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By J Q. Shi, M Karakus, Y Liu

Predicting the spatial distribution of rock mass properties in cave mining is a critical challenge. In this study, we introduce a novel machine learning-based model to advance our comprehension of rock behaviour. This model specifically focuses on the spatial distribution of rock mass and mechanical properties, a crucial aspect of our understanding of rock mechanics. Our model is inspired by the recognition that neighbouring information serves as crucial prior knowledge for predicting the spatial distribution of these properties, wherein closer neighbours are likely to exhibit similar characteristics. To effectively capture and model these neighbour relationships, we design a neural network-based model to map the spatial locations within the data set into a new highdimensional space. Within this transformed space, we utilise Euclidean distance to identify N neighbours. Leveraging these neighbours, we introduce a straightforward yet highly effective approach—label propagation—to construct a graph that illustrates neighbour relationships. This graph not only facilitates the prediction of the spatial distribution of rock mass properties but also offers a measure of uncertainty for these predictions. We validate the proposed method using a real rock data set and showcase its efficacy in capturing intricate relationships and distributions within rock properties, enabling precise predictions across diverse spatial scales. Our results underscore the potential of machine learning-based approaches to revolutionise the field of rock mechanics, providing valuable insights applicable to geotechnical engineering, mining, and other sectors where an accurate understanding of rock properties is paramount. This model has direct practical implications, offering a new tool for geotechnical engineers and mining professionals to enhance their understanding and prediction of rock properties, thereby improving safety and efficiency in their operations.

Sep 1, 2024

By D McKeon

In July 2006, ten Mining Engineering students and Associate Professor David Laurence from the University of New South Wales (UNSW) participated in the universityÆs inaugural overseas mining field trip. The ten-day trip to western Canada involved visits to two mines in British Columbia, the Diavik Diamond Mine in the Northwest Territories and the Syncrude oil sands operation in Alberta. Importantly, the groupÆs main objective was to gain a global understanding of todayÆs mining industry by observing the different cultural, legal, social and environmental setting found in Canada. It should be noted that the entire trip was planned, organised and directed by the students and benefited from extensive industry support both in Australia and Canada. This report intends to provide an overview of the field trip and describe to a limited extent the Canadian approach to mining.

Jan 1, 2007

By S Johnston, L Howe, S Stevens

Regulators have an important role to play in fostering and enabling reliable, effective, environmental management. Given this, it is perhaps surprising that there has been relatively little debate on exactly how regulators can enhance their own approaches, in order to promote improved outcomes overall. The authors argue that applying research on High Reliability Organisations, as well as the University of Pennsylvania’s Penn Program Framework for Regulatory Excellence, to regulators has the potential to facilitate positive environmental results across the mine life cycle.

Aug 2, 2023

By D Stephenson, N R. Steward

“TerraFlowingTM” is a dewatering process that addresses both the value proposition of Tailings as a Resource™, and the safe storage of tailings. “TerraFlowingTM” incorporates two stages of cyclone dewatering followed by centrifugation of the final dilute tailings stream. In this process three dewatered tailings streams are produced; a primary cyclone underflow, a secondary cyclone underflow and a centrifuge pulp. These three streams can be combined, or used, in various configurations to achieve different outcomes. The ability to vary the cyclone and centrifuge operations and configuration enables this process to deal with tailings feed variations in particle size distribution and mineralogy and deliver consistency, or design variations, in particle size distribution, tailings solids concentrations and recoveries. Water recovery can be up to 85% of the total water in the tailings with a stackable final tailings product achieved if the three tailings streams are combined in the maximum solids concentration configuration. The primary cyclone can be operated to deliver a particle size distribution suitable for tailings storage facility embankment construction or alternatives such as concrete structures or shotcrete for support. The secondary cyclone underflow and centrifuge pulp is suitable for beaching deposition within the tailings storage facility.

Jul 1, 2021

When a major mineral find has been announced the general perception is that a battle between Aborigines and the mining company involved will inevitably occur.It is a fact that many miners in the past have not had a good relationship with Aborigines because of their indifferent attitudes towards them. They saw no common future and went their particular way. However, attitudes have changed significantly since Noonkanbah and both miners and Aborigines are seeking common ground in order to achieve mutual benefits from the establishment of a mine on or near Aboriginal land. There are many obstacles that both miners and Aborigines need to overcome inordertofindthiscommongroundtoachieveawin/win situation. The obstacles can be found in entrenched ideas and practices which need overhauling, not the least of which emanate from government policy and requirements.Without going into specifics, the Noonkanbah incident during the 1970's where Aborigines and their supporters confronted miners who were ordered by the Western Australian governmentto drill on Aboriginal land, polarized Aborigines and miners. Since this incident, many Aborigines, particularly those in the cities, have had the attitude that mining and Aboriginal culture are in direct conflict. Aboriginal opinion is generally shaped in the larger cities through mass media coverage of the opinions of urban Aborigines and their supporters. Through no fault of their own, these Aborigines were removedfromthe land of their ancestors and have notlived atraditional Aboriginal life-style for a number of generations and most have little knowledge of, nor have had involvement in, traditional Aboriginal lore and culture. For the most part these people live in awestern life-style and few still know their language. They generally have high profiles, often giving viewpoints that are wrongly considered "Aboriginal" and supposedly representing all Aborigines. This group is very different with their thought processes and values from those Aborigines who live on their own traditional lands with a traditional life-style, and practise their age old ceremonies. Their tribal values are based in their relationship with the land, expressed through complex religious ceremonial rites of song, dance and legend. Today this group is very much diminished in numbers but nevertheless in the region of the Gulf of Carpentaria there is a high proportion ofpeople who practise their lore, speak their own languages and pass on traditions to their children. It is well documented in the history of Australia that Aborigines have been decimated in numbers and whole tribes have been wiped out. Certainly in this region the experience has been no different.

Jan 1, 1993

By V P. Beskrovnaya

Tests for the development of a metals recovery technology from samples of a Russian gold-bismuth deposit were carried out. Gold, silver and bismuth assay reported 5.6 g/t, 3.0 g/t and 0.08 per cent, respectively. Two flow sheet options were pilot plant tested: gravity/cyanidation of gravity tailings with subsequent flotation of cyanidation/carbon-in-pulp (CIP) tailings, and gravity/flotation concentration with cyanidation/CIP of concentrates. Option 1 results showed lower gold, silver and bismuth recoveries (81.3 per cent Au, 55 per cent Ag and 74.0 per cent Bi) due to low flotation efficiency for cyanidation tailings. Therefore, a flow sheet involving gravity/flotation concentration to produce bismuth-gold concentrates (0.8 per cent Bi) with subsequent cyanidation/CIP was recommended. Gold, silver and bismuth recoveries obtained by this method to the combined gravity/flotation concentrate were 90.2 per cent Au, 83.3 per cent Ag and 80.2 per cent Bi of the ore, respectively. Overall gold, silver and bismuth recoveries were 83.0 per cent Au, 40.5 per cent Ag and 80.2 per cent Bi, respectively. Gold and silver recoveries to the cathode precipitate were 92 per cent Au and 48.6 per cent Ag (per operation). Reagents consumed for flotation were 0.1 kg lead acetate/t ore, 0.4 kg butyl xanthate/t ore, 0.2 kg T-80 frother/t ore, 0.02 kg sodium hexametaphosphate/t ore, 0.15 kg copper sulfate/t ore. Reagents consumption for cyanidation was 0.42 - 0.48 kg NaCN/t ore and 0.2 kg CaO/t ore. It was recommended to deliver bismuth concentrates after hydrometallurgical treatment to a smelter. Overall bismuth recovery including bismuth recovery achieved by pyrometallurgy was 60.0 per cent. However, it was obvious that delivery of bismuth concentrates to a smelter and their commercial treatment would be very expensive due to relatively high mass pull of bismuth concentrates (7.6 per cent of the ore weight). For this reason, thiourea leaching and hydrochloric acid leaching with subsequent cyanidation/CIP were investigated as alternatives to cyanide leaching. These two alternatives were proposed to enable optimal recovery of valuable metals from concentrates on-site. Recoveries obtained by thiourea leaching were 91.2 per cent Au, 90.5 - 91.9 per cent Bi and 77.0 - 78.1 per cent Ag. However, that method required considerable capital and operating costs. As an alternative, hydrochloric acid leaching with subsequent cyanidation was investigated. Test results showed improved gold, bismuth and silver recoveries, which were 94 - 95.9 Au per cent, 94 - 96 Bi per cent and 76 - 78 Ag per cent, respectively. Hydrochloric acid consumption was 100 kg/t concentrate or 7.6 kg/t ore. Current efficiency during electrowinning was about eight to 12 per cent. A recommended flow sheet involving hydrochloric acid leaching of concentrates, electrowinning of bismuth from solutions, recycling solutions after electrowinning and cyanidation of hydrochloric acid leaching cakes is described. Overall recoveries achieved by the proposed flow sheet were as follows: 84.8 - 86.5 Au per cent, 75.8 - 76.9 Bi per cent and 63.2 - 64.9 Ag per cent. Based on results from these tests, initial data for a bankable feasibility study and plant designing were developed.

Jan 1, 2007

The quality of the external water source for a mineral processing plant may influence the extent to which the environmentally desirable practice of recycling of water from plant products is possible. This is particularly likely for froth flotation plants where the chemical quality of the water may affect the plantÆs performance. The quality of the external water source or the recycled water can be improved by a water treatment step, and in turn the extent of recycling which can be tolerated is able to be influenced. The quality of the external water can range from very high quality, soft water derived from melting snow, to poor quality, hard water (high levels of dissolved calcium and magnesium) from underground aquifers, and to even lower quality sea water (very high levels of dissolved species including sodium chloride). It can be noted that some underground water is more saline than ocean water as well as containing high levels of dissolved calcium and magnesium. Occasionally, a different source of water is utilised in the wet and the dry seasons. Increasingly, sewage water from cities is becoming a potential external water source with sustainability implications. If the initial quality of the external water is high, the scope for recycling of water from all the products is maximised. Such reuse or recycling of water from the products allows chemical species from oxidation of the ore and from other inputs to the process such as reagents to increase in concentration in the water returned to the plant. Such accumulation of species can have negative effects on the performance of a process such as froth flotation but instances of positive effects exist. Some reagents which are used in flotation plants such as lime or sodium carbonate also happen to be commonly used for independent water treatment plants. Hence, the flotation process may inadvertently provide some aspects of water processing. Where the quality of the water in the feed to a mineral processing plant (external water plus recycled water) is not an issue, more powerful solid-liquid separation processes can be considered to maximise the removal of water from the products and its reuse. Such processes may also have complementary benefits in a sustainable mineral industry by, for example, producing a tailing stream with a higher per cent solid value which is more suitable for safe storage on the surface or underground. This paper documents findings on the effect of water quality on the flotation process. It also considers current directions of change in the need for increased removal of water from plant products. It then considers the implications of these trends for maximisation of water recycling by such operations.

Jan 1, 2003

By M Skead, H Michael, R Chase, A Davidson

Ashanti Goldfields CompanyÆs (AshantiÆs) most recent development is the Geita Project in the Lake Victoria Goldfield of NW Tanzania. It comprises six distinct gold deposits within two mineralised trends: Nyankanga, Lone Cone, Geita Hill (Geita trend) and Matandani, Kukuluma and Area 3 West (Kukuluma trend). Between 1936 and 1966, the Geita area produced an estimated 5.5 M tonnes of ore from five underground deposits at an average recovered grade of 5.3 g/t. The discovery of Nyankanga was made by Ashanti in 1996 from RAB drilling of a +100 ppb Au anomaly in laterite soil above ferricrete cover. The Kukuluma trend was discovered by SAMAX Resources (taken over by Ashanti in 1998) between 1996 and 1997 from RC drilling of a +80 ppb Au laterite soil anomaly. Oxide facies banded iron formation (BIF) of the Upper Nyanzian System forms prominent topographic ridges and is the dominant host lithology for gold mineralisation. The ridges are flanked by felsic tuff units which lie stratigraphically above. Syn-genetic lamprophyre (vogesite) and post-genetic felsic dykes are also seen in the Geita trend. At Nyankanga a granodiorite-diorite suite has intruded as dykes and sills into BIF from a plug centred on a WNW fault and has produced wallrock alteration assemblages similar to those seen in Cu-porphyry systems (potassic, propylitic, etc) as well as sulphide and gold deposition. However, the main ore-grade mineralisation (as in the rest of the Geita trend) is controlled by low-to-medium angle structures dipping north-west and north with numerous splays in the hanging wall. High-grade shoots at Nyankanga plunge to the west and to the north-west, being lithologically and fault-controlled respectively. At Geita Hill the higher grade shoots are controlled by fold noses in BIF dipping to the north. Free gold occurs within fractures of sulphides. The deposits of Kukuluma and Matandani occur on an ancient (possibly Cretaceous) erosional plateau and are related to two WNW to NW trending shear zones, discordant to the local strike of the BIF sequence. Complete oxidation occurs up to 120 m depth and there is a strong supergene component to the gold distribution. Primary gold mineralisation is divisible into two distinct assemblages: arsenopyriteûpyrrhotiteûmagnetiteûchlorite associated with brecciated cherts and pyrite associated with shaley banded ironstones. Area 3W is most likely the fault-displaced extension of the same mineralised trend and comprises thin, intermittent zones of high-grade gold mineralisation occurring adjacent to a ridge in banded cherts and minor BIF. Current resources (measured, indicated and inferred) for the project are estimated at 89.24 Mt at an average grade of 4.17 g/t (11.97 Moz of contained gold) at a 1.0 g/t cut-off grade. Of this 9.83 Moz is within the Geita trend and 2.14 Moz is within the Kukuluma trend. A resource of 2.74 Moz is from an inferred resource at depth at Nyankanga where the viability of an underground operation is being studied. Proven and probable reserves are 49.77 Mt @ 3.46 g/t (5.54 Moz) based on a $325/oz gold price providing a mine life of ten years at an average production rate of 500 000 oz per year. Reserve estimation was carried out using mineable polygons to select resource blocks based on a series of mining and costs parameters. In addition key cost parameters were tested to provide sensitivities for pit optimisations and pathfinders for negotiations with suppliers and contractors. Construction began in March 1999 and first gold is expected to be poured in the second-quarter 2000.

Jan 1, 2000

By Mining Geophysics

Modern geostatistics has eliminated much of the guess-work in ore reserve estimation, and can calculate levels of confidence for the reserve estimate. Geological modelling software has brought about a revolution in the communication of complex geo-variables to mining engineers, metallurgists, surveyors and managers. Mine planning and scheduling can now avail itself of a veritable toolbox of enabling technologies.

Jan 1, 1994

By G L. Simmons, K M. LeVier, R Kappes

The low potential hydrophobic state of pyrite in amyl xanthate (PAX) flotation with nitrogen is of particular interest with regard to the N2TEC flotation technology currently being used for the recovery of auriferous pyrite at NewmontÆs Lone Tree Plant in Nevada. Initially, the N2TEC system had been found to operate satisfactorily, but cyanide in the flotation mill water appeared to be responsible for a loss in pyrite recovery. This supposition was confirmed with laboratory experiments, and a program was initiated to study flotation chemistry variables by electrochemically controlled contact angle measurements. Experimental results show that activation of pyrite in such cyanide solutions can be achieved more effectively with lead than with copper. Subsequently, based on these fundamental studies, significant improvement at the Lone Tree Plant was achieved by lead activation, in which case the recovery increased to expected levels. The effect of activator is particularly significant not only with respect to pyrite depression by residual cyanide, but also with respect to collector (PAX) consumption and the initial state of the pyrite surface. Experimental results show the importance of the pyrite surface state and the rather interesting features of the activation process.

Jan 1, 2005

By K Biegaj

During the author’s 25+ year career in mine management in various parts of the world (mostly in Australia), the author has been privileged to live and work in mining towns (not FIFO) for more than 20 years. And has personally observed other people from the mining industry carrying out work at home in an unsafe manner, eg pushing lawn mowers whilst wearing thongs or performing electrical jobs whilst standing on aluminium ladders, as well as many others. It is common that injuries sustained at home whilst on break are not reported upon arrival back on a mine site. A large number of compensation claims for injuries at work, which in fact had been sustained at home, come at substantial extra costs to mining companies.

May 5, 2022

By R Valenta

Most developing projects face a range of technical and non-technical challenges, and examination of development histories can potentially provide insights into improved approaches to project development. The Kestanelik project in the Canakkale region of Western Turkey was acquired by Chesser Resources Ltd in 2008. Turkey is a significant and growing source of gold production, with sector participation by both domestic and international companies. While the broad ranges of challenges faced by developing projects is well known, there are relatively few case studies in which the range of technical, environmental, social and governance challenges are presented in a single contribution. Recent studies of undeveloped complex orebodies have particularly shown the extent to which environment, social and governance (ESG) complexities contribute to project delays and failures. The Kestanelik project faced a full range of technical and ESG complexities, and provides an illustrative example of the associated challenges. CITATION: Valenta, R, 2018. A case study of technical, social and environmental challenges for a gold project development in Western Turkey, in Proceedings Complex Orebodies Conference 2018, pp 73–74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By McConachy G. W, Wright J. V

During the 110 years since the discovery of the Broken Hill PbZnAg deposit six major mining companies have mined the ore body and explored the ore environment. Despite this activity, no new orebodies have been found at Broken Hill. The failure to discover large new resources cannot be attributed to a lack of activity because major companies have maintained substantial exploration commitments over many decades. This suggests that not only was a unique coincidence of conditions required to form the deposit but also that full recognition and definition of the critical parameters may not yet have been recognised. In an attempt to illuminate some of the more unusual and poorly studied characteristics of the ore environment some new areas of investigation are presented here which may contribute to understanding the ore deposit setting and focus exploration towards different and perhaps more productive targets. Sedimentological characteristics of the host succession of the Broken Hill deposit are apparently unique along the line of lode. An upward-coarsening megasequence reflected in the development of clastic psammites stratigraphically below the ore deposit is one important ingredient which has received little exploration focus. These psammites also host mineralisation and form part of a spectrum of quart-zrich rocks collectively referred to as gametiferous psammites, garnet quartzites and blue quartz lodes. Sedimentological data interpreted from outcrop, drill core and downhole geophysical well logs support a elastic origin for some of these rocks; an interpretation which is at variance with traditional interpretations favouring an exhalative origin. A clastic origin for many of the footwall psammites, and their close spatial association with the orebodies suggests their role in ore formation was important. It is interpreted as a critical part of the fluid flow architecture within the sedimentary basin, which focussed ore forming fluids into an unique environment favourable for trapping mineralisation. Detailed stratigraphic correlation near the deposit has also highlighted that quartzofeldspathic rocks (Potosi gneisses and lode pegmatites) have complex relationships with ore. Suites of stratabound quartzofeldspathic pegmatites have received limited study, but their distribution and voluminous development suggests they may be as important to ore formation as the psammitic lode rocks which host the orebodies. These associations are not in conflict with some recent ore forming models invoking deposition in a shallow water environments of deposition. The geochemistry of parts of the host sequence has been studied extensively in the past but this has not been merged with current stratigraphic subdivisions. A large drillhole data base now permits the geochemistry to be related to the sedimentary succession and reveals that a signature involving stratigraphic vectors best illustrated by changes in MnO, Na2O, Pb and Zn can be detected. This is interpreted to reflect sedimentary basin processes as opposed to a classical volcanic hydrothermal alteration pipe associated with seafloor venting. The stratigraphic setting together with characteristics of some of these poorly understood areas is discussed to emphasise that construction of sound models for exploration requires the total ore environment to be studied with attention directed to the geometry and setting of the full range of host rocks. Control of the greater portion of the line of lode by a single company, Pasminco Australia Limited, now permits disparate datasets and observations to be merged and presents new opportunities and encouragement for model refinement and exploration success.

Jan 1, 1993

The results of a systematic geochemical survey of rare elements are applied to elucidate genetic relations in a suite of rocks and to predict the probability of mineralization. The geology, radioactivity, major element geochemistry and classification of the main intrusives are described. The distribution of a group of rare elements, their concentration trends and the bearing these have on the emplacement sequence of the rocks are considered in some detail. The guides for exploration in the Pilanesberg that emerge are listed and some areas which substantiate predictions are described briefly. It is concluded that a study of rare element trends can make a considerable contribution as an exploration tool and for clarifying relations between the members of rock suites.

Jan 1, 1986

The general principles of technical due diligence best practice that are involved in assessing a mineral property in the early stages of its development are described and a bibliography of relevant papers is attached. The issues specific to the evaluation of gold deposits are highlighted. The Australasian Institute of Mining and Metallurgy's (The AusIMM) initiatives in this area, dealing with the proper public reporting of Reserve/Resource information (JORC Code) and property assessment/valuation (VALMIN Code), will be used as a framework against which the illegal tampering with drilling samples to artificially boost their gold content (salting) from the Busang gold deposit (Kalimantan, Indonesia), owned by Bre-X Minerals Limited (Calgary, Canada), will be reviewed. While the Busang saga was based upon fraud, through salting the samples, the general lessons to learn from such a scam are worth documenting. In Australia, most of those working in the mineral industry belong to long established professional institutes and consultant associations (eg The AusIMM or Mineral Industry Consultants Association [MICA]) that require their members to work within their technical limits and to comply with best practice guidelines, or risk being judged and found wanting by their peers in the context of strong Ethics Codes. There is also a strong interface between such representative professional bodies and the corporate and financial market regulators (ASC/ASX), which closes the monitoring loop. Canada has only now seen the wisdom of having this type of early warning system in place. Fraud and deliberate deception will be always possible, but deception on the enormous scale that occurred at Busang is most unlikely with proper surveillance systems in place and the use of accredited technical professionals. There should have been more hard data available about so big and rich a deposit owned by a C$6Bn company.

Jan 1, 1997

By Jankowski P

The Bannockburn gold deposit is located 67 km north-west of Leonora in a poorly exposed part of the Norseman-Wiluna belt of Western Australia. The deposit consists of narrow, complexly shaped orebodies which have presented a challenge to find successful grade control and mining methods. The deposit also presents an opportunity to examine in detail the geology of this part of the Norseman-Wiluna belt.This paper discusses the geology and structure of the Bannockburn gold deposit as well as the grade control and mining systems developed to define the ore and extract it with minimum dilution. We discuss the different techniques employed for grade control in the past and their shortcomings, and the evolution of the present system of doing grade control in cross section from blast hole assays.

Jan 1, 1993

By Kupper T

Firstly, electric analog models are discus- sed to show fluid streaming conditions. In these models the depth of blast at tuyere level, the height of the bath, the influ- ence of different angles of the furnace zones and the different possibilities of the root of the cohesive zone have been changed. Tests to define the influence at a large blast furnace are given. Secondly, the wear of carbon bricks in the hearth is examined under the influence of gas, slag and pig iron. Oxidation tests in a special scanning microscope with the pos- sibility of heating and gas treatment are shown. Wear mechanisms are discussed fora large blast furnace and proposals for im- provement are given. Finally, the possib- ilities and value of the temperature meas- urement in the hearth block are discussed.

Jan 1, 1981

By Galecki G

The investigations conducted in the High Pressure Lab at the University of Missouri-Rolla demonstrated the ability of high pressure waterjets to excavate coal and minerals, disintegrate materials and as well as to comminute coal and minerals. Additional progress in comminution can be achieved if the compressive crushing principle commonly used at present is changed to one where particles are fragmented by the tensile growth of preexisting internal flaws or cracks, under internal waterjet pressure. This idea was studied in a number of tests. It covers tests with different jets imposed on coal and rock samples during compressive load as well as without any loading.

Jan 1, 1993

By Lewis PC, Carr GR, Dean JA, Glen RA

The Lachlan Fold Belt (LFB) is a complex orogenic belt which developed in Early to Mid Palaeozoic time. A number of orogenies and more localised deformational events affected the region. A simplified classification scheme for the diverse gold deposit types is proposed, subdividing primary mineralizing processes into four categories: volcanism (epithermal and volcanogenic deposits), igneous intrusion (subvolcanic/porphyry style, skarn and magmatic deposits), metahydrothermal processes (deposits generated during metamorphism and regional deformation) and hydrothermal-distal processes (deposits generated by poorly understood, generally remote large scale hydrothermal processes). Major gold deposit associations include epithermal and porphyry style deposits in Ordovician-Early Silurian shoshonitic andesite sequences; volcanogenic base metal-gold deposits in Silurian rift or basin felsic sequences; vein deposits in Late Silurian and Early Devonian S and I-type granitoids; deposits in Early Devonian sedimentary rocks of the Cobar Basin probably generated by metahydrothermal processes during basin closure and cleavage formation; deposits associated with serpentinite; and metahydrothermal quartz vein deposits in folded sedimentary rocks.Studies of host rock geochemistry suggest a relationship between magma types, gold enrichment and mineralization particularly in shoshonitic sequences and Early Devonian granitoids of the Boggy Plain Supersuite. Structural studies indicate the importance of thrust type structures and detachment faults in generation and location of gold mineralization. Lead isotope initial ratios help define metallogenic associations and a number of distinctive isotope "signatures" have been established.

Jan 1, 1990

By Piga P, Sammarco O

Ventilation and the environmental climate in the Campiano mine is the subject of this re- search. The mine is located in Southern Tuscany (Central Italy), a region where geothermal gra- dients are very high (three times the average gradient of the earth). The research produced interesting indications as to the influence of surface climatic conditions on the environmental parameters inside the mine. A close correlation has been found between dry-bulb temperature and humidity ratio of the air in the mine for dif- ferent metereological conditions and for differ- ent mass flow rate values. Variations in air enthalpy, caused only by the heat exchange with the rock walls during the flowing of the air through the mine, depends on the surface temperature values. Statistical analyses have been used to ex- press air enthalpy variations on surface tempe- ratures, on the variations of the humidity ratio that the air undergoes inside the mine and on the mass flora rate. The application in practice of the results will permit the identification of correct mea- sures to be adopted so that optimal microcli- matic conditions are produced in the mine.

Jan 1, 1986