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By John Ward Smith

Dawsonite bearing oil shale of Colorado's Green River Formation offers a unique and vast (6.5 billion tons of Al2O3) resource of easily extractable alumina. The processing methods required by the thermal reactions dawsonite and its oil shale carrier also require production of shale oil, soda ash, and nahcolite as marketable coproducts. These production methods are presented. The alumina production process is contrasted with the Bayer process to describe technical advantages of extraction of alumina from oil shale which may offset the problems associated with processing a relatively lean ore. While alumina production from oil shale requires development of new technology, the technical problems appear solvable. Only the political problems arising from the now onerous and completely unnecessary Federal oil-shale withdrawal appear less solvable.

Jan 1, 1980

By Ihsan Berk Tulu, Mark Van Dyke, Ted Klemetti, Deniz Tuncay

"Longwall abutment loads are influenced by several factors, including depth of cover, pillar sizes, panel dimensions, geological setting, mining height, proximity to gob, intersection type, and size of the gob. How does proximity to the gob affect pillar loading and entry condition? Does the gob influence depend on whether the abutment load is a forward, side, or rear loading? Do non-typical bleeder entry systems follow the traditional front and side abutment loading and extent concepts? If not, will an improved understanding of the combined abutment extent warrant a change in pillar design or standing support in bleeder entries?This paper details observations made in the non-typical bleeder entries of a moderate depth longwall panel; specifically, it explores data collected from borehole pressure cells and roof extensometers, observations of the conditions of the entries, and numerical modeling of the bleeder entries during longwall extraction. The primary focus was the extent and magnitude of the abutment loading experienced due to the extraction of the longwall panels. Due to the layout of the longwall panels and bleeder entries, the borehole pressure cells (BPCs) and roof extensometers did not show much change due to the advancing of the first longwall. However, they did show a noticeable increase due to the second longwall advancement, a maximum of about 4 MPa of pressure increase and 5 mm of roof deformation. The observations of the conditions showed little to no change from before the first longwall panel extraction began to when the second longwall panel had been advanced more than 915 meters. Localized pillar spalling was observed on the corners of the pillars closest to the longwall gob as was an increase in water in the entries. In addition to the observations and instrumentation, numerical modeling was performed to validate modeling procedures against the monitoring results and evaluate the bleeder design. ITASCA Consulting Group’s FLAC3D numerical modeling software was used to evaluate the bleeder entries. The results of the models indicated only a minor increase in load during the extraction of the longwall panels. These models showed a much greater increase in stress due to the development of the gateroad and bleeder entries—about 80% development and 20% longwall extraction. The FLAC3D model showed very good correlation between modeled and expected gateroad loading during panel extraction. The front and side abutment extent modeled was very similar to observations from this and previous panels."

Jan 1, 2019

By Frederic Souche, Andrew R. Klaetsch, Brian Hann, Nick Goodenow

This paper describes support of excavation (SOE) design and construction for three large diameter shafts excavated through glacial soil and controlled blasting in complex sedimentary rock formations. SOE in soil consists of unreinforced secant pile rings designed to resist lateral pressure in circumferential compression, eliminating costly steel core beam reinforcing. Controlled blasting at the shafts, adits, and tunnels in densely populated neighborhoods requires managing risks to the public, buildings, and utilities. Controlled blasting approaches limited adverse impacts to receptors nearby while achieving adequate production and fragmentation. A site-specific observational approach was used to adjust blasting parameters, limiting the impact on local stakeholders while maintaining daily progress and managing overbreak.

Jun 13, 2023

By J. C. Ashby

Electric utility response to certain amendments of the Clean Air Act has resulted in a production of several types of alkaline coal combustion byproducts. Alkaline combustion byproducts are gaining increasing usage for acid mine drainage mitigation as research leads to a better understanding of their beneficial applications. Since January of 1997, Mettiki Coal Corporation has been injecting alkaline flue gas desulfurization material from Virginia Power's Mt. Storm Unit #3 wet limestone scrubber into abandoned portions of the active Mettiki mine. This paper provides an overview of the key design, transportation, regulatory, and environmental issues faced in the project.

Jan 1, 1998

By G. Chancellor

"INTRODUCTION The paste plant is located at the Barrick Goldstrike mine in Northern Nevada on the Carlin Trend. The Goldstrike property consists of an open pit and an underground mine; along with two processing facilities: a roaster and an autoclave. The underground portion of the mine produces approximately 1,800,000 ore tons per year and approximately 400,000 ounces. The mine is broken up into four distinct zones: Banshee, Meikle, Rodeo and Northpost. The current paste plant services both the Rodeo and Northpost zones. Development of the conceptual designs and permit approval for this plant was an extensive process that took over a decade to complete. A testing program was developed in conjunction with this process and implemented throughout to ensure the following metrics were achieved: ensure no environmental impact, material available onsite would be able to flow through the pipe to all required locations, and that this material could achieve the appropriate final strength. PLANT AND UNDERGROUND CONSTRUCTION This is the first paste plant to be built in Nevada. The paste plant at Goldstrike began construction in January 2012 and was completed in March of 2013. This plant was constructed to service the Rodeo side of the underground mine which previously utilized a cemented rock fill (CFR) plant to meet their backfill needs. However, in March of 2013, the same month the plant was commissioned, the raise that fed this CRF plant was mined out in a planned phase of the adjacent open pit. This made the switch to paste all the more difficult as it was being relied on for as the sole source of backfill production even though the system yet to be fully tested and optimized. The plant was designed to be fed with onsite Roaster tailing which would be thickened and then mixed with cement and fly ash. The plant was designed to pump 177 tons of paste per hour with a utilization of 65%. The original design specifications for the paste were 77% solids with varying binder contents depending on where the paste was being placed"

Jan 1, 2015

By B. G. Stone

"INTRODUCTION “Sampling is the process of taking a small portion of an article such that the consistency of the portion shall be representative of the whole” (Baxter and Parks, 1939) “An orebody is a mixture of minerals in proportions that vary in different parts of the mass. As a consequence the proportion of contained metals also varies from place to place. Therefore, a single sample taken in any particular place would not contain the same proportion of metals as does the orebody as a whole except by a highly improbable coincidence. The probable error, which would be very large if only one sample were taken, decreases with the number of samples, but it never disappears completely unless the samples are so numerous and so large that their aggregate is equal to the orebody itself, in which case the orebody would be completely used up in the process of sampling. Since carrying sampling to such an extreme would defeat its own purpose, some probable error is always present in actual cases and the practical objective is to reduce this probable error to allowable limits. This means balancing the number of samples against the desired accuracy; if there are not enough samples the result is unreliable; if there are too many, the time and expense of taking them is excessive.” (McKinstry, et al., 1948). In an actual orebody, the accuracy of sampling depends not alone on the number of samples but also on proper distribution of them throughout the orebody, for it would obviously be incorrect to take all of the samples either in a rich part or a lean part. Therefore it is important to select the places in such a way that all parts of the orebody will be represented. “For those who cultivate land which is alike arid, heavy , and barren, and in which they sow seeds, do not make so great a harvest as those who cultivate a fertile and mellow soil and sow their grain in that. And since by far the greater number of miners are unskilled rather than skilled in the art, it follows that mining is a profitable occupation to very few men, and a source of loss to many more.” (Georgius Agricola page 5 Book 1 as translated by H.C. Hoover and Lou Henry Hoover, 1950)“It is evident that mining is very profitable to those who give it care and attention”"

Jan 1, 2015

By J. Klemenic

This paper presents an analysis of gold production and prices over an extended period. Production patterns are provided for the world as a whole and for the five major producing countries. Gold prices as a function of interest rates, as measured by municipal bond rates, are given for the period 1947 to the present. World gold production has had a phenomenal increase since 1980, with the exception of South Africa, all major producing nations participated in this increase, even though the price of gold generally has been decreasing since the high level attained in 1980.

Jan 1, 1993

By D. M. Thayer

In the last decade public awareness of the need for pollution abatement has increased greatly. The concern that had been previously shared by local and state conservation groups has spread to create a national concern for preservation of our non-polluted environmental assets and regeneration of those that have been wasted. Because other current matters such as inflation, civil rights,' tax reform and the Vietnam situation have been the object of most national concern, an extremely strong national pressure base has not been brought to bear on the pollution control crisis. Yes, the word is crisis, for in many areas pollution is of critical concern. One has only to look at Lake Erie, the skies about our major urban areas and many of our major rivers and streams to see this crisis These are not situations that can be corrected overnight. We are faced with two basic problems that should be attacked simultaneously: (1) Cleaning up the present sources of pollution and (2) preventing the generation of new pollution sources. What approach should be taken? As in any engineering problem, the limits must be well defined before a final solution is attempted. Pollution must be defined on a national basis. This means that basic Federal legislation and control is necessary. This should reduce any competitive advantage that can presently be gained by movement of operations from one state or geographical area to another on the basis of differences in local legislation .and enforcement. By giving real numbers as guidelines, selective enforcement can be avoided. As a starting point, for a definition of pollution let us use the following - "Any change in the environment occurring from other than natural causes." This definition may not be satisfactory to all but surely we must be somewhat dramatic in our statements to counteract the present prevailing philosophy. Our statement of this philosophy - "At what level of pollution can we afford to operate?" On the basis of our general definition we would like to state what we feel should be the philosophical statement - "How little can we change our physical environment as a result of operations?"

Jan 1, 1970

Your thoughts on the current status of the global minerals industries? The global economic, technological, social and political changes of the last two decades of the 20th century resulted in the emergence of a restructured minerals industry. This industry is now based on a new cost-cutting philosophy; utilization of modern technology; productivity gains rather than production tonnages; diversification of mineral markets; and globalization of exploration, mining and processing. Quantity and tons used to be the focus. The emphasis today is on remaining competitive in the marketplace by lowering per-unit production costs as much as possible. What factors and trends will impact the minerals industries in this, the 21st century? A number of parameters will impact minerals operations and shape the future sustainability and growth of the minerals industries. Increased demand for minerals will be accompanied by the demand for technical advancements. We will also see a continued emphasis on health and safety, environmental stewardship, and education and training. Let me elaborate.

Jan 1, 2002

By J. P. Wilson

The Tessenderlo-Kerley Leach process has been shown to be effective in the removal of residual copper from molybdenite concentrates. Concentrates of varying mineralogy, including those containing relatively large amounts of chalcopyrite, have been successfully leached on laboratory and pilot plant scales. The lixiviant system is ammonia and ammonium bisulfite with air / oxygen addition. An abrasive is added which greatly enhances the kinetics, and it is subsequently screened out and reused. The dissolved copper is easily recovered using existing technology. Extraction profiles, reagent consumptions, and mineralogical data are presented.

Jan 1, 1999

By Franz Albert Nonnen

Backfill systems have been used for as long as mining activities have existed. Various backfill methods have been developed over the centuries with consideration for geological necessities, the technical means available, security requirements, and available finances. In the past, backfill systems were introduced and upgraded geographically in accordance with local experiences. In modern times, mining engineers participate in international forums for the exchange of knowledge so that backfill techniques and experiences are shared concurrently in mining areas all over the world. Mine backfilling increases the cost of mining so that great attention must be paid to choose a low-cost, reliable, and low maintenance backfill system. Some methods are described in this paper.

Jan 1, 2001

By Yuting Xue, Mark Van Dyke, Joe Wickline

The understanding of coal mine roof lithology is a critical component in the determination of engineering solutions for roof control. Coreholes were the first technology available to determine lithology of the roof in reserve areas, but coreholes are typically drilled 500–2,500 ft apart due to their cost and sometimes reach more than $125,000 dollars per hole, depending on mine conditions. The next method developed to bridge this gap was the fiber-optic scope which is utilized in the roof at the faces of underground development. High-end fiber-optic scopes can also be costly (20,000–40,000 dollars) but are more affordable than drilling a corehole, and the information can be processed immediately to make quick roof support determinations. The fiberscope can be operated wherever a roof bolter can drill a hole, and there are no restrictions related to property owners, proximity to streams, elevation changes, etc. The latest borescoping method utilized by mining companies is the use of videoscopes. Videoscopes and all borescopes in general are limited by the lengths of the scope and the length of the borehole drilled in the mine. Videoscopes have the advantage of being able to record video while examining the roof lithology. The information can be recorded quickly underground and then be examined on the surface which allows anyone to capture the video so that a geologist can make lithology descriptions without ever going underground. In the past, videoscopes had limited resolution, a short battery life, were fragile and were relatively costly. As technology progresses, videoscopes have become more affordable, have increased battery life, and offer enhanced 1080p resolution. With the broader availability of affordable videoscopes, videoscopes can be more readily used in various mine environments at every active section underground. This paper will discuss the types of videoscopes available, the features that will aid in lithology description/identification, the deployment methods pertaining to supplemental roof support recommendations, and an advanced methodology to enhance accuracy in understanding roof lithology.

Feb 1, 2025

By James K. Ballard

Leach dumps in Butte are relatively new in comparison with older established dumps in other areas throughout the West. With the exception of one 10 million ton dump, all dumps have been formed on a prepared base. This is necessary because the entire leach dump area overlies an alluvial fill which varies in depth from 100 to 400 feet and through which solution would be lost. Preparation of the leach pad consists of first removing all vegetative material and compacting the exposed surface with rollers. This surface is covered with a 4" layer of minus 1" crushed rock which in turn is roller compacted. A 3" compacted layer of asphalt hot mix is then applied to the crushed rock surface. Final sealing is effected by a 1/4'? coating of catalytically applied hot asphalt. Dump leaching was inaugurated in 1964. First solution applied was wholly made up of mine water pumped to surface through a central pump shaft. Sulfuric acid was added on surface at a surge pond to control pH of the leach solution. Acid addition is necessary not only to benefit the leach dumps, but to prevent the formation of ocher scale within the pipe line distribution system. Mine water pH is on the order of 2.8. The combination of ferrous and ferric iron as well as magnesium and aluminum salts is such that ocher forms at a pH of 2.38. It is therefore mandatory to control pH at 2.0. Dump effluent pH is held at 2.3 or less.

Jan 1, 1968

Giant gold deposits are considered products of crustal-scale systems. Reduced fluids stored in mid to lower crustal reservoirs were discharged into mid to upper crustal sites of deposition. Elements of the architecture include crustal-scale structures, reduced packages of rock and regional seals. Gas-rich aqueous fluids were common but non-aqueous fluids may have been significant in the deeper parts of the systems. Fluid fluxes in over pressured domains were maintained by porosity waves. Abnormal heat input from the mantle may not be required once the systems were perturbed. Fluid-mixing and hypogene enrichment were probably the most significant precipitation processes.

Jan 1, 1999

By George M. Potter

Under contractural arrangements with the Bureau of Mines, Mountain States Research and Development, Inc. (MSRD) completed a technological investigation to determine the feasibility of in situ mining of metal commodities other than copper and uranium, The study was based upon available literature and experience. The selection of potential candidates for in situ mining was influenced by economic importance, probable amenability to in situ methods, and environmental considerations. Four metals (or metal pairs) were chosen for feasibility studies: aluminum (with a copper byproduct), gold-silver, and manganese were recommended for further study and action; cobalt-nickel was also recommended contingent upon preliminary laboratory leaching and recovery investigations and field geohydrological work. Mining and recovery plans and an economic evaluation are included. Other metals with potential for in situ leaching are lead/ zinc, molybdenum, and vanadium.

Jan 1, 1981

By Jacques Bernazeaud

Rouez is a recent discovery of a major low-grade sulfide body (± 100 m, 0,6 % Cu, 0.3 % Pb, 1 ,5 % Zn, 21 g/t Ag, 1.5 g/t Au) in a populated farming area of Brittany, France, some 30 kilometres northwest of Le Mans. The discovery is the result of an airborne electro- magnetic (INPUT) survey. It is the first time that the INPUT method has been used in France. The survey Gas successful in spite of the numerous interferences normally found in populated areas. The lack of a good drainage system would not allow the discovery of Rouez using stream sediment geochemistry alone. Ground geophysical surveys confirmed the airborne work and gave sufficient information to make the first hole a discovery hole. The deposit is Proterozoic in age and sediment-hosted. The metamorphism is low grade.

Jan 1, 1983

By Geoffrey Hughes

The Narragansett Bay Commission (NBC) is a regional sewer authority that serves ten communities in the Providence, Rhode Island metropolitan area. From 1992 to 1999, the NBC developed a comprehensive facilities plan to abate Combined Sewer Overflow (CSO) pollution in the Upper Narragansett Bay. The plan underwent many major evolutions during this period, most notably the addition of a stakeholder?s process by which NBC demonstrated a site-specific plan to control the pollutants and meet water quality standards. The favored solution consisted of deep tunnel storage with treatment at existing wastewater facilities that had been recently upgraded. In 1999, a final plan was accepted which included two tunnels, five CSO interceptors, twelve sewer separation projects, a wetland facility, and a wastewater treatment facility upgrade. The program is to be constructed over 20 years in three sequential phases (Figure 1). Phase I of the program includes a 4,963 m (16,284 ft) long, 7.9 m (26 ft) diameter, 70.1 m (230 ft) deep storage tunnel; seven drop shafts with connecting adits; ancillary facilities; and a pump station. Construction of Phase I began in 2001 and is expected to be operational by October 2008. This paper focuses on design and construction of the Fields Point Tunnel Pump Station (FPTPS)located at the south end of the main spine tunnel. A189 Ml/day (50 MGD) pump station is required to lift CSO flows from the tunnel to the Fields Point Wastewater Treatment Facility (FPWWTF). The pumps are to be housed in a 35.6 m × 18.6 m ×20.7 m (117 ft × 61 ft × 68 ft), 91.4 m (300 ft) deep cavern excavated in a complex meta-sedimentary rock of the Rhode Island Formation, and connected to the surface by 9.7 m (32 ft) and 3.4 m (11 ft) diameter shafts. Factors which influenced selection of the size, configuration and location of facilities included the preferred arrangement of pumps, critical aspects of site geology, and estimated cost. Technical and value engineering reviews also affected the final design. Following Notice to Proceed (NTP), concerns were raised by the contractor regarding constructability and design. Additional geotechnical investigation and independent engineering review were employed to validate the design assumptions. The cavern was successfully excavated and sup-ported in rock, completed on schedule and within budget in 2005. In 1992 the NBC retained Louis Berger Group (LBG) as Program Manager (PM) for the CSO Abatement Program. LBG thereafter formed a design team including: Jacobs Engineering Group(JEG) as the designer for underground structures and near surface collection facilities; Black and Veatch(B&V) to design the pumping system and associated facilities; Haley and Aldrich (H&A) to oversee the geotechnical program; and Malcolm Pirnie to design the system-wide instrumentation and control system. Construction management, resident engineering, and inspection services were provided by the joint venture Gilbane/Jacobs Associates (G/J).

Jan 1, 2008

By Christof Metzger

This paper discusses the process utilized by the Kiewit?Bilfiger Berger Joint Venture (Contractor) to select, design, and procure the largest mixshield tunnel boring machine (TBM) ever implemented in North America. The mixshield will excavate the 8,534 linear m × 6.7 m ID (28,000 linear ft × 22 ft ID) tunnel for the City of Portland Oregon?s, Bureau of Environmental Services (Owner) East Side CSO Tunnel Project. TBM selection was conducted under a preconstruction contract in which the Contractor, Owner, Construction Management Consultant and Designer collaborated on TBM selection prior to commencement of construction. This paper focuses on TBM design considerations, including the use of one versus two machines, machine configuration,extended-wear protection, hyperbaric interventions, boulder digestion, and erection of a steel-fiber-reinforced segmental lining

By D. Bristow, D. Baker, K. Awuah-Offei, A. ur Rehman

While a body of work exists on intelligent systems for guiding occupants out of buildings during an emergency, the problem of guiding miners out of a mine during an underground emergency has not been explored. Underground evacuation fundamentally differs from building evacuation because of differences in the regulatory regime and uncertainty regarding the number of occupants. The potential for implementing an intelligent miner guidance system is buttressed by the fact that miner tracking systems, along with communication and sensor networks, already exist in underground mines. This work presents a method based on a local positioning system, in the form of a network of “nodes” at major “intersections,” which can then be used to guide miners to safety. We have developed a path-planning algorithm, based on Dijkstra’s algorithm and the local positioning system that can provide miners with the optimal escape path in an emergency. The algorithm is validated with scenarios at the Missouri University of Science & Technology Experimental Mine demonstrating the potential to include smart technology in mine emergency management and response planning. INTRODUCTION Underground mines are hazardous environments with a higher than usual risk of safety emergencies where miners have to evacuate the mine to save their lives. Mines have always trained miners to evacuate or shelter-in-place in minimum time. Jalali and Norrozi (2009) opined that the three major components that help miners in case of emergency are pre-planned optimal escape routes, decreasing delays, and improving the education of miners. In fact, Goodman and Kissel (1990) suggested that fatalities arising from mine accidents could be reduced by 50% just by decreasing delays in finding the pathways in case of emergency. The proposed work can assist miners in finding escapeways quickly in case of emergency. It is very important to have a pre-planned evacuation strategy that is clearly communicated to miners to ensure the safety of all (Conti, Chasko & Wiehagen, 2005).

Jan 1, 2019

By P. Jonsén

Understanding mill charge motion is important. In the charge, the centre of gravity is shifted from the rotational centre of the mill system, and its motion is induced by rotation of the mill, while at the same time the charge creates a torque into the mill system. Breakage of ore particles and wear of liners/ball media are closely linked to the motion. To study these phenomena in a physically correct manner, numerical models for different parts of the mill system are needed. Validations of such models are scarce, because of the difficulty to measure in a tumbling mill. Experimental measurements in a lab mill were done for diverse load cases: varying feed materials, mill fillings, mill speeds and pulp liquids. The mill is set up to directly measure the charge-induced torque. The accuracy is good with relative uncertainty smaller than ±2% for relevant load cases. A full three dimensional numerical model of the whole mill is used to predict induced torque. Agreement between predicted and measured torque at steady-state is good. In addition, the model can accurately predict the mill start-up behavior for torque and mill power. This proves that the model is physically correct, and can be used for full-scale mills.

Feb 27, 2013