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By M. Wickham

Design of an open pit backfill requires an understanding of highly varied processes including slope stability, hydrogeology, pit lake chemistry, climate, runoff, and mine waste behavior. Dynamic systems modeling (DSM) provides flexibility to the designers of open pit backfill, allowing them to directly integrate many different physical processes and varying levels of complexity. DSM also provides for the efficient application of uncertainty analysis to define a range of possible results, the sensitivity of the results to uncertainties in model inputs, and the value of additional data. This paper presents the results of an analysis using DSM to evaluate a pit backfill design at an Arizona mine. The objective of the partial backfill was to stabilize an active slope that threatened facilities adjacent to the pit. DSM was used, in part, to develop a pit lake water balance model for evaluating the influence of the backfill on the ability of the pit to maintain passive hydraulic containment of groundwater and surface water inflows and for evaluating costs for various backfill scenarios.

Jan 1, 2001

By K. E. Robinson

During operation of tailings impoundments, water is lost through decanting, evaporation and seepage. Techniques have been developed to regulate or control each of these components. Collectively implemented, these techniques form the basis of tailings impoundment management. Regulation of the rate and level of decanting influences the size of a free water pond, and, thereby, the amount of evaporation and seepage, which are both area-dependent. Conversely, the encouragement of seepage and/or evaporation could also be used to reduce decanting requirements. Management of one of the components of a tailings impoundment's water balance is reflected in changes in the other components. The seepage component has the greatest potential impact on the environment, and consequently requires the closest scrutiny. Water percolating through tailings backfill transports heavy metals and other dissolved solids from the impoundment into the local groundwater regime. Depending on the seepage volume and concentration of contaminants, seepage from impoundments could exceed environmentally tolerable limits. Once mobilized, seepage-borne pollution is much more difficult to treat, mainly because of the problems in collecting the diffusive transportation medium. Pollution abatement measures relative to tailings impoundment seepage depend on seepage prevention or reduction. Seepage control measures include constructing barriers to flow, pump-back systems of interception and restricting the supply of water available for seepage.

Jan 1, 1987

By John H. Gasper

The success of steep slope (>20°) contour mining depends on many factors. Most important is the selection of the mining method that best suits the premining site conditions environmentally and economically. These conditions can be divided into three categories: • Geometric conditions - machine limitations, slope stability restrictions, erosion capacity; • Physical conditions - material properties, rock strengths, ability to dig, driving surfaces; and • Chemical conditions - acid-base relationships, blending or selective placement of overburden. This article incorporates these conditions by conceptually modeling compliance-oriented contour mining methods, particularly haulback methods, using the combined front-end loader (FEL)/ truck, tractor/scraper, and FEL-truck and scraper. Engineering analyses, including machine selection, sequencing, ease of varying production rates, slope requirements (for stability and running surfaces) and drainage requirements can be performed after the geometric constraints dictated by in situ conditions and regulatory requirements have been conceptualized. Once all generalized geometries have been established, reduction to idealized, three-dimensional views is achieved. These are then reduced to two-dimensional symbolic models, mainly plan views but also elevations and sections. Equipment activities and operations are then conveniently overlayed. Without this simple, two-dimensional reduction, technology transfer remains awkward and non-analytical.

Jan 1, 1991

By M. S. Davis

The Tek Process can produce masonry products such as bricks, roof or wall tiles, and block from virtually any inorganic waste. In the process the aggregate raw materials, portland cement, water and common chemicals are first mixed together; then mechanically subjected to several thousand pound pressure per square inch. This causes a novel chemical reaction between the cement, chemicals and water; producing the "patented" Tek adhesive binder which holds the aggregate together in a stone-like mix. Simultaneously, the desired product shape is formed. The building modules can have strengths of 8000 p.s.i. (pounds per square inch) with completely sound aggregates utilizing air curing for a period of 28 days. With most aggregates, 3000 p.s.i. is achieved within 24 hours. Eventual strengths usually exceed 5000 p.s.i. with almost any raw material. Water absorption ranges from 5-7.5 percent. Both absorption and strength figures are superior to the most rigid of any and all A.S.T.M. specifications for the highest quality bricks. In most locations, the product (when brick shaped is called Tekbrik) can be produced significantly more economically than can comparable grades of clay or other bricks, be- cause almost any inorganic waste materials or pollutant can be used as a raw material. The process results in a lower manufacturing cost as compared to clay bricks; fuel cost to operate a clay kiln represents a substantial portion of the total cost. Capital expenditure for a Tek plant also is lower due to the large investment in clay kilns. Transportation savings also are important, clay brick factories must be very large because the kilns are uneconomical unless they are large. Most bricks are manufactured at the sites of clay deposits in relatively uninhabited areas. The cost of transportation to the job site represents a considerable percentage of the selling price.

Jan 1, 1974

By Ahmed M. Yousif, Walid M. Abdellah, Galal M. Abdel Wahab, Amal E. Mubark

The present work is concerned with selective dissolution of niobium from Gabal El Faliq concentrate sample by using fluoridefree process. The chemical analysis of concentrate sample revealed the presence of high amount of ZrO2, Nb2O5, Re2O3, and HfO2 assaying 33.6, 1.99, 4.8, and 1.2%w/w respectively. Several economic minerals including zircon, samarskite, fergusonite, and xenotimewere recorded in the studied sample. About 98%of Nb content was selectively dissolved at the optimumconditions of 1:2 concentrate sample: KOH weight ratio, 2.5 h fusion time, and fusion temperature of 550 °C. Organic solvent extraction process using Aliquat 336S in xylene was effectively used for preparing pure Nb2O5 (98.95%).

Oct 22, 2019

By K. E. Wood, K. J. DiRocco, L. A. Becker

The Russia Wharf segment of the Silver Line Phase II Project for the MBTA incorporated ground freezing and underpinning during New Austrian Tunneling Method(NATM) tunneling through timber pile foundations, urban fill, and abandoned wharf structures beneath two historic 7-story buildings with steel frames and masonry facades. During construction, the project team implemented an extensive program to monitor, evaluate, and mitigate the ground and building movements caused by the various construction activities. Mitigation included freeze cycling and building raising/lowering to compensate for ground movements and safely maintain the serviceability and occupancy of the buildings. In this paper, we present the history of the freeze, tunnel construction, and thaw-related movements that occurred and the building response that we observed.

Jan 1, 2005

Phelps Dodge Mining’s Bagdad, AZ copper facility uses a large series of cone crushers and ball mills to reduce copper ore to very fine particles. The solids are mixed with water to create a slurry. Milk of lime is added to this slurry to raise the pH. Small amounts of reagents are also added, including a frother to make bubbles, as well as a collector chemical that causes the copper minerals to stick to those bubbles. This material is pumped to a series of froth flotation cells to concentrate the copper. Air is blown into the flotation cell tank and the pulp mixture is vigorously agitated. Rising bubbles carry the copper particles over the edge of the flotation tank. The bubbles break after they flow over the edge.

Jan 1, 2005

By Dale S. Hursh, William A. Brooks

Introduction US dependence on external energy sources is dangerous because of unstable political situations existing in key energy exporting countries. So, recent national energy policies call for increased reliance on domestic energy sources. Coal ranks as the most feasible domestic energy source due to its abundant reserves and continental distribution. But to efficiently extract these coal reserves, huge sums of capital funds are needed. Due to the depressed economy, lenders of capital funds are forced to be more stringent with loan applications. This results in fewer loans granted. In many cases, it is uncertain if funding can be obtained. Furthermore, the greatest level of domestic mine financing is expected to be in the coal sector. Demand for capital in the domestic coal industry is anticipated to increase 80% by 1990. The Chase Manhattan Bank in New York warns that these future needs cannot be met by the present capital markets. This article analyzes the current and expected situations of the capital markets available to the domestic coal industry, including: • current and expected future types of financing used in the domestic coal industry; • problems the domestic coal industry may encounter as it seeks capital; and • the future availability of capital funds as concluded from analysis of the first two items. Background Information Regardless of industry, all projects or ventures can be divided into four basic stages: generation; evaluation; selection; and execution. Within the mining industry, one can break down these stages to draw a clear picture of mine development, as shown in Fig. 1. Each successive stage has a corresponding risk level. This risk level defines the type of financing available to the mine operator. Mining Venture Risks A coal mining venture can be characterized by its unique blend of technical and financial risk. As the mine moves through different development stages, varying proportions of each of these risks are encountered. It is these risks that the lender evaluates to determine project suitability. For a coal mining venture, the major complexities generally occur with the technical risk. These include: • quantifying the coal reserves: • assessing the feasibility of the mining method; and • evaluating the design of the wash plant. The reserve risk is gauged by the amount of measured, mineable, and saleable reserves. The greater the latter amounts, the lower the risk. Secure title to the reserves plus title for any surface areas required are also of concern to the banker. Feasibility of the mining method and evaluation of the wash plant design should verify that the project can be completed according to the engineered spec-

Jan 9, 1982

By T. B. Thompson

The Leadville District has been a prominent metal producer since its discovery in 1860. Veins and replacement bodies both have contributed to district production. The latter have been the major metal sources and are hosted within the Paleozoic Leadville, Dyer, and Manitou Dolomites. Igneous bodies representing eight separate events cut the sedimentary section. The main intrusive complex within the district occurs in the Breece Hill area and was the thermal center about which the vein and replacement ores exhibit mineralogical zoning. Precious metal-pyrite-quartz veins (quartz Th= 422 to 469°C; salinity < 4.2 wt. percent eNaCI) occur within or peripheral to the Breece Hill Intrusive Complex, whereas base metal veins and replacement bodies extend from the complex margins outward as much as 2 mi. Pre-ore and post-ore igneous bodies occur, but Fragmental Porphyry dikes immediately post-date the ore event. The Fragmental Porphyry grades downward from a heterolithic breccia with rock-flour matrix to one with a dark, glassy, sulfide- and phenocryst-bearing matrix, commonly with quartz-feldspar porphyry selvages on the dike. Two types of replacement bodies are recognized in the district: 1) the Leadville-type (LTM), massive sulfide (> 60% sulfides) bodies with recoverable Zn, Pb, Ag, and Au, and 2) the Sherman-type (STM), sulfide bodies (low total sulfide) with barite, galena, sphalerite, argentian tetra.hedrite, and minor pyrite. The latter type occurs only within the Leadville Dolomite and is found throughout the Mosquito Range and extending into the Alma District. The Leadville-type replacement bodies are zoned with a pyritic margin and base metal core. Wallrock alteration and trace Pb-Zn dispersion are strongly developed in igneous wallrocks but are weakly developed in carbonate wallrocks. Cu:Zn, Ag:Zn, and Au:Fe ratios increase outward from the center to the margins of LTM. Some of the sulfide bodies are localized on earlier-formed magnetite skarns. Pyrrhotite, pyrite, and marcasite are the earliest formed sulfide phases while chalcopyrite, marmatite, and galena developed later. Tetrahedrite and electrum occur in vugs and fine veinlets cutting the sulfides. Late-stage barite, dolomite, and fluorite occur as minor phases. Pressure-corrected Th for quartz (375-410°C), sphalerite (374-387°C), barite (320-360°C), and dolomite (310-314°C) fluid inclusions with salinities < 5.2 wt. percent eNaCI characterize the fluid responsible for the formation of the Leadville-type orebodies. These values clearly demonstrate the high temperature and low salinity of the ore fluids. Sulfur isotope analyses for galena and barite from LTM are - 1.9 to + 0.9%o and 7.8%o, respectively. Proximity to feeder veins and favorable dolomite hosts are the principal controls on ore localization. The Sherman-type bodies are not internally zoned but commonly have host rock silicification near the orebody margin or in the footwall rocks adjacent to fluid flowpaths along faults. Early quartz, pyrite, dolomite, and white barite precede base metal-silver minerals which are followed by late quartz and golden barite. It is not clear whether the early quartz and the late quartz and barite are part of the STM-forming process. Fluid inclusion analyses yield trapping temperatures as follows: early quartz, 316-341 °C; barite, 264-347°C; low-iron sphalerite, 215-265°C; and late quartz, 260-278°C. All inclusion fluids have salinities < 8.1 wt. percent eNaCI. Sulfur isotope values for barite and galena from STM range from 13.2 to 24.00/00 (avg: 18.4%o) and -6.8 to -3.8%o (avg: -5.5o/00), respectively. A hydrothermal fluid d34SSS of about 15%o is needed in order for galena and barite in equilibrium to exhibit the observed sulfur isotope compositions. Equilibrium sulfur isotope fractionation between barite and galena indicates a 300°C temperature of deposition. Two separate hydrothermal events appear to have taken place to form the distinctive Leadville-type orebodies and those of the Sherman-type assemblage. The STM is known to be older than the LTM. The latter is likely mid-Tertiary in age, post-dating emplacement of the Johnson Gulch Porphyry. LTM is clearly related to meteoric leaching of sulfur and lead (and other metals) from the upper portions of the Breece Hill Stock. Fluids were transmitted along faults, bedding planes, and contacts, and cooled away from the intrusive complex. Early ore fluids were weakly acidic and developed argillic assemblages in the igneous rocks adjacent to the fluid conduits. Reaction/replacement of carbonate rocks occurred where fluids encountered dolomite, but rapid neutralization prevented any wide-spread alteration beyond the ore-carbonate host contact. Pressures based on sphalerite geobarometry and stratigraphic reconstruction were 1.0-1.2 Kb. The high temperatures of vein and replacement ore fluids indicate that chloride complexing was more effective in metal transport than bisulfide complexes. Cooling, dilution of ore fluids, and reaction with carbonate rocks were the major factors in LTM ore deposition. STM formed over wide expanses of the Leadville Dolomite terrain adjacent to (and possibly capping) the Sawatch uplift. Sedimentary sulfur was derived from Pennsylvanian evaporite-bearing sequences adjacent to the uplift. Ore leads are strongly radiogenic (J-type) and are compatible with a crustal-leaching model. Temperatures of ore formation are higher, and ore-fluid salinities are lower than Mississippi Valley-type ore fluids. Superimposed upon dark-gray, diagenetic Leadville Dolomite are several stages of hydrothermal dolomite regionally distributed astride intrusive centers of the Colorado Mineral Belt. The presence of these later dolomites argues for dolomitization and later ore deposition in response to an abnormal thermal gradient caused by emplacement of Laramide batholiths and their generation of convective flow of meteoric fluids.

Jan 1, 2013

By Ramon B. Santos

The Atlas Concentrator, reputedly the largest in the Far East today, is located on the island of Cebu in the Republic of the Philippines. It started operation on a 4000 TPD capacity in 1955. An expansion program, coupled with significant improvements both in the Crushing Plant and the Mil, made the Atlas Concentrator what it is today, treating about 14,000 tons of ore per day at a comparatively low cost of about $0.50 per ton treated. The Atlas Copper Mine is at present mainly an open pit operation, with ore supplied from two pits (Lutopan and Biga) north of the Concen¬trator. Development of an Underground Mine, situated on the main ore body at Lutopan, which will be a block caving operation, has been underway since 1963, and this underground mining operation is expected to b e in full production by the latter part of 1966.

Jan 1, 1966

By B. Comley, M. C. Harris

There is as yet no accepted method of predicting flotation frother performance in plant processes based on laboratory scale characterisation techniques. This paper investigates the use of dynamic surface tension, using the maximum bubble pressure method, as a means of evaluating frothers and frother mixtures. An adsorption model is presented, which has been used to quantify the role of frother type and concentration during frother bubble interaction, based on the correlation of model parameters to physical frother characteristics. This approach was found to provide useful insight with respect to blending and selection of flotation frothers to meet specified flotation performance criteria.

Jan 1, 2001

By P. A. C. De Ruiter

The Lower Cretaceous salt deposits of the Gabon Basin and Congo Basin were said down on ton of an Burly Cretaceous Lato Jurassic, continental graben fill that represent!) the rifting phase of the Afro-American continent. The salt 13 characterized by high percentages of potash and magnesium salts and the scarcity of sulphates and carbonates. The salt probably originated from a brine that was already enriched in high-soluble salts before entering the Gabon Congo basins. Their low-solubility equivalents are found in the Cuanza Basin of Angola. Commercial mining of the potash salt is only possible in those onshore areas where it is essentially undisturbed, shallow and of the right chemical composition. These conditions are net in Congo where the Holle mine produces from rich sylvinite deposits.

Jan 1, 1978

By John Drew Ridge

Recent work by Haas has made available information on densities and vapor pressures of solutions of differing salinities at temperatures up to 330°C. From these data it is possible to predict the behavior of volcanic exhalations of various degrees of salinity as they approach the sea floor. Particular attention is devoted to solutions of 5.0 weight per cent NaCl and 20 weight per cent NaCl, two fluids that approximate quite closely the salinities of what Roedder termed: (1) normal hydrothermal fluids and (2) fluids typical of stratiform deposits of low-temperature conditions of origin. It is apparent that solutions above 220-230°C. cannot reach a sea floor on which the depth of water is 600 feet or less in the liquid state but will boil at some appreciable depth beneath the sea floor. Such boiling would result in the precipitation of all constituents of the ore fluids of significantly lower vapor pressure than water. The principal such constituent would be salt, and no sulfide deposits, the major constituent of which is salt are known. It follows, therefore, that ore fluids probably never get close to the sea floor of shallow seas at temperatures high enough to permit boiling. Ore fluids significantly above 230°C. can reach the sea floor in the fluid state only if the depth of the sea in the area. in question is well above 600 feet, for example, solutions at temperatures of ±300°C. reach the sea floor in the liquid state only if the depth of sea water is slightly over 3000 feet. Ore fluids reaching the sea floor at such depths may be the parents of such fluids as the Red and Salton Sea brines. On the basis of these data, the Cyprus and Kuroko deposits are discussed.

Jan 1, 1973

By Yung Sam Kim

The study of ultrasonic-wave propagation in substances has been remarkably advanced in recent years in most engineering and science fields. The main object in studying the velocity of ultrasonic-wave propagation in solids, is to determine dynamic properties of these materials. The present paper, however, presents some other possible applications of ultrasonic-wave propagation in the study of rock mechanics as follows: Investigation of the mechanism of microseismic activites of geologic materials, (a) at initial or low stress level, (b) at final or fracture stress level, and (c) under fatigue loading condition. Also, correlations among stress level, density, and the velocity of ultrasonic-wave propagation in rocks are discussed in this paper.

Jan 1, 1973

By Reginald Dias

Mining equipment life may be extended through preventive maintenance and the proper application of quality lubricants. There are several practices mine operators should consider implementing to preserve their equipment. An exercise in review — Begin by reviewing original equipment manufacturer (OEM) recommendations regarding servicing and maintenance intervals for each part of the equipment, especially the engine. And the verdict is — If the manufacturer’s recommendations have been followed, good. If not, owners/operators should begin periodic service work on equipment, to help minimize equipment downtime and extend engine life.

Jan 1, 2004

By Johann Steynberg

The design and construction of a Concentrator based on initial pilot plant work is rarely perfect. Palabora&apos;s plant was no exception although the basic objective to produce copper in a safely conservative manner was certainly achieved in a profitable manner. identification of the metallurgical and mechanical deficiencies of the plant through operating experience and a better concept of the minerology of the orebody enabled the development of a more efficient process both in terms of the metallurgical performance and cost effectiveness. To maintain and improve this level of efficiency, continuous inspection and revision of the plant metallurgy and engineering standards is required. In this presentation a few of the investigations and changes are described: 1.0 Alternative methods to restrict and eliminate the detrimental effect of critical size material on the performance of an autogenous mill. 2.0 An analysis of the environmental condi¬tions in Palabora&apos;s grinding circuit and the introduction of high chrome balls as grinding media. 3.0 The role of magnetite in the beneficiation process at Palabora. 1.0 Alternative methods to restrict and eliminate the detrimental effect of critical size material on the performance of an autogenous mill.

Jan 1, 1985

By P. A. Hagerty

Biological treatment of metals-impacted water using sulfate reduction is a viable means of treatment that has been applied in pilot and full scale at numerous projects. One of the fundamental challenges with this type of treatment is the selection of an appropriate substrate to support the sulfate reduction process long-term. The substrate degradation products provide a carbon source and an electron donor for metabolism by sulfate-reducing bacteria and consequently organic characteristics are critical; however, the physical attributes of the substrate are equally critical to an efficient and optimized substrate mix. This paper explores the affect of particle size (a.k.a. grain size) of several substrate mixes on the treatment efficiency of sulfate reducing treatment systems. Substrate selection can be separated into two phases of evaluation, the primary selection phase and the secondary optimization phase. The primary selection phase considers such fundamental attributes as source availability, economics, bioavailability and longevity. These fundamental activities are conducted in order to identify potential candidate ingredients of the substrate mix which are regionally available, economically viable and consistent with the biogeochemical aspects of the project. Recent work has been conducted in the development of testing protocol for organic substrates to quantify bioavailability (Martinez Hernandez et al. 2010, Place et al. 2006) as part of the primary selection phase. Once the substrate ingredients have been selected based on the primary criteria, the mixture of these ingredients is then developed based on an optimization process, including consideration of the substrate ingredient?s particle size distribution.

Jan 1, 2011

By H. L. Lovall

Huge banks of preparation plant refuse and other non¬saleable materials have accumulated over the years in all major United States coal producing areas. These banks, esthetically and commercially undesirable, can cause air and water pollution and land reclamation and mineral conservation problems for the industry and nearby communities Although some refuse banks have been reworked to recover saleable coal, all remain and accumulation continues. Even those previously processed continue as potential hazards. Among the several problems created by refuse banks, in situ combustion is most treacherous. Of the millions of tons of major accumulations, there are at least 450 refuse banks on, fire at this time Attempts to extinguish such fires are costly, impractical and generally unfruitful. Studies are in progress to evaluate the potential of processing such materials to eliminate the combustion capability and to yield usable fuel and nonfuel products. Aspects of the study now in. development for coal refuse include: (a) evaluation of characteristics (size, sink-float, ash, sulfur and calorific value) of the coal refuse materials which are known to be highly variable, (b) development of an ignition test having significance for in situ conditions, (c) study of processing capabilities (comminution for liberation, pilot plant washing tests), and (d) investigation of potentially significant properties of fuel and nonfuel products which could be altered to enhance their market potential.. Among the latter products are lightweight aggregate, fill for mine slushing operations, construction, etc: Plans are to extend the studies to include the design, erection, and test processing of refuse with a transportable plant,; which could provide basic economic and product utilization data from several locations

Jan 1, 1964

By Y. J. Wang

This paper deals with the application of linear programming to the solution of mine ventilation network problems which involve only the controlled splitting of air. An airway whose air quantity is to be controlled to a prescribed value is called a "fixed-quantity" airway. In a network where the fixed-quantity airways are increased in number and are distributed such that the air quantities for the remaining airways are uniquely determined by Kirchhoff&apos;s first law, the problem reduces to determining the head losses and locations for air regulators and fans. This is one of the network problems encountered most often in underground coal mines. By formulating Kirchhoff&apos;s second law as a set of linear constraints and the total air horsepower supplied by fans as a linear objective function which is to be minimized, the problem is analyzed through the technique of linear programming. Some important properties of the problem are discussed and examples are presented.

Jan 1, 1971

By Francis J. Quinn

The Natural Gas Act, of 1938, which put interstate pipelines under the jurisdiction of the Federal Power Commission, did not place a protective competitive shield around such companies - nor does any provision of the act guarantee them a profit. Natural-gas pipelines are competitive with each other and also with the coal and oil industries. Gas distributing companies must compete not only with the coal and oil industries, but also with the electric industry. Natural gas has captured markets from oil, which had taken them from coal. Oil men contend that gas prices have: been, held to an artifically low level by regulation. The electric industry is moving into the space-heating market, which pleases the coal people because the coal industry&apos;s largest customer since losing the railroads to dieselization has been the electric companies. The coal industry is attempting to monopolize the industrial and electric generating market through government intervention, and this is being done under the guise of concern for the national welfare through advocation of a "National Fuels Policy purporting to, further the cause of fuel conservation. Such a policy is contrary to American principles and would result in the individual&apos;s loss of freedom of choice and ultimately, in less reserves of preferred fuels because of diminished exploration efforts.

Jan 1, 1961