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By Robert J. Storms, David J. Malone, Thomas E. Crandall

Corrosion and abrasion have been present in hydrometallurgical processes for many years. Ceramic lining materials have been used in several applications to protect process vessels from the corrosive and abrasive effects of a wide range of ore slurry processes. This paper reviews the history of ceramic lining systems utilized in hydrometallurgical vessels, the commercial benefits associated with their use, and additional areas of opportunity for the Mining Industry.

Jan 1, 1995

By S. Bhattacharjee, S. K. Singh, R. K. Galgali

A method for the preparation of zirconia- toughened mullite using dc plasma is presented. An indigenously developed 50-kW thermal plasma reactor is used for the preparation of zirconia-toughened mullite using a dissociated zircon and alumina mixture. Both XRD and SEM studies of the product confirmed the formation of mullite and zirconia. The zirconia grew as equiaxed grains of uniform size (~5 µm) in a mullite matrix.

Jan 1, 2002

By D. J. Barratt

The specification of the prime mover of an autogenous-semiautogenous mill involves an analysis of the likely operating conditions within the mill and the choice of a nominal operating speed. For variable speed mills, the operating range for mill speed has to be defined so that mils power-torque requirement can be matched by the motor power-torque capability. This paper describes how thin relationship can be influenced by ore grindability.

Jan 1, 1995

By Robert H. Shannon

Coal is the primary fuel for U.S. electric per generation -- over 78% of U.S coal production. In 1987 over 56% of electric per generation was from coal-fired plants. Areas of concern confronting the expanded use of coal for per generation include environmental, political and the nation's energy security and economy. These matters and available alternatives and options directed to the expanded use of coal are reviewed.

Jan 1, 1989

By Maurice Deul

Certain health and safety hazards occur entirely unexpectedly in some subterranean excavations. Although ground support is not the subject of this paper, ground failure can result in large and often uncontrolled flow of fluids into an excavation. Even when there is no ground failure, the disturbance of nature's equilibrium between rock or unconsolidated alluvium or rubble and the contained fluids poses severe problems to a well planned operation. Optimum conditions for safe operation cannot be the sole criterion for site selection. Some mineral deposits form in zones of structural weakness, others form where hydrothermal alteration substantially weakens the enclosing rock, and tabular deposits such as coal and evaporites inevitably undermine large areas. Excavation to acquire mineral values cannot be relocated. The same is often true for tunnels driven to connect distant points by the most direct route. Rivers and mountains cannot he avoided, and the cost of lengthening a tunnel--by even a fraction of a percent--must be strongly justified. No responsible engineer will knowingly select a dangerous route for excavation, but to what extent do engineers attempt to assess the health and safety hazards that may be reasonably expected? How, specifically, can methane explosions, water and sand flooding, dangerous dusts, toxic gases, thermal shock and radar poisoning be eliminated or minimized through systematic advance planning?

Jan 1, 1974

By F. J. Klingler, K. M. Swaffar, M. M. Rabbaig

The Detroit Water and Sewerage Department has undertaken a $1.2 billion effort to capture and treat combined sewage overflows from various outfalls along the Detroit and Rouge Rivers in Detroit, Michigan. This program is planned to include a 455,000 m3 (120 million gallon) storage and treatment tunnel which will capture overflows from 19 outfalls along the Rouge River. The tunnel is currently in the conceptual design phase, with the bid date planned for mid-year in 2001,and completion planned for August 2005. The total design and construction cost is currently estimated to be approximately $450 million. Current concepts are for the storage and transport tunnel will be 6.1 m (20feet) in finished diameter, with a total alignment length of approximately 12,200 m(40,000 feet). The main tunnel will extend through the Traverse and Antrim Shalerock formations, while approximately 5,500 m (18,000 feet) of various diameter connecting tunnel will extend through both rock and soft ground. The project will include a total of 10 drop shafts, 13 riser shafts, various connecting structures, and a 455,000 m3/day (20 mgd) pumping station. This paper will present a discussion of the design philosophy, subsurface conditions, the various planned components, and the expected design and construction considerations for the proposed Upper Rouge Combined Sewage Overflow Tunnel.

Jan 1, 1999

By James Sheridan

Risk can generally be defined as the possibility or chance of a loss corresponding to uncertainty. Analysis is the process for examining the components and relationships of a complex system in order to determine the impacts of its variables. Risk analysis is therefore a course of action taken to analyze multiple variables of a system that is subject to speculative outcome. When risk analysis is applied to mine development, it becomes the means for assessing and measuring those parameters that contribute to economic viability. Mining can be a risky business. It is composed of an assortment of factors that contribute to its financial outcome. Of these factors, the most consequential output is the net present value (NPV). Applying risk analysis in mine development can identify those factors having the most significant impacts and applying limits to those impacts. Mathematical computer modeling using Monte Carlo techniques is available and can be customized to suit specific mine development ventures. Essentially, those parameters that are not fixed values can have input variability. Rationally deduced engineering estimates should be the basis for determining the initial values applied as inputs in the models. Risk analysis therefore provides the user a means to identify, rationalize and assess the risks in mine development in an informed, calculated, and unbiased format for making economic decisions.

Jan 1, 2002

By Donald G. Dahle

Project Payette is a conceptual nuclear experiment under the Vela Uniform program intended to further evaluate the mechanism of seismic decoupling. Vela Uniform is a Department of Defense program to improve this country's capability to detect, locate and identify underground nuclear detonations. This program evolved from recommendations of the Panel on Seismic Improve¬ment, (Berkner Panel), an officially appointed group of noted U. S. scientists. This Panel, taking note of difficulties in detecting the differences between some underground nuclear detonations and some earthquakes recommended a program of increased basic research in seismology. The theory of decoupling, Which involves possible reducing of seismic motion resulting from underground explosions by reducing the coupling or physical linkage between the explosion and the geologic environment, was investigated by Dr. Albert latter and his associates at RAND during the late 1950's. The concept has been further investigated theoretically by scientists of the Lawrence Radiation Laboratory and the Sandia Laboratory. The theory has been tested experimentally under Vela Uniform Projects Cowboy, Dribble and Sterling. The Salmon Event of Project Dribble was a tamped (with the explosive in firm contact with the geologic formation) nuclear detonation 2700 feet below ground in the Tatum Salt Dome. Project Payette, if found to be feasible and if authorized for actual execution, would become a decoupled experiment in the same environment.

Jan 1, 1968

By Y. C. Kim

For the past quarter of century, much more effort and research have been expended in developing the "optimum" ultimate pit limit design algorithms and much less to solving the "optimum" open pit production sequencing. However, the potential economic benefit to an operating mine is far greater for the latter than the former. Unfortunately, the problem of "optimum" open-pit production sequencing has not been fully solved to date. This paper first reviews the past and currently used methodologies for developing this sequence. The staggered pit phase geometry problem of advanced stripping and operational constraints such as ore and waste tonnage requirements by period and necessary contiguity of mining faces are the main reasons why the "optimum" production sequencing problem has not been solved as yet. This paper also explains why any method which attempts to simplify the problem using ultimate pit limit design algorithm will fail to reach an "optimum" solution.

Jan 1, 1994

The response of 174 domestic water supplies to longwall mining of the Pittsburgh coal seam was compared to various physical parameters. Sixty-four percent of domestic water supplies returned to service without the need for intervention, while thirty six percent required intervention to reestablish a suitable water supply. Domestic well response is strongly correlated with the topographic setting. Valley wells showed the least effect while hilltop wells showed the greatest effect. Well response was also found to be correlated to the location of the well above the mining with greater effects observed in zones of surface tension and compression, and fewer effects in zones which are stress neutral. Ground water supplies remained unaffected or were re¬established at 149 of 150 sites, indicating that ground water resources remain available to domestic wells after mining. Results of this study support the stress-relief model of ground water flow in the Northern Appalachian Basin. Longwall mining's effect on this system is to locally increase fracture connectivity in the near surface zone. This may shift the zones of saturated fractures to greater depths beneath hilltops and hillsides, and increase recharge and storage in valleys. General trends in well response are predict¬able utilizing the stress relief conceptual model, the topographic setting of the water sources, and their location over the mine.

Jan 1, 1986

By A. Pincomb

After determining minable acreage, tons are calculated by multiplying minable acreage by average thickness and by a volume-tonnage conversion factor. Converting from tons in the ground to tons sold across the scale takes fines and internally used and wasted stone into consideration, resulting in minimum losses of about 10% for limestone and 15% for sand and gravel. A high degree of certainty about thickness, lateral continuity and geologic character defines proven reserves. Assuming continuity of these characteristics defines probable reserves. By using tpa estimations and annual tonnage requirements, the life of a deposit can be quantified. The decision can then be made regarding the necessity of securing more acreage. Some landowners choose to multiply aggregate price, operating income, or a royalty rate by tons to arrive at a value for their reserves. In doing so they probably overstate the value of their land.

Jan 1, 2003

By Robert C. White, Kurt W. Keskimaki

The Henderson Mine is a large underground panel cave molybdenum mine located near Empire, Colorado. Diesel equipment is employed for all development work, as well as production ore handling. Due to fluctuating demand for molybdenum, production rates have varied from 16,000 to 32,000 metric tons per day (18,000 to 36,000 short tons per day) over the last four years. In order to obtain the maximum air flow for minimum power cost the Henderson mine has completed the following modifications to the ventilation system: removal of large intake fans, elimination of underground booster fans, shutdown of tunnel exhaust fans, completion of the number 5 exhaust ventilation shaft, and use of partially debladed main exhaust fans. These changes have reduced the annual cost of mine ventilation at the Henderson Mine by over 80 per cent, a very critical cost savings in today's competitive molybdenum marketplace.

Jan 1, 1989

By E. Valdiviezo, J. F. Oliveira

Adsorption of residual flotation reagents onto equilibrium fluid cracking catalysts is a promising method of purification of flotation process water. In the present paper, adsorption of sodium dodecyl sulphate (SDS), dodecyl ammonium chloride (DAC) and sodium oleate onto a spent catalyst from petroleum industry was studied by analysing the residual concentration of the surfactant after contact with the zeolite catalyst. The adsorption of the DAC was rather low but SDS and sodium oleate presented a high affinity for the catalyst surface. The loading capacity was 4.2 kg/ton for SDS and 5.5 kg/ton for oleic acid. After the treatment of the loaded catalyst with a HCI 1 N solution these surfactants are desorbed and the catalyst may thus be regenerated. This would be an additional advantage to its low cost, not to mention its condition as a discarded product and its availability in large tonnages.

Jan 1, 1995

By H. L. Ford

Flocculant testing should be initiated for economic or performance reasons. When the decision has been made to test, the laboratory can provide valuable information concerning the various products under consideration. Properly conducted laboratory tests can determine: 1. If two flocculants are needed to achieve clarity or density. 2. Ease of mixing. 3. How quickly the material goes into solution. 4. Stability of prepared f locculant solution. 5. Stability of the floc formed. 6. Amount of mixing required for proper floe formation. 7. Optimum flocculant concentration. 8. Optimum pulp density. 9. Approximate location of the point of addition. 10. Single or multiple addition points. When a flocculant shows promise in the laboratory, a plant test should be scheduled. During the plant trial, arrange for normal conditions and start testing with a crew that is most familiar with the unit operation where the flocculant will be applied.

Jan 1, 1986

By Kai Nielsen

In underground mining coarse muck and large boulders lead to ineffective utilization of costly mining equipment, and extra expenses and delays caused by secondary blasting. Cost analysis in some Norwegian mines shows that these extra expenses may amount to 10% or more of total mine operating costs. A computer model has been developed for sensitivity analysis of underground longhole stope blasting. The basic idea of the model is : When increasing the blasting energy input and fragmentation costs, the fragmentation will be better. This will lead to cost savings for loading, hauling, secondary blasting and primary crushing. The blasting design giving the lowest overall costs will indicate the optimal practice. The model has been used with data from several underground operations in Norway. An example run with typical costs shows that the costs for drilling, blasting and secondary blasting are the most significant parameters in the optimization process.

Jan 1, 1986

By W. R. Dearman, N. Turk

A seismic fissuration index (K) is defined as the ratio of the difference in the P and S wave velocities obtained when a dry rock specimen is tested both under a load equal to half the uniaxial compressive strength of the rock (Vo) and without an applied load (Vd) to the velocity obtained without an applied load (Vd), as K = (Vo - Vd)/Vd. A similar seismic fissuration index is also proposed for classifying the dry rock mass in terms of field seismic velocities. The field equation is extended by including the intact rock seismic velocities. K is found to be related to the porosity of rocks. The proposed equation can equally be used for characterizing saturated rocks, using S-wave velocities. However, the time average equation should be used for characterizing saturated rocks, using P-wave velocities, even though this equation gives upperbound estimates of the rock material and fracture porosities.

Jan 1, 1986

By Kenneth Maser, Douglas W. Ounanian, Joseph S. Boyce

Foster-Miller Associates, Inc. (FMA), under contract to the Department of Transportation (DOT) and the Urban Mass Transit Administration (UMTA), is currently developing an Extruded Tunnel Lining System (ETLS). The ETLS would reduce ground support costs in machine bored tunneling by eliminating the need for temporary support, and by slip-forming the final concrete lining directly behind the Tunnel Boring Machine (TBM). The system can advance at variable rates, from 0.6 to 3.7 m (2 to 12 ft) per hr, by combining three systems: a very high early strength concrete, continuously produced and delivered by a concrete process system; a slipform/bulkhead system for supporting the concrete prior to strength gain and exposure; and a control system for form/bulkhead alignment and concrete process control. Large-scale tests are planned to demonstrate the system in a 3 m (10-ft) diameter steel "tunnel".

Jan 1, 1981

By C. A. Rowland

Introduction Comminution efficiency, as measured by relating circuit performance to the consumption of energy and the time and money required, can be determined by the following comparisons: Theoretical efficiency: The theoretical efficiency is the actual energy consumed in a comminution machine compared to the theoretical energy required to perform the size reduction. Operating efficiency: The operating efficiency compares the operating work index of a comminution machine to the Bond work index of the ore, as determined from bench-scale crushing and grindability tests or pilot-plant tests. Economic efficiency: The economic efficiency is comparing income from production to predicted income. Key words: Comminution, Bond work index, Grinding, Crushing, Ball mills, Rod Mills. Theoretical efficiency In their book Process Engineering of Size Reduction - Ball Milling, Austin, Klimpel and Luckie (1984) stated that, "We have tried throughout this book to avoid the use of the term grinding efficiency because the degree of conversion of energy to useful size reduction is an ill-defined concept. In addition, the only efficiency, which is of real interest, is the meeting of product specifications at the minimum cost." The National Materials Advisory Board, National Re¬search Council (1981), in the abstract of a report titled "Comminution and Energy Consumption" stated that, "Up to 99% of the energy consumed in grinding these ores may be expended in the movement of machinery, with noise and heat the undesirable byproducts, thus leaving only 1% of the energy available for size reduction. Coupled with this is evidence that many of today's crushing and grinding techniques not only are antiquated but have little or no scientific base of understanding." Throughout the past 50-plus years, grinding efficiency has been referred to as being from 1 % to 10%. The measurable basis for these observations is difficult to establish, but they appear to be based on production performance compared to theoretical energy requirements for the work done. The theoretical energy requirements were determined from the energy required to break a single particle or a thin layer of monosized particles by compression or by a single impact from an impact-testing device. King, Tavaras and Middlemiss (1997), in a paper titled "Establishing the energy efficiency of a ball mill" described such a test. These batch single-breakage tests generally do not duplicate the continuous-breakage process in the comminution machinery used in ore concentrators. Operating efficiency The currently available crushers and grinding mills are fed at a controlled continuous flow rate, and they impart the breakage pattern needed to produce the desired size reduc¬tion. While theoretically inefficient, they are the most practical comminution machines available. The operation of this machinery is relatively simple and can be controlled with available control systems. The essential factors in determining the operating efficiency of comminution machines are energy, as consumed in the machinery, and the required energy, as determined from test work. Bond work indices, obtained from bench-scale or pilot-plant crushability and grindability tests are used in the following Bond equation (Bond, 1960) to determine the energy required to produce the required size reduction

Jan 1, 1999

By Jess H. Albino, Girish Roy, James M. Monsees

Construction of the North Hollywood line of the Los Angeles Metro System required crossing the Hollywood Fault as the twin transit tunnels extend into the San Fernando Valley. The Hollywood Fault is considered active and represents the largest active fault that the North Hollywood Redline extension will cross. The feature is a thrust fault with the north plate overriding the southern plate and creating the Santa Monica Mountains in the process. South of the fault lies the alluvial valley and Hollywood. North of the fault are the Santa Monica Mountains which rise locally to more than 1200 feet. The average overburden at the seismic section is about 300feet and is overlain by Runyon Canyon Park, a municipal park with environmentally sensitive areas. The actual fault plane was anticipated to lie within the southernmost120 feet of the 600 to 700-foot-wide fault zone. The special seismic section constructed for the tunnels consisted of an enlarged cross-section with special lining, drainage and finish features that will facilitate the restoration of metro service in case of a major event occurring on the Hollywood Fault. The discussion will address the geology, the procedure used to define the design event and predicted displacements, the unique design features as well as the construction methods used and the instrumentation and the results obtained.

Jan 1, 1999

By G. J. Jansen

Introduction The usefulness of microscopes in exploration and ore dressing, problems has been documented for the older generation of mining industry personnel in such publications as Schneiderhohn and Ramdohr (1931). A more recent publication that examines the subject is Process Mineralogy, a conference proceedings of The Metallurgical Society (TMS, 1981). However, it is worthwhile to review some of the principles and advantages of microscopic examination of rocks, ores, and mill products. Transmitted light Microscopists can look at materials in transmitted or reflected light. Studying transmitted light is what is usually meant by petrography. In this method, the light passes through the specimen. The upper polarizing filter can be moved in (crossed nicols) or out (open nicols) of the light path. The specimen can be a thin section, a slice of rock mounted on a glass slide and ground to 30 µm (>400 mesh). Or, it can be a sample of rock or ore crushed to about 70 µm (200 mesh). Transmitted light study is particularly suited to gangue minerals, such as quartz, carbonates, and feldspars, and to the study of alteration processes and products. It has some applications to liberation studies. Minerals are identified in transmitted light by observable and measurable optical parameters, such as cleavage and twinning. Figure 1 is a photomicrograph of the mineral microcline, (original

Jan 8, 1985