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By Evelyn Dayrell Lopes Júnior

A capacidade de alimentação de sistemas de fundição é uma das características tecnológicas que está correlacionada a resultados qualitativos negativos, como porosidades e deformações geométricas dos produtos fundidos. As ligas com suas características são parte fundamental do processo de alimentação. A metodologia de caracterização da capacidade de alimentação por meio da coquilha Tatur foi utilizada nesse trabalho, para a qual foram desenvolvidos novos processos de dosagem da liga líquida, com o objetivo de prover maior repetitividade, e consequentemente, maior coerência morfológica das amostras produzidas. Para isso, foram desenvolvidos dois novos métodos de dosagem, chamados “método de dosagem dinâmica” e “método de pré-dosagem”. Esses foram testados e analisados, sendo suas amostras avaliadas comparativamente com o padrão morfológico teórico. O objetivo da obtenção de amostras coerentes foi atingido, sendo evidenciadas a grande influência das variáveis presentes na etapa de vazamento sobre os resultados das amostras obtidas.

Aug 17, 2017

By Charles B. Carpenter

For many years, studies of ground movement and subsidence accompanying subsurface mining operations have been part of the research program of the Bureau of Mines. Periodic observations by engineers of the Mining Division of the Bureau of man-built structures beneath which mining operations are conducted offer indisputable evidence of subsidence in the form of creeks in masonry structures and fractures and depressions in the surface of the earth. As the removal of subsurface rock and earth material by mining, especially by the room-and-pillar method, is equivalent to withdrawing some of the foundation of a building, subsidence of the formations above, the mining levels in certain areas is easily understood as a gravitational adjustment of the overlying earth formations.

Jan 1, 1940

By Charles B. Carpenter

For many years, studies of ground movement and subsidence accompanying subsurface mining operations have been part of the research program of the Bureau of Mines. Periodic observations by engineers of the Mining Division of the Bureau of man-built structures beneath which mining operations are conducted offer indisputable evidence of subsidence in the form of creeks in masonry structures and fractures and depressions in tie surface of the earth. As the removal of subsurface rock and earth material by mining, especially by the room-and-pillar method, is equivalent to withdrawing some of the foundation of a building, subsidence of the formations above, the mining levels in certain air-as is easily understood as a gravitational adjustment of the overlying earth formations.

Jan 1, 1940

By Gennady I. Gulyayev

A mathematical model of plastic deformation occurring in cold plug drawing of mother tubes with initial cross-sectional wall thickness variations (CSWTV) has been developed. The main provision of the model is that eccentricity em is of such value that projection of all forces acting upon the plug in the deformation zone along the axis perpendicular to the drawing axis equals to zero. Calculations have proven that with other conditions being equal increase in the die cone angle and the deformation cycle number reduces CSWTV. Theoretical findings were confirmed by practical results. Keywords: cold, drawing, plug, die cone, plastic deformation.

Jan 1, 2003

By Mary Ellen Bruce Large, Antonio Marinucci, Silas C. Nichols

Tip post-grouting of bored pile (drilled shaft) foundations refers to a method where cementitious grout is injected beneath the tip of a shaft to improve the overall performance of the constructed foundation. This technique, when performed satisfactorily and in the appropriate ground conditions, enhances axial load-displacement performance by improving the mobilization of pile’s resistance. Potential benefits associated with tip post-grouting include reduced settlement under loading, better alignment of load transfer curves, and improved ground beneath the base of the bored pile. However, to be able to realize the benefits attributed to this method, the design, construction, of both the bored pile and the post-grouting system must meet a minimum level for quality assurance. The various factors affecting the successful installation and performance of a bored pile (e.g., workmanship, base cleanliness, borehole integrity, and concrete placement) have been discussed by numerous practitioners and researchers in the available technical literature. For a conventional (i.e., ungrouted) bored pile, acceptance is based on a combination of visual inspection, material testing, and the results of integrity and/or performance testing of the constructed pile. A properly executed tip post-grouting program can be a relatively comprehensive and complex process, which is typically evaluated throughout the construction process based on the results of prior projects and/or on test pile(s) at the particular site. For tip post- grouting programs, verification procedures and acceptance criteria should be established during and incorporated into the design process to ensure design intent and objectives are achieved. Project specifications should be produced to ensure performance requirements are achieved. This paper will present and discuss factors affecting the successful execution of tip post-grouting, including grouting criteria, instrumentation, reliability and uncertainty with the method and outcome, and verification and acceptance. INTRODUCTION Constructing bored piles (drilled shafts) is increasingly more challenging given the lack of ideal site locations, tight project site confines, difficult or restricted access, greater demands on drilling equipment, and close proximity to adjacent structures. To evaluate the feasibility of bored piles as an appropriate foundation system, a myriad of factors is evaluated during design, including site conditions and constraints, budgeting and scheduling, reliability and risk exposure, presence of and depth to adequate load bearing soils/rock, and the magnitude of the imposed loading. Moreover, updated design codes increased load demand per element, and improved material strengths have led to more complex foundation designs, larger foundation elements, and significant increases in load magnitude. Monopile (monoshaft) foundations have been utilized where one large bored pile is used in lieu of a group of piles connected via a pile cap. In addition, to accommodate the design criteria, site conditions, and imposed loading, the geometry of the bored piles being designed and installed have been as large as 13 feet (4 m) or greater in diameter and to depths in excess of 260 feet (80 m).

Jan 1, 2018

Die Suid-Afrikaanse Instituut vir Mynbou en Metallurgie het 'n paar jaar gelede 'n toekenning vir voortreflike akademiese prestasie deur vierdejaarstudente aan technikons ingestel. Disinvestment campaign by COLIN M.SPENCE As President of the Federation of Societies of Professional Engineers, which is an organization representing twelve institutions of the engineering profession comprising over 18 000 engineers of all kinds-of whom over 15 000 are either professional engineers or engineering graduates-I have been asked to make a statement on the disinvestment campaign on behalf of the profession.

Jan 1, 1985

By R. C. Bryce

"Selbaie is located northwest of Joutel, in what is known as the fourth east-west volcanic sediment group in northwestern Quebec. The main metals produced are copper and zinc, with important contents of both silver and gold. Production comes from an open pit mine on the A-I zone and from two underground mines on the B zone and the A-2 zone. Each mine gave rise to important capital investment programs for construction and mine development, all of which were managed and staffed with company-hired, non-union personnel. Production from all sources now exceeds 7000 tonnes per day, with a workforce of540 regular employees. Of particular interest technically is the high recovery of B zone reserves underneath 40 m of overburden cover, the low-cost capital development of the A-2 zone, the computerized control of open pit mining, and the successful copper-zinc separation of the A-1 zone ore. Due to the low grades of the mineral deposits, efficiency in all aspects of the production process, is essential to the success of the operation.LocationThe Selbaie Mine is located 82 km northwest of the locality of Joutel in northwestern Quebec (Fig. 1). Access to the mine is by an all-weather road, 32 km of which is paved. A second road access to the site is via La Sarre, 134km to the southwest. Employee access, materials transport and haulage of copper and zinc concentrates take place over both of these roads."

Jan 1, 1990

Jan 1, 1996

By R. L. Benner

The Bureau of Mines investigated the ZnO-Fe2O3-Fe3O4 system at 1,000°, 1,300°, and 1,400° C, with oxygen pressures between 1.0 and lx10-4 atmospheres. The results, divided into the thermodynamic properties as related to the spinel structure, and the thermodynamic properties as related to zinc concentrate roasting, were used to calculate the activities of ZnO, Fe2O4, and Fe3O4 within the spinel solid solution region of the ternary system, and the pseudo-binary activities of ZnFe2O4 and Fe304. The activities of both systems show large positive deviations from Raoult's Law, especially at high Fe3O4 concentrations. The free energies, the enthalpies, and the entropies of mixing for the binary system were calculated from the binary activities, and the entropies of mixing were compared with two statistical models, one representing an ideal solution, and one representing the mixing of a normal with an inverse spinel. The binary entropy of mixing seemed to be better represented by the latter statistical model, indicating that the tetrahedral and octahedral cations of the reactants tend to remain in the product, even at the high temperatures of the study. This comparison also indicated that the cations of the components are the major contributing factors to the thermodynamic properties.

Jan 1, 1966

By Steve Kral

Worker safety is an issue that transcends industries, whether it be mining, construction, manufacturing or even general office work. In the mining industry, safety and training are particularly important because mining is a dangerous occupation. Throughout the years, federal and state safety regulations have been written and revised to keep up with the changing technologies. And mine operators have installed their own safety and training programs. They have come to realize that a safe and healthy workforce has positive effects on productivity and profitability —not to mention avoiding the high costs of injury-related absenteeism.

Jan 1, 2003

By Donald A. Bruce

"Abstract The Deep Mixing Methods (DMM), in their current forms, have been employed in the United States since 1986, although an earlier version had seen service from 1954. The earlier developments were strongly influenced by practices in the Nordic countries and Japan, while by the late 1980’s several DMM systems had been developed in the U.S. itself. Since then, DMM has continued its evolution, principally via the challenges of a series of large, landmark projects, but also via distinct, significant technological advances. This paper highlights the key points in the history of DMM in the U.S., and provides an overview of the different methods currently in use.In the BeginningIt is a common misconception that the history of applications of the Deep Mixing Methods (DMM) in the United States dates from 1986 when SMW Seiko Inc. — a subsidiary of Japan’s Seiko Kogyo Company — was established in the Bay Area. However, the author believes that Intrusion Prepakt Co.’s patented MIP (Mixed in Place) system had been used, albeit sporadically (about 30 projects are recorded), since 1954 (FHWA 2000, 2001). Ironically, by 1961 this single auger method had been extensively used under license in Japan for excavation support and groundwater control — by the Seiko Kogyo Company. By 1972, the original MIP technique had been succeeded by more advanced Japanese methods, involving multiple augers. Intrusion Prepakt have long since become defunct.The first systematic studies of contemporary Deep Mixing Methods in Japan began in 1967 when the Port and Harbor Research Institute of the Ministry of Transportation began laboratory testing using granular and powdered lime for treating soft marine soils. Fundamental studies continued through the early 1970’s, by which time the development of industrial scale equipment was well advanced, having its first application on a marine trial near Haneda Airport. Coincidentally, laboratory and field research also began in 1967 in Sweden (“Swedish Lime Column Method”) for treating soft clays using unslaked lime. Reportedly the progenitor was a Norwegian, Kjeld Paus, who had made observations on fluid lime columns in the U.S. It would seem that developments in Japan and the Nordic countries proceeded independently until 1975 when the technology leaders from each group (Broms and Boman; and Okumura and Terashi, respectively) presented their — very similar — findings at a conference in Bangalore, India. Limited technical exchanges ensued thereafter.Whereas the Nordic developments continued to focus on the use of dry reagents (cement and lime) and relatively light equipment compatible with operating on and in very soft clays and organics, the Japanese progressed into the use of fluid reagents (cement-based grouts) and heavier equipment for both marine and land-based projects. Thus, by 1986, there were a large number of proprietary (wet and dry) DMM systems in Japan, and a rapidly growing market already by then accounting for over 12,000,000 m3 of ground treatment."

Jan 1, 2014

By O. Rielo, P. Katsabanis

Traditionally fine aluminum is not used in dry commercial explosives due to the hazard associated with aluminum dust explosions during mixing. An industrial process has been developed which enables the safe use of paint grade Aluminum with ANFO. The addition of fine aluminum particles resulted in increased velocity of detonation of ANFO compositions. Velocities of detonation, in 52mm (2 1/16 in.) diameter confined charges were 20% higher than velocities of detonation of straight ANFO. The detonation performance of fine grained ANFO was not benefited by Al at the diameter tested. Furthermore use of larger Al flakes resulted in decreased velocities of detonation. The results are compatible with the experience of Al addition to high explosives. Tests were also conducted using bio-diesel, finding no substantial difference in the performance of AN fuel explosive compositions which used bio-diesel.

Jan 1, 2009

By C. Meyer, J. J. Eidel

C. W. Hunt I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 6, 1987

By Russell Clough

The Pacheco Pumping Plant is situated on the west end of San Luis Reservoir in western Merced County, California. It is designed to draw water from the reservoir and pump it into a 3,500,000 gallon regulating tank. The water then flows entirely by gravity to the Coyote Pump Station in Morgan Hill, a distance of 40 miles, where it is pumped into Anderson Reservoir. This water is used to recharge the depleted groundwater table in the Santa Clara Valley. Eventually, some of the water will be diverted to Hollister in San Benito County and to Watsonville and Santa Cruz in Santa Cruz County. The owner is the United States Bureau of Reclamation. The underground work consisted of a fifteen foot finished diameter surge shaft 250 feet deep to the crown of the pump chamber; a twenty foot finished diameter pump chamber which declined from the shaft at 14.2% for ninety feet and then ran horizontally for 180 feet; and twelve each five foot diameter steel lined intake shafts 240 feet deep which intersect the pump chamber in the horizontal section. (Figure 1) Upon completion of the pump chamber, the contractor had to dewater the existing tunnel under the reservoir, excavate the remaining fifteen foot plug, and concrete the transition. The low bidder for this contract was Underground - Continental-Heller at 414,456,000. Excavation of the open cut for the pumping plant and surge shaft began on April 14, 1983. This was performed using a Koehring 1066D backhoe, dozer, trucks, and two Cat 631 scrapers. The excavation was started at the surge shaft so that the grouting could begin

Jan 1, 1985

By Charbel Khoury, Kwabena Ofori-Awuah, Kofi B. Acheampong

"Following heavy rains in spring of 2014, Prince George’s County officials issued a mandatory evacuation for homes in the Piscataway Hills subdivision of Fort Washington, Maryland where a landslide along a 1700-foot hillside destabilized homes, collapsed the single access road, and resulted in water and sewer mains break. Forensic investigations, including geologic assessments, test borings and in-situ Cone Penetrometer and Dilatometer soundings, were performed to evaluate subsurface conditions and provide stabilization options for the roadway and slopes. Post-failure ground movements were monitored using inclinometers. Critical failure planes were identified within the underlying 30-foot thick Marlboro Clay formation, a known geologic hazard with historic occurrences of landslides and slope failures.This paper discusses the remedial design for stabilizing the landslide and 60-foot hillside slope failure, and protecting the roadway. Amongst several feasible options, driven piles were selected in consultation with the County and retained contractor based on cost, environmental impacts and site constraints. Constraints included private ownership of hillside slope, upslope buildings safety; deep-seated failure, relocation of underground water and sewer mains, and accelerated construction schedule.Pile design included global slope stability analyses and lateral pile analyses using several loading configurations to optimize pile geometry and spacing, and determine a value-engineered design satisfying both serviceability and strength limit states to achieve long-term stability with factor of safety of 1.3. Soils within the active landslide plane were assumed to provide no resistance, while soils below the failure plane provided lateral resistance. This stabilization scheme, which extended along the 1700-foot roadway section and toe of hillside slope area, consisted of 410 steel HP16x141 piles in two to three rows driven to depths between 60 and 70 feet below the Marlboro Clay stratum at 5 to 7-foot spacing."

Jan 1, 2017

By M. K. Pelser

The purpose of this paper is not so much to provide a scientific study of the selection process for the perusal of other psychometrists or industrial psychologists?the purpose is to provide line management with a practical, relatively user-friendly guide to fair and scientific selection. The main areas that are to be covered are: ? Why fair and scientific selection? ? Job analysis ? The job requirement?selection technique circle ? Assessment centres in the mining industry?the Tavistock Collieries Ltd experience. Why fair and scientific selection? Seen from a line manager?s perspective, fair and scientific selection should be pursued for two main reasons: ? to remain within the ambits of the law ? to maximize the probability of selecting the potentially most productive and efficient candidate for the job.

Jan 1, 1997

By Peter Fischer, Heinz-Jiirgen Kateloe, Anton Sroka, Axel Preusse

"Since mining in Germany has a long history, there are still many locations where the surface fracture problem has to be solved. Shallow mine workings from an earlier era can affect the surface in a discontinuous way. In many cases, due to light overburden load, those mine rooms did not collapse and a downfall can suddenly happen for many reasons, e.g., in connection with a changed load entry into the subsurface or by additional influence of water. This results in ground movements, which in extreme cases, appear as surface fractures.Depending on the use of the surface, ground movements caused in such a way constitute an endangerment by law. Particularly, within the southern Ruhr district, surface fracture and subsidence endangered ranges are determined on the basis of an empirical method that resulted from a systematic evaluation of surface fractures and rock disclosures. This method indicates maximum ranges within which impacts from abandoned shallow mine workings must be assumed.With a special emphasis on a risk management approach, RWTH Aachen University adapted the model of stochastic media to the conditions of abandoned shallow mining to compute and illustrate potential ground movements due to the collapse of shallow mine workings. Further investigations were concerned with the analysis of characteristic parameters which can serve for the assessment of the surface fracture probability in a comparative view of different cases. In recent years, more than 50 surface fractures in the southern Ruhr district were analyzed in order to develop a risk assessment of surface fracture endangered ranges over shallow mine workings. The results that have been obtained so far are described in this paper.INTRODUCTIONAbandoned underground mine workings of shallow depth can pose a threat to the surface. Due to small overburden rock loads, shallow excavations often remain intact for decades after the operations have ceased and may collapse abruptly (Braemer et al., 2005; Hollmann and Nuerenberg, 1972; Preusse et al., 2007). Several approaches for prognosis of surface fracture resulting from 97 subsurface collapse deal with this topic (Loebel and Sroka, 2001; Tajdus and Sroka, 2009)."

Jan 1, 2010

By Northcutt Ely

This volume summarizes mining and petroleum legislation in 25 jurisdictions of East Asia and the Pacific. Within these jurisdictions, primary attention is given to requirements that must be met in each country for acquisition of rights to permit development of mineral resources. Coverage includes: First, identification of the controlling laws or statutes governing minerals acquisition and reference to the administrative authority; second, analysis of the laws governing mines and quarries and their products; and third, analysis of laws applicable to natural gas, petroleum, and related materials. Where pertinent, sections dealing with historical background or administration have been added. In countries where minerals are subject to control of States or Provinces, those areas are considered separately from the central government.

Jan 1, 1971

By A. E. Fiorato

A test program was conducted to evaluate use of high-strength concrete in drilled shafts (caissons). The objective of the program was to determine if internal temperatures developed during cement hydration, or other characteristics of high-strength mixes, affect in-situ strength and stiffness. This paper covers strength results. Two 10-ft (3.0-m) diameter by 40-ft (12.2-m) deep caissons were constructed using two different commercially available high-strength concretes, a "low-heat" and a "high-strength" mix. Measured 6x12-in. (150x300mm) moist cured cylinder strengths at 56 days were 13,690 psi (94 MPa) for the "low-heat" mix and 17,130 psi (118 MPa) for the "high-strength" mix. Compressive strengths and moduli of elasticity of cores taken from the caissons were compared to those of companion cylinders made during casting of the caissons and stored in a moist room. Strengths of 4x8-in. (100x200 mm) cores taken at four ages and tested between 34 and 398 days averaged 81% of strengths of 6x12-in. (150x300 mm) moist cured cylinders at corresponding ages. In-situ (core) strengths of the caissons did not appear to be measurably affected by temperature. However, the data indicate that core strengths were sensitive to level of consolidation, as reflected in entrapped air voids. Overall, the results indicate that high-strength concretes can be used in drilled shaft (caisson) foundations.

Jan 1, 1991

By Congcong Chen, Bo Ma

When assessing the safety of a tailings dam, the constant weight method (CWM) is one of the most commonly used methods. However, when the evaluation indicator value suggests serious defects, the evaluation value is often inconsistent with the actual situation. To address this issue, the variable weight method (VWM) is introduced to assess the safety of the tailings dam. Initially, a three-layer indicator system for dam failure safety assessment is built, and individual indicator values are divided into four grades. Then, an appropriate state variable weight function is constructed and relevant parameters are determined. Finally, a case study is illustrated to verify the effectiveness of the model. The assessment results of the VWM more closely represent the actual situation than that of the CWM, which is more helpful for decision makers and technicians to take scientific and reasonable precautionary measures, thereby improving the safety management of the tailings pond.

Oct 8, 2022