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By Tamara Nestorovic, Luan T. Nguyen

"With the aim to mitigate excavation risks and reduce the costs caused by tunnel boring machine (TBM) stoppage when tunneling under uncertain soil conditions, prediction ahead of the tunnel face has become an increasing interest in the tunneling community. Our research topic is concerned with developing effective concepts for nondestructive identification of geological anomalies ahead of the tunnel face by waveform inversion of reflected tunnel seismic waves. The authors demonstrate that this new technique is promising in providing tunnel engineers with an accurate image of the geological situation that the TBM is going to encounter thanks to the waveforms’ rich information about the geological structure that affects propagation, reflection/refraction and mode conversion behavior of the elastic waves. By setting up a 2-dimensional numerical model for simulation of tunnel seismic wave propagation influenced by a dip layer change ahead of the tunnel face, the authors show that the waveform misfit to be minimized by the inversion process is highly multimodal and therefore propose a hybrid stochastic optimization method that can quickly and robustly converge to the global minimum. DEVELOPMENTS IN TUNNEL ADVANCE EXPLORATION Conventional site investigation by drilling boreholes helps to draw a general image of geological structures along the borehole axes but that image is likely to misrepresent the detailed geological structure due to limited sampled locations. Due to high costs and restricted boring space which deep tunneling and tunneling under urban areas encounter, many industrial and academic research groups have had great interest in developing nondestructive ahead of the tunnel face prediction systems. That means only excitation sources and receiving sensors, which are usually placed on the ground surface or on the side walls or on the cutter head of the TBM, are used for acquisition of the measurement data. The recorded signals in the form of seismic or electromagnetic/ electrical waves, which travel through the geological structure or are reflected back from it, hold the signature of the geological structure of concern, such as geological layer changes, fault zones, erratic rocks, boulders, construction remnants, etc., and therefore can be used to reconstruct the spatial and material properties of those hidden geological structures. Most common nondestructive ahead-of-tunnel investigation systems to date are based on interpretation of reflected elastic/ acoustic waves (seismic waves) and analysis of electromagnetic/ electrical resistivity signals (Mooney et al. 2012). However, due to insufficient penetration depth and spread of signals generated by radar and geoelectric sources, the use of seismic waves for ahead of the tunnel face prediction (tunnel reconnaissance) is more preferable (Kneib et al. 2000; Bohlen et al. 2007)."

Jan 1, 2016

By F. Calizaya

This paper explains and discusses a computer program developed to determine the ventilation design parameters for complex auxiliary ventilation systems such as those found in the construction of long excavations with multiple headings. The program is based on the principle of partitioning the system into segments of finite length, and formulating and solving the resulting networks recursively. The application of the program is illustrated by the detailed solution of an auxiliary ventilation system proposed for the Exploratory Studies Facility (ESF) at the Yucca Mountain project, Nevada.

Jan 1, 1994

By P. W. Finck

Detailed mapping, using a large diameter diamond-drill in conjunction with high resolution reflection seismics, has increased known resources of kaolin clay and glass-grade silica sand from scattered deposits generally < 1 km2 to large areas of Cretaceous valley fill up to 130 m thick. Detailed chemical and physical analysis of drill core is presently underway. Silica sand deposits intersected in this study are up to 99.4 % SiO2 without beneficiation. Light grey to white kaolin clays identified by XRD and DT A have concentrations values (without beneficiation) up to 47.28% SiO2, 37.44% Al2O3, 0.45% Fe2O3, 0.49% K2O, 0.07% Nap, 0.07% CaO and 0.39% MgO.

Jan 1, 1996

By Georgios Kafantaris, Carsten Bonde, Nataša Katic

Within the investigation works for the Copenhagen Cityring metro, Geo/CMT have carried out 90 geotechnical boreholes. Together with the previously available investigation, this resulted in more than 15 km of vertical drillings and several thousands of laboratory tests. The design is made for 17 stations, four shafts and two parallel 16 km long tunnels. The geotechnical investigation and design have been carried out in several stages comprising appropriate refinement of structural design and design of excavation operations, including TBM break-in and launching operations at each station shaft. Acceptance of the solution and / or refinement of the investigation and design schedule in the next stage were based on the geological conditions, area availability at surface level, planning and cost-control criteria. The applied recursive design refinement is presented herein with an example of the Østersøgade shaft location.

Jan 1, 2016

By B. DANIEL MARJAVAARA, I. A. SOFIA LARSSON, ANNA-LENA LJUNG

One way to upgrade iron ore is to process it into pellets. The pelletizing process is multifaceted, involving complex fluid dynamics with highly turbulent, high-temperature flow in intricate geometries. This makes it hard to perform measurements during operation, so a useful tool for better process understanding is computational fluid dynamics (CFD), where the challenge is to perform efficient and trustful simulations of complicated problems. A validated simulation model can be valuable for increased process control and development. In this paper, the flow field and coal combustion process in a pilot-scale iron-ore pelletizing kiln is simulated using a CFD model. The objective of this work is to apply a coal combustion model to enable an investigation of thermal effects from the flame on the surrounding flow field.

By Dennis C. Martin

Assessment of the potential for mining induced subsidence and determination of ultimate design requirements for a mining operation should be based on a number of assessment approaches. Although the rock mechanics engineer has a variety of limit equilibrium and numerical modeling tools available for assessment and prediction of subsidence effects, empirical approaches based on precedent experience provide a powerful tool for calibration/verification of analytical models and prediction of subsidence. Three separate analyses approaches have been applied to the assessment of potential subsidence for a proposed block caving mine in eastern Canada. The investigations have included an assessment of documented historical information from previous block cave mining at the site, deterministic analyses using limit equilibrium approaches to assess kinematically possible failure mechanisms, and three-dimensional numerical modeling techniques. Analyses results have been used and compared with precedent experience and documentation of subsidence behavior from previous mining to optimize the subsidence predictions for the proposed mine.

Jan 1, 1998

By Ulrich Kappus

The purpose of the project is to divert flood flows of North Potato Creek. The project is located in the southeast corner of Tennessee near Copperhill, approximately 160 kilometers north of Atlanta, Georgia. The project consists of: a 28-meter high dam, a 90-centimeter diameter outlet conduit; an emergency spillway; and a 4.0-meter diameter hard rock trans-basin diversion tunnel. This floodwater management system was part of Cities Service Company mine safety program for the Cherokee orebody which is partially located within the stream channel. The following paper describes the entire project development from feasibility studies to design and construction management.

Jan 1, 1978

By Gleason

"From June 16 to 19, more than 1,400 tunneling and underground construction professionals gathered in Chicago, IL for the bienial Rapid Excavation and Tunneling Conference (RETC). There, they were greeted by a full technical program and an exciting exhibit hall that provided a comprehensive look at the world’s bustling tunneling and underground construction industry.The successful conference was a reflection of the industry itself, which is to say, busy. As much of the world has begun to focus on creating a cleaner and greener environment, the global tunneling industry has seen an uptick in infrastructure projects move from design-build to construction phase. With a global shift away from the use of fossil fuels, major cities around the world are looking to increase public transportation options, which leads to the need for more transportation tunnels. And as urban populations continue to grow, the need for clean water calls for more tunnels, and as urban footprints continue to expand, the need to increase and update combined sewage overflow tunnel grows with them.During two and a half days, more than 20 sessions covering all of these topics were presented at the Hyatt Regency in Chicago, many to packed rooms in which every seat was taken and people were standing along the side and back walls.RETC is a biennial conference and one of the largest in the North America for the tunneling and underground construction industries. As such, it hosts a robust exhibit floor. This year 172 vendors occupied 205 booth spaces. The exhibit included everything from tunnel boring machine manufacturers, like Robbins and Herrenknecht, to the companies that supply all kinds of parts and services to the industry."

Sep 1, 2019

By Frank F. Aplan, G. Rinelli

INTRODUCTION Coal is a solid, combustible mineral substance resulting from the degradation and alteration of vegetable matter largely in the absence of air. In this natural process of coalification, some non-combustible mineral matter is always associated with the combustible material. Coal preparation or cleaning is the process of removing this inert mineral matter from the coal. Preparation is highly successful in removing the large fragments of inert material, but is not very effective in removing the fine inorganic mineral matter intimately associated with the coal. Of the 600 million tons of coal produced in the United States every year, approximately one-half is produced by coal cleaning methods (1). The bulk of this tonnage is cleaned by coarse or intermediate gravity preparation methods (5 inches to 28 mesh, Tyler). Fine cleaning, say, -28 mesh, is done by shaking tables, washing cyclones, and flotation, or, until recently, the fines were either incorporated into the clean coal or simply discarded--not infrequently, the latter. In 1972, only 13 million tons of raw coal were cleaned by flotation in the United States, and from this 8.4 million tons of clean coal were produced (1). The percentage of clean coal produced by flotation in Europe (England, West Germany, Poland, U.S.S.R., etc.) is substantially higher. However, coal flotation has grown rapidly in the United States from only a few plants in 1950 to 31 in 1960 (2) and 66 in 1970 (1). Virtually all new preparation plants incorporate flotation into their basic flowsheet. The essential difference between ore and coal flotation is that for ores the entire tonnage is ground to flotation size, whereas for coal

Jan 1, 1976

By F. Taylor Ostrander

Some countries are infinitely poorer than others in mineral resources-despite the perfect equality of their political leaders ambitions. Compare the mineral poverty of Kenya and Tanganyika with the riches of Katanga Province and Northern Rhodesia. Compare Paraguay with Chile, There never has been any equality in the distribution of nature&apos;s wealth. Minerals cannot play any role at all in economic development where they don&apos;t exist, and there are bound to be differential rates of economic development where there are basic differences in the wealth of mineral resources available. Africa is my principal area of interest and I know that there is an unfortunate but widespread misconception about Africa&apos;s "vast mineral resources, "its "untapped mineral wealth." Why is it untapped? Why is it undeveloped?

Jan 1, 1963

By J. Christophe Niyonzima, Ekata Emmanuel Edo, Sayaf Mustafa, Liqun Luo

Iron and manganese both are important ferrous metals, and they usually need to be extracted separately for better usage. Ferromanganese ore from the Yunnan Province of China was investigated by subjecting it to reduction roasting, leaching, magnetic separation, hydrometallurgical separation process, X-ray diffraction (XRD), electron probe micro-analysis (EPMA) and scanning electron microscopy/energy-dispersive spectroscopy (SEM-EDS). It is noted that the ferromanganese ore contains valuable components or elements of 21.41 wt%Fe2O3 and 19.88 wt%MnO, which are 14.99% and 15.40% of the total of Fe and Mn, respectively, with a large amount of impurities comprising 33.00 wt% SiO2, 9.81%wt%Al2O3, etc. After roasting, microscopic examination showed the presence of haematite, magnetite, pyrolusite, psilomelane, hollandite, marcasite, pyrite, limonite, braunite and manganite, while XRD analysis showed that the magnetite content increases with the increase in roasting temperature, reflecting the increase in conversion of haematite to magnetite. Based on EPMAand SEM-EDS analysis, it was shown that the haematite and magnetite interface were the main Fe-bearing minerals; however, the dissemination of the two minerals, that is, haematite andmagnetite with the coexistence of Fe- and Mn-bearing minerals, will result in difficulty in effective separation of Fe and Mn. The effective roasting temperature and roasting time were 800 °C and 60 min, respectively, to avoid the formation of a composite oxide of MnxFe3-xO4 beyond 800 °C. The Fe recovery via roasting and magnetic separation only was 66.56%, whereas a combination of magnetic separation which ensued after the leaching process showed a recovery of 80.08% and 59.95% of Fe and Mn, respectively.

Mar 26, 2021

By H. Shafick Hanna

The beneficiation characteristics of low grade Birmingham red iron ores of the Big Seam and Ferruginous Sandstone seams were investigated using flotation and magnetic separation after reduction roasting. Samples of Bib Seam Ore responded more readily to concentration than the Ferruginous Sandstone ores. The impurities inherent with the iron oxide minerals limit the grade of concentrates recoverable from these ores to a maximum of about 61% Fe if reasonable iron recoveries are sought. Flotation concentrates assaying 60-61% Fe and about 0.1% P with attendant iron recoveries of about 63% were achieved from Big Seam ore charges while those obtained from the low phosphorus Ferruginous Sandstone samples analyzed 54-56% Fe. Reductive roasting and magnetic separation of ground charges of the two ore samples yielded concentrates assaying 60-61% Fe. Iron recoveries were better than those achieved by flotation, but the magnetic products of Big Seam ore were high in phosphorus (0.2-0.3% P).

Jan 1, 1983

By Dae S. Young, Steven F. Hoerger

The geostatistical method of indicator kriging (IK) was extended to analyze two-dimensional distributions of rock joint orientations. The IK method provides a non-parametric approach for spatial analysis of local probability distribu- tions. By taking into account the spatial correlation of rock joint outcomes and the relative geometry between estimation unit and samples, the IK method provides optimum, spatially conditioned estimates. The estimation method was tested by comparing distributions of actual mapped rock joint orientations with their corresponding kriged estimates. The comparisons show the unbiasedness and accuracy of the non-parametric approach for estimating local probability distributions.

Jan 1, 1986

By Juan L. Yarmuch, Gonzalo Sepulveda

This article presents a novel approach to address the mining width-constrained open pit mine production scheduling problem in the context of medium-term planning. A mathematical formulation is proposed to incorporate mining width constraints into the production scheduling process, aiming to maximize the NPV of the schedule while ensuring enough room for the operation of mining equipment. To tackle the computational challenges posed by large-scale instances of the problem, we propose a method based on variable fixing and horizontal precedence generation. In this study, we apply the developed model to real-world scenarios from Radomiro Tomic short-term mine planning problems such as optimizing the timing of major truck maintenance and the impact of external factors, like the delay in the production of the Chuquicamata underground project. Remarkable improvements are observed with the mining width-constrained model. Specifically, the mining width satisfiability is enhanced from 2 to 60% compared to the traditional open pit mine production scheduling model, underscoring the significance of incorporating these constraints. The proposed method showed good results reaching optimality gaps within 5%.

Mar 28, 2024

By Cheng Xie, Zhihu Li, Xiaoming Sun, Linsen He, Jiaxu Ding, Jinkun Yang, Yong Zhang, Zhenmin Qi

To solve the problem of large deformation of deep soft rock roadway, taking the soft rock roadway of no. 1 coal mine in New Shanghai as an engineering example, the deformation mechanism of surrounding rock of deep soft rock roadway is analyzed by combining theoretical analysis, numerical simulation and field test, and the control countermeasures centering on deep and shallow dense drilling are put forward. Through theoretical derivation, based on the masonry beam theory, surrounding rock structure S-R stability principle and composite beam principle, the length, angle, and spacing of deep and shallow dense drilling are determined. Through numerical simulation, the deformation evolution process of soft rock roadway surrounding rock after dense drilling pressure relief is reproduced, and the influence of drilling parameters (drilling spacing, dip angle) on pressure relief effect is analyzed and compared. The field application test and monitoring verify that the deformation control measures of deep and shallow dense drilling broken roof surrounding rock have a good effect of large deformation control of soft rock roadway, and provide a new support means for the safety and stability control of soft rock roadway.

Mar 2, 2024

By David R. Delling

Introduction In 1967, Tenneco acquired Kern County Land Co. The primary reason for the acquisition was to obtain Kern&apos;s agricultural, manufacturing, and oil interests. Included in the Kern portfolio were the core of Tenneco&apos;s present sodium leases in Sweetwater County, WY. This lease base has been ex¬panded and now consists of 62 km2 (24 sq miles). Beneath this property lies more than 500 Mt (550 million st) of economic trona ore. Following the Kern acquisition, Tenneco continued exploration and feasibility studies concerning the trona leases. The effort was accelerated in 1976. Tenneco was attracted to trona because of the favorable lease position it held, the growth rate of the Wyoming industry during the 1960s and 1970s, and the prospects for a long-term, stable business enterprise. The reserve picture was certainly attractive to a company long accustomed to the never-ending struggle to replace oil and gas reserves. In 1978, Wyoming was a boom area that had experienced rapid growth for a number of years. Unemployment was very low and vacant housing nonexistent. The prospects for soda ash were somewhat different in the 1970s than now. But it was recognized even then that a new producer would have a challenging task to compete in this business. Tenneco knew the capital burden required to build a grassroots facility during inflationary time, would have to be offset elsewhere Since labor and energy are the dominant direct costs in mining trona and producing soda ash these factors have always received a great deal of attention. Contracting and permits Environmental monitoring on the site began in late 1977. With the already mentioned considerations in mind, engineering began by mid-1978. Brown & Root Inc. was selected as the general contractor for the project. S. A. Scott & Co. was the engineering subcontractor for the mine shafts, hoists, ventilation system, and miscellaneous mine facilities. Frontier-Kemper was awarded the contract for sinking the two mine shafts. Acquisition of numerous federal, state, and local permits occupied all of 1978 and 1979. The Wyoming Industrial Siting Permit, which addresses socioeconomic issues, drew the most public interest. Siting issues were all satisfactorily resolved by negotiating reasonable stipulations with various local governmental units, school districts, and the like. Site location The Green River project location is not truly remote. It is located within 5 km (3 miles) of Interstate 80 and only about 32 km (20 miles) west of the city of Green River. Nevertheless, a substantial investment had to be made in communication and utility links to the site. These included: • A 14-km (8.5-mile) rail spur connecting with the Union Pacific Railroad at Bryan, WY. This spur has four bridge structures including one crossing Interstate 80. Most soda ash is shipped by rail, and coal is received over this line as well. • A paved 5-km (3-mile) roadway connecting to Interstate 80. • A powerline extension of about 27 km (16.5 miles), along with two new substations. • A 24-km (15-mile) waterline connecting the plant to a pump station on the Green River. The site is located on gently sloping terrain at an elevation of about 2.1 km (6800 ft). Ground conditions are good for construction. Weathered bedrock lies near the surface in most places. Geology The general geology of the Green River Basin has been well described previously. Tenneco&apos;s ore is in several superimposed evaporate beds. But the bulk of it is present in Bed 17, located about 457 m

Jan 10, 1985

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

Incident investigation is of utmost importance in most high-risk industries and is often used to improve organisational safety. This study was undertaken to examine the content of past incident investigation reports to determine the effectiveness of the incident investigations. The study uses a semi-quantitative method to assess the effectiveness of incident investigations in the Ghanaian mining industry by evaluating the quality of past investigation reports. The assessment tool consists of five elements with several indicators and rating scales for assessing the quality of an investigation report as a measure of the effectiveness of the investigation. The method was applied to 304 investigation reports of three Ghanaian large-scale gold mines, and the results correlated with incidence rates of the mines to determine if any relationship existed. The results showed that the mines differ significantly in the quality of their investigation reports, suggesting differences in the effectiveness of their investigations. In addition, the incidence rates of the mines negatively correlated with some elements of the assessment tool. In general, the method was found useful and revealed areas where improvement is needed.

By Liaqat Ali, Robert Chapman, Asghar Ali, Mohammad Tahir Shah, Seema AnjumKhattak, Mohammad Farhan

Alluvial gold is abundant in the Quaternary deposits of the Kabul and Indus rivers in District Nowshera, Khyber Pakhtunkhwa, Pakistan. Understanding the provenance of alluvial gold using morphology and elemental composition could be helpful in developing an exploration strategy of regional benefit. Detailed morphological studies of gold grains revealed high flatness index values which are indicative of a distal source. Compositional studies of 58 gold grains using SEM and EMPA showed broadly similar Ag ranges (1– 15 wt%) for each sample and occasional Cu values in individual gold particles to 0.4 wt%.Whilst the Ag profile is not diagnostic, the Cu values are compatible with derivation from either porphyry systems or ultrabasic rocks. The complex geology of the drainage catchments could host gold mineralization of other styles, but larger sample suites would be required to refine the current interpretation to establish whether particles which are simple Au-Ag alloys could be derived fromorogenic or epithermal sources. This scoping study has demonstrated that the compositional and morphological studies of gold grains are useful in providing information regarding the nature and location of the source of placer gold in areas where there is limited information on the nature and location of in situ mineralization.

Oct 6, 2020

By Sean Masse

New Gold?s New Afton Mine, located 8 km (5 miles) west of Kamloops, British Columbia, is a 4.5-Mt/a (5-million stpy) block cave mine, making it the highest tonnage underground hard rock mine in Canada. The reserve is estimated at 52.5 Mt (55.9 million st) with grades of 0.65 g/t (0.02 oz/st) gold and 0.93 percent copper (2012). Commercial production was achieved in July 2012 and nameplate production was achieved ahead of schedule in September 2012, with the cave breaching to surface in 2013. The mill has a SAG and a ball mill with a froth flotation circuit.

Jan 1, 2014

By M. S. Moats

In the 1990?s, Técnicas Reunidas developed the Modified ZINCEX® Process to recover zinc from ores and secondary materials. The heart of this process was the use of solvent extraction to produce purified zinc electrolyte instead of traditional zinc dust cementation. This development was commercialized by Reunion Mining and Anglo American for primary ore at the Skorpion mine in Namibia with the first SHG zinc produced in May 2003. Horsehead Corporation through Horsehead Metal Products, Inc., its wholly owned subsidiary, is presently commercializing the MZP for the treatment of Waelz oxide. This paper will review open source information about the lessons learned and process modifications that have occurred at Skorpion over the past decade. It will also provide an update on Horsehead?s facility being constructed in Rutherford County, North Carolina.

Feb 23, 2014