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Several major impediments threaten the successful delivery of tunnel and under-ground construction projects. In addition to technical design and construction risks associated with tunnel projects, many of which are well understood, budgetary pressures, funding constraints and the complexity of procuring, administering and executing multiple concur-rent projects in a large program could also have a catastrophic impact on the program?s objectives. Contributing factors often include poorly managed design, procurement, construction, managerial, organizational, market and stake-holder risks, as well as nonconforming inputs or outputs to the costs and schedule, or any other potential inabilities to deliver the required or desired results. A strategy to prevent ?failure? of a project requires a proactive and holistic approach to risk management. Through planning, identification, analysis, management, monitoring and control of the project?s risks (both threats and opportunities), attention to management of risk will in-crease the probability and impact of positive events and decrease the probability and impact of events adverse to a project?s objectives.

By Robert C. Freas

Dravo Lime Company has opened a new 290m (940 ft.) deep lime-stone mine near Maysville, Kentucky. As the mine was opened there were many unknowns as to the stress relationships within the rock, and their influence, if any, on the selected mining method. Therefore, a system of overlay geologic and structural maps, borehold extenso-meter measurements, and oriented photography was developed for the purposes of monitoring the internal structural relationships of the rock mass. This paper presents a description of the methods used, the observations made, and the conclusions and recommendations made as a result of the initial monitoring program.

Jan 1, 1977

By Jamal Rostami, Jürgen Schmitt, Rohola Hasanpour

"Double Shield TBMs can be used in fast track projects for accelerated completion where there is limited information available on ground conditions and there are possibilities of encountering weak ground and shear zones. As such, the shielded TBMs are the primary choice of the machines in long tunnels, but face the possibility of entrapment in squeezing ground, which entails long delays and major risks. This paper examines the possibility of using ground improvement methods to increase ground strength, and thus, increase the capability of the machines to cope with squeezing ground conditions. In this study, 3D finite difference simulation of a shielded TBM in squeezing ground was performed to estimate the operational parameters including required thrust to get a machine out of an entrapment. This analysis was also used to evaluate the possibility of preventing machine jamming by the implementation of pre-excavation ground improvement to increase the strength of the ground. INTRODUCTION In order to face adverse tunneling conditions especially using a shielded TBM in squeezing ground, new shield designs, with extra thrust and torque, step shield geometry with reduced shield diameter from front to the back, and conical shape shields have been used. In addition, many of the new machines have the capability to implement ground improvement at distances up to 50 m ahead of the face in order to reinforce the ground and further increase in their chances to cope with squeezing ground conditions. While these features have been added to the machine, there has not been a thorough evaluation of their impact on improving the chances to avoid machine jamming in weak rocks at high depth, which is conducive to rapid convergence of the ground."

Jan 1, 2016

By G. J. Allen

Kennecott Copper Corporation's Nevada Mines Division initiated a program to stabilize the inactive portions of the tailings disposal area and perimeter dikes in 1946. To date, approximately 1,000 acres have been stabilized with vegetation and ground cover.

Jan 1, 1978

By Dion Weatherley, Raúl Castro, Pablo Cid, René Gómez

In underground mining, hang-ups due to coarse fragmentation are frequently observed in drawpoints, drawbells, and ore passes during ore draw. Hang-ups can often require operational interference and hang-up removal activities. Drawpoint and drawbell design has been shown in some studies to influence hang-ups; however, the full extent of this influence remains open to question. In this study, the discrete element method was used to analyze the effect of hang-ups on three distinct drawbell geometries: the Drawer type, Circular type, and El Teniente type. The drawer type was used as the base case given that data was available from a physical model in which hang-ups were studied. The drawer type base case data was then used to calibrate our numerical model. Results show that the El Teniente drawbell geometry sustained 13% more hang-up events as compared with the base case, while the circular drawbell geometry had 16% fewer hang-up events than the base case. From this study, it can be concluded that fewer hang-up events will occur with a rounded drawbell geometry.

Apr 11, 2023

By Michael S. Moats, John Bailey Fletcher

Wear rates of grinding media can be misrepresented by marked ball wear tests (MBWT). Galvanic interactions between dissimilar grinding media can be affected by the chromium content in the media and the presence of oxygen in the environment. Corrosion, one component of wear, can be affected by many variables. Corrosion rates and corrosion potentials for modern high chromium white iron (HCWI) and high carbon steel (HCS) grinding media samples were obtained through electrochemical testing. In this study, the impact of chromium content in the grinding media and the dissolved oxygen in a simulated mill water solution on corrosion rates and potentials was examined. Increasing chromium content in HCWI above 15 weight percent increases the corrosion potential and decreases corrosion rate. Removing most of the oxygen from the solution lowers both the corrosion potential and corrosion rate of the materials tested. The electrochemical results were examined to model possible galvanic coupling effects on corrosion rates. Galvanic coupling between HCS and HCWI could cause differences in corrosion rates for almost all scenarios modeled. Based on the galvanic coupling analysis, MBWT results could be impacted by mixing HCWI and HCS in a ball mill charge. This impact is predicted to be more significant when dissolved oxygen is present in the mill water and as the chromium content of HCWI is above 15 weight percent.

Dec 21, 2022

By Serdar Aktaş, Özgün Küçükoğlu, Burcu Nilgün Çetiner, Mehmet Hakan Morcalı

This study compares the cementation performance of metallic iron, metallic aluminum, and metallic tin in terms of the reaction conditions and parameters in synthetic antimony chloride solutions. The effects on the antimony recovery (%) caused by the cementators’ types, stirring speed, reaction time, and temperatures were explored thoroughly. The cementation kinetics of antimony were also explored for each cementator. The activation energies were determined to be 10.99, 9.09, and 13.58 kJ mol– 1 for Al, Fe, and Sn, respectively. The results reveal that the reaction is diffusion controlled, and comparable results were obtained for each cementator. At 25 °C, 40 mg of iron powder was found to reduce all antimony ions (i.e., approx. 99% recovery), but even when 100 mg of Al and Sn cementators were used, the antimony recovery did not reach 100%. This result shows that iron is the best candidate to cement antimony out of the solution.

Jan 28, 2022

By R. V. Ramani

An improved mine environment is the single most critical factor affecting the health and safety of workers engaged in underground coal winning. A very important subclassification of this wide field is mine ventilation, which essentially deals with 'mine atmospheric environmental control.' To ensure proper mine atmospheric environmental control, adequate quantities of air must flow through working sections in the mine. In recent years much attention has been paid to the fan and its prime movers, but the efficient use of the fan output in the workings has not received an equal amount of investigation. In mechanically ventilated mines friction losses in main airways often account for 70 to 90 percent of the total pressure loss sustained in the system. Also the leakage losses are a serious detriment to the efficiency of mine ventilation systems. It is not uncommon to loose 60 to 70 percent of the air between the fan and the last open cross-cuts due to leakage directly into the return Proper assessment of these losses in simulating and projecting complex ventilation systems is vital. Network analysis of ventilation systems is not new. Scott and Hinsly (1951) presented the detailed mathematical framework. Since then work has been done in adopting this technique to analog, and within the past few years, to digital computers. Development of computer programs to solve ventilation network problems has been reported in United Kingdom, Japan, U.S.S.R., South Africa, Germany, and the United States. The purpose of these programs is to serve as an experimental mine wherein analysis of proposed alternatives or ventilation planning can be tested. The great power of the computer as a planning tool lies in the ability to input empirical or Projected data into programs with predicting ability. But, however good a computer program is, unless fairly accurate input information is available accurately assessing the engineering factors of the ventilation system, the output will be suspect. Thus, to simulate and project mine ventilation systems, good estimates of leakage and friction factors are important. Yet, relatively little work has been done in the past three decades to determine these more realistically.

Jan 1, 1973

By Nicole R. Henderson

Many mining engineering graduates enter the mining industry lacking training in mine emergency management. As a result, mining universities in the United Sates and other countries are beginning to form volunteer student mine rescue teams to train mining engineering students in handling mine emergency situations and give them hands-on experience managing potential emergency scenarios underground. In the early 1980s, the Missouri University of Science and Technology developed the first collegiate mine rescue team in the United States. For approximately 30 years, it was the only successful collegiate team until the Colorado School of Mines (CSM) started its program in 2009. Currently, there are at least five collegiate teams in the United States and one in Canada. At the Freiberg University of Mining and Technology in Germany, the goal is to adapt the Colorado School of Mines Mine Rescue Program to develop a collegiate team of its own. Currently, mining engineering students cover the theoretical basics of mine rescue in an occupational health and safety lecture and take a basic, one-day mine rescue training course at the Central Mine Rescue Station in Leipzig. The course covers the basic mine rescue topics and gives students the opportunity to experience working in elevated heat and smoke conditions while wearing breathing apparatus. This training gives students a small insight into the importance of mine rescue and mine emergency management. Collegiate mine rescue teaches students the importance of mine rescue and mine safety by giving them hands-on learning experiences before entering the mining industry.

Feb 1, 2014

By C. E. Capes

The spherical agglomeration process provides an attractive method for the cleaning and recovery of fine coals in the form of compact oil-bonded pellets. In treating a washery effluent containing 50% minus 20 micron material by this technique, the slurry was first mixed under vigorous agitation with oil to deash and dewater the fine coal. The flocculated coal pulp was then formed into larger agglomerates on a modified balling disc. The operation of a semi-pilot scale process is described and an analysis of some of the operating and system variables is given. A semi-theoretical expression to predict the final agglomerate size under various conditions is derived and compared with the experimental data. Coal producers are faced with a growing requirement to clean and recover fine mesh coals. Greater mechanization of the extractive and preparation processes has resulted in finer-sized products containing larger quantities of associated foreign matter and preparation plant effluents contain quantities of fine coals which are potentially valuable. These losses will probably increase with the expansion of production and will require the development of effective disposal and utilization processes under pressure of the lack of adequate disposal areas, the enforcement of air and stream pollution laws, and the economic need to obtain the maximum yield of salable product(1)

Jan 1, 1970

By Francesco Chiappalone, Franco Gasperin, Fabrizio Fara

This document describes the challenging task of mining through tiebacks using a 21'-8" diameter Tunnel Boring Machine (TBM) as part of the Ship Canal Water Quality Project. The mining operation involves navigating through 17 tie-backs that are evenly spaced at 8-foot intervals, with many intersecting the full face of the cutterhead. Detailed analysis and review of TBM parameters specific to this area have been conducted to ensure operational efficiency and safety. Hyperbaric interventions have been planned and coordinated, encompassing pre-mining preparations, continuous monitoring and adjustments during the mining process, as well as post-mining measures. The document highlights the complexity and importance of strategic planning and execution to successfully overcome the tie-back intersections during the mining operation.

Jun 23, 2024

Federal Regulations require that coal producers conduct a written, in-house investigation with every lost time injury accident. Besides their obvious value in accident prevention, competently conducted investigations can provide a number of additional benefits to include positive supervisor involvement, the control of rising worker's compensation costs and a measure of protection from civil/criminal proceedings. The paper describes such topics as MSHA minimum requirements, investigator selection and training, accident site procedures, witness interview techniques and the management review process. The reader is also presented with a number of information resources available through MSHA, the National Safety Council and other sources.

Jan 1, 1995

By J. L. Huiatt

Kerosine, fuel oil No. 2, vapor oil, and fuel oil No. 6 were separated into general hydrocarbon fractions by ion exchange chromatography and adsorption chromatography. The collecting properties of these fractions were evaluated by flotation of molybdenum and copper minerals from a natural chalcopyrite ore. Paraffin fractions and aromatic fractions of low polarity produced the best molybdenum recoveries. Selective flotation of molybdenite from copper sulfide minerals was not possible with any of the chromatographic fractions.

Jan 1, 1972

By R. L. Weigel

As Florida phosphate mining gradually moves from the Bone Valley formation to the Hawthorn formation, a greater portion of the minable deposit contains dolomitic diluents which result in lower product grades that can be detrimental to the production of phosphoric acid for fertilizer uses. One beneficiation technique found applicable to the phosphate pebble size range (3 X 16 mesh) is heavy media separation using suspensions of magnetite and ferrosilicon. As part of an ongoing investigation of dolomite removal technology, a pilot heavy media cyclone system was constructed by IMC and used in the testing of a variety of drill core composites and hulk samples. The results of these tests were used to develop a predictive model for heavy media cyclone separation based on pebble fraction assays and heavy media operating parameters. This model is currently being used in the evaluation of specific future mining areas.

Jan 1, 1984

By R. J. Mirville

Flocculation is an important step in the treatment of coal preparation waste waters. The effects of polymer charge and molecular weight and solution pH and ionic strength on the adsorption and flocculation characteristics of a series of polymeric flocculants on some typical waste water constituents have been studied experimentally. The results indicate that the nature and extent of flocculation are strongly system-dependent. For the case of coal, both adsorption and flocculation behavior can be correlated with the polymer conformation in solution. For the mineral constituents, on the other hand, adsorption and flocculation depend also on the surface properties of the solid.

Jan 1, 1979

By Taghi Sharizadeh, MAURICE SUNKPAL, ELAHEH TALEBI, PEDRAM ROGHANCHI

Excessive heat exposure is among the health and safety hazards that have adverse effects on the mine workers. The very nature of the underground climate makes it a convenient avenue for heat generation and accumulation from several heat sources including autocompression, equipment, and heat from strata. This study investigated the effects of clothing insulation and acclimation on the thermal comfort ofmineworkers who are exposed to heat in underground working environments. Several clothing ensembles have been considered to analyze the effect of the thermal resistance of clothing on the thermal comfort of workers. To investigate the impact of the clothing insulation, the thermal comfort limit of an underground miner was calculated in the form of maximum allowable exposure time for an 8-h shift. Parametric analyses were subsequently performed using an already developed thermal comfort model using MATLAB software. The results demonstrate that clothing insulation has a significant effect on the thermal comfort of mine workers. Increase in the clothing insulation decreases the maximum allowable exposure time of mine workers. This is especially true for the new and non-acclimated workers. Since acclimatized workers can tolerate a higher level of the dehydration and are capable of losing more water by sweat per shift, the maximum allowable exposure time for the acclimated workers are higher than non-acclimated workers. These analyses have shown that acclimated workers can have more continuous work per shift compared with non-acclimated workers. For example, in an environmental condition with clothing that a nonacclimated worker cannot work more than 5 h, an acclimated worker can work a full 8-h shift.

Jun 29, 2020

By Naohiro Kurokawa

Isa Limestone Quarry with an annual production capacity of 18 million metric tons is known as the largest limestone deposit in Japan located in the mountainous region about 20 mile northwest of Ube City, Yamaguchi Prefecture, Japan adjacent to Isa Cement Factory to which it belongs, and which constitutes a mainstay of Ube Industries? cement operating division. Isa Cement Factory is equipped with a N.S.P. kiln of capacity of 3 million metric tons per year, which is the largest of its type in the world. Geographically, it is situated in the south- western tip of the Mainland of Japan (Mid City, Yamaguchi Prefecture) and is bordered by the scenic Akiyoshi Karstic Plateau which is world famous for its huge stalactite grotto.

Jan 1, 1982

By William F. Butler

I propose to do three things today. First, take a broad look at the role of mining in the Latin American economy; then, review briefly the current situation in four principal metallic mineral exporting nations -- Chile, Mexico, Peru and Venezuela; and. finally, raise some, policy questions that seem to me to be important. The Role Of Latin America In World Mining First, let's consider Latin America's position in world mining markets. Latin America provides more than 5% of world output in 16 metals or ores, ranging from antimony and barite to Tungsten and Zinc. Latin America supplies a fifth or more of the world's antimony, beryl, bismuth, copper, fluorspar, silver and Tellurium.

Jan 1, 1962

By E. O. Strahl

In the search for economic mineral deposits, the need for efficient mineral or chemical assays is of prime importance. Costly analytical methods and long delays in obtaining assay results severely limit the effectiveness of an exploration program. The assay problem becomes acute once a potential ore body is located and large numbers of samples are generated in close interval drilling programs. In order to avoid the delays and high costs of extensive assays, the exploration geologist or mining engineer is likely to be required to curtail his drilling program, composite samples, or restrict the required analyses to a limited number of critical elements. As a result, the definition of the potential ore body may be less than needed for final economic evaluation. The assay requirements for bauxite exploration usually involve a considerable number of total elemental and empirical analysis. Since the Bayer process for extracting alumina from bauxite involves the selective dissolution and reaction of specific minerals from the bauxite, a direct chemical analysis for elemental composition yields only a portion of the data required to effectively describe the potential economic value of ore body or deposit. To fully characterize the economic value of a bauxite requires digestion, mud separation and mud settling tests under conditions approximating a commercial Bayer plant. A close approximation of the process behavior of a bauxite also can be calculated from a combination of the chemical and mineralogical analyses. By determining the elemental chemistry, mineralogy, and Bayer plant processing characteristics of a few samples of a given bauxite, correlations can be derived that permit defining a bauxite in terms of a given set of process conditions.

Jan 1, 1977

By Katarína Gáborová, Marcela Achimovičová, María Florencia Márquez‑Zavalía, Jaroslav Briančin, Oľga Šestinová, Pavel Škácha

In this paper, the structure, morphology, chemical composition and leaching of naumannite ( Ag2Se) were studied. Mechanical activation of Ag2Se in a planetary ball mill resulted in increasing its specific surface area. The influence of milling time on the particle size was studied by particle size distribution analysis and scanning electron microscopy. The leaching kinetics of non-activated and mechanically activated samples in 3.5–7.9 mol/L HNO3 solutions were examined. Subsequently, the effect of leaching temperature in the range of 25–50°C on the recovery of silver from mechanically activated naumannite was documented. The maximum yield of silver 94% was achieved after 120 min of leaching in 7.9 mol/L HNO3 at 50°C for the sample mechanically activated for 30 min. Based on calculated activation energy values from the Arrhenius equation, a mixed leaching mechanism consisting of diffusion and surface chemical reaction as the rate-controlling steps of the solidliquid reaction was assessed.

Mar 4, 2023