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By Carl Barchet

INTRODUCTION Located on the Colorado River on the Nevada-Arizona border about 56 km (35 miles) southeast of Las Vegas, Nevada, Hoover Dam is a gravity arch dam 221 m (726') high for electric power generation and water supply. The head waters of the dam form a large reservoir, Lake Mead. The dam is equipped with two emergency spillways, one in the Nevada abutment and one in the Arizona abutment. Both spillways which are concrete lined and 15.25 m (50') in diameter, were intended for use only if Lake Mead is full and incoming flow of the Colorado River exceeds the discharge capacity of the turbines and regular bypass conduits. In the spring of 1984, a combination of rain and unusually rapid snow melt required the opening of the spillways for only the second time in the 50 year history of the dam. As in the previous use in 1942, the massive discharge of water through the tunnels resulted in severe damage to the concrete Linings of both tunnels. This damage is the result of cavitation which occurs as the discharge water flows at very high velocities over minor irregularities in the concrete lining. The U.S. Bureau of Reclamation has long been aware of the cavitation effect which occurs during these high volume discharges and has been studying solutions. One solution to the problem is to induce air bubbles into the flowing water to eliminate the vacuum associated with cavitation. This solution had been implemented at Yellowtail, Flaming Gorge, Blue Mesa, and Glen Canyon dams by constructing an aeration slot in the inclined portion of their spillway tunnels. Since the spillways of Hoover Dam were already in need of repair, the BUREC decided to construct similar facilities in each of the two 15.25 m (50') diameter spillways coincidental with the other repairs required.

Jan 1, 1987

By Roger L. Baer

Introduction Brief Review -SEC mission & history -Development of SEC mining disclosure guidelines -Principles of good public company ‘disclosure’ SEC staff views of alternative approaches to mining company disclosure -SME Resource & Reserve Committee – April 2003 Food for thought

Jan 1, 2003

By Douglas J. Kramm

This paper discusses the history and development of the Rotary Kiln in improved fuel economy. It discusses latest technology to optimize fuel economy in a long Rotary Kiln. It discusses the limestone preheater, the SF process for cement manufacture, and the flash calciner with suspension preheat and. suspension deheat for fine limestone.

Jan 1, 1977

By R. W. Waytulonis

New exhaust control techniques and devices may be necessary to meet future diesel particulate matter emission standards in underground coal mines. This paper reviews conventional work practices and devices used to control diesel exhaust emissions, and new techniques being tested by the US Bureau of Mines. Discussions will center on important work practices and on the function and efficiency of exhaust aftertreatment devices. An industry-government cooperative research project to develop and test an exhaust aftertreatment system for part 36 equipment is also discussed.

Jan 1, 1992

By C. Bazin, B. Girard

The application of time series analysis techniques to plant data provides a method for examining and modeling the behavior of operators during the operation of furnaces for the reduction of ilmenite concentrate. The obtained model is used to assess the consistency of actions carried out by the operators and to review and improve the training procedures.

Jan 1, 1996

By Gabriel Babut, Ion Matei, Roland Moraru

Several controlled recirculation systems are in operation wor1dwide. As an unconventional technique of ventilation the implementation of such a system requires particular safety conditions and a well-founded set of feasibility factors and parameters. On the other hand, many mines in Romania are facing problemms in meeting the growing ventilation demands, so that controlled air recirculation could give an answer. The present paper presents the results of the work in this field, based on a detailed theoretical approach. Parameters wich must to be taken into account were identified and analysed, numerical simulation are carried out and an experimental test-scale model is presented.

Jan 1, 1997

By G. Righettini, P. Mousset-Jones

Diesel powered vehicles have made underground mines more efficient, but with the advent of DPM regulations, in most cases, extra ventilation and/or engine emissions control technology will be required. Using fuel cell powered vehicles will not need these measures to be taken. Nine US underground mines of varying production rates and mining methods were studied to determine possible ventilation reductions if their diesel fleets were replaced with identical fuel cell powered vehicles. Factors that might limit ventilation reductions, such as heat and the effects on other pollutants were determined for each mine. The ventilation cost savings and other benefits of fuel cell vehicles show that when they become commercially available they have the potential of being viable alternatives to diesel vehicles.

Jan 1, 2004

By S. K. Singh, J. Shepherd

Feather-edging, a major source of injury and fatal accidents in Australia, South Africa and the United States, refers to a phenomenon in which the roof at the goaf edge falls, often suddenly, as a thin wafer of rock that overrides conventional timber breaker lines. The fall may adversely affect a working bord at a distance of 15 m (50ft) or more from the goaf edge. Feather-edging typically occurs in relatively massive, strong roof strata such as sandstone or conglomerate. This paper presents the results of a test in which a concentrated row of fully grouted bolts were used to prevent feather-edging in an Australian pillar- ("total-") extraction coal mine. The test demonstrated that the bolts could resist feather-edging.

Jan 1, 2000

By S. I. Nozhko, V. N. Guliy, A. A. Zolotarev, L. M. Luyshnia

The study of the apatite deposits of the Aldan Shield shows wide spread of the Precambrian apatite-carbonate ores and possibilities of using them for extraction of apatite. Dependency of flotation on ore minerals was studied according to the following scheme: preparation of the monomineralic samples of anhydrite, gypsum, chlorite, serpentine, phlogopite, apatite; mixing them in apatite ore of the average composition; followed by flotation. Another series of the experiments was conducted to ascertain a dependence of flotation activity of the different minerals on the different flotation reagents, which were used as collectors. It has been shown that apatite from silicate-carbonate ores is most extractable because it has the biggest size of grains and is the most free of inclusions. Beneficiation of the sulphate-containing apatite-carbonate rocks is possible when flotol - 7.9 is used as a collector. Meanwhile, the use of the tallaktam leads to an increase in the sulphate recovery. The estimation of individual technological features of the layered Mghydrosilicates and their influence on the process of beneficiation has been examined using samples of apatite-dolomite ore (P205-8%) with the addition of the phlogopite, serpentine and chlorite. The results show that there is little influence of the chlorite presence on the flotation while the serpentine presence leads to a decrease of the flotation, because of its high specific surface area.

Jan 1, 1993

By J. Muir

This report focuses on minimum ore block sizes that are economically feasible to mine with the vertical crater retreat (VCR) method. In 1985, Homestake Mining Co. began a program to bring several small block VCR stopes on line. This report examines these experimental stopes, including design parameters, ground control, drill patterns, secondary blasting, and mucking. Cost and scheduling comparisons are made with mechanized cut-and-fill and open cut- and-fill methods.

Jan 1, 1987

By S. D. Morrison, J. L. Watson

It is well known that the density and viscosity of a mill pulp have optimum levels for grinding efficiency, and sophisticated control loops are employed to control pulp density in industry. However, these control loops rely on a number of plant measurements, and often the input data will not permit effective determination and control of the mill pulp density. The use of a single remote pulp density measurement has obvious advantages, and it is suggested and demonstrated for laboratory batch grinding that mill noise measurements can indicate the effective density of the mill pulp. In addition, the mill noise is shown to indicate the actual effective pulp viscosity in the mill and hence permit the identification of the dynamic rheological regime existing in the mill. It is demonstrated that mill noise increases with grind time and, at any given grind time, with increasing pulp density in the pseudoplastic range. This increase in mill noise level with pulp density is interpreted as indicating a decreasing pulp viscosity. The results show that the transition from dilatant to pseudoplastic conditions within the mill, with increasing pulp density, can be identified by this increase in mill noise. When the pseudoplastic pulp started to exhibit yield characteris- tics, the mill noise fell dramatically. The technique of mill noise analysis is then used to investigate the effect of a grinding additive on the batch grinding of two ores. With a magnetite ore, the additive was shown to increase the mill noise, and hence decrease the pulp viscosity, in the pseudoplastic region and to increase the effective grinding. The molybdenite ore, however, did not show significant noise level changes and did not show improved grinding efficiency.

Jan 1, 1987

By E. G. Kelly, D. E. Walsh

The behavior of gold particles on a spiral was studied using radioactive gold tracers. The method allowed the effects of particle size, particle shape, pulp density, feed rate and splitter settings to be studied. Although the method has been successfully applied to other gravity concentrators, it was found that reliable results were more difficult to obtain on the spiral. However, these preliminary results show that, with suitable precautions, the technique is capable of providing valuable information, unobtainable from conventional studies, that could be used to better optimize spiral performance.

Jan 1, 1993

By W. J. Pennstrom, J. R. Arnold

This paper focuses on solution-balance management around heap-leach operations. Experience has shown that increased leach recoveries can be achieved by utilizing various leach-solution recirculation techniques. The most prominent solution-recirculation technique is intermediate leaching. The net effect of intermediate leaching is to increase recovery plant performance by increasing solution concentration tenors, to increase metal recovery by increasing the total leach time and to decrease the overall capital expenditures required for metal-recovery facilities. The adverse effect on the flow of cash from increased metal inventories in the recirculating solutions is offset by increased metal recovery and lower operating costs per unit produced.

Jan 1, 2000

By R. Kanniganti, M. Karmis, C. Haycocks

An extensive review of multi-seam under-mining literature was conducted and a data base of case studies was assembled . A critical review of the design principles outlined in this literature resulted in the compilation of specific design criteria for the design of lower seam mines. Analysis of this criteria demonstrated the necessity for a protocol for the design of unsymmetrically loaded pillars. Such a design criteria was developed using finite element methods for a wide range of possible loading conditions. This design criteria can be utilized for underlying pillar design when the loading conditions can be determined. To facilitate using all the under-mining research results by field/planning engineers a Windows TM based software package was developed. This software package contains a multi-seam tutorial, analytical tools and a case history database. The package is user friendly and fully interactive and supported with extensive on-line help. The package contains numerous case studies of multi-seam mines that can be reviewed to facilitate analyses.

Jan 1, 1996

By H. Sevim

In long-term open pit production planning, a series of nested and maximum-value pits is usually generated first. These pits are then considered as possible pushbacks over a number of planning periods. To determine the best pushback in each planning period, the pits are evaluated for their technical and economical feasibilities under certain production constraints. Parameterization is a commonly used technique to generate a series of pits. In almost all cases, however, some of the consecutive pits generated by this technique are too far apart from each other. This is called the "gap" problem. It may make the entire pit series useless for production planning purposes. A new pit gener¬ating algorithm has been developed to overcome the gap problem. Through this algorithm, a series of nested maxi¬mum-value pits can be generated with a controllable size increment. The logic of the algorithm is illustrated through a small hypothetical case. Its capability of generating maximum-value pits that are as optimal as those generated by parameterization and its advantages over parameteriza¬tion are presented through an actual gold deposit case.

Jan 1, 1996

By James C. Puckett

The mining industry finds itself in the middle, between the need to increase production of our energy resources and the necessity of minimizing the environmental impact. Using the recent past as a guide, the mine planning engineer's function will continue to increase as further coal quality constraints are made upon the production staff. The engineer will need to make use of all available tools in order to provide timely answers to the complex "what if" questions that arise. This need to consider many alternatives is bringing about a rapidly increasing acceptance and utilization of the computer. In the areas of data handling, mineralization modeling, and production simulation, the computer is an effective tool for the mine planning engineer. Described herein is a coal data storage and analysis system developed to provide timely answers to the "what if" questions for an operating strip coal mine in Montana. The characteristics of a computerized coal data base and coal quality planning system are outlined in this chapter. The system has been developed for use at a particular coal mine; however, it has applicability to coal mines in general. Fig. 1 is a flow chart showing the functional relationships of the system. There are three main file types: the drill-hole data base, the boundary file, and the zone file. The purposes for which each file is organized are illustrated on the flow chart.

Jan 1, 1979

By L. Boyd, T. Martin, V. Gall

Water infiltration into subgrade infrastructure can cause major impacts on their performance. In addition to damaging the structure, water intrusion leads to deterioration of installations including electrical and mechanical components and in patron discomfort. To remedy these impacts, leak remediation is often carried out to halt water infiltration. Remediation methods include coatings, drainage, injection/stitch grouting, curtain (backside) grouting, and/or internal umbrella systems. Selection of the rehabilitation method depends on the structure’s use, owners’ priorities, its installations, structural conditions, surrounding ground, and hydrogeologic conditions. Since many factors influence the rehabilitation method chosen, a novel holistic approach is undertaken to understand leakage causes and consequences to develop the most appropriate, efficient, and reliable solution to extend the structure’s life. A reconnaissance phase combines geologic, hydrogeologic, and as-built information with detailed digital scans and visual observations to develop a database of existing conditions. This database, called a tunnelband, is used to develop the rehabilitation solution and made part of the contract documents, allowing for an informed bid by specialty contractors. Tunnelband and the preferred rehabilitation system are portrayed in contract documents, which are procured in various contract types depending on the owner’s preference and project characteristics. The pool of contractors are required to submit their understanding of this holistic approach by developing and supplying the owner with a detailed workplan. The completed rehabilitation is portrayed in detailed as-built drawings which also provide the owner with an operation and maintenance manual outlining for periodic observation of the structure and checking of its performance. Ultimately, this information is implemented into a “BIM Digital Twin” that is used by the operations and maintenance staff for long-term observations. This proposed novel framework for leak rehabilitation is currently being used successfully in a number of projects throughout the United States.

Jun 13, 2023

Bauxite mine rehabilitation is an important stage of today’s bauxite mining activities. To get an overall picture on those activities the International Aluminum Institute (IAI) has been carrying out Bauxite Mine Rehabilitation Surveys since 1991. The most recent survey from 2003 covers 70% of the world’s bauxite production and 23 corresponding companies from 12 countries. The survey activities show that nearly all operations refer to a sophisticated environmental management strategy. By setting up a review scheme based on the principles of the Global Reporting Initiative the compliance of this survey to aspects of Sustainable Development has been reviewed. The Clarification of a multitude of aspects based on the GRI guidelines helped to structure recommendations and relate them to the survey as such but also to the different stakeholders involved.

Jan 1, 2005

By Malcolm J. McPherson

Within the world of mining health and safety, increasing attention is again being given to underground fires and explosions. This paper reviews the effects of open fires in mine entries on the ventilation system, and outlines current methodologies of attempting to control such a fire. The particular hazards of a fuel-rich fire are discussed. There appear to have been no really significant advances made in methods of extinguishing mine entry fires in the last several decades. The final section of the paper introduces research that is investigating the simultaneous production of an inerting, cooling and quenching atmosphere by means of a dense water fog.

Jan 1, 1993

By Wilhelm J. Kogelmann

The quest for U.S. energy independence will result in a major increase in underground mining operations. It will necessitate the rapid excavation of development drifts, entries and slopes to exploit underground deposits of energy resources such as coal, uranium and oil shale. Most of this development work will be done in soft and medium hard rock up to an unconfined compressive strength of approximately 20, 000 psi. OBSTACLES TO RAPID TUNNEL EXCAVATION Labor In the U. S. coal mining industry, the underground productivity in tons per man-day declined from 15. 61 in 1969 to 11. 00 in 1973 which is a startling 30% decline. While productivity declines, the cost of labor and supplies continues to rise. Ralph E. Bailey of Consolidation Coal Company recently stated four reasons for the decline of productivity: A shortage of experienced miners, enactment of the Federal Coal Mine Health and Safety Act effective April 1970, major changes in union work rules in 1968, and a deterioration in the attitude of the work force (1). Because there is already a great shortage of skilled miners, the situation will get worse when large new mines for oil shale, coal and uranium open in sparsely populated areas in the Western United States. Only the large scale use of easy to operate tunneling machines can increase productivity and lower the cost of excavation.

Jan 1, 1974