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By RT White

For many years the concept of life cycle costing (LCC) was promoted for decision making in corrosion protection systems. Nevertheless, the application of LCC was limited. Input data was often sourced from suppliers and met with scepticism. As a result final analysis was often insufficiently rigorous to meet the needs of Project Managers in sound decision making. The need for expediency often resulted in non-optimal corrosion protection system specifications. With improved communications and the global reach of industries, case history data, based upon actual performance has been able to provide input to substantiate decision making. However, today?s focus upon sustainability whereby environmental, economic and even social aspects enter into decision making has extended LCC into Life Cost Analysis (LCA). In an LCA analysis energy and environmental inputs into systems are compared as part of an overall assessment. The development of Agenda 21 at the Rio summit of 1992 has challenged the countries of the world to look at sustainable development in every economic activity. This ranges from construction to mining to electricity production to automotive production, use and disposal. The protection of buildings, infrastructure and transport systems is part of the needs of sustainable development. Zinc based corrosion protection has been an important part of the arsenal of the corrosion protection industry. This paper will highlight the use of LCC and the development of LCA with reference to the use of zinc based protection systems in a number of important industries.

Jan 1, 2006

The estimation of the shear stress distribution around an excavation is important to the design of the excavation since shear stresses can generate cracks, loosen grain boundaries or otherwise degrade the mechanical and physical properties of the rock and lead to stability problems. In this study, the distribution of shear stresses in a pillar were back-calculated from the deformation measurements made from the SPDV (Site and Preliminary Design Validation) area at the Waste Isolation Pilot Plant (WIPP) site. A plausible pattern of shear stress around an excavation has been suggested based on the Zero Strain Boundary (ZSB) calculation, computer simulation using FLAC, and back-calculation using measured deformation rates in the pillars.

Jan 1, 1998

By Michael S. Miller

In 1984, at the request of Bureau of Land Management, the Bureau of Mines studied 8,500 acres of the 20,250-acre Seven Blackfoot Wilderness Study Area (WSA) consisting of all 3,950 acres of MT-024-657A and 4,550 acres of the 4,850 acre MT-024-657B in order to evaluate the mineral resources. Within this report these 8,500 acres are referred to as the study area. Located about 30 miles northwest of Jordan, MT, the study area is underlain by outcrops of Quaternary alluvium and Cretaceous to Paleocene sandstones, shales, clays, and coal. No mines or prospects were found in the study area. Except for some current interest in petroleum and natural gas, there has been no mineral exploration activity in the study area. The study area contains subeconomic clay, placer gold, and coal. Land within the study area is leased or under lease application for oil and gas.

Jan 1, 1986

A paper presenting an overview of legislative and best practice approaches to the management of OHS&E and business risk for Australian tunnelling operations. Best practice can be achieved in Australian tunnelling through ærisk awarenessÆ by decision-makers and line personnel. This will identify problems before they occur and lead to implementing controls appropriate to avoiding loss throughout the life cycle of the underground opening. The author draws on legislative approaches from all Australian states together with practical experience from risk management and risk engineering work from six recent tunnelling projects. This describes a process that:commences with concept risk assessment,involves quantification of major hazards,conducts assessments of operating risks, andleads to implementation of an integrated management system that keeps construction activities connected with the controls identified in the design and planning phases and minimises the losses sustained as a result. Key points addressed include:where the industry is going with respect to risk û methods and considerations,how tunnelling risks are perceived by the industry and legislation,how tunnel constructors and owners can minimise exposure by using proper risk engineering ætoolsÆ, andreflections on best practice methods for transferring knowledge from designers to contractors/operators.

Jan 1, 2008

By Jaidev Sankar

The dream of constructing the new Second Avenue Subway in New York has finally become reality as the first construction contract package is currently underway. This first contract requires the construction a TBM Launch Box in the middle of Second Avenue from which a Tunnel Boring Machine (TBM) will bore two tunnels south to 63rd Street. This paper will discuss the design of this contract and how construction has progressed including preparation, site constraints, utility construction and com-munity impacts while highlighting the challenges of working in an urban environment. It will also discuss moving forward on this major project outlining the remaining contract packages including their scope and status.

The heap leaching of base metal ores can be applied within a number of different scenarios, each requiring its own set of parameters to be determined during the metallurgical testwork programme. The occurrence of acid-gangue reactions and its concomitant precipitation reactions is a factor common to all cases, and requires that the optimal irrigation acid strength be found that optimises the combination of extraction kinetics, acid consumption and possible premature blinding of the heap due to precipitation reactions. For the heap bioleaching of base metal sulphide ores the oxygen requirement needs to be determined for the design of the aeration system, and the operating conditions employed need to also facilitate bacterial growth over and above the acid strength optimisation mentioned above. For the heap bioleaching of chalcopyrite, the need to preserve heat in the heap becomes yet a further parameter of critical importance. For the heap leaching of uranium ore a choice is required between either chemical or bacterial oxidation, based on economic and processing factors. Frequently the operating parameters need to be determined for a circuit in which heap leaching is combined with tank leaching and/or pressure leaching. The processing implications and metallurgical testwork approach for each case is discussed.

Jan 1, 2007

By K Faure

At Sams Creek a gold-bearing, peralkaline granite pophyry dyke intrudes Ordovician-Silurian metapelite and quartzite. The granite porphyry dyke has a thickness of up to 40 m, extends discontinuously for about 8 km, and intrudes thin lamprophyre dykes along its contacts. The granite dyke and gold-bearing sulphide and quartz-siderite veins within it have been deformed and recrystallised during several phases of folding, the youngest of which is Early Cretaceous.   The unaltered granite porphyry is composed of phenocrysts of perthite, arfvedsonite, aegerine and quartz in a groundmass of the same minerals, with accessory ilmenite, rutile and fluorite. K-Ar dates of amphibole from the granite gave ages of 226 and 246 Ma, but these ages may be a minimum due to resetting during the thermal and deformation events that have affected the area. Unpublished Ar-Ar data on amphibole from the granite show disturbed spectra with high temperature steps around 300-315 Ma, which is consistent with the age of A-type granites in the Buller region. Further age dating of primary and hydrothermal minerals in the granite is continuing. At least three stages of hydrothermal alteration have been identified in the granite. Stage I alteration is characterised by high fO2 magnetite-siderite ¦ biotite, which is cut by thin quartz-pyrite veinlets (Stage II). These are cut by Stage III sulphide, quartz and siderite veins, and pervasive silicification represented by quartz-perthite-albite-rutile ¦ pyrite-siderite-sericite assemblages overprints the earlier alteration stages. Lamprophyre is altered to a siderite-chlorite-sericite assemblage. Stage III sulphide veins are composed of arsenopyrite + pyrite ¦ gold ¦ galena ¦ sphalerite ¦ chalcopyrite ¦ pyrrhotite ¦ graphite, deposited by low fO2 H2S fluids. The gold contains 18-30 wt% Ag and up to 1 wt% Bi. Temperature of vein formation was estimated from vein quartz fluid inclusion homogenisation temperatures (Th 260-355oC, average 330oC), arsenopyrite-sphalerite thermometry (310-365oC) and quartz-albite stable isotope thermometry (340oC). The altered granite and the veins have been deformed, and recrystallised and competent sulphide minerals are fractured and brecciated. Alteration and mineralisation are confined to the granite porphyry and adjacent lamprophyre.

Jan 1, 2004

By Paul Wellman

A computer program is presented that may be used to calculate the bare equipment cost of the major processing units for any hot potassium carbonate gas purification system. The program is designed such that, with only minor modifications, it could be used with a variety of computer systems.

Jan 1, 1968

By William H. Dresher

Introduction A subject long debated but rarely resolved involves the interaction between the academic community and industry in the sponsorship and conduct of research. The subject is, unfortunately, too often treated as a controversy involving ethics and the profit motive. But, in fact, the two branches of society - industry and academia - are necessarily part of the same system. In the last 25 years, the realization has developed that research alone is not sufficient to bring about use of those results to benefit society through productivity gains and economic growth. The flow of events shown in Fig. 1 was generally believed to be the steps required for reaping the benefits of research. Today, research still has the very important role of creating new information or new ideas. However, it is recognized to be but one of many steps in a process that we now refer to as technological innovation. Charpie (1967) said, "Technological innovation is the driving force behind economic growth in the US. In this context, innovation means the process by which a new idea is successfully translated into economic impact within our own society, by providing better products, and simultaneously creating new jobs in the manufacturing of those products. Only after an investigation is put into sufficient use to have an economic effect, is it termed an innovation." One of the best depictions of the technological innovation process is shown in Figs. 2 and 3. These are adapted from Haeffner (1975), and modified by the Committee on Mineral Technology of the National Research Council (1981). Figure 2 identifies the many steps involved in the process. It designates a generalized form for interaction between the academic community and industry. Figure 3 identifies the steps in the "innovation activity" box of Fig. 2. Academia is generally responsible for developing of new knowledge and ideas, as well as maintaining and enlarging the collected body of scientific knowledge. Industry is responsible for developing new products, methods, and processes. Both institutions operate for the benefit of society, but under different driving forces. In academia, the driving force is the achievement of academic excellence. In industry, the driving

Jan 10, 1984

By Guangqing Zhang

The paper presents results of a systematic study of synthesis of titanium oxycarbide and its chlorination. Titanium oxycarbide was produced by carbothermal reduction of titania in hydrogen, argon and helium. Formation of titanium oxycarbide started at 1200°C in all gases. The reduction was the fastest in hydrogen. Formation of titanium oxycarbide in hydrogen was close to completion in 120 min at 1300°C, 60 min at 1400°C and less than 30 min at 1500°C. Reduction in argon and helium progressed at a similar rate and reached 90-95% after 300 min at 1400-1500°C. The chlorination of titanium oxycarbide was ignited at 150-200°C. Chlorine partial pressure and gas flow rate strongly affected the chlorination rate. Chlorination of titanium oxycarbide produced with carbon to titania molar ratio 2.5 at 235-400°C was close to 100% in 30 min.

Jan 1, 2009

Longwall minim; is a highly mechanized, high productivity mining method that is finding increasing applications in coal. Although the method would be highly advantageous in certain hard rock mining applications it cannot be applied in hard rock because no suitable cutterhead exists for such materials. The wedge longwall cutterhead is a, roller cutter device that is wedge-shaped, with cutters arranged to eliminate the very large normal force ordinarily required to cause such cutters to penetrate hard rock. However, the wedge geometry cannot be extended to a point: special nose cutters are needed to open a narrow slot for the wedge. This report describes the design, fabrication, and successful field testing of these critical nose cutters.

Jan 1, 1974

By Graham W. Marks, Betsy M. Jones

"Recently4/ it was shown that the total energy method5/ of spectrochemical analysis is suitable for the quantitative estimation of many of the elements of which ores are composed. It was shown how this method can be applied to the determination of germanium, tin, and lead. Continuing this work, the present report deals with analyses for beryllium, zinc, cadmium, and indium.There are three basic problems in these investigations. The first is to study the influence of those elements that make up the greater part of an ore sample on the spectral-line intensities of the elements for which analyses are being made, the latter generally being the minor constituents. The second is to develop proper methods for the preparation of standard spectrographic curves. Finally, we are concerned with improvement in equipment and procedure, so that greater accuracy can be achieved.As discussed previously, it is better to study as groups those elements that belong to the same group in the periodic table because their spectra are similar. Beryllium, zinc, and cadmium are thus related. Indium was included in this work because it is associated with zinc and cadmium in zinc ores.The authors wish to acknowledge the valuable assistance of the staff of the Bureau of Mines Analytical Laboratory who made the chemical analyses and supplied the ore samples used in this work.A brief description of the procedures followed in making the standard curves and analyses is given below; a detailed discussion will be found in an earlier paper.6/Basically, the procedure for determining a standard curve consists of two parts: (1) Choosing a suitable line in the spectrum of the element to be determined and (2) determining the variation in the intensity of this line with the amount of the element burned in the arc."

Nov 1, 1948

By Bryn Harris, Liming Huang, Andre Laplante

"This paper reviews flowsheets generally used in gold rooms to upgrade primary gravity concentrates particularly those of Knelsons. It is concluded that even for small operations, which treat between 250 and lo00 kg of concentrates per day, there is a strong economic incentive to include in the flowsheet magnetic removal of tramp iron, at least two shaking tables, screening of either table feed or table tails at 150-212 um, and scavenging of table tails with a small centrifuge. Headroom, rather than floor space, is often inadequate in most gold room designs, and limits gravity flow and flowsheet flexibility. Experimental data are presented to demonstrate the effectiveness of a small Knelson Concentrator to scavenge significant amounts of gold (up to 91 %) from fine table tails.RésuméCet article examine les schémas d’évolution généralement utilisés pour traiter les concentres gravimétriques d‘or, en particulier ceux produits par concentrateur Knelson. Nous en venons à la conclusion que même pour un petit circuit d’une capacité de 250 A 1000 kg/jour pourrait bénéficier des opérations unitaires suivantes : concentrateur magnétique pour extraire la feraille, au moins deux tables A secousses, criblage de l’alimentation ou du rejet d’une ou des tables i une maille de 150-212 um, et épuisages des rejets fins de table avec un centrifuge de petite capacité. C’est l’espace vertical du lieu où se fait cette concentration qui représente la contrainte la plus importante, plutôt que sa surface, puisqu’il faut maximiser l’écoulement par gravite des pulpes et s’offrir une certaine flexibilité quant à l’agencement final des opérations unitaires. Nous présentons également des données expérimentales pour démontrer l’efficacit6 d‘un Knelson de laboratoire pour récupérer jusqu’ à 91 % de l’or contenu dans les rejets fins de table."

Jan 1, 1999

By Q. X. Yun

This paper provides a new approach to optimize the production planning in underground mines by means of evolutionary algorithms. Firstly, genetic algorithm is used to reach the global optimization in planning. Then, evolutionary programming is employed to obtain the partial optimization for each year. The application proves that the new approach is reasonable and useful. Keywords: Evolutionary algorithm, Genetic algorithm, Evolutionary programming, Optimization, Mining engineering.

Jan 1, 2003

By R. Sharma, S. Svoronos, S. Gupta, N. A. Abdel-Khalek

This paper presents the results of column flotation of a fine feed sample of Florida phosphate. A central composite design is used to study the main and interaction effects of parameters affecting column efficiency. The statistical design is also used to determine the optimum conditions. The results indicate that, depending on the experimental conditions, it is possible to achieve a concentrate of high grade and recovery. A concentration of 15 ppm of non-ionic frother is found to be enough to maximize the recovery at the pH of 9.5.

Jan 1, 1999

By I. Stanculescu

The consolidation of thick and very compressible soil deposits by stone columns associated with cast-in-place plain concrete columns, has been performed for shallow foundations of some heavy industrial structures. The reduction of settlements and increase of soil bearing capacity were thus ensured as a result of soft soil interaction with stone and concrete columns. The results of model tests and in situ large scale applications are presented. A calculation procedure is also suggested for foundation bases improved by the proposed method.

Jan 1, 2010

By Susan Jacob

The heat of fusion of silver was measured using high temperature differential scanning calorimetry (HTDSC). Heating rate, sample mass, calibration standard and cover gas flow rate were varied to determine their impact on instrument accuracy and reproducibility. Good reproducibility was achieved in most of the runs. Accuracy was not satisfactory in most of the runs, though three runs gave results within 1.7%, 3.3% and 3.5% of the literature value, within the acceptable limits. A larger mass and higher heating rate tend to generate more accurate results.

Jan 1, 2006

By Douglas F. Scott

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied an 11,980-acre part of the 33,300-acre High Rock Canyon Wilderness Study Area, CA-020-913B, in order to evaluate its identified mineral resources. No mineral resources were identified during this study, and no significant amounts of gold, silver, mercury, gem-grade opal, or placer gold are present. The study area is located in Washoe County, NV, about 53 miles southeast of Cedarville, CA. No mining districts or mineral production are known, and no oil and gas leases are in the area. No current claims are in the area; however, six placer claims were located in 1911 in High Rock Canyon near its confluence with Mahogany Creek.

Jan 1, 1987

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 Javier Pozo

La herramienta de gestión corporativa más adecuada en el ámbito de la gran minería es el sistema EAM (Sistema Corporativo de Gestión Mantenimiento de Activos, Enterprise Asset Management). Para que este sistema se realice de manera exitosa, se requiere del compromiso y el apoyo de la gerencia. Posterior a esta etapa de implementación, se desarrolla la de consolidación, donde es importante el apoyo personal externo a la empresa para ejecutar tareas de implantación. Finalmente en SPCC fue necesario un cambio organizacional para la implantanción de MIMS.

Sep 13, 2001