Dense media separation (DMS) plays an integral part in coal processing as well as in the upgrade of low grade ore bodies prior to further processing like flotation and leaching. Various separating vessels are used in DMS; of which the dense media (DM) cyclone is the most common. However, the limited materials of construction available for DM cyclones leave the industry with little choice. In addition, the DM cyclones available moved away from the basic principles of classification hydrocyclones which is to reduce the turbulence in the feed chamber in order to achieve improved efficiency. The ceramic tiled DM cyclones available in the market have ceramic tiles installed perpendicular to each other in the feed chamber, which increase the turbulence in the feed chamber at the expense of longer equipment life. For that reason, a research project was initiated to establish the current installed base of DM cyclones in Southern Africa and to develop and evaluate a DM cyclone with a laminar spiral feed chamber design to reduce the turbulence when feeding the cyclone, whilst achieving the same or superior wear properties. Because Cavex is well proven in hard rock mining and coal classification, it was used as basis for the development of a DM cyclone. Individual moulds were developed and produced in order to fabricate a Cavex DM cyclone with the exact laminar spiral feed chamber that exists when moulded out of rubber. Afterwards, the Cavex ceramic tiled (CVXT) cyclone was manufactured, installed and commissioned. Using the basic operating principles of hydrocyclones, the predicted results were achieved. The 650CVXT results confirmed that a DM cyclone and a classification cyclone are inherently the same piece of equipment; it is the selection criteria and material of construction that differ. There is a definite benefit in focussing on metallurgical efficiency in conjunction with wear properties, rather than equipment life (wear life) as the only parameter during equipment fabrication. A simple way to achieve improved performance is to reduce the turbulence in the feed chamber. Further work must include the evaluation of the Cavex CVXT DM cyclone in near gravity coal circuits and to investigate whether the same lower operating pressures (6D compared to conventional 9D) will result in improved coal yield, as was illustrated successfully in the separation of fluorspar by DMS, whilst achieving the desired ash contents. The work must include detailed studies on the effect of feed pressure vs. yield/recovery, when the turbulence the feed chamber is reduced. Overall energy savings should be quantified by reducing the cyclone feed pressure.

A Thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy 2015. / Gold mining in South Africa has been the backbone of the economy for many years. With it came economic well-being, the growth and development of satellite towns, cities and metropolitan cities, e.g. Johannesburg-a place of gold. Unfortunately, it also came with adverse effects, most of which are now evident, after a century of mining, with little or no regard for pollution prevention or any form of remediation. Of interest, in this study, is the presence of tailings storage facilities (TSFs) found within the residential areas, in close proximity to commercial district and industry, having been built around them. Currently, some 270 TSFs lie dormant, pregnant with vast number of toxic heavy metals from the initially low efficient but selective gold processing techniques. This led to the deposition of the sand dumps, with high sulphur, iron, chromium, cadmium, arsenic, and mercury amongst other toxic metals. Exposure to oxygen, and water, the pyrites were oxidized and formed acid mine drainage (AMD), which resulted in the leaching out all toxic heavy metals into ground water and surface water causing serious water pollution and environmental degradation. Due to the low efficient gold processing technique, some gold amount was discarded together with the tailings materials. The reprocessing of these dumps led to the generation of dust, which is easily distributed over large areas of land. The unrehabilitated, semi-rehabilitated, and the abandoned TSFs contributed to all forms of pollution, majorly, windblown dust from unprotected tops and sides, AMD leaching toxic heavy metals. In this study, mercury, one of the most toxic elements found within the vast TSFs was determined. This was carried out as part of a larger environmental impact assessment on the effects and scale of pollution from the gold mining in the Witwatersrand. The study area consisted of the greater Johannesburg area, covering commercial business district (CBD), the industrial areas (Aeroton, City Deep, Germiston, Selby, Springs), and the residential areas (Alberton, Boksburg, Centurion, Germiston, Greenside, Sandton, Springs). Dust samples were collected from paved surfaces in the streets, and accessible buildings, were sieved into three sieved into three fractions (PM100, PM50, PM25), and most of the work focused on the smallest size fraction (PM25) in order to study impact of inhalable and respirable dust. Three sequential extraction procedures (modified BCR-the European Community Bureau of Reference, selective sequential procedure (SSE), and novel sequential extraction procedure (n-SEP)) were applied for partitioning and evaluating the mobility, availability and persistence of mercury in urban dusts. Bioavailability of mercury was assessed by leaching dust with artificial gastric and lung fluids which mimicked body conditions. Contamination levels were assessed based on the enrichment factor (EF), contamination factor (Cf) and geoaccumulation index (Igeo) were calculated to further assess the environmental risk and provide a preliminary estimate of the main sources of mercury in street dust. Non-carcinogenic effects and carcinogenic effects due to exposure to urban street dusts were assessed for both children and adults. The total mercury (HgTOT) ranged from 269 to 1350 μg kg-1. In the PM25 size fraction, mercury exhibited the following decreasing order of HgTOT: industrial area > CBD > residential area. This order shows that the HgTOT concentration in the street dust decreased with increased distance from the TSFs. The highlight was that the highest HgTOT was reported in industrial areas next to the TSFs, tailings reprocessing areas, and tailings footprints. Furthermore, in residential areas grossly affected by TSFs and tailings reprocessing, reported high HgTOT values similar to those reported for industrial samples. These results indicated that the presence of TSFs were largely responsible for the mercury found in the dust. The results from the characterization of the dust showed a large concentration of fine particulate matter, with the characteristically high quartz (74 – 98 wt. %), and minor minerals phases such as chloritoid, chlorite, K-feldspar, jarosite, mica, muscovite, pyrite, and pyrophyllite, all below 10 wt. %. These have been known to enrich trace metals, hence a high concentration of mercury. The close proximity of the tailings to the communities led to the determination of bioavailability of mercury from dust. The bioaccessible Hg extracted by lung fluid (up to 3% of HgTOT) was higher than that of gastric fluid (up to 1% of HgTOT) and was related to the mobile pool of Hg in dust. This suggests that human exposure to Hg in dust via inhalation is greater than that via the gastric tract. These values were very similar to the values obtained from water soluble phase in the sequential extraction procedure (average 1.4% of HgTOT). This indicated that these fluids were able to extract the most bioavailable fraction of Hg, which is responsible for most of the transformation reactions involving mercury. Contamination assessment factor was carried out to classify the pollution levels and indicate whether they are from natural or anthropogenic sources. Based on the EF, Cf, and Igeo, 70, 82, and 84% of the street dust samples were classified as heavily enriched, very highly contaminated, and strongly polluted by mercury, respectively, indicating that they are of anthropogenic origin. The human health risk model was useful in identifying the areas of health risks from exposure to mercury pollution. It showed that children were more vulnerable than adults when exposed to mercury in dust via ingestion. The cancer risk for exposure to As, Cd, and Cr by both children and adults was significantly high for oral ingestion of dust. Cr (VI) was the highest contributor followed by As and lastly Cd. For inhalation pathway, the possibility of developing cancer after a lifetime exposure was low and below the acceptable limits (10-6).

This report investigates the application of digital computer simulation models to the analysis and optimization of complex mine water reticulation systems- A simulation program is developed and documented, Guidelines in the construction and use of mine water models are applied in a case study of water quality and quantity aspects of Unisel Gold Mine.

Investigations have been carried out for a number of cobalt deposits in Australia including three from the Mt Isa Block in Queensland, several deposits in New South Wales, and one deposit each in the Northern Territory and South Australia, with respect to the identification of cobalt-bearing mineralisation and possible modes of formation. The deposits studied cover a range of deposit and mineralisation types including hydrothermal (e.g., cobaltite, Esperanza, Queensland; arsenopyrite, Dome Rock, South Australia) and sedimentary (secondary mineralisation such as the manganese wads at Bungonia, New South Wales). Deposits that were studied previously by the author (MSc thesis) in the Mt Isa Block have been used for comparison of mineralisation and temperatures of formation. The determination of the temperatures of formation of mineralisation, in particular with respect to cobaltite and arsenopyrite, by means of the application of the FeAsSCoAsS-NiAsS ternary phase diagram and the arsenopyrite geothermometer, has helped lead to deductions concerning the modes of deposition. Other deposit features such as structural constraints and associated mineralisation aided in the formalisation of conclusions. Many of the deposits are hydrothermal in nature and contain high temperature phases including molybdenite and uraninite. The latter represent geochemical and mineralogical clues which show that many of the ores were emplaced by igneous processes associated with granites. The findings of this study suggest that despite high percentages of substituting species in arsenopyrite, derived temperatures, from the application of the binary and ternary geothermometers, are comparable. It was noted that the presence of pyrrhotite and/or löllingite to act as buffers in the system is an important constraint on the comparability of derived temperatures. Potential processing applications for the extraction of cobalt from ores are briefly discussed, with respect to the type and cobalt content of mineralisation identified. The Esperanza and the Selwyn copper-gold deposits show the greatest potential for economic cobalt recovery. / Doctor of Philosophy (PhD)

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1926. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed November 30, 2009) Includes index (p. 30-35).

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1887. / The entire thesis text is included in file. Holograph [Handwritten and illustrated in entirety by author]. Title from title screen of thesis/dissertation PDF file (viewed December 28, 2009)

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains x, 64 p. : ill. (some col.), maps. Includes abstract. Includes bibliographical references (p. 63-64).

Thesis (M.A.)--Ohio State University, 1954. / Available online via OhioLINK's ETD Center

No description available.

The asbestos resources in Turkey should be exploited in a carefully planned manner for two reasons: (1) to minimize the health hazards associated with the mining and processing of asbestos, and (2) to avoid wasteful exploitation for the sake of making profit. Its consumption should be optimized by using it for the critical applications only, where its unique properties are essential. Turkey's asbestos resources and alternative minerals to asbestos should be exploited to assist in its economic development. However Turkey must control the environmental and occupational hazards associated with the production of these commodities if it is to avoid the loss experience of other developed countries. The hazards associated with the use of asbestos in many noncritical applications have raised the demands for substitute materials which are less hazardous. Turkey is in a position of developing and marketing many of the substitute materials by exploiting some of its industrial minerals.