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By A. Bezama

For over a decade European countries have addressed contaminated sites by developing technologies for managing both polluted soil and groundwater. This development has not only been driven by health and environmental aspects, but also because of economic pressures, as the remediation and redevelopment of derelict areas can be a meaningful alternative to undeveloped areas for the establishment of new industrial, recreational, housing and service locations. In most developing countries, however, the subject of contaminated sites is a new environmental issue that authorities have recently started to deal with. Among these countries, Chile has just started to prepare the country's legal context as well as to foster the formation of research and investigation groups that will deal with the exploration, investigation and management of contaminated sites. That requires a comprehensive technical, scientific and legal support in this stage. Goal of this article is to present the state-of-the-art technologies for site remediation currently applied in industrialized countries, in order to identify the most interesting approaches that can be implemented within the Chilean situation, especially considering the influence of the copper mining industry on the soil and groundwater quality of the environment surrounding their production facilities.

Jan 1, 2007

By S. R. Amos, N. O. Lotter, A. L. Hannaford, J. F. Oliveira, D. W. Broughton

"Ivanplats Ltd appointed Xstrata Process Support to perform the flowsheeting development work for their hypogene and supergene geomet units of the Kamoa Copper deposit, located in the Democratic Republic of the Congo. Through systematic flowsheet development using modern Process Mineralogy, the optimised milestone flowsheet delivered a saleable concentrate grade of 32.8% Cu at 85.4% recovery with hypogene ore, and a saleable concentrate grade of 45.1% Cu at a recovery of 83.4% for supergene ore. The significant value of this development is that a single flowsheet will treat both hypogene and supergene ores and produce saleable concentrates. Further work to advance the flowsheet performance has been identified for investigation in the near future.INTRODUCTIONLocation and Description of the Kamoa DepositThe Kamoa copper resource is located some 40 km west of the city of Kolwezi, in the south west of the Katanga Province of the Democratic Republic of the Congo, in the region of Central Africa. Drilling at Kamoa in 2008-2009 had discovered laterally continuous, sediment-hosted, high-grade stratiform copper mineralisation in a newly discovered copper district that forms a previously unrecognised western extension of the famous Central African Copperbelt – which hosts such world-class deposits as Kolwezi, Tenke-Fungurume, Konkola and Nchanga. This discovery showed that the western end of the Copperbelt in the Congo does not terminate at Kolwezi (Friedland & Broughton, 2009). The resource contains hypogene and supergene geomet units with a transitional zone located inbetween the (upper) supergene and the (lower) hypogene. In the hypogene unit, the major copper sulphides are bornite, chalcopyrite and chalcocite, whilst in the supergene, the sequence is led by chalcocite, then bornite, and finally chalcopyrite. Covellite is present in both units as a minor copper sulphide. Both geomet units will be mined and treated in one concentrator, either as blends or as campaigns."

Jan 1, 2013

By M. Sider, D. L. Piron

"The cost of energy is a growing factor in the cost of zinc production. Electrowinning from sulphate solutions with periodical reverse current or from acidic chloride or alkaline solutions could be the way to lower costs. A comparison of the energy consumption for electrolysis shows that the alkaline solution may be considered the most promising alternative. IntroductionZinc electrowinning from sulphate solutions is a very energy intensive process (typical specific energy usage : around 3.1 kWh / kg zinc). This energy consumption represents 35% of the total cost of electrolysis and is the most important cost component.In order to lower costs, the energy efficiency of the sulphate process should be improved or alternative processes should be developed. In this laboratory, that objective has resulted in research on electro winning in sulphate solutions with the use of periodical reverse current (PRC) and in acidic chloride and alkaline solutions.Some of the results obtained in this laboratory and already published and new experimental results reported in this paper make it possible to present a more critical comparison of the energy consumption of the three processes mentioned.ExperimentalThe experiments at constant current were carried out as described previously. Specific conditions are indicated in Table I. Current efficiencies were obtained by weighing deposits.ResultsThe best energy consumptions for electrolysis obtained in this laboratory for the three media are presented in Table I. More detailed results can be found in the papers already mentioned."

Jan 1, 1988

By Jochen Franke, Derek D. Lichti

"This paper gives a brief introduction and presents recent enhancements in the MillMapper technology developed for thickness gauging and condition monitoring of liners in grinding mills used for mineral comminution. It also introduces the recent expansion of MillMapper functionality aimed at mill operational optimization. MillMapper uses calibrated laser scanner data captured inside a mill to determine thickness at several million points on all liner surfaces at feed, shell, and discharge ends with millimeter accuracy. Data capture takes nominally 5 minutes, hence interruption to mill operation is negligible.The paper is structured as follows. First, a review of the technology and discussion of recentlyimplemented innovations such as liner change out forecasting, automatic ball charge volume and weight measurement, and automatic mill liner volume/weight measurement for mill operational control or load cell calibration are presented. Combined weight information provides control over load related issues such as load fill levels for relining, or start-up load after reline. Feature descriptions are followed by a listing of the numerous advantages over existing techniques and the benefits to operations. Results from the application of MillMapper are presented throughout.INTRODUCTIONThe need for thickness gauging of liners of grinding mills used for mineral comminution is well known but the task is rarely completed to a satisfactory standard. Liner failure resulting from excessive wear can have expensive consequences. Furthermore, mill performance as well as liner wear are known to be correlated to lifter bar geometry (Napier-Munn et al., 1999; Rajamanni et al., 2005). At present, the following techniques are routinely used to gauge the thickness of mill liners:1. Visual inspection;2. Ultrasonic thickness gauging (for steel liners); and3. Physical inspection (e.g. nail inserted in rubber liners)"

Jan 1, 2008

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 Ralph J. Holmes, David McCallum, Alan Roberts, Rolando Orense, University of Auckland, Tobias Krull, Tom Honeyands, Kenneth Williams

"The safe ocean transport of bulk commodities like iron ore, coal, nickel ore, manganese ore and bauxite by large bulk ships is vitally dependent on the stability of the cargo under the influence of wave induced ship motion. Safety standards are set by such bodies as the International Maritime Organisation (IMO) with recommended tests for the assessment of bulk commodities. Since the 1960s, the bulk cargo code (BC Code) commenced defining methods to determine the Transportable Moisture Limit (TML) for transportation of bulk commodities. By the latter part of the 1960s, three TML test methods were defined, namely the Flow Table, Proctor-Fagerberg and Penetration tests. All three tests were predominantly aimed at determining TML values for mineral concentrates.More recently, bulk commodity producers, Maritime Organisations and Port Authorities worldwide have been investigating whether commodity based TML methods better reflect realistic safe ship transportation than the current concentrate based TML test methods. In these investigations, the relationship between the mineralogical and particulate parameters of specific commodities with respect to cargo stability and moisture retention has provided insights into the development of tailored TML test methods. To this end, an AMIRA International project (P1097) undertaken by CSIRO, TUNRA Bulk Solids, the University of Newcastle and the University of Auckland assisted the IMO Technical Working group to investigate the relationship between iron ore fines characteristics and a new TML test specific for iron ore fines bulk cargoes.A review of the three standard concentrate based TML methods and characterisation studies of iron ore fines, as well as cyclic triaxial testing to determine liquefaction resistance, resulted in the development of a modified Proctor-Fagerberg method for determining the TML of iron ore fines. Of particular importance in determining TML is mineral composition, porosity, particle density and allowing time for moisture equilibration."

Jan 1, 2016

By S. Banisi, A. Haji-Zadeh, A. R. Hasankhoei, M. Maleki-Moghaddam

At the concentration plant of the Gol-E-Gohar Iron Ore Company (Iran) three 9m × 2.05m AG (Autogenous) mills (fixed speed) are used in parallel in a dry operation. The test works conducted in a scale down mill with a diameter of 1m indicated that conventionally used "deflector" type liners did not provide efficient environment for grinding. In this research, to improve the grinding efficiency, a new design using low profile end liners incorporating radial ribs of proper height was investigated. In order to determine an appropriate liner design at different operating conditions, a 100cm×10.8cm model mill was used for experimentation. The special design of model mill made it possible to increase the radial ribs height in steps of 6mm up to 18.5mm. The transparent end of the mill enabled accurate trajectory determination by image analysis. The results indicated that the new lower height profile deflectors and 15.5mm-height (14.5cm in industrial scale) radial ribs improved the mill performance while avoiding excessive pressure drop across the mill and wear on the liner. The image analysis showed that the use of new liners increased the distribution of coarse particles across the mill cross section from 28% to 35%. A new liner design was proposed by decreasing the number of liners in each slice from 5 to 4 pieces. The thickness of the inner head liners reduced from 45cm to 30cm and the outer deflector liners replaced by radial ribs. The distance between the feed and discharge inner head liners increased from the original 115cm to 145cm which increased the effective length of the mill by 26%. The new design reduced the weight and volume of end liners by 9% and 23%, respectively. It was predicted that the new liners design increases the mill throughput by 10% and reduces the metal consumption by 20%.

Jan 1, 2016

By M. Bryson, S. Broom-Fendley, A. E. Brady, W. Dawes, G. Beer, N. Sehlotho, S. Al-Ali, F. Wall

The Songwe Hill Rare Earth Element (REE) Project in Malawi is a near surface carbonatite-hosted deposit with synchysite and apatite as the key REE bearing minerals. A strong focus has been placed on understanding the REE mineralogy of the Songwe Hill carbonatite as REE mineralogical characterization is a crucial component at all steps, ranging from exploration to production, in the development of REE deposits. Extensive mineralogical work has been completed at Camborne School of Mines (CSM), Natural History Museum (NHM) London, British Geological Survey (BGS), Nottingham, Aberystwyth University, Wales, Mintek, South Africa, and SGS Inc. Canada (SGS). The following analytical techniques were used: scanning electron microscopy (SEM), electron microprobe analysis (EMPA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and QEMSCAN®. The detailed studies have demonstrated that while synchysite is light-REE enriched as expected, apatite, abundant in all stages of carbonatite emplacement at Songwe, is anomalously enriched in mid- to heavy-REE relative to apatite in other carbonatite deposits. The distribution of REE within synchysite and apatite at Songwe has had important implications for the direction of the metallurgical work with respect to the behaviour of light and heavy REE through the flotation and hydrometallurgical stages of the flow sheet.

Jan 1, 2014

By Baseer Abdul, Edouard Asselin

Hydrometallurgical leaching of sulfide concentrates of copper and nickel at medium temperature (150°C) produces residues that contain sulfur and iron bearing minerals and phases. During leaching, and depending on various process parameters, iron may be precipitated as hematite, goethite, jarosite or other oxyhydroxides, which may be more or less crystalline. Hematite is the favored precipitate because it is the most environmentally stable and does not ad/absorb as much copper, nickel or other solution constituents during precipitation. However, the low solubility of iron during the medium temperature processing of sulfide ores can favour the formation of poorly crystalline, nano-scale iron oxide/oxyhydroxide phases. In some cases these phases have been positively identified as the metastable ferrihydrite, which transforms into iron oxides such as goethite, hematite and magnetite over time. A better understanding of what may help drive this transformation during leaching would ultimately result in lower valuable metal losses and more stable leach residues. Higher acid concentrations result in increased copper extractions and favor the formation of hematite during concentrate leaching, rather than other metastable phases. Furthermore, commercially available water displacement formula “WD40®” and other novel reagent(s) affect Fe precipitation and sulfur chemistry, leading to very different process outcomes such as improved extractions and larger, more easily separated, sulfur particles.

Jan 1, 2017

By Jürgen Antrekowitsch, Gerardo R. F. Alvear Flores, Mehmet Ayhan, Christoph Zschiesche

Synergies between copper and lead extractive metallurgical processes enable the processing of a broad range of polymetallic materials. However, this complexity also brings some challenges expressed in terms of complex intermediates and final products. For instance, based on the limited solubility of Cu and Ni in crude lead bullion additional phases will appear during the crystallization of the melt. Beyond the need for continuous optimization of metallurgy the control of phase solidification is a further important pillar to achieve a more efficient process by minimizing the amount and cycles of reverts. This paper describes the microscopy study of one of the most relevant intermediate in the Cu and Pb metallurgy, the Cu based alloy and highlights the importance of applying a well-controlled cooling sequence to improve the overall process efficiency. INTRODUCTION One of the key aspects in Aurubis’s 2025 vision is to move towards the implementation of a multi metal recovery strategy. The implementation of this new multi metal vision is supported by the long tradition of the company, founded in 1866 as Norddeutsche Affinerie, and further developed by adopting modern copper smelting and lead smelting technologies for the processing of primary and secondary materials. The combination of these assets have already build the basis for processing of complex materials in the copper and lead circuits implemented in Aurubis’s facilities. The addition of a new smelting facility, will enhance these capabilities. Aurubis current flowsheet combines Cu, Pb and Zn metallurgy. This includes primary smelting of copper concentrate, processing of secondaries (residues, slimes, slags) and recycling materials (scrap, shredder material, e-scrap). These broad range of materials contain not only the mentioned base metals but also a number of minor metals that requires to be properly managed to ensure efficient recoveries and quality of the targeted metals.

Jan 1, 2019

By A. McGrath, M. Trovant, M. Haque

Minimizing energy consumption is a priority for many industrial facilities. Metallurgical and gasification processes produce dirty syngas (CO and H2), which offers the potential for energy recovery. However, syngas handling can pose an explosion risk and even minor leaks can result in poor workplace hygiene. Furthermore, many jurisdictions around the world now discourage wet syngas handling due to limited water availability and secondary pollution. Hatch has developed a 100% positive pressure gas handling system that targets these safety hazards without using fresh water. The implementation of a system for calcium carbide smelters at Qinghai Salt Lake Industry Co. (QSLIC) in China is profiled as a case study.

Jan 1, 2015

By M. B. Kime, A. T. Kaniki

"Grinding tests were conducted on an oxidized copper-cobalt ore using a pear-shaped ball mill. Twelve mono-sized ore fractions were prepared and wet ground batchwise. The mill was run for 0.5 to 30 min intervals. The shortest interval provided data more closely related to the breakage function (B) because less secondary breakage was hypothesized. Some selection function (S) and B parameters were determined. Remaining parameters were estimated using a population balance model simulator. To evaluate the kinetics model, an unsized ore sample was also milled. Predicted and measured particle size distributions (PSDs) agreed well, suggesting that S and B parameters can be used for continuous operation mass balances.RÉSUMÉ Des essais de broyage ont été menés sur un minerai oxydé de cuivre-cobalt à l’aide d’un broyeur à boulets piriforme. Douze fractions de minerai de dimension unique ont été préparés et broyés en voie humide en lots. Le broyeur était mis en route à des intervalles de 0,5 à 30 minutes. L’intervalle le plus court fournissait des données plus étroitement liées à la fonction d’abattage (B) car d’après l’hypothèse avancée, le besoin d’abattage secondaire était moindre. Certains paramètres de la fonction de sélection (S) et de B ont été déterminés ; les paramètres restants ont été estimés à l’aide d’un simulateur de modèle d’équilibre de population. Pour évaluer le modèle de cinétique, un échantillon de minerai non calibré a également été broyé. Les compositions granulométriques (PSD, de l’anglais particle size distributions) prévues et mesurées correspondaient bien, ce qui laisse penser que l’on peut se servir des paramètres S et B dans le cadre d’équilibrages massiques en fonctionnement continu. INTRODUCTIONSize reduction of solids is a very energy intensive and highly inefficient process. It consumes approximately 5% of the electricity produced worldwide (Rhodes, 1998), and more than 50% of the total energy used in mineral processing plants (Walkiewicz, Lindroth, & Clark, 1996). An increase in grinding efficiency can therefore result in significant reductions in operating costs. This often amounts to determining the optimal design configurations for milling an ore sample in a laboratory mill under standard conditions. Prior to optimizing the milling stage, the requirements for downstream processing in terms of particle size distribution (PSD) need to be understood because low liberation and overgrinding will lead to future problems. Once this is done, it is also important to clearly understand the breakage properties of the ore. The kinetics of size reduction in tumbling mills are often determined using two probabilistic functions: selection and breakage (Austin & Luckie, 1972). Knowledge of the selection and breakage functions also enables the prediction of the PSD for a given ore sample."

Jan 1, 2017

By S. Kelebek, B. Ingram, C. Gibson, T. MacNeil, M. Aghamirian

"The beneficiation and upgrading of pyrochlore from its ores is carried out through flotation. In industrial practice, upgrading is conducted in a two-stage flotation process in which pyrochlore flotation is carried out after gangue mineral pre-flotation (carbonate, silicate, sulphide or phosphate reverse flotation). In this study, the flotation of pyrochlore from a low grade carbonatite ore was performed at the laboratory scale following a two-stage flotation process in which carbonate minerals were floated in advance of niobium minerals. In parallel, a simplified flotation process was developed in which pyrochlore was floated directly from gangue minerals at increasingly acidic pH. Laboratory results indicated that both two-stage and direct flotation provided similar results in terms of niobium grade-recovery. Based on these results, a large scale, integrated pilot plant was conducted using a direct flotation flowsheet. While the elimination of reverse gangue flotation resulted in flowsheet simplification, the dissolution of carbonate minerals and the subsequent effect of dissolved cations on the floatability of pyrochlore added an element of complexity. A comparison of results from locked-cycle laboratory testing and pilot plant testing highlights the challenges of scaling up a complex flowsheet. A case is made for the direct flotation process and the key parameters to achieving success in large scale direct flotation of pyrochlore are discussed.INTRODUCTIONPyrochlore (Ca,Na)2Nb2O6(OH,F) is a niobium bearing mineral which has been the primary global source of niobium since the first pyrochlore mine commenced operations in the late 1960s (Gibson et al., 2015a). Preceding the discovery and development of high grade pyrochlore deposits in North and South America, the majority of global niobium supply came from gravity concentration operations of columbite (Fe,Mn)Nb2O6, across Africa (Perrault and Manker, 1981)."

Jan 1, 2016

By Karl Dufresne

Blasting in geothermally high temperature ground and/or extremely reactive ground is an increasing common challenge for surface and underground mines. Many current PETN based non-electric and electronic detonators have manufacturer published in-hole temperature limits ranging from 55°C to 65°C (131°F to 150°F). When confronting blasthole temperatures above the manufacturer published limits, operations may request site-specific guidance and qualification for use. The advised safe loading window for in-hole PETN based detonators is often too short to be practicable for production blasting. To overcome limitations of PETN based initiation systems, surface mines with high temperature ground and/or reactive ground are known to load blastholes with a qualified high temperature bulk emulsion that are top primed with a cartridge of temperature qualified detonator sensitive emulsion plus an RDX detonating cord downline. As there is no in-hole delay detonator in this system, blasthole timing is accomplished with surface delays. Although this system is safe, top priming and surface delaying does influence floor quality and top size fragmentation, and safe loading windows times reduce blast block size and increase blasting frequency. A mining company with a site characterized by geothermally high temperature ground plus highly reactive ground employed a blasting system like the one described above. The site desires to improve blasting performance by moving to an in-hole delay initiation system that can withstand the site ground conditions. At the request of the mining house, DynaEnergetics developed an electronic initiation system for application in geothermally high temperature ground and/or extremely reactive ground conditions. The DynaEnergetics IGNEO high temperature electronic initiation system is rated for in-hole use in ground up to 150C (302°F) for 48 hours. The detonator consists of a high strength detonator with an HMX base charge and thermally resistant downline. To make up a primer, the detonator is inserted into a booster charge assembly that is fitted with a small HMX shape charge. This high energy primer is designed to be compatible and reliable for firing bulk emulsions, including those with high percentages of urea inhibition to combat reactive ground. Up to 1000 detonators may be programmed in 1ms increments up to 1500ms. The system is controlled by a digital firing panel that can be used with either a wired or wireless trigger.  The system enables high temperature and/or reactive ground sites to utilize in-hole delay initiation and realize the associated performance benefits. Conclusions and Future Work 1] The HMX based electronic initiation system permits bottom in-hole delaying in ground temperatures above 80°C (175°F). As compared to top priming and surface delaying, in-hole bottom delaying is known to improve floor quality, muckpile fragmentation uniformity and reduce oversize. 2] Field evaluation of the HMX initiation system at the Lihir Mine is continuing. 3] Work on the next generation of the HMX initiation system is underway and will bring with it expanded application range and flexibility. 

Oct 1, 2024

By Dani J. Alldrick, Alastair J. Sinclair, Colin I. Godwin

"Abstract - The Stewart mining camp has a long history of precious and base metal mining. The camp is abundantly mineralized, with more than 200 widespread, varied, vein prospects, deposits and orebodies. These show wide variations in the mineralogy of ore, gangue and alteration assemblages, and wide variations in textures and structural settings. This report establishes the timing of the different metallogenic epochs and suggests a specific exploration application for systematic lead isotope analyses.Galena lead isotope ratios from a range of mineral occurrences indicate that all these varieddeposits formed during two main mineralizing events. Lead isotope data from the Stewart mining camp do not provide absolute ages for the formation of mineral deposits, but the relative distributions of data are consistent with dates determined in other studies. One ore-forming episode occurred in the Barly Jurassic and the other in the Middle Eocene. Both metallogenic epochs were brief, regional-scale phenomena. Sorne deposits from the younger mineralizing episode were em­ placed adjacent to or superimposed on the older deposits.Field and laboratory studies show that the two metallogenic epochs are characterized by different base and precious metal suites: Barly Jurassic gold-silver-zinc-lead-copper; and Middle Eocene silver-lead-zinc. Therefore, showings of different ages have different base and precious metal potentials and deserve different exploration emphasis. Lead isotope studies provide a reliable, cost-effective method for evaluating the age and commodity potential of small or recently discovered mineral showings and for setting exploration priorities on properties with several varied mineral occurrences . The determination of the age and metal potential of a prospect at an early stage of exploration may govern the urgency, intensity or even the necessity for further exploration work."

Jan 1, 1993

By Dorothy Walters

As an increase in the number of producers alters fact ors affecting supply, long-term prospects in traditional markets for many minerals weaken. At the same time, conflicts between national and international objectives undermine existing competitive elements in mineral markets and Canadian costs escalate. Such changes may dramatically alter the environment in which the mining industry operates.

Jan 1, 1979

By J. Peace, J. R. Fletcher

"British Steel has increased its usage of stainless steel for bunker, silo and chute linings to reduce maintenance costs and improve productivity.A generation of low cost 12% Cr steels has been specifically developed to satisfy the needs of hardness, flow promotion and through life costing which are demanded by bulk solids handling industries.The range of stainless steels include:• a very hard martensitic grade which is particularly suitable for high stress applications where impact and abrasion are predominant;• a titanium stabilized duplex steel for structural applications, as well as low friction , medium abrasion resistant wear liner plate; and• a ferritic stainless steel with rubber backing for low stress application where flow promotion of product is the predominant requirement.Industrial applications and experiences along with methods of fixin g the stainless steels will be discussed in conjunction with the relative through-life costs of the products.IntroductionBritish Steel has become one of the most efficient steel manufacturers in the world, with improvements seen in productivity, quality, delivery, performance and response to the needs of the worldwide market place.Part of this success stems from reductions in engineering downtime in the key areas of its operations, by the introduction of better engineering design and the use of enhanced materials where significant cost benefits have been identified.The nature of producing iron and steel requires the use and handling of a number of raw materials with wide ranging properties, each calling for a different approach to solving the difficulties encountered in storing and transporting these materials to their respective point of use. Figure 1 shows steel production for 1988-89 where over 30 million tonnes of raw materials were handled in making 14 million tonnes of liquid steel at British Steel's five integrated works.Typically solid raw materials include, iron ore, coal, limestone, ferro alloys and scrap. Intermediate products such as coke and sinter create their own specific handling and wear problems.Coals and ores are shipped into the United Kingdom from several sources, and have a great variety of properties. Some coals can be extremely wet and sticky, whereas others are dry and dusty . The ores handled can vary from wet concentrate and fines to heavy angular rubble and pellets. These raw materials are off-loaded, stored and conveyed through British Steel's own port facilities at Port Talbot, Immingham, Redcar and Hunterston. British Steel also produces the majority of its own coke and all its own sinter. Coke and sinter are frequently handled at elevated temperatures which cause other handling problems."

Jan 1, 1991

By E. Dernedde

A few studies have suggested that the rate of adsorption of hydrogen fluoride on smelter grade alumina is determined by kinetic factors. However, no performance equation for dry scrubbers has appeared in the literature so far. Experimental data from a pilot dry scrubber with co-current flow were compared with results of kinetic models of adsorption, film diffusion and pore diffusion. The pore diffusion model was deemed the most appropriate. It was transformed into a performance equation for steady-state operations of dry scrubbers by the inclusion of the alumina recirculation. Operating results of industrial dry scrubbers with co-current flow were successfully evaluated by means of the performance equation. The average fluoride content of the alumina was also estimated by using the pore diffusion model.

Jan 1, 2011

By J. A. Bos, Z. Dai, P. Quinn, A. Lee

A flowsheet is being developed for processing Thompson ultramafic low-grade nickel ores. This type of ore is characterized by high content of serpentinized magnesium silicates which generate slimes during comminution. Flotation of this type of ore proves difficult due to problems associated with the slimes. The flowsheet, based on extensive laboratory and miniplant flotation tests, consists of two key components: desliming by hydrocyclones prior to flotation and using soda ash for pH control in flotation. Satisfactory metallurgical results have consistently been achieved in laboratory full circuit simulation and miniplant tests.

Jan 1, 2009

By Roger Francis

There is increasing use of acid leach extraction methods at elevated temperatures and pressures by the mining industry. In many locations there are limited supplies of fresh water, and waters with higher chloride contents must be used, making conditions more corrosive. The fluids downstream of the main autoclave are hot, acidic, oxidizing and contain chlorides and present a challenge to the mining community to ensure reliable operation. Zeron 100 is a high strength superduplex stainless stee, that offers high corrosion resistance at a cost effective price. The paper presents a combination of laboratory data and service experience, particularly in the aggressive fluids found in downstream processing.

Jan 1, 2010