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By D. R. Miller

The use of fully grouted cables for ground reinforcement in underground mining is becoming widespread. Reinforcement design for this application has tended to be empirical although some two- dimensional design techniques have been developed. This paper describes a technique based on a model of the behaviour of cables placed across planes moving in shear. The model is three- dimensional and includes a simple model of the 'dowel' effect which arises from the bending of the cables. The model determines the shear resistance developed at a particular shear displacement assuming joint friction and cable parameters. Using data for twin 15.2mm dim. steel strand cables, and a concept of reinforcement efficiency, the application of the model to design wall support in open stopes is demonstrated. The examples consider the cases where major planar structures are known in location and orientation and where, as is more common is open stope development, mapping has indicated that a distribution of potential shear failure structures may be present. The actual location and orientation of potential shear planes is not known. These two cases highlight the underdesign of reinforcement that may arise if the distribution of orientation of potential shear planes is not considered.

Jan 1, 1984

By M. R. Louthan

The susceptibility of titanium to stress orientation of hydride precipitates was investigated. It was determined that, when hydride precipitation occurred in titanium under an applied tensile stress of 30,000 psi, the hydrides precipitated on the titanium habit plane oriented most nearly perpendicular to the stress axis. Stress orientation of the hydride platelets occurred because the precipitation of the lower density hydride phase perpendicular to the stress axis caused expansion of the matrix in a direction that tended to relieve the applied stress. The Ti-H system has received considerable study in recent years, mainly because of concern over the effects of hydrogen on the mechanical properties of titanium. The amount of hydrogen present in commercial titanium is now quite low and should have no appreciable effect on its mechanical properties; however, many titanium applications require ex- posure to hydrogenous atmospheres under conditions in which hydrogen pickup is likely. In such cases continued exposures may cause the hydrogen content to increase to the extent that titanium hydride does precipitate as a second phase. The hydride phase has been shown 1,2 to have an adverse effect on the mechanical properties, particularly the impact properties, causing reductions in strength and ductility. BACKGROUND The behavior of titanium is often quite similar to that of zirconium and zirconium-base alloys, and the technology developed on one metal can often be applied to the other. Marshall and Louthan3,4 have shown that Zircaloy is susceptible to stress orientation* of zirconium hydride platelets, and that the platelet orientation has a pronounced effect on the mechanical properties of Zircaloy. They showed that when zirconium hydride precipitated in Zircaloy under an applied stress the hydride platelets tended to be aligned parallel to a compressive stress and perpendicular to a tensile stress. They also showed

Jan 1, 1963

By Marcus Novaes Motta

O modelo utilizado como base para elaboração deste trabalho, foi desenvolvido com os dados coletados no start up da planta de desfosforação de gusa líquido, fornecida pela TECNOSULFUR S/A, localizada em Sete Lagoas - MG a Siderúrgica CISAM, localizada em Pará de Minas – MG. Esse modelo prevê de forma precisa a quantidade de agente desfosforante necessário para o tratamento de desfosforação de ferro gusa, considerando o teor de fósforo final objetivado e levando em consideração o fósforo, silício e temperatura iniciais. O objetivo deste trabalho é testar esse modelo em outros reatores que possuem processos de desfosforação, tais como: desfosforação de aço em convertedores e fornos elétricos. Inicialmente foram coletados dados de desfosforação de algumas publicações para verificação de viabilidade desse trabalho e como o modelo se mostrou eficiente, futuramente ele será testado em algumas empresas e se necessário será ajustado.

Aug 16, 2017

By Gordon Revey

In construction and mining work, situations occasionally occur where hard rock or concrete must be excavated at locations near critical structures or utilities. Fearing damage from blasting, contractors and engineers often explore the viability of using mechanical methods or expansive concrete to facilitate the excavation work. However, for moderate to large excavations, the prolonged duration and high cost of using these methods is often impractical. In these situations, under the right conditions, controlled blasting and blast-management methods can be used to speed up the work and lessen costs. The process of determining whether or not blasting is practical is ofien complex, particularly when risks are high.

Jan 1, 2001

COMMITTEES Committee on Arrangements DAVID H. BROWNE, Chairman LAWRENCE ADDICKS THOMAS T. READ P. E. BARBOUR BURR A. ROBINSON GEORGE D. BARRON F. T. RUBIDGE KARL EILERS E. MALTBY SHIPP LOUIS D. HUNTOON BRADLEY STOUGHTON H.A. MEGRAW EDWARD B. STURGIS ARTHUR L. WALKER

Jan 4, 1917

By Z. C. Chen

Based on the analysis of load test data of long floating piles in soft soil regions, the expressions of load-transfer function of pile shaft and tip for soft soils are presented in this paper, and the data of cone penetration test are suggested to use for calculating the parameters of load-transfer functions. For the loads of pile within the range of the working load of pile, the estimated pile stiffness by the suggested method in this paper are in satisfactory agreement with the results of load tests. The current Vijayvergiya's method and Satowa's method also are used to calculate pile stiffness in soft soil for comparison.

Jan 1, 2010

By O Gutsche, Fuerstenau D. W., R. Ravikumar

Six minerals and one ore, namely, barite, dolomite, galena, limestone, quartz, quartzite and taconite, were ground in single-particle comminution mode in a rigidly mounted roll mill with different levels of energy input. Grindabilities were determined from the median size of the self-preserving product size distributions, which was taken as a measure of the fineness of the ground material in an empirical energy-reduction ratio relationship. These values reflect the inherent resistance of the solids to mechanical size reduction that are least distorted by particle-particle interference effects, grinding characteristics, energy efficiency of the milling system employed and the extent of the fineness specified.

Jan 1, 1992

This paper will be a discussion of the geological exploration and drilling carried out on the Mt Davy Block, Greymouth Coalfield. A brief summary of the geology of the Greymouth Coalfield will be given to put the Mt Davy Block into perspective.

Jan 1, 1979

Jan 3, 1953

By John C. Osmond

One of the least known geologic regions in the U.S. is the area now called the Basin and Range Province. It is paradoxical that so little geologic information has been compiled for a province that has yielded billions of dollars worth of metals and is currently producing a small amount of oil. Regional stratigraphic studies of parts of this large territory have been published only recently, and regional structural interpretations of even parts of the province are rare in the literature. This, of course, does great injustice to the earliest workers: Gilbert, Russell, Le Conte, Spur, Louderback, and others, who recognized the area as distinctively different from the rest of North America. Their simplified picture of the structure of the ranges and the province as a whole is the groundwork for present understanding and has never been superseded. Since their early works, however, geologic data from the province has consisted largely of detailed reports of widely scattered mining districts. Each district has been described as though it were an island in an unknown sea.

Jan 3, 1960

By M. S. Prasad

This paper presents the process methods of beneficiating various copper-cobalt and copper-zinc ores mined by Gecamines in Zaire. Geology and mineralization of both sedimentary and vein-type deposits are described with special emphasis on the production of oxide, dolomitic and sulfide concentrates. Description of different types of concentrators and their treatment methods are discussed for the production of sulfide, oxide and dolomitic concentrates. Production of concentrates, their consumption and stocks are briefly reviewed. Modernization of the concentrators with substantial investments on grinding, classification, flotation methods and tailings treatments are also discussed and to improve the metallurgical efficiency of 'the concentrators to improve the production quality and quantity of concentrates.

Jan 1, 1992

Jan 1, 2009

By David E. Siskind

In the period 1989 to 1994, the U.S. Bureau of Mines assisted the Office of Surface Mining, Reclamation and Enforcement (OSM) in studying a high-complaint situation near an active surface coal mine. As part of a review for its project report, the Bureau had to address issues on the adequacy of the safe blasting criteria and analysis procedures in its 1980 report RI 8507, Structure Response and Damage Produced by Ground Vibration From Surface Mine Blasting.

Jan 1, 1996

By Elmer Ruiz

Frente al actual escenario en Perú, el autor propone trabajar en el diseño de una nueva estrategia, acorde con la realidad de los trabajadores de la minería a pequeña escala, que permita alcanzar una solución viable e integral. Con el fin de dinamizar el proceso de formalización, el autor considera, entre otras, una serie de propuestas que incluyen: censo nacional, sinceramiento de concesiones inactivas, control de la comercialización, así como la promoción, sistematización y fiscalización de la actividad mediante su definitiva reglamentación.

Jul 30, 2020

By W. Blake, J. Mahaut, W. Hustrulid

Division II at Kamoto mine in Kolwezi, Zaire represents a transition zone between Divisions I and III where transverse and longitudinal cut-and-fill rooms were being mined. Because this transition zone had been geologically depicted as being badly faulted the mining in this division had been deferred to a future time. However, to increase production and to reduce mining costs by carrying out the mining of the 3 divisions simultaneously, it was decided to mine Division II. The mining research group of Gecamines was given the task of designing a mining geometry then testing this design in a full scale test. Based on an evaluation of the faulting and fracturing of the 2 parallel orebodies and on an extensive in situ testing program preliminary mathematical analyses were used to develop and evaluate room and pillar designs in the 35°-65° dipping bedded formations. Based on these analyses and the constraints of having to fit the design of Division II to grade into Divisions I and III in a logical manner, a mining geometry for Division II evolved. To test this design an instrumented room was excavated in the most critical area. The results of this full scale testing showed that the behavior of the roof and wall rocks were as had been predicted by finite element computer model studies which incorporated the material properties and results of the field testing. The room geometry design was both judged and observed to be stable, hence mining commenced.

Jan 1, 1977

By Jerry L. Hodgson

This paper presents an application case history of the planning methods used for developing, costing and scheduling an underground hydro- electric pumped storage facility in weak rock. This method covers the system configuration, excavation methods and costs, initial support systems and final lining systems. This study was performed by the Omaha District, Corps of Engineers for the proposed Gregory County Hydro- electric Pumped Storage Project, and presents a synopsis and the results of the studies performed.

Jan 1, 1986

By Oaitse Medupe

The feed to the BCL concentrator is made of the ore from Phikwe No3 shaft, Selebi shaft and Selebi North shaft. The receiving bin of the concentrator has daily throughput of 7869mt live capacity of ore with feed grade from underground operation of 0.70%Ni, 0.75% Cu and 0.05% Co. The valuable minerals in the ore are Pentlandite, Chalcopyrite. Cobalt is present mainly in the solid solution in pentlandite. The common non-sulphides minerals are Amphibolites, quartz, micas, and Feldspar while pyrite and pyrrhotite are the major gangue sulphides. Pyrrhotite contains between 0.1% and 1% Ni in solid solution. From the mineralogical investigation, it was found that approximately 65% of the pentlandite in the ore occurs as exsolutions in the pyrrhotite and the grain sizes ranges from 8 to 38µm. about 25% of the nickel bearing pentlandite is medium grained and subhedral. This kind of pentlandite occurs along the cracks of pyrrhotite or as inclusions in pyrrhotite. The rest of pentlandite present is disseminated in the gangue matrix. Because of the fine occurrence of pentlandite, fine grinding was conducted in order to improve the recovery as well as the concentrate quality. A series of subsequent flotation test were performed in order to evaluate grinds of 35, 40, 45, 50, 60 and 80% passing 75µm. It was observed that ? The mass pull increased together with increasing fineness of grind ? Similar nickel recoveries were obtained at 35 and 40% passing 75µm but from 50% and 60% the grind was seen to adversely affect the nickel recovery. At 80% passing 75µm the recovery increased by small amount. ? Flotation kinetics showed higher initial nickel recoveries but these did not translate into higher final recoveries. ? Grinding finer than 80% passing 75µm yield very high grades of the concentrate in the first minute of the flotation test, and the grade is dramatically reduced in the fifth minute of the test. It was concluded that the current grind of approximately 48% passing 75µm is close to the optimum and no significant benefit were found to be associated with finer primary grinds. The inconsistence of the grade and recovery as well as the pentlandite losses will be discussed. Keywords: Pentlandite, Nickel losses, Grain size, Flotation

Jan 1, 2007

By C. N. Baker

The design and construction of drilled piers through water bearing and caving soil conditions are discussed. The need for close cooperation between the design engineer and contractor in both the design and construction stage is outlined. Four case histories illustrating the design and construction considerations for four different problem soil and ground water profiles are presented, including the field testing and observation procedures that were utilized to confirm that the design inten. was accomplished. Requirements advisable when placing concrete under water in a cased environment and when placing concrete under slurry in an uncased environment are described.

Jan 1, 2010

By Zhang Qi

For the most part, the flying piece is serious endangerment in the demolition blasting. To prevent the endangerment, a large number of materials are needed as the protection. Therefore, the determination and design way of the flying distance of piece in demolition blasting have been concerned extensively. Previously, the experienced or half experienced formula was adopted to calculate the distance of the flying pieces. The calculating values of the distances of flying pieces are not identical with the practice results. The problems concerning the design way of flying distance of pieces are researched in the paper.

Jan 1, 1994

By S. R. S. Sastri, G. V. Rao

Because the nickel contained in lateritic nickel ores does not occur in an identifiable mineral, it is generally accepted that these ores are not amenable to beneficiation. For this reason, such ores are either directly smelted or leached to extract the nickel. In this paper, a process for enriching the nickel content of the lateritic nickel-bearing chromite overburden, normally a waste material generated during chromite mining, is described. In this flotation process, a nickel preconcentrate containing >1.1% Ni was obtained from material containing as little as 0.36% nickel. An empirical relationship was developed to predict the grade of nickel that can be obtained.

Jan 1, 1997