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By T. M. Ruff, W. G. McCoy, M. J. Beus, S. Iverson, W. Hasz

Technology to enhance safety during mine hoisting has been developed by researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health. Assessment of current hoisting technology suggests that monitoring conveyance position and load directly from the skip or cage top offers several significant safety advantages. Wireless data transmission schemes and a package consisting of sensors, batteries, and a charger mounted on the wire rope and skip have been developed. A state-of-the-art automated hoisting test facility was constructed to test the concept in a controlled laboratory setting. Field tests in a full-size shaft are underway.

Jan 1, 1999

By N. B. Aughenbaugh

A study was made to determine those petrographic parameters that are correlative with carbonate-aggregate quality as indicated by the Los Angeles abrasion and absorption tests. Samples collected at 28 sites in northern and eastern Indiana were analyzed petrographically, chiefly for void content, grain size, grain-size variation, grain shape, and grain interlock. Most of the sampled sites are in the belt of Silurian rocks of east-central and north- western Indiana. Though a few sites lie outside this belt, most of these have only a thin Devonian section above the Silurian. Three sites are non-Silurian and are included for comparison. Most of the samples studied are from Middle and Upper Silurian units. Both biohermal and nonbiohermal facies are included. The biohermal rocks are typically dense but vugular, finely crystalline granular dolomite. Nonbiohermal facies are porous, medium to coarsely crystalline, granular dolomite with dolomite rhombs The Los Angeles abrasion losses ranged from 20 to 46 per cent, the rocks in the eastern part of the state showing the higher values. Absorption tests indicate the same general quality trend. Comparison of petrographic studies with Los Angeles abrasion- and absorption-test results indicate the following correlations. (1) As per, cent of voids increases, quality decreases. (2) As average grain size increases, quality decreases. (3) Variations from mean grain size appear to have no effect on the quality. (4) As angularity and roughness of the grains increase, quality increases. (5) As grain-to-grain interlock increases, quality increases. Variations in the calcium-magnesium ratio have no apparent effect on aggregate quality, except as they affect the texture.

Jan 1, 1966

By D. L. Madge

The text of this chapter was not received in time for printing.

Jan 1, 1979

By M. T. Worley

Joint Development Associates International, Inc. (JDA) began humanitarian relief and community development in Central Asia in1992, following the collapse of the former Soviet Union. Appropriate technology has played an important role in their efforts to assist those segments of society that are most vulnerable to poverty and disease. Three case histories are described to illustrate the successful implementation of simple, but effective technology in community development.

Jan 1, 2004

By A. Iordanidis

Mining activities have recently been taken place in Vourinos mountain, northern Greece, exploiting the so-called ?olivinite?. A representative sample was collected from this mining area. Mineralogical analysis was conducted using X-Ray powder Diffraction (XRD). A thin section was prepared and analyzed under optical microscope. X-Ray Fluorescence (XRF) was employed for the chemical analyses of major, mi-nor and trace elements. Environmental Scanning Electron Microscopy coupled with energy dispersive x-ray analysis system (ESEM-EDX) was also applied for the characterization of the sample. Forsterite (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were the main mineral phases determined by XRD, with a 56% and 44% content respectively. Trace amounts of chromite spinels were also determined. Based on this characterization, the industrial rock proved to be a hartzburgite (a type of peridotite in petrological terms). Optical microscopy and ESEM-EDX provided similar observations and confirmed the above-mentioned results. XRF revealed a composition of 43.31 MgO, 44.25 SiO2, 9.98 Fe2O3, 1.40 CaO, 0.67 Al2O3, 0.22 MnO, 0.01 TiO2 and negligible amount of LOI (<0.1%). Trace elements with high concentrations were Cr (2678 ppm) and Ni (2044 ppm). The comprehensive characterization of this mining product suggested the suitability for various uses, such as refractories, foundry and slag conditioner. Additional experiments are being carried out for environmental applications, e.g. wastewater treatment.

Jan 1, 2006

By James R. Runkle

Studies in eastern Ohio, northern West Virginia, and southwestern Pennsylvania determined whether subsidence caused by longwall mining influences soil moisture and tree growth. Soil moisture was measured both over new longwall panels and over an unmined control area throughout the growing seasons of 1990, a wet year when the panels were excavated, and 1991, a dry year. No significant effects of mining could be detected. Tree growth was studied in two pairs of woodlots. In each pair, one woodlot was located over a longwall panel excavated about 1980 and the other over an unmined area. Differences in tree growth between mined and unmined areas were neither significant (for most species) nor consistent in direction. The above results imply that if mining does have impacts they are likely to be highly site-specific and localized such as by disruptions of springs or soil slippage.

Jan 1, 1986

By Biao Qiu

Longwall and/or room-and-pillar mining operations in multiple coal seams could not only induce subsurface and surface subsidence but also cause interactions between these mined coal seams. The interaction might destabilize mine structures and subsequently induce additional strata movements. Mechanical models to utilize the predicted subsurface deformations to assess the interactions and the consequences have been developed. The models are incorporated into a computer program, CISPM-MS, for predicting the final surface movements and deformations as well as the mining interactions associated with multi-seam coal mining operations. It predicts final surface movements and deformations caused by the individual mining operations and by the interactive effects. The program can also be used to assess mine structural stability in multi-seam mining operations. The paper presents the developed interaction models and their application in surface subsidence prediction caused by multi-seam mining operations. A case study involving mining in two coal seams, using longwall and room-and-pillar mining methods, respectively, will be used to validate the program.

Jan 1, 2013

It took me nearly nine months to make the move from Arizona to Berkeley, opening an office and planning our new home. While I was in Warren Dorothy had rented two rooms for my office In the new California Commercial Union Building at 315 Montgomery Street in San Francisco. She made such a good choice that this remained my address for more than 50 years Dorothy had also looked over many lots In Berkeley, and took an option on the one that pleased her the most. It was a beautiful lot, or rather three, as we took three lots to protect our view. The only possible drawback was that it was in a new district and there were only two houses within two blocks. No one could tell how the area would develop but we liked it so much that we bought the lots on the spot and signed a note to guarantee payment. Dorothy&apos;s good judgment was shown by the fact that after 50 years we are still glad to be living on the same property, at 168 Southampton Avenue. We arranged a meeting with the distinguished architect Bernard Maybeck-and employed him to design a house for us. Dorothy spent most of her time with Maybeck planning the house and an attached studio for her, and she later wrote an amusing essay on her dealings with Maybeck. They were so successful that even now we could not think of any changes we would have wanted. It took several months to design a house that suited Dorothy and would fit on our hilltop. I was glad to overcome some of Maybeck&apos;s scorn for "only an engineer" by showing how, by rotating the studio addition 45º, it would fit the lot without serious excavation. We finally signed a contract with Maybeck, borrowing so much money that it scared us. First Consulting After short jumps to the gold mines in the Secret Pass District near Kingman, Ariz., and to the Espiritu Santo prospect adjoining the rich

Jan 1, 1976

By George M. Potter

Precious gold and silver markets support substantial activity in the search for and development of improved and unconventional ore and tailing processing methods. The need for such methods 1s strengthened by consideration of increasingly low grade and refractory ores and old tailing reserves. As background for this review of new and unconventional precious metal processing, recent USBM data (1981) show annual world gold production of about 40.8 million troy ounces. In the U.S. about half the 2.8 million ounce consumption was used for jewelry and the arts, 39 percent for industry, and 8 percent for dental purposes. World silver production in 1981 was about 365 million ounces. Domestic usage the same year was about 117 million ounces. More than $ was used for photography and 30 percent for electrical and electronics. By process, about 1 percent of U.S. production of gold came from amalgamation, 66 percent from cyanidation, 31 percent from smelting ores and concentrates, and 2 percent from placers. As for silver, about 11 percent is from cyanidation and 89 percent from smelting ores and concentrates. Evidently the search for innovative and unconventional precious metal processes must include gravity concentration, froth flotation, hydrometallurgical, and electrometallurgical methods. Although smelting processes are equally important, they largely comprise nonferrous metal technology, and are not discussed here.

Jan 1, 1984

By C. Manea

During exploration and exploitation of complex ores, waste dumps that contaminate severely the environment and in particular soils, are genetated. The most hazardous pollutants are heavy metals and metalloids (e.g As, Mo, Pb and Cu) as well as radionuclides (e.g U and Ra). Ecological remediation aims, among others, at decontamination of soils by preserving important properties as soil fertility.

Jan 1, 2008

By Richard H. De Voto

The Pb-Zn-Ag deposits within the Lower and Middle Paleozoic strata of central Colorado (Leadville, Gilman, Aspen, and others) occur principally in Late Mississippian karst-solution features within dolomites and, to a lesser extent, limestones. Several un- conformities within the Devonian and Mississippian carbonate rocks and the subregional dolomitization of the Leadville (Mississippian) Formation that occurred during the Late Mississippian resulted from recurrent uplift of elements of the Ancestral Sawatch, Gore, and Front Range areas within central Colorado. Uplift of these areas also strongly influenced the details of the extensive karst topography that developed during the Late Mississippian. In particular, uplift of the Sawatch Range area caused paleovalleys from 300-600 ft deep to form on the karst landscape. The pattern of karst-solution caverns, sinkholes, cutters, channelways, and breccia-rubble zones was strongly controlled by incision of surface drainages and the strong northeast-trending Mississippian joint system. These subterranean karst-solution features and breccia-rubble soil [ ] zones are the primary controls of the location of the Pb-Zn-Ag ore deposits in these rocks. In the Leadville and Aspen districts, the deeply incised paleovalleys occur immediately adjacent to the principal areas of mineralization. Pennsylvanian deposition of a thick terrigenous and evaporite sequence occurred within central Colorado in response to actively subsiding extensional basins and adjacent high-relief uplift areas. Hot brines developed within the Pennsylvanian strata, migrated laterally to, and moved upward vertically along, basin- margin faults during continued Pennsylvanian subsidence and deposition. These metal-rich brines migrated into karst-solution features within the Lower and Middle Paleozoic dolomites and limestones, principally within the Leadville Formation, in basin- edge uplifted locales where the Pb-Zn-Ag minerals were precipitated. Field relationships, mineral assemblages and paragenesis, fluid-inclusion data, and isotope studies suggest that the metals and brines were derived within the Pennsylvanian sedimentary sequence and that the ore minerals were deposited under different temperatures and at different depths from deposit to deposit. Chemical reaction with the carbonate cave sediment and wallrock, cooling of fluid temperatures, and mixing with meteoric ground waters were the probable combined causes of mineral deposition in the karst-solution features. Late Cretaceous-Tertiary intrusive activity has subsequently modified some of the primary Pb-Zn-Ag deposits in local areas.

Jan 1, 2013

By Gennaro G. Ph. D Marino

In order to improve handling of subsidence damages the Illinois Mine Subsidence Insurance Fund supported the development of novel cost-effective methods of repair. The research in developing the repairs was directed towards the most common and costly damages that had been observed. As a result repair techniques were designed for structurally cracked foundations in the tension zone; structurally cracked foundations in the compression zone; and damaged or undamaged tilted foundations. When appropriate, the postulated methods would result in: 1. significant cost savings (over conventional procedures); 2. a structural capacity greater than when the foundation was untracked; and 3. an aesthetic appeal. All the postulated repair methodologies were laboratory and/or field tested. The paper will summarize the essentials of each technique developed and the test results.

Jan 1, 1986

By J. H. Tu

The technical paper correctly points out that the kriging variance is not a good measure of the uncertainty of the estimated (i.e., kriged) value of individual blocks. The authors claim that their proposed jack-knife method, which is a rekriging of each block by eliminating, in turn, one sample from m the original sample set and then taking the average of the rekriged estimates, not only gives good block estimates, but the resulting jackknife kriging standard deviation is a useful indicator of the "true uncertainty associated with block estimates." However, they immediately abandon the idea of using the block-by-block standard deviations, reasoning that these standard deviations are not independent and that there is no easy way to utilize them. There may be another reason for not using them. The jackknife standard deviations for individual blocks given in their example are mostly in the range of 0.004 to 0.005 oz/st (0.14 to 0.17 g/t) with only one block having a high value of 0.012 oz/st (0.41 g/ t). These individual block standard deviations are as low as the jackknife standard deviation for the mean grade of the entire shape, i.e., 0.0041 oz/st (0.14 g/t). Do they represent the "true uncertainty" .of the individual block estimates? Could the authors explain this? In a global shape consisting of a large number of blocks, any given sample will affect the kriged estimate of only those few blocks within its vicinity. This is the rationale for the authors&apos; selective rekriging, making the jackknife algorithm more efficient. On second thought, why not do away with jackknifing altogether? Just cumulate and normalize, if necessary, the kriging weights of each sample used during the ordinary block kriging process, and then compute the global variance from these kriging weights and their respective sample grades? After all, isn&apos;t the global mean grade nothing but the weighted average of the samples used in the estimation? Reply by G.S. Adisoma and M.G. Hester The jackknife is one of the many tools in a practitioner&apos;s toolbox to solve estimation problems. The strengths of the technique lies in its simplicity, i.e., it uses the concept of mean and standard deviation and the fact that it can be easily combined with other tools, in this case kriging. Because the jackknife kriging (JK) estimate is also the mean of the pseudovalues, the JK standard deviation is attractive just as the standard deviation of the mean explains the variability of the data. The difference is that the pseudovalue calculation in jackknife kriging uses the ordinary kriging (OK) weighting scheme instead of simple arithmetic averaging. The data used to illustrate the jackknife technique in the paper con¬sist of high values that are roughly three times the low values. The resulting JK estimate of the block grades show that the highest estimate is roughly twice the grade of the lowest estimate. The contrast between the low and the high estimate is more evident in the JK estimate than in the OK estimate, even though the mean grades of the blocks for the two estimates are very similar. Nonetheless, in this paper, we are concentrating more on the need for a more realistic measure of uncertainty, or precision, for the estimate. Unlike its OK counterpart, the JK standard deviation of the blocks clearly reflects the original data variation. The highest JK standard deviation of the blocks is three times its lowest value. This follows our intuition that, when the samples used to estimate a block is more variable, the resulting estimation variance (or standard deviation) should be higher than the case where the samples are more uniformly valued. However, block-by-block standard deviation or variance is of little practical value in reserve estimation and classification, as well as in mine planning. One is usually more interested in quantifying not the variance of the individual block estimate, but the uncertainties associated with a much larger dimension, such as the minable reserve. Thus, the thrust of the paper is to find a simple way to obtain a single estimation variance or standard deviation associated with the reserve grade estimate. The discussion by J.H. Tu did not mention how one would obtain the global variance from the OK weights and the sample grades. As a technique that offers a data value-based measure of uncertainty for its estimate, the "leave-one-out" jackknife fills this need nicely through the block kriging shortcut approach described in the paper. Note: The first column and the last two columns of Table 3 in the paper should have contained a single number each, namely, an OK estimate of 0.0317, a JK estimate of 0.0333 and a JK standard deviation of 0.0041 oz/st, respectively, for the shape, as are obvious from the text.

Jan 1, 1997

By G. Sanders

The studies reported on in this paper were initiated to draw attention to the severe contamination problem in the Section 30 drilling program at Chimney Creek. The lithologic-subset sampling study reached a different conclusion from that presented in your paper, and I wish to comment on your subsequent analysis of the data and your conclusions. Request for more complete data In the section on subsampling, you mention that the subordinate lithologies were separated and sampled, yet only the dominant-lithology gold value is plotted in Fig. 4. In a contamination study, the reader is interested in the assay values for the individual subsets. Please include a table of the subsample assay data in your reply. Also, please indicate which analytical methods were used to arrive at the gold values in the subsampling study. Turning barren rock into low-grade ore Figure 5 is very revealing and typical of all of the cross sections in Section 30. Note the long strings of low-grade mineralization spread out for hundreds of feet below the ore zones. There were some very high gold values found in certain contaminated fractions during the subset sampling. The conclusion, here, was that the distinctive, strongly-mineralized dolomite layer was probably loose and crumbly and continued to disintegrate during drilling. This caused salting of the unmineralized rock samples below.

Jan 1, 1993

By M. P. Meehan

The purpose of this paper is to present the key elements in a system; study of the electrical system for a timing and/or tilling operation. The ability of an electrical system to function in a reliable fashion at its proper levels is essential for an operation to be successful. A system study consists of a load study for determining the capability of the electrical network to provide power to the various loads and a short circuit study for determining the capability of the electrical protective equipment to properly protect against fault conditions. The sequence of events in a system study is data acquisition, determining the electrical parameters and analyzing the ability of the system to meet these requirements. If the system is small, herd calculations will be the manner in which the study will be conducted; if it is large then commuters will be used. A load study has as its objectives the determination of the capability and reliability of the source of power, transformers and conductors to satisfactorily deliver power to the loads at an acceptable voltage level. The Information required is a single line diagram showing the source, transformers, conductors and loads.

Jan 1, 1980

By V. L. Magnus

The text of this chapter was not received in time for printing.

Jan 1, 1979

By D. Nilsson, B. Aaro

To find out if there are any potential savings in "in-the-wall haulage for open pits," the Swedish companies ASEA and Kiruna-Truck in 1984 gave us financial support to study this solution in more detail. In the study, the use of in-the-wall haulage was studied for three hypothetical open pits with different sizes and shapes. Annual ore production rates also varied. A part of this thor¬ough study was published by the Swedish Mining Research Foundation (see Report F 8444, "The Use of Electric Trucks and In-the-Wall Haulage in Open-Pit Mining," in Swedish with an English Summary). Although in-the-wall haulage is of interest in some open pits, the local terrain is important for profitability. The authors do not think in-the-wall haulage is of any major interest for the mining industry. The following is a summary of some of the author&apos;s findings. To place the haul road in the wall is not of interest in open pits with declining metal contents in the bedrock. In such mines, the volumes from the haul roads will not yield reve¬nues. The cost per m3 for an underground haul road is much higher than for a haul road in the pit. This means that it is only of interest to place the haul road in the wall when mining gets deeper than about 50 m (165 ft). In-the-wall haul roads will reduce flexibility in the pit, and it will make necessary the use of smaller equipment with lower productivity and higher costs per ton. As Hustrulid, et al. show (Table 4), excavation savings of material hauled are very low, $0.10 to $0.25/t (0.09 to 0.27 per st). The extra operating cost, due to lower productive equip¬ment, will normally be much higher and thus destroy the whole idea with in-the-wall haulage. If electric trucks are profitable for in-the-wall haulage, it is normally also profitable to use electric trolley assist for trucks on the haul road in the pit. But the profitability of using electric power is different in different countries, and depends on the relation between the cost for electric power and diesel fuel. In the US, diesel fuel is inexpensive compared with electricity, but in a country like Sweden, diesel fuel is much more expensive. In most open pits, the trucks have to move a considerable distange from the loader until they reach a final haul road in the wall. A trolley line along such temporary haul roads will be exposed to flyrock. It is normally less expensive to perform rock support from the open pit than from underground ramps in the wall. In Fig. 8, Hustrulid et al. gives the impression that the underground haul roads will be very close to each other. This is seldom the case. Figure 1 shows a haul road in the wall. The haul road passes through each cross-section only once. Ar¬ranging a reliable dewatering and rock support system from only one underground ramp is probably impossible. Many more drifts are therefore necessary. In our report, we also studied what would happen if the final pit slope is increased by 5°, using underground drifts in the wall. Our conclusion was that the extra cost for drifts, rock support, pumps, etc. destroys the whole idea, and that it was better to accept a higher stripping ratio with the haul road in the pit and to use conventional low-cost open pit equipment. Finally, we think it is would be difficult to try to reduce the safety factor when determining the slope angle by moving the haul road in the wall. Minimizing the risk for pit wall collapse is also important with in-the-wall haulage, primarily because men and equipment will be working in the pit, but also to guarantee many accesses between the pit and the haul road in the wall.

Jan 1, 1989

By S. Budirsky

J.B. Gwiazda&apos;s article deals with an interesting problem that has not been studied thoroughly up to now. Gwiazda has proposed a technical solution that eliminates horizontal load imposed by the supports on the roof. That load is due to a discrepancy between the trajectories of the canopy and the overlying strata. It is true that the improved lemniscate guidance system proposed by Gwiazda could eliminate the horizontal load but, on the other hand, it would represent a higher cost of the supports, and it would complicate the already complicated mechanism of powered supports. That is why we must be convinced that the proposed improvement is actually needed. From that point of view, the following questions should be elucidated. As shown in Fig. 1, the point O travels along the curve a, which produces horizontal load on the roof in the direction of the coal face. As stated by Gwiazda, "such a high load is capable of destroying the roof above the support, causing rock debris to be scattered around the face." The results of our measurements carried out in coal mines of the Czechoslovak part of the Upper Silesian Coal Basin show that the convergence in the modern type of powered supports does not exceed several millimeters (not more than 10) per hour. Similar conclusions were drawn from field measurements performed in the Polish part of the Upper Silesian Coal Basin (see S. Romanowicz and H. Szopka in Proceedings, Scientific and Technical Symposium Simmex &apos;85, Katowice, Poland, pp. 73 -83). The small vertical closure of the supports also induces a small horizontal displacement of the canopy. In addition to this, the transmission of forces between the roof and the canopy is influenced by the layer of debris on it, i.e., the canopy slides without imposing a greater horizontal load on the roof. This was deduced from field measurements of Voest-Alpine F 4/4600 powered supports equipped with rams instead of the common front lemniscate links (denoted as 1 in Fig. 5). In these supports, the pressurizing of the space of piston rod (la in Fig. 5) causes the rams to close, which induces horizontal load on the roof in a direction toward the coal face. After the setting of a support unit, the pressure in the piston rod space was found to drop, frequently to zero, because the small horizontal sliding between the canopy and the debris or inside the debris caused the horizontal reaction from the roof to fall to zero, although the debris were pressurized by vertical setting load. As a consequence, there was no horizontal load imposed by the canopy on the roof. A rise of the horizontal load was recorded only after the passage of the shearer and during lowering of the adjacent units. Thorough information on the results of the afore- mentioned field measurement is given in the paper, "Analysis of the performance of shield powered supports installed in a thick seam," published in Mechanizacja i automatyzacja gornictwa, 1982, No. 12, pp. 38-46. An English translation of the paper is available from the author. We have deduced from our observations that horizontal load imposed by the canopy on the roof in the direction toward the coal face is useful for roof control because it limits the displacement of the immediate roof toward the gob particularly during the rise working. We came to the conclusion that horizontal load on the roof toward the coal face should be induced on purpose. Could Mr. Gwiazda prove with the results of field measurements his contrary opinion? Has the small horizontal displacement of the canopy toward the face actually had an adverse effect on the roof? As shown in Fig. 2, during the setting of a support unit, the canopy imposes a horizontal load on the roof in the direction of the gob. In this case, I share Gwiazda&apos;s opinion that the horizontal load could have an adverse effect on the roof. Nevertheless, two important circumstances were neglected - the horizontal compliance of the supports and the interaction of adjacent units. The question of the compliance was analyzed precisely by I. Krumnacker in Gluckauf -Forschungshefle, 1984, NO. 5, pp. 219-223. He found that due to the clearance between the hinge pins and the eyes of the sheild and due to the elasticity of the steel structure,

Jan 1, 1988

By Charles A. Maliszewski, James M. Galvin, Gerhard Urschitz

With obvious signs of deterioration, the double track, historically registered Bergen Tunnels as part of the commuter rail system in New Jersey waited for rehabilitation for a long time. Serious water in filtration not only caused operational and safety hazards for the electrified rail line but also deteriorated and structurally compromised the tunnel lining. An innovative rehabilitation program was developed to enlarge the tunnel and to provide a new waterproofing system and final lining. For the rock excavation and support New Austrian Tunneling Method (NATM) principles were utilized, while water tightness was achieved by installing a PVC membrane waterproofing system followed by a reinforced cast-in-place final lining. Experienced on-site supervision generated additional savings during construction by streamlining support elements based on geologic conditions encountered.

Jan 1, 2003

By Jon A. Hummer, Aleksandar D. Bugarski, Shawn Vanderslice, Teresa Barone

A study was conducted to examine the potential of diesel emissions control strategies based on retrofitting existing power packages with exhaust aftertreatment devices and repowering with advanced power packages. The retrofit systems, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), were evaluated individually using a US EPA tier 2 (ter 2) engine operated under four steady-state conditions and one transient cycle. The DOC effectively curtailed emissions of CO, and to some extent organic carbon (OC), elemental carbon (EC), and aerosol number concentration. The DPF system offered substantially higher reductions in OC and EC mass and aerosol number concentrations. Both, the DOC and DPF achieved reductions in the aforementioned emissions without adversely affecting emissions of NO2 and nano-sized aerosols. The strategy of repowering with an advanced system was examined using a US EPA tier 4 final (tier 4f) engine equipped with a cooled exhaust gas recirculation system and diesel exhaust fluid-based selective catalytic reduction system, but not with a DPF system. The tier 4f engine contributed substantially less than the tier 2 engine to the EC and OC mass, aerosol number, and CO, NO, and NO2 concentrations. The tier 4f engine was very effective in reducing aerosol mass, NO, and NO2 concentrations, but it was not equally effective in reducing aerosol number concentrations. The implementation of viable exhaust after treatment systems and advanced diesel power packages could be instrumental to the underground mining industry to secure a clean, economical, and dependable source of power for mobile equipment.