Gelfill (GF) is made of tailings, water, binder and chemical additives (Fillset, sodium silicate gel). The components of GF are combined and mixed on the surface and transported (by gravity and/or pumping) to the underground mine workings, where the GF can be used for both underground mine support and tailings storage. Thermal (T), hydraulic (H), and mechanical (M) properties are important performance criteria of GF. The understanding of these engineering properties and their evolution with time are still limited due to the fact that GF is a new cemented backfill material. In this thesis, the evolution of the thermal, hydraulic, mechanical, and microstructural properties of small GF samples are determined. Various binder contents of Portland cement type I (PCI) are used. The GF is cured for 3, 7, 28, 90, and 120 days. It is found that the thermal, hydraulic and mechanical properties are time-dependent or affected by the degree of binder hydration index. Furthermore, a relationship is found between the compressive strength and the saturated hydraulic conductivity of the GF samples. The unsaturated hydraulic properties of GF samples have also been investigated. The outcomes show that unsaturated hydraulic conductivity is influenced by the degree of binder hydration index and binder content, especially at low suction ranges. Simple functions are proposed to predict the evolution of air-entry values (AEVs), residual water content, and fitting parameters from the van Genuchten model with the degree of hydration index (α). Furthermore, two columns are built to simulate the coupled thermo-hydro-mechanical (THM) behaviour of GF under drained and undrained conditions. The obtained results from the GF columns are compared with the small samples. It is observed that the mechanical properties, hydraulic properties (suction and water content), and temperature development are strongly coupled. The magnitude of these THM coupling factors is affected by the size of the GF. The findings also show that the mechanical, hydraulic and thermal properties of the GF columns are different from samples cured in plastic moulds.

The Lower Athabasca Water Management Framework limits water extractions by the oil sands industry near Fort McMurray, Alberta. To increase water-use efficiency and minimise the cost of water restrictions, several policy and technology options were developed and assessed using quantitative and qualitative methods. Selected options were the policies of water trade and pricing with refund, and the technologies of storage, and consolidated tailings and increased recycling. Options were designed based on year 2020 demand and assessed relative to prior allocation. Using linear programming and static optimisation, it is shown that an off-stream storage sized to avoid water restrictions, in combination with efficient water allocation (e.g. water trade), is most cost-effective, although provides no ongoing incentive to increase water-use efficiency. Only the policy options provide equal incentives across firms to increase efficiency. To achieve both objectives of increased water-use efficiency and minimised costs, a combined policy and technology approach is recommended. / Agricultural and Resource Economics

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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)

Gelfill (GF) is made of tailings, water, binder and chemical additives (Fillset, sodium silicate gel). The components of GF are combined and mixed on the surface and transported (by gravity and/or pumping) to the underground mine workings, where the GF can be used for both underground mine support and tailings storage. Thermal (T), hydraulic (H), and mechanical (M) properties are important performance criteria of GF. The understanding of these engineering properties and their evolution with time are still limited due to the fact that GF is a new cemented backfill material. In this thesis, the evolution of the thermal, hydraulic, mechanical, and microstructural properties of small GF samples are determined. Various binder contents of Portland cement type I (PCI) are used. The GF is cured for 3, 7, 28, 90, and 120 days. It is found that the thermal, hydraulic and mechanical properties are time-dependent or affected by the degree of binder hydration index. Furthermore, a relationship is found between the compressive strength and the saturated hydraulic conductivity of the GF samples. The unsaturated hydraulic properties of GF samples have also been investigated. The outcomes show that unsaturated hydraulic conductivity is influenced by the degree of binder hydration index and binder content, especially at low suction ranges. Simple functions are proposed to predict the evolution of air-entry values (AEVs), residual water content, and fitting parameters from the van Genuchten model with the degree of hydration index (α). Furthermore, two columns are built to simulate the coupled thermo-hydro-mechanical (THM) behaviour of GF under drained and undrained conditions. The obtained results from the GF columns are compared with the small samples. It is observed that the mechanical properties, hydraulic properties (suction and water content), and temperature development are strongly coupled. The magnitude of these THM coupling factors is affected by the size of the GF. The findings also show that the mechanical, hydraulic and thermal properties of the GF columns are different from samples cured in plastic moulds.

This work deals with issues aimed at the possibility of treating the material which has not been used yet – coal tailings. The work includes among others the production, its optimalization and utilization of a new type of lightweight artificial aggregate in the process of production of concrete. The possibility of manufactured the artificial aggregate is dealt with the principle of self-burning of the raw material's batch at the agglomerative grate. The optimalization of the burning process was performed both with the homogenous and the layered batch. Further part of the work focuses on the fabrication of diverse types of concrete and determination of their parametres. This section is significantly extended with the comparison of basic physical and specific properities of the new type of concrete with those of the commonly produced types. The last part of presented work deals with the ecological - economic situation of these issues. The proposed solution points to the possibility of utilization of the coal tailings which are put to the tailings heaps. It was managed to optimize the burning process and to find the most convenient system for storing the raw material's batch at the agglomerative grate. Next, it was proved that the types of concrete produced with a new sort of aggregate are also suitable for fabricating the construction concrete with the strength above the border of 50 MPa, which are applicable even in harder conditions. These sorts of concrete also have a lower volume weight and very good bending properties. The major finding, which underlines the contribution of this work, is that the up to now unused material is suitable for fabrication of relatively high-quality and thermally stable aggregate of strength on the border of 5 MPa, which can be use for fabricating concrete with very good results even in this field. Another great contribution of this work can surely be the fact, that a preliminary economic balance of the manufacturing pr

MESMEG / Department of Mining and Environmental Geology / The increase in the demand and market price of gold has led to reprocessing of gold tailings in many parts of the world. Mines are recently closing down due to depletion of resources and increasing mining costs leading to the reprocessing of old tailings dams. The cost of rehabilitation is high, and therefore a more convenient way of rehabilitation is required. The most convenient strategy identified here was to reprocess tailings for gold and use waste rocks as construction materials. The tailings residues (waste remaining after reprocessing) will be relocated to a more convenient place to avoid pollution. Gold reprocessing from tailings dams has gained momentum in South Africa especially in the Witwatersrand Basin where there are large volumes of tailings. Gold is being reprocessed from tailings in this area using hydraulic monitors. This study focused on the evaluation of gold and heavy metals within the tailings at Consolidated Murchison Mine tailings in Gravelotte, Limpopo province. Augering was conducted over the tailings up to a depth of 8 m along four sampling Profiles. The first profile had two sampling points, the second profile with three sampling points, the third and fourth profiles consisted of four and five sampling points respectively. Samples were collected at 1 m interval, therefore a total of 112 samples were collected and analysed for heavy metals using X-Ray Fluorescence spectrometry and 84 samples were analysed for gold using fire assaying. Tailings sampling was accompanied with tailings logging, taking note of colour, texture and moisture content. Based on this, the oxidation status of the tailings dam was determined. Oxidation zone of this tailings dam was mainly from top down to a depth of 3 m. The transitional zone was not identified, hence after the oxidation zone, the rest was unoxidized zone. This study established that gold was erratically distributed within the tailings dam with the lowest and highest values of 200 mg/kg and 1880 mg/kg respectively and the average was 670 mg/kg. The tonnage of tailings within the dam was found to be 13 280 310 tons with a total gold amount of 8 897. 81 kg. At the current world market, this interprets to US$ 306 932 396.00 (R 4 281 706 924.20). It was concluded that this tailings dam is economically viable for reprocessing, although previous studies have indicated that it is not possible to extract gold from tailings dams completely. The heavy metal content of Pb, Ni and Cr were found to be high with average values of (ppm); 5631.5, 2062.6 and 1345 v respectively. The metals with the lowest values were Cd, Co and Cu, averaging (ppm); 0.01 ppm, 19.8 ppm and 42.1 ppm respectively. Heavy metal content in soil around the tailings dam was gradually decreasing with distance from the tailings dam. Waste rocks have been used in some parts of the world as sub-base material for engineering construction, hence in this study, a total of 6 waste rock samples were collected using grab sampling method for geostatistical investigation. Such samples were subjected to various geotechnical tests which included particle size distribution analysis (sieve analysis), Atterberg limit tests and laboratory compaction test to determine their suitability for construction. The waste rock material was found to be suitable for road construction as it was classified under Group A-1-a using the AASHTO classification system. The material consisted mainly of rock fragments, gravel and sand material with minor silt/clay. In general, Consolidated Murchison mine waste was found to be suitable for road construction. / NRF

Abandoned industrial-waste deposits (incl. fly ash or tailings ponds) represent very specific and mostly extreme habitat conditions. They offer unique opportunity to study primary succession in cultural landscape. Substrate of the material deposited here shows extreme properties, such as low pH, overheating of the open surface, salinization etc. The aim of this work is to map the colonization of different successional stages of vegetation by ants after years of abandonment of ore-waste deposits in Chvaletice (Eastern Bohemia, CR) and to compare the present state with analogous study made in 2001. Particular aims of both studies (Jarešová 2001, and present study, 2011-12) is to test the influence of ants on vegetation succession. During the years 2011-2012 several prospections were made to record species diversity of ants. On the surface plateau of the sedimentation basin two types of habitats were chosen - the areas with present ant nests and the other areas without them. Each of both types of habitats exhibits different plant species richness: separately the species-area curves were constructed and explained. Three dominant ant species of different size categories present on sedimentation basin were selected for experimental offering of plant seeds, Formica pratensis, Lasius niger, Tetramorium...

A human enters with his activities to the industrial landscape in the same natural way as the nature entered before, and developed them.

A study was conducted to evaluate the properties and processes influencing the rate and magnitude of volume decrease and strength gain for oil sand fine tailings resulting from a change in bitumen extraction process (caustic versus non-caustic) and the effect of adding a coagulant to caustic fine tailings. Laboratory flume deposition tests were carried out with the objective to hydraulically deposit oil sand tailings and compare the effects of extraction processes on the nature of beach deposits in terms of geometry, particle size distribution, and density. A good correlation exists between flume deposition tests results using oil sand tailings and the various other tailings materials. These comparisons show the reliability and effectiveness of flume deposition tests in terms of establishing general relationships and can serve as a guide to predict beach slopes. Fine tailings were collected from the various flume tests and a comprehensive description of physical and chemical characteristics of the different fine tailings was carried out. The characteristics of the fine tailings is presented in terms of index properties, mineralogy, specific surface area, water chemistry, liquid limits, particle size distribution and structure. The influence of these fundamental properties on the compressibility, hydraulic conductivity and shear strength properties of the fine tailings was assessed. Fourteen two meter and one meter high standpipe tests were instrumented to monitor the rate and magnitude of self-weight consolidation of the different fine tailings materials. Consolidation tests using slurry consolidometers were carried out to determine consolidation properties, namely compressibility and hydraulic conductivity, as well as the effect of adding a coagulant (calcium sulphate [CaSO4]) to caustic fine tailings. The thixotropic strength of the fine tailings was examined by measuring shear strength over time using a vane shear apparatus. A difference in water chemistry during bitumen extraction was concluded to be the cause of substantial differences in particle size distributions and degree of dispersion of the comparable caustic and non-caustic fine tailings. The degree of dispersion was consistent with predictions for dispersed clays established by the sodium adsorption ratio (SAR) values for these materials. The biggest advantage of non-caustic fine tailings and treating caustic fine tailings with coagulant is an increased initial settlement rate and slightly increased hydraulic conductivity at higher void ratios. Thereafter, compressibility and hydraulic conductivity are governed by effective stress. The chemical characteristics of fine tailings (water chemistry, degree of dispersion) do not have a significant impact on their compressibility behaviour and have only a small influence at high void ratio (low effective stress). Fine tailings from a caustic based extraction process had relatively higher shear strengths than comparable non-caustic fine tailings at equivalent void ratios. However, shear strength differences were small and the overall impact on consolidation behaviour, which also depends on compressibility and hydraulic conductivity, is not expected to be significant.