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By S. Titkov

At present, Russia is engaged in processing, 3new plants of hard-to-process potash ores with increased content (up to 10 - 12%) of insoluble impurities (insoluble residue ? I.R.). This required additional research to improve the process of potash ores flotation. Based on the study of the effect of dispersive properties of frother and its flow rate on the efficiency of aliphatic amines with different length of the hydrocarbon radical (as sylvite collector) there was showed the possibility to apply high molecular amine with length of hydrocarbon radical C20 ? C26 by normal temperature of circulated plant salt solution (saturated solution KCl ? NaCl ? H2O). There was designed and tested in plant conditions the modified amine collector with the length of the hydrocarbon radical C16 - C26, improving flotation of Sylvite under normal temperature of circulating salt solutions at potash flotation plants. There was made the study of the influence of the hydrocarbon radical length of alkylmorpholine on the Halite flotation from intermediate products of sylvite recleaner flotation with different content of I.R. (silicate-carbonate slimes), at normal and elevated temperature of salt solution. On the basis of the application of modified alkylmorpholine for Halite flotation, there was developed the process of further beneficiation for the intermediate products of sylvite recleaner flotation from potash ores with increased content of insoluble impurities, which can eliminate the circulation of the intermediate products in the process flow sheet of sylvinite ore processing and increase the KCl recovery into the finished product. Keywords: flotation, potash, halite, alkylamine, alkylmorpholine

Sep 1, 2012

By Jason J. Crowder

Presentation Outline ? Introduction ? Costs of ground support and rehabilitation ? Why post-failure rock mass properties are necessary ? The Rock Mechanics Problem ? Present State of Modelling and Instrumentation in Mining ? Case Study Background ??Williams Mine ? Deriving Parameters for Modelling from Instrumentation ? Results from Case Study ??Back Analyses ? Discussion of Research Impact t Summary

May 1, 2006

By F T. Suorineni, L Baird, A Papaioanou, D Hines

The Mathews et al (1981) stability graph was developed to provide guidance in the determination of stope sizes to control dilution in bulk mining of large orebodies. Longhole and sublevel open stoping (LHOS and SLOS) are the lower end in scale of underground mass mining with panel and block caving (PBC) at the higher end. Currently, the stability states of stopes in the stability graph are described qualitatively as stable, unstable or cave. The alternative quantitative option to the qualitative stability graph is the Equivalent Linear Overbreak Slough (ELOS) stability graph. The ELOS stability graph only applies to narrow vein orebodies. It is easy for the Mathews et al (1981) and the ELOS stability graphs to be applied outside the limits of their databases. What is currently referred to as ‘stable’ in the present stability graphs has diverse interpretations at different mines depending on their acceptable dilution values. In 2014, a research program was conceptually conceived at the UNSW Australia School of Mining Engineering to develop a quantitative dilution-based stability graph independent of orebody width to address some industry concerns on the use of the stability graphs. A dilution-based stability graph provides the mining engineer the flexibility to determine open stope sizes based on what dilution amounts are acceptable. The graph also unifies both the Mathews et al (1981) and ELOS stability graphs for wide and narrow vein orebodies, thus, eliminating their potential misapplications. To date, the concept is proven with case studies from metalliferous underground mining operations located across Australia. This paper presents the dilution-based stability graph concept, the initial results and future plans to account for other critical factors and increase confidence in its application with the addition of more data outside Australia.CITATION:Suorineni, F T, Papaioanou, A, Baird, L and Hines, D, 2016. A dilution-based stability graph for open stope design, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 511–522 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By W. J. Miles

Many years ago, a relationship was established between dust inhalation and pneumoconiosis. Since then, various government agencies have regulated crystalline and amorphous forms of silica material in the workplace. In 1987, the International Agency for Research on Cancer (IARC) classified crystalline silica as a probable carcinogen. With this listing, crystalline silica became a regulated substance under the Hazard Communication Standard. The minerals and chemicals industries have responded in various ways. They have: • developed worker and user training programs and literature; • labeled products with appropriate warnings; • continued to implement dust reduction programs; and • developed meaningful epidemiological studies of workers. • begun development of reliable analytical methods for measuring crystalline silica at the 0.1 % threshold level; Background Silicosis historically has been the major health hazard resulting from exposure to crystalline silica. Silicosis is the scarring of the lung from excessive exposure to crystalline silica. It has been recognized as an occupational disease for more than 2000 years, since early Greek physicians noted the respiratory problems of miners, stonecutters, and quarrymen who were exposed to excessive quantities of mineral dust. During the industrial revolution, the incidence of the disease was greatly increased by the use of machinery that increased dust levels. Subsequently, the need for dust control was recognized and measures were instituted. Silicosis is characterized by progressive breathlessness on exertion and develops over the course of years. Xray images of the lungs show

Jan 1, 1990

By J. E. Friant

The Mini-DiscTM cutter drill bit is a radical design departure from the traditional tri-cone rockdrill bit. Miniature disc type cutting tools as small as 3.25 inches (82.5 mm) diameter are fitted to a bit body to cut individual concentric kerfs. The action is the same as that commonly used on large tunnel boring machines but miniaturized. The high performance rate and efficiency of a disc cutter are the result of producing a large proportion rock chips rather than sand or powder. The Mini-DiscTM drill bit, referred to as the “Disc Bit” has other unique features as well. It can be re-greased between runs. It can be rebuilt in the field in about 15 minutes, cutters can be replaced and the Disc-Bit appears to require less down hole hydraulic power than conventional bits. Thoroughly tested in the laboratory, the bit has recently been undergoing field trials in well drilling, blast hole drilling and shaft drilling. As any engineer knows, the laboratory can not shake out all the problems but it eliminates the more glaring weaknesses. Performance results have been exhilarating, and a few mechanical problems were discovered and largely overcome. This paper is a progress report.

Jan 1, 1999

By M. Melashvili

"The SART Process was introduced to the gold mining industry in the late 1990s and several commercial plants were built over the following 10 to 15 years. Most of these plants have operated well and enjoyed plant performance in line with expectations based on the underlying chemistry of the process. However, two of the plants have consistently suffered from high reagent consumption and poor product quality, which has motivated a re-examination of the process fundamentals in the hope of understanding the reasons for poor performance when it occurs, and developing mitigating strategies.This testwork along with a review of the relevant literature has demonstrated that the amount of sulphide added to the primary reactor, relative to the copper concentration, is the most critical parameter dictating plant performance, with pH and residence time important secondary factors. The primary product in the SART Process is synthetic chalcocite, Cu2S, and the stoichiometric requirement for sulphide addition is therefore 0.5 moles per mole of copper in solution. Testwork shows that when sulphide is added in excess of this amount (generally with the express purpose of lowering residual copper in solution) it not only fails in its intended purpose, but can have a negative impact on the settling and filtration characteristics of the copper sulphide product, as well as the final product quality. Moreover, these problems are exacerbated the higher the selected operating pH in the pH 3 to 5 range, and the longer the residence time of slurry in this pH range.Freshly precipitated copper sulphide compounds are known to be very fine and slimy, with poor settling and filtration characteristics. It is therefore important to engineer the SART Process in such a way as to encourage growth in the average particle size of the precipitate crystals. This was the rationale for recycling a portion of the thickener underflow to the primary reactor when the SART Process was developed. The theory of crystallization predicts that compounds of extremely low solubility, such as chalcocite (Cu2S: KSP = 10-48), are likely to experience growth in crystal particle size through aggregation rather than heterogeneous nucleation. On this basis, the SART practice of recycling a portion of thickener underflow to the primary reactor in the commercial plants is unlikely to lead to crystal growth via nucleation, and could in fact promote breakage of the aggregates that formed in the thickener. Recycling thickener underflow could therefore have the opposite of the desired outcome. The result of testwork that is reported here lends credence to this theory and questions the wisdom of recycling in the SART process.There is evidence to suggest that operating the copper sulphide thickener in the SART Process without flocculants may be beneficial. Thickener underflow densities could improve from the current 10 - 15% range to 40 - 50%. This will not only reduce the flowrate of slurry to the filter, but the filtration properties of the slurry (filtration rate, filter cake moisture content) will also improve. This is one of the most critical engineering and design aspects of the SART Process, and the achievement of high solids density in the thickener underflow will not only improve the health and safety aspects of the operation, but also has the potential to lower capital costs and improve the quality of the final product."

Jan 1, 2016

By S. H. Ward, R. A. Barker

THE Juniper Prospect is in Carleton County, N. B., at approximately 46" 31' north latitude, 67" 20' west longitude. During the summer of 1955 an area in west-central New Brunswick was selected for aerial electromagnetic prospecting with American Metal Co.'s helicopter-mounted equipment. Generalized, small-scale government geologic maps had suggested that this area was located along the western border of the northeast-trending granitic backbone of northwestern New Brunswick and might be underlain by the Ordovician-Silurian sediments and volcanics that are the host rocks for the recently discovered sul-fide deposits of the Bathurst-Newcastle district. The helicopter electromagnetic equipment located an anomalous conductive area, coincident with a small aeromagnetic closure, about five miles west of the town of Juniper. Subsequently 30 mining claims (total area about 6600 x 8000 ft) were staked and company personnel conducted geological, geophysical, and geochemical investigations on the property. The claims and immediately contiguous areas were mapped geologically, and an area of about 2000 x 4000 ft was soil-sampled and also surveyed by ground electromagnetic and gravity methods. Finally six diamond drillholes, totaling 3500 ft in length, were drilled to test the anomalous conditions discovered by the several exploration techniques used. The discovery of base metal sulfides during drilling was a technical success for the exploration methods, but the quantity of sulfides was too small to be profitably exploited.

Jan 1, 1959

The Bulli Seam, New South Wales, comprises medium to low volatile bituminous coal, generally of coking quality. It is worked over an area embracing 300 square miles.Variations in several factors are found.1. The seam is somewhat disturbed and dissected by various structural features.2. This structure, and present topography, have resulted in depths of cover from very shallow to approaching 2,000 ft in the presently worked areas.3. Wide variations of seam thickness occur.4. Gradations of rank occur from place to place.5. Variations in seam gas content and wide variations in seam gas composition are experienced.6. Variations in coal strength occur.These factors may contribute to the occurrence of stress and gas phenomena in mining exploitation.INTRODUCTIONThe Bulli Seam, the most extensively worked seam in Australia, is the uppermost seam of the Illawarra Coal Measures, which comprise the southern portion of the Sydney Coal Basin. Generally, the rank of the seam and its assemblage of types make it ideal for the production of hard metallurgical coke. The thickness and relatively flat dips render the seam suited to mechanized bord and pillar mining, and this method is used almost without exception. At the north-eastern corner of the field, stress and gas phenomena have occurred during mining.Various data have been assembled on physical, chemical and geological conditions of the seam which may influence the occurrence of stress and gas phenomena. This material is presented in an attempt to explain the location of such phenomena to date, and to enable variations in conditions to be considered when future possibilities are being assessed.

Jan 1, 1963

By Delahant A. B, Dworski M

From the Saranac Laboratory for the Study of Tuberculosis of the Edward L., Trudeau Foundation, Saranac Lake, New York:We are assembled to honor the memory of our friend and colleague, Donald Cummings, one of the founders and a past president of the American Industrial Hygiene Association. I deem it an Unusual privilege to have been asked to give this first memorial lecture and hope that what shall have to say may be worthy of the occasion. It is fitting that we should discuss here the subject of Silicosis to which he devoted such a large part of his life and it is doubly fitting, I think, that I should report to you an extended series of investigations carried on by his associates at the Saranac Laboratory.The subject of silicosis may seem hackneyed to this audience which is so familiar with the tried and accepted methods of prevention and control.But in spite of our efforts, the condition is still with us and unfortunately is still being produced in many places. In industries that now maintain good control of dust, fresh cases are appearing on annual re-examination, whose major exposure date back to the days before the hazard was recognized.A few new employees, with apparently ineffective upper respiratory protection against inhaled dust, develop silicosis precociously in environments that are comparatively harmless to their fellows. In plants that have relaxed their vigilance under the urgency of war production schedules, conditions again prevail that will produce, disease in the future.Silicosis acquired new interest with the announcement by Denny, Robson and Irwin(1) in 1937 that it could be prevented by the inhalation of powdered metallic aluminium. It so happened that without knowledge of their work, we at the Saranac Laboratory had for some months been conducting similar experiments with one of the hydroxides of aluminium.Quite independently we discovered that hydrated alumina would also protect animals against quartz. Our approach to the problem had been empirical; we were trying to neutralize quartz particles by coating their surfaces with an insoluble material following the lead of Kettle who in 1932 had shown that this could be accomplished with iron. He neglected to describe his method and the chemist who prepared his coated...

Jan 1, 1945

By R. Cao

Geostatistics was initially developed in the mining sector, but has been extended to other geoscience applications, including forestry, environmental science, soil science, and petroleum science and engineering. This paper presents methods, workflows, and pitfalls in using geostatistics for hydrocarbon resource modelling and evaluation. Examples are presented of indicator variogram analysis of categorical variables, lithofacies modelling by sequential indicator simulation and hierarchical workflow, porosity modelling by kriging and stochastic simulation, collocated cokriging for integrating seismic data, and collocated cosimulation for modelling porosity and permeability relationships. These methods together form a systematic approach that can be effectively used for modelling natural resources.

Jan 1, 2014

By G McMillan, P Mulvey

"Geochemical characterisation is done based upon the geology and metallurgical batch testing prior to commencement of the operation of the plant.  Tailings repository design is based upon geochemical assessment of the waste material, as well as the geomechanical issues associated with storing the waste. The resultant conceptual and detailed design is incorporated into the environmental impact statement (EIS), upon which mine approval is based. The entire environmental monitoring and harm mitigation program, which is usually a condition of the Mine Lease approval, is based upon the applicability of the original characterisation.Tacit to this process is that there is no change in the geochemistry of the tailings, i.e. no change in the implications for acid & metalliferous or saline/neutral mine drainage (AMD/SNMD) generation. But any changes in milling and processing can have a substantive impact on the geochemical behaviour of the tailings metallurgy, and potentially render an operation non-compliant within the conditions of the mine license.Environmental and statutory approval implications for continuous improvements of metallurgy need to be understood because unintended consequences could cost more than the benefits of the improvement, and in some cases cost more than all the profit made from the mine.  Examples uncovered during audit and consultant practice will be presented together with a process to ensure implications for adverse environmental harm and license conditions are fully considered.*This paper is only available for individual download. It is not included in the conference proceedings*CITATION:Mulvey, P, 2013. Continuous improvement - how changes in metallurgy can have a substantive impact on environmental impact and closure - lessons learnt from environmental auditing, presented to MetPlant 2013 Conference (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

The Tasman Orogenic Zone is regarded as a single metallogenic province (the Tasman Province) with four SUb-provinces corresponding with its major tectonic components: the Lachlan, New England, Hodgkinson.and North Queensland orogenic provinces. Within the Tasman Province there are four main ore-rock associations.These are1. manganese and iron with sedimentary and basic volcanic rocks,2. zinc-lead-copper and copper with intermediate-acid volcanic sequences,3. minor chromium, platinum, and osmiridium with ultramafic complexes, and4. tin, wolfram, gold, and copper with syn- and posttectonic granitic intrusions.Whereas the ores of ultramafic and volcanic associations form geographically-restricted metallogenic districts, the ubiquitous granitic ores may be subdivided into twenty-one districts that cover almost the entireOrogenic Zone. The Tasman Province is notably lacking in uranium ores and Mississippi Valley-type deposits.There is a distinct tendency for ores of each association to be progressively younger to the east and north, thus paralleling the progressive growth and stabilization of the Zone. Similar ore-rock associations are present in repeated phases of mineralization from the Cambrian to the Permian-Triassic, reflecting the essential homogeneity of the Tasman Province, and the similarity of the successive tectonic cycles.

Jan 1, 1972

By Sharpe E. J

The Triton lode is a schistose feldspar biotite chlorite rock with quartz, carbonate, pyrite and some pyrrhotite. Its more chloritic sections strongly resemble the enclosing greenstones, its more feldspathic portions are indistinguishable from the flne-grained phases of the porphyry dyke into which the southern extremity of the ore body merges. The ore body' has a length of 880 ft. and an average width of I2t ft.; in places this widens to as much as 30 ft.The average dip is 85° west and pitch of the ore shoot 75° south.METHOD OF SAMPLING.With the exception of a limited amount of channel sampling (a reference to which is made elsewhere in this paper) all the sampling is by chip sample.The samplers use a hammer weighing approximately 11 lb. and chip directly into the sample bags. Sampling is generally carried out over 3-ft. sections and portions thereof to the nearest half foot-thus a face 8t ft. wide is divided up into two sections of 3 ft. each and one section of 2 ft.-no measurements of less than 4 ft. are used and calculations are all in feet and dwt. per long ton.In the oxidised stopes wp.ere the lode is much narrower, .i.e., 6 ft., sampling is over 2-ft. sections. All borehole samples are over 2-ft. sections, this corresponding approximately to steel changes.(a) DEVELOPMENT SAMPLING.Driving.-This is done by following the east wall and each face is sampled-this corresponding to an advance of 5 ft. If the full width o,f the lode is not exposed boreholes...

Jan 1, 1938

By D Brooks, S Gunn, T Perkins, J Siliezar

Ernest Henry Mining (EHM) is a copper, gold and magnetite mining and processing operation located 38km north east of Cloncurry. The EHM ore body has an average grade of 0.9% copper (chalcopyrite), 0.5g/t gold and 22% magnetite.Open pit mining commenced in March 1998, but EHM transitioned to underground mining in December 2012, extending the life of operations beyond 2024. The underground mine currently produces up to 3Mt/year of ore, hauled up a decline by truck. This figure shall double in 2014 with the completion of a 1000m shaft. The EHM Concentrator has a nameplate capacity of 10Mt/year. In June 2011, Xstrata Copper acquired the Mount Margaret resource to supplement underground production and utilise the full capacity of the Concentrator. The Mount Margaret Mining (MMM) operation was established to develop the five deposits making up the resource by way of open pit mining.Copper concentrate is produced by the EHM Concentrator via grinding, flotation and dewatering circuits. The grinding circuit comprises a SAG and ball mill in a closed AB configuration. Flotation consists of a rougher train, regrind and three stages of cleaning, with the tail from the first stage reporting to the tailings thickener.The mineralogy of the MMM ores is complex, comprising fine textures of active pyrite, copper oxides, native copper, clay and secondary copper sulphides. This paper provides an overview of the metallurgical test work completed to forecast the performance of the MMM ores through the EHM Concentrator and identify flow sheet modifications for maximising copper recovery and producing a saleable concentrate. A discussion of the challenges experienced in the plant to date follows.CITATION:Gunn, S, Siliezar, J, Brooks, D and Perkins, T, 2013. Adapting the Ernest Henry Mining concentrator to process the Mount Margaret ores, in Proceedings MetPlant 2013 , pp 347-370 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By A. Fuerst

The recent seismic events have shown that earthquakes have an immense destructive power. Chile was hit in February 2010 with a seismic intensity of 8.8 on the Richter scale, and had loss of about 700 killed persons, while Haiti was hit in January 2010 with 7.0 killing about 220?000 people. The event in Haiti showed that the seismic events can lead to a disaster if no preventive measures are taken. On the other side, the seismic event in Chile has hit a well-prepared country with moderate consequences. The earthquake with 6.6 Richter in Japan in March 2011, have further shown how severe the consequences can be if critical equipment is involved. Fortunately, the equipment in a mine has not the potential hazard as a nuclear power plant. Anyway, we are diligent and it is obvious that the seismic risk may lead to a real disaster even if the probability is small. The GMD is an important component in the grinding circuit of a mine. This paper maps out earthquake-prone areas including expected earthquake magnitude calculated according to relevant standards, focusing mainly on the building code IBC 2009. An overview is provided on how this standard is applied to mining equipment to minimize damage and aid large mills in operation to successfully withstand seismic effects. The differences in stresses and forces on the GMD and foundation are shown based on a turning and stopped mill simulation during an earthquake. The results demonstrate the need to maintain active and operating earthquake detection systems. Aside from detecting an earthquake?s magnitude, the sensor information can also be used to reduce the harmful effects that an earthquake has on mining equipment. As follows the earthquake requirements are defined. The last part of this paper explains how to fullfill these requirements.

Jan 1, 2012

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By J. M. Davidson

The potassium mineral polyhalite (K2SO4.MgSO4.2CaSO4.2H20) found in large deposits in western Texas and southeastern New Mexico is associated with varying amounts of halite (sodium chloride, NaCl) and anhydrite (calcium sulphate, CaSO4). Although the anhydrite, because of its low solubility and slow rate of solution, is relatively inert, the halite is dissolved immediately in any process solution with which the polyhalite comes in contact. Limited quantities of sodium chloride in the liquors used for the hot extraction of polyhalite materially improve the results obtained,4 but only a very small sodium chloride content may be desired in the entering polyhalite in other procedures, such as Bureau of Mines process 75. In. all of the processes suggested for the recovery of potassium sulphate from polyhalite the control of the sodium chloride content will be desirable, if not absolutely essential to efficient operation. OCCURRENCE OF HALITE IN POLYHALITE A preliminary estimate of the amount of halite associated with typical deposits of polyhalite may be derived from drill cores, although it should be remembered that only 50 or 60 core tests have been made in the many hundreds of square miles of the Permian basin. From a mineralogical study of 41 of these cores, Schaller and Henderson6 state: In many of the sections of core that seem when viewed by the unaided eye to consist essentially of polyhalite, both halite and anhydrite are present in greatly varying quantities - with very minor quantities of clay and magnesite.

Jan 1, 1934

By Stewart A. Silling, Dale S. Preece

The two key results of rock blasting are fragmentation and movement of geomaterials. Movement/flow of the blasted rock is often referred to as heave. Modeling the movement of full scale blasting is now possible with 3D distinct element models and parallel processing.

Jan 1, 2016

By E. J. Dulis, A. Kasak, R. C. Westgren

The potential of uirought tungsten- and tantaluw-rich alloys of the W-Ta-Mo-Cb system was investigated for high-strength structural applications above 2500° F. Appreciable strengthening of tung-sten and tantalum—essentially attributable to solid-solzction effects—was obtained with binary, ternary, and quaternary alloys. Tensile strengths as high as 67,000 psi were achieved at 3000 OF. ThE quest for wrought structural materials which possess good strength properties at temperatures above 2000°F has led to a considerable research effort during the past decade. In addition to exploring the potential of various high-melting-point refractory metals (such as molybdenum, columbium, tantalum, and tungsten) for very high-temperature structural applications, alloy-development programs have been undertaken to achieve greater strengths than could be achieved with unalloyed refractory metals. The methods of strengthening refractory metal alloys have included both solid-solution and dispersion strengthening. General relationships among the relevant properties (melting point, recrystallization temperature, and high-temperature strength) of refractory metals indicate that the highest strengths at temperatures of 2500°F or higher would be obtained with tungsten-or tantalum-base alloys. Therefore, the present investigation was undertaken to determine the high-temperature strength potential of solid-solution strengthened alloys based on the binary system W-Ta; to effect further strengthening, minor additions of molybdenum and columbium (at the 6 and 12 pct levels) were made. The portion of the W-Ta-Mo-Cb quaternary alloy system of interest is shown schematically in Fig. 1. The component metals—W, Ta, Mo, and Cb—have a bcc structure at all temperatures, and their binary systems are mutually completely soluble.' Complete solid solubility in the W-Ta-Mo and W-Ta-Cb alloy systems has been demonstrated,' and, therefore, it was expected that the quarternary alloys of the system would also exhibit complete solid solubility at all temperatures. In the virtual absence of contamination by interstitial elements, all the alloys would be truly solid-solution strengthened. Twenty specific compositions of this investigation included binary, ternary, and quaternary alloys of the W-Ta-Mo-Cb system as well as unalloyed tungsten and tantalum. The compositions are shown in Table I. EXPERIMENTAL PROCEDURE Consumable-electrode vacuum-arc melting with ac power was used to produce small laboratory-sized, cylindrically shaped ingots (1-1/4 in. in diameter and 2 to 3-1/2 in. long) of the twenty compositions. A furnace was specially constructed to melt as many as four electrode rods simultaneously into molds lined with tungsten or tantalum sheet. High-purity rods of tungsten, tantalum, molybdenum, and columbium were used for consumable electrodes; the diameter of each rod was determined by the desired weight percentage of the component metal in a given alloy. The details of the construction and operation of the melting furnace will be discussed in another p~blication.

Jan 1, 1964

By M. Dworzanowski

The physical beneficiation of iron ore that has a wide particle-size distribution is problematic, regardless of the process applied, whether dense medium separation, gravity concentration, magnetic separation, or flotation. The problem of particle size is further compounded when there is a significant -10 µm fraction. Generally the approach to a wide particle-size distribution is to split into narrower size ranges and treat each separately. More often than not the -10 µm fraction is not treated but discarded. This approach results in a more complicated and expensive flow sheet and the loss of any potential value in the -10 µm fraction. Wet high-intensity magnetic separation (WHIMS) bench-scale test work was conducted on a haematite-rich material with a particle size of -200 µm. What made this material different was that it contained a 60% -10 µm fraction, hence discarding the -10 µm material was not an option. The objective of the test work was to determine how to maximize the recovery of the haematite across the full particle size range. Given the unusual particle size distribution, it was concluded that WHIMS would be the only practical beneficiation route. The -200 +10 µm and -10 µm fractions were treated separately and together under varying WHIMS conditions. For a given concentrate grade, the mass yield obtained was greater when the total particle-size distribution was treated. The inferred optimum conditions, using the same material, were tested on a pilot-scale WHIMS and similar results were obtained.

Jan 1, 2014