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By J. C. Detweiler

THE Jacksonville plant of Humphreys Gold Corp., operating under leases from National Lead Co. and Rutile Mining Co. of Florida, recovers rutile, ilmenite, zircon, and monazite from an ancient beach deposit containing about 2.5 pct of these minerals in combination. The location of the plant is unique, being situated about ten miles from the center of Jacksonville, Fla., surrounded by a thriving suburb. Two four-lane highways pass within 1 ½ miles of the plant. An expressway now under construction will pass over the tailing pile, within 500 ft of the mine office. The elevation at the plant site is approximately 50 ft above sea level. This is one of two mines producing titanium minerals and zircon in Florida. Another mine is also operated by Humphreys at Starke, about 50 miles southeast of Jacksonville. The Jacksonville deposit extends about six miles in a north-south direction, averaging approximately one half mile wide and twenty ft thick. Values begin at the surface over most of its length and ter-

Jan 1, 1952

By Samuel Hoyt

SOME of the more important properties of finished materials are strength, ductility, toughness, resistance to alternating and repeated stresses, etc: Of these, the property that appears to have received the least consideration, at least in this country, is toughness, which is clue, possibly, to our regarding toughness as a qualitative property or, at any rate, as one that, parallels ductility. This arises out of our greater experience with the simple carbon steels in the rolled or forged (non-heat-treated) condition which, qualitatively, are tough if ductile and are not tough if brittle. In this way we have erroneously become, accustomed to judging the toughness of a material from its behavior in the tensile or similar test. The point of view presented in the present paper is that toughness, like hardness or tensile strength, should be regarded as an independent property and of sufficient importance to require, in so far as that may be possible, quantitative determinations. If such be true, it becomes at once necessary to devise experimental means for measuring, or valuating toughness, and the notched-bar impact test (the Charpy test) is advanced as the most logical test that has so far been developed for this purpose. It is further advanced, with particular emphasis, that we have two kinds of toughness to deal with and, accordingly, they will be dealt with independently. CLASSIFICATION OF MATERIALS ACCORDING TO TOUGHNESS Toughness has been defined somewhat as follows: Tough materials are those that offer considerable resistance to permanent deformation but which, once such resistance has been overcome, may' be deformed plastically, but only by the expenditure of considerable energy. In other words; tough materials may be deformed plastically but they absorb a considerable amount of work in the process. This kind of toughness may be called "static" toughness when the rate of loading is reasonably slow or "dynamic" toughness when the rate of loading is

Jan 2, 1919

By André R. Laplante

"This presentation reviews three continuous centrifuge separators, the Falcon-C, Kelsey Jig and Multi-Gravity Separator, two units with possible synergies with centrifuges, the In-Line Pressure Jig and InLine Leach Reactor, and two centrifuge prototypes, the continuous Knelson and the Altair Jig. Typical applications, potential problems, promising synergies and general concentration mechanisms are discussed. A general discussion on the sources of information, the nature of the fluidization water flow, test work for potential centrifuge separations and the early life cycle of new technology, using centrifuge separators as an example, follows. ResumeCette présentation fait le point sur trois appareils de séparation centrifuge, le Falcon-C, bac oscillant Kelsey et Multi-Gravity Separator; deux appareils qui présentent des synergies possibles avec les centrifuges, le bac oscillant In-Line Pressure Jig et le système InLine Leach Reactor; et deux prototypes centrifuges, le Knelson continu et le bac oscillant Altair. On y présente des applications typiques, les problèmes d’opération les plus usuels, les synergies les plus intéressantes. On discute également des sources d’information disponibles pour le minérallurgiste, de l’impact du mode d’ addition de l’eau de fluidisation, de la démarche expérimentale a faire avant d’installer un centrifuge, et du cycle de développement de nouveaux équipements, en utilisant les centrifuges comme exemple.IntroductionGravity separation has undergone a renewal in the past 20 years, much of it attributed to centrifuge units. The semi-batch Knelson Concentrator has probably received the most exposure, but it is rather because of the shear number of units sold than the width and breath of its applicability. It excels at recovery very dense minerals in very small concentrations, and has become a workhorse of the gold industry. Falcon’s Super-Bowl comes a distant second, with very similar applications. A number of copycats are available, and are generically identified as “Knelsons.” This presentation will not address these units explicitly, but as possible synergies."

Jan 1, 2000

By E Ah Mu and C R Lilley, A D. Campbell

Cave propagation is a complex process due to interacting variables such as mine geometry, rock mass heterogeneity and complex structural networks and stress fields. The Ernest Henry sublevel cave (SLC) is directly below an open pit, which provided an opportunity to observe and measure rock mass failure as the cave initiated and propagated through the pit wall. This paper describes interaction between the open pit and SLC as well as rock mass failure mechanisms observed from the start of the SLC to surface breakthrough.Cave propagation and slope failure mechanisms were found to be governed by intermediate structures, while the cave shape was largely controlled by cave-scale faults. The open pit, production-level geometry and production draw strategy were also important factors for cave and subsidence growth. Cave propagation was episodic and asymmetric in shape due to the orientation and relative position of geological structures, combined with the effects of the increasing SLC geometry and drawdown from the underlying production levels. The precursors and failure mechanism of a 2.5 Mt wall collapse are also reviewed in detail.Cave growth was simulated using a 3D, non-linear, discontinuum finite element model coupled with Newtonian Cellular Automata. Model results are compared to field observations and monitoring data to determine the accuracy of forecasts and compared models versus actual rock mass response during cave propagation.CITATION:Campbell, A D, Ah Mu, E and Lilley, C R, 2016. Cave propagation and open pit interaction at the Ernest Henry Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 311–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

I find that during the short time I have been in this district, the majority of boilers are, and have been, receiving very bad usage owing to the difficulties which they have to contend against, viz., oil and bad water. Oil on the heating surface of a boiler is of a highly dangerous nature inasmuch as it allows the surface to become overheated, owing to the water not coming into direct contact with the plates, and it naturally follows that when the crown sheets of a flue or firebox become overheated, you lose a considerable amount of the strength of the plate, and the flue or crown comes down. Referring to the oil question, I find that too much care cannot or exercised on the part of engine drivers in order to minimise as much as possible the internal lubrication of the various engines under their control. For I consider that it is here that the most of the trouble is caused. My reasons for stating such to be the case, are:-That the majority of enginedrivers before coming to this field have been used to driving engines that have been exhausting into the atmosphere, and probably they have been taught that it is far better to use a little extra lubrication than to have a hot bearing. So far so good. But one thing that must not be overlooked is that on these fields the conditions are altered in this respect, as the majority of engines in this district are not exhausting into the atmosphere, but are condensing their exhaust steam and using the water so condensed for feed purposes.

Jan 1, 1901

By M. G. Maruma

The effect of the amount of cold reduction and annealing temperature on the evolution of the texture of AISI 441 steel is reported. The steel was cold rolled by 62%, 78%, and 82%, followed by isothermal annealing of each sample at 900°C, 950°C, and 1025°C for 3 minutes. The crystallographic texture was determined by Phillips X?Pert PROMPD texture diffractrometer. Microstructures were characterized using optical microscopy and scanning electron microscopy (SEM).The results show that sample that received 78% cold reduction and annealing at 1025°C presented the highest Rm-value and lowest ?R-value, which would enhance its deep-drawing capability. In addition, this sample showed the highest intensity of shifted ?-fibre, notably {554}<225> and {334}<483>. It can therefore be concluded that the ?-fibre, which favours deep drawing, is optimal after 78% cold reduction and annealing at 1025°C.

Jan 1, 2013

By B. Weyerman

U. S. Steel&apos;s Oak Grove Mine experienced several top hinge failures on their caving shields. It was determined that all the caving shields needed to be replaced with new caving shields before more thilures occurred. The cost and amount of time needed for several scenarios of caving shield change outs were compared. This paper discusses how Oak Grove Mine decided to and did change 126 caving shields in six specially designed jig stations underground during a longwall move using their own UMWA employees.

Jan 1, 2001

Despite the recovery of approximately six million ounces of alluvial gold from the West Coast of the South Island, New Zealand during the last 140 years, a great deal of this having been obtained via sluice boxes and riffle tables, there has been little advance in riffle table technology during this period. In this paper contemporary riffle table design and current operational practices are examined. Studies of gold loss to undersize tailings are described. In addition recommendations derived from recent research carried out in North America are contrasted with gold saving strategies adopted by West Coast miners.

Jan 1, 1992

By Jinwu Kang

The hydraulic turbine blade of the matensitic stainless steel (Cr13%,Ni5%,Mo1%) is a kind of large and curved shape, which is susceptible to deformation in both casting and heat treatment processes. The coupling analysis of heat transfer, phase transformation and stress in heat treatment process of the turbine blade for Three Gorges Project is carried out by using Deform-3D software. Its temperature fields, phase fields and stress fields in heat treatment process are obtained. And its deformation is predicted. In the cooling process of normalizing, the blade exhibits relatively large deformation. Based on the stress analysis and deformation prediction in heat treatment process, an algorithm for the determination of reverse deformation of the blade casting in heat treatment process is presented. And the reverse deformation distribution of blade is obtained.

Jan 1, 2010

By J. B. Gwiazda

Introduction Thick seams constitute a considerable portion of Polish coal reserves. In producing mines and those under construction, the reserves where the height is more than 4.5 m (15 ft) total about 24% of all the hard coal reserves. The reserves that are under urban and industrial areas can be extracted using stowing methods for surface protection. About 50% of thick seam reserves can be extracted by caving methods. Thick seam mining methods Thick seams are usually extracted by multilift methods. There are some methods of thick seam mining that generally can be divided into caving and stowing methods. The stowing method is more expensive, but must be used when mining to protect surface features. The more known methods of thick seam mining include • extraction of thick seam in ascending order with stowing ; • thick seam mining in descending order with consolidated stowing; • thick seam mining with gob consolidation; • thick seam mining in descending order with roof caving ; • sublevel caving thick seam mining system; and • thick seam mining system using an artificial roof. Thick seam mining with introduction of an artificial roof The most advantageous method of thick seam mining is the method using an artificial roof. The artificial roof usually consists of wire mesh. Such wire mesh must be durable and must prevent small rock fragments from passing through. The mesh is usually made of steel properly protected against corrosion. The artificial roof is placed on the coal floor of the top slice (Fig. 1). Caving rock falls on the artificial roof and is thus separated from the coal. The next slice is extracted under the artificial roof. The producing face of the next slice must progress within 10 m (33 ft) behind the front of the first slice. As the second producing face progresses, the wire mesh moves down on the coal floor and may be used as an artificial roof for the next slice. Thus, one artificial roof allows the extraction of several consecutive slices. Application of the artificial roof allows for clean extraction and reduces coal losses. It also eliminates the hazard of spontaneous combustion. Introduction of the artificial roof has been limited due to a lack of artificial roof laying equipment. Manual laying of wire mesh is a labor-intensive operation, and it delays face progress, resulting in poor productivity. To eliminate these problems, artificial roof laying equipment was designed at the Polish Central Mining Institute. The support and the method of laying operation is covered by a patent. Artificial roof laying powered support To extract thick seams using an artificial roof, four-leg shield supports with lemniscate linkage were developed (Fig. 2). This shield is used in the first top

Jan 3, 1987

By Driver R. C, Moelle K. H R

This paper is dedicated to the memory of our friend Peter McKenzie who contributed much to the knowledge of the New South Wales Coalfields.ABSTRACTA fossil river system was recently mapped over parts of the Southern Coalfield, N.S.W. This river system occurs in the roof strata of the Bulli Seam. Sandstone of a fluvial nature was deposited in its course. The sandstone exhibits strong sedimentary vectorial properties and has a marked influence on strata-control in colliery workings.The sedimentary features analysed indicate an approximate S200W flow direction. Petrological studies reveal a clastic, well-cemented sedimentologically and structurally anistropic rock type. Washouts have been found and isopach maps of both sandstone and underlying roof-strata have been compiled. Relevant measurements were carried out in existing colliery workings and on bore cores.Optical determinations of feldspars revealed the presence of plagiocIase feldspars with few exceptions. Most of the feldspars are altered to clay minerals. It was found that a geographical trend exists in the distribution of feldspars, with more basic plagioclase in the northern part of the field.The source area of the fluvial sandstone lies to the north of the Southern Coalfield.Petrofabric analyses were done on several specimens of the fluvial sandstone. In the vicinity of major disturbances, penetrative fabrics were discovered.Calcites (e, 0112), micas (001), and quartz (crystalIo graphic c) show preferred orientations.

Jan 1, 1967

By J Mercuri, S Dunford, P Rothman, E Bartsch, J Snyder, D Newton, R Maron, D Cirulis

The purpose of a mineral comminution circuit with a ball mill running in closed-loop with a hydrocyclone classification cluster is to feed the downstream process with the target particle size. Maintaining the optimal particle size in the flotation feed can significantly improve plant cash flow. In particular, reducing the amount of coarse material is often a major challenge. Existing instrumentation to provide particle size measurement is considered standard equipment in most modern concentrator plants. However, availability is often very low, mainly owing to high maintenance requirements of the analyser and associated sampling system.CiDRA Minerals Processing has developed two novel and robust technologies that address this challenge by providing high reliability and very low maintenance systems for on-line measurement of coarse material in the overflow of individual hydrocyclones. The first system is non-invasive and measures pebbles and rocks greater than 6 mm. This paper focuses on the second system, which is a ruggedized wetted sensor design with no moving parts and provides a real-time trend of the desired target grind size parameter, such as percentage above 150 micron.Both systems have simple robust designs and measure in the primary overflow stream of the individual hydrocyclone. Individual hydrocyclone measurement enables identification of poor performing hydrocyclones in addition to providing a representative measurement of the whole hydrocyclone cluster. The systems do not require sampling and associated sample transfer piping circuits that are prone to plugging, thus avoiding high maintenance requirements.The wetted sensor will be described in detail along with its implementation in a robust control scheme in a major copper concentrator in North America. Plant data shows very high availability, achieved with very low maintenance, has enabled improved process control, thereby maintaining throughput and ball mill target power while reducing grind size.CITATION:Cirulis, D, Dunford, S, Snyder, J, Bartsch, E, Rothman, P, Maron, R, Newton, D, O’Keefe, C and Mercuri, J, 2015. Process optimisation using real-time tracking of coarse material in individual cyclone overflow streams, in Proceedings MetPlant 2015, pp 93–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By L. du Plessis

The name FISH (Fully Integrated Sort House) refers to a class of technology deployed at Jwaneng Mine final diamond recovery. The FISH concept is based on three pillars, namely: ?Improved sorting efficiency FISH is based on laser technology, which is more efficient than hand sorting for certain product categories. Laser sorting is based on measuring in-elastically scattered light from molecules and this is referred to as Raman spectroscopy. The Raman scattered light occurs at wavelengths that are shifted from the incident light by the energies of molecular vibrations ?Availability of production information Roller gap diamond size distribution information is generated on line for upstream process optimization ?Improved product security A ?hands-off? philosophy reduces security risk during operation and maintenance of the plant. In addition, a number of lessons were learnt about the application of new technologies in the industry: ?The required human competency profile demanded by new technology should match the available competencies of the operational staff ?An integrated information management system should be fully functional for both production management and diamond control purposes ?Operational feedback must be correctly evaluated to identify design, maintenance, training and operational issues so as to accelerate the maturity of the new technology within the time span of the sustainable operations project ?Project execution and technology maturity risks have to be evaluated and married to ensure risk mitigation by means of suitable project resource and contracting model selection.

Jan 1, 2003

For many years the scrubbing of roaster gas carrying sulphur dioxide has been carried out at the plant of the Electrolytic Zinc Co. of Australasia Ltd. at Risdon, Tasmania, using long horizontal tubes. in which the gas stream crossed a shower of water. In order to provide for increased roaster capacity, it was evident that additional gas scrubbing capacity would be required to prevent pollution of the atmosphere.This provided an opportunity to review the whole operation of gas scrubbing and an investigation was initiated to determine the characteristics of a counter-current type of scrubber. It was hoped that a change to this type of scrubbing would also reduce the sulphur dioxide concentration of the gas delivered to the atmosphere to a negligible amount. This, paper outlines results obtained from an experimental tower which was operated under a wide range of conditions, the packing height, gas flow, water flow, water temperature, and concentration of S02 in inlet gas being varied independently. A description is given of the leading features and operating characteristics of the plant units, which are designed on the basis of the experimental results. Operation of the new scrubbing system commenced on October 5th, 1948.THE PROBLEMThe gas which is handled carries S02 which may vary in concentration from 2% to 5%, and reaches the scrubbing system at a temperature of approximately 180 deg. C. An appreciable amount of suspended material accompanies the gas which has passed the cyclone system.

Jan 1, 1949

By J. Tanner Blackburn, James R. Gingery, Lisheng Shao

Rigid inclusions consist of grout columns installed using displacement auger or vibrated tooling. The columns are typically installed in an array to provide support for footings, mats, or embankments. Due to the relative small column diameter and low replacement ratio, the surrounding soils typically have minimal densification or improvement. A gravel load transfer platform is commonly used above the rigid inclusion head to distribute stresses more broadly to the supported structure. The axial stiffness and geotechnical engineering mechanics of rigid inclusion design are similar to those of deep foundation systems, but they are typically only lightly- or un-reinforced and are not structurally connected to the above-grade structure. The popularity of rigid inclusions is increasing in the Western U.S., where many urban areas are subject to moderate to high seismic hazard levels. However, the performance of rigid inclusions under seismic loading is poorly understood, and seldom addressed in current designs. The elements are brittle, with limited or no ductility and relatively low moment capacity, and therefore may be prone to damage under seismic loading. Three modes of seismic loading should be considered: inertial loading from the structure, kinematic loading from vertically propagating shear waves, and kinematic loading from ground failure- related permanent ground deformation. This paper focuses on the first two modes. A simplified procedure for evaluating kinematic and inertial loading of rigid inclusions is described, and its use is illustrated through application to a site in Southern California. The results show that moderate to severe kinematic loading can generate plastic hinges in the rigid inclusions. Engineering consequences of this hinging could include settlement or bearing failure. INTRODUCTION In this paper the term ‘rigid inclusion’ (RI) refers to grout or grouted aggregate columns that are installed using either drilled or vibration displacement techniques. They are commonly installed in arrays to support vertical loads from footings, mats, or embankments. RIs are not structurally connected to footings they support. Rather, it is typical for a dense gravel load transfer platform (LTP) to be installed as a cushion between the RI head and supported footing or new fill. In cases of RI support of fill embankments, the LTP may be reinforced with horizontal layers of geogrid.

Jan 1, 2018

By N N/A

To the members of The South African Institute of Mining and Metallurgy We have audited the annual financial statements set out on pages 239 to 245. These financial statements are the responsibility of the Institute?s Council. Our responsibility is to express an opinion on these financial statements based on our audit. Scope We have conducted our audit in accordance with statements of South African Auditing Standards. These standards require that we plan and perform the audit to obtain reasonable assurance that the financial statements are free of material misstatement. An audit includes: ?examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements ?assessing the accounting principles used and significant estimates made by management ?evaluating the overall financial statement presentation. We believe that our audit provides a reasonable basis for our opinion. Audit opinion In our opinion, the financial statements fairly present, in all material respects, the financial position of the Institute at 30 June, 2000, and the results of its operations and cash flows for the year then ended in accordance with South African Statements of Generally Accepted Accounting Practice.

Jan 1, 2000

By N. P. Kripakov

Results of a complex three-seam interaction analysis in a western U.S. coal mine are presented. The physical situation simulated by the models represents the development of a set of entries underneath two previously mined seams with all three seams in proximity to each other. The layout and the geometry of the remnant pillars in the upper seams were nonuniform and not always directly superimposed over each other, creating a very challenging modeling problem. The U.S. Bureau of Mines&apos; MULSIM/PC computer code was upgraded and enhanced to perform the required three-seam interaction calculations. Analysis was limited to simple linear-elastic assumptions as only peak stresses were required. Results clearly indicated that stress concentrations in the lower seam increased approximately 100 percent when compared to cases simulating no extraction in the two upper seams. These stress concentrations generally occurred in zones directly below points of highest abutment pressures in the upper seams. Overall, the model results compared favorably with actual documented observed behavior where roof failures were known to have occurred.

Jan 1, 1996

By M R. Stevens

An approach of geological mapping and descriptive criteria has been used to identify hydrothermal eruption breccias, named the Onemana Breccia. These in part mantle a gold bearing fossil hydrothermal system located on the eastern side of the Coromandel Peninsula, New Zealand. Whilst eruption breccias are documented from active and recent geothermal centres within the Taupo Volcanic Zone and in Northland their recognition at Onemana is the first confirmed discovery for this lithotype within ancient hydrothermal systems of the Coromandel Volcanic Zone. At Onemana the widespread occurrence of silicification, sinters, volcanic lake sediments, eruption breccias and advanced argillic alteration allows classic hot spring epithermal modelling. The geological setting, distribution, lithological characteristics, hydrothermal alteration and trace element geochemistry of the Onemana eruption breccias are described. These breccias are closely comparable with hydrothermal eruption deposits elsewhere, particularly those in active ore forming hydrothermal systems. Consideration is given specifically to the role of the Onemana Breccia in an exploration strategy for discovering epithermal gold-silver deposits.

Jan 1, 1991

By P. W. Godbehere

"INTRODUCTIONMagnetic mill linings have been developed from an invention by Mr. Bertil Brandt, the originator of the Skega rubber lining. The OREBED magnetic mill lining is a concept in which rubber covered strontium ferrite permanent magnets are arranged on the inside wall of a mill shell so that they attract magnetically susceptible material be it ore, media or tramp, to form a protective layer over the magnets and to serve as an operating surface with indefinite life.Noranda Mines Ltd. through its associate Norcast Division of Noranda Metal Industries formed a joint venture with the inventors to market magnetic mill linings in North America. For the past twelve months trials have been undertaken in conjunction with Orebed Inc. to test and develop these linings for grinding mill applications at the Horne Concentrator. Two independent milling circuits are currently being operated, one treating a siliceous gold ore and the other a copper slag.This paper presents the results of the magnetic lining test programme to date."

Jan 1, 1983

By P. Falcão Neves

A detailed analysis of the geomechanical behaviour in rock cutting with a diamond saw is provided to obtain a better understanding of the mechanisms involved in the process. The energy of elastic deformation (before failure) and plastic deformation (post failure) was determined in uniaxial compression tests as well as the energy consumed per unit volume in the cutting process. The test samples are White and Ruivina marbles from Borba - Vila Viçosa in Portugal. Correlations between total deformation specific energy and cutting specific energy, normal and tangential forces and diamond indentation are analysed, and some conclusions are presented.

Jan 1, 2012