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By M. Z. He

Attractive particle interactions which underpin the sliming of gangue mineral particles onto valuable mineral phases are encountered in a number of flotation circuits. Sliming leads to poor flotation recovery of the valuable minerals and high recovery of the gangue particles in the concentrate. To mitigate sliming, low molecular weight poly-electrolytes are commonly used as dispersants during pulp conditioning prior to flotation separation of the valuable and gangue mineral phases. In the present work, the sliming mechanism of sericite onto chalcocite and the influence of interfacial chemistry and two anionic copolymer dispersants (carboxylate substituted polyacrylamide, polymer Cyquest 3223 and sulfonate substituted polymaleic acid, polymer P80) on the sliming interactions were probed in the pH range 5~9. It was shown that the sliming occurred under solution conditions where both chalcocite and sericite particles were negatively charged, as evidenced by their apparent particle zeta potentials. The suspension pH had a profound effect on sliming process as the extent was markedly greater at lower than higher pH. The sliming was found to be due to the chalcocite dissolution, Cu (I) release and oxidation to Cu (II), followed by hydrolysis and specific adsorption, leading to sericite particle surface charge reversal and the formation of electropositive sites on chalcocite surface in the pH range 5~9. Addition of polymer Cyquest 3223 or P80 not only increased the magnitude of zeta potentials of both sericite and chalcocite particles but also reduced the formation of Cu (II) ions and complexes, which mitigated the sliming behaviour. The adsorption of polymer Cyquest 3223 or P80 at 3 g polymer / kg solid or more had a significant impact on the zeta potentials of both sericite and chalcocite particles. Sericite-chalcocite particulate adsorption studies showed that sliming was completely suppressed via an electro-steric repulsion mechanism resulting from anionic polymeric dispersant adsorption at dosages > 3 g polymer / kg solid.

Jan 1, 2014

By A. Qaredaqi, M. Mohammadi

Wet High Intensity Magnetic Separators, for short, WHIMS are used for recovery of Iron ores with low magnetic susceptibility. A Jones patent WHIMS with "grooved plates" matrix is being used in Dry Tailing processing line in Hematite Recovery Plant at Golgohar mining & Industrial Co. for recovery of Hematite. In this kind of separators Matrices are used for increasing the Magnetic field intensity and providing high magnetic field gradient. The laboratory WHIMS in Golgohar Iron Ore and Steel research Institute is capable to provide a background magnetic field strength up to 0.85 Tesla and in presence of ‚expanded metal? matrix, magnetic field intensity could increase up to 0.9 Tesla. More than 50% of feed particles in this separator were finer than 36 micron and recovery of these particles needs more magnetic field intensity. Hence, ‚Grooved Plates? matrices with Js= 2 Tesla and 3.8 mm gap were constructed. Measurements indicated that magnetic field intensity around the matrix will increase to 1.25 Tesla. Graph of Magnetic field intensity around the matrix to background magnetic field intensity was plotted and a model with Rsquare= 0.9 was offered. In addition, magnetic field gradient and magnetic force were calculated. In WHIMS with feed top size of 150 micron, the main effective forces on separation process are the magnetic force and the hydrodynamic drag force. With assuming that the particles are smooth and spherical and the flow is laminar, Recovery of fine magnetic particles is problematic in this separator because of drag force. Considering these facts and mentioned model, finest particles that are recoverable in different magnetic field intensities were calculated. Computations illustrated that with magnetic field intensity more than 0.8 Tesla, particles as fine as 4 micron are theoretically separable but it should be noted that in practice a larger attractable particle size would be expected.

Jan 1, 2014

By Ana Elisa Casas Botero

The Rhodococcus opacus microorganism was evaluated as a biocollector for flotation of barite. The electrophoretic behaviour of the mineral, before and after R. opacus interaction, was evaluated and showed that the cells adhesion shifted the mineral zeta potential curves. Adhesion tests were suggested a high affinity of the bacteria for barite. The experiments of the adsorption rate of the R. opacus on the mineral surface showed fast kinetics, achieving a maxim of cell adsorption after 5 minutes. Adsorption isotherm curves for barite could be categorized as Langmurian (L) type II. The best bioflotability results for barite achieved values around 75% for a R. opacus concentration of a R. opacus concentration of 250 ppm in the pH around 5.0. The studies were compared with the flotation of barite using a traditional collector. The bioflotation experiments were discussed considering the obtained adhesion tests. The results were supported by the Thermodynamic approach for selected pH values. The fundamental flotation studies showed the paramount potential that R. opacus presents as a biocollector and its possible application in the mineral flotation industry.

Jan 1, 2014

By Y. Posedko Eugene, S. S. Gudkov, Yu. E. Emelyanov, A. V. Bogorodsky, A. V. Boldyrev, S. V. Balikov

"The article presents the results of precious metals leaching using halogen solvents and their precipitation on a sorbent in the process of pressure oxidation. A technology of pressure oxidation – carbon-in-leach treatment (POX-CIL) of refractory sulphide gold-bearing flotation concentrates with the addition of a halogen solvent and a sorbent was developed based on the laboratory studies and pilot plant tests. The technology involves the following steps: oxidation of a flotation concentrate; precious metals dissolution and recovery on a sorbent; precious metals elution; electrolysis of eluates; smelting of cathode precipitates with producing Dore beads. This approach ensures oxidation at least 98% of sulphides and gold of more than 95%. The POX-CIL process have the following patents: a patent of the Eurasian Patent Organization No.017438 “A method of processing materials containing precious metals and sulphides” and a patent of the Russian Federation No.2625146 “A method of precious metals recovery from refractory sulphide gold-bearing materials”.INTRODUCTION Gold-bearing ores are classified as readily amenable to cyanidation, or non-refractory, and not readily amenable to cyanidation, or refractory [1]. Special attention should be given to the three most common technological types of gold-bearing ore materials, according to the Irgiredmet’s classification: pyrite-arsenopyrite ores with finely disseminated gold locked in sulphides (physical depression of gold in cyanidation process); cupriferous gold-bearing ores, when cyanidation comes along with chemical depression of gold by mineral compounds (cyanisides); carbonaceous ores showing higher sorption activity to precious metals dissolved in cyanide. Direct cyanidation of refractory sulphide gold-bearing materials does not provide high recovery of precious metals. There are the following methods of refractory gold-bearing ores and concentrates preparation to subsequent gold recovery: roasting, fine grinding, bacterial and pressure oxidation (POX) [2]. Existing POX-cyanidation flowsheets involve high costs due to a large amount of process operations and using expensive and environmentally hazardous sodium cyanide."

Jan 1, 2018

By Diogo R. Prado, José Aurélio M. da Luz

Drying operation can have a major importance in a mineral processing undertaking. The proper sizing of dryers can ensure the specified dewatering level without energy wastage. However, often the sizing of fluidized bed is done disregarding the actual residence time distribution (RTD) of the particles inside the reactor. In this case it is usual to adopt the average residence time as a design criterion. In this work, we have quantified the effect of residence time distribution on drying, ensuring that a previously adopted fraction of the particles remains inside the reactor for the required time lapse needed for drying. Design criteria such as particulate flow rate and drying time, taking into account the statistical distribution of residence time was studied, matching the thermodynamic and fluid dynamic aspects of the drying process. Experimental tests carried out have confirmed the RTD for a teetering bed as the same for a canonical ideal mixing system. Although the fluidized bed volume using the proposed formulation was higher than that found for the average time based procedure, the efficiency gain in drying has proven advantageous.

Jan 1, 2014

By F. Waanders, Campbell. Q.

This project was specifically aimed at using increased acceleration separation, as a method to optimize the recovery of gold in an ore body mainly consisting of hematite where the specific gravity of gold is much higher in comparison to the carrying material, making it possible to separate gold from other materials like silica, base metals and their oxides, usually associated with gravitation-gold-recovery-processes. The ore body investigated in this project originated from a gold reef containing a large portion of gold locked inside the gold pyrite complexes, which was mined and treated in a conventional way. After gold extraction, the material was pumped to a tailings dump and the gold extraction of this dump was investigated. In order to assemble a concentration plant setup, the head grade and size distribution of the dump and bulk sample were determined accurately. Chemical analysis and mineralogical examination were done on a representative sample of the bulk sample, to determine the chemical composition of the material. The results obtained thereof were evaluated and a pilot plant was configured. A bulk sample was processed in the pilot plant and the results were evaluated. The results at optimum acceleration forces applied, resulted in a recovery of 5% of the mass, with a gold concentrate of 90 g/t Au, which represented 58% recovery of the gold. The hematite with high specific gravity as main phase positively influenced the high acceleration separation process. It proved that if the specific gravity of particles in a suspension were increased, high acceleration separation could be applied effectively to separate much smaller particle sizes.

Jan 1, 2014

By Mohsen Hashemzadehfini

Nowadays heap leaching has become established as a mineral processing technology for treatment of some low grade minerals such as copper, gold, and zinc, etc. Heap height, particle size, leach reagent consumption, and metal recovery are four important metallurgical parameters in a hydrometallurgical process like heap leaching. This paper investigated the effects of heap height and particle size on copper recovery as well as acid consumption. Three heap heights of 2, 4 and 6 meters and two particle size fractions of less than 25.4 mm and 50.8 mm were selected as variables in the experiments. The research results showed the inverse relation between heap height and copper recovery as well as acid consumption. Under given conditions, the copper recoveries of minus 25.4 mm ore are 78.63%, 66.27% and 52.88% higher than that of minus 50.8 mm samples for the heap heights of 2, 4, and 6 m, respectively. Both copper recovery and acid consumption increase with decreasing particle size. Keywords: heap leaching, heap height, particle size, acid consumption

Sep 1, 2012

By K. Price, G. Wang, L. R. Moore, Y. R. Xiong, J. Gu

"Sand is a naturally occurring granular material that is a result of the physical or chemical breakdown of rocks. Raw/natural sand contains various minerals, and it is this combination of minerals that brings the value to the construction aggregate industry. However, it is the quartz component of sand that is valued in its application as industrial silica in glass, high purity quartz, foundry sand, and oil and gas fracturing. Depending on the industry, the grade requirements can be the concentration of SiO2, particle size or shape, as well as contaminants such as the heavy refractory minerals, clays, fines, and alkali metals. With the ever declining mineral feed grade, processors continue to face challenges making the industry specific concentrate grade. As such, it becomes more important to tailor make the processing reagents to fit the mineral, processing conditions, and desired quality specification. This paper focuses on the application of novel collectors towards the beneficiation of sand for each of the major industrial silica applications. INTRODUCTIONQuartz is a mineral composed of a framework of silicon and oxygen atoms. It is the second most abundant mineral in the Earth’s continental crust. There are many species of quartz, which are defined by the particle size, shape, and color. Silica sand is one of those species, which is the byproduct of the physical or chemical breakdown of quartz containing rocks or crystals. Geologist define silica sand as a silica mineral with a particle size between 0.05 and 2 mm in diameter (Zdunczyk, 2001). Silica sand has significant value to society in recreation (beach sand and toy boxes), construction aggregate (concretes and asphalt), industry (iron & steel casting, fracturing proppants, and glass), as well as specialty products such as semiconductors or silicon wafers used in electronics.The aggregate business is the dominant consumer of silica sand products. Conversely, glass making, foundries (casting material), abrasives, and fracturing proppants are the dominant applications for industrial silica sand. Not much beneficiation is required for sand products going into the construction industry, other than sizing and scrubbing to remove clay. However, the industrial silica sand applications are dependent on particle size, shape, and degree of contaminants, which sets the market value (table 1). Therefore, as the more specialty products are produced, more sophisticated techniques and chemistry need to be applied to ensure the appropriate quality is met."

Jan 1, 2018

By A. Y. Senchenko, S. G. Rybkin, A. V. Aksenov

"Oxidized nickel ores are important source for nickel production in Russia. Considerable explored reserves of oxidized nickel ores with relatively low nickel content, about 0.6-1.4%, are concentrated in the Ural region of Russia. Conventional process flowsheet with the use of blast matte smelting, applied in particularly by JSC “Ufaleynickel”, proves itself as extremely low-margin technology. This paper will examine development of a new more cost-efficient process involving integrated treatment of oxidized nickel ores using the ore from Serovskoye deposit as an example. Target products of this process are hydrate residues containing up to 15 % of nickel and 0.3 % of cobalt, as well as saleable salts of magnesium sulphate and ammonium suplphate. This innovative process includes roasting of a mixture composed of ground ore and sulphuric acid at 650 °?. Sulphate roasted product is then leached in a weak sulphuric acid solution with the following separation of liquid from insoluble solids. Sulphate solution is neutralized by aqua ammonia in two stages until media pH is 3.0-3.5 and 7.5-8.0 with detachment of iron- and nickel-bearing hydrate residues respectively. The mother solution is boiled out resulting in salt crystals which are then dried and roasted at 500-600 °? to obtain magnesium sulphate. The gases generated during salts roasting are captured with production of ammonium sulphate. The developed technology demonstrates higher potential in terms of its economics and eco-efficiency comparing with the conventional process. This innovative technology for integrated process of oxidized nickel ores was patented in Russia.INTRODUCTION Development and industrial implementation of efficient technologies to process oxidized nickel ores is a very important task for non-ferrous metallurgy of Russia. The main reasons for the required technical upgrade of the plants processing oxidized nickel ores is depletion of rich ores, increase of energy resources costs, amplification of environmental and production standards. Due to this, transition from conventional pyrometallurgy to cost-effective hydrometallurgical technologies of ore liberation and solutions processing is logical and corresponds to the worldwide practice of Ni production from oxidized nickel ores."

Jan 1, 2018

By Leon Lorenzen, Victor E. Ross, Anton W. Kleingeld

Key to successful innovation, whether at organization, industry or national level, is the alignment and utilization of resources in the most appropriate and efficient way. Innovation needs to be directed strategically, and it needs to be auditable in a systematic and integrated fashion. In the light of these considerations, this paper describes the construction and use of a topographical map of the innovation landscape. The purpose of the map is to provide a holistic view of the key factors that enable innovation (the so-called ’landmarks’), how well they are aligned to support a particular type/nature of innovation in the organization, and to identify possible gaps. The significance (importance) and height (performance) of the landmarks in supporting and enabling innovation within the organization is determined by means of a selfappraisal audit. The topography of the landscape derived thus is subsequently interpreted in terms of the organization’s particular innovation strategy and environmental context. The application of the Innovation Landscape Methodology is illustrated in a number of organizations within the Mining and Minerals Industry of South Africa. Important observations and conclusions regarding the strategic alignment of enabler strengths within these organizations are made.

Jan 1, 2003

By R. S. Wang

The flotation of pyrite which be pretreated by electrochemical ways under external controlled voltages in different pH is explored. The floatability of pyrite is increased indistinctively after being pretreated in acidic and xanthate environment; Whereas, it is increased obviously between 400~800 millivolt in alkaline and xanthate condition. The reason for higher recovery of pyrite is that oxida-tion reaction, which results in S0 and S02, takes place on its surface, and that ethyl xanthate is oxi-dized into dixanthogen. In the meantime, the kinetics and mechanism is also studied.

Jan 1, 2014

By M. Rudolph, D. H. Hoang, N. Kupka

"Froth flotation has been subjected to modelling since the 1930s and there is a large variety of approaches that intend to portray the entire process. Among these, three fundamental models could be considered exhaustive: the Pyke model [1], the Yoon model [2] and the Schwarz and Koh model [3]. The first model makes use of the generalized Sutherland equation collision model, the Dobby-Finch attachment model and its own stability model, the second model considers an extended DLVO approach for the attachment and stability whereas the third model makes use of computational fluid dynamics. Using a scheelite ore as a test case, a specific batch flotation test was repeated ten times and analyzed for chemical assays, mineralogical studies and froth properties. The detailed data are used to feed the three flotation models aforementioned in order to compare the outcomes of the three approaches, their capacity to reflect reality and to predict it. This article intends to pave the path towards reliable process models incorporating in depth mineralogy information, e.g. surface liberation, particle size and particle shape. KEYWORDS Froth flotation fundamental models, scheelite, automated mineralogy, critical assessment. INTRODUCTION In mineral processing, only three approaches aiming at describing froth flotation fundamentally could be considered exhaustive: Pyke’s collision and sliding approach [1], Yoon’s kinetic approach [2] and Schwarz and Koh’s approach [3]. The models will hereafter be referred to as Pyke model, Yoon model and Schwarz and Koh model. The first model makes use of the generalized Sutherland equation collision model, the Dobby-Finch attachment model and its own stability model, the second model considers an extended DLVO approach for the attachment and stability whereas the third model makes use of computational fluid dynamics. All three approaches rely on the widely accepted idea that flotation is a kinetic reaction dependent on a flotation rate constant kp, as expressed in Eq. [4]:"

Jan 1, 2018

By Kari Niiranen, Patrick Krolop, Viktoria Töyrä

Luossavaara-Kiirunavaara AB (LKAB) operates an iron ore mine, three beneficiation plants and three pelletizing plants in Kiruna, Sweden. The current methods of separation in the beneficiation plants are wet low intensity magnetic separation (WLIMS) and reverse apatite flotation, where the WLIMS stage is regarded as the crucial part of silica separation from the ore. Currently, the high-grade iron ore deposit of Kiirunavaara has a low grade of silica in situ, of approximately 3.0% SiO2, but the silica grade is expected to increase in the deeper parts of the deposit with a complex silicate mineralogy. An increasing silica grade will affect especially the production of direct reduction pellets (LKAB DR Oxide Pellets), one of the main products of LKAB in Kiruna with an average silica grade of under 0.75% SiO2. The silica grade in the magnetite concentrate is normally limited to a maximum level of 0.55% SiO2 in order to achieve the required chemical composition in the pelletizing process. In order to study the possibility to reduce silicate content in the magnetite concentrate (pellet feed) in the beneficiation plants in Kiruna obtained by wet low intensity magnetic separation (WLIMS), enlarged mineral processing test work was carried out in the LKAB’s mineral processing laboratories in 2016. The test work consisted of comminution, low intensity magnetic separation and reverse cationic silicate flotation at laboratory scale, complemented by screen analysis, chemical assays and mineralogical investigation. The results of these mineral processing test work showed that the magnetic separation is not sufficient to reduce the silica content in the magnetite concentrate, particularly in the case of the high-SiO2 ore type B2-a. The reverse cationic flotation can be regarded as a possible solution to reduce the silicate content in the magnetite concentrate obtained by WLIMS and to achieve the required silica grade of less than 0.55 % SiO2 in the pellet feed. The results of this study provide a good basis to understand the behaviour of different silicates in the existing beneficiation process. Furthermore, it serves valuable information for development of new beneficiation processes and for investment in new equipment at the beneficiation plants in Kiruna in the future.

Jan 1, 2018

By C. S. Gundewar

About 90% of the barytes produced the world over is used for oil and gas drilling as weighting agent in drilling mud to control pressure, prevent blow out and provide lubrication. This is because of its unique properties like high specific gravity, water insolubility and intentness. India is one of the leading producers and exporters of barites. The Mangampeth Baryte deposit in Cuddapah district of Andhra Pradesh, India being the largest single deposit in the world having a reserves of about 80 million tonnes. Approximately 50% of the total reserves of grey barites of Mangampet deposit assays less than 92% BaSO4, the minimum stipulated grade for oil and gas drilling industries. To reach and recover the high grade barite, the overlying low grade has necessarily to be mined out and removed. At present this is being stacked separately at the mine site involving lot of labour and transport cost. Considerable barites is contained in the dumps adversely affecting the conservation and creating lot of environmental hazards. IBM being the premier organization in India in the field of conservation of minerals and environmental protection in mining has recognized the importance of adverse effect of these huge dumps at site. The Ore Dressing Division of IBM, Nagpur has characterized these dumps and developed the flotation process on a sample assaying 66% BaSO4 and 23.3% SiO2. The flotation concentrate obtained assayed 93.7% BaSO4, 2.38% SiO2 with BaSO4 recovery of 80% and meets the requirement of the oil industry. The flotation concentrate being non-wetable, can not be used as such as weighting agent, and hence the collector coating on the concentrate was removed either by acid treatment or heating to make it water wetable. The concentrate was 92% -325 mesh and having a specific gravity 4.3. The barites concentrates so produced meets the size, grade and specific gravity specifications required for use in oil drilling industry. Apart from the financial benefits the process augurs well for the commercial exploitation of these huge dumps in terms of (1) additional recovery of these valuable minerals and conservation, (2) reduction in dumps value, (3) improvement in environment and offering an excellent potential for export.

Jan 1, 2014

By P. Han

The preparation technological conditions and regeneration method of two novel granulated adsorbing materials of rectorite/fly ash composite (Material 1) and rectorite/water quenched - slag composite (Material 2) and the use of them to remove heavy metals from copper smelting plant wastewater have been studied. The experimental results showed that under the preparation conditions with the ratio of rectorite to fly ash or water - quenched slag of 1:1, the amount of the additive (Industrial Starch, IS) of 15% (Material 1) or 10% (Material 2), the addition of 50% water, and the calcination temperature of 500? (Material 1) or 400? (Material 2), the efficiency of heavy metal removal with the granulated materials was the best, whereas the ratio of disintegration loss was the lowest. Under the treatment conditions of natural pH, and with the addition of the granulated materials of 0.07g/cm3 (Material 1) or 0.05g/cm3 (Material 2), a reaction time of 60 minutes (Material 1) or 40 minutes (Material 2), and the adsorption temperature of 25?, the efficiency for the granulated materials to remove Cu2+Pb2+Zn2+Cd2+ and Ni2+ from the copper smelting plant wastewater was 98.9, 97.5, 96.7, 90.2, and 79.1, (Material 1) or 98.2, 96.3, 78.6, 86.2, and 64.2, (Material 2), respectively, and the quality indexes of the wastewater after treatment conformed with the first level of integrated wastewater discharge standard (GB8978-1996). When the adsorption of heavy metal ions on the surface attained saturation the granulated materials could be regenerated by washing with 1 mol/L sodium chloride (NaCl) solution and still with quite good heavy metal removal efficiency. The granulated adsorbing materials had the advantages of high efficiency of wastewater treatment, easy method of solid-liquid separation and regeneration, and a broad prospect of applications.

Jan 1, 2014

By Ashish Agarwal

For a correct evaluation of the performance of any process, it is important to reconcile the data gathered in the plant from the material balance point of view for all the streams flowing in and flowing out of the process unit. There are two main approaches to reconciliation of data, which involve minimization of the sum of the squares of: (i) the closure residuals and (ii) the component adjustments; both weighed with the estimated variances of the components. Though, these approaches have served us well, it has not been possible to ascertain if the reconciled values for various components and the split factors obtained using these approaches are truly the best estimates. In this paper, this aspect has been investigated by analyzing pseudo-experimental data of known error structure on size classification of particles in a hydrocyclone. Three types of basic error structures were considered for the measured component values: absolute error, relative error and chi-square error. The error structure was modified by adding a random component of error using normally distributed random numbers corresponding to zero mean and different levels of variance. By carrying out a large number of simulation experiments, it has been shown that in the presence of random errors, irrespective of the basic error structure of data, which is usually unknown, the chi-square error minimization criterion can be used to obtain most reliable results. Keywords: data reconciliation methods, chi-square error minimization

Sep 1, 2012

By R. D. Alorro

Melting has become a popular pre-treatment method for municipal solid waste (MSW) incineration residues in Japan. Although the method is effective in stabilizing the hazardous organic sub-stances such as dioxin, it concentrates the heavy metals such as Zn, Pb, Cu, and Cd in a newly formed fly ash (melting fly ash). Melting fly ash is classified as a hazardous waste because of the leaching potential of these heavy metals in landfill environment. Extraction and recovery of these metals seem to be more environmentally and economically attractive than disposing the material to landfill after immobilization process. This study proposes a Carrier-in-Pulp (CIP) method as a new hydrometallurgical route to reject and recover heavy metals from fly ash. In this method, a carrier material which recovers the extracted metals is added simultaneously with fly ash to leaching solutions and is harvested from the pulp by physical separation method like magnetic separation or sieving. To demonstrate the effect of CIP method, shaking flask experiments were conducted under various conditions using NaCl solution as lixiviant and iron powder or granular activated carbon as carrier materials. In the CIP method using iron powder, more than 97 wt% of Pb and Zn were extracted from the ash to the solution phase. However, the iron powder which was harvested from the pulp by magnetic separation, recovered only Pb (more than 94%) through cementation, leaving behind Zn ions in the solution phase. Due to this problem, granular activated carbon (GAC) was considered as an alternative carrier material. Single- and multi-metal adsorption experiments using granular activated carbon were conducted as a preliminary study. Around 85% Pb and 88% Zn were recovered by GAC in the single-metal adsorption experiment, while 60% Pb and 70% Zn in the multi-metal experiment. These results showed that activated carbon was superior to the iron powder since it was able to recover both Pb and Zn through adsorption. The leaching test conducted on the residue after the CIP-Fe treatment revealed that the solubilisation of Pb was successfully suppressed to meet landfilling guidelines.

Jan 1, 2014

By U. S. Chattopadhyay

The estimated requirement of the nation by the year 2020 is approx. 80 Mt of steel and more than 0.2 million MW installed capacity of the electricity, thereby increasing the consumption of the coking and non-coking coal, which is expected to be in tune of about 75 Mt & 500 Mt respectively. One of the major deleterious factors in achieving the goal is the deteriorating quality of the feed coal used in both steel and power industries. Indian coking coals, in general, are typified by high ash, high inert (both organic and inorganic), low rank, low reactive macerals content, heterogeneous petrographic make-up, inferior coking properties and poor amenability to washing, thereby necessitating suitable washing measure. Coke-based steel industries in India require washed coking coal containing ash % varying between 17-19. The situation demands taking on immediate challenges to fill up the gap between the requirements and supply of coking coal. This paper reviews the R&D attempts in this laboratory and throws light on the key measures as long-term solution to the problem. Search for alternative source of coking coal, like LVC coal and their judicious preparation technology. The low volatile coking coal (LVCC) constitutes about 50% of the total coking coal reserves in India. These coals are characterized by high raw coal ash content (37 to 40%) and very difficult washability potential. If these coals are treated in the existing washeries, which are generally 2 or 3-product systems, the cost of clean coal is high as the byproduct sale value is low. It has been proposed to produce a new type of by product, which enjoys high demand and good coking properties.

Sep 1, 2012

By Shailin Lalloo, Allan B. Nesbitt

A fluidised bed was exposed to high gravities by placing it in a centrifuge. The bed expansions were measured and compared with the bed expansions predicted by the Richardson-Zaki model (1954). The Richardson-Zaki model was found to predict effectively the fluidisation behaviour of defined particles in this increased gravity environment.

Jan 1, 2003

By Aidan Giblett, Karen McCaffery, Robert Dunne

"A worldwide decline in competency levels of practicing metallurgists over recent decades has become clearly evident and is a common topic of discussion among senior practitioners and professional associations. The associated impacts on the industry are material and include operational inefficiencies, missed optimisation opportunities and suboptimal new plant designs. There are many contributing factors to this condition. Decrease in competency is particularly evident both in regions where imbalance between supply and demand has led to a general reduction in experience levels for comparable roles over time and in emerging regions where a rapid rise in demand for practitioners has occurred in conjunction with rapid economic development and industrialization. The context, depth and breadth of education curricula and levels vary with location such that solutions to the technical competency dilemma may need to be developed specifically for each region with these influences in mind. Delivering, demonstrating and maintaining competencies are a critical requirement of undergraduate training and ongoing professional development. Other factors such as generational and cultural characteristics and expectations, political influences, role requirements and employment reward and recognition systems all play a critical role in determining if core competencies can be effectively developed, applied and subsequently maintained. This paper reviews factors impacting and some common approaches to competency development. The authors’ experiences in the management of professional development efforts within the global industry are reviewed and a blueprint proposed to address industry requirements in this area."

Jan 1, 2014