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By Sharad Mathur

The purpose of this paper is to present the benefits of high reactivity meta kaolin (HRM) in high performance cement-based systems. HRM, unlike other pozzolans, is manufactured from selected naturally occurring kaolin ore and carefully processed under stringent conditions to result in a consistent product with highly pozzolanic properties. HRM is an ultrafine pozzolan that enhances the mechanical properties (workability and strength) and chemical stability (durability) of Portland cement concrete and cement-based products. HRM is unique with respect to its white color which makes it an ideal choice for architectural applications where visual and aesthetic concerns are critical.

Jan 1, 2003

By Ernst Langer

INTRODUCTION Morro do Niquel is located near the small town of Pratdáolis in the southwest part of the State of Minas Gerais, Brazil, about 300 km in a straight line north of São Paulo and 300 krn west of Belo Horizonte. The deposit is known since 1935. Systematic exploration started, however, only in 1957 and production with one furnace in 1962. Since 1969, after the installation of a second furnace, the mine produces about 2 500 tons of nickel, contained in ferronickel, per year. This production is now consumed totally by the Brazilian steel industry. The "Morro do Niquel" is a serpentinite stock of 900 by 400 m which rises 200 m high above the surrounding metamorphic rocks of Algokian age (see Figure 1). On top of the hill there is a leached barren zone of about 200 by 400 m, generally 20-30 m deep, which consists practically only of a boxwork of quartz colored brown by limonite. Surrounding this zone on the sides of the hill is weathered, decomposed serpentinite which contains about 213 of the economic nickel mineralization. Roughly 113 of the ore reserves lie below the leached overburden representing ore of a different type. The geological map and cross-section, Figure 2, give a clear picture of the occurrence.

Jan 1, 1979

By E. J. Beckman, R. M. Enick, C. Shi

A novel liquid-liquid separation for the recovery of free or liberated gold from mixtures of fine particles was evaluated. Two inexpensive and environmentally benign fluids were selected for the study, water and carbon dioxide. The separation, which is conducted at 295 K and at the vapor pressure of carbon dioxide (6.0 MPa), is based on differences in wettability between the precious metals and other minerals. Contact-angle results indicated that, in the presence of water and liquid CO2, gold is slightly hydrophobic. The addition of CO2-soluble fluoroalkyl thiols or f uoroetherthiols increased the hydrophobicity of gold exposed to water and CO2 to a greater extent than alkylthiols. Minerals, including quartz, pyrite and magnetite, were hydrophilic. During the separation, an aqueous slurry of fine mineral and gold particles was mixed with liquid carbon dioxide. Pure gold particles (-325 mesh) were found to agglomerate at the H2O-CO2 interface. The minerals tended to remain in the aqueous phase. Despite these promising preliminary results, very poor gold recoveries were obtained when applying the procedure to an Australian gravity concentrate. This was attributed to the native gold particles in the concentrate being either too large, agglomerated in slimes or coated with minerals. Although this particular application was unsuccessful, this water-CO2 biphase technique may be applicable for other separations that require the removal of very fine, hydrophobic particles from an aqueous slurry.

Jan 1, 2000

By George W. Luxbacher

The inclusion of a new term "planned subsidence" in the Surface Mining and Reclamation Act of 1977 has lead the U.S. coal mining industry into a new aspect of engineering: subsidence planning. Subsidence planning has necessitated the integration of geotechnical, civil, and mining engineering disciplines. Although much of the foundation and application work has been completed, subsidence planning is still a developing area. This paper discusses the application of subsidence planning in several brief case studies (a high voltage transmission tower, a sewage treatment plant, and a slurry impoundment), emphasizing the risk assessment aspects necessary to account for some of the uncertainties that may exist.

Jan 1, 1986

By E. W. Cokayne

GENERAL DESCRIPTION OF THE METHOD The original application of sublevel caving was in ground so weak that it would collapse even in small headings when the support was removed. Heavily tim¬bered drifts were driven across the ore body; the timber was removed at the end of the drift, and the ore caved and slushed out. When dilution became excessive the next set was removed and so on. This method gave high dilution and poor recovery and was slow, but it was the only way to mine this type of ore body at that time. In more recent times the method has been adapted to stronger ground which needs to be drilled and blasted, so it is not a caving method as far as the ore is con¬cerned. However, the method does rely on the walls to cave and so the name sublevel caving has been retained. The method as presently generally applied is shown in Figs. 1, 2, and 3. Sublevels are established at approximately 7.6 to 12.2-m (25 to 40-ft) vertical intervals. They are usually accessed from a ramp system. A haulage drift is driven down the strike of the ore body, but in the waste. Production drifts are turned off the haulage drift and driven across the ore body on about 10.7-m (35-ft) horizontal centers. This divides the ore body into a geometrical pattern. Slot raises are driven at the end of the drifts near the ore-waste contact and the slot is expanded to the shape of the fan drilling. Up holes are drilled to break towards the slot at burdens of 1.2 to 1.8 m (4 to 6 ft). They are drilled past the next sublevel to the production drift im¬mediately above. When a sufficient number of fans has been drilled, production can start by blasting one or two fans at a time towards the slot. Load-haul-dump (LHD) units are used to muck the ore, which rills out into the drift. At first, when only a small area is mined, the walls may not cave, and the operation will be similar to open stoping. Later, sloughing from the walls will fill any voids created, and the ore after blasting will be con¬tained by the caved waste and gravitate downwards as mucking proceeds. This process is repeated in each of the production drifts as the face is retreated towards the haulage drift. When the top level has been retreated back a safe dis

Jan 1, 1982

By R. M. Imhof, M. J. G. Battersby, J. V. Brown

There is a plethora of former industrial sites where coal mining operations have left large slurry impoundments. These contain raw washed fines, which have previously been too expensive to process to requisite grades for commercial use. New technology has been developed for fine material processing, namely the Imhoflot pneumatic flotation G-Cell. This froth flotation technique is a highly efficient means of concentrating coal and is particularly appropriate to the nature of materials encountered in tailings ponds. The high volumetric throughput resulting from the vastly reduced residence time in the cell allows for drastically reduced equipment sizes when compared to conventional flotation cells. This means the process, when combined with innovative pre treatment and filtration equipment can be developed as a mobile plant concept. This is seen as a minimum requirement when re-treating and rehabilitating fine coal ponds.

Jan 1, 2003

By M. Fofana

The use of a laboratory-scale magnetic fluid-based separator for coal separations was examined. A Frantz laboratory magnetic separator was modified by fabricating new pole pieces of the appropriate geometry to provide the proper magnetic field gradients. Two separation chambers, which were constructed out of Plexiglas, were designed to fit between the pole pieces. A commercially available, water-based, ferro-magnetic fluid was used as the separating medium. The separating density was changed by varying the intensity of the electromagnet. Both batch and continuous separations were made using 0.59x0.50 and 0.18x0.15 mm coal. The results are compared to those obtained using organic liquids.

Jan 1, 1996

By D. I. Phillips, P. J. Bethell

This paper focuses on the -1/2 mm cleaning at Elk Run Coal. The original circuitry incorporated desliming cyclones. Problems with slimes entrainment in the cyclone underflow (froth cell feed) resulted in poor froth cell selectivity. Laboratory test work led to the installation of high frequency desliming screens. Consequently, great improvement in cell performance was brought about by enhanced desliming with the ability to use split flotation. The modifications resulted in significant improvement in total plant performance and overall yield while maintaining clean coal quality.

Jan 1, 1987

By Khaled Morsy

Cementitious seals are made of foamed cements with strength ranging from 100 to 600 psi. These cementitious seals are usually used at locations where the seal will be subjected to some convergence, assuming that this material can absorb entry closure without compromising the structural integrity of the seal. Prior to 2006, Lake Lynn Experimental Mine (LLEM) conducted full-scale tests on various cementitious seals designed to meet or exceed the 20-psi horizontal static load requirements of the old 30 CFR1 75.335. Both hydrostatic and dynamic loading tests were conducted. The structural response (pressure and displacement readings) obtained from these tests were recorded. The stability of the cementitious seal is based on balancing the load applied to the face of the seal from the explosion against the shearing resistance at the seal/rock interface. Therefore, the properties of the seal/rock interface, such as stiffness, cohesion, friction, etc. are critical to determine the stability of a cementitious seal. These properties are usually assumed by the researchers in their models. This paper emphasizes the importance of having the correct properties of seal/rock interface in the numerical modeling. FLAC 3D models were developed to simulate Celuseal2 cementitious seals subjected to both hydrostatic and dynamic loadings. Using the hydrostatic and dynamic loading test data conducted at LLEM, the static and dynamic properties of the seal/rock interface were back calculated. The FLAC 3D models showed good agreement with the test results.

Jan 1, 2009

By Håkan Tyni, Jan Björkman, Per-Olaf Samskog, Irving Wigdén

Process automation can provide better utilization of capital investments. Furthermore, it is a necessity for securing the high demands of product quality. In this paper, process automation in underground mining as well as in the beneficiation plant will be discussed. The development of reliable broadband communication systems for real-time transfer of image, audio and data have enabled remotely controlled LHDs and drilling rigs. In the beneficiation plants, model-based expert control systems far on-line dynamic process optimization and control have been installed in unit operations such as grinding, flotation and induration.

Jan 1, 2000

By M. O. Woodburne

The Mojave Desert province is comprised of a diverse group of mountains that range in elevation from about 2,000' (600 m) to 3,000' (900 m), separated by tracts of alluvial cover. The province is bounded on the southwest by the San Andreas fault, on the north by the Garlock fault, on the east by the Death Valley- Granite Mountains fault. Rocks preserved in the Mojave Desert Province collectively record a rich assemblage of Precambrian crystalline basement' ranging in age from ca. 1.8 to 1.35 Ga, upper Precambrian and Paleozoic Cordilleran miogeoclinal sediments and platform rocks, Mesozoic backarc and interarc shallow marine and continental sequences, locally emplaced Permian- Triassic syenitic plutons, extruded hypabyssal volcanic rocks of the ?Jurassic "Sidewinder Volcanic Series," and regionally intruded late Mesozoic granitoid batholithic rocks (Dokka et al., 1988). The Mojave block apparently was a high-standing element for much of the early Tertiary, with strata of Late Cretaceous or early Tertiary age preserved only on its margins. Beginning about in the late Oligocene an intense episode of regional north-south extension was developed in a roughly east- west trending belt that traversed the central part of the province. This extensional belt has been termed the Mojave Extensional Belt. The extensional regime lasted from about 22-17 Ma, and is generally divided into two phases. The first, from about 22-20 Ma records intense extension via the activity of crustal-scale, simple shear, low- angle normal faults, high-angle normal faults, and extensional fracturing, along with intrusion of intermediate to silicic volcanic rocks, including episodes of explosive volcanic activity. The Peach Springs Tuff, a major regional marker unit that extends across the Mojave from Arizona to about Barstow, forms an effective stratigraphic lid on the extensional interval, (i.e., is not rotated) and is dated isotopically at about 18.5 Ma. The extensional episode was followed by an interval of high- angle normal faulting and dike emplacement from about 19 to 17 Ma, and was accompanied by at least local uplift and volcanism. Most volcaniclastic and epiclastic sedimentary units of the central Mojave block post-date the interval of extension and normal faulting, and occur as a complex of marginal alluvial and more interior lacustrine facies that formed as recently as late Miocene (ca 13 Ma). Local sequences (e.g., Lava Mountains) record deposition up to about 8 Ma, but there appears to be a regional "gap" from then until at least local successions record Pleistocene deposition. Magnetic and isotopic age studies indicate a complex history of crustal rotations, distributed across a number of discrete domains, during the past 10 Ma. Some of the youngest volcanic and geomorphic features apparently developed at "holes" formed at the edges of rotated blocks.

Jan 1, 1995

By C. H. Sampaio

The effectiveness of modem spirals in the processing of fines from Brazilian coals is assessed and discussed. Coals representing the four major coalfields in Brazil have been cleaned in Reichert LD 9 spirals in pilot and industrial plants and performance results are here presented. Normalized distribution curves for all equipment and splitters are presented and were modeled using an empirical model. These data have been compared with those for shaking tables and water-only cyclones (WOC), and it has been observed that, in the size interval investigated, spirals have indeed superior accuracy than WOC and comparative performance to tables. By analyzing experimental as well as simulation results it could be observed that although limited by the poor liberation characteristics of most Brazilian coals, significant ash and sulfur removal could be achieved using spirals.

Jan 1, 1995

By S. K. Mukherjee, A. W. Laurito, M. M. Singh, N. I. Jayaraman

This paper describes the application of foam to control respirable dust in a double-drum longwall mining section. The feasibility of injecting an adequate quantity of foam through the shearer drum was initially established in the laboratory. Thereafter, underground testing of the foam system to determine its effectiveness on an active operating longwall was conducted in a mine in West Virginia. The foam system proved superior to the water spray system. The details of the laboratory and field investigations, the results obtained, and the degree of acceptance of this system by the mining company are discussed in this paper.

Jan 1, 1987

By Randal J. Barnes

In, any open pit mine the ability to make accurate production estimations for the shovel-truck system is an important asset. This is true in an operating mine wishing to estimate production under a set of system modifications (i.e. more trucks, fewer loaders, change in roads, etc.), as well as in the pre- mining planning stages of a property. Many different methods have been proposed for solving this problem; some of the methods rely heavily on "rules of thumb" while others are highly mathematical and require access to a high speed digital computer. Analysis of shovel-truck systems with the use of simulation models is a widely accepted technique within the industry. Through the use of such models it is possible to account for much of the inherent variability of the system and thus produce meaningful results. However, simulation studies are expensive. Formulation and setup of the actual simulation model requires a significant commitment of time and energy. In addition, the cost of the necessary computer runs is often of considerable magnitude.

Jan 1, 1979

By Heinrich H. Becker, Vladimir L. Konyukh, Sergey P. Koltsov, Valery A. Davidenkol

Ramifide conveyor transport of the biggest russian coal mine "Raspadskaya" is simulated by Petri nets. There are 6 longwalls with accidental output. 12 belts, and 5 transfer bunkers at this mine. It is necessary to coordinate transport links for recon- structed conveyor system. Many tasks were solved by dynamic simulation, such as estimation of transport lateness, influence of transfer bunkers on an unevenness of total coal flow, maximum filling of each bunker, maximum time of main conveyor refusal, co-ordination of unloading for dependent bunkers, choice of main conveyor. The problem of mine-wide conveyor transport animation for dispatcher is formulated in reference to mine "Komsomolets". OBJECT OF SIMULATION The biggest russian coal mine "Raspadskaya" is situated on a south part of Kusnetski coal basin (West Siberia). One mines about 20.000 tons of coal out of flat seams by 2.2-4.5 m thickness in a day. There are 6 fully- mechanized longwalls by output 720- 3600 tons in a shift in mine. Coal haulage to surface is carried out by 12 belts having 1.6 - 4.3 km length. For a smoothing over un- evenness of coal flows 5 transfer bunkers to 300 tons were intro- duced. The designed conveyor system is divided into two parts (Figure 1). In the upper part some coal from Face 1 comes through belt road C, into transfer bunker 8,. From the opposite side that bun-

Jan 1, 1996

By Raj K. Singhal

Three principal activities are involved in planning and developing a surface mine. These are 1) definition of economic and technical feasibility, 2) design, procurement and construction, and 3) mining and reclamation. The last is the only activity which begins in the feasibility study and continues throughout the life of a mine. It is also the activity which depends heavily on use of computers. This paper deals with a method of selecting mining software and dwells on the recent progress, made in this area. Discussed also is the status of computerized equipment management and information systems: a microprocessor based technology applied to dispatch systems, monitoring of equipment health and performance, wireless data transmission to a centralized data processing unit, and mine- wide information and reporting system. Reference has been made to upcoming developments which offer the potential- of transforming the surface mine of the year 2000 into a "manless pit". Canadian achievements in all of these areas have been highlighted at appropriate places in the text.

Jan 1, 1989

By Thomas A. Wheeler, Robert O. Keys

The choice of the flotation reagent that suits a particular coal has become more complicated with the development of new, more efficient reagents. Frothers and conditioning reagents, in particular, have experienced a dramatic reevaluation of their role in floating various types of coals. This paper offers a better understanding of how each of the following factors contributes to the reagent selection: 1. Natural Flotability 2. Degree of Oxidation 3. Size Distribution 4. Percent Solids in Feed Slurry 5. Fluctuations in Plant Feed 6. Limitations on Froth Handling 7. Clean Coal Specifications 8. Ash Content in Feed a) discrete ashable minerals b) inherent ashable minerals 9. Water Chemistry 10. Petrographic Composition of Coal 11. Free-Swelling Index 12. Convictions of Customer The application of conditioning reagents - both promoters and emulsifiers can substantially improve the coal recovery. Some low-rank, hydrophylic coal, previously considered unfloatable can be economically recovered with the use of the proper reagent.

Jan 1, 1986

By N. Kuyucak

Acid rock drainage (ARD) resulting from the natural oxidation of sulfide mineral wastes has become a major concern to the mining industry, both during the operational period and after mine closure. ARD is generally characterized by high acidity and high concentrations of dissolved metals and sulfates. If the generation of acid cannot be prevented or controlled, it must be treated to eliminate acidity and to reduce the concentration of heavy metals and suspended solids before release to the environment. Microorganisms play an important catalytic role in the generation of ARD. Several prevention, control and treatment technologies that are based on microbiological activities have been developed. The role of microorganisms and biotechnology in the generation of ARD and their role in the methods used for prevention, control and treatment are discussed in this paper. Recently developed passive and biological treatment processes that have been implemented at mine sites are emphasized in this paper. Benefits, limitations and design criteria for passive biological processes are also presented.

Jan 1, 2000

By Donald E. Ralston, A. T. Yu, Richard P. Killmeyer, Peter Phillips, R. W. Vander Laan, John N. Murphy, John R. Messineo, John Peters

Overview Coal production in the first half of 1982 remained near the high levels begun in mid-1981. Production then fell sharply during the latter part of the year due to recession-weakened demand. Even so, 1982 coal production was estimated at 756 Mt (833.4 million st), a record high that exceeded 1980's previous production record of 752.7 Mt (829.7 million st). Though 1982 coal production was substantially below industry expectations, the attained production represented a modest achievement in view of the recession's severity. In 1982, the gross national product declined 1.8%, its worst performance in 36 years. The recession, along with mild weather, improved energy efficiency, and conservation efforts caused the nation's energy use to drop 4.1%. With the iron and steel, construction, and auto industries experiencing production declines, industrial energy use fell 10.8%. The extent to which the nation's economic slump affected coal markets in 1982 varied: • total domestic coal use declined 3.4%; • exports remained strong for most of the year; • electric utility coal use declined for the first time in 25 years; • coal use at coke plants declined by one-third; and • coal use in other industrial sectors stayed surprisingly near the 1981 level. Coal Use Domestic coal use totaled 641.8 Mt (707.5 million st) in 1982,22 .9 Mt (25.2 million st) below the 1981 level. Nearly all the decline occurred at coke plants where use dropped to 37.1 Mt (40.9 million st) in 1982 from 55.3 Mt (61 million st) in 1981. The decline in all other industrial and electric utility coal markets was only 5.3 Mt (5.8 million st). Residential and commercial coal use increased 635 kt (700,000 st) to 7.3 Mt (8.1 million st) from 6.7 Mt (7.4 million st). Power generation decreased 2.3% in 1982, the first year since 1945 that output failed to increase. The decline was due to a drop in industrial demand. Electricity sales to residential, commercial, and other nonindustrial users increased slightly. But coal's competitive position stayed strong. Power generation from oil and natural gas fell 28.9% and 11.7%, respectively. Power generation from coal declined only 0.9%. Among the primary energy sources, coal fueled 53.2% of US electric power generated in 1982, compared with 52.4% in 1981. In 1982, US steel production declined to 66.1 Mt (72.9 million st), the lowest level in 50 years and down from 109.6 Mt (120.8 million st) in 1981. The reduced steel demand forced 13 coke plants to shut down. Coal Exports Coal exports in 1982 totaled 96.4 Mt (106.3 million st), 5.7 Mt (6.3 million st) less than in 1981. Despite the worldwide recession and above normal coal stockpiles in many countries, exports were higher than many expected. This showed the relatively strong US position in international coal trade. The US continued to export near-record coal tonnages despite increasingly competitive influences. These included an improvement in Australia's labor difficulties, the return of Polish coal to Western European markets, and lower oil prices. In 1982, US port facilities were improved and expanded, and more efficient methods for scheduling foreign vessels were implemented. As a result, high volume coal shipments to US ports were routinely loaded and dispatched unhampered by bottlenecks that plagued East Coast ports in 1981. Appalachian coalfield production declined 1.4% from 1981 output and 3.9% from 1980 output. The interior region of the US showed an increase of 7.8% in production. This was primarily because of a

Jan 5, 1983

By C. G. Janes, N. Finkelstein, L. M. Jr. Johnson

In May, 1966, the General Services Administration (GSA) announced a program to encourage additional domestic production of copper in the interest of national security. Upon learning of the copper production expansion program, Duval Corporation entered into negotiations with GSA for development of the Sierrita copper-molybdenum property under the program. Agreements between the GSA and Duval Sierrita Corporation, a wholly owned subsidiary of Duval Corporation, were concluded in 1967, with the Sierrita Concentrator beginning operation in 1970 at a designed capacity of 72,000 STPD. Subsequent additions and modifications have expanded capacity to 90,000 STPD. This property, located approximately 20 miles south of Tucson, Arizona, represents an investment including working capital of about $200 million. These funds were provided from an $83 million loan from GSA, repayable in copper valued at 38 cents per pound, $48.75 million of bank loans subject to U. S. Government V- loan guarantees, and Company capital contributions. Current general operating statistics for the concentrator are listed below: Ore Grade 0.32% Cu., 0.030% Mo. Daily Tons Milled 90,000 STPD Annual Copper Production 94,600 Tons Annual Molybdenum Production 15,000,000 Lbs. Annual Silver Production 1,135,000 Ounces

Jan 1, 1976