Browsing by Author "Fernando, WLW"

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An assessment of aluminosilicate refractories from in-situ deposits
(Department of Mining and Mineral Engineering, 1984-05-28) Fernando, WLW
It is possible to predict the behaviour of Aluminosilicates prior to its use in iron and steel practice. The methods adopted by the author comprise extraction of the material from bore holes, bcneficiation and fabrication into suitable specimens for carrying out specific tests. Particular care was taken for the grog preparation, size grading, mixing and powder pressing prior to the heat treatment. In short, this paper summarises the test methods developed by the author to examine the grade of in-situ specimens, recovered from bore hole surveys.
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Conversion of Sri Lankan iron ore into high quality pellets to be used in iron making
(2015-06-24) Guluwita, SP; Fernando, WLW; Munasinghe, RGNS
Iron ores and lime are two of the available raw materials in Sri Lanka for iron making. However, proven reserves of iron ore deposits in Sri Lanka have not been scientifically estimated as yet. There is no indication of the occurrence of coal deposits in Sri Lanka for the utilization to produce iron using the blast furnace. Therefore, it is important to investigate the possibility of producing high quality iron ore pellets using locally available resources as a substitute for sponge iron which is imported to use in the cupola furnace. In this study it was aimed at obtaining high quality iron ore pellets with required strength, porosity and degree of reduction by varying pellet compositions, firing temperature and soaking time. The pellets prepared with 100 parts of Dela Iron ore, 7 parts of Aruwakkalu lime and 7 parts of coke which was sintered at 1250°C for 10 min gave the optimum crushing strength, apparent porosity and degree of reduction. The subsequent melting of these pellets in the lab scale cupola recovered iron as “metallic pigs‟, which conformed to alpha iron having high purity.
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Design and fabrication of a spiral classifier for off-shore sand washing
(Department of Earth Resources Engineering, 2008-05) Udawatte, NBB; Siriwardene, HP; Samaratunga, SPND; Udayanga, WAC; Rupasinghe, SN; Theeparuban, B; Fernando, WLW; Karunaratne, S
The rapid growth of construction industry has created a significant demand for sand. Consequently, it has increased the exploitation rate of river sand giving rise to adverse environmental impacts. Therefore, the tendency now is to find alternatives for river sand avoiding massive environmental damages. Among the potential alternatives, offshore sand could be the best alternative, because of particle size distribution and availability. However, the demand on offshore sand is low, due to its soluble Cl- content which could influence badly on the structural properties of concrete. As a solution, sea sand could be stored in open air until the Cl- content is decreased to acceptable limits (<0.075% by weight) under the influence of rain water. However, considering the increasing demand and changing weather patterns, the above method appears to be inappropriate to meet the demand. In this research, a spiral classifier was designed and fabricated in order to wash offshore sand from salts and other suspended materials. The separation is done on sea sand by optimizing critical parameters of the spiral classifier such as feed rate, rotational speed of spiral, inclination angle of the spiral and weir height.
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Designing a vibrating sieve
(2014-06-30) Fernando, WLW; Basnayake, BMV; Fernando, HAS; Rajapaksha, HMPB; Rodrigo, SAIJ; Theres Lathanky, J
This report presents the development of proto type of a Vibrating Sieve. The preliminary objective of this project is to design a prototype of a vibrating sieve to be used for clay refinery process, which can be easily maintained with available materials in the market and cost effective. Secondary objective of the project is to gather knowledge, practice and experience on technology, equipments and methods available in the mechanical designing activities in the workshop and develop skills and experience in team work spirit
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Designing of a vibrating sieve
(Department of Earth Resources Engineering, Faculty of Engineering, University of Moratuwa, 2005) Fernando, WLW; Basnayake, BMV; Fernando, HAS; Rajapaksha, HMPB; Rodrigo, SAIJ; Theres Lathanky, J
This report presents the development of proto type of a Vibrating Sieve. The preliminary objective of this project is to design a prototype of a vibrating sieve to be used for clay refinery process, which can be easily maintained with available materials in the market and cost effective. Secondary objective of the project is to gather knowledge, practice and experience on technology, equipment and methods available in the mechanical designing activities in the workshop and develop skills and experience in team work spirit.
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The flow behavior of mineral particles through glass funnels
(2007) Rohitha, LPS; Dissanayaka, DMDOK; Fernando, WLW
In industry the flow of mineral particles in silos playa very important role in the recovery of these particles into containers for bagging and transport. The silo design parameters and particulate properties are restricting the flow behavior in silos thereby controlling the rate of packing into containers as a finished product or else in the utilization of these particles for subsequent unit operations down the processing line. Further, telescopic silos have been introduced recently in mining industry [1] for dust suppression in quarries, gravel pits by minimizing the distribution of dust and fines in to the surrounding areas. There are factors affecting the flow behavior in silos [2] such as particle size, angle of repose. moisture content, static electric charges of powders and so on. In order to simulate the behavior of mineral particulates in silos, glass funnels of different dimensions have been chosen due to their transparency.
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Flow Behavior Of Mineral Particles Through Silos
(2008) Rohitha, LPS; Dissanayaka, DMDOK; Fernando, WLW
Flow behavior of dry minerals in silos has been investigated initially with glass funnels with different orifices. Thereafter, funnel was scaled up to a pilot plant (Silo) with adjustable orifices at its discharge end. The flow rates vs particle size were investigated with beach mineral sands and quartz grains of varying sizes obtained from river sand. Zero flow rates were observed at d/D ratio of 1/5-1/4 for large size sand grains. For small grains of size about 200 microns zero flow rate was observed for orifice diameters 1.5, 2.0 and 3.5cms respectively due to 'floc' effect arising probably from static electrical charges of the powder and the humidity of air prevailing at the time of investigation.
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Flow behavior of mineral particulates through conical silos
Rohitha, LPS; Fernando, WLW; Dissanayake, DMDOK
Silo or Bin is used very widely in Mining, Processing, Pharmaceutical, Cement, Ceramics and Packaging industries. The purpose of the silo is to hold material until it is ready to use in subsequent processes such as processing, chemical, physical or transport. According to the Oxford Dictionary ( DK illustrated), a Silo is a pit or airtight structure in which green crops are kept for fodder or it can be a pit or a tower for the storage of grains ,cement etc, or it is an underground storage chamber for guided missiles. The capacity of a silo may vary from Kgs. to Tons. In this research, a silo is used as a conical shaped container with an orifice through which mineral sands of varying sizes were allowed to pass and their flow behavior were examined with respect to their material physical properties and silo parameters. In the first stage of the project, the flow behavior was studied using beach mineral sands with glass funnels with orifice diameters 3.5, 4.8 and 8.0 mm and heights 8, 10 and 24cm respectively to simulate silos of varying orifice. The capillary part of the funnels were cut uniformly at the neck regions to prepare them for the tests. It was decided to use naturally occurring geo-materials of different mineralogical, chemical, and physical characteristics for the investigation. For this purpose, samples of beach sand from several locations along the western coast of Sri Lanka were collected and sampled using the sampler riffler, thereafter sieved through 2mm sieve to remove sea shells and other extraneous impurities followed by spiral separation and tabling. Subsequently, magnetic separation and high tension separation were carried out to separate magnetic and non magnetic fractions according to the standard procedure. The fractions separated consisted of ilmenite, rutile, garnet and zircon. A sample of silica was also obtained from the glass sand deposit at Naththandiya. Each sand sample was sifted using the standard test sieves. Before conducting the flow properties of these minerals they were dried at 110°C for 2 hours and the test was conducted 3 times and the average flow rate obtained thus was plotted against the particle size and the diD ratio for each material. Where, d = average particle size diameter and, D = funnel orifice diameter. Interpretation of flow rate measurements and analysis of data indicate that all beach mineral sands used in the study had the same flow rate pattern. The mass flow rate vs diD curves consisted of three significant zones representing bridging effect, constant gradient zone with a negative gradient and the no-flow zone, which spilled over to the fine particle fractions. The effects of charge particle nature, moisture contained, repose angle, surface morphology of mineral and the orifice diameter of the funnel on the flow properties were also investigated. As the particles studied were naturally occurring, they were sub-angular having rounded edges. Another series of experiments were conducted using spherically shaped silica gel particles having diameters 1.2,2.2, and 3.3 mm respectively. In the second stage, a pilot plant in the form of a conical silo was fabricated in the workshop and the experiments were conducted using mineral samples each sample weighed approximately 3 to 6 kg. The samples for the second stage was obtained from two sources, Lanka Mineral Sands Ltd and the river sand pits at lngiriya. After a tedious process of size separation mostly involving sorting of particles of different size fractions by hand picking and sieving. The results obtained agree very closely with those obtained using the glass funnels. It is evident that there are three zones in the performance curve -flow rate vs particle size with the bridging effect region corresponding to diD ratios of 1/4 to 115 for relatively larger size particles and the region exhibiting the 'floc effect' resulting from residual charges in the fine sizes and air trapped within the floes. The mineral particles used were pre-dried (dried at 110°C for two hours).However, the presence of moisture in the powder seems to have a significant contribution on the flow rate. - The importance of the performance curve and its characteristic features have been discussed and also the relevance of the performance curve in designing silos.
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The importance of humphreys spiral in heavy mineral Separation
(Engineering Research Unit, Faculty of Engiennring, University of Moratuwa, 1997-11) Fernando, WLW; Hettiarachchci, P
The Humphreys Spiral Concentrator which was developed in 1943 is now being used extensively for the concentration and the recovery of heavy minerals. In Sri Lanka, this device is very effectively used by the mineral sand industry and in the beneficiation of glass sands. The advantage of this over the Wilfley Table is that the capacity of Spirals are high and the running costs are very low. The study conducted by the author has shown that this method can be profitably used in the upgrading of Gold bearing sands. In this study, samples of river sands collected from Welioya, Kaltota area were subjected to gravity separation using the Spiral followed by the Wilfley Table. The concentrates obtained by this research showed Gold values ranging from zero to 0.0019%. The discovery of Cyanide heap leaching followed by activated Carbon Adsorption now makes it possible for samples containing considerably less than 0.0003% to be considered an ore. Thus, the beneficiated samples have economically recoverable Gold values.
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Magnetic induction assisted levitation of metallized particles in sintered dela Iron ore pellets
(2010) Gobikrishna, S; Raguratnam, E; Guluwita, SP; Munasinghe, RGN De S; Fernando, WLW
Degree of metallization is on important characteristic of reduced iron ore pellets when determining its applicability in the iron and steel making industry. If the degree of metallization is about 95 -97% induction furnace could be used in making alloy steels. If the degree of metallization is less, it may be employed in an arc furnace. In the present research a simple and economical method has been suggested to examine the degree of metallization of reduced iron ore pellets by magnetic induction assisted levitation. This may be adopted to quantify the degree of metallization of reduced pellets after a suitable calibration. Further research is in progress
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Processing of high grit ball clays
(2001) Mayooran, D; Gunasekera, HKM; Cristin, M; Fernando, WLW
In Sri Lanka high grit ball clay is not mined al all from the ball clay deposits as the process adopted in purification is Dry Processing. It involves dry grinding causing high wear and tear to the grinding mill. Hence the cut- off grade of ball clay for Mining and processing is determined by the grit content which is limited to a maximum of 2%. In this research the authors have experimented on high grit ball clay and have suggested a flow sheet for its processing Though the capital outlay is high in the method suggested . authors’ aim is to make use of this mineral deposit industrially with optimum utilization.
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Quartzite mining and sand manufacturing
(Department of Earth Resources Engineering, 2006-10) Kalubowila, KDLSSP; Gomes, DGNM; Arundathie, KWDD; Dharmarathne, WGAD; Kumara, WAP; Welideniya, HS; Fernando, WLW; Karunaratne, S; Dissanayake, DMDOK; Ratnayake, N; Chaminda, SP
Manufactured sand is considered as an alternative to match the rising demand of river sand in the construction industry. The basic concept is to crush Quartzite, the source rock to produce sand. This report focuses on sand manufacturing from a quartzite deposit at Dampellessa in Kurunegala district in Sri Lanka. The deposit has to be mined in multiple benches of 10m height and 80° of maximum working angle. Blasting for rock loosening and subsequent ripping with dozers, excavators and hydraulic hammers is recommended as a mining method. The manufacturing process involves crushing of the aggregates after. which grinding and milling is simultaneously done by a specially designed perforated ball mill. Product is made on for customer specifications and suitable for concerting, plastering and as mortar.
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Recovery enhancement of graphite tub-dust to 99+ carbon using a mill modification
(Department of Earth Resources Engineering, 2007-10) Samarakkody, SATI; Rohitha, LPS; Fernando, WLW; Karunaratne, S
There are many mineral processing methods that are being used in mining and mineral processing industries. One such method very widely used in the graphite industry is froth flotation. During the present study, graphite having a 82- 85% C, with a low market, has been up- graded to Carbon 99% + grade by using flotation. It has been observed that the rod weight in the grinding operation has a major role to play. If the rod weight is increased over and above the critical weight, over grinding takes place. Further, it has been found that pH and the type of collector also play major roles in the graphite processing. Laboratory trials indicate that by using the rod weight of 625kg to 725kg in the rod mill and the particle size range of 75 to 150 microns, maximum recovery of 85% could be achieved at 99% + C grade.
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Reduction of iron ore pellets using coke bed technique
(2010) Abewardhana, DMUC; Gunasekara, PP; Guluwita, SP; Munasinghe, RGN De S; Fernando, WLW
This research project was carried out with the intension of producing high quality iron are pellets for iron making using processed Data (Rathnapura) iron ore and Aruwakalu lime is coke bed. Different pellet compositions were prepared by changing the percentage of Dela ore, lime and coke and thereafter firing them under different temperatures with the aim of obtaining required physical properties enabling its subsequent reduction to metallic iron. Reducibility of pellets at different temperatures were done by the packed coke bed crucible method developed by the authors, for those pellets which satisfied the required porosity and compression strength parameters. By observing the micro structure of specimen before reduction and after packed bed reduction, the quality of the pellets so produced was assed. This method may be adopted in the lab as a relatively cheap method to study reducibility of iron ores.
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Resource recovery from photographic waste by electro-winning
(2006) Wijeyekoon, SLJ; Rohitha, LPS; Fernando, WLW; Dissanayaka, DMDOK; Karunarathna, S
Industries such as mining and industrial minerals, metallurgical, photographic, textile, leather and chemical produce wastewater containing heavy metals that are hazardous to man and the environment. Indiscriminate discharge of these effluents pollutes natural resources and disturbs vital eco systems. On the other hand most heavy metals in these effluents are rare in nature and hence are expensive industrial raw materials. Therefore a sustainable pollution control option for these industries should aim at resource recovery. Successful isolation of heavy metals from wastewaters will not only render such effluents non hazardous but also make waste management an attractive proposition, thus leading to multiple benefits in terms of resource conservation, pollution control and treatment cost savings. Photographic waste effluents arise from X-ray, lithographic and photographic operations. The photosensitive medium used in these operations is an emulsion of fine Ag halide matrix in gelatin. During fixing, the Ag+ is removed by the fixer solution. The developer and bleach solutions also contain the Ag heavy metal. The recovery of Ag" from such wastewater may be done by electro-winning, metallic replacement, evaporation, ion exchange, reverse osmosis and electro-dialysis. However many process parameters of these methods are not readily available and opportunities exist for optimization of methods to improve removal efficiencies. The aim of this research was to investigate the application of electro-winning technique for selective removal of Ag metals from photographic wastewater. The advantages of the application of electro-winning technique are no hazardous sludge generation, isolation of pure elements, no pretreatment requirement and l
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Rheological behaviour of mineral (clay) suspensions
(Department of Earth Resources Engineering, 2007-11) Balasooriya, BARD; Kumara, WC; Prasanna, TGS; Sasekaran, M; Fernando, WLW; Karunaratne, S
In this research, a rotating cylinder viscometer was designed and fabricated to study the structure formation of particles in a mineral suspension and its influence on the relative viscosity q/qo. It is known that the value q/qo is affected by the concentration of suspended mineral particles in an aqueous media. The relative viscosity q/qo thus obtained is related to the volumetric concentration of suspended particles by the equation q = qo + k(f>, where the value k depends on particle behaviour in aqueous medium and is related to the shape, zeta potential and the volume % of particles. By this method it is possible to classify the suitability of surface active minerals in mineral deposits on the basis of the k factor. The rotating cylinder viscometer consists of a cylinder, of known dimensions, immersed fully in a mineral suspension so that it can be rotated by applying a mechanical couple (Force X distance) acting on the cylinder by two identical falling weights which are tied to each other by an inextensible string. Initially the cylinder is made to rotate in water of known viscosity by fully immersing it, thereafter in the known suspension. From the rates of rotation, the viscosities can be compared and hence the k values.
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The effect of carbon and firing temperature sequence on CHICO mill-scale and Its applications in metallurgy
(2010) Paranavithana, RM; Shyamali, MAS; Guluwita, SP; Fernando, WLW
Mill scale is a surface layer of iron oxide form on steel billets during hot rolling. Currently this is a waste material and constitutes nearly two percent of the yearly output from CHICO. The current research shows that this waste material could be recycled into useful products. One of them is a feed material to a cupola furnace to produce pig iron; and the other is an abrasive material for metal polishing. The processing and heat treatments utilized for these products are discussed in this paper. Further research is in progress.
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The effect of dolomitic lime and the firing temperature on the properties of pellets produced from dela iron ore
(2009) Dharmasiri, PDSC; Aboonidhal, MA; Guluwita, SP; Fernando, WLW; Munasinghe, De SRGN
Iron ores and lime are two of the available raw materials in Sri Lanka for iron making. However, proven reserves of I iron ore deposits in Sri Lanka have not been scientifically estimated as yet. There is no indication of the occurrence I coal deposits in Sri Lanka for the utilization to produce iron using the blast furnace. Therefore, it is important to investigate the possibility of producing high quality iron ore pellets using locally available resources for the utilization as a substitute for sponge iron, which is imported. In this study it is attempted to optimize the dolomitic I lime content and firing temperature in producing high quality iron ore pellets.
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The use of prototype pelletizer for iron ore preparation
(Department of Earth Resources Engineering, 2007-11) Arachchi, GARMG; Jayarathna, STCK; Jeyarupan, G; Thusyanth, M; Fernando, WLW; Karunaratne, S
In this research, a pelletizer was designed and fabricated as a prototype machine to make iron ore pellets to be used as a blast furnace burden. During the iron manufacturing process, iron ore powder of specified particle size distribution is mixed with a binder, coke powder and calcium carbonate. The raw materials are intimately mixed and thereafter treated with a critical amount of water while the pelletizing is taking place. During the pelletizing process the ore particles are subjected to horizontal and vertical forces applied mechanically coupled with the adhesive forces created by water molecules. The forces acting on iron ore particles would facilitate by bringing the particles together and thereby giving uniformity to the pellet. The addition of water has to be carried out carefully as it is a critical parameter. After careful drying, firstly in air and thereafter in an oven at HOC for 2 hours, the green pellets thus obtained were sintered to produce the final pellet to be used in the blast furnace.
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The use of saltern bitterns for manufacturing magnesia refractories.
(1998) Fernando, WLW
In Srilanka there are salterns where bitterns are produced as potential magnesia compounds , from which magnesia can be precipitated , consolidated and heat treated under certain conditions to produce high quality magnesia pellets which are of similar quality to that produced in the U.K. This is confirmed by the microscopical, chemical and X-ray diffraction studies. This research describes the recovery of magnesia in the lab scale using the sea water bitterns ,from Hambantota salterns , which is presently discarded.