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By Thomas Marcher

Stanford Linear Accelerator Center (SLAC) is located in Menlo Park, CA. In order to allow for enhanced experiments, the current facilities required expansion. Tunnels were excavated through very weak sedimentary rock interspersed with uncemented zones (Ladera Sandstone) employing the principles of the NATM. The overburden var-ied from 10 to 80 feet. The paper addresses the characterization of Ladera Sandstone that can exhibit the properties of dense sand and weak rock. The paper focuses on the challenges that were encountered during the NATM initial support design and the construction phase including the geotechnical instrumentation, monitoring and design verification process in particular the excavation of the junction between access tunnel and the FEH cavern (49 ft wide by 32 ft high).

By Steve Kral

Competition from foreign coal producers could displace as much as 9 Mt/a (10 million stpy) of US coal bound for power plants located near waterways. But, according to a Maryland-based coal consultant, it could be worse. Theoretically, about 52 Mt (57 million st) of domestic coal could be vulnerable to imports by 1990, said Forrest Hill, of Hill & Associates of Annapolis. Hill was speaking to about 150 coal industry executives and experts at the third annual Coal Marketing Strategies Conference in November. Most were at the Denver, CO conference to pick up tips on how to sell coal in an oversupplied market. Imports threaten domestic markets Of the 200 utilities studied by Hill and his staff, 119 are situated near major waterways, he said. However, most of those waterways are not equipped to handle coal from the shipping lanes. Good news for US coal producers. But don't breathe too easily. Foreign coal still poses a major threat to domestic markets, Hill continued. The strength of the US dollar is an obvious factor. But easy access to US utilities located on waterways combined with low rates for ocean vessels give foreign producers another edge. And foreign mines are typically low cost producers. For example, Hill said Colombia's huge Cerrejon mine can deliver coal to an Illinois power plant for $47.87/t ($43.39 per st). That compares to $52.85/t ($47.95 per st) from a Kentucky coal mine. Also, Colombian coal producers can generate a cash flow even if the coal sells for $27.50/t ($25 per st). The main competition US producers face from abroad, as Hill sees it, comes from Australia, Canada, Colombia, Poland, South Africa, and, perhaps, from Venezuela. Domestic producers, however, do have some things going for them. Most US coal buyers, Hill said, "are not wild about the idea of buying foreign coal." A 10% price advantage or pressure from public utility commissions would be needed to force some of them to buy foreign coal, he said. Some of the utilities contacted said they would not commit to more than one-third of their stockpiles to a foreign source. Another advantage for US producers is that they have room in their long-term contracts to cut prices and still maintain a profit, Hill said. Railroads, too, have high profit margins written into their rate structures. They are also aware of the import threat. Therefore, they may reduce their rates accordingly to keep their markets. Marketing's role The energy price shocks of 1972 and 1976 caused major adjustments in world economics. Coal was no exception. High oil prices caused many utilities to look at less expensive coal. As the market improved, coal prices began to respond, said R. Gale Daniel, of Anaconda Minerals Co. But clean air legislation and the strengthening dollar caused havoc in the coal markets, he said. The price of oil crashed, taking with it predictions of record coal use. The result is an oversupply of coal that has led to price cutting. Now, coal marketing must be recognized in its "true leadership role," Daniel said. Marketing people must know when to use spot sales to balance production objectives and maintain cost-effective-

Jan 1, 1986

By S. Atallah

A survey was conducted relating to the current practices for the classification of hazardous locations in coal preparation plants. Several plants processing bituminous, anthracite and lignite coal in Pennsylvania, West Virginia, North Dakota, Colorado, Montana and Wyoming were visited. Coal preparation plant operations and designers as well as MESA inspectors were interviewed. The National Electrical Code was discussed with selected members of the NFPA committee and electrical equipment manufacturers. Data provided by MESA on fire and explosion accidents in coal preparation plants were examined. The requirements of the pertinent Federal Regulations, National Electrical Code, National Electrical Manufacturers Association and Underwriters' Laboratories were compared and evaluated. This report consists of two parts. Part I: "Analysis and Review" provides a summary of the findings. Part II: "Recommended Guidelines" consists of recommended uniform guidelines that may be used for interpreting the National Electrical Code as it applies to the classification of hazardous areas in coal preparation plants.

Jan 1, 1977

By Edgar A. Peña

El presente trabajo describe el plan de minado del yacimiento de Cuajone a través de las leyes de corte variable y stock dinámicos con el fin de maximizar el valor presente neto a largo plazo. La estrategia de leyes de corte variables consiste en seleccionar material desde una ley superior a la ley de corte de equilibrio del plan. Luego, el material de alta ley es llevado directamente a la planta, que al ser extraído anticipadamente, genera un mayor valor para el negocio, al tiempo que aprovecha el costo de oportunidad. De otro lado, el mineral restante que haya sido extraído es llevado a depósitos de almacenamiento (stocks dinámicos). Como consecuencia, esta estrategia permite realizar una mejor toma de decisiones que se ajuste más a la realidad de cada periodo, logrando aprovechar al máximo los periodos de alza de precio de los metales, así como poder incrementar la producción de concentrado en periodo de depresión de los precios.

Sep 12, 2011

By Lawrence A. Engel

The idea of using apron feeders for in directly feeding crushers is not a new one, it has been used for many years. To the best of our knowledge, the first apron feeder was used for bulk material handling in 1893. Since that time many design innovations have been introduced, with perhaps the most effective one being, the application of crawler tractor components in the feeder construction. This design was first introduced to the mining industry in 1954 by, national iron company. These feeders were used in the handling of run-of-mine iron ore on the Minnesota iron range, at the rate of 1,000 ltph. The material was fed over a grizzly to a jaw type of crusher. The crusher output was also handled by an apron feeder. Today, the apron feeder is being used in hard rock surface mine operations feeding crushers at rates of 5,500 ltph and over.

Jan 1, 1983

By James J. Tansey

A Deep Foundations Institute meeting with the University of Michigan at Ann Arbor in March of 1984 featured legal rights under Differing Site Conditions. A workshop conducted by the authors and Gerard Ittig, Esq. added to the value of the symposium. This paper will be of interest to your attorneys in any subsurface disputes.

Jan 1, 1985

By Raffaella Granata

The paper deals with the remediation of two areas formerly utilized for the disposal of hazardous wastes in a petrochemical plant. The works, designed on the basis of the criteria of maximum safety and minimum environmental impact, consisted in the confinement of the contaminated soil and groundwater within surface caps and perimetrical cut-off walls embedded in the underlying clay layer. The cut-off wall is 0.8 m thick and has a maximum depth of 33 m: it was designed to guarantee, as a minimum, the level of safety for a landfill for hazardous wastes, in accordance with the applicable National Standards. It was constructed with self-hardening mud and with the installation of an HDPE geomembrane. The HDPE liner of the cut-off wall was then sealed to that of the capping to obtain the complete encapsulation of the contaminated soil. A system of piezometers allows the monitoring of the cut-off efficiency measuring the fluctuations of the groundwater table and testing the chemical contents. Some wells installed within the contaminated areas will contribute to guarantee the full efficiency of the system in case of state of emergency, controlling the water-table level inside the confined areas.

Jan 1, 2006

By J. D. Morgan

Demand for nonfuel minerals depends on the overall state of the economy, which steadily improved each quarter in 1984. New housing starts rose to 1.8 million units. Automakers turned out about 15% more cars (7.8 million) and 30% more trucks (3.1 million) than in 1983. Nevertheless, many domestic mineral operations experienced difficulties in 1984. This resulted from import competition greater use of newer engineered materials, emphasis on multi-unit housing and downsizing of motor vehicles. About 15% of our energy was imported. This in cluded $36 billion worth of crude oil and $22 billion in refined products This added significantly to the overall merchandise trade deficit of $12; billion. On the bright side for mining, coal production rose 14% to 810 Mt (890 mil lion st). Three-fourths o: the coal was burned to generate electricity and more than half of our electricity was derived from coal-burning plants. With the exception of a few large-bulk, low-value raw minerals, most minerals move relatively freely in world trade. The strong dollar encouraged imports and made exporting more difficult. Consequently, our nonfuel minerals trade deficit rose 60% to $19 billion, reflecting imports of $39 billion and exports of $20 billion. There were increased pressures from some major segments of the minerals industry for some form of import protection. But President Reagan said, "Our goal is a system of free and fair trade in goods, services, and capital. We will work toward this goal through both bilateral and multilateral trading agreements." The US minerals industry consists of domestic mines, concentrators, smelters, refineries, mineral manufacturing plants, and recyclers. It also includes many wholly- or partially-owned operations in many parts of the world, providing employment and income for US citizens and others as well. Compared with 1983, the value of US raw nonfuel mineral output rose 8%, to $23 billion. The $253 billion worth of goods processed from this crude mineral output was a 14% increase. Major Metals Raw steel production - a major indicator of both material use and mineral production-rose 10%, to 84 Mt (93 million st). This stimulated a 36% rise in domestic iron ore production, to 52 Mt (57 million st), about 98% pelletized. Iron ore imports rose 44%, to 14 Mt (15 million st). Despite the increase of steel production, output remained well below levels of just a few years ago. For example, 1984 production was still 23% less than in 1981. Raw steelmaking capacity remained steady at 122 Mt (135 million st). The industry continued to cite steel imports as a major reason for low domestic capacity. In December, pacts with seven leading steel exporting nations were announced. This is an effort to reduce import penetration to about 18.5% of the domestic market. Domestic producers of bulk ferroalloys of chromium, manganese, and silicon operated at about 50% capacity. The US mined no manganese or chromium. Only a small quantity of ferronickel was produced from domestic laterite mining in Oregon. Molybdenum production, at 45 kt (49,500 st), rose threefold. Mine shipments of tungsten, another mineral tied to steel

Jan 5, 1985

By A. Basçetin

Equipment selection in mining engineering is one of the most important decisions that affects the mine design, production planning and economic parameters in open pit and underground mining. Mine planning engineers generally use their intuition and experiences in decision making. Mostly, linguistic variables (the weather is raining, soil is wet, etc.) come into question and decision-makers may not know how these variables are computed. Since the advent of the fuzzy set theory, these uncertainties are easily interpreted in the decision-making process. The development of computer technology and programming of colloquial language with expert systems have considerably reduced decision-makers? burden. This paper reviews the development of a computer programme software called EQS (EQuipment Selection) that automates equipment selection in mining engineering using fuzzy set theory. The EQS with an introduction of the concepts and theories of multiple attribute decision-making, the fuzzy set theory, and EQS applications to mining industry problems with case studies are presented

Jan 1, 2006

By Val E. Payne

Issues between resource utilization and resource preservation often develop in connection with coal mining. One such conflict exists in eastern Utah where PacifiCorp and Energy West Mining Company are working with State and Federal agencies to address the resource recovery/resource preservation dispute. The effects of underground longwall coal mining on golden eagle (Aquila chrysaetos) cliff nesting sites have been studied at the Cottonwood Mine since 1986. Subsidence, escarpment spalling, and the nesting activities of the local eagle population were monitored.

Jan 1, 1986

By Paul D. Klipfel

Introduction Mineral exploration interest, principally for gold, in the south-western Pacific has surged to new proportions. This is primarily due to the application of epithermal exploration concepts in the Australian-Oceana region. Other factors that have contributed to the high level of exploration interest include governmental policies supportive of mineral exploration, along with relative ease of tenure access and a relatively short bureaucratic process. This paper highlights exploration and development activities in the North Island of New Zealand, Fiji, Vanuatu, the Solomon Islands, and Papua New Guinea (Fig. 1). It provides a framework to understand the overall recent enthusiasm that has been brought to the south Pacific by explorationists. Through these recent developments, it is clear that the south Pacific region will become a significant gold producing area and thereby worthy of attention and study. Papua New Guinea alone is the free world's seventh largest producer (Table 1). And, with the addition of production from deposits presently being developed, this status is likely to be raised. History Gold was first noted on various Pacific islands in the late 1500s by Spanish explorers. They thought they had reached the legendary King Solomon mines. Since then, the history of prospecting in the southwest Pacific has coincided with the colonization of the region. Settlers in New Zealand extensively mined alluvial and lode gold deposits starting in the 1850s. The spread of European colonization to the more remote Pacific islands from 1880-1940 was accompanied by varying degrees of prospecting activity by planters, traders, and settlers. Some were successful, others may have been successful, but never returned due to hostile indigenous peoples or disease. In general, records of such prospecting activity are meager and exploration leads are, in some cases, gained through local village folk memory. Most early discoveries were alluvial finds. These led to placer operations, particularly in New Zealand, the Solomon Islands, and Papua New Guinea. Continued prospecting located lode deposits such as the Morobe Gold-field of Papua New Guinea, the Coromandel Peninsula of New Zealand, and the Emperor of Fiji. Some areas were prospected thoroughly. Yet others, such as Vanuatu, remained relatively unexplored until the present exploration surge began. During World War II, interest in minerals was diverted. It was renewed significantly until the middle 1960s and early 1970s when regional porphyry copper exploration was conducted.

Jan 10, 1987

By S. Panigrahi

The SO2-ammoniacal ammonium sulfate leach liquor generated by leaching of manganese nodules, after removal of minor quantities of iron and manganese, contained copper, nickel, cobalt, zinc and (NH4)2SO4. After extraction of copper from the leach liquor with LIX 84I, stripping of ammonia from the Cu-barren raffinate was carried out followed by precipitation of metal ions from the ammonia-stripped solution as sulfides. Leaching of the sulfide precipitate was carried out with H2SO4 to obtain a leach liquor containing 0.58 kg/m3 Cu, 2.67 kg/m3 Zn, 2.00 kg/m3 Co, 24.68 kg/m3 Ni and 10.0 kg/m3 (NH4)2SO4. After extraction of copper and zinc from the sulfate leach liquor with LIX 84I and D2EHPA, respectively, the solution was left with Co and Ni. Extraction of cobalt from the Cu- and Zn-free solution was carried out with 0.1 M PC88A and stripping of the cobalt-loaded organic was carried out with the cobalt-spent electrolyte (pH 1.4). Extraction of nickel from the cobalt-free solution was carried out with 90% neutral 1M NaPC88A followed by stripping of the nickel-loaded organic with 120 kg/m3 H2SO4 solution. Extraction of metal ions increased with increasing equilibrium pH and extractant concentration. The maximum separation factors, with respect to the pH and extractant concentration variation studies, were 3796.7 and 15350.0, respectively. The extracted species for the metal ions were CoA2?3HA and NiA2?5HA.

Jan 1, 2009

By Paul W. Cleary

Keywords: Reactive pellets, CFD, Lagrangian SPH, Pyrometallurgy In several pyrometallurgical processes, reactive pellets are added to a melt. Heat is transferred to the pellets and reaction products such as gases, metal and slag are formed. For many pyrometallurgical processes traditional grid based CFD methods, such as using the Finite Element Method (FEM) and Finite Volume (or Control Volume methods), produce suitable predictions. However, the inclusion of solids in the bath represents significant challenges for these methods. Smoothed Particle Hydrodynamics (SPH), a Lagrangian simulation method, is able to simulate both the fluid component of the bath and any immersed solid materials, tracking the motion of these solids, and their interaction with the fluid, including gas generation. In this paper, we will summarize the key aspects of the SPH method and will show a series of structured examples illustrating the behavior of the different physics sub-systems that are used in the model of the overall system.

Jan 1, 2005

By J. B. Clark

In multiphase ternary diffusion studies, plots of the variation bf the composition on the isotherm constitutes one of the most effective methods of presenting experimental results, especially if such plots are made in a manner which relates the composition path on the isotherm with the diffusion layer structure in the couple. Unfortunately, if different conventions for plotting are used serious misinterpretations occur readily, causing apparent disagreement between investigators who actually share the same viewpoint. A common convention for mapping these diffusion paths is needed at this time because with the increasing use of the electron-probe X-ray microanalyzer, a much greater number of ternary diffusion studies can be expected in the near future. In an effort to prevent unnecessary confusion in the future litera- ture, a convention for these plots is proposed, as outlined below. A hypothetical example of the use of these conventions is given in Fig. 1 where the path of composition through the diffusion structure of the 100 pct A/50 pct B, 50 pct C couple is plotted on the appropriate isotherm of the ABC system. The lower case letters relate the region in the diffusion layer structure to the appropriate composition on the ternary isotherm. 1) The diffusion path is plotted on the isothermal section corresponding to the diffusion temperature of the couple. 2) The terminal compositions of the plotted diffusion path are the initial compositions of the couple halves—provided infinite boundary conditions are maintained. If, in either couple half, infinite conditions are not maintained, then the path terminates at the composition of the exterior surface of the couple. If, at this surface, the composition varies with time or if the plotted path is time dependent, then the diffusion time should be noted beside the plotted path. 3) A solid line crossing a single phase field (e.g., line a-b in Fig. 1) denotes an existing layer of that phase in the diffused couple. 4) A dashed line crossing a two-phase field parallel to the tie lines (e.g., line g-h) represents an interface between the two phases with interfacial compositions designated by the ends of the tie-line. The line represents no spatial extent. 5) A solid line crossing a two-phase field so as to cut tie lines (e.g., line b-c or line j-k) represents a locally equilibrated columnar two-phase layer. The solid line should cut those tie lines which correspond to the lateral interfacial equilibria along the columnar

Jan 1, 1963

By H. Guo

There are a number of methods available for the determination of the fracture toughness of rock. Some of the most recognised methods include the hollow pressured cylinder, the short-rod, the chevron - edge-notched round bar in bending and the disc-shaped compact specimen. Most of these tests are difficult and expensive to conduct. In this paper the simple Brazilian testing of discs for tensile strength has been used to determine their fracture toughness. Tests were conducted on six different rock types and the values of the fracture toughness obtained for each type are in close agreement with the results of the well recognised the chevron edged types. Details of the tests, and analytical validation of the technique, are presented

Jan 1, 1992

By G. A. Van Wielingen

"The conditioning of natural gas to meet contract pipeline specifications involves in the majority of cases in Western Canada, the appropriation of substantial capital expenditures for treating and processing installations. It is therefore of vital importance to the owners and producers of natural gas to arrive at an appreciation of the economics pertaining to the production and surface handling of their gas reserves at the earliest possible stage of field development. The treating and processing of natural gas often results in considerable changes in composition and related physical characteristics between the wellhead and the point of delivery of the saleable gas. This paper presents a general outline of engineering calculations which can be applied in the pre-determination of the effects that surface handling of gas will have on the composition and physical characteristics of sale-able gas. Emphasis has been placed on the calculation of hydrocarbon dew-points, heating values and shrinkages prevailing at the various stages in the surface handling of natural gas. It is believed that advance information indicating the approximate ranges of these physical properties will facilitate process selection and will provide a basis for the estimation of capital and operating costs of process installations."

Jan 1, 1960

By P Cameron

MetPlant conferences have focused on ensuring mining projects are well designed then optimised to operate safely and effectively at the top end of world’s best practice to ensure shareholders are not just happy but delighted. This assumes the MetPlant was built right the first time. However, reality is, too often Plant Metallurgists (PlantMets) find after commissioning they are faced with the expensive task of correcting errors or modifying shortcomings to achieve product quality at name-plate capacity, i.e. get it right the second time. Why do companies spend good money to engineer an excellent feasibility study then allow “wise men” remote from the project team to impose cuts in budget and schedule, often under the guise of value engineering? Since mining is full of uncertainties, such actions can increase the risks of failure with the result that some MetPlants do not work well. Can PlantMets influence the remote wise men who often are also imposing the rules for lending and the required returns to appreciate the uncertainties of mining and their associated risks then let the project team get it right the first time? PlantMets can negotiate with the wise men from the outset of the project and bring them into an outer layer of the team where they can understand the risks then share responsibility and accountability to achieve the common goal of building a MetPlant which works well the first time and deliver the forecast profits. Since shareholders are not in the business to make losses they appoint a Board of Directors to deliver the best outcomes for the shareholders. Thus the Board should seek effective advice on the risk reward implications from the PlantMet before making their decisions.CITATION:Cameron, P, 2015. Do all metplants work well? PlantMets can ensure they do, in Proceedings MetPlant 2015, pp 2–9 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Filip Rochette, Yvan De Busscher

Extraction of minerals can be achieved by a variety of technologies; one of them is ion exchange. There are several ion exchange configurations and mechanical set-ups available, but only one technology will provide more process performance and flexibility compared to the other. The multiple column Continuous Countercurrent Ion Exchange (CCIX) technology provides the highest form of process flexibility with also the highest mineral recovery feasible through ion exchange. In comparison with a fixed bed system, the PuriTech CCIX system offers the benefits of continuous counter-current contact mode. This way the resin capacity is fully exploited leading to reduction in resin inventory and, at the same time, in chemicals and water consumption, and product dilution. For any set of operating conditions the mass transfer zone has a characteristic length (MTZL). The MTZL can be expressed in duration, column length, or volume, but is the measure of the quantity of resin in the system that is doing "work" at any given moment in the process. The objective of continuous ion exchange processing is to eliminate all resin volume from the process equipment that is not within a mass transfer zone. In most commercial ion exchange processes for the recovery of metals, CCIX engineering can eliminate as much as 20 - 80 % of the ion exchange resin inventory. Consumptions of water and chemicals are typically brought down around 40% or more. For each type of resin the selectivity/affinity towards a particular metal depends on the basic process conditions such as pH, concentrations of other competing metals in solution. By changing the pH in the ion exchange process phase, the selectivity of the resin can be changed. By doing this, a split elution, or extraction of metals separately can be achieved and the effect of other competing metals (cross-contamination) can be reduced. For example the DOW resin XUS43578 is commonly used for the recovery of copper or nickel/cobalt separation.

Jan 1, 2016

THE ore treated is almost pure copper pyrites (chalcopyrite) in a gangue of quartz and quartz-felsite. Very little free iron sulphide (pyrite) occurs, and at the time of the erection of the flotation plant the stopes in the oxidized zone had been almostentirely depleted. This zone only extends to a shallow depth, and, below the l00-ft. level, the sulphide for the most part is clean and bright but in the crushed and brecciated parts of the ore channel, where surface water has circulated freely, the gangue is decomposed and kaolinized, and the copper sulphide badly tarnished. This class of ore gave considerable trouble at the mill, but unfortunately, was very limited in quantity. A sample of rich ore assayed-Copper, 21.2 %; iron, 24:.3 %; silica, 28.9 %; sulphur, 25.1%.The concentration in the original mill was effected by handpicking, jigging, and tabling. A considerable portion of the copper mineral arrives at the surface in the form of large lumps of very pure quality, eminently suitable for sorting out by hand.The rich ore is tipped over a grizzly at the shaft bins; the oversize hand-picked, and the undersize bagged direct.

Jan 1, 1912

By Phillip R. Mulligan, Kevin Gantz, Aaron J. Ward, allen shirley, Sean Treadway

Understanding the impulse transferred into a structure by the coupled two-phase loading produced by an explosive charge buried in soil is of interest for various applications. The most common impulse measurement technique involves a buried explosive charge and a steel plate/test structure suspended above the charge. Upon detonation of the charge, the soil and overpressure heave the plate into the air. The plate’s trajectory and velocity provide the necessary information to calculate the total impulse transferred from the charge configuration.

Jan 1, 2016