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By Raphaël Mermillod-Blondin, Claude Bazin

"Sampling is an important step for ore body evaluation and daily plant material balances. The Gy’s equation is regularly used to assess the size of the samples to be collected and to estimate the reproducibility of the collected samples. The equation works well for iron and base metal ores but seems to produce pessimistic estimates of the gold content reproducibility for gold ores. A model is proposed to simulate the division of samples using a standard splitter and discrepancies are observed between the Gy’s equation predictions and simulated samples reproducibility for crushed gold ore. Results of the simulation show that sampling a pile of ore crushed to -2 mm should lead to more reproducible gold content than it is observed in practice and predicted by the Gy’s equation.INTRODUCTION With current gold prices above $1400 per troy ounce operators seek for new economical ore bodies. The metallurgical evaluation of an ore body is one of the numerous steps required to justify the investment for the development of a gold mine. Metallurgical testing requires to sample the ore body and to prepare the ore sample for the grinding and separation tests. The preparation implies crushing the ore usually to less than 2mm and its division into batches of a given weight for subsequent processing. For gold ore testing a batch of crushed ore is ground in a laboratory mill and leached using cyanide. Gold recovered in the solution is used as an indicator of the ore processing amenability. One difficulty associated with ore testing is due to the reproducibility of gold content measurements of the feed sample. According to the Gy’s equation (Gy, 1979; Morisson, 2009) the division of a 20 kg batch of -2 mm ore containing 5 g/t of gold into batches of 1 kg may lead to batches containing 5 ± 5 g/t of gold. For this reason the gold content of a feed sample is usually back calculated from the assays of the solution and solids residues of the leaching process. However, these two assays may contain measurement errors that can propagate through the calculation of the gold recovery. The use of the feed assays as a redundant information could add robustness in the evaluation of ore amenability to processing. This paper discusses the problem of sampling reproducibility for a gold ore. The analysis is carried out with reference to the Gy’s equation for the sampling of particular materials."

Jan 1, 2012

By Richard Manrique

"La implementación del proyecto de modernización de la fundición de cobre de Southern Peru Copper Corporation requiere cambiar la metodología de funcionamiento de los sopladores para la etapa de conversión. En este sentido, el presente texto señala los aspectos del Sistema de control maestro de reparto de carga implementado en la Fundición de Ilo con excelentes resultados, logrando mejorar el rendimiento de los equipos con una antigüedad de mas de 30 años e invirtiendo tan solo en nuevos controladores en una etapa ligada directamente a la línea de producción. Mantener la variable primaria presión en la red de sopladores, compartiendoóptimamente la carga entre los sopladores en la red, mientras que, se minimiza el riesgo de surge, consumo de energía y los disturbios en el arranque y el paro de sopladores individuales, el sistema deberá ser lo suficientemente flexible que no deberá de perturbarse ante la salida frecuente de los convertidores, es decir deberá de mantener las presiones y flujos a la descarga del manifold ante las variaciones en el consumo de aire todo esto con un mínimo de venteos al ambiente."

Sep 19, 2006

By J. C. Ion, O. Isaksson, J. Stjernberg

Iron ore pellets are a preferred feedstock for ironmaking. One method used for pelletizing is the grate-kiln process, first established in 1960.During the past decade, the establishment of new grate-kiln plants has increased rapidly, especially in China, and new constructors of pellet plants have started to operate in the market. It is well known that the grate-kiln method yields a superior and more consistent pellet quality compared with the straight-grate process. However, certain issues exist with the grate-kiln plant, which are discussed here, together with proposed practical solutions.

Jan 1, 2015

By A. D. Hughes

C. W. MERRILL*-Mr. Hughes' paper not only is very well presented but is most timely in that it covers a subject of vital interest to the United States. Tin is one of the strategic metals which has not been found here in appreciable quantities. The total United States tin output since the first recorded production over 100 years ago would not supply current consumption for a fortnight. On the consumption side, tin is extremely important in national defense because of its use in tin plate which, in the form of tin cans, makes it possible to feed properly the armies that the United States recruits from its civilian population in emergencies. Moreover, the internal combustion engines so important in powering tanks, planes, and other war machines, require large quantities of tin alloys for bearings and for soldering. These considerations, along with the fact that Malaya, historically, has been the leading source of tin to the United States, make the kind of information that Mr. Hughes has presented so ably, a matter of vital interest.

Jan 1, 1949

Rock mass classification is widely used throughout the underground mining industry—in both coal and hard-rock mines. It is used in all stages of the mining process, from site characterization to production operations. The goal of the International Workshop on Rock Mass Classification in Underground Mining was to provide a forum for leading practitioners of rock mass classification to come together and share their methods and experiences with the technique. The workshop was held in Vancouver, British Columbia, Canada, on May 31, 2007. It was co-chaired by Christopher Mark, Ph.D., P.E., National Institute for Occupational Safety and Health, Pittsburgh, PA, and Rimas Pakalnis, P.Eng., University of British Columbia, Vancouver, Canada. The proceedings of the workshop contain 16 invited papers from 9 countries, reflecting the international depth and breadth of current practice. Applications in both hard-rock and coal mining are well represented. Some of the topics that were addressed at the workshop include: • Major rock mass classification systems used in mining and their variants • Collection of input data through observation, rock testing, and geophysics • Design of mine layouts and rock support systems using classification • Estimation of rock mass strength and other input parameters for numerical models from classification • Applications in weak rock, raise boring, cavability assessment, and other special topics • Risk assessment using rock mass classification

Jan 5, 2007

By G. O. Oniyide, H. Yilmaz

The South African platinum mines in the Bushveld Complex (BC) have unique features that distinguish them from the gold mines. They have a higher horizontal stress closer to the surface, lower occurrence of seismic activity (caused mainly by pillar failure), and are sited in an area of high geothermal gradient. One of the future challenges of platinum mining is the increasing temperatures as the mining depth increases. High temperatures invariably bring about higher ventilation costs and require different approaches to human factors and ergonomics. Excavation stability would also be another area of concern due to increasing stresses. In this investigation, the effect of temperature on the physical and chemical properties of selected Bushveld rocks (chromitite, pyroxenite, norite, leuconorite, gabbronorite, mottled anorthosite, varitextured anorthosite, granite, and granofels) was studied by means of optical microscopy and scanning electron microscopy using energy-dispersive Xray spectrometry (SEM-EDX). The rock specimens were heated in a temperature-controlled oven a rate of 2°C /min to 50°C, 100°C, and 140°C and kept at temperature for five consecutive days. Samples were allowed to cool to ambient temperature (approximately 20°C) before image capturing. Micrographs of the specimens were taken before and after heat treatment. All the SEM samples were also subjected to heating and cooling on alternate days for ten days in order to observe the effect of repeated heating and cooling on the rocks. The results of the optical microscopy analyses showed minor physical changes in the rocks. The SEM images revealed that cracks initiating at lower temperatures extend with increasing temperature. The chemical analyses showed that the temperature range considered in this research is not high enough to induce changes in the chemical composition of rock samples.

Jan 1, 2016

The speed and internal accuracy of today's electronic calculators can be utilized to write an efficient slurry calculation program. The calculator's input/output printing feature offers additional benefits for data organizing and record keeping. This program allows slurry calculations to be performed without the urgency of immediately transferring a calculated result onto a process flowsheet or specification sheet. The number of flowsheets required for some hvdrometallurgical processes means the number of process stream blocks or ladder diagram entries can become substantial. Slurry calculations for such projects tend to become repetitious and tedious, and the chances for errors increase both in calculation and data entry onto process documents. Using this program has minimized both types of errors. Checking process flowsheets is particularly expedient with the program because you may "walk" through the flowsheet on a weight basis, i.e., solids rate and solids density, and have the program verify and/or correct the volume entries, gallons, and specific gravities. The program was initially used on a beneficiation project to check some 500 data entry values on ladder diagrams covering seven process flowsheets. Numerous hand calculation errors were determined and corrected, and the time for completely checking and correcting the flowsheet ladder diagrams was substantially reduced.

Jan 4, 1981

By John T. Norton

N order to attempt to arrive at a better under-Jl standing of the whole basic problem of sintering, these remarks will serve as an introduction for discussion that is included and will, perhaps, help to isolate specific questions which need to be answered or to suggest some definite avenues of investigation which should be followed. To bring some sort of logical order into the presentation, I will consider the various types of interaction between the metal to be sintered and the atmosphere which surrounds it, depending upon whether the phenomena are essentially chemical or physical in nature. For example, when the only necessary criterion for the satisfactory sintering of a certain powder is the removal of an oxide skin, then the problem of choosing a suitable atmosphere is primarily chemical; however, if a special surface condition as a consequence of the oxide skin removal is necessary for particularly effective sintering, then the problem becomes a physical one. Of course, the two aspects overlap considerably, but it may be possible to make a distinction in principle if not in practice. The chemical characteristics of the phenomena will be emphasized, since these are the better known. Metal-gas reactions involved in sintering are controlled primarily by the thermodynamics of the processes involved. In which direction will a reaction go and how far before it stops? The answer is to be found in the magnitude of the free energy change associated with the reaction. If a constituent is to be removed from the specimen as completely as possible or if a constituent is to be formed in the specimen as completely as possible, then one chooses conditions which are far from equilibrium so that the reaction is driven toward completion. On the other hand, if the composition is to be maintained at a desired value, then conditions are adjusted as closely as possible to the equilibrium point. This aspect of the problem is susceptible to quite precise analysis, provided, of course, that the significant reactions can be recognized and the required thermodynamic data are available. Conversely, if one asks how fast the reaction goes or how far it proceeds in a given time, the answer is frequently much more difficult to answer in quantitative terms. Yet the rate-con trolling factors of the reactions may be of primary importance in the success of a particular operation, especially where competing processes are at work. Both equilibrium and rate factors must be understood if a clear picture is to be obtained. For instance, in a process for carburizing titanium dioxide, is the difficulty of obtaining a stoichiometric Tic due to a true limitation of the equilibrium or simply to a very slow rate of reaction? An example of this appears in the work of Kalish and Mazza.' They showed that the oxygen content of sintered iron compacts was lower when sintered in pure hydrogen than in the case where the hydrogen was diluted with either argon or nitrogen. The equilibrium oxygen content of the iron would be the same in the two cases, since it is determined by the ratio of the partial pressures of water vapor and hydrogen and this pressure ratio is unchanged by dilution. The rate of oxygen removal, however, under the conditions of a constantly replaced furnace atmosphere, depends upon diffusion and thus upon the concentration of hydrogen in the furnace atmosphere. Possibly the clearest way to illustrate the interplay of these two factors is to consider in more detail some of the typical metal-gas reactions. Adsorbed Gases It is common experience that fine metal powders with their very large surface areas often contain large quantities of gas. This gas, which results from exposure to air or perhaps from some step in the

Jan 1, 1957

By Colin Rawlings, Simon Pepper, Maria Karakitsiou, John Mathews, Peter Townsend, Russell Bowler, David Keeble, Christopher Darton, Scott Sadler

National Grid needs to maintain a connection between two existing electricity sub-stations (Beddington & Rowdown) in the Croydon (south London) area, and allow the replacement of two 275 kV cable circuits that are buried under roads. This is to be achieved using a single 400 kV cable circuit within a 10 km (6.25 mile) long, 3 m (9.8 ft) diameter high voltage cable tunnel which is being driven through water bearing Chalk, at depths ranging from 5 m (15 ft) to 80 m (262 ft), with four access shafts(12.5 m (41 ft) in diameter) ranging in depth from 10 m (31 ft) to 40 m (131 ft). The Chalk in this area acts as a source of public drinking water supply (PWS) and is protected by areas designated Groundwater Source Protection Zones. To minimise the groundwater risk the design and construction of the cable tunnel and shafts has paid particular attention to the construction materials used, including testing of these construction materials prior to use, developing construction methods (including the design of the Earth Pressure Balance TBM) and maintaining a groundwater monitoring & testing programme prior to and during construction to ensure the integrity of the Chalk aquifer is maintained as a drinking water source. This paper describes the tunnel &shaft design and construction in relation to these particular groundwater environmental issues which set new precedents for tunnel assessment, design and construction requirements in the United Kingdom.

Jan 1, 2007

By J. W. Thompson

Be if enacted by the Senate and House of Representatives of the United States of America in Congress assembled, That deposits of coal, phosphate, sodium, oil, oil shale, or gas, and lands containing such deposits owned by the United States, including those in national forests, but excluding lands acquired under the Act known as the Appalachian Forest Act, approved March 1, 1911 (Thirty-sixth Statutes, page 9G1), and those in national parks, and in lands Withdrawn or reserved for military or naval uses or purposes, except as heroinafter provided, shall be subject to disposition in the form and manner provided by this Act to citizens of the United States, or to any association of such persons, or to any corporation organized under the laws of the United States, or of ;iny State or Territory thereof, and in the case of coal, oil, oil shale, or gas, to municipalities: Provided, That the United States reserves the right to extract helium from all gas produced from lands permitted, leased, or other- wise granted under the provisions of this Act, under such rules and regulations as shall be prescribed by the Secretary of the Interior: Provided further, That in the extraction of helium from gas produced from such lands, it shall be so extracted as to cause no substantial delay in the delivery of gas produced from the well to the purchaser thereof: And provided further, That citizens of another country, the laws, customs, or regulations of which, deny similar or like privileges to citizens or corporations of this country, shall not by stock ownership, stock holding, or stock control, own any interest in any lease acquired under the provisions of this Act.

Jan 1, 1921

By Donald Leroux, Jean-François Wilhelmy, Ahmed Bouajila

"A young private R & D organization, COREM celebrated its 10th anniversary in 2009. Managed by a consortium of nine mining and metallurgical companies, COREM has the mandate of increasing the competitiveness of its member companies through the development and transfer of mineral processing innovations. Typical technologies developed by COREM include alternative mineral processing techniques, novel operating strategies, innovative sensors and process simulation software. Many of them were developed in partnership with universities and selected research organizations.Because the COREM membership base is broad (from ferrous to base, to precious metal industries), its R & D program must deliver technologies with applications within a wide spectrum of mineral processes. Comminution, physical (gravity and magnetic) separation, flotation, cyanidation, pelletizing and thermal processes are the main topics of the R & D program. A number of new technologies have been developed and transferred to the plants of member companies. These examples of transferable technologies demonstrate the capability of COREM to impact the bottom-line of its member companies.INTRODUCTIONCOREM is a private mineral-processing R & D organization that operates from its own laboratories and pilot-plant with its own staff of professionals and technicians (about 95 persons). It is managed and financially supported by a consortium of nine mining and metallurgical companies and three provincial and federal ministries. The very ‘down-to-earth’ mission statement of COREM is to increase the competitiveness of the mineral processing plants of its members. The eighteen plants upon which the COREM technology development program is currently based can be found in Québec, Newfoundland and Labrador, New Brunswick, the Netherlands and Botswana."

Jan 1, 2010

By P. Massacci, F. La Marca, G. Bonifazi

Certain deposits of incoherent materials which are near the surface and exploitable by open-pit mining may be characterized in real time before they are mined through an analysis of ground-surface imagery. If the slice to be stripped is not overly thick, in fact, surface texture and color properties may be extrapolated to its entire thickness. Image analysis techniques to process ground surface images acquired in situ(or in the laboratory shortly after their acquisition) which yield pattern vectors representative of RGB color component distributions and HSB texture parameters have been developed. The techniques were applied to a mineral sandy ore deposit containing three different lithotypes. Geostatistical analyses showed that the data used to characterize the lithotypes were reliable. The correct recognition of the lithotypes was carried out using a multi-barycenter classification algorithm. Such in situ image-analysis procedures open the way to the proper selection of the ore to be mined, or the proper way for run of mine (r.o.m).processing, or the appropriate blend to be processed before or at the same time as the mining process itself is enacted.

Jan 1, 1999

By S. J. Broderick

[The term "nonmetallic minerals,? as commonly used in the mining industry, refers to those minerals of industrial importance that are mined essentially for uses other than for the metals contained. The field comprises several hundred minerals of industrial importance, of which 70 have been adequately described in the textbook Industrial Minerals and Rocks.3/ A few of the more important nonmetallic products are sand and gravel, salt, phosphates, clays, refractories, linestone, and cement materials. Some of tic minerals, such as bauxite and pyrolusite, have both metallic and nonmetal is applications, but in this report only the nonmetallic mineral phases are considered. In the organic field of nonraetallics only coal is considered, as, the, others - petroleum, natural gas, natural bitumens, and hydrocarbons - are of no importance in water softening.]

Jan 1, 1941

The following notes apply more especially to the purchase of silverlead ores produced in the neighbourhood of Zeehan and Dundas; for it is this class of ore that is principally mined in those parts, and which creates competition among the ore buyers.In the early days of this field, most of the ore passed through the hands of the first buyer who had sufficient enterprise to establish himself at Zeehan but in more recent times, competition has been so keen that there are generally three or four buyers tendering. lf the output was large this would not matter so much from the buyers' point of view but when we consider that the output of the field is only some 1,650 tons per month, and that of this 70 odd tons are produced by the Western and Montana mines, aud being sent home for realization, is withdrawn from local purchasers, there is really not enough for four buyers, especially at the present exorbitant prices they pay the miners.Some of the mines have a fixed sampling day, on which it is tacitly understood that the ore buyers will attend. Others, such as Grubb's Silver Mining Oompany, No-Liability, send round a printed reminder, stating the quantity of ore, and the date of sampling.

By P. Somasundaran, D. R. Nagaraj, Tarun Bhambani, P. Patra

Flotation separation and recovery of value minerals from ores containing fibrous silicate minerals are known to be quite challenging. Earlier studies have established that the metallurgical challenges (poor selectivity and recovery, high energy consumption, etc.) arise from the impact of the fibrous minerals (with high aspect ratio) on pulp rheology, which was found be rather complex. The complex rheological behavior of ore suspensions containing particles with high aspect ratio and its influence on flotation outcome are investigated in this study. Flotation tests and rheological measurements were carried out with both ores (containing fibrous minerals) and a model system comprising nylon fibers (chemically inert) added to a copper ore that had no fibrous mineral. These studies allowed the determination of contributions of physical properties of the fiber to pulp rheological behavior. Optical microscopy images of the fiber pulp indicated that the fibers entangled to form two levels of microstructures: two-dimensional (2D) aggregates under semi-dilute (< 20% solids) conditions and three-dimensional (3D) microstructures at concentrations > 30% solids. The yield stress (σ) values determined for the fiber pulp were logarithmically related to the volume fraction of the 2D/3D structures. The relationships developed here for different ARs showed that the yield stress of a flotation pulp changes with respect to shape, size, and the concentrations of the microstructures. Implications to the effects of such entangle networks on selectivity of flotation separation are discussed.

By Michael J. Lord, Richard H. O. Wagner

"The technologies used in the mineral processing of ores are being increasingly applied to the identification and remediation of metal contaminated industrial, military and landfill sites. The objective of mineral processing treatment of contaminated site material is to restore the value of the land and to concentrate the contaminants into a very small volume of separated material which, depending upon its nature, can be further processed, marketed, or sent to a landfill. A systematic characterisation of the site material is first undertaken. Bench and pilot testing follows to evaluate criteria for metal separation. The testing may examine one or more physical or physico-chemical reprocessing methods, singly or in combination, for the remediation of the test samples. These mineral processing tests determine the % metal removal fiom the soil and the contaminants concentrated from the medium. The usefulness of mineral processing testing for site remediation flowsheet design and execution is illustrated by the case studies presented. This paper will present the test results of three case studies: an industrial site decontamination, the cleanup of a small arms firing range, and the reclamation of property within a landfill.INTRODUCTIONEnvironmental legislation and our society’s quest for a cleaner environment has led to the application of mineral processing expertise and technology for industrial site decontamination, military site cleanup and landfill reclamation. Although the required level of decontamination varies between jurisdictions, a site becomes a candidate for decontamination once the contaminant concentrations are found to exceed the Canadian Council of Ministers of the Environment (CCME) Interim Remediation Criteria for soil (decommissioning guidelines) or applicable provincial guidelines. The objective of mineral processing treatment of contaminated site material is to restore the value of the land and to concentrate the contaminants into a very small volume of separated material which, depending upon its nature, can be further processed, marketed or disposed of in a landfill"

Jan 1, 1999

By S. R. Zimmerley

As a result of the drilling program of the :Mining Division, Bureau of Mines, large amounts of manganese ores have been blocked out in the Drum Mountain District of Utah. The ores, as mined, would not be acceptable for the production of ferromanganese, and this investigation was made to determine their amenability to concentration by ore-dressing methods and the amount of

Jan 1, 1942

By S. R. Zimmerley

As a result of the drilling program of the Mining Division, Bureau of Mines, large amounts of manganese ores have been blocked out in the Drum Mountain District of Utah. The ores, as mined, would not be acceptable for the production of ferromanganese, and this investigation was made to determine their amenability to concentration by ore-dressing methods and the amount of

Jan 1, 1942

By Roberto Folcht

The obligations of the European Directive 96/82/EC on the control of major accident hazards, the so-called Seveso II Directive, became mandatory within the E u ropean Member States February 3, 1999. Explosive products have been included within the Seveso II Directive, in the categories of substances capable of generating a major accident. In addition to taking “all measures necessary to prevent major accidents,” explosive manufacturers are also obliged “to limit their consequences for man and the environment.” However, for explosives in particular, no pro c e d u res, nor specific re f e rence values for damage calculation, are given either in the Directive or in the corresponding Italian Legislation, “Ministry of the Environment decree of 20 Oct. 1998.” This article presents a simplified but scientifically rigorous approach for the first approximation calculation of the effects on the surrounding area following an accidental explosion. As an example of the method of calculation, the damage areas in a hypothetical explosives manufacturing facility, as shown in F i g u re 1, will be anal y z e d . The method proposed in this article can also be used for the analysis of explosions of gas in tanks or pipelines,

Jan 1, 2004

By P. D. R. Maltby

"With the narrow vein structure of Nova Scotia gold deposits, selective mining is rarely possible and mill heads will be too low (below 0.10 oz per ton of gold) to support a conventional mill of up to 1000 ton per day capacity at present gold prices. The recent operation of a small 100 t.p.d. mill at Cochrane Hill using fine grinding - leaching - filtration supported this assertion. Milling costs exceeded $25.00/ton of feed mainly due to high capital, labour and maintenance costs.Accordingly, since 1981, efforts have been directed towards the development of a cheap gold extraction process in terms of both capital and operating costs. The main criteria is to produce gold below US $200 per oz including all administration, mining and process stages. This paper describes such a process development for Cochrane Hill. LOCATION AND HISTORY OF THE PROPERTYThe Cochrane Hill property is located about 8 miles North of Sherbrooke, N.S. on highway No. 7. Sherbrooke is about 180 miles east of Halifax. Gold was originally discovered at Cochrane Hill in the 1860's. Early work consisted of trenching. In the 1930's a small shaft was sunk to about 80 feet and some tonnage treated using a stamp mill with gravity concentration of gold.Northumberland Mines Ltd. acquired a 70% interest in the property in 1977. Subsequent drilling indicated a potential zone of gold mineralization with a drill-indicated tonnage of one million tons having a grade of 0.07 ounces per ton of gold (all high assays cut to 1 oz) down to a depth of 300 feet recoverable by open pit mining methods. In broad terms, the goldbearing zone is about 50 feet wide and 800 feet long and dips at about 70°."

Jan 1, 1984