400 and 800 mg/L Fe(III), respectively, was effected by mixing it in a continuous stirred tank reactor (CSTR) with dissolved calcium hydroxide for pH control at a residence time of 15 minutes. Precipitate samples analysed for morphology and PSD, using nanoSEM and Zetasizer respectively, showed a general decrease in PSD and zeta potential with increases in feed Fe (III) concentration. These results were used to infer the particle size enlargement mechanisms of Fe (III) oxyhydroxide precipitates under a given set of operating conditions. Preliminary product quality results indicate that a high concentration (800 mg/L) leads to the rapid formation of metastable precursors with poor product quality, whilst a low concentration (50 mg/L) leads to formation of thermodynamically more stable precipitates with good product quality. The approach demonstrates a potential route forward in terms of linking operating conditions to the attainment of desirable characteristics rather than specific precipitate phases which are difficult to identify.

Jan 1, 2016

By W. Curlook

"A review is presented of a growing number of imperatives, some self-imposed, some imposed by society, which the mining and metals industry faces in carrying out its business. These imperatives bear on all activities from the exploration phase, through engineering, design, plant construction and operation, to decommissioning.IntroductionThe mining and metals industry must learn to cope with, i.e. manage, a growing number of imperatives. Some of these, such as the need for responsible stewardship of natural resources, the requirement to respect laws and regulations, the need to provide for safe and healthy workplaces, and the need to provide appropriate returns to investors of capital , have been with the industry for a long time (fable I). But the industry now faces additional imperatives that are growing in number and in importance (fable 2):• There is the growing concern about the impact of operations, not only on the workplace environment and the external environment, but also on the need to monitor not only the chemical concentrations in various effluents but to also monitor the effects of such emissions on the environment; i.e. there is a growing concern about the ""net"" consequences of operations.• There is the need for on-going improvement in productivity and safety to compete and survive in a global economy. The global business environment has become paramount.• There is the imperative to failsafe all designs, equipment and operational procedures, and having done that to provide for containment of unavoidable spills, and to have ready and in place systems for emergency response.• There is the need, indeed the imperative, to involve all employees in various quality improvement programs.• There is the imperative to face up to ""virtual elimination/zero emissions""; and• One must have waste management plans in place to cope with the need to reduce, reuse, and recycle; and• There is the need for decommissioning plans for all operations, for the restoration of business habitats to their original states (or better). Indeed, one must engage in the decommissioning exercise from day one, i.e. right from the time of design and commissioning."

Jan 1, 1992

"A 3-dimensional finite element model for stress/stability analysis of rock excavations in underground mines is presented. Developed for use on personal computer under OS/2 operating system, the model employs the 8-node isoparametric brick element and accounts for such loading conditions as in situ stresses and gravity loading of the rock mass. In addition, modelling of backfill in mine stopes as in situ stress-free material is incorporated. Material failure is assessed by Mohr-Coulomb or Hoek-Brown failure criterion. A mine design example is presented to illustrate the potential use of the model as a tool for stope design.IntroductionNumerical modelling of mine structures has become a vital tool for mine design in recent years. The need to maximize ore extraction ratio and to reach deeper mineral deposits underground has led the mining industry to employ numerical methods of analysis to undertake complex ground control studies in order to better understand the ground response to mining excavations and to evaluate the ground support requirements. Thanks to the rapid developments in computer technology, it is now possible to perform very comprehensive analyses including, but not limited to, 3-dimensional, elasto-plastic, or large deformation or time dependent nonlinear analyses on personal computer.During the past ten years or so, many researchers undertook 3-D finite element analyses of rock mechanics problems in mining engineering. The following is only a sample review. For example, Chan'!' used three-dimensional finite elements to study the mechanical response of jointed granite during shaft sinking at the Canadian Underground Research Laboratory. Wang et al.(2) performed 2-D and 3-D finite element analyses of room-and-pillar mining system with flat and rolling coal seams. Thatejatu used three-dimensional finite element method to examine the problem of branching tunnels. Dolezalovaw used three-dimensional finite elements for the analysis of tunnel-face advance with partial excavation as well as full-face excavation in combination with rein for cement of the face by long anchors. Peili (5) used three-dimensional finite elements for the simulation of rock-liner interaction near the tunnel face."

Jan 1, 1992

By J. B. C. Wu, B. McKee

"Mining along with subsequent processing of the minerals often presents conditions where a wear- and/or corrosion-resistant alloy is needed to minimize downtime and maximize efficiency. This paper is intended to give an overview of the alloys that are currently being used, as well as those developed in recent years that could be used in the mining industry. Emphasis will be put on the iron-, nickel-,cobalt-based alloys and composites containing a variety of carbides. The characteristics, properties, product forms, and methods of application are presented. In addition, examples of the actual use of these wear-resistant materials are illustrated.IntroductionPreventing wear and corrosion is important in any industrial operations. In the mining industry, the process equipment typically suffers many different types of material degradation. Abrasion, impact, erosion, metal-to-metal wear and corrosion are typically encountered. Each situation requires different material characteristics to retard the degradation process. Therefore, it is essential to understand the characteristics of the materials and the effects of the alloying elements.There are four common classes of metallic materials for resisting wear and corrosion; namely, iron-based alloys, nickel-based alloys, cobalt-based alloys, and carbide-containing composites. Each class of material has its own characteristics. Depending on the chemical composition, the materials within each class can be vastly different in properties. In recent years, there have been materials developed in each of the four classes using the knowledge of the metallurgical principles and the effects of the alloying elements on the material degradation process.To use a wear-resistant alloy, it is also necessary to understand the available product forms and their application methods. Weld overlaying is a traditional way of using these alloys (Wu and Redman, 1994). In recent years, thermal spray is becoming popular. For applications where over-laying and spraying are impractical, solid components can be made by a variety of casting and powder metallurgy techniques. They can also be fabricated from the wrought products.To select a proper material for an application, it is important to understand not only the characteristics of the wear-resistant materials but also the degradation process. Due to the complexity of the processing environments, past experience is also helpful in making the decision on the material selection."

Jan 1, 1997

By H. M. Howard

"The subject of Grinding Media is perhaps still quite controversial. Many people will state today that the spherical ball is the only way, and also will state that this was settled long ago others are not so sure, and I am in this second category. Over the years there have been many changes in grinding and in our evaluation of grinding media we should always be ready to review the overall situation at regular intervals. There is quite a lot of inertia in all branches of Hineral Dressing and this is particularly true of grinding or, more correctly, comminution.In order to understand some of the things which are done today, and to understand some of the thinking on grinding, it is desirable to go back some sixty years and trace the developments in comminution. In doing this we should consider perhaps three general categories with respect to daily tonnage. An arbitrary division would be under 500 T.P.D., 500-5000 T.P.D., and large operations which might have several parallel units, each with a capacity of about 5000 T.P.D. For the future, in the broad picture, this last category will be the important one because we will be more and more dependent on large-tonnage low-grade operations for most of the metals of the future. Some such division is necessary because the daily tonnage will have a very great effect on what we can and cannot do. It is also necessary to consider the entire flowsheet, and to remember in particular that grinding is not merely to make small particles but is also a conditioning process, to prepare the materi.al for the process which follows. The relationship of crushing to grinding must also be considered. It is logical to include the liners as part of the grinding media and we should try to distinguish between the wear of grinding media and the consumption of media by corrosion. Finally, the whole question of grinding media should be examined in relation to the possibilities of using some form of autogenous grinding."

Jan 1, 1970

By Laxman M. Amaratunga

"The fine fraction of tailings is usually excluded from the backfill process and generally disposed on the surface in tailings ponds. Because of the ever increasing demand for fine grinding in the extraction process for improved liberation of valuables in the ore, increased production of fines in the tailings has resulted. The negative impact of surface impoundment of tailings on the environment is well known. Amaratunga and Annor (1989) first presented a concept of fine tailings agglomeration for backfill.This paper presents the development of the novel cold-bond tailings agglomeration (CBTA) technology for non-reactive fine gold mill tailings. For cold-bond agglomeration regular portland cement was used as a binder. In order to cut costs, alternate binders such as lime, and blast furnace slag cement were examined. The effects of binder dosage, curing time, and agglomerate size on the fracture load strength of the agglomerate were studied.Fine tailings agglomerates are mixed with coarse tailings or non-agglomerated fine tailings to make high density fill compositions to be used as underground backfill. Alternatively, the agglomerates can be used as aggregates for surface applications. The paper discusses the environmental and operational benefits of this total tailings utilization and disposal technology.IntroductionIn Canadian mines, mill tailings are probably the most commonly used material for backfill. However, only the coarse fraction of tailings is desirable for use as hydraulic fill or high density fills. The fines are disposed on the surface in tailings ponds since they are unsuitable for underground backfilling owing to the following factors:i) slow settling ratesii) longer percolation timeiii) excessive consumption of binder due to drainageiv) poor compactionFor improved value liberation more milling operations have resolved to fine grinding in their comminution circuits. Gold milling operations driven by down stream leaching processes grind their ores excessively fine. In general, gold mines use hardly any tailings for backfilling. This can result in periodic short falls and the need to search for alternate backfill material from other sources. Apparently, the gold producers are the most identifiable sector which suffer from a shortage of backfill materials ( Amaratunga and Annor, 1989)."

Jan 1, 1994

By F. Goodarzi

"The nature and distribution of the inorganic components and the concentration of certain environmentally sensitive elements, such as, As, Sb, B, Hr, Cd, CI, F, Mo, Pb, S, and Se, or elements detrimental to the utilization by industry such as B, Na, P and S are very important in determining coal quality. The concentration of elements in coal is controlled by the following factors: (1) frequency of occurrence of partings; (2) nature and habit of occurrence of minerals in coal; (3) environment of coal deposition; (4)rank; (5) geological setting; and (6) weathering.Selective mining of coal can reduce the input of undesirable elements such as As and S by eliminating the part of the seam which is enriched in these elements. IntroductionCoal is a sedimentary rock of plant origin and consists of two components: an inorganic component (minerals) which is formed by influx of clastic sediments into the coal-forming environment and also by activities of groundwater, and an organic component (macerals) which is formed from plant debris deposited in the original coal-forming environment. However, coal is a generic term with a broad range of utilization characteristics. A coal that is attractive for use in one market - such as generation of electricity (combustion) - may not necessarily be acceptable for use in another, such as for production of coke (Davis, 1978).The elements in coal are associated with both macerals and minerals. The elements associated with coal macerals, such as C, H and N are termed elements with organic affInities. The concentration of elements with organic affmities (including B, Br, CI, F, I, S, and Mg) often decrease with increasing ash content of coal (Nicholls, 1968; and Finkehnan,1982). FIgure 1 shows such a trend for chlorine. Some of these elements may also be incorporated in coal maceral as very fine mineral grains (Finkelman, 1982). The elements with organic affmities are often volatilized during combustion and carbonization of coal and emitted in the vapour phase. Emission of some of these elements (C, 0, Br, N and S) is of major environmental concern (Lim, 1979)."

Jan 1, 1994

By Pura Alfonso, Sarbast Hamid, Hernan Anticoi, Eduard Guasch, Josep Oliva

"Av. Bases de Manresa 61-63, Manresa (08242) Barcelona, SpainTantalum is a strategic metal and an improvement of the mineral processing is an important issue. The main objective of this work is to optimize the grinding technologies for tantalum ores with high pressure grinding rolls. The selected ore for this study was an altered leucogranite from the Penouta Open Pit Mine (NW Spain). In the present work mono-size experiments have been carried out using grinding rolls with controlled pressure. The particle size distribution has been monitored in the input and output of the high pressure grinding rolls for each experiment. The cylinder pressure that is transmitted to the particles has been determined. New population balance models are presented for high pressure grinding rolls with parameter adjust for tantalum ore. The obtained model uses the physical description of particles under the comminution action of the grinding rolls. The obtained results are in agreement with other models and the errors in the adjustment are low. The selection function proposed for this model describes adequately the breakage probability of the particles inside the high pressure grinding rolls. The presented model can be a good alternative for simulating a high pressure grinding roll process. INTRODUCTIONTechnology for grinding have been improved for many years, introducing new variables and parameters involving energy consumption, mechanical stress analysis of the compression particles or pressure application for optimizing the comminution (Morrell et al, 1997). High pressure grinding rolls is a modern technology that is proven to reduce the operating costs in full scale plants when compared with other milling technologies. Its benefits on energy saving and simplicity in the process have been studied and applied, first in the cement clinker industry (Abouzeid & Fuerstenau, 2009) and after in mining activities, especially in metallic ore deposits (Austin et al, 1991; Guevara & Menacho, 1992; Morrel et al, 1997; Torres & Casali 2009; Numbi & Xia, 2015). Many author structures of the High Pressure Grinding Rolls modelling in three main branches; (a) throughput modelling, (b) Power and energy model and (c) particle size distribution modelling (Austin et al, 1991; Guevara & Menacho, 1992; Austin & Trubelja, 1994; Morrel et al, 1997; Torres & Casali, 2009)."

Jan 1, 2016

By G. K. Rutherford, G. W. Van Loon

"Tailings in the mining and smelting industry are reject products of the refining process which are deemed too deficient in native are to warrant smelting. They are essentially finely ground rock materials which have been moved by alluvial suspension from the site of crushing to a deposit site. It is realized that components of flotation chemicals used in specific gravity separation may become part of the tailings and also that sewage sludge or other materials may be added at some stage to the tailing deposits.It would seem, then, that as tailings have a similar parent material to soils, namely rocks, and that they have also been comminuted to similar size fractions, they would react in similar ways to soils. There is an increasing body of evidence and experience which both supports and negates this supposition. It is the object of this paper to point out similarities and contrasts between these two materials which may influence the vegetation and rehabilitation of tailings.Soil-Formlnq FactorsThere are considered to be six soil-forming factors which impart the particular and unique properties harboured by a soil at any site. It is .relevant to consider each of these in turn, as each provides an historically based parameter with which to judge tailing properties.Parent MaterialsAlthough all mineral soils have originally come from rocks, for most soils the route has been rather circuitous. Soils may be formed directly from underlying rocks, as in some parts of tropical and semitropical regions today; these are sedentary soils. However, most soils of the world have been formed by materials which were transported to their present site by ice, water or wind, or as volcanic ash. Virtually all soils in Canada have been transported by ice or water and deposited on an extraneous rock surface during the last glacial retreat. Ice-deposited materials are extraordinarily heterogeneous in their size components and may range from very bouldery and gravelly to predominantly clay-sized materials. Water deposited sediments are usually homogeneous, but nevertheless these also show considerable level variations. In many parts of Canada, clay-sized materials deposited in ephemeral post-glacial lakes form the parent material for soils."

Jan 1, 1982

By Gene O. Cowie

"Zinc, which once enjoyed an unchallenged position in the field of decorative applications, has lost a substantial share of its markets to other materials, particularly plastics. This turn of events has led the zinc industry to explore new market areas, particularly those applications where the engineering properties of zinc can be utilized. This paper gives an overview of the zinc industry's efforts to develop the data base and product development technology which have enabled zinc alloys to emerge as engineering materials. It also indicates those areas in which the research facilities of the zinc industry must be employed to ensure that zinc alloys keep pace with developments in competitive materials and processes.The Materials RevolutionThe development and utilization of new materials and manufacturing processes progressed for centuries by evolution. Recently it erupted into a revolution, which may become as significant as the industrial revolution. The materials revolution has impacted upon many industries, but none has been affected more traumatically than the North American automotive industry. The plight of that industry is of great importance to us because their problems have, to a great degree, become problems to the zinc industry.Much of the impetus behind the automotive trauma came from the battery of motor vehicle regulations promulgated by the United States government in the 1970s. These regulations required that the efficiency of passenger cars, in terms of miles per gallon, be approximately doubled in ten years. In view of the fact that major changes in the automotive world require three years of lead time to implement, the industry was left with only seven years to perform the task. The automotive industry was simultaneously required to make progress in other areas, such as reduced emissions, reduced cost of repairs and increased levels of occupant safety. These added demands not only diverted some of the available resources away from efficiency goals, they often ran in direct conflict. For example, when you are required to provide a front bumper which will absorb the energy of a 5-mile -per-hour barrier collision, you must add both hardware and structure to the vehicle. This adds weight, and increased weight reduces miles per gallon."

Jan 1, 1983

By D. Madsen, B. Salamondra, A. Moss, D. Etienne

"Raise mining at the Namew Lake Nickel Mine in Manitoba uses 3 m diameter bored raises driven at 45 to 50 degrees dip for stope access and drilling. These raises are developed within the orebody on 20 m centres to accommodate electric-hydraulic longhole jumbos and charging wagons. Critical elements of stope development include delineation of are contacts, control of deviation during raise development, optimal stope sequencing to permit a high extraction rate, drill anchorage installation, production drilling and blasting, and ground control. Procedures to deal with these elements are described, with emphasis on the geotechnical investigation for design of open stopes and pillars.Although mining with drilled raises does not have the flexibility to follow large variations in orebody dip, results to date indicate that it can be used successfully in the thicker ore zones. Thinner zones are currently mined using a modified Avoca method. Some flexibility to accommodate variations in orebody dip in thin are zones may be obtained by using alimack raise climbers to drive access raises, and carry longhole drills and charging equipment. Rock quality has been sufficiently good to maintain stable stope walls for full-height mining of primary stapes at 20 m strike length.IntroductionThe Namew nickel deposit is located 60 km south of Flin Flon, Manitoba. It is a moderately dipping (45 to 50 degrees) pipe-like ultramafic intrusion with a sulphide halo enrichment. The diluted recoverable ore reserves at January I, 1990 are 2.2 million tonnes grading 2.05% Ni and 0.7% Cu. The operation is a joint venture between Hudson Bay Mining and Smelting (60%) and Outokornpu Mines Ltd. of Toronto (40%). The mine is budgeted to produce 530 000 tonnes in 1990. The deposit was discovered in 1984 and mine development commenced in 1987.In the raise mining area, primary stopes will be filled with a high quality backfill consisting of cement and quarried limestone. Secondary stopes will be mined out between the primaries in the second pass of mining. The design extraction rate is 94% over all.The orebody above 120 level has an average mining width of 2.4 m, so is too narrow for raise mining. A modified form of Avoca stoping is used."

Jan 1, 1991

By L. A. Clark, G. H. R. Burrill

"Most unconformity-type uranium deposits in Saskatchewan occur within a few tens of metres above and/or below the basal unconformity of the 1,45-b.y. Athabasca Sandstone. Graphitic basement rocks coincident with post-Athabasca faulting or brecciation at or near the unconformity are important in localizing uranium deposits which form as tabular, ribbon-like bodies with grades averaging over 2 per cent uranium and containing up to 50,000 tonnes UJOs. Some of these deposits have similar contents of nickel and arsenic.In the genetic model proposed to explain these deposits, traces of uranium were leached from the sandstone and weathered basement rocks by oxidized formation waters sweeping through the sandstone and along brecciated faults. Over basement meta-petites, a thick clay regolith adsorbed uranium from the solution. Thus fixed, the uranium was reduced through an indirect reaction with graphite, possibly involving methane. The clay mineral surfaces were thus continuously cleared to allow further adsorption. Basement faults localized along weak graphitic units were re-activated, offsetting the sandstone formation, probably at the time of an early uranium deposition about 1.2 b.y. ago, and served as vents for spent ore solutions. Fluid convection was induced by topographic relief and/or crustal heating from radioactive decay in basement plutons or mantled Archean domes with uranium and/or thorium contents a few ppm above those of adjacent rocks. Heat from radioactive decay within the incipient uranium deposit would develop in about a million years. The self-generating convection cell would continue uranium deposition until all permeability was plugged by minerals. In some instances, convection was re-initiated after subsequent faulting and brecciation. While some deposits were further enriched, heavy flows of oxidized fluids re-dissolved and partially depleted other uranium deposits.The East Alligator Rivers uranium deposits in Northern Territory, Australia, occur within Middle Proterozoic quartzchlorite and quartz-muscovite schists overlain by sandstone. Highest grades occur in silicified breccias where carbonate beds were leached out. Mineralization ages are both pre- and post-Kombolgie Sandstone, but, to date, no significant uranium mineralization has been encountered in the sandstone. There are many general similarities with Saskatchewan deposits, but important differences in detail."

Jan 1, 1981

By N. Birbilis, S. Kairy, C. R. Hutchinson, D. Jiang, D. R. Feenstra, O. Gharbi

"Recent developments in metal-based additive manufacturing (AM) technology have generated considerable interest in multiple industries, owing to flexibility in design and the ability to produce final components in their net shape. The AM of high-strength aluminium alloys has not been widely explored, due to findings of undesirable microstructures leading to short fatigue life and poor fracture toughness; restricting the application of AM to lower strength aluminium alloys (with cast-like Al-alloy compositions) to date. Herein, aluminium alloy AA2024 (Al-3.6Cu-1.2Mg) was additively manufactured via selective laser melting (SLM), with the resultant microstructures and corrosion properties characterised and compared to wrought AA2024-T3. Microstructural characterisation was carried out using transmission electron microscopy (TEM), revealing SLM produced AA2024 included a population of ?-phase (Al2Cu) in preference to S-phase (Al2CuMg) typical of wrought AA2024. Additionally, the corrosion properties were investigated by potentiodynamic polarisation in a range of NaCl concentrations, whilst elemental corrosion rates were also determined (including for open circuit exposure conditions) and quantified in situ with an inductively coupled plasma mass spectrometer coupled with an electrochemical flow cell. Results revealed a significant improvement in the corrosion resistance, and elemental dissolution of AM prepared 2024 relative to wrought AA2024-T3.INTRODUCTION Aluminium alloys remain the preferred candidate materials in applications requiring a balance of low density and strength. The ability to produce net shape components from aluminium alloys has accelerated due to recent developments in metal-based additive manufacturing (AM) technology, including selective laser melting (SLM) and powder bed 3D printing. The AM of Al-alloys, including Al-Si-Mg (namely AlSi10Mg), has become widespread commercially in recent years. Alloys including AlSi10Mg offer reliable and reproducible production by AM, however such alloys (and variants thereof) are not high strength alloys. The pursuit of higher strength AM Al-alloys presents significant merit to multiple industries; however, such higher strength AM Al-alloys have not been widely studied to date. The solidification of high strength Al-alloys during conventional (casting) operations needs to be executed in a manner that avoids so-called =hot-tearing‘, which can arise as a result of the solute type and loading. A report on the solidification of a high strength Al-alloy prepared by AM, along with factors related to solidification, was recently covered by Pollock and co-workers (Martin et al., 2017). It was reported that AM of high-strength aluminium alloys (which have to date been principally based on the compositions of wrought high strength Al-alloys) may lead to undesirable microstructures that reduce fatigue life and result in poor fracture toughness; presently limiting the application of AM to lower strength aluminium alloys (with cast-like Al-alloy compositions) to date."

Jan 1, 2018

By E. Vesely, A. Saxena

"SAG mill liners are designed for protecting the mill shell and providing lifting power for ore charge and grinding media. Due to the impacts from the charge and the grinding media, the liner experiences dimple, plastic deformation, strain hardening, fatigue, peening and final failure. Because of the collisional environment directly measuring such dynamical loads is extremely difficult if not impossible. In this study we tried to evaluate the liner failure risk by simulating the collisions of solid particles with mill liner using Discrete Element Method (DEM). DEM simulation has been proved to be a very useful tool in evaluation of granular flow and its impacts on the solid structure. But there are certain limits in DEM coherently, such as the number of solid elements, the computer runtime, etc. Here we first present the general feature of the particle-liner collision in terms of impact force and collision energy. Then the effects of parameter selection is discussed. Our simulations show the fatal collisional event of huge impact force is very rare and the collisional events of low impact is much more frequent. The fatal event may contribute most to the liner failure. The rarity of the fatal events may be missed in a short runtime simulation. This technical challenge combined with lacking of criterion to evaluate varying impact loads in fatigue problems may further complicate the evaluation. Should we use the largest impact force alone or we should use the more frequent events is an open question and requires more effort. In order to evaluate the quality of liner design, we proposed a relative comparison method. In the end we show the implication and application of this method in liner optimization by a work example. In particular, the effects of the charge level of grinding balls and their size on the operation performance is presented.INTRODUCTION Grinding is one of the most important and expensive steps of mineral processing. A variety of grinding mills such as rod mills, ball mills, semi-autogenous (SAG) mills and autogenous (AG) mills are being utilized for comminution of mineral ores (Gupta & Yan, 2016). Up to today, SAG mills and AG mills have been widely used to reduce operation costs and increase throughput. In an AG mill, a rotating drum throws larger rocks of ore in a cascading motion which causes impact breakage of larger rocks and compressive grinding of finer particles. Unlike AG mills, SAG mills use steel grinding balls to break ores of size quite small such that they cannot be easily broken in AG mill. SAG mill liners are designed for protecting the mill shell and providing lifting power for ore charge and grinding media. Due to the impacts from the charge and the grinding media, the liner experiences dimple, plastic deformation, strain hardening, fatigue, peening and final failure. Quality and performance of SAG mill liners play a fundamental role to enhance efficiency of grinding mills, because failure of liners is the major cause for unexpected breakdown (Banisi, Hadizadeh, Mahmoudabadi, & Eilkhany, 2006)."

Jan 1, 2019

By Q. Li

"The precursor of In2O3 was prepared by hydrolysis precipitation/hydrothermal method using In(NO3)3 solution as the feed material and ammonium hydroxide as the neutralizing agent. The crystallinity, morphology and particle size of the products were characterized by SEM, XRD, BET and LPSA. The results showed that the hydrolysis product consists of an aggregate of cubic In(OH)3 particles with a short rod morphology. In the hydrothermal process, the structure, morphology and size of the particles changes through the mechanisms of Ostwald ripening and phase transition, respectively. When the hydrothermal temperature was less than 280 ?, the Ostwald ripening process took place, which changed the morphology of the particles from short rods to cuboids through dissolution-recrystallization. When the hydrothermal temperature was higher than 280 ?, the processes of Ostwald ripening and phase transition took place successively. Firstly, the morphology of the particles changed from short rods to cuboids through Ostwald ripening, and then, the phase transition from cubic In(OH)3 to orthorhombic InOOH occurred and the morphology of the particles changed from cuboids to polyhedron. INTRODUCTIONDue to its excellent electrical conductivity and optical transparency, indium tin oxide (ITO) film has been wildly used in flat-panel display, solar cell, antistatic coating and EMI shielding (Medvedovski et al., 2008). Indium oxide powder is one of the fundamental materials for preparing ITO film. Along with the development of ITO targets of both high density and large size, high quality indium oxide powders, such as single phase, nano-size, spherical morphology and mono-disperse, have been in high demand (Nakashima and Kumahara, 2002; Betz et al., 2006; Kim et al., 2007). The main preparation methods for indium tin oxide or indium oxide powders include chemical precipitation (Nam et al., 2001; Xu and Yu, 2007), melt atomizing-combustion (Chen et al., 2000) and spray pyrolysis (Ogi et al., 2009). Among them, chemical precipitation has been preferred, since it is simple, easy to control and suitable for industrial scale-up. In chemical precipitation method, indium oxide powders were prepared through the following steps: firstly, indium hydrate precursor was precipitated from an indium salt solution by neutralization using an alkali, such as ammonia; and then, indium oxide (In2O3) powders can be obtained from the precursor through calcination (Li et al., 2006), or solvothermal method (Lee and Choi, 2005), or hydrothermal processing/roasting (Xu et al., 2005; Chen and Li, 2007), respectively. However, the indium oxide powders obtained by direct roasting are polycrystalline, dispersable with a wide size distribution (Liao, 2006). The disadvantages of the solvothermal method are high cost, complicated after-treatment processes, as well as bad performances of the powders (Udawatte and Yanagisawa, 2000). Therefore, among three methods of obtaining indium oxide from the hydrolysis precursor, the hydrothermal process/roasting method is the most feasible to synthesize high quality In2O3 powder with uniform crystallinity and size (Kim et al., 2002; Zhu et al., 2004; Xu et al., 2005; Xu et al., 2005; Chen and Li, 2007; Seetha et al., 2009). However, current research on hydrothermal process-roasting method has been limited to the synthesis of a certain ITO or In2O3 powders under specific conditions. A systematic study on the phase transition, as well as the change of the morphology and size of the particles in the hydrothermal process is still missing. In this paper, the effects of hydrothermal processing on the mineralogy, morphology and size of products were investigated. The results showed that the evolution of crystal structure, morphology and size in the hydrothermal process was affected through the mechanisms of Ostwald ripening and phase transition successively. These results are novel and have guidance for improving the hydrothermal process for In2O3"

Jan 1, 2012

By Norm Clegg

The Plant Engineering and Maintenance Association of Canada PEMAC is a national, not-for-profit industry association for plant and facility maintenance, engineering and physical asset management in all industry sectors in Canada. Our mission is to provide professional development for our members and the profession in Canada

Feb 1, 2008

By Jeffrey Oke D.S.H. Oke, Craig J. Archibald, Anna P. Perry

Underground mining at the Diavik Diamond Mine (Northwest Territories, Canada) commenced in 2003 and has targeted four kimberlite pipe orebodies. The A154 North (A154N) pipe was mined using longhole open stoping with cemented and uncemented rock fill. During the later stages of mining, unique geotechnical challenges developed in the upper portion of the orebody, resulting in difficult ground conditions during secondary stoping. The two uppermost stoping horizons in A154N (A- and B-blocks) were located within the widest portion of the kimberlite pipe and were mined using a multi-panel retreat, overhand primary–secondary extraction sequence. Primary stopes were commonly advanced to near the top of each block prior to the initiation of secondary stoping. Ore development was excavated to full stope width, and secondary development initiated at the base of the block adjacent to mined-out primary stopes resulted in the formation of tall, slender hanging pendant pillars—locally up to 100 m high—laterally supported by frictional contact with adjacent cemented rockfill pillars. Beginning in 2015, differential vertical movements across the ore-waste contact of A154N pendant stope pillars were identified, and the extent and rates of movements increased significantly as secondary stoping progressed through to 2025. These conditions created significant challenges for the safe extraction of remaining stopes and raised concerns for deeper mining blocks if similar methods were maintained. This case study describes the factors contributing to the observed ground behaviour and outlines the strategic mine design modifications and tactical risk mitigation measures implemented to manage geotechnical risk in the remaining A- and B-blocks and to prevent recurrence in lower A154N mining horizons.

May 2, 2026

By J. M. Hong, H. K. Zheng, R. Hu, C. B. Zhou

The Jinping-I double curvature arch dam, located in the middle reach of the Yalong River and with a maximum height of 305 m, is the world highest dam of the same type that has been completed. Since the second and third periods of the reservoir impounding, after which the reservoir water level was raised by about 200 m, a significant amount of leakage was observed out of the drainage holes deployed in the lowest drainage tunnel at the left-bank abutment at EL. 1595 m, with a pressure of 0.3 MPa at one typical hole when it was blocked. In this study, a number of analyses including water quality analysis, digital borehole imaging, tunnel geological mapping and in-situ groundwater monitoring were performed to investigate the source of leaking, the leakage passages and the performance of the grouting curtains. An inverse modeling procedure combining the orthogonal design, finite element forward modeling of the transient seepage flow, artificial neural network and genetic algorithm was invoked to further evaluate the permeability of the foundation rocks whose permeability was underestimated in design, using the in-situ measurements of flow rate and piezometric head. The geological structures that lead to the leakage were identified and the seepage flow behaviors in the dam foundation and the left bank abutment were assessed. Given the connectivity nature of the sub-vertically oriented fractures that induce the leakage event, it is found that some of the drainage holes with relative larger amount of discharge could be closed or blocked for reducing the amount of leakage without remarkably increasing the pore water pressure in the foundation rocks.

Jan 1, 2015

By Qian Liu

Mining in highly stressed ground conditions has been an increasing challenge at the Brunswick Mine. Two large regional pillars were established on the 1000 m Level to support the ground for safe extraction of the surrounding ore. The South Regional Pillar contains about 5 million tonnes of ore and the North Regional Pillar has about 3 million tonnes of ore. In the fall of 2000, mining activities were suspended following a series of ground movements around the South Regional Pillar along weak geological structures. After extensive geotechnical investigations, a decision was made to carry out a mass destress blast in the West Ore Zone (WOZ) to cut the principal stress across an area of 135 m along strike and 86 m high. At the end of July 2001, the WOZ mass blast was successfully initiated. Following this success the mine decided to take a similar approach to destressing the North Regional Pillar (NRP). The final mass blast was taken in early February 2003. Advanced blasting technologies, including state of the art electronic detonators and blast simulation, played an important role in achieving the successful blasts. The high precision of delay timing and long delay duration of the electronic detonators ensured accurate and reliable initiations of over 800 blastholes in the WOZ mass blast. Orica?s DMC_Blast (Distinct Motion Code) simulation code was used to study different blasting blocks for the desired timing in the initiation sequence. This paper describes the process of applying electronic detonators in complex blasts, and discusses how blast simulation results were interpreted to guide engineering design of the mass blasts.

May 1, 2003