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By Katerina Adam

During wet grinding the electrochemical interactions between grinding media and pyrrhotite not only accelerate the media wear but also adversely affect the flotation response of the sulfide mineral. A possibility of remedying the adverse effect on its floatability by applying electric potentials to grinding media was examined. Flotation tests, Auger electron spectroscopy and x-ray photoelectron spectroscopy were used to study the surface properties of pyrrhotite. Although anodic polarization of the steels increased the metal loss by corrosion, the flotation recovery of pyrrhotite was increased. In the case of cathodic polarization, the flotation recovery improved in a narrow range of overpotentials. At higher cathodic overpotentials, however, the floatability of the mineral was progressively lowered although the corrosive wear of grinding media might be reduced.

Jan 1, 1984

By Virginia T. McLemore, Abena S. Acheampong-Mensah

Critical mineral endowment of mine wastes in two mining districts in New Mexico (Copper Flat at Hillsboro and Carlisle-Center mines in the Steeple Rock district) will be characterized and estimated. “Beta-testing” of USGS procedures was performed. Potential critical minerals at these deposits include As, Bi, Te, Zn, Co, Ni, Mg, Mn, and fluorite. pH and particle size of samples were analyzed to determine weathering and migration potential of heavy metals. Soil pH was also measured to determine the potential for Acid Rock Drainage. The pH of the waste rock piles ranged from 3.66 to 5.67 which indicates fine- grained pyrite or sulfide oxidation. The samples collected from the tailings however, showed a different range of pH, from 6.30 to 8.62, probably due to the presence of carbonates. Difference in particle size fractions and its distribution along the slope are generally influenced by natural occurrences (e.g., gravity and pre-mining hydrothermal alteration) and operational activities such as material piling or dumping. Future work includes analyses of mineralogy and particle size correlation and estimation of critical mineral endowment of these mine wastes at New Mexico.

Feb 1, 2024

By I. Abdullayev, M. Soberano Capistran, J. Garcia

The application of post-tensioning in segmental structures was introduced in the early 1900s and has been successfully applied in different types of structures including immersed tunnels, bridges, buildings, metro stations, and stadiums. There are, however, only five known circular concrete tunnel projects where the post-tensioning approach has been adopted. This paper discusses the application of post-tensioning to mitigate the high internal operating pressures in an effluent outfall tunnel project 7 miles, 11.3 km long, currently under construction for the Los Angeles County Sanitation Districts, LACSD. This project will be the first use of post- tensioned segmental concrete tunnel linings in North America.

Jun 23, 2024

By James A. Doolittle

In the underground type of mining operation, the finer portion of the waste material commonly is pumped as a hydraulic slurry to a tailings disposal pond. (1)* The tailings slurry is deposited via a pipe manifold system located around the perimeter of the pond. This method of deposition produces zoning because the coarser material tends to settle out immediately while the finer particles tend to remain in suspension and are deposited progressively nearer the center of the pond. The manifold system must be raised periodically as the pond fills with the tailings material. Over a period of time, this procedure will produce a zoned embankment known as a tailings dam. A typical pond and dam are shown in Figure 1. In plan view, the dimensions of tailings dams can be on the order of miles, with the height of the dam reaching 100 to 200 feet. Due to such factors as inadequate compaction, inherently low strength of the tailings material, and the possibility of high phreatic surface, many dams at some point become unstable, i.e., the factor of safety against a slope failure approaches 1.0. Remedial measures are required to improve the safety factor in order to prevent massive failure of the dam. In most cases, stability can be improved by effectively flattening the slope of the dam as shown in Figure 2, but this is not possible in every case. Occasionally, a tailings dam is constructed adjacent to a natural or legal boundary so that it is not possible to construct a conventional berm or to reduce the slope angle with earth moving equipment. Even a terracing process would require removal of the material and this may not be practical. In such a situation, an alternate scheme to improve stability must be found.

Jan 1, 1974

By Y. J. Wang

A critical path approach is presented for the problem of mine ventilation net- works where regulators and fans are employed to control the airflow distribution which is preassigned. The problem is a classic one which arises in mine ventilation planning. By identifying the analogy between the network for controlled flow and that for CPPI, the applications of the well known CPM technique to the ventilation network problem become straight- forward. The mathematical formulation of the problem is presented and the solutions are illustrated with examples. The effect of booster fans on the total air power consumed in a ventilation network are also discussed.

Jan 1, 1981

By Michael Moats, Weston Hartzell

The stable domestic supply of gallium, indium, and germanium has been identified as a critical need for the USA. Electric arc furnace dusts processed to recover zinc produce a process residue that could be a potential source of these critical materials. An industrial zinc leach residue was characterized to determine the predominant mineral phases and leached with common mineral acids. Atmospheric agitated leaching using sulfuric acid and hydrochloric acid were examined to determine the extractions of gallium, indium, and germanium as a function of concentration, temperature, and time. Extractions of gallium were found to be similar to iron in all experiments. The maximum percentage of Ga, Ge, and In leached into solution were 82%, ~100%, and 89%, respectively.

Aug 8, 2023

By Martin B. Zimmerman

It is becoming evident that traditional methods of econometric analysis are inadequate in estimating-the long-run supply of minerals. Econometrics is limited to extracting estimates from observations of the theory predicts that the least cost deposits will be exploited first.1 The estimation of parameters from past data then must lead to biased projections of the future. Mining conditions in the future will be worse than in the past and it is the impact of the future conditions on cost that we need to know. In this paper we present a methodology for dealing with this problem. We estimate a "cumulative cost" function that yields the long-run marginal cost of mining as a function of cumulative output produced over time.2 This is relatively easy to do for coal mining in the United States where exploration for new deposits is not a major factor in supply. The first step of the procedure relates cost to the rate of output and to the geological conditions of the mine. The second step combines geological information on remaining deposits with the cost function to yield the cumulative cost function. A central theme of both these steps is the interaction of economics with geology. The best deposits are selected first and in each step of the estimation allowance must be made for this fact. The problem of depletion is part of the general problem of structural change. The change through depletion in the nature of the exploitable mineral stock is only one factor that calls for an analysis sensitive to the changing circumstances of the industry. The factors impinging most heavily on the coal industry today are the strict environmental regulations legislated

Jan 1, 1977

By R. T. Hukki

The paper describes a two-stage industrial hydraulic classification system including hydrocyclones for primary classification and newly developed cone classifiers for secondary classification. Performance data based on large scale grinding and classification tests are presented.

Jan 1, 1981

By Anna Sieminska-Lewandowska, Monika Mitew-Czajewska

"The construction of 6.3 km long central part of 2nd metro line in Warsaw was completed in September 2014 (7 stations - out of which three 25m deep stations - built using cut and cover method; two single-track tunnels constructed using four EPB TBMs as well as a short NATM section with soil freezing below the existing road tunnel). Central section of the 2nd metro line was opened to public after verification and testing in March 2015. Design and build tender for the extension of this line in East (three stations) and West direction (three stations) was announced with total length of running tunnels – approx. 5 km. Detailed description of a very complex geotechnical context, different construction methods, challenges encountered and solved during construction and finally lessons learnt on this interesting project are presented in the paper. DESCRITPTION OF THE PROJECT Introduction The very first concept plan of the metro system in Warsaw was designed several years after regaining independence by Poland in 1918. In 1929, following the geotechnical survey, design works begun, but the economic crisis of the 1930s stopped it. After a few years of break, in 1938 a coherent concept of the metro network was proposed to be implemented in phases over the next 35 years. In total, construction of 46 kilometers of metro, including 31 km of tunnels and 15 km on surface, was planned. Unfortunately, World War 2 made the implementation of those plans impossible. In the post-war period several metro designs were elaborated, but none except one was scheduled for implementation. Construction of the 1st, 23.1 km long, North-South line commenced in 1983 and finished in 2008 (Sieminska-Lewandowska et all. 2009). Nowadays, Warsaw covers the area of 517 km2 and, according to year 2014 statistical data, the city has much more than 1.7 million inhabitants. Only one operating metro line is not sufficient for such a populated city. Up-to-date metro plan, shown on Figure 1, includes also 30.5 km long 2nd metro line. It’s route is divided into four sections: Western Section with the length of approx. 9.2 km and 9 stations, Central Section with the length of 6.3 km and 7 stations, North-East Section with the length of 7.7 km and 6 stations, South-East Section with the length of 7.1 km and 6 stations. The construction of the central part of the 2nd metro line in Warsaw was completed in September 2014 and its operation started in March 2015. The paper focuses on challenges encountered and solved and lessons learnt during construction of the central part of the 2nd metro line in Warsaw."

Jan 1, 2016

By Pierre Mousset-Jones

A questionnaire was sent out to three classes of mines to determine the extent of the heat problem in U.S. and Foreign underground mines. The following list shows the replies received from this questionnaire, however not all the known hot mines in the US replied. A complete listing of the results can be seen in Appendix I. 1) US coal mines - 37 replies 2) US non coal mines - 23 replies 3) Foreign non coal mines - 36 replies. At the present time there are approximately eleven non coal and one coal mine in the US experiencing heat problems which require special efforts to maintain an acceptable working place climate. However since the survey was completed some of them have been placed on standby. The Mine Safety & Health Administration (MSHA) does not have any specific regulations relating to heat stress. Informally the American Conference of Governmental Industrial Hygienists guidelines are followed which use wet bulb globe temperature (WBGT) with values ranging from 26.7°C to 31.1°C for a moderate workload, and different rest regimes. An MSHA report (Misaqi 1976) recommended that conditions should not exceed 26.1°C WBGT for men and 24.4°C WBGT for women. However, quite recently the organizations involved with planning two of the proposed nuclear waste repositories in the United States, have opted for the criteria of an air cooling power of 300 w/m2, and a WBGT of 27'C respectively.

Jan 1, 1986

By E. W. Geist

This paper is presented from the viewpoint of the mill operator and maintenance supervisor. Its purpose is to highlight the things that have been accomplished by the mill designers to lighten the load for the maintenance superintendent and to reduce the overall costs for the plant operator. The complexity of plant design, the civil and structural engineering problems encountered when the satisfactory maintenance layout is accomplished are appreciated, and the writer is fully aware of the complexities of these problems. However, it is not the purpose of this particular paper to dwell upon these problems, nor to emphasize or de-emphasize the problems of the civil, mechanical and electrical engineers. It is simply that the paper will attempt to review what these people have accomplished in spite of the many technical problems. This paper then is prepared with the operator and maintenance people?s viewpoint. What is their definition of design for maintenance? It is the writer's interpretation that the various design concepts which mean improved maintenance are such items as (I) maintenance areas, (2) laydown space for maintenance materials in specific maintenance jobs, (3) the inclusion of bridge cranes in the plant and specific design of the craneways to accomplish flexibilities for the cranes, and (4) the location of the piece of equipment to allow maintenance people to work around the equipment - - - this specifically includes the orientation of the particular piece of equipment.

Jan 1, 1967

By Kevin Andrews, SETAREH GHAYCHI AFROUZ

Ground control analysis and groundwater inflow assessments for underground coal mines require in-depth field investigations including, but not limited to, geological and geotechnical core logging, downhole geophysical logging, laboratory rock strength testing, and packer (Lugeon) testing. Field and laboratory data collection are time consuming and expensive, and an initial understanding of the expected trends among various geotechnical and hydrogeological parameters can assist with the planning and optimization of geotechnical characterization studies and grouting plans. In this study, a comprehensive database is analyzed, comprised of important rock mass characteristics (hydraulic conductivity, rock quality designation (RQD), and lithology) for coal-bearing rocks in the Central Appalachian Basin. Statistical analysis of the data is completed to establish an enhanced understanding of geotechnical and hydrogeological conditions expected to be encountered as underground coal mining passes near and beneath streams and rivers. The results of the study provide valuable reference material for the coal mining industry for completion of shaft installations, mine stream crossings, environmental assessments, and grouting and mine dewatering designs.

Jul 1, 2023

By David L. Giles

The Lime Creek* ore body in northwestern British Columbia is one of the few commercial primary stockwork-type molybdenite deposits in North America. Others include the Climax, Urad-Henderson, Questa, and Endako ore bodies. They are mined on a low grade-high tonnage basis, and are open pit operations except for Climax and Urad-Henderson. Much recent geochemical research on both porphyry copper and stockwork MoS2 deposits has been concerned with dating of micas related to the mineralization and associated igneous rocks. The results appear to show that mineralization and the predominant magmatic events of the deposit are indistinguishable in age (1-5), except where dating has been in sufficient detail to resolve the analytical overlap (6). At Lime Creek, geologic information shows that the Main granodiorite, the major intrusive and dominant host rock for MoS2 mineralization, was emplaced and had solidified sometime prior to the introduction of MoS2. The first MoS2 episode is intimately related to localized bodies of kalialaskite which clearly intrude the older stock. K-Ar dating was undertaken to clarify the age relations between Lime Creek plutonism and the apparently younger hydrothermal event that began with kalialaskite.

Jan 1, 1975

By R. Schlüter

"The “Biohydrometallurgical Center for Strategic Elements (BHMZ)” is a cooperation of 13 departments of the Technical University Bergakademie Freiberg fostering interdisciplinary research along the whole (bio-) hydrometallurgical process chain to extract indium and germanium from sulphide ores. Research comprises methods to (i) bring the respective metal from the source material into aqueous solution and (ii) different approaches to extract pure metal or metal-containing materials from the solution. Within the BHMZ the Department of Underground Mining Methods deals with the design and implementation of an underground testing facility for bacterial in-situ stope leaching in its own “Research and Educational Mine”. The intention is to investigate innovative approaches for leaching technologies by crack initiation due to hydraulic fracturing or water pressure blasting under consideration of leaching kinetics and underground conditions. It is planned to set up two testing units comparing energy input and the metal output of conventional (blasting) as well as one of the innovative technologies. Aim of subproject is to establish an innovative and sustainable method ready for up-scaling. BACKGROUND Metals like copper and zinc mainly occur as sulphide ores in nature. Due to the insolubility of these sulphide minerals the respective metal is commonly extracted by pyrometallurgical processing methods. These methods require several steps of enrichment of concentrates such as flotation and roasting (Figure 1) under extensive energy utilization. Additionally, this arouses the emission of sulphur dioxide gas which can have a negative impact on the environment in form of acid rain, as long it is not caught by sulphuric acid facilities (Schippers et al. 2011). However, to treat the ore on the surface either open pit or underground mining operations are necessary. This implies operation steps from excavating, loading, and conveying/hauling, to dumping with the sub-processes crushing and stashing. Due to the tendency of increasing depth, more complex ores and decreasing ore grades of the mineable deposits as well as increasing energy and environmental costs these conventional mining and processing methods become in general more costly and difficult to apply. Hence, hydrometallurgical processes and especially the suitability of bioleaching as an alternative in-situ method for future mining projects should be examined. Leaching by means of microorganisms is a combination of mining and processing by converting the insoluble metal into an aqueous form. This technology is an economically beneficial and environmentally friendly alternative to pyrometallurgical processing methods especially for primary and secondary low grade ores. Mainly the extraction of copper but also of zinc and lead from sulphide ores is state-of-the-art in surface leaching operations like heap and dump leaching (Figure 1)."

Jan 1, 2015

By Liming Yuan, Wei Tang, RICHARD THOMAS, JOHN SOLES

Lithium-ion (Li-ion) battery pack fires pose great hazards to the safety and health of miners. A detailed experimental study has been conducted at the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Mining Research Division (PMRD) to investigate the effectiveness of different fire suppression systems on Li-ion battery pack fire extinguishment. Tests were conducted in a well-ventilated container. Two sizes of battery packs (12 V and 24 V) were heated by heater strips to trigger thermal runaway and fire. Water mist with different flow rates, ABC powder, type D dry chemical, and water mist with F500 additives were used as the fire suppression agents. Multiple thermocouples were installed on the battery packs to measure the temperature evolution during the tests. The results indicate that the water mist with F500 additives is the most effective suppressant among the agents tested. Dry chemicals, however, do quench the fire for a moment, but cannot prevent re-ignition of the battery since they do not provide enough cooling. The findings of this paper can be used to develop safer battery fire suppression techniques in mining environments.

Jan 1, 2024

By Siddhartha Agarwal

The mining industry collects a significant amount of operational data. However, gleaning useful information from the terabytes of data is difficult, and not just because of the sheer volume of the data. Therefore, an automated tool was developed at the University of Alaska Fairbanks to go through data and apply sophisticated statistical and neural network techniques in order to identify the data streams that are important to a process. This paper presents results from the tool as applied to SAG mill data from a gold mine. The results were compared to results achieved earlier with available commercial modeling tools. The comparison indicates that there was little or no loss in performance by automating the very complicated process of neural network modeling. Therefore, the intent of the exercise, to examine if complicated modeling tasks can be automated, was realized. Mining Engineering, 2011, Vol. 63, No. 12, pp. 52-54. Official publication of the Society for mining, metallurgy and exploration, Inc.

Jan 1, 2011

By Klaus Rabensteiner, Klaus Chmelina

"INTRODUCTION Urban tunneling is often related with special geotechnical risks. Typical causes are difficult (hydro)geological conditions, a very low overburden and the presence of critical and vulnerable (infra)structures in the influence zone of the construction (e.g. existing tunnels, roads and pavements, sewer pipes, gas and power lines, landmarked buildings, historic monuments). To manage these risks appropriately, an early detection and warning of unexpected behavior of the affected geotechnical objects ground and tunnel, as well as existing structures are mandatory. To accomplish this, the design and execution of a dense geotechnical monitoring program is of high importance. In more detail, this means specifying and performing a systematic and continuous acquisition, processing and analysis of monitoring data to support decision making. In recent years the development of new automatic sensors and (wireless) data transfer techniques and the general trend towards an automatic acquisition of monitoring data has led to an enormous increase of data production frequencies and volumes. In order to handle this data explosion efficiently, information systems and geo-databases have been developed and used successfully in many projects. They represent IT tools that support the different tasks of a given geotechnical monitoring program including data acquisition, transfer, check, processing, backup, analysis, distribution, reporting and, last but not least, alarming. Meanwhile, some tools already have developed the capability to connect to other theme-specific databases used in the project and, thus, serve as a central data management system for all kind of digital data produced. This makes possible the implementation of further useful functions and services supporting tunneling tasks such as machine control, tunnel simulation, geological prediction, process optimization, etc. where data from different engineering disciplines must be combined and processed in an integrated way. In the following chapters our aim is to describe how monitoring data management, geotechnical monitoring, alarming and reporting are organized and technically implemented at the metro project Cityringen in Copenhagen (Denmark). We want to highlight the specific role and tasks of the used tunnel information system in the project, and particularly inform on the most relevant challenges."

Jan 1, 2016

By Caelen D. Anderson

An investigation of a hydrometallurgical method for the recovery of tellurium dioxide from cadmium telluride (CdTe) thin-film manufacturing scrap was conducted. Sulfuric acid/ hydrogen peroxide lixiviation was employed to selectively leach cadmium and oxidize tellurium to tellurium dioxide (TeO2). Experimental variables included solution pH, pulp density, oxidant (H2O2) concentration, temperature, agitation rate and residence time. After one hour of lixiviation, no noticeable increase in grade or recovery occurred; thus, all experiments were performed for one hour. Leaching results showed it was possible to recover at least 74% of the tellurium, while producing a 98% pure TeO2 product. Additionally, an apparent activation energy value of 12.1 kJ/mole (2.9 kcal/mole) was determined. This value, along with results from agitation rate experiments, indicated the reaction was primarily controlled by diffusion through the product layer. During lixiviation, partial dissolution of tellurium proved inevitable. Thus, a second step: ammoniacal precipitation was introduced to recover the aqueous tellurium as a precipitate. A statistical experimental design (DOE) was used to identify the significant effects from the residual effects. Experimental variables included precipitation pH, temperature, initial tellurium tenor and agitation rate. Precipitation results showed that it was possible to produce a low-grade (46% Te) precipitate, while recovering 98% of the aqueous tellurium species. The precipitation pH and temperature (°C) were determined as the significant effects for both the grade and recovery of tellurium. Agitation rate and initial tellurium tenor were determined as the residual effects and did not influence the grade or recovery of tellurium. An illustration of tellurium recovery, as a function of the significant effects, is illustrated in Fig. 1.

May 1, 2012

By Charles H. McGuirk

The Port of Conneaut, the largest bulk material handling and storage facility on the Great Lakes, is using the latest electronic and visual testing devices to augment and enhance its well established computerized preventive maintenance system. The results of this comprehensive program have been impressive. The remaining life of components can be accurately forcast, and replacement can be programmed around operations, resulting in a significant improvement in system availability and reduced costs for the dock operator and its customers.

Jan 1, 1983

By C. Don Sullivan

Paraphrasing the poetic repetition of Gertrude Stein - "Research is research, is research, is research --- ad infinitum." But research takes many forms and involves many facets. Perhaps the most simple of definitions is that attributed to the late "Boss" Kettering of General Motors who in advising a young trainee said, "Research is an intelligent effort to satisfy the curiosity of the human mind." Reclamation research is complex and requires a diversity of scientific knowledge. The overall aim of land reclamation research is directed to finding practical ways to develop efficient methods to restore mined lands to productive use, compatible with use of adjacent lands, as soon after mining as possible; and, finding practical ways to reduce or prevent damage to surrounding resource areas, which may be affected by the mining process. Research in the field of mined land reclamation is not entirely new, although in some respects we are exploring new areas each day.

Jan 1, 1967