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By U. B. Kodukula

Attempts are made to evaluate the feasibility of using a water-injection cyclone for the concentration of iron ore fines. The separation characteristics of clay fines, containing large amounts of alumina and silica, from the iron values are discussed. The effects of critical variables, such as injection water rate, truncated cone diameter, spigot opening and vortex finder diameter, on the performance of a water-injection cyclone in terms of iron, alumina and silica grades; iron recoveries; and alumina and silica rejections are discussed. A set of 16 full-factorial experiments (24) was carried out to gain an understanding of the individual and interaction effects of the variables. The results indicate that classifying iron ore fines containing 63.0% iron, 2.5% alumina and 3.5% silica through a water-injection cyclone can produce concentrates with iron grades greater than 66.0% and alumina and silica contents less than 1.5% and 2.0%, respectively, at different study conditions. The achievable iron recovery values are greater than 88%, and alumina and silica rejections are more than 80% and 50%, respectively, within the specific study conditions. While the truncated cone diameter, injection water rate and spigot diameter influences the alumina rejection to a considerable extent, it is mostly influenced by the vortex finder diameter. The iron recovery and silica rejection values are mostly influenced by spigot diameter and truncated cone diameter. The effect of injection water on the concentration characteristics depend on the prevalent truncated cone diameter and spigot diameter conditions.

Jan 1, 2008

By Ali Ameli

Design loads are limited for piles relying upon toe stresses in rock due to uncertainty about the rock quality over the whole pile diameter because of rock mass properties or construction effects. The paper discusses the use of video images to evaluate rock quality at the bottom of piles socketed into graniodorite bedrock in a steel pipe pile project. Skillful interpretation was required to assess the 3D properties of the rock from video images. It is necessary to observe the rock mass characteristics near the project site for better perception of the rock features from the images. Video image interpretation skills were established by the evaluation of the cores drilled under the socket base and the results of pile loading tests. Correlations were found between rock appearance in the images and the rock socket drilling records. Rock socket acceptance criteria were developed through monitoring the drilling operations for the specific site procedures. Video images then served as one of the quality-assurance tools together with probing and pile loading test. Lessons and methods learned from video inspection in this project could be used to evaluate rock quality in similar cases.

Jan 1, 2006

By Jan E. Nesset, James A. Finch, Wei Zhang

"Bubbles are unquestionably the heart of the flotation process. Their size and combined surface area are largely what drive the recovery process. This suggests that plant engineers should be aware of where their plants are operating with respect to what is achievable for these key parameters. The paper presents a model of how the key operating variables of frother type and concentration, gas rate, altitude (above sea level) and viscosity affect the Sauter mean bubble size (D32) and bubble surface area flux (Sb). The results are compared to a set of plant measurements that demonstrate the benchmarking capability of the approach. A case study is used to link hydrodynamic change to improved metallurgical performance.INTRODUCTION At the beginning of the 20th Century the early practitioners of flotation were aware of the importance of understanding bubble behaviour (Rickard, 1916) but measurement of individual bubble and gas behaviour in the industrial environment was not possible due to a lack of adequate sensors. This situation was not rectified until three quarters of a century later with the advent of industrially-robust sensors developed, notably, at the University of Queensland’s Julius Kruttschnitt Mineral Research Centre (JKMRC) (Schwarz & Alexander, 2006) and McGill University (Gomez & Finch, 2002). What emerged was not the chaotic environment perhaps expected, but defined relationships between gas rate, gas holdup, bubble size and the total surface area of bubbles. These relationships could be defined by mathematical expressions and predicted from an understanding of the key process variables (Gorain, Franzidis & Manlapig, 1997; 1999) (Hernandez-Aguilar, Gomez & Finch, 2002) (Gomez, Cortes-Lopez & Finch, 2003) (Nesset, Gomez & Finch, 2007). The early JKMRC work focused on a large pilot cell (3 m3) installed in plant environments, while the McGill work was initiated on flotation columns (Finch & Dobby, 1990) (Xu, Finch & Uribe-Sales, 1991) and later adapted to industrial mechanical cells (Cooper, Scott, Dahlke, Finch & Gomez, 2004) (Dahlke, Gomez & Finch, 2005) (Nesset, Gomez, Finch, Hernandez-Aguilar & Difeo, 2005). Yianatos of Santa Maria University (Chile), a graduate of the McGill research team, carried the work to industrial settings in South and Central America (Yianatos, Bergh, Condori & Aguilera, 2001). The methods of gas dispersion measurement are now well accepted and most major research centres and flotation cell manufacturers have adopted the technology (Pyecha, Sim, Lacouture, Hope & Stradling, 2006) (Yañez et al., 2009) (Collins, Schwarz & Alexander, 2009)."

Jan 1, 2012

By O. Celep, T. Uslu, Savas

This study investigates the enrichment of a low-grade colemanite concentrate (-3 mm) using a Knelson centrifugal gravity concentrator. Due to its low boron content, the concentrate is unsaleable and has to be stored under appropriate conditions to avoid potential environmental problems. The low-grade colemanite concentrate was comminuted to size fractions of-1 mm, -0.5 mm, and -0.15 mm before treatment in the Knelson Concentrator. The effects of particle size, fluidizing water velocity, and bowl speed on the enrichment process were examined. The B2O3content of the concentrate was increased from 33.96% to a maximum of 45.52%. B2O3recovery increased with increasing bowl speed and particle size, and decreased with increasing fluidizing water velocity. The enrichment process also rejected arsenic and iron to some extent, with a maximum reduction of arsenic from 1360 g/t to 765 g/t and iron from 0.88% to0.33%.

Jan 1, 2015

It is a pleasure and a privilege to be with you for the Annual Conference of The Australasian Institute of Mining and Metallurgy.The inaugural meeting of The Institute was held in Adelaide in April, 1893. Through the kindness of your President, who passed on to me several publications concerning The Institutute I have been able to glance back over the eighty years in which The Institute has served both the profession and Australia.In that record, many names of great distinction caught my eyes. When one reads the list of past presidents of the The Institute since 1893 and the list of those to whom The Institute Medal has been awarded, one reads the headings of a biographical dictionary of the Australian mineral industries. Many famous names are there-men from the great mining companies, engineers, scientists, metallurgists and geologists. Simply to read the names is to recall great enterprise and great achievement. Going over those names one hears the echoes of the inspiring story of the establishment of the Australian steel industry, the electrolytic zinc inq.ustry, all the major developments in the mining of coal, gold, copper, silver and lead, the treatment of difficult ores, the geological exploration of a cqntinent, the discovery of uranium, bauxite, petroleum, nickel, the establishment of the alumina industry and finally the mammoth earthmoving operations of today. The list of names is a chronicle of great men who did a mighty work. They stand like milestones in the progress of a nation.When one reads further and runs down the titles of some of the papers published in the Proceedings of The Institute even a layman like myself can appreciate the dramatic developments in mining and metallurgy that have transformed the whole practice of the mineral industries in our land. Australians have made some notable innovations and discoveries both in mining techniques and in the processing of ores. The history of mining is not only a story of the discovery of the mineral resources of this continent but of adventurous steps taken to perfect new ways of mining the ore and extracting the metal.I read with great admiration the presidential address given by Sir Maurice Mawby in 1968 and wa...

Jan 1, 1973

By Bengt H. Fellenius

The bearing capacity equation?"the triple N formula"? is now about 50 years old. It was developed from theory of plastic resistance of metal to a cone being pressed into the surface of the metal, superpositioned by resistance due to shear in an interparticulate medium (soil; note, we are not dealing with metallurgy), and tempered by work necessary to move the footing into the medium. The equation (and its coefficients) was "confirmed" by tests on small footings placed at or near the surface of the soil. The equation is a basic tenet of every geotechnical textbook, manual, and code. Over the years, innumerable variations of the N-coefficients and adjustments to the equation have been published. The main assumption behind the bearing capacity equation is that a shear plane develops between two essentially otherwise unaffected bodies: the main soil body and a body comprised of the footing with some soil. Moreover, the notion is that a model footing placed at or near the surface of a soil would behave proportionally or similarly to a full-scale footing, or to even a same size footing (pile toe) placed at some depth in the ground. This is not in agreement with factual observations. It is suggested that the behavior of a small or large diameter footing as well as a pile toe is governed by compression of the soil below the footing or pile toe and not by "bearing capacity".

Jan 1, 1999

By Kent C. Condie

Precambrian terranes in the Rocky Mountain region decrease progressively in age from the Archean Wyoming Province (> 2.5 b.y.) to the late Proterozoic in West Texas (figs. 1,2). Within the Wyoming Province, most dates fall near 2.7 b.y. although some are recorded at 2 3.8, 2.9, and 2.6 b.y. Although Penokean (- 1.8 b.y.) deformation and plutonism are recorded in southeastern Wyoming, most Precambrian rocks south of the Wyoming shear zone, which separates the Archean and Proterozoic provinces, are < 1.76 b. years in age. Supracrustal rocks in Colorado, western Arizona, and northern New Mexico fall in the range of 1.72-1.76 b.y., those in central New Mexico about 1.65 b.y., those in southeastern Arizona and southwestern New Mexico about 1.70 b.y., and those in West Texas 1.1-1.2 b.y. The Wyoming Province is comprised chiefly of 2.7 or 2.9 b.y. tonalitic gneiss terranes intruded by 2.6 b.y. granites in the central and southern parts of the province. Supracrustal rocks are minor and include greenstone belts comprised chiefly of pillow- ed tholeiites and graywackes and remnants of quartzite-shale successions. Metamorphic grade in greenstone-gneiss terranes ranges from upper greenschist to amphibolite facies and in quartzite-gneiss terranes from upper amphibolite to granulite facies.

Jan 1, 2013

By Chas. F. Jackson

During the current business depression the Bureau of Mines has received many inquiries concerning placer mining, the prospects for men of small means to make wages by small-scale placer operations, the locations of placer deposits in the United States, methods of working placers on a small scale, and allied subjects. It has therefore seemed desirable to prepare a circular covering, in nontechnical language, the principal questions which have boon referred to the Bureau of Mines for answer. There are a number of bureau publications dealing with placer mining, most of which are now out of print, but which may be consulted in the larger libraries. Other articles on placer mining nave appeared from time to time in the technical press and several good textbooks have been written on the subject. A partial bibliography of this literature appears at the end of this paper. A recent pamphlet published by the Idaho Bureau of Mines and Geology to assist the prospector and inexperienced small operator has received wide and favorable attention and is recommended as a useful reference. In the present paper no attempt will be made to cover the subject of placer mining in a comprehensive manner, but discussion will be confined to elementary questions of particular interest to persons of limited experience.

Jan 1, 1932

By Natalia Konstantinova, Georgy Novikov, Pavel Rekant, Goergy Cherkashov, Olga Bogdanova

The economic interest of oceanic ferromanganese crusts and nodules is determined by high grades of major, rare and earth rare elements in these types of marine minerals [1]. Modern oceanic ferromanganese deposits have a global distribution with the largest fields in the Pacific Ocean. The Arctic Ocean still remains a poorly explored region. The first ferromanganese deposits from the deep part of the Arctic Ocean were recovered almost at the same time in 2012 both in US and Russian cruises to the Chukchi Borderland (1) and Mendeleev Ridge (2). Preliminary results of mineral deposits from the first area were reported at UMI-2012 by James Hein et al. [2]. We present here the data of ferromanganese deposits from the Mendeleev Ridge.

Sep 1, 2014

By S. J. Jung

A fundamental study of fragment size distribution and characteristics of fracture pattern is presented for the dynamic penetration of a conical bit into coal block. In this paper, damaged zones during crater formation and fragment size distribution were studied. Bit with a sharper tip angle and a smooth body configuration performed better penetration. Results suggest that in coal cutting the trend should be toward the face cleat direction using a sharper angled tip bits which consumes less energy for an optimum range of penetration depths, thus attaining maximum cutting efficiency and reducing fine fragments.

Jan 1, 1989

By K. G. Thorne, L. J. Cabri, L. R. Fyffe, D. R. Lentz, D. Hoy

"Mineralization at the Main zone of the Clarence Stream gold deposit in southwestern New Brunswick occurs within a parallel series of quartz veins that occupy a NE-trending, steeply north-dipping, brittle-ductile shear zone related to the nearby terrane-bounding Sawyer Brook fault. This deformation zone cuts volcaniclastic sedimentary and volcanic rocks of the Silurian Waweig Formation, and is intruded by mantle-derived East Branch Brook gabbroic dikes and a number of felsic dikes. Intermittent shear-zone reactivation during local magmatic activity induced heterogeneous deformation and alteration of the country rocks and dikes. The terminal phase of shearing is associated with narrow pegmatite-aplite dikes that grade laterally into granophyric granite, and into an auriferous quartz vein. Gold, aurostibite, and gold-antimony intergrowths, predominantly with vein quartz, are associated with a low ƒO2 sulfide mineral assemblage (pyrrhotite, arsenopyrite, and berthierite) that has a sulfur isotopic signature consistent with a magmatic source. Gold saturation and deposition occurred episodically between 300° and 360°C at low activity of sulfur, predominantly in response to pressure reduction during brittle failure combined with the effects of decreasing temperature and sulfidation reactions during fluid-wall-rock interaction. Geochronological studies demonstrate that the timing of the emplacement of the pegmatite-aplite dikes and associated auriferous veins overlap with that of the Early Devonian Magaguadavic granite. Moreover, the composition of the dikes is consistent with their derivation from this granite as late fractionates. The Main zone of the Clarence Stream deposit is therefore interpreted to be intrusion-related, with the Magaguadavic granite being the ultimate source of the gold-bearing fluids. La minéralisation de la zone principale du gisement aurifère de Clarence Stream dans le sud-ouest du Nouveau Brunswick occupe une série de veines de quartz parallèles dans une zone de cisaillement fragile-ductile de direction NE et à pendage abrupt vers le nord apparentée à la faille de Sawyer Brook avoisinante qui délimite deux terranes. Cette zone de déformation recoupe les roches volcaniclastiques et volcaniques de la Formation de Waweig d’âge Silurien et est recoupée par les dykes de gabbro d’East Branch Brook, d’origine mantellique, ainsi que par divers dykes felsiques. La réactivation intermittente de la zone de cisaillement durant l’activité magmatique locale a entraîné la déformation et l’altération hétérogènes des dykes et de l’encaissant. La phase finale du cisaillement est associée à de minces dykes d’aplite-pegmatite qui passent latéralement à des granites granophyriques, puis à des veines de quartz aurifères. L’or, l’aurostibite et les intercroissances d’or et d’antimoine principalement associées aux veines de quartz sont associés à un assemblage minéral de sulfures à faible ƒO2 (pyrrhotite, arsénopyrite et berthierite) présentant une signature isotopique du souffre compatible avec une source magmatique. La saturation en or et la précipitation a eu lieu épisodiquement entre 300° et 350°C dans des conditions de faible activité de souffre, principalement en réponse à la baisse de pression durant la rupture fragile ainsi qu’aux effets de la baisse de température et aux réactions de sulfuration durant l’interaction entre le fluide et l’encaissant. Les études géochronologiques indiquent que l’âge de la mise en place des dykes de pegmatite-aplite et des veines aurifères qui leur sont associées coïncide avec le granite de Magaguadavic, d’âge Dévonien Précoce. De plus, la composition des dykes est compatible avec une origine provenant de ce granite sous la forme de phases fractionnées tardives. Le gisement principale (Main zone) de Clarence Stream est ainsi considéré comme étant associé aux intrusions, le granite de Magaguadavic étant la source ultime des fluides aurifères."

Jan 1, 2008

By Liane J. Terrill

Rockbolt failures at the Waste Isolation Pilot Plant have been recorded since 1990 and are categorized in terms of mode of failure. The failures are evaluated in terms of physical location of installation within the mine, local excavation geometry and stratigraphy, proximity to other excavations or shafts, and excavation age. The database of failures has revealed discrete areas of the mine containing relatively large numbers of failures. The results of metallurgical analyses and standard rockbolt load testing have generally been in agreement with the in situ evaluations.

Jan 1, 1995

While ring-blasting techniques offer substantial benefits, there are intrinsic problems that are exacerbated when large blocks of ore are mined in attempts to improve the production economics. These problems relate to both the convergence of holes around the ring drive and the charging of up-holes. The size and shape of the ore block concerned should be carefully considered so that good drilling, patterns can be achieved. The hole diameters chosen, both affect and are affected by the size of the ore block. The explosive selected depends on the hole diameter and together with the diameter, determines the nominal drilling pattern. Ring-drilling patterns are best derived through the use of computer software together with engineering judgement. The loading of explosive is necessarily high, and charging patterns require careful thought if overcharging is to he minimised and adequate energy is to be available at all parts of the ore block. Initiation systems are critical to the blasting results, but sub-optimal systems must be adopted if collar priming is practised. In view of all these factors, idealised guidelines can be given for ring design, but it should be recognised that developments in technology may in time change some of these parameters.

Jan 1, 2000

By John F. MacDonald

This paper describes the driving of a 400 m long by 25 m diameter highway tunnel through sensitive, overconsolidated silts and clays. The design concept requires the construction of the permanent support system, consisting of 24 concrete filled perimeter drifts, before excavating the mass core. General construction procedures used during the construction of the perimeter drifts are described.

Jan 1, 1985

The seams of black coal occurring in Victoria are so disturbed by faulting, wash-outs, thinning, etc., that it is necessary, for the prevention of costly errors in development, that close boring be undertaken so that the correct positions of the shafts, tunnels, main and auxiliary roadways can be set out in order that the area can be economically worked. The State Coal Mine has two boring plants continuously at work, which have given good service for the last twenty-five years.The information supplied herein is merely our experience in boring at the State Coal Mine over an extended period. The type of plant in use is that known as the Victoria Drilling Plant, equipped with an 11 h.p. portable oil engine, using power kerosene as fuel. It was purchased in 1914, complete with mechanism for cable drilling, capable of boring to a depth of 1500 ft. with a guarantee of 1000 ft., with Calyx cutters, boring rods and all necessary equipment for the sum of &#163;1473. The chief mechanical features of the plant are as follows:-The derrick is in the shape of a tripod (see Fig. 1), two of the legs being of steel channel built together to form a frame which, when lowered on to two sets of road wheels, forms a carriage for the transport of a portion of the boring equipment. The third leg is made of oregon in the form of a double bow, with bolts and distance pieces between the wooden sides. The top of this is hinged on to the steel frame, and the bottom is fitted into a cast iron block, having two small wheels to facilitate erection. A rope attached to the cast iron block and to the winch easily...

Jan 1, 1936

By Jones S. C

A specific arc can be cut in hard rock formations using a specially designed multistep piloI bit, variable sized drift joint and long heavy control rod as a stabilizer rather than the Vaughan Thompson &quot;Lifting&quot; arc cuttingequipment. The rate of deflection can be controlled after an initial determination of behaviour in any particular rock type.

Jan 1, 1966

By Onur Kacar

A numerical approach has been implemented to assess the settlements of pile groups bearing in clay. A three-dimensional finite element program has been utilized to model a vertically loaded spread footing, a single pile and a pile group. The soil-pile interaction was modeled with elastoplastic soil and interface elements. The model has been calibrated using a full scale load test results of the spread footing. The load transfer between the pile cap and the piles was assessed and compared with the measured load transfer. The predicted settlements for the pile group were compared with the settlements measured in the load test. Two analytical methods were adopted to predict the pile group settlements and they were compared with the measured values. The group effect determined from the analysis and load tests was compared with the interaction factor approach. It was shown that three-dimensional finite element approach can be successfully utilized to assess the soil-structure interaction and hence the load transfer between the piles and pile cap. Also, it was shown that the interaction factors method and equivalent footing method work well in the working stress range, however they underpredict the settlements at larger loads. INTRODUCTION The settlement and stress distribution of pile groups have been traditionally estimated based on load test results of single piles and accounting for the group effect using various approaches. The most widely used approaches are group interaction factor method, equivalent footing method and equivalent pier method. These approximate solutions are used very commonly in practice as full-scale load tests on pile groups are very expensive and time consuming. These approximate solutions are also adopted in design guidelines such as AASHTO LRFD Bridge Design Guidelines (2014) and FHWA Design and Construction of Driven Pile Foundations (2016). In this paper, a full-scale foundation load tests performed by Nagai et al. (1961) and reported by Koizumi and Ito (1967) is modelled using a three-dimensional numerical method. The settlements and the stress distribution on foundations were then compared with the traditional equivalent footing method and interaction factor methods.

Jan 1, 2018

By Paul D. Tomlingson

Part two of this two-part series covers the use of an integrated information system with administrative information, including error and absentee reports as well as open work files. Part one (ME, July, page 650) discussed conceptualizing and developing a maintenance information system. It explained what information is needed to manage such a system.

Jan 8, 1985

By Gavin J. Faulkner

This paper presents an investigation of some alternatives, and improvements to timber posts and cribs. The purpose is to find a cheaper, better, easy to install, and effective means to replace or improve them. Selection of supports needs to take account of several factors. These factors include the mechanical behavior of the support, technical feasibility, and cost. In this paper a variety of supports are compared on these bases. Particular advantages and disadvantages of those supports have been determined through published material and a testing program. A broad evaluation of a number of specific groups of supports is presented. Included in this evaluation are timber posts and cribs, steel friction props and several, newer developments such as the Micon Yield Capsule and the Super Post. Another support that will be briefly discussed is steel-fiber-reinforced concrete. Particular emphasis will be placed on the Micon Yield Capsule and the Super Posts on which preliminary testing has been carried out. The testing results are presented in detail. The shortcomings of the test procedure are pointed out and some new ideas to improve the testing in the future are proposed.

Jan 1, 1986

By S. Z. Pethö, H. Yilmaz

South Deep Mine is currently undertaking numerous voidfilling projects using low strength aerated cement products. Representative samples from one such site, were taken and tested for the load deformation behaviour under uniaxial loading conditions. The process of sample collection, laboratory preparation and testing are explained in detail. The results of testing were analyzed and the critical aspects pointed out as a design consideration to be implemented as part of the quality control and assurance program. Design aspects and underground application of the aerated cement product are discussed for the particular site on 58 level SV1. A simple instrumentation has been designed and installed to enable monitoring of any future movements in this area. A quality control and assurance process has been formulated enabling all aspects of the support installation in this excavation to be signed off.

Jan 1, 2003