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By S. C. Sun

A process was developed to recover coal, clays and pyrite from coal wastes. The process consists of fine grinding followed by coal flotation and pyrite flotation leaving the clays in the flotation pulp. A bituminous coal refuse, containing l0% S-30% C*, was treated by this method to yield a coal product containing 4% sulfur, 10% ash; a pyrite product containing 45% sulfur (84% FeS2), 1% carbonaceous material and a clay product containing 2% sulfur (3.5% FeS2). The coal yield was about 89%. The pyrite yield was about 77%. The process steps may be entirely flotation, or gravity separation (hydrocyclone) may be used to increase the pyrite: coal ratio in the flotation feed. Cost estimation shows a profit of $2.28 per ton of low pyrite grade refuse (Labor, maintenance, overhead and plant depreciation were not included). The development of this process consisted of three parts: 1) exploratory tests, 2) optimization tests and 3) confirmatory tests.

Jan 1, 1968

By W. M. Luff

The Brunswick No. 12 Deposit is a large polymetallic massive sulphide deposit, occurring in Ordovician age rocks of the Tetagouche Group. Silver is contained within the sulphide zones and economically it is the second most important commodity produced. Brunswick is one of the largest silver producers in Canada. The distribution of silver within the mine is presented, with examples from various levels. The concentration of silver can be shown to be related to both stratigraphy and structure. The mineralogy of silver in mill products is also presented.

Jan 1, 1986

By Ping Zhang, Shahram Mozaffari, Andreas Ylmefors

The risk associated with mining induced seismicity and the related rock bursts has become one of the major threats to the safety and sustainability of mining at the Kiirunavaara mine. The causes of mining induced seismicity at the Kiirunavaara mine are very complex and have affected our understanding on the source mechanisms of seismicity and further the mitigation of the seismic risk. Detailed analysis of historical mining induced seismicity at the Kiirunavaara mine was conducted. The focus of this analysis was placed on the classification of large seismic events and the evaluation of the influential factors on the classified seismic events. 145 events with local magnitude larger than 1.5 that occurred between January 1, 2011 and March 31, 2021 were analyzed. For this analysis, seismic events located in the hanging wall were not included, as these have not been observed to cause large damages to the mine itself. It was found that the magnitude of the events had good correlation with the stress change in relation to the production location. The seismic events were classified as mining-front associated, ore-pass associated, mining-front and ore-pass associated and others, according to their hypocenter location. Most of the mining-front associated events, concentrated around the production levels and slightly above and below them, generally correlated with shear cracks, and most of them occurred when the ore flow between two production levels started. The numerical modelling showed that slip of the geological discontinuity, due to unclamping between hanging wall and footwall, could be the major causative mechanisms, which further supports this finding. The ore-pass associated events are located close to the ore passes. Large seismic events located between ore passes have the source mechanism of both fault-slip and non-shear, but events located at the outer side of ore passes were all fault-slip type. By checking with the ore pass scanning data, it was concluded that the most of the events located between ore passes could be pillar bursts. An elastic core concept has been then used to define a critical pillar width. The paper is not intended to be prescriptive but rather to initiate discussion of the possible classification of seismic events at the Kiirunavaara mine and to present new perspectives of the causes of the seismicity for improving the present seismic risk management.

Apr 26, 2022

By E. Siami-Irdemoosa, S. R. Dindarloo

"Discrete event simulation is a stochastic mathematical modeling tool with applications in queuing systems. Many mining operations, both surface and underground, can be simulated in the context of queuing theory , for example open pit loading and haulage operation, underground level and vertical transportation, and mineral processing circuits. A computer simulation model of the operation is an invaluable tool to study both the system’s dynamics and conducting sensitivity analysis on different effective elements on system performance. In this paper, merits of discrete event simulation in decision making in mining engineering is discussed. Moreover, a stochastic simulation framework for selection and sizing of shovels and dump trucks in surface mining is presented to elaborate one example for applicability of the method in mining operations. INTRODUCTION Mathematical modeling is a valuable tool in design, optimization, and decision making in both surface and underground mining operations. Several researchers have tried to study different aspects of mining operations using a wide range of mathematical techniques such as linear programming[1], analytical hierarchy process [2], non-linear programming[3], genetic algorithms[4-5] ,mixed integer programming [6], machine repair model[7], queuing theory [8], and conventional spreadsheet calculations based on experience and engineering judgments. There are different uncertainties in typical mining operations (e.g. material loading and haulage, drilling, and blasting). For example, in a truck-shovel operation, different governing activities such as loading, haulage, and dumping cycles are stochastic variables. Moreover, analytical modeling of a large truck-shovel operation is very complicated. Thus, application of analytical and/or deterministic techniques cannot guarantee a solution for different problems that are encountered in daily mining operations. Discrete-event system simulation (DES) is a modeling method for such time discrete and probabilistic phenomena [9]. DES has been employed by different researchers in mining engineering through available software and languages such as GPSS, SIMAN- ARENA, and SLAM [10-14]. Most of the studies so far, tried to evaluate some “what-if” scenarios, to understand the possible effects of changing different input variables on overall mine economics. For instance, Baffi and Ataeepur (1996) used Arena to simulate a truck-shovel operation [10]. Also, Sturgul has conducted extensive studies in the application of DES in the mining engineering field [15- 17]. A very good background review of application of this technique in the industry can be found in [15-16]. Previous studies have shown that, different approaches including deterministic, stochastic, and experimental methodologies result in considerable differences in outputs [18]. These techniques lead to different solutions, regardless of the quality of technique/software itself or knowledge of the modeling team. Hence, the first step is to develop a comprehensive simulation framework to obtain nearly the same optimal results for the same input variables, regardless of the employed technique."

Jan 1, 2016

By Hasan Ali Taner, Vildan Onen

One of the problems in flotation is mechanical entrainment and the other is the presence of complex gangues (especially clay minerals). In the present study, it was aimed to determine the effects of clay types (kaolinite, illite, and montmorillonite) on mechanical entrainment parameters (total flotation recovery, real recovery, mechanical entrainment recovery, and water recovery). Effects of clay types and clay amount on chalcopyrite flotation were investigated by flotation experiments. Interaction mechanisms between the clay minerals and ore were characterized using SEM–EDS analyses. Experiments were carried out with and without a collector using the mixture of clay minerals and ore under certain experimental conditions. While the clay mineral most affecting the chalcopyrite grade was montmorillonite, the highest mechanical entrainment recovery and the lowest real recovery values were obtained in the presence of illite. While illite is stated as the least problematic clay mineral in the literature, it was determined that illite among three clay minerals used in this study caused significant mechanical entrainment. In contrast, it was determined that increasing the amount of kaolinite did not have a significant effect on mechanical entrainment. This study’s findings will guide in determining of clay minerals’ effect on gangue entrainment in flotation.

Dec 29, 2023

By Charles W. Daugherty

INTRODUCTION The Washington Metropolitan Area Transit Authority's (WMATA's) rapid transit system, Metro, ultimately will comprise 162.5 km (101 miles) of line divided among 10 routes. As shown in Figure 1, about 24 km (15 miles) of the system will consist of mined rock tunnels distributed along the A, B, C and K Routes. The structural construction contracts for all of the A, C and K Route rock tunnels are complete and trains are running in about one-third of them. A contract for construction of rock tunnel section B-9, the southernmost third of the B Route, was awarded on June 27, 1980. The final design of Sections B-10 and B-lla, the remainder of the rock tunnel portions of the B Route and the Metro system, are well advanced and should be under con¬struction by 1982. Of Metro's 87 stations, 11 will have been constructed by mining in solid rock, a not inconsiderable achievement, since each structure must be over 183 m (600 feet) long, wide enough to accommodate two trains and one or two passenger platforms, and high enough to achieve a stable arching action without encumbering columns. With the passage of years, some original priorities have been reordered, and ways have been sought to streamline and simplify this most complex of Metro structures without grossly violating the architectural standards that make it unique. This paper will summarize that search, and describe the design and construction aspects of the resulting product, the dual chamber rock tunnel station.

Jan 1, 1981

By B. K. Mishra

The motion of the charge inside a grinding mill is of considerable practical importance. The dynamics of grinding mills have been the subject of study by a number of workers because it can accurately predict: i) the power drawn by the mill, ii) the distribution of forces inside the mill, and hence the wear rate of balls as well as the liners, and iii) mass transport of milled product through the porous ball charge. Some of the earlier analyses of the motion of a charge of particulate material in a tumbling mill were reported by White (1904), Davis (1919), and Dyer (1945) and have been reviewed by Rose and Sullivan (1958). In these works, frictional force at the wall of the mill and between the colliding balls, and the interaction of different ball trajectories, was not considered. Moreover, it was assumed that the profile of the tumbling charge is independent of the degree of filling, which is generally not true. However, all this work led to the identification of so-called "equilibrium surface" which is the plane that separates the rotating charge into two regions. The inner region is static; here there is no motion relative to the mill shell. The other region is a shear region where either the balls flow down the surface of the charge (cascading motion), or are projected out of the surface and follow approximately parabolic paths (cataracting motion).

Jan 1, 1990

By William S. Alldredge

The Washington Metropolitan Area Transit Authority(WMATA) officially came into existence in February 1967 after the District of Columbia, Maryland, and Virginia joined in a com¬pact pursuant to Federal creative legislation signed the previous November to build a regional rapid rail transit system called METRO (1). The parent organization was the National Capital Transportation Agency (NCTA), a Federal agency, subject to Federal statutes and regulations. Soon after the completion of the transition from NCTA to the new "non-Federal" status of the Authority, the Board of Directors of the Authority formally adopted procurement policies and procedures (2). These are specific statements concerning competition by formal advertising for bids or by solicitation of proposals for negotiation, contracting authority, approval of awards, awards of contract modifications, and processing of claims and disputes. These policies and procedures are silent as to Federal procurement statutes and regulations. But because of the Authority's origin, the sensitive nature of the compact among the several sovereign jurisdictions, Federal financing of two-thirds of the costs, and the resultant surveillance by the General Accounting Office over staff operations, the Authority's procurement practices follow closely Federal regulations adapted to WMATA's needs. This is an important point and is the foundation of contractual relations between the Authority as the owner and its construction contractors. Various constraints and flexibilities of this arrangement with respect to excavation and tunneling contracts will be pointed out in the ensuing discussions.

Jan 1, 1974

By Lawrence K. Nordell

The selection of belt conveyor drive systems (*) is the subject of ongoing investigation. Frequently this choice has been governed by an incomplete perspective on the major considerations. A more comprehensive and objective approach is desirable. This paper presents additional factors which hopefully will broaden this perspective. BACKGROUND Conventional belt conveyors are powered by electric or electro-mechanical drives(*) mounted at the conveyor's head, tail, intermediate return span, or a combination of these (Fig. 1). A list of the drives reviewed is given in Table I. The following are main elements influencing the selection of the drive system: 1) dynamic characteristics, 2) economic factors such as capital cost, plant spares compatibility, reliability, availability, maintainability, and 3) environmental constraints. The principal dynamic characteristics of concern are the reactions of belt forces generated by the drive system during starting of the conveyor. Another attribute for consideration is the application of multiple driven pulleys used to 1) lower the conveyor's belt tension requirements, 2) increase the expected tonnage throughput, allowing for possible drive component failures, and 3) increase the plant spares flexibility related to the drive assembly.

Jan 1, 1977

By Michael A. Werner

"A Yieldable Structure for Use in Areas of High Rock Stress & Deformation." Rock stress of up to 9000 psi have been recorded in the mines of the Coeur d'Alene Mining district. Associated with these large stresses are rock fractures and deformation. In order to maintain openings required for mining, large wood preparation structures are constructed to provide access to the work areas for men and materials. These wood raise preparation structures are costly to construct and maintain. Therefore a steel-foam concrete structure was designed and proposed for testing which would be less costly to construct, require no maintainence and maintain its structural integrity while allowing up to 53 inches of wall rock deformation.

Jan 1, 1984

By P. L. Sibrell

Three different refractory carbonaceous gold ores from the Carlin operation in northeastern Nevada were investigated to characterize the effect of passivation treatments on the nature of the carbonaceous material. The carbonaceous material was chemically isolated from the ores and passivated residues, and examined by FTIR spectroscopy, elemental analysis, and gold adsorption capacity. The main component of the carbonaceous material in these ores was found to be a naturally occurring activated carbon-type compound. Hydro-carbons were detected on rare occasions, but no evidence was seen for humic acids. Ore samples were passivated by autoclaving, or by treatment with sodium hypochlorite or gaseous Chlorine. In some of the passivation tests, a new peak was observed in the IR spectra of the isolated carbonaceous material, that was due to carbonyl functionalities. However, all of the passivation treatments tested decreased preg robbing significantly. This suggested that the appearance of the carbonyl peak was due to the severity of the conditions during passivation, rather than the method used.

Jan 1, 1990

By W. L. Price

Recent publication of United States Bureau of Mines figures showed that the sand and gravel (3) industry is the largest single mining industry in the United States in term of yearly tonnage produced. The yearly production of over 500,000,000 tons per year now exceed bituminous coal production. This disclosure caught unawares many observers who have not been following closely the rapid-growth of this phase of mining. Along with this steady growth in production, the sand and gravel industry has gone through an accelerated and varied program of beneficiation in a period of the last ten years.

Jan 1, 1958

By R. Eggert

Since the discovery of high temperature superconductors has led to extensive interest and conjecture regarding their potential to change contemporary technology, discussions of the impact on the metallurgical and other industries have naturally arisen. In this paper we present data showing the possible impact of these developments on the materials related to the fabrication and proliferation of devices based on superconductor materials. We observe that the largest volume of effort with LTSC will be for the demonstration of high power devices while applied research relating to processing will remain the principal HTSC activity. We also note that in the next decade copper consumption in the US is expected to remain essentially at the current level while the need for Nb and Sn,; two major components of LTSC, will grow at a faster rate both in the US and the world. Although the use of superconductor-based magnetic separation is anticipated to increase, no major impact of these components on the metallurgical industries is expected.

Jan 1, 1990

By Margreth Tadie, Chalwe Chibwe

Physicochemical properties of copper electrolytes are a strong fundamental consideration in electrodeposition processes during electro-purification and recovery of copper. Their influence extends to mass transfer as well as energy consumption during the electrodeposition process. In this study, the influence of electrolyte composition on electrolyte physicochemical properties was investigated to review the existing literature data. This review of data is considered necessary as more and more electrowinning models are being developed for process prediction and optimisation and a need of such data is required for accurate prediction of physicochemical properties. The major components of importance to the formation of smooth high-quality and high-purity copper cathodes at optimum current efficiency are considered the species in solution. These include Cu ions, Fe ions (major impurity), H2SO4, and a smoothing agent additive. A 5-factor, 2- and 3-level experimental design was employed to determine the effect of copper (35 and 45 g/l), sulphuric acid (160 and 180 g/l), iron (1, 3, and 6 g/l), polyacrylamide additive (2, 5, and 10 mg/ l), and temperature (45 and 55 °C) on electrolyte density, conductivity, and the diffusion coefficient in synthetic copper electrowinning electrolytes. The major species in a copper electrowinning electrolyte are found to be the most relevant for prediction of physicochemical properties. These results indicate that relatively simple empirical models are sufficient for modelling of the electrolyte domain in electrowinning, without the need for the generation of vast amounts of complex experimental data.

Feb 1, 2021

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 J. O. Marsden, J. H. Gourdie, J. R. Arnold, J. G. Mansanti

During the testing and design of the Gold Fields' Chimney Creek mine, it was found that a much higher carbon loading was possible with CIC (carbon-in-solution columns) than with CIP (carbon-in-pulp). In an effort to keep the carbon handling minimized, an emphasis was put on forcing gold to the CIC circuit rather than the CIP. After considerable study, it was found that a circuit with two thickeners and an interstage leach would force 90% of the gold to CIC. Computer modelling indicates that the benefits of the hybrid circuit include higher recovery, less carbon handling, fewer leach tanks, and lower reagent costs.

Jan 1, 1990

By M. Rieber

The potential for the wide-spread commercialization of superconductivity, the disappearance of all resistance to a direct current (D.C.) electric flow, began in 1986-87 with the development by Bednorz and Muller at IBM's Zurich Laboratory of an yttrium -barium -copper oxide conductor which attained zero resistance at 90t:. Although the status of superconductivity is still pre-bench scale, it is useful to forecast its probable effects on the copper industry. I t should not be forgotten that at their inception, the impacts of transistors, semi-conductors, thin films and fiber optics on the electric/electronics sector of this industry, were largely underestimated. Superconductors are not metals, but a class of ceramics. They represent an efficiency increase of one or more orders of magnitude. If their development is to be a boon to the copper industry, rather than a reduction of metal demand through miniaturization or material substitution, vastly expanded copper containing electrical uses must be in prospect. In this paper the projected uses of high temperature superconductivity are examined, followed by the remaining problems to be overcome. Assuming success, a time horizon for maturation is estimated. The penalties for the non-recognition of new markets and material substitution are shown on the basis of past forecasts. Finally, the application of successful superconductivity to the copper industry over the forecast period is estimated.

Jan 1, 1990

By Jack G. Crump

Nuclear radiation systems for gauging solids content in process slurries and level in crushers has demonstrated acceptance in ore processing. The use of nuclear radiation for moisture analysis of bulk materials is presently receiving acceptance in beneficiating and agglomerating processes. On the horizon is the use of nuclear activation methods for continuous, qualatative and quantitative analysis of concentrate. The common characteristics of these uses of radiation is the non-contacting nature of the measurement. Unquestionably, this is the dominant reason for acceptance of nuclear methods in level and slurry-gauging. Moisture activation analysis of a product using nuclear methods retain this advantage. However, and: more importantly, they offer new solutions to old problems. The nuclear method in addition to being non-contacting, is non-destructive and provides a continuous measurement of the process variable. The system responds: to the fundamental makeup of matter, mass and elemental composition, not to secondary properties such as temperature, resistivity, or dielectric constant. Measurement is a volume rather than a surface phenomenon, thus the results can provide a truer pricture of the measured variable.

Jan 1, 1965

By S. Phillipson

The Mine Safety and Health Administration’s Roof Control Division (RCD) evaluated the use of Shuttle Radar Topography Mission (SRTM) data to identify fracture traces on Earth’s surface. Results were compared to the analysis method employed by RCD for 30 years, which relies on LANDSAT-TM Band 4. SRTM elevation models are expected to provide a direct representation of bedrock surface, while LANDSAT-TM Band 4 represents reflected near-infrared radiation as an indication of moisture content and is only a proxy for possible structures. Three areas in southwestern Pennsylvania were chosen for ground-truthing lineaments derived from both methods, following a series of desktop comparisons in six areas of the contiguous U.S. Field studies that identified numerous instances in which SRTM lineaments corresponded with joints at the projected location, and were oriented within 10° of joint strike, indicating that those SRTM lineaments represented the structural grain of the area. In some cases, lineaments were associated with individual joint zones. Photo-lineaments derived from the existing LANDSAT-TM methodology appear to offer a higher coincidence with expected trends of joints on a regional scale when performing the desktop comparisons, while field observations indicated that SRTM-derived lineaments had a higher association with individual geologic structures in the case study field area. It appears that both methods can identify the structural grain of an area, and that both tend to identify linear segments of valleys where erosion has preferentially occurred along joint zones or other structures.

Jul 1, 2023

By Kaige Zheng, Hongwei Wang, Tong Wang, Yanjun Li, Yongping Wu, JIANQIANG JIAO, Baolin Jiang

Due to the influence of economic development on the demand growth of coal resources, many mines in China have gradually entered deep mining. When the roof of deep coal seam is hard rock, it is easy to cause strong ground pressure with the advance of the working face, which seriously threatens the safety of coal mining. Taking 31,104 working face of a mine as the engineering background, this paper studies and compares the deformation characteristics and stress transfer evolution law before and after the presplitting of the hard roof through the combination of physical similarity simulation, numerical calculation, and field measurement, based on the analysis of the interaction relationship between the breaking and collapse of the composite hard roof, and verifies the treatment effect of hydraulic presplitting through field measurement. The results show that: (1) In the early stage of mining under the composite hard roof, the lower roof is mainly subjected to tensile failure, the voussoir beam structure formed is relatively unstable, and the stope is prone to impact. When the mining distance of the working face is large, the breaking rotation of the upper hard roof voussoir beam causes pressure damage to the lower hard roof, causing the lower hard roof voussoir beam structure to slide and lose stability, resulting in strong ground pressure in the working face. (2) After presplitting of composite hard rock stratum, in the early stage of mining, the range and degree of rock stratum damaged by presplitting are small except for the hard rock stratum itself, and the presplitting effect is not significant. When mining to the first square position, the roof is damaged in advance by presplitting, the overall plastic damage range increases, the damage form area increases, and the damage degree deepens. The vertical displacement of the composite hard roof increases rapidly, and the presplitting effect is remarkable. (3) The evolution characteristics of roof principal stress transfer show that under the dual effects of mining and presplitting, the roof tensile stress area above the goaf is large, the rock failure horizon rises, and the roof failure height is high and the failure degree is deep. The stress concentration degree of the coal mass in front of the goaf is reduced, and the stress concentration range is transferred to the rock mass in front. With the advance of mining, the hard roof in front can break and caving in time, so as to avoid rock burst disaster caused by large suspended roof area. The field ground pressure monitoring shows that the average periodic weighting interval, weighting range, peak value before weighting, and peak value during weighting of the working face after presplitting decrease by 53.5%, 38.03%, 8.63%, and 5.96%, respectively, which effectively reduces the weighting intensity and ensures the safe and efficient mining of the working face.

May 16, 2023