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By O. F. Brown

Excavation and loading are primary operations in the surface mine production chain, constituting a significant component of production costs. This makes excavation and loading important cost centers that need to be improved to lower production costs. Optimizing the design and use of excavators will improve energy efficiency in earthmoving operations, and this requires a thorough understanding of the soil-tool interaction process. Modeling the interaction process accurately is the key to this optimization. Experimental and analytical methods have provided limited information on the behavior of soils during excavation. Finite element (Fe) analysis of soil-cutting blade interaction produces some advantages over experimental and analytical methods. However, the soil constitutive equations used in most of the available Fe analyses fail to adequately model the plastic behavior of the soil. This work uses Fe modeling to study the behavior of formation-cutting blade interactions in dozer excavation. The formation is modeled as a nonlinear elastoplastic material using the modified cam-clay (mCC) model. The model accounts for soil-tool interface friction, and progressive and continuous cutting at the blade tip. The results provide soil forces, a progressive developed failure zone and soil displacement fields. The sensitivity analysis of changes in blade angle on cutting force shows that the cutting force increases with increasing blade angle. The cutting depth of the blade had a similar effect on blade cutting force. Increasing the depth of cut increases the required cutting force. Increasing the coefficient of friction at the soil blade interface increases the blade cutting force. Reducing the coefficient of friction at the soil blade interface from 0.3 to 0.05 reduces the cutting force by 22.3%. The percentage represents the maximum potential savings in blade cutting force. This research initiative advances the frontiers of soil-tool interactions during excavations to expand the limited knowledge in this critical area.

Jan 1, 2012

By C. Frenzel

Tunnel boring machines (TBM) utilize disc cutters as the primary means for excavating hard rock. Depending on rock excavatability and rock abrasivity disc cutters can exhibit significant wear. A detailed analysis has been carried out to characterize failure modes and wear patterns of disc cutters. The relationship between rock properties, op-eration of the TBM, and failure modes of cutting tools is clearly high-lighted. On that basis a prediction tool for disc cutter consumption has been developed that allows to estimate not only gross cutter life, but accounts for cutterhead design, premature cutter changes, and disc cutter repair costs.

Jan 1, 2011

Although out of the ordinary, MINING ENGINEERING is pleased to present a few photographs that typify Western US mining activity during WWII. The photographs, taken by R.G. Zellers at Colorado mining operations between 1942 and 1946, were primarily intended for equipment manufacturers. The pictures capture scenes of hardworking miners during a time when output was essential to fuel a wartime effort. In addition to providing a rare opportunity to step back 40 years and view the equipment and activity common at the time, Zellers' skill with photo composition and his ability to obtain clarity in dimly lit underground operations gives viewers an acute awareness of the dampness and dirt of the mines, and a sense for the miners' limited working space.

Jan 6, 1983

By Joaquin Ruiz

Naica consists of at least 10 mantos and 40 chimneys that have produced over 15 million tens of ore with 10% Zn, 13% Pb and 13 oz/ton Ag. The ore occurs in thick-bedded, folded Cretaceous limestone. Fractures and 26 Ma old felsite dikes with an initial strontium isotopic ratio of 0.708 localize the mineralization. The mantos follow the dikes and have abundant early skarn with manganohedenbergite, calcic garnet, idocrase, quartz, calcite, wollastonite, schellite and later sulfides. The chimneys arise from the mantos and change from silicate-rich to silicate-free sulfide limestone replacements. Carbon, oxygen and sulfur isotope data on carbonates, silicates, sulfides and sulfates are compatible with a single evolving (magmatic?) fluid.

Jan 1, 1985

By N. Del Bel Belluz

Drilling underground in the Grasberg De-watering drifts has routinely hit water aquifers with high flow rates and pressures. Two types of holes are utilized; pilot-holes to probe ahead of the tunnel development to intersect aquifers ahead of the face; and de-watering holes to de-water rock formations that will drain water from the Grasberg pit and allow tunnel development to proceed safely. Recently, rates of 1050 psi static pressure have been recorded with flows from a NQ hole measured at 1350 gpm (US). The water flows can be slightly acidic, necessitating the use of stainless steel collar gear to resist corrosion. These rates were anticipated and contingencies were planned early to deal with these conditions. The collar gear is used to control water flows whereby the water is treated as an important resource. As a result, pm has established procedures to maintain safety of the drill crews, enable coring of the rock and to maintain safety of the miners who are driving the drifts.

Jan 1, 1998

By Thomas P. Meloy

Comminution is an old art. Unfortunately the analysis of the unit operations has been handicapped by the lack of both theoretical and experimental information. Two types of infor¬mation are needed, one an understanding of what happens when a particle breaks in a brittle manner; and two, an understanding of what happens when the daughter fragments pass through the mill. This paper is concerned with the former, the catastrophic fracture of a brittle solid. Recently, successful theoretical attacks on the frac¬ture of brittle solids have yielded significant-results. New experimental techniques are yielding insight into the physical phenomenon occurring during brittle fracture. Many of the re¬doubtable shiboliths of the last century are either being laid to rest or verified.

Jan 1, 1965

By J. D. Miller

The fossil resins of certain western coals are of significance and of sufficient value as a chemical commodity to justify a fossil resin industry. At the present time these valuable fossil resin resources, worth more than $0.50/lb as a chemical commodity, are being burned as fuel for electric power generation. This waste of our fossil resin resources corresponds to a loss in revenue of $200 million per year -equivalent to the value of the coal itself! Improved process technology for the recovery of fossil resin is under development and includes selective flotation of fossil resin from fine coal streams and solvent refining of the fossil resin flotation concentrate to produce a premium resin product. The most recent developments in process technologies are discussed with respect to separation efficiency and product quality. It is clear that the development of a fossil resin industry should not be limited by process technology.

Jan 1, 1994

The speed and internal accuracy of today's electronic calculators can be utilized to write an efficient slurry calculation program. The calculator's input/output printing feature offers additional benefits for data organizing and record keeping. This program allows slurry calculations to be performed without the urgency of immediately transferring a calculated result onto a process flowsheet or specification sheet. The number of flowsheets required for some hvdrometallurgical processes means the number of process stream blocks or ladder diagram entries can become substantial. Slurry calculations for such projects tend to become repetitious and tedious, and the chances for errors increase both in calculation and data entry onto process documents. Using this program has minimized both types of errors. Checking process flowsheets is particularly expedient with the program because you may "walk" through the flowsheet on a weight basis, i.e., solids rate and solids density, and have the program verify and/or correct the volume entries, gallons, and specific gravities. The program was initially used on a beneficiation project to check some 500 data entry values on ladder diagrams covering seven process flowsheets. Numerous hand calculation errors were determined and corrected, and the time for completely checking and correcting the flowsheet ladder diagrams was substantially reduced.

Jan 4, 1981

By C. D. Taylor, A. L. Mazzella, A. L. Martikainen

In fluctuating airflow, continuous air velocity recording is the most reliable method of air velocity measurement. It allows for fast recognition of changes and the calculation of long-term averages. Also, it enables the mine operator to identify when the airflow has decreased to a point requiring action. Using ultrasonic anemometers provides an accurate option for continuous air velocity monitoring. This paper provides information about the effect of common obstructions in underground mining on air velocity readings. Stationary and moving obstructions are used to represent workers and equipment that would cause discrepancies in measured airflow. Also, it is important to know how large of a sample size is required to ensure reasonable accuracy of results. Statistical analysis is used to evaluate the required sample size. The sampling procedure is further studied by comparing two different sample rates. The results show that obstructions provide noticeable differences in air velocity measurements. Also, movement of obstructions can be recognized from changes in results. Surprisingly small sample sizes provide reliable air velocity information. Standard sample rates are found to be suitable for the underground environment.

Jan 1, 2011

By Weijie Wei, Jinwang Zhang, Shengli Yang

In longwall top-coal caving (LTCC) mining with an inclined seam, the recovery rate is low and equipment stability is poor due to the unbalanced top-coal drawing process. To address these problems, this paper proposes the dynamic group caving method (DGCM), whose basic premise is that when the drawn volume of top coal from a support reaches about half, the next support begins drawing top coal, and the drawing process between the two supports is half done. Using particle flow code (PFC), the caving mechanism of top coal under DGCM was investigated. The results are of significance to realize high efficiency and precise caving in LTCC mining with an inclined seam.

By Pedro Pablo Vasquez Coronado, Victor Octavio Tenorio

"Productivity in openpit mines depends on the observation and adjustment of critical phases of operation. As one of the most expensive activities in openpit production, optimization of the load-haul-dump cycle becomes a critical aspect to address. Using simulation techniques and an ad hoc methodology for analyzing the key performance indicators (KPIs) involved in the production cycle, it is possible to compare actual performance and ideal operating conditions and develop an alert system when operating conditions are subpar with the expected production standards.Study objectivesThe purpose of this work is to implement a methodology for optimizing the haulage cycle by identifying and adjusting the factors that affect the cycle time performance. The methodology includes the implementation of an alert system emitting warning messages when one or several trucks are idle, or when the time of completing production tasks is falling outside a predefined value. This alert is compared with predefined KPIs and is used to determine corrective actions.The alert will:• Demonstrate the benefits of time analysis and how this affects the productivity results in the mining process.• Demonstrate the utility of KPIs in the extraction of ore and waste and how they help to identify equipment performance.• Develop software interfaces to visualize the alert system in order to increase awareness in the operations supervisor.• Make recommendations for future applications that can help improve the productive process of an openpit mine.Problem statementTransporting material in openpit mines may require the utilization of high capacity equipment, which also represents an elevated cost per hour. A supervisory system that controls the adequate distribution of trucks and shovels by providing the operational status of each unit shall contribute to increase productivity while subsequently reducing operational costs. Nevertheless, there is an issue with certain dead times such as queue trucks for loading, trucks waiting to be loaded and other delays. This creates inefficiencies in fuel consumption and energy utilization.For the identification of delays, a contextbased system could be required in order to help optimize the haulage cycle time by controlling delays in loading, haulage and dumping. After applying this methodology, efforts were focused in correcting out-of-standard performance values."

Jan 1, 2015

By J. A. Lombardi

Acid-Minesite-Solutions (AMS) are defined as copper-containing pit lake, tailing pond, acid-mine-drainage, and heap and waste dump irrigation solutions. All of these solutions are characterized by copper, acid and water contents that have value as individual commodities. HW Process Technologies, Inc. (HWPT) has developed nano- and hyper-filtration membrane methods for the separation of copper and other base metals, acid and water from AMS. These treatments are collectively called HWPT?s Engineered Membrane Separation® (EMS®) systems. The EMS® method of copper recovery produces small volumes of higher-concentration copper solution from large-volume, copper-dilute AMS. A case study of the 4,000 gpm Cananea EMS®-AMS plant for the recovery of copper from an acid-pit-lake resource is described. The EMS® method of copper removal from AMD and tails pond waters has been bench-scale demonstrated and are described, complete with projected budgetary capital and operating costs. Additional treatments for the recovery of sulfuric acid and high-quality water from the permeate (membrane passing) waters for the above-described AMS treatments are presented, with budgetary capital and operating cost estimates. [ ]

Jan 1, 2009

By D. D. Gertenbach

"The successful commercialization of a pressure oxidation (POX) process for recovering metal values, including gold, copper, zinc, nickel and molybdenum, is the result of a carefully planned development program. The initial task involves developing one or more conceptual flowsheets, including the POX autoclave and downstream purification and recovery steps. A laboratory program is completed to determine the technical viability of the flowsheets, define the operating parameters for each step and provide information for an initial economic assessment of the process. The process is then confirmed during a continuous pilot plant program, providing engineering design data and other information for the commercial design. A well-thought-out development program has been shown to be critical for reducing the risk of commercializing POX processes. Experiences developing POX processes for refractory gold ores and copper concentrates are briefly discussed. IntroductionPressure oxidation (POX) has become a common commercial operation for processing sulfide-bearing feedstocks. These feedstocks include gold ores and concentrates; copper concentrates; nickel concentrates and mattes; zinc concentrates; and molybdenum concentrates. Drivers for the development and commercialization of POX processes include:• The high cost for pyrometallurgical processing of sulfide ores, much of which is attributed to environmental controls.• The motivation to implement safe and more environmentally attractive alternatives for sulfide ores.• The need to process increasingly difficult ores with complex mineralogy.• Improvements made over the last 25 years in POX equipment design and experience operating commercial POX plants.Although the capital and operating costs for commercial POX processing can be high, this technology is capable of rapid oxidation of most sulfides and arsenic minerals in the feed, with little noxious gases and environmentally stable iron arsenate and other iron compounds in the POX residue (Marsden and House, 2006).In POX operations, sulfides are oxidized to either sulfates or elemental sulfur in an autoclave at elevated temperature and pressure with oxygen gas. An example is the overall oxidation reactions of chalcopyrite when sufficient oxygen is present, shown in the following reactions:"

Jan 1, 2016

By L. Diestelow

Evaporation and crystallization processes are used extensively in the mining industry to provide many pro-ducts. In the case of solution mining evaporators are used to concentrate, or to concentrate and crystallize the raw materials being mined. In the case of underground, or strip mining dissolving and crystallization are used in many processes in order to purify the ore to saleable materials. Presently evaporators and crystallizers are being used in the production of sodium chloride, potassium chloride, sodium carbonate, sodium sulfate, lithium chemicals, aluminum, and many others. The evaporator is a device designed to remove water or solvent from a solution. In an evaporator the energy released by steam condensing on one side of the heat transfer surface is transferred to the product solution on the other side of the heat transfer surface. As long as the boiling temperature of the product liquor is below the condensing temperature of the steam, the product solution will absorb heat. This heat absorption causes vaporization of the water (solvent) in the product solution resulting in concentration of the product. The simplest evaporator is the single effect evaporator. If we assume the feed introduced into the single effect evaporator is at its boiling point, ignore radiation losses, and assume the steam into the heat exchanger is dry and saturated, then the heat transferred will correspond to the latent heat of vaporization. Therefore, one kilogram of condensing steam will produce one kilogram of evaporation. Economies in energy usage compared to the single effect evaporator can be made by using multiple effect evaporators, or vapor recompression evaporators.

Jan 1, 1993

More than 1,200 professionals from the global tunneling and underground space industries are expected to be on hand for the 2009 Rapid Excavation and Tunneling Conference to be held at Caesars Palace in Las Vegas, NV. The conference, set for June 14-17, is sponsored by the Society for Mining, Metallurgy, & Exploration, Inc. (SME) and the Construction Institute of the American Society of Civil Engineers. The four-day conference will feature more than 100 technical papers in 19 sessions. Two one-day short courses are also planned, as are a pair of field trips. And the show?s exhibit will feature more than 120 of the industry?s leading equipment and service suppliers.

Jan 1, 2009

By A. Ghosh

Commonly used predictors of ground vibration from blasting, being linear in log-log plot, do not model the underlying physics of wave attenuation. Amplitude of the wave decays with distance due to geometrical spreading and inelastic attenuation producing a nonlinear carve in log-log scale. The nolinear decay of seismic waves has also been observed from non-explosive sources, such as, pile driving, drop hammer, traffic, etc. The improved predictors, by explicitly taking these two mechanisms into consideration, model the data trend extremely well at all distance ranges. Actual field data from different studies have been used to validate the improved models.

Jan 1, 1991

The most complete mining show ever held in the United States and the largest exposition of its kind to be held anywhere in the world in 1988. That's how the American Mining Congress is billing its "MINExpo International '88," to be held April 24-28 at Chicago's McCormick Place, the largest exposition facility in the country. MINExpo International '88 will combine for the first time two previously separate AMC-sponsored shows - the International Coal Show and the International Mining Show. Starting with the 1988 show, MINExpo International will be held every four years. The next show, in 1992, will be held in Las Vegas. The MINExpo in Chicago will feature more than 500 mining equipment and services exhibits covering 3 hm2 (320,000 sq ft) of exhibit space. Exhibitors will display products ranging from small safety devices to large earth-moving equipment. MINExpo is one of the few trade shows selected by the US Department of Commerce for its Foreign Buyer Program. Commerce is working with US embassies around the world to publicize MINExpo and to form delegations of visitors from many countries. Overseas visitors to the show will be assisted at an on-site International Business Center. It will provide currency exchange, translation, and other services to foreign buyers. Registrants at MINExpo will also be able to attend their choice of 27 morning-only program sessions. At these sessions, international mining experts from industry, government, and academe will analyze technical, strategic, and policy matters and discuss the outlook for the industry. "Toward the 21st Century" is the theme of this year's program. The technical workshops and managerial seminars are designed to assist mining executives, engineers, and geologists as well as mine superintendents, managers, and foremen in handling their responsibilities. Based on previous attendance at AMC international mining shows, the association says that more than 25,000 persons are expected to attend the Chicago show. It is expected that approximately 15% of the attendees will be from foreign countries. The Soviet Union will be among those exhibiting at MINExpo. The Russians have leased more than 2.8 dame (3000 sq ft) of space to display their mining machinery and equipment. It is the first time that the Russians have joined in an exhibition of mining equipment in the US. The two largest manufacturers of mining equipment in the Soviet Union, Setmash and Avtoexport, will put on display in Chicago a variety of Russian-made equipment. It will range from 100 t (110 st) heavy-duty dump trucks and diesel engines to drilling, hoisting, and conveying equipment. In addition to some 400 US exhibitors of mining equipment and services at MINExpo, nearly 100 companies will be present from other major mining nations such as Australia, Canada, Great Britain, Japan, the Netherlands, and West Germany. And, for the first time, a Chinese manufacturer will take part in the AMC show, participating with its US marketing partner.

Jan 3, 1988

By M. A. Trevits, G. Frampton

"Mine safety training materials have long included pictures of mine conditions, equipment, hazards, etc. These images are invaluable to both the trainee and the trainer to convey many important concepts. The human eye takes in a tremendous amount of information, while the field-of-view from a consumer grade camera is, generally, 40 degrees to 90-degrees. This difference in field-of-view is a primary reason that pictures, especially of dark and dusty areas, don’t adequately describe the scene. For conveying information to a trainee, these images lack context. Today, 360-degree cameras are available with consumer-grade cameras costing a few hundred dollars. Also, the display technology is already owned by most trainees and trainers and is widely available. The resulting 360-degree videos and pictures can be readily viewed on smart phones and inserted into Microsoft PowerPoint slideshows. These images and videos can easily be included in existing training modules, disseminated using the internet, and used by trainees easily. We propose a methodology for utilization of 360-degree video and images with simple display technology for miner training. INTRODUCTION AND BACKGROUND In mining, as in other production-related industries, the safety of workers is dependent upon many interrelated factors. One of the more important safety factors is a miner's ability to recognize hazards in their workplace. The ability to perceive and identify hazards is perhaps more difficult to master in underground mining than in general industry because the work environment is confined, noisy, dark, and inherently dangerous because of the hidden unknowns created by the geological setting and the conditions created by the mine opening. Further complicating the situation is a setting that is continuously changing as mining advances (Barrett 1995) [1]. Hours of excellent mine safety training have been developed and utilized over the years. Pictures of mines, activities, hazards, etc., are included in many of these training courses. These photographs, especially those taken underground, often lack context because of the limitations of the cameras and lenses. Notable research by the US Bureau of Mines and then later by NIOSH showed that the use of stereoscopic three-dimensional slides in training exercises was an effective aid for improving the ability of miners to recognize hazardous ground control conditions (Barrett 1988) [2]. An example of type of three-dimensional slides and slide viewer is shown in figure 1."

Jan 1, 2018

The Earth?s population is approaching 6.6 billion people. More than half live in urban areas. And, as those figures continue to grow, the need to make wise use of the world?s natural resources as well as its living space will also grow. Thus, the concept of sustainable development ? meeting the needs of the current generation while preserving resources for future generations. The use of underground space is only one part of the sustainable development concept. But it is an important one. Tunnels and underground space are environmentally friendly and contribute significantly to sustainable development. But it takes years to plan and build tunnels and other underground infrastructure. And the demand for infrastructure in the world?s mega cities has grown significantly. In December, about 100 people representing several developed and developing nations spent a day at the United Nations (UN) in New York City discussing the future of underground space development throughout the world. The meeting was put on by the UN?s Department of Economic and Social Affairs and the International Tunnelling and Underground Space Association (ITA). The conference was titled ?The Use of Underground Space as an Unexpected Solution for Promoting Sustainable Development.? Its aim was to promote practical solutions to the use of underground space and tunnels as feasible alternatives to promote sustainable development throughout the world. A panel of speakers from government, academia, the UN and the ITA stressed that development is not sustainable without infrastructure. And, as the world?s population grows, there is now an urgent requirement to efficiently plan for the use of underground space to preserve it for the future benefit of mankind. The benefits of the use of underground space are many, they said. Among them: ? Tunnels channel clean water in and waste water out. This promotes health and sustainability worldwide, particularly in developing countries. ? The use of tunnels and underground space helps conserve energy and increases its efficient use ? the use of tunnels cuts commuting time and so saves energy. ? Tunnels, microtunnels and other underground structures promote the more efficient use of space in large cities ? the bulk storage of water, fuel and other goods. ? Underground structures are subject to less stress than surface structures, making them safe havens for natural and man-made hazards, including earthquakes. And, because underground structures are more durable, lifecycle costs are less than surface structures. ? Underground structures promote the multiple use of available land. Land owner-ship at several layers increases land use and provides more usable space. Han Admiraal is director of the Center for Underground Construction in the Netherlands. He said that urban planners need a new vision concerning the use of underground space. Going underground protects historical and archaeological surface facilities, he said. Underground space use can also protect populations located in adverse climates. And sensitive environmental areas on the surface can also be protected from development. In addition to the transportation of people, freight and water, underground development can also store water, as well as provide storage for waste, hazardous materials, carbon dioxide and geothermal energy. The upshot of this new awareness and vision for under-ground space is that its use should be considered before surface development, Admiraal said. And planners and developers are placing more emphasis on underground space development as part of their overall development plans for urban areas. That was not always the case, he said. In the past, underground space was not considered until after the surface space had run out, he said.

Jan 1, 2008

By Judson H. Whitman

To evaluate intelligently and to market a source of rare earth raw material, it is necessary that the producer understand the requirements of the processor and the manner in which these requirements effect the value and salability of his product. This paper will be an attempt to aid in such an understanding. The majority of rare earth processors are primarily chemical companies, not mining or metallurgical companies, as the complexities of the processing procedures are' much more chemical in nature than metallurgical. The rare earths and the rare earth industry are normally divided into two groups - the ?light? or cerium group and the ?heavy? or yttrium group. They are so named because cerium and yttrium are the most common elements in 'heir respective groups and are so divided on the basis of mineralogical and chemical characteristics. The dividing line of the two groups is not rigidly fixed but usually is considered as being between samarium (atomic number 62) and europium (atomic number 63). Although the two groups are quite similar, processing procedures differ significantly, hence most processors tend to specialize in one group or the other. There is, however, a growing tendency toward participation in both groups.

Jan 1, 1960