Search Documents

By M. R. Bowie, J. M. Barker, J. S. Hingtgen

Techniques of testing perlite require a combination of art and science. The modifications made to the perlite Corp. vertical laboratory furnace include addition of instrumentation, flowmeters, vibrators, automatic feeders, and regulators. The basic testing sequence consists of expanded density, furnace yield, compacted density, percent sinkers, and compaction resistance. These tests are modified versions of those specified by the Perlite Institute. This sequence is designed as a preliminary evaluation of a material's suitability for horticultural-aggregate end uses rather than a detailed measure of filtration capability.

Jan 1, 1988

A rotating disc geometry was used to provide a uniformly accessible surface for a kinetic study of copper cementation with zinc in sulphate solution. For copper concentrations of the order of 10 p.p.m., a porous, adherent deposit is formed on the zinc surface and this has a significant influence on the reaction rate. When the specific mass of deposit is less than about O· 35 mg/cm2 the surface may be considered as smooth and the rate is described by simple convective counter diffusion of zinc and copper ions through a laminar diffusion boundary layer to the deposit-solution interface. In the presence of additional deposit, the diffusional mass transfer rate is increased by increased surface roughness.The rate under these conditions is first order, with the degree of enhancement independent of further increases in the specific deposit mass. The enhancement in rateis, however, directly related to the initial mass flux and the species involved in the reaction.Preliminary work showed the same mechanism to apply to cementation from chloride solution, solutions of high zinc concentration, and cementation of copper with iron..

Jan 1, 1970

This paper reviews the historical literature and the author's experience with regard to the effect that the selection of grinding ball size or sizes has on ball mill grinding efficiency. The conclusions presented provide guidelines for single and multi-size charging prac- tices in commercial milling operations.

Jan 1, 1998

By A. Haque

The shear behaviour of infilled joints produced from ordinary gypsum plaster (gyprock) and bentonite was investigated in the laboratory under Constant Normal Stiffness (CNS) conditions. Shear tests were performed on saw-tooth profiles having Joint Roughness Coefficients (JRC) of 4.75 and 9.25 under an initial normal stress (sno) of 0.30 to 1.10 MPa, and at a normal stiffness (kn) of 8.5 kN/mm. Test data under the same sno and infill thickness to asperity height ratio (t/a) were analysed for two different sets of JRC. The peak shear stress plotted against the t/a ratio under constant sno revealed an increase in peak shear stress with the increase in JRC, up to a t/a ratio of about unity. The effect of roughness on the peak shear stress was observed to be minimal when the t/a ratio exceeded 1.40. A mathematical model for the prediction of peak shear stress due to the increased infill thickness has been developed based on a hyperbolic stress-strain relationship and energy balance principles. The model predictions are in good agreement with the laboratory observations. Le comportement de cisaillement des joints remplis produits à partir de plâtre ordinaire et de bentonite a été étudié dans le laboratoire sous des conditions de rigidité normales constantes. Des essais de cisaillement ont été réalisés sur des profils en dents de scie ayant des coefficients de rugosité des joints (CRJ) variant de 4,75 à 9,25 sous un effort normal initial (sno) de 0,30 à 1,10 MPa, et une rigidité normale (kn) de 8,5 kN/mm. Le résultat des essais conduits sous la même contrainte et épaisseur de remplissage au rapport aspérité/hauteur (t/a) ont été analysés pour deux ensembles différents de CRJ. La variation de l'effort de cisaillement maximal contre le rapport t/a sous une contrainte normale constante a indiqué une augmentation de l'effort de cisaillement maximal avec l'augmentation du CRJ, jusqu'à un rapport de t/a proche de l'unité. L'effet de la rugosité sur l'effort de cisaillement maximal a été minimal quand le rapport t/a a excédé 1,40. Un modèle mathématique pour la prévision de l'effort de cisaillement maximal dû à l'épaisseur accrue du remplissage des joints a été développé sur la base de la variation entre contraintes hyperboliques et déformation et sur des principes de bilan énergétique. Les prévisions du modèle sont en bon accord avec les observations de laboratoire. Das Scherverhalten in mit gewöhnlichem Gips und Bentonit gefüllten Klüften wurde im Labor unter Bedingungen konstanter Normalsteifheit (CNS) untersucht. Scherversuche wurden durchgefürt für Sägezahnprofile mit Werten des Fugenrauhigkeitskoeffizienten (JRC) von 4.75 und 9.25 unter Normalspannungs-werten (sno) von 0.30 bis 1.10 MPa, und bei Normalsteifheit (kn) von 8.5 kN/mm. Testresultate für gleiche Werte von sno und Verhältnis Fülldicke zu Rauhigkeit (t/a) wurden untersucht für zwei verschiedene Werte von JRC. Die Beziehung zwischen maximaler Schubspannung und und t/a Verhältnis unter konstantem sno zeigte einen Anstieg der maximalen Schubspannung mit zunehmendem JRC, bis zu einem t/a Verhältnis von etwa 1.0. Der Einfluss der Rauhigkeit auf den Maximalwert der Schubspannung war minimal solange das t/a Verhältnis den Wert von 1.40 überstieg. Ein mathematisches Modell wurde entwickelt für die Vorhersage der Schubspannung die von zusätzlicher Fülldicke erwartet werden kann, ausgehend von einer hyperbolischen Spannungs-Dehnung Beziehung und dem Energiegleichgewichts-prinzip. Die Modellvorhersagen zeigten gute Uebereinstimmung mit den Laborbeobachtungen.

Jan 1, 2003

By R Barrette, V Lawson

Over the last year at Clarabelle Mill, three circuit reconfigurations were implemented. One circuit reconfiguration, æA CleaningÆ, was initiated due to a furnace failure at the smelter complex, and two of the circuit reconfigurations, æincreased copper (Cu) separationÆ and the æInterim IsaMillÖ circuitÆ, were seen as opportunities to increase cash flow through the mill. A Cleaning and the Interim IsaMillÖ circuit took advantage of engineering design already completed for a major capital project. The engineering for each was modified, as needed, and construction of the required portions of the capital project was fast tracked. The increased Cu separation circuit change used existing test and plant equipment to increase the plant Cu concentrate production. Implementation of the projects required teams that included operations, maintenance, technical support, project management and capital project resources. This paper discusses the business reasons driving the changes and the forethought or synergies with other work, which made them a success, and what was learned through each project. CITATION:Taylor, A, Lawson, V and Barrette, R, 2012. Responding to the challenge - Necessity driving circuit change, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 247-254 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Jozef Descour, Kazunori Nishioka, David M. Neil

Designers, engineers, and contractors are using three-dimensional seismic tomography for geotechnical site investigations and during tunnel excavation for hard rock and soft ground applications. Utilizing multiple types of seismic signals produced by a TBM, drill, or impact breaker, the reflection of different velocity features are processed into a holographic image of the actual structure to be encountered. The Mill Creek Phase 3 alignment in Cleveland, Ohio, was imaged to define existing conditions along a 1,200-ft section of a proposed 6.1-m (20-ft) diameter CSO tunnel and, specifically, a zone of expected anomalous conditions where drilling was inconclusive. In Japan, Kajima Corporation used TRT™ to image a number of tunnels including the Fujikawa and Kanaya tunnels in a combination of methods to map structural features along the alignment.

Jan 1, 2001

By Yanhui Liu, Xuewei Lv, Chenguang Bai

A thermodynamic model for determining the surface tension of molten slag by considering the surface tension and molar volume of the pure oxide component, and their ionic radii was extended to the slag bearing high TiO2 (varying from 80 to 67%) at 1973 K. The iso-surface tension curves for the FeO-TiO2-Ti2O3 ternary system at 1973 K are almost parallel to the FeOTi2O3 line. TiO2 plays a role of surface-active solute, and its surface-active effect is attenuating with increasing the TiO2 content. The iso-surface tension curve shifts away from the TiO2 corner, indicating that the surface tension of the ternary slag decreases along with the addition of SiO2. The reasons include the addition of SiO2 with lower surface tension and the decrease of the total ion moment at the surface. Both CaO and MgO can bring about that the iso-surface tension curve shifts towards the TiO2 corner, indicating that the surface tension of the ternary slag increases along with the addition of CaO or MgO. CaO has a more pronounced effect on increasing the surface tension of the ternary slag than MgO at an equimolar amount addition. The increase of the surface tension results from both the compositional change and the variation of the slag structure.

Jan 1, 2015

"Background:The recorded coal production in Nova Scotia from 1863 to 1980 was 390, 000, 000 short tons. This extraction was associated with an estimated 60,000,000 short tons of discarded material. This mining discard and coal washing plant reject are located in numerous, varying sized dumps throughout the mining areas. Approximately 70% of these dumps are in the Sydney coal field region of Nova Scotia.The coal content of these dumps varies from 10 to 30% coal with an average of 18%.Energy Costs:The explosion of energy costs in the mid-1970 's greatly increased the sale price of thermal coal which made recovery of coal from some of the dumps economical. The environmental spin-off of these operations will be the rehabilitation of the dumps upon cessation of the coal reclamation operation.Cape Breton Development Corporation, the owner of most of the dumps in the Sydney coal field was receptive to an approach by Selco of reclaiming coal from their dumps. The technology to be used, had been developed by an associate firm in the United Kingdom on similar mine dump situations."

Jan 1, 1983

By Y. Mitani, M. Zhang, M. Takeda, T. Esaki

Despite their inadequacy, assumptions of isotropy and homogeneity are often applied to the analyses of in situ permeability tests. In this paper, we exam the effects of anisotropy and heterogeneity on Pressure Pulse Test (PPT) and Constant Head Injection Test (CHIT) by means of numerical approaches. Some new findings that offer practical considerations in properly interpreting in-situ permeability tests are presented. Malgré leur manque de précision inhérente, les assomptions d'anisotropie et d'hétérogénéité sont souvent utilisées lors de test de perméabilité in situ. Dans cette étude, nous examinons les effets de l'anisotropie et de l'hétérogénéité sur le test par pression pulsée et le test à injection à charge hydraulique constante par le biais de la simulation numérique. Des nouveaux résultats permettant une interprétation pratique et claire des test de perméabilité in-situ sont présentés. Trotz ihrer inhärenten Ungeeignetheit werden häufig Annahmen über Isotropie und Homogenität auf Analysen von in-situ Permeabilitätstests angewendet. In diesem Papier untersuchen wir die Effekte von Anisotropie und Heterogenität auf Durck-Impuls-Test (PPT) und Konstant-Kopf-Einspritztest (CHIT) mit numerischen Ansätzen. Einige neue Befunde, die zu praktischen Erwägungen zur richtigen Interpretation von in-situ Permeabilitätstests führen, werden vorgestellt.

Jan 1, 2003

By M. E. Kukura, L. G. Stevens

As described in a previous presentation and in various patents, the Minerals Sciences Div. of UOP, Inc., has developed a modified reduction roast ammonia leach process for nickel laterites. This process gave considerable improvement in extraction over the conventional Caron approach as practiced in Cuba, Australia, and the Philippines. This greatly improved response was obtained with a wide variety of ores. This paper describes the pilot plant flowsheet and reviews the design features unique to the UOP process. Operating results from pilot plant campaigns are compared with bench scale results. Operating problems and their solutions are also discussed.

Jan 1, 1976

By Kenneth N. Han, Yichang Guan

The dissolution behavior of metals from Au/Ag/Cu-alloys has been studied using rotating disc electrodes in solutions containing acids, cyanide, and ammonia. Electrochemical methods as well as leaching tests were adopted in this study. The results showed that there was no galvanic effect on the dissolution of metals from homogeneous alloys. In aerated cyanide solutions, the dissolution of gold, silver, and copper from their alloys was partly controlled by surface chemical reaction, but largely by mass transfer. On the other hand, the galvanic coupling effect played a very important role in heterogeneous alloy systems.

Jan 1, 1995

By Evert Hoek

SYNOPSIS It can be shown that the properties of intact rock are relatively unimportant in rock slope stability and that failures are controlled by structural discontinuities such as bedding planes, joints and faults in the rock mass. The frequency, orientation and inclination of these discontinuities as well as their strength characteristics are important factors to be considered in any rock slope analysis and their influence will be demonstrated by means of a number of practical examples. Methods for determining the mechanical properties of discontinuities will be reviewed and the interpretation of the strength test results for use in stability computations will be discussed.

Jan 1, 1971

By E. Stiakakis

The paper presents a geotechnical simulation of the "Mavropigi" open pit mine (Western Macedonia Lignite Center, Greece), using the finite element method. The simulation was based on the initial planning of the pit using Mohr-Coulomb and Soil Hardening models. Results indicate high stability factors as well as the magnitude of the expected horizontal displacements and floor heaving. However, these deformations do not influence decisively the overall stability unless locally adverse tectonics are encountered. Results can be used in the ongoing update of mine planning and stability evaluation.

Jan 1, 2006

By R. M. Brick

A PREVIOUS publication 1§ has described the effect of quenching stresses on the lattice parameter values of high-purity aluminum-copper alloys particularly with reference to the solution and precipitation of CuAl2. A similar study has been made of the aluminum-rich aluminum-mag-nesium alloys. Attention has been directed in the present investigation to the magnitude of the quenching stresses as affected by the specimen size and shape, the number of solute atoms and the quenching rate. The effect of cooling stresses in causing plastic deformation or cracking has been considered in relation to the physical properties of the alloy. On reheating alloys in the two-phase field, the time required for pre-cipitation to occur has been observed in connection with the degree of supersaturation, the rate of diffusion of the solute atoms as a function of the comparative atomic radii, degree of strain, temperature of reheating and grain size. A few qualitative comparisons on the relative effect of these factors have been drawn between the aluminum-copper alloys and the aluminum-magnesium alloys.

Jan 1, 1935

By Reed S. C. Rogers, Robin P. Gardner, Kuruvilla Verghese

The development and use of short-lived radioactive tracer methods for the onstream determination of residence time distributions in large-scale ball mills is described. Tests are reported on a pilot-plant ball mill with 0.43 m diameter and 0.86 m length and on an industrial mill with 1.83 m diameter and 2.74 m length. Tests with different tracer feed sizes indicate that the residence time distributions on both mills are independent of charge particle size. Similar tests are planned for a large ball mill of 4.57 m diameter and 9.30 m length. No safety problems were encountered in these tests and none are anticipated in tests of the larger mill.

Jan 1, 1981

By John F. Vynne

This paper will discuss the application of available monitoring technology on blasthole drills with the goal being to reduce costs and increase productivity. Case studies from the monitoring of blasthole drills in North American open pit mines will be used to illustrate the ability to meet these objectives.

Jan 1, 1997

By Edwin A. Sperry

In 1892 I tested an ore, which was peculiarly difficult to treat, on several concentrators then in general use, including t,he Frue-vanner, the Luhrig table and the Cornish buddle. Owing to the character of the ore it had to be crushed- to a very fine state of division, and the results obtained were far from satisfactory; a large proportion of the values was lost in the slimes, which indicated the necessity of a very careful sizing before dressing. Even after reworking some of the slime-tailings, the results, in my opinion, were not as good aa those which might be obtained on a table designed more especially for the handling of slime. Although the subject of slime-concentration has occupied the attention of many engineers who have threshed the field quite thoroughly, the results obtained in my work led to a careful

Jan 1, 1904

By James T. Kemp

Some interesting and, to American eyes, rather unusual processes for refining impure aluminum derived from scraps were found by American and British investigators who went into Germany in 1945 for the Technical Industrial Intelligence Committee of the Joint Chiefs of Staff. What was found was recorded in a series of reports (see page ), many of which have been released for general reading. This paper gathers under one title and summarizes the German work in refining light metal scrap. Reference must be made to the original reports for greater detail. Basically, the occasion and stimulus for the German developments in treating light metal scrap were hard necessity. Germany needed the metal for a rapacious war industry. Adequate supplies of new aluminum from reduction works were not assured. Great quantities of airplane and other light metal war scraps were forecast. It was evident that the scrap metal would have to be reabsorbed by the producing industry and would have to be kept of good quality. The normal current production of manufacturing scrap was being and could be consumed as generated. It offered no technical problem. The mixed scraps, especially those arising from crashed and decommissioned airplanes, however, presented problems of another kind. Airplane Scrap The recovery of usable aluminum alloy from the mixed assemblies that made up the piles of airplane scrap was attacked in different ways by different groups and with differing degrees of success. Three procedures actually were used on a commercial scale, one was in pilot-plant stage and another had come to a halt in the laboratory a year before Germany collapsed. Four of these five processes actually involved "refining"; that is, some measure of purification of the metal after melting. Sorting and Separation on a Sloping Hearth The simplest procedure for utilizing airplane scrap involved no refining in the strict sense of the word. This was the practice adopted by two representative plants visited by the author, the Leipziger Leichtmetalle Werke, Rackwitz, Saxony, and the Vereinigte Leichtmetalle Werke, Hanover. These firms did essentially the same thing that was done in England but not with equal success, to judge by their shorter experience, the smaller tonnage handled and by the number and quality of alloys produced. The two German firms named rough-sorted scraps by their easily recognizable alloys, essentially by part and shape. They used hand labor to chop and hack and tear apart. The easily separated heavy metal and nonmetallic scraps were discarded as they were found. Steel and the higher-melting-point metal parts riveted to aluminum or built into

Jan 1, 1947

By James T. Kemp

Some interesting and, to American eyes, rather unusual processes for refining impure aluminum derived from scraps were found by American and British investigators who went into Germany in 1945 for the Technical Industrial Intelligence Committee of the Joint Chiefs of Staff. What was found was recorded in a series of reports (see page ), many of which have been released for general reading. This paper gathers under one title and summarizes the German work in refining light metal scrap. Reference must be made to the original reports for greater detail. Basically, the occasion and stimulus for the German developments in treating light metal scrap were hard necessity. Germany needed the metal for a rapacious war industry. Adequate supplies of new aluminum from reduction works were not assured. Great quantities of airplane and other light metal war scraps were forecast. It was evident that the scrap metal would have to be reabsorbed by the producing industry and would have to be kept of good quality. The normal current production of manufacturing scrap was being and could be consumed as generated. It offered no technical problem. The mixed scraps, especially those arising from crashed and decommissioned airplanes, however, presented problems of another kind. Airplane Scrap The recovery of usable aluminum alloy from the mixed assemblies that made up the piles of airplane scrap was attacked in different ways by different groups and with differing degrees of success. Three procedures actually were used on a commercial scale, one was in pilot-plant stage and another had come to a halt in the laboratory a year before Germany collapsed. Four of these five processes actually involved "refining"; that is, some measure of purification of the metal after melting. Sorting and Separation on a Sloping Hearth The simplest procedure for utilizing airplane scrap involved no refining in the strict sense of the word. This was the practice adopted by two representative plants visited by the author, the Leipziger Leichtmetalle Werke, Rackwitz, Saxony, and the Vereinigte Leichtmetalle Werke, Hanover. These firms did essentially the same thing that was done in England but not with equal success, to judge by their shorter experience, the smaller tonnage handled and by the number and quality of alloys produced. The two German firms named rough-sorted scraps by their easily recognizable alloys, essentially by part and shape. They used hand labor to chop and hack and tear apart. The easily separated heavy metal and nonmetallic scraps were discarded as they were found. Steel and the higher-melting-point metal parts riveted to aluminum or built into

Jan 1, 1947

By James Y. Oldshue, Paul M. Kubera

Most coillillercial processing applications employing mixers in various types of slurry systems are continuous flow. These applications may also be multiple stage, with the stage number varying anywhere from two or three to ten or more. Two questions that usually come up at the beginning of any proposed pilot plant study are (1) can the pilot plant unit be operated batch-wise, and the results extrapolated both on the basis of scale and fluid motion to the full-scale tank which will be continuous-flow (and probably multi-stage), or (2) does the pilot plant need to be operated in a continuous-flow fashion, and if so, does the exact number of tanks/stages that are proposed for the plant need to be used in the pilot plant? We will consider these possibilities in sequence and present the principles involved in running some of the various pilot-plant arrangements.

Jan 1, 1992