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By Zengwu Zhao, Peng Xu, Jieliang Wang, Qingwei Bai, Xinyang Liu, Xiao Lei

The paper investigates the capture and recovery of rare earth minerals from Bayan Obo ore using superconducting magnetic separation. A finite element model (FEM) was established to study the influence of various factors on the capture of rare earth minerals under a high-gradient superconducting magnetic field. The study aims to improve the efficiency of rare earth mineral separation and recovery.

Oct 1, 2023

By C. Clark, R. Pakalnis, B. Seymour, L. Martin, M. Stepan, M. Roworth, C. Caceres

The National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health, Ground Control Engineering Branch is investigating the use of shotcrete in weak rock mass mines with the objective of reducing fatalities and injuries resulting from rock fall accidents. When shotcrete is used as part of a multielement ground support system, there is a need to know the support characteristics that the shotcrete contributes to the overall system. To quantify the support provided by the shotcrete, flexural strength tests were conducted with two common, commercially available fiber-reinforced shotcrete (FRS) mixes using the round determinant panel (RDP) test method, ASTM C 1550. A portable RDP test machine developed by NIOSH researchers was used to determine the peak flexural load and residual load capacity for a steel FRS and a synthetic poly FRS that were sprayed using dry mix procedures and equipment. Besides the flexural strength and loading behavior determined from these tests, a method was also developed for measuring the width of cracks exposed on the underside of a shotcrete panel during a RDP test and relating these measurements to residual load values. Quantifying the peak flexural load and residual loads of a shotcrete mix through on site testing at a mine and visually assessing the loading cycle and load-carrying capability of the shotcrete applied to underground workings will improve mine safety by providing a better assessment of the stability of shotcrete supported entries.

Jan 1, 2010

By Yuting Xue, Lihong Zhou, DAVOOD BAHRAMI

The paper discusses the use of machine learning (ML) to develop a predictive model for determining the location and size of underground mine fires using simulated ventilation data. The study highlights the importance of prompt fire location determination for effective firefighting strategies and reducing injury risks. The ML model was trained with simulated data and achieved an accuracy score of 0.920, which improved to 0.962 by grouping closely connected airways.

Sep 1, 2023

By S. D. F. Rocha, A. L. A. SANTOS, E. M. A. BECHELENI, F. P. C. Silvas

Hydrometallurgical processes are needed to extract nickel (Ni) when it is disseminated in mineral matrix. High-pressure acid leaching (HPAL) and atmospheric acid leaching (AAL) are alternatives, and AAL has the advantage of requiring mild temperatures and pressure. Reducing-reagent tests improved the extraction of metals for the specific limiting portion of the ore. Low dosage of sodium thiosulfate presented better selectivity and safer operating conditions, allowing metal extractions of 50–62 percent at 95 °C. However, the low extraction rate obtained for Ni and the similar levels of impurities — magnesium (Mg), manganese (Mn), cobalt (Co) and iron (Fe) — extracted may represent economical and technological challenges in the downstream process.

By J. E. Dreier, R. E. Scheffel, A. Guzman

"This paper outlines a comprehensive, cost-effective testing program for the acid-ferric sulfate heap leaching of oxide, supergene and primary copper ores. It is based on extensive experience in copper heap leaching and uses the many technological advances in the field developed over the past several decades. The approach described requires firstly a detailed resource evaluation, then a hydrodynamic characterization of representative samples and, finally, a focused metallurgical testing program. The principles communicated here can be applied to other acid leachable minerals. The program varies considerably from conventional testing in its disciplined, orderly, step-by-step approach, its application of hydrological and chemical principles to leaching, and its reliance on fewer, more tightly controlled column tests. The purpose of the test program is to optimize the financial, time and other resources devoted to the program, while minimizing the financial risks to the development company or companies and the project funding providers. IntroductionThe major goal of any process development testing program should be the successful implementation of the project. With respect to heap leaching, the metallurgical testing program plays a critical role in the larger objective, as described in Scheffel (2013, 2014). McNulty’s series of papers (1998, 2004, 2014) confirm that the success of any project is directly proportional to the extent and quality of the testing program on which the process is designed.Therefore, a key development objective is to conduct a well-focused metallurgical test program. While the primary focus of this paper is copper, the acid leaching of any substance would benefit from a similar approach.This paper addresses primarily the sulfate system, which is compatible with the bioleaching of sulfide minerals. Nicol et al. (2011) described the advantages of the chloride leaching of copper sulfide minerals. United States patents Nos. US 2009/0173188 A1, US 8,597,933 B2 and US2015/0232963 A1, assigned to BHP Chile Inc. and BHP Billiton S.A. Ltd, describe methods for both the oxidative and nonoxidative leaching of primary and secondary copper sulfides. Reyes (2013) and Ipinza and Flaquer (2014) described commercial applications of chloride-based heap leaching. The testing disciplines discussed in this paper will also apply to the development of an acidic chloride leaching system."

Jan 1, 2016

By Lawrence A. Browning

In recent years, there has been a growing realization of the importance of ground water as a national resource and increasing concern that this resource be properly managed and protected from a variety of pervasive practices that endanger it. Aquifers have been adversely affected in every region of the country. In dealing w.ith the underground water program, EPA will have the following objectives: to protect human health, and to protect and conserve an important national resource. In pursuing these objectives, EPA will take economic consequences and other national objectives (e.g., energy) into account. EPA intends to pursue these objectives in full partnership with the States. Generally the States should retain the lead in protecting ground water.

Jan 1, 1978

By H. O. Harju

In July 1968, P.T. Inco Indonesia was granted a Contract of Work to explore and develop the nickel laterite resources on the southeastern peninsula of the island of Sulawesi. Since 1970, exploration has centred on the deposits at Soroako as the site for initial project development. This paper describes the exploration methods used to evaluate these rather unique laterite deposits, the geology of which is described in the first section of this volume.

Jan 1, 1979

By Raj K. Rajamani, Samira Rashidi

High pressure grinding rolls have been utilized in various operations during the past four decades, simply due to their inherent mode of breakage that offers metallurgical benefits with pronounced energy reduction. For every new application, wear and in particular roll surface wear protection has always been the focal point of HPGR trade-off studies. Wear remains an important issue throughout a mine’s life given inevitable variations in the ore deposits properties. Hence, the capability of continuous scanning of rolls provides ample information about any deviations in the design values as well as their effect on the wear pattern. In part I of this manuscript, we present the feasibility of in-line scanning of roll surface in a 200 × 100 mm lab-scale HPGR. First, the in-line scanning was developed in a mock-up roll and then the scanner was moved to the laboratory-scale HPGR. We present the choice of scanners and the methods adopted to achieve high-level accuracy of determining wear. Even though we planned for micron-level precision of scanning, the inherent variability in shaft rotation was higher than the variability in the roll diameter due to wear. The hundred-kilogram mass processed in the HPGR was not sufficient to create enough wear that is discernible to the in-line scanner. Yet, the method tested is a promising avenue for inline scanning of HPGR rolls.

By Desiree Willis

At 6 percent downgrade to a low point beneath California?s Sacramento River, the Lower Northwest Interceptor Sewer was a difficult project from the outset. Project owner Sacramento County Regional Sanitation District (SRC-SD) planned to excavate the V-shaped tunnel in two sections using an earth pressure balance (EPB) machine in soft ground. Muck removal, due to the steep downgrade, was a tricky proposition. ?We did look at muck cars, but determined they were not the best option due to the relatively steep slope of the tunnel alignment. The safety benefits of conveyors on this job were obvious, as there were not the potential hazards associated with muck cars traveling on an incline or derailing,? said Steve Norris, senior civil engineer for SRCSD The successful project represented one of the first instances of a conveyor system being used for a soft ground tunnel boring machine (TBM) application. Several projects in California, including a recent tunnel completed in 2009, have highlighted a growing acceptance of conveyor muck removal in a variety of ground conditions. Conveyors offer higher system availability than more common methods, such as muck cars, as they allow for continual operation of the TBM. The design of conveyor systems must, however, take into account the differences in material between soft ground and hard rock, including belt cleaning features, sealed transfer points and other elements.

Jun 1, 2010

By Foreback T. G.

The McKinley Mine is a large strip operation sup-plying coal to several utility and industrial customers. The mine reserve comprises many coal seams of varying quality and thickness. Erosion of the terrain has created coal out-crop lines that are encountered frequently with associated deviations in quality. Due to the complex nature of the coal reserve and the various customer quality requirements, coal quality control is a primary consideration and a constant challenge at the McKinley Mine. This paper will discuss the practices employed to ensure that the available coal meets contract specifications.

Jan 1, 1994

By John W. Stevenson

At the No. 4 Mine of Jim Walter Resources in Tuscaloosa County in the North Central part of the State of Alabama, the Mary Lee and Blue Creek coal beds lay 2000 feet below the surface. The quantity of methane gas stored within the coal bed reservoir at this depth and released during development mining necessitates that each coal producing section be ventilated using large air quantities approaching 100,000 cfm. In order to meet coal contractural commitments in the early stages of mine development by installing the necessary number of continuous mining machine units and to develop the mine to projected air shaft sites, high pressure, large volume mine ventilating fans were required. This presentation discusses the installation start-up and changeover procedures when two size GAF 31.5-28-1 TLT-Babcock 3500 Horsepower fans with adjustable pitch in flight blades were put on line while phasing out two Jeffrey Mining Machine Company 8HUA 117 Fans. A graph will be presented to depict the most economic diameter shaft size under 2000 feet of cover with different air quantity requirements.

Jan 1, 1982

By H. F. Ghezzi

The indirect method of drying coal fines is applied to filter cakes which ordinarily contain 22 to 30% moisture and are not readily transportable. The "Thermal Dryer", which operates on the mass transfer principle, has found wide use in coal preparation plants. The thermal dryer is penalized in operation by the necessity of adding coarse coal to the wet fines before entering the dryer body in order to produce a permeable bed, and thus enable hot gases to uniformly contact the wet mass. The ratio of coarse coal to fines varies from 2:1 to as much as 4:1, depending on the average particle size, moisture, and ash content of the fines.

Jan 1, 1985

By Kirk Carlton

The Athabasca tar sands of Alberta are an increasingly important source of crude oil for the North American continent. Published figures indicate estimates of recoverable resources in the tar sands at some 300 billion barrels of synthetic crude of which some 86 billion barrels can be recovered by surface mining techniques. At the present time, two commercial plants are in operation, Great Canadian Oil Sands Limited and Syncrude Canada Ltd. Their present combined capacity is approximately 150,000 barrels per day. Some of the factors which will make this oil expensive will be noted here. The location of the present producing plants is 500 kilometres north of Edmonton at an elevation of approximately 320 metres. Recorded temperatures range from +38 to -55 degrees Celsius. Wind velocities are not high but the chill factor with even a slight breeze and minus 40 degrees is very uncomfortable.

Jan 1, 1979

By D. W. Mitchell

Planning today for what hopefully will never happen is one of the surest ways to decrease the chance of it happening. As Napoleon proved and Ian Mitroff wrote, "The heat and stress of battle is the worst time to make decisions of strategic importance." Mitroff also wrote, "The value of a plan is not that it will ever perfectly match reality, but going through the process of planning speeds the process of recovery. It allows the organization to emotionally work through the worst before it actually happens." This paper concentrates on things miners must consider; on the need for plans to be like a belt conveyor strong enough to carry the load, flexible enough to stretch a little; on the criticality of throwing away fax machines and telephones, and having certain officials at the scene rather than back in head-quarters; on the training of fire brigades and mine-rescue teams; on having company-controlled chromatographs; on having people who can look at trends rather than numbers. Some of the things in this paper might anger some readers; for that, I can only ask them to consider first the problem not their position.

Jan 1, 1993

By Ralph T. Buscarello

For practical purposes, the terms "natural frequency," "resonance" and "critical speed" are synonymous. A part passing though its "critical" or "critical speed" may also be said to be "resonant" or "resonating." The vibrations of a precisely balanced part can be magnified by the structure in which it is assembled. Anyone who has driven an automobile knows that it will vibrate more at a certain speed than at others. According to the formula for centrifugal force, vibration should increase steadily with a rise in rpm. What happens instead is that the vibration not only in- creases with r m. but suddenly rises at a much higher rate through the critical speed, and then apparently smooths out as the rpm passes beyond it. To visualize what happens, consider a simple flat spring with a weight mounted at one end. When the spring is deflected by pulling down on the weight and then letting it go, the spring will oscillate, and the spring-and-weight system will vibrate at its natural frequency. If the timing or direction bf the impulses imparted to the spring did not coincide with its natural frequency, the result would be an irregular vibration that would not build up. If, on the other hand, the timing and direction of the impulses did coincide with the spring's natural frequency, the result would be a larger and larger amplitude. If the impulses were continued indefinitely, the amplitude of the spring's vibrations would go on rising [while its frequency stayed the same] until the spring broke or the amplitude of the vibrations reached an equilibrium [because frictional or other forces would tend to damp it]. Resonance magnifies the amplitude of vibrations in a relatively undamped system between 100 to 200 times over that of nonresonant vibrations. Frictional or viscous damping often reduces the magnification [from 10 to 20 times], but even with this reduction the amplitude would still be large enough to cause excessive wear, and sometimes even fractures. For example, a blower might show only 0.001 in. of vibration on the manufacturer's test stand. Installed, the blower could pass into its critical speed [the speed at which the frequency of the vibrations caused by the rotor coincides with the supporting structure's natural frequency], and the 0.001 in. of vibration could be resonated to 0.010 in., or as much as 0.020 in. The cure for such a condition would not be to lower the vibration of the blower by further balancing or better alignment but to separate the two frequencies by at least 20 to 30%.

Jan 1, 1970

By James A. L. White

Although the quantity of native sulphur associated with volcanism is large, production from such deposits represents only a very small percentage of total world production, This paper describes the location of the known deposits, the typical geology of these deposits and the nature of the sulphur mineralization. Methods of treatment are discussed and some comments are offered on the economic position of these occurences in world sulphur markets.

Jan 1, 1967

By Lauren M. Roberts, Ralph R. Sacrison

Pipeline or borehole free-fall transfer of material has long been done in support of underground mining. This paper addresses some characteristics and design elements in selecting systems suitable to the transferred media and the mine requirements. Though aspects of overall systems are discussed, principal attention is directed to the slickline/dropline/transfer line and the discharge diverter/rockbox/energy dissipator/boot. These terms are common to these systems, often used interchangeably, and will be used as appropriate to the material, equipment and construction. Following several design sections, fabrication and construction, and system operating and maintenance procedures are discussed.

Feb 1, 2025

By John P. Hunt

Early disseminated copper mineralization at Quebrada Blanca, Chile, accompanied 38 million year old quartz monzonite stocks and dikes. Early mineralization was followed by hydrothermal mineralization, mineralized breccias, and post-mineral faulting. After supergene leaching and enrichment, Quebrada Blanca was buried under late Tertiary gravels, and then partially re- exposed in Quaternary time. Based on work to date the orebody appears to contain more than one hundred million tons of plus one percent secondarily enriched copper ore, overlying several hundred million tons of protore averaging more than 0.5% copper. A source of industrial water appears to have been located. Pilot scale metallurgical tests, mine planning, and feasibility studies are in progress.

Jan 1, 1981

By R. E. J. Putman

Rising demand, artificial market conditions, increased overseas competition, and a fluctuating international situation have brought ever increasing pressures to bear on the nonferrous metals industries, and particularly in the United States, Although capacity is being expanded by the construction of new plants and the development of new ore deposits, increasing attention is being focused on the possibilities of improving the performance of the existing installations and of getting the most out of the new equipment now installed. At first sight the task appears formidable. Based on raw materials which are nonhomogeneous, and possessing characteristics which are hard to quantify, even the processes by which the values in the ores are concentrated and extracted are in many cases not fully understood. The necessary analytical equipment and transducers demanded by these industries have also been slow in development and their earlier absence has hampered the application of modern control technology, This is reflected in plants which have been designed for ease of manual rather than automatic control, and in which the application of control techniques at first sight appears economically prohibitive. However, in any industry progress often comes only in small steps, It may be that by the wise choice of limited objectives and perhaps only partial solutions, substantial improvements in plant performance can be implemented now, and with only a modest investment. If modern control equipment is chosen of the type which can be reprogrammed, advantage can be taken later of more sophisticated solutions as the technology of the industry advances. This task of improving plant performance can and must be commenced even though our knowledge is incomplete. The experience of a related mineral consuming industry, with similar problems in the past, can be encouraging.

Jan 1, 1967

By Edward R. Mueller

As an alternative to a million dollar, sensor based, computer dispatching system, Cyprus Pima Mining Company has installed a home¬made analog computer. The device is used in conjunction with a standard radio-dispatching system; it is inexpensive and very simple to build and operate. It enables the dispatcher to make near opti¬mum dispatching decisions and to identify all off schedule haulage trucks. Since installation, Cyprus Pima has experienced significant increases in pit productivity.

Jan 1, 1977