Beneficiation of thermal coal in India is a relatively new development. For the year 2006, India produced 380 million metric tons of thermal coal, of which only 17 million metric tons were beneficiated coals. One potentially attractive method for upgrading India's coal feed stocks is the air table dry deshaling technology. Dry deshaling offers significant advantages over wet cleaning operations, including reduced surface moisture, enhanced heating value, elimination of processing water and waste slurries, and reduced transportation of large amounts of ash-forming minerals. To evaluate this potential, a pilot-scale air table deshaling unit was tested at three locations in India for the specific purpose of upgrading thermal coals. The field testing confirmed that the separation performance for Indian coals is similar to that which has been achieved at sites in the United States for material in the 50 x 6 mm size range. The data indicate that material with 80% ash and higher can be rejected by the dry deshaler unit with a combustible recovery of more than 90%. Furthermore, a discreet elemental model was developed using PFC3D to understand the process of segregation on a dry density based vibratory table. Analysis was done to show the effect of different forces on the process efficiency. Also, operating parameters and particle properties such as frequency of vibrations, amplitude of velocity, bed depth, particle size and specific gravity were analyzed in the model. The model results were compared with field testing results of dry deshaling air table and All-Air Jig separator. / Master of Science

Beneficiation of fine coal (+500 μm –2000 μm) is a worldwide problem in the mining industry, especially dry beneficiation of fine coal. Coal beneficiation can be divided primarily into two methods, namely wet- and dry beneficiation. Wet beneficiation methods are utilized more in today‘s industry because of the sharp separation efficiency that can be achieved. These processes include wet jigging, dense medium cyclones, spiral beneficiation etc. Due to the lack of a sufficient water supply in some regions around the world including South Africa, dry beneficiation methods are becoming more popular. Recent mechanized mining methods caused the fraction of fines from coal mines to increase over the years. However, due to old inefficient technologies, coal fines contained in slurry ponds could not be beneficiated and had to be discarded. One new dry beneficiation technology that has been used and researched extensively is the fluidized dense medium bed (FDMB) technology. The purpose of this study is to determine whether fine coal can be successfully beneficiated with a FDMB. It also has to be determined whether adding magnetite and introducing a jigging (pulse) motion to the air feed will increase the separation efficiency of the fluidization process. Witbank seam 4 and a Waterberg coal was used in experiments during this study. A coarse (+1180 μm –2000 μm), fine (+500 μm –1180 μm) and a mix of the two samples were prepared and tested. It was found that adding magnetite to the feed of the fluidized bed did not increase the separation efficiency. However, previous studies indicated the opposite results with regards to magnetite addition. The difference in results obtained could be prescribed to the ultrafine nature of the magnetite and the small coal particles size range used. If the presence of fine particles in the bed increases, the stability of fluidization decreases. In turn, the separation efficiency of the process decreases. Subjecting the feed air flow to a pulsating motion did not have a significant effect on separation. Good results were still obtained with jigging experiments, although not better than with normal fluidization. Stratification of coal particles according to quality was evident by the results obtained during experiments. The quality of coal increases from the bottom to the top of the bed. Overall the fluidized bed, in the absence of magnetite, was found to be a sufficient de-ashing process and further research on this technology could be very beneficial to the coal industry. / MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

Beneficiation of fine coal (+500 μm –2000 μm) is a worldwide problem in the mining industry, especially dry beneficiation of fine coal. Coal beneficiation can be divided primarily into two methods, namely wet- and dry beneficiation. Wet beneficiation methods are utilized more in today‘s industry because of the sharp separation efficiency that can be achieved. These processes include wet jigging, dense medium cyclones, spiral beneficiation etc. Due to the lack of a sufficient water supply in some regions around the world including South Africa, dry beneficiation methods are becoming more popular. Recent mechanized mining methods caused the fraction of fines from coal mines to increase over the years. However, due to old inefficient technologies, coal fines contained in slurry ponds could not be beneficiated and had to be discarded. One new dry beneficiation technology that has been used and researched extensively is the fluidized dense medium bed (FDMB) technology. The purpose of this study is to determine whether fine coal can be successfully beneficiated with a FDMB. It also has to be determined whether adding magnetite and introducing a jigging (pulse) motion to the air feed will increase the separation efficiency of the fluidization process. Witbank seam 4 and a Waterberg coal was used in experiments during this study. A coarse (+1180 μm –2000 μm), fine (+500 μm –1180 μm) and a mix of the two samples were prepared and tested. It was found that adding magnetite to the feed of the fluidized bed did not increase the separation efficiency. However, previous studies indicated the opposite results with regards to magnetite addition. The difference in results obtained could be prescribed to the ultrafine nature of the magnetite and the small coal particles size range used. If the presence of fine particles in the bed increases, the stability of fluidization decreases. In turn, the separation efficiency of the process decreases. Subjecting the feed air flow to a pulsating motion did not have a significant effect on separation. Good results were still obtained with jigging experiments, although not better than with normal fluidization. Stratification of coal particles according to quality was evident by the results obtained during experiments. The quality of coal increases from the bottom to the top of the bed. Overall the fluidized bed, in the absence of magnetite, was found to be a sufficient de-ashing process and further research on this technology could be very beneficial to the coal industry. / MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

Microplastics are particles that are < 5 mm in size and come from a wide range of sources. The global distribution in terrestrial and aquatic environments indicates they are likely to cause harm to living organisms. They are used in a variety of personal care products and kitchen scourers. To advance further studies, different approaches have been developed in recent years. In this research, a comparison of methods and analytical techniques were applied to characterise microplastics in two toothpastes and two facial scrubs. The analysis of microplastics was determined using light microscopy, laser diffraction, Fourier-transform infrared spectroscopy. This research reports for the first time, the application of Imaging flow cytometry to characterise microplastics, and was explored to characterise smaller sized particles in each product. The methods developed where validated by characterising particles abraded from kitchen scourers. Two market leading and three chain store brands of kitchen scourers were utilised for the characterisation of microplastics. The application of the different techniques indicated differences in the size, number and morphological characteristics of the particles analysed. The different approaches developed for particle extraction, and the analytical techniques had an apparent influence on the results produced. Currently, there are no universally accepted laboratory protocol and analytical techniques to characterise microplastics. However, this research can serve as a reference point to promote more studies on laboratory methods and analytical techniques to characterise microplastics, with the hope of understanding better these complex particles.

A sequential extraction method was used to determine which dominant sedimentary mineral phase was involved in phosphorus retention in the sediments of Lake Rotorua and to verify the importance of iron phases in the role as a phosphorus sink. The observed influence of the experimental conditions upon the extent of phosphate adsorption to various iron phases shows a considerable quantity of phosphorus is present in the reducible phase and in the residual mineral phase. The phosphorus associated with iron(III) oxide phases was released into solution under reducing conditions when ferric iron oxide/oxyhydroxides, including amorphous and poorly crystalline Fe(III) phases, were solubilized. The residual primary and secondary mineral phases remained stable in the sediments until they were exposed to extremely acidic media analogous to strongly reducing conditions. Manganese is not involved in phosphorus retention to the same extent as iron. Aluminium phases present were released from surface complexes with relative ease and also from mineral structures under the prevailing conditions. The results show a strong agreement between aluminium and phosphorus suggesting it is associated with various aluminium phases to some extent. The sediments of Lake Rotorua are rich in organic-bound P which is released when organic material is oxidized under conditions analogous to anaerobic degradation. The degradation of refractory organic material represents a significant source of phosphorus for incorporation into diagenetic minerals forming in oxic and anoxic layers of the sediment. Heavy liquid separation of the sediments concentrated the small quantities of dense minerals into a separate fraction and the presence of iron sulfides could be verified. Three density fractions obtained by this method separated the diatoms (d less than 2.6 g cm-3), the silicates (d greater than 2.6 less than 3.7 g cm-3) and the heavy minerals (d greater than 3.7 g cm-3) present in the sediment sample. In the heavy mineral phase spherulitic framboidal pyrite and rhombohedrial siderite were observed by scanning electron microscopy (SEM). Energy dispersive x-ray fluorescence (XRF) analysis of the framboidal pyrite detected significant fluorescence's for sulphur and iron. The elemental analysis of siderite characterised it as an iron-rich, non-sulfidic particle with no phosphorus fluorescence. Particles were also observed that had a variable morphology to the framboidal pyrite minerals but similar ratio of Fe to S in the XRF spectrum. It is likely they are other stable forms of iron sulfides or pyrites in various stages of diagenetic dissolution. Digestion of the three density fractions shows the heavy mineral phase is significantly enriched in sulfur and in iron confirming the presence of sulfides. The sulfide-forming trace metals are concentrating in the heavy mineral phase but a progressive enrichment of trace metals down core is not found in the results. Many of the trace elements show maximum concentrations in the Tarawera tephra. There is a good agreement between iron and phosphorus in both treatments that implies iron phases are the predominant phosphorus fixers in the sediments of Lake Rotorua. However the identity of the phosphorus sink could not be confirmed by SEM or XRF analysis of the heavy minerals. The most likely explanations for the observed concentrations of iron and phosphorus and enrichment in the heavy mineral fraction are the persistence of the highly insoluble crystalline iron oxyhydroxides (goethite) in reducing sediments or the formation of the reduced iron mineral vivianite. Considering the density of vivianite it would have being taken into the heavy fraction by default which would account for the enrichment demonstrated by the solution analysis.

It is estimated that 75 million tons of plastics waste is currently in the ocean and expects to increase in line with plastic consumption. Plastic items in natural or aquatic environments are fragmented into smaller pieces called microplastics. Microplastics can enter rivers and lakes through sewage water to end up in wetlands where they sediment. Due to lack of standard monitoring tools, microplastics in a Scanian context are rather uninvestigated. The current work therefore studies microplastics’ abundance in eleven wetlands along the Sege river and Kävlinge river. The aim is with available methods and tools to examine microplastics in sediment and examine if determined microplastics concentrations can relate to urbanization in the two catchments. The study also looked into wetlands position in relation to stream order to test if microplastics concentrations increase downstream. In the study, density separation has been used to extract microplastics from soil samples and analyzed using correlation. The result showed microplastics concentrations in all sampling sites. There was weak negative or no correlation with degree of urbanization nor a relation to higher concentration further downstream along Sege river and Kävlinge river. However, the study concludes that microplastics do appear in Scanian wetlands and not necessarily in the vicinity of human activity which complies with microplastics' ability to travel long distances. / Idag finns det cirka 75 miljoner ton plastavfall i haven, som förväntas öka i samband med ökad plastkonsumtion. Plastföremål i naturliga eller akvatiska miljöer fragmenteras till mindre bitar som kallas mikroplast. Mikroplast kan transporteras till åar och sjöar genom dagvatten eller avloppsvatten, och slutligen sedimenteras i våtmarker. Inom arbete med plastföroreningar i Skåne saknas övervakning av mikroplast koncentrationen. På grund av brist på standardverktyg för övervakning är mikroplaster i Skåne förhållandevis outforskat. Denna studie tittar därmed på mikroplast förekomsten i elva våtmarker längs Sege å och Kävlingeån. Syftet är att med tillgängliga metoder och verktyg undersöka mikroplast i sediment, om koncentrationer kan relatera till tätorter i närområdet. Studien tittar också på våtmarkernas position i förhållande till stream order för att testa om mikroplast koncentrationerna ökar nedströms. I studien har flotteringsmetoden använts för att extrahera mikroplaster från jordprover och dessa analyserades med korrelation. Resultatet visade på förekomst av mikroplaster i samtliga våtmarker. Dock kunde studien inte påvisa någon relation mellan urbanisering och högre koncentration av mikroplaster och resultaten visade också en svag negativ eller ingen korrelation mellan en ökad koncentration av mikroplaster och stream order. Vad studien kan dra för slutsatsen är att mikroplaster förekommer i skånska våtmarker som inte nödvändigtvis är i närheten av mänsklig aktivitet vilket överensstämmer med mikroplasters förmåga att färdas långa sträckor.

A better understanding of several mineral processing devices and applications was gained through studies conducted with mathematical analysis tools. Linear circuit analysis and population balance modeling were utilized to remedy inefficiencies found in a number of popular mineral processing water-based unit operations. Improvements were made in areas, including unit capacity and separation efficiency. One process-engineering tool, known as linear circuit analysis, identified an alternative coal spiral circuit configuration that offered improved performance while maintaining a reasonable circulating load. In light of this finding, a full-scale test circuit was installed and evaluated at an existing coal preparation facility. Data obtained from the plant tests indicate that the new spiral circuit can simultaneously reduce cut-point and improve separation efficiency. A mathematical population balance model has also been developed which accurately simulates a novel hindered-bed separator. This device utilizes a tangential feed presentation system to improve the performance of conventional teeter-bed separators. Investigations utilizing the mathematical model were carried out and have predicted solid feed rates of up to 71 tph/m² (6 tph/ft²) can be achieved at acceptable efficiencies. The model also predicts that the unfavorable impact of operating at low feed percent solids is severely reduced by the innovative feed presentation design. Tracer studies have verified that this system allows excess feed water to cross over the top of the separator without entering the separation chamber, thereby reducing turbulence. A hindered-bed separator population balance model was also developed whose results were utilized to improve the efficiencies encountered when using a teeter-bed separator as a mineral concentrator. It was found that by altering the apparent density of one of the feed components, the efficiency of the gravity separation could be greatly improved. These results led to the development of a new separator which segregates particles based on differences in mass after the selective attachment of air bubbles to the hydrophobic component of the feed stream. Proof-of-concept and in-plant testing indicate that significant improvements in separation efficiency can be achieved using this air-assisted teeter-bed system. The in-plant test data suggest that in some cases, recoveries of the plus 35 mesh plant feed material can be increased by more than 40% through the application of this new technology. / Ph. D.

Introduction: During cardiac surgery aided by cardiopulmonary bypass (CPB) the autotransfusion of pericardial suction blood (PSB) is regarded mandatory to limit allogeneic blood exposure. PSB is however proposed as a source of lipid microemboli and to contribute to brain damage. This thesis addresses the logistics of allogeneic blood transfusion during coronary artery bypass grafting (CABG), the embolic potential of reinfused PSB, and means to reduce PSB fat contamination, investigated both clinically and experimentally. Methods: Study I) Patients undergoing CABG surgery (n=2469) were included in a database study. The magnitude of surgical bleeding versus blood transfusion was analyzed to extract a subgroup of patients (n=982) in whom transfusions were independent from bleeding. Study II) PSB and venous-blood samples were collected from patients undergoing routine CABG (n=20). The in vitro capillary-flow properties of blood subcomponents and the effects of routine screen filtration were tested. PSB fat contamination was evaluated by imprint microscopy. Study III) Heat extracted liquid human fat or soya oil were mixed with mediastinal drain blood (n=20) and incubated in a temperature controlled column, to evaluate spontaneous density separation of fat. Study IV) The findings from study-III were applied to develop a fat-reducing system (FRS) using two stacked compartments. The FRS was experimentally tested (n=12), with similar methods as in study-III, and clinically evaluated (n=10). A single-chamber blood bag (n=10) served as reference. Results: Study I) A surgical bleeding of less than 400 mL showed no correlation to blood transfusion, although 64 of 982 patients still received allogeneic blood. The strongest predictors for this kind of transfusion were; female gender, weight ≤70 kg, CPB time ≥90 minutes, CPB temperature ≤32 ºC, and advanced age (P&lt;.001 - .038). Study II) The capillary-flow profile of PSB plasma was highly impaired compared to venous plasma (P&lt;.001). Conversely, blood-cell components showed no difference between PSB and venous blood. Routine screen filtration showed no ameliorating effect on capillary-flow resistance. Fat debris was detected on imprints in all PSB samples in contrast to venous plasma (P&lt;.05). Study III) After 10-min of incubation had 77% of added soya oil separated and found contained in the top 20% fraction of blood (P&lt;.001), aimed to be discarded. The density separation of human fat was less efficient compared to soya oil (P=.011). Fat also adsorbed to surface which was more pronounced at low temperature (P&lt;.001). The overall reduction of human fat was 70%. Study IV) PSB contained 1.5 mL fat suspended in 418 mL PSB. Of this fat was 24% surface-bound. Experimental analysis of the proposed FRS revealed an 83% fat-reduction which was clinically confirmed, suggesting 80% reduction (P=.001). The FRS also gave a small but significant erythrocyte-concentrating effect. Conclusions: Transfusion of allogeneic blood during CABG surgery appeared associated with an institutional, individual, and technical bias of an anticipated need and not only used to compensation for surgical bleeding. In part may this reflect a non-compliant CPB methodology and hemodilution. It was confirmed that PSB plasma contained fat, with a suggested embolic potential. Human fat was significantly reduced from mediastinal drain blood by spontaneous density separation and surface adsorption. The prototype FRS used for PSB incubation during CPB allowed an efficient fat reduction.

To provide an increased breadth in the knowledge of tephra dispersal, this pilot study examines a peat core from Lakselv in Finnmark County in northern Norway. Peat samples are exposed to burning, HCl, density separation and polarized light microscopy. One sample from a depth of 37.5-40 cm was analysed using an electron microprobe analyser (EMPA). At least two tephra horizons were identified, one at a depth of 12.5-17.5 cm and one at 37.5-40 cm. The lower horizon shows a chemical composition similar to eruptives from Jan Mayen and São Miguel, Azores while the origin of the upper horizon is unknown as no geochemical analysis was performed for that depth.

A cadeia da construção civil é uma grande causadora de impactos ambientais, pois além do alto consumo de recursos naturais gera também grandes quantidades de resíduos. Isto traz elevados custos à sociedade pela necessidade de remoção e destinação dos resíduos, normalmente depositados em aterros. A reciclagem tem sido uma alternativa para redução do volume de resíduos finais. Estudos utilizando agregados reciclados de Resíduos de Construção e Demolição (RCD) para a produção de concreto têm sido realizados por vários pesquisadores indicando viabilidade técnica da sua aplicação. No entanto, há dúvidas que dificultam a implementação do uso de resíduos reciclados dada a grande variabilidade das suas propriedades devido à variação de sua constituição que é muito influenciada pela origem dos mesmos. Assim, alguns tratamentos são propostos com a intenção de otimizar o desempenho do concreto produzido com estes agregados reciclados. A presente dissertação tem como objetivo avaliar a influência dessas variabilidades dos agregados de RCD reciclados nas propriedades do concreto estrutural. Esses agregados foram provenientes das cidades de Macaé e São Paulo, ambos submetidos aos mesmos tipos de tratamento: (a) britagem e (b) britagem e separação densitária (jigue), atendendo a mesma faixa granulométrica de -19+4,8 mm. No programa experimental, foi utilizada a metodologia de dosagem convencional para a avaliação do comportamento mecânico do concreto reciclado. Neste estudo, os agregados foram utilizados sem pré-saturação, o que possibilitou o preenchimento de parte dos poros dos agregados pela pasta de cimento. Tal procedimento contribuiu para uma menor diferença relativa de desempenho do concreto convencional em relação ao produzido com agregados reciclados, principalmente para os concretos com maior relação água/cimento. Foram analisados os resultados de resistência à compressão, resistência à tração por compressão diametral, módulo de elasticidade, absorção de água, índice Binder Intensity e ensaio de ultra-som. Comprovou-se que a porosidade dos agregados é o fator principal de influência no comportamento do concreto. Já a origem dos agregados foi um fator secundário dado que os mesmos apresentavam diferentes porosidades em função da cidade onde foram obtidos. A separação densitária possibilitou a aproximação do comportamento dos agregados de diferentes origens por aproximar a porosidade dos mesmos. / The civil construction industry is a great producer of environment impacts. It also generates great amounts of residues, further the high consumption of natural resources. This fact brings high costs to society due to the need of residues removing and disposal, which typically occurs in landfills. Recycling has been an alternative to reduce the volume of residues. Studies using recycled aggregates from Construction and Demolition Waste (CDW) to produce concrete have been carried out by several researchers, indicating that is technically feasible in terms of application. However, there are questions that turns difficult the implementation of the use of recycled residues, due to the great variability of their properties as a result of the variation of their constitution, which is strongly influenced by their origin. Thus, a few treatments are proposed, aiming at optimizing the performance of these recycled aggregates to produce concrete. The present work aims at assessing the influence of the recycled CDW aggregates on the properties of structural concrete. These aggregates originated from the cities of Macaé and São Paulo, and both were submitted to the same type of treatment: (a) crushing and (b) crushing and density separation (jig), complying with the same granulometric range of -19+4.8 mm. The conventional mix design methodology was used in the experimental program to assess the concrete behavior and the influence of the recycled material. The aggregates were used in this study without being pre-saturated, which allowed filling up part the pores of the aggregates with cement paste. Such procedure contributed for a smaller relative difference on the performance of the conventional concrete and that one produced with recycled aggregates, especially the concrete with a higher water/cement ratio. The compressive strength, split tensile strength, elastic modulus, water absorption, Binder Intensity index and measuring of ultrasonic testing were analyzed. The porosity of the aggregate was proved to be a prevalent factor influencing the behavior of the concrete. The origin of the aggregates was a secondary factor because they had different porosities according to the city where they were obtained. The density separation allowed the reduction of the difference in behavior between the concretes produced with aggregates from different origins by approaching their porosity.