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By D. A. Rice

In pelletizing magnetic iron ore concentrates, about 6 to 18 lb of bentonite binder are added per ton of concentrate during balling to give green and dry strengths to the unfired pellets. The dry bentonite is mixed into the filtercake following the magnetic concentration circuit of the plant. The filtercake contains about 10% moisture, and the water may be of highly variable composition, depending on the particular concentration circuit, its source, and the ore being treated. A knowledge of the parameters that influence the balling operation is essential for optimal efficiency in producing balls strong enough to survive the treatment during transportation from the balling device to the furnace and during the firing operation. Furthermore, very weak unfired pellets probably contribute to high dust losses and poor furnace control. The factors that determine the strength of unfired pellets have received considerable study (1,2,3,4). Tigerschiold and Ilmoni(l) pointed out the significance of the surface area of the particles being pelletized. Merklin and Childs(2) reported on the effect of material size consist, chemical additives such as soda ash, lime, balling time, ball size, and the moisture content of green balls. Iwasaki and Zetterstrom(3) examined the detrimental effects of fatty acids on the pelletizing process. Stone(4) correlated the zeta potential of bentonites with the strength of unfired pellets. He found that, in general, a high negative charge on the bentonite is conducive to good balling. Although studies of pelletizing in the iron ore industry deal with a complex multicomponent system consisting mainly of the iron mineral, bentonite, and water, the last of these has received little attention, particularly with regard to the possible effects of mill water chemistry on the pelletizing process and the strength of unfired pellets. It is widely known that the composition of mill process water is an important variable in unit operations such as flotation, thickening, and filtering and that impure water can lead to poor metallurgical results. The results of the present study indicate that the chemistry of the mill water may be an important variable in the balling operation as well. Knowledge about this variable should contribute to lowering bentonite and oil consumption and to improving furnace performance. Such knowledge can also assist those who use balling in evaluating commercial bentonites for plant use as well as those investigating balling from a more fundamental point of view In this study we have examined 1) the effects of replacing mill process water in the magnetic concentrate filtercake with pure water, and 2) the effects of several chemical impurities that are commonly found in mill process waters upon the strength of unfired pellets. The results are interpreted in terms of the zeta potential of the bentonite and magnetite particles. The data lend support to a suggested mechanism whereby the electrostatic attraction of oppositely charged particle surfaces causes bentonite-bentonite and magnetite-bentonite bonding. This mechanism would also explain why several chemical additives e.g., sodium carbonates and phosphates, have such marked effects on increasing the strength of unfired pellets.

Jan 1, 1971

By V. Z. Sun

One of the major concerns of ground control in a coal mine is safety against failure of one of three components (i.e. roof, pillar, or floor) of the mine entry. In order to better design and evaluate stability of the mine entry with a certain confidence, a reliability approach is introduced rather than using the conventional safety factor (SF) method only. Advantages of using the reliability approach is that it not only takes variability of both rock/coal properties and stress distribution into consideration, but also assesses the stability of each component and mine entry as a whole system. Therefore, it is anticipated that, by using this approach, the current ground control technology in coal mine will convey a better sense of confidence. The results of a case example show a significant influence on the current design concept and stability evaluation of mine entry.

Jan 1, 1997

By C. L. Jiang

The role of iron ions (Fe2+ and Fe3+) in the flotation of both ore-and coal-pyrite with ethyl xanthate was comparatively investigated. The complete/partial depression of ore-and coal-pyrite in neutral to weakly alkaline solution is due to the formation of ferric dihydroxy ethyl xanthate between xanthate and the oxidation products of pyrite, ferric and ferrous ions. With xanthate as collector, coal-pyrite was found to be nonfloatable above pH6. In the presence of iron ions and between pH6-9.5, the flotation of ore-pyrite was significantly depressed. Ferrous ions have a stronger effect on pyrite flotation than ferric ions in neutral to weakly alkaline solutions.

Jan 1, 1996

By Z. Zhang, M. S. Gonzalez, M. de P. Bueno, P. Holopainen, S. Luukkanen

In an extremely competitive mining industry, onsite experience is a big advantage. Mining education at the universities is mostly focused on theoretical studies without a possibility of practical training in mining sites. Hence, experimental mines suitable for practical education are needed to provide a platform for systematic research and education in industrial scale and for training in real mining conditions. Yet, this kind of mine sites is rare worldwide. Thus, a new educational research project, namely MINETRAIN is introduced in this paper evaluating the transition of the Pyhäsalmi mine in Central Finland from an active base metal mine to a research, educational and training underground facility. The uniqueness of MINETRAIN compared to other test mine programs is that the existing state‐of‐art infrastructure in Pyhäsalmi enables research and training facilities among all disciplines related to the overall mine value chain. Though all the above sound interesting in the context of research and education purposes, in practice Pyhäsalmi will have to become an experimental mine that can be sustainable in the future. Accordingly, a prefeasibility study is being conducted and some preliminary results are presented in this paper. INTRODUCTION Despite being a field of studies that requires practical knowledge and experience, mining engineering education follows the same pattern in most mining universities around the world; consisting of theoretical courses and laboratory-based practical modules (Mischo, 2015). The possibility of having practical training in real mining conditions on actual mine sites or processing plants is limited to none, while the only contact that undergraduate students have with mining operations during their time of studies is usually through short-time internships or visits in the context of educational trips. Yet, real integration between universities and the mining industry may be scarce, which does not help students to observe the actual processes, and thus understand the whole picture of mining operations. Indirect practical training is also possible nowadays that technology is shifting from mechanical to digital, and the use of virtual reality -in the context of Mining 4.0- can provide additional experience to the learning process. However, virtual reality is limited to the visual impression and is also limited in actions (Binder et al, 2018). In any case, when there is not a proper pragmatic view of how the different disciplines link to each other and especially if there is a lack of communication, unfortunately the results could be seen at a later stage in the mines as a poor performance of professionals and workers. Another major challenge for educating specialists in the mining sector is that experimental mines suitable for practical education, where the skills and know-how could be developed and/or enhanced are rare worldwide. Such research and educational (R&E) facilities are practically former metal ore mines that have been transformed into experimental sites. Besides being limited in number, not all facilities of this kind serve both a research and educational purpose.

Jan 1, 2019

By Dapeng Zhang, Brij Moudgil, Shibo Zheng, Chunhui Feng, Wenyi Song, Wending Xiao, Patrick Zhang

Separation of dolomite from phosphate is the most challenging problem in phosphate mineral processing. Over 50% of the future phosphate reserve in Florida contains too much dolomite to process using the current industry practice. The current phosphoric acid production practice requires less than 1% MgO in the phosphate concentrate as the feed material. The Florida Industrial and Phosphate (FIPR) Institute has collaborated with worldwide experts in the field to address this issue. As a result, the industry is now offered three feasible options. Option 1 offers three methods for reducing MgO content in the concentrate from the Crago process, including adding a dolomite depressant in the rougher flotation step, dolomite flotation of the cleaner concentrate, and scrubbing the cleaner concentrate in quartz sand. These methods could reduce MgO content in the final concentrate by 20–40%. Option 2 involves crushing and grinding of high-dolomite phosphate pebbles followed by dolomite flotation at slightly acidic pH using a new collector that does not require phosphoric acid as a phosphate depressant, achieving a final concentrate analyzing less than 0.9% MgO at about 87% P2O5 recovery. Option 3 is a gravity separation technique using an innovative separation jig, and its full potential remains to be demonstrated.

The objective of this paper is, firstly, to summarize several field developments utilizing the art of hydraulic fracturing as it has been extended into various mining applications. Secondly, to summarize the understanding of the hydraulic fracturing processes; and lastly to discuss researchable areas and possible future applications. Hydraulic fracturing was developed as a method of stimulating production of oil from oil producing formations. The primary paper by Clark (1) in 1949, describes the process of placing a hydrostatic pressure of sufficient strength on the producing formation of an oil well that the rock apparently cracked, and then, on allowing the well to flow back, a higher rate of recovery of oil was enjoyed. The interpretation of the process mechanism was that the formation rock was cracked to a considerable distance from the well bore, increasing the drainage area; thus, the productivity of the well was measurably improved. Figure 1 is illustrative of this process. This development was of major significance to the oil producing community and considerable research and development ensued. Improvements in method, engineering development of equipment, and research to ascertain the optimum application of fracturing practice led to a highly sophisticated, but specialized technology. The Production Research Division, Continental Oil Company, vigorously pursued research in this area in the 1950's with a resulting number of process improve¬ments. The research group, published a significant number of technical papers on these various researches. One of the developments was the process aimed at controlled orientation of the fractures, either in the vertical (2) or horizontal (3) orientation.

Jan 1, 1969

By Kenneth R. Krivanek

In recent years the widespread problems of air and water pollution generated by both population and industrial expansion have become a major public concern. Therefore, many municipalities are striving to achieve more efficient wastewater treatment processes so these wastewater's can be reintroduced into the waterways of our nation with little or no detrimental effects on the future beneficial use of that water. With this, improved treatment comes an ever increasing volume of wastewater sludge which must be disposed of in a manner of minimal impact on the environment. Furthermore, with demand for energy continually accelerating in this nation, our concern over high oil prices and our increasing dependency on foreign oil sources, there has been an ever growing interest in the largest energy source that are nation has, coal. However, surface mining of coal can cause many environmental problems when adequate precautions are not faithfully adhered to. These problems include water pollution from silt and/or clay erosion and acid runoff, produced by oxidation and hydrolysis of pyrite; i.e., FeS2 + 3/02 + H20 + FeSO4 + H2SO4. One method of wastewater sludge disposal which can utilize large volumes of sludge for a beneficial project that may not compound our environmental problems is spray irrigation, to either depleted farmland or to abandoned strip-mined soils. Sludge is characteristically high in organics, as well as having near neutral to alkaline pH properties. With these two qualities it possesses a potential for neutralizing acid strip mine spoils, which would enhance the establishment of a vegetative ground cover. Sludge can accomplish this by lowering the oxidation potential, reducing the solubility of iron and aluminum and by the chelation of metals, thereby

Jan 1, 1977

By M.P. ROY, ASHISH K. VISHWAKARMA, A.K. MISHRA, P.K. SINGH, VIVEK K. HIMANSHU

Principal component analysis (PCA) is one of the dimension reduction techniques widely used to classify data based on features. Ground vibration is a major hazard arising from rock blasting operations, and accurate prediction of the vibration is necessary for designing controlled blasting parameters. Most of the widely accepted predictors of ground vibration consider the maximum explosive charge weight per delay (MCPD) and distance as the parameters responsible for ground vibration, but mining sites with bigger production targets have varying geometrical parameters to suit the excavator utility. Accordingly, other blast design parameters will also have impacts on ground-vibration intensity. A blast vibration predictor considering all the blast design parameters would be complicated, and some of the parameters will have overlapping contributions to ground-vibration intensity. Data classification using PCA is a feasible solution, and regression analysis may be performed to develop predictors using the classified input data. In this study, PCA was used along with multivariate logarithmic regression to predict ground vibration, and the performance of this technique to predict ground vibration was compared with the performances of various existing empirical predictors. The evaluation suggests that the predictor with logarithmic regression followed by PCA performs better than the existing empirical predictors.

Nov 1, 2022

By James E. Jones

The coal mining industry is being called upon to vastly increase production in the coming years. Many mining operations will have to prepare an environmental impact report of some kind and all will have to comply with various types of environ- mental regulations. Therefore there is a great need within the industry for access to environmental data, information, and literature. This paper discusses the informational resources available, the current lack of access to these resources, and the Environmental Data, Information and Literature (EDIL) Bank of the Kentucky Institute for Mining and Minerals Research. The bank's major emphasis concerns the environmental, social and economic aspects of producing clean solid, liquid, and gaseous fuels from coal. The data bank promotes information interchange between other related governmental and private projects and the energy development community.

Jan 1, 1976

By John D. Hanifin, C. Kevin Moon, Eric C. Wang

Value Engineering on Connecticut DOT’s Walk Bridge selected the trenchless option for utility relocation to address the channel crossing’s environmental concerns. The design and construction considerations of the twin micro-tunnel drives and associated shafts are presented. Key challenges included vertical alignment selection to achieve minimum one-tunnel diameter stable cover within thin glacial till underlying extremely soft clay, limited choice of pipe and joint materials meeting stringent non-metallic conduit requirements, thermal grout backfill application, and the close proximity of temporary trestle piles. Mitigation measures were developed for potential point loading pipe damage from remnant boulder fragments in the annular space.

Dec 1, 2022

By Wei Victor Liu, Na Zhang, Chengkai Fan, Bei Jiang

This study used artificial neural networks (ANNs) coupled with Gaussian mixture modeling (GMM) to analyze truck haulage data from openpit mines. The proposed weighted ensemble models performed better than benchmark models in predicting truck productivity, providing a new means of solving complex data and improving mine planning and decision-making.

Jun 1, 2023

By Verne Huser

The intensity of environmental conflict, the delays and legal battles that have marked the 1970's suggest the need for additional processes to resolve environmental disputes. Our present means frequently fail to address the real issues separating individuals and institutions. They are primarily adversary processes that foster polarization and reduce cooperative efforts. At the Office of Environmental Mediation, we have no quarrel with adversary processes nor with polarization, for both serve as important spurs to necessary change. We do seek cooperation among parties at a point where there can be a realistic expectation of success in facilitating a resolution of their mutual differences.

Jan 1, 1979

By H. R. Bullis

Lupin is located on the shores of Contwoyto Lake at lat. 65° 48'N, Long. 111° 15'W and lies about 80 kilometers south of the Arctic Circle. Since start up in 1982 the mine has produced over 2.15 million ounces of gold from 6.66 million tonnes of ore grading 10.63 gm/tonne. Total remaining reserves at 1993 year end were 5.1 million tonnes at a grade of 9.11 gm/tonne (1.65 million ounces). This is sufficient for 7 -8 years at the present annual production rate of about 200,000 ounces. The Centre and West Zones of the deposit are open to depth. The deposit is in an Archean metaturbidite sequence of the Contwoyto Formation, which has been mapped as part of the Yellowknife Supergroup of supracrustal metasedimentary and metavolcanic rocks making up part of the Slave Geologic Province. These rocks have been subjected to regionar and contact metamorphism and to several phases of deformation. Six stages of Archean plutonism have been identified and all Archean rocks have been cut by Proterozoic diabase dyke swarms. Gold mineralization in the Lupin deposit is commonly fine grained and associated with pyrrhotite and arsenopyrite in amphibolitic banded iron formation. The gold-bearing portions of the host iron formations are characterized by the presence of multiple quartz veins and the pervasive replacement of grunerite by hornblende. In sparsely mineralized portions of the host iron formation, zoning of sulfides about quartz veins is clearly seen with the arsenopyrite halo being more restricted around the veins than the pyrrhotite halo. In well mineralized portions, quartz vein densities approach one vein per metre along strike. In these areas pyrrhotite distribution in the iron formation is more pervasive and the rock takes on the appearance of a banded sulphide rock.

Jan 1, 1995

By C. B. Daellenbach

The influence of reduction roasting and thermal shock on the grindability of a refractory low-grade Michigan iron ore was examined in bench scale tests. The quantitative effects of the various treatments were evaluated at three sieve levels: 48, 100, and 400 mesh, using ball mill grindability and work index parameters as response indicators. Data from the testing program were analyzed statistically as a means of isolating the effects of cooling rate, roasting temperature, and ore chemical condition. All three variables were found to have an important influence on the grindability of the treated ore; ore chemical condition and roasting temperature had the most pronounced effects.

Jan 1, 1970

By A. H. Srnallbone

Over the past few years the rising production costs, shortage of skilled labor, and increased use of lower grade ore bodies have all added justification for the use of on-stream analysis. A rise in the number of on-stream units indicates that this type of assay is now being accepted as a necessity. On-stream analysis is a much more rapid means of obtaining true assays of a flowing product when compared to wet chemistry or "grab" samples dried, briquetted and assayed by x-ray. In contrast, on-stream analysis uses real time samples assayed every 30 seconds while each stream is assayed every 5 to 15 minutes. It is very important not only to know that a change has occurred in the process, but to know what caused the change and how to correct for the change. For example, in a tailing sample the elements of interest comprise between 1% and 10% of the sample. The remainder is water and gangue. Previously the gangue was not assayed nor were the low atomic number elements used for corrections. In addition to the demand for higher accuracies some concentrators were being penalized for excessive Ca or in some cases 5i in their concentrates. This penalty was being imposed by the smelter in order that they could better cope with pollution problems and prolong the life of their furnaces. But until Ca, 5i, and S are measured on-line, nothing can be done about their control. By accurately measuring these light elements on-line, a complete assay is obtained of the total sample providing improved accuracy for the important products. The justification for complete accuracy assays is now even more obvious because they are possible at very 1ittle increased cost and at no increase in analytical time.

Jan 1, 1977

By Fengmei Chen, Na Liu, Bingrui Li

A quantitative analysis method based on the airflow influence factors is proposed to evaluate airflow stability and discriminate airflow directions in complex ventilation networks. The law governing the changes in airflow caused by changes in branch resistance is revealed based on simulations of the airflow state in a ventilation network and a statistical analysis of the results. Then, three evaluation indices (airflow sensitivity, airflow influence factor, and critical airflow) are determined, matrices of the airflow influence factors and critical airflows are constructed, and a quantitative evaluation method for ventilation system stability and an airflow directional discriminant are proposed. The results show that the stability of a ventilation system can be reliably evaluated based on the airflow influence factors. The sensitive branches and dominant branches in the ventilation network can be determined based on the matrix of airflow influence factors, and the reversed branches, the trigger branches, and the reversal conditions can be determined based on the critical airflow matrix and the matrix of airflow influence factors. The proposed airflow directional discriminant is suitable for evaluating arbitrarily complex networks.

Nov 15, 2023

By J. Noll, D. Yantek, B. Kendall, J. A. Organiscak

"A self-tramming remotely controlled mobile Dry Scrubber (DS) was developed by J. H. Fletcher and Co. under a contract with the National Institute for Occupational Safety and Health’s Office of Mine Safety and Health Research (NIOSH OMSHR) to reduce exposure of miners to airborne dust. NIOSH OMSHR laboratory testing showed that the DS averaged greater than 95% dust removal efficiency with the disposable filters and averaged 88% and 90%, respectively, for the optional washable filters in their pre-washed and post-washed test conditions. Although the washable filters could be reused, washing them generated personal and downstream respirable dust concentrations of 1.2 and 8.3 mg/m3, respectively, for a 10-minute washing period. The DS’s velocity pressure regulated variable frequency drive (VFD) fan maintained a relatively consistent airflow near the targeted 1.43 and 4.25 m3/s (3000 and 9000 ft3/min) airflow rates during most of the laboratory dust testing until reaching its maximum 60 Hz fan motor frequency or horsepower rating at 2610 Pa (10.5 in. w.g.) of filter differential pressure and 3.97 m3/s (8420 ft3/min) of scrubber airflow quantity. Laboratory sound level measurements of the DS also showed that the outlet side of the scrubber was noisier and the loaded filters increased sound levels as compared to clean filters at the same airflow quantities. With loaded filters the scrubber reached a 90 dB(A) sound level at 2.83 m3/s (6000 ft3/min) of scrubber airflow, indicating that miners should not be overexposed in relation to MSHA’s permissible exposure level (PEL) of 90 dB(A) at or below this airflow quantity (1). The DS’s washable filters were not used during field testing because of their lower respirable dust removal efficiency and the airborne dust generated from filter washing. Field testing the DS with the disposable filters at two underground coal mine sections showed that it can clean a portion of the section return air and provide about a 50% dust reduction at the face area downstream of the continuous miner (CM) operation. INTRODUCTION Coal mine worker overexposure to coal and quartz dust continues to be a problem at underground coal mining operations in the U.S. The U.S. Mine Safety and Health Administration (MSHA) recently changed the standard for coal mine worker respirable dust exposure from 2.0 mg/m3 average during an eight-hour shift to 1.5 mg/m3 average over the actual working shift, effective as of August 1, 2016 (1). If more than 0.1 mg/m3 quartz mass is found in the coal mine worker dust sample, the applicable respirable dust standard is further reduced to the quotient of 10 divided by the percentage of the quartz in the sample (1). Over 90% of the mechanized mining units operating in U.S. underground coal mines are continuous mining machines (2). MSHA inspector dust samples from 2009 to 2012 showed that 3.7% of continuous miner operators exceeded the 2.0 mg/m3 dust standard, while 8.8% of these dust samples exceeded the new 1.5 mg/m3 dust standard and 9.7% of these samples exceeded the reduced quartz standard (3). Additionally, roof bolter dust samples at these mechanized mining units during this same period have exceeded the 2.0 mg/m3, 1.5 mg/m3, and reduced quartz levels at 1.1%, 3.7%, and 10.6%, respectively (3)."

Jan 1, 2016

By J. Noll, D. Yantek, J. Organiscak

The Office of Mine Safety and Health Research of the U.S. National Institute for Occupational Safety and Health (NIOSH OMSHR) conducted laboratory testing of a self-tramming, remotely controlled mobile Dry Scrubber (DS) that J.H. Fletcher and Co. developed under a contract with NIOSH OMSHR to reduce the exposure of miners to airborne dust. The scrubber was found to average greater than 95 percent dust removal efficiency with disposable filters, and 88 and 90 percent, respectively, with optional washable filters in their prewash and post-wash test conditions. Although the washable filters can be reused, washing them generated personal and downstream respirable dust concentrations of 1.2 and 8.3 mg/m3, respectively, for a 10-min washing period. The scrubber’s velocity-pressure-regulated variablefrequency- drive fan maintained relatively consistent airflow near the targeted 1.42 and 4.25 m3/s (3,000 and 9,000 ft3/min) airflow rates during most of the laboratory dust testing until reaching its maximum 60-Hz fan motor frequency or horsepower rating at 2,610 Pa (10.5 in. w.g.) of filter differential pressure and 3.97 m3/s (8,420 ft3/min) of scrubber airflow quantity. Laboratory sound level measurements of the scrubber showed that the outlet side of the scrubber was noisier, and the loaded filters increased sound levels compared with clean filters at the same airflow quantities. With loaded filters, the scrubber reached a 90 dB(A) sound level at 2.83 m3/s (6,000 ft3/min) of scrubber airflow, indicating that miners should not be overexposed in relation to MSHA’s permissible exposure level — under Title 30 Code of Federal Regulations Part 62.101— of 90 dB(A) at or below this airflow quantity. The scrubber’s washable filters were not used during field-testing because of their lower respirable dust removal efficiency and the airborne dust generated by filter washing. Field-testing the scrubber with disposable filters at two underground coal mine sections showed that it could clean a portion of the section return air and provide dust reduction of about 50 percent at the face area downstream of the continuous-miner operation.

Jan 1, 2016

By Stuart W. Maher

A major problem in future discoveries of base metals is their "explorability". By this I mean an exploration program must be designed that assures accurate assessment of the potential for ore, but is within reasonable budgetary constraints. As we are compelled to depend more and more on non-outcropping prospects, "blind" deposits, and as drilling costs multiply, the costs of exploration increase significantly. Solutions to the problem of defining exploration targets are influenced by our conceptions of the origin and recognition o f conditions that localize ore. The maxim that "elephants should be sought in elephant country" presumes we can recognize elephant country. This paper presents a suggested origin for some mineral deposits, and their controls; particularly those termed ?Mississippi Valley type". Tennessee is used as an example of the ideas offered. Mining districts designated "Mississippi Valley type" are, and have long been, the principal sources of barite, fluorite, lead and zinc ores in the United States and elsewhere throughout the world. A large volume of literature is available describing this class of ore deposits, explaining their habitat, and invoking genetic models for them. The quality of this literature is notably uneven, some of it demonstrably erroneous, and much of it is restricted to detailed descriptions of one aspect of the problem, or to detailed descriptions of one aspect of the problem, or to a single mine, or even a single stope. If an ore deposit is thought

Jan 1, 1977

By M. Nambiar

Due to the remote locations of the mining projects and the demand for long transmission lines to provide electrical power, mining sites often operate with poor network power quality and low short circuit capacity. In order to cope up with this situation, more and more mining projects are considering the installation of appropriately designed Synchronous Condensers(SC) together with Power Factor Correction and Harmonic Filter System(PFC&HFS). The installation of these power quality equipments is viewed as a technological advancement in the mining application. An adequate level of short circuit power is essential and has to be ensured for the safe and reliable operation of especially large cycloconverter driven gearless mill drive systems used for grinding application. Increase in plant short circuit power is generally achieved by lowering the impedance of the supplying network. The SC also provides smooth voltage control during mill starting or major load trips, thereby regulating the plant voltage within the required limits. This paper will explore the impact, technical advantage and reasoning for the selection of the advanced hybrid technology mentioned above, in order to cope with the power system challenges for future mining projects. It also highlights the potential problems and how to address them carefully.

Feb 23, 2014