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By T. Y. Yan

A method has been developed to remove calcite from the leaching circuit in the uranium in situ leaching system. The process involves injecting the leachate and a pH control agent tangentially into an inverted cone reactor containing calcite seed catalyst. The leachate can be treated at high throughput to obtain clear effluent containing 5 ppm or lower Ca. Both lime and ammonia are effective pH control agents and consumed according to stoichiometry.

Jan 1, 1983

By Hesam Dehghani, Farid Alimohammadnia, Nima Babanouri, Mokhtar Kalhori

In open-pit mining, blasting pattern design is performed to achieve a desired degree of fragmentation for loading, hauling, and crushing operations. Inappropriate fragmentation of rock will result in numerous problems such as incurring extra costs for secondary blasting, production interruption, etc. Wetness of the blast holes is one of the most important factors, which can cause the inappropriate rock fragmentation. Lowering ambient temperature in the vicinity of the explosion, the presence of water in the hole adversely affects the quality of the explosive while dissipating part of the explosion energy, ending up with inappropriate fragmentation problems. In the present research, in order to study blast-induced fragmentation conditions in Baba-Ali Iron Ore Mine, three scenarios were considered: explosion of ammonium nitrate with fuel oil (ANFO) in dry hole, explosion of ANFO in wet hole, and explosion of the emulsion in wet hole. For this purpose LS-DYNA, a numerical simulation code was used. Results of the present research showed that, compared to the explosion of ANFO in wet hole, the explosion of the emulsion produced more uniform distribution of fragment size, while the explosion of ANFO in dry hole resulted in fewer large fragments.

By L. H. E. Weyher

A mine is essentially a vast materials-handling system. All other systems found in the mine exist to one degree or another to support the materials-handling functions, from the cutting at the face to the hoisting in the shaft. In this chapter computerized planning of underground materials-handling systems will be examined by dividing this function into: (1) the planning of the production section, and (2) the planning of underground rail or belt haulage from the production section to the shaft, slope, or surface. While alternative divisions might focus on the different materials- handling functions, i.e., production, supply, and manpower transportation, historical computer analysis has focused on the various systems rather than functions. The emphasis in this chapter is directed toward coal mine applications; however, most of the programs and methods are equally applicable to other underground mines. Markedly different methods are encountered in each system, and moreover, marked differences exist in the nature and the degree to which the materials-handling subsystems in each interact with the environmental or support systems. The most intimate interaction exists at the faces where geologic, human, and machine performance factors are closely related and constantly varying. In view of this, the planning of the materials-handling systems for the face will usually stress flexibility, while the outby materials-handling systems will generally place decreasing emphasis on flexibility and more on system reliability, capacity, and cost effectiveness. Thus, hoisting and main haulage systems are generally designed and constructed as permanent installations and cannot be readily changed, whereas secondary haulage systems and face operations are relatively mobile. These differences may have considerable significance for the mine planner in making technical and financial comparisons of alternatives to provide the scheduled mine production.

Jan 1, 1979

By Leon J. Jacobs, Kyle R. Ott

This paper discusses design and construction aspects of the tunnel, shaft and station for the Weehawken Tunnel and Bergen line Avenue Station. The project consists of a 1,269 m (4,156 ft) long existing railroad tunnel, which will be enlarged and equipped with a two-track light rail system. The project also includes construction of a deep underground station, with a large shaft connecting the surface station to the below ground station for access and ventilation purposes. Vibration and noise from blasting is a critical community issue and blasting adjacent to two 230-kV duct banks located in the tunnel invert required special blasting procedures.

Jan 1, 2003

By Z. Sample

"INTRODUCTION This past year commodity prices continued their dip with increased volatility causing market values to slide another 16% putting increased pressure on even the largest companies to improve their free cash flow.[1] Without a recovery in commodity prices in sight, companies must find a sustainable method to improve returns in the current economic climate. In an effort to improve plant sustainability, the mineral processing industry is investing in advanced automation technologies and innovative processing methods that are both more reliable and more efficient than ever before. One such breakthrough technology is Heap Leaching (HL). This method of extraction has certain advantages over traditional metallurgical methods making previously unsustainable operations economically feasible. While HL is already seeing use in the gold and copper industries among others, recent developments may allow for the use of HL to process primary sulfide ores which make up about 80% of today’s ores.[2] For this reason, this emerging technology is poised for exciting growth. Unfortunately, as with any process change, the implementation of HL projects requires significant training on both the control system as well as the underlying process, and further, due to the complex nature of the HL process, this can be a particularly difficult task. DEMOGRAPHIC TIME BOMB Even before the implementation of these new technologies, the availability of the skilled workforce has already become a significant problem for the mining and mineral processing industries. From a survey of 912 mining professionals, Stratum International found that a mere 0.4% of senior level candidates were between the ages of 25 and 34 and a similar proportion aged over 75 years.[3] This indicates that there is both a deficiency of young skilled workers and a skilled workforce that is retiring earlier than the previous generation. Combined with data published by the US Department of Labor stating that the median age of the mining workforce is approaching 50 years old, research suggests that up to 50% of skilled mining and mineral process professionals are expected to retire in the next 5 years, leaving with their irreplaceable knowledge and experience.[4] While it is projected that the labor pool will be sufficient to fill open positions, the real question is if this young workforce will have necessary skill sets and experiences. In addition to a rapidly aging workforce and an inexperienced labor pool, a study done by the Oil and Gas Journal showed that it takes about 7 years, on average, for new workers to achieve a level of competency that permits them to assess risks and appropriately make decisions.[5] Not only is this figure is in direct conflict with the typical tenure of 5 years in one position meaning that the thinly spread skilled labor will be required to become senior staff before they are able to achieve competency in their current role, this also means that these millennials are not given the opportunity to become competent in their role before the retirement of the more experienced workforce."

Jan 1, 2016

By S. K. Kawatra, T. C. Eisele

Production of highly-cleaned coal for advanced utilization schemes requires close control of the coal ash content at very low levels. For this purpose, a sensitive, low-cost, robust on-stream ash analyzer is needed. The development of such an instrument based on x-ray backscatter and fluorescence is described, including features to improve its sensitivity at low ash levels. The performance of the resulting device in testing a real coal sample is discussed.

Jan 1, 1990

By Z. Rogovin

A Knowledge of the amount of time the material spends in a continuous mill in a closed-grinding-circuit is essential for circuit performance analysis and scale-up design. A convenient method for acquiring this information involves the use of tracers in residence-time-distribution (RTD) experiments. In a typical wet process the RTD measurements are usually done by injecting a pulse tracer into the mill inlet and detecting it in the circuit exit. In this article a simple to use mathematical method for the calculation of the closed circuit material residence time in the mill is developed. Using this method there are no restrictions on the location of the tracer injection or detection points. Any convenient location in the closed circuit can be chosen without affecting the simplicity of the method. This method also enables the calculation of the degree of mixing in the mill. The use of this method for the analysis of impulse response data obtained from several commercial grinding circuits is presented.

Jan 1, 1986

By Jr. Winters

The United States continues to be the largest producer and consumer of copper in the world. Table 1 on the following page shows several production statistics for 1974, the most recent year which the non-communist world copper industry might consider a good year, and for 1976 and 1977. In 1974 an estimated 24 percent of the non-communist world's newly mined copper was mined in the United States, and. 87 to 89 percent of that was from the western porphyry coppers. In 1976 U. S. new mine production was down to 22 percent of the non-communist world's newly mined copper, and the percentage of U. S. new mine production supplied by the porphyry coppers had risen to 89 to 91 percent. In 1977 the statistics remained the same as in 1976. U. S. porphyry copper production represented about 65 percent of U. S. refined copper consumption in 1974, rose to 75 percent in 1976, and dropped back to 61 percent in 1977 as imports of foreign copper into the United States began to swell.

Jan 1, 1978

By Lauren M. Roberts, Ralph R. Sacrison

The Meikle Mine uses long-hole open stoping and cut-and-fill methods with backfill as the primary ground support technique. The mine operates at 2,858 tonnes per day (3,150 tpd) and has sustained operation in excess of 3,175 tonnes per day (3,500 tpd). Consistent backfill production is critical in achieving these mining rates. The heart of the system is a 7.65 cubic meter (10-cyd) horizontal shaft ribbon mixer located 328 m (1,075 ft) underground. System control is through several PLC's, allowing for a high degree of automation and process flexibility. Aggregate feed is routed 257 m (842 A) through vertical drop pipes in the ventilation shaft, a rockbox, transfer raises, and then into either of two raisebored storage silos. The aggregate is crushed mine waste, nominally 70% 3.8 cm x 1.0 cm (1-1/2"x 3/8") and 30% -1.0 cm (- 3/8"). The binder is routed through a vertical borehole, surge bins, and transfer raises. The binder is a mixture of Type II cement and fly ash. Two primary manufactured fill designs are produced: a high strength mix for stopes which will be undercut; and a low strength mix for stopes with only rib exposure. The high strength target is 5.5 Mpa (800psi) unconfined compressive strength in test cylinders. The low strength target is 2.8 Mpa (400 psi). The systim has allowed consistent achievement of these targets, while experience has allowed reduced costs and increased efficiencies. Fill placement is through 6.1 cubic meter (8 cyd) LHD's dumping into stopes. Specific sills and cut-and-fill drifts are jammed to the back. System enhancements have included colloidal mixers for cemented waste slurry placement and transfer raises for sending manufactured fill to the lower levels of the mine.

Jan 1, 2001

By Carl E. Bagge

It is easy for a coal spokesman to relate to the theme of this meeting--that the decade of the 1970's is pivotal for the mineral industries. For the coal operator, this period is crucial. The coal industry, according to most energy forecasters, must gear its production machinery to meet a sharp rise in the demand for coal--in this decade to sustain inevitable boosts in electricity output, and in the next to start supporting a big new domestic synthetic fuels industry that is already in the formative stage. The logic of that projection flows from a combination of hard circumstances--proved reserves of domestic fluid fuels are dwindling, the hope for bountiful and cheap nuclear power must be indefinitely deferred, and the threat of long-term fuel imports to the national interests is becoming starkly visible. Only coal, with its assets of abundance, security and versatility, offers the nation an adequate and immediate lift out of its current energy crisis. A hard-won expansion of coal production made the critical difference between local power load-shedding and major area blackouts in 1970, the year the energy crisis went public. Coal will have to play that same key role, not just through this pivotal decade but through the turn of the century. But the logic of fuel demand apparently does not always extend to supply. The coal industry has had a huge production job laid out for it by the energy statisticians, but up to now the energy policy-makers have not followed through with the aids and inducements that the coal operator urgently needs to do that job well and completely.

Jan 1, 1972

High pressure grinding rolls have found widespread acceptance for cement processing, and are now making their debut in the metalliferous minerals industry. Significant energy and wear material savings appear achievable in many applications. This paper re- views the technical literature on this important, emerging technology.

Jan 1, 1997

By N. Economou

Temporary local seismic networks were installed in western Crete, in central Crete, and on Gavdos, an island south of western Crete, in order to image shallow seismically active zones of the Hellenic subduction zone. Data acquisition was divided in four campaigns through the years 1996 to 2001. More than 4000 events in the magnitude range between 0.5 and 4.8 were detected and localized. The resulting hypocenter distribution allows the localization of seismically active zones in the area of central Crete from the Mediterranean Ridge to the Cretan Sea. The comparison of the hypocenter distribution and the structure has allowed intraplate and interplate seismicity to be distinguished. A southwards dipping zone of high seismicity within the Aegean lithosphere is found south of central Crete in the region of the Ptolemy trench. Between 20 and 40 km depth beneath central Crete, the Aegean lithosphere appears to be seismically inactive. Especially for the year 2001, 1560 events were localized, by the seismic network installed on Messara, central Crete. Most of the seismic events were located, as expected, in the South region of central Crete. National Observatory of Athens (NOA) maintains a permanent seismic network in Greece. In this work a comparison of the earthquake epicenters obtained from both the NOA network and the BOCHUM-TUC network is presented.

Jan 1, 2006

By W. Bosmans

The European Commission published its Communication of the Thematic Strategy on the sustainable use of natural resources ("Resource Strategy") on 21 December 2005. The Resource Strategy aims at reducing environmental impacts associated with resource use - called decoupling - in a growing European economy and worldwide. The impacts of unsustainable resource use include e.g. climate change due to fossil fuel use, land use and environmental degradation due to mineral extraction and processing, or overexploitation of soil and fish stocks. To decouple environmental impacts from economic growth, a life-cycle approach is adopted. It means that the environmental impacts are taking into account at each stage of the life cycle of a resource, avoiding that negative impacts are shifted to other environmental media, to other stages of the life cycle, or to other countries. Key to achieving decoupling are three factors: - More value - creating more value while using fewer resources (?resource productivity?); - Less impact - reducing overall environmental impact per unit of resources used (through ?cleaner? technologies and consumption pat-terns); - Better alternatives - substituting currently used resources with better alternatives. The paper focuses on the implementation actions of the Resource Strategy in particular related to the minerals industry: 1. The Data Centre on natural resources; 2. Indicators to measure progress; 3. The involvement of economic sectors to take concrete actions; 4. EU Member States involvement, focusing on resource uses with the most significant impacts; 5. The International Panel on the sustainable use of natural resources, set up together with UNEP. With its 25 years time horizon and its wide approach the Resource Strategy will have a co-ordinating function to ensure enhanced coherence and efficiency. The challenge will be to integrate this approach into all policies and decision-making.

Jan 1, 2007

By Natalie White, Joel Asp, Allyz Kramer

"Minnesota has robust reclamation standards and have proven results in the taconite mining industry. Reclamation of overburden spoils, lean ore spoils and fine tailings from taconite production has generally been successful on the Iron Range, using a low input standard reclamation practice. Success at reestablishing vegetation on these landscapes is likely due to fairly favorable chemical and physical properties (e.g., few limitations due to acidic generating materials, metal toxicities and water and nutrient holding capacities). However, coarse tailings reclamation has proven more difficult, presumably due to lower nutrients and challenges with moisture holding capacities. Research efforts conducted since 1990 have struggled to develop a reclamation strategy for coarse tailings that meets the Minnesota Mineland Reclamation Rules, Chapter 6130. However, new breakthroughs in scram mining technologies are producing fine and coarse tailings that have not been encountered nor reclaimed in northern Minnesota. Scram mining in Minnesota is defined as those mining operations that produce natural iron ore concentrates. Innovative research is underway to investigate and determine successful reclamation strategies to reclaim scram mining tailings from these scram mining operations. The research program is conducted through collaboration with SEH, Prairie Restorations, Inc. (PRI) and Mining Resources, LLC with funding support from the Iron Range Resources and Rehabilitation Laurentian Vision Partnership minescapes grant program.The research program was divided into three phases:Phase I. Bench-scale testing to identify successful treatments to reclaim and restore scram tailings through evaluating surface soils amendments, viable seed mixes and plant germination, growth and densities. Phase I was completed in early 2015.Phase II. Field-scale pilot trial to test larger scale effectiveness of the treatments deemed successful in Phase I and test various vegetative assemblages and planting techniques focused on the unique challenges with scram tailing basins. Phase II was completed in late 2016 with a summary monitoring report.Phase III. Produce a technical report of results for the research undertaken in this study, as well as compile prior reclamation results used during previous Minnesota iron mining reclamation projects on tailings basin applications. Phase III was completed in 2017 with a summary monitoring report and recommendations."

Jan 2, 2018

By Randall J. Weege

Nickel laterites throughout the world are similar in their gross aspects, but vary significantly in detail. The deposits occur in two separate and distinct geologic settings --those formed over ultramafic rocks which were mechanically emplaced, and those formed over ultramafic rocks that were intruded as melts. The source of the primary nickel in the parent rock may occur both as ionic replacement in silicate lattices and as nickel sulfides. Factors controlling the degree of laterization and nickel enrichment are dependent upon the parent rock characteristics as well as chemical and climatic conditions. Two chemically and physically distinct zones (oxide and saprolite) are commonly present in the laterized rock, but one or the other may be extremely thin or absent. Cobalt and copper may be present in recoverable amounts. Geologic, geophysical and geochemical methods are all utilized in exploring for these deposits. These methods are compared, evaluated and illustrated in the paper. Drilling patterns and ore reserve calculations are also discussed. In contrast to many ore deposits, processing costs are much higher than mining costs. The most efficient processing method is directly dependent upon the chemical composition of the ore. This variation in the chemical and physical characteristics of nickel laterites requires a detailed test program of the metallurgical response to representative samples and blends of ore. Detailed laboratory and bench-scale metallurgical tests are necessary prior to a full scale pilot plant test.

Jan 1, 1978

By Mike O’Brien, Rob Croll

The Evolution of AngloGold -Incorporated in 1944 under the name of Vaal Reefs Exploration and Mining Company Limited -Name changed to AngloGold Limited in 1998 as the vehicle consolidating the gold interests of Anglo American Corporation -Diversification (geographic and orebody) through the sale of low-margin, deep level, short-life assets and the acquisition of higher margin, open-pit and shallow underground operations

Jan 1, 2003

By C. P. Mangelsdorf, Richard A. Allwes

At the request of the U.S. Department of Labor, Mine Safety and Health Administration (MSHA), the U.S. Bureau of Mines evaluated the suitability of using tri-sets for protecting mine personnel in roof-fall prone areas. A steel-set arch provided by MSHA served as a basis for evaluating the performance of the tri- set. All tests and analyses were conducted according to the arch canopy test and design procedures developed by the Bureau. Theoretical resistance functions were established for the steel-set arch and tri-set and were representative of their experimental behavior. The resistance functions were used to determine the energy absorption capacity of the structures and to predict their dynamic response to impact loading. The dynamic tests demonstrated that the arch canopy design procedure is appropriate for tri -sets and yields conservative designs for both steel-set arches and tri-sets. As a result of this work, it is recommended that tri-sets may be considered for protection against roof falls, provided that the arch canopy design procedure is utilized for each application and that the principles underlying the design procedure are understood.

Jan 1, 1992

By Bryan Ulrich

Knight Piésold?s annual roundtable discussion was held at the Red Lion Hotel and Casino in Elko, NV on March 14. This year the title was, ?Roundtable discussion on material co-disposal/ co-placement in the mining industry.? This topic was chosen because of the benefits that the mining industry could realize through the advancement of improved methods of storing tailings and mine waste and from reducing short-and long-term environmental hazards while reducing the footprint of these facilities and making strides toward attaining a walk-away solution. Knight Piésold had a local representative, Bryan Ulrich, as well as representatives from its Denver, CO office, including Tom Kerr, president of Knight Piésold?s U.S. practice, and Jeff Coffin, Ph.D., geotechnical engineer, to help facilitate the discussion. The event played host to about two dozen attendees from several western states. Attendees included personnel from more than 10 mining properties, various corporate offices and academia. The purpose of the roundtable was to exchange ideas and information pertaining to broad topics revolving around the subject of co-disposal/co-placement in the mining industry. Compared with traditional conferences and symposia, the roundtable forum tends to provide a less inhibited format for discussion. In the roundtable format, lively discussions and applicable tangential departures are encouraged. This was the seventh in the series of the Elko Roundtable events. Previous roundtables pertained to: ? Heap leach pad design, construction and operation. ? Design, construction and operation of tailings storage facilities. ? Site-wide water considerations. ? Mine closure and cover design. ? Strides toward sustainability in mining. ? High-density tailings, paste and filtered tailings. Acid rock drainage for engineers and environmental scientists.

Nov 1, 2013

By B. T. Mirabile, D. Tang, Y. Luo, S. S. Peng, C. T. Holland

Knowledge of local coal mine roof geology is critical to the design of a safe and suitable mine structure. An automated drill control and data collection system has been designed for a J.H. Fletcher twin-head roof bolter. Drilling parameters collected during the drilling process can be used to interpret geologic features intercepted in the mine roof. The drill and data collection system have been tested in both laboratory and underground settings. Visualization of certain drilling data has shown good correlation with geology drilled. A quantitative prediction model was developed using drilling parameters examined with data visualization. The quantitative model was tested using laboratory drilling data.

Jan 1, 2004

By Kevin J. Ashley

Coal is deposited at a mine site in several thin seams which outcrop in rolling hills and dip at about 8° to the northeast. The deposit is located in the northeast area of the State of New Mexico in the Southwest of the United States. A drilling program was undertaken and was quite irregular. Not all of the seams appear in all of the drill holes. Some of the holes did not go deep enough, while others were drilled below the outcrop of some seams. Occasionally a seam would pinch out and not be seen in a drill hole. Also, the outcrops of the seams are buried in many places by several feet of alluvium. All of these factors make correlation of the seams between drill holes difficult. The drawing of cross sections in three directions and at many locations across the mining area have been necessary to assure the accuracy of the input data.

Jan 1, 1982