Search Documents

By K. M. Mohamed, R. K. Zipf

The shear strength properties of generic cement foam material and cement foam/concrete interfaces were examined at three testing scales. In laboratory direct shear tests on specimens with average shearing area of 0.006 m2 (10 in.2), the cement foam material had average peak and residual shear strengths of 0.88 MPa (128 psi) and 0.39 MPa (56 psi), respectively. Depending on the concrete strength, the cement foam/concrete interfaces had peak and residual shear strengths ranging from 0.71 to 0.81 MPa (103 to 117 psi) and from 0.27 to 0.29 MPa (39 to 42 psi), respectively. In laboratory direct double shear tests on specimens with average shearing area of 0.084 m2 (130 in.2), the cement foam/concrete interfaces had average peak and residual shear strengths of 0.17 to 0.30 MPa (25 to 44 psi) and of 0.11 to 0.23 MPa (16 to 33 psi), respectively. In large shear tests of simulated cement foam seals with the Mine Roof Simulator (MRS) test frame, cement foam/concrete interfaces with shearing area of 1.486 m2 (2,304 in.2) had average shear strengths of about 0.08 and 0.16 MPa (11 and 23 psi) along the roof and floor interfaces, respectively. The average shear strength through the cement foam material was 0.38 MPa (55.3 psi). Finite element analysis of the large seal tests and the back analysis of the shear strength of full-scale cement foam seals conducted at the NIOSH Lake Lynn Laboratory confirmed shear strength of about 0.14 MPa (20 psi) along the seal/rock interfaces. The study concluded that the structural analysis of cement foam seals should be based on their residual shear strength determined from small laboratoryscale tests of the cement foam/concrete or rock interface and not be based on their peak strength.

Jan 1, 2014

By S. Rukhaiyar, M. Ramulu, G. Pradeep, P. K. Singh, P. B. Choudhury

The drill and blast method is the most prominent rock excavation method used in mining and civil engineering projects. The ground vibration is the most undesirable effect of the blasting and needs to be controlled. The blasts are designed so that ground vibration at nearby structures must remain under the prescribed limit. Various empirical blast vibration attenuation models have been presented to estimate the ground vibration for designing purposes. These models assume ground vibration as a function of distance and maximum charge per delay. United States Bureau of Mines (USBM) model is most commonly used for the blast design. However, the uncertainty associated with these models is seldom characterized, thus diminishing its reliability. The probabilistic Bayesian approach associated with the Monte Carlo method can easily quantify uncertainties associated with the model and its parameters. Thirty-three blast vibration observation data from a granite quarry in Kerala, India, is used to estimate the probability distribution of model parameters. Markov Chain Monte Carlo (MCMC) approach is used for sampling 12,000 samples for obtaining the posterior distribution of parameters. The uncertainty associated with model parameters is quantified from the posterior distribution, and this is further used to estimate the credible and prediction limits of the model. The point estimate of the most optimum value of the parameter is estimated using maximum-aposteriori or MAP estimate. The model parameters are also obtained using the commonly used least-square error method, which is a maximum likelihood estimation or MLE approach. It has been observed that the accuracy of the model obtained using both MAP and MLE approach is almost equal. However, the MAP estimate as per Bayesian probabilistic analysis has the added advantage that it can estimate the uncertainty of parameters as well as the model, which is not possible using the MLE approach.

Sep 27, 2021

By Shangyong Lin, Wei Sun, Weiping Liu, Muhammad Azam, Junfeng Chen, Yujie Zhao, David Asubonteng, Michael Ngoie

Copper concentrates are widely used in smelting operations worldwide and typically consist of chalcopyrite ( CuFeS2) as the primary mineral, with chalcocite ( Cu2S) and bornite ( Cu5FeS4) as secondary copper-bearing minerals. However, these concentrates often contain hazardous impurities, such as the fluorine ion, which can result in various complications during the smelting process. These issues include equipment corrosion, gas treatment requirements, environmental hazards, and strained community relations. Furthermore, high fluorine content in copper concentrates can lead to penalties and limitations during sales. To address these challenges, this comprehensive review assesses current techniques for removing fluorine from copper concentrate. Drawing upon recent research and the findings in the field, the review analyzes the advantages and disadvantages of existing fluorine removal methods and identifies critical issues requiring attention in the future. This review provides valuable insights into the current state of fluorine removal from copper concentrates and serves as a practical guide for researchers and industry professionals in this field.

Aug 2, 2023

By B. J. Arnold

Utility coal specifications usually contain a requirement for a maximum moisture content in order to prevent coal handling problems and to minimize evaporative losses in the boiler. As most coal cleaning processes are water-based, dewatering and sometimes drying steps are required to meet moisture specifications. Screens are often used for dewatering, with centrifuges and filters used to further reduce moisture in many cases. Algorithms to predict the performance of screens were developed for the Coal Cleaning Simulator running under Aspen Plus during a project sponsored by the U.S. Department of Energy and the Electric Power Research Institute. These algorithms include calculations for the size separation and a calculation for moisture content of the oversize product based on particle size and specific gravity distribution. This paper discusses the algorithm for predicting the moisture content of coal dewatered by screens.

Jan 1, 1997

By R. Benito

This paper describes the development of a life-of-mine schedule (LOM) for one of the world's largest known sedimentary copper-cobalt districts located in the Katanga Province, Democratic Republic of Congo (DRC). A particular feature of the Tenke Fungurume LOM schedule is the considerable number of pits/phases for scheduling, each competing to provide the best ore available to a capacity-constrained process facility. This paper discusses the LOM scheduling objectives and constraints, data preprocessing steps such as ore binning, block aggregation and clustering analysis as a scheduling aid, the mine scheduling approach and results and conclusions. Mining Engineering, 2011, Vol. 63, No. 8, pp. 39-47. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Louis A. Panek

Using an approach based on the theory of similitude, the author develops a general equation and related concepts that provide new insights to an old problem. The load-bearing capacity (strength) of a square, rectangular, or cylindrical prism of a brittle material such as rock, coal, or concrete is expressed as the mathematical product of a size effect, a shape effect, and a function of the mechanical properties (deformability, cleat/joint spacing, and friction) of the pillar, roof and floor materials. Through an application of multivariate statistical analysis, the results of assorted tests and observations of failed pillars can be combined into a fundamental scaling equation, which provides a unified, consistent approach to the estimation of mine pillar strength. The form of the equation is sufficiently general to be able to incorporate refinements in the characterization of the basis factors, as they become available through future experimentation and analysis.

Jan 1, 1979

By Thomas F. Connors

The end of an era is here. The pony-express era of industrial relations in the coal industry is ending. Those professionals who know it must end to insure the industry's future are happy, relieved, but somewhat saddened. They are sad because it did have its elements of suspense, thrills, frustrations, and at times, plain fun. The days of the Company town are ended; the wildcats are declining; violence (while a big part of today's industrial relations) is beginning-to decline. The spirit of sound industrial relations is beginning to take hold. This has to happen for the industry to compete in today's economy and it is causing major changes for those who have grown accustomed to the pony-express type industrial relations.

Jan 1, 1981

By MUSTAFA ERKAYAOGLU, Muhammet Mustafa Kahraman

Particulate matter (PM) is one of the main actors related to air pollution caused by surface mining. Fugitive dust, considered as particulate matter that cannot be collected by conventional measures, is classified by the particle size. The Environmental Protection Agency (EPA) categorizes PM as coarse and fine particles based on the particle size being less than 10 μm (PM10) and less than 2.5 μm (PM2.5). Basic operations of surface mining such as drilling and blasting, loading, haulage, and processing are processes that can potentially generate fugitive dust. Regulations and legislations enforce the mining industry to use environmental monitoring systems, fugitive dust level measured by PM10 level as part of this. Air quality monitors are positioned at different locations around surface coal mines and track air quality levels during production. This study introduces a data-driven methodology to handle air quality issues related to fugitive dust at surface coal mines. Data is sourced from different mine equipment in real-time and they are integrated with air quality monitoring systems to provide information to support decisions for fugitive dust. The method is implemented and demonstrated in a case study at a large surface coal mine.

Sep 29, 2020

By A. D. Hammond

Vanadium is a transition metal, ductile and silver-gray. It is harder than most metals and steels and it has a good resistance to corrosion. It is stable against alkalis and sulfuric and hydrochloric acids. Vanadium is oxidized in air at about 660° C (1,220° F), although an oxide layer forms even at room temperature. The chemistry of vanadium is noteworthy for the accessibility of the four adjacent oxidation states, 2-5. In aqueous solution, the colors are lilac V2+, green V3+, blue VO2+ and, at high pH, yellow VO42-. Considered to be as abundant as zinc, metallic vanadium is not found in nature, but it is known to exist in about 65 different minerals. Economically significant examples include patronite (VS4), vanadinite (Pb5(VO4)3Cl), associated to the uranium mineral carnotite (K2(UO2)2(VO4)2?3H2O) and in a vanadium mica called roscoelite K(V3+,Al,Mg)[(Si,Al)4O10] (OH)2. Other important vanadium ore oxides are montroseite (V,Fe)O(OH) and corvusite (Na,Ca,K)V8O2.4H2O. Much of the world?s vanadium mine production comes from magnetite-hosted deposits and, to a lesser extent, sedimentary-hosted sandstone.

Dec 1, 2013

By Jonathan Baggett, Nino Ripepi, Amin Abbasi, Richard Bishop, Juan Monsalve, John Hole

This work focuses on the operational and safety issues associated with karst voids in large opening underground mines. Issues include water inrush, structural instability, and engineering uncertainty in these environments. Coupled with the fracturing prevalent in folded sedimentary rocks, karst voids are complex and challenging ground-control risks. Traditional methods of predicting karst void locations, such as probe drilling, are impeded by the inconsistent spatial distribution and variable sizes of the features as reported by Li et al. (J Rock Mechan Geotech Eng:232–242, 2010) and Hassan et al. (Procedia Chem 19:737–742, 2016). Ground-penetrating radar (GPR) is a geophysical technique that transmits radio waves into a medium and subsequently detects reflected waves via a receiver. The travel time and energy of received signals are then processed and interpreted. The difference in conductivity and dielectric permittivity between limestone and open karst cavities causes strong reflections. GPR is frequently used as a geophysical surveying technique in several industries; however, there is a lack of published research on underground mining GPR applications as reported by Zhao et al. (2015a; Geophys J Int:62–71, 2015b) and Eskelinen and Pellinen (Constr Build Mater:888–898, 2018). The purpose of this work is to demonstrate the use of GPR in an underground stone mine and to discuss the importance of karst void detection ahead of mining.

By L. Alagha, M. Khodakarami

"This work focuses on the extraction of rare earth metals (REE) from aqueous solutions using stimuli-responsive polymers. Various parameters affecting the adsorption capacity of the polymer, including pH, polymer concentration and REE concentration were studied. The interfacial behavior of REE in aqueous phase before and after polymer addition and the mechanism of the formation of metal-polymer complexes and their properties were investigated using UV/VIS spectroscopy. Results obtained would help to test the feasibility of employing stimuli responsive polymers in pre-concentration of rare earth elements associated with other elements in mineral aqueous streams prior to solvent extraction. The pre-concentration step would reduce the amount of organic solvents used for extraction and striping compared to conventional extraction processes. INTRODUCTION Rare earth elements (REEs) have become the foundation for several technologies and have been used extensively in many industries such as modern electronics, green energy, health care and transportation and defense [1-4]. As these industry sectors are growing, the global consumption of REEs is going to increase dramatically. The current global REEs demand is estimated to be 105,000 tons of rare earth oxides per annum with an expected annual growth of 5.6% [5-6]. Rare earth elements are produced from different sources (primary and secondary). China is considered as the largest producer of REE in the world, providing about 90% of the world’s mine production while the United States is second with 4% of the mine production [7]. High global demand for rare earth materials results in shortage of such materials in the near future. It should be considered that the term ‘‘rare’’ earth is not an accurate term, since they are abundant in some extent in the Earth’s crust, but are typically finely dispersed. Thus, nowadays looking for more efficient and cheaper methods for extraction, separation and purification of low concentrated REE ores and exploring secondary sources are essential. Rare earth materials are found in raw condition and require treatment that involves several processes, which can consume money and time. Recent improvements in extraction and recycling technology have made the extraction of rare earth elements from rare earth sources more feasible in terms of cost and time [8-10]. Physical and pyrometallurgical methods require high-energy and thus high costs. Moreover, due to environmental problems, environmental protection systems are required, and they are not as adaptable as chemical processes [11, 12]."

Jan 1, 2016

By M. J. Gula, S. S. Xue, E. P. Horwitz

A study has been conducted to remove iron from sulfate solutions using Eichrom's Dipexo® extractant, P,P'-di(2ethylhexyl) methanediphosponic acid (H2DEH[MDP]). It is found that this extractant can effectively and selectively extract ferric ion from highly acidic solutions. Ninety-nine percent of the iron was extracted from a simulated feed solution in a single stage. The separation factor, Fe/Zn, was 106. Over 90% of the iron in a loaded organic can be recovered in an aqueous solution by reductive stripping. This paper presents the experimental results. A new process for iron removal using Dipex extractant is described and discussed.

Jan 1, 1999

By Donald O. Rausch, William E. Hawkes, Odin Jr. Strandberg

INTRODUCTION Kennecott Copper Corp.'s Tintic Div. Burgin mine is a 725 t/d (800 stpd) lead-zinc producer, located in the east Tintic mining district, 5.6 km (3.5 miles) east of Eureka, and 130 km (80 miles) south of Salt Lake City, UT. The Burgin mining complex includes three shafts, shop, dry, and office facilities, and a 454 t/d (500 stpd) flotation concentrator. Production and ser¬vice entry to the mine is through a 4.26-m (14-ft) diam concrete-lined production shaft, and a three-compart¬ment rectangular shaft. A connection with the Apex No. 2 shaft and the Burgin mine provides a second exhaust airway. Bear Creek Mining Co., Kennecott's exploration sub¬sidiary, began exploration of the Burgin mine area in 1957 with the sinking of the 335 m (1100 ft) deep No. 1 shaft. A station was cut at the 320-m (1050-ft) level of the shaft and extensive drifting, diamond drilling, and some winzing and raising confirmed the presence of a major lead-zinc ore body, the main portion of which oc¬curred below a hot saline water table. Surface facilities and the 4.26-m (14-ft) diam concrete-lined production shaft were completed in 1966. Ore production has been steadily increased to 725 t/ d (800 stpd) since 1966. The collar elevation of the No. 2 production shaft is 1731 m (5678 ft) above sea level. The mine's three levels, the 1050, 1200, and 1300 are at elevations of 1414.6, 1356.4, and 1338.1 m (4587, 4450, and 4390 ft), respectively. The approximate elevation of the hot saline water table is 1382.6 m (4536 ft). The earliest production on the east Tintic mining district was from the Eureka Lilly mine in 1909. Later, in 1916, the Tintic Standard mine was discovered, and pro¬duced ores with a gross value of $80,000,000 through 1956. The Eureka Standard mine located 1.6 km (1 mile) southwest of the Burgin mine produced ore worth $12,000,000 from fissures in the Tintic quartzite along the Eureka Standard fault. Ores produced from the east Tintic mining district through 1971 are valued at $151.3 million. The production from the entire Tintic district is approximately $500 million. GEOLOGY The Burgin ore deposit occurs as replacement bodies in limestone, dolomite, and shale. Numerous fault struc¬tures and rock formations make the mine geology com¬plex. The mineralization is strongly associated with sev¬eral major geological features, which include the Ophir formation, consisting of limestone, dolomite, and shale as the favorable host rock, and the structural influence of the east Tintic thrust, the Eureka Standard and sev¬eral other significant faults. Fig. 1 depicts the Burgin 1300 level workings, a generalized configuration of the ore body, and the main geological features. Covering the quartzite, limestone, dolomite, and shale facies enclosing the Burgin ore deposit are 183 to 274 m (600 to 900 ft) of andesite. The Burgin ore consists of massive sulfide and oxide lead-zinc ores with significant silver and cadmium val¬ues. The main ore minerals are galena, cerrusite, and spalerite. Extensive manganese oxide deposits are associated with the lead-zinc ore occurrence. A limited

Jan 1, 1982

A methodology has been developed and demonstrated to be effective in reclaiming surface-mined land for a forestry post-mining land use. The forestry reclamation approach (FRA) has been applied, almost exclusively, to flat or gently rolling surfaces. One of the primary steps in the FRA is to loosely grade the top 1.22 m (4 ft) of soil or substitute root growth medium to avoid excessive compaction. Concern has been expressed by regulators and the public that loose grading on steep slopes (i.e., greater than 23°) could lead to slope failures, which is one of the issues that the Surface Mining Control and Reclamation Act of 1977 (SMCRA) sought to correct. A field investigation was conducted at a steep-slope contour operation in eastern Kentucky to test the applicability of FRA in this setting. Final grading was performed according to FRA standards. The surface consisted of two distinct substitute rooting media. One was unweathered gray sandstone and the other was a combination of gray sandstone, brown sandstone, and topsoil. A variety of native hardwoods was planted following the FRA guidelines. The slope was instrumented with 70 survey monuments to monitor for mass movement. The reclaimed spoil was also characterized using bulk density and penetrometer resistance methods. The characteristics of both spoils are similar to those observed on flat to rolling surfaces where the FRA has been used and, after one year, approximately 70% of the trees had survived. During this first phase of investigation, there has been no major mass movement of the slope and slope stability analysis indicates that the application of the FRA has little impact on the overall stability of the slope. Mining Engineering, 2011, Vol. 63, No. 12, pp. 55-62. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011

By Arthur W. T. Grimley

Hydraulic coal mining is being successfully practiced in China, U.S.S.R., Japan and Canada and in each country, excepting Japan where suitable sites are not available, the system is being expanded to either existing conventional mines or new mines. Productivity levels and economics at these mines are in all cases better than the productivities achieved in conventional mines in the same general localities. In the U.S.S.R. face productivities approaching 50 tons per man shift have been reported while in Canada the latest statistics show average face area productivity levels are in the region of 200 tons per man shift production monitor. In the United States hydraulic mining has not been actively pursued to the same degree and consequently there are no full scale hydraulic coal mines in operation or construction. Because many of the coal measures in the Western U.S.A. are generally somewhat similar to those being successfully hydraulic mined in Western Canada and parts of Siberia it is realistic to believe that successful hydraulic mines can be designed and developed in the Western U.S.A. Particularly if the vast technological base that already exists is used to improve on other people's ideas, systems, methods and equipment.

Jan 1, 1983

By Daniel F. Meyer

INTRODUCTION The Metropolitan Boston Transit Authority (MIA) Red Line has served greater Boston commuter needs from its Harvard Square terminus since its opening in 1912. Since then, the population of Boston's northwest area has increased substantially, and with this growth have come dramatic changes in the type and distribution of urban land uses, including the number of households, jobs, shopping and recreational opportunities; these changes have created a need for improved transportation. Extension of the Red Line to better serve these communities has been a topic of discussion for nearly 40 years. In November of 1977, the Urban Mass Transportation Administration (UMTA) granted the MBTA approval and funding for the Red Line Extension Project. With funding in place, the MBTA proceeded with final engineering and construction of the section from Harvard Square to Alewife. When completed, the Red Line Extension will add 3.2 miles of new track to the MBTA system. Estimated final cost is about $400 million. On October 3, 1978, the MBTA received bids for the construction of Project 091-105, Harvard Square to Porter Square Tunnels and Shafts, which is part of the overall Red Line Extension. The Joint Venture of Morrison-Knudsen, White, Mergentime was the low bidder at $47,478,600. Official award of the contract came on October 25, 1978, with Notice to Proceed given October 31, 1978. The contract called for construction of two independent parallel concrete-lined tunnels in rock, soft-ground and mixed-face

Jan 1, 1983

By A. L. Mular

A great deal of effort is being expended by mineral processing engineers to acquire a basic knowledge of modelling and optimization techniques. Stimuli such as immediate process improvement, expanded process understanding, optimal flowsheet design and re-design, and the development of new and better control systems are goals which excite the imagination in terms of increased profits. To reach these goals, process models and efficient optimization strategies, regardless of their purpose, assume an important role. Consequently, few of us can argue that such efforts are of no value. The purpose of this paper is to review empirical modelling methods and optimization strategies which appear to be of value to mineral engineers.

Jan 1, 1972

By D. Van Orden, Y. Kamiya, R. Lee, E. Ilgren

Crocidolite is a well-known causative agent for mesothelioma. However, 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 although this has never been formally confirmed. To date, crocidolite appears to be the only asbestos mineral for which an epidemiological study comparing the risk of mesothelioma in a population exposed to ‘thin’ fibers with another exposed to ‘thick’ fibers of the same species may be carried out. Finnish anthophyllite, South African amosite, and African Transvaal crocidolite can also be classified as thick fibers, and there is a paucity of mesotheliomas in populations exposed to them compared to those exposed to thin Cape crocidolite. No thin occurrences of these minerals are known. Our previous study looked at crocidolite from several sources. The present study considers the amphibole anthophyllite found in many places in the world. This mineral, regardless of source, does not show the same variation in fiber width found with crocidolite from different areas. All anthophyllite fibers that have been mined may be classified as thick and populations exposed show very low levels of mesothelioma. We suggest the most likely explanation is related to the fiber width distribution and a concomitant reduction in the ‘Stanton fiber size’ fraction.

Jan 1, 2012

By Morgan M. Sears, Gamal Rashed, Michael M. Murphy, Brent Slaker

In this study, a parametric study was conducted using FLAC3D numerical models to examine the impact of oblique loading, generated from seam dip, on the strength and the failure propagation pattern of a stone pillar using two simplified geometry types. In type 1, the sidewalls of the pillars were assumed to be perpendicular to the roof and the floor, while in type 2, the sidewalls of pillars were assumed to be vertical. The complex pillar geometry in dipping mines was frequently modeled using these two geometries. To capture a complete picture of the effect of seam dip on pillar stability, the modeled width-to-height (W/H) ratio of the pillars, in situ stress field, and pillars roof/floor interfaces were systematically varied to account for the potential distribution of values for these parameters across the underground stone mines in USA. Results from the numerical modeling indicate that dipping pillars have reduced strength compared with horizontal pillars. Also, an asymmetric failure propagation pattern could be obtained depending on an interaction between the W/H ratio, seam dip, in situ stresses, and pillar geometry.

Feb 5, 2021

By Jackson M. Langton

INTRODUCTION The Morenci-Metcalf district is located on the southern slope of the white Mountains in Greenlee County, Arizona. Both porphyry copper deposits are four to six miles northwest of Clifton, the county seat, and the new Metcalf mine is situated approximately one mile northeast of the Morenci open pit (Figure 1). Chase Creek, a south-flowing tributary of the San Francisco River, dissects the district and separates the two ore bodies. More than 1,200 exploration and development drill holes have been completed in the district and the Morenci-Metcalf ore bodies have been delineated on a 400-foot grid. Recently initiated drilling programs have revealed new data about deeper protore and associated hypogene alteration. This information, correlated with surface mapping and petrographic studies, was utilized to propose a plausible geochronologic sequence for this region. The reasoning behind this study has been helpful in locating new ore beneath leached capping indicative of only protore mineralization. The scope of this paper is to establish a practical solution to a highly theoretical problem of ore genesis and to familiarize the reader with stratigraphic, structural, and mineralogic events responsible for localizing ore in this district. Continued research will possibly alter the proposed time span and relative displacements, but it is doubtful that the order of events will vary significantly. Geochronologic conclusions are therefore presented as general hypotheses and additional geologic mapping,

Jan 1, 1972