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By F. Chiesa

The permanent mould process, which is a favoured process for producing premium quality aluminium casting, is rarely used to produce magnesium alloy parts. This may be attributed different factors such as: the reservation with which the automotive industry considers using magnesium in structural castings; also the relative hot shortness of most magnesium alloys when compared to aluminium A356/357 is another factor. A third reason stems from the fact that the "heat content" of magnesium is much less than that of aluminium, resulting in the difficulty, for a relatively slow process such as permanent mould (versus pressure die casting), to reach a mould dynamic equilibrium temperature sufficiently high to avoid premature freezing and misruns. The present work will address this problem by carrying out controlled cycling of a laboratory mould, poured with aluminium and magnesium alloys. The influence of insulation of the mould and artificial electric heating on the run-in mould temperature will be determined experimentally. A thermal model will be sought for these thermal devices that will allow to predict the thermal behaviour of moulds of different geometry before a single casting is poured. The model will be tested on an industrial casting in a workshop environment.

Jan 1, 2006

By Filippo Maria Leoni, Gianluca Pianezze

"As part of the Southeast Louisiana (SELA) drainage program, designed to reduce flood damages in the City of New Orleans and surrounding parishes, the SELA-22 project entailed the construction of a concrete covered canal along Jefferson Ave. and Prytania Street. The scope of the required soil improvement was to replace the soil between two parallel lines of sheet piles with a soil-cement mass to eliminate under-seepage, thus creating a so called bottom plug, and provide structural support for the concrete box culvert. The U.S. Army Corps of Engineers (USACE), New Orleans District, selected the jet grouting technology for the construction of the bottom plug to a maximum depth of approximately 40 ft, and for a total length of approximately one mile. The specialty geotechnical contractor proposed to accomplish the task utilizing their proprietary and innovative elliptical bi-fluid jet grout technology which, by limiting the overlap between adjacent columns, allowed a reduction of the overall number of installations. Approximately 2,400 elliptical jet grout columns were installed in a very challenging environment, especially under a logistical point of view. This paper will summarize the main features of the project, focusing on the innovative technological solution adopted to maximize productivity and on the several challenges faced in such limited and complicated logistical conditions.INTRODUCTIONThe Southeast Louisiana (SELA) drainage program has been designed with the purpose of reducing flood damages in the City of New Orleans and surrounding parishes. This will be accomplished by constructing new pumping stations and better drainage canals throughout. The program was authorized in 1996 by the United States Congress and administered under a project cooperation agreement between the Sewerage and Water Board of New Orleans (SWBNO) and the USACE.Prompted by the severity of damages associated with rainfall flooding in southeast Louisiana, the SELA program consists of several individual project components. The proposed work is located on both the east and west banks of the Mississippi River in the Orleans and Jefferson Parishes, as well as in portion of St. Tammany Parish."

Jan 1, 2017

By A. J. Baer

"DEFINITION OF THE REGION AND ITS BOUNDARIESTHE EXPOSED PART OF THE GRENVILLE PROVINCE is the southeastern part of the Canadian Shield, characterized by crystalline rocks with K-Ar ages of about 1,000 million years. Its Canadian portion is bounded on the southwest by Georgian Bay •and by Paleozoic sediments south of a line passing through Orillia and Kingston, on the southeast by the St. Lawrence River valley and the north shore of the Gulf of the St. Lawrence, on the east by the coast of Labrador and on the northwest by the Grenville front, a linear tec-tonic feature that is a metamorphic transition zone and/or a fault. Rocks located to the southeast of the front have younger K-Ar radiom€tric ages than rocks located to the northwest of it.The region is formed of complexly deformed and highly metamorphosed crystalline rocks and in part differs from other areas of the Canadian Shield by the presence of large amounts of crystalline limestone and bodies of anorthosite."

Jan 1, 1970

By Fjeldstad Karin Jusnes

Two quartz types used in the silicon and ferrosilicon industry were heated to temperatures of 1600 and 1700 °C. The parameters varied were the temperature and the holding time at maximum temperature. The amount of quartz, cristobalite and intermediate amorphous phase were measured using XRD and the internal standard method. Type P showed a much larger ability to transform to cristobalite at lower temperatures than type A. Type P had a larger amount of alkali and alkaline earth impurities. This could have enhanced the transformation to cristobalite. For quartz type A the amount of cristobalite was larger at 1600 °C than 1700 °C. This can also be seen for some of the samples of type P at shorter holding times.

By A. L. de Vegt

For the past ten years Paques has been engaged in the development and installation of treatment systems based on biotechnological processes to remove sulfur compounds from water, air and gaseous streams. Metal and sulfate can be removed from mine waters using two biological steps: 1. Sulfate reducing bacteria convert sulfate to hydrogen sulfide (H2S). The H2S reacts with the dissolved metals to form insoluble metal sulfide precipitates. 2. Sulfide oxidizing bacteria convert excess H2S to elemental sulfur. Paques has designed and installed a groundwater treatment system for the Budelco zinc refinery in the Netherlands to remove metals and sulfate as described above. The system has been operating since May 1992 treating a flow of 5000 m /d. A pilot plant started operation in November 1995 at Kennecott's Bingham Canyon Utah copper mine to develop the processes for metal and sulfate removal from groundwater and selective copper recovery from leach water. The principle of the biotechnological methods, full scale experience, and an overview of the test program at the copper mine are presented.

Jan 1, 1997

By G. Song

This paper reports the anodizing voltage, gas evolution and sparking behaviors of an anodized coating formed on AZ91D in a silicate containing solution. According to their responses to an anodizing current, a four-stage anodizing mechanism is proposed. At the same time, the formed coating is characterized in terms of its microstructure, composition, thickness and corrosion performance. It was found that deposition of MgSiO3, Mg(OH)2 and MgO as well as dehydration of Mg(OH)2 are involved in the anodising process; the vigorous gas evolution accompanied by intensive sparking and the corresponding negative anodising efficiency in the later stage of the anodising process are closely associated with thermal decomposition of water due to the high temperature resulting from the intense sparking on the surface of the anodized alloy; the thickness, porosity, and composition of the anodised coating on a magnesium alloy depend on the final anodising cell voltage; and the corrosion resistance of a thick but porous coating containing more silicates appears to be more corrosion resistant than a thin but compact coating containing less silicates.

Jan 1, 2006

By D. van Rensburg

Jointed rock slopes are generally stable, as there is no freedom of movement for blocks of rock. In an open- pit mining environment, blasting opens up space into which blocks of rock can fail, resulting in the common occurrence of slope failure. Prior to the blasting of a trim pattern, the immediate highwall is scaled, where loose rock material is removed by means of a mechanical scaler. As mining of the pit progresses, the height of the scaled highwall from the pit floor progressively increases. These highwalls are never scaled again for the remainder of the pit life, and time-dependant deterioration contributes to these highwalls becoming subject to rockfall and, sometimes, slope failure. This paper documents the development of a South African innovation, a remote-controlled mechanical highwall scaler, a world first for the mining industry. The scaler will enable open-pit highwalls to be scaled from crest to toe whenever the need arises. It will reduce the risk associated with highwalls and deliver on the Anglo American promise of producing safe, profitable platinum.

Jan 1, 2012

By Claude W. Sill

In the course of a series of investigations on vanadium deposits of the western United States, the Bureau of Mines collected many hundreds of samples for chemical analysis. As uranium is often associated with these vanadium minerals, they were also analyzed for uranium, which was pound to be absent in a large percentage of the samples. Since the usual methods for determining uranium are laborious and time-consuming it is very desirable to have some simple qualitative test that can be applied prior to a quantitative analysis to determine whether uranium is present or absent and thus save the time and expense of applying the quantitative analysis to the large proportion of samples containing no uranium. To be acceptable, the test should be specific for cranium, sensitive enough to detect small amounts of uranium, and. simple enough to make it worthwhile to apply. The available methods for detecting uranium lacked one or more of the desired characteristics. Eventually, however, a method was worked out that satisfied all the requirements. This method is probably more specific and sensitive than the usual qualitative methods for uranium, and its simplicity and speed of application make it ideal for testing samples prior to quantitative analysis.

Jan 1, 1945

By Vincent Canaguier

Methane is increasingly considered as a promising reductant for metal oxides, including chromite. To assess the possibilities of such reduction route, the gas-solid reactions between Ar–CH4–H2 gas mixtures and synthetic chromites are studied between 950 and 1050 °C. The influence of Mg and Al additions on the reduction-caburization of (Fe,Mg)(Cr,Al)2O4 solid solution is investigated thermodynamically, structurally and kinetically. The product phases are examined by x-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). The reaction rate is derived from real-time exhaust gas measurements and post-reaction product analyses such as oxygen analysis. Kinetic models are proposed based on the product phase morphologies and confronted with the empirical data.

By Z. Zhang, D. Bouchard, H. Blanchette, A. Lemieux

This paper describes quality control methodologies for the production of semisolid A356 aluminum slugs with the SEED process. A methodology based on destructive tests carried out with an apparatus measuring the force to slice the slugs is presented. The force measurements were correlated with the solid phase morphologies of the slugs and were validated against a non destructive methodology that consisted in monitoring the temperature evolution of crucibles to produce the slugs and the drained metal. Results from the destructive and non destructive methodologies are compared and discussed.

Jan 1, 2006

Discussion of the paper presented at the North Staffordshire Institute of Mining and Mechanical Engineers' general meeting held in Stoke-on-Trent, March 27th 1916, with Mr. John Gregory, President, in the chair, included contributions by Gregory J., Cadman J., Hartley J.W., Wain E.B. and Henshaw A.M., followed by the author's reply

Dec 1, 1916

By Lifeng Li, Jhon Silva-Castro

"Signature Hole Technique is one method to assess the vibration waveform of a production blast.Methematically, it is the convolution between a prior measured waveform of a single blast hole (signature) and a given time delay sequence (comb function). Being an advantage, the inverse operation of convolution, known as deconvolution, can be used to estimate the signature."

Jan 1, 2017

By H. P. Kritzinger, T. C. Kingsley

Rotary kilns are used for a variety of mineral processing operations. Hatch makes use of a kiln model developed from first principles to evaluate designs for its clients. This tool has been applied to a variety of pyrometallurgical applications. This paper illustrates the application of numerical optimization techniques in combination with the kiln model in the interrogation of a generic iron-ore reduction process. The fundamental modelling concepts are explained, followed by a description of the optimization approach. The results show how the combination of the two methods, with modern computing power, can generate a large number of viable design and operating candidates.

Jan 1, 2014

By William Hanco, Carlos Calero

La inclusión de tecnologías 3D en las plataformas de Sistemas de Información Geográficos (GIS) corporativas viene potenciando la labor de Osinergmin, cuya Gerencia de Supervisión Minera está encargada de asegurar el cumplimiento de las normas relativas a la seguridad de la infraestructura de la mediana y gran minería. El artículo describe cómo la captura de aerofotografías de componentes mineros de interés, tomadas con cámaras de alta resolución desde vehículos aéreos no tripulados (drones), son procesadas luego para obtener modelos digitales en 3D, sobre los cuales se realiza la medición de magnitudes físicas para verificar, en gabinete, que los parámetros técnicos de los componentes analizados cumplen con lo autorizado. De este modo, no solo se logra cubrir una mayor área de supervisión, sino también focalizar el trabajo de campo en aquellos puntos donde se encuentren observaciones.

Sep 20, 2019

By Zhijing Zhang

Sodium borosilicate is the basic composition of coating materials, Vycor and Pyrex glasses. In the present study, viscosities of Na2O-Si02-B2O3 ternary melts were measured under various compositions and temperatures. Experiments were carried out using rotary viscometer and graphite components. Our experimental results were compared with those in literature. Based on present experimental results, the previous structure based viscosity model was modified. The predicted viscosity results are in excellent agreement with the present experimental data in the temperature range with molten state samples. The fitting ranges of the model cover the composition of XB2O3 from 0.1 to 0.6 combined with xSio2 / xNa2O = 0.5, 1,2 and 5 respectively.

Jan 1, 1998

By G Baird, M Seto

A low-cost methodology that allows the determination of in situ stresses using oriented core specimens has been investigated. The technique can be used to determine the stresses during the early stages of a project, even in undeveloped areas of a mine. The research aim was to compare the experimental results estimated by the Acoustic Emission and Deformation Rate Analysis methods with those estimated by conventional Hollow Inclusion cell measurements. The studies have been focused on full stress tensor determination from a single oriented rock core. In all cases the rock core specimens recollected the in situ stresses reasonably well compared with the standard overcoring method.

Jan 1, 2000

By A. J. Paul

Traditionally, 16"/50 caliber projectile shells have been fabricated from forged steel. The Naval Surface Warfare Center (NAVSWC) has determined that cost savings of approximately 60% (-$4.7M/year) as well as improved shell fragmentation can be achieved by casting these shells from austempered ductile iron. One of the technical concerns arising out of this material substitution is the role of the casting process in controlling the quality of the cast shells. Optimizing the process through proper orientation of the mold, placement of chills, superheat, etc., can minimize shrinkage porosity and, consequently, flaw size. For this purpose, the mold filling and subsequent solidification of the projectiles was simulated using a 3-D, fully transient, coupled fluid flow and heat transfer model based on finite differences. Several casting orientations were investigated and the casting parameters were varied to optimize the process and minimize casting defects. A comprehensive software tool, which was developed using state-of- the-art visualization techniques, has been used to analyze the process of casting. Emphasis is placed on the use of this visualization tool as an aid to the foundry engineer for process optimization.

Jan 1, 1992

Mining education in Ballarat has a long and proud history dating back to the 1870s. Today the School of Engineering continues this tradition at the University of Ballarat. The recent review of Tertiary Minerals Education by the Minerals Council of Australia has questioned the current situation regarding Minerals tertiary education in Australia and recommendations have been made regarding the future of minerals tertiary education. This paper initially examines the original recommendations made by the Minerals Council of Australia and assesses subsequent changes made to these recommendations. Secondly the paper outlines the future shape of mining education in the light of these recommendations given that they are implemented. Finally the future delivery of mining education is discussed, particularly with respect to the impact of modern technologies.

Jan 1, 2004

By Russell R. Trengove

In order to extend or delimit the known ore reserves adjacent to the Comet Coalition property on the western slope of the Highland Peak Range about 8 airline miles west of Pioche, Nev., the Bureau of Mines undertook an exploration project of diamond drilling. Production figures from this property, formerly known as the Schodde, are not available, but it has been reported that small amounts of rich silver and gold ore were Shipped by wagon to a smelter in the Salt Lake valley during 1900-1910. Small shipments were reported for the period 1915-1927, also. A study of the Pioche District by the Federal Geological Survey in 1942 and 1943 was the basis for the exploration program of the Bureau of Mines in 1947 This program consisted of diamond-drilling three holes. The total footage was 2,967 feet. No. 1 hole was drilled 1,260 feet, a record depth for diamond drilling in the Pioche District. Silver-bearing lead-zinc sulfide ores are found in the Combined Metals limestone, known locally as the C.M. bed, These deposits have been formed by replacement of the limestone that is inclosed in the Pioche shale.

Jan 1, 1949

By S. Geerts, J Davidson

The purpose of the experiment was to determine detonation characteristics of various improvised explosives. The test consisted of detonating a pipe filled with an explosive compound inside of a plywood arena. The pipe will be located in the center of the arena to ensure even distribution on the witness panels. Details on pipe dimensions, weights of the pipe and explosive, and the density were recorded prior to testing for use in the model calculations. The same size pipes were used throughout to minimize the variables inherent in testing. The plywood witness panels will capture the fragments so that penetration data was obtained, primarily the surface area of impact and depth of penetration. Through the use of the penetration data in conjunction with a mathematical model the original fragment velocity was determined. The mathematical model was developed to measure lethality of fragments from explosives and was modified to determine the original fragment velocity instead. From this model other variables such as the Gurney velocity were calculated. This test was done with an explosive compound that was commonly found, and numerous improvised compounds. In order to guarantee accurate data all of the explosives used for testing were cap sensitive, to eliminate the need for a booster charge which would introduce many unknown variables. The one common explosive compound that was used was C-4 which has known data in order to show accuracy of the model and calculations. The other 5 compounds chosen will not have this data as they will primarily be improvised mixtures.

Jan 1, 2011