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By D. G. MacBeth

Most belt scales on the market are factory calibrated to minimum accuracy figures of 0.1% - 0.2% at several load points. However, if the same belt scale is not properly installed and maintained on the customers conveyor then the scale will not measure up to the claims of the manufacturer or to the requirements of the operator.

Jan 1, 1975

By J. G. Manchuk, M. Thurston

"The degree of uncertainty associated with a natural diamond resource is important to quantify from the time of discovery through the production lifetime. Data collection occurs during the discovery, exploration, delineation, and production or recovery phases. Quantifying the relationship between data and uncertainty is an important component of project valuation. The value of data is measured as their potential to reduce uncertainty if they are collected. A method is developed using Monte Carlo simulation for predicting resource uncertainty and valuing data during critical phases of development, particularly discovery and exploration. The technique is applied to diamond pipe deposits.RÉSUMÉ Il est important de quantifier le degré d’incertitude associé à une ressource diamantifère naturelle, depuis le moment de sa découverte et durant toute la durée de l’exploitation. La collecte de données se fait durant les phases de découverte, d’exploration, de délimitation, et de production ou de récupération. La quantification de la relation entre les données et l’incertitude est une composante importante de l’évaluation du projet. La valeur des données est mesurée en tant que leur potentiel à réduire l’incertitude si elles sont recueillies. Une méthode a été développée qui utilise la simulation de Monte Carlo pour prédire l’incertitude de la ressource et évaluer les données durant les phases critiques du développement, surtout celles de la découverte et de l’exploration. La technique est appliquée à des gisements de cheminées diamantifères."

Jan 1, 2015

By B. Dubé, R. Friedman, J. Oliver, R. Aubertin, M. Burson, G. Panneton, M. Hamilton, J. Ayer

"Abstract — The Detour Lake gold deposit is located within the northwestern limit of the Archean Abitibi Subprovince of the Superior Province. Mineralized zones are hosted by a sequence of pillowed and massive flows, hyaloclastite units, and altered ultramafic rocks, and are commonly oriented parallel to a series of high-strain zones that are co-planar to the regional-scale Sunday Lake Deformation Zone. Early in its kinematic history, the Sunday Lake Deformation Zone placed older (2.72 Ga) volcanic rocks of the Detour Lake Formation over younger (2.70 Ga) sedimentary rocks of the Caopatina assemblage. Gold mineralization is also parallel to the position of a laterally persistent siliceous rock unit, the 2.725 Ga ‘Chert Marker Horizon.’ The Chert Marker Horizon coincides with the boundary between the mafic-dominated upper Detour Lake Formation and the ultramafic-dominated lower Detour Lake Formation. Stratigraphic and geochronological data suggest that the Chert Marker Horizon is a deformed felsic volcaniclastic unit. At a cut-off of 0.6 g/t Au, the Detour Lake deposit contains 17.26 million ounces of Au within 445.9 million tonnes of rock grading 1.20 g/t Au. Gold occurs in shear-hosted and extensional vein arrays within rocks of the upper and lower Detour Lake Formation and within the Chert Marker Horizon. The Detour Lake deposit has many of the characteristics of a greenstone-hosted, quartz-carbonate vein deposit; its very large size may be attributed to large-scale rheological controls resulting in the formation of dilatant sites in permissive rock units. © 2012 Canadian Institute of Mining, Metallurgy and Petroleum. All rights reserved."

Jan 1, 2012

By Jerry Gagnon, Matt Burr, Timothy Ellis, Abbas Mirza, Larry Webb

"The mechanical properties of RSR anode alloys (lead-calcium-tin, 009+ and lead-strontium-tin) were investigated as a function of time with an objective of developing lead anodes for use in high temperature electrolytic processes such as in copper liberator cells and in cobalt and nickel electrowinning. At a temperature of 70 oC, the mechanical properties of rolled RSR lead-calcium-tin (PbCaSn) alloy currently used in copper electrowinning decreased gradually while the mechanical properties of rolled RSR lead-strontium-tin (PbSrSn) decreased relatively quickly and stabilized at low strength levels. Cast PbSrSn started off as the weakest alloy but its properties remained stable with time. Rolled RSR 009+ anode alloy showed improvement in ageing properties over the other alloys tested. However, its mechanical properties did not stabilize in the study timeframe of 284 days. Further investigations are planned to study the effect of alloying elements on mechanical properties of RSR 009+ anode alloy over several years as a function of time at 70 oC. The mechanical properties will be evaluated to determine the time at which they stabilize. Comparative plant trials with rolled RSR PbCaSn and RSR 009+ will also be performed in copper liberator cells and in cobalt and nickel electrowinning tankhouses to determine their mechanical and electrochemical performance at temperatures of 65-75 oC.INTRODUCTIONLead-based alloys are the primary anodes used in the electrowinning of copper, zinc, nickel, cobalt and manganese from sulfate-based aqueous systems. Lead anode technology has evolved over the years migrating from pure lead and lead-antimonial alloys to the present day PbCaSn alloys for copper and PbAg and PbCaAg alloys for zinc electrowinning (Prengaman, Ellis and Mirza, 2010). It has also migrated from cast to rolled microstructures in search of improved mechanical properties and higher corrosion resistance. Although great strides have been made in the development of new lead anode alloys and production processes for lead anodes to be used in copper electrowinning, the industry still has some unresolved issues. These relate to the necessity of having higher mechanical properties especially for the lead anodes in liberator cells in copper electrorefining and for cobalt and nickel electrowinning as these tankhouses operate at temperatures of 65-75 oC compared to 40-45 oC in case of copper electrowinning."

Jan 1, 2016

By P. Bakke

Following extensive R&D efforts, Hydro Magnesium has launched a new alloy series with remarkable combinations of properties. The AE alloy family is based on additions of aluminium and rare earth elements to control mechanical properties, including elevated temperature creep strength. By combining these alloying elements with manganese additions, high purity alloys with outstanding corrosion performance are defined. A basic philosophy behind the developments has been to simultaneously approach all the critical issues related to developing a commercial material. Apart from the obvious requirements for material properties, the critical issues relate to die casting performance, as well as alloy production, recycling and environmental compatibility. Some of the important elements related to alloy production and recycling are addressed in the present paper.

Jan 1, 2006

By Claude Bazin, François Robichaud

"The control of the operation of semi autogeneous grinding (SAG) mills is mainly achieved through adjustments of feed rate, water addition and speed of rotation. With the introduction of image based sensors it is possible to have on-line measurements of the size distribution of the ore feeding a SAG mill. This information could be used for the development of a control strategy to regulate a SAG mill feed size distribution to a set-point. The control of the size distribution is carried out by adjustment of the speed of the ore extractors underneath the ore stockpile. The potential and difficulty associated with the implementation of such control are assessed using a multivariable statistical analysis of data collected from the operation of the grinding circuit of the Agnico-Eagle Goldex mine in Val d’Or, QC. A control strategy for the ore feed size distribution is assessed using a simulator of the ore stockpile operation.INTRODUCTIONThe popularity of autogeneous (FAG) and semi autogeneous (SAG) grinding mills has been increasing over the last 20 years (Napier Munn et al., 1996). These mills use the ore or a combination of ore and steel balls as the grinding media. Since the ore is used as a media for the size reduction the mill ore feed size distribution impacts the performance of the mill. Several papers were recently published on this subject (Dance et al.,2011; Wennen & Murr, 2011; Dance & Valery, 2011; Allaire et al., 2011) showing the advantages of preparing the feed size distribution to maximize the circuit throughput or mill efficiency (Wennen & Murr, 2011; Dance & Valery, 2011; Allaire et al., 2011). With the availability of particle size sensor based on image analysis of the ore on a conveyor (Partanen et al., 2001; Bobo et al. 2004; Edwards et al., 2002; Wei & Craig, 2009) it is possible to control the size distribution of the ore feeding autogeneous or semi autogeneous mills (Partanen et al., 2001).This paper describes a method to control a size distribution index to a set point via the manipulation of the speed of the extractors that withdraw the ore from the stockpile feeding the grinding circuit. The paper consists of 4 sections. The first section describes the considered grinding circuit. A statistical analysis of the collected data on the grinding circuit is presented in the second section. This analysis demonstrates the necessity of using real-time adaptation mechanisms to develop a control strategy for the size distribution of a grinding circuit. The third section describes the method used to simulate the ore stockpile operation and the last section describes the preliminary development and assessment of a control strategy of size distribution of the ore feeding a SAG mill."

Jan 1, 2013

By D. Nower

"The supply of copper is expected to be at a large deficit in 2012. To recover from these deficits mining companies are required to maximize production and there is no better way to accomplish this than to optimize the use of their mobile mining equipment fleets. To optimize these fleets, each equipment type has to be monitored in its own unique way. Automation would not only improve production, but also minimize the safety risks and eliminate planning errors. The automated vibration monitoring of multiple systems on the shovel can determine the machine’s condition at all times. This reduces unplanned downtime and keeps critical shovels in production. This paper will discuss the details of how shovels can be successfully monitored, continuously. INTRODUCTIONP&H Mining, part of Joy Global, is the world’s largest manufacturer of above-ground mining equipment. Its electric rope shovels, such as Figure 1, with capacities up to 115 tons (104.3 metric tons), are used for high production loading in surface mines; its draglines, such as Figure 2, have bucket capacities to 160 cubic yards (122 cubic meters). P&H also produces blasthole drills, mobile mining crushers and other essential mining equipment. Headquartered in Milwaukee, WI, the company does business on every continent, except Antarctica. ECONOMIC FACTORSDue to the global demands for metals and power, mines are required to operate at full capacity. Mine operations cannot afford any critical assets to shutdown unexpectedly; depending on the ore type and quality, downtime for a single shovel can be as much as $300,000 per hour.Electric rope shovels are one of the most critical assets in open pit mining. They are very large, complex machines with DC or AC motors, multiple reduction gearboxes (some of them complex planetary) and multiple large rolling element bearings. This complexity, combined with the tough 24/7 service, results in too much unplanned shovel downtime, which can affect the entire downstream process."

Jan 1, 2012

By S. Ianos, C. Vibert

Type and shape of large dams founded on rock depend upon the expected deformation of their foundation. Their design consequently requires the assessment of the deformability of the rock mass at large scale. Seismic refraction, laboratory tests on rock samples and empirical formulas can provide an order of magnitude of the deformation modulus, with a limited degree of reliability. Direct in-situ measurement of the deformability of a volume of rock is therefore preferred, which integrate the effect of discontinuities, such as plate loading tests, dilatometric tests, etc. The authors have been compiling results obtained by in-situ deformability tests on a number of dam sites, including the Scarabée (“Petite Sismique”) method. This last method consists in thoroughly analysing the shape of seismic wave forms transmitted through the rock mass. It has been used since now more than 40 years over a large number of dam foundations, and has proved to provide a satisfactory assessment of the static deformation modulus. After comparing the results obtained from different methods on six dam sites, the Authors conclude that their reliability closely depends upon the size of the loading device in relation to the spacing of the discontinuities. Attempts to correlate results from different types of in-situ loading tests reveal difficult, because closely depending upon local geotechnical conditions at test location. Plate jacking tests appear to be the most reliable, because involving a relatively large volume of rock. On the other hand, the Scarabée method (“Petite Sismique”) allows a rapid assessment of the deformation characteristics of the rock mass at large scale, and has been found to provide values generally in agreement with those from plate loading tests, while dilatometric or flat-jack tests were found too dependent upon local conditions. The Authors conclude that preference should be given first to the Scarabée method, which uses light equipment and is quickly performed, together with an accurate geological and geotechnical assessment for interpretation. In a second stage, Scarabée shall be complemented by adequately performed plate jacking tests in selected locations, in order to cross-check results and refine the assessment. The general accordance between the results of the two methods, which both can integrate anisotropy of rock masses, justifies this statement.

Jan 1, 2015

This paper deals mainly with the modernization in the coal loading system at the loading piers of the Dominion Coal Company, Ltd., Sydney, Nova Scotia. The history of the operation is briefly outlined, and the construction of the Company's new pier is described in considerable de-tail. Particular attention is paid to the bins and conveyors, and to the loading tower. The paper concludes with a description of the S.S. Cape Breton Miner, built specifically for the coal trade, and the unloading facilities at Lakeview, Ontario. Coal Shipping at Sydney C OAL from the mines operated in Cape Breton by the Dominion Coal Company, Limited, has been shipped from the International Piers, situated on the east side of Sydney Harbour, for over sixty years. There were three piers, of which two were active-ly used in the shipping of coal until 1964. Nos. 2 and 3 were high piers about 600 feet long, of wooden construction throughout. They were founded on' rock-filled cribs and creosoted piles driven into the harbour bottom, and each had two decks which carried standard-gauge railway tracks.

Jan 1, 1965

By O. Matwijenko

"The Kidd Creek concentrator is located twenty-six kilometres east of Timmins, Ontario, within a metallurgical complex including a 109,000 MTPY zinc plant and a new 59,000 MTPY copper smelter and refinery. A complement of 159 persons is employed in the operation of the concentrator.Ore from the Kidd Creek Mine is crushed underground to minus 15. 0 cm, then transported twenty-seven kilometres by rail 1:0 the concentrator. After being crushed to minus 1. 6 cm, the ore is further processed by grinding and flotation.The concentrator commenced operations in November of 1966 at a designed capacity of 8,200 MTPD. Two parallel flotation and grinding circuits treated copper-zinc ore (2.28% Cu, 5.63% Zn) and a third treated silver-copper-lead-zinc ore (230 g/MT Ag; 0.57% Cu, 0.88% Pb, 7.89% Zn).By 1975, the concentrator was treating 9,100 MTPD of ore. Seven concentrates were being produced, namely, high silve1: copper, low silver copper, lead, low silver zinc, high silver zinc, pyrite and tin.Planned minesite expansion to a second underground mine required increased concentrator throughput. Expansion of the concentrator enabling a thirty-three percent increase in copper-zinc ore throughput occurred during the period 1975 through 1978. This expansion included increased load-in capacity, major redesign in the crusher house, the addition of a fourth grinding and flotation circuit, the building of a fourth dryer, and numerous expansions of services."

Jan 1, 1980

"The Schist Lake mine, owned and operated by the Hudson Bay Mining and Smelting Co., Limited, is situated on the northwest arm of Schist Lake, 4 miles southeast of Flin Flon, Manitoba.The deposit was discovered early in 1947, during a diamond drilling program exploring small copper showings along the west shore of the lake. The orebodies came to surface between the mainland and the north end of Stitt Island.Production began in August, 1954, at an initial rate of 300 tons per day. Underground workings have been carried to the 1,700-foot level, where exploration work is now being done.General GeologyRocks of the area are Precambrian lava flows, with associated pyroclastic breccias and tuffs, and related minor intrusions. Their general strike is northwest and their dip is nearly vertical. Shearing is common and is related to the activity which caused intense folding and much faulting in the area. The larger faults and the fold axes trend a few degrees west of north. The lavas are mainly andesitic but a layer of sericite-carbonate schist, which is probably derived from a fine-grained, grey quartz porphyry, occupies most of Stitt Island and extends into the mine area. It is within this layer of schist that the ore deposit occurs (Figure 1).The OrebodiesThe ore occurs as tabular to lens-shaped bodies which strike northwest, dip nearly vertically, and plunge at 60 degrees to the southeast. The ore zone is 800 feet long and has been traced for a distance of 2,000 feet along the plunge (Figure 2). The maximum length of continuous ore within this zone is 200 feet. Widths of individual ore lenses vary from a maximum of 35 feet to a minimum of 2 feet.The ore consists of three distinct types: massive sphalerite-pyrite, massive chalcopyrite-sphalerite, and disseminated chalcopyrite-pyrite. The No. 1, or eastern, orebody is predominantly massive sphalerite-pyrite. The western part of the No. 2 orebody is massive chalcopyrite-sphalerite. The disseminated ore forms the eastern part and the lower end of the No. 2 orebody. All three types of ore, with patchy distribution, are found in the smaller lenses below the 1, 100-foot level.Metallic minerals, in order of deposition, are pyrite, arsenopyrite, chalcopyrite and sphalerite, galena, enargite, and gold. Both massive types of ore exhibit banding in many places, probably as a result of the selective replacement of schist. The disseminated ore was formed as a filling of the interstices in a brittle chert rock which appears to have been crushed by the same forces which produced the schist."

Jan 1, 1949

By D. Tao

Froth flotation is widely used in the coal industry to clean -28 mesh or -100 mesh fine coal. A successful recovery of particles by flotation depends on efficient particle-bubble collision and attachment with minimal subsequent particle detachment from bubble. Flotation is effective in a narrow size range outside which the flotation efficiency drops sharply. A fundamental analysis has shown that use of picobubbles can significantly improve the flotation recovery of particles by increasing the probability of collision and attachment and reducing the probability of detachment. A specially designed column with a picobubble generator has been developed for enhanced recovery of fine coal particles. Picobubbles were produced based on the hydrodynamic cavitation principle. Experimental results with one metallurgical coal and one steam coal have shown that the use of picobubbles in a 2" column flotation increased fine coal recovery by 10-30%, depending on the feed rate, collector dosage, and other flotation conditions. Picobubbles also acted as a secondary collector and reduced the collector dosage by one third to one half.

Jan 1, 2006

By W. A. Bell

The Carboniferous system of rocks in the Maritime Provinces include as workable mineral and organic substances, gypsum, anhydrite, salt, coal, building stones, grindstones, limestones, brick-clay shales, fire-clay shales, oil shales, etc. The system is, therefore, pre-eminently of economic value to the provinces in which it occurs, and the more knowledge we may gain concerning it, the more we may be prepared to aid in the development of these useful substances. For this purpose it is not sufficient to state that the ground upon which we stand is underlain by Carboniferous rocks. In-discriminate digging or drilling will not open many new mines of wealth, however difficult it may be to dampen the optimism of gamblers. For mineral wealth has not been scattered in the rocks haphazard, now here, now there, but its distribution has been the result of natural earth forces acting at intervals throughout the countless millions of years that have elapsed since our planet was born. As regards the majority of metalliferous deposits, the earth forces involved have resulted in the penetration of surface or sub-surface rocks by molten rock-matter and associated mineral solutions from deep-seated sources. But the economic Carboniferous deposits that have been mentioned are themselves types of bedded surface rocks rather than immigrant deposits, and their formation and geological history is closely related to that of the rocks with which they are interbedded.

Jan 1, 1924

By H. Lundberg

Introduction The world has been suffering from an excessive production of all kinds of raw materials, and the metals and petroleum are no exception. As a consequence, at the moment, the urge to find new mineral deposits is almost non-existent and prospecting languishes. But from previous experience we know that sooner or later new supplies will be needed. Mineral deposits become exhausted, and to keep up the supplies of our metals and petroleum, new deposits must be found. Even now, a supply of petroleum of domestic production would not be unwelcome in Canada. It is not, therefore, so entirely malapropos to discuss means of finding ores and oil as it would seem. Almost any physical property connected in definite manner with minerals and rocks may be made the basis of geophysical exploration. This is particularly true of electrical resistivity, and its utilization in electrical prospecting has been the deciding factor in the discovery of such big ore-bodies as Buchans mine, Newfoundland, and the large copper ore-bodies in northern Sweden, etc., as well as in the solution of many foundation and structural problems. The importance of electrical prospecting has been growing steadily, and already there exists hardly any exploration project involving geological problems which may not profit by its application. Electrical prospecting is marching on, and neither temporary failures, nor incompetence, nor over-optimism, nor ill-will and pessimism, nor bad times and business depression, will be able to halt its progress.

Jan 1, 1931

By Craig M. Sams

"Variable speed mill popularity has grown during the last 10 years with almost every SAG mill fitted with a variable speed drive. In addition, many of today’s larger ball mills are running a variable speed drive for various reasons. In the past, motor suppliers, especially gearless drive suppliers, have considered mills as being an overpriced rotor. This has lead to mills demanding more torque than what a motor can generate. This paper identifies the reasoning of what has happened and how to mitigate the mismatch in the future. Technical and economical issues are discussed, allowing mill operators to make an informed decision of which path to take in deciding what motor to put on a mill.INTRODUCTIONIt has been generally accepted in the past that motor suppliers and specialists in engineering companies understand the workings of a SAG mill or a ball mill and although there is a fair knowledge within the industry, in regards to mill torque requirements, the advent of variable speed drives in ball mills has shown the writer that a complete understanding of the mill torque requirements are not fully understood.This paper will discuss two aspects of mill torque requirements, (operating torque at various charge levels and start up torque), and how it relates to specifying the proper motor torque requirements.MILL OPERATING TORQUEMill operating torque at a given charge level and density in a mill is essentially constant throughout the entire speed range. For the purpose of this paper, we will take a 38’x 22.5’, 20’ EGL, SAG mill and provide the power draw at variable speeds but fixed loading conditions.The power draw and mill torque of this mill at 8% ball charge and 28% total loading (Highlighted) is shown below as Figure 1, at variable speeds."

Jan 1, 2007

By S. Avalos, J. M. Ortiz, W. Kracht

Semi-autogenous grinding mills are intensive energy consumers. Current models base their energy consumption inference on operational variables and feeding ore characterization. While they provide adequate design guidelines, they are not suitable for real-time energy forecasting dealing with gaps in operational dataset and up/downstream process bottlenecks. This work explores the capability of Gated Recurrent Units to learn the semi-autogenous grinding mill consumption behaviour. Gated Recurrent Units are trained to forecast different time-support consumptions under a time-series operational dataset. The results show high performance on small supports (30 minutes) to capture local variability and long-trends while larger time supports (8 hours) can only capture time-trends but not local variability. The proposed technique seems promising for further research and implementation on real mine cases since the input variables are low-cost and easy to obtain. INTRODUCTION Current changes in the Chilean energy matrix (Román-Collado, Ordoñez, & Mundaca, 2018), from fossil fuels to renewable energies, have impacted different industries and particularly the mining sector. Solar energy incorporation into greenfield/brownfield projects will help reducing costs and will lead to rethink foundational paradigms (production and processing strategies) (Pamparana et al., 2017). Also, integration of new space-time predicting tools together with automated real-time updating models are some of the main challenges in the geometallurgical framework (Ortiz et al., 2015; van den Boogaart & Tolosana-Delgado, 2018). Those contexts encourage and demand the development of tools capable of predicting the energy consumed by mining systems, being comminution the greatest energy consumer with an average close to 50% of the entire mine consumption (Cochilco, 2013). In comminution, the semi-autogenous grinding mill (SAG) represents the largest energy consumer (~10 nominal each SAG). Theoretical and empirical energy consumption models (Jnr & Morrell, 1995; Morrell, 2004; Silva & Casali, 2015) base their inferences mainly on feed/product size distributions, SAG sizing, bearing pressure, feed hardness, water addition and grinding charge level, and commonly assume steady-state and work isolated from up and downstream processes. While those techniques provide adequate design guidelines, they are not suitable to predict hourly, daily or even weekly energy consumptions on interconnected comminution circuits where upstream/downstream bottlenecks lead SAGs to operate below designed regimes. Forecasting energy consumption is required by short-term energy management, medium and long-term planning energy consumption, designing the nominal capacity of renewable energy sources, among other. Also, when models are input-sensitive and some of those input measurements are expensive and/or time consuming, model robustness suffers when real-time predictions are required.

Jan 1, 2019

By K. M. Ed

AN explosive is a solid or liquid substance which, when fired by some means, changes into a gaseous product occupying a volume very much greater than its original volume. The great speed at which this change takes place causes the explosive to exert a sudden blow on adjacent material. It is this action which is effective in blasting operations when the explosive, confined in a shot-hole, is fired. All explosives are similar in one respect, in that the change into the gaseous state is accompanied by the production of hot gases or flame. This results from the rapid combustion of the solid or liquid ingredients. Ex-plosives differ greatly, however, in the speed at which the reaction takes place. Black blasting powder, for instance, reacts comparatively slowly, hence the flame persists for an appreciable length of time. High explosives, on the other hand, react much more quickly; consequently, the flame is of much shorter duration. In 'closed-light' or 'gaseous' coal mines, the use of ordinary explosives is generally prohibited, due to their inherent ability to ignite gas or coal-dust by reason of the flame which they produce when fired. For instance, black blasting powder, which produces a flame of long duration, is not ordinarily considered safe to use in such mines; neither are ordinary dynamites, as their flames, while shorter than that of black blasting powder are, nevertheless, of sufficient temperature and duration to cause ignition of fire-damp or coal-dust. For this reason, specially formulated high explosives, called 'permitted' explosives, should invariably be used in such mines.

Jan 1, 1940

By Orlando C. Gaspar

Abstract - The presence of fine-grained mineral intergrowths, the complex distribution of deleterious minor elements, and the variable base-metal contents in some assemblages commonly pose technical problems for the processing of volcanogenic massive sulfide ores. The beneficiation of most massive sulfide ores from the Iberian Pyrite Belt requires extremely fine grinding to liberation sizes of K80 = 15 µm to 25 µm. For several deposits, mapping of the ore types and metal zoning patterns has shown that the different ore types are distributed as ore lenses within the massive sulfides. Mineralogical, textural, and metallogenetic studies have provided an understanding of the distribution of both the vertical and the horizontal metal zonation in the orebodies. Because the efficiency of ore processing is affected by ore textures, and because the same mineral commonly has different textures and varies in chemical composition, a relationship between textures of the feed and the middlings must be established for all ore types defined at the deposit scale. Quantitative mineralogical methods have been developed to provide, on a timely basis, the information needed to optimize the concentration processes for the massive sulfide ores at the Aljustrel and Neves-Corvo deposits, Iberian Pyrite Belt, Portugal.

Jan 1, 1997

By J. D. Clucas, D. B. Dreisinger

"The Starved Acid Leach Technology (SALT) has been developed by Search Minerals to extract nickel and cobalt VALUES (from nickel laterite ores (saprolites) and Caron plant residues. The technology consists of sulfuric acid atmospheric leaching of the ores or residues followed by neutralization and recovery of nickel and cobalt. The acid addition is carefully controlled to maximize nickel and cobalt extraction while minimizing overall consumption of acid by various gangue reactions. The final recovery processes can be tailored for maximum economic benefit. The use of resin-in-pulp processing is advocated as the most cost effective method for initial recovery of nickel and cobalt from lower grade materials. INTRODUCTIONCommercial processes for laterite ore treatment vary according to laterite type and local conditions. The two general categories of laterite ore are saprolites and limonites.Saprolites are generally treated by pyrometallurgical processes for reduction of nickel to matte or ferro nickel alloys. The high cost of drying, chemical reduction and electric furnace smelting requires that the saprolite grade for economic processing is of the order of 1.8% nickel or higher. There are of course large amounts of saprolite that fall below this “cut-off” grade that are not currently economic.Limonites can be treated by the Caron Process which involves drying of the ore, a reduction roast of the whole ore to reduce nickel and cobalt (and some iron) to the metallic state followed by ammonium – ammonium carbonate solution to leach nickel and cobalt. Nickel and cobalt recovery are low (70-85% for Ni and 20-50% for Co). The Caron plant tailings therefore contain high levels of unrecovered nickel and cobalt. Relatively few plants have used the Caron Process and new installations are not anticipated due to the high energy cost of drying and reduction roasting. Nevertheless, plants in Brazil (Niquelandia), Australia (Yabulu) and Cuba continue to operate.The high pressure acid leach (HPAL) process was pioneered at Moa Bay in Cuba in the 1960’s in the treatment of limonites. In the 1990’s the HPAL process was touted to revolutionize the nickel industry with low capital and operating costs for new installations. Murrin Murrin, Cawse and Bulong in Australia were started and in each case the technical difficulties of operating at extreme temperature and pressure conditions and the challenges in “ramping up” a complex hydrometallurgical facility conspired to cause these plants to fail economically. At present, Cawse and Bulong are closed and Murrin Murrin continues to operate after undergoing a financial restructuring."

Jan 1, 2012

By W. Noel O?Brien

Introduction Since 1930 numerous improvements have been made in equipment designed for the mechanical removal of broken ore in underground mining operations. New applications of mechanical equipment, as? well as improvements and adaptations of well established systems, are being made continually. It is the purpose of this paper to discuss present-day equipment for the removal or transfer of broken ore by means of a powered hoist and scraper arrangement. The terms used throughout the paper are those commonly employed in the trade literature and by mining men. The terms slusher hoist, hoist, and scraper hoist are used inter-changeably to mean a machine, powered by compressed air or electricity, with drums for the winding of wire rope. The tail rope, also known as the pull-back rope or return rope, drags the empty scraper toward the tail-sheave, that is, back to the loading point. No attempt is made to cover the entire field of application of scraping methods. Rather it is the? writer's desire to emphasize the fundamental principles of scraping practice and design and to relate them to some modern applications. The available literature on scraping practice has been freely used. together with personal observation and information and advice of practising engineers and representatives of companies manufacturing slushing equipment.

Jan 1, 1951