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By T. Holmes

Investigations reveal that the throughput difference between a perfect production day and the average is often on the order of 40%, and that bulk solids handling system deficiencies are the largest (>50%) class of lost opportunities. Root causes for underperformance of elements in material handling systems can often be traced back to the detailed design and even study-stage oversights. To reduce or eliminate bulk solids handling problems in an existing system requires an analysis of troublesome handling equipment – for example, a concentrate transfer chute that experiences plugging, poor flow to the furnace, unacceptable dust generation, and spillage. These problems often lead to significant maintenance costs related to downtime and personnel time. Understanding the cause and cost of flow issues is the first step in troubleshooting the problem. Next, measuring the material’s flow properties is critical to providing design data required to develop a comprehensive scientific solution. In the case of a new installation, the design data is required to properly design the system right first time and prevent flow problems from occurring so that the new equipment works correctly from start-up. This paper highlights the cost of material handling problems and discusses the best approach to evaluate material handling system deficiencies. A case study is given of how Anglo American's operation in Barro Alto Brazil enjoyed a 5-month payback from a bulk solid transfer chute debottleneck project. INTRODUCTION When operating a plant or designing a greenfield or brownfield operation, the intent is to have perfect production days (PPD) each and every day. Money is made by moving material through the plant in a controlled manner to produce the desired product. Mining operations and copper concentration processes are at the most basic level a practice in bulk solids handling (BSH). Unfortunately, many of the project planning steps are overlooked, particularly related to BSH. Investigations reveal that the throughput difference between a PPD and the actual average is often on the order of 40%, and that BSH system deficiencies are the largest (>50%) class of lost opportunities (Wellwood, 2017). Root causes for underperformance of elements in material handling systems can often be traced back to the detailed design and even study-stage oversights. BSH issues are essentially baked into the fabricated plant and left to operations to accept the deficiencies and deal with them for the life of the mine. These deficiencies then become part of the normal operation of the mine and plant.

Jan 1, 2019

By L. W. T. Weitzel

"This paper reviews the Falconbridge- SMRQ’s Raglan project in northern Quebec and the process that was used in developing its current long-term mine plan. Challenges were many and not only limited to the longevity of the project, numerous ore deposits (both underground and open pit), and a 40 km property strike length. As a result of its remote northern location, other factors such as progressive reclamation, leachable mine waste, water treatment, and waste management were also part of the plan. A combination of modern planning tools were used to formulate the plan including DataMine, Mine 2-4D, AutoMod Simulation, and an Excel-based financial spreadsheet to bring the total plan together. The focus of the paper is to show the complexity of modern mine planning and associated economic modelling of mine processes. IntroductionThe Raglan project is located 1660 km directly north of Quebec at the northern tip of the Quebec Peninsula in Nunavik. The main property is 40 km in length stretching from the Donaldson airport area at the eastern edge of the property to East Lake at the western edge. The Deception Bay port is 90 km north of the main complex/mill situated at Katinniq which lies approximately in the middle of the property (Fig. 1). The mine processes 1 000 000 tpy of ore from both open pit and underground sources. The mill is forecasted this year to produce more than 150 000 t of concentrate grading more than 18% nickel. All personnel and critical cargo are transported to the site via a company-leased 737 jet from Rouyn-Noranda where the main administration office is located. The majority of cargo is shipped to the site via Deception Bay from Quebec and on the return trip, nickel concentrate is shipped back. From Quebec, the nickel concentrate is sent by rail to the Falconbridge smelter in Sudbury and on the reverse rail haul, nickel matte from the smelter is sent to Norway via Quebec."

Jan 1, 2003

By John T. Ling

"This paper describes the operation of a rope haulage used as the main system of transportation in an underground coal mine. Prince Colliery, which is operated by the Cape Breton Development Corporation, has been in operation for 23 years and produces 1.2 million tonnes of coal annually. The mine extends a distance of 8000 metres under the Atlantic Ocean. All personnel and supplies are transported by means of an endless rope haulage system consisting of a train of rail cars that are operated by an electric engine on surface. The wire rope is 15 km long and weighs 63 tonnes. The system is believed to be the longest of its type used in an underground coal mine. The design of the system, safety features of the haulage, and problems encountered during the design and construction are described. IntroductionCoal has been mined commercially in Cape Breton, Nova Scotia since the 1800s. Several coal seams that are part of the Sydney coal fields, dip toward the north and northeast out under the Atlantic Ocean at angles between -4 and -15 degrees. Coal has been economically mined at depth in excess of 1200 m and more than 11 km from the coastline.Traditionally, single and double drum hoists have been used to haul the coal to the surface and also for transporting the workers and the materials required for mining up to 8 km. With the introduction of mechanized mining methods in the late 1960s, conveyor belts began to replace rope hoists for coal transportation. Improvements in hoisting system design also allowed for drums that could wind up to 6100 m of 32 mm wire rope in 15 layers.These hoists are commonly referred to as “drop hoists” because they take advantage of the gradient of the slope to assist in allowing the mine car train to reach the end of travel. The cars travel on steel rails and the rope is guided by rollers to reduce friction in the system."

Jan 1, 1999

By H. Powell

"This paper discusses how elemental analysis of conveyed bulk flows in real time using PGNAA (Prompt Gamma Neutron Activation Analysis) technology has resulted in significant improvements in advancing plant control in mineral processing operations. PGNAA through belt, full stream, continuous, multi-elemental, real time analysis technology is explained. Capabilities and limitations in plant operating environments are discussed including comparison with other real time, on-line technologies through review of published information available for on-conveyor minerals applications. Case studies include an iron ore and copper-gold company, both of which consider the technology an essential component in advanced plant control necessary in new process flow sheet designs, rather than an optimisation tool.INTRODUCTION Process operators rely on supply of a reasonable ore quality and consistency from the mine. Unfortunately neither the mining nor process operators have much control over the ore quality once it has been put into the crusher. Grade control typically stops once the material is designated as ore and the process plant operator needs to process it irrespective of quality. Plant control is most effective when technologies measure process streams directly and preferably in real time. Measuring sampling streams that are not representative of the primary flow will result in incorrect plant control decisions. Sampling coarse conveyed flows is expensive and impractical at many operations, however, this does not mean those flows cannot be measured. Investigations to find techniques suitable for real time elemental analysis have focussed on the application of known laboratory techniques to process streams. For conveyed applications, development of neutron irradiation techniques were most promising and early studies indicated potential success for bauxite measurement (Beurton et al, 1995). Tran & Evans (2001) concluded there was no equivalent technology to PGNAA in terms of material penetration power and that the technology was eminently suitable for basic industries such as cement. Nelson and Riddle (2003) evaluated PGNAA for possible use in the phosphate industry by using a unit installed in a cement plant to test performance on phosphate samples and ultimately recommended its use for further characterisation of the mine’s various ore types to improve stockpile allocation and grade control"

Jan 1, 2014

By Andy Fortin, Jeet Basi, Simon Hille

Goldcorp’s Eleonore mine is situated in Ell Lake area in the northeastern part of the Opinaca reservoir in the James Bay region of Quebec. The design of the 7000 t/d process plant includes crushing, grinding, bulk sulphide flotation, separate concentrate and tails leaching and detoxification circuits and residue handling. Detoxified flotation tails are thickened and filtered. A portion of the filtered tails are blended with the thickened detoxified sulphide concentration for paste backfill. The remaining filtered tails are trucked to the waste management facility. This presentation will describe the challenges faced with the commissioning and subsequent ramp-up of the flotation tails filter plant and the successes achieved by the multi-discipline team at Eleonore.

Jan 1, 2016

By Sanjiv Dhanjal

"Often mineralogy dictates the physical properties of a material rather than chemistry. This in turn affects how that material behaves in a process plant, and whether optimum conditions for refining one mineral are different to those for refining another. For example how does refining copper from chalcopyrite differ to refining copper from bornite?Minerals are naturally occurring inorganic solids that have a definite chemical composition and an ordered atomic (crystalline) structure. X-ray diffraction is a common and highly developed method to identify and quantify minerals. X-rays are fired onto a material and the mineral is identified by the angles where the diffracted X-rays are in phase.Most X-ray analyzers are laboratory based. A sample is prepared and analyzed by a detector that travels in an arc to collect the diffraction pattern. COSMA has a curved detector which picks up the complete x-ray pattern instantaneously. Therefore, material is collected and transported through the machine where is it is analyzed continuously.COSMA measures about 0.5 tons of material per day, while laboratory analyzers measure a few grams at a time. Real time data trends are produced allowing for improved process evaluation and automatic control. The COSMA on-line system has taken X-ray diffraction out of the laboratory into the field.There are a number of systems in operation in cement production. It is recognized that on-line mineral analysis has a role in many other processes. This paper presents the technology and invites further discussion should the technology be beneficial to members of the audience.INTRODUCTIONThis article describes COSMA, a system that provides direct and continuous on-line mineral analysis using X-ray diffraction in the field. While X-ray diffraction is a common technique used in mineral analysis, the time from sampling to analysis can be hours and plant operators typically do not get the data in time to control a process or respond to an upset. COSMA provides rapid measurement, analysis and feedback of data, in real time. This provides powerful information that can be used to optimize operation, thereby reducing costs and increasing quality."

Jan 1, 2009

By L. Garycki, P. Poks, R. Urbaniak, T. Gabka

In 2016 at Głogów Copper Smelter KGHM Polska Miedź S.A., after shutting down the shaft furnaces new FSF was launched. Currently, it is the only smelter with two direct to blister flash smelting furnaces in operation. The main difference between the vessels are the dimensions and production capacity. The new furnace design output is about 30% higher compared to the old flash smelting furnace working for 40 years. The paper presents a comparison of both FSFs operation, differences in technology and the way to optimize the process to maximize efficiency. INTRODUCTION KGHM Polska Miedź S.A. is the only company in Poland (eastern part of Europe) that extracts and processes copper ores. It is located in the south west of Poland and this region is called the "Copper Basin”. KGHM PM S.A. consists of three underground mines: Lubin, Polkowice-Sieroszowice, Rudna, concentrator plants, a tailings pond plant, three copper plants: Legnica, Głogów and Cedynia wire rod plant in Orsk. The publication relates to the operation of the furnaces in Głogów (the plant in Głogów consists of Głogów 1 and Głogów 2 which form integrated smelting and refining facilities). In 2016, after closure of the shaft furnaces technologies in the Głogów 1, a new FSF commenced operation. The simplified process flow sheets are given in Figure 1 and 2. Technological schemes are similar, but due to the differences in them, they will be discussed separately. Głogów 1 Enriched ores are discharged and directed to the feed preparation plant. Delivered concentrates are built up on the three bedding aisles in appropriate proportions. The concentrates are distributed in even layers in one of the three aisles. Aisle emptying is done with a blending machine which cuts across the concentrate layers and collects thus blended material, sending it via belt conveyors to a storage bin. From the cross- blending machine and conveyor assembly, the mixture of concentrates is directed to drying in the steam dryer. Part of the charge is directed to the FSF and part to the roaster for carbon elimination. Known in the world roasters are used to eliminate sulfur compounds or arsenic. In the case of KGHM deposits, the aim of the process is to reduce the energy value of the feed by eliminating carbon and converting sulfur from sulfide to sulfate. Changing the nature of exothermic to endothermic material is crucial in the case of furnace operation with design performance. Roaster is a separate furnace with an innovative character.

Jan 1, 2019

By P. K. Kaiser

3-D virtual reality (VR) visualization has opened new opportunities for complex 3D (x, y, z), 4D (x, y, z, t) or even nD data interpretation. The integration of common earth models (3D geologic data), mine models (3D excavations and stress), extraction models (1D time sequencing or mine sequencing) and nD monitoring data (e.g., seismic event parameters) into a common mining process model provides a platform for experts in various fields to better design, evaluate, monitor and modify mine plans throughout a mine?s life; from feasibility, through operation, to closure. Viewing seismic data in a stereoscopic VR environment within a mining process model offers data interpretation processes previously unavailable at lower dimensionality. MIRARCO has developed data analysis and viewing processes specifically designed to enhance microseismic and seismic data interpretation in a collaborative, immersive VR environment; bringing mine personnel and expert consultants together to evaluate data and make strategic decisions for cost effective and safe mining. Seismic events cause immediate hazards (rockbursts) and microseismicity causes gradual hazards through its cumulative effect in rockmass degradation. The focus of this paper is on understanding seismicity from a mine safety and mine planning perspective; in particular, how seismic migration patterns relate to the rockmass response to mining. The benefits of innovation in seismic data interpretation are significant, e.g., for hazardous work area identification, allowing better formulation of re-entry policies and workforce allocation planning, as well as allocation of effective support systems to strategic areas of elevated risk. Better understanding of the overall response of a mine to extraction also facilitates mine planning and design, assisting in reducing production costs and thus in enhancing profitability.

Apr 1, 2005

By David Lin

"Modal data from Red Dog Main Pit ores were collected and analysed on a size-by-size basis. The Main Pit data were compared to data from composite samples of Red Dog Aqqaluk ores. The data revealed that a large fraction of the sphalerite in the Aqqaluk baritic ore was tied up in sphalerite/galena binaries. This provided an explanation for its poor leadlzinc selectivity compared to Main Pit ores. The Aqqaluk vein ore exhibited levels of sphalerite/galena binaries comparable to that of Main Pit ores resulting in comparable lead/zinc selectivity.An attempt was made to correlate the modal and metallurgical data for Main Pit stockpiles. It was found that there was moderate correlation between the percentage of sphalerite locked in binaries with galena in the <C5>C6 size fi-action and sphalerite deportment to the leadconcentrate.INTRODUCTIONTeck Cominco’s Red Dog Mine in northern Alaska is one of the richest zinc districts in the world. Red Dog Mine has been in operation for over ten years and produces nearly 1 million tonnes of zinc concentrate per mum. Red Dog Mine is an open pit operation and current mining is conducted in the area known as the Main Pit. The Main Pit contains proven reserves of about 41 900 000 tonnes of ore grading 19.2% Zn and 5.2% Pb (Cominco 2000). To the north of the Main Pit is the Aqqaluk deposit. It contains probable reserves of 56 100 000 tonnes of ore grading 16.6% Zn and 4.1 % Pb. After the Main Pit has been exhausted, the Aqqaluk deposit will be exploited.The Aqqaluk deposit consists of three main geologic ore types: baritic, siliceous and vein. The siliceous ore type is dominant, representing 64% of the mineralisation. Composite samples of these ore types were created from drill core and batch flotation tests were performed on them. The flotation tests indicated that there were significant metallurgical differences between Main Pit ore and the Aqqaluk siliceous and baritic ore. The siliceous and baritic ores were found to suffer from poor lead/zinc selectivity (Lin 1999, G&T 1999). It was suspected that there were problems with the original Aqqaluk composite samples, thus a new set of composite samples were created and batch flotation tests were conducted again. In this set of tests, the new baritic ore still suffered from leadlzinc selectivity problems, but the new siliceous ore provided excellent metallurgical results. A summary of the flotation results is given in Table 1. Stockpile 132, which is typical of Main Pit ore, is given for comparison purposes. The mineral suite at Red Dog is relatively simple. The ore consists of galena, sphalerite and pyrite in a silicate matrix. The low zinc recoveries of the baritic ore were largely due to sphalerite losses to the lead concentrate."

Jan 1, 2002

By S. Dessureault, J. Porter, M. Woodhall

Information and communication technology (ICT) is seen as a key source of future productivity improvements in mines. The information technology infrastructure (ITI) necessary to achieve these productivity improvements will come in the form of data integrated from multiple source systems throughout the mining value chain. Two pure approaches are available: supplier-controlled or operations controlled data structures; each strategy has its own advantages and disadvantages. Case studies involving the South African mining industry are used to demonstrate the advantages of using hybrid-controlled data structures. Depending on the level of operational control, new skills are also necessary to be learnt by mining professionals including: information engineering; creating consistent and quality data; and process improvement techniques that use the integrated data for improving the operation.

Jan 1, 2004

By I. Vazaios, M. S. Diederichs, N. Vlachopoulos

"As rock engineering moves from continuum to more discontinuum approaches for modeling, the engineer must make decisions regarding the degree of complexity to simulate for a given application, balancing the level of structural detail within the rockmass model with computational cost and result accuracy. It is important to consider that model does not need to include all the existent fractures and that representative geometrical properties for a given rock mass volume can be defined including only major structural entities.Within this paper, the scale-dependency associated with the geometrical properties of fractured rock is investigated utilizing a Synthetic Rockmass (SRM) approach with a view to characterize such ground to aid in the design of geotechnical works. In terms of process, the concept of the Representative Elementary Volume (REV) is used to determine the equivalent structural properties of the rockmass in order to justify the applicability of far-field behaviour of such ground. A large size Discrete Fracture Network (DFN) measuring 60m x 60m x 60m has been generated using the structural data obtained from LiDAR scanning of the Brockville Tunnel, Ontario, Canada. A number of DFN samples of varying sizes are extracted from the master network, generated using MoFrac, in order to be used as a the basis of the structural analysis of the rockmass. Volumetric measurements for the density and the intensity of jointing are employed in order to approximate the geometrical REV for the networks.In this paper a complete methodology of how to generate a DFN from LiDAR data and its analysis in order to determine the size of a geometrical REV is demonstrated. For the specific rockmass found in the area of the Brockville Tunnel, a geometrical REV measuring 3.5m x 3.5m x 7m is established. The results are generally in good agreement with the in-situ observations."

Jan 1, 2015

By G. R. Brough

"Today it is more important than ever to get the maximum possible return on capital invested in the processing industry. To this end the plant is often operated continuously and the choice of equipment is, consequently, extremely important.Screening spans a wide range of particle sizes and there are many different types of screening elements. The following types are common:1. Cloths and elements of rubber.2. Wire mesh screens with round wires.3. Wire mesh screens with profiled wires.4. Perforated steel plates.5. Elements of plastic.6. Gratings of steel beams.7. Gratings of iron rods.We would like to deal with two of these types namely rubber and briefly on plastics.We first introduced rubber screens to the Canadian Mining Industry in November, 1963. This stemmed from a conversation with the superintendant of one of Canada's largest screening plants containing 48 vibrating screens, with an average wire cloth life of 10 to 12 days. We contacted the manufacturer of rubber screen cloths who had supplied rubber screens to a mine in Northern Sweden for a 50,000 ton per day plant in 1951."

Jan 1, 1983

By K. Morin

"Silver and gold leaching by cyanidation is a well-known process used around the world. This reaction is often accompanied by the leaching of other species throughtout the cyanidation circuit that causes the diversion of cyanide towards non valuable by-products (SCN-, Cu(CN)x, Fe(CN)x, etc.). One of the detrimental impacts of the formation of these by-products is the precipitation of silver-cyanide complexes that occurs when cyanide concentration is too low. Without any extra-addition of free cyanide, the precipitated silver is lost and cannot be recovered causing an important economic loss. To overcome silver precipitation, cyanidation circuits are often operated at higher cyanide concentrations. Recently, COREM’s research team has been working on a technology to measure and control silver precipitation during the cyanidation process. Moreover, a methodology has been elaborated in order to evaluate threshold cyanide level which corresponds to the cyanide concentration at which silver starts to precipitate. This technology has been tested on site on a real cyanidation circuit at Agnico Eagle’s LaRonde mine."

Jan 1, 2014

By J. R. Donald

"Project development has been increasingly formalized in the past decade, with most organizations having extensive and descriptive deliverables documents and processes to govern the stage gate progress of capital projects. Although this has improved the general governance of capital project development and execution, it has perhaps not led to improved business success. This paper identifies specific challenges associated with developing complex projects with multiple stakeholder interests over the long timeframe of the project life cycle. The paper outlines these challenges and suggests management approaches and aspects of project development where increased focus is required to achieve improved business outcomes."

Jan 1, 2015

By A. Taylor, E. Thorn Corthay, J. Farrell, L. A. Westfall, S. Borchardt

Mining and metallurgical industries need to minimize their greenhouse gas (GHG) emissions; Hatch specializes in conducting mining and metallurgical energy management assessments and optimizing productivity. Projects executed have demonstrated that there is a wealth of energy management, waste reduction, and process efficiency improvements that require no or low capital investment. Typical energy cost savings are on the order of 5% to 12%, with similar reductions in GHG emissions. Hatch generates Marginal Abatement Cost Curves to optimize the implementation pathway, maximizing carbon abatement and minimizing cost. The findings of a practical case study from Cameco are presented.

Jan 1, 2010

By Tassos Grammatikopoulos, Gary Pearse, Massoud Aghamirian, Charlotte Forstner, Stephen Mackie

"SGS Minerals Services (Lakefield, Ontario site) has conducted a number of developmental and pilot programs that examined methods for the beneficiation, extraction and recovery of lithium from a variety of spodumene containing hard rock sources. An overview of the beneficiation programs is presented separately by Aghamirian, Mohns, Grammatikopoulos, Imeson & Pearse (2011). The focus of this discussion will be the hydrometallurgical steps involved in producing a high grade lithium carbonate (Li2CO3) sample from the spodumene concentrate. SGS has applied the standard Li2CO3 hydrometallurgical flow sheet to a number of spodumene concentrates and has determined that all of these samples respond in a similar manner to the process and produce a final product having a Li2CO3 grade of >99.5%. The standard process is sufficiently robust to accommodate the observed variability in the concentrates that have been tested. Advantage of one spodumene deposit over another will thus be gained through process optimization and innovation. Optimization at the beneficiation stage and at the hydrometallurgical stage must be considered. Some aspects of the process optimization of the hydrometallurgical flow sheet will be presented.INTRODUCTION The current activity in the exploration, development, and mining of lithium based minerals is due in large part to the key role that this metal plays in the rechargeable battery industry (U.S. Geological Survey, 2011). Lithium battery technologies are widely applied in a range of portable electronic consumer products. The expanding development and production of hybrid and fully electric vehicles has contributed to the increased interest in finding and developing new lithium sources in order to meet the expected demand from the lithium battery industry. Lithium may be sourced from continental brines (sub-surface salars), hard rock minerals (pegmatite, spodumene), hectorite clay deposits, geothermal brines and oilfield brines. Currently the majority of the lithium products are produced from Li brines. The four major lithium producing countries are Chile, Australia, China, and Argentina (U.S. Geological Survey, 2009; Roskill, 2009). These countries accounted for 97.6% of the total lithium produced in 2010."

Jan 1, 2012

By J. E. Amadi-Echendu, F. Stober, J. Ndlovu, L. R. Nelson

The Polokwane Smelter Complex (PSC) relies on a single 68MW high-intensity six-in-line furnace to smelt a planned 650 000 t/a dry concentrate to produce a platinum group metals (PGM)-bearing matte. As typical of a greenfields venture, considerable attention was paid to the project development and implementation stages of design, engineering, construction and commissioning. Somewhat unusual though, was the role of a dedicated multi-disciplinary "Operational Readiness" and support team, comprising the owners team and specialists from the furnace designer, HATCH, to effect a safe and rapid ramp-up to the design smelter capacity of 68MW. The challenges encountered in developing an effective partnership will be discussed. The modus operandi and roles of the "Operational Readiness" team during the design, procurement, construction and commissioning stages as well as that of the operational support team within the overall ramp-up objective will be presented. The "Operational Readiness" team was responsible for:

Jan 1, 2005

By Bryan M. Maybee

The scheduling of underground mining activities is a complex task, in particular because of the requirement to satisfy a large number of constraints. A Schedule Optimization Tool (SOT) for underground mine planning is described, and its use for investigating strategic decisions is illustrated by means of a case study. The main components of SOT include: a genetic algorithm, which searches for optimal schedules; guidance, the application of heuristic rules to guide the genetic algorithm; and sliding, which implements just-in-time development. For the case study, SOT is employed to generate schedules at various ore capacities, accounting for the appropriate financials in each schedule evaluation. The case study finds that preliminary scheduling performed before invoking SOT, intended to provide a good starting point for the search, does not ultimately lead to higher value schedules. Two key uses for SOT are identified. A mine planner can save time by using SOT to produce high-value scheduling alternatives. This process ensures a broader investigation of the value that the deposit can yield. Also, SOT can be used to validate strategic and tactical decisions, by scheduling under alternative scenarios. Both uses produce high value schedules conforming to all imposed resource constraints.

May 1, 2009

By B. D. Pandey, M. S. Kim, B. S. Kim

The recovery of Sn from used Pb-free solder (Sn, 3~4 % Ag, < 0.9 % Cu, < 1.2 % Pb) has been investigated by electrorefining in sulfuric acid solutions containing small amount of hydrochloric acid. This involved preparation of the anode material by melting and casting the used solder followed by refining. During electrorefining, dendritic tin was deposited on stainless steel cathode. Increasing the amount of hydrochloric acid up to 0.3 mol /L in the electrolyte enhanced the current efficiency to 92.2 % and the enrichment ratio of silver to 94.3 % in the anode slime which was otherwise 84.7% and 81.6 % in absence of HCl, respectively. The electrolyte containing hydrochloric acid has also prevented the precipitation of tin oxide in the bath. In the scale-up experiment using 1.6 kg anodes, 84.3 % current efficiency and close to 100 % Ag enrichment ratio were obtained, while the purity of electro-refined tin was over 99.9 %. The energy consumption of the winning process was found to be 0.151 kWh /kg-Sn which is competitive as compared to commercial tin electrorefining processes.

Jan 1, 2014

By D. Paul Bishop, Kevin P. Plucknett, Hung-wei Liu

"Spark plasma sintering (SPS) process has been evaluated for producing the commercially pure (CP) Ti, TiAl and a TiAl-B4C composite. Comparisons were made between the materials in terms of the sintered density, resultant hardness and microstructures. In the present work, the titanium aluminide powders (Ti-48Al, producing a mixture of y-TiAl/a2-Ti3Al) were synthesised „in-house? using a simple reaction-sintering and mechanical attrition approach. This allowed various size distributions to be generated. The powders were then blended with a fine boron carbide (B4C) powder (up to 6 wt.%), and the resulting mixtures were consolidated using spark plasma sintering (SPS) under vacuum in graphite dies. An applied stress of 50 MPa was used for all SPS runs. The SPS parameters were varied in terms of the ultimate sintering temperature (up to 1300°C) and hold time (up to 10 minutes) for each material. It is demonstrated that high densities can be achieved this approach (exceeding 95% of theoretical, with optimised samples close to full density). Microstructural characterisation was conducted using optical microscopy, scanning electron microscopy, and X-ray diffraction. The B4C additions were seen to partially react with the TiAl to form reinforcements, such as TiCx and TiBx. Preliminary mechanical property assessment will also be briefly discussed.INTRODUCTION Titanium- and titanium aluminide-based alloys possess many unique properties, such as excellent corrosion resistance and high temperature strength, respectively (Cardarelli, 2001; Leyens & Peters, 2003). Compared to many other competing materials (e.g. stainless steel or Ni-based alloys), Ti- and TiAl-based alloys also have relatively low densities (~4.5 and ~3.9-4.1 g/cm3, respectively), which is critical for performance in aviation and automobile applications. However, the manufacturing cost is high, due to the expensive raw Ti material and difficulties in machining. TiAl-based alloys are particularly difficult to produce because of their limited ductility (Lütjering & Williams, 2007). To overcome those problems, powder metallurgy (PM) technologies have shown great potential as near-net shape processes for Ti- and TiAl-based alloys. The general PM process largely avoids laborious post-machining and minimises material use. In industrial production, the PM approach has been successfully utilised to manufacture aluminium- and iron-based alloys (Huo & Heath, 2008)."

Jan 1, 2017