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By A. A. Levinson, M. B. Kirkley, J. J. Gurney

"Scientific advances in the past decade have greatly clarified our understanding of certain concepts relating to the age and origin of diamonds. These advances are largely the result of geochemical studies of mineral inclusions in diamonds, made possible by modem analytical techniques which enable the accurate chemical analysis of micro-sized particles of the order of 200 microns in maximum dimension. As a generalization, the inclusions indicate that most diamonds formed from either of two rock types, peridotite and eclogite. Peridotitic diamonds have yielded ages of 3300 million years, whereas eclogitic diamonds areyounger and rangein agefrom approximately 1000to 1600million years. Kimberlite and lamproite, the two rock types usually associated with diamonds, typically are much younger than the diamonds they contain. Thus, it is now dear that kimberlites and lamproites are only the transporting mechanisms which brought diamonds to the surface and are in no way related to the formation of most diamonds. The latest concepts which developed during the past decade regarding the sources of carbon for the crystallization of diamonds from peridotite and eclogite, and the mechanisms of kimberlite and lamproite emplacement, IntroductionThe decade of the 1980s has seen major advances in our understanding of the age, origin and emplacement of diamonds. The information presented herein is applicable to virtually all natural diamonds, excluding diamonds related to meteorite impacts. There is still some question, however, as to the applicability of the new information to industrial grade ""fibrous"" or ""coated"" diamonds, and to microdiamonds (< 1 mm). In addition to drawing upon our own experiences, this review is summarized from a voluminous literature and for those interested in the original sources we recommend the books by Mitchell and Bergman (1991), Ross (1989), Nixon (1987), Mitchell (1986), Glover and Harris (1984) and Dawson (1980), and the review articles by Mitchell (1991), Gurney (1989) and Meyer (1985).are also discussed."

Jan 1, 1992

By C R. Evans

Whole-rock and muscovite potassium-argon dates from selected low-grade metamorphic rocks of Precambrian age in the Canadian Rocky Mountains near Jasper, Alberta, were obtained to ascertain the age of the source terrain and the age of the metamorphism. Ten argillites gave whole-rock dates ranging from 270 to 485 million years, dates which are apparently inter-mediate between the age of the source material and that of the metamorphism. "Up-dating" increases with the degree of orientation of muscovite in the cleavage plane, and with the ratio of the muscovite in the cleavage plane to that in the plane of the bedding. Detrital muscovite from four arenaceous rocks gave dates ranging from 1,050 to 1,780 million years. "Updating" increases with decreasing grain size, so that, within the range investigated, the cube of the median diameter (¢) of the muscovite is apparently proportional to the radiometric date.

Jan 1, 1964

By E S. Bernard

Toughness testing of fibre reinforced concrete (FRC) at 28 days age is typically undertaken as part of quality control for the many applications where fibres are used in concrete, including shotcrete, tunnel segments, and cast-in-place tunnel linings. The performance achieved at 28 days is usually assumed to be retained with increasing age. However, as the average strength grade of concrete used in most tunnelling applications, including tunnel segments, has steadily increased over the last 20 years, this assumption is becoming increasingly unviable. This is because for some types of fibre the mode of post-crack fibre behaviour depends on the strength of the concrete and can change from a desirable high-energy pull-out mode to a low-energy rupture mode as the strength and age of concrete increases. This paper describes a series of trials performed over two years in which the American Society for Testing and Materials (ASTM) C1609/C1609M beam tests were used to assess the performance of FRC reinforced with two widely used brands of steel and macro-synthetic fibre. The hooked-end steel fibres used for half the beams exhibited a dramatic fall in performance beyond 56 days age as the mode of failure changed from pull-out to rupture. The other fibre did not exhibit a fall in performance with age. This phenomenon highlights the need to quantify performance of FRC at much later ages when long-term performance is required, for example, to resist seismic events or changes in ground stress due to nearby excavations. As an alternative, a reduction factor may be applied to the performance of FRC mixes for which evidence of satisfactory long-term performance is not?available.CITATION:Bernard, E S, 2014. Age-dependent changes in post-cracking performance of fibre-reinforced concrete for tunnel?segments, in Proceedings 15th Australasian Tunnelling Conference 2014, pp 229–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By William Fink

APPROXIMATELY two years ago the authors obtained data that indi-cated that initial precipitation could not be detected by change of lattice parameter in the aluminum-rich aluminum-magnesium alloys. Some of these data were first published in a brief note in MINING AND METAL-LURGY1. Cast specimens were used at that time and they showed initial precipitation relatively sooner than sheet material of the sane composi-tion. For this reason a more thorough investigation has been carried out using a homogenized aluminum-magnesium sheet containing approxi-mately 10 per cent magnesium. Materials.-The aluminum used in the preparation of the aluminum-magnesium alloy was of high purity, containing less than 0.01 per cent each of iron, silicon and copper. The magnesium was high-purity sub-limed magnesium. Preparation of Alloy.-Approximately 4 kg. of the aluminum was melted in a plumbago crucible in an electric furnace and the magnesium was added. The melt was thoroughly stirred with a graphite rod and fluxed with chlorine gas before casting. The alloy was cast in the form of a sheet ingot in a cold iron tilting mold (approximately 200 by 165 by 40 min.) and into small chill-cast, slabs for chemical analysis (75 by 40 by 5 mm.). The chemical analyses were made upon drillings from the analysis slabs. The analytical methods were those described in "Chemical Analysis of Aluminum," published by the Aluminum Company of Amer-ica. The composition of the alloy was found to be: magnesium 10.30, silicon 0.013, iron 0.008 and copper 0.005 per cent.

Jan 1, 1936

By F. R. Hensel

Up to the present time few attempts have been made to produce hard nonmagnetic materials by heat treatment of austenitic steels. The usual result has been to cause them to pass into the martensitic stage, thus destroying to a great extent the typical austenitic properties, since this involves a transition of a portion of the iron from a face-centered to a body-centered type of atomic arrangement. High-strength nonmagnetic materials such as might be provided by properly hardening austenite are required in the electrical industry for different machine parts. In Europe nonmagnetic retainer rings for restraining the end-turns of the rotor windings in turbo-alternators have been developed as a special application of high-strength austenite. In testing1 a 28,000-kva. three-phase Siemens turbo generator running at 3000 r.p.m. at full load current, the losses in the short-circuit test were 450 kw. for the magnetic ring and 286 kw. for the nonmagnetic, and the difference should be attributable to the magnetic ring. The differences in temperatures during the same test are given in Table 1 and these show the advantage of a nonmagnetic over a magnetic retainer ring.

Jan 1, 1931

By A. M. Talbot

THERE is still considerable controversy as to the exact nature of the mechanism of the age-hardening process, in spite of the many experi-ments already performed. For this reason, a considerable number of typical systems should be examined in detail and their results correlated. Furthermore, the methods of studying the changes that take place during the progress of this phenomenon should be carefully scrutinized and the different methods applied to the same samples, preferably at the same time. The experiments described in this paper are presented to supply information on one age-hardening system and to show how the various methods of investigation compare in their indication of what has hap-pened. In brief, the progress of aging in magnesium alloys containing about 10 per cent by weight of aluminum at different temperatures was followed by measurements of hardness, electrical resistivity, dilation and lattice parameter, and by microscopic observation.

Jan 1, 1936

By F. H. Samuel, J. E. Gruzleski, S. Valtierra, H. W. Doty, N. Andrade

In this work, the age-hardening behavior of cast Al-Si base alloys was investigated. It was found that multiple aging peaks are present in the age-hardening curves of Al-Si-Cu-Mg alloys. TEM observations reveal that the age-hardening behavior is related to the precipitation sequence of the alloy. For the Al-Si-Cu-Mg alloy, the first aging peak is the result from the high-density GP zones, while the subsequent are from metastable phases. The transition from GP zones to metastable phases may be the main reason of the formation of multiple aging peaks.

Jan 1, 2006

By Taehong Kim, Changsoo (Kevin) Moon, Anil Parikh

"This paper presents an overview and performance evaluation for a reconditioned decades aged open type hard rock TBM utilized for the twin running tunnel excavations of the Second Avenue Subway Project in Manhattan, New York. The TBM tunnel lengths are approximately 2,370 m (7,800 ft, east TBM Tunnel) and 2,190 m (7,200 ft, west TBM Tunnel) with a 6.7 m (22 ft) bored diameter. This “senior” TBM mined through metamorphic rocks consisting of schist, granofels, and pegmatite, and encountered various adverse geological structures, including some relatively heavy groundwater inflows. The ground support was generally pattern friction rock bolts, and steel sets were used in poor ground. This paper presents TBM characteristics and the subsequent performance, such as machine utilization, downtime, cutter consumption rate, net penetration rate, and daily advance rate. Machine operating parameters including thrust, torque, gripping force, and cutterhead RPM, are compared with various accompanying ground conditions. The performance changes between the adjacent tunnel sections are also presented. INTRODUCTION Project Overview The Metropolitan Transportation Authority Capital Construction (MTACC)’s Second Avenue Subway (SAS) Program consists of four (4) phases from 125th Street to Manhattan Battery Park along the 2nd Avenue (see Figure 1) in Manhattan New York. As a part of Phase 1, Contract 1 was awarded to S3 JV (Skanska/Schiavone/Shea) to build a TBM launch box and subsequent twin TBM tunnels from 92nd Street to 63rd Street under 2nd Avenue. Contract 1 was one of the key contracts in Phase 1 to pre-excavate through the footprint of the follow-on underground stations (72nd St. Station, 86th St. Station, and 96th St. Station) by hard rock TBM excavation. The project team included Client MTACC, S3 Tunnel Constructors, Designer, Aecom-Arup JV, and Consultant Construction Manager, Parsons Brinckerhoff. The major elements of Contract 1 included construction of TBM Launch Box supported by secant pile and slurry walls and mining of twin TBM tunnels with a combined tunnel length of approximately 4,560 m (15,000 ft). The dimension of the TBM launch box was approximately 247 m (810 ft) long from 92nd Street to 95th Street, 21 m (70 ft) to 24 m (80ft) wide along the 2nd Avenue, and 18 m (60 ft) to 21 m (70 ft) deep from the ground surface. The launch box was later used for the follow-on 96th Street Station."

Jan 1, 2016

By Caisa Samuelsson, Fredrik Engström, Bo Björkman, Margareta Lidström Larsson

"Large amounts of by-products are generated by the Swedish steel industry each year. The EAF-process generates about 400 000 ton of slag, from which 80% is deposit. An alternative to deposit is to use slag as road construction material. However, metal content in the slag can be a problem, due to the leaching. The aim of this work was to investigate how stable these materials are when ageing and kept outside. Five different EAF-slags from domestic steel plants were used in this study. The materials were characterised after 0, 6, 12, 18 and 24 month to evaluate the ageing process. Scanning electron microscope (SEM), x-ray diffraction pattern (XRD) and a standard test for leaching were used. The changes in behaviour differ between the five materials. The total leachability decreases with time for all samples. CaCO3 is formed on slag surfaces as CaO reacts with moister and CO2 in the air. Introduction The slag generation in the Swedish steel industry is about 1.5 million tonnes annually, of which more than 500 000 ton is generated in EAF (Electric Arc Furnace), AOD- (Argon Oxygen Decarburization) converters and during the refining of steel in the ladle metallurgy. Some of the slags are used in different applications, but most of the steelmaking slags produced in Sweden are landfilled today. The chemistry, mineralogy and physical characteristics of slags make it a suitable material in construction, replacing for example, gravel and rock [1]. In some respects, in road construction, it may even be technically superior to virgin material. Slag from scrapbased steelmaking is used for road construction in Europe. The reason for the low utilization in Sweden is mainly due to potential leaching of harmful elements, legislations and competition with easily available natural raw materials. Except the potential leaching, the technical obstacles for not using some slags in construction include:"

Jan 1, 2008

By V. Labiouse, M. Souley, N. Lafrance, C. Auvray

"Chalk rocks have been used for centuries as a strong building material and for the production of lime. The shallow underground room-and-pillar quarries where the chalk was extracted are now abandoned and endure the effects of time and weathering, increasing their risk of collapse. The risk of instability, involving natural or anthropic underground structures, is an issue for more than 10 000 towns in France.In order to investigate the causes of underground quarry collapse and to aid prevention strategies, we carried out a study of the physico-mechanical behaviour and ageing of chalk in abandoned pillars in two underground quarries, in situ-instrumented by INERIS, in the Parisian Basin, France. Core samples were drilled horizontally from pillars in the Saint-Martin-Le-Noeud dolomitic chalk quarry (Oise, France) and the Estreux glauconitic chalk quarry (Nord, France).Uniaxial tests were performed on dry and saturated cylindrical plug samples extracted perpendicular to the cores at regular distances along their lengths. Physical and mechanical properties were obtained. The dolomitic chalk (Saint-Martin-Le-Noeud) exhibits variation in mechanical and physical properties with horizontal pillar depth. Both density and compressive strength seem to increase outwards from the pillar-core to the pillar-wall. This is the opposite of that would be expected from a purely mechanical point of view. SEM analysis revealed progressive degradation and homogeneity of the grains from the edge to the inside of the pillar. At the pillar wall, the crystal faces are well-defined, almost euhedral, and the grains are of variable size. In contrast, at the inside of the pillar, crystals are finer-grained and are anhedral with highly degraded edges. In the physico-mechanical tests and SEM analyses performed on the Estreux samples, no significant variation was observed between the pillar-walls and pillar-core. However, dissolution marks were observed along the entire length of the half-pillar core."

Jan 1, 2015

By ALEXANDRE CALDELLAS BARBOSA

O objetivo desse trabalho é planejar e controlar a chegada de veículos para carregamento nas plantas ArcelorMittal Tubarao e ArcelorMittal Vega, apresentando uma agenda com os horários disponíveis para o transportador escolher. Esse processo de escolha de um horário disponível é suportado por uma agenda gerada pela usina, considerando as restrições operacionais e de capacidade de expedição por ponto de carregamento. Programar a chegada de veículos aumenta a previsibilidade da necessidade de recursos adicionais para realizar o carregamento e assim não gerar filas, não perdendo produtividade no processo de transporte com veículos parados. A ausência da programação tem uma abrangência muito maior que apenas perda de produtividade e atrasos, ela também eleva o custo total de transporte da cadeia de suprimentos. Visando aumentar a competitividade e melhorar a previsibilidade do processo de expedição, foi implementada a solução para regular o fluxo de chegada dos veículos, sistematizando o processo de agendamento do veículo para carregamento.

Oct 30, 2017

By I. Nikolic

Twin-roll casting is an integrated casting and rolling process that involves the continuous solidification of a melt and the plastic deformation of the solidified metal between two rotating rolls. Computer modeling is a valuable tool to help engineers understand the metallurgical process during twin-roll casting. However, commercially available software can only model either the fluid flow/heat transfer of the melt or the plastic deformation of the solid, but not both. In this study, an object-oriented finite element program was developed to simulate the steady-state fluid flow, solidification and plastic deformation of an A7,31 magnesium alloy in a horizontal twin-roll caster. The melt, the mush zone and the solid were treated as a generalized Newtonian flow in an Eulerian reference frame and different constitutive equations were employed to describe the material behaviours. The effect of operational parameters on the solidification process was discussed based on the simulation results.

Jan 1, 2010

By V. A. Temeng, M. Owusu-Tweneboah, K. Awuah-Offei

The mining industry has long recognized the value of dispatch systems in open pit mines as they reduce load and haul costs. Over the years, researchers have proposed many dispatch systems with various limitations and advantages. The simplest dispatch algorithms are the so called 1-truck-for-N-shovels dispatch strategy. These algorithms are limited by the fact that their objective functions do not consider all the objectives of a mine and cannot be applied to all possible truck-shovel configurations. They are also myopic in nature. However, they are simple and computationally efficient and do not require occasional updates of the upper stage problem as required in multi-stage dispatch algorithms. In this work, an agent-based truck dispatch algorithm that conceptualizes trucks as intelligent agents that make autonomous dispatching decisions to maximize their utility is proposed. The advantages of this algorithm includes utility functions that encapsulate all of management’s objectives and agent’s with broad situational awareness. They are also more suitable for autonomous trucks. We evaluate the new algorithm against a simple 1-truck-for-N-shovels dispatch strategies using discrete event simulation. The simulation results show that the new utility function has significant advantages over 1-truck-for-N-shovels inspired utility functions. Future work will incorporate adaptive behavior into the model via reinforcement learning algorithm. INTRODUCTION In an attempt to optimize truck shovel operations in open pit mines in order to reduce the cost of haulage operation, which according to (Alarie and Gamache, 2002) is estimated to be about 50-60% of the total cost of mining, several effective and efficient strategies have been developed. Optimizing truck haulage systems in an open pit mine is one of the greatest challenges of mining engineering and has been the subject of many research projects. It is important that haulage systems are designed to be efficient, in order to minimise haulage cost, improve profitability and increase the total mine value. Although optimizing the number of trucks required in the operation of open pit mines can help reduce the cost, an effective and efficient truck dispatching system add value by ensuring that the available trucks are used efficiently. With truck dispatching systems, the trucks are normally dispatched between the crusher and dumping station (e.g. waste dumps and stockpiles), and the shovels in order to maximize the total output, obtain grades targets, reduce fuel consumptions and other objectives. Truck dispatching, which can have one or more objectives, is typically subjected to certain operational constraints such as truck and shovel capacities, empty and loaded trucks speed, among others. The problems associated with truck dispatching was first mentioned by Dantzig and Ramser (1959) after they made an attempt to determine the optimum routes of a fleet of delivery trucks between bulk terminals and a service stations. The problem occurs in several industrial systems besides mining (Alarie and Gamache, 2002; Gendreau et al., 2006; Rego and Roucariol, 1995). The dispatching problem, also referred in literature as the vehicle routing problem, has seen a number of modifications and extensions with Bertsimas and Ryzin (1991) presenting a dynamic and stochastic vehicle routing problem, and Ralphs et al. (2003) also adding to the original concept, the concept of vehicle capacity routing.

Jan 1, 2019

By Hayward P. G

Complex ores, characterised by intimate intergrowths between minerals, have previously been treated by flotation with limited success. The most common problem has been that the liberation size is often finer than the lower size limit for selection flotation. A technique has been developed in which the problem is overcome by the use of a selective agglomeration procedure in which the values are coalesced with oil to a size suitable for flotation prior to introduction into the flotation machine. A complex lead ore was characterised by QEM*SEM mineralogy as having a mean galena liberation size of 15 ¦m. The best recovery of lead at 50 per cent Pb grade by standard flotation was 53 per cent. After application of the procedure, 86 per cent recovery was obtained after a single cleaner step. The oil functions as a bridging liquid in the presence of conventional collectors which render the mineral oleophillic.

Jan 1, 1991

By William Skinner, Ishmael Quaicoe, Jonas Addai-Mensah, Ataollah Nosrati

To date, intractable ore specific operational challenges such as poor heap geotechnical stability, permeability and high acid consumption rates associated with low grade (~1 wt%) nickel (Ni) laterites still makes the adoption of heap leaching processing unattractive. This paper presents some highlights of drum agglomeration, column leaching and characterization studies undertaken to foster the understanding and knowledge of some of the desirable product attributes of -2 mm and -15 mm, low grade saprolitic (SAP) and goethitic (G) Ni laterite feed ores and their blends (SAP/G). For column leaching, 5-40 mm agglomerate beds were continuously irrigated with 200 g/dm3 H2SO4 solution at 8.5 dm3/m2/h rate over 100 days. Ni, Co, Fe, Al and Mn extraction rates, free acid concentration, agglomerate bed slump and structural changes were determined as a function of time. The results show that at equivalent feed masses, except -15 mm G which displayed slower, pseudo-layering based behaviour, all the feeds (single and blends) displayed coalescence controlled agglomeration behaviour at varying binder dosages. Whilst the agglomerate compressive strength of the G ore was markedly higher than that of SAP ore, those of the blends were substantially similar. At fixed column leaching conditions, the Ni/Co extractions and acid consumption were higher for SAP ore whilst the agglomerate bed slump was lower than those for G ore. The bed of agglomerates produced from -2 mm G/-15 mm SAP blend was more stable than that for the -2 mm G/-2 mm SAP blend agglomerate, the latter experiencing blockage within 24 h of acid irrigation due to agglomerates breakdown. The Ni/Co extractions and acid consumption rates obtained for agglomerates of -15 mm G/-2 mm SAP blend were lower than expected based on the ratios of the SAP and G ores within the blend composition. The findings suggest that judicious saprolitic and limonitic ores’ blending could reduce acid consumption rate, improve the agglomerate bed robustness and enhance bed percolation behaviour under prolonged acid irrigation periods during heap leaching of lateritic ores of variable mineralogy.

Jan 1, 2014

By R. Hogg

The sedimentation and dewatering characteristics of flocculated slurries are determined by the size and density of the flocs. Studies of the formation and growth of flocs reveal that floc size is limited by breakage of the agglomerates due to shear in the suspension. Floc density measurements indicate that there is an inverse relationship between size and density. This relationship appears to be determined primarily by the nature of the solid particles, especially the size distribution, but it appears that agitation of the suspension can lead to some densification of the flocs, in addition to breakage. It follows that both size and density can be controlled to a significant extent by regulating the physical conditions (agitation, method of flocculant addition etc.) during flocculation. The use of physical floc conditioning to control the sedimentation and dewatering (filtration) behavior of flocculated, fine-particle suspensions is evaluated in terms of its effects on floc size end density.

Jan 1, 1986

By G. E. McClelland

Introduction Many discoveries have been made during the-past decade of low grade gold-silver deposits in the western US. This has stimulated development of low cost cyanidation procedures for precious metal extraction. Heap leach cyanidation techniques possess considerable potential for application to these low grade ores, small ore bodies, mine strip waste, and tailing materials where fine grinding is not necessary for good extraction. For heap leaching to be successful, these resources must have good permeability to achieve uniform distribution of the cyanide solution throughout the heaps. Some of the most difficult of the gold and silver ores to treat successfully by heap leaching are those containing excessive amounts of clays, or fines generated by crushing. Presence of excessive amounts of slimes, -50 µm (-270 mesh), in the heap leach feed will slow percolation, cause channeling, or produce dormant or unleached areas within the heap. This may result in unreasonably long leaching periods and poor extractions. In extreme cases, the clays or slimes can completely seal the ore heap. This causes the leach solution to run off the sides of the heap rather than penetrate the ore bed. The problem of heap leaching ores with fines can be aggravated while preparing ore heaps because of the natural sorting of coarse and fine material that occurs. This phenomenon results in concentration or ore fines in the center of individual ore piles and concentration of larger rock fragments of the lower slopes and base of the pile. When the individual piles within the heap are leveled off for the installation of the sprinkling system, additional segregation occurs as the fines sift through the coarser ore particles. This results in localized areas or zones with marked differences in permeability. Consequently, the leach solutions follow the course of least resistance. They percolate down through the coarse ore regions and bypass or barely wet areas that contain large amounts of fines or slimes. Effective use of marginal gold and silver resources by heap leaching required development of new methods to achieve more uniform size distribution when preparing ore heaps and better slime control during leaching. Early methods Agglomeration and balling of crushed ore to produce a porous and more uniform feed material for heap leaching is a viable method for treating clayey ores. Researchers from the US Bureau of Mines in Reno, NV began agglomeration pretreatment research in the mid-1970s for applications to and exploitation of these poor percolating feed materials. Little attention had been given to such methods before the Bureau&apos;s research. In 1905, T. C. Scrutton developed a unique technique for obtaining rapid vat leaching of a clayey ore where the gold was finely disseminated. His technique consisted of rolling the ore down a chute inclined at 60° to form agglomerates or balls readily permeable by the cyanide solution. However, these agglomerates lacked rigidity. And, to ensure good percolation leaching and washing, they could not be bedded in layers more than 1 m (3 ft) deep. If this depth was exceeded, it is difficult to obtain uniform leaching and washing. This results in reduced gold recovery. Shepard and others in 1937 studied the addition of lime and carbon dioxide or calcium carbonate to gold-bearing tailings to form agglomerates suitable for vat leaching. Satisfactory percolation flow rates were achieved in 90 g (3 oz) scale experiments, but the reagent requirements were cost prohibitive. Agglomeration and pelletizing has been used in other segments of the mineral industry. This technique was first used successfully around 1911 for pelletizing iron ores. Since then, agglomeration

Jan 7, 1986

By David A. Milligan

This paper describes the Darwin Silver Recovery project, located 66 km (40 miles) outside of Lone Pine, near Darwin, Inyo County, California. A lead-zinc mine and a flotation concentrator were operated there from 1945 to 1957. By the time the mine was shut down, 1.53 Tg (1.69 million short tons) of tailings had been stored in ponds. An average silver assay of 47 mg/kg (1.38 troy oz/st) of tailings stimulated interest for commercial silver recovery. A heap leach process was developed in 1981 at the Tucson Research Center of Anaconda Minerals Company, a division of Atlantic Richfield Company. Agglomeration techniques were used on the ore since the fine grind did not allow direct heap leaching. Lime and cement were required as binders, Early laboratory tests showed that recoveries equal to those from an agitated leach could be achieved at lower capital and operating costs. Laboratory tests determined cyanide requirements, lime and cement usages, and percolation or leach rates, as well as confirming that a zinc precipitation step could recover the silver from the leach solution.

Jan 1, 1983

By David A. Milligan

This paper outlines the research and development of a process to treat flotation tailings from the Darwin mill in lnyo County, California. A flowsheet was developed incorporating an agglomerated heap leach process using sodium cyanide to extract the silver values. Agglomeration was the key to developing this resource as the mill tailings averaged only 13% plus 100 mesh. Percolation through the heap would have been impossible without agglomeration to improve the permeability. The various tests that went into this research program are described with particular emphasis on the agglomeration techniques developed at the Anaconda Minerals Research Center. Start up and operation are discussed.

Jan 1, 1984

By G. N. Carlson, C. H. Hazelroth, D. R. Dorrance

"Located on the north shore of the St. Lawrence River at Pointe Noire, Quebec are the agglomeration and ship-ping facilities of the Wabush Mines complex. Here, the specular hematite concentrate from the Scully Mine is received for further processing. Modern facilities for handling the ore, either to the 1plant or to stockpile, provide quick and efficient operation of the ore receiving station. Physical preparation of the ore for balling is accomplished with regrind ball mills, filters, bentonite crushing and drying facilities, pumps and related conveying circuits. Rotating table feeders deliver the reground and de-watered ore from storage bins to balling drums, where green ball or green pellet formation is achieved. The green balls are then conveyed to the indurating section. Three Dravo-Lurgi travelling grates, producing a total of 6,000,000 long dry tons of pellets per year, are used in the indurating phase of the operation. These grates, having 38 windboxes and firing at a temperature of 2,500°F, harden the pellets for shipment to various blast furnaces throughout the world."

Jan 1, 1969