This review summarises the factors which control the formation and distribution of surficial gold placer deposits. Regional tectonic and climatic conditions as well as gold source are considered. The characteristics of eluvial, alluvial, marine, glacial and fluvioglacial gold placer deposits are described. Particular attention is paid to the gold grains within these placers. These gold grains have a distinctive morphology and chemical composition which reflect the manner in which they were transported, deposited and concentrated within the placers. The knowledge of the processes which lead to the formation and location of surficial gold placers is then used to guide exploration and target potential deposits, which can then be evaluated.

This dissertation studies the evaluation of selectively mined, open pit gold deposits during the exploration stage of the mine's life. Since 1970 a large number of selectively mined, open pit gold mines have come into operation. The most common deposits include epithermal vein, mesothermal lode and laterite gold deposits. In general the deposits are characterized by small tonnages (1-20 million tonnes), relatively high grades (2-10 grams per tonne gold), submicroscopic to coarse gold, inexpensive mining, and both free milling and refractory ores.The key components that require evaluating during the exploration period are the deposit's geology, ore reserves, pit design, ore metallurgy and environmental impact. Feasibility studies are the main vehicle by which to report and guide the exploration programme. During the exploration period a company may undertake an initial (geological feasibility), second (preliminary mine feasibility) and third (final feasibility) delineation programme in order to gather sufficient data to justify a mine development decision. The responsibility of evaluating the mineral prospect lies primarily with the exploration geologist and mining engineer. Broad experience, a professional attitude, a thorough understanding of mining economics, and a high level of geological, engineering and technical skills are traits required by the evaluators. In order for mining companies to make sound investment decisions the geographical, geological, mining, metallurgical, environmental, marketing, political and financial aspects affecting the economic potential of the venture must be integrated so that the likely costs, risks and returns of the investment alternative are quantified. Ultimately, it is the economic analysis of these three items that determine whether the mineral prospect is developed into a mine I delineated further I retained until economic circumstances improve, or abandoned. To assess the costs, risks and returns, extensive use of the risk analysis is advocated throughout the exploration period . When combined with intelligent judgement of the intangible risk elements, the probabilistic distribution of discounted cash flows are invaluable in making sound investment decisions. However, the economic analysis is only as good as the information on which it is founded. Accurate and representative field data is the most important prerequisite to successfully evaluating and developing a new mine.

Gold-bearing volcanic breccia complexes are the major sources of gold in the Tasman Fold Belt System in north Queensland. The Tasman Fold Belt System represents the site of continental accretion as a series of island-arcs and intra-arc basins with accompanying thick sedimentation, volcanism, plutonism, tectonism and mineralisation. In north Queensland, the fold belt system comprises the Hodgkinson-Broken River Fold Belt, Thomson Fold Belt, New England Fold Belt and the Georgetown Inlier. The most numerous ore deposits are associated with calc-alkaline volcanics and granitoid intrusivesof the transitional tectonic stage of the fold belt system. The formation and subsequent gold mineralisation of volcanic breccia complexes are related to Permo-Carboniferous magmatism within the Thomson Fold Belt and Georgetown Inlier. The two most important producing areas are at Mount Leyshon and Kidston mines, which are high tonnage, low-grade gold deposits. The Mount Leyshon breccia complex was emplaced along the contact between CambroOrdovician metasedimentary and metavolcanic rocks, and Ordovician-Devonian I-type granitoids of the Lolworth-Ravenswood Block. The Kidston breccia complex is located on a major lithological contact between the Early to Middle Proterozoic . Einasleigh Metamorphics and the Silurian-Devonian Oak River Granodiorite. The principal hosts to the gold mineralisation at the Mount Leyshon and Kidston deposits, are breccia pipes associated with several episodes of porphyry intrusives. The goldbearing magmatic-hydrothermal and phreatomagmatic breccias post-date the development of a porphyry-type protore. The magmatic-hydrothermal breccias were initially emplaced without the involvement of meteoric-hydrothermal fluids, within a closed system. Later magma impulses reached higher levels in the cooled upper magma chamber, where meteoric water invaded the fracture system. This produced an explosive emplacement of phreatomagmatic breccias, as seen at Mount Leyshon. Widespread sericitisation and pyrite mineralisation are common, with cavity fill, disseminated and fracturelveincontrolled gold and base metal sulphides. The Kidston and Mount Leyshon breccia complexes have hydrothermal alteration and mineralisation characteristics of the 'Lowell-Guilbert Model'. However, the argillic zone is generally not well defined. The gold travelled as chloride complexes with the hydrothermal fluids before being deposited into cavities and fractures of the breccias. Later stage epithermal deposits formed at the top of the breccia complexes that were dominantly quartz-adularia-sericite-type. The erosion, collapse and further intrusion of later porphyry phases allowed the upper parts of the breccia complexes to mix with the lower hydrothermal systems. Exploration for gold-related volcanic breccia complexes is directed at identifying hydrothermal alteration. This is followed by detailed ground studies including geological, mineralogical, petrological and geochemical work, with the idea of constructing a 'model' that can be tested with subsequent subsurface work (e.g. drilling). Geomorphology, remote sensing, geochemistry, geophysics, petrology, isotopes and fluid inclusions are recommended exploration techniques for the search of gold-bearing volcanic breccia complexes. Spectral remote sensing has especially become an important tool for the detection of hydrothermal alteration. Clay and iron minerals of the altered rock, within the breccia complexes, have distinctive spectral characteristics that can be recognisable in multispectral images from the Landsat thematic mapper. The best combination of bands, when using TM remote sensing for hydrothermally altered rock, are 3/5/7 or 4/5/7. The breccia complexes have exploration signatures represented as topographic highs, emplaced within major structural weaknesses, associated I-type granitic batholiths, early potassic alteration with overprint of sericitic alteration, and an associated radiometric high and magnetic low. The exploration for gold-bearing volcanic breccia complex deposits cannot be disregarded, because of the numerous occurrences that are now the major gold producers in north Queensland.

The thesis takes the form of a collection of publications and patents concerning gold extraction which were presented over a period of 18 years while employed at the Anglo American Research Laboratories.

Dissertation submitted in compliance with the requirements for the Master's Diploma in Technology: Electrical Engineering (Light Current), Technikon Natal, 1987. / In the gold mining industry, one of the significant physical properties of the mineral slurry is its density and it is important to be able to measure this parameter in most processes. There are many techniques for determining the density of fluids, but because of the hostile, abrasive nature of mineral slurry, very few of these are suitable, This dissertation describes the deveiopment, construction and testing of a portable, ultrasonic, density measuring instrument. The instrument uses an ultrasonic transducer as the primary measuring element, and system operation is based on the fact that the driving impedance of the transducer varies with changes in the physical properties, and hence the characteristic impedance, of the surrounding medium into which the ultrasonic energy is being transferred. The technique may a-Lao be used to measure the relative concentrations of two liquids in a mixture or emulsion, provided that the characteristic impedances of the liquids are sufficiently dissimilar. The electronic circuitry is fairly straightforward, consisting essentially of an oscillator, driving circuit for the transducer and a voltage monitor to provide a d.c. voltage proportional to the impedance of the transducer, and hence to the density of the surrounding medium. Most of the research has been concentrated on the probe design, as the type of transducer, the type and thickness of facing material and the method of construction all contribute to the sensitivity of the instrument. A design of probe assembly has been developed that may be used for both slurry density measurement and the measurement of the ratio of aqueous to organic liquids in emulsion. / M

On the Gracey group of claims, Unuk River, B.C., are mesothermal-type quartz veins; (1) with speoularite-gold mineralization, (2) with galena-pyrite-gold mineralization, and (3) with chalcopyrite-pyrite mineralization containing no precious metals. The veins outcrop in a band of Late Palaeozoic(?) andesite tuff, siltstone, argillite, and limestone bordered on the northeast and southwest by Triassic(?) diorite gneiss sills. The main body of Coast Range intrusives outcrops five miles southwest of the property, but several stocks are exposed about five miles east of the property. The regional-type metamorphism, and most of the folding and faulting of the bedded rocks on the property have been caused by orogeny associated with the Coast Range intrusives; but some recrystallization of andesite-tuff can be attributed to thermal metamorphism produoed by the adjacent diorite-gneiss sills. The vein-forming fluids are probably derived from Coast Range intrusive rather than the local sills. In the quartz-galena-pyrite veins anhedral gold fragments are associated with three soft minerals, possibly tellurides, which form inclusions in the galena. In the quartz-specularite-gold veins the gold has been deposited in disruptions between specularite 'cleavage' plates. Both classes of veins contain minor amounts of gold in or near fractures in the quartz. No veins contain both abundant specularite and abundant sulfides. The specularite probably has been deposited earlier than the sulfides but in the same period of mineralization. Specularite does not necessarily indicate hypothermal deposition, but it is usually one of the first minerals deposited from hydrothermal solutions. It is formed only under oxidizing conditions, and if exposed to later sulfide-bearing, and thus reducing, solutions, it tends to be reduced to magnetite or an iron-bearing sulfide. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Mining frontiers have rarely attracted the attention of geographers because of the transitory nature of settlement in such areas. However, a more stable pattern of settlement emerges if the area of study is broadened to include the supply centres for the mines and the transportation routes along which the supplies were carried. The permanent impact of mining on settlement occurred in these service centres and along the main transportation routes leading to the mines. This study examines the nature of the permanent impact on British Columbia of the gold rushes which occurred between I858 and 1866. These rushes established a new pattern of settlement which remained until the coming of the railway in 1885, and, later, they acted as guidelines in the development of settlement. The British Columbia frontier was part of a larger frontier which was opened in California in 1848 and spread northward and eastward in the ensuing twenty years. San Francisco early secured a dominant position as the manufacturing centre for this frontier area, and it retained this position throughout the period of the British Columbia gold rushes. As a result, British Columbia remained within San Francisco's hinterland from 1858 to 1885 and most of the gold mined was shipped to the San Francisco Mint to pay for manufactured goods. The main flow of gold arrived when the United States Government was in very great need of gold to hack its borrowing for the conduct of the Civil War. The determination of the Colonial Government of British Columbia to secure political autonomy in spite of economic dependence on the United States led to the construction of costly wagon roads from east to west across the mountain barrier of the Coast ranges. These roads funneled trade from the interior of the Province through the Lower Fraser Valley to New Westminster and Victoria and thus avoided the traditional Columbia fur trade supply routes which lay in United States Territory. The wagon roads inaugurated a new era of transportation, and determined the locations of all important subsequent transportation routes in the southwestern part of Mainland British Columbia. Land was a strong interest among those who arrived in the gold rushes, and, at times, this land interest rivalled their interest in gold. The group of settlements subsequently established in the Lower Fraser Valley formed the nuclei of many present day communities, and the system of land survey which guided some of these early settlements shaped subsequent patterns of transportation. In the Province as a whole the patterns of settlement established between 1858 and 1866 remained substantially the same until the coming of the railway in I885. With the coming of the railway the Province entered a new phase of economic development, but the broad lines of settlement which the gold rushes created remained dominant and today they are still evident in the spatial organization of economic activities. Gold initiated a pattern which was confirmed by the subsequent construction of the trans-continental railway, the growth of the forest industries, and the development of agriculture. / Arts, Faculty of / Geography, Department of / Graduate

Sampling of soils and till are conventional methods of gold exploration in glaciated regions. However, the exact nature of the residence sites and behaviour of gold within soil and till are poorly known. A gold dispersion train extending from the Nickel Plate mine, Hedley, southwest British Columbia, was investigated in order to determine the distribution and behaviour of gold within soils developed from till. Three hundred and twelve soil, till and humus samples (representing LFH, A, B and C horizons) were collected from fifty-two soil pits and thirty-four roadcut locations within the dispersion train. Soil and till samples were sieved into four size fractions; the resultant -212 micron (-70 mesh) fraction of each sample was analysed for Au by FA-AAS. Humus samples were ground to -100 micron powder and analysed for Au by INAA. Based on the analytical results, each LFH, A, B and C horizon was subdivided into anomalous and background populations. Detailed size and density fraction analysis was carried out on soil profiles reflecting anomalous and background populations, and a mixed group of samples representing the overlap between both populations. Samples were sieved to six size fractions; three of the size fractions (-420+212, -212+106, -106+53 microns) were separated into two density fractions using methylene iodide and analysed for Au by FA-AAS. The Au content of the -53 micron fraction was analysed by FA-AAS and cyanide extraction - AAS. Results indicate that the Au content of soil profiles increase with depth while decreasing with distance from the minesite. Heavy mineral concentrates and the light mineral fraction Au abundances reveal that dilution by a factor of 3.5 occurs within the till over a distance of 800 metres. However, free gold within the heavy mineral fraction is both diluted and comminuted with distance. Recombination of size and density fractions indicate that the Au contents of each size fraction are equivalent; variation in Au abundance is not observed with a change in grain size. Seventy percent of the Au in the -53 micron fraction occurs as free gold. Chemical activity has not altered the composition of gold grains within the soil profiles. Compositional and morphological differences between gold grains are not indicative of glacial transport distance or location within the soil profile. Relative abundances of gold grains between sample locations can be used as an indicator of proximity to the minesite. The sampling medium with the best sample representivity and contrast between anomalous and background populations is the -53 micron (-270 mesh) fraction of the C horizon. Geochemical soil sampling programs in the vicinity of the Nickel Plate mine should collect a minimum mass of 370 grams of -2000 micron (-2 mm) soil fraction in order to obtain 30 grams of the -53 micron fraction. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

M.Ing. / Gold ore deposits are depleted near the surface of the earth and the remaining deposits are located at great depths of over 3000m. Geothermal energy will cause the ventilation air temperature to increase above 50°C, and therefore it must be cooled to an effective working temperature. The cost of providing acceptable air temperatures to the workers in the mine plays an important role in the feasibility of whether to proceed with a mining project. At present the air in South African gold mines is cooled by a number of processes including bulk air coolers and direct contact spray chambers. In all of the above mentioned processes large quantities of water need to be pumped into the mine where it is used as the cooling fluid to reduce the air temperature. One of the recent developments for cooling the ventilation air uses ice, produced on surface in large quantities and transported underground in conventional plastic piping. It is regarded as the most effective system for creating chilled cooling water. To create an even more effective process, the properties of a new coolant will be investigated. In the new process, ice is transported into the mine and then mixed with a brine solution. The presence of the salt in the brine creates a freezing point depression and an endothermic chemical reaction causing the temperature of the mixture to decrease well below zero degrees Celsius. This chilled brine solution will be used instead of water to decrease the temperature of the ventilation air. The aim of the project is to conduct an analytical and experimental evaluation by using ice and brine as the coolant. In the experimental investigation the coolant is pumped over a flat, multi-plate heat transfer surface where the air flow is maintained at a constant rate. This simplifies the mathematical modeling and gives useful relationships between the experimental results and the theoretical results.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in the partial fulfilment of the requirement for the Degree of Master of Science in Engineering / The impact of TMMM on Environmental Engineering is pervasive in all aspects. More critical aspects have been evaluated to quantify their impact on air and refrigeration of a typical deep, hot gold mine. ( abbreviation abstract) / Andrew Chakane 2018