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By K H. Esbensen

The critical role of representative sampling is featured and illustrated by selected examples from the geosciences and beyond. As there already are many demonstrations of the potential (and potentially large) economic consequences of ignoring proper standards with respect to representativity, eg for mining and minerals processing companies, which æstand to lose millions of dollars by failing to optimise exploitation of their mineral resourcesÆ, such need no further iteration here.This keynote lecture, rather, takes a point of departure from the opposite perspective: what is to be gained by a scrupulous stand for representativity? Honesty, reputation, credibility, market advantage - is what!CITATION:Esbensen, K H, 2012. The critical role of representative sampling, in Proceedings Sampling 2012 , pp 9-12 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By P. Tsakiris

The increasing social interest for the environmental issues, forces the authorities to enact more rigorous regulations. The mining industry is one of the sectors that concentrate vigorous remonstrance. It is an absolutely justified reaction, as a result of the numerous contaminated and polluted sites that have been inherited by previous operations and they remain unremedied. The lack of a consolidated global legislation, transfers the burden of decisions to the national level. This paper consists of two parts. At the first part, it discusses the critical role of the state to form an effective environmental policy, feasible for the context of the national economy. Afterwards it analyses two of the main points, which must be considered by the regulator for the excavation activity, the abandoned sites and the duration of the mining investment. The aims are to defuse, in the short-term, the public pressure, protecting the economic growth and, at the same time, to form a basic structure for the development of the corporate social responsibility. The second part presents an alternative financial instrument for the Greek regulatory framework, conformed to the characteristics of the Greek Economy, and analyses the expected benefits both for the business and the social welfare.

Jan 1, 2002

By B. Yarar

The critical surface tension of wetting (?c) of Cu2S, FeS2, PbS, and MoS2 were determined by plotting flotation recovery versus YLV which was arranged by methanol, and Extra-polating to % R = 0. ?c values ranged from 26 dyne cm-1 for MoS2 to 49 dyne cm-1 for PbS and elemental sulfur gave a value of 31.5 dyne cm-1. Minerals exhibiting natural flotability of different extents, could be separated from their mixtures in the absence of conventional flotation reagents, but controlled ?LV. Correlations between non-stoichiometry and degree of natural hydrophobicity for MOS2 are also reported in this paper.

Jan 1, 1983

By J. C. Edwards, C. C. Hwang

In ventilated tunnel fires, smoke and hot combustion products may form a layer near the ceiling and flow in the direction opposite to the ventilation stream. The existence of this reverse stratified flow has an important bearing on fire fighting and evacuation of underground mine roadways, tunnels and building corridors. In the present study, conducted by the National Institute for Occupational Safety and Health, a CFD program (fire dynamics simulator) based on large eddy simulations (LES) is used to model floor-level fires in a ventilated tunnel. Specifically, the critical ventilation velocity that is just sufficient to prevent the formation of a reverse stratified layer is simulated for two tunnels of different size. The computer code is verified by checking the computed velocity profile against experimental measurements. The CFD results show the leveling-off of the critical ventilation velocity as the heat release rate surpasses a certain value. At this critical ventilation, the ceiling temperature above the fire reaches a maximum for both tunnels. The velocity leveling-off can be explained from this observation. An extended correlation of Newman (Combust. Flame 57 (1984) 33) is applied to the temperature profiles obtained by CFD. At the critical ventilation, temperature stratification exists downstream from the fire. The computed critical ventilation velocity shows fair agreement with available experimental data taken from both horizontal and inclined fire tunnels. The CFD simulations indicate that the Froude modeling is an approximation for tunnel fires. The Froude-scaling law does not apply to two geometrically similar fire tunnels. The CFD results are compared with two simple theories of critical ventilation by Kennedy et al. (ASHRAE Trans. Res. 102(2) (1996) 40) and Kunsch

By A. KROENLEIN

THE Cromwell 'Pool has been the outstanding development in Oklahoma during the year 1924. . Tonkawa contributed the deep "Slick Sand" bit apparently its 'peak has been reached and like other pools producing from below the Mississippi lime its decline' mill be rapid. After reaching a daily production of 67,000 bbl., the Cromwell Pool is declining because of a lull in -new completions, but a mile extension has revived activity and an area equal to that of the present producing' area is under development and will cause an increase in the present production of 38,000 bbl. This pool is seven months old, has three dry holes in one hundred twenty completions and is actually defined only on the southern extremity. This area has been one of the chief contributors to the .over-production of high gravity oil in the Mid- continent fields and will be such' for the remainder of ' the year. 1924 and first part of 1925.

Jan 1, 1924

By Alexander I. Raitchenko

"An electroconductive viscous liquid may flow in laminar or turbulent regime under Lorentz-force generated by the intercrossed electric current and magnetic field. When there is a starting flat layer between hard and free boundaries with surface tension the spatial Lorentz-force can create a specific stationary regime of flow: the plane free surface will transform into the wavy one, and the movement in the depth will be not laminar and not turbulent, but this regime will be characterized by organized forms with indications of ""rolling of long cylindrical drops"". Wave-length is determined by the viscosity, the density, the surface tension, the average thickness of layer, and Lorentz-force. ·The limit of wavy regime is determined by most long of wave which is directly proportional to the critical value of specific flow and inversely proportional to the kinetic viscosity. The proper critical value of Reynolds number is determined by the dimensionless combination containing surface tension, density, viscosity, and Lorentz-force. The mentioned dimensio.nless combination in our case is some criterion substituting the known Kapitsa number for case of the thin viscous liquid layers under gravity. Spreading of admixture by mechanism of wavy regime is more rapid than by common diffusion or by laminar flow. The suggested conception can be a contribution into the theoretical basis for elaboration of some specific liquid metals technologies."

Jan 1, 1999

By Bill Tucker, Mike Black

"PROJECT OVERVIEW Crossrail, Europe’s largest construction project, will increase London’s transportation capacity by 10% when it opens in 2018. The Crossrail scheme is a combination of surface and underground railway that stretches 118km east-west through central London from Reading, Berkshire and Heathrow airport in the west to Shenfield, Essex and Abbey Wood in the London Boroughs of Greenwich and Bexley in the east. Crossrail will serve 40 stations, ten of which are new, and bring 1.5 million people within 45 minutes commuting distance of London’s key central business districts. 21km of the Crossrail route comprises twin-tunnels beneath the heart of central London. It is the central section of the route, and the challenges that had to be overcome to construct its tunnels under the historic capital that forms the subject of this paper. The route of the Crossrail tunnels can be seen in Figure 1. These tunnels weave their way through the city’s underground landscape, linking eight new underground stations which connect to the existing London Underground network, providing interchanges with nine existing lines as well as the National Rail and Docklands Light Railway networks.Crossrail began construction of enabling works in May 2009 and launched the first of eight tunnel boring machines (TBMs) in May 2012. 42km of major tunneling work was completed in May 2015, and included 11km of sprayed concrete lined tunnels at the five mined stations (Bond Street, Tottenham Court Road, Farringdon, Liverpool Street and Whitechapel) in addition to the bored tunnel sections. The remaining three sub-surface stations at Paddington, Canary Wharf and Woolwich were constructed as large open boxes prior to the TBMs passing through. Crossrail, Ltd. is a special purpose company formed by the project’s joint sponsors, Transport for London and the Department for Transport, to manage design, construction and commissioning of the project. In 2009, Crossrail engaged Bechtel Ltd. as its delivery partner and a joint venture, Transcend (comprised of CH2M, AECOM and the Nichols Group), as its programme partner. The project is being managed by an integrated programme management team which is staffed by Crossrail and its partners. The railway, when opened, will be operated by Rail for London. With tunneling completed in accordance with the project’s master control schedule, the new railway is scheduled to commence dynamic testing in late 2017, with a phased opening of the tunneled sections and stations through Central London in 2018."

Jan 1, 2016

By K. E. Waters, J. E. Nesset, F. Rosenblum, R. Langlois, J. A. Finch

"Some sulphide mineral mixtures when exposed to air and a warm and humid environment can exhibit a self-generating temperature rise, referred to as self-heating or spontaneous heating. The observed self-heating derives from the oxidation reactions of the active sulphides. In previous publications by the authors, it was proposed that the self-heating of sulphides proceed in three distinct stages; namely, Stage A, Stage B and Stage C. In Stage A (<100OC) the sulphides, in the presence of moisture are oxidized, generating heat through a series of sequential reactions and forming elemental sulphur as one of the products. In Stage B (>100OC) the elemental sulphur produced in Stage A is further oxidized to generate additional heat and SO2. Stage C (>~380OC), sometimes referred to as thermal runaway or roasting, is not addressed in this paper. This communication focuses on the type and role of elemental sulphur found in Stages A and B, and the sequence of reactions that is occurring in Stage A. The sequence is divided into two phases, the first based on galvanic interaction between the sulphide minerals that generates an acidic environment but little heat, and the second involving the production of H2S which rapidly oxidizes to produce heat and elemental sulphur. To date, data suggest that the primary oxidation product formed in Stage A is the stable orthorhombic a-S8 form of elemental sulphur. Above 96OC the a-S8 transforms to a monoclinic ß-S8 structure which is less stable and will readily oxidize to generate heat and SO2. Above 159OC a proportion of the ß-S8 sulphur will transition to a polymeric Sµ form of sulphur which can readily volatilize. INTRODUCTION Some particulate and granular materials, when exposed to appropriate atmospheric and physical conditions, can exhibit a self-induced temperature rise resulting from accumulated heat due to internal exothermic oxidation reactions. This phenomenon is commonly referred to as self-heating or spontaneous heating. Under favorable physical and environmental conditions, these reactions can elevate the temperature of a given material from ambient to the point of auto-ignition. Self-heating behaviour should not be equated to pyrophoric behaviour which describes a group of materials (e.g. certain finely powdered metals) that will ignite spontaneously in air below 55OC. There are numerous materials such as coals, hay, forestry wood products, food products to name a few that can exhibit self-heating behaviour. This publication continues the focus of the authors on the self-heating of sulphide mineral mixtures. Many of the metals of commercial use found in nature are in the form of these sulphides which must be mined, crushed, ground and concentrated prior to smelting or hydrometallurgical processing in order to produce primary metal. The issues of sulphide self-heating therefore pertain to the mining and processing of metals."

Jan 1, 2018

By V. (“Viv”) R. Forbes

[ ] INTRODUCTION "The Liberal Party believes that the State&apos;s mineral resources belong to the people of Queensland and therefore it is essential that the state, on their behalf, obtains maximum benefit from the development of those resources." (Liberal Party, 1980 "Mineral Resources Policy" p.2). "Unless sound policies are implemented.... increased production of minerals will benefit only the already wealthy and the lucky few... A resources tax is essential to ensure that above normal profits are shared by the whole community.... Labor policies on taxation must ensure an adequate return from mining developments to the Australian people." (Labor Party Policy Paper, May 1982 "National Issues relating to rapid expansion of mineral production during the eighties". p.1, 37, 47). Judging from these statements, key political parties in Australia believe that mining profits are lightly taxed and that shareholders get most of the benefits. THE REALITY The Government Share of Income statement in Table 1 attempts to measure the government share of the income generated by the "Big Five" Australian mining companies - Broken Hill Pty Ltd. (BHP), CRA Limited, Utah International, MIM Holdings Ltd., and Western Mining Corporation ("WMC"). These companies control over 70% of Australia&apos;s mining industry including all the most profitable mining operations. They dominate the mining and processing of iron and steel, aluminum, manganese, coal, oil and gas, copper, lead, zinc, silver, nickel, gold, ferro-alloys and salt in Australia. They are also major world exporters of most of these products. They are thus a representative sample of the profit-earning side of the Australian mining industry. In their two most recent financial years these five companies had income before tax of A$6,980 million. The Government share of this income was A$6,285 million or 90%. The total market capitalisation of the Big Five is about A$8,480 million. (December, 1982). Governments thus consumed the equivalent of 82% of their total value in just two years. This was taking place while the politicians drafted the above statements calling for an "adequate" share for the people.

Jan 1, 1985

By E. J. Hammer

In the crushing and grinding of metallics for beneficiation, the sizing is normally done to liberate the metals or sulphides for further processing to improve recoveries of the basic metals or minerals. The objective is to reduce the ore in size through various closely controlled stages to that degree of fineness which gives an economic liberation of valuable mineral, but which avoids as much as possible the production of sliming fractions. A different philosophy applies to the crushing and grinding of Gypsum. Our requirements normally demand controlled grinding and/or crushing of the material not only to a fineness suitable for further processing of the mineral into end products, but to produce various sizes of material which are them- selves saleable products. The majority of our tonnage ultimately ends up in stucco for Wallboard. Therefore, our mineral reduction is normally designed toward this end, but it is done in a manner that permits drawing off inter- mediate products to meet various Customer requirements. This forces us into compromises at times in our equipment installations, and our equipment must sometimes be more versatile and complex than we would like it to be. We try to process our basic rock, Gypsum, for the most efficient size reduction. We market 5 to 6 different sizes intermediate to the end product, which generally is the fineness of material to be used for stucco for Wallboard, and we do this with controlled crushing, grinding and sizing cycles of the material. To summarize, we use a different philosophy of crushing and grinding than the metallic field which uses comminution or crushing and grinding to improve recovery, whereas we choose our equipment to crush and grind primarily for product performance.

Jan 1, 1969

In November 1999 Waihi Gold Mining Company commissioned its new crushing and conveying plant used to transport both ore and waste from the Martha Mine to its ore processing plant and also its tailings dam construction area. To date, a record monthly throughput of 854 000 tonnes throughput has been achieved. This paper outlines the measures taken subsequent to the commissioning of the system to achieve greater than design throughput and to mitigate the environmental and safety issues associated with operating the system in the middle of a town.

Jan 1, 2001

By B. D. Cullity

GOLD and beryllium form an intermediate phase composed of the two metals in equal atomic proportions and having the formula AuBe. According to Winkler,1 this phase probably exists in two modifications: beta, stable below about 600°C, and alpha, stable between 600°C and the melting point, about 740°C. Only the low- temperature beta form will be considered in this paper. EXPERIMENTAL PROCEDURE The gold used had a fineness of 999.75 to 999.85, balance mainly silver, and the beryllium purity was better than 99.8 pct. AuBe was prepared by melting the constituents in a beryllia crucible in an evacuated induction furnace. After melting and thorough mixing, the alloy was allowed to solidify in the crucible. No difficulty was encountered in obtaining a homogeneous ingot. Both chemical analysis and microscopic examination of the ingot showed that the alloy was essentially one phase, containing 50 at. pct gold. The alloy was quite brittle and powder samples could easily be pre- pared by grinding in an agate mortar. The X-ray diffraction patterns were made with CuK-alpha radiation in a Debye-Scherrer powder camera 57.3 mm in diameter. The film was placed unsymmetrically in the camera in order to afford a basis for am-shrinkage corrections. A sample homogenized at 5o0°C gave the same diffraction pattern as a sample taken from the as-melted ingot. GENERAL RESULTS The diffraction pattern of AuBe was readily indexed on the basis of a simple cubic lattice with ao = 4.659 ± 0.001kX. If the unit cell is assumed to contain four AuBe "molecules," the calculated X-ray density is 13.46 grams per cc as compared with the measured density of 13.55 gm per cc. The only missing reflections in the dsraction pattern are (100) and (220) (see Table I). Since these missing reflections are not those characteristic of body or face centering, the lattice of AuBe must be simple cubic. To locate the positions of the atoms within the unit cell, two possibilities had to be considered: I. The structure was disordered and there were eight positions to be filled by an "average" gold-beryllium atom. That the structure was disordered seemed unlikely since the lattice parameter did not vary with composition in alloys containing some- what more and somewhat less than 50 at. pct gold, indicating a fixed composition for AuBe.

Jan 1, 1947

By R. A. H. Lycett, P. R. Jochens, D. D. Howat

The crystallization of rutile from titaniferous slags by R. A. H. LYCETT, M.Se. (Eng.),"A.M.I.M.M. (Visitor), P. R. JOCHENS, Pr. Eng., M.Se. (Eng.) (Rand), Ph.D. (Member), and D. D. HOWAT, B.Se., Ph.D., F.R.I.C., F.I.M. (Fellow) Factors affecting the precipitation of rutile from smelter slags were investigated, with particular reference to the effect of additions of phosphorus pentoxide to the slag. The phases were identified and the phase boundaries determined for slags having phosphorus pentoxide additions of 0 to 50 per cent. The liquidus temperatures of these slags were determined, and a pseudo-binary phase diagram was constructed. Rutile crystallized as the primary phase from melts having a phosphorus pentoxide content of more than IS,S per cent. Prismatic rutile crystals whose TiO. content was more than 97 per cent were grown from melts that had a phosphorus pentoxide addition of 30 per cent. However, the morphology of the precipitated rutile was such as to make subsequent separation impracticable.

Jan 9, 1975

By G. Cartaud, F. Osmond

WE have already devoted two previous memoirs to this question. In the first we collated and discussed the existing literature on the subject; in the second, we described the crystalline forms obtained by the reduction, at different temperatures, of ferrous chloride by hydrogen or by zinc-vapor. The conclusion from these researches was that the three allotropic states of iron-a, stable below A2; 19, stable between A2 and A3; and 7, stable above A3-all crystallize in the cubic system. The differences observed were such as are customarily encountered in the crystallographic records of many minerals of which allotropic varieties or isomerides are not known, but did not conform to the ordinary definition of polymorphism. It is, however, improbable that allotropic transformations, which are placed beyond doubt by a series of positive facts, do not involve some changes in the intimate structure. As a matter of fact, the crystals we did obtain were too small to allow of a precise examination, and this might introduce an element of uncertainty in the firm establishment of our conclusions. Professor H. Le Chatelier was even led to think from some of our results that iron could very well be a rhombohedron simulating a cube, and not a true cube, and it will be remembered that the crystalline form of bismuth was for a long time incorrectly regarded as cubic. Allotropy does not, however, necessarily involve such a deduction. Without departing from the cubic system at all, a whole

Nov 1, 1906

By J. E. Rowland

NIOCALITE is a new mineral species which has been identified in rock from the Oka district, Quebec. It occurs as prismatic crystals up to l 0 mm. in length and I mm. in width, in coarse, white, crystalline calcite with associated apatite, diopside, biotite, pyrochlore, and niobian perovskite. The crystals of niocalite are light yellow in col-our and have a vitreous lustre. The optical properties of niocalite (I) are as follows: Biaxial negative -2V = 56° a = 1.700, [ ] = 1.730 Birefringence y -a = 0.030 Optic orientation: X = b, Z/\c 12°, Y , /\a = 32° The specific gravity is 3.32 and the hardness is approximately 6 (Mohs scale). A detailed analysis performed on 2.4 gm. of hand-picked material reveals that niocalite is essentially a calcium niobium silicate. Table I gives the result of the analysis. Crystals of niocalite, apparently suitable for X-ray diffraction work, were selected, and single crystal photographs were obtained using both Weissenberg and Precession cameras. Initial difficulties were encountered in interpreting these films, and in correlating the crystal data with the optical data. The in-consistencies were explained by the fact that every grain examined was twinned to some extent.

Jan 1, 1957

By T M. Brettell, D Sidea

The CSA Mine is located in Cobar, New South Wales and is operated by Glencore. Large scale underground production started from 1965, with zinc, lead, silver and copper extracted in the past. The current operations focus on copper, with a silver co-product.From 2014 to 2016, Cobar Management Pty Ltd (CMPL) undertook a major capital project to upgrade the primary ventilation system at the CSA Mine. This involved the development of ten raises using full-face raise boring from surface to a depth of 1450 m. The total length of the raises was approximately 2500 m. Geotechnical conditions were identified as a key project risk during the early planning stages of the project. Timely quantification of the geotechnical risks was required to minimise project delays and cost overruns. Geotechnical investigations were planned and conducted for each raise prior to pilot drilling and full-face back reaming.Nine of the ten raises had final wall camera and laser baseline surveys completed following full-face reaming. The surveys were conducted progressively, allowing ongoing back analysis and calibration of geotechnical evaluations as the project advanced.This paper presents the design and planning process of the raise bored excavations. It details the geotechnical investigation work undertaken to mitigate the geotechnical risks and the challenges and learnings from the project including the benefits of close collaboration between the parties involved.CITATION:Sidea, D and Brettell, T M, 2017. The CSA ventilation upgrade – geotechnical challenges and learnings, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 341–352 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

Computer programs for the storage, retrieval and use of basic thermodynamic and physical property data for chemical substances are described. Methods are presented for the collection, critical assessment and pre- processing of source data for files containing enthalpy, entropy and heat capacity data for 3000 compounds, enthalpy and excess entropy for 200 dilute solutions and critical propert- ies and vapour pressure for 600 compounds. Retrieval programs are discussed which allow the tabulation or plotting of many basic and derived thermodynamic properties for chemical substances or balanced reactions. Examples are given of the use of such data to infer the stability or corrosion resistance of materials and the feasibility, yield and heat release of reactions. A general purpose calculation program is discussed which allows the equilibrium compos- ition to be found for complex systems with many species and phases, using the method of Gibbs energy minimization. Methods of correction for non-ideal behaviour in these systems are discussed, as well as methods for fixing, maximizing or minimizing any desired property of the system. Examples are given of the simulation of various laboratory Experiments and industrial processes by this method.

Jan 1, 1977

By D. Küster, G. Franken, P. Schütte, J. Vasters

The CTC (Certified Trading Chains) mineral certification system has been piloted in Rwanda since late 2008. CTC project implementation is jointly driven by the Federal Institute for Geosciences and Natural Resources (BGR) and the Rwanda Geology and Mines Authority (OGMR), in cooperation with other national stakeholders. Five Rwandan mineral producers participate in the CTC project with their flagship mining concessions. Based on independent third-party audits, CTC certifies supply chain due diligence measures of these companies engaged in the artisanal mining sector through on-the-ground assessments of mining conditions, transparency, as well as mineral origin and traceability. The CTC system thus allows responsible mineral producers and their clients to verifiably demonstrate supply chain due diligence and good governance in conflict-affected and high-risk areas.

Jan 1, 2011

By Fiseha Tesfaye, Pekka Taskinen, Daniel Lindberg

Due to increasing complexities of raw materials for base metals production the conventional pyrometallurgical processes are challenged. To make the appropriate modifications, thorough evaluations of the thermal stabilities of phases and phase assemblages which are commonly encountered in these processes are essential. In this work, phase relations and thermal stabilities of equilibrium phases in the Cu-Ni-S system have been reviewed. The calculated phase diagram of Cu-Ni system has been validated. At T < 630 K, in the Ni-rich corner, large scatter in data has been observed and discussed in detail. The other binary systems, Cu-S and Ni-S, have been also critically reviewed together with the ternary Cu-Ni-S system. The reviews were focused on compiling and discussing phase relations and thermal stabilities of the selected systems in the pyrometallurgical processes of Cu and Ni productions.

Jan 1, 2016

By R. D. White

"The Cumberland Basin of Nova Scotia has long been considered a structural basin by virtue of the elliptical outcrop and inward dip pattern of the Pennsylvanian outcrops. Recent published and unpublished data indicate that subsidence began in the late Devonian, perhaps resulting from a graben or rift. The Mississippian sediments which filled the growing depression were continental, lacustrine and marine with evaporites. The cessation of the riftforming processes is recorded by the alluvial swamp-type sediments of the Pennsylvanian which filled the depression. In excess of 25,000 feet of Carboniferous rocks are believed to be present in the deepest part of the Basin. Starting with the rift hypothesis, we can speculate on the kinds of sediments, their location and the structural features present beneath the Pennsylvanian surface. Using surface exposures and a limited amount of subsurface data, we theorize that (1) the Mississippian evaporites acted as glide zones which effectively divided the Basin into two horizontal structural layers. The rocks above the evaporites, responding to Appalachian stresses, formed the long diapiric folds with cores of overthickened evaporites. Below the evaporites the structures are related to movements of the rift floor, compaction closures and structures formed by differential horizontal movements of the rift walls. (2) The rift, in its deeper parts, will have more and a greater variety of marine rocks than the outcrops indicate. Should the rift hypothesis be correct, the possibility of finding hydrocarbons is enhanced."

Jan 1, 1972