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By R. P. Townsend

It is a widely accepted "fact" that a Koepe friction hoist is generally the best solution for production hoisting when compared to a double drum hoists. This would appear to be true if one looks at the initial capital cost of just the hoist, and also if one compares the size of the motors selected for the duty. But is this the whole story? What are the longer term costs involved in the hoist's operation, and what are the relative efficiency's of the two designs? Perhaps the Koepe hoist design enjoys a better reputation than it deserves.

Jan 1, 2011

By S. Eckert, M. Reuter, D. Obiso, S. Kriebitzsch, M. Akashi

The present paper focuses the application of CFD techniques to investigate the Top-Submerged- Lance (TSL) gas injection in liquid metal. Previous works of the authors have shown that up- and down- scaling procedures based on the modified Froude number have some shortcomings, as this approach does not take into account the interfacial and viscous forces. Indeed, surface tension and dynamic viscosity of the smelting slags (σ = 0.4-0.5 N/m, μ = 0.2 Pa·s) are higher than the operating fluids that have been used in literature (water, paraffin oil) to study TSL injection in down-scaled furnaces. In order to get closer to real systems, the authors study the TSL injection of Argon in a liquid metal. An experimental campaign was carried out in the X-ray lab at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), where the eutectic alloy GaInSn was used as liquid phase. The alloy is liquid at room temperature, and X-Ray imaging is used to picture the multiphase flow in a quasi-2D vessel. The aim of the present work is to demonstrate the applicability of CFD techniques to model multiphase flows involving liquid metals, and validate the model using the data produced at HZDR. The commercial software ANSYS Fluent® was used together with the Volume of Fluid model to directly resolve the gas-liquid interphase. Some features of the flow, such as the void fraction distribution and bubble detachment frequency are tracked with CFD and compared to the experimental data. INTRODUCTION In the last thirty years the TSL smelting technology has increasingly been used for industrial non- ferrous smelting processes and is now one of the significant pyrometallurgical processes. Developed in the early 1970’s at CSIRO, the furnace is nowadays commercialized in different market sectors, including copper and lead smelting, zinc fuming, waste treatment and slag recovery (Floyd, 2005). Despite the wide application of these reactors in the pyrometallurgical market, some aspects of the process are still not fully clarified, since in-situ measurements and optical accesses are prohibitive because of the high temperatures and aggressive conditions. Phenomena such as the bubbling regime, the slag solidification and the submerged combustion still need a deeper scientific investigation to obtain a better understanding of the process.

Jan 1, 2019

By B. R. Rakishev

When transferring from the railway transport to the combined automobile-conveyor transport by stripping works at coal mines, it was proposed to form at the working zone a concentration horizon for reloading part of the stripping volumes at the railway transport. The procedure is adduced for substantiating parameters of bloc-panels, depending on the step of transferring of reloading points in interrelation with the intensity of the working zone?s development with observing the balanced movement of parts of the stripping zone relative to the temporary concentration level.

Aug 1, 2013

By Gang Mei, Nengxiong Xu, Yanlin Zhang

After open-pit mining finishes, an iron mine with steeply inclined ore-bodies will generally transform to underground mining. Non-pillar sublevel caving method, with horizontal slice mining from up to down, is commonly used for mining deep ore-bodies under the open-pit bottom. As horizontal slice mining proceeds, a gradually enlarging goaf will be formed under the open-pit bottom, the rocks surrounding the handing and heading sides of the goaf will collapse continuously, and then these results in rock-mass failure with large deformation and displacement in the open-pit slope. Based on FLAC3D, a modeling approach to predict pit slope deformation and failure induced by transitioning open-pit to underground mining is proposed in this paper. This method mainly consists of three procedures of modeling, i.e., mining modeling, landslide modeling, and filling modeling, of which landslide modeling is the core of the proposed approach. In the procedures of modeling with FLAC3D, iteration non-convergence is taken as a local failure criterion of pit slope. When iteration calculation cannot converge, the sliding modeling will start by deleting some elements with large displacements, and finish until convergence. Before modeling landslide, several displacement contours of rock-masses in the pit slope are searched out, and each contour is an approximate possible sliding surface of the open-pit slope. From these contours, the most proper one is selected as the slope sliding surface by using the iteration calculation convergence and minimum element deletion as the judgment condition. Landslide modeling is then realized by removing the elements outside the slope sliding surface. Finally, to demonstrate the effectiveness, the proposed approach is used to simulate the process of open-pit to underground mining at Yanqianshan Iron Mine, and to predict the deformation and failure characteristics of open-pit slope during underground mining. The case study results show that: the prediction of the slope stability determined by using our method is consistent with that calculated by using the limit equilibrium methods.

Jan 1, 2015

By D. H. Rousell

"Rocks of the Whitewater Group (Aphebian age) oc ithin the Sudbury Basin and consist of three formations rre, from oldest to youngest: Onaping, heterolithic breccias lus an igneous-textured component; Onwatin, argillite and siltstone; and Chelmsford, greywacke with minor argillite with siltstone. Mineralization in these rocks is as follows:1) Sulphides are disseminated throughout the Onaping Formation. Pyrrhotite, the major sulphide mineral, occurs mainly as fragments; other sulphides are chalcopyrite, sphalerite, galena, pyrite and marcasite.2) Zn, Pb, Cu, Ag and A u mineralization in the Vermilion member, a carbonate-chert unit near the base of the Onwatin Formation (Vermilion and Errington mines).3) Pyrite and minor base metals in the Onwatin Formation .4) Mineralized quartz veins, located at or near the base of the Onaping Formation, include such deposits as Moore Lake (Pb, Zn and Ag), Foisey (Zn, Pb), Papineau (Cu, Au and Co) and Proulx (Pb, Zn, and Cu). Quartz-carbonate veins in a meta-gabbro sill contain Cu, Zn, As and Au. Material from quartz veins from two former ""gold mines"" (Gordon Lake and Creighton) yielded no Au values.5) Anthraxolite veins in the Onwatin Formation .The mineral occurrences can be explained in term of either the volcanic theory or meteorite-impact theory of basin formation. According to the latter theory, the sulphide fragments in the Onaping Formation may have been formed by the brecciation of sulphide-rich pods located in the upper mantle and at the base of the transient crater; some of the sulphides may have been derived from target rocks of the Huronian Supergroup. The Vermillion-Errington deposits may represent sedimentary exhalative deposits of the Remac type; mineral-rich brines, trapped at the base of the transient crater, rose upward and precipitated the mineralized carbonate-chert under reducing conditions. These conditions continued throughout the deposition of the upper Onwatin Formation but pyrite was the only sulphide that formed.The quartz veins were emplaced during the time of basin deformation. Metamorphism remobilized and concentrated carbonaceous material in the Onwatin Formation 10 form the anthraxolite veins."

Jan 1, 1984

By John E. Udd

I N Part I of this paper, Professor Morrison suggested that our technique of causing cracks to develop around openings in a sheet of photoe1ashc plastic is, in effect, a laboratory-scale rockburst. Our investigations have indicated that the location and direction of these cracks are predictable, and that their growth can be controlled. On several occasions, we have been able to cause these cracks to propagate sufficiently slowly to be followed, with the naked eye. In practice, the rate of growth, gradual or sudden, would depend upon rock properties. This part of the paper presents an analysis of the stresses surrounding the openings before and after failure and also this author's views on the causes and after-effects of cracking. An attempt is made to correlate the stress patterns with those deter-mined from pure mathematics. Considering that the openings, except for the central enlargement, are long apertures with somewhat rounded corners, they might be compared with elongated ellipses having axes ratios of about 20:1 or with

Jan 1, 1963

By D. Ling, Santos. R. M., T. Van Gerven, M. Guo

The valorization of alkaline waste materials from thermal processes utilizing intensified mineral carbonation routes is investigated. The principal advantages of this approach are the chemical stability and storage safety of mineral carbonates, the opportunities for process integration presented by the technology, and the potential for conversion of low-value materials into useful products. Treatment and disposal of steel slags are a costly burden on steel plants. Sustainable solutions for Argon Oxygen Decarbonisation (AOD) and Continuous Casting (CC) stainless steel slags and Basic Oxygen Furnace (BOF) steel slag are desired. An integrated on-site mineral carbonation approach is envisaged as a favourable solution.

Jan 1, 2011

By D. M. Baird

Copper mineralization occurs at several places along the shore of Notre Dame bay, Newfoundland, and at one time formed the basis of a considerable mining industry. The sources of the mineralizing solutions and the structural settings of some of the deposits have not been clearly understood. This paper reports new investigations into the origin and structure of the deposits between Bett's cove and Stocking harbour, in a strip about ten miles long and two miles wide along the western shore of Notre Dame bay. The most complete previous descriptions of the area are those of Snelgrove (1929, 1931, 1938), Douglas, Williams and Rove (1940), and the writer (1947). The discovery of the Bett's Cove deposits took place about 1860, soon after the discovery of the well-known Tilt Cove deposits to the north. Several other small prospects were found between Bett's cove and Stocking harbour between 1880 and 1910. At Bett's cove, active mining began in 1875 and a small smelting plant was built near the mine in 1877. .Mining operations came to an abrupt halt in 1883 after a major cave-in. In 1900, and again in 1906, attempts were made to drain the old workings and reopen the mine but were abandoned long before completion. Total production amounted to about 130,000 tons of hand-picked copper ore which averaged about ten per cent copper, and 2,450 tons of pyrite (Snelgrove, 1938, pp. 52-55).

Jan 1, 1948

By André Chagnon, Michel Malo, Benoît Dubé, Chantal Pelchat

"Abstract- In the southern Gaspé Appalachians, gold mineralization is spatially associated with the Acadian dextral strike-slip Grand Pabos-Restigouche fault system. Two different structurally-controlled gold prospects, the Lac Arsenault and the Saint-André-de-Ristigouche, are described to unravel the genesis of gold mineralization in this part of the Canadian Appalachians.At the Lac Arsenault gold prospect, gold mineralization consists of Au-As-Pb-Zn-Cu-(Ag) polymetallic fault-filled quartz veins with laminated textures emplaced in brittle-ductile sinistral X shear fractures. Mineralized veins are hosted by Middle Ordovician graywacke of the Arsenault Formation, belonging to the Dunnage Zone, the Early Paleozoic oceanic domain of the Appalachians. Terrigeneous rocks of the Arsenault are regionally metamorphosed at the lower greenshist facies and the mineralized veins are included in a zone of Fe-carbonate alteration.The Sb-Au-As mineralization of the Saint-André-de-Ristigouche gold prospect, in the southwestern Gaspé area, comprises extension veins in the extension direction emplaced in brittle conditions. Mineralized veins are hosted by calcilutite and laminated silty and argillaceous limestone of the Early Silurian part of the White Head Formation, which belongs to the Gaspé Belt, the Middle Paleozoic successor basin in the Gaspé Appalachians. Metamorphic grade of the White Head Formation in the southwestern Gaspé area is very low, but the gold mineralization is included in a zone of hydrothermal propylitic alteration which includes two Cu-skarn mineral occurrences. The Lac Arsenault gold prospect has many characteristics of "greenstone-hosted quartz-carbonate vein" deposits whereas the southwestern Gaspé area, which includes the Saint-André-de- Ristigouche gold prospect, shows affinities with the geological setting of sediment-hosted gold deposits (Carlin-like deposits). The two gold prospects are controlled by the Grand Pabos- Restigouche fault system but they were not emplaced at the same level in the crust. Acadian strikeslip fauting played a major role in their respective genesis in providing channelways for ore-bearing fluids. The recognition of the analogy of the geological setting of the southwestern Gaspé area with that of Carlin-like mineralization gives new ideas for exploration in the area and elsewhere in the Appalachians.Résumé - Dans le sud des Appalaches de la Gaspésie, on trouve des minéralisations aurifères spatialement associées au système de failles de coulissage dextre acadien de Grand Pabos-Restigouche. Deux indices très différents, Lac Arsenault et Saint-André-de-Ristigouche, sont décrits pour évaluer la genèse des minéralisations aurifères à contrôle structural de cette partie des Appalaches canadiennes. Au Lac Arsenault, la minéralisation aurifère comprend des veines polymétalliques à Au-As-Pb- Zn-Cu-(Ag) en remplissage de failles. Ces veines à texture laminaire se retrouvent dans des zones de cisaillement fragiles-ductiles senestres de type X. Les veines minéralisées sont encaissées dans les grauwackes d’âge Ordovicien moyen de la Formation d’Arsenault appartenant à la zone de Dunnage, le domaine océanique du Paléozoïque précoce des Appalaches canadiennes. Les roches terrigènes de l’Arsenault sont métamorphisées régionalement au faciès inférieur des schistes verts et les veines aurifères sont dans de larges zones d’altération dolomitique (Fe-carbonate).Dans le sud-ouest de la Gaspésie, la minéralisation à Sb-Au-As de Saint-André-de-Ristigouche est dans des veines d’extension comprises dans la direction d’extension et mises en place dans des conditions de déformation fragile. Les veines minéralisées sont encaissées dans les calcaires argileux et les calcilutites de la partie silurienne de la Formation de White Head qui appartient à la ceinture de Gaspé, le bassin successeur du Paléozoïque moyen des Appalaches de la Gaspésie. Le degré métamorphique des roches du White Head est très bas, mais"

Jan 1, 1998

Since 2008 rapid advances have been made in technologies for the sensing and sorting of ores, particularly copper, and copper-related ores. Advances include significant increases in the sensitivity and throughput, specifically in the area of bulk sorting. Such advances were not possible without contemporaneous advances in the understanding of copper orebodies, in particular the understanding and quantification of the heterogeneity required within an orebody to support an effective sort, regardless of the technology deployed to do this. This paper covers fundamental knowledge in the characterization of orebodies and their ores for sorting; relationships between measures of heterogeneity and sorting response; the design of bulk sorting systems that can exploit this heterogeneity to add value to copper operations; and, a quantification of the value that can be generated from bulk sorting at a case study mine. INTRODUCTION Society currently puts increasing pressure on industries to move towards cleaner and more efficient means of production, and the mining industry is no exception. Mining additionally faces other factors increasing the pressure to be more efficient: high-grade and easily accessible reserves have become largely depleted, therefore the mined grade at operations across most commodities, including and in particular copper, is decreasing. Additionally, the grade of new discoveries in the sector continues to decrease (Schodde, 2011). Factor in the high capital cost of processing facilities and the low levels of efficiency of current grinding circuits, and the situation for such mines becomes dire. Sorting, by maximizing the amount of ore extracted while simultaneously reducing the waste content in ore delivered to downstream processes (whether simply transport and crushing, or more sophisticated circuits such as grinding and flotation or leaching) has long been of interest to mining operations and projects struggling with low margins (Bamber, 2012). However, until recently sorting technologies that are both cost effective and effective at such high throughputs have not been commercially available.

Jan 1, 2019

By T. E. Warren, K. W. Bowles

"IntroductionTHE PROBLEM of producing synthetic liquid fuels from coal and other raw materials is of increasing importance in Canada as well as in the United States. This is due, to a large extent, to the continually increasing demand for gasoline and other liquid products which are now obtained solely from petroleum. The United States has reached a position where domestic supplies of crude petroleum must be augmented by imports and Canada is still a long way from self-sufficiency. In the event of war, there might well be an immediate need to find supplementary sources of liquid fuels. It is, therefore, expedient to consider alternative sources of production now -well in advance of the time when supplies of petroleum may prove inadequate to meet requirements.The purpose of the present paper is to give a short review of the history of liquid fuel production from coal, to describe briefly the research sponsored by the Federal Government on the coal hydrogenation process, and finally to evaluate the present status and future trend of the synthetic fuel industry, with special reference to necessary research work.History of the Oil-From-Coal IndustryThe history -of coal liquefaction began in 1913, in Germany, with the work of Frederick Bergius. His first approach to the subject was not deliberately planned."

Jan 1, 1952

By K. Himbeault, D. Campbell, N. C. Garisto, D. A. Orava, A. Rosaasen

"The level of scientific knowledge about the effects of contaminants is increasing and changes in environmental monitoring are likely to allow for the assessment of environment effects particularly to the aquatic environment. This paper provides an overview of recent developments in this area which include the environmental effects monitoring program for pulp and paper operations, the assessment of the Aquatic Effects of Mining (AQUAMIN) program, the Aquatic Effects Technology Evaluation (AETE) program, and the review of the federal Metal Mining Liquid Effluent Regulations (MMLER). The paper also provides a look forward at the direction of environmental monitoring of mine projects in Canada. IntroductionEnvironmental monitoring programs provide a wide range of data to environmental management systems, regulatory authorities, and stakeholders. The data obtained are used to demonstrate that operations are in compliance with regulatory environmental protection requirements, and provide the scientific basis for assessing the effectiveness of environmental protection measures. Environmental monitoring requirements for mine projects are established based on the type of operation, site specific issues and concerns, and the requirements of regulators and mine proponents.The level of scientific knowledge regarding the potential effects of contaminants on the receiving environment is increasing, and in particular with regards to the receiving aquatic environment. Regulatory controls regarding the protection of fish, fish habitat, and fishery resources are being reviewed with regards to their adequacy, and the environmental effects monitoring program on the pulp and paper industry is expected to provide useful data relevant to those types of operations. These developments are of interest to mine proponents as it is presently expected that an environment effects monitoring program will be developed specifically for the metal mining industry under a regulated environmental effects monitoring program as part of the Fisheries Act. This paper reviews recent developments in this area, and provides a look forward on the future directions of environmental monitoring programs."

Jan 1, 2000

By Wei Yun-Jie

Columnar jointed basalt is a fractured rock, with a lot of small spacing structural planes and poor integrity of the rock mass. On the basis of the comprehensive study of the columnar shape of Columnar joints, rugosity of the fracture surface and the chemical composition of basalt, columnar joints of Bai hetan dam area were formed as a result of the cooling and shrinkage effect of magma. Columnar joints basalt are mainly chlorite, kaolinite, epidote, tremolite chemical reactions and the content of columnar joints are mainly chlorite by slice identification and chemical analysis. Columnar joints basalt showed high uniaxial tension test, low coefficient of friction and high cohesion by indoor physical and mechanical test. Columnar joints rock mass showed high strength and large deformation by field shear test and deformation test. Columnar joints basalt can be used directly as a foundation of dam as long as we follow the rules and reduce disturbance strictly.

May 1, 2009

By R. J. Mitchell

"High narrow backfills of significant strike length approach the stress conditions associated with a free standing wall but this lower bound design approach is not considered efficient for earth structures. This paper considers the design of high narrow backfills using upper bound limit analysis, retaining wall theory with backfill arching and centrifuge model tests. Complex toe support situations pertaining to operational factors at Falconbridge's Lockerby Mine are investigated. It is shown that the susceptibility of high narrow fills to toppling is much lower than anticipated from the retaining wall analysis and that toppling can be avoided by a suitable toe support. It is also concluded that adhesion between the fill and an adjacent pillar can markedly increase the stability of the fill. INTRODUCTIONFalconbridge's Lockerby Mine pillar projects will expose cemented tailings backfills to heights (H) up to 55 m. The exposed backfills may have strike lengths (L) greater than the heights but are relatively narrow, having widths (w) of up to 12 m. The bulk cement content of the fills varies from 8.3% (12.1 T:C) to 3.0% (33.1 T:C). Exposed faces may have up to a metre of overhang due to stope overblasting, as shown in Figure 1. These fills have a solids specific gravity of close to 3.0 and were placed at a pulp density of about 68%. The tailings have a fairly uniform grain size with 32% less than 0.075 mm (200 sieve) and about 12% slimes (less than 0.02 mm sizes). The fill exposed by early pillar removal will be backed by adjacent, near vertical, ore pillars. Future pillar removal may expose similar fills which are not supported by an adjacent ore pillar but which will be backed by either an open void or by uncemented backfill. Furthermore, these fills may be undercut when the pillar slot is driven, further reducing stability (case 3, Fig. I) or a wedge could be left to help support the fill (case 2, Fig . 1). This paper presents limit equilibrium analyses for these various backfill conditions in a 22: 1 T:C fill and com- pares the results to data from centrifuge model studies at a scale factor of A= 157 as indicated in Figure I. Prototype fills have a 6 m deep cone plug of 16:1 T:C which is accounted for in the comparison of centrifuge model test with analytical results."

Jan 1, 1989

By M. A. Hardie

"CASES and mixtures of them are so common and so much a part of everyday existence that they become so taken for granted that their individual characteristics and idiosyncrasies rarely become of curiosity to others than those involved in tl1eir production, processing, treatment, transportation, and for utilization. The use of the most common and universal mixture of gases -air -is begun at birth by ail living creatures and their discontinuation of its use terminates existence. Modern man rides on air in his tires, rides through it for high-speed transportation, and uses it for his comfort in the heating and air conditioning of his domicile. It is neither the aim nor the in-tent, in the next few moments, to provide a panacea for even a portion of the problems inherent in the gas industry nor to delve deeply into any particular facet of its diversities. The purpose is primarily to touch upon some of the peculiarities and generally to consider approaches to employ in the pursuit of solutions."

Jan 1, 1959

By I. Filzwieser, M. B. Hanel, A. Filzwieser

The paper describes the current density increase within the last 150 years. From the beginning in 1885 at 30 A/m² up to the highest used current densities nowadays at 420 A/m² towards future pathways were even 1000 A/m² can be achievable. A short tour through history will highlight the milestones of the process of electrolytic refining of copper. Besides the improvement of the existing technology, the biggest changes leading to higher possible current densities are linked to the introduction of the ISA stainless steel plates and the introduction of the parallel flow principle. Furthermore, the parameters influencing the limitations regarding current density and therefore the practical used current density as well as the influence from the chemical composition of the electrolyte is discussed. Finally, the possibility of further increasing the current densities by enhancing the relative movement between electrolyte and electrode will give an outlook about the future of the copper electrolysis process. INTRODUCTION The current density is the most important characteristic to describe the productivity of a copper refining electrolysis besides the characteristic number for the electrical efficiency. Over the last 150 years, current density has risen from a few amperes per square meter to over 400 A/m² without any significant change in the principle of electrolytic refining. This increase in current density is documented exemplary by the electrolysis of Montanwerke Brixlegg in Austria (Brixlegg, 1963, 2013). The very beginning of the technology of electrolytic refining of copper was first patented in England by James Elkington in 1865 and the first electrolytic copper refinery was built in Newark, New Jersey, in 1883 (Armstrong, 1999). The secondary smelter Montanwerke Brixlegg, Austria, has been operating an electrolysis plant since 1884. In 1988, the third "Mount Isa" electrolysis plant worldwide and the first in Europe was put into operation in Brixlegg. Since 2010, the so-called high-current electrolysis (parallel flow METTOP-BRX Technology) with a current density of approx. 400 A/m² has been operated in half of the electrolysis process.

Jan 1, 2019

By E. M. Timoshenko, A. V. Tarasov

The results of laboratory, bench-scale and semi-commercial investigations of a method for adding surfactant (technical-grade lignosulphonate) to the process of pressure leaching of nickel-containing pyrrhotite concentrates have been discussed. Lt has been demonstrated that feeding of technical-grade lignosulphonate distributed along the length of an autoclave ensures a reduction in its requirement by a factor of 1.5 to 2 as compared with single-point feeding; it also results in a decrease by 5% in the unit requirement of metallized iron-bearing precipitator in the process of non-ferrous metals precipitation and reduces by 0.05 to 0.1% (abs.) the nickel and copper contents in the tailings of the given process. Technical solutions have been proposed for commercial introduction of the process.

Jan 1, 2004

By Lawrence Devon Smith

"This paper examines the impact of the various assumptions that go into an economic evaluation, and shows how these can be combined to show an exciting result that may not really exist. An example of an embellished case (the kind that one frequently sees when projects are being promoted) is developed and the cumulative impact is analysed to show the actual project underneath. The paper also points out some areas to watch for overly optimistic assumptions such as prices, inflation, and debt. The concept of a ""bare bones"" base case is proposed (constant metal prices, constant dollars, no inflation, no debt, no interest, on a project basis, after tax) as a common reference point.As well, the discount rate is examined as a fundamental means of reflecting risk in discounted cash flow evaluations. Current industry practice is discussed, and a methodology for the analysis of risk levels is proposed that assesses the constituent components of the discount rate: real interest, mineral project risks, and country risk.INTRODUCTIONOften, the first time that all of the technical and economic data for a mineral project comes together in one place is when the economic evaluation is developed. This typically happens when work on the project has progressed to a sufficient level of detail that the effort to produce a year-by-year cash flow is justified, usually at the pre-feasibility or feasibility study stage. The data involved will include:• production; tonnes waste and ore mined, ore grade, mining recovery, metallurgical recovery, metal sold• revenue; metal price, smelting & refining charges, marketing costs• operating Costs; mining, milling, administration, fees, royalties• capital Costs; exploration, development, construction, indirect costs (engineering, management), contingencies, start-up, inventories, working capital, replacement and sustaining capital, closure costs• taxes and royalties• exclusions; depreciation (this is not a cash item), sunk costs (only costs going forward)."

Jan 1, 2003

By J. Makgatho, P. Condori, J. Winnett, Fischerm D.

"Palabora Mining Copper (PMC) has two autogenous mills that have been in operation since 1976. The mills were originally designed to treat 30 000 t/d of open cast copper ore in a closed circuit with cyclones. As the ore body went deeper the open cast method of mining was changed to block caving, a consequence of this was the dolerite content (hardest barren material) increased significantly, increasing the production rate of pebbles and thus reducing the milling capacity. In order to cope with the increased ore hardness and to increase mill capacity, a second ball milling stage and pebble crushing were incorporated to the circuit. The above actions created new challenges to the circuit operation and bottlenecks in different areas of the milling circuit.This paper reports the holistic work performed on the Palabora autogenous milling circuit including the implementation of a mill constraint control scheme, the implementation of a pebble removal system from the circuit and a new circuit configuration."

Jan 1, 2012

By B. J. McKay, K. Schneider, H. B. Nadendla

"A series of experiments were conducted to assess the impact of zinc additions on the morphology and soundness of the interface of Al-Mg compound castings. It was found that high amounts of zinc (>15wt%) are necessary to affect the morphology and microstructure of the interface. At these zinc concentration levels, the formation of the zinc-rich phases t1 and ? were observed along with the Al-Mg intermetallic phases ß and ?. The micro hardness of all phases across the interface was found to be similar, ~200 Hv. This even hardness gradient is thought to avoid mechanical failure in the interface under load. In samples containing large concentrations of zinc (>15wt%), the formation of bubble shaped voids as well as the complete transformation of the aluminium alloy was observed. While the exact mechanism causing the voids has not been identified it thought to be connected to the Kirkendall effect. INTRODUCTION Conventional single material components are increasingly failing to meet the demands, in terms of cost and performance, of the transport industry. Compound castings have been identified as a promising alternative as they possess a number of benefits (Bührig-Polaczek, Röth, Baumeister, Nowack, & Sussmann, 2006). Compound casting is described as a process in which a metallic melt is cast around a solid metal shape. Preliminary research has concluded that for the stability of such a resultant hybrid structure it is imperative that both metals form a sound connection via form closure, force closure, or material bonding. A continuous material bond between the two metals is also highly desirable as the formation of a crevice between the metals could lead to galvanic corrosion, particular in a humid environment (Lao, 2013; Rübner, Günzl, Körner, & Singer, 2011). Even though Al-Mg compound castings could offer the biggest potential in terms of weight savings to date only a limited amount of research concerning such structures exists."

Jan 1, 2018