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By X. Zhang, Z. T. Yuan, C. Zhang, H. M. Zheng, X. M. Wang, L. X. Li, N. Li

In metal mines, comminution is commonly used to liberate minerals for subsequent mineral concentration processes, such as flotation, magnetic separation and gravity separation. However, ores are aggregates of valuable minerals and their disseminated gangue minerals, and these minerals exhibit diverse comminution behaviours. In carbonate-bearing iron ores, hematite, siderite, and quartz are the predominant minerals, of which hematite is the objective recoverable mineral. In this regard, the present study aimed to identify the imperfections in siderite minerals by X-ray computed tomography (XCT), and thus quantitatively characterise their size and shape in terms of Feret diameter and aspect ratio, as well as other parameters. XCT images indicated the protogenetic ubiquity of pores <5 μm in diameter and cracks of 7-8 μm inside siderite particles. In the ground product of artificially mixed siderite and hematite, siderite particles were smaller than hematite particles. Siderite particles had a larger surface area and greater surface roughness than hematite particles of the same volume, which was attributable to the intrinsic holes and cracks in siderite particles. This study provides an insight into the relationship between the inherent imperfections of minerals and their comminution properties. Keywords: Siderite; X-ray computed tomography; particle imperfections; grinding behaviour; sliming

Jan 1, 2020

By Alexander L. Holley

(WITH FIGURES ON PLATE I.) A CHARACTERSSTIC, and, to Americans, an amusing discussion of the three-high rail-mill, arose out of the reading of Mr. Lauth&apos;s paper on three-high plate-mills, at the Glasgow meeting of the Iron and Steel Institute. From the report of the meeting in the English papers, it appears that Mr. Menelaus, the celebrated rail-maker of Dowlais, could not wait for the discussion of Lauth&apos;s plate-mill, but launched at once into the British objections to the three-high rail-mill, which is quite another matter. The American mill, which is very different in principle and ar-

Jan 1, 1873

By H. A. Pearse

Introduction This paper may be regarded as another instalment of the story of the Britannia milling operation. From time to time in the past, articles (1) have been prepared by various members of the staff, giving details of crushing, grinding, and flotation treatment for the normal Britannia ore. It is not, therefore, the purpose of the present paper further to discuss what may be termed the standard milling operation, but rather to describe a flotation practice which has been evolved directly as a result of the general depression. The normal Britannia ore mixture contains chalcopyrite and pyrite as the main sulphide minerals, together with minor gold and silver values. The standard milling practice, evolved during several years of experimentation, provided for bulk flotation of the two sulphides after primary grinding to only approximately 35-mesh, followed by regrinding of the bulk concentrate, with subsequent separation of the chalcopyrite and pyrite to make a marketable concentrate of each mineral. However, in the face of a constantly increasing surplus of copper on the world markets and a steadily falling price during 1930 and 1931, it was obviously undesirable to continue producing large quantities of this metal at a loss. On the other hand, Company officials were very reluctant to add to unemployment by closing down entirely, provided operations could be continued without excessive losses. Fortunately, the existence was known of a fair sized body of ore, quite low in copper and relatively high in zinc content, with also a very considerably higher gold value than that prevailing in other sections of the mine.

Jan 1, 1934

By H. A. Pearse

NORMALLY, the Britannia ore mixture contains chalcopyrite and pyrite as the chief sulfide minerals, together with minor amounts of gold and silver and a low zinc content. Reduction is accomplished by jaw crushers underground, followed at the concentrating plant by Symons cone crushers, rolls, and ball mills. The standard flotation practice, evolved during several years of experimentation, provided for bulk flotation of the two sulfides, after primary grinding to only approximately 35 mesh, followed by regrinding of the bulk concentrate, with subsequent separation of the chalcopyrite and pyrite to make a marketable concentrate of each mineral. This so-called standard milling practice has previously been described in detail in U. S. Bureau of Mines Information Circular 6619. A modification will he discussed here. In the face of a constantly increasing world surplus of copper and a steadily falling price during 1930 and 1931, it was obviously undesirable to continue unprofitable production of large quantities of this metal. On the other hand, company officials were

Jan 1, 1934

By N. P. Kripakov

Results of a complex three-seam interaction analysis in a western U.S. coal mine are presented. The physical situation simulated by the models represents the development of a set of entries underneath two previously mined seams with all three seams in proximity to each other. The layout and the geometry of the remnant pillars in the upper seams were nonuniform and not always directly superimposed over each other, creating a very challenging modeling problem. The U.S. Bureau of Mines&apos; MULSIM/PC computer code was upgraded and enhanced to perform the required three-seam interaction calculations. Analysis was limited to simple linear-elastic assumptions as only peak stresses were required. Results clearly indicated that stress concentrations in the lower seam increased approximately 100 percent when compared to cases simulating no extraction in the two upper seams. These stress concentrations generally occurred in zones directly below points of highest abutment pressures in the upper seams. Overall, the model results compared favorably with actual documented observed behavior where roof failures were known to have occurred.

Jan 1, 1996

By Hamid Maleki

In this paper, the authors present a review of data gathering programs and stress analyses for improving mine layout designs at BRL mines located near Paonia, Colorado. BRL and other companies have used both longwall and continuous miner methods for the extraction of the Upper D, Upper B, Lower B and C seams from the multiple-seam reserves in the North Fork Valley. Historic mining in the B and C seams has created stress footprints in the neighboring unmined seams compounded by stress transfer from recent longwall extraction in the Upper D Seam. Thus optimum positioning of workings in the remaining reserves requires careful collection of pertinent data and consideration of load transfer from previous workings through remnant abutment pillars. Based on long-term subsidence monitoring, underground mapping and stress analyses, we have confirmed initial load transfer analyses finding mild interactions between the UD and LB workings, and the mining conditions have proven to be good and manageable during the development stage of the LB Seam. This has been achieved through prudent mine planning, prudent positioning of the gateroads in multiple seam workings and support allocations.

Jan 1, 2007

By Massimilinao Svetina

In 2010 Danieli & C. S.p.A. put into operation a new Pickling Tandem Mill in Cremona (Italy) at Acciaieria Arvedi, the last Pickling line coupled Tandem Cold Mill (PLTCM) in Europe. The plant was tailor-made to suit the specific requirements of this customer; a very broad range of sizes and grades (IF to AHSS as well as DP and TRIP1000) including ultra-thin hot band can be processed, achieving a total capacity of 1.6 Mt/y. The Danieli & C. S.p.A. Turboflo® process was selected because of its proven efficiency and ability to handle ultra-thin gauges at speeds exceeding 400 mpm in the pickling tanks. All the equipment, i.e. pickling section and rolling mills was provided with the last generation of Danieli market-oriented technologies. Danieli & C. S.p.A. - with the support of Arvedi and feedback from the field - is continuously improving its technical design solutions and optimizing plant operations.

Aug 16, 2017

By Dorothy B. Niell, O&apos

In its first three years of operations, the in-house programs of the continental Shelf Division of the Marine Minerals Technology Center (MMTC/CSD) have focused on the development of drill systems - technology and the improvement of techniques and applications of reconnaissance methods to marine mineral deposit characterization. Many of the technological advances made to date have been in direct response to specific requests from industry for drill systems needs, and from federal and state agencies seeking technical support for various research efforts. These cooperative programs have proven to be an extremely efficient and effective way for the MMTC to achieve some of the main program goals that were established for the organization at the outset: primarily, to encourage and assist U.S. industry in marine minerals research activities and to encourage cooperative work among research institutions, government agencies, and industry. The primary achievements of the MMTC/CSD to date include the development of the Remote Placer Drill System for rapid reconnaissance drilling of precious metal placer deposits (including both pneumatic prototype and hydraulic production

Jan 1, 1991

By Pinnaduwa H. S. W. Kulatilake

To exploit an underground mine effectively and safely, it is important to have a good understanding of the geotechnical behavior of the rockmass surrounding the underground mine excavation. The aim of this study was to investigate, at the threedimensional level, the geotechnical behavior around a tunnel excavated in a metal mine in China. A three-dimensional numerical model was built by using the 3DEC software package to simulate a tunnel excavation under a high in situ stress condition and by relying on the information available on lithology, geological structures, in situ stress measurements, physical and mechanical properties of intact rock, discontinuities, and interfaces between different rocks. The authors also investigated the effect of the discontinuity network, possible intact rock and discontinuity parameter variability, representation of rock masses as discontinuum or equivalent continuum material and rock support system on the deformation, and stability around the tunnel. A very good agreement was obtained between the collected field deformation monitoring results and the results of the conducted numerical stress analyses with appropriate geomechanical property values.

Jan 1, 2013

By N. Kernahan, T. Zaniewski

Threshold blasting involves the use of small amounts of high explosive to break and fragment hard rock without having to evacuate mining personnel. The method is easily assimilated and effective in rockbreaking, but requires rigid control on drilling, charging and timing. Current underground trials are aimed at fine-tuning the amount of explosive energy and blast hole geometry to allow the firing of multiple sets of shot holes in a continuous manner. Through correct procedures, the after-blast fumes, dust and fly rock can be contained so as to provide a safe working environment. Threshold blasting hugely reduces the volumes of explosives used in mining and brings to maturity the potential of the process begun by Alfred Nobel when he introduced nitroglycerine, and later dynamite, to mining. Its key contribution is its enabling of continuous mining operations with well understood and relatively low cost technologies. The use of batch blasting, employing large burdens holds the greatest potential for delivering high flow rates of ore at minimal cost. There is good potential for rapid evolution of the concept.

Sep 1, 2001

Threshold blasting involves the use of small amounts of high explosive to break and fragment hard rock without having to evacuate mining personnel. The method is easily assimilated and effective in rockbreaking, but requires rigid control on drilling, charging and timing. Current underground trials are aimed at fine-tuning the amount of explosive energy and blast hole geometry to allow the firing of multiple sets of shot holes in a continuous manner. Through correct procedures, the after-blast fumes, dust and fly rock can be contained so as to provide a safe working environment. Threshold blasting hugely reduces the volumes of explosives used in mining and brings to maturity the potential of the process begun by Alfred Nobel when he introduced nitroglycerine, and later dynamite, to mining. Its key contribution is its enabling of continuous mining operations with well understood and relatively low cost technologies. The use of batch blasting, employing large burdens holds the greatest potential for delivering high flow rates of ore at minimal cost. There is good potential for rapid evolution of the concept.

Jan 1, 2002

By T. M. Louw, L. Auret, S. M. Bradshaw, F. F. Noelle

Modern industrial processes undergo frequent process state shifts due to changes in demand, feedstock or maintenance operations. Multimodal continuous process monitoring is therefore required for effective plant operation. Steady state analysis is a key component in effective multimodal monitoring. Various issues still remain in determining the starting and ending times of transition states. High dimensionality of process data is a characteristic that makes it difficult to select variables to consider when conducting steady state analysis. In order to address these problems, steady state detection on the principal component space is proposed. First, data undergoes principle component analysis to reduce dimensionality, then existing multivariate steady state detection algorithms are applied on the principle component scores. A novel algorithm, threshold PCA-SSD, is proposed and compared to an existing technique for steady state detection. The algorithms are investigated on high dimensional synthetic data Keywords: Multimode process, steady state detection, principle component analysis

Jan 1, 2020

By Thomas H. Dubaniewicz

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approximately proportional to beam diameter for beam diameters from 0.1 to 2.0 mm. Results suggest that relatively powerful beams may be used in these atmospheres without causing ignition, provided the beam diameter is controlled. Threshold ignition delay times using 91125 and 62.51 125 pm fibers were approximately proportional to the inverse square of the laser power. Ignition delays were about 45 ms or longer for laser powers up to 800 mW. Preproduction samples of a commercial optical fuse prevented ignitions under selected test conditions. A self-healing effect was observed for one sample. Comparisons are made with the results of other researchers. O 2006 Laser Institute of America. Key words: propane ignition, butane ignition, laser ignition, nonbeam hazards, fiber optic fuse

May 3, 2006

By Allan King

Ammonium Nitrate (AN) is most commonly encountered as either a prilled solid or a highly concentrated aqueous solution, with or without organic ( e.g amine) nitrates. Under certain conditions of fire exposure involving prilled or solid AN, the molten state can be formed. The shock sensitivity of the molten material at temperatures greater than 220 Celsius has been found to be much higher than that of the prilled or solid form. Molten AN can be a precursor to events leading up to explosion of a bulk prill storage pile as a result of fire exposure. The explosion hazards presented by molten AN are a function of two factors; 1) its shock sensitivity and the deflagration to detonation ( DDT ) properties of the molten material, and: 2) the ability of large masses of unfueled prilled AN to be initiated and detonate. This paper presents the results of tests designed to determine the shock initiation and DDT properties of the solid ( prilled ) and molten AN.

Jan 1, 2008

By R. J. Piniazkiewicz

Talc orebodies are mined in Asia, Australia, Europe, North America, and South America. Operators in North America must be efficient quality suppliers to thrive in a talc market in which many overseas suppliers have advantages such as lower hourly wages, shorter distances to ports, and less government regulation and intervention. Continuous improvement through teamwork and innovation is needed in the following areas to thrive amidst worldwide competition: 1) Maximization of the in-place value of ore. 2) Research and development to yield new processes and products. 3) Safe productivity. 4) Involvement in legislative processes. 5) Wellness programs to lower health care costs.

Jan 1, 1993

Gold mining in Waihi spans three centuries and five generations. Following the discovery of gold in 1878 the Martha Mine was developed and the town of Waihi grew up around it. Now, five generations later, descendents of many of the original settler families continue to live and work in Waihi. Many have returned to mining, in jobs far removed from those of their parents or grandparents. &nbsp; Members of three local families were interviewed on video. This paper is a summary of some of the major themes and gives some insight into the role gold mining played in the development of the region and its continued its importance today.

Jan 1, 2006

By S Agdaca

Leightons is the sole contractor at the Wahana Coal Mine Project (part of the Bayan Group), a multi-seam thermal deposit consisting of 13 coal seams with thicknesses ranging from 20&#160;cm to 500&#160;cm. The average dip of the deposit is 18 - 20&#176;. However the deposit is heavily faulted in certain domains with anticlinal and synclinal structures present causing seams to dip up to 90&#176;. Average thickness of coal inter-burdens range from less than 2 to 12 m. The minimum coal thickness being mined is 20 cm. Coal production is direct mine mouth feed and there is no coal processing plant currently used.Conventional blasting between the highly variable coal horizons in the early phases of the mine life was suboptimal from a production perspective. Drilling short holes with a reduced drill pattern, and on occasions with sloping benches, resulted in low drilling and explosives loading efficiency.A high frequency of small size blasts fired up to two times daily was required with each blast consisting of four up to five small blast areas. Each blast averaged approximately 36&#160;000 bcm thus causing a low utilisation rate of the mining fleet from frequent blast delays and the inability to deploy larger Liebherr 9350 excavators on bench. It was identified that increasing the production targets required a more efficient drilling and blasting process. Furthermore, due to the highly variable nature of the deposit, the existing coal model was determined to not be able to accurately predict the coal seam location prior to blasthole drilling.In August 2009, Leighton Contractors Indonesia and Orica Mining Services with the full support of the Wahana team, initiated through seam blasting trials using electronic blasting systems. Further trials were conducted in November 2009. Trial evaluations indicated that the benefits from decreased lost time events due to blasting, an increased vertical advance rate per blast, and increased overall blast size could be attained while not damaging or diluting coal.Full-scale?through seam blasting has been ongoing since February 2010 for the upper eight coal seams to extract coal seam thicknesses ranging from 20 - 100 cm. This paper will discuss the parameters of the through seam blasting process in Wahana and the resulting benefits to the overall mine production.

Nov 8, 2011

By Guy T. McBride

The 1970&apos;s have been considered a pivotal decade for the mineral industries. Undergraduate mineral engineering education is relevant to this theme; in particular, there are three interrelated problems: 1) The goals, and therefore the course requirements, of the under- graduate curricula are in question; 2) The unit costs of undergraduate education appear excessive to those who bear the charges; and 3) The present social ambience detrimentally affects the work attitudes and career motivation of both prospective and in-course students. Any discussion of these problems must bottom upon recognized national needs for minerals and a technologically sound minerals industry staffed by competent engineers, particularly at the exploration, development and production levels. Fortunately, these needs have been recognized and to some extent quantified, and they are even now under further intensive study by some of the most competent members of society and the profession.

Jan 3, 1973

By Guy T. McBride

Mr. Chairman, Fellow Keynoters, Ladies, and Gentlemen: It is purposed to consider the theme of this meeting, "The 1970&apos;s - Pivotal Decade for the Mineral Industries," from the particular -- some would say peculiar -- point of view of one engaged in mineral engineering education, and this coign of vantage prompts the textbookish subtitle, "Problems and Solutions (?) in Undergraduate Mineral Engineering Education." Three interrelated problems, or problem areas, will be presented and discussed, and where solutions seem to be emerging or seem worthy to be suggested, they will be identified. The three problems are: 1. The goals, and therefore the course requirements, of the undergraduate curricula are in question, 2. The unit costs of undergraduate education appear excessive to those who bear the charges, and 3. The social ambience of the day affects for the worse the work attitudes and the career motivation of both prospective and in-course students. The Need. - Any discussion of these problems must bottom upon recognized national needs for minerals and a technologically sound minerals industry staffed by competent engineers, particularly at the exploration, development, and production levels, Fortunately, these needs have been recognized and to some extent quantified, and they are even now under further intensive study by some of the most competent members of our society and profession. The latter reference is, of course, to the current work of the National Commission on Materials Policy (U.S.A.) under the executive directorship of Dr. James Boyd. Predating this, and perhaps to some extent

Jan 1, 1972

By B. Goertz

Since the turn of the century the mining industry in the United States has had a number of serious mine explosions, fires and ground fall disasters that have led to a major re-evaluation of mine communication and rescue practices. One of the hindrances of current underground communication technologies is the potential of lost or cut connections when a serious accident, such as an explosion, fire, inundation or major ground fall, takes place. The Mine Improvement and New Emergency Response Act of 2006 (MINER Act)1 mandated that each underground coal mine in the U.S. must provide for two-way wireless, post-accident communications between underground and surface personnel as well as electronic tracking of underground workers One area that has gained renewed attention in the mining sector is Through-The-Earth (TTE) communication. TTE technology has a major advantage in that transceiver devices can be carried by miners and set up quickly during an emergency, since they require no wire connection to the surface. TTE technology uses ultra-low frequency (1 to 4 kHz) electromagnetic waves, requiring relatively large wire loop antennas and highly sensitive receivers. The signal bandwidth is narrow and the permissible antenna currents in coal mines are restricted, which has led to limited usability of TTE technology in the past, as evidenced in research studies conducted by the U.S. Bureau of Mines in the 1970s. Yenchek (2012)2 pointed out that recent advances in receiver and signal processing technology have enabled voice and text communication capabilities and much improved sensitivity that offers new possibilities for TTE communication in mining applications. One company that has been developing such technology is Vital Alert Communication Inc. Vital Alert has been providing TTE communications since 2003 with a growing focus on emergency response and portable systems. The company?s Canary® Go System is one such product that looks to provide reliable communication capabilities in a portable, user friendly unit that can be utilized both for normal operation and mine rescue scenarios. Researchers at the Colorado School of Mines (CSM) have tested the Canary Go TTE communications system in the CSM Edgar Experimental Mine to determine signal propagation distances, signal quality and aspects of practical application.

Feb 23, 2014