Flertalet stora produktionsbolag inom förädlingsprocessen av råvaror har som mål att så mycket som möjligt av materialet i produktiosprocessen kommer till användning. Detta kan ske genom att effektivisera produktionen, men även genom att de restprodukter som uppkommer återanvänds tillbaka i processen alternativt komma till användning i nya områden, hela tiden i åtanke att bibehålla samma kvalitet på ursprungsprodukten. Detta arbete har valt att fokusera på restprodukter från de två områdena skogs- och pappersindustrin samt gruvoch stålindustrin. I gruv- och stålindustrin kommer stora kvantiteter av restprodukter upp under produktionsprocesserna i form av bland annat sidoberg, anrikningssand och slagger. Ofta gör de stora mängderna restprodukter att det blir logistiska problem när nya områden för produkterna ska analyseras, även att det finns svårigheter att få lönsamhet i de nya områdena. Ur perspektivet skogsindustrin kommer detta arbete att fokusera på den del av branschen som producerar för pappersindustrin. I arbetet har undersökningar gjorts på vilka produkter respektive industrier i nuläget producerar genom sina restprodukter och avfall, samt vilka i framtiden som har potential att produceras. Detta har gjorts genom att intervjua centrala personer för området på företag som är stora aktörer inom respektive industri samt litteraturstudier inom dessa områden. Det som erhölls genom arbetet var att skogs- och pappersindustrin redan i dagsläget har ett välfungerande system och får generellt lite restprodukter som är svåra att komma till ny använding alternativt läggs på deponi. De små mängder som uppkommer bedrivs det samtidigt utveckling på för att även de ska kunna tas tillvara på, exempel på detta är biodrivmedel där företag som SCA har planer att utvidga sin verksamhet. Gruv- och stålindustrin hade även de utveckling för att minska och förädla de restprodukter som uppkommer, bland annat försöker LKAB utveckla gödsel ur den fosfor som finns i anrikningssand och sidoberg, samt att SSAB exempelvis kan använda sina slagger i asfalt och cementproduktionen / Several of the big production companies aim to use as much of their products as possible in the manufacturing of raw materials. This can be done by streamlining or reusing the residual products from the production process for new products, while still ensuring the quality of the product. This article focuses on the products from the wood and paper industry and the mining and steel industry. In the mining and steel industry, large quantities of residual products come up during the production processes in the form of, for example, country rock, enrichment sand and slag. Often, the large quantities of residual products cause logistical problems when analyzing new areas for the products, also that there are difficulties in obtaining profitability in the new areas. In the perspective of wood industry will this work focus on the areas which produces for the paper industry.In this area, studies have been done on which products each respective industry produces today with their residuals and waste. The study relied on interviews with key people in every area of each big company. They found that the wood and paper industry already has a system that works well and generally has only a few residuals that are hard to get rid of in landfills, and the small amounts of residuals that do exist are being developed so that they can also be utilized (biofuel companies like SCA are expanding their operations to do this). The mining and steel industry has also made progress toward minimizing and refining their residuals. For example, LKAB is trying to develop fertilizers from the phosphorus found in tailings and country rock, and SSAB is using its slag in asphalt and cement production.

[pt] O gerenciamento e estocagem dos residuos de mineração apresentam desafios constantes devido às crescentes demandas do setor, dessa forma, o aperfeiçoamento dos processos de gestão dos rejeitos e a otimização da capacidade de estocagem dos reservatórios são fundamentais para a viabilidade de um empreendimento de exploração de recursos minerais. O presente trabalho apresenta a metodologia utilizada para avaliação do processo de ressecamento de rejeito da lavagem de bauxita da Mineração Rio do Norte, sendo proposta a execução de dois reservatórios experimentais, em escala piloto, possibilitando o monitoramento do comportamento de ressecamento do rejeito in loco e a cxecução de ensaios em laboratório. A proposta do estudo é avaliar o comportamento do rejeito quando disposto em diferentes espessuras de camadas, incluindo aspectos de condições climáticas e tempo de secagem. O objetivo foi calibrar o modelo de enchimento e otimizar a área dos reservatórios contidos no sistema de contenção de rejeitos da MRN, aperfeiçoando a previsibilidade do final da vida útil das estruturas e maior assertividade do balanço de massas no longo prazo. Os estudos de campo e laboratório consistiram na disposição e monitoramento de camadas com 0,50 m e 0,80 m. Dessa forma, foi possível a avaliacão dos teores de sólidos ao final do periodo de secagem das camadas dispostas, avaliar as curvas de enchimento e recalque do rejeito, medir os ângulos de repouso no momento da disposição e após periodo de ressecamento e analisar a morfologia e desenvolvimento das trincas de contração. Com base nos resultados laboratoriais e de campo obtidos nesse trabalho, conclui-se que o comportamento do processo de ressecamento do rejeito é influenciado por uma série de fatores, podendo citar a permeabilidade do fiundo dos reservatórios as condições climáticas (incidência pluviométrica e taxa de evaporação) como os mais impactantes ao processo. No trabalho não foi observado uma grande diferença do comportamento de rejeito para as camadas de 0,50 cm e 0.80 cm. / [en] The management and storage of mining waste present constant challenges due tothe increasing demands of the sector. Therefore, improving waste managementprocesses and optimizing the storage capacity of reservoirs are fundamental to theviability of a mineral resource exploration project. This study presents themethodology used to evaluate the desiccation process of washed bauxite tailings atMineração Rio do Norte (MRN). The implementation of two experimentalreservoirs at a pilot scale is proposed, allowing on-site monitoring and laboratorytests for the tailings desiccation behavior. The objective of the study is to assess thetailings behavior when disposed in different layer thicknesses, considering aspectssuch as weather conditions and drying time. The aim was to calibrate the fillingmodel and optimize the area of the reservoirs within MRN s tailings storage facility,thus improving the predictability of the structures end-of-life and enhancing theaccuracy of long-term mass balance. Field and laboratory studies involved thedeposition and monitoring of layers with thicknesses of 0.50 m and 0.80 m. Thisenabled the evaluation of the solids content at the end of the drying period.assessment of filling and settlement curves, measurement of the angle of repose atthe time of deposition and after the drying period, and analysis of crack morphologyand development. Based on the field and laboratory results obtained in this study,it can be concluded that the behavior of the tailings desiccation process is influencedby several factors. The permeability of the reservoir bottom and weather conditions(rainfall and evaporation rate) are identified as the most impactful to the process.No significant difference in the behavior of the waste was observed between the 0.50 cm and 0.80 cm layers.

This study focuses on the particle tracking of reactive transport with groundwater in a tailing dam, specifically at the Malmberget mine in Northern Sweden. Understanding the geochemical behaviour of major elements and trace metals in the subsurface environment with a focus on the tailings sand and moraine layers. The mobility and interactions of pollutants through a period of time were simulated using advanced modelling programmes such as FASTREACT, PHREEQC, and MIKE SHE.  The results reveal that major elements such as calcium (Ca), sodium (Na), and sulphate (SO₄) remain stable, indicating minimal geochemical reactions within the tailings sand layer. A decline in pH, primarily due to pyrite oxidation, highlights key geochemical changes. Trace metals, including cobalt (Co), copper (Cu), nickel (Ni), strontium (Sr), uranium (U), and zinc (Zn), maintain constant concentrations, attributed to the uniformity of processed water both as the infiltrating and existing solution in the tailings sand. In the moraine layer, the incoming water supersedes the existing water, achieving the concentration of the incoming water after subsurface mixing. Consequently, it is essential to assess the concentration reaching the lake to determine safety levels.  In the closure scenario, rainwater replaces the processed water as the infiltrating solution, resulting in gradual dilution and displacement of the original process water chemistry within the tailings sand. This natural attenuation process enhances subsurface water quality by reducing contaminant levels initially introduced by mining operations. In moraine, the incoming concentration from the sand supersedes that of the existing groundwater, leading to an increase in the concentration of the moraine layer. The study also examines travel times, indicating rapid particle movement through the sand layer and more variable travel times through the moraine layer, reflecting geological heterogeneities.  The study emphasises the importance to combine geochemical and hydrological models when evaluating tailings dam effects on the ecosystem in order to decrease the negative consequences of mining operations. The study recommends that future work should add dynamic situations and precise geochemical interactions to improve the knowledge of contaminant behaviour, while accepting limitations such as the assumption of steady-state flow and simplified geochemical processes.  Overall, this study contributes to the development of sustainable mining practices and the protection of surrounding water resources by providing a comprehensive analysis of a simple subsurface geochemical and hydrological processes and their impacts. / Denna studie fokuserar på partikelspårning av reaktiv transport med grundvatten i en avfallsdamm, specifikt vid Malmbergets gruva i norra Sverige. Förstå det geokemiska beteendet hos viktiga grundämnen och spårmetaller i den underjordiska miljön med fokus på avfallssand och moränlager. Föroreningarnas rörlighet och interaktioner under en tidsperiod simulerades med hjälp av avancerade modelleringsprogram som FASTREACT, PHREEQC och MIKE SHE.  Resultaten visar att huvudämnen som kalcium (Ca), natrium (Na) och sulfat (SO4) förblir stabila, vilket indikerar minimala geokemiska reaktioner i avfallssandskiktet. En minskning av pH, främst på grund av pyritoxidation, belyser viktiga geokemiska förändringar. Spårmetaller, inklusive kobolt (Co), koppar (Cu), nickel (Ni), strontium (Sr), uran (U) och zink (Zn), upprätthåller konstanta koncentrationer, vilket tillskrivs enhetligheten hos bearbetat vatten både som infiltrerande och befintlig lösning i avfallssanden. I moränskiktet ersätter det inkommande vattnet det befintliga vattnet och uppnår koncentrationen av det inkommande vattnet efter blandning under ytan. Följaktligen är det viktigt att bedöma koncentrationen som når sjön för att fastställa säkerhetsnivåer.  I stängningsscenariot ersätter regnvatten det processade vattnet som den infiltrerande lösningen, vilket resulterar i gradvis utspädning och förskjutning av den ursprungliga processvattenkemin i avfallssanden. Denna naturliga dämpningsprocess förbättrar vattenkvaliteten under ytan genom att minska föroreningsnivåerna som initialt introducerades av gruvdrift. I morän ersätter den inkommande koncentrationen från sanden den i det befintliga grundvattnet, vilket leder till en ökning av koncentrationen av moränlagret. Studien undersöker också restider, vilket indikerar snabb partikelrörelse genom sandlagret och mer varierande restider genom moränlagret, vilket återspeglar geologiska heterogeniteter.  Studien understryker vikten av att kombinera geokemiska och hydrologiska modeller vid utvärdering av avfallsdammseffekter på ekosystemet för att minska de negativa konsekvenserna av gruvdrift. Studien rekommenderar att framtida arbete bör lägga till dynamiska situationer och exakta geokemiska interaktioner för att förbättra kunskapen om föroreningars beteende, samtidigt som begränsningar som antagandet om steady-state flöde och förenklade geokemiska processer accepteras.  Sammantaget bidrar denna studie till utvecklingen av hållbara gruvdriftsmetoder och skyddet av omgivande vattenresurser genom att tillhandahålla en omfattande analys av en enkel underjordisk geokemiska och hydrologiska processer och deras effekter.

Mon sujet de thèse intègre l’un des projets globaux de l’UMR UFC/CNRS 6249 Chrono-Environnement intitule « stratégies de phytoremédiation basées sur l’utilisation d’arbres et de microorganismes associés », qui s’appuie, entre autre, sur 2 projets de recherche :• le projet PROLIPHYT (programme Eco-Industrie, 2013-2018, ADEME) intitulé « PROduction de LIgneux PHYtoremédiants»,• le projet PHYTOCHEM (ANR CD2i, 2013-2018) intitulé « Développement de procédés chimiques éco-innovants pour valoriser les biomasses issues des phytotechnologies ».Les objectifs généraux sont d’améliorer le potentiel de phytoremédiation d’un panel d’espèces ligneuses et de développer le potentiel microbien pour une phytoremédiation aidée sur sol contaminé. En plus de limiter l’impact des polluants, cette stratégie vise à promouvoir la production de biomasse sur sols délaissés et non exploitables par l’agriculture, tout en assurant la biodiversité nécessaire à la restauration d’un écosystème anthropogénique.Mon travail de thèse est financé au travers un contrat doctoral ministériel handicap (dyslexie). Il s’appuie sur la réhabilitation de deux zones de stockage de sédiments industriels, utilisés jusque dans les années 2000. Ces deux sites expérimentaux (site INOVYN de St Symphorien-sur-Saône en Côte d’Or, site CRISTAL de l’Ochsenfeld en Alsace) présentent des caractéristiques physico-chimiques très particulières qui en font des lieux d’étude privilégiés. Le premier est une ancienne lagune de décantation dont les sédiments enrichis en Hg, Ba et As proviennent du traitement des eaux usées issues du procédé d’électrolyse à Hg de l’entreprise SOLVAY. Le second est une lagune constituée d’un remblai dans lequel ont été stockés depuis les années 1930, les résidus d’extraction du dioxyde de titane de l’Usine CRISTAL de Thann. A l’inverse du premier site expérimental, on observe une flore peu abondante qui se traduit par un développement hétérogène d’une espèce ligneuse principale, le bouleau.La recolonisation naturelle et spontanée de végétaux, plus particulièrement d’espèces ligneuses sur les deux sites est sans doute le résultat d’étroites collaborations avec des microorganismes telluriques situés aux abords de leur système racinaire. Nous avons ainsi choisi de travailler sur 3 espèces pionnières qui se sont naturellement réimplantées sur les deux sites d’études : le saule et le peuplier pour la friche industrielle de Tavaux et le bouleau pour l’unité de traitement des effluents du site de l’Ochsenfeld. / AbstractMy thesis subject includes one of the global projects of the UMR UFC/CNRS 6249 Chrono-Environnement entitled "phytoremediation strategies based on the use of trees and associated microorganisms", which is based, among other things, on 2 research projects:• the PROLIPHYT project (Eco-Industry programme, 2013-2018, ADEME) entitled "Production of woody phytoremediants",• the PHYTOCHEM project (ANR CD2i, 2013-2018) entitled "Development of eco-innovative chemical processes to exploit biomasses from phytotechnologies".The general objectives are to improve the phytoremediation potential of a panel of woody species and to develop the microbial potential for assisted phytoremediation on contaminated soil. In addition to limiting the impact of pollutants, this strategy aims to promote the production of biomass on land abandoned and not exploitable by agriculture, while ensuring the biodiversity needed to restore an anthropogenic ecosystem.My thesis work is financed through a ministerial doctoral contract for disability (dyslexia). It is based on the rehabilitation of two industrial sediment storage areas, used until the 2000s. These two experimental sites (INOVYN site of Saint-Symphorien-sur-Saône in Côte-d'Or, CRISTAL site of Ochsenfeld in Alsace) present very particular physico-chemical characteristics which make them privileged places of study. The first is a former settling lagoon whose sediments enriched in Hg, Ba and As come from the treatment of wastewater from SOLVAY's Hg electrolysis process. The second is a lagoon consisting of a backfill in which the titanium dioxide extraction residues from the CRISTAL Thann Plant have been stored since the 1930s. In contrast to the first experimental site, there is a low abundance of flora which results in heterogeneous development of a main woody species, the birch.The natural and spontaneous recolonisation of plants, more particularly woody species on both sites, is undoubtedly the result of close collaboration with telluric microorganisms located near their root systems. We have thus chosen to work on 3 pioneer species that have naturally relocated to the two study sites: willow and poplar for the industrial wasteland of Tavaux and birch for the effluent treatment unit at the Ochsenfeld site.

The commercial mining of asbestos occurred in four Provinces of South Africa (Northern Cape, North West, Limpopo and Mpumalanga). It was initiated in the late 1800's and lasted for over a hundred years into the beginning of this century. As a producer of amphibole asbestos, South Africa far outpaced every other country being responsible for 97% of global production. The last crocidolite mine closed in 1996 and chrysotile in 2002. Anecdotal information concerning environmental contamination as a result of the former mining activities and the improper disposal of mine waste tailings has been reported by a variety of authors. Few comprehensive or systematic surveys have been conducted to date to document this issue and very little quantifiable research has been completed on the communities located in close proximity to the former mine sites to determine the extent of contamination. In 2004-2006 communities were surveyed within the Northern Cape and North West Provinces to determine the extent and severity of environmental contamination. This research developed and applied a methodology to select those communities suspected of environmental contamination, a targeted survey methodology, and a protocol for rapid sample laboratory analysis. A total of 41 communities were initially predicted by the model to be suspected for environmental asbestos contamination. Based on the inclusion of local knowledge, a final 36 communities were selected for a screening-level field assessment, 34 of which were found to contain environmental asbestos contamination at rates ranging from 20 to 100% of the surveyed locations. A total of 1 843 samples of soil and building material were collected in the screening level assessment. One community (Ga-Mopedi) was selected as being representative of the total cohort and a more detailed house to house survey was completed. A total of 1 486 samples were collected during the detailed survey. Results of the detailed survey revealed 26.2% of the homes were contaminated with asbestos containing soil and/or building material. A theoretical quantitative cumulative exposure assessment was developed to estimate the disease burden within the study area population of 126,130 individuals within the surveyed communities resulting in a predicted range of 25-52.4 excess deaths per year from lung cancer and mesothelioma due solely to environmental exposures to asbestos pollution.

Please read the abstract in the section 00front of this document / Thesis (PhD(Geotechnical))--University of Pretoria, 2008. / Civil Engineering / PhD / unrestricted

MENVSC / Department of Ecology and Resource Management / Historically, mining activities have generated vast quantities of abandoned tailings dumps in several regions of South Africa and throughout the world. The management and disposal of huge volumes of tailings dumps has constituted a major challenge to the environment. The current study aims to establish the physicochemical properties and mineralogical characterization of the old copper tailings dump in Musina, to reveal the mobility patterns and attenuation dynamics of potentially toxic or heavy metal species as a function of depth, with a view of assessing their potential environmental impact with respect to surface and ground water systems. This information is crucial in the beneficial utilization of copper tailings in the development of sustainable construction materials as part of reuse approach management system. About twelve tailings samples were collected into polyethylene plastic bags from three established tailings profiles drilled by a hand auger. The collected tailings samples were characterized using standard analytical procedures i.e., X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS). The transfer of potentially toxic or heavy metal species from tailings to water was evaluated using the standardized batch leaching test (EN 12457) and speciation-equilibrium calculations on the aqueous extracts performed by MINTEQA2. The leachate concentration of cations in the collected tailings samples was determined by inductively coupled mass spectrometry (ICP-MS) and the leachate concentration of anions was determined by ion chromatography (IC). A modified sequential extraction scheme was applied on the selected tailings samples of the drilled tailings profiles to further understand the mode of occurrence, the geochemical partitioning and distribution, real mobility, and environmental bioavailability of potentially toxic or heavy metal species in the tailings and tailings-soil interface. The extracted fractions or phases from sequential scheme were as follows: (F1) water-soluble fraction, (F2) exchangeable fraction, (F3) carbonate fraction, (F4) iron and manganese hydroxide associated fraction, (F5) organic matter and secondary sulphide associated fraction, (F6) primary sulphide bound fraction, and (F7) residual or silicate fraction. The results obtained from the seven steps sequential extraction scheme were validated by the determination vi of percentage recoveries from pseudo-total digestion or total metal content of the original sample. The distribution of major elements and potentially toxic or heavy metal species in different leachate fractions obtained after each step of sequential extraction of the selected tailings samples was determined by inductively coupled plasma mass spectrometry (ICP-MS). The appraised data was used to reveal the impact of atmospheric oxygen and infiltrating rain-water on the chemistry of copper tailings dump by depth profiles. Macroscopic properties revealed that the abandoned Musina copper tailings are fine to medium coarse grained, and range in color from light/dark gray at the upper or shallow depth of the tailings, to dark reddish-brown at the deeper zone where the tailings are mixed with the underlying soil or soil-interface. The drilled respective tailings profiles were uniform and slightly varied in both mineralogical and bulk chemical compositions with tailings depth. Mineralogical analysis showed the following order of mineralogical composition within the respective tailings profiles: quartz> epidote> chlorite> muscovite> calcite> hematite. Chalcopyrite was the only sulphide mineral observed by optical microscopy, although not identified or quantified by XRD and SEM-EDS analysis. The observed discrete chalcopyrite grains were attributed to the primary mined ore (i.e., chalcopyrite, chalcocite and bornite) during past copper mining activities in Musina. The tailings profiles were characterized by a medium alkaline pH (7.97-8.37) that corresponds very well with the tailings leachates or pore-water pH (8.36-8.46). This pH was constant and slightly varied with tailings depth in the respective tailings profiles. The high abundance of alumino-silicate minerals and traces of carbonates as calcite coupled with low sulphide mineral content, suggested a high neutralization capacity of the tailings which was in common agreement with an alkaline nature of the copper tailings dump. The chemical composition of major elements within the respective tailings profiles followed the order: Si>Al>Fe>Ca>Mg>K>Na, and corresponds very well with the mineralogical composition of the tailings, whereby alumino-silicates were the most abundant minerals in the tailings samples. Nevertheless, the solid-phase concentration of metals decreases with increasing tailings depth as Cu>Sr>Zr>Ni>Zn and was incongruent with the mineralogical composition within the respective tailings profiles. The main secondary minerals were calcite and hematite, and their proportion increased with increasing tailings vii depth. In addition, hematite formed coatings on the rims and corners of chlorite as observed from optical microscopy, and retained relatively high amounts of potentially toxic or heavy metals (up to 862 ppm of Cu, up to 36 ppm of Ni, and up to 25 ppm of Zn) at the upper and shallow depth of the respective tailings profiles, where bulk density was high and low porosity. Based on batch leaching tests, the amounts of potentially toxic or heavy metal species released into solution were low (0.27-0.34 μg/L Pb, 0.54-0.72 μg/L Ni, 0.88-1.80 μg/L Zn, and 20.21-47.9 μg/L Cu) and decreases with increasing tailings depth, indicating that, presently, the tailings have a minor impact on heavy metals load transported to the receiving surface and groundwater systems. The low concentration of potentially toxic or heavy metal species in solution is primarily due to their retention by secondary Fe oxide phases (i.e., hematite) and the prevailing medium alkaline pH condition of the tailings leachate or pore-water. The observations are consistent with MINTEQA2 speciation calculations, which predicted the precipitation of secondary phase cuprite (Cu2O) as the main solubility-controlling mineral phase for Cu, Zn, and Ni. Primary factors influencing aqueous chemistry at the site are neutralization and dissolution reactions as a function of pH, precipitation, and sorption into hydrous oxides (hematite and cuprite). Based on sequential extraction results, the leachable concentration of potentially toxic or heavy metal species in the water-soluble, exchangeable and carbonate fractions of the respective tailings profiles was relatively low, except for Cu and Mn. For instance, the leachable concentration of Cu and Mn reached 10.84 mg/kg and 321.7 mg/kg at the tailings-soil interface (3 m) in tailings profile C, respectively. The low concentration of potentially toxic or heavy metal species (Cr, Co, Ni, Zn, Cd, and Pb) in these fractions could be due to the low solubility of minerals bearing these trace elements caused by variations in pore-water pH in the respective tailings profiles. The high concentration of Cu and Mn in these fractions suggests their high mobility and therefore most available for uptake in the environment. Except for Cu>Mn>Cr, the contents of potentially toxic or heavy metal species in the Fe and Mn oxides and organic matter or sulphides bound fractions was low, due to the low viii quantity of these fractions in the tailings, despite their high affinity and sorption capacity for potentially toxic or heavy metal species. Likewise, the residual fraction of the respective tailings profiles contained the highest proportion of potentially toxic or heavy metal species. Although the highest potentially toxic or heavy metal species content was in fractions with limited mobility, care must be taken since any geochemical change or shift in the tailings pH or acidic conditions may cause them to be displaced to more mobile fractions, thereby increasing their mobility and environmental bioavailability. Therefore, physicochemical properties of the tailings including pH and mineralogical composition of the tailings samples were the main substrate controlling the geochemical partitioning and distribution, potential mobility, and environmental bioavailability of potentially toxic or heavy metal species by tailings depth. The knowledge of mobility and eco-toxicological significance of tailings is needed when considering tailings dump disposal or reuse in the environment. The addition of copper tailings at 3 and 28 days successfully improved the compressive strength of cement mortar mixtures incorporating tailings at C5 (5%) and C10 (10%) respectively, although with small margin relative to the control mixture (C0). The maximum strength was 31.15 Mpa attained after 28 curing days, and slightly varied when compared with other compressive strength on copper blended cement mortars mixtures in other countries, used for the development of sustainable construction materials. The chemical composition, physical properties and improved compressive strength on cement mortars mixtures incorporating copper tailings, implies that copper tailings are suitable for the development of sustainable construction materials, thereby ensuring job creation, availability of land for development usage, and the reduction of environmental pollution induced by the abandoned copper tailings dumps.

MENVSC / Department of Ecology and Resource Management / Mine tailings (MT) have been a global problem due to the environmental impacts the waste generates such as air, soil and water pollution. The detrimental impacts include a global problem such as acid mine drainage (AMD) which has been difficult to cleanup. Several studies have been conducted to find alternative measures in reducing or mitigating impacts such as AMD and air pollution. Several studies have revealed how alumino-silicate mineral waste can be used as raw material to produce construction materials. This study aimed at evaluating the potential of synthesizing a geopolymer material from Musina copper mine tailings. Tailings were characterized for their physicochemical and mineralogical compositions using standard laboratory techniques in order to evaluate suitability in geopolymerization. First section of the results presented physicochemical and mineralogical characterization of the Musina copper tailings together with the bioavailability of the chemical species. It was observed that the tailings are mainly composed of SiO2 and Al2O3 as the major oxides indicating that they are aluminosilicate material. Mineralogical analysis revealed dominance of quartz, epidote and chlorite as the major minerals. The bioavailability assessment showed that largely Cu and Ca are bioavailable and highly soluble in an aqueous solution while Al, Mg, Ni, Co, Cr and Fe have a high proportion in non-labile phase. Second section presented the preliminary results wherein the potential application of Musina copper tailings in geopolymerization was evaluated. The results showed that Musina copper tailings can be used to synthesize a geopolymer material. However, it was recommended that several parameters influencing geopolymerization need to be evaluated. The third section presented the evaluation of optimum parameters that influence the geopolymerization process, which include type of alkali activators, alkali activator concentration, curing temperature, liquid-solid (L/S) ratio and curing regime. It was observed that a mixture of NaOH:Na2SiO3.5H20 at a ratio of 70:30 yields a better geopolymer material. The concentration of 10 M NaOH:Na2SiO3.5H20 at a ratio of 70:30 was observed to be the best that yielded the UCS that is acceptable according to SANS1215 standards. When evaluating curing regime, it was found that the material cured using greenhouse has lower UCS as compared to the material cured using oven. The v effect of temperature showed that the UCS decreases with increasing curing temperature. An admixture of river sand and cement was introduced which resulted in a high UCS of 21.16 MPa when using an admixture of cement. The mineralogical composition of the geopolymer bricks showed formation of secondary minerals such as phlogopite, fluorapatite, diopside and actinolite. Batch leaching conducted on the geopolymer bricks detected high leaching of Na from the bricks. Based on the findings of the study of the raw MT potential to produce geopolymer bricks, it was concluded that the material can be used to produce bricks that are within the SANS 1215 requirements. The study further recommended that the study a focus on using cylindrical moulds, other alkali activators and a mechanical mixer. It was also recommended that the greenhouse be restructured to contain heat within the greenhouse during the evening so as to allow constant temperature within / NRF

Surface water pollution is prevalent in numerous areas of central Roodepoort mainly due to gold mining activities. The surface water quality for the Bosmontspruit, Russell’s Stream and the New Canada Dam was assessed from October 2010 to March 2011. Physical, chemical and biological characteristics of the water were determined for 8 monitoring points and the results obtained were compared with the In-stream water quality guidelines for the Klip River catchment and the South African Water Quality Guidelines. A trend noticed throughout the sampling period was the non-compliance in the levels of total dissolved solids (TDS) and dissolved oxygen. The results indicated that concentrations of iron, aluminium, nickel, manganese and potassium were above the limit across the Bosmontspruit and Russell’s stream. There was also significant evidence of excessive faecal coliform and ammonium pollution in the Bosmontspruit. During the monitoring period it was noted that water from these streams were utilised for crop irrigation, bathing, livestock and human consumption and may pose a health hazard due to poor water quality. / Environmental Sciences / M.Sc. (Environmental Science)

Msc. / This study focuses on the functional evaluation of a gold Tailings Storage Facility (TSF), the Fleurhof TSF (designated slimes dam 2L3), which is representative of gold slimes (tailings) dams in the Witwatersrand. The aim is to evaluate the rehabilitation status (in terms of species composition and landscape function) of TSF surfaces that were planted ~20 to ~40 years ago using the most common rehabilitation practice, namely pasture grassing. Pasture grassing aims to obtain rapid dust control. Mine closure was not considered at the time, and the vegetation was hence not designed with ecological processes or long-term objectives in mind. However, over time, grassing practices became routine in the TSF vegetation industry, and the contribution that they have made towards surface rehabilitation needs to be assessed against the current site closure objectives. On the selected site, evaluations of vegetation cover, species composition, and substrate physical and chemical properties were conducted in 1975 (Thatcher, 1979). The aim of the current mid-summer study in 2009 was addressed by assessing the same parameters of vegetation cover, species composition, and soil physical and chemical properties, and comparing these to the results of the previous assessment in 1975. Landscape Function Analysis (LFA – an index-based method of evaluating the retention of resources by surfaces and soil condition), was applied to determine the landscape function (stability, infiltration and nutrient cycling that are derived from the eleven soil surface assessment indicators), and compared with the landscape function of natural analogues in the same locality. Landscape organisation (also an indicator of LFA) was used to investigate the contribution of vegetation overall, and of discrete plant functional groups to landscape functionality. A total of 35 plant species were observed in the quadrats (56 species on the TSF overall), with 51% of species overall being alien. Perennial vegetation and cryptogam covers contributed the most to stabilising the TSF slopes and flat (top) surfaces. The percentage of vegetation basal cover on the TSF (30% – 70%) was lower than for analogue grassland sites on a nearby hill (80% – 100%). Lower basal vegetation cover on the TSF than on the analogue site, were associated with lower LFA indices of stability on all TSF slope aspects (P = 8.19 x 10-13 for all aspects), iii lower nutrient cycling for the northern and southern TSF slopes (south aspect P = 4.20 x 10-6; top aspect P = 0.03), and lower infiltration on the southern slope of the TSF (P = 2.68 x 10-6). However, a higher infiltration on the northern TSF aspect (P = 0.02) than on the analogue site, was attained. Perennial tussock grass patch types (which included perennial forbs) made the largest contribution to the soil surface assessment (SSA) indicators on the TSF and analogue sites, and therefore to the LFA indices that were derived from these SSA indicators. The contribution of woody patches to function was not evaluated.