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By Doug Harding

The Metropolitan St. Louis Water District’s Project Clear is a 28-year program targeting wastewater capacity throughout St. Louis, MO. The extensive program includes the Jefferson Barracks Tunnel, running parallel to the Mississippi River at 2 m ID and 5,400 m long. A rebuilt Robbins Main Beam TBM began boring but hit challenging conditions about 2,400 m in, including water inflows. A larger 4.1 m Robbins Main Beam machine will complete the remaining 3,050 m in limestone, dolomite, and shale. The TBM will utilize a high-powered, high breakout torque cutterhead along with enhanced 360-degree probing & grouting capabilities to detect any karst formations.

Dec 1, 2022

By B. Boberg

Annual requirements of uranium to fuel the 441 currently operating nuclear reactors in the world is 170 million pounds U3O8 (65,385 tonnes U). 2005 global production was 108 million pounds (41,595 t U), of which only 2.7 million pounds U3O8 (1,039 t U), was produced from US uranium deposits. US nuclear utilities represent 26% of the global nuclear capacity but only obtain 2.5% of their supply from US uranium mines. Since 2002 annual global production increased from 93 million pounds U3O8, a 15% increase and the US production increased from 2.3 million pounds to 2.7 million pounds, a 17% increase. Reasonably Assured Resources (RAR) of 12,332 million pounds U3O8 (4.7 million t U) are reported from a wide variety of countries and types of uranium deposits. This RAR suggests that there are significant global uranium resources potentially producible at a price of $50 per pound U3O8 ($130 per kg U). Table 1 shows the distribution of global uranium resources. This table, prepared from historic data maintained by the World Nuclear Association, does not include some areas of the world that are currently considered to contain significant resources of uranium such as Mongolia. Table 1 suggests that the United States contains the fourth largest uranium resource in the world with 890 million pounds U3O8, behind Australia, Kazakhstan and Canada in resources that are producible at a price of $50 per pound U3O8 ($130 per kg U). Within the US, the states that demonstrate the greatest amount of uranium resource are Wyoming, New Mexico, Texas and the Four Corners Area of Arizona, Colorado and Utah.

Jan 1, 2007

By Kai Wang, Chao Xu, Qiang Fu, Tong Yang, Chunyu Zhao, Wei Zhao

The stress of a coal seam is an important factor that affects the permeability of the coal seam and then affects the coalbed methane (CBM) drainage. In China, adjacent coal seam mining is an important method to reduce stress, which increases the permeability of the coal seam. However, in the process of mining adjacent coal seams, many coal pillars remain, which causes stress concentrations and results in a decrease in permeability. Therefore, it is important to study the influence of coal pillars on the stress of adjacent layers and its distribution and evolution in the floor rock. This paper took the Shendong Baode Coal Mine as a case study and investigated the influence of the coal pillar on the stress and permeability of coal seam #11. The results show that under a coal pillar, the relationship between the vertical stress of different floor depths and the width of the coal pillar can be divided into a negative correlation zone, transition zone, and positive correlation zone. The change in the coal pillar width does not affect the pressure relief range or the degree of pressure relief in the adjacent coal seams below the goaf. The field measurements show that after the mining of panel #81,505, the permeability coefficient of coal seam #11 under the goaf increased from 0.1434 to 26.3545 m2/( MPa2*d), increasing 182.7 times, and the drainage mixing volume of boreholes #1 and #2 increased from 1.24 to 1.52 m3/ min. While the permeability coefficient of coal seam #11 from 12.5 m in the coal pillar has only increased by 2.6 times, the drainage volume of boreholes #3 and #4 did not change significantly.

Nov 19, 2022

By Gerry Norton

The purpose of this paper is to make the most complete assessment of coal cleaning methods, both process and equipment related to modern-day production and environmental requirements. In order to achieve this primary objective, a number of interdependent aspects of coal cleaning technology require evaluation and analysis. 1.0 CLASSIFICATION OF SEPARATION PROCESSES Processes and cleaning equipment can be categorized according to the important parameters of 1) mechanics of separation, 2) size range application, 3) range or variance in accuracy of separation related to 2) above, and 4) feed-size ratio affecting 3) above.

Jan 1, 1977

By Ahmed Alghamdi, Salem AlGharbi, Aisha AlHarbi, Owain Morton, Norah AlMuhaisen

This paper addresses the challenges in optimizing the phosphate flotation process, specifically focusing on the variability in P2O5 recovery. An artificial intelligence (AI) driven Flotation Prediction Model was developed to accurately forecast P2O5 grades. Leveraging real-time data from various operational sources, the model provides insights into how operators can opstimize key flotation parameters to enhance product quality and recovery rates. The results demonstrate the effectiveness of AI predictive modeling in addressing operational variability, marking a crucial step toward intelligent operations in the phosphate flotation process.

Feb 1, 2025

By D. R. Zhu, H. S. Chiang, Y. M. Jiang, S. S. Peng

Two types of underground tests on three types of shield supports, 2-leg, 4-leg, and chock shield, were con- ducted to measure the horizontal movement of the canopy against the immediate roof. In no friction tests, steel rollers were placed between roof and canopy top, while in friction tests normal direct contact was used. Results indicate that the canopy for 2-leg shields always moves forward during setting, whereas there was no forward movement for 4-leg or chock shields. Based on the test results, a model for active horizontal force was proposed.

Jan 1, 1990

By K. Hebbar, R. G. Reddy

The viscosities of various FeO-SiO2 slags were calculated using a previously developed structural-based model. Using hole theory and the atomic pair model, an expression was derived to relate the viscosity to temperature and the fraction of the bridging oxygen in silicate melts. The deduced equation was successfully applied to predict the viscosities of FeO-SiO2 slags in the composition range of 0.1 < XSi02 < 0.423 for several temperatures. The calculated data agree well with the experimental viscosity data.

Jan 1, 2002

By Michael V. Wolski, Ryan O. McCarter, Kenneth A. Johnson

"The Central Subway is Phase 2 of the San Francisco Municipal Transportation Agency’s (SFMTA) Third Street Light Rail project and will extend the existing Phase 1 initial operating segment from its current connection to the Embarcadero line at Fourth and King streets along Fourth Street to Market Street, under the Bay Area Rapid Transit (BART) and Muni Metro tunnels and then north beneath Stockton Street to Chinatown (Fig. 1).Total new track to be constructed as part of the Phase 2 work consists of approximately 734 m (2,410 ft) of surface track and 2,636 m (8,650 ft) of tunnels. The tunnels were constructed as twin, singletrack bores by two tunnel boring machines (TBMs) (Johnson, 2014) moving north from the southern end of the launch box under the I 80 freeway between Bryant and Harrison streets. North of Chinatown Station the TBMs continued another approximately 683 m (2,240 ft) to a retrieval shaft near Columbus Ave. at Washington Square. The project also includes five cross passages to connect the two tunnels, and three underground stations (the Yerba Buena/ Moscone Station, Union Square/Market Street Station and Chinatown Station.)Excavation of the twin tunnels was performed with two TBMs, with both TBMs driving northward from the launch box. TBM excavation was performed such that the location of the machines was staggered to separate the active excavation faces by a minimum of 91 m (300 ft) between headings. This minimum separation was maintained until the first TBM arrived at the retrieval shaft plug, at which time the separation requirement was relaxed.Excavation began with the “southbound” (SB) tunnel which will ultimately accommodate the southbound TBM light rail trains followed by the second TBM in the “northbound” (NB) tunnel. With the completion of the drives in June 2014, cross passage excavation then began and was completed in April 2015. Overall, construction of the Central Subway tunnels was a success considering the nature and complexity of the project. Additional details of the completion of the Central Subway tunnels are presented in another paper from the RETC 2015 conference (Leong et al., 2015)."

Jan 1, 2015

By R. G. Reddy

Solid state reduction of roast movat chromite ore with carbon was carried out as a function of C/FeO ratio and temperature in the range 800°C to 900°C by thermogravimetry analysis (TGA). A two stage mechanism, (1) the reduction of FeO present in Roast Movat with carbon monoxide; and (2) the regeneration of CO by the oxidation of carbon with CO2 was proposed. The rate controlling step is the carbon oxidation reaction. A kinetic equation, that of random nucleation, was proposed. The activation energy for the reduction was determined to be 55800 J/mole and is compared to those activation energies determined for other chromite ores.

Jan 1, 1998

By Chikaosa Tanimoto

INTRODUCTION Bratislava is located at the intersection of important traffic routes, including motor-ways, roads, railways, air traffic, trading, and inland waterway with an important harbour. The construction of the D2 Motorway Bratislava, Lamacska cesta Stare grunty was the last missing section of D2 Motorway and its completion linked the Czech Republic through Bratislava to the Hungarian Republic. Traffic was obliged until its completion to use the Lamacska Road and Mlynska Dolina, which were the most heavily trafficked roads in the city. The section of D2 Motorway to be completed in 2006 was 3,300m in length, of which the SITINA Tunnel was approximately half the length. After putting into operation the transit traffic(motorway) and urban traffic was separated. Transit traffic by passing the town was eased. The junctions D2 with Lamacska Road (Harmincova) and Mlynska Dolina also allowed better use of the motorway for the urban traffic The tunnel construction was specified by the features with the highly weathered and thermally altered granitic rock formation with the overburden of Quaternary sediment of 2?4 m thick, very thin overburden, severely controlled deformation limit and environmental protection. The tunnel had to be excavated beneath and nearby the academic complex area and the zoo, where sensitive facilities exist and animals live in. The tunnel consisted of two tunnels (Tunnel A and B) with the length of 1,415 and 1,440 m, respectively. The overburden thickness was in the range from 10?30 m. The standard cross-section and the one with invert arch were 79.5?81.5 m2 and 92.1?93.3 m2. The excavation took 21 months from September 2003 to May 2005. The construction was based on the concept of NATM. The SITINA Tunnel was the third application of NATM in Slovakia, following the BRANKISKO Tunnel (commenced in July 2003) as the first and the HORELICA Tunnel (in October 2004) as the second NATM practice. To protect the surrounding structures and citizens from tunneling operations, seismic monitoring was performed in association with blasting. The allowable limit of blasting vibration was fixed to be under the particle velocity of 15 mm/sec. The tunnel excavation cleared this limit as expected before construction. In driving through the difficult geological situation the excavation work hit 49 faults, and some of them occasionally caused serious face instability. In principle, the rock formation has been affected by the high hydrothermal effect and the resultant clay filing along faults and joints. The auxiliary reinforcement with the 4?8 m long pipe roofing was needed to protect the vicinity of mining face area. This operation extraordinarily required additional works and time which had not been expected before construction.

By Marianne Snedeker

In September 1985 we published a questionnaire asking about the content of MINING ENGINEERING and about your interests. By Dec. 10, our cutoff date, we had 430 responses, representing about 1.5% of the 28,238 people who received the September issue of ME. In the data that follow the tabulation and percentages are based on the number of individuals who responded to the particular question. About ME Through responses to the questionnaire, we were hoping to learn more about you, your interests, and how the magazine could better serve you. Those of you who responded told us something positive - you look at or read the magazine. Of the 430 respondents, 428 or 99.5% indicated that they had read or looked through the July and/or August issues. Those of you who refer to the magazine once are 207 or 48.5%. Those of you who refer to the magazine two or three times are 193 or 45.2%. Those of you who refer to the magazine four or more times are 27 or 6.3%. How much time do you spend reading the magazine? Of those responding to this question: 64 spent up to 1/2 hr 15.0% 224 spent up to 1 hr 52.6% 115 spent up to 1-2 hr 27.0% 23 spent more than 2 hr 5.4% In an informal survey among our staff, we determined that most people spend 1/2 to 1 hr reading magazines to which they subscribe at home. Does that match your experience? Many of you, 335 or 79%, clip your magazine for further reference. Also, many of you, 313 or 73.6%, do not pass your copy on to another reader, indicating that you are clipping it or receiving the magazine at home. Those magazines that are passed on reach: 1 person 3 0.7% 2 people 64 15.1% 3-5 people 34 8.0% 5 or more 11 2.6% Answers to what portions of the magazine you find useful indicated that the top three were Industry Newswatch, feature articles and Technical Papers; see Table 1. The "other" category included advertising - display, classified, Employment, and Professional Services - Washington Survey, New Products, Free Literature, book reviews, technology news, and Coming Events and Short Courses. We asked your appraisal of the technical level of the magazine. Of those responding, 39 or 9.1% indicated that it is too technical, 55 or 12.8% indicated it is not technical enough, and 335 or 78.1% judged it to have the correct technical level. In response to the question about whether you like to read an occasional feature that is not technically oriented, 21 or 5.1% said no, but an overwhelming 94.9% (393) said yes. Of the specific

Jan 1, 1986

By Marcelo de Oliveira, Antoine Allanore, Dennis P. Chen, Davide Ciceri

Potassium fertilizers (potash) are mined in a handful of countries in the Northern Hemisphere. Potash is either expensive or unavailable to the farmers of the Southern Hemisphere. Alkaline alteration of K-feldspar rock (ultrapotassic syenite) in autoclave in the presence of Ca2+ generates a mixture of K-bearing calcium-aluminum-silicate-hydrate (C-A-S-H) minerals that potentially can be used as an alternative local fertilizer. This work investigates the effect of processing temperature (200 °C, 220 °C, and 230 °C) and time (from 0.5 to 3.0 h) on pH, mineralogy, and elemental availability of the C-A-S-H mineral mixture. Increasing temperature results in an increased conversion of K-feldspar and increased content of both the mineral tobermorite (Ca5Si6O16(OH)2·4H2O) and amorphous phase in the resulting C-A-S-H mixture; increasing time results in an increased conversion of α-dicalcium silicate hydrate into tobermorite. The amount of K leached from the mixture is relatively constant across all processing conditions. Hydrothermal alteration in autoclave of K-feldspar-bearing rocks such as ultrapotassic syenite permits the synthesis of a potential potassium fertilizer which alkalinity and mineralogy can be tailored according to soil requirements.

May 22, 2020

By Ali Yalçin

The study area is located in the NW of Uluborlu (Isparta). Massive limestones and alluvial deposits form the lithological units of the study area. The average thickness of the alluvium deposit consisting mainly of light brown - red colored and fine grained clastic sediments which derived from the limestone is about 10 meters. The aim of this study to investigate the uses of this alluvial sediments as tile - brick material. For this aim, disturbed and undisturbed samples have been taken from different depths in the alluvial deposits. Mineralogical compositions have been determined by XRD and major oxide contents by XRF. Laboratory experiments have been carried out to determine the technological properties of the samples. The selected major oxide contents of samples vary between A12O3 (24.6 - 24.12 wt %), CaO (0.76 - 4.27 wt %), Fe2O3 (10.21 - 10.29 wt %), MgO2 (1.25 - 1.51 wt %). CaCO3 and MgCO3 values calculated from the geochemical analyses, are between 1.55 - 1.62 and 2.62 - 3.17 respectively. The ratios of grain size of the samples are 82 % for < 0.2 mm and 5 % for > 3 mm. Geochemical analyses and technological features of the samples indicate that these fine grained sediments of alluvial deposit are suitable in terms of uses as tile - brick material. The potential reserve of this tile - brick material has been determined as 40 million tones.

Jan 1, 2005

By G. R. Struble, J. R. Marks, A. B. Brown

The center of mining at the Homestake gold mine in Lead, SD, is moving deeper every year. As a result, it has become necessary to upgrade the ventilation system. This paper describes the first phase of a scheduled two-phase upgrade - installation of a 2.2-MW (3000-hp) centrifugal fan. The higher pressure fan is required to route larger airflows into the deeper production levels. Selection of the fan began by specifying the necessary operating point to provide these larger airflows. Special site work had to be done on the surface to accommodate the new fan structure as well as underground to reroute airflows.

Jan 1, 1987

By B. Pregerson, M. Gaft, J. Rabinowitz

The main phosphate minerals, apatite and francolite, are characterized by intensive selective photoluminescence, connected with impurities of Eu2+, Ce3+, V4+, Mn2+ and (UO22+ ). The non-uniform distribution of phosphate minerals in lumps makes photoluminescence sorting possible. As result, an intermediate product is recovered which is enriched by P205 and has relatively small amounts of chert, dolomite, calcite, fluorite, etc. In the case of Zin Phosphate Plant coarse rejects, for example, it is possible to separate a product enriched by francolite, practically free of chert and with a lowered calcite content. This material is suitable for flotation, with a potential 6-7 % increase yield of concentrate.

Jan 1, 1993

By W. V. Liu, D. Omane, H. Yu, Y. Pourrahimian

"A large-scale wildfire had broken out at Fort McMurray in Alberta, Canada during May 2016. Many oil sands mining activities were affected due to the wildfire and the associated ash emissions. In particular, ash emission generated from the fire outbreak is a huge problem during the post-fire cleanup. These emissions pose a severe health hazard to workers, environment, and global climate. The ashes emitted into the atmosphere are caused by either human activities or climate conditions. The objective of this research is to assess the effect of three different ash dust suppressants, namely water, #1 surfactants, and #2 polymers at various volumetric concentrations on ashes samples to prevent propagation of fine solid emissions into the atmosphere. It is found that both #1 surfactants solution and #2 polymers solution are effective in retaining fugitive ash dust generated from the ashes. Volumetric concentration efficiency of 0.05% of #1 surfactant and 5% of #2 polymers in 500 ml of water have been proven to provide ash dust retention efficiency greater than 99% after the spraying of these suppressants. It is also found that both #1 surfactants solution and #2 polymers solution maintain an ash dust retention efficiency higher than that of the use of only water. This confirms the merit of using chemical dust suppressants on fugitive ash dust for a longer period, which is proven by the 72-hour data from this experiment. This study gives a general view of how effective chemical suppressants on fugitive ash emissions work. INTRODUCTION On May 1st, 2016, a large-scale wildfire gutted Fort McMurray, Alberta, Canada. Many oil sands mining activities were affected due to the wildfire and the associated ash emission. Due to the wildfire, some of the biggest oil sands companies in Fort McMurray such as Royal Dutch Shell and Suncor Energy shut down their oil production, at 255,000 and 350,000 barrels per day respectively [1]. Syncrude Canada Ltd scaled down its normal production capacity level of 350,000 barrels per day [1]. This generated an estimated loss of about 1.1 million barrels of oil production per day, constituting a 30% reduction in the Canadian daily oil production, crippling the economy [2]. This loss in production by the companies translated into 0.33 % of the Alberta GDP in 2016 constituting a loss of $985 million and 0.06 % of the entire Canadian economy [3]. In 2017, it is estimated that the rebuilding and reclamation of the affected areas in Fort McMurray will add $ 1.3 billion in GDP to Alberta’s economy [3]. A population of over 90,000 people was evacuated from the location and its surroundings for health and safety reasons [4]. The fire destroyed about 2,400 structures and over 500,000 hectares of forest vegetation in Fort McMurray, leaving an estimated 232,000 tonne of post-fire ashes [5,6]."

Jan 1, 2017

By T. H. Dubaniewicz, J. E. Chilton

The U. S. Bureau of Mines is investigating the application of fiber optic technology to methane and carbon monoxide monitoring. A methane monitoring system is described that is based on differential absorption of infrared light. It can detect concentrations as low as 0.2% and as far away as 2 km via fiber optic cable. The upper range is 100% methane. The system requires no electrical power within the mine so it should operate safely under mine disaster conditions. A hybrid carbon monoxide monitoring system is described that combines a low-powered electrochemical cell with fiber optic telemetry. Testing has shown the system can operate maintenance- free for several months.

Jan 1, 1992

By K. Kavouridis

The energy and climate protection policy of European Union (EU), and its Member States adopted in 2007 bridges security of supply, environmental protection and competitiveness. The objectives of the EU energy and environmental strategy cover the foreseeable period till 2020. It assumes all sources of energy will be needed. The objectives for renewable and improved efficiency are ambitious; it must be established if they are also realistic. Coal can continue to make valuable contribution to the security of supply and low price of electricity, only with technologies allowing for drastic reduction of the CO2 emitted of its combustion. The aimed at -20% reduction of green-house gases (GHG) of EU-27 by 2020 is an objective limited in time and content. Europe produces less than 15% of global CO2 and this will be reduced to 10% in 2030. Emissions Trading (ET) is to remain the central instrument for CO2 management, especially in the power sector. ET scheme (ETS) or other mechanisms need designing to create an incentive for investment in higher efficiency and technologies and to Carbon Capture & Storage (CCS). The ETS as the climate protection instrument of the EU can become a heavy burden (high fuel and electricity prices, less security of supply) or it can create a climate for modernization of fossil fuel power plants. The suggestion in this paper of fuel-specific benchmark system for CO2 allocation after 2012 can combine the emission levels to be reached with a strong drive to invest, the necessary investment security, transparency and the principle of proportionality. A Benchmark System as recommended by coal industry could adapt to the different circumstances in the long term and comply with EU energy and environmental policy objectives.

Jan 1, 2008

By KAGAN BENZESIK, OMUR CAN ODABAS, SELCUK KAN, Onuralp Yucel

In this study, domestic molybdenum disulfide (MoS2) concentrate was roasted in a chamber furnace and then in a rotary kiln. The behavior of the roasting process was examined in both furnaces, and which type of furnace is more advantageous to use in mass production was investigated. It is theoretically possible to roast in a chamber furnace, but a major problem was observed when the amount of concentrate was increased in the chamber-furnace experiments. The problem was solved by using a rotary kiln. This study improves the understanding of the roasting of  MoS2 concentrate and presents a different perspective to the industry, showing that rotary kilns can also be used for roasting.

By G. Belardi, N. Sheau, P. Plescia, F. Veglio

A study was conducted to assess a new wet gravity-separation machine, identified as the Multi-Gravity Separator(MGS). Chromite fines, obained from an Albanian chromite and olivine ore and containing 23% Cr2O3 and 18% SiO2, were used in the study. The first step was to determine the influence of various operating parameters. The study indicated that the most important variables for the MGS are rotational speed, tilt angle and shake amplitude. The best treatment conditions for the ore were then identified by investigating a series of circuits designed to produce a marketable product. In open circuit, a concentrate containing 50% CI-203 was obtained with a recovery of 72%.

Jan 1, 1996