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By Joseph B. Alberts, David D. DiPonio, Francis B. Manning

From 1996 to 2001, Wayne County and 13 suburban Detroit communities constructed the Downriver Regional Storage and Transport System (DRSTS) to improve area water quality, protect public health and alleviate basement flooding. The project consisted of a 10-mile long storage and transport tunnel, a pump station at the existing wastewater treatment plant, 9 miles of relief sewers (6 in tunnel and 3 in open cut). The work was separated into 10 contracts. Due to hydraulic design requirements and other constraints, the tunnel profile was located generally 65 feet below ground surface within a soft to medium clay strata which skimmed along the top of a very dense glacial till “hardpan” overlaying bedrock. Boulders within the tunnel bore were recognized as a significant, but indeterminate risk. This paper presents a case history of the owner’s contracting strategy for risk assumption and management of the boulder impacts on the project. Actual conditions encountered during construction and contractual adjustments made to address problems are reviewed, and recommendations for future contracts are included.

Jan 1, 2003

By M. Fan

Froth flotation is the most widely-used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating ultrafine coal and coarse coal particles. Our previous fundamental test results demonstrated that cavitation-generated nanobubbles can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubble on the flotation performances of different particle size fractions of coal was investigated using a bank of 10-liter flotation cells, a specially designed 50 mm inside diameter column and a 152 mm inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during coal froth flotation process improved flotation efficiency. The use of nanobubble in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes. The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.

Jan 1, 2012

By William C. Grady

The environmental and economic problem created by pyrite in coal are well documented. The removal of pyritic sulfur prior to, or during, utilization has been the object of considerable research, however, much of this research has proceeded without a proper knowledge of the microscopic occurrences of pyrite in coal. This paper investigates the forms, occurrences, and variations in the distribution of pyrite in major West Virginia coal scan. Twenty-nine samples from twenty-two major west Virginia coal scans were selected for this study (see Table I). The samples were selected so as to be representative of the major coal producing areas of the state. All samples, except five, were collected at active surface mines, as indicated in Table I, and all except one were channel samples. The time interval between sampling and preparation of polished microblocks varied from two months to two years, though most were prepared within three months of collection. Grinding, screen¬ing, and riffling of samples to obtain 250 grams of -20 mesh coal for microscopic analysis strictly followed ASTM procedure D2013-72.

Jan 1, 1976

By Fritz Kleiner, Walter Meintrup

On Nov. 4, 1981 A/S Sydvaranger's 1-kt/h (1,100-stph) wet-process, iron ore ball mill completed its first four months of uninterrupted, full-load operation in Kirkenes, Norway. This 6.5-m-diam (21-ft-diam) mill is driven by a gearless ring or wraparound 8.1-MW (10,860-hp) motor at 13.1 rpm-a first of a kind in this segment of industry. This article examines reasons for selecting this type of drive over more conventional schemes, lists specific advantages of such large mills, and describes the installation in Norway. History For almost a decade, good operating experiences have been gained with 28 gearless ring motor drives in the cement industry, driving 2.5 to 4-m-diam (8.2 to 13-ft-diam) tube mills with drive powers ranging from about 3-4 MW (4,000 - 8,000 hp). Why then did the mineral ore processing industry hesitate until 1980 to adopt this successful concept for similar applications on ball, semiautogenous, and autogenous mills? There are a number of good reasons in the eyes of conservative mill builders and operators, the most commonly cited ones are: • No operating experience in this segment of specialized industry. • More severe environmental conditions in the wet ore grinding process. • An indifferent attitude of mill builders and electric motor manufacturers towards new drive technologies. • Limited confidence in solid-state power supply systems, such as frequency converters of the required size. There have been and still are numerous problems associated with low-speed geared mill drives of any kind, especially with individual motor/gear sizes approaching or exceeding about 4 MW (5,360 hp). Every mill builder knows about them, but operators learn to accept them as inevitable. The Decision to Change Three things combined to break this technological stalemate: the courage and progressive spirit of one major iron ore processor in Scandinavia, the cooperation of three experienced manufacturers, and an unusual application problem that could not be solved by any conventional approach. The last factor was surely the decisive one, but the first one does not come as a surprise either. The Swedes near Kiruna and the Norwegians around Kirkenes are experienced ore miners and processors, and much credit goes to them for technological breakthroughs in the industry. At A/S Sydvaranger in Kirkenes, above the Polar circle at about the latitude of Alaska's northern tip, the existing grinding facilities, with a total of 14 100 to 240-t/h (110 to 264-stph) ball mills, can not be expanded. Nevertheless, to increase mill throughput, only installing a larger mill in place of an existing smaller one was a practical alternative. For this replacement, the owners set requirements that seemed impossible to meet: • The old 100-t/h (110-stph) ball mill should be replaced with a new ball mill with 10 times the rated throughput, without significantly impairing the operation of the remaining mills, and without significantly changing the mill building. • The new mill should have a variable-speed drive to ultimately optimize the grinding process by means of a closed-loop process¬computer-controlled grinding cycle, and to minimize the specific energy consumption. • Availability, efficiency, and life expectancy of all new components must be higher than those being replaced. • Inrush-current and harmonic loads on the rather weak electric supply line must be minimized to ensure safe plant operation. All old ball mills at A/S Sydvaranger are the geared type, using single synchronous and wound-rotor, slow-speed motors with ring-and-pinion gears. Operators are familiar with the limitations and problems associated with such drives, and they are aware that the following items become major concerns when drive powers are drastically increased: • Gears are subject to wear and tear, require frequent maintenance, and eventual replacement of major parts. • Gears are sensitive to misalignment, overload, and thermal distortion, limiting their useful life. • On dual or quadruple drives, load-sharing and torque oscillations between motors can be a major reason for concern. • At these speeds, ring-and-pinion gears reach their torque transmission capabilities altogether at around 4 MW (5,360 hp) per motor/pinion. To obtain the desired variable-speed performance of the new drive, the only practical and economical conventional solution would have been a frequency-controlled, low- or medium-speed dual motor drive with about 8 MW (10,720 hp) of power. This, however, was not feasible because of limited floor space. Therefore, bids were solicited for the alternative drive method, the gearless ring motor. General Considerations Why are such large mills considered? After all, one could avoid all the problems by simply staying with smaller mill unit sizes. Under competitive pressures of free markets, however, grinding efficiencies and specific energy consumption become key factors in selecting new equipment. Specific energy consumption of ball mills decreases with increas-

Jan 9, 1982

It is crucial to reestablish a domestic rare earths minerals production industry to help secure the Nation's clean energy future, reduce the U.S. vulnerability to material shortages related to national defense, and to maintain our global technical and economic competitiveness. Given that the Chinese dominance of the rare earths market has adversely impacted supply stability and endangers the United States and its allies' assured access to key materials, rare earths should qualify as materials either strategic or critical to national security. Further, the U.S. government should facilitate the reintroduction of a globally competitive rare earth industry in the U.S. Realization of this objective requires: ? Developing domestic processing capability so that the U.S. is not primarily dependent on China as a source of rare earth ore, and almost exclusively dependent of China for processing of the ores. ? Providing a mechanism where access to Federal lands for rare earth exploration and extraction is possible, and ? Training engineers to design and operate rare earth ore processing facilities

Jan 1, 2011

By G. Barbery

In Mineral Processing, the objective of most processes is the separation of mixtures of minerals, which are originally associated in composite particles. Feed preparation processes grinding for instance, which take place before beneficiation or separation processes do not usually break particles at the boundary between mineral phases. They produce composite ("middlings") as well as liberated particle. It is therefore necessary, in a particulate system, to determine the proportion of particles which are liberated as well as, ideally, the size distribution of minerals which remain associated in composite particles. Up to now, there has been a lack of experimental techniques to characterize completely composite particulate systems. Heavy liquid separation which is commonly used to obtain information of this type can only be applied to simple binary cases for which one mineral has a low density (lower than e.g 2.8 ). The technique which is proposed in this paper involves the measurement of parameters on polished sections of particles mounted in a matrix, and the use of mathematical transformations to reconstruct in three-dimensions the information obtained from these measurements .

Jan 1, 1977

By David Whitehead

My qualification to speak on the globalization of the the mining industry comes from having worked in the industry in Europe, North and South America, Africa and Australasia in positions ranging from exploration geologist to chief executive. For about a third of my career I have lived and worked in the Southern Hemisphere. And for much of the rest of my career I have been involved in or responsible for activities in the Southern Hemisphere. This has given me the opportunity to experience globalization from the sharp end, as it were. This means speaking English with an Australian accent, Spanish with a Chilean accent, French with a West African accent and Dutch with an English accent. My topic is globalization, especially of the mining industry from a Southern Hemisphere perspective and specifically the experience and history of Gencor in that context. First, I will say a little about what globalization means to the southern part of the world: How and why the South differs from the North and how the challenge of globalization affects a south-based company differently than a northern one. I will also detail how Gencor has made significant progress in globalizing through the acquisition of mining assets from Shell. As Fig. 1 shows, I have divided up the world into northern and southern components, rather than hemispheres. The southern world comprises mainly countries that have emerged from the status of economic - if not political - colonies of nations such as England, Spain, Portugal, France, the Netherlands and, surprisingly, Italy and Germany. I have not considered the Indochinese and Arabian peninsulas in my southern world. The emergence of the. former is still in its early stages while the latter is clearly a part of the northern economic system. Large parts of Africa and South America are geometrically in the Northern Hemisphere but economically in the southern world. The reverse is the case for the IndoPersian peninsula. With the distinguished exception of Australia and South Africa, most of these countries nationalized their mining industries and mineral patrimony after attaining political independence. A major element of the globalization of the mining industry is related to the privatization of the mining industry in these countries and to the opening up of their min¬eral patrimony to non-national exploitation. The Southern Hemisphere is the watery part of the world. It is almost three quarters ocean as against a slight preponderance of land in the north. Economically, ocean areas have only a fraction of the productivity of land, except in a few oil-rich areas like the Gulf of Mexico and the North Sea. The consequence is that even on an economically level playing field we would expect the south to generate only about one third of the world's economic product.

Jan 1, 1997

By I. Pordea

The materials used for the construction of buildings contain natural radionuclides of the U238 and Th232 series and are ? 50% due to land radioactivity. Another component of natural radioactivity is K40, with ? 40%. The presence of these radiopollutants in the final products (i.e. bricks, concrete) due to body irradiation is by two pathways: external irradiation and internal irradiation. External irradiation is due to gamma radiations emitted by Pb214 (RaB) + Bi214 (RaC) from the U238 series, by Ra228 (Mezothoriu I) + Ac228 (Mezothoriu II) + Tl208 (ThC??) from the Th232 series and by the K40 radionuclide. Internal irradiation is due to inhalation of radon (Rn222) and Rn220 (Tn) plus short life descendents (Po, Pb, Bi), radionuclides which are present in concrete. A fraction from radon present in concrete enters into a house leading to internal irradiation by inhalation. In Romania, the maximum concentration of radon allowed for new buildings is 200 Bq/m3.

Jan 1, 2008

By Stuart K. Nicol, Malcolm D. Engel, Neville T. Moxon

Ion flotatir,n of gold is a process being developed to selectively float extremely dilute aurocyanide liquors using a novel surface active complexing agent. The principle of ion flotation is also applicable to a wide range of other metal-containing solutions. The market potential of the gold flotation process would be enhanced by the possible combination of the gold recovery capabilities with both cyanide recovery and metal removal. For example, recovery of copper cyanides from a return liquid strean1 would be a useful means of reducing operating costs and satisfying environmental pressures to treat tailings dams. Experimental work is described where samples of tailings solution from a far north Queensland gold mine were subjected to ion flotation to remove copper cyanide species from a clear recycle solution. The form in which these products was removed was of secondary importance compared to the need to produce a clean solution for use in the plant. Recovery of the anionic copper cyanide species was accomplished using a quaternary ammonium surfactant.

Jan 1, 1991

By Staff

GENERAL DESCRIPTION The Lucky Friday mine is located in Mullan, Sho-¬shone County, Idaho. The mining method is horizontal slice cut-and-fill (with timbering for support or un¬timbered) using hydraulic sand. Cemented sand fill at a 1:17 ratio is used in sill pours and at a 1:7 ratio for the final 152 mm (6 in.) capping in successive stope floor pours. Annual production with 100% cut-and-fill mining is 167 829 t (185,000 st). The average depth of mining is 1296 m (4250 ft) and the average travel time to the stope is 45 min. GENERAL ORE BODY REQUIREMENTS AND LIMITATIONS Size The ore body is 396 to 488 m (1300 to 1600 ft) long on strike, 1421 m (4660 ft) on dip, with an average width of 2.3 m (7.5 ft). Dip varies from vertical to1.2 rad (70°) Ground Conditions, Ore Value, and Production Requirements The ore body contains quite strong argentiferous galena and quartz. The hanging wall and footwall are strongly sheared and fractured. Ore value is $211/t ($192/st).

Jan 1, 1982

By B. J. Arnold

A coal's size distribution clay content and moisture content can affect its handling behavior. But the combined effects of these properties and the effects of other properties are not known. Research underway at CQ Inc.'s (formerly EPRI's) Coal Quality Development Center (CQDC) and at Iowa State University (ISU) will answer these questions as part of a four year project to develop a coal handleability index for utilities to use when specifying coals. This paper will present preliminary data from the first year of the project, which focused on obtaining data on the chemical and physical properties of carious coals and their measured handling properties. Additionally, size, ash and moisture analyses and shear test data for several coals used at one power plant will be presented along with correlations between these physical and chemical properties and the measured handling properties. These data lead to the conclusion that while moisture content is the most important variable, the amount of -44 µm (-325 mesh) coal fines is a significant factor in determining coal handling behavior.

Jan 1, 1992

By Legett Garrett

Texas Utilities Generating Company (TUGCo) surface mines lignite for use as a boiler fuel at mine mouth generation stations. Currently, the annual lignite production requirement of approximately 28 million tons necessitates mining across approximately 1,600 surface acres each year. The mining operations, located in Freestone, Panola, Titus, and Hopkins counties, Texas, have drastically disturbed some 13,000 surface acres to depths of up to 110 feet since initial startup in 1971. The TUGCo mining philosophy, a commitment made prior to initiation of mining operations and prior to any mining regulations, includes a return of mined-out land to private ownership in the most useful state possible. In the areas of TUGCo operations, the local economies are based upon agricultural production. Historic land use surveys have typically shown a trend from row crop production to pastureland for cattle production. During the 1960?s, the percentage of acreage devoted to row crop production approached zero with respect to the total acreage devoted to agriculture. TUGCo reclamation operations have therefore emphasized restoration of land to a state that is favorable to cattle production

Jan 1, 1982

The evolution of surface mine layout configuration is a function of the schedules and sequence of material excavation within the optimized layouts. The production schedules and sequence of materials movement from multi-bench and multi-face operations are difficult to plan and execute. However, the ability to maximize the profit or net present value of an orebody is largely dependent on the mining schedule. The mining schedule will determine the life of the mine, the projected cashflows, and the investment requirements over the mine life. The pit geometries, pit expansion rates and the periodic volume of materials from different benches in a multi-bench, multi-face open pit mine determine the equipment requirements. The volume of materials excavated, as well as pit layout changes from circular and elliptical geometries of an oil sands mine were modeled using analytical geometric and parabolic partial differential equations (PDEs) and solved within Matlab. The results show that the geometric values are almost the same as those obtained from PDEs for different pit configurations. The economic analysis shows that both the current mining system (CMS) and the cyclic excavator conveyor belt control system (CycEx CBCS) are viable with high NPV (= $3.20 × 1010), PI (> 19%) and IRR (> 29.02%) with short discounted payback periods (= 3.24 months). The CycEx CBCS option is more economic than the CMS option. Its NPV is 1.27 times that of the CMS option. The PI and IRR for the CycEx CBCS option are respectively 2.24 and 1.13 times that of the CMS option. As well, the CycEx CBCS option has almost half the DPBP of the CMS option. The CMS option has an operating cost of $1.386 per tonne ($2.774/barrel) while that of the CycEx CBCS option is $0.779/tonne ($1.558/barrel). These results show that the CycEx CBCS option is the better option for mining companies working on oil sands deposits to invest in.

Jan 1, 2011

By E. A. Rychkun

Introduction Minicomputers have been gaining acceptance in mining. Low cost interactive processing and plotting can now be controlled by geologists or engineers needing rapid solutions and specialized mining software in formats that allow noncomputer personnel to readily interact with computer processes. User-oriented programs maximize the use of interactive display features and graphics, as shown by the HP9845 minicomputer, a unit with portability, processing power, graphics capabilities, capacity, and peripherals such as plotters, digitizers, disk drives, and printers. Application Coal exploration projects require that much effort be spent determining coal volumes within trial pit limits. This determines a prospect's viability and potential. Adapting volume calculations to a computer has been limited, since it was difficult to create reasonable representations of complex coal seam geometry with a digital process. So many of the simple mechanical procedures needed to produce pit reserves are still performed manually by geologists and engineers. But with new minicomputers and their interactive graphics, it is now practical to accurately model complex structures without tedious calculations. GEOSEM (Geomin Seam Oriented Exploration System) is a computer system designed to analyze coal prospects. The system shows how a coal prospect, with complex geology, can be quickly analyzed, modeled, displayed, and evaluated for mineable reserves. Its interactive graphics allow rapid visual presentation of data, high-speed tabular reports, and precision plotting. The system is most effective when used by a geologist or engineer who selects the required operations and specifies relevant parameters via screen and keyboard interaction. Rolling Hills The Rolling Hills prospect represents a typical Rocky Mountain coal deposit. Enough geological interpretation has been done to show a complex system of block faulting with coal seams following synclines of stratified lithologies. With the completion of initial drill hole exploration, questions arose concerning coal volumes and strip ratios involved with various pit limits. Quality information had been gathered on the coal intercepts. It was decided that coal vol¬umes and pit designs were of prime importance. The objective was to enter and display data, create a computer model based on interpretation, develop pit designs, compute seam/ waste volumes, and report various contents. The project, begun by entering data in the GEOSEM system, was completed in several days. Data Entry For modeling, the prime information was seam identity and drill hole intercept. Other information-rock type, Btu rating, and percent of ash, sulfur, and moisture-was also available. It, too, was entered into the data base through the computer keyboard and then reported, verified, and corrected. Various reports can be produced, according to user specified sort parameters. For example, from an analysis of available data, only 14 intercepts could be found with Btu value greater than 8000 and sulfur content less than 0.4%. The sort option can also be used prior to entry into the analysis routines. Data Analysis Though the objective was to create a seam model and compute reserves, it became necessary to project quality information into unsampled areas. Statistical analysis was then war-ranted. A typical analysis correlated the lack of relationship between percentage of ash and Btu. Although histograms were also produced, these typified a lack of samples and "ragged" distributions. A geostatistical analysis was also applied, showing the results of computing a 2-D variogram on the largest coal seam. Results showed an average range of 18 m, with a poorly defined variogram. Data Display and Drafting Scaled plans and sections were required so seam locations could be compared to hand drawn interpretations and drill coordinates verified. At the same time, topography could be interpolated from collar elevations to determine whether surface control points were needed for better definition. In addition, a new set of 50 final-scale drawings were required, showing new drilling information. By using the computer screen as a "scratch pad" device, various sections were displayed and then plotted on a drum plotter at the desired scale for overlay on original sections. Both lithology and seam name were plotted for the five main sections. Since the coal seams were striking north-south, sec-

Jan 11, 1981

By T. C. Rao

The quantum of coal fines below 6 mm in run-of-mine (ROM) coal has been increasing due to progressive mechanization of mining methods which has created a substantial incentive, worldwide, to develop suitable fine coal beneficiation techniques. The majority of the efforts have been directed toward reduction in ash/sulfur contents in clean coal. The beneficiation techniques may be broadly grouped as those based on specific gravity and surface property. The processes, which use heavy medium cyclone, water-only cyclone, concentrating tables, and spirals, belong to the former group while the latter group encompasses froth flotation, column flotation, oleo- flotation, and oil agglomeration. In almost all the gravity based techniques, it has been noted that a classification step prior to beneficiation is essential for effective treatment. In general, the effect of design and process variables on the performance of these units and also the quantification of the processes have been the main areas of research and development. In froth flotation, efforts throughout the world have been mainly to understand the effect of variables and to optimize the process. Quantification of the process has been attempted through kinetic studies and mathematical modeling. The efforts have led to the development of new reagents, machine designs, and flowsheets for a specified objective. The attempts so far with the column flotation and oleoflotation processes have indicated a great potential. Extensive R&D efforts are in progress to understand as well as to commercialize the processes. The efforts in the oil agglomeration process have been toward substantiating the inherent merits of the process by developing cheaper bridging liquids and technology to recover and reuse the oil to make the process commercially viable. Modeling of the process has also been attempted to predict the yield and size distribution of the agglomerates. This paper reviews and summarizes the recent developments in the science and technology of fine coal beneficiation processes. The current trends in R%D efforts for these processes are also highlighted.

Jan 1, 1987

By Kenneth L. Schellie

In preplanning the reclamation of a pit or quarry the geology of the site is the name of the game! The planner must know the parameters of the deposit, the quantity and kind of earth materials to be removed, and the amount and nature of the materials to be left behind or wasted as the result of processing the marketable product. With many states and most local jurisdictions requiring reclamation plans prior to the issuance of mining permits, the need for accurate and complete data concerning the geology of the site becomes increasingly important. The producer need only know that marketable materials are available in sufficient quantity to make the mining operation economically feasible-the planner, in order that the land may be reshaped for a useful purpose, must have reasonably precise information as to the dimensions and configurations of the pit or quarry following extraction and the amount and type of materials available on the site (or in some cases offsite as well). Therefore the geology of the site is of major significance in determining the land forms and use capabilities of the property upon completion of the mining process.

Jan 1, 1974

By Les T. Zoschke

Over ten years ago, Modular began development and implementation of its DISPATCH System for haulage optimization in open pit mines and now has over two dozen systems in operation worldwide. The so-called 'top down' approach used in system design and implementation was deliberate. This foresight now allows addition of features which would otherwise prove infeasible - without complete system redesign. Until recently, truck and shovel operator input provided timing data needed for optimal allocation. Now, addition of a high-speed, general purpose token ring loop controller and infrared (IR) transponders to each piece of mining equipment automates these important functions. Here, we discuss new devices, systems, and subsystems comprising mining's future.

Jan 1, 1992

By Indranil Roy

Gua supergene enriched iron ore deposit from Jharkhand, India has been geostatistically modeled. Population modeling shows a negatively skewed 3-parameter log-normal fit for Fe and positively skewed 3-parameter log-normal fit for Al2O3 and SO2. Semi-variographic studies for Fe indicate spherical function fit using point kriging cross-validation technique with Co=4.06(%)2, C5.11 (%)2, Co+C=9.1 7(%)2 and 'a'=348m. Kriging with 50mx50mx 10m block size at 740mRL led to a global mean kriged estimate of 61.98% and kriging variance of 4.04(%)2 for Fe with central 90% geostatistical confidence limits at 61.39% and 62.24% for that level. This led to an ore inventory at 740mRL as 7.29 million tonnes of ore.

Jan 1, 2002

By S. Hodgson

The Red Dog zinc/lead deposit in northwest Alaska is the second largest zinc deposit ever discovered. Being developed by Cominco Alaska with startup scheduled for early 1990, it will ultimately be the largest zinc mine in the Western World. Table 1 illustrates the reserves of the deposit.

Jan 1, 1988

By J. Hansen

This paper has been written for presentation during the Open Pit Mining Session at the SME Annual Meeting and Exhibit, Denver, Colorado, February 26 to 28, 2001. The paper addresses the application of automated monitoring of electric rope shovels to improve performance and blasting technique.

Jan 1, 2001