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Infacon 74 Members are reminded of the International Ferro-Alloys Congress that is to take place in Johannesburg between 22nd April and 1st May, 1974. The Congress is being held jointly by the National Institute for Metallurgy, the Ferro Alloy Producers' Association of South Africa, and the South African Institute of Mining and Metallurgy. Correspondence and enquiries should be addressed to The Secretary, Organizing Committee, INFACON 74, Private Bag 7, Auckland Park 2006. The gold deposits of the farms Lisbon and Berlyn in the Eastern Transvaal by v. c. H. R. BRERETON. Published in the Journal November 1973. AUTHOR'S CORRECTIONS The following amendments should be made.

Jan 2, 1974

This paper describes the operating practice and design features of an intensive-cyanidation plant at the East Gold Plant of Vaal Reefs Exploration and Mining Company Limited (V.R.E.M.). After the development oh cyanidation route for the treatment of gold-plant gravity concentrates by the Anglo American Research laboratories (A.A.R.L.), a full scale plant was commissioned at Western Holdings (Welkom Division) Gold Mine in March 1977, and the V.R.E.M. plant was commissioned in August 1981. Although the gravity-concentration route does not now enjoy the prominence of former times, in an existing conventional plant the intensive-cyanidation route can successfully replace mercury amalgamation.

Jan 1, 1984

By C. T. Connor, O&apos

The fifth University of Cape Town (UC1)/University of Stelenbosch (US) Minerals Processing Symposium was held at the Faculty of Engineering, University of Stelenbosch on Friday, 8th August, 1986. This series was initiated in 1982, the symposia being held alternately in Cape Town and Stelenbosch. The South African Institute of Mining and Metallurgy has kindly agreed to sponsor this event for the next three years. Cokemaking On the initiative of the European Cokemaking Commitee, the First International Cokemaking Congress will be held in Essen (F.R. Germany) from 13th to 19th September, 1987. It is being organized by the Steinkohlenbergbauverein, together with the Verein Deutscher Eisenhitenleute.

Jan 1, 1986

By P. H. Botha

An account is given of the procedures used by the South African Iron and Steel Industrial Corporation (Iscor) for tests on the flotation of coal fines, and some of the beneficiation problems encountered with coal from Durnacol, Grootegeluk, and the Soutpansberg area are discussed. These, and other South African coals differ from overseas coals in that they contain a high percentage of fixed ash, which means that they have to be crushed more finely for liberation and that they then contain more fine material (smaller than 0,84 mm). In addition, the coal from the three areas mentioned occurs in fine layers and seams, and contains many intergrown particles.

Jan 1, 1980

By R. J. Mostert

The role of hardenability in the development of high-strength low-alloy (HSLA) steels is discussed. The applicability of the superhardenability treatment. a steel making technique for increased hardenability, to HSLA steels is indicated, and the literature on this treatment is reviewed. Several low-carbon superhardenability HSLA steels were designed by use of published superhardenability multiplying factors. It was found that the hardenability of these low-carbon steels can be increased to the same extent as that of medium-carbon steels. The mechanical properties as determined in normalized bars indicate that the superhardenability treatment can be used successfully in the production of low-carbon hot-rolled HSLA steels.

Jan 1, 1984

By I. J. Barker, D. A. Vetter, G. A. Turner

The modeling of the uranium-leaching process, and the logging of data from a plant for the evaluation of the model, are reported. A phenomenological approach was adopted in the development of the model. A set of eight chemical reactions was chosen to represent the complex chemistry of the process, and kinetic expressions for these reactions were incorporated in differential equations representing mass and energy balances. These equations were coded in FORTRAN to form a program that simulated the process, and that allowed averaged and continuous data from the plant to be compared with the model. This allowed the model to be 'tuned', and to reveal a number of minor

Jan 1, 1989

PREFACE During the past year, considerable effort was devoted to the implementation of the strategic plan that was adopted by the SAIMM in 1986. Good progress was made in a number of areas, while in others the foundation was laid for future progress. Key Objective of the Institute The key objective of the SAIMM is as follows: To identify the needs of its members and to initiate and give effect to the means whereby the requirements for technology and scientific knowledge of the minerals and metals section of the South African economy are satisfied; and to represent and promote the interests of its members.

Jan 1, 1987

By M. J. Nicol

This paper ,examines the kinetics of the extraction of uranium from acid sulphate solutions by strongbase anionexchange resins. Parameters such as the concentration of uranium in solution. the agitation of the resin beads in solution. the size of the resin beads. and the degree of cross-linking within the resin matrix were varied. and the effec ts on the kinetics are reported. The applicability, of various empirical kinetic models to the description of the data is assessed, and an attempt is made at the modelling of the rate data in terms of established theories about the diffusion of ions through films of stagnant liquid and through spherical beads of resin.

Jan 1, 1980

By K. R. Noble

The planned extraction of the No. 1 shaft pillar at Blyvooruitzicht Gold Mine highlighted a number of potential problems. In spite of the relative shallowness, careful thought had to be given to stope phasing owing to the detrimental effect of the anticipated geology and the fact that uninterrupted hoisting was necessary. Extensive use was made of computer modellig to design the stope phasing, determine the influence of regional support and to predict the direction and magnitude of displacements in the shaft. The paper describes the success of this design approach, and measured displacements in the stoping horizon and shaft barrel are compared to those obtained from the original computer model

Jan 1, 1987

By W. J. C. Pothas

This paper describes the state of the art in backfilling techniques used on East Driefontein Gold Mine. Areas covered are the preparation plant, the distribution plant, the pipeline network and finally placement techniques. The in-situ performance of placed backfill has been assessed by the Chamber of Mines Research Organization, and results to date will be shared. Details of the backfill expansion programme that will enable this facility to be made available to all working places are included. Benefits obtained by the introduction of backfilling are described, together with certain management aspects to be considered in the control of quality and quantity of support supplied via a pipeline.

Jan 1, 1988

By C. Birch

"A mineral resource royalty is payment to the holder of mineral rights for the utilization of the mineral resource. In South Africa, this payment is made to the State as holder of the mineral rights (The Mineral and Petroleum Resources Royalty Act of 2008). The principle purpose of this research paper is to identify if the State is benefitting from the mineral resource royalty by considering its impact on seven individual Witwatersrand gold mines.For this study, a simple financial optimiser model was created in Microsoft Excel that links the ore flow, block listing and the cash flow (excluding or including the cost of the mineral resource royalty). Mixed integer linear programing (the Excel Solver function) is utilised to optimise either profit or NPV (at 9% and 12%) by adjusting the cut-off grade.The impact on each of the seven mines mine was different but overall R7.9 billion is estimated to be paid in mineral resource royalty over their expected remaining lives. Due to the cost of the mineral resource royalty and increasing the cut-off grades, the total revenue decreases by R10 billion. A significant portion of this lost revenue would have been paid to the State in the forms of other taxation including company income tax which decreases by R2.8 billion. It is recommended that an industry wide investigation be conducted to determine if the resource royalty is adding to the State’s revenue, or destroying value including premature job losses. IntroductionTaxation of mining companies has become a very topical subject in the context of the postapartheid South African economy. There have been increasing calls for equitable re-distribution of mineral asset wealth for the benefit of all South African citizens and not just to an elite few. As part of the Mineral and Petroleum Resources Development Act (MRDPA) of 2002, the Mineral and Petroleum Resources Royalty Act of 2008 was introduced and came into effect in 2010 (South African Revenue Services, 2008). A mineral royalty is payment to the holder of mineral rights for the utilization of the mineral resource. In the case where the holder of the mineral right is the State, then this payment is made to the State (Cawood, 1999). Studies on the potential impact of the mineral resource royalty on the minerals industry have been conducted during the formulation of the Act and subesquently. These include Cawood and Macfarlane (2003), who suggested a cap of no more than 3% (Cawood and Macfarlane, 2003), as well as Cawood (2011), who predicted rising cut-off grades and thus reducing mineral reserves. In 2013, Grobler completed a Masters in the Faculty of Economic and Management Sciences at the University of Pretoria and concluded that the impact of the mineral resource royalty on the economy is positive. She stated that the royalty has caused operating expenses to increase, but this does not appear to be significant. Furthermore, she stated that the royalty has not affected the way the mining industry operates (Grobler, 2014)."

Jan 1, 2016

By W. A. Hustrulid

CONTENTS PART I The theory of percussive rockdrill operation. Blow frequency Piston impact velocity and blow energy Thrust requirements Prediction of penetration rate Drillsteel life Bit wear PART II Measurements of percussive rockdrill performance Thrust-penetration rate measurements Blow frequency Piston impact velocity and blow energy Prediction of penetration rates The effects of hole diameter Thrusts applied by men Bit wear Appendix I Experimental procedure and rockdrill and drill steel specifications Appendix II Piston impact velocities and energies PART III Practical implications. Provisions of adequate thrust Conclusions INTRODUCTION In South African gold mines some 100 million tons of rock are broken each year by drilling and blasting. Only minor improvements to this method of rockbreaking have been made since the general introduction of pneumatic rockdrills for stoping 50 years ago and, more recently, of drillsteels tipped with tungsten carbide. The combined total cost of drilling and blasting amounts to almost R0,50 per ton of rock broken, which is just short of one quarter of the direct cost of stoping or development. Rockdrilling accounts for about R0,25 of the total cost of rockbreaking, of which RO,12 represents labour costs and R0,13 the cost of drillsteels, rockdrill spares and power. Mine air compressors use over 7 X 108 kWh of electric energy a year, amounting to 7 percent of the total electric power used by the gold mining industry. The efficiency of percussive rockdrilling is, therefore, of considerable significance to mining costs. Over the past four years the Mining Research Laboratory of the Chamber of Mines of S.A. has been engaged in experimental studies of percussive drilling. These experiments were conducted at test sites on Robinson Deep Gold Mine and Vlakfontein Gold Mine, made available by Gold Fields of South Africa, Limited. Three rockdrills, designated types A, Band C, of different manufacture, were used in the experiments which involved the measurement of the following operating characteristics: 1. Throttle air pressure 2. Applied thrust 3. Penetration rate 4. Air consumption 5. Blows per minute 6. Drill steel revolutions per minute. The results of these investigations are presented in three parts. Part I, "The theory of percussive rockdrill operation" which provides a concise, mathematical description of the performance of a percussive rockdrill in terms of its principal mechanical dimensions and operating conditions, and an analysis of the bit and gauge wear of drillsteels. Part II, "Measurements of percussive rockdrill performance" in which the experimental results are presented in terms of thrust-penetration rate curves at different throttle air pressures and throttle pressure-air consumption curves, which are shown to agree well with the predictions of theory. In addition, data relating gauge wear on the drillsteel and penetration rate to the distance drilled are discussed. Part III, "Practical implications" in which an analysis of the status of thrusting devices is made and the benefits that would derive from using uptimum thrusts are discussed.

By D. H. Diering

Definition of mineral resources and reserves forms the basis for effective mine planning and reliable public reporting of mineral assets. Historically, the mineral resource and reserves declaration process has been the domain of the geology and surveying disciplines, with the declaration of the reserves by the surveyor being based on the application of modifying factors to the declared resources available for mining. As part of an ongoing process to improve efficiency, reliability, and reproducibility of results, this approach has been revised and enhanced through the introduction of a revised process and reconciliation tools. The revised approach to reserve definition is based on the definition of scheduled resources, at an appropriate confidence estimate in the context of an approved business plan, over the anticipated life of the mineral asset being applied to define reserves. This planning and scheduling is developed, during the annual business planning process, by the mine planning department using tools such as CADSMine?. The scheduled area together with the application of revised modifying factors is tabulated in the BME (basic mine equation) and reflects the mine production plan over time. Simplification of the modifying factors to dilution and losses underpins the simple yet robust approach to improved definition of reserves in this process and in the basic resource to reserve equation (BR2RE). Dilution intrinsically affects grade but not metal content, whereas the losses reflect both the efficiency of mining and planning and are reflected in metal losses, area losses, or both. Reconciliation of the derived 'resource converted to reserve' area (which is based on the business plan from CADSMine?) versus the 'resource available for mining' (which is derived from Datamine?) underpins the robustness and auditability of the reserves declaration. This R&R accounting and reconciliation approach is transparent and facilitates interrogation of the logic and rationale of long-term business planning and project strategy. These numbers are processed and reported in the logic of the basic resource equation (BRE), which also addresses aspects such as white areas (future and historic), tail management, and partial extraction (non-scheduled pillars, etc.) in compliance with SAMREC definitions. Areas that do not have the necessary confidence and data support to be declared as resources find their space as pre-resource (outside the domain of public reporting), outlining existing potential for future extraction and reporting. Use of the BRE leads ultimately to a complete, refined accounting and reconciliation-oriented approach for all production entities. The revised resource and reserve process includes the discipline of mine planning as intrinsic to the definition and declaration of resources and reserves. Subsequent to the change in process, the resources and reserves have truly become the domain of the mineral resource management discipline. This paper defines the logic of the basic resource equations and outlines their application in the definition and reconciliation of mineral resources and reserves at Anglo American Platinum Limited.

Jan 1, 2013

By D. A. Singer, J. C. Griffiths

"One of the most useful approaches to a complex problem is to model the system which gives rise to the problem and to perform simulations through the model to find appropriate solutions. The Engel Model may be used as such a simulator to investigate the problem of the exploration for natural resources.The Engel Model is based on a two-stage search procedure in which a known area (A) which contains m prizes is subjected to search by n coverings. During the first-stage search the sensor system records signals which may be a response from prizes (that is, true signals) or may be false. Signals tend to cluster around a prize and a cluster size consists of s signals. If a circle of radius R is drawn around each signal some will overlap and the overlap from s signals contains a prize. The cost of a single covering in which each point of the area comes under observation once, is designated E1. Second-stage detailed search is expensive and is confined to areas of overlap of s circles; it leads to the location of prizes. Second-stage search of the whole area costs Ea units. The expected value, V, of a prize is known and its development cost is E3 units.The sensor system characteristics are defined by the circle of radius R around a signal, which should be small compared with the total area A and enters the model as a parameter a x R2/A. The probability of a false signal during a single covering of a circle of radius I is a known constant, A.This model was applied to the search for uranium ore bodies using two different types of occurrence. In the first, the Wyoming Basin type, the area is relatively large (A = 1 496 square miles) and a few (m = 4) large prizes occur (expected value V = $30 million). In the second area, which represents the Ambrosia Lake region of New Mexico, the area is smaller (A = 212 square miles) and contains many (m = 200) smaller prizes (expectedvalue of a prize V,$2 million). The three costs, E1, E2, E3, are adjusted to the different circumstances in the two areas.Simulations were performed using n = 1 to 40 coverings with cluster sizes s = 0 to 19; the radius R was varied from 0.52 to 3 miles (and, therefore, a = 0.002 to 0.133 0, respectively, dependent on the area of interest). The value of A was varied from 0.01 to 0.10.Profitable programs were found over a wide range of the parameters; the two areas required different strategies to achieve maximum profit. In the Ambrosia Lake region a few passes (n = 4 to 6) with small cluster sizes (s = 2 to 6) are more profitable, whereas in the Wyoming Basin region a large number of passes (n = 35 to 40) and cluster sizes of s = 5 to 10 are most profitable.As pointed out by Allais (1957) the larger prizes are the most important in deciding the successful outcomes of exploration programs, and the profit margin in the search for a few large prizes is sufficient to yield success over a wide range of programs. Such programs require very large investments if they are to be successful.To refine the Engel Simulator as a decision-maker in selecting the most profitable exploration programs it is necessary to obtain firm estimates of the sensor system characteristics, that is, of R, a and ? (lambda)."

Jan 1, 2014

By G. van Aswegen, J. D. Bosman

Gold bearing deposits in the Witwatersrand consist predominantly of narrow tabular conglomerates with quartzite host rock. Extensive mining of these deposits at depth results in significant stresses being induced in the periphery of the tabular excavations. Where remnant pillars are created excessive stresses have resulted in the dynamic failure of the abutments. At the Hartebeestfontein Mine four brittle shear zones have recently been exposed and investigated. For most part, they represent abutment failure into the weaker hangingwall strata, striking parallel to the abutment, dipping towards the stope, with a sense of displacement consistent with closure of the stope from above. These shear zones are similar to those described in various publications by Ortlepp2: they are essentially brittle shear zones characterised by the presence of very finely comminuted ‘rock flour’ on an obviously freshly sheared surface. The angle between the shear zone wall and extension fractures indicate the sense of shear and the intersection of the extension fractures with the shear zone walls define a strong lineation normal to the direction of slip. It is suggested that these structures are referred to as ‘mining induced dynamic brittle shears’. Les gisements d’or du Witwatersrand consistent principalement de conglomérats tabulaires peu épais contenus dans une quartzite mère. Une exploitation poussée de ces gisements en profondeur a pour résultat l’apparition d’importantes contraintes induites à la périphérie des excavations tabulaires. Là où des piliers restants sont créés, des contraintes excessives ont eu pour résultat une rupture dynamique des appuis. Dans la Mine d’Hartebeestfontein, quatre zones fragiles de cisaillement ont été récemment exposées et étudiées. Dans la plupart des cas, elles représentent une rupture des appuis dans les strates moins solides de la paroi suspendue, orientée parallèlement à l’appui, inclinée en direction du chantier d’abattage avec une direction de mouvement consistante avec l’affaissement du toit de la galerie d’abattage. Ces zones de cisaillement sont similaires à celles décrites par Ortlepp2 dans diverses publications: Ce sont essentiellement des zones cisaillement fragiles caractérisées par la présence de « farine de roche » très finement réduite sur une surface évidemment fraîchement cisaillée. L’angle entre la paroi de la zone de cisaillement et les fractures de tension indiquent le sens du cisaillement et l’intersection des fractures de tension avec les parois de la zone de cisaillement définit une forte délinéation perpendiculaire à la direction du glissement. Il est suggéré que l’on se réfère à de telles structures comme des « cisaillements dynamiques fragiles induits par l‘exploitation ». Goldablagerungen im Witwatersrand bestehen überwiegend aus schmalen tabularen Konglomeraten mit Quarzitwirtgestein. Der umfangreiche Abbau dieser Ablagerungen in der Tiefe resultiert in signifikanten Drücken, die auf die Peripherie der tabularen Aushöhlungen wirken. Wo Restpfeiler hergestellt wurden, resultierten exzessive Drücke im dynamischen Versagen der Auflager. In der Hartebeestfontein Grube wurden kürzlich vier spröde Scherzonen freigelegt und untersucht. Zum größten Teil representieren sie Auflagerversagen im Stratum der schwächeren Stollenfirste, parallel zum Auflager verlaufend, in Richtung Abbaustelle abfallend, mit einem gewissen Grad an Verschiebung konsistent mit der Schliessung der Strosse von oben. Diese Scherzonen sind jenen ähnlich, die in den verschiedenen Publikationen von Ortlepp2 beschrieben werden: sie sind im Wesentlichen spröde Scherzonen, charakterisiert durch das Vorhandensein des sehr fein pulverisierten „Gesteinsmehls“ auf einer offensichtlich frisch abgescherten Oberfläche. Der Winkel zwischen der Scherzonenwand und den Bruchverlängerungen deutet die Richtung der Scherung an und die Kreuzung der Bruchverlängerungen mit der Abscherzone grenzt sich gegen eine starke Lineation normal zur Richtung der Lehne ab. Es wird vorgeschlagen, daß diese Strukturen als `vom Abbau verursachte dynamisch spröde Scherungen’ bezeichnet werden.

Jan 1, 2003

By G. C. Smith

Process control applications in the minerals processing industry have grown extensively over the years due to the many benefits derived, both financially and operation-wise. Although control theory is widely known, conventional control does not address many of the problems posed by minerals processing circuits. Some of these problems include interactions between process units, large dead times, few and sometimes unreliable measurements of process variables, non-linear systems, disturbances entering the process, processes with varying dynamics, and many more. For the past 26 years Mintek has been active in the field of providing specific, customized solutions for the minerals processing industry. This paper focuses specifically on applications in milling and flotation control. The underlying control principles have been applied to a wide range of other processes including submerged arc furnaces. Advanced control application is implemented on a common advanced control platform, called the PlantStar. Much innovation has been brought to the fore in terms of adapting theoretical techniques and developing new methods to resolve specific milling and flotation circuit issues by using process control. The general approach adopted by Mintek when implementing advanced control is to enforce stabilization of the process as a solid foundation for optimization strategies to be built upon. In doing this, a robust control solution is presented, and the end result is flow and level stability, better product quality regulation, increase in throughput and a stable feed to downstream processes. The MillStar advanced milling control system ensures that the milling circuit is at all times easy to operate while achieving optimum product quality and throughput. Stabilization should include product size regulation and sump level control. Another important aspect of stabilization control is the handling of milling circuit constraints without introducing cyclical behaviour and with minimal disturbance to the final product quality. Process constraints may include factors such as process water limitations, cyclone feed density, and cyclone underflow angle. An optimization strategy should be developed to increase the mill throughput without affecting product quality or introducing mill overloads. The relationship between solids feed and power draw is examined and manipulated for optimization. The interactive nature of flotation circuits and the presence of recirculating streams tend to make satisfactory control almost impossible with conventional techniques such as PI (Proportional plus Integral) or PID (Proportional, Integral and Derivative) control. The FloatStar Level Stabilizer simultaneously considers all the flotation levels in a circuit by use of a multivariable algorithm, and takes compensating action in anticipation of disturbances. The FloatStar Flow Optimizer is an optimization strategy that controls the concentrate flow rate between various sections of a flotation circuit (e.g. Rougher ?Cleaner; Cleaner ?Recleaner). By controlling the concentrate flow between the sections, the mass pull, circulating loads and residence times of the circuit can be stabilized, thereby enhancing the performance of the flotation process. Optimizing grade and recovery are coupled with the dynamic optimization of circulating flows. The FloatStar Grade-Recovery Optimizer will maximize the grade in a section, whilst ensuring that recovery or any other process specific limits remain within predefined limits. With successful applications on several milling and flotation plants worldwide processing amongst others PGMs, gold, copper and nickel, Mintek has shown that it is a leader in milling and flotation control innovation

Jan 1, 2004

Mr G. Maude was educated at Huish's Grammar School (Taunton) and Leeds University. He graduated in 1961 with a B.Sc. degree in Mining. Mr E.B. Crocker was educated at Florida Park High School, Witwatersrand Technical College, and the University of the Witwatersrand.

Jan 1, 1985

By R. W. O. Kersten, J. D. Austin

A questionnaire was circulated in 1986 that had the objective of establishing the type of material that members would like to see featured in the Journal of The South African Institute of Mining and Metallurgy. The questionnaire contained five main questions involving the following:

Jan 1, 1987

By G. A. Bezuidenhout, S. Bradshaw, W. Malan

"Currently, the matted-based collection process is most widely used for platinum group metal (PGM) recovery. However, because PGM-containing concentrates are becoming more enriched with UG2 (Upper Group 2) low-grade concentrates, this is expected to be integrated or replaced with an alloy collection process.The reduction LG (low-grade) concentrates with silicon carbide (SiC) was investigated. The purpose of the study was to ascertain the feasibility of using SiC as reductant with regard to metal fall, PGM grade in the alloy, slag composition, and overall PGM recovery, and if possible, the integration of such a process in the current matte-based collection process. Rowland and Easterns LG concentrate samples from Lonmin were analysed by Xray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). It was found that SiO2 and MgO are the most abundant oxides and Pd is the most abundant of the PGMs. Sulphide-bearing minerals such as chalcopyrite were detected in low concentrations (below 1%), and Cr2O3 concentrations are between 2-4%. SiC reduction of Rowland and Easterns concentrate were conducted at 1600°C with reductant to concentrate ratios ranging from 2.5 to 3.5 kg SiC per 100 kg concentrate.The reduction experiments revealed that PGM recoveries from Rowland concentrate were poor. SEM images showed entrained metal prills in the slag phase. The slag viscosity at the end of the melt was calculated by using FactSage, and the results indicated that the viscosity was higher than 4 poise, which is above that of Easterns slag. PGM recoveries for Easterns concentrate were significantly better. More than 85% of the Ir and Pd and almost 60% of the Pt were recovered in a test with a reductant to concentrate ratio of 3.5 kg SiC per 100 kg Easterns concentrate. At this reductant to concentrate ratio, Fe recovery was also the highest, at 66%. SEM imaging of a slag sample revealed few or no metal prills entrained. The FeO content in the initial concentrate charge was then increased by adding Peirce-Smith converter slag in order to decrease the slag viscosity and further increase PGM recovery. A test was conducted with the addition of 10 kg converter slag per 100 kg Easterns concentrate. The reductant to concentrate ratio was kept at 3.5 kg SiC per 100 kg Easterns concentrate. The Ir and Pd recoveries were more than 95%, while Pt recovery was almost 70%. Fe recovery increased to 76%. On the basis of these results an optimum feed ratio between Easterns and Rowland concentrates and Peirce-Smith converter slag were calculated. FactSage predicted that the concentrate charge should consist of 70-80% Easterns concentrate with 20-30 kg converter slag per 100 kg LG concentrate. SiC reduction of this optimum LG concentrate charge is expected to recover more than 90% of all PGMs. Cr and Si concentrations in the alloy will be below 1% in total.The effectiveness of SiC as reductant was also compared to carbon reduction. Carbon reduction of an optimum concentrate charge at the same reductant to concentrate ratio resulted in a marginally higher metal fall than SiC reduction. However, gas emissions and energy requirements are higher for carbon reduction.The study has shown that base metals and PGMs can be recovered in an iron alloy by SiC reduction of LG concentrate with converter slag additions. Integration of such a process into the matte-based collection process could be considered as a future alternative for smelting UG2 LG concentrates."

Jan 1, 2014

By H. Möller, L. Mashigo, C. Gassmann

Wire-arc additive manufacturing (WAAM) is a directed-energy deposition technology that uses arc welding procedures to produce computer-aided designed parts, such as three-dimensional printed metal components. A challenge of additive manufacturing is the anisotropy. Interstitial elements play a significant role in the mechanical properties of Ti6Al4V of different grades. In this research, the mechanical properties of Grade 5 and Grade 23 Ti6Al4V were compared for this application. Samples were extracted from WAAM-produced Ti6Al4V walls in different directions (horizontal and vertical) and at different positions (top and bottom). The samples were subjected to optical microscopy and tensile and hardness tests. Grade 5 Ti6Al4V samples were found to have greater strength, greater hardness, and lower ductility, owing to the higher content of interstitial elements compared with Grade 23. The bottom samples had higher strength than the top samples, which is attributed to thermal cycling during manufacturing, resulting in different microstructures.

Jul 1, 2021