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By Jafar Safarian, Merete Tangstad, Leiv Kolbeinsen

"Silicon and its binary alloys have several applications in metallurgical, chemical, photovoltaic and semiconductor industries. Silicon goes to its liquid state within its production, refining and when it is alloyed with other elements. Therefore, the characterization of silicon melts thermodynamics is important and useful. The liquidus and activities in several silicon binary systems have been recently calculated by the application of two liquidus constants, which were established using the experimentally determined liquidus data. In the present study, the thermodynamic properties of six silicon binary melts, which are simple eutectics, are calculated by analytical approaches. In this case, the changes in the partial and integral Gibbs free energies and enthalpies of mixing are calculated and compared with the experimental data in literature. The enthalpies are calculated by two methods and the calculation results are compared to the data from the literature. It is shown that thermodynamic properties of silicon binary melts can be accurately predicted without the use of complicated thermodynamic software.IntroductionSilicon and its alloys have several industrial applications. Silicon is used for making aluminium-silicon alloys to produce cast parts, mainly for automotive industry. Silicon in the form of ferro-silicon is used to deoxidize and alloy steel and cast iron. The photovoltaic (PV) industry has had a rapid growth in the recent years and silicon is the dominant material used for the fabrication of solar cells. Silicon is primarily produced through carbothermic reduction of quartz in electric arc furnaces and the produced metallurgical grade silicon (MG-Si) contains around 1 wt% impurities. It is further refined to produce solar grade silicon (SoG-Si) with above 99.9999 wt% Si to fulfil the chemical requirement for PV application. Since molten silicon is processed all along the metallurgical route, obtaining fundamental thermodynamics knowledge about silicon melts is valuable for the related industries."

Jan 1, 2012

By M. Sadegh Safarzadeh, Erich U. Petersen, Jan D. Miller

"An acid bake-leach process has been identified and applied to an enargite concentrate containing ~67% enargite, ~27% pyrite (FeS2), ~3% chalcopyrite (CuFeS2), ~6% sphalerite (ZnS) and <1% galena (PbS). Sulfuric acid baking of this concentrate resulted in the transformation of the concentrate to S8, As2O3, HFe(SO4)2•4H2O, PbSO4 and Cu0.47Fe0.53SO4•H2O, all of which (except elemental sulfur and PbSO4) dissolved during the water leaching step. More than 87% Cu and 64% As were leached when the concentrate was baked at 200°C over 7 hours with a sulfuric acid-toconcentrate weight ratio of 1.6. Less than 1% As was lost to the gas phase. Upon water leaching, copper and arsenic were released to the solution at a concentration ratio of about 3:1. While enargite is very reactive during the sulfuric acid baking reaction, other minerals present in the concentrate such as pyrite, galena and sphalerite may compete to consume sulfuric acid and be converted into their corresponding sulfates at different concentrations. The purpose of this paper is to present our examination of the effects of sulfuric acid dosage on the extractions of Cu, Fe, and As from an enargite concentrate. In this regard, the concentrate, baked concentrate, and the leach residues are characterized and a conceptual process flowsheet is described for the acid bake-leach process for the treatment of enargite concentrates.IntroductionThe occurrence of enargite (Cu3AsS4) in copper ores and concentrates and the associated high arsenic values in such resources have resulted in a considerable decrease in the demand for such concentrates because they cannot be economically processed using conventional technologies such as smelting and atmospheric leaching (Mihajlovic et al., 2011). The exploitation of such problematic deposits through competitive treatment strategies will be required in the near future in order to satisfy increasing pressure from the copper market. It is expected that the average arsenic grade of copper concentrates will increase from 0.17% in 2008 to 0.22% by 2020 (Mayhew et al., 2011).The acid bake-leach process was identified and selected for further investigation at the University of Utah as a possible process alternative for the treatment of enargite concentrates. In this case, adequate amounts of concentrated sulfuric acid are mixed with the concentrate and heated to the temperature range 150-300°C. Subsequently, the baked material is leached with water/weak acid and the acid bake-leach process has some advantages over conventional sulfuric acid leaching (Prater et al., 1970). During water leaching, metal sulfates are released in solution, after which they can be extracted through well-known hydrometallurgical techniques. While the majority of the work has been done on oxide minerals, there is a limited record of sulfuric acid baking of sulfides."

Jan 1, 2015

By V. F. Hollister

Although it is apparent that porphyry copper deposits may have formed in the Andean orogen from Permian time onward, commercial deposits thus far developed appear to have Cenozoic ages only. Following Chilean useage, the porphyry deposits are divided into either: (a) a stockwork, or (b) a tourmaline breccia model. Stockwork type deposits tend to occur on major strike-slip structures which may be either transcurrent or transverse faults related to plate movements, while the tourmaline breccia type may more frequently form independently of regional faults. Stockwork types may be conjugate fractures that intersect and ramify as a network of veins and veinlets, cutting altered rock, and genetically related to a major regional fault, or in other cases they may reflect the intersection of two large fault structures. Circular fracture patterns may more rarely occur in stockwork deposits in response to a specific intrusive. Tourmaline breccia types are characterized by circular and radial fractures genetically connected in some way with tourmaline breccia pipe development or an intrusive piercement that preceded it. Each structural model contains mineralized intrusive8 which have a close time-space relationship to ore and in each model, mineral paragenesis is similar, regardless of age or location in the plate. Also, each model contains the same type of alterntion halos (phyllic, argillic, prophllitic) as are developed in intru- sive centers in porphyry copper deposits found in North America. The potassic zone is exposed best in the older deposits. Examples of each type of deposit are illustrated, demonstrating the feature evolved.

Jan 1, 1973

By George C. Toland

Most existing impoundment ponds and dams leak effluent into the soil or rock upon which they are constructed. However, proposed environmental legislation will require very stringent control on the release of toxic effluents such as cyanide. More exacting investigation, design, and construction techniques than have been used in the past will be required to satisfy these new regulations. This paper discusses the types of field and laboratory investigations required to develop the data for the design of an impoundment system containing toxic effluent, and discusses in detail technical considerations necessary to design this system. Design topics include reservoir sealing with natural and man-made materials; embankment sealing; embankment design considering stability, surface hydrology, capacity, and downstream catchment basins; and special implications of cyanide effluents.

Jan 1, 1975

By Bruce D. Sartwell

A program was written which utilizes a remote teletype input to a time- sharing computer to plot charged particle or X-ray energy spectra which are stored in the memory of multichannel analyzers. The program, written in FORTRAN V, accepts the data printed out by the pulse height analyzer on paper tape and then, after reading these data tapes into the computer, plots on the teletype the desired energy spectra on a scale automatically adjusted for the maximum number occurring in the data. The program is flexible enough so that the researcher can subsequently expand or contract the vertical (intensity) or horizontal (energy) scales. With a slight modification, the program will accept data printouts from scalers or analog to digital converters. The program also includes a feature for integrating the energy peaks obtained by pulse height analysis.

Jan 1, 1970

By Immo H. Redeker, O. E. Pothier, E. W. Gieseke

Phosphate rock is the primary source of phosphorus, an element necessary to all forms of life--plant, animal, and human. While phosphorus finds many uses in everyday life, it is an irreplaceable ingredient in all complete plant foods. With the present need for intensive farming, the fertility of the soil can be maintained only by external additions supplied by mines or other sources. A major consideration in any mining operation is to establish the economic and ecological impact of the development on the local population as well as the national interest. The Commodity Data Summaries, as published by the U.S. Bureau of Mines (USBM), is a ready reference concerning the importance of phosphate to the national and local interest. The summary of domestic and world pro¬duction is given in Table 1. During 19722 the demand for marketable phosphate rock exceeded the supply in the United States and the rest of the world. Domestic and world reserves are more than adequate to meet furture demands. Phosphate rock prices firmed and export prices increased, reflecting the change from oversupply to a shortage of phosphatic fertilizers. Demand is expected to exceed supply through 1973. New fertilizer plant capacity planned for 1973-74 will increase the production of phosphate rock by more than 5 million tons in the United States. Morocco and Spanish Sahara are scheduled to increase their production to 18 and 3 million tpy, respectively, within 2 to 3 years. The domestic phosphate rock production for 1972 was 40.8 million tons and 1973 was 42.1 million tons.&apos; Industry, with government-supported programs, will emphasize restoration of mined land and solution of the colloidal slime disposal problem in Florida. The foregoing information comes by courtesy of The Division of Nonmetallic Minerals of the U.S. Bureau of Mines, January 1973. The summary gives a great deal of information but does not give a complete picture. There are many supporting industries which contrib¬ute to the area in which the mines are located. The figures shown in Table 1 deal with concentrates. To produce such concentrates many more tons of waste overburden and ore must be moved. Because of the competitive nature of the phosphate rock industry, data on concentration ratios not only are difficult to obtain but also are not for publication by companies. The concentration ratios vary from one mine to the next in Florida as well as in Tennessee and the western United States. To produce 42.4 million tons of phos¬phate rock in the United States required moving about 350 to 400 million tons of material. Domestic Industry. In 1972 some 26 firms and the Tennessee Valley Authority produced phosphate rock, with several firms produc¬ing from more than one mine. The distribution of marketable phos¬phate rock production was: Florida and North Carolina 82%; Idaho, Montana, Utah, and Wyoming 13%; and Missouri and Tennessee 5%. The value of this production was $223 million. The principal consuming classifications were: agriculture 75%, soaps and detergents 5%, plating and polishing 3%, animal feed supplements 4%, and miscellaneous applications 13%. Over 5,000 firms processed end-prod¬ucts for agricultural purposes. Uses of Phosphate Rock. The tendency in the United States has been to produce more phosphoric acid by the wet process, while the production of electric furnace phosphorus, triple superphosphate, and ordinary superphosphate has been on the decline. Exports of phosphate rock have been on the increase for several years and in 1971 reached 33% of total production. However, export sales of phos¬phate rock are expected to decline in the years ahead, both in total tons of sales and in percentage of production as domestic sales increase (see Table 2). The description and chemistry involved in the production of phos¬phate fertilizers is too complicated to be presented here. The Waggaman13 book is a very thorough reference on the subject involv¬ing production, utilization, and chemistry. The various operations generally have chemical plants near the dry plants or ship to associated chemical plants for further processing. Wet rock, dry rock, and ground dry rock of various grades are sold. In addition various grades of calcined phosphate rock, including defluorinated phosphate rock for animal food supplements, are pro¬duced. Various grades of phosphoric acid, superphosphate, triple suerphosphate, as well as diammonium phosphate, are produced. These products are available from the various producing compa¬nies listed in the text. For prices and specifications the producing companies should be contacted.

Jan 1, 1985

By M Haydon

How do you portray a large structurally and stratigraphically complex deposit to return a meaningful resource estimation, and produce a geological model that is useable for planning on a daily basis? The George Fisher Mine is located 22 km north of Mount Isa and forms part of XstrataÆs Zinc Group operations. It is currently a major producer of zinc, lead and silver in the region with an estimated total resource for all categories of 127 Mt at 100g/t Ag, 5.3 per cent Pb and 9.2 per cent Zn (June 2005). Production in 2005 totalled 2 647 492 wet tonnes for 317 699 kg Ag, 140 317 tonnes Pb and 230 331 tonnes Zn from underground operations. George Fisher (GF) consists of two deposits that are structurally complex on a mine scale, George Fisher North (GFN) and George Fisher South (GFS). Regional faulting has resulted in a 2 km long package of variably pyritic shale and siltstone that separates the deposits. This paper looks specifically at GFN. Distinct correlations exist between the two deposits based on stratigraphic matches; however, orebody characteristics, geometry and fault architectures differ significantly between the two. The deposits consist of multiple, sedimentary-hosted, stratiform orebodies from 2 to 25 m wide, separated by waste intervals of variable width. Each ore-waste interval is modelled as an individual geological domain. Structurally, George Fisher North (GFN) contains a series of major late-stage NE faults with dextral offset(s) of up to 130 m. Further complexity is added by NS, NW and NNE striking fault orientations that can produce either a loss or repeat of stratigraphy, local drag folding, orebody attenuation and block rotation. Due to this structural complexity and orebody offsets, domains at GFN are further divided into fault blocks (FB). The GFN model comprises eight FBs over a strike length of 1 km, all of which are modelled independently. As drilling progresses and additional resources are converted, further FBs will be added at major fault offsets to accommodate orebody and model expansion. This will be in addition to what is already a large and time-consuming data set to manage and update. For example, each FB has 18 domains each with two constraining wireframes (hanging wall and footwall). Each wireframe has several sets of point data depending on the type of data available, ie diamond drilling, mapping or interpretation points. This equates to over 1100 separate files to manage. Additional wireframes and files are also required for major structures, daily planning requirements and block model runs. In total some 1500 files are managed, updated and maintained for GFN alone. The ongoing need to expand as a business and optimise production in the current economic climate where there is a global demand for metal has led to an increase in production at GF. This has resulted in a rapidly growing data set and highlights the importance of practical and efficient modelling to achieve a meaningful resource estimate. This paper focuses on the geological modelling, modelling approaches and techniques employed for the GFN deposit.

Jan 1, 2006

By J. R. Martson

The arrangement of the larger furnace at the United Verde smelter, together with the boiler layout and connecting flues, is shown in Fig. 1. The important dimensions are given in the figure, and cross-sectional areas of combustion space, flues, etc., are recorded. The location and extent of the baffling in the boilers also are shown because of their importance in the interpretation of the data. Two boilers serve each reverberatory furnace. They are of the class M-26 Stirling type (rated at 713 boiler hp. each). Steam is generated at 178-lb. gage pressure at a total temperature of 528" F., from feed water at a temperature of 113" F. The feed water is condensate from turbogenerators plus make-up softened by the lime-soda process. The make-up is rather large in amount as it must match the amount of steam consumed in reciprocating blowing engines and the like, which are not served by surface condensers. As a result the boiler feed water has a hardness of 1.5 to 3.0 grains per gallon, but this results in the formation, during six months to one year of boiler operation, of scale only of "eggshell " thickness or less. The boilers are set at the same elevation as the tapping floor of the furnace, which results in the introduction of the waste-heat gases at the top of the front bank of tubes and necessitates the inversion of the usual baffling arrangements. The boilers are equipped with valve-in-the-head soot blowers, which keep most of the dust blown off the surface of the tubes, but it is necessary to supplement the soot blowers by high-pressure air lances, inserted by an attendant through side doors in the boiler setting. Deposits of coal ash and of dust from the furnace charge accumulate in the flues between the reverberatory furnaces and the boilers and this necessitates cleaning of these connecting flues by hand during the greater part of one of the three 8-hr. shifts during each 24 hr. This cleaning operation requires the opening of clean-out doors, which, of course, has some effect on the yield of steam. Revebberatory Furnace Practice The United Verde furnaces are fired with pulverized coal of sub-bituminous type of which the screen and chemical analyses are given in Table 1.

Jan 1, 1934

By Kasimcan Koruk, Julian M. Ortiz

Building a geological model is important in resource estimation, as it defines the extent of domains for estimation. Geological models are built by assigning a domain to the samples, based on logging of different features related to lithology, alteration, and mineralization. Then, the extent of these domains is determined using geometric or geostatistical tools. However, these models should account for uncertainty, since the actual extent of these domains is not known and must be extrapolated from the labelled samples. With the availability of geochemical datasets and machine learning techniques, employing multiple variables to build resource models should be considered. This article proposes a two-step machine learning approach with an ensemble implementation to define geological domains and their uncertainties. First, an unsupervised binary clustering method labels the geochemical samples into two domains. These labelled samples are used to inform a geological domain model built by support vector classification. This application is repeated with subsets of variables and subsets of samples, leading to an ensemble learning method. Weak models are produced with each subset of samples and variables, and combined to devise a stronger learner. The final model accounts for uncertainties thanks to the ensemble implementation. The proposed workflow is demonstrated on a dataset from a porphyry copper deposit, applied hierarchically to define four domains. Performance is comparable with traditional methods, but provides the advantage of allowing domain knowledge in the selection of the variables, and generates domain boundaries that can be controlled in terms of their continuity and smoothness.

Oct 11, 2023

By Barber S

The Golden Cross Mine is located within the Waitekauri Valley near the southern end of the Coromandel Ranges, eight kilometres north-west of Waihi, North Island, New Zealand. The mine is owned and operated in a joint venture by Coeur Gold NZ Ltd (80 per cent) and Viking Mining Ltd (20 per cent). The underground mine produces gold and silver from low sulphidation epithermal quartz veins which developed in the shallow parts of a meteoric water dominated system during the Upper Miocene (7.36 - 6.67 Ma). The Empire Vein System is hosted within a dilational structural environment which developed at the lithological contact between acid intrusives, rhyolitic-dacitic tuffs and reworked pyroclastics, and undifferentiated andesites. The formation of the Empire Vein System was controlled by the rheological properties of the host rocks and variable displacement along a series of normal, right lateral, easterly-dipping faults. These faults represent sub-parallel zones of master shearing within a Riedel shear model. Underground mining extracts ore from the steeply dipping hangingwall and the complex footwall veins of the Empire Vein System. Initially sills are driven along the hangingwall vein on ten to fifteen metre sublevel intervals. In the footwall zones where significant mineralisation adjacent to the hangingwall sill drives has been identified, a series of cross-cuts and footwall drives (sub-parallel to the hangingwall sill) are also developed. Where continuity of mineralisation and ground conditions permit a combination of post pillar flatbacking and AVOCA longhole benching methods are used. Detailed underground mapping of lithology, quartz veining and major structures provides the information for designing ground support and footwall pillars, planning mine development and ore extraction sequencing. Sectional interpretation displays the vertical extent of faults, fractures and the vein system. The mining methods used underground at the mine have evolved through a thorough understanding of the structural complexity and the systematic geological mapping of the Empire Vein System.

Jan 1, 1997

By Maria I. DeRosa

This Bureau of Mines report describes the Automated Breathing Metabolic Simulator and its hardware and software systems with emphasis on the role exerted by the software program subroutines in controlling the hardware mechanisms during the simulation of man&apos;s respiratory and metabolic functions.

Jan 1, 1978

By AIME AIME

THE best meeting ever held, was the opinion expressed by a number of those who attended the annual meeting of the Institute in New York, Feb. 18 to 21, and there was an atmosphere of friendliness and good fellowship about it that fully justified the feeling. In numbers it was not quite so large as last year and unless the Engineering Societies should build for themselves a new building it is probable that no meeting can be larger, in respect to numbers, than that held in 1928, which was only made possible by the circumstance that the eighth floor of the building happened to be, temporarily vacant at the time. The number of rooms available for -sessions that were provided when the building was built long ago proved inadequate, and it is only by the expedient of obtaining the temporary use of the board and committee rooms of other societies that it is possible to arrange for the over 40 sessions that must be spread over the four days of the meeting. The-fifth floor, where. a buffet lunch is served each-day, has reached its full capacity and it seems quite evident that any future development of Institute meetings must be along the lines of quality, not size.

Jan 1, 1929

By T. T. Wang, T. H. Huang, Y. C. Chiu

Quantitatively analyzing deformation of a tunnel with lining anomalies for structural safety evaluation is essential for sustainable tunnel engineering. However, a complete theory and associated methodology accounted for displacement of a built tunnel is absent. This manuscript introduces a novel characteristic matrix method proposed by the authors which is an integrated procedure that analyzes displacement of rock tunnels in operation. First, establish a numerical model expressing a specific state of the tunnel in interest. Derive the characteristic displacement modes by a unit disturbances and check their independency. Once the characteristic displacement modes are proved to be orthogonal (independent), they are ready for use. Given a tunnel displacement, modal decomposition returns the magnitude of each characteristic displacement modes that together consist the given displacement. By realizing the definite value of horizontal and vertical translation, rotation, uniform compression/expansion, elliptic deformation, triangular deformation…etc. for a tunnel displacement, one can distinguish tunnel displacement and deformation types from their modal composition. A circular tunnel with elastic structure and surrounded by elastic rock mass is chosen to demonstrate the outcome of characteristic modes and how they work. The influences of tunnel shape, elastic modulus ratio between rock mass and tunnel structure, and numbers of monitoring points on a tunnel profile were also discussed. Identifying possible tunnel deformation causes is attainable if further connections between mode combination and force increments were built.

Jan 1, 2015

By K. M. Wild, C. D. Martin, F. Amann

"Argillaceous rock formations, in particular clay shales, are notorious for creating challenges in rock engineering. Due to their generally low hydraulic conductivity and their complete saturation in their natural state at depth, the behavior of clay shales is usually characterized by a strong hydro-mechanical coupling.This paper presents typical pore pressure responses monitored in different underground rock laboratories and explores alternative ways for their interpretation. The underpinning processes and their relevance are identified based on analytical and conceptual numerical models. Pore pressure monitoring data from Opalinus clay at the Mont Terri Underground laboratory, the Boom Clay at the Mol facility and the Callovo-Oxfordian clay in the Meuse/Haute–Marne URL show a similar pore-pressure response associated with stress changes accompanying tunnel construction although the tunnels were built in different rock types, at different locations, and under different in-situ conditions.The numerical analyses in this study shows that the pore pressure response around an excavation in low permeable clay shales may have different explanations. Pore pressure drops observed in the tunnel near field can theoretically be explained by both, a pure elastic response in an isotropic or anisotropic rock mass with an anisotropic stress state, or a inelastic response and related dilatancy. However, a comparison between the numerical models and the in-situ measurements revealed that the latter is more likely. This conclusion is justified by the observation that pore pressure drops occur significantly ahead of the tunnel face which is not the case in elastic numerical simulations. Pore pressure measurements in the far field, where failure processes are unlikely to occur, can only partly be explained by a linear poroelastic models. The introduction of an anisotropic material plays a key role in reproducing the responses, conceptually."

Jan 1, 2015

By Engineering Staff

"This paper briefly describes the surface mining operations at Smoky River Coal Limited (formerly McIntyre Mines Limited, Coal Division) near Grande Cache, Alberta. Geology, mining methods, equipment, manpower and reclamation and environment topics are discussed. Introduction Smoky River Coal Limited, a wholly-owned subsidiary of McIntyre Mines Limited of Calgary, Alberta, produces a high quality, low sulphur, low volatile bituminous coking coal from its minesite located at west central Alberta, approximately 20 km from the town of Grande Cache and 360 km west of Edmonton (Fig. I). Most of the coal property is contained within a 30 km long by 20 km wide block lying in a northwest-southeast direction in mountainous terrain. Elevations vary from 920 m above sea level ·at the plant·site on the Smoky River to 1,600 mat the upper levels of current and proposed mining operations. A total of 11 coal seams have been identified. Only two seams, No. 4 Seam and No. 10 Seam are currently considered of major commercial value. These seams are recovered by both surface and underground mining. Approximately 650Jo of the plant feed coal is obtained from a conventional shovel/truck surface mine; the balance is mined underground by room-andpillar methods. Background In 1921, McIntyre Mines Limited acquired some 26,300 hectares of coal leases at Smoky River. Since then the leases were explored intermittently by different companies including McIntyre. In the mid-l 960s exploration activities increased and several feasibility studies were completed. Development of the area was undertaken by McIntyre in 1968 and, in August of the same year, a long-term contract was signed with a consortium of Japanese steel mills for delivery of 2 x 106 t of clean coking coal for 15 years commencing in 1970. Production was focussed on underground mining, using longwall methods."

Jan 1, 1985

This paper describes the results of a laboratory study on the upgrading of Algoma siderite by the amine flotation of silica and silicate gangue. The experiments indicate that a virtually complete removal of silica is possible in a rougher flotation con-ducted in tap water at natural pH, without prior desliming of the ore. Grinding considerably finer than the apparent liberation size is essential for maximum silica rejection. A cationic collector, Aeromine 3037, gave best results when used in combination with a modifier. Of the several modifiers tested, a Dutch potato dextrin, Dextrin 4356, was found to be the most effective. Both iron recovery and the grade of the final iron product are enhanced by floating the pyrite contained in the ore prior to the amine flotation of the silica, and by scalping the magnetics from the silica concentrate. F OR over twenty years, the Algoma Ore Properties Division of The Algoma Steel

Jan 1, 1963

By K Hooper

Over the past 20 to 30 years statistics as a science has grown in significance. Not a day passes without reference to the latest statistics by the print, audio and audio-visual media. The Northern Territory Government has been part of this growth and like other public and private sector organisations collects a broad range of statistics. The Northern Territory Department of Mines and Energy participates in the government&apos;s statistics collection process. Statistics collected and published by the Department of Mines and Energy include geoscientific; mining and exploration tenure; environmental (e.g. mine site waste water management); production of minerals, oil and gas; mining sector employment; and occupational health and safety. The importance of statistics collection to the Northern Territory Government is discussed in the paper.

Jan 1, 1994

By L. A. Wrigglesworth, A. S. Dadson

The orebodies of the Giant Yellow-knife mine occur in zones of schist, in an assemblage of typical Precambrian greenstones which form part of the Yellowknife Greenstone Belt. One of the most interesting problems at the mine concerns the fold-like attitudes assumed by the schist zones. The internal structure of the zones and orebodies provides much evidence of folding. A logical conclusion would be that the zones represent a single horizon which has been folded and drag-folded in the ordinary course of mountain building. However, surface mapping, and correlation of certain marker horizons, in underground work, indicate a homo-clinal succession of steeply dipping flows. If this concept of the geology is correct, the zones must cross-cut the regional strike at a small angle and, in the over-all aspect, the regional dip at a large angle. A mechanical interpretation of the zone structure is presented as a suggestion for the present until new evidence is found.

Jan 1, 1959

By J. S. Kirkaldy

A theoretical procedure is demonstrated for calculating two-dimensional binary cellular single-valued interfaces and extended to triple-valued (remelt) shapes. The numerical calculations for the single-valued local equilibrium problem which yield unique shapes as functions of the supersaturation parameter a and the partition coefficient k are reviewed. The cell amplitude L and wavelength A scale identically as the inverse velocity to the 112 power and the aspect ratio r is a constant equal to 312, independently of a and k for a < 0.5.. For 0.5 < a < m, L, A and r decrease asymptotically to zero indicating the finite amplitude nature of the instability at a = 1 and the existence of sub-marginal states which converge to a flat interface at a- m (Glv- m). Scaling comparisons between equilibrium single-valued and triple-valued and deep-rooted non- equilibrium cells are made.

Jan 1, 1992

By U. Caliskan, S. Miskovic

Gravity separation is a technique that depends on the difference in density of minerals for their separation. Although this method is one of the oldest separation techniques, it is still preferred in the industry because of its low capital and operating cost while it is environmental-friendly. In this paper, we present a new numerical methodology that can be used to investigate dynamics of dense slurry flows in gravity separation systems. A simple channel with a set of riffles is selected as a test platform in order to observe the effect of the riffle shape on segregation profile of particles with different densities. It is believed that the riffle shape would affect the slurry flow and possibly cause one class of particles to segregate within the riffle zone. The turbulence, as a disturbance effect within the riffle zone, causes heavy particles to displace the light, that is, the heavy particles will be trapped in riffles, while the lighter particles are carried by water to the end of the channel, which is an example to uninterrupted suspension. MP-PIC model in OpenFOAM is used to study the effect of riffle shape and slurry percentage of solids in this simple gravity separator on particle segregation profile of four discrete mineral density classes, which are Quartz/Clay (SG 2.6), Pyrite (SG 4.2), Chalcopyrite (SG 5.1), and Gold (SG 19.32). Gold particles are found to be readily captured and retained in the riffles because of their high density, while particles with the intermediate densities are more influenced by the flow. The developed model framework has been proven robust and capable of providing physical results even for the flows with a very high percentage of solids, characteristic for mineral processing operations. INTRODUCTION Gravity-based ore concentration techniques make use of differences in density of minerals within an ore to enable separation of valuables from the gangue. As some of the oldest techniques used for ore beneficiation, they are known to offer a range of benefits such as low specific energy consumption and low capital and operating costs (Burt, 1999; Falconer, 2003; Holland-Batt, 1998), however, they suffer from low selectivity, poor separation efficiency, and low capacity. Gravity separation techniques are common practices in the mining industry and are employed widely for the precious mineral concentration, iron ore recovery and coal preparation (Kroll-Rabotin, Bourgeois, & Climent, 2013; Laplante & Spiller, 2002; Williams, 1997). For example, gravity separation systems are highly applicable for precious metal enrichment operations by being included in primary grinding circuits, shaking table tailing separation, pre-concentration of leach feed and flotation concentrate enrichment for both flash and conventional flotation purposes (Burt, 1999; Falconer, 2003; Holland-Batt, 1998; Laplante & Spiller, 2002; McAlister, 1992). Gravity separation can be employed in the copper processing circuits by being integrated into the pre-flotation circuit to capture the gravity recoverable gold (GRG) and any free copper aiming to enhance the gold and copper recovery of the plant. When native copper and GRGs are present in the deposit, this integration not only facilitates plant overall performance via removal of the valuables early in the circuit, but it also reduces downstream operational expenditures due to less retention time of coarser copper particles in the system.

Jan 1, 2019