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By Zoltan F. Oszter

Feeding bulk solids from bins or bunkers sometimes poses a problem to the materials handling engineer. The paper describes, by practical examples, how material flow can be improved on existing installations, and how difficult-to-handle materials can be successfully drawn from storage and fed to fully automated process systems. The examples illustrated are based on actual experience with projects designed for the mining and metallurgical industry. Maintenance costs, where available, are also indicated.

Jan 1, 1966

By S. V. Tracy

The Outokumpu Skim-Air Flash Flotation machine was developed to separate valuable mineral from gangue as early as practical by floating it with specially designed flotation equipment installed in the grinding circuit. Machines already in service have shown the ability to produce final grade concentrate with an increase in overall recovery and flotation rate while decreasing filter cake moisture and reducing fluctuating feed grades to conventional flotation circuits. The first US production test was carried out in a southwestern copper concentrator with successful results. This report describes the results of the test along with an explanation of the process and the benefits obtainable.

Jan 1, 1986

By Andrew P. Gize

A petrographic approach to studying the organic matter in ore deposits is advantageous in that direct observation of sample heterogeneity can be made, organic constituents (macerals) can be identified, and valuable information about the geological history of the sample (such as thermal history, oxidation, and reworking) can be obtained. Thermally immature bitumens are compositionally and structurally heterogeneous, and optically isotropic. The end product of thermal alteration, graphite, is compositionally and structurally homogeneous, and optically an isotropic. One route by which thermally immature bitumens can approach the graphite structure Is by an aromatic intermediate phase, termed mesophase. The development of optical anisotropy and a thermal mesophase has been observed In several high temperature deposits. Textures in bitumens are described from the thermally-altered Mississippi Valley-Type deposit at Nanisivik (Northwest Territories), the silver-vein deposit at Kongsberg (Norway), and the gold deposit at Carlin (Nevada). Textural evidence for multiple generations of bitumens, supportive of a pulsing model for incoming brines, is shown. Petrological evidence for the introduction of bitumens as an immiscible phase or possibly as micelles is shown in the Carlin and Kongsberg deposits.

Jan 1, 2013

By T. W. H. Parker, S. B. Sadleir

ABSTRACT A comprehensive program of air flush core and reverse circulation drilling, trial mining and beneficiation test work was carried out in 1980-1982 to re-assess the potential of the Mitchell Plateau bauxite deposit. The results generally confirm previous work by Amax Corporation. The bauxite is a medium available alumina and reactive silica deposit which responds well to wet screen beneficiation. High grade pockets have developed locally, with the potential for refractory grade extraction. A major feasibility study of the Mitchell Plateau bauxite deposit was completed in 1983. Due to the unexpected severity of the downturn in the alumina market, development of the project has been deferred.

Jan 1, 1984

By Douglas Castleberry

The degree of fragmentation obtained in primary quarry blasting has always been a factor in the speed of digging' the muckpile This paper will discuss a case history of increased production and associated lowered costs from increased fragmentation. The quarry under discussion is fairly new, located in Georgia, and is in the large operation .category. Loading is done by three yard shovels, and, primary crushing by a 48" x 60" haw crusher preceded by a 5' wide feeder. The stone is a hard granite gneiss, of Los Angeles rating 22, and apparent specific gravity is 2.68. The product is shipped to points in that state for railroad ballast, concrete aggregate, and road building stone. Inasmuch as fairly large shovels and a large Jaw were to be utilized, initial drilling and blasting were pointed toward producing fairly large sized muck for this large equipment. This was following a concept somewhat in vogue for some years in the Southeast wherein many large equipment plants would tend towards larger fragmentation, and smaller equipped plants would conversely tend toward attempts at smaller sized rock piles for smaller shovels and crushers.

Jan 1, 1960

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

10.1 I~RODUC1'ION In order to understand the effects of surface subsidence due to underground mining on the ground water hydrology, a brief introduction to the rate, direction, and general pattern of ground water movement in aquifers is necessary. Ground water movement in an aquifer is controlled by aquifer lithology, structure, permeability, water levels, topographic set¬ting, and pumping patterns (Sgambat et al., 1980). Fig. 10.1 shows an idealized flow pattern of ground water in a hilly terrain (Coe and Stowe, 1984). The hill is made up of a series of interbedded permeable aquifers (mostly sandstone) and confining units (mostly shale). Since sandstone is porous and permeable, ground water moves through it downward and laterally until it reaches the interbeddings of the confining unit immediately below. The ground water then moves laterally along the interbeddings, be¬cause the confining unit is less permeable, and comes out as springs on the surface at the intersection of the aquifer and the confining unit. If there is a ground water table in each aquifer, it is a perched water table (e.g., right side of Fig 10.1). On the other hand, if the ground water recharge is larger than can be drained out, the interbedded permeable aquifers and confining units will be filled with water and a ground water table will exist only at the uppermost permeable aquifer. This is the semi-perched water table (e.g., left side of Fig. 10.1). There are three ground water flow systems: shallow, interme¬diate, and deep. Shallow flow systems occur near the land surface and the surface drainage system. The flow depth ranges from a few to several hundreds of feet with a resident time of a few weeks to a few years after entry, depending on the permeability of the rock strata. In a shallow flow system, the drainage coincides with sur¬face run-off water divides. Intermediate flow systems occur in minor hills some distance away from surface drainage. The travel distance ranges from several hundreds to several thousands of feet, the travel time from several months to tens of years. These systems are less dependent on seasonal recharge or discharge. In deep flow systems, the ground water travels from thousands of feet to miles, and transfers between surface basins. The travel time ranges from several tens to several hundreds of years. The systems generally receive recharge over a large area on major mountains and dis¬charge into major stream systems. 10.2 CASE STUDIES There are two ways of monitoring water wells for studying the effects of dewatering due to underground mining, i.e., water level and piezometric level. The water level is the water elevation in a water well that has penetrated two or more aquifers. Thus it indi¬cates the combined flow of all the aquifers that the water well intersects during the time of measurement. The piezometric level is the level to which water rises in a piezometer cased to a specific aquifer, and coincides with the pressure level of water in that aquifer. Therefore piezometric level reflects the water condition in that particular aquifer to which it is confined, while the water level represents the total yield of a water well without regard to the source of water. For instance, if a water well intersects two aqui¬fers, and if the lower aquifer is affected by undermining and goes dry while the upper aquifer does not, the water level in the well will drop, but may never go dry. Under this condition, the data obtained by monitoring the water level do not indicate the true behavior of the individual aquifers, especially if they are located at widely separated heights. 10.2.1 WATER LEVEL EFFECTS The effects of underground mining on ground water flow have been the subject of many investigations (Booth, 1984; Coe and Stowe, 1984; Owili-Eger, 1983; Rauch et al., 1984). However, the problems are very complicated, as have been exemplified by the conflicting conclusions reached by various investigators in var¬ious case studies. The most dramatic examples were described by Coe and Stowe (1984). In the first case (Fig. 10.2), the coal seam was 5 ft thick with cover from 400 to 800 ft deep. The majority of water supplies came from a sandstone aquifer in most ridge tops. When the face of the Panel No. 3 passed under it, dug well WW-1, which was approximately 670 ft above the coal, went dry, while the water level in Borehole B- 1, which was located at the center of Panel No. 4 with the bottom reaching the coal seam, also dropped about 160 ft. In Panel No. 5, the developed spring DS-2, which originated from the surface of the sandstone/shale contact and was approximately 750 ft above the coal seam, stopped when the face passed under it. The water level in the dug well W-2, which was dug into the shale about 700 ft above the coal seam dropped about 22 ft, but the well did not go dry. Therefore, nearly every spring or well located above or near the active panels was affected by longwall mining. In the second mine (Fig. 10.3), the seam was 5 ft thick with cover from 200 to 400 ft thick. Dug well DW-2, the bottom of which was 35 ft deep and approximately 330 ft above the coal seam in a perched sandstone aquifer, went dry right after the longwall passed under it. Drilled well W-3, in the sandstone aquifer, about 220 ft above the coal seam, experienced a 75-ft drop in water level when the face was under it, but showed some re¬covery after the face had passed under it. Ponds P- I and P-2 were developed in shale bedrock and were spring fed. They were not affected by longwall mining. Pond P-3 was developed in the sand¬stone aquifer, and its water table showed some decline when the face passed under it. Spring ST-1, which originated from Pond P-1 and was fed from several tributary valleys, was affected by longwall mining, probably because it passed across the panel edges where tension cracks drained off the water. Although the overbur¬den in case 2 was about half of that in case 1, the majority of water resources were not affected by longwall mining. Coe and Stowe (1984) attributed this discrepancy to: (1) a higher percentage of clays, shales, and claystones, resulting in a lesser degree of inter¬connected fracturing, and (2) a less rugged topography resulting in a less localized ground water flow system. Therefore, in order to assess the effects of underground mining, the premining ground water flow patterns, topographical, lithological, and meterological conditions must be known. Booth (1984) also monitored the ground water effects of a longwall mine (Fig. 10.4) in a seam 5 ft thick and 300 to 800 ft deep. There were three major aquifers: Morgantown sandstone approximately 30 ft thick and 630 ft above the coal; Saltsburg sandstone of up to 50 ft in thickness and 520 ft above the coal; and

Jan 1, 1992

By Sam H. Patterson

The advances in knowledge of world bauxite resources in the last few decades include contributions to the geology of deposits, discovery of large resources, shifts in availability, and changes in. the industry in response to political and economic pressure. Improvements in the understanding of geology have resulted from the larger numbers of geologists working on bauxite and better exchanges of information. The large deposits discovered are mainly the laterite type in tropical regions. These discoveries have led to major increases in bauxite resource estimates as well as to shifts in bauxite availability and in the ranking of producing nations. Changes resulting from political, environmental, and economic pressures have resulted in increased costs of bauxite and in renewed interest in potential nonbauxite sources of aluminum. Aluminum is produced from nonbauxite raw materials only in the U.S.S.R.; however, research on extraction processes or investigations of nonbauxite alumina resources has taken place in several countries.

Jan 1, 1984

By Thomas Schultheis, William Heron, Paul Watson, Colin Warren

This paper describes the geology and geotechnics associated with construction of the Thames Tunnel, part of the UK’s Channel Tunnel Rail Link (CTRL). The 2.5km long twin tunnels run beneath the river Thames at depths of up to 40m and are currently under construction. They pass through varying geology comprising alluvium, terrace gravels and chalk with flints and are currently being bored using Herrenknecht mixshield slurry tunnel boring machines (TBM’s). This paper outlines the lithology and engineering properties of each geological formation and describes the geotechnical processes, potential hazards and difficulties experienced in the works. A summary is given into the extent of the investigative work in terms of route selection, tunnel design, TBM optimisation and further details are provided on the geotechnical aspects associated with the construction of the tunnel approach structures and the tunnels.

Jan 1, 2003

By M. A. Bothwell

The purpose of this paper is to describe the methods used to select mill discharge screens, and to outline factors which should be taken into consideration when choosing screens for this application.

Jan 1, 2001

By K. C. Shaver

Detailed examination of the Sloan Ranch diamond prospect has shown that the Sloan 1 diatreme, the Sloan 2 dike, and the Sloan 3 horizontal sheet complex are all parts of the same kimberlite complex. Geologic mapping, geophysics, soil chemistry, test pitting, and drilling all helped to delineate the structure. Bulk sample testing yielded moderate grades with encouraging gem-to-industrial ratios, but no large stones were recovered. These test results, along with supporting mineral chemistry data, suggest that the Sloan Ranch complex is analogous to sub- economic occurrences located near the margins of the Archean cratons in southern Africa.

Jan 1, 1987

By Ross D. Lawrence

Suggestions have been made that the appraisal of mining assets using discounted cash flow techniques should be based solely on proven and probable reserves in reliance upon the widespread international recognition of uniform resource definitions. Following a review of generally accepted valuation principles, a survey of the literature and, most importantly, a review of real transactions in the open market, it is clear that valuators should not be constrained by the growing acceptance of modern mineral resource codes. On the contrary, valuation practitioners should be encouraged to examine all classes of mineralization and, after making due allowance for risk, to utilize all mineral resources as a basis for determining fair market value.

Jan 1, 2002

By H. P. Schlanger, L. Paterson, B. H. G. Brady, B. E. Hobbs

A novel principle for a waste repository, based on a backfilled thermosyphon as the functional unit, is proposed. Such a unit reduces temperatures and temperature gradients in the vicinity of a waste package and in the repository near field, reducing leach rates from packages and thermomechanical disturbance of the rock mass. Preliminary analyses confirm the mode of performance of the system, and reveal some interesting features of material transport and sealing in backfill and rock fissures. The thermosyphon combines attractively with the prospect of developing a near-field geochemical trap with chemical specificity for radionuclides. It is proposed that a thermosyphon repository may provide superior performance of engineered and natural barriers compared with conventional designs. The achievement of the ability to predict accurately the performance of the thermosyphon, relative to other isolation schemes, will represent a benchmark in the understanding of the absolute performance of any repository.

Jan 1, 1986

By Subhash Sethi

The WIPP (Waste Isolation Pilot Plant) Project near Carlsbad, New Mexico. is a research and development project sponsored by the U.S. Department of Energy, designed to demonstrate the safe disposal of radioactive waste. A mine (repository) is being developed 2150 feet below the surface in a thick salt bed, which will serve as the disposal medium. The underground ventilation system for the WIPP project was originally designed based on a fixed project scope. The design criteria and ventilation requirements were developed for the performance of various activities as then envisioned towards the achievement of this goal. However, in light of new information and actual site-specific experience at WIPP leading to a clearer definition of the scope-related programs and activities, it was realized that the existing ventilation system may need to be modified. A re-assessment of the ventilation requirements--based on the current status of the facility and a clearer definition of the scope of the experimental programs, waste storage methodology, mine developmental activities. and current equipment list--indicates a two- fold increase in underground airflows from 210,000 cubic feet per minute (cfm) to 425,000 cfm. Various options to provide the increased airflow to the underground facility were considered and analyzed. Based on the techno-economic analysis, safety and environ- mental considerations, and other conditions unique to a facility like WIPP, it was decided to construct a new shaft to serve as the primary fresh air intake, along with the installation of additional fans in parallel with the existing set up. Low cost and the ease with which the new design could be implemented and integrated into the existing ventilation system with minimum impact on current activities and projected schedules were the guiding factors in designing the shaft and related ventilation modifications.

Jan 1, 1987

By William Petruk

Performance assessments are carried out to monitor operations, to evaluate performance and to identify processing problems. The assessment involves collecting and analyzing representative samples from critical points in a flowsheet and interpreting the data. Sample analysis techniques include chemical analyses, mineralogical investigations, mineralogical analyses, and materials balancing. Chemical analyses provide the lowest cost assessment and should be used liberally, particularly in monitoring a process. Materials balances performed on chemical assays for a suite of samples are used as a first step in evaluating a process. Mineralogical investigations are more expensive than chemical analyses but need to be used only at the beginning of mining and metallurgical operations and as a second step in assessing processing problems. Quantitative mineralogical analyses combined with materials balancing provide the most complete performance assessment, but the procedure is expensive. On the other hand, the assessment has the potential of a large payback when carried out where warranted.

Jan 1, 1991

By D. B. Jenkins, D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity that exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into a worldwide business with a capacity of about 500 kt/a. This paper will present data on the chemistry, mining, manufacturing, and applications for acid-activated clays.

Jan 1, 1988

By Erich U. Petersen, W. Dan Hausel, William J. Tafuri, Donald M. Hausen, Douglas N. Halbe

The geology of Wyoming has been compared to some of the richest precious metal producing regions of the world including South Africa, Western Australia, and the Superior Province of Canada. These areas are all underlain by ancient cratons that contain some of the oldest rocks on the surface of the earth. But unlike the other cratons, the Wyoming craton (also termed the Wyoming Province) has been greatly modified by Laramide tectonics which thrust slices of the ancient craton through younger Phanerozoic sedimentary rocks. Unfortunately, the nature of the Laramide tectonics left vast regions of the craton at the bottom of the Tertiary basins unavailable to direct examination, but the exposed slices in the mountain cores contain some of the best exposures of Precambrian rock in the world. The cores of these uplifts contain extensive regions of relatively unmineralized gneiss and granite that include scattered fragmented supracrustal belts formed of metamorphosed volcanic, plutonic, and sedimentary rock. Some of these supracrustal belts exhibit similarities to the gold- and nickel- rich terranes of Western Australia. Yet these areas remain incompletely explored. Archean (> 2.5 Ga) gold deposits within the Wyoming craton are primarily confined to greenstone belts and related terranes. These supracrustal belts include relatively narrow vein and shear zone deposits with strike lengths of tens of feet to more than a mile. Some exceptional deposits possess widths of greater than 15 feet to possibly as much as 300 feet, but the majority have widths of± 5 feet. These belts include Cu, Ag, W, Fe, and Cr mineralization, asbestos and pegmatites, and anomalous Ni and Sri in addition to gold. The Proterozoic terrane (<2.5 Ga) exposed in the cores of mountain ranges in southeastern Wyoming includes a thick miogeosynclinal metasedimentary succession which unconformably lies on the Archean craton. These metasedimentary rocks are separated from a predominantly metavolcanic terrane to the south by a major Precambrian suture, or shear zone. The metasedimentary rocks north of the shear include quartzite-hosted stratabound Cu-Ag-Au deposits, Au-Ag veins, and Witwatersrand-type metaconglomerates with isolated gold anomalies. The suture includes scattered base and precious metal deposits in shear zone cataclastics. South of the shear zone, the metavolcanic terrane includes scattered volcanogenic Zn-Cu-Ag massive sulfide deposits, at least one Cu-Au porphyry, and two large layered mafic complexes. The northern edge of one of these layered intrusives yielded some platinum and palladium to miners at the beginning of the 20th century. Phanerozoic sediments host many precious metal anomalies. Some Au-REE anomalies occur in Cambrian conglomerates. Ag-Cu-Zn stratabound deposits are found in bleached Jurassic redbeds in the Overthrust Belt of western Wyoming. The broad Wyoming basins include many enigmatic gold occurrences and anomalies that can only partially be explained by detrital transport in fluvial systems. Many of these anomalies were probably geochemically transported and precipitated. Rocks of Late Cretaceous age along the flanks of the uplifts have numerous black sand deposits. These paleobeach placers contain concentrations of detrital heavy minerals with anomalous titanium, rare earths, and in some cases gold. Gigantic base and precious metal deposits are associated with scattered composite intrusives in the Absaroka Mountains in northwestern Wyoming. This deeply incised volcanic plateau includes several Tertiary age copper porphyry deposits with significant Cu, Mo, Ti, Pb, Zn, Au, and Ag resources that rival the porphyry districts of the Basin and Range Province. In the Black Hills of northeastern Wyoming, disseminated Au-Th-REE mineralization is found in association with fenitized alkalic igneous rock. In addition to disseminated mineralization-scattered gold, fluorite, rare earth and copper veins; lead, zinc, and silver replacement lodes; and tin pegmatites are found in this region.

Jan 1, 1990

By S. Lefond

A glance at the accompanying table and a review of contributors&apos; comments suggest that the industrial minerals industry is recovering from the recession of the past few years. Actually, the total value of nonmetal production in 1983 was $15.5 billion, up 10% over 1982. Nonmetallics still have not recovered to 1981&apos;s high of $25.3 billion, but at least it is on the way up. It is significant that cement (+20%), clays (+13%), gypsum (+16%), sand and gravel (+12%), sodium carbonate (+7%), and crushed stone (+11%) are up. These commodities are largely used in the housing and construction industries. Raw steel and steel mill products, iron ore production and castings, and purchased scrap are showing improvement and increased in value last year. They are, however, still not up to the high of 1981. These industries consume considerable amounts of many industrial minerals, such as limestone, dolomite, fluorspar as fluxes, and many types of refractories.

Jan 5, 1984

By Rudolf E. Greuer, Xintan Chang

Mine fires have always been of great concern to mining engineers and their behavior has been studied for a long time. Although an abundance of observations exist, no satisfactory mathematical model for their interpretation and extrapolation has become known. The paper presented here tries to close this gap, making use of the laws of chemical kinetics, energy and momentum conservation. To overcome the mathematical difficulties, the fire zone is axially divided into segments and radially into sections, each one with an extension of only a few inches. Conditions in segments and sections are updated in time intervals of one second or less. To solve the large number of resulting equations, a numerical solution is performed. The model has so far been tried on timber fires. It confirms experimental observations on the ignition phases and equilibria of these fires.

Jan 1, 1987

By P. Bevilacqua, M. C. Williams, T. P. Meloy

We will bet you that, without prior programming within 10 minutes, we can design and simulate a 10,000 unit operation separation circuit. We will even do it at your place. We do it all the time. [ ] There are no tricks; we do it in a spreadsheet. We do it in those user friendly spreadsheet such as Quattro Pro. Spreadsheets must be user friendly. Accountants use them as do managers, business men, lawyers, doctors and salesmen. What these users seldom realize, is how powerful a mathematical tool a spreadsheet is. Among their other capabilities, spreadsheets can do a finite element analysis. That is why they are useful for accounting. That is also why they are more useful to engineers in the mineral industry. Spreadsheets are ideally suited for the engineering problems in the mineral industry. We have used then for solving problems in: a) mine ventilation; b) circuit design and optimization of dense media, flotation and sizing; c) comminution circuit design; d) shaking tables; e) Humphrey spirals; f) sluice ways and channel flow; g) lock particle and liberation problems; h) tunnel and shaft stress problems; i) cascadograph simulation; j) complex heat transfer problems; k) flow in porous media; and sheet flotation (Figure 1). Mineral industry problems presented on or with a spreadsheet are an excellent teaching instrument, problem statement and solution tools and sales devices. Spreadsheets answer easily, quickly and reliably many mineral industry engineering problems. What makes spreadsheets so useful to the mineral industry. The short answer is: they are easy to use; mineral industry problems fit the spreadsheet format. Those reasons are part of the answer. The real answer lies with the structure of the spreadsheet itself. Essentially, a spreadsheet is a "finite element analysis" form of computer software. Many mineral industry problems are readily solved by finite element analysis techniques. While some in the mineral industry may think they have never heard of finite element analysis, most use it weekly if not daily. Any profit and loss statement is essentially a finite element instrument. In fact, any array of numbers where one number is related to another may be construed as a finite element analysis product. Finite element analysis is a common daily activity. To get an appreciation of a finite element analysis, think of a monthly sales forecast for the next year. For each product and for each month, there exists a dollar figure for the forecasted amount of sales. In the forecast statement, for a given product in a given month, there is a "box" where the forecasted figure is presented. The forecast figure in that box was arrived at through some type of formula. The formula probably required some information from other neighboring boxes in the master forecast statement. Voila, one has a finite element analysis. Today the analysis would be done in a spreadsheet. A typical mineral industry problem is ventilation in an underground mine. Think of a rectangular room and pillar mining operation. Each room has air entering at a given pressure and velocity and air leaving at another pressure and velocity. During steady state, the air entering and leaving the room is determined by conditions in the adjacent rooms. One can readily model the room and pillar mine layout in a spreadsheet, and then find the flow in and out of each room at steady state. Change the flow by moving a brattice cloth or blocking off a path way and one gets a new air flow profile. Change the numbers on the spreadsheet that reflect

Jan 1, 1993

By G. S. Grainger, R. A. Cummings, F. S. Kendorski, R. L. Butts

Georgia Power Company&apos;s Rocky Mountain Project, located approximately ten miles northwest of Rome, Georgia, in the Valley and Ridge Physiographic Province, is a pumped-storage facility rated at approximately 800 megawatts of peaking energy. Geological field explorations and borings enabled the division of the rocks along the tunnel and shaft alignment into distinct lithologic units and defined the ground--water regime. Field explorations included a detailed analysis of the rock mass discontinuities at available rock unit exposures. Testing of rock strengths was performed in several phases in both the field and the laboratory. The field testing consisted of point-load testing, geophysical testing, in situ load testing, and hydro-fracture testing. Laboratory testing determined the Brazilian split-tensile strength, the unconfined compressive strength, the triaxial compressive strength, the joint-direct shear strength, and the pulse velocity. The rock mass along the tunnel and shaft was also characterized by empirical classification systems. The classification systems included the Rock Mass Rating (B1IR) and the Rock Mass Strength Determination (RHSD). The results of the field explorations, field testing, laboratory testing, and rock classifications were used to divide the rocks into two structural groups. These rock groups were defined as volumes of rock wherein the rock mass behaves similarly in response to the excavation. Each group, therefore, required separate rock engineering consideration.

Jan 1, 1986