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By T. B. Thompson

The Leadville District has been a prominent metal producer since its discovery in 1860. Veins and replacement bodies both have contributed to district production. The latter have been the major metal sources and are hosted within the Paleozoic Leadville, Dyer, and Manitou Dolomites. Igneous bodies representing eight separate events cut the sedimentary section. The main intrusive complex within the district occurs in the Breece Hill area and was the thermal center about which the vein and replacement ores exhibit mineralogical zoning. Precious metal-pyrite-quartz veins (quartz Th= 422 to 469°C; salinity < 4.2 wt. percent eNaCI) occur within or peripheral to the Breece Hill Intrusive Complex, whereas base metal veins and replacement bodies extend from the complex margins outward as much as 2 mi. Pre-ore and post-ore igneous bodies occur, but Fragmental Porphyry dikes immediately post-date the ore event. The Fragmental Porphyry grades downward from a heterolithic breccia with rock-flour matrix to one with a dark, glassy, sulfide- and phenocryst-bearing matrix, commonly with quartz-feldspar porphyry selvages on the dike. Two types of replacement bodies are recognized in the district: 1) the Leadville-type (LTM), massive sulfide (> 60% sulfides) bodies with recoverable Zn, Pb, Ag, and Au, and 2) the Sherman-type (STM), sulfide bodies (low total sulfide) with barite, galena, sphalerite, argentian tetra.hedrite, and minor pyrite. The latter type occurs only within the Leadville Dolomite and is found throughout the Mosquito Range and extending into the Alma District. The Leadville-type replacement bodies are zoned with a pyritic margin and base metal core. Wallrock alteration and trace Pb-Zn dispersion are strongly developed in igneous wallrocks but are weakly developed in carbonate wallrocks. Cu:Zn, Ag:Zn, and Au:Fe ratios increase outward from the center to the margins of LTM. Some of the sulfide bodies are localized on earlier-formed magnetite skarns. Pyrrhotite, pyrite, and marcasite are the earliest formed sulfide phases while chalcopyrite, marmatite, and galena developed later. Tetrahedrite and electrum occur in vugs and fine veinlets cutting the sulfides. Late-stage barite, dolomite, and fluorite occur as minor phases. Pressure-corrected Th for quartz (375-410°C), sphalerite (374-387°C), barite (320-360°C), and dolomite (310-314°C) fluid inclusions with salinities < 5.2 wt. percent eNaCI characterize the fluid responsible for the formation of the Leadville-type orebodies. These values clearly demonstrate the high temperature and low salinity of the ore fluids. Sulfur isotope analyses for galena and barite from LTM are - 1.9 to + 0.9%o and 7.8%o, respectively. Proximity to feeder veins and favorable dolomite hosts are the principal controls on ore localization. The Sherman-type bodies are not internally zoned but commonly have host rock silicification near the orebody margin or in the footwall rocks adjacent to fluid flowpaths along faults. Early quartz, pyrite, dolomite, and white barite precede base metal-silver minerals which are followed by late quartz and golden barite. It is not clear whether the early quartz and the late quartz and barite are part of the STM-forming process. Fluid inclusion analyses yield trapping temperatures as follows: early quartz, 316-341 °C; barite, 264-347°C; low-iron sphalerite, 215-265°C; and late quartz, 260-278°C. All inclusion fluids have salinities < 8.1 wt. percent eNaCI. Sulfur isotope values for barite and galena from STM range from 13.2 to 24.00/00 (avg: 18.4%o) and -6.8 to -3.8%o (avg: -5.5o/00), respectively. A hydrothermal fluid d34SSS of about 15%o is needed in order for galena and barite in equilibrium to exhibit the observed sulfur isotope compositions. Equilibrium sulfur isotope fractionation between barite and galena indicates a 300°C temperature of deposition. Two separate hydrothermal events appear to have taken place to form the distinctive Leadville-type orebodies and those of the Sherman-type assemblage. The STM is known to be older than the LTM. The latter is likely mid-Tertiary in age, post-dating emplacement of the Johnson Gulch Porphyry. LTM is clearly related to meteoric leaching of sulfur and lead (and other metals) from the upper portions of the Breece Hill Stock. Fluids were transmitted along faults, bedding planes, and contacts, and cooled away from the intrusive complex. Early ore fluids were weakly acidic and developed argillic assemblages in the igneous rocks adjacent to the fluid conduits. Reaction/replacement of carbonate rocks occurred where fluids encountered dolomite, but rapid neutralization prevented any wide-spread alteration beyond the ore-carbonate host contact. Pressures based on sphalerite geobarometry and stratigraphic reconstruction were 1.0-1.2 Kb. The high temperatures of vein and replacement ore fluids indicate that chloride complexing was more effective in metal transport than bisulfide complexes. Cooling, dilution of ore fluids, and reaction with carbonate rocks were the major factors in LTM ore deposition. STM formed over wide expanses of the Leadville Dolomite terrain adjacent to (and possibly capping) the Sawatch uplift. Sedimentary sulfur was derived from Pennsylvanian evaporite-bearing sequences adjacent to the uplift. Ore leads are strongly radiogenic (J-type) and are compatible with a crustal-leaching model. Temperatures of ore formation are higher, and ore-fluid salinities are lower than Mississippi Valley-type ore fluids. Superimposed upon dark-gray, diagenetic Leadville Dolomite are several stages of hydrothermal dolomite regionally distributed astride intrusive centers of the Colorado Mineral Belt. The presence of these later dolomites argues for dolomitization and later ore deposition in response to an abnormal thermal gradient caused by emplacement of Laramide batholiths and their generation of convective flow of meteoric fluids.

Jan 1, 2013

By N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities for the year 2015 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL) (Charlottesville, VA) database and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry, and presents analyses of exploration activities performed by the mineral industry.Three types of information are reported and analyzed in this annual review of international exploration: budgetary statistics expressed in U.S. dollars provided by SNL; regional and site-specific exploration activities that took place in 2015 as compiled by the USGS; and regional events that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize planned company budgets for worldwide exploration activities in 2015 for 24 nonfuel mineral commodities and metal alloys and are based on company surveys. Surveys focused on precious metals (gold, platinum-group metals and silver), base metals, (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (diamond, graphite, heavy-mineral sands, lithium, niobium, rareearth elements (REE), tantalum, tungsten and uranium).USGS data compilations and analyses are based on information provided by USGS mineral commodity and country specialists, as well as industry contacts and published trade journals. The USGS data summarize exploration site data collected for more than 80 minerals and materials, with a focus on base metals, diamond and precious metals. The USGS analyzed available information to assess the level of exploration activity in 2015 and to report trends in mineral exploration activity for the period 2005 through 2015. These analyses identify where mineral exploration is occurring by commodity and region and the intensity of activity that is taking place in each region for selected mineral commodities, and determines those factors that most affect changes in exploration activity."

May 1, 2016

By B. G. Hicks

The Manapouri Power Project is located in New Zealand&apos;s South Island Fiordland. The project is being constructed for the New Zealand Ministry of Works. Construction began in 1963 and is scheduled&apos; for completion in 1969. The project will divert water from the natural, glacially carved Lake Manapouri, at Elevation 580, through vertical- penstocks into an underground powerhouse 364 feet long, 127 feet high, and 59 feet wide excavated about 700 feet below ground surface and about 560 feet below the present lake level. The possible ultimate power installation will produce 700 megawatts from turbines located in the underground machine hall. The turbine flow will discharge through the 6-mile, 30-foot diameter tailrace tunnel into a fiord arm of the Tasman Sea. The rocks in the project area are primarily Paleozoic Fiordland Complex gneiss, schist, amphibolite, and marble intruded by granitic rocks and pegmatite. Shear zones have been encountered in the tunnels and machine hall. These produce water and occasionally require steel support. The machine hall arch was stabilized entirely by rock bolt reinforcement. Rock mechanics instrumentation has been used throughout the project both for pre-construction design calculations and to monitor tunnel rock loads and movements of the machine hall roof and walls. About 28 miles of the 100-mile transmission line will be constructed across glacially oversteepened slopes and debris or swamp filled valleys between the power plant and the eastern edge of the mountainous area. Steep glacially carved rock slopes and locally unstable glacial till complicated construction of the transmission line access roads.

Jan 1, 1968

By Chamila Jinendra Nanayakkara, Nimila Dushyantha, Amila Sandaruwan Ratnayake, Gayithri Niluka Kuruppu

Rare earth elements (REEs) are key ingredients in many advanced materials used in energy, military, transportation, and communication applications. However, the prevailing geopolitical dynamics and the rising demand for REEs have rendered the reliance on primary REE resources susceptible to future supply disruptions, posing a substantial risk to the availability of these elements for numerous applications. Therefore, it is imperative to undertake substantial initiatives in the extraction of REEs from secondary sources on a large scale to ensure the resilience of the supply chain. Permanent magnets, lighting phosphors, and nickel-metal hydride (NiMH) batteries are among the secondary sources with high potential for sustainable REE extraction. This review assesses the extraction potential of REEs from the aforementioned three secondary sources and their leaching kinetics and thermodynamics aspects. More importantly, state-of-the-art different existing kinetic models employed in rare earth (RE) leaching were well discussed for a better understanding of the REE leaching reactions. Furthermore, the optimized leaching parameters related to this kinetics were described, and various RE recovery methods were comprehensively summarized. These processes facilitate to managing one of the fastest-growing solid waste streams by minimizing environmental impacts and producing critical metals, including REEs via circular economy approaches. The recovery of REEs from secondary sources aligns with numerous United Nations Sustainable Development Goals (SDGs), particularly in the renewable energy sector for climate change mitigation. Consequently, this trash-to-treasure urban mining concept to transforming e-waste into a valuable resource for REE recovery emerges as a pivotal element within the REE industry.

Dec 28, 2023

By A. Nieto

This article is a review of previous discussions about underground mining method selection and classification with the purpose to clearly define and classify the two groups of variables (indicators) involved in the mining selection process: key deposit indicators (KDIs) and key mining method indicators (KMIs). This paper provides a simple and clear approach for the classification and selection of a feasible underground mining method based on a predetermined set of favorable deposit characteristics, which are defined as key deposit indictors (KDIs). This article also gives a summary of the key advantages and disadvantages associated with every underground mining method based on their key mining indicators (KMIs). The selection method given in this paper is based on defining field KDIs and comparing them to the KDIs that are favorable to every considered mining method. By cross validating a matrix of favorable KDIs, the paper presents a simple approach to rank several underground mining methods using a scale from favorable to less favorable accordingly to the ore deposit characteristics (KDIs). KMIs are used to further complement KDI rankings by analyzing every method’s KMI performance based on the expected productivity of the mining operation being considered. To further assist the reader through the selection process, this paper gives basic sketches representing each of the primary underground mining methods discussed in this paper. Each method is given using the same 3D isometric view as spatial reference to assist the reader with visual interpretation and comparison between methods.

Jan 1, 2010

By Staff

In 2012, the estimated value of mineral production increased in the United States for the third consecutive year. Production and prices increased for most industrial mineral commodities mined in the United States. While production for most metals remained relatively unchanged, with the notable exception of gold, the prices for most metals declined. Minerals remained fundamental to the U.S. economy, contributing to the real gross domestic product (GDP) at several levels, including mining, processing and manufacturing finished products. Minerals? contribution to the GDP increased for the second consecutive year. Trends in other sectors of the domestic economy were similar to those in mineral production and consumption rates (Table 1). After continued decline following the 2008-2009 recession, the construction industry began to show signs of improvement late in 2011 and throughout 2012, with increased production and consumption of cement, construction sand and gravel, crushed stone and gypsum, mineral commodities that are used almost exclusively in construction.

May 1, 2013

By G. T. Daware, M. J. Chaddha, S. P. Masurkar, P. G. Bhukte, A. Agnihotri

JNARDDC has evaluated bauxite deposits of India from the geo-technological point of view. During the evaluation studies, it was observed that bauxite deposits are associated with saprolite resources. During bauxite mining, various low-grade materials such as saprolite, laterite and low-grade bauxite are generated. These materials typically have low-alumina, high-iron oxide and high-silica content. Owing to their inferior quality, these materials cannot be used for alumina production and hence remain unutilized at the mine site. For the present study, the saprolite samples were collected from the Western Ghats bauxite deposits in India. The sintering studies were conducted on saprolite granules using a variety of parameters. The sintered granules were characterized, and their properties determined. The test results showed that bulk density, apparent density, porosity and refractoriness (PCE 1645–1659 °C) of the aggregates were within the range of refractory specifications. The feasibility tests carried out at the refractory industry indicated that the developed aggregates are suitable as refractory material and can substitute for calcined clay. Currently, high-purity clay resources used in the refractory industry are limited and fast exhausting; therefore, the industry is likely to face an acute shortage of raw materials, which will become more critical in the future. Therefore the sintered granules (aggregates) developed from saprolite, which is a mining waste, provide a low-cost, eco-friendly solution for the fast-exhausting resources of the high-purity clays. The developed process may change the Indian bauxite mining scenario because saprolite may substitute as a potential raw material for the refractory industry.

Apr 12, 2021

By LeRoy D. Loy

Would you believe me if I told you the constant battle between Government regulatory agencies and industry could be won by both sides? No, I&apos;m not crazy, nor have I been soaking up any of that fine Kentucky whitelightning. But I have recently been a participant in a battle where both sides won. Actually, I&apos;m using the term "battle" loosely because, in reality, it wasn&apos;t a battle at all - despite the fact that all the ingredients were there for a monumental struggle; i.e.. government, industry, special interest groups and a controversial issue - the development of effluent limitations. I&apos;d like to tell you about it. Historically, on one side of the battle, government has always been ac¬cused of adopting regulations with limited evaluation of existing technologies; and then with seemingly no regard for the economic consequences. On the other side, industry gets punished by government&apos;s harsh actions because of their past "do-nothing" attitude toward pollution control. Recently, this battle seems to be losing steam, because both government and industry are beginning to realize that, ultimately, they both will lose. Even more important is the fact that both sides are, or should be, working for industrial expansion compatible with environmental protection.

Jan 1, 1977

By J. G. Groppo

A series of performance studies have been conducted using counter-current column flotation to recover a marketable clean coal product from existing preparation plant fine waste streams. The test work was conducted at several preparation plant sites in Kentucky and Virginia and utilized a 0.15m (6 in.) I.D. column that was 5.79m (19 ft.) high. The refuse streams tested included both thickener feed and classifying cyclone overflow with a typical size distribution of 100 mesh X O. The percent solids of the column flotation feed varied from 1.5 to 15% while the ash content ranged from 30-60%. The concentrates produced contained 2-10% ash with BTU recoveries of nearly 90% using 0.12-1.25 kg/ton (0.25-2.5 lbs/ton) fuel oil and 0.12 kg/ton (0.25 lb/ton) MIBC. These results were consistent with or better than results obtained in preliminary laboratory scale column flotation evaluation. Test results from 7 different seams are discussed as well as scale-up relationships utilized to design a full scale installation presently in operation.

Jan 1, 1990

By N. A. Karl, D. R. Wilburn

"This summary of international mineral exploration activities during 2017 draws upon information from industry sources, published literature, SNL Metals & Mining (SNL), an offering of S&P Global Market Intelligence (New York, NY) and specialists in the U.S. Geological Survey (USGS) National Minerals Information Center. Three types of information are reported and analyzed in this annual review of international exploration: 1) budgetary statistics expressed in U.S. dollars provided by SNL; 2) regional and site-specific exploration activities that took place in 2017 as compiled by the USGS and 3) regional events and legislation that affected exploration activities including economic, social and political conditions, which were derived from published sources and discussions with USGS and industry specialists. Commodity and regional compilations are presented in this summary. Because multiple sources were used to develop commodity and regional compilations, statistics may vary depending on the source and type of data that are being reported.The SNL data summarize budget estimates for worldwide exploration activities in 2017 for 30 nonfuel mineral commodities and metal alloys, based on company surveys. Surveys focused on precious metals (gold, platinumgroup metals (PGMs) and silver), base metals (cobalt, copper, lead, molybdenum, nickel, tin and zinc), bulk commodities (bauxite, chromite, iron ore, manganese, phosphate and potash), and other commodities (aluminum, antimony, diamond, graphite, heavy-mineral sands, lithium, niobium, rare-earth elements (REEs), scandium, tantalum, tungsten, uranium, vanadium and yttrium). Information on uranium exploration activities was included in SNL’s survey for the first time in 2007. Data on lithium, niobium, phosphate, potash, REE and tungsten were compiled for the first time in 2010, and scandium, vanadium and yttrium were added in 2014 because of their increased topical significance. Since 1999, companies with exploration budgets of $100,000 and greater were included in the SNL surveys. SNL budget estimates exclude coal, and oil and gas. The 2017 SNL mining company survey compilation was reported by SNL to include an estimated 95 percent of the world’s nonfuel mineral exploration budgets. The 5 percent that was not covered was accounted for by companies that chose not to participate in the SNL survey, private companies that do not publish their budget data, and government-funded exploration activities."

Jan 5, 2018

By D. D. Xu

A novel system for the depression of pyrite and the ash-forming minerals has been developed. A metal ion, including but not restricted to Fe+2, is added to form a hydroxide coating on the pyrite or ash-forming mineral. A polymeric depressant is then added to attach to this re-surfaced mineral. Nearly 200 flotation tests with a 11 different coals indicate the effectiveness of this system. Many of the important process variables such as the coal source, frother-collector system, grind size and procedure, pH, metal ion, and depressant type and concentration have been studied.

Jan 1, 1994

By J. Starwood

Post-super-cycle mining executives must exploit every aspect of the value chain to deliver continued value to stakeholders. Integrating enterprise-wide information technology with value-chain-wide operational technology, known as IT-OT integration, is essential to extracting optimal results from the value chain. Mining companies trail other industries with respect to IT-OT integration across the value chain. Manual data consolidation and value chain optimization using spreadsheets and human intelligence are widespread practices within the industry. Increasing automation with smart devices and controllers means the volume and velocity of data will soon increase beyond human abilities. Enterprise Architecture provides a method for aligning information technology with the business operating model to successfully implement IT-OT integration. A Value Realization Framework (VRF) provides a means for predictable traceable value realization from IT investments and assets. With these principles, frameworks, models, methods, and techniques, mining organizations can accomplish IT-OT integration that provides their executives with a strategic value-chain-aligned platform for sustained value realization over the long term.

Feb 23, 2014

By M. Ramokhothoane, S. Rupprecht

"NTRODUCTION Women employment in the mining industry dates back to the 19th century. Various parts of the world, for example, India, Japan, the United Kingdom and the United States of America had women employed in large numbers. The women’s jobs were primarily manual in nature. Women were used to carry coal in buckets from the coal face and out the mine, and those who worked on the surface plants were used to sort waste rock from the coal product. Other heavy industries, which were traditionally male dominated, for example the military, also had a considerable number of women supporting the war effort. The outbreak of war also caused a shortage of labour, which in turn, necessitated that women were used in various roles during the war. After World War II, women returned to their traditional roles, but had acquired new skills, and had a different outlook to life. The wearing of pants and short hair became fashionable, as a result of being in the army.Various laws were passed which prevented the employment of women underground. Different countries had rules that they believed were in the best interest of women and were of the opinion that the rules somehow were protecting women against the harsh working conditions. In South Africa, post 1994, there has been a shift in thinking in regard to the employment of women in the mines. WOMEN IN SOUTH AFRICA MINING In the words of the Minister of Women in the Presidency, Minister Susan Shabangu, “women must take centre [sic] stage as the country gears itself for the implementation of radical socio-economic transformation policies and programmes in the next five years” (SA Government News Agency, 2014). In as much as some progress has been made in advancing women, more needs to be done in order to realize sustainable benefits in the economy. The emancipation of women is a reality and remains top of the South African government agenda. From the Authors’ experience there are two types of men in the mines. The first group support change and see the value in it. To them, women in mining bring in the diversity and play the complementary role in achieving greatness. There is no fear of job security and humiliation but a great sense of “camaraderie”. The other group continues to enforce stereotypes, which works against the spirit of redressing the imbalances of the past."

Jan 1, 2018

By Sandeep Kumar Jeripotula, Govinda Raj Mandela, Aruna Manglapady

Dumper operators are frequently exposed to whole body vibration (WBV) in surface mines. Surface mining activities involve the amalgamation of comparatively high intensity of vibration and extended exposure durations. Efficient risk reduction mandates knowing of important phases of a task that poses a threat to health of dumper operators. So far in India very limited studies have been reported on WBV exposure with regard to surface mines. This paper evaluates WBV of dumper operators based on ISO 2631-1:1997 Standards and European Union (EU) Directive 2002 for different phases of job cycle. Six dumpers were considered for this study and the vibration measurements were made for all the four phases of the job cycle by placing the triaxial accelerometer on the operator’s seat-surface and at the seat-back, independently. The findings of the study revealed that the haulage task (loaded travel and empty travel) remains the chief contributor to vibration exposure according to seat-surface and seat-back measurements. Maximum frequency weighted root mean square (RMS) of 1.12 m/s2 and 1.09 m/s2 were reported for empty travel task for seat-surface and seat-back measurements, respectively. For seat-surface measurements based on RMS, Z axis remains as the dominant axis of vibration for all the dumpers during haulage task, whereas for seat-back measurements, the dominant axis varies between X and Y. Exposure action value (EAV) based on RMS has exceeded the threshold value of 0.5 m/s2 for all the dumpers during loaded travel and empty travel for seat-surface as well as for seat-back measurements.

By J. J. Gusek

Passive treatment of mine drainage using constructed wetlands has been employed on coal and metal mine sites since about 1985. The technology has advanced significantly since then; there are currently over 600 of these systems treating coal mine drainage in the Eastern U.S. at flow rates of hundreds of liters per minute. Passive treatment performance at three metal mines discussed in this paper has been positive for a wide variety of flows, water chemistry, and climates. The sites include a high-altitude underground copper mine, acidic seepage from a gold heap leach pad, and pumped effluent from an active underground lead mine in Missouri.

Jan 1, 2000

By Greg Colzani, Emily Thompson

The 3RPORT Project, includes a 5-mile tunnel excavated by a 19-foot diameter slurry Tunnel Boring Machine below the city of Fort Wayne, IN. The Geotechnical Baseline Report (GBR) indicated vuggy to massive argillaceous dolomite within the tunnel alignment. During excavation of the first reach, the TBM encountered zones of cohesive clay and sandstone presented in full face and mixed face conditions. The occurrence of Sandstone was not a “Baselined Condition” described in the GBR for this reach of the alignment. This paper will discuss the methodology to investigate, mitigate and evaluate the DSC impacts on TBM performance.

Dec 1, 2022

By V. O. Tenorio, D. Tolmachoff, K. Willa Brown, K. J. Kingsbury, J. B. Nickels, G. J. Nail

A major design feature to consider from the initial pioneering works until reaching full mine production of icy regolith at the South Pole of Moon will be the ramp. This will allow the access of equipment and personnel in and out of the excavation area. Although most of the requirements considered when designing a ramp on the Earth are similar, the fact of working in low gravity, with zero atmosphere, the potential exposure to high radiation, extreme temperature levels and drastic changes of illumination, from intense light to total darkness, are new factors to be included. Transversal sections are obtained according to the progression sequence of the production levels, with changes in length, gradient, friction factor of the terrain and curvature when required by the location characteristics and the specification of the equipment utilized. A MATLAB script was developed to calculate all the variables, in order to obtain 3D generated surfaces from the range of possible profiles.

Mar 2, 2022

By A. D. Ajak

A complete mining cycle involves digging, loading, hauling and dumping of the materials. Moving the ore from the pit to the crusher or to the waste dump requires access routes, which are termed haul roads. These roads have to be designed, constructed and maintained. A review of the literature indicates a common consensus among researchers that there should be a balance between haul road economics and safety of the road users. However, there is no universally accepted theory on the design of haul road geometry and, in particular, road dimensions. The current industry practice is based on empirical data and rules of thumb developed by engineers. Therefore, this paper will use the overlooked and less valued branch of mathematics, arithmetic progression, to derive a road width equation. It is beyond the scope of this paper to discuss all road design components. The focus will be on the geometric aspects, which more often have a direct impact on road safety. In this paper, the current design practices and techniques for haul road geometrics design will be explored, using arithmetic progression to formulate road width equations, case examples to apply the equation and then validating the results with conventional techniques that have confirmed the reliability of road width equations, thus eliminating use of tables during design.

Jan 1, 2012

By K. T. Stafford, N. A. Iverson, V. T. McLemore

Laramide porphyry copper deposits are large, low grade (<0.8% Cu) deposits that contain disseminated copper minerals, breccias, and stockwork veinlets of copper and molybdenum sulfides associated with porphyritic intrusions in Southwestern New Mexico. Critical minerals, such as PGEs, tellurium, indium, germanium, and gallium are recovered from the anode slimes remaining after copper is refined. Detailed age dating, mineralogy, geochemistry, along with geologic mapping could refine the location of critical minerals within specific systems and could identify porphyry systems with elevated critical minerals that could become economic, in addition to the already produced copper, gold and molybdenum.

Feb 1, 2023

By Guodong Li, Chenlin Wang, Zibiao Yu, Bo Xu

Abandoned coal mines have many underground space resources, such as roadways, shafts, and gobs. Among them, abandoned roadways are the best gas storage space for underground compressed air energy storage (CAES). However, CAES caverns have high air pressure and strict sealing requirements. Therefore, the stability and sealing of abandoned roadways under high internal pressure must be analyzed. Afterward, the suitability of abandoned roadways used for CAES caverns should be evaluated. In this study, the numerical simulation software FLAC3D was used to calculate the stress, deformation, plastic zone volume, and pore pressure of surrounding rock in an abandoned roadway under 10 MPa internal pressure. The influence of buried depth, surrounding rock grade, and in situ stress state on roadway stability and the effect of surrounding rock permeability on roadway sealing were analyzed. Results showed that the stress, displacement, and plastic zone volume of surrounding rock were affected by high internal pressure when the buried depth was less than 300 m, but high internal pressure had little effect on them when the buried depth was more than 300 m. The suitable range of buried depth was more than 300 m. The optimal choice of surrounding rock grade was I and II, followed by grades III, IV, and V. The optimal choice of in situ stress state was σH > σh > σv, followed by σH > σv > σh and σv > σH > σh. The sensitivity of the stability evaluation parameters was ranked in descending order as follows: buried depth, surrounding rock grade, and in situ stress state. When the surrounding rock permeability was less than 1 × 10− 14m2, the 24-h air leakage rate of the roadway was less than 1%. The suitable range of surrounding rock permeability was less than 1 × 10− 14m2.

May 23, 2023