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By D van der Merwe

Tracers of known densities are used world wide in coal processing plants to evaluate plant performance. Tracers are added to the feed stream and are counted after being recovered from the product and discard streams to determine partition curves. The need to recover the tracers can be eliminated by adding radio frequency identification tags to the tracers. Readers mounted on the product and discard streams record the passing RF tracers and produce the partition curve instantly. Tests were performed with three different shaped tracers at different collieries on cyclones ranging from 510mm to 800mm in diameter. Sink and float analyses of coal samples were used to compare conventional partition curves to partition curves obtained by using RF tracers. The average amount of tracers recorded was 78% of tracers in the feed. The results indicate that the stone shaped tracers represent the results from the sink-float analyses the best. The results suggest that RF tracers can be used to evaluate cyclone circuits in the coal industry and will make it possible to evaluate a coal circuit?s efficiency without stopping a plant and waiting for laboratory analyses. Keywords Coal tracers, partition curve, radio frequency tracer, RFID

Jan 1, 2006

Ladies and gentlemen, distinguished guests and fellow members of The AusIMM, good morning.   Thank you for the opportunity to address you all today, Crown Minerals are very pleased to be associated with the conference again this year, and I commend the committee on their organisation and delivery of this yearÆs event.   As you can see from the topic of my discussion, I would like to broach the subject of collaboration between ourselves û Crown Minerals û and you our clients, and convince you that we are on the right track but can each do more.

Jan 1, 2007

By I. C. L. Webster, G. E. Ray

"The magnetite-rich Heff Cu-Au skarn lies in the Quesnel Terrane of south-central British Columbia, approximately 26 km northeast of Kamloops. The skarn formed close to the northern margin of the Heffley Creek pluton, and is hosted by Carnian (Late Triassic) Nicola Group limestone. The Late Triassic pluton (208.1 ± 6.1 Ma, U-Pb zircon) is a composite body of alkaline affinity that includes dioritic, gabbroic, and magnetite-rich clinopyroxene ± olivine ultramafic phases.The skarn has been discontinuously traced along strike for more than 1 km, and individual skarn layers are up to 40 m thick. The most common non-opaque minerals are garnet, clinopyroxene, and carbonate, with lesser epidote, biotite, amphibole, and chlorite. Apatite locally forms more than 3 vol.% of the rock. Compositionally the garnet is a low Mn grandite averaging Pyr3-Grs41-Adr56 mol.%.Mineralization consists of lenses, up to 10 m thick, containing massive low Ti-V magnetite (avg. 0.03 wt.% TiO2 and 0.01 wt.% V2O3). Magnetite is associated with up to 20 vol.% pyrrhotite, lesser pyrite, and trace chalcopyrite and gold. There is a moderate enrichment in rare earth elements with assays up to 570 ppm La and 490 ppm Ce. The Heffley Creek pluton belongs to a suite of Late Triassic-Early Jurassic alkalic and Fe-rich intrusions that are widely developed throughout the Quesnel Terrane. Some host Cu-Au porphyry mineralization, but less commonly they are associated with magnetite-apatite veins such as at the Glen Iron mine and Magnet occurrence, or with magnetite-rich Cu-Au skarns such as the Heff occurrence.Although abundant low Ti magnetite is present in the Heff skarn, it does not appear to represent iron oxide copper- gold (IOCG) type mineralization. Microprobe analyses completed during this study show that low Ti magnetite is not a unique feature of IOCG deposits, but also characterizes some other types of hydrothermal mineralization. In British Columbia these include some alkalic porphyry-related magnetite-apatite veins in the Quesnel Terrane, as well as the well-known Wrangellia-hosted Fe skarn deposits. Thus, low Ti magnetite appears to be a common signature of many magmatic hydrothermal deposits in contrast to the high Ti primary magnetite found in most igneous rocks."

Jan 1, 2007

By Robert A. Westin

Polychlorinated Biphenyls (PCBs) have been widely used as fire resistant dielectri coolants in electrical equipment used in mining applications, including transformers capacitors, electric motors, and electromagnets. In addition, PCBs have been used in hydraulic fluids and heat transfer fluids, and are present in many oil filled transformers. The Environmental Protection Agency recently banned the manufacture of PCBs and equipment using PCBs, and imposed strict requirements on the continued use and disposal of existing PCB equipment. This manual discusses the EPA requirements, suggest ways to decrease the risks resulting from continued use of PCB equipment, and surveys the non-PCB equipment that is available as replacements for the PCB electrical equipment presently used in mines.

Jan 1, 1979

By K. Zabrusky

Estimation of high grade epithermal vein deposits can present challenges in correctly representing the continuity of grade within an undulating structure. One solution to this problem is to use dynamic anisotropy to follow local variations in the strike and dip of veins. Dynamic anisotropy (D.A.) allows the search parameters to change block by block throughout the model to account for the local variations. Presented here is a study of a vein that changes orientation down-dip. A traditional resource estimate using one search ellipse orientation was performed. The resulting estimated grades did not accurately reflect those of the sample data. Using a search ellipse with an average value for the two distinct dips caused the grade estimation to be less representative than desired. Rather than performing domain-based analysis with different search ellipses, the issue was corrected by using Datamine Studio 3?s D.A. function. The 3D vein trend was used to estimate the dip and dip direction of the vein in each block. The resulting D.A.-estimated model follows the two dip trends of the vein. This software makes a previously tedious task faster, and allows for more accurate estimations.

Feb 27, 2013

In 1962, minerals beneficiation showed definite signs of coming out of the doldrums into which it has drifted after the uranium boom. Demand by steelmakers for high-grade iron pellets has created the need for concentrating plants to upgrade specular hematite by spiral concentration or flotation and magnetites by magnetic means and flotation. According to a paper given at the AMC annual meeting by C. S. Arms of Pickands Mather, "the shipment of pellets, started in the mid-1950's, has increased to 17.6 million tons in 1961 from North American operations. Many plants already underway will raise this production to about 42 million tons by 1965. This will be a very sizeable percentage of the total iron ore production contemplated by that date." Iron ore concentration methods are gradually raising the assay of pellets into the 65 to 69% Fe range and lowering silica to the 4 to 7% range. Quebec Cartier's Lac Jeannine concentrator went into operation in late 1961 and all grinding units were running by 1962. The Iron Ore Co. of Canada's new Carol Lake plant was started in mid-1962.

Jan 2, 1963

By T. A. Klinefelter

KYANITE and the related minerals sillimanite, andalusite, dumortierite, and topaz are natural aluminum silicates that can be used in production of mullite (3A1203?2Si02), a superduty refractory material. Kyanite and sillimanite are the dominant ones because of their greater abundance. The only other kyanite-group mineral presently used for mullite production is andalusite. Mullite is not an absolutely essential material as other refractories can be used in the same heat range. However, it is a highly satisfactory one. It is the only compound of silica and alumina that is stable at high temperatures. It has low thermal expansion and is very resistant to corrosive melts and to thermal shock. For these reasons mullite refractories have a much longer life than standard fire-clay refractories under the same conditions. Worldwide, excluding U.S.S.R., the refractories industry consumes about 150-000 short tons annually of kyanite group minerals and synthetic mullite.

Jan 1, 1961

Thickener Modelling - Incorporating Shear Effects

Sep 13, 2010

By T Do, J Siliezar, M Larson

With the expansion of magnetite projects in Australia has come the opportunity to take advantage of newer technologies that were not necessarily available when the magnetite industries of North America and Europe were maturing. One of these technologies is the IsaMill, originally developed for the economic treatment of ultra-fine grind (UFG) duties of Mount Isa Mines. As understanding of the IsaMill has increased, so too has the ability to process coarser feeds while maintaining the same energy efficiency advantage and tight product size distribution that originally made the IsaMill so attractive. In the case of magnetite the hard non-elastic ceramic grinding media is ideally suited to the grinding duty when compared to steel grinding media. The centripetal separator and naturally steep product size distribution curve provide a mill discharge that maximises the critical concentrate grade. This paper analyses the effect of the IsaMill grinding technology on the full-scale Ernest Henry Mine (EHM) magnetite operation along with pilot and lab scale demonstrations of optimisation. Issues encountered and the solutions to maximise the mill throughput and quality are examined in an effort to promote better understanding across the industry. CITATION:Larson, M, Do, T and Siliezar, J, 2013. Enhancing magnetite returns - the benefits of IsaMilling, in Proceedings Iron Ore 2013 , pp 411-416 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By P. L. Swanson, F. M. Boler

The U.S. Bureau of Mimes conducts research at the Galena Mine, Wallace, ID, with the aim of mitigating the effects of rock bursting. Destress blasting is commonly used as a stress control technique at the mine. A digital seismic array and an array of borehole pressure cells (BPC's) had been installed near the site of a stope undergoing mining and periodic destressing. The instrumentation was being monitored at the time of a destress blast of the 46-99 stope. No significant seismic events occurred coincident with the destress. However, the destress was followed by a 21/2-week period of increased seismic activity, including two damaging events on February 7, 1990, at 034500 (hour, minute, and second) and 122020 Pacific standard time. BPC measurements indicated coseismic ground pressure changes on the order of 200 to 300 kPa associated with the damaging events. Fault plane solutions and dislocation models established that stress changes induced by the event at 034500 may have been significant in promoting the occurrence of the event at 122020. Theoretical investigations suggest that applying knowledge of the existing stress field, an understanding of rock burst mechanics, and fracture mechanics principles can improve destress effectiveness.

Jan 1, 1993

By E. P. Youngman

Titanium ranks as one of the more abundant elements, is widely distributed, and occurs in concentrated form in numerous deposits. This substance was discoveres 140 years ago; but despite the efforts of metallurgists and chemists to find a place for it in industry, only within the last 10 or 15 years has the increased use of titanium pigments provided any extensive outlet for titanium ores. Even to-day titanium is confined to a few highly specialized industrial applications. The metal itself is now quoted regularly in trade journale, but scarcely yet can it be said that the production or use of the metal. has progressed very far beyond the laboratory stage. Ferroalloys containing the element were largely used for a time, especially in connection with the manufacture of Bessemer steel rails; but as American rail- ways adopted open-hearth rails in preference to Bessemer rails, the demand for the alloys in the rail manufacture gradually dwindled into insignificance. New outlets for ferrotitanium have been found in the steel industry; and the production of titanium alloys, both in the United States and in Europe, has increased in recent years. By far the largest use of titanium at the present time, however, is in pigments. The manufacture of titanium white began in Norway, but at present the United States is the leading producer. One of the two companies now operating in the United States is also the leading factor in European production. Although titanium occurs, in many minerals, the principal commercial sources are rutile (the natural oxide, Ti02) and ilmenite (iron-titanium oxide, FeO. TiO2). The latter is a coal-black mineral, but it is the one used in the manufacture of the titanium white of commerce, as well as in the manufacture of ferroalloys and arc-lamp electrodes. Rutile, the natural oxide, is not pure white and, being less common in nature, costs more; it is, therefore, reserved for use in the manufacture of titanium chemicals employed in relatively small amounts in dye works and bleacheries and for sundry minor purposes. This paper summarizes the titanium industry, with special reference to its economic aspects. It is offered as a survey of current trade literature and as a digest of material in the files of the bureau and is presented in response to numerous inquiries from prospective producers as to ways and means of exploiting deposits. (At present, much of the ilmenite consumed in this country comes from overseas, principally from British India..). A forthcoming circular, devoted to deposits of titanium-bearing ores, deals with foreign and domestic sources of supply.

Oct 1, 1930

The mineralogy, textures, and genetic significance of a silver-rich siderite vein and an apparently co-genetic galena vein from the South mine, Broken Hill are discussed.Both veins cut sharply across the Main Lode Horizon and appear to be coeval with thc A.B.H. Consols lode.The minerals of thc siderite vein apparently result from the preferential leaching of silver from Main Lode Horizon ore with a demonstrable "breakdown series" commencing with tetrahedrite, passing through silver sulpho-salts, and ending with simple binary compounds or with elemental silver.The siderite vein has been deposited by metahydrothermal fluids along the lines of Schneiderhohn's "secondary hydrothermal" mineralization.

Jan 1, 1968

By M. G. Zabetakis, T. D. Moore

The use of a partially slotted 6.5-inch-inside-diameter vertical pipe to remove methane from a longwall gob area at a depth of 2,260 feet in the Pocahontas No. 3 coalbed ms investigated. The value of gas removed by such a pipe under free-flow conditions was found to equal the cost of the installation in this case. Approximately 25 percent of the available methane passed through the pipe without the use of an exhauster; an additional 10 percent was removed when an exhauster was employed. The diversion of methane through a vertical slotted pipe to the surface permitted the use of increased mining rates and decreased the ventilation air requirements.

Jan 1, 1972

By Dennis W. Boehm

The building boom of the late 1970's and early 1980's has all but used up most of the better sites across the more populated metropolitan areas of the United States. This means that current buildings and other types of structures are being founded on more marginal sites. The use of marginal sites has placed ever-increasing quality control on the installation of the deep foundation systems utilized for these sites. Several remedial techniques are available for the repair of the deep foundation systems. These include minipiles, compaction grouting and jet grouting. Eight case histories are cited where these methods have been utilized to repair deep foundations.

Jan 1, 1999

By P. Scinto, A. Festa

"Orway Mineral Consultants Ltd (OMC) as a consultancy has specialized in comminution circuit design for over 30 years. The OMC Power Model is OMC’s in-house software for specific grinding energy power-based circuit calculations. The model uses ore hardness parameters from testwork, circuit configuration, equipment geometry and operating conditions as inputs. The model combines proprietary and published power models to predict the total specific energy and the specific energy for each of the components of the comminution circuit. This makes the software a valuable tool for the design and validation of JKSimMet modelling or actual plant performance. Proprietary calculations have been developed and reconciled with over 100 plant benchmark projects encompassing a variety of comminution circuit configurations.This paper describes the OMC approach for determining power requirements for the design of grinding circuits. The accuracy of the OMC Power Model software is confirmed through plant survey benchmark performance and comparisons are made with other power modelling techniques. Practical examples are presented, showing applications for single stage SAG (SS-SAG), SAB and SABC circuit configurations.IntroductionConventional low throughput grinding options, consisting of multi-stage crushing followed by rod and ball mills, have almost become obsolete in the move to higher milling rates required to process lower metal grades. Grinding circuits with fully autogenous (AG) or semi-autogenous (SAG) mills, often combined with ball mills are now the standard to meet the high capacity requirement for processing ores with lower metal grades. Simulation software and power-based equation methodologies have been established for designing AG/SAG based grinding circuits and predicting their energy requirements.Presently, power-based equations remain the principal method for designers to size mills and estimate the power requirement for comminution circuits. The technique is simple and it relies on the design to specify a feed and product size plus a hardness index to produce a specific energy value (kWh/t). The desired throughput of the mill is multiplied by the specific energy to give the mill power requirement, which is used in turn to size a mill for dimensions, internal geometry and loading conditions to match the power draw."

Jan 1, 2015

By M. G. Senyur

This study aims at investigating the structural characteristics of backfilling material. In this regard, spatial arrangement of solid particles and associated voids in a unit mass of coal mine refuse as backfilling material were tested. The materials were produced from coal mine refuse of Zonguldak Colliery, Turkey. The experimental procedures were developed to determine their void ratio (or its equivalent porosity), bulk density and the shape properties of constituent particles. The orientation fabric and the co-ordination number were the other two fabric elements determined. The filling materials were sieved and their particle size distributions were found. The results obtained by experiments were related to the particle size distribution parameters, namely, the coefficient of uniformity and the effective size. It was concluded that mean value of void ratio is correlated with coefficient of uniformity. The standard deviation of porosity as an index of fabric heterogeneity is clearly correlated to effective size. By an original experiment, the frequency distribution of coordination number was observed as binomial in uniformly graded materials. Also, the co-ordination numbers of test mixtures were calculated by the Marsal method and results obtained showed a good correlation between the minimum particle size and number of contacts per unit area.

Jan 1, 1998

By T. T. Tomimatsu

[This Bureau of Mines paper investigates explores, and analyses the Corporate structure dynamics and Rancid role to evaluate the economic health of the U.S. copper producers. It highlights the Corporate policy options and measures of corporate profitability and suggests that a competitive domestic copper industry will exist in the future. The study highlights the activities of 14 selected major copper-producing companies, including their subsidiaries o affiliates, that were responsible for more than 95 percent of the total U.S. production in each of the years since 1969. The selected firms are hot all primarily in the business of producing copper. Several of the large producers are classified by the financial institutions as integrated oil and gas enterprises.]

Jan 1, 1980

By S. P. Godby, S. P. Sharples

Wind-tunnel tests were carried out of the conditions under which nuisance dust particles (100-1 000 micrometres) become entrained by wind. A laser entrainment monitoring system (LEMS) was used, and was found to provide an accurate means of assessing nuisance dust emissions from a surface. Accurate determination of the threshold entrainment velocity of dusts using the LEMS gives a baseline against which the performance of dust control techniques can be evaluated. Minerals tested included coal, petroleum coke, limestone, sand and pulverised fuel ash. Pilot field trials of a portable wind tunnel equipped with the LEMS have been successfully completed, providing a means of validating laboratory results in the field

Jun 19, 1905

By A Rantala, K Aberkrom, O Haavisto, P Blanz

More complex ore bodies with lowering grades increase the challenges of maintaining high throughput, energy efficiency and required particle size for optimal downstream processing in grinding circuits. Continuous and often rapidly changing characteristics of the mill feed requires constant focus to operate the circuit at optimal level. Modern process instruments, on-line analyzers, monitoring and process control systems provide attractive and managed options to increase the circuits’ capability to respond to the challenge, often in phases and in rather short time period. Furthermore, well instrumented and performing base level automation in the grinding circuit enables advanced process control (APC) strategies that utilize measurements from the whole circuit to stabilize and optimize production. In this paper alternatives for incorporating process measurements and controls to typical grinding circuits are proposed. The expected benefits to throughput, availability, energy efficiency and particle size stability are described in recent case examples.CITATION:Rantala, A, Blanz, P, Aberkrom, K and Haavisto, O, 2015. Increasing grinding circuit robustness with advanced process control, in Proceedings MetPlant 2015, pp 129–141 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

An examination is made of some of the consequences of a magmatic gas phase developed during a late stage of differentiation of an acidic magma. Elements possessing halides with high partial pressures (Sn, Mo, W) may be removed from the magma by distillation into gas bubbles in the manner suggested by Fenner (1933). The common chalcophile elements are not affected by this mechanism, but form sulphides which may become attached to rising gas bubbles by one of three distinct mechanisms. The gas bubbles may then carry the sulphides upwards and concentrate them in some favourable locus, giving rise to an ore-forming fluid. The process would operate selectively upon different sulphides and is capable of providing an explanation of the paragenetic succession observed in ore deposits as well as other important geological criteria of ore genesis.INTRODUCTIONThere is a widespread belief among contemporary geologists that a large and important class of ore deposits is genetically related in some way·to acidic igneous rocks. This class includes the tin-tungsten-molybdenum-bismuth type of mineralization as well as a variety of sulphide deposits.A basic problem confronting explanation of the genesis of these deposits is the manner in which trace elements which were originally widely dispersed in granitic magmas were segregated therefrom and concentrated into economic mineral deposits.The principles underlying the formation of one group of minerals deposits (pegmatites) related to granitic magmas ate reasonably well understood, largely due to the labours of Goldschmidt and his school. However, many geologists have noted that there appears to be some sort of fundamental discontinuity between pegmatite formation and the origin of the more common hypogene ores, particularly sulphides.Accordingly it has been suggested that these ores...

Jan 1, 1956