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By Marco A. Vera

"This paper investigates the froth function in flotation and the associated upgrading process. Flotation literature has revealed that one of the main functions of the froth phase is the cleaning of bubble-particle aggregates by rejection of entrained material. The cleaning and transport processes across the froth phase exert straining forces on these aggregates on their way up to the froth surface. These forces will impact on the recovery of bubble-particle aggregates.The grade at the top of the froth (TOF) is a parameter related to the quality of particles collected by bubbles in the pulp zone (true flotation). It has recently been demonstrated that TOF corresponds to the maximum practically attainable grade described by the recovery-grade (or enrichment ratio) curve. TOF lumps all the processes experienced by the bubble-particle aggregates before reaching the launder concentrate. This paper describes a methodology for quantifying flotation performance by means of the top of the froth sample - a touch of froth.INTRODUCTIONFroth flotation may be the most important mineral processing technique, but its theory is complex and is not completely understood even though many aspects have been studied and reviewed (Teague, 1998; Wills, 1992).Two distinct particulate systems prevail in the flotation process: a pulp phase and a froth phase (Figure 1). The pulp zone had been studied extensively; however, it is only recently that techniques to measure the froth zone performance have been developed (Contini et al., 1988; Falutsu and Dobby, 1992; Feteris et al., 1987; Seaman, 2002; Vera et al., 1999b).Flotation involves a number of mass transfer processes, occurring in the pulp phase and the froth phase. The formation of the froth and its subsequent removal are considered to be two important steps of the process. Phenomena that occur in the froth phase are known to affect flotation performance significantly (Cutting et al., 1981).Because the froth has a high free surface energy (as a result of the extensive interfacial surface between liquid and air), it appears thermodynamically unstable. The foaming is a dynamic balance, as new bubbles are added continuously from the pulp, while others disappear from the top. Under steady-state conditions, the volumes of added and subtracted air are equal (Booth, 1953)."

Jan 1, 2003

By Marcelo deCastro Souza

Neste artigo é descrito o desenvolvimento e implementação de uma nova estratégia de controle para Prensa de Rolos Polycom da POLYSIUS, utilizada no processo de pelotização da Samarco Mineração S.A. A estratégia de controle é redesenhada com objetivo de otimizar o processo e aumentar a eficiência do equipamento. Como resultado do trabalho foi verificado um aumento significativo da superfície específica do pellet feed de saída.

Aug 16, 2017

By Felix Cheng

Extensions to the Convention Centre in Adelaide, South Australia consisted in part of construction over the existing railway system comprising nine rail lines and passenger platforms. Vibro-pile (Aust) won the design and construct tender with a solution comprising over 500 cast insitu concrete piles. The pile types were 500 to 900mm diameter non-displacement CFA piles and 400mm diameter displacement V-piles. The V-pile is a cast insitu screw pile developed by Vibropile (Aust) Pty Ltd. Both pile types were installed with minimal noise and vibration required for the project, while the displacement V-pile had the advantage over the CFA pile by developing the same pile capacity but with a smaller diameter and with minimal spoil. The latter was important in alleviating spoil removal problems near the railway tracks and disposal of potentially contaminated spoil. The results of dynamic compression load testing and static lateral load testing indicated that the performance of a 400 mm V-pile was equivalent to a 500 mm CFA for this site. The lateral load testing indicated that the surficial soils have a major influence on the load-deflection response, but despite the site containing up to 4 m of filled ground, the piles were found to carry the required lateral loads satisfactorily.

Jan 1, 2002

By Steven Gillgrass

Gerdau Monroe has installed and commissioned the Tallman Supersonic Carbon Injection system (TSCi™) for use in their 135-ton Electric Arc Furnace (EAF) located in Monroe, MI. TSCi™ is an innovative injection system with the primary aim of improving injection carbon delivery to the steel bath by increasing efficiency. It is proven technology with installations at numerous steelmaking facilities all over the world. Results from installation and commissioning of TSCi™ at Gerdau Monroe will be reported as well as on-going trials and optimization efforts. Standard injection systems deliver carbonaceous material from a vessel to the EAF using air where it is injected through a lance pipe or oxy-fuel burner. Using this method, material delivery to the EAF is limited by the pressure and velocity of the transport air. Loss of efficiency can be observed by looking at the quality of the injection carbon stream during operation or by measuring loss on ignition of EAF slag or off-gas system dust. TSCi™ uses a patented design and proprietary technology to improve delivery of carbonaceous material to the EAF. Using this method, savings at Gerdau Monroe were realized by reducing the amount of carbon used in each heat while maintaining or improving upon existing foamy slag practice. As well, significant savings were achieved as a result of reduced FeO content in the slag and improved recovery of iron. Additional savings can be realized by using a smaller mesh material to take advantage of lower material cost and higher injected surface area. Other inherent benefits to improved injection carbon include lower energy and electrode consumption, reduced refractory wear and reduced maintenance cost.

Oct 30, 2017

By J. G. Kelly, C. P. Brown

"In June 1983 a new borehole hoisting system was commissioned at Sherritt Gordon's Fox Mine. Twelve hundred tons-per-day of ore from the 2600 and 2800 levels are being hoisted to the 2000 level through an 8-jt diameter bored winze. This new method replaces the diesel truck haulage system which had been in operation at the mine since 1975.A study was initiated in 1980to determine the most effective method of achieving the required production. The study examined several hoisting alternatives including: expanding the existing trucking system; converting to electrically -powered truck haulage; and deepening the skip compartments of the existing main shaft. The alternative selected as the hoisting method most suited to the requirements was borehole hoisting.Development of the new system commenced in April 1982. Underground excavations included 700 feet of 8-ft diameter borehole, a hoistroom and headframe, storage bins, and a grizzly and rockbreaker station. Equipment installations included: a 5-ft diameter double-drum Nordberg hoist; a counterweighted Kimberley-type skip; two rockbreakers; and the steel sets in the winze. These installations were completed in June 1983. Some problems were encountered after the initial commissioning but these were solved, and since August 1983, the system has proven that the designed capacity is achievable within expected costs."

Jan 1, 1985

By P. D. Hanson, H. Colijin

"New procedures and techniques are now available for the design of bulk storage bins. These new methods have essentially eliminated guesswork in the gravity flow of bulk solids, and have provided a sound basis for the quantitative analysis of alternate designs of hoppers and bins. This paper will discuss the practical application of the Solids Flow Theory (Jenike & Johanson) and illustrate the required design procedure with a few examples of actual bin operations."

Jan 1, 1970

By Jouko L. Lehtonen

Sheet pile walls can be sealed watertightly using various methods. The objective of this paper is to introduce a new innovation comprising the use of continuous cement grouting during embedding. The method has been tested on a field test site and installation and permeability features have been observed and analyzed. Installation can be carried out using traditional sheet piling machinery, merely some additional grouting equipment is needed. Installation speed of grouted sheet piles corresponds to that of conventional embedding. The permeability of the tested method is satisfactory in applications where e.g. polluted soil or water has to be isolated from the surrounding environment. In addition, this method can be used for conventional retaining walls where very low permeability is required or for reduction of soil vibration, e.g. close to a railway embankment. The new method to grout simultaneously and continuously during embedding has been developed based on respective innovations on impact driven steel piles.

Jan 1, 2006

By R F. Hoeberling

"The use of ground penetrating radar (GPR) for geological purposes has been underway for almost two decades. The commercial need for a versatile GPR that can rapidly identify buried objects andunderground voids has been recognized and is an area of research that has already proved useful for several geological activities. Several types of GPR endeavors have been reported in the literature, including exploration of placer deposits (Davis, et al. 1985) and heavy metals (Hammond and Sprenke, 1991), improving oil recovery (Witterholt and Kretzschmar, 1984), investigating coal seams (Coon, et al., 1981), stratigraphic survey (Fisher, et al. 1992), Lunar soils characterization (Olhoeft, et al. 1975 and Strangway, et al. 1977), characterization of rock around mine tunnels (Cook, 1985), location of old mine workings (Scaife, et al., 1992), location of abandoned gas wells in coal seams (Kemerait, 1992) and survey of hazardous waste burial areas (Horton, et al., 1981). Coal seammapping has been developed using a related continuous wave, phase discrimination technique (Stolarczyk, 1990). As the technology for the radar equipment and the onsite computational power has increased, many new applications have become feasible. This article will describe the present status of the GPR technology and indicate some of the exciting possibilities for nearterm prototypes now being constructed."

Jan 1, 1994

By Sigurd L. Lamhauge, Karl Gunnar Holter, Svein E. Kristiansen

An innovative sprayable waterproofing membrane in combination with the traditional Nordic method of waterproofing with polyethylene foam sheets was used for the waterproofing of the tunnel. The sprayable membrane was integrated in the final sprayed concrete lining in a sandwich structure, hence constituting a composite water-proof lining based on sprayed concrete. The spray able membrane was applied in areas with small to moderate water ingresses, making up approximately 50% of the total area requiring waterproofing in the tunnel. State-of-the-art application technology with a computerized spraying robot was used. A consistent application of the required thickness at a high speed was thereby achieved.

Jan 1, 2007

By J. Nielen van der Merwe

Rock engineering research and technology development in South Africa only received serious attention in reaction to the Coalbrook disaster in 1960. At the time, a number of gaps in knowledge of rock related matters were identified and in the ensuing years, these were progressively attended to. The paper describes the events that led up to the Coalbrook disaster and reviews the developments that took place afterwards. The effectiveness of the research outcomes are tested by referring back to the disaster. It is concluded that tremendous advances were made but that not all the unknowns were attended to at the same level. The strength of nominally square internal pillars is the one issue that received the most attention, but the strength of barrier pillars, overburden behaviour and loading systems are still largely unknown. Due to the complexity of the remaining unknowns, they can and should be addressed by the application of back calibrated numerical models. There are no readily available simple analytical solutions. The state of mining rock engineering research in South Africa borders on an emergency. More than a 1000 years of aggregate research experience has been lost in the last three years and funding is under severe pressure. There are disturbing parallels between the current positioning of the industry as a whole and the Coalbrook mine in the years preceding the disaster.

Jan 1, 2006

A massive cobalt-containing pyrite orebody occurs in banded albite-quartz-biotite rocks at Thackaringa, some 30 km SW of Broken Hill. Because of the world-wide shortage of cobalt during the late 1970s, serious consideration was given to the development of a suitable flow-sheet to recover the cobalt from this ore. Details of a pressure leaching process in which more than 90 per cent of the cobalt is extracted from a pyrite concentrate are presented.

Jan 1, 1983

By CHONG WEI, TATYANA KATSAGA, DEREK APEL

This study provides an effective determination process of the interface microstructural parameters in the numerical modelling of the mechanical interaction between two different geomaterials involved with frictional-bonded interfaces, such as the interaction between backfill columns and the surrounding rocks, or the soil-structure interaction, by using the coupled finite-difference and discrete-element (FD-DE) method. Three-dimensional numerical direct shear tests were conducted on the coupled FD-DE model of the combined rock-cemented rockfill (R-CRF) specimens with the frictional-bonded interface. With the microstructural parameters determined, the macro-mechanical properties of the interface of the coupled model were calibrated to well fit with the theoretical values of the combined specimen under the direct shear condition assumed according to the Mohr–Coulomb strength criterion. Evident elastoplastic shear behaviour was observed on the interfaces, and excellent agreement was attained between the shapes of the theoretical and simulated shear stress-displacement curves of the coupled models at different servo-controlled normal stresses. Particulate-scale force chains inside the DE model of the CRF specimen were highly consistent with the force contour on the FD model of the rock specimen, demonstrating the shear stress evolution of the coupled model at different shear displacements. Parametric studies verified the effects of the deformation properties of the interface parallel bonds on the shape of shear stress-displacement curves of the coupled models. The test results validated the feasibility and rationality of the coupled FD-DE method for modelling the combined specimens with frictional-bonded interfaces or joints. Furthermore, this study provides valuable numerical modelling experience for investigating the shear behaviour at the interface between cemented backfill columns and surrounding walls by using the coupled FD-DE method.

Nov 2, 2021

The Annual General Meeting of the South African Institute of Mining and Metallurgy was held in Kelvin House on Wednesday, 24th August, 1977. Dr M. D. G. Salamon (President) was in the chair and declared the meeting open at 16h00. Obituaries The President: It is my sad duty to announce the death of the following members of the Institute : C. G. Evans, J. P. Rees, Life Fellows ; S. R. Bryant, H. MacConachie, M. Mrost, and A. W. van Zyl, Fellows; L. T. Campbell-Pitt, F. W. Collins, A. J. Duncan, I. G. Evans, F. W. Kleinschmidt, P. L. Vaughan, R. W. Wallace, and H. Wason, Members. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I would ask you to rise and observe a few moments' silence. Minutes The President: May we confirm the minutes of the General Meeting held on 23rd March, 1977, as published in the June issue of the Journal? Agreed.

Jan 1, 1978

By Rayleen Riske

Why do we look for better reconciliation when times get tough? Why wait? Mine reconciliation should be a priority throughout the good times too. In fact, with good reconciliation, those good times are going to be even better and will help pave the way to success through those preventable bad times. Reconciliation throughout the entire mining value chain requires the capture, validation, and analysis of copious amounts of data. This task can be daunting for a team in a small mine, let alone reconciling across a suite of large mines. This paper will outline the different ways we can reconcile across the value chain, why we should reconcile over differing periods of time and how Snowden?s solution to proving reconciliation can be a simpler, reliable and transparent process. Snowden?s Reconcilor is proving to be a valuable tool on any mining scale, by capturing, validating, sorting and reporting data for timely decision making by the site geologist through to corporate management. By instigating vigorous reconciliation, you are setting your mine up for the future. Not only will you have the means to analyse your current processes and measures, but you will have the opportunity to identify and improve your mine?s performance from the resource model through to the final product.

May 1, 2010

By Anna Paula Littig Berger

A remoção do fosfóro através do processo de desfosforação do ferro-gusa tem sido cada vez mais relevante, devido a influência que exerce de forma prejudicial as propriedades do aço e devido a extensão do cenário de escassez de minérios com menor teores de fosfóro. Este trabalho tem como objetivo a avaliação termodinâmica computacional de misturas a base de dolomita e finos de minério utilizadas no processo de desfosforação realizado em panela para o refino do ferro-gusa. Foi utilizado o software Factsage para avaliação termodinâmica, tendo este se mostrado eficaz na determinação da concentração de fósforo de equilíbrio no metal, fases presentes e temperatura de fusão das misturas. Verificou-se uma tendência de maiores valores de eficiência para o processo de desfosforação quando aumenta-se a razão de massa de desfosforante e massa de gusa.

Aug 17, 2017

By C. M. Offenhauer

Abstract Zirconium markedly affects the formation of graphite in cast iron and may promote the formation of normal flake gaphite, fine flakes of eutectiform graphite, or spheroid nodular graphite, according to the composition of the Iron and the amount of the zirconium addition. Usually, it is employed in the form of a complex addition agent in order to facilitate its introduction and to guide its effect. The reported applications of zirconium as an inoculant for the production of pearlitic high-strength cast iron indicates that it is most effective as a silicon-manganese-zirconium alloy. Added in this form it reduces chill and minimizes zones of ferrite and eutectiform graphite. In low-sulphur cast iron, zirconium in amounts greater than 0.10 per cent tends to promote the development of eutectiform graphite. These irons are characterized by freedom from primary cementite or normal flake graphite and exhibit very little tendency to shrinkage on solidification. In hyper-eutectic low-sulphur cast iron, zirconium causes the formation of a partially nodular graphite structure. A combination of magnesium with silicon-zirconium alloy was found to produce completely nodular graphite structures without the hazards associated with the addition of elemental magnesium.

Jan 1, 1949

By Lewis M. Haupt

Discussion of the paper of Mr. Granger, presented at the New Haven meeting, February, 1909, and published in Bulletin No. 25, January, 1909, pp. 1 to 37. LEWIS M. HAUPT, Philadelphia, Pa. (communication to the 'Secretary*) :-This subject is of great interest to me, and I am noting progress and conditions as a test of my own judgment in advocating what I believed to be the nearer, cheaper and better route at Nicaraugua. I have as yet learned nothing to change my views, or modify the convictions which led me to retire from the Commission; but that is not the issue to-day. Our government is committed to the Panama route, and is bound to " make good." There are many points presented by Mr. Granger which seem to me worthy of very serious consideration. But when all is said there remains the risk of seismic convulsions, to which either form of canal is subject; and I fail to see that the risk would be reduced by making the cut deeper, with greater surcharge of lateral pressure upon the side walls. A severe earthquake in the rainy season would doubtless close either type of canal. One of the arguments in favor of the Panama route most insisted on, was that Nature had provided good natural harbors at its termini. Recalling this, it has interested me to note that the cost of creating the necessary harbors is estimated at $27,000,000. Mr. Granger refers to this, and quotes the Board's report to the effect that, on the Atlantic side, it will require 5 miles of jetties to " make an excellent harbor out of a wretched one." The vulnerable part of Mr. Granger's paper seems to me to lie in the admission that the plant required is still in the embryonic stage, and that at least one machine should be built and tested " to demonstrate that the theoretical strains and forces work out in practice exactly as expected." This, how-

Jul 1, 1909

By Robert H. Ridgway

This circular outlines salient facts regarding the pyrites industry of the United States and the world. It is founded chiefly upon published information available in the literature of the subject. The United States Bureau of Mines has in its files additional and more detailed data upon many of the subjects presented very briefly here, and will endeavor to assist the mineral industries and the public by giving further information in response to individual inquiries. The bureau will welcome comments, criticisms, and contribu- tions of data that may assist in making later editions of this circular of information more accurate, or may aid in developing more fully the files pertaining to pyrites.

Sep 1, 1931

By Charles G. Patmon

This paper describing the methods of dredging and treatment of gold-bearing gravels at the Lancha Plana Gold Dredging Co.'s dredge is one of a series of similar papers being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The dredge is located near the Mokelumne River, 12 miles west of San Adreas, Calif.; it is accessible by an improved dirt road from Jackson, which is about 20 miles distant.

Jan 1, 1932

By J. R. Thoenen

During the past 6 years the Mining Division of the U.S. Bureau of Mines has prepared many information circulars containing valuable technical data covering the operating details of mining and ore-dressing plants throughout the United States, Canada, Mexico, and other countries. These papers, written for the most part by operating officials in the field, have been designed to comprise a reference library for the operating engineer. In order to make the information contained in these publications more readily available to the busy engineer the enclosed series of reference tables has been compiled. The tabular arrangement is by subject rather than alphabetical order, thus avoiding the bulk of an alphabetical index.

Jan 1, 1935