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By B. Hilscher, P. Nayak, N. Yoon

"The mining industry is currently facing challenges with declining feed grades and is struggling to find solutions to improve the project’s economic value. By means of pre-concentration, ore sorting aims to separate the barren material from the valuable ore to reduce energy consumption and tailings generation, while increasing the feed grade, concentrate grade, mill recovery, and revenue. In addition, ore sorting allows the modification of deposit geometallurgy in order to allow the creation of an optimal mill feed.This paper evaluates the applicability and challenges of ore sorting by utilizing the results from four different mines, and reviews them in detail. The mines include two underground and two open pit mines that are base metal and precioius metal operations. In order to understand the applicability of ore sorting in these operations, initial rock-by-rock test results and different types of assays (atomic adsorption [AA], inductively coupled plasma [ICP], and fire assay) are utilized. Using the assay results, the grade recovery curves for ore sorting are generated and they are further improved by using and developing an ore sorting algorithm, which is discussed in this paper. The application and evaluation of ore sorting in greenfield and brownfield properties will also be discussed.The state of the art ore sorting technologies for both rock-by-rock and bulk sorting are reviewed in this paper. The future technologies on the horizon, including different combinations of sensors, are explained. The sorting technologies include, X-ray transmission (XRT), X-ray fluorescence (XRF), colour, infrared, electromagnetic, and laser induced breakdown spectroscopy (LIBS).IntroductionOre sorting is a sensor-based sorting technique introduced between the excavation stage and processing stage, where the unwanted waste is diverted to the waste dump and only the ore is sent to the mill for further processing. As a result, the quality of the material entering the mill is improved and the dilution of the ore is reduced. In greenfield projects, sensor-based ore sorting provides an opportunity to reduce the capital cost of the project and increase the return on investment (ROI). With most operations currently facing the challenge of finding a high grade deposit, having a sorting unit provides several advantages while keeping the cost at minimum."

Jan 1, 2017

By F. C. Gennari, D. M. Pasquevich

With the gradual exhaustion of natural rutile, there has been extensive research into its synthesising from lower-grade titanium minerals. The removal of Fe from pseudobrookite (Fe2TiO5) by chlorination was studied, using both isothermal and non-isothermal thermogravimetric measurements. Correlation of the results obtained from element distribution maps, scanning electron microscopy, energy-dispersive X-ray analysis and phases detected by X-ray diffraction in the chlorinated samples showed clearly two associated processes. First, the pseudobrookite particles reacted with chlorine and iron was removed selectively as FeCl3(g), leaving a solid residue rich in the TiO2 phases anatile and rutile, separated from an inner layer of unreacted pseudobrookite by a distinct interphase boundary. Second, chlorine allowed TiCl4(g) to form in the reaction bed, where it removed iron from the Fe2O3 crystals as FeCl3(g) and substituted Ti through a pseudomorphic reaction

Jun 21, 1905

By Derek T. Novotny

Blasting cap precision is of major importance to advanced blast design. New technologies have introduced the use of microchips within detonator casings in the hope that the electronic control of the timing element will increase the accuracy of the cap and therefore improve the results of perimeter control blasting applications. The electronic detonators have proven to be accurate in timing tests done to date. They boast cap scatter results to microsecond accuracy, but the question is, does this degree of accuracy actually prove to be beneficial during practical use in the industry, or are conventional technologies applicable.

Jan 1, 1998

China’s vibrant economic growth is built on coal, the source of two thirds of the country’s electricity. Over 95 percent of China’s coal is mined underground with the average mining depth at 410 m and in-creasing at 10 m per year; today, the deepest Chinese coal mines have exceeded 1,000 m. With increasing mining depths, there are greater challenges including increased methane emissions and spontaneous combustion. According to the government, nearly half of China’s coal mines are classified as gassy (with specific gas content at least 10 m3/mt). Coalbed methane (CBM) is a clean energy source. However, only a small percentage of the methane is captured, and the rest is vented directly to the atmosphere. This paper describes China’s CBM resource, its production and utilization.

Jan 1, 2006

By J. M. Cardoso, E. F. Quadros, A. Chiarini, F. Fernandes, G. Vilela, J. Ireno, L. C. Agostini

Based on the geological-geometric characterization of the basaltic rock at the site of a factory for chemical products situated in the Southern region of Brasil, and on results of a significant number of packer tests, the principal directions of flow were estimated, taking into consideration the intersection and the orientation of the joints and the amount of contaminant flow measured in each interval. The tests were performed using the multi-packer hydraulic multitest probe of IPT (HMTP) instrumented with an electric conductivity meter. A method of analysis for three-dimensional evaluation of the amount of contaminant flow in the area was proposed for future mitigation of the problem. Basé sur une caractérization géologique-géotechnique de la roche basaltique existant sur un site dune fabrique de produits chimiques située au sud du Brésil et sur les resultants dún nombre significantif déssais du type packer, les directions principales d´écoulement ont été estimées en considerant l´intersection et orientation des joints et la quantité de contaminant mesurée sur chaque intervale d´essais. Ceux-ci ont été realizes en utilisant une sonde multipacker developée au IPT – São Paulo (HMTP) instrumentée avec un mesureur de condictivité électrique. Une méthode d´analyse 3-D pour l´évaluation du transport du contaminant sur ce site a été proposée pour une future mitigation du problème. Auf Grund der geologischen Struktur des Basalts auf dem Gelände einer chemischen Fabrik in Südbrasilien und der Ergebnisse einer ansehnlichen Zahl von Pumpversuchen wurden die Hauptfließrichtungen bestimmt unter Berücksichtigung des Kluftgefüges und der in jedem Intervall gemessenen Menge kontaminierten Wassers. Die Versuche erfolgten mit dem im IPT entwickelten Verfahren (HMTP) mit Mehrfachpackern und elektrischen Leitfähigkeitsgebern. Ein analytisches Verfahren zur dreidimensionalen Ermittlung der Mengen kontaminierten Wassers wurde für die künftige Befassung mit dem Problem entwickelt.

Jan 1, 2003

?Longhole blast hole drilling? techniques are not new to the mining industry. Appropriate mechanization and improvement of the techniques and application has evolved from the industry requirements. Today safety and economics play a larger role in the excavation of ore passes, ventilation passes, and relatively small inclined excavations in the conventional gold and platinum industry. The application of dropraise drilling from the top or from the bottom is discussed investigating the current techniques available, DTH application, advantages and disadvantages, limiting factors, typical layouts and proposals, the drop raising technique and future applications. Similarly, the application of longhole blast hole drilling in tabular and massive orebodies is discussed with emphasis on the DTH application, advantages and disadvantages, limiting factors, typical layouts, the long hole stoping techniques and future applications.

Jan 1, 2003

By K. Cybulski

In 2002 a coal dust explosions occurred in the Polish collieries “Jas-Mos” and “Rydultowy” in the Upper Silesia coal basin. In the “Jas-Mos” colliery the coal dust explosion was initiated in the face of gallery by explosives and causing ten death. The stone dust barrier extinguished the flame, stopped the explosion development and saved forty nine miners working in that area. In the “Rydultowy” colliery methane inflammation caused three deaths and seven serious burns and ignited the coal dust explosion. The coal dust explosion was stopped by stone dust barrier and did not cause any victims itself. This paper presents the investigation carried out by the Central Mining Institute Experimental Mine “Barbara” and shows that the stone dust barriers remain still a basic mean for suppression of coal dust explosion in mines. The investigation were aimed at determining the cause of explosion and circumstances that led to their propagation. The evaluation of the state of dust explosion hazard in the areas of accidents have been performed, and the range of flame estimated.

Jan 1, 2003

By A. M. Gaudin

This year the American Institute of Mining, Metallurgical and Petroleum Engineers has chosen to give me its Robert H. Richards Award, a distinction which is widely regarded as the highest honor in the field of mineral engineering. I am deeply moved by this tribute, which suggests not only regard for my service to the profession but also the affectionate esteem of my fellow mineral engineers. You have made me happy at the prospect of the permanent association of my name with that of Robert Hallowell Richards and of the distinguished recipients of the award, Arthur Fay Taggart, Frank R. Milliken, John F. Myers, Edward William Englemann, C. Harry Benedict, Edward W. Davis and Arthur W. Fahrenwald. I wish to thank you all for an honor so generously bestowed. Professor Richards is known to us all as a legendary figure, and we can read about him in the Richards Memorial Volume of our Transactions. Some of us have even had the good fortune of knowing him. I count myself among those lucky few. In its intangible attributes the Award recalls those things for which Professor Richards stood: for Science in Art, for thoroughness, for meticulous accuracy, for bold imaginativeness, most of all for professional integrity. Now, as in his day, these attributes are central to an engineer's creed. They are appropriately needed in a formulation of a definition of the mineral engineering profession.

Jan 6, 1957

By A. Asadi

Subsidence phenomenon as an unwanted consequence of underground mining can cause problems for environment and surface structures in mine area. Surface subsidence prediction for inclined and steep seams has been given less attention than horizontal seams due to the difficulties involved in the extraction of such coal-seams. This paper introduces a new profile function method for prediction of surface subsidence due to inclined coal-seam mining. The results of calculation with the new function indicate that the predicted value has good agreement with the measured data. Keywords: subsidence; coalmining; caving mining methods; longwall mining; profile function.

Jan 1, 2005

By S. J. Lötter, J. T. Nel, W. Purcell

"SynopsisGlow discharge optical emission spectroscopy (GD-OES) is an analytical technique used in the analysis of solid, conducting materials. Though primarily of interest as a depth profiling technique on samples with varying layers of both conducting and non-conducting materials, it is also capable of rapid bulk analysis of homogenous, solid samples. GD-OES combines the advantages of ICP-OES (wide detection range, speed, and lack of interferences) with the solid sampling of XRF techniques. This allows the analyst to not only quantify the elemental composition of a sample, but to evaluate it in terms of homogeneity with depth, a field in which auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) have traditionally been the primary techniques. Although GD-OES does not replace these useful techniques, it does offer various advantages over them, making it an excellent complementary analytical tool.In GD-OES analysis, a low-pressure glow discharge plasma is generated with the sample material acting as a cathode, accelerating the cations in the plasma towards the sample surface. This bombardment causes the sample material to ‘sputter’, essentially knocking free atoms or molecules of analyte material, which are then drawn into the plasma where they are excited. The light emitted by this excitation is then diffracted to separate the wavelengths emitted by the specific elements and detected by a spectrophotometer. The intensity of the signal is directly proportional to the quantity of analyte element present in the sample, allowing simple calibration and quantitative determination of the elements. Technological improvements made in the past twenty years or so have significantly increased the usefulness of GD-OES for surface analysis. Faster plasma stabilization and start-up allow for the quantification of surface layers as thin as 1 nm. Sputter rates have been accurately measured for many common materials, allowing them to be built into software libraries in the instrument’s control software. This dramatically expands the usefulness of this software and the ease of performing analyses.GD-OES analysis of nuclear materials allows for the rapid determination of the elemental composition without the requirement of initial dissolution. The thickness of any corrosion layers on nuclear materials can also be determined."

Jan 1, 2015

By Wils L. Cooley

Although electric utility companies have been active in grounding and bonding within substations, the mining engineer or mine electrical engineer is not involved to the extent that he can be fully up-to-date on the most effective practices for substation construction. The coal mine power system is grounded in a fundamentally different way from most other industrial power systems and is subject to considerable Federal and State regulation. At this time, there is little information that is directly applicable to the mine situation, especially if the substation must be built in an area of limited size or in low-conductivity earth. The objective of this guide is to provide specific engineering information to the mining; industry. Using as little theory as possible, it was written to be general enough to cover most substations, but specific enough to provide direct help with each substation. It will attempt to recommend practice that is in agreement with present Federal rules and regulations.

Jan 1, 1980

By J. C. Duchon

The U.S. Bureau of Mines is conducting human factors research for the purpose of reducing accidents and improving the person-machine interface found in surface and underground mining operations. Miners are exposed to a variety of environmental stressors, e.g., extreme heat, noise, vibration, and adverse illumination, throughout the workday. Exposure to these environmental stressors has been noted in the literature to affect performance on vigilance tasks. Since impaired performance at vigilance tasks can lead to industrial accidents, further investigation of the effects of environmental stressors on human performance is warranted. A brief description of the environmental conditions present in the mining workplace is followed by a review of experiments dealing with the effects of environmental stressors on vigilance task performance. The applicability of past research to actual mining operations is considered.

Jan 1, 1989

The objective in controlled blasting is to reduce overbreak to control the final pit wall slope, shaft, drift ditch, bench, etc. to the final planned excavation limit. The six main types of controlled blasting utilized today are: 1) Line Drilling 2) Cushion Blasting 3 Smooth Wall Blasting 4) Buffer Blasting 5) Presplitting or Preshearing 6) Air Deck Presplitting

Jan 1, 1992

By P. K. Frempong, S. D. Butt

"A case study for the application of a novel geostatistical technique for resource estimation of a narrow steeply dipping, gold-silver mineralized quartz vein deposit is presented. The technique is novel in two respects. First, mineral grades are kriged directly rather via the accumulation method more often applied to vein deposits and, second, a modified 2D ordinary kriging algorithm is used that allows the calculation of a single grade and variance for irregular shaped blocks of varying sizes. The objective of this investigation was to evaluate the suitability of this novel geostatistical technique for resource estimation of the Poura mine deposit and, if appropriate, to lay a firm foundation for future geostatistical work at the mine.The reserve estimation concentrated on the remnant ore blocks and pillars in both underground and surface workings. The data, which was collected in 2D coordinates with grade and vein thickness values, was first analyzed statistically and used to compute experimental semi-variograms. Appropriate semivariogram models were fitted and various aspects of the estimation technique were evaluated using cross-validation error analysis, with acceptable results. A block kriging computer program called Krige2D was developed to implement the modified 2D kriging algorithm and calculations. Production data were not available to evaluate the computed block resources, but they were compared with a previous resource data determined using an arithmetic approach. The geostatistical technique estimated slightly higher grades but lower overall tonnages as compared to the earlier arithmetic estimates."

Jan 1, 2004

By K. Barr, F. Grenier, J. Hettinger

"To reach the Hemlo Gold Inc. objective of becoming the lowest cost, safest Canadian gold producer while causing no environmental damage, management embarked from its inception on a strategy to build an organization which would foster employee involvement wherever possible. This paper describes the organizational structure and how various innovative concepts have been implemented.BACKGROUNDThe Golden Giant Mine in the Hemlo area of North Western Ontario is owned by Hemlo Gold Mines Inc. 50.1% is controlled by Noranda. The mine commenced operations in March 1985 at a modest production rate. After it reaches full production by the end of 1988, with completion of underground development work, the mine is expected to operate at 3000 t/d and produce in excess of 300,000 ounces of gold per annum. This makes it one of the three largest producing gold mines in North America.Two other companies, Lac Minerals and Teck-Corona, operate mines on either side of the Golden Giant Mine. Noranda Geco Division is located 55 kilometers to the north at Manitouwadge. The majority of Hemlo Gold's 270 employees live in Manitouwadge where a mix of accommodation was constructed and made available for purchase by employees. Bus transportation is provided to and from the workplace with modern coaches. The housing and transportation policies were implemented prior to start-up and designed to help attract and maintain good employees.As shown in Figure 1, the operation is divided into five operating and support departments with each reflecting a high degree of departmental control and responsibility. For example, the mill department is responsible for all aspects directly relating to the milling complex including safety, operation, mechanical maintenance, assaying, instrumentation, and environmental control. Similarly, the mine department is responsible for all phases of operation, mine engineering, geology, and maintenance of underground mobile equipment. The plant department is responsible for maintenance of hoisting plants and conveyances, underground stationary equipment, all site electrical services, surface buildings, housing and yard maintenance. Efforts are made at every level of the organization, from departmental organization to individual job assignments, to ensure responsibilities are clear and that they encompass complete functions."

Jan 1, 1988

By Pierre Roy, Claude Gosselin, Maryam Sadeghi, Michel Bourassa, Christian Rochefort, Claude Bazin, Gautier Mahieu, François Lavoie, Marilène Renaud, David Cataford

"Spirals are gravity concentrators used for the concentration of iron oxide minerals from ores. This paper presents the mineral size recovery curves observed for spirals operating in two Canadian iron ore processing plants. The size recovery curves are presented for rougher, cleaner and re-cleaner spirals. The partition curves observed for the spirals are significantly different than those observed for typical gravity concentration devices such as hydrocyclones or hydraulic classifiers. The size recovery curves show the complex behaviour of the minerals as they flow down a spiral and are analysed with a view toward process modelling and simulation. Initial simulation results show that gains in the iron recovery can be achieved by increasing the recovery of coarse iron oxide particles in the rougher spirals.INTRODUCTION Spiral concentrators are gravity based separation devices used for the preparation of coal, iron and different heavy minerals ores (Wills, 1992). The classification of the particles in spirals is based on the combination of gravity, centrifuge, drag, lift and Bagnold forces (Atasoy and Spottiswood, 1995; Burt, 1984; Bouchard, 2001). Several papers are dedicated to the analysis of the forces acting on the particles flowing down a spiral (Das and al., 2007; Sivamohan and Forssberg, 1985; Holland-Batt and Holtham, 1991; Holtham , 1992). Most of these papers aim at the development of a general model for the simulation of the classification of the particles for coal ore processing. Few papers deal with the operation of spirals for processing iron ores (Hyma and Meech, 1989; Srivastava, 2001; Dallaire et al., 1978) and fewer papers present results for spirals used as cleaners following a rougher stage. Since the classification in spiral classifiers is dependent on the particle size and specific gravity a partition or performance curve commonly applied to classifiers (Mai Manga et al., 2012) is used here to analyse spiral operation. Few papers were found to describe the operation of spirals in terms of partition curves (Atasoy and Spottiswood, 1995; Holland-Batt and Holtham, 1991; Richards et al., 2000). Most of the investigations presented the application of a model to simulate the position of coal particles of various sizes and specific gravities along the trough of a spiral (Kapur et al., 1996; Holland-Batt and Holtham, 1991). In addition most of the available literature on spirals deals with one stage of concentration by spirals (Dallaire et al., 1978; Das and al., 2007; Sivamohan and Forssberg, 1985) while industrial circuits usually consist of rougher and cleaner spirals."

Jan 1, 2014

By R. P. Vinson

Assessment of workplace exposures is an important tool for helping to minimize dust-related occupational illness and diseases. Real-time particulate monitoring can effectively locate areas where dust controls are needed and determine how well they are working. An affordable, person-wearable, real-time dust monitor is needed. The SKC Inc. Dust Detective (SKCDD) fulfills those requirements (Disclaimer: Mention of any company or product does not imply endorsement by NIOSH). The SKCDD consists of a disposable sampling tube (DST) connected to a small hand-held sampling pump. The SKCDD was developed through a Cooperative Research and Development Agreement (CRADA) between the National Institute of Occupational Safety and Health (NIOSH) and SKC Inc. The relationship of dust concentrations measured by personal gravimetric samplers to those measured by the SKCDD was determined in a laboratory aerosol chamber. A comparison of the means and the relative standard deviation of triplicate measurements of each type of sampling device demonstrated the SKCDD to be a viable alternative means for measuring dust. While it provides accurate measurements for specific coal types, it requires correction factors (those correction factors still need to be calculated) for other coal types.

By D. E. Pollock, J. A. Organiscak

Water sprays and water powered scrubbers have both been utilized in the mining and milling industry to suppress airborne dust. Unconfined water sprays operated at lower water pressures of ?689 kPa (?100 psig) can be very effective at wetting the mine product at the dust source and significantly reducing the amount of respirable dust that becomes airborne. However, unconfined waters sprays can be somewhat ineffective in actually removing airborne dust from the air. On the other hand, water powered scrubbers operating at higher water pressures of ?1,724 kPa (?250 psig) in physical enclosures or ducts have previously been demonstrated to be very effective in removing airborne dust from the air. These higher operating water pressures are uncommon in many mines and mills, so their use is limited. The National Institute for Occupational Safety and Health (NIOSH) recently investigated the performance of a lower-pressure, water powered inline series spray scrubber for removing localized airborne dust emitted at the source. Results showed noticeable improvements in airborne dust capture efficiency through the operation o f multiple inline series hollow cone spray nozzles within a round duct or pipe at the same water pressure as a single spray. Operating hollow cone spray(s) at higher water pressures noticeably improved airflow through the scrubber and yielded some additional scrubber efficiency improvements. Thus, in-line spray scrubber efficiency trade-offs were observed to be made by altering spray power components of water pressure and/or quantity (number of sprays). Results show that, on average, up to 0.23 and 0.32 m3/s (484 and 679 cu ft per min) of airflow at 0.81 and 0.69 dust capture efficiencies can be achieved with three 81° and 33°hollow cone inline series sprays, respectively, operating at 1,655 kPa (240 psig).

By F. Hassani, K. Moozar, J. Ouellet, P. Gauthier

"This paper describes a sudden spill of waste rock used for backfilling from a waste pass at an underground mine in Canada, thus causing a major failure/accident. The mine operator immediately launched a detailed investigation to understand the causes of this accident and develop procedures to prevent any recurrence of such events in the future. The authors from McGill University were invited to collaborate with the engineers at the mine to examine this accident. The events leading to the accident were studied, appropriate measurements were taken and samples of the waste material were collected for further testing and analysis.The field visit and the interview of the witnesses allowed the detailed documentation of the events. The sequence of events related to the incident, along with the experimental results obtained in the course of the investigation, are presented. The waste material was characterized in the laboratory with regard to its behaviour in the presence of water. This information is discussed and the failure mechanism involved in the accident is identified. Finally, the full recommendations as well as the immediate operational measures implemented by the mine to prevent the future occurrence of such events are presented and discussed."

Jan 1, 2004

By Hassan Ghaffari

? HPGR Process/Overview ? HPGR vs. SAG ? The Manufacturers ? Mine Operations using HPGR ? Projects by Wardrop/Tetra Tech ? Economic Benefits ? Questions Main Operating Parameters ? Press Force (N/mm2) ? Roll Speed (m/s) ? Moisture Content (%) ? Feed Particle Size Distribution Specific throughput M* = throughput/D*L*V (ts/hm3) Flake thickness/strength in balance with the compressing force (floating roll situation)

Aug 1, 2013