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By K. E. Kolm, W. H. Langer

Developing natural aggregate resources (sand, gravel, and stone) creates environmental impacts. A systems analysis method has been designed to characterize the components of the environmental system, identify potential impacts to those systems, and evaluate the extent of those impacts. The step-wise method consists of problem definition, data collection, preliminary conceptualization and characterization, additional data collection, data analysis, and refinement. The method requires analyzes of various systems making up the environment, including land surface, geomorphic, subsurface, and groundwater systems. After system characterization is complete, the method focuses on identifying and evaluating potential environmental impacts to determine acceptable mining strategies.

Jan 1, 2001

By R. H. Zeng

Many subsidence researchers in the U. S. have developed new empirical function methods to predict subsidence, or attempted to validate some empirical functions developed by foreign researchers for use in the U. S. An attempt is made in this paper to develop a new empirical function to predict a surface subsidence basin due to longwall mining. In the U. S., the emphasis of empirical methods for the subsidence prediction over longwall panels has been in large part on determining the profile functions for the major cross-sections of a subsidence basin. In this approach, the surface monuments are usually laid out along the major cross-sections and thus, the subsidence profiles developed are restricted for subsidence prediction along the major cross-sections. However in practice many monuments or surface structures for which subsidence prediction for damage evaluation is required, are not laid out along the major cross-section of the basin. In such cases, it is difficult to get either the empirical profile function for the cross-sections where these structures are located or to predict their subsidence based on the profile function developed for the major cross-sections. Therefore, there exists a strong need to develop a subsidence basin function with a reasonable degree of accuracy, which can be determined or confirmed by the data of scattered monuments on a surface basin. The same subsidence basin function can also be used for prediction of subsidence for any arbitrary points over a longwall panel. In 1982, He (1) proposed the clastic theory, for which he developed the basic differential equations describing the movement and deformation of overburden due to underground mining, and performed the selection of best solution for the equations. He found that the Weibull dietribution is the optimal solution. The Weibull distribution has three parameters that vary to fit the subsidence profile so well that the profile function derived from it provides a high degree of accuracy in subeidence prediction. However the results

Jan 1, 1986

By Tom Martin

Mega projects present unique challenges with regard to estimating costs. With such projects, which may span decades, these challenges often begin as soon as a project is conceived. The importance of having a sound, resource based estimate avail-able early in the process cannot be overstated because it provides the basis for ongoing project decisions. For the final phase of providing an updated cost estimate, often while bidding by contractors is underway, the Engineer?s Estimate (EE) must incorporate present market conditions; account for possible volatile material price swings; be based on actual labor and fringe costs; rely on meaningful productivity rates; and accommodate any recent technology advances while identifying and allowing for risk factors. This paper explains the benefits associated with consultants adopting a contractor?s estimating approach when preparing the Engineer?s Estimate on mega projects like the various tunneling projects in New York City.

By G. Folmo

Allis Mineral Systems' GRATE-CAR agglomeration/induration/reduction process is currently being operated to process ilmenite at Tinfos Titan & Iron KS in Tyssedal, Norway. In this process, balled ilmenite concentrate is fed to a traveling grate where pellets are dried and preheated, using fully oxidized kiln exhaust gas. Hot preheated, semi-indurated pellets are fed directly to a ported kiln where reduction of the ilmenite's iron oxide fraction occurs in the presence of lump coal. The reduced pellet sand coal char are discharged from the kiln to an indirect rotary drum cooler. Cooled pellets and char are screened and magnetically separated prior to their further processing in a downstream smelting operation. The pellets are melted and the titanium dioxide and iron are separated. Operation commenced in late 1986.

Jan 1, 1992

By G. D. Mainwaring, Weng L. W, Lam Y. K.

The first power transmission cable tunnel in Singapore was the 2.6km long undersea tunnel between Pulau Seraya and mainland Singapore, constructed in the1980s. Ten years later, similar concepts were used for the Tuas Cable Tunnel. The tunnel, which includes a 2.2km long immersed tube section, was designed to accommodate 10power circuits of 400kV and 230kV capacity. It is fully equipped with sophisticated control and communication equipment, fire suppressant and life safety systems plus a maintenance vehicle which runs on tracks through the length of the tunnel. The paper discusses the planning, design, and construction of the Tuas tunnel, and the development of these concepts for future tunnels.

Jan 1, 2001

By R. P. King

The MODSIM mineral processing plant simultor is used to find optimal combinations of target separation specific gravities in a typical modem coal washing plant. A plant that is set up with these optimal targets can deliver up to 10% more yield at the same ash content as the same plant set up with separation targets chosen by conventional methods. MODSIM is the only simulator currently available that can simulate the liberation of pyrite and other mineral matter during open- and closed-circuit grinding operations. The simulator can therefore be used to assess the benefits of grinding operations in the flowsheet.

Feb 24, 1997

By V. O. Tenorio, K. P. Hague

Mines are constantly trying to improve production processes by optimizing work cycles, reducing operational delays, minimizing costs, controlling equipment utilization, and preventing occupational hazards. Currently, advances in digital mining technologies within the concepts of 5G and Industrial Touch Internet are allowing better control and monitoring of underground mining equipment, with centralized control systems that unify data analysis for proper decision making. A wireless 5G-based platform for controlling and monitoring systems for underground mine operations can be designed over a comprehensive layout in where bandwidth selection, sensor location, Wi-Fi repeaters and power distribution are put together to build a successful supervisory system. In order to confirm the validation of these concepts, a case study is proposed for a medium-sized underground mine with a multi-level network which includes tablets managed by production supervisors, along with other data collection devices installed in semi-autonomous mining equipment, collecting, and distributing data in near-real time, with interconnection to support and services areas on the surface.

Mar 2, 2022

By I. Tsolas

This paper presents the use of non-parametric approach (i.e., data envelopment analysis, DEA) for the development of environmental sustainability indicators in mineral processing using environmental, economic and/or integrated indicators (i.e., indicators that interrelate two dimensions of sustainability). A case study based on real publicly available data is presented to illustrate how the proposed approach can be implemented in practice. The merit of this approach, which is based on the productive efficiency framework, is that it provides environmental sustainability indicators that can be used internally for benchmarking purposes and externally for sustainability reporting.

Jan 1, 2008

By T. Rasmussen, T. G. Jørgensen, T. Fischer, R. K. McLimans, C. Knudsen, D. Frei

Ilmenite-bearing paleo-beach deposits were discovered in Jylland, Denmark using a combination of Ground Penetrating Radar (GPR), portable X-ray fluorescence (XMET), bulk XRF analyses, Computer Controlled Scanning Electron Microscopy (CCSEM), and wire line logging. The Miocene-age paleo-beach deposits are located below a thin Quaternary cover in a region of very moderate relief and essentially no outcrop demanding unique approaches in exploration. Initially, an isopach map of the Quaternary is prepared from existing water well data. A geological model for likely occurrence of Miocene paleo-beach deposits is generated and the coincidence of thin Quaternary cover and potential paleo-beach deposits define targets for detailed exploration. The defined targets are traversed with GPR to identify paleo-beach structures which are then used to define a drilling program. This methodology located a paleo-barrier island at the Vorslunde location with more than 10% ilmenite in the sand. During the drilling process, the TiO2 and heavy mineral contents of the sand were logged every meter with a portable XRF unit (XMET) and subsequently calibrated more accurately by comparison to bulk XRF and CCSEM analyses for selected samples. The bulk XRF data also provided more complete compositional information. Insitu determination of geology, heavy mineral abundance, and corroboration of the XRF logging was done using wire line logs, a combination of spectral gamma and induction conductivity logs. Detailed characteristics (abundance, grain size, shape) and chemical composition of minerals was determined by the GEUS CCSEM methodology (Frei et al, this vol.). The average weight percent TiO2 for all Ti-minerals is 62%, 60% excluding rutile. That elevated TiO2 content (>> ilmenite stoichiometric value, ca. 50 %) indicates that ilmenite experienced an iron-leaching environment. The source of the sand deposit was investigated by dating contained zircon. The results show that the likely sources of zircon are in southern Norway and southwestern Sweden with common zircon ages of ca 1100 Ma. and 1500 Ma.

Jan 1, 2005

By Z. Henderson, J. Saylor, L. R. Mendoza

"Diesel particulate Matter (DPM) is a byproduct of fuel combustion in diesel engines. It is classified as a carcinogen, with associated respiratory and cardiovascular health effects. The composition, size, and concentration of DPM is dependent on factors such as engine type, loading and fuel composition. Though a number of DPM abatement and control strategies currently exist, particularly in underground mining environments, occupational exposures remain a serious health concern. As a novel abatement approach, DPM scavenging by fine water or “fog” droplets has been proposed and a laboratory set-up has been built to test the efficacy on engine exhaust. Here, we describe a series of tests that varied engine load, system flow rate and fog drop number density. While none of these factors had overwhelming effects on the results within the ranges tested, the improvement in DPM mass removal attributed to the fog treatment was about 45% on average in comparison to no treatment. INTRODUCTION Diesel engines have seen widespread use for well over a century due to their relatively high thermal efficiency and fuel economy1. More recently, however, adverse health risks of diesel exhaust have become increasingly clear. Many of these risks are associated with the physical and chemical properties of exhaust components1–3. The term diesel particulate matter (DPM) is used to refer to the solid components of diesel exhaust, which are a mixture of elemental and organic carbon (EC and OC) and minor constituents including sulfates and metal ash3. The OC fraction of DPM results from unburned fuel and lube oil, whereas EC or soot is formed during the combustion of locally rich regions within the fuel. DPM is classified as a carcinogen6,7 and epidemiological studies have demonstrated a positive correlation between long-term exposure to DPM and other combustion-related fine particulate and increased cardiovascular and pulmonary diseases8,9. Diesel engines operate in relative fuel rich/oxygen lean conditions and are characterized by relatively high emissions of particulate as compared to spark-ignition engines2,3,10. Typically, these emissions range from 107 – 109 particles/cc and cover two primary size ranges: the nuclei mode where particles have diameters less than about <50 nm, and the accumulation mode where diameters are from about 50-10,000 nm. Most OC resides in the nuclei mode as semi-volatile compounds, while most EC is in the accumulation mode3. The physical and chemical properties of DPM vary with the type of engine, fuel (e.g., petro- vs. bio-diesel) and operating conditions such as loading (i.e., a function of torque and rotational speed)2,3,9,11,12. Loading is a particularly important factor with respect to DPM toxicity9,13,14, and on the effectiveness of after-treatment technologies2,3,15. Engine load alone can affect the EC/OC ratio, and the size distribution and number density of DPM. For diesel engines, the load is roughly proportional to the equivalence ratio3, defined as the actual fuel/air ratio over the stoichiometric fuel/air ratio for complete combustion. Light loads generally favor the formation of OC and small particles. As load is increased the volatiles are oxidized leading to larger soot particles (i.e., EC), but lower total number density of DPM. With further loading, the formation of soot offsets the decrease in volatiles, resulting in increased DPM mean size and number density3."

Jan 1, 2017

By R. L. Grayson, S. S. Eslambolchi

"In making strategic economic decisions, it is important for a mining company to gain insights on the impact of significant political, social and economic issues when planning for present and future mines. The size of any mine, measured by the average number of employees working in the mine, will likely vary according to the pressures generated by the significant issues from one year to another. The objective of this study is to develop a model that represents U.S. underground coal mine size transitions during the period 2002-2012 using data derived from the MSHA databases. Coupled with information on significant issues over the past ten years, this model is used to gain insight on the impact of the issues on mine sizes. Results indicate that the structural impact of the combined driving pressures can be discerned by examining the year-to-year stability of mine-size categories. The effects of The MINER Act, the Obama Administration environmental policies on coal, and the coal market are evident. The lessons learned from these analyses give good insights on what the industry and market responses have been on the structure of the underground coal industry over the period of study. INTRODUCTION It is apparent that key driving issues affect the structure and viability of the coal industry. The driving issues may be political, social, and/or economic in the final analysis, but are generally rooted in reaction to dramatic and publicized events or movements. Mine disasters, an increase in miners’ disease prevalence, strife in the coal fields, and negative environmental impacts on air, land or water can capture the attention of the media and the public. Some of the issues occur over a long period of time, like the current global climate change movement. The coal industry veteran can sense the changes in political and social sentiment, and attempt to react to the economic repercussions; however, the insights from the media and from unique combinations of driving pressures are difficult to fathom. Thus decisions made on inadequate information related to the driving pressures and their likely impacts could lead to missteps in corporate and market restructuring. One way to gain some more insight on the potential impacts is to examine the complicated restructuring of mine operations in reaction to the driving pressures of the recent past. This paper examines an 11-year history of the changes in the underground coal industry structure, as reflected by changes in the numbers of mines in various statuses by mine-size categories. Superimposed on the results of mine-size changes is a mapping of the key driving pressures that occurred over the same period, 2002-2012. It is assumed that using this methodology, some important insights can be gained on the immediate and delayed responses to the driving pressures during that period."

Jan 1, 2015

By T. Stauffer, B. McGunegle, A. Adu-Acheampong

The Fairmount Minerals, Inc., Maiden Rock underground sand mine historically delivered air to ventilate diesel-powered equipment at its working faces through high-resistance, 15-inch-diameter PVC distribution lines. In support of plans for expanded production, three new, low-resistance ventilation design alternatives were analyzed. The study determined that adequate ventilation for expanded production was possible with various commercially-available, high-volume/low-pressure fans combined with a systematic layout of control structures. The recommended re-design was implemented in 2001, resulting in a significant increase in flow volumes and a noticeable improvement in the mine environment.

Jan 1, 2007

By J. D. Noll

An effective technique to minimize miners? respirable dust and diesel exposure on mobile mining equipment is to place mine operators in enclosed cabs with designed filtration and pressurization systems. Many factors affect the performance of these enclosed cab systems, and one of the most significant factors is the effectiveness of the filtration system. High-efficiency particulate air (HEPA)-type filters are typically used because they are highly efficient at capturing all types and sizes of particles, including those in the submicron range such as diesel particulate matter (DPM). However, in laboratory tests, minimum efficiency reporting value (MERV) 16 filters have proven to be highly efficient for capturing DPM and respirable dust. Also, MERV 16 filters can be less restrictive to cab airflow and less expensive than HEPA filters. To verify their effectiveness in the field, MERV 16 filters were used in the enclosed cab filtration system on a face drill and roof bolting mining machine and tested at an underground limestone mine. Test results showed that DPM and respirable dust concentrations were reduced by more than 90% when the cabs were properly sealed. However, when the cab door was opened periodically throughout the shift, the reduction efficiency of the MERV 16 filters was reduced to 80% on average.

Feb 1, 2014

By M. Sadegh Safarzadeh, Stanley M. Howard

The two-dimensional predominance area (Kellogg) diagram (PAD) surfaces bounding the three-dimensional Cu-As-S-O system were constructed at 900 K. The computations employed gases As4O6(g), O2(g), and SO2(g) as the independent coordinate species to generate diagrams of As4O6(g) − O2(g),O2(g) − SO2(g), and As4O6(g) − SO2(g), while the third gas (As4O6, O2, or SO2) was fixed. The results indicate that there is no shared boundary between enargite (Cu3AsS4) and copper sulfate (CuSO4); however, at PO2 < 10−6 atm, PAs4O6 < 10−10 atm, and PSO2 > 10−4 atm, CuSO4 is the stable phase at 900 K. The chemical driving force for oxidation of intermediate phases between enargite and copper sulfate is substantial except for basic sulfate (CuO · CuSO4).

By M. Sadegh Safarzadeh, Stanley M. Howard

The two-dimensional predominance area (Kellogg) diagram (PAD) surfaces bounding the three-dimensional Cu-As-S-O system were constructed at 900 K. The computations employed gases As4O6(g), O2(g), and SO2(g) as the independent coordinate species to generate diagrams of As4O6(g) − O2(g),O2(g) − SO2(g), and As4O6(g) − SO2(g), while the third gas (As4O6, O2, or SO2) was fixed. The results indicate that there is no shared boundary between enargite (Cu3AsS4) and copper sulfate (CuSO4); however, at PO2 < 10−6 atm, PAs4O6 < 10−10 atm, and PSO2 > 10−4 atm, CuSO4 is the stable phase at 900 K. The chemical driving force for oxidation of intermediate phases between enargite and copper sulfate is substantial except for basic sulfate (CuO · CuSO4).

By André Vervoort

After the systematic closure of Europe’s coalfields in the late twentieth century, the emphasis is now clearly on industry’s environmental legacy. One aspect of the latter is the longterm surface movement above abandoned coal mines. The analysis of satellite data shows that the subsidence lasts longer than generally assumed. However, a few years after the flooding of the abandoned underground coal mines, a new phenomenon was observed, i.e., the direction of the surface movement was reversed. The phase of upsidence has already lasted for several decades, and only future measurements will tell how long it continues. A key conclusion is that the regions with maximum subsidence do not necessarily correspond to the greatest upsidence. In other words, buildings and infrastructure are subjected to a different loading from this upsidence than during the subsidence phase. The longterm surface movements have an impact on vulnerable structures in the densely populated regions of the former deep coal mining areas in Europe. These movements create additional damage. This new knowledge is also relevant for mines that are still in operation or future mines that are planned.

Feb 1, 2024

By A. Bergmann

Location The Meggen Mine and the concentrator plant of the "Sachtleben Bergbau G.m.b.H." are located in the southern part of the Ruhr-district of the Federal Republic of Germany. The mine has been in operation for more than 100 years, but the concentrator described in this paper was built in 1962 and started up in January 1963. Goelogy and Mining The Meggen ore-body is of sedimentary origin and occurs in a zone of limestones, graywacke and shales of Devonion age. The average thickness of the deposit is 3 meters and, due to an intense folding of the area, the mineralized zone dips very steeply at 800 toward the north. The ore consists of 85 percent of sulfides and 15 percent gangue that mainly contains silicates from the host rocks. The principal ore minerals are pyrite (67 percent), sphalerite (16 percent) and galena (2 percent) with minor amounts of marcasite and only traces of chalcopyrite. As shown in Fig. 1, the sphalerite and galena are very finely disseminated in the massive pyrite of the Meggen ore, and a very fine grinding combined with a special flotation technique are required to liberate the valuable sulfides and to produce separate concentrates of lead, zinc and pyrite. Mining is performed by the sub-level stoping method and employs trackless equipment. Present operations provide ore from the 600 meter level. Annual ore production is 870,000 metric tons.

Jan 1, 1972

By W. McMahon

Following the Sago Mine accident, the Mine Safety and Health Administration (MSHA) asked the U.S. Army Engineer Research and Development Center to study several possible methane explosion scenarios in the Sago coal mine. The study used a 1-ft resolution map of the mine to produce a 3-dimensional (3-D) model of a portion of the mine, including the sealed area where the explosion occurred. An advanced 3-D computational fluid dynamics (CFD) code was used to calculate the explosion pressures within the sealed area, on the mine seals, and in nearby regions of the mine. Based on the best available information on methane concentrations and assumptions on homogeneity and on layering and mix composition, three separate initial conditions of methane-air concentrations and location were studied. This paper discusses the CFD modeling technique, the results of the calculations, the challenges of conducting this type of modeling, and the advantages and limitations of CFD modeling of accident investigations of mine explosions.

Jan 1, 2009

By I. M. Ahmed, R. S. Hassan, M. I. Aly

Extraction and separation of La, Sm and Dy ions from acidic sulfate-phosphate solutions was investigated using a cation exchange extractant, bis(2,4,4-trimethylpentyl) phosphinic acid, CYANEX 272, in kerosene. The influence of shaking time, equilibrium pH, extractant, sulfate and phosphate ion concentrations, diluent type and temperature was studied. The extraction was found to be pH-dependent, and increasing the phosphate ion concentration inhibited the extraction which was found to be endothermic. The stoichiometry of the extracted metal species was found to be MOH.H2OHSO4H2A.A2. Aliphatic diluents were found to enhance the extraction compared to aromatic diluents. The results showed that there was a separation mode between the metal ions when varying the hydrogen ion and sulfate ion concentrations, under the used experimental conditions. The investigated process was used for the recovery of La, Sm and Dy from the acid solution resulting from the leaching of low-grade monazite.

By E. R. Bauer

Previous studies and research efforts have shown that noise-induced hearing loss (NIHL) is a problem in the U.S. mining industry. This is especially true in surface and underground coal and stone mining where large, noisy equipment predominate. Workers in coal preparation and stone processing plants have also been found to be subject to high sound levels that could potentially cause NIHL over prolonged periods of exposure. National Institute for Occupational Safety and Health (NIOSH) researchers have been conducting a cross-sectional survey of equipment noise and worker noise exposures in the mining industry to estimate the potential for NIHL within the mining community. One commodity recently surveyed was the extraction of sand and gravel from surface pits and by river dredging. Little is known about the noise environment and worker exposures in these environments, where processing and mining equipment similar to coal and stone are employed. To address the potential for NIHL in the sand and gravel industry, sound levels on and around the dredges and processing equipment were recorded to identify areas of high noise levels. Full-shift worker dosimetry, in conjunction with task observations, was documented to determine the relationship between exposure and source. This paper presents research examining noise on dredges, in several surface mine sand and gravel operations and in the processing facilities. The locations where workers are likely to be overexposed and were found to be most susceptible to noise overexposures are reported. Results indicate that there are areas on the dredges (crane, suction pumps, and diesel engines) where sound levels greater than 90 dB(A) are present. In addition, crushers and screens used in the processing of the sand and gravel also generate sound levels greater than 90 dB(A). Although no surveyed worker exceeded the Mine Safety and Health Administration (MSHA) Permissible Exposure Level (PEL) of 90 dB(A) TWA8, laborers, mechanics, oilers, helpers, pickers, and greasers are the workers likely to be exposed to hazardous sound levels and thus develop NIHL over time. Knowledge of the equipment noise, area sound levels, and worker dose levels is information that management and employees can use to reduce exposures. Exposures can be reduced in certain areas through administrative controls and through engineering controls applied to the noisiest equipment.

Jan 1, 2008