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By S. Komar Kawatra, Youlian Zhou, Joseph A. Halt

"Bentonite clay has been the most common binder for iron ore pellets. Although bentonite increases pellet strength and durability, it has several disadvantages. For example, its use increases the cost of pellets and decreases pellet purity due to its composition and the higher levels of flux required to meet basicity limits. Several new types of binders have been proposed to replace clay. The binders include starch, modified humic acid (MHA), and dispersants. These binders were used to pelletize a magnetite concentrate from the United States. Typical doses of each binder type were 0.05-0.1 % starch, 0.5-0.75 % MHA, and 0.05 % dispersant. At these doses, the pellets exceeded the minimum recommended values for wet drop, dry compression strength, and fired compression strength. Pellets made with the MHA and dispersants had the lowest abrasion rates of the new binders, and were comparable to pellets made with bentonite clay. In this paper, we compare the new binders, considering pellet quality and the advantages and disadvantages of each binder type.INTRODUCTIONIron ore pelletizers need binders in order to make good quality iron ore pellets. The typical binder is bentonite clay, an alumino-silicate material. Bentonite increases the ballability and strength of iron ore concentrates, but reduces pellet iron grade and reducibility. As high quality bentonites can be expensive to ship, low quality bentonites are often used at significantly higher doses – this reduces iron grade and reducibility even further. Thus, several new types of binders have been proposed to replace bentonite clay.In this paper, we present several new binders for iron ore pellets: starch and modified humic acid (MHA). These have been tested alone and in mixtures with dispersants, or else with bentonite clay. Starch, MHA and their mixtures are briefly described below."

Jan 1, 2016

By H. Dundar

The first application of High Pressure Grinding Rolls was in 1985 at a cement plant, for the purpose of capacity improvement. Then various circuit configurations were derived to achieve a reduction in overall specific energy consumption, by transferring more of the grinding required to the HPGR. In most circuit configurations, the recycle of fines is required for effective breakage between the rollers. By increasing the fines amount in the feed material to a specific level within the recycling load, a uniform material bed is created and a higher pressure gradient along the roller width is obtained, resulting in compact flakes, including more fines. The fines recycle results in enhancement of the interparticle breakage. This paper will discuss the effect of the feed size distribution on HPGR performance.

Jan 1, 2012

By G. Dörsam, M. Spreij, S. J. Van der Wal, A. P. Schmidt

The transfer of hot metal desulphurising from the torpedo cars to the hot metal ladles at the IJmuiden BOS plant no.2 caused a decrease in ladle lining life from 680 to 470 heats. Changing the desulphurising agent CaC2 for CaO during a trial period, for environmental reasons, led to a further decrease in refractory life. Availability of the ladles became critical and the major reasons for the low life were identified. Solving one of them, temperature, quickly resulted in restoration of the original lives. However, re- introduction of the new desulphurising agent on 50% of the heats again resulted in a decrease, this time from 700 to 550 heats. In order to be prepared for the full introduction of the new agent, thorough investigation of worn linings was conducted, revealing the major (chemical) wear mechanisms. With these findings, a new design for the hot metal ladle is proposed.

Jan 1, 2004

By Zhou Yanwen, Fudong Wang, Shing Liu

Mixed CrB2 and MoS2 powder (Cr:Mo=1:1 atomic %), without any further process, were used as the targets to be sputtered and deposited onto stainless steel and silicon substrates by pulsed DC power supply. The structures and properties of the CrBMoS films were then analyzed by using SEM, XRD, micro-hardness tester. The SEM morphology of the films showed dense, defect free structure, and the preferred orientations of the films were CrB2 (111) and MoS2 (200) according to XRD spectra. The thicknesses of the films were measured and the relationship between the deposition rates and pulsed factors was determined. The films, with the micro-hardness as high as 19GPa and friction coefficient as low as 0.02, could be considered to be the hard solid lubricant films.

Jan 1, 2015

By M. H. Ali

Codelco, a multi-process primary copper producer, is undertaking a full life cycle inventory (LCI) of all its commercial products based on copper and molybdenum. During this work, many questions have surfaced regarding the contribution of process unit design to specific aspects of a product's LCI and, more importantly, how such designs could be improved using a life cycle perspective. Management strategy efforts were undertaken to improve the LCI footprint, however it was found that the corrective actions were almost impossible to apply at the operation level in plant, given the ongoing timing pressures of extractive mining, and costs saving priorities. Additionally, it was found that most of the important comparative differences between operations had structural reasons. In this circumstance, the LCI practitioner group from 1M2, and the environmental managers from Codelco, decided to shift its efforts to place the critical LC1 aspects to the design process of future developments. Hatch Associates has developed unique tools in their Sustainable Plant Design (SPD) package that compliment and enhance LCA methods; these effectively drive sustainability into the heart of the design process. By using LCA and SPD in a project design phase, you cannot only address potential hotspots, but also decide on materials, location and size of certain facilities to optimize for energy efficiency. Moreover, you can avoid the shifting of environmental burdens upstream or downstream within the plant and finally it is extremely useful in identifying opportunities for greenhouse gas reduction.

Jan 1, 2007

By J. A. E. Bell

"Inco has shifted part of its traditional extractive research effort at its J..Roy Gordon Research Laboratory in Mississauga toward new, value-added products. Most of the effort is being expended on new Ni powders for batteries and new Ni-coated products which will be produced in Inco's carbonyl nickel refineries. New products under development are Ni-coated powders, Ni-coated fibres and ultra-fine Ni powders. Other new products for advanced material applications include controlled expansion composites, NiGOLD strip, Thermal barrier coatings on Inco alloys, and plasma coatings.Research and Corporate Strategic ThrustsThe newest strategic thru st of the company is to increase the value of the primary metal products. These new products are to be in addition to any new alloys or downstream alloy fabrication.Historically Inco has had the highest research expenditures in the extractive metallurgy field in North America. This has resulted in many new processes including flash smelting , matte separation, fluid bed roasting, pressure carbonyl refining and cobalt electrowinning which have contributed to establishing Inco as the lowest cost nickel producer. The recession of the 1980s caused a restructuring of Inco research and corporate goals .As shown in Figure I, from 1975-1982, i.e. pre-recession, Inco spent around 33 million dollars per year on research. Some 48070 of that sum was spent in Corporate Laboratories in Sterling Forest in the United States and in the United Kingdom , mostly on alloy associated research. A further 10% was spent on alloy research at the alloy production facilities in Hunting- ton, West Virginia, and Birmingham and Hereford in the United Kingdom. On extractive research, 13% was spent by process technology groups at the plant s, 20% at the pilot plants in Port Colborne and 9% at the J. Roy Gordon Research laboratory.The relative research expenditures (Fig. 2) have decreased so that today they are at the same level as 1975-80. The research as a per cent of sales has been cut from 2.2% to 1.2% of normalized sales. A normalized sale price of $4.00/lb Ni was used in the 1988 figures. This was partly achieved by closing Corporate Laboratories. Most of the essential alloy research was moved to producing plants and total alloy research is now 27%.A new thrust initiated in the 80s was mining research which now accounts for 20% of research expenditures. Over a period of the past five years this research has doubled the mining productivity in Inco. The pilot plant expenditures have been cut in half. One entire research station at Port Colborne was converted into a platinum group metals intermediate refinery. The decrease in pilot plant expenditures has been compensated by full scale plant trials devoted to the S02 abatement program at Sudbury."

Jan 1, 1990

By G. Itoh, S. Fukasawa

The Al-Zn-Mg alloys have been known to be susceptible to stress corrosion cracking (SCC), which is based on intergranular cracking arisen from hydrogen embrittlement (HE). The mechanism of HE has not been fully understood yet. In order to elucidate the mechanism of HE, we need to investigate the behavior of hydrogen in the alloys. In this paper, behavior of hydrogen in an Al-5.8%Zn-2.4Mg alloy was investigated by means of hydrogen microprint technique, a method to visualize location of hydrogen emission from specimen surface as silver particles. One side of the tensile test pieces was electrolytically polished and then covered with photographic emulsion. Hydrogen was pre-introduced into the test pieces from opposite side by cathodic electrolytic charging for 30min. Then, the test pieces were stretched with continuing the charging. After that, the specimen was fixed, rinsed, dried and observed with a scanning electron microscope. As a result, silver particles were observed on some grain boundaries.

Jan 1, 2015

By A. Mellek, M. Pischtschan, M. Perrucci

ABB has received an order for one of the most challenging mill drive projects in its history. With one SAG mill and one ball mill to be added at an iron ore mine in Sweden, the customer’s plant managers wanted to have the most efficient solution for driving their mills but had the budget limitations typically faced by the majority of mining companies during periods of market downturn. To find the best balance between cost of acquisition and highest performance throughout the lifetime of the plant, ABB was selected to deploy a synchronized bypass solution, in which only one drive system is used for two different mills in series. However, being one of the first grinding mills in the world with such a solution was not the only challenge the ABB team faced: The inclusion of some mill application functions - e.g., frozen charge protection, automatic positioning and creeping mode - brought the demands on the engineers to another level. With only one frequency converter and one mill application controller available, the configuration logic and interlocks had to be meticulously designed and thoroughly tested to ensure a smooth and safe startup. The solution offers a footprint reduction and more operator flexibility at a reduced investment as each mill can be run in both directions, and wear on the mechanical components can be greatly reduced due to ABB’s premium ring-geared mill drive (RMD). This paper will describe the details of the project, the configuration developed and the tests performed to guarantee correct software functionality. Mill startup is scheduled for January 2016.

Jan 1, 2016

By K. E. Waters, N. Brodusch, R. Gauvin, A. Jordens, Teng. C., H. Demers

Rare earth elements (REEs) become increasingly significant for renewable energy devices and high-technology electronic products because of their large-scale popularity and applications. In this project, a field-emission scanning electron microscope was used to characterize the composition and distribution of REEs-bearing minerals. X-ray elemental maps were acquired with a large area x-ray detector (60 and 80 mm2 collecting area) and annular detector (60 mm2 collecting area), which allow fast x-ray acquisition at high count rate. These elemental maps were transformed into phase maps, which are used to identify the composition of the mineral phases and the REEs distribution over a large area. The phase maps are an easy way to distinguish the phases with and without REEs and compare the efficiency of different REEs extraction processes. Different methods (manual and automatic) for producing phase map were studied by comparing the distribution of REEs obtained from the same area.

Jan 1, 2015

By A. I. A. Salama, M. W. Mikhail

"A comprehensive software package has been developed at the Western Research Centre to meet many of the coal preparation requirements in the Canadian coal industry. This package performs three main functions: (1) data handling and manipulation; (2) data analysis, including the generation of washability data, performance evaluation and prediction, density and size modelling, evaluation of density and size partition characteristics, and attrition curves; and (3) graphics output.The software described in this paper is potentially a valuable tool for coal preparation plant engineers and operators for evaluating process performance and adjusting plant density separator cutpoints. Moreover, the analytical laboratory technician could find this package very useful in manipulating and presenting laboratory results."

Jan 1, 1997

By A. Gourlie

"This paper describes the performance properties of a new 95 ksi minimum yield strength, oil well casing grade designed specifically to resist hydrogen sulphide stress corrosion cracking, SSCc. The new grade, Soo-95SS, demonstrates NACE Tensile threshold values greater than 90% specified minimum yield strength, SMYS, and NACE Bent Beam values in excess of 12.7 x 1()4 psi. The new Soo-9588 grade also exhibits superior collapse and notch toughness values. IntroductionIn recent years, a trend toward casing grade specialization has resulted in the introduction of numerous proprietary grades designed specifically for particular production environments, In response, Algoma Steel has developed, as part of a "" grade for service"" philosophy, two new 95 ksi minimum yield grades. The two grades are Soo-95, High Collapse (HC), and Sour Service (SS). This paper describes the development of Soo-95 Sour Service.Four main objectives were established:1. Definition of the steelmaking and continuous cast processing practices2. Determination of the acceptable maximum and minimum levels for all chemical elements3. Definition of special processing requirements4. Definition of the physical characteristics and ranges of the product properties.This paper provides a description of the experimental approach, followed by a presentation and discussion of the trial results . Finally, a number of conclusions are given."

Jan 1, 1988

By R. J. Mitchell

"High narrow backfills of significant strike length approach the stress conditions associated with a free standing wall but this lower bound design approach is not considered efficient for earth structures. This paper considers the design of high narrow backfills using upper bound limit analysis, retaining wall theory with backfill arching and centrifuge model tests. Complex toe support situations pertaining to operational factors at Falconbridge's Lockerby Mine are investigated. It is shown that the susceptibility of high narrow fills to toppling is much lower than anticipated from the retaining wall analysis and that toppling can be avoided by a suitable toe support. It is also concluded that adhesion between the fill and an adjacent pillar can markedly increase the stability of the fill. INTRODUCTIONFalconbridge's Lockerby Mine pillar projects will expose cemented tailings backfills to heights (H) up to 55 m. The exposed backfills may have strike lengths (L) greater than the heights but are relatively narrow, having widths (w) of up to 12 m. The bulk cement content of the fills varies from 8.3% (12.1 T:C) to 3.0% (33.1 T:C). Exposed faces may have up to a metre of overhang due to stope overblasting, as shown in Figure 1. These fills have a solids specific gravity of close to 3.0 and were placed at a pulp density of about 68%. The tailings have a fairly uniform grain size with 32% less than 0.075 mm (200 sieve) and about 12% slimes (less than 0.02 mm sizes). The fill exposed by early pillar removal will be backed by adjacent, near vertical, ore pillars. Future pillar removal may expose similar fills which are not supported by an adjacent ore pillar but which will be backed by either an open void or by uncemented backfill. Furthermore, these fills may be undercut when the pillar slot is driven, further reducing stability (case 3, Fig. I) or a wedge could be left to help support the fill (case 2, Fig . 1). This paper presents limit equilibrium analyses for these various backfill conditions in a 22: 1 T:C fill and com- pares the results to data from centrifuge model studies at a scale factor of A= 157 as indicated in Figure I. Prototype fills have a 6 m deep cone plug of 16:1 T:C which is accounted for in the comparison of centrifuge model test with analytical results."

Jan 1, 1989

By Yihan Liu, Jintao Zhang, Chen Xiao, Xiaomeng Zhao, Guanglei Song

To estimate the performance of the inert anode materials based on NiFe2O4 spinel ceramic during it used for aluminum electrolysis, we investigated the wetting process of cryolite molten salt which is in composition of industrial aluminum electrolysis with carbon anode and NiFe2O4 based cermet materials, by means of determination the interface wetting angle between the molten cryolite electrolyte and the solid anodes interface. The results show that the wetting angle between the electrolyte and carbon anode is larger than 90 angulation, this means that they basically can not wetting; however the nickel ferrate spinel ceramics behaves much better. In regard to the NiFe2O4 matrix materials, their initial wetting angles is 76.9. The initial wetting angles for 1.0wt%MnO2, 2.5wt%TiO2 and 0.5wt%V2O5-doped samples are respectively 56.86°, 52.98° and 51.93°. However, after 50s later, all the wetting angles came down below 15°.

Jan 1, 2015

By A. Blackmore, D. Baker, L. Human

"Mechanical mixing equipment is common in a wide variety of mining, metals and process applications, such as hydrometallurgical reactors, solvent extraction, digestors, and tanks for storage of slurry or hydrocarbons. Computational Fluid Dynamics (CFD) has been applied successfully to single-phase mechanical mixing problems for several decades and is established as a reliable design tool. As computational power and CFD codes have improved over the years, there have been significant advances in modelling capabilities including improved models of turbulence, interaction of rotating and stationary components, multiphase flows, and modelling of free surface interfaces, for example. This paper will provide an overview of the application of CFD to mechanical mixing problems. First, it will review the traditional single phase Multiple Reference Frame (MRF) approach and introduce a range of advanced modelling techniques. Three examples of the application of CFD to industrial mixing problems will be given. It will be demonstrated that CFD is an effective tool for reducing technical risk in design, for identifying the root-cause of mixing problems, and testing modifications to existing operations."

Jan 1, 2015

By P. Müller, W. J. Przybylowicz, V. M. Prozesky, D. de Bruin

"Abstract -The common style of gold mineralization in the Basal Reef and other auriferous conglomerates of the Witwatersrand Supergroup comprises clusters of gold grains occurring interstitially to quartz and pyrite pebbles as well as gold accumulations attached to the surface of and infilling hairline cracks and fractures in round, compact, detrital pyrite. The latter textural association is generally interpreted as a result of remobilization of originally detrital gold during regional metamorphism and related hydrothermal fluid circulation. There is general agreement that, although gold solubility was Iow, ore modification occurred during the metahydrothermal event, but uncertainty exists about the magnitude and scale of gold remobilization .Micro-textural and chemical investigation of compact round pyrite and associated gold accumulation has established that gold is preferentially deposited on chemically heterogeneous pyrite surfaces. Combinations of alternating high- and low-As zones in pyrite result in mixed np-type conductivity accompanied by electron exchange and the reduction-driven deposition of gold at the cathode. This mode] does not explain gold accumulations which are not immediately linked to chemical heterogeneities and it is inferred that an additional control on the deposition of gold was exerted by physical defects which lead to zones of increased charge density and/or areas of focussed conductivity. The inferred precipitation mechanisms suggest that submicrocopic physical and chemical controls are the important factors that determined the sites of gold nucleation and that precipitation mechanisms based on physicochemical changes of the hydrothermal system were not involved. The Basal Reef contains on average close to 5% of round, detrital, chemically zoned pyrite which provides a large number of electrochemically active pyrite surfaces. The extremely effective electrochemical precipitation mechanism together with the low solubility of gold in Witwatersrand fluids is the main reason for the spatially restricted remobilization of gold in the conglomerate reefs."

Jan 1, 1994

By B. A. Watters, G. A. Parslow, F. H. Mcdougall

Carbonate-rich rocks occur at several localities within the Flin Flon volcanic sequence of the eastern Amisk Lake area. The rocks occur in two areas: as a group of small occurrences on islands within Amisk Lake and as two much larger linear belts running parallel to the regional structure east of Amisk Lake. Mineralogically, the rocks consist of talc and Ca-poor ankerite with occasional graphite. Segregation of these minerals and colour variation impart a well-defined planar fabric to the rocks and where the units are fairly continuous (e.g. Mosher Lake), their trend and attitude suggests a concordant relationship to the volcanics. Major and trace analysis of22 samples confirms the presence of two types, with one type being represented in each of the two areas. Most of the elements studied can be used to characterize the two groups, but three elements in particular give a clear separation: Mg, AI and Ni. Recalculation of the major element analyses, on a water and carbonate-f ree basis, indicates that one group (large concordant bodies with high MgO, high Ni and low AI20.J is altered ultrabasic material of peridotitic or dunitic composition. Because no relict igneous material is observed, and the contacts are apparently very sharp, it is possible that the hydration-carbonization process occurred simultaneously with intrusion, .in a closed system. The other group (small occurrences with relatively low MgO, low Ni and high AI203J represents alteration of basaltic rocks. AIthough some analyses suggest the introduction of calcium, as carbonate, along with the volatiles, the major oxides have remained remarkably stable during the alteration process(es).

Jan 1, 1981

By S. Markstrom

The Boliden AITIK copper mine is located 100 kilometres north of the Arctic Circle in northern Sweden. A pre-feasibility study was conducted in 2005 with the aim of increasing the capacity of the existing processing plant. After analysis, options to upgrade the existing plant were abandoned in favour of building a new processing plant, with higher capacity and therefore greater profitability. A new plant could be designed with greater flexibility to make potential future expansions easier. A feasibility study for a new 36 Mt/y processing plant including fully AG grinding circuits and flotation was completed in 2006. The project was approved by the Boliden board shortly thereafter. Construction started in the beginning of 2007 and was completed during 2009. Commissioning of the new plant was undertaken in the first half of 2010. The grinding circuit consists of two lines with each line consisting of a 22.5 MW AG mill and a 10 MW Pebble mill in closed circuit with a spiral classifier. The nominal production level is 2 200 t/h for each grinding line. This paper presents the start-up and operation of the grinding circuit.

Jan 1, 2012

By C. Tissot, R. Palmer

"Due to the low concentrations of gold, direct measurement of gold concentration in ore on belt has not been seriously considered to now. Pre-concentration or sorting strategies have largely consisted of particle sorting based on secondary characteristics such as colour, which can be successful in select cases. CSIRO has produced sample measurement results using gamma activation analysis of ~300 gm samples with accuracies of around 30 ppb at best. With this encouragement, a feasibility study into gold ore measurement on belt for the purpose of sorting pods of gold ore has been undertaken. The study described here included, prototype design options with existing industrial Linacs, extensive Monte Carlo modelling of measurement sensitivity and shielding, further sample measurement, a study of the interaction of target measurement accuracy and sorting efficiency, and a rough estimation of potential economic benefit. The projected model sensitivity of around 0.1-0.15 ppm (1 standard deviation) in 10 seconds for 1 ppm average feed result in good bulk sorting performance and intriguing economic potential.INTRODUCTION Pre-concentration or sorting strategies for gold ores have largely consisted of particle sorting based on secondary characteristics such as colour or density, which can be successful in select cases (Klein, 2010). No method is available to measure gold content for sorting in particles or even in bulk on belt, principally due to the low concentrations of gold present. In fact, in many cases it is difficult to do rapid bulk grade measurements of base metal ores with concentrations many orders of magnitude higher. By a fortunate quirk of nature gold is particularly amenable to gamma activation analysis (GAA). CSIRO has performed extensive work in GAA of samples of crushed ore (Tickner, 2017). This has resulted in the Photon AssayTM technique that is currently being commercialised through the CSIRO spinoff company Chrysos. The technique relies on the recent availability of industrial high intensity X-ray sources such as Linacs which are currently being used in industry for security, medical and sterilisation applications. This development has led to CRC ORE funding a feasibility study to determine whether on-belt measurement of gold concentration is possible at a rate and accuracy sufficient to be useful for bulk sorting, where pods of ore are diverted rather than individual rocks. The study in the first instance is based on Monte Carlo modelling that has successfully predicted the performance of the sample based gold measurements. As well as the measurement feasibility consideration was also given to the likely heterogeneity of gold ores and hence the degree to which useful separation could be achieved. This is then tied to a back of the envelope evaluation of the order of magnitude economics of bulk sorting in an example deposit."

Jan 1, 2017

By P. Fellner, A. Sýkorová, J. Thonstad, J. Jurišová, V. Khandl

Adsorption of S02 on alumina used in the aluminium industry, so-called smelter grade alumina, was studied in the temperature range 15 C-120 C. The specific surface area of the smelter grade alumina was 88 m2/g. It was found that at temperatures lower than 40 C, sulphur dioxide is bonded to alumina reversibly by physical forces, and the adsorption can be described satisfactorily by the Langmuir adsorption isotherm. The heat of adsorption was estimated to be -33 kJ.mor1. At temperatures in the range 80 C- 120 C, which prevail in dry scrubbers in the aluminium industry, the heat of adsorption was determined to be -56 kJ.mor1. When S02 was adsorbed at temperatures higher than 80 C, about 30 % of the S02 could not be desorbed when heating the samples up to 250 C. In the presence of S02 and oxygen, the formation of sulphate was determined at temperatures above 90 C.

Jan 1, 2006

By G. W. Govier

The origin and limitations of the conventional and empirical equation for the interpretation of the results of back pressure tests on gas wells are discussed. Difficulties in data interpretation arise from many causes, including Jack of flow stabilization, uncertainties in connection with the friction calculation, and the effect of turbulence near the sand face in the reservoir. A procedure is developed to ac-count for the turbulence effect. This is based upon the theoretical equation for laminar steady state flow and current knowledge of turbulent steady state flow. The procedure involves the expression of the equation for combined laminar-turbulent steady state flow in terms of a turbulence contribution factor. This factor. is shown to be dependent mainly upon the flow rate per unit of pay thickness and the reservoir permeability. The method of interpretation permits the use of judgment based upon the theory and present day under-standing of laminar-turbulent flow and is considered an improved method

Jan 1, 1961