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By V. T. McLemore

Deposits of rare earth elements (REE) are found in NM, but they have not been important exploration targets in past years because demand has been met elsewhere. However, with the projected increase in demand and potential lack of available production from China, the New Mexico deposits are being re-examined for their potential. REE-Th-U veins are found in the Gallinas, Caballo, Capitan, and Cornudas Mountains and Laughlin Peak-Chico Hills. Past production of bastnaesite has come from the Gallinas Mountains. Carbonatites are found in the Lemitar and Chupadera Mountains, Laughlin Peak-Chico Hills, Lobo Hill, and Monte Largo (Sandia Mountains). Although carbonatites have not been found in the Gallinas Mountains, they are suspected to occur in the subsurface based upon mineralogy/alteration. Disseminated Y-Zr deposits in syenite are found at Pajarito Mountain, Mescalero Apache Indian Reservation near Ruidoso. In 1990, Molycorp, Inc. reported historic resources of 2.7 million short tons grading 0.18% Y2O3 and 1.2% ZrO2 as disseminated eudialyte. Two additional deposit types have potential for REE in New Mexico: Cretaceous heavy mineral, beach-placer sandstone deposits and pegmatites. Exploration is ongoing in the Lemitar, Gallinas, and Cornudas Mountains.

Jan 1, 2012

By L. Nahai

THE OUTPUT ff the mineral industry in 1964 in both non-Communist and Communist Europe showed an upward trend for most countries in keeping with the higher index of overall industrial production. Comparable indexes of mineral industry production for non-Communist and Communist Europe (including the U.S.S.R. in Asia) are not available, primarily because the U.S.S.R. does not report details of its industrial production by industrial sectors. However, available data both in the form of index numbers on production published by the United Nations and based on data as reported to the United Nations by the various countries, and actual production data for selected major commodities published by the various European countries reflect generally expanded output by both the extractive sector and the processing sector of the mineral industry in most of the 26 nations of Europe.

Jan 1, 1966

By James P. Ulery

Explosions in U.S. coal mines have caused death and injury to miners and destruction of workings since the first reported explosion in 1810. These explosions are caused when buildups of explosive gas and/or dust in the mine are ignited by the presence of a flame or spark. Methane gas is inherently generated and held by adsorption in coal and is normally liberated during mining. Because this gas is explosive in the range of 5%–15% by volume, fresh air is constantly supplied to the working face to prevent the methane/air mixture from reaching this explosive range. The required amount of ventilation air is based on estimates of gas release under normal conditions. Occasionally, unanticipated and unusually high emissions are encountered, which, despite normal ventilation controls, result in an explosive mixture that a spark from a cutting bit or electrical equipment can easily ignite. Investigations have shown that such emissions are often associated with anomalous geologic features or conditions. Although most operators are aware that certain geologic features may adversely affect productivity, few are aware of their potential as a gas emission hazard. This report presents a historical framework detailing the impact of geologic features on excess gas emissions and resultant mine explosions. It also provides operators with specific information on recognizing and alleviating potential hazards from methane emissions related to these geologic features.2

Jan 4, 2008

By Christopher Mark, Gregory M. Molinda, Timothy M. Barton

The Coal Mine Roof Rating (CMRR) was first presented at this Conference nine years ago. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, and extended cut evaluation. It has also become truly international, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. The purpose of this paper is to bring the mining community up to date with recent improvements and applications of the CMRR. The most important new development is a streamlined process for determining the CMRR from exploratory drill core. Just three types of information are now required: •Fracture spacing (or RQD) •Uniaxial compressive strength (or axial Point Load Testing) •Diametral Point Load Testing The moisture sensitivity adjustment has also been changed, and new research has related the immersion test to slake durability. Most recently, the CMRR has been implemented in a computer program, which can be obtained from NIOSH free of charge. The program facilitates calculation of the CMRR from either underground or drill core data. Values from many locations can be saved in a single file, and an interface with Autocad allows CMRR contour plots to be integrated into mine planning.

By Robert E. McIvor

"The Functional Performance Equation for ball milling circuits allows us to isolate the circuit classification system efficiency (CSE) from the mill’s grinding performance. The factors which affect circuit CSE are reviewed, with emphasis on water usage at the classifiers. It is shown that manipulation of such water usage can be carried out to improve plant grinding circuit efficiency, at times by more than 30 percent.THE FUNCTIONAL PERFORMANCE EQUATIONObservation of the feed and product size distributions going into and discharging from the mill in grinding circuits with low versus high circulating load ratios initially led to the definition of “circuit classification system efficiency” (or CSE, McIvor, 1988a), and ultimately the discovery of the Functional Performance Equation (McIvor, 1988b, and McIvor et al, 1992). The CSE is the percentage of “coarse” (typically with reference to the plus P80) size material occupying the mill (versus “fines” or product size material, finer than the circuit P80), and can be calculated by taking the average of the percentage of coarse material in the mill feed and mill discharge. As this also represents the percentage of the mill energy expended on targeted, coarse size material, it is directly proportional to overall grinding circuit efficiency and production rate. This is all clearly expressed in the Functional Performance Equation for ball milling circuits, which is derived as follows.We define “fines” as any product size material, and “coarse” as that targeted to be further ground, the two typically differentiated by the circuit target P80. For any grinding circuit, the production rate of new, product size material (fines) must equal the specific grinding rate of the coarse material (i.e. fine product generated per unit of energy applied to the coarse material) times the power applied to the coarse material."

Jan 1, 2009

By E. R. Cole

One objective of Bureau of Mines recycling research is to devise technology that enables recovery of metals and minerals from wastes. From October 1982 through September 1985, researchers at the Bureau and at the University of Missouri Rolla (contract H0222002) investigated the use of nonferrous flue dust with varying Zn contents (11 to 66 pct) as a source of Zn for electrogalvanizing steel wire. The waste dusts used were from a secondary Cu smelter, a brass smelter, a Pb smelter, and a water treatment plant. The dusts were leached in H2S04, and the leach solutions were treated to make electrolyte for electrogalvanizing steel wire using soluble Zn anodes. Cyclic voltammetry was used in an inno-vative method to evaluate the quality of the electrolytes used for elec-rogalvanizing. After electrogalvanizing, the wire was drawn on a labo-ratory draw bench to simulate industrial practice. Corrosion resistance was measured by a number of electrochemical techniques and by the stan-dard ASTM salt-spray tests. After successful bench-scale tests, the process was demonstrated in an industrial pilot plant. Results indicate that nonferrous flue dusts can be used as a source of Zn for electro-galvanizing if certain impurities are either partially or completely removed from the starting electrolyte.

Jan 1, 1987

By Richard J. Mainiero, James H. Rowland III, Marcia L. Harris

This paper reviews the potential hazards posed by the toxic fumes produced by detonating explosives in surface mining and construction operations. Blasting operations produce both toxic and nontoxic gaseous products; the toxic being mainly carbon monoxide (CO) and the oxides of nitrogen (NOx). The quantity of toxic gases produced by an explosive is affected by formulation, confinement, age of the explosive, and contamination of the explosive with water or drill cuttings, among others. Techniques to protect workers and the public from the potential hazards of explosive-related toxic fumes are discussed. These include: • Minimizing the quantity of toxic fumes produced. • Determining where the fumes may go so workers and neighbors can be moved out of harm’s way. • Preventing the fumes from moving towards workers and neighbors. • Monitoring the air near workers and neighbors so they can be relocated if fumes appear. • Ventilating structures or confined spaces until CO falls below a hazardous concentration.

By J. W. van der Merwe, A. S. Bolokang, M. J. Phasha, V. J. Matjeke, C. Moopanar

"Excessive wear rates on railway wheels can result in rolling-stock derailments. If wear is detected early the possible derailments can be prevented by prematurely replacing wheelsets, although the inventory cost and maintenance downtime remain a challenge. In the current study, wheels were introduced and monitored in-service for two years to investigate the cause of excessive wear rates. The wear rates and stresses were calculated for the wheels suitable for a maximum load of 26 t per axle. Microstructural and mechanical properties were analysed. As expected, the general microstructure of all the wheels tested was pearlitic. Although all the wheels complied with the tensile strength requirements, stress calculations confirmed material distortion on excessively worn wheels whereas trial wheels revealed yield strength exceeding the yield criterion. High wear rates observed on the wheels were a result of low yield strength relative to the load per axle. The typical wear mechanism found was due to a combination of rolling contact fatigue and abrasive brake wear. Despite compliance of the wheels with existing requirements regarding material and mechanical properties (hardness, ultimate tensile strength), it is recommended that the yield strength must also be taken into consideration as a critical parameter.IntroductionRailway wheels are used to support the wagon mass and guide the wagon along the tracks (Park, 1974). The wheels and rails must be able to tolerate the applied tangential forces in order to effect wagon dynamic performance and reduce material deformation (Ghidini et al., 1994; RSE_TE_SPC_0045, 2011; AAR M107/M 208 Specification, 2011. Over the past ten years, the South African coal wagon maintenance depot has experienced excessive hollow wheel wear rates on the heavy haul line wheels. The maximum load of Jumbo wagons on the coal line is 104 t, or 26 t per axle. Although the maintenance intervention cycle for wheelsets was two years, between February 2011 and August 2012 some wheels experienced excessive hollow wear. Hollow wear is regarded as wear exceeding 2 mm on the central portion of the wheel tread (RSE_TE_SPC_0045, 2011). This happened despite the fact that these wheels were manufactured and certified according to the requirements of AAR M107/208 standard for carbon steel wheels (AAR M107/M 208 Specification,. 2011) and the local wheel RS/ME/SP 021 standard specification (RS / ME / SP / 021 REV 5 (2013). The AAR standard only specifies a minimum hardness as a required mechanical property and the local standard specifies hardness and minimum tensile strength only. In general, an increase in hardness will improve the rolling/sliding wear resistance of steel. This relationship of hardness and wear resistance was found to be true only in a situation where solid and similar alloys are in contact (Singh, Khatirkar and Sapate, 2015). The sliding wear resistance of a material is usually estimated using Archard’s equation (Liu and Li, 2001)."

Jan 1, 2016

Allis Mineral Systems ARCO Coal Company Buckley Powder Co. CALCO, Inc. Coal Magazine Colowyo Coal Company Continental Conveyor & Equipment Company Crane & Hoist Sales Cummins Southwest, Inc. Energy West Mining Company Paul J. Epley FMC Corporation The Falkirk Mining Company Fleischli Oil Co., Inc. T. J. Gundlach Machine Company Halbach & Braun Harnischfeger Corporation Hemscheidt Corporation Hyatt Regency Beaver Creek Jennmar Corporation Joy Technologies, Inc. K&P Sales Engineers, Inc. Kennametal, Inc. Kerr-McGee Coal Corporation McLanahan Corporation National Coal Association The North American Coal Corporation Northwestern Resources Company Peabody Coal Company Phillips Machine Service, Inc. Pincock, Allen & Holt, Inc. Pittsburg & Midway Coal Mining Co. Roberts & Schaefer Company Rust Tractor Company Salt River Project Santa Fe Pacific Coal Corporation Schroeder Industries Shearson-Lehman Brothers Southern Pacific Transportation Stamler Corporation Trapper Mining Inc. Wagner Equipment Company Western Energy Company Wheeler Machinery Company

Jan 1, 1992

It is no longer satisfactory to assess the value of a coking coal on its intrinsic properties alone; its value depends upon its behaviour as a component in a blend. No single test can be used to make this assessment, it can only be made by carrying out a suite of tests. The quality parameters which are considered desirable, and which have widespread acceptance, have been discussed and their application to the blending of coals from New South Wales and New Zealand has been reported and discussed. Blending can be utilised to offset deficiencies, or capitalise on advantages, of the individual coals making up a blend. Coals can be blended, which alone are poorly, Coking, but which have compensating features. Blending also allows better exploitation of coking coal reserves. Several applications of blending have been reviewed with regard to coal producers and exporters, as well as coal users. The possibility of extracting a coking coal fraction from fuel coals is discussed. Blending systems and the coking of coal are also briefly reviewed.

Jan 1, 1971

By Albert L. Toenges, Theodore R. Jolley

"INTRODUCTION The construction of frame houses (fig. 1) in recent years instead of the conventional sod hut (igloo) (fig. 2) by the Eskimos in the villages along the Arctic Ocean has increased the demand for fuel in these villages. The frame houses, which are not insulated against extreme cold and are difficult to heat, are equipped with Goal stoves. The well-insulated sod huts were heated comfortably with whale-oil stoves. In some years whaling is Door, consequently there is a demand for solid fuel.The Eskimo villages usually are on the sand spits at the mouths of rivers and points of land near the best fishing and hunting grounds. These narrow necks of land usually are sand bars that are not underlain with coal, and coal must be transported to the villages. Lack of development of coal deposits in the Arctic has made it necessary to import coal from the States, generally from 'Washington, to supply these villages. This coal is imported by boat and is received once a year. Its cost is, high, and development of coal deposits in the Arctic to supply these native villages should result in a considerable saving to the Government-operated schools and hospitals as well as to the natives.Early traders attempted to establish coaling stations in the Arctic, and the Eskimos generally know where the coal deposits are situated. A. reconnaissance of a number of deposits in the Arctic was made in the summer of 1946 by engineers of the Coal Division, Fuels and Explosives Branch, Bureau of Mines, and this report describes the areas investigated and suggests plans for the development of some of these deposits."

Dec 1, 1947

By G. A. Grandy, P. F. Thomas, C. D. Danecki

When considering the mill drive system for a grinding application, a large number of questions must be answered. Depending on the mill size and type, the mill can be driven by several configurations of drive systems: a single low-speed motor connected to a pinion driving a ring gear, two low-speed motors connected to two pinions and driving a ring gear, or a gearless motor mounted directly. In addition, a gear drive system can have a reducer placed between a high-speed motor(s) and pinion(s) or a power path splitting pinion stand. In some designs the reducer is integral with the pinion stand driven by a high-speed motor. The technical and commercial implications of several mill drive options are presented. Initial cost, cost of installation, cost of commissioning, and cost of operation and maintenance are presented for each drive option considered. The impact of each drive system on the design, cost and operation of the overall plant electrical system is discussed. Also, consideration is given to mill drive availability, and the potential cost resulting from delays in plant production.

Jan 1, 2001

By Gheorghe Marin, Franco Chiesa, David Levasseur, Bernard Duchesne

Over the past 20 years, pressure die casting has evolved to a point where structural parts can now be produced by this process. This has been made possible by the development of vacuum die casting and by the development of die-castable, low iron content alloys. This resulted in the production of low porosity, weldable die-cast parts on which heat treatment may be applied. In the present paper, the influence porosities on the tensile properties of as-cast A360 tensile test bars was evaluated. This was done by casting 24 clusters, comprising three 6mm diameter test bars each, in a 280T cold chamber pressure die casting machine after a steady dynamic equilibrium had been reached. Modeling of filling allowed to explain the differences in porosity observed in the 3 samples of a same cluster while the results of solidification modeling were related to the microstructure. Tensile samples were radiographed on a real time X-cube apparatus and separated into 2 lots: samples where no porosity defect were visible and samples with visible defects. By measuring the tensile properties of the 2 lots it was possible to quantify the drop in tensile properties brought about by porosity, which is the most common defect observed in pressure die-cast parts.

Jan 1, 2015

By Samantha Smith

Nautilus Minerals (Nautilus) is following the lead of the petroleum industry as it strives to tap vast offshore resources. Planning is well underway for the Solwara 1 Project in the Bismarck Sea, Papua New Guinea (PNG) to recover high-grade seafloor massive sulphide deposits in 1600 m water depth. The deposit contains an average copper grade >10 times higher than a typical land-based porphyry copper mine. The high grades combined with a relatively small amount of overburden ensure the Solwara 1 Project will have a significantly smaller physical footprint than its land-based counterparts. Offshore minerals production also has the advantage of minimal social disturbance. Nautilus is dedicated to setting a high environmental and social responsibility standard. Nautilus recognises the importance of transparent and inclusive stakeholder engagement and has taken a proactive approach to involve as many key stakeholders as possible. One of the first steps in the permitting process in PNG is the preparation of the Environmental Inception Report, which describes the project, its envisaged impacts and the proposed studies for the Environmental Impact Assessment (EIA). Local (PNG-based) and international environmental scientists, anthropologists, NGOs and other experts were involved in the definition of studies conducted for the Solwara 1 EIA and a team of world-leading experts was involved with carrying out the studies, culminating in the preparation of the Environmental Impact Statement (EIS). To ensure transparency, collaborating researchers are free to publish their findings. Following its submission, the EIS was made available for public review and public hearings were held at several locations. The EIS has also undergone a rigorous independent review by PNG government-engaged consultants. Outside the permitting process, Nautilus works alongside government officials to carry out ongoing community consultations. Information dissemination and feedback acquisition has also occurred through the Nautilus website and attendance at a number of international conferences, workshops, and meetings. This paper will outline the leading edge approach Nautilus has taken in completing the environmental impact statement for the world?s first deep seafloor copper-gold mine. In addition, this paper will review the permitting process and the government and stakeholder engagement undertaken as part of Nautilus? desire to ?do it right? in this exciting new industry.

Jan 1, 2010

By Anthony (Sam) J. S. Spearing

Backfilling using coal waste is not a novel means for waste disposal throughout the world; yet, backfilling using a high density (paste) backfill is relatively new, except in Germany and Poland. One of the main benefits of a high density backfill, as opposed to a low density (slurry) backfill, is that, if placed at a low permeability and low moisture content, the risk of water table contamination can be relatively low. In addition, if paste backfill can be placed cost effectively, environmental benefits are huge because the surface impoundment footprint can be greatly reduced or even eliminated. This is especially true in room-and-pillar applications. In its current state, backfilling is considerably more costly than surface disposal. This is mainly because paste, as opposed to slurry, significantly increases backfill placement costs; however, this could be offset by increasing the achievable extraction rate. Overall, such a system could potentially improve the public?s image of coal mining in the US for a myriad of reasons. This paper discusses a proposed backfill system for a typical room-and-pillar coal mine in the Illinois Basin of the US and clearly shows the technical advantages, although costs are still higher with fill. The cost differential will likely reduce over time, in favor of the backfill option, as costs of traditional surface disposal increase, due mainly to ever-restrictive disposal regulations.

Jan 1, 2013

By Jacek Paraszczak

Numerous problems encountered in the mining of narrow vein deposits challenge the productivity, competitiveness and profitability of many mines. Mechanization of mining operations is one of the most important means to ensure the healthy survival of this mining sector. Vein deposits account for nearly all the world's primary silver production, as well as a significant portion of gold, tin, copper lead and zinc. In North America, narrow vein mining constitutes an important sector of the industry. Operators exploiting such deposits are concerned with the most appropriate mining method and equipment to mine in such a way as to minimize waste rock dilution. Unfortunately, most of the equipment available does not meet the additional geological and economical restrictions typical of narrow vein mining. Thus, mining these deposits is labor intensive and can result in low productivity. Consequently, the profitability of many such mines is reduced. Increased mechanization is one of the solutions to ensure their healthy survival. This paper reviews the state-of-the art in mining equipment with reference to narrow vein mining limitations. Problems encountered Geological conditions and economical factors have a decisive impact on the choice of mining method and equipment. Many ore bodies are relatively small, usually erratically distributed, often less than 2 m (6.5 ft) wide, with dips ranging from 0° to 90°. To make things worse, ore body limits are sometimes difficult to determine and the ground is hard and abrasive.

Jan 1, 1992

CLASSIFICATIONS: 1, Nonferrous metals. 2, Iron and Steel. 3, Petroleum and Gas. 4, Coal. 5, Industrial minerals. A, Geology, exploration. B, Mining and production engineering. C, Preparation and milling. D, Physical metallurgy. E, Administration and economics. F, Chemical metallurgy. G, General. ARIZONA HASTINGS. EARL F., P. 0. Box 10 Chloride 1-A,B,C, Denver Univ., Texas Call. Mines. Asst. chief metallurgist, Old Dominion Copper Co., '26-'29; mine examination and mill construction in Colo.. Ariz.. and New Mexico; mill supt., Arizona Molybdenum Corp.. 34; at present gen. mgr., Pioneer Gold Mng. Co. Specialty: mine examinations and flow sheets of gold and rare metal plants. Examinations limited in Mohave County, A.riz., for present.

Jan 1, 1936

By André Brasil

Dado que las represas de relaves construidas por el método de aguas arriba presentan deficiencias relacionadas con los aspectos constructivos y de seguridad, es difícil evaluar la variabilidad real del depósito basándose apenas en los procesos de campo. En ese sentido, el presente texto desarrolla un modelo para describir y simular el mecanismo de formación de las represas de relaves considerando las variables externas (concentración y caudal de descarga) e internas, así como muestra soluciones analíticas y numéricas comparados a nivel laboratorio.

Sep 9, 2007

By S Strong, L I. Sanz Vivanco, T Brown

One of the most significant technical and practical challenges facing the tunnel construction team on the Legacy Way road tunnel project in Brisbane, Australia was how to erect the prestressed precast concrete slabs to form the smoke duct in the tunnel boring machine (TBM) tunnels.An essential part of the tunnel ventilation system, the smoke duct extends the full length of the 4.6 km-long twin two-lane tunnels. The vast majority of the tunnels (approximately 4.3 km) were constructed using two 12.4 m diameter double-shield TBMs. The refurbished Herrenknecht machines broke several world records on the way to completing the tunnel excavation works in just over nine months. With the excavation complete the focus turned to solving the complex civil tunnel fit-out challenges. A key component of the civil fit-out of the tunnels was constructing the smoke duct in the TBM tunnels, which was designed as a precast solution.The slabs, which each measure 8.62 m long × 2.0 m wide × 200 mm thick and weigh close to 9?t, need to be erected above cast in situ corbels whilst other tunnel finishing works continue. The space-proofing clearance offered by the design to the support corbels below and the precast segmental lining above was in the order of only 100 mm.This paper tells the story of how the Transcity Joint Venture (JV) tunnel fit-out team comprising some of Europe and Australia’s leading tunnel construction specialists drew upon the global strengths of the existing JV member companies and the global reach of leading TBM manufacturer Herrenknecht to develop an innovative system in solving this challenging problem. This globetrotting story, which starts in Australia, visits Europe and mainland China before returning to Brisbane where it all began.CITATION:Brown, T, Strong, S and Sanz Vivanco, L I, 2014. How the global experience and reach of tunnelling’s true multinationals helped solve a road tunnel fit-out challenge, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 507–512 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By P. Rosario

"Industry practice for high-pressure grinding roll (HPGR) assessment and sizing relies on tests using pilot-scale machines with 0.7–1.0 m roll diameters. Typically 1–10 t of sample are required, depending on the level of study and resource complexity. This is challenging during early-stage development, which hinders incorporating HPGR into designs. With support from the Canadian Mining Industry Research Organization, researchers at the Norman B. Keevil Institute of Mining Engineering at The University of British Columbia developed bench-scale piston–die press tests (PPTs) that correlate to pilot- and full-scale HPGRs. This paper describes a new regression model to estimate the HPGR-specific throughput rate using both PPT results and an HPGR database. A case study is presented to show how the current PPT method is used for engineering studies. ¦ KEYWORDS Empirical modelling, High-pressure grinding roll (HPGR), Piston–die press test (PPT), Sizing and scale upRÉSUMÉ La pratique en vigueur dans l’industrie concernant l’évaluation et le calibrage d’un cylindre de broyage à haute pression (HPGR, de l’anglais high-pressure grinding roll) dépend d’essais menés à l’aide de machines à l’échelle pilote dont les diamètres de bobine sont de 0,7 à 0,10 mètre. On a généralement besoin de 1 à 10 tonnes d’échantillons en fonction du niveau de complexité de l’étude et des ressources. C’est une pratique difficile durant les premières phases de développement, qui empêche l’intégration du HPGR dans les plans. Bénéficiant du soutien de la Canadian Mining Industry Research Organization (CAMIRO, l’organisation de recherche de l’industrie minière canadienne), des chercheurs du Norman B. Keevil Institute of Mining Engineering (l’institut Norman B. Keevil de génie minier) de l’université de la Colombie-Britannique (UBC) ont mis au point des essais en laboratoire sur des presses à matricer à pis¬ton (PPT, de l’anglais piston–die press tests), qui mettent en corrélation les HPGR aux échelles pilote et réelle. Cet article décrit un nouveau modèle de régression qui évalue le taux de production spécifique aux HPGR à l’aide des résultats tirés des PPT et d’une base de données dédiée aux HPGR. Une étude de cas est présentée afin de décrire l’utilisation de la méthode actuelle des PPT dans les études techniques. ¦ MOTS CLÉS calibrage et mise à l’échelle, cylindre de broyage à haute pression (HPGR), essai sur presses à matricer à piston (PPT), modélisation empiriqueINTRODUCTION It is widely accepted that high-pressure grinding rolls (HPGRs) are a viable, energy-efficient solution for modern comminution flowsheet design. Table 1 summarizes select examples of HPGR applications in the mining industry. The main benefits of HPGRs are energy savings, which leads to lower operating costs, and stable operating characteristics that can better cope with variations in ore hardness compared to the conventional autogenous (AG) or semi-autogenous (SAG) mill-based comminution circuits."

Jan 1, 2019