Thiourea Leaching Of Gold-Bearing Mine Wastes From The Madjarovo Processing Plant In The South East Of Bulgaria

2000 ◽  
pp. 181-188
Author(s):  
Stoyan Gaydardjiev
Keyword(s):  
Processing Plant ◽  
Mine Wastes ◽  
The South ◽  
Gold Bearing

scholarly journals Silicotic Lungs: The Minerals they Contain

1933 ◽  
Vol 33 (3) ◽  
pp. 307-329 ◽  
Author(s):  
William R. Jones
Keyword(s):  
Pathological Condition ◽  
Fibrous Tissue ◽  
The South ◽  
Chemical Action ◽  
Silicate Minerals ◽  
South Wales ◽  
Fibrous Minerals ◽  
Physical Form ◽  
The Impact ◽  
Gold Bearing

The results of these investigations on the mineral residues obtained from twenty-nine silicotic lungs, and of the examination of the rocks and materials which gave rise to the inhaled dusts causing these cases of silicosis, lead to the following conclusions:(1) The bulk of the mineral residues obtained from every silicotic lung investigated by the author consists of minute fibres of the mineral, sericite, a hydrated silicate of aluminium and potassium known also as “secondary white mica.” This mineral is abundantly present also in all the rocks and materials which gave rise to the inhaled dust; and it is present in these rocks and materials in minute fibres and scales of the size it is found in the residues and also in the lung tissue.(2) Silica in the uncombined state, as quartz, is also present in these residues as relatively coarse and fine grains; it occurs, however, in amounts subordinate to sericite. Especially is this so with regard to the small number of quartz particles, as compared with the countless fibres of sericite.(3) One relatively large grain of quartz, measuring 10 × 8 × 5 microns such as is found in the residues, is equal in volume to 800 fibres of sericite measuring 2 × 0·5 × 0·5 microns, and contributes as much silica in the chemical analysis of a residue as would 1600 fibres of sericite. This would appear to be out of all proportion to the silicotic effect of one such quartz in the bronchi and bronchioles, compared with the effect in the alveoli of hundreds of fibres of sericite.(4) Silica in the uncombined state, as quartz, is not the chief cause of silicosis in these and certain other cases. This appears to be conclusively established, it is submitted here, by the following facts: (a) The amount of quartz and the size and form of the quartz grains in the sandstones occurring in the underground working-places in the Scottish Coalfields and in the South Wales Coalfield, are alike. The latter sandstones give rise to dust that has caused scores of cases of silicosis, whereas no authenticated case of silicosis has been produced in the Scottish Coalfields. (b) The gold-bearing quartz conglomerate of South Africa gives rise to dust that has caused thousands of cases of silicosis; the gold-bearing quartz rock of the Kolar Goldfield, India, contains more quartz than the South African rock and yet produces dust that has caused no case of that disease. (c) No quartz-bearing rocks investigated by the author are known to have given rise to silicosis-producing dust except those which also contain abundance of fibrous aggregates of sericite or of fibrous silicate minerals, loosely held together and easily freed into the atmosphere when the rock is drilled and blasted. (d) Rocks which contain a relatively small percentage of quartz (well below the minimum amount in the rock types named in the Silicosis Schemes under English law) but which do contain fibrous silicate minerals such as sericite and sillimanite, as for example at Broken Hill Mines, New South Wales, produce dust that has caused a large number of silicosis cases.(5) These investigations are not concerned with the pathological condition produced by the minerals in the lungs. Whether they merely act as mechanical irritants causing the growth of fibrous tissue as advocated by some well-known authorities, or induce chemical changes as maintained by certain eminent pathologists, is a question entirely beyond the province of the author. His conclusions do not militate against either theory; on the contrary, they provide the former school with evidence of the presence in the lungs of thousands of acicular fibres that presumably could act as mechanical irritants, and the latter school with evidence of the presence of silicate minerals less stable than quartz and which, because of their physical form, expose far greater surface to volume for any chemical action than do the more compact grains of quartz.(6) Lastly, it is submitted here that it is mainly the presence in the exploited rocks and materials of fibrous minerals, be they sericite, sillimanite, tremolite, etc. (or a fibrous form of free silica as in chert or of a fibrous rock as in pumice) in aggregates which during the impact of drilling, blasting, or crushing, become freed into the atmosphere as individual fibres, that enables sufficient material in course of time to enter the lungs to cause silicosis. It is not suggested that sufficient minute particles of quartz could not, under any circumstances whatever, enter the lungs to cause silicosis, although the cases here investigated appear to show conclusively that they have not done so; but it is maintained that the fibrous minerals hasten the process so very considerably that their presence in the exploited rocks and materials is of far greater importance in causing this disease than is the presence of quartz.

Rb-Sr geochronology of single gold-bearing pyrite grains from the Katbasu gold deposit in the South Tianshan, China and its geological significance

2018 ◽  
Vol 100 ◽  
pp. 99-110 ◽  
Author(s):  
Leilei Dong ◽  
Bo Wan ◽  
Weizhong Yang ◽  
Chen Deng ◽  
Zhenyu Chen ◽  
...  
Keyword(s):  
Gold Deposit ◽  
The South ◽  
Geological Significance ◽  
South Tianshan ◽  
Gold Bearing

scholarly journals Current issues of search of gold placers in the south of Ukraine

2020 ◽  
Vol 16 (4) ◽  
pp. 32-40
Author(s):  
I.E. Lomakin ◽  
E.A. Sarvirov ◽  
V.V. Kochelab
Keyword(s):  
Ukrainian Shield ◽  
High Mass ◽  
Market Force ◽  
The South ◽  
Placer Gold ◽  
Gold Ore ◽  
Size Classes ◽  
Gold Market ◽  
The World ◽  
Gold Bearing

The main gold ore territory of Ukraine is Ukrainian shield, mainly its central and eastern parts. Currently, the potential of Ukrainian shield is estimated at 2.4 thousand tons of gold. Gold ore deposits are insufficiently studied and not brought to development. The same can be said about the development of gold placers. But in the case of shallow deposits its study and development may be economically justified, it does not require large capital investments and allows to recoup costs in a short time. This is especially true given the extremely favorable situation on the world gold market in recent years. Erosion and denudation of native deposits certainly led to the formation of deposits of native placer gold in the sedimentary cover on the territory of the Ukrainian shield and its slopes. Significant amounts of geological information on the widespread distribution of placer gold in loose sediments, in the modern basins of the Dnieper, Southern Bug, Don, Black and Azov Sea shelf, have been accumulated. This corresponds to the location of indigenous sources of gold and the general direction of unloading of river systems. Previous geological studies in this area have revealed numerous manifestations of placer gold of various scales, but no industrial facilities have been recorded. Placer gold in the south of Ukraine is characterized by a high mass fraction of gold of small and thin size classes and significantly aleurite-clay composition of gold-bearing deposits. Such characteristics complicate the geological search and real assessment of gold-bearing objects and, provided that standard sampling and processing methods are used in geological works, lead to underestimation of the real gold content. Studies conducted on the most studied placer sites convincingly show that gold is lost when washing samples, even under careful control. And this is a typical situation for many objects (not only Ukrainian), which were studied using the standard method of extracting free gold by gravity. That is why there are reasonable doubts about the reliability and quality of the current assessment of placer gold deposits. In our opinion, the prospects for the search for loose gold on the Ukrainian shield and its slopes are significantly underestimated. The presence of indigenous sources with great resource potential and at the same time numerous known manifestations of different ages and scales of placer gold clearly indicate the possibility of the formation of placers with industrial characteristics in the sedimentary stratum of southern Ukraine. The use of modern technologies for the gold enrichment and extraction, high-precision analytical research and the favorable state of the world gold market force to urgently review the results of previous geological work. The problem of conducting new comprehensive research aimed at auditing the accumulated data, identifying, and studying of placer deposits namely with gold of small and thin size classes is becoming urgent. The result of such work should be the discovery and industrial development of gold placers, which can be the basis of gold production in Ukraine.

scholarly journals IV.—The Geology of the Dolgelley Gold-belt, North Wales

1910 ◽  
Vol 7 (4) ◽  
pp. 159-171 ◽  
Author(s):  
Arthur R. Andrew
Keyword(s):  
The South ◽  
Ordnance Survey ◽  
Gold Mines ◽  
South Eastern ◽  
North East ◽  
The North ◽  
North Side ◽  
North Wales ◽  
The Town ◽  
Gold Bearing

The town of Dolgelley lies slightly outside the main tract of gold-bearing country of Merionethshire, but it forms a convenient headquarters from which to visit the various gold-mines and auriferous lodes. The Dolgelley Gold-belt lies within the area covered by the quarter-sheets 27 N.E., 27 S.E., 32 S.E., 33 N.W., 33 N.E., 33 S.W., 36 N.W., 36 N.E. of the 6 inch Ordnance Survey maps of Merionethshire. It is on the north side of the estuary of the Mawddach, extending from the sea at Barmouth to the locality of Gwynfynydd on the north-east. The belt forms the south-eastern flank of a range of high ground sloping down to the south and south-east from the mountains of Rhinog, Diphwys, and Garn. It is drained by several tributaries of the Mawddach, of which the principal are the Afons Hirgwm, Cwm-llechen, Cwm-mynach, Wnion, Las, Gamlan, Eden, and Gain.

scholarly journals A Holistic Approach in Re-Mining Old Tailings Deposits for The Supply of Critical Metals: A Portuguese Case

2019 ◽  
Author(s):  
Janine Figueiredo ◽  
M. Cristina Vila ◽  
António Fiúza ◽  
Joaquim Góis ◽  
Aurora Futuro ◽  
...  
Keyword(s):  
Laboratory Tests ◽  
Holistic Approach ◽  
Processing Plant ◽  
Mine Wastes ◽  
Environmental Intervention ◽  
Environmental Aspects ◽  
Critical Metals ◽  
New Techniques ◽  
Field Samples ◽  
Panasqueira Mine

The growth of demand for metallic minerals has faced with the need for new techniques and improving technologies for all mine life cycle operations. Nowadays, the exploitation of old tailings and mine wastes facilities could represent a solution to this demand, with economic and environmental advantages. W-Sn Panasqueira Mine has been operating for more than 100 years. Its first processing plant “Rio” was located near Zêrere river being the mineral processing residues deposited on the top hillside on the margin of this river in Cabeço do Pião tailings dam. The lack of maintenance and monitoring of this enormous structure in the last twenty years represents high risks to the environment and population of the surrounding region. The re-mining of the tailings by hydrometallurgical methods was considered, in order to satisfy these two enounced conditions - metals demand and environmental risk, aiming for the sale of the metal to pay the environmental intervention. Field samples campaign allowed collecting data and results from laboratory tests driving to use regression optimization. The re-mining solution was studied, taking into account the technical, economic, social, and environmental aspects.

scholarly journals Mineral types of gold deposits and regularities of their distribution in south-eastern part of the East Sayan

2019 ◽  
Vol 61 (2) ◽  
pp. 23-38
Author(s):  
B. B. Damdinov
Keyword(s):  
Gold Deposits ◽  
Crystalline Basement ◽  
The South ◽  
Genetic Characteristics ◽  
Gold Telluride ◽  
South Eastern ◽  
Leading Role ◽  
Mineral Associations ◽  
Metallogenic Zone ◽  
Gold Bearing

Based on the mineral composition, gold deposits of the south-eastern part of the East Sayan were typed. The most informative classification criterion for typing is the composition of the gold producing ore mineral associations which are specific to each of the selected types. Whereas using other criteria different structural, composition or genetic characteristics of deposits will necessarily overlap. Eight mineral types of deposits, characterizing the main gold-bearing ore mineral associations were identified: gold-polysulfide, gold-quartz, gold-telluride, gold-tetradymite, gold-stibnite, gold-bismuth-sulfosalt, gold-pyrrhotite and gold-fahlore types. Regional metallogenic divisions such as structural metallogenic zones, differ somewhat in the characteristics of mineralization. Thus, within the Bokson-Garganskaya metallogenic zone, gold-quartz, gold-polysulfide and gold-pyrrhotite types dominate, although gold-telluride and gold-bismuth-sulfosalt types are common in the western part of this zone. In the Ilchir zone, gold-fahlore type deposits are developed. Khamsarinskaya zone is characterized by gold-tetradimite and gold-antimonite deposits existence. It has been established that the mineral types of deposits formation depend on the enclosing rock complexes composition. Thus, gold-quartz, gold-polysulfide and gold-pyrrhotite types are formed in association with the ophiolites and rocks of the Archean crystalline basement. At the deposits associated with granitoid massifs, minerals of metalloids, such as bismuth-bearing sulfosalts, stibnite, tetradimite and tellurides, take a leading role in ores. In the carbonate strata, a gold-fahlore type is formed. The proposed classification allows typing all known gold deposits in the south-eastern part of the East Sayan and can be applied to adjacent regions.

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