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By G. ALBORNOZ, S. Utili, A. AGOSTI, C. VALDERRAMA, R. PELL

The steepness of an openpit mine’s slopes has a substantial influence on the mine’s financial return. This paper proposes a novel design methodology where overall steeper pitwalls are employed without compromising the safety of the mine. In current design practice, pitwall profiles are often planar in cross section within each rock layer: that is, the profile inclination across each layer tends to be constant. Here, instead, a new geotechnical software, OptimalSlope, is used to determine optimal pitwall profiles of depth-varying inclination. OptimalSlope seeks the solution of a mathematical optimization problem where the overall steepness of the pitwall, from crest to toe, is maximized for an assigned lithology, geotechnical properties and factor of safety (FoS).

By Victoria Vaccarezza, Corby Anderson

The demand for rare earth elements for everyday technology and applications has initiated much research into the extraction and recovery of these rare earth elements. An otherwise unknown group of minerals, eudialyte is a zircon silicate consisting of rare earth oxides (REO), contained in a unique mineral structure and represented by a complex chemical formula. Research into extraction and recovery of rare earth elements involves various beneficiation and hydrometallurgical techniques. The goal of beneficiation being to efficiently liberate and upgrade the REO content, followed by hydrometallurgy to extract the desired elements. This overview will discuss previous research on treating eudialyte group minerals via different mineral processing and extraction techniques.

By R. Guardia, J. Hoskins, E. Claros, Y. Kamiya, R. Ramirez, J. Dalenz, P. Fernandez, E. Ilgren

Crocidolite is a well known causative agent for mesothelioma. Studies have shown that the pathogenicity of the fiber from different mines varies considerably and it has been postulated the parameter that appears most likely to account for this variation is fiber width. Epidemiological studies have shown that ‘thin’ fibers from mining areas of Western Australia and the Cape Province, in South Africa are associated with a high mesothelioma risk while exposure to ‘thick’ asbestiform amphibole fiber of the same fiber type are associated with little or no mesothelioma risk. This study is concerned with ‘thick’ Bolivian crocidolite but similar findings also probably explain the paucity of mesotheliomas in the Finnish anthophyllite, South African amosite and African Transvaal crocidolite mines. The findings from the present study suggest the incidence of mesothelioma in the three major cities of Bolivia is not significantly elevated above background even though Bolivian crocidolite has been used for the past 60 years commercially and residentially in all three cities. Although some cases of mesothelioma may have been missed due to a failure to reach hospital or a shortened natural lifespan, mesothelioma generally occurs after the age of 50, we cannot tell precisely the extent to which these were confounding. We suggest the most likely explanation for the lack of mesotheliomas despite the large populations at risk from the long and extensive residential and commercial use of crocidolite containing products, is related to an increased fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By Karl J. Benecke

Though the first patent on a bucket wheel excavator was granted in 1881 in the U.S. this technology was developed in Germany to the high standards of today. However, this development was only possible in parallel with the development of shiftable belt conveyors and boom stackers. The combination of these three types of equipment in the open pits of the Federal Republic of Germany has made lignite the cheapest energy source for power generating, despite the low heating value of German lignite in the order of 8500 kJ/kg (3600 BTU/lb) only. Comparing the costs for fuels used in power generating on the basis of their heating value, the relation between lignite, high quality black coal, and imported crude oil is in the order of 1 to 1.5 to 2.5, hence highly in favour of lignite. These cost advantages for lignite in Germany are due mainly to the concentration of lignite mining in a few high-output open pit mines. The largest one, Fortuna Mine in the Cologne district, produced a, total of 45 000 000 t lignite in 1976. That equals the annual fuel need of a 5750 MW power plant running 7000 hours per year at full capacity. Altogether 95 200 000 bank m3 equal to 200 000 000 t overburden had to be removed to accomplish this lignite output. The largest BWE (Fig. 1) ever built is working in the Fortuna Mine, too. At a digging height of 51 m above crawler level, the total vertical reach in relation to the face conveyor level is 98 m by means of its conveying bridge and loading unit. The hourly output is 10 400 bank m3. Its weight in operation is 13 000 t, its wheel diameter 21.6 m, as high as a 7-storey building.

Jan 1, 1977

By Martin P. Schroeder

"Challenges have emerged as subway systems age and as new tunnels are bored in congested corridors or in high-risk environments. To help public transportation agencies address tunneling challenges, the American Public Transportation Association has convened numerous independent industry peer reviews composed of top experts in their fields to come together and provide recommendations and solutions. This paper provides case histories of peer reviews that include topics such as boring through toxic soils, boring underneath existing tunnels, retrofit of tunnel ventilation systems, and mitigation of water intrusion. Peer reviews are applicable to all tunnel projects worldwide. The paper will highlight the conditions of these challenges, peer review recommendations, steps taken to reach agreement, and the successes that resulted, which led to major changes, new legislation and reduction of risk. INTRODUCTION Public transit agencies face many challenges in maintaining and expanding safe transit operations, especially as systems age, ridership expands, and budgets remain flat. The development of new industry standards and federal safety regulations places further demands on transit systems, with compliance often taxing in-house resources. Studies of the state-of-good-repair across US public transit systems indicate a current backlog of $84 billion in maintenance projects, which will require an investment of $18.2 billion per year to eliminate the backlog by 2030[1]. Systems not in a state-of-good-repair may not operate efficiently, may not be available to meet the growing ridership demands, and may not meet required safety goals or reduction of risk. Innovation is another clear need transit agencies have for improving system performance and lowering operating costs.To meet these challenges, transit agencies often turn to industry peer reviews for guidance and recommendations as part of their overall strategy to maintain and grow the safe operation of their systems. As a service to its members, the American Public Transportation System (APTA) has developed an industry peer review program designed to give agencies opportunities to learn from each other and help them address challenges in operations, engineering design, and construction of their systems. Over the past 20 years, APTA has performed hundreds of peer reviews covering all aspects of transit system operations from fare collection to agency organization, project delivery methods to safety culture, and engineering design including tunneling and tunnel fire ventilation. As rail transit systems expand to meet increased ridership, it is often necessary to bore new tunnels for alignments in congested areas where surface rights-of-way are lacking. Such proposed alignments can pose significant challenges for transit agencies, as they contend with various tunneling problems."

Jan 1, 2016

By J. C. Cawley

Improvements in today's maintenance practices are mandatory as more complex and productive machines evolve in the mining industry. By keeping machine reliability high, through improved maintenance procedures, overall mining costs can be reduced. The Bureau of Mines is investigating diagnostic maintenance systems for underground mining machinery. A hydraulic expert diagnostic system and an electric motor predictive diagnostic system have been designed and installed on a Joy 16CM continuous miner. An electrical diagnostic system has been designed and installed on a Joy 14CM continuous miner. Each system is functionally described and the relative merits of expert diagnostic systems versus algorithmic diagnostic systems are discussed.

Jan 1, 1991

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

One way to upgrade iron ore is to process it into pellets. The pelletizing process is multifaceted, involving complex fluid dynamics with highly turbulent, high-temperature flow in intricate geometries. This makes it hard to perform measurements during operation, so a useful tool for better process understanding is computational fluid dynamics (CFD), where the challenge is to perform efficient and trustful simulations of complicated problems. A validated simulation model can be valuable for increased process control and development. In this paper, the flow field and coal combustion process in a pilot-scale iron-ore pelletizing kiln is simulated using a CFD model. The objective of this work is to apply a coal combustion model to enable an investigation of thermal effects from the flame on the surrounding flow field.

By L. J. Tucker

The magnetite orebody at Pea Ridge strikes NE-SH and dips at about 800 to the SE. The ore is high grade magnetite with a strike length of over 600-m and a maximum width of over 180-m on some of the levels. The shape and the mineral content of the iron orebody have been fairly consistent so far. The iron ore and surrounding basement rocks are Precambrian in age. These rocks are usually very competent, about 400-m of sediments lie over the ore.

Jan 1, 1991

By Paweł Stefaniak, Natalia Duda-Mróz, Sergii Anufriiev, Wioletta Koperska

Due to the high environmental risks and negative impact of a failure, tailings storage facilities (TSFs) need constant monitoring. Advanced mathematical models have been developed in the past to predict the behavior of TSFs and raise alerts if needed. To be precise and reliable, such models need a spatial distribution of soil types within the dam as an input. Getting this data from laboratory measurements is time and costconsuming. In this article, we propose an ANN-powered algorithm, which allows us to accurately estimate the soil distribution based on a cone penetration test (CPT).

Jun 25, 2023

By B. J. Arnold

Over 600 million tons of coal are handled annually for use by the country's coal-fired power plants. Coal is transported in various ways. overland conveyors. Railcars, trucks, and barges. It can travel short distances or thousands of miles, picking up moisture, freezing, or drying. When the coal is received at the power plant, environmental problems with fugitive dust and further handling problems can arise.

Jan 1, 1989

The past four years since the 2008 MINExpo have been a roller coaster ride for the mining industry, with highs and lows and everything in between. One of the natural consequences of this uncertainty has been a number of significant consolidations and mergers, and this trend has trickled down into the crushing industry. And while there have been some significant changes to this sector of the mining industry, many of the big players have weathered the storm. The following is a look at some of the mineral processing companies that will be at MINExpo. McLanahan Corp. McLanahan Corp. is an example of the changes in the sector. The crushing and grinding stalwart acquired Universal Engineering, expanding its traditional focus on soft mineral crushing to hard rock crushing. At MINExpo, it will be showing off three new pieces of equipment, the LabMill Crusher, the Rocker Tooth Crusher and the Recessed Filter Press.

Jan 1, 2012

By J. C. Haptonstall

Stoping methods at the Homestake Gold Mine through 1978 had been traditional overhand cut-and-fill, shrinkage or square set. High costs, low-productivity and safety concerns prompted the mine to search for and adopt a "bulk mining" technique as a primary stoping method. Blasthole stoping had been successful but it is very development intensive, and was not suitable for the mine's accelerated mining program. Vertical Crater Retreat stoping was selected, and today accounts for over 50% of ore production. Case histories representing both the successes and failures of VCR stoping in the mine are discussed.

Jan 1, 1986

By Richard A. Thomas, Liming Yuan, Lihong Zhou, James H. Rowland

Hydrogen (H2) gas released during battery charging can result in cross-interference for carbon monoxide (CO) sensors used for early fire detection and compromise the integrity of the mine atmospheric monitoring system (AMS). In this study, a series of laboratory-scale and full-scale experiments were conducted to evaluate the responses of different CO sensors to H2 gas. In the laboratory-scale experiments, constant H2 concentrations in the airflow, from 100 to 500 ppm, pass through sensors. While in the full-scale experiments, increasing H2 concentrations generated as a byproduct from charging the batteries at the battery charging station rise to the sensors under different ventilation scenarios. The H2 concentrations at the CO sensor location were measured using H2 sensors and were correlated with the CO sensor response. The effects of ventilation and sensor location on the CO sensors responses were also analyzed. The results of this study can help mining companies to select appropriate CO sensors and improve the deployment of these sensors to ensure the safeguard of underground miners.

By Donald R. Simon

Money... not many subjects are as personal or as emotional. Hessiod said it well in 700 B.C. "Money is life to us wretched mortals". Are you getting paid enough? Does your company reward its top people? Does coal or copper pay more? Production or engineering? How is the synfuels industry going to influence mining salaries? Do high salaries attract and retain the best people? Do modern compensation systems ensure fairness or destroy entrepreneurial spirit? With our tax system and high standard of living why are we so salary conscious? Salary is not only important for what it can purchase but it is also a yardstick, measuring how well we are doing. We all need money to pay the bills and maintain our standard-of-living, but once we reach a certain point the psychological ramifications become more important than the purely practical side. Even necessary payments like the mortgage and the car are a function of our egos. Are our choices of cars and homes based on simple transportation and shelter?

Jan 1, 1980

By Silas Li, Michael Harris-Gifford, Jason Choi, William H. Hansmire

Twin-bore tunnels with a single track in each tunnel are currently the most common subway tunnel configuration. However, a large diameter single-bore tunnel with two tracks separated by a center wall could replace twin-bore tunnels and introduce potential benefits but require necessary modifications to the subway system. In particular, a nominal 40-foot-diameter single-bore tunnel can be considered in lieu of nominal 20-foot-diameter twin-bore tunnels. This paper discusses the benefits and modifications introduced by replacing twin-bore tunnels with a single-bore tunnel, with respect to various elements of the subway related to the tunnel, stations, track, and tunnel systems.

Dec 1, 2022

By A. Bascetin

Materials produced in quarries have been used for different intentions such as concrete and cement raw material, asphalt and embankment aggregates, railway ballast. Especially in cement manufacturing, the chemical composition and the uniformity of the raw materials play a strategic role in the economy and quality of the cement process. Therefore, it is necessary to achieve uniformity and desired chemical composition and maintain these at all production stages according to the type of cement produced. To achieve this goal the production planning and pit design play an essential role. This paper briefly outlines the production optimization of cement raw materials in a quarry in Istanbul western part of Turkey. For the purpose it was used the 3D ore body modeling and the geostatistical techniques. The variation of chemical components (%CaO, %Al2O3, %Fe2O3 etc.) and quality control parametres (LSF, SR, AR and etc.) obtained from the quarry were determined. Then the values of unknown chemical components and quality control parameters in the ore body were estimated using Kriging which is one of the geostatistical interpolation methods. The open pit design was also created by specifying wall slopes and taking into consideration of the grade distributions of the benches. The most important revolution in the paper is investigating the effects of the block dimensions in block modelling which is important for reserve estimation. The other important point in the study is using the different range values in variogram analysis for determination optimal reserve estimation. n this study, the effects of two parametres on reserve and waste amount estimation were determined according to CaO% distribution. The study was pointed out that the changing of the two parameters are very important for the optimal mine planning and environmental considerations.

Jan 1, 2010

By GRANT COLLIGAN, BROCK O’KELLEY, Corby Anderson

With the world’s ever-growing push to expand technological capabilities, the need for specialized materials including rare earth elements has exploded. One source of rare earths found in the United States is bastnaesite, a rare-earth-bearing fluorocarbonate, mined at the Mountain Pass Mine in California. To increase production, it has been essential to optimize existing processes and create new ones to capture current reserves. This paper presents the results of a research program conducted to expand the understanding of the bastnaesite leaching system. With the help of prior knowledge and thermodynamic calculations, a novel single-stage hydrochloric acid leach system was created to optimize the extraction of rare earths from bastnaesite. Historically, this extraction has entailed the use of a two-stage leach system involving a high-temperature hydrochloric acid leach followed by a caustic crack. We ran a series of single-stage leach experiments by reacting locked-cycle flotation concentrate with hydrochloric acid to test common leaching parameters. The results of these single-stage tests showed significantly higher rare-earth recoveries than the reported recoveries of the historic two-stage caustic crack processes, all while decreasing the number and amount of reagents needed.

Feb 1, 2023

By P. Mousset-Jones

The USBH Mining Systems and Ground Control Generic Research Center funded a project leading to the improved planning of airflow and refrigeration in underground mines experiencing hot working conditions. The project was broken down into approximately five phases: 1. Visiting some of the known hot mines in the U.S. and sending out a questionnaire to determine other mines which might be experiencing hot working conditions in the future. 2. Choosing two mines in which to conduct measurements to determine the insitu rock thermal conductivity and diffusivity, and comparing these values with laboratory determined values. 3. Investigating computer programs available for mine climate simulation, and testing these programs with case study examples from the two mines where the rock thermal properties were measured. 4. Considering improved ways of estimating the wetness factor and experimenting with the use of heat flux meters to more directly measure the rock heat inflow into the airstream. 5. Applying the results of these investigations to simulating the climate for future mine development and production areas at the two- mines. The project is approximately two thirds completed. At the time of writing, the insitu measurements at one of the mines are still being recorded. This paper will be describing the procedures and results of the insitu rock thermal property measurements, and give a brief description of some of the simulated results obtained for a mechanised cut and fill stope case study from the Homestake Gold Hine in South Dakota.

Jan 1, 1985

By R. R. Givler

Since the 1860's the good ole days, oil has been nozzle fed to burners under pressure atomizing the oil into droplets -- 1960's has produced vaporized oil that burns oil with the flame color and consistancy of gas -- If you can tell the difference by looking at the flame, gas or oil I?ll buy the lunch. First, we must ask, "Why all the excitement about Blue Flame?" This question is best answered by you after you have studied the principle of operation and see the result. I will attempt to explain both of these so that you can draw your own conclusions.

Jan 1, 1975

By J. Bilant, B. Carlson, N. Gow

"High-pressure grinding roll (HPGR) technology was evaluated to replace tertiary cone crushing at Coeur Rochester operations (Coeur Rochester Inc.) as an opportunity to improve silver recovery. In 2016 and 2017, onsite and third-party pilot programs were initiated to evaluate the impact on metallurgical recovery and heap leach performance of crushed product generated by an HPGR. In 2018, Forte Dynamics evaluated the HPGR laboratory metallurgical data from Coeur Rochester and all third parties to develop field-scale leach curves based on new crushing scenarios. The laboratory recovery test work data were consolidated and scaled to field conditions to determine projected heap leach performance. Based on the metallurgical testing conducted, the replacement of current tertiary cone crushers with HPGR technology has the potential to increase Coeur Rochester’s silver recovery rate by 8 percentage points, from 61 percent to 69 percent, and shorten the overall timing of silver recoveries from 20 years to just more than two years.The Rochester Mine, and associated valley fill heap leach facilities is an openpit silver and gold mine located in Pershing County, NV, approximately 42 km (26 miles) northeast of the city of Lovelock. In 2017, Rochester produced approximately 4.7 million oz silver (Ag) and 51,000 troy oz gold (Au). Ore mined at Rochester is either fed directly to the primary X-Pit crusher, crushed at an in-pit crusher system, or placed directly onto a heap leach pad as run-of-mine (ROM). Both crushing circuits are comprised of three stages of crushing to produce a nominal 3/8 in. ore. Primary crushing consists of jaw crushing while secondary and tertiary crushing are composed of varying cone crushers.Historical recovery rates of crushed Rochester ore averaged 61.4 percent Ag and 95.9 percent Au over a period of 20 years (Robinson et al., 2018). These rates were derived from third-party verification of in-house metallurgical test results, crusher production and heap leach production results from 1986 through 2004 in a private report for Rochester produced by KD Engineering Co., Inc. Recovery rates are regularly verified by compositing daily samples of ore delivered to each leach pad from the X-pit crusher, in-pit crusher and/ or ROM. A proportionate split of each sample is used to generate monthly composites for metallurgical analysis utilizing column leaching and bottle roll leaching. These tests are run in a manner analogous with production conditions and deliver test results that provide expected heap leach performance. As the Rochester oxide deposit has been mineralogically and metallurgically consistent, the gold and silver recovery trends have also been consistent over the life of the project."

Sep 1, 2019