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By R. Chen, K. Xia

In deep mining activities, blasting induced compressive stress wave would be reflected as tensile wave at a free surface around the openings, which would facilitate the tensile failure of the deep rock since it is much weaker in tension than in compression. It is thus critical to understand the dynamic tensile failure of rocks subjected to static tension for deep rock engineering applications. A modified split Hopkinson pressure bar (SHPB) system is adopted to load Brazilian disc (BD) samples statically, and then exert dynamic load to the sample through stress wave generated by impact. The pulse shaper technique is used to generate a slowly rising stress wave and thus to facilitate the stress equilibrium of samples during each test. Five groups of Laurentian granite (with tensile strength of 12.8 MPa) BD samples under the pretension stress of 0 MPa, 2 MPa, 4 MPa, 8 MPa, and 10 MPa are tested under different loading rates. The result shows that the dynamic tensile strength of the rock decreases with the increase of pre-tension stress, which is easy to understand because pre-tension stress weakens the rock sample. It is also observed that under the same pre-tension stress, the dynamic tensile strength increases with the loading rate, revealing the so-called rate dependency that is common for engineering materials. Furthermore, it is found that the loading rate sensitivity of the rock increases with the increase of pre-tension stress. A qualitative explanation for this phenomenon is that more microcracks are generated and activated under higher pretension stress, resulting in a more viscous material. Based on the results, an empirical equation is proposed to fit the data and explain the dynamic tensile behaviour of rock under pre-tension stress. A physical model is used to simulate the dependency of the dynamic tensile strength of rock on the pre-tension stress and the loading rate, which is shown to be in good agreement with the experimental results.

Jan 1, 2015

By G. Avramovic-Cingara, H. J. McQueen

The microstructure of commercially pure aluminum was investigated by using polarized optical microscopy (POM), orientation imaging microscopy (OIM), and transmission electron microscopy (TEM) techniques. Specimens were deformed in torsion at 400°C and equivalent strain rate of 0.1 s-1, to various strains of 0.2, 0.5, 1, 4, and 6. The results indicate that POM can usefully reveal grain and subgrain structures over a large field in aluminum. TEM is most suitable to study dislocation substructure and evolution of subgrains. While TEM microscopy and OIM are capable of resolving individual subgrains, OIM can not reliably distinguish subgrains with small misorientations, particularly in samples with low strain. On the other hand, the OIM technique is very useful in the analysis of many regions surrounded by high, medium, and low angle boundaries (HAB, MAB, LAB). Various misorientation maps were studied using different data processing methods. The analysis revealed that the subgrain size is relatively insensitive to strain. The fraction of low LAB ( < 5°) decreased and HAB (>15°) increased conversely with increasing strain, whereas MAB (5-15°) remained stable. The development of an increasingly bimodal grain boundary misorientation distribution is consistent with the predominance of dynamic recovery (DRV) in the evolution of microstructure, combined with geometrical dynamic recrystallization (gDRX), now called grain-refining DRV.

Jan 1, 2006

By Carlos Palacios M., Brian K. Townley

"Abstract - The mainland Aysén region of Chilean Patagonia (44°15&apos; - 47°30&apos;S) is a representative segment of the South American active continental margin, distinct with respect to northern and central Chile. Mineralization consists mainly of polymetallic deposits, with important Zn-Pb mines and more recently discovered Au-Ag deposits, unlike the central Andes, which are dominated by Cu mineralization. On a regional scale, rocks may be grouped in four main map units: 1) the Paleozoic metamorphic basement; 2) upper Jurassic-Cretaceous calc-alkaline volcanic and marine sedimentary rocks; 3) the Patagonian batholith, and 4) upper Cretaceous to Miocene basalts and marine and continental sedimentary rocks. The upper Jurassic-Cretaceous rocks and the Patagonian batholith formed in a volcanic arc and back-arc setting superimposed on the Paleozoic metamorphic basement.Based on geographic location and geologic and tectonic setting, ore deposits in this region are assigned to three groups, from south to north: El Faldeo, Fachinal, and El Toqui. The El Faldeo group (south of 47°05&apos;S) includes upper Jurassic Zn-Pb skarn and associated polymetallic massive sulfide vein deposits locally overprinted by Au-rich epithermal mineralization, hosted by volcanic and sedimentary rocks and/or by rocks of the metamorphic basement. The Fachinal group (46°05&apos; - 47°05&apos;S) consists of volcanic-hosted lower Cretaceous Au-Ag epithermal deposits, except for the Mina Silva and Manto Rosillo deposits, which are metamorphic basement-hosted Zn-Pb skarns. The El Toqui group (44°30&apos; - 46°05&apos;S) comprises lower Cretaceous Au-rich Zn-Pb skarns and associated polymetallic veins, as well as Au-Ag-rich epithermal deposits, hosted by volcanic, intrusive, and marine sedimentary rocks. Galena lead isotopic signatures for each deposit group indicate a decreasingly radiogenic trend from south to north, suggesting different lead sources or differences among underlying crust. Three metallogenic provinces and two metallogenic epochs are proposed for the Aysén region: the El Faldeo metallogenic province of Late Jurassic age; and the Fachinal and El Toqui provinces of Early Cretaceous age. Résumé - La partie continentale de la région d’Aysen (Patagonie chilienne, 44°15&apos; - 47°30&apos;S), est unsegment représentatif de la marge continentale active d’Amérique du sud, différent des segments du nordet du centre du Chili. La minéralisation, qui consiste essentiellement en des dépôts polymétalliques, avec d’importantes mines de Pb-Zn, et des dépôts d’Au-Ag récemment découverts, différe de celle des Andes centrales où domine la minéralisation cuprifère. A l’échelle régionale, les roches peuvent être regroupées en quatre unités cartographiques principales : 1) le socle métamorphique paléozoïque, 2) les roches volcaniques calco-alcalines et les sédiments marins du Jurassique supérieur-Crétacé, 3) le batholite patagonien, et 4) les sédiments marins et continentaux ainsi que les basaltes du Crétacé supérieur-Miocène. Les roches du Jurassique supérieur-Crétacé et le batholite patagonien, formés dans un contexte d’arc volcanique et d’arrière-arc se superposent au socle métamorphique paléozoïque.Fondé sur la localisation géographique ainsi que sur le cadre tectonique et géologique, les dépôts de minerais de cette région se répartissent en trois groupes, du sud au nord, El Faldeo, Fachinal et El Toqui. Le Groupe El Faldeo (sud de 47°05&apos;S) contient des skarns à Pb-Zn du Jurassique supérieur associés à des veines de sulfures massifs polymétalliques, localement recoupées par des minéralisations épithermales, riches en Au, et contenus dans des roches sédimentaires et volcaniques et/ou dans des roches du socle métamorphique. Le Groupe Fachinal (46°05&apos; - 47°05&apos;S) consiste en des dépôts épithermaux Au-Ag, se trouvant dans des roches volcaniques du Crétacé inférieur, excepté pour les dépôts de la Mine Silva et Manto Rosillo, où des skarns à Pb-Zn, se trouvent dans le socle métamorphique. Le Groupe El"

Jan 1, 1999

By J. Lu, D. B. Dreisinger, G. Houlachi

"Zinc metal is primarily produced by electrowinning from sulfate solution. Zinc electrowinning is very sensitive to impurities such as Co and Ni. These impurities have to be removed to produce high-quality zinc and maintain a high zinc current efficiency. Zinc dusts are used to remove these impurities by cementation. However cobalt cementation is extremely slow and it is typically activated by the addition of Cu and Sb. Even with the use of Cu-Sb activation, cobalt is still difficult to remove. The zinc dust used for cobalt cementation is negligible compared to that consumed for hydrogen evolution. In some plants up to 6-7% of electrolytic zinc is used for cementation. This is a great waste of energy. Cu-Sb activation is not well understood. The objective of this study was to further understand the Cu-Sb activation and then find a way to reduce hydrogen evolution and promote cobalt cementation. The investigation reveals how hydrogen evolution (or zinc dissolution) and cobalt cementation and re-dissolution change with temperature, zinc dust dosage, the concentrations of copper and antimony and time. In the Cu-Sb activation, copper is deposited on a zinc particle to produce a porous shell. The zinc particle as an anode dissolves while the shell as a cathode provides a place where cobalt cementation and hydrogen evolution occur and they are catalyzed by antimony. A certain level of antimony (around 0.1 mg/L) is a key to maintain the catalytic effect of the shell. At a higher antimony concentration, cobalt cementation is accelerated slightly while hydrogen evolution is increased greatly. When a zinc particle dissolves to a certain degree, cobalt loses its cathodic protection and starts to re-dissolve. The change in cobalt concentration is determined by the rates of cobalt cementation and re-dissolution. The operation conditions can be optimized to maximize the cobalt removal and minimize the zinc dust dosage.INTRODUCTIONMost of the world’s zinc metal is produced by electrowinning from sulfate media. Many impurities such as iron, copper, cobalt and nickel are co-extracted into solution with zinc. Iron, mercury, indium, lead and tin are removed by co-precipitation as hydroxides. Copper, nickel, cobalt, aluminum, arsenic and germanium are partially co-precipitated with iron while cadmium, magnesium and chloride remain in solution. Cobalt, copper, cadmium, nickel and etc. are subsequently removed by cementation with zinc dust to achieve an acceptable current efficiency and high purity metal product for the economical production of zinc. Zinc provides a strong thermodynamic driving force for the cobalt cementation:"

Jan 1, 2016

"Since World War II, urban communities have expanded at an unprecedented rate. The industrial mineral industry supplies the sand, grave], limestone, crushed rock, cement, gyp-sum, etc. for urbanization. Most de-posits in use are close to or within communities. Pollution of water and air has become a matter of public concern. Waste disposal and the effects of noise and vibration are subjects of public debate. Need for the reclamation of land after operations such as strip mining is discussed in magazine articles and on TV pro-grams; i.e., the general public is educated in the unattractive features of mining.Legislation is on the books and being drafted to regulate mining operations and their side effects. To avoid over-regulation and restrictive legislation, it is necessary that the public be educated and legislators informed of problems peculiar to the mining industry. Our side of the story needs publicity."

Jan 1, 1968

By Margaret Armstrong, Normand Champigny

"In order to define the ore/waste boundaries as finely as possible, mine planners often insist on kriging very small blocks (relative to the spacing of the available sample grades). These kriged estimates for very small blocks are over-smoothed. For several simple sampling patterns the relation between the block size and the variogram range, and the kriging results were studied. Meaningful estimates of individual blocks are obtained when the variogram range is large compared to the block size and the sample spacing. For a variogram range less than half the sample spacing, the kriged block estimates were found to be uncorrelated with the actual grades. The over-smoothed estimates should not be used for calculating recoverable reserves IntroductionNowadays most mining companies know that the geostatistical estimation method, kriging, gives the best estimates of individual block grades. As most mining engineers and geologists are now familiar with the basics of geostatistics, the definitions of the variogram and of kriging will not be repeated here. An appendix containing definitions and mathematical formulae is given at the end of the article for the sake of completeness.Even though it is well known that the kriged estimates for very small blocks are over-smoothed, mine planners who want to define the ore/waste limits as finely as possible (especially for selective underground mines), are often tempted to krige very small blocks. So we ask how small is ""too small""? Clearly ""smallness"" cannot be expressed in yards or metres. It depends on the nature of the orebody under study and this is reflected in the variogram model chosen to describe it.To answer this question, the changes in four key parameters are studied:• the kriging variance,• the variance of the estimated grade,• the slope of the linear regression of the true but unknown grade on its estimated value, and• the coefficient of correlation between the actual grade and the estimate;as a function of the block size and the variogram range. (Definitions of these four parameters are given in the appendix). Ideally the kriging variance should be low while the variance of the estimated grade should be equal to the dispersion variance of the blocks. The slope should be l.0, and so should the correlation coefficient.These four parameters have been calculated for several simple 2-D examples. The effect of using kriged block estimates that are too heavily smoothed are shown, and the dangers of trying to use these estimates for predicting recoverable reserves for small blocks (i.e. selective mining units) are pointed out."

Jan 1, 1989

By Z. D. Hora

Sedimentary phosphate-bearing rocks are found over a considerable area of so utheastern British Columbia that extends from Fernie east to the Alberta-British Columbia boundary and from the International Boundary northward to the headwatei: s of the Elk River. Phosphatic beds occur at the following four stratigraphic levels: 1. lower part of the Banff-Exshaw sequence of Mississippian age; 2. lshbel Formation of Permian age; 3. base of the Fernie Group of Jurassic age; 4. belemnite bed within the Rock Creek Member of the lower part of the Fernie Group. To date, considerable tonnages of phosphate rock have been proven in the area. However, no commercial production has been initiated because of a relatively low P2O5 grade. Data on assays and thicknesses of the phosphatic beds are in part recalculated from the paper by Telfer (I 933) and in part from assessment reports filed at the British Columbia Ministry of Energy, Mines and Petroleum Resources.

Jan 1, 1984

By J. Ipinza, J. P. Ibáñez, Casas J., S. Cortés

Copper powder generated during the treatment of electro-metallurgical bleeds by reactive electro- dialysis (RED) had totally reduced the content of ferric ions in acidic synthetic electrolytes (Cu (II)- Fe (III) – H2SO4). In batch and columnar experiments 100% of the ferric ions were reduced to ferrous ions with an extremely high kinetics. A preliminary conceptual design for reducing ferric ions based on an integrate RED- Column for treatment of electro-winning bleed system is discussed. This system is able to recover simultaneously sulfuric acid and copper powder, which will reduce ferric ions. INTRODUCTION It is well known the negative effect of ferric ions in the copper electro-winning process. The increase of ferric content in the electrolyte reduces the current efficiency, i.e., there is an increase in the energy consumption, and changes the surface morphology of the copper deposit (Das, Gopala & Krishna, 1996; Vargas & Parra, 2013). The increase of the specific energy consumption due to the loss of current efficiency occurs by the reduction reaction of ferric to ferrous ions in the cathode, at the anode the ferrous ions are slowly oxidized to ferric ions (Shaw, Dreisinger, Lancaster, Richmond & Tomlinson, 2004). To control the level of iron in the electrolyte, bleeds are needed; this bleed electrolyte containing copper, sulfuric acid, cobalt, iron and other impurities normally is waster, which increased the production cost of the plant (Milbourne, 2002; Mckevitt & Dreisinger, 2009). Then, permanent efforts oriented to treat those bleeds to avoid losses of valuables components are made; among them are use ion exchange resins (Shaw et al., 2004; Mackevitt et al., 2009), chemical precipitation (Izadi, Mohebbi, Amiri & Izadi, 2017) and electrodialysis (Cortés, Ipinza & Ibáñez, 2013). The last one allows to the simultaneous recovery of sulfuric acid and copper powder. If one of the valuables obtained by treating the bleed can be used to reduce ferric ion concentration in the electrolyte could be an important asset. This issue at laboratory scale is reported in this work, the use of copper powder, generated by reactive electro-dialysis when treating synthetic acidic electro-metallurgical bleeds, for reducing ferric ions in acidic electrolytes.

Jan 1, 2019

By Robert W. Baker

"Brunswick Mining and Smelting commenced production at the No. 12orebody, a lead/zinc/copper/silver deposit, situated some seventeen miles southwest of Bathurst, New Brunswick, in 1964 at 4100 tonnes per day. Today it operates at 10500 tonnes per day.Brunswick has utilized underground incentives since commencement of operations. Early incentive systems were “off the wall"" based on those in effect at other properties then manipulated to fit, often hack calculated from actual performances to tm1ve at the desired result. If subsequent payouts were considered too high the rates were simply reduced, often retroactively. A large amount of this was&apos; subjective and depended to a large extent on whoever was handling the bonus, in conjunction with senior mine department staff.In 1971, it was&apos; decided that a more scientific approach was needed, particularly with the introduction of the new cut-and-fill mining. After some research, a system based on Work Study was selected. Another major mining company employing such a system loaned one of their experienced employees to train some Brunswick personnel in the art of Work Study and conversion of data to incentive rates, and in 1972, the first such developed incentive rate was-introduced.Along the way, borrowing from others where necessary, a set of Brunswick principles and parameters were developed. While refined to some extent, these remain basically the same today.Improvements in methods and equipment have resulted in improved performance and reduced costs. The use of underground incentives has played an important role in this. A/though individual bonus earnings have steadily increased, bonus cost per tonne has remained nearly constant - in real dollars, it has regularly decreased. These are two of the main parameters of a successful system."

Jan 1, 1995

By J. L. Nebreda, Z. Fan, J. B. Patel

"A380 alloy has been widely employed to produce thin-wall components via high pressure die casting (HPDC). During HPDC processing, there is a significant problem of property variation even with the very stable and precision automated casting procedure. The enlarged variation lowers the component performance and affects the steady and uniform property distribution along the whole component. In this study, high shear melt conditioning technology was developed and applied to the melt prior to pouring into the shot sleeve. Experimental results show that with application of intensive melt shearing, the variation of elongation was decreased from 21.8to 13.9%, and yield strength variation was reduced from5.5to 3.6%. The improved property variation is attributed to enhanced nucleation both in shot sleeve and the die-cavity, and to the improved distribution of porosity and secondary phases as a benefit of high shear induced grain refinement. With application of high shear, large number of the Spinel phase (MgAl2O4) particles with double size distribution in average diameter of 80and 300nm were formed. Due to the good orientation relationship and small misfit between alpha Al and MgAl2O4, the particles act as the effective nuclei in shot sleeve and die cavity, respectively.INTRODUCTIONA380 alloy had been widely used for produce automotive components by cold chamber high pressure die casting(HPDC) processing, due to its relative good mechanical properties and cast ability performance, and more important most of A380 ingots were produced by recycled Al alloys. Therefore, to promote utility of A380 will contribute to reducing emission of CO2and to the lightweight of automotive industry as well. When cold chamber HPDC was employed to produce the components, the mechanical properties of A380 alloy always have a distribution range (named variation herein), or in other words the properties were not stable. The reason was ascribed to the typical solidification characteristics occurred in HPDC processing. During HPDC processing, there are three steps of melt movement. The first step is that the melt was poured into shot sleeve at temperature of about 680°C, in which shot sleeve was preheated by few shots of melt filling, or by heater. During step one, the first solidification of melt was happened in shot sleeve and about 20% solid made of coarse a-Al grains was formed(Li, Xiong, & Guo, 2016).Such kind of grains will retain in the final products and deteriorate the properties variation. The second step is that the melt was forced moving forward slowly by plunger at about 0.2–0.3m/s until the liquid melt front to the inner gate of mold. The third step is that the melt moved very fast to complete the filling of die cavity and refilling the solidification shrinkage by fast movement of plunger about 2–3m/s. The second solidification was occurred in die cavity and fine a-Al grains will be formed by high cooling rate at about 500–1000°C/s. From the solidification point of view, the grain size was dominated by nucleation and growth. When HPDC was employed to produce components, the melt quality becomes the priority factor to control the solidification process as the other casting parameters were kept at the same."

Jan 1, 2018

By F. Osmond, R. Kelly

"Malcolm Knowles, the famous adult educator once wrote: ""What a challenge we in human resources development face if we are to avoid the obsolescence of our workforce. I can foresee this challenge requiring that we reconceptualize (...) and redefine the role of HRD, away from that of managing the logistics of conducting training activities to that of managing a system of learning resources"".The context in which this was written surrounds the subject of adult education and the need for business and industry to change its approach to the treatment of adults as learners. In explaining what &apos;managing a system of learning resources&apos; means, Knowles refers to line supervisors and managers as the most ubiquitous resources for day-in and day-out employee development. In many organizations training has been largely a staff rather than line responsibility. Even where trainers reported to line management, it was still seen as a staff function performed by a few specialists.This change referred to by Knowles places a much heavier responsibility on line supervisors and managers for the development of their personnel than has traditionally been the case. Managing that change - handing over the responsibility to the line organization - is the supreme challenge for the HRD function.Just why is this change necessary? Because too often, the learner does not effectively use on the job what he or she learned in the classroom. In fact, learners often discard new methods and revert to the older ways. The reason training does not stick is that the systems for training and work management are most often separate entities and while one may support the other, they need to be a single integrated system in order to ensure the transfer to the job effectiveness of training and some real value for the training dollars.Because much training can be wasted, steps have to be taken to ensure that it fulfills its intended purpose. The effective and continuing application of knowledge and skills that learners acquire can only be realized when line supervisors and managers are at the centre of the training system.This paper describes how such a systemis being developed at the Iron Ore Company of Canada (IOC) as a functional training program is introduced. The following text provides background information on the IOC - who they are and where they are located, a definition of functional training, an evaluation of the suitability of this approach for adults in industry, a description of how the program is being implemented at IOC and some observations that have been made as this change is experienced."

Jan 1, 1995

By Jacob Wood, Robert Matusewicz

The Outotec® Ausmelt Top Submerged Lance (TSL) Process has achieved widespread commercial acceptance over the past 40 years for the processing of copper, nickel, lead, tin, zinc and precious metal bearing feeds. The continual development and evolution of the technology during this period has resulted in a more intense smelting process with higher energy efficiency and lower operating costs. More recently, considerable effort has been invested in decarbonisation of the process through improvements such as increased oxygen usage, dry feed injection and use of low-carbon auxiliary fuels. This paper covers a number of these recent advances to the technology and highlights their impacts on energy consumption and CO2 emissions for a range of non-ferrous smelting flowsheets. INTRODUCTION Relentless demand for improvements in the profitability, safety and environmental performance of non-ferrous smelting plants has driven a continual development and evolution of processing technologies in this industry. In response to these demands, a number of bath smelting technologies have emerged over the past 40 years and have been implemented for the treatment of primary and secondary feedstocks. The Outotec® Ausmelt Top Submerged Lance (TSL) Process (henceforth Ausmelt Process) is one such bath smelting technology which has been widely adopted in a large number of greenfield projects and brownfield plant modernisations (Wood & Hughes, 2016). Emissions of CO2 from the production of non-ferrous metals represent approximately 4-5% of global totals (Rankin, 2012), comparable with the almost 10% attributed to iron and steel production. Despite significant improvements in the energy efficiency of modern smelting technologies (Coursol, Mackey, Kapusta & Cardona Valencia, 2015), primarily through increased oxygen usage, further innovation and development is still required to address their reliance on fossil fuels such as coke and coal. Transformation of the non-ferrous smelting industry to low-carbon technologies and process flowsheets is lagging behind the power and transport sectors, which have witnessed significant growth in clean/renewable energy technologies to reduce CO2 emissions and address the issue of anthropogenic climate change (IRENA, 2018; IEA, 2018).

Jan 1, 2019

By R. R. Stone

"This paper will examine the role of debt and equity in project financing and will illustrate the impact on the return to the project sponsor of each type. Conventional debt sources will be examined, as will product purchaser advances, foreign export-import bank loans and lease financing. The paper will review guarantees, charges against the project, dividend restrictions and other commitments. It will also discuss various features of sales contracts and the degree to which they can assist in securing financing. IntroductionThe cost of bringing new mining projects on stream is escalating significantly more rapidly than general rates of inflation. Reasons for this include the higher costs of safeguarding the environment and ensuring the health and safety of workers. The need to develop properties in more remote areas is also a significant factor. These higher costs have not been matched by increases in metal prices, making the task of financing these projects ever more difficult. At the same time, the imagination of borrowers and lenders seems boundless, and innovative schemes for financing projects are constantly being unveiled.It is probably safe to say that no two projects have ever been financed in precisely the same way and the number of financing options for any project is limited only by the imagination of the sponsors themselves. The objectives of the project sponsor represent the most important factor in determining the scope of possible financial arrangements. For example, the sponsor may wish to maximize over-all company leverage by isolating each of its projects in separate companies. In so doing, it hopes to facilitate more ventures than would otherwise be the case. These objectives point toward true project financing. Additional objectives may be to develop a number of its properties by joint venture and to reduce the amount of debt on the sponsor&apos;s balance sheet. Those sponsors whose objectives include minimizing over-all financing costs will wish to increase the number of financial options and, as a result, will not be so concerned with effecting true project financing. This approach may also provide ""greater certainty that tax benefits are utilized quickly."

Jan 1, 1980

By O. E. Humeniuk, A. I. A. Salama, M. W. Mikhail

"The Western Research Centre (WRC) of CANMET operate a unique pilot plant facility where ongoing R&D on coal preparation and mineral processing is conducted. The pilot plant carries out two functions: coal preparation processing using state-of-the art technology and coal-liquid mixture preparation with intensive cleaning circuits that can also be used for mineral processing. In total, the pilot plant includes more than 30 different flowsheet options. The facility is dedicated to small and fine coal, and designed to be flexible and versatile.This paper describes the use of a pilot-scale facility as a research tool for process control development, fine coal beneficiation, development of coal-liquid fuels technologies, development of process models and testing and evaluation of new developments. The pilot plant is used to assist in resource development by evaluating and optimizing flowsheet selection, and producing sufficient samples for utilization tests. The facility is also an important tool for evaluating and testing samples from troublesome circuits of operating plants to find means to optimize and improve recovery, particularly of fines circuits.Detailed examples are given to demonstrate the role of a pilot scale facility in coal preparation R&D, coal industry development and optimization of coal processing operations. These examples include the development of heavy-medium cyclone computer control system, detailed evaluation of beneficiation of a coal deposit with high clay content, development of column flotation, and its role in fine cleaning circuits and treatment of ultra-fines in relation to intensive cleaning, the importance of testing coals in different processes, and cleaning processes influence on coking quality and other utilization applications. The potential of the facility for helping the mineral industry is also described."

Jan 1, 1992

By H. E. T. Haultain

Research is a much over-overworked word, sometimes a much abused word; the result of this has been that many who really need the word avoid it, shy away from it just as we do from that most useful word camouflage. We have not been altogether happy in our substitutes. Some years ago I spoilt a very good proposition by using the word investigation. There were those who thought that men and methods were to be investigated instead of simply processes. They expected disruption instead of co-ordination. The bad psychology up-set the scheme. The word experiment is even worse in its psychology. To the mind of the "practical" business man experiment denotes ignorance, waste of time and money and presupposes failure. It is not so long ago that the recognized way of improving the methods about a mine was to get a new manager. Until comparatively recently the average life of a boss in a mine in the West was under, rather than over, two years. Certainly was this the case in the smaller mines. Directors did not recognize that a cock-sure new boss was a greater experiment than a certain amount of feeling-his-way on the part of the old one. We always say that no two mines are the same but we are only now realizing to what extent the fine points of the game can and must be learnt on the job itself. One of the main differences between a small property and a large one lies in this study of the fine points of the game. In the early stages operation is the main point-get her going and keep her going.

Jan 1, 1924

By Q. Shi, Q. Feng

"The influence mechanism of chlorite on the flotation of pyrrhotite was investigated through flotation tests, Zeta potential measurements, optical microscope photos, solution ion measurements and absorption measurements. It is observed that, the addition of chlorite influences the flotation of pyrrhotite seriously. The IEP (isoelectric point) of pyrrhotite and chlorite is 7.6 and 4.3 respectively, in the condition of slight alkalinity, both pyrrhotite and chlorite are negatively charged, and the hetero-aggregation will not occur. With the existence of oxygen in solution, the iron ions are dissolved from pyrrhotite surface because of the oxidation of pyrrhotite during pulp conditioning. The dissolved iron ions adsorb onto the surface of chlorite in the forms of iron hydroxyl and iron hydroxide, and the adsorption results in the opposite charge of chlorite surface. As a result, the hetero-aggregation between pyrrhotite and chlorite occurs. The adsorption of chlorite changes the surface property of pyrrhotite and restricts the adsorption of amyl xanthate onto pyrrhotite surface, and then decreases the flotability of pyrrhotite.INTRODUCTIONIn sulfide ores processing, magnesium silicate bearing gangue minerals often report to the concentrate causing downstream processing problems as well as increased smelting costs. Talc,chlorite and serpentine are gangue minerals commonly encountered in complex sulfide ores (Engel, Middlebrook, & Jameson, 1997; Pietrobon et al., 1997; Witney & Yan, 1997; Chen, Grano, Sobieraj, & Ralston, 1999a, 1999b; Bremmell, Fornasiero & Ralston, 2005; Senior & Thomas, 2005; Wang, Somasundaran, & Nagaraj, 2005; WieseHarris & Bradshaw, 2007). All of them are characterized with uniform crystal structures consisting of silicon-oxygen tetrahedron and magnesium-oxygen octahedron. The magnesium-oxygen octahedron layers are broken during the liberation of serpentine to expose the magnesium-oxygen bonds with strong ionicity and hydration, which results in natural hydrophilicity of serpentine. In water, the hydroxyl on serpentine surface ruptures and dissolves into the aqueous phase while the Mg2+ remains, resulting in surface positive charge (Tao, 2012). As serpentine has a positive potential at alkaline condition, it is therefore likely that it will attach through electrostatic attraction to the negatively charged mineral surface and reduce both the flotation rate and recovery of target minerals (Lu et al., 2011). For talc, characterized as good natural hydrophobicity, the liberation comes from the interlaminar fracture to remain molecular bonds on surface with weak hydration. Being naturally hydrophobic, talc easily reports to flotation concentrates, thus reducing concentrate grade (Shortridge, Harris, Bradshaw, & Koopal, 2000; Beattie, Huynh, Kaggwa, & Ralston, 2006). Meanwhile, both molecular bonds and magnesium-oxygen bonds are exposed on chlorite surface when liberation occurs, resulting in moderate natural hydrophobicity between serpentine and talc (Tao, 2012). And thus the mechanisms of influence of chlorite on sulfide ores are more difficult to study."

Jan 1, 2016

Unplanned open stope hanging wall dilution is a significant cost for many open stope mining operations. Significant advances in empirical and analytical approaches for estimating stope dilution have been made, however, many important factors are still either ignored or assessed in purely subjective terms. There are many hard to quantify factors that simultaneously influence opening stability and dilution. This creates a significant difficulty for determining the influence of a single variable, such as exposure time, on opening stability. Open stope exposure time has been found to be one of the important factors that influences overall stope stability and dilution. A study is currently being conducted to quantify many of the factors influencing open stope dilution. The assessment of a large comprehensive case history database of Hudson Bay Mining and Smelting Co. Ltd. (HBMS) operations forms the basis of this study. This paper presents the findings of a study on the influence of stope exposure time on open stope dilution. The study is based on applying existing empirical stope dilution prediction methods to the extensive HBMS database. Minimising stope mucking time has been recognised as a method to significantly reduce stope dilution. Factors which influence hanging wall dilution, such as drill and blasting methods as well as undercutting the hanging wall, have been applied to reduce the scatter in the database. Empirical design techniques based on rock classification attempt to relate opening stability to ?stand-up time?, however, these approaches have not frequently been applied to the mining industry. Data from a ?stand-up time? graph have been interpreted in terms of an equivalent average depth of hanging wall slough and compared to the HBMS database findings. To add to the existing HBMS database, several stope case histories have been taken from Geco mine. These cases include data from very large open stopes with long exposure times. Data from all three sources suggest that hanging wall slough increases between .14 and 0.3 metres per month for a rock mass Q? value between about 4 and 13.

May 1, 2003

By S. Parada, P. T. Jones, M. Guo, S. Smets, E. Boydens

The corrosion behaviour of a pitch-bonded MgO-C refractory in contact with a vacuum oxygen decarburisation slag with high Al2O3 content (12-17 wt%) is investigated under VOD process conditions by rotating finger tests in a vacuum induction furnace. The refractory degradation mechanisms are studied by the characterisation of the corroded microstructures using scanning electron microscopy, equipped with energy dispersive spectroscopy. The influence on the refractory wear of the process temperature, corrosion time and the Al2O3 content in the slag is discussed. The degradation mechanisms include slag infiltration, direct MgO dissolution from the refractories into the penetrated slag, erosion of magnesia grains at elevated temperatures, removal of carbon through the MgO-C reaction, and finally, oxidation of refractory carbon by reducible slag components. Both a porous MgO layer and a dense (Mg)(A1,Cr)2O4 spinel at the slag/brick interface were observed. Their formation mechanisms and industrial relevance are discussed.

Jan 1, 2004

By P. Taskinen, A. Jokilaakso

The Flash Smelting Process for copper and nickel production has been one of the most successful new metallurgical process developments in the 20th century. The experimental data from laboratory scale investigations of studies has produced information and insight into the reaction mechanisms and kinetics of the flash reactions of copper concentrates. Advanced computer models coupling chemical reactions with a Computational Fluid Dynamics (CFD) software became possible with the development of commercial CFD software together with increased computing power. Currently, there are both experimental and CFD modelling, including also CFD–DEM coupling (Discrete Element Method), studies ongoing for investigating the kinetics of matte – slag reactions in the flash smelting furnace (FSF) settler. The ultimate goal of the modelling work is to develop a comprehensive FSF model for studying the behavior of changing raw materials, both primary and secondary, and distribution of their elements between the matte, slag, and gas phases. The use of User-Defined-Functions (UDF) is one way to digitalize metallurgical knowledge and experimental information to be used for supporting process experts and development of artificial intelligence applications in metallurgy. In this paper, a review of the development of the FSF reaction shaft modelling and experimental investigations, and the current work for the settler reactions’ experiments and modelling are presented. INTRODUCTION The Outotec Flash Smelting process (Bryk, Ryselin, Honkasalo, & Malmström 1958) has been used in the copper and nickel industry for 70 years with continuous support from experimental investigations by many research groups in academia, among others Jorgensen and Segnit (1977); Jokilaakso, Suominen, Taskinen and Lilius (1991), Chaubal and Sohn (1986), Kim and Themelis (1986), and in industry Mäkinen and Jåfs (1982); Kojo, Lahtinen and Miettinen (2009); Tuominen, Pienimäki and Fagerlund (2016). It has been developed also for pyrite and lead smelting (Asteljoki, Sulanto & Talonen, 1984). A schematic illustration of the FSF and other main parts of the process is depicted in Figure 1. Also, two and three dimensional physical water or gas models have extensively been used in product and process development (Lilja & Rajainmäki 1995). During the recent decades, computer based models have increasingly been adopted in the FSF research and development (Ahokainen & Jokilaakso, 1998); Ahokainen, Jokilaakso, Taskinen & Kytö, 2006; Hahn & Sohn, 1990; Jorgensen & Elliot, 1992; Zhou, Zhou, Chen & Mao, 2014; White, Haywood, Ranasinghe & Chen, 2015) to name a few, but also in supporting engineering and sales of the technology (Miettinen 2017). Even though the reactions of the sulfidic concentrate particles have been included in the reaction shaft modelling, the complete FSF model with both gas-solid/drop and molten slag/matte drop has so far been and still is too demanding for today’s computer hardware.

Jan 1, 2019

By Burden of Occupational Cancer in Canada Project Team, Demers P. A., Kim J., Arrandale V. H., Jardine K.

"In 2012 diesel engine exhaust (DEE) was classified as a human carcinogen by the International Agency for Research on Cancer (IARC) and is one of the most common workplace carcinogens internationally. We estimate that approximately 2.4% of lung cancers (n=560) and a suspected 2.7% of bladder cancers (n=200) are attributable to occupational exposure to DEE annually in Canada. High levels of exposure to DEE in mining results in a disproportionate number of cancers in this sector (approximately 220 lung and 20 suspected bladder cancers annually). These could be prevented by reducing the number of workers exposed and level of exposure. KEYWORDS Bladder cancer, Diesel engine exhaust, Economic burden, Lung cancer, Mining, Occupational cancer, Prevention, Regulation INTRODUCTION Diesel engine exhaust is a complex mixture of gases and particulates containing known and suspected carcinogens such as benzene, polycyclic aromatic hydrocarbons (PAHs), and metals. Approximately 900,000 Canadians are exposed to diesel engine exhaust at work, making it the most prevalent occupational lung carcinogen in Canada (CAREX Canada). Diesel engine exhaust is recognized as one of the most common workplace carcinogens in the world, but its classification as a human carcinogen by the International Agency for Research on Cancer (IARC) was relatively recent. In 2012, after decades of mounting evidence, diesel engine exhaust was upgraded from a probable (IARC Group 2A) to a definite human carcinogen (IARC Group 1) (IARC, 2014). The IARC evaluation was based on strong evidence in humans for an increased risk of lung cancer, as well as strong evidence in animal studies. The key human evidence considered by IARC was from epidemiologic studies of workers in truck transportation, rail transportation, and mining industries, where the use of diesel engines is widespread. These studies provided strong sufficient evidence for an increased risk of lung cancer, as well as limited evidence for bladder cancer. The human studies used particulate matter, generally measured as elemental carbon (EC) or total carbon, as a surrogate for diesel engine exhaust to assess the risk associated with level of exposure. The animal studies reviewed by IARC showed sufficient evidence for cancer with exposure to whole diesel exhaust and the particulate matter fraction of diesel exhaust, but not for the gas phase components."

Jan 1, 2019