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By Yinan Zhang, Yi Luo

The widely used R70 method is modified to measure the self-heating propensity of low-rank coals. This modified R70 method enables the introduction of controlled amount of moist oxygen into the reaction vessel. Three coal lumps were collected from three different locations in a surface mine in the Powder River Basin. The coal samples were tested in oxygen flow with controlled moisture content under adiabatic condition. By measuring the relative humidity at the exhaust exit point of the testing setup, the flux and cumulative wetting heat that is consumed by coal samples can be determined. Through a better way of determining the coal’s specific heat, the total heat, including heat of wetting and coal’s oxidation heat, required to raise coal to a given temperature can be determined. Then, the contribution of heat of wetting at the different stages of the testing is quantified. The effects of evaporative heat through a group of tests have also been quantified. From this research, a better understanding of the effect of wetting heat on inducing low-rank coal’s spontaneous combustion can be acquired.

Nov 30, 2022

By D. G. Chedgy

Careful consideration is given to the type of cleaning equipment and control sys- teas to be used when selecting circuits for wash-ing fine coal (28M x 0 size fraction). However, the desliming, declaying and sizing procedures required to ensure efficient operation normally are not evaluated in sufficient detail resulting in disappointing system performance. This paper details desliming and dewatering circuit design which is extremely effective based on recent test data. The circuit maintains control of the 28M x 0 (declayed) size fraction with minimal misplaced material and maximized circuit efficiency. A discussion of circuit design parameters and control systems, as well as results from the testing program, are included in this text.

Jan 1, 1986

By Sam Rosenblum

The anomaly ratio is obtained by dividing the analyzed value of an element by the anomaly threshold value of the element. The sum of anomaly ratios for all anomalous elements in a sample may be compared with similar sums for other samples, so that the samples having the greatest anomaly-ratio totals can be recognized easily. In partial or full-suites-of-ore-elements the use of anomaly ratios is more meaningful than analyzed values because the ratios quickly indicate anomalous elements and call attention to samples and localities that should be investigated.

Jan 1, 1980

By M. T. Ityokumbul

The effect of reaction conditions on the desulphurization of oil sand coke residues has been studied. The variables investigated were temperature, reaction time, heat transfer resistance, and mode of caustic soda addition. The results obtained show that oil sand coke desulphurization increases with temperature, reaction time, and heat transfer rate. In an oxidative environment, coke combustion during molten caustic leaching (MCL) commences at temperatures above 500°C. The mode of caustic addition has no effect on coke desulphurization.

Jan 1, 1995

By J. Driscoll, T. Morson, Ross M. Workman

The study investigates the effectiveness of the canopy air curtain (CAC) in reducing respirable dust exposure for shuttle car and ramcar operators in underground coal mining. Field testing showed that the CAC reduced dust exposure by 11-34% overall and by 57-65% during ramcar loading by the continuous miner. These results demonstrate the CAC’s potential as a significant dust control device.

Feb 19, 2022

By Jan Luca Grunow, Ansgar Bendiek, Klaus Böde

According to the Markowitz portfolio theory the value of a diversified portfolio is higher than the sum of the parts of a portfolio, which is an important consideration for the correct valuation. This is valid for real estate portfolios as well as for mining assets (or enterprises). This paper analyses the application of the portfolio theory to a diversified portfolio of assets in the real estate industry and draws conclusions on further research work to be done in the minerals industry. The volume of real estate transactions is increasing over recent years. As such, the nature of those transactions is constantly changing and in some cases portfolios become more heterogeneous as they are composed of different property categories, e.g. locations and types of use. This makes their economic evaluation more difficult. This paper focuses on the acquisition of a fairly heterogeneous real estate property portfolio purchased by “Commerz Real” in Germany in Q4 2019. For economic evaluation the widely used Markowitz portfolio theory (Markowitz, 1952) was applied. It was investigated whether diversification effects could achieve added value in the form of a reduction in risk compared to the sum of their individual components. As a result the findings of this research could be applied to other heterogeneous real estate transactions and even to mine property portfolio or PPP1 project portfolio transactions.

Jun 25, 2023

By C. G. Tester

Automatic tripper control systems can be reliable and as such are suitable for use in the mining industry. Proper application of fundamental engineering principles provides the means for the reliability. Some of the principles are: (1) Be sure the system designer designs a system that does the job operations people want done; (2) Use sound logic design practices to avoid internal electrical problems; (3) The design must be maintenance oriented; and (4) Use good quality components. I would like to discuss a tripper control installation at Kennecott Copper Corporation, Chino Mines Division, in Hurley, New Mexico, and how these principles apply to this tripper control system. First, however, I will expand on the principles to clarify just what is meant. First, "Be sure the system designer designs a system that does the job operations people want done.? Operator acceptance is often the key to the success or failure of an automatic control system. One of the best ways I know of to get operator acceptance is to give him a system that he wants. I don't mean to imply that if bad practices or procedures exist that they should be incorporated in the control system. I do think that many designers feel they haven't done their job if the control system doesn't do things drastically different than the old manual method. Good engineering principles dictate that the job should be done right and if the manual method was right it can very likely be right for the automatic method.

Jan 1, 1973

By Ashish Ranjan Kumar, Barbara Arnold, Luis Sanchez Gonzalez

Mining operations adopt a variety of measures to combat dust underground. These include ventilation systems, water sprays, physical barriers, and personal protective equipment (PPE). Respirators are a class of PPE that can provide clean particulate- free air to the users. Powered Air-Purifying Respirators (PAPRs), used commonly in medical and other sectors, are not prevalent in the mining industry. PAPRs use P100 filters that have 99.97% dust capture efficiency. We present our results from computational fluid dynamics (CFD) simulations performed to understand the impact of a PAPR on airflow and dust particle concentration in the vicinity of a miner. These results show that donning PAPRs can lower the miners’ exposure to respirable coal dust in their workplace.

Feb 1, 2025

By Richard Giffen, Martha Gross, Luca Pellegrini, Pa Ousman Njie

The Hampton Roads Bridge-Tunnel (HRBT) Expansion project in Virginia includes parallel 1.5- mile (2.4 km) tunnels constructed using a tunnel boring machine (TBM). The TBM launching and receiving shafts were excavated within the footprint of two reclaimed islands abutting the navigation channel for the Port of Virginia. The shaft excavations—a circular tri-cell shaft at South Island, and a circular-rectangular twin-cell shaft at North Island—were supported by slurry walls up to 190 feet (58 meters) below the island surfaces. This paper describes specic design considerations for these shafts, as well as construction and uality-oversight aspects of their excavation and construction.

Jun 23, 2024

By S. J. Lefond

Most people, when Borates are mentioned, mentally visualize the famous twenty mule team (really eighteen mules and two horses), trudging across the Mojave Desert or "she burns green Rosie, we are rich." Actually, however, the first use of borax was prior to Babylonian times. Their emissaries had orders to bring borax Iron the Gobi desert for use as a flux by the Babylonian goldsmiths. The borate mineral imported for this is not known but probably was borax. The ancient Persians and Arabians knew about borax and the Arabic word "Baurach" appears in a two thousand year old manuscript. The Sanscrit word for borax was tincana which has been corrupted to tincal. The Chinese were using borax as a glaze in three-hundred B.C. Marco Polo brought the first borax, along with gunpowder and spaghetti, from Mongolia to Europe in the late 1300's. Borax from Tibet was imported to Europe for nearly 500 years. In 1772 boric acid (sassolite) was discovered around Tuscany, Italy as a precipitant from volcanic steam vents. Production of boric acid started there about 1815 and provided the sole competition to the borax from Tibet. Borate deposits in Turkey have been known and exploited on a small scale since the 13th century. It is only recently that the operations are being modernized and production increased. About 1836, borax minerals were found in Chile and Argentina with borax production starting in 1852 in Chile and in Argentina in 1886. During the latter half of the 19th Century, Chile was the principle world producer of borax.

Jan 1, 1980

By James W. Echerd

Anthracite preparation developments, particularly in the early days of the anthracite industry, formed the basis for the modern coal preparation plants that have become so essential to the coal industry today. The anthracite industry, from early in the 19th century until relatively recently, was a leader in mining, preparation and marketing of coal, and played a leading role in the development of the industrial America we know today. Anthracite was discovered in America in about 1760--the story of Necho Allen is well known--but the rediscoveries leading to mining operations took place about 50 years later. The Wurtz brothers in 1815 at Scranton, the Smith brothers at Wilkes-Barre in 1807, Beach in Hazleton in about 1814, and Boyd in 1816 at Shamokin were all instrumental in promoting early mining and marketing of anthracite (J3. The early canals and railroads were built for the specific purpose of moving anthracite to the market areas. Eventually, the industry grew until, in 1917, it reached a production zenith of a little over 100,000,000 tons, representing about 20 percent of the total coal output in the United States. Almost half of the anthracite produced that year was consumed for domestic heating, a utilization that had dominated the industry for almost 100 years. Initially, anthracite had to be used by gunsmiths and blacksmiths, after which had followed the consumption of extensive quantities for railroads, blast furnaces and foundries, and electric power generation. Most of the markets have been lost to coke, oil, and natural gas. Near the anthracite regions, however, significant quantities are still used for domestic heating, power generation, carbon black manufacture, blending with bituminous coal to make metallurgical coke and fuel, and for other industrial purposes. Thus, anthracite production has not been entirely committed to history, but remains an active industry that follows modern practices in the mining, preparation, shipping, and utilization of a fuel that is still a valuable adjunct to the national economy. In fact, its inherent low sulfur content may make it an important fuel of the future. Estimates indicate there are reserves of anthracite to last for 300 years at a consumption rate of 50,000,000 tons/year. Anthracite Preparation Yesterday A 170-year history of the anthracite industry obviously is not the purpose of this discussion. A complete history of anthracite preparation, the rather unglamorous step in the processing of "mine run" hard coal to make it suitable for the user, is also not practical. Hence, the purpose of this report is to trace the development of some of the most important processes used through the years to meet a part of the demand for energy developed by our modern society. Anthracite preparation in the early days of the industry consisted solely of separating slate from the coal, by hand, underground (Z). This method prevailed for almost 20 years until wrought iron hand rakes were introduced to separate the large and small sizes. Shortly thereafter, the first attempts were made to size and clean the coal aboveground. The coal was dumped on a perforated cast iron plate, and men used sledge hammers to break the larger pieces into smaller sizes suitable for the market. The smallest sizes--that is, the material that went through the plate--were thrown away because they had no value at that time--a concept that existed for many years and actually was the basis for the subsequent "river" coal production and the many silt banks which are landmarks in the anthracite region. The larger sizes, at that time, sold for 50 cents per ton. The Batten breaker, or roll crusher, was invented in 1844, followed soon thereafter by the Snell-Diehm breaker (A). The latter had disadvantages, including excessive waste and fixed product size, but it later was improved in these respects. A breaker was also developed at Minersville, Pa., at about the same time that processed 200 tons of coal per day, using roll crushers and circular screens (1). Handpicking, from the beginning of anthracite preparation, was an important part of the cleaning process and was still being practiced as late as 1950. It was this process that involved the "breaker" boys of coal region lore. How much good handpicking accomplished depended on how much impurity was present in the coal--the more the impurities, the greater the reduction in ash. Thus, high-impurity streams were significantly improved, whereas picking of relatively clean coal was mainly to show an effort to make a quality product. As indicated, picking is largely a visual operation. It was and is wasteful of coal in the larger sizes since some good coal is always associated with the bad. However, it was probably much more effective' in the larger than the smaller sizes.

Jan 1, 1971

By Hasan Nizamoğlu, Z. Abidin Sarı, Aslıhan Demiraslan, M. Deniz Turan, Tolga Depci

In this study, recovery of copper from solid material (obtained by leaching of chalcopyrite with oxalic acid in the presence of hydrogen peroxide) with a copper oxalate structure was carried out selectively using HCl. The chemical composition of the solid was as 29.3%, 9.7%, and 13.3% for Cu, Fe, and S, respectively. Selective recovery of copper by degrading the copper oxalate structure with a low-solubility product (Ksp = 4.43 × 10−10) was performed by conventional leaching in the presence of HCl. The optimum leaching conditions were determined as 5 M of HCl concentration, 318 K of leaching temperature, 120 min of leaching time, 25 ml/g of liquid–solid ratio and 400 rpm of stirring speed. Under these conditions, approximately 77% of copper and 3% of iron were taken into the solution. According to the characterization of the leach residue that was obtained, the oxalate structure was degraded. Moreover, the results of XRD analysis showed that the sulfur (S) and cubanite (CuFe2S3) phases were mostly observed in leaching residues, and this was supported by the SEM-EDX data. Based on the results, it may be stated that selective copper extraction can be obtained from a chalcopyrite concentrate by a two-step leaching method using a conventional hydrometallurgical technique.

By Matthew Burdick, Andrew Rule, Erica Bailey

The Second Narrows Water Supply Tunnel, Burrard Inlet Crossing project for the Greater Vancouver Water District entails deep shaft construction, subway sized pressurized face tunneling through highly variable ground conditions, installation of three permanent steel water mains and construction of elaborate valve chambers adjacent to either shaft. The paper discusses key elements of the planning and implementation of 6.69 m Ø slurry mixshield tunnel boring machine (TBM) assembly in a small diameter deep shaft including incorporation of a fully pressurized launch lock, preparations for saturation diving, surface support infrastructure and initial mining sequence.

Jun 13, 2021

Smart defense: that?s what the industry needs to play for the next four years, according to panelists at the 118th Annual Meeting of the Northwest Mining Association (NWMA), which met December 2-7 in Spokane, WA. The conference was well attended, with approximately 2,200 attendees, 244 booths in the two packed exhibition halls, and a rich offering of short courses, field trips, social events and technical sessions. Speakers at the packed legislative session articulated many of the frustrations felt by members of the mining community after the U.S. elections in November, and offered words of advice. Matthew Ellsworth, the new Government Affairs hire at NWMA, stated it best: ?Elections are like Christmas: you find out who?s naughty and nice ? and it?s always going to come again.?

Jan 1, 2013

By David B. Gladwin

Regional characteristics in the coal resource base have resulted in application of different mining methods across Canada. Longwall methods predominate in eastern Canada, whereas open pit, hydraulic and room-and-pillar methods are utilized in the west. Both provincial and federal agencies have regulatory responsibilities and both also share in the development of R&D programs. This paper outlines the scale and scope of the various agencies involved with health and safety R&D in our expanding coal mining industry. Specific R&D activities in ventilation, dust control, explosion hazards, tunnel boring, strata control and truck braking, which form part of the national program, are outlined.

Jan 1, 1982

By T. W. Martin

The use of conveyors in large, open pit mines and their drawbacks are discussed. Technological developments such as long distance conveyors capable of handling large rocks are explored. The development and testing by the Bureau of Mines of a prototype crib and cable conveyor for handling large rocks are discussed, and possible modifications of the concept for a production model are examined.

Jan 1, 1984

By A. I. Johnson

This paper describes," the application, of a modular or building block approach to the analysis, design, and control of complex mineral treating processes. The main purpose of the paper is tutorial, to show the reader how such processes can be modeled using a modern digital computer" and, not to discuss in any detail the results that may be achieved in such studies. It is proposed that, the main techniques be illustrated by reference mainly to the Bayer process for alumina extraction and purification; in cooperation with the Aluminum Company of Canada Ltd. the author and his Colleagues at McMaster University and their students have studied this, process as a means of applying new computer techniques to extractive metallurgical processes. The plant described was studied by the author and his colleagues as a senior undergraduate project in cooperation with the Aluminum Company of Canada. It is one of several studies that have been carried out with Canadian industry. (1)

Jan 1, 1972

By O. A. Bascur

Current competitive demands on the process industries stimulate the need for improved operating efficiencies and compliance to stricter governmental regulations. Emerging information technologies allow narrowing the gap between management business objectives and the process control level. Benefits come from enhanced energy management, operating costs reduction, enhanced scheduling of activities, reduced quality giveaway, enhanced market driven production and enhanced decision making. Plant management systems integrate economic performance monitoring by controlling the business rather than just throughput and product quality. Sound business based decisions about how to operate the plant can be achieved by adequate dynamic performance monitoring at the plant level and the enforcement of the desired targets at the process control level. This paper describes some of the key requirements to implement a process management system to meet stricter process performance standards. Extensions are made to facilitate conforming with regulations established by various governmental and industry monitoring agencies.

Jan 1, 1993

By Richard Emberley, Timothy Shaw, José L. Torero, Jurij Karlovsek, Timothy Gibson

"Tunnel closures are highly undesirable and the lengthiest are generally attributed to structural failures (e.g. Mont Blanc). Although historical data shows structural failures are closely linked to fire, design parameters for tunnel safety are not well defined. Current research has focused on defining the fire heat release rate and temperature, but these parameters cannot be easily used to determined structural performance. The energy transferred to the structure, the heat flux, is required but current literature lacks these values. Full scale experiments were undertaken on passenger vehicles resulting in heat fluxes between 20-70kW/m2. Analysis shows a vehicle fire’s duration is closely linked to its mass. Further analysis shows small vehicle fires can be scaled as a function of the tunnel diameter and the characteristic height of the desired vehicle. The present work provides engineers an appropriate design methodology to undertake informed thermal-structural analysis to minimize the risk of tunnel structural failure.INTRODUCTION Quantifying the effects of a tunnel fire depends on many factors such as the type of occupants, their vehicles and spacing, ventilation conditions and the geometric shape of the tunnel (Ingason and Lonnermark 2011). For design engineers investigating the thermal-structural performance of a tunnel, these factors are typically converted into spatial and temporal temperature distributions (Usmani et al. 2001) using various design curves such as those of ISO834-1, Hydrocarbon, Rijkswaterstaat (RWS) or RABT-ZTV (Promat 2013). However, to define a temperature profile through a structural element these curves require a heat transfer model that incorporates an appropriate boundary condition. The appropriate boundary condition is the net heat flux which is the result of a complex energy balance. For use in heat transfer calculations the net heat flux must account for the tunnel geometry as well as thermal properties of a given structural element and all other surfaces and mediums affecting the transfer of heat (Torero 2014)."

Jan 1, 2016

By Christopher R. Winter

Mining companies have sharpened their refocus on their tailings management strategies in recent years. Mining companies with tailings storage facilities that use the upstream construction method have been challenged to track the evolution of industry standards, assess risks, revise design, and communicate design revisions with regulators. While many aspects of best practices and industry standards have evolved in recent years as an attribute of continual improvement, the controlling standard in the design of many upstream dams is understanding the foundational strengths of hydraulically deposited tailings. Following best practices and industry standards, Hibbing Taconite Company managed by Cleveland-Cliffs, began the re-evaluation of foundation strengths underlying a system of upstream dams at the company’s iron ore mine tailings storage facility in northern Minnesota. Initial steps in the re-evaluation require reanalysis of design parameters and recommendations by the Engineer of Record to the Owner, which was followed by a series of meetings with the Technical Review Board to determine an initial path forward. Once a path forward and preliminary design parameters were determined, the Owner engaged with the State Dam Safety Engineer to discuss and seek approval of the plan. With continuous regulatory engagement throughout the process, further refinement of the design parameters for the hydraulically-placed tailings foundations underlying upstream dams began with field and lab geotechnical investigations. Following a review of risk assessments and trigger actions response plans, Hibbing Taconite revised its tailings storage facility operating plans and budget for the coming years. Based on the findings of the re-evaluation, reanalysis, and refinement of parameters, a paradigm shift was realized with the hydraulically placed tailings foundation strengths underlying the upstream system of dams. This paper explores the path that the Hibbing Taconite Company followed to understand the paradigm shift and construct downstream improvements. The plan involved tailings re-characterization, dam design revisions, operating plan reconciliation, budget revisions, wetland permitting, dam safety permit amendments, storm water prevention plans, borrow materials studies, new concrete decant structures and the pursuit to recognize and be consistent with industry standards.

Feb 1, 2024