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By MINE SAFETY BOARD

RECOMMENDATIONS OF THE UNITED STATES BUREAU OF MINES ON CERTAIN QUESTIONS OF SAFETY AS OF FEBRUARY 3 , 1933

Jul 1, 1933

By C. Garcia, J. J. Opazo, A. Potulsha, T. Comi

"Sierra Gorda SCM is a joint venture partnership of KGHM International (owned by KGHM SA, Poland), Sumitomo Metal Mining and Sumitomo Corp. (Japan) operating in northern Chile. The Sierra Gorda openpit mine and coppermolybdenum processing plant will become one of the largest mines in the world. The need for optimum production efficiency and sustainability has driven the creation of the most modern, wellinstrumented mine in Chile. This article contains a general review of the project including geology and history.This was a fast-track project going from greenfield site acquisition to mill startup in 10 years. Highly experienced and motivated engineers and technical staff have overcome many significant challenges resulting in a rapid ramp-up of production capacity. A potential expansion to double the production rate in the fourth year of operation has also been intensely studied.The Sierra Gorda property is located in the Atacama Desert of northern Chile, in the District of Sierra Gorda, Region II of Antofagasta, Chile (Fig. 1). There is almost no precipitation in this area. The mine site is generally flat with some rolling hills. The project is located about 5 km (3 miles) from the village of Sierra Gorda at an elevation of approximately 1,700 m (5,600 ft) above mean sea level. The village is near a highway and railway line. The city of Calama, home of the famous Chuquicamata Mine, is located about 60 km (37 miles) northeast of Sierra Gorda. In addition, the SG mine is in the midst of numerous other mines including Spence, Esperanza, Mantos Blancos, El Tesoro, Lomas Bayas, Gabriela Mistral, El Abra, Radomiro Tomic and Escondida, to name a few.The primary organizational value at Sierra Gorda is "Zero Harm." This includes employees, contractors, the environment, the community, plant facilities and mine equipment. A cornerstone of this program is called 5X5S (five by five S), which combines the lean principles of 5S with the safety model of taking five steps back and thinking about the task at hand for five seconds, five minutes, the time it takes to assess and manage the risk. "People caring about people" promotes proactive engagement in the safety of coworkers and others at work and at home."

Jan 1, 2014

By Patrick R. Taylor

In the search for the development of more "environmentally friendly" and more intensive waste disposal approaches to meet more and more stringent environmental regulations, thermal plasma-based processes? are considered one of the most promising alternatives to well-established technologies such as incineration. This paper presents an overview on the research and development status of thermal plasma-based waste remediation technologies. The properties of thermal plasma are described. Due to its unique feature of high-energy intensity and super high temperature, thermal plasma is particularly capable of destroying organic-containing wastes. Its potential and promising application to waste remediation may include: treatment of incinerator ashes; metallurgical dusts (especially, electric arc furnace dust); medical wastes; radioactive wastes; and other Resource Conservation and Recovery Act (RCRA) listed hazardous wastes. Many research institutes and vendors have been involved in the development of thermal plasma-based waste treatment-technology encouraged by the cleanup programs supported by the Environmental Protection Agency (EPA), the Department of Energy (DoE) and the Department of Defense (000). More recently, thermal plasma-based waste treatment technologies (sometimes called plasma-enhanced pyrolysis) are focused more and more on not only just destroying organic wastes but also on how to practically, and economically recover energy contained in the organic waste materials in addition to the recovery of metals in order to offset the high operating costs.

Jan 1, 2003

By Patrick R. Taylor

In the search for the development of more "environmentally friendly" and more intensive waste disposal approaches to meet more and more stringent environmental regulations, thermal plasma-based processes are considered one of the most promising alternatives to well- established technologies such as incineration. This paper presents an overview on the research and development status of thermal plasma-based waste remediation technologies. The properties of thermal plasma are described. Due to its unique feature of high-energy intensity and super high temperature, thermal plasma is particularly capable of destroying organic- containing wastes. Its potential and promising application to waste remediation may include: treatment of incinerator ashes; metallurgical dusts (especially, electric arc furnace dust); medical wastes; radioactive wastes; and other Resource Conservation and Recovery Act (RCRA) listed hazardous wastes. Many research institutes and vendors have been involved in the development of thermal plasma-based waste treatment technology encouraged by the cleanup programs supported by the Environmental Protection Agency (EPA), the Department of Energy (DoE) and the Department of Defense (DoD). More recently, thermal plasma-based waste treatment technologies (sometimes called plasma-enhanced pyrolysis) are focused more and more on not only just destroying organic wastes but also on how to practically, and economically recover energy contained in the organic waste materials in addition to the recovery of metals in order to offset the high operating costs.

Jan 1, 2003

By B Yang, S M. Aminossadati

Transporting coal by means of conveyor belts is very common in Australian underground coal mines. Major conveyor belt-related mining incidents are now relatively infrequent as a result of recent improvements in engineering standards and use of fire-resistance materials. However, conveyor belts have the potential for incidents capable of causing either personal or structural damage. In addition, any unexpected break down of rolling components or failure of belts creates a significant interruption to the production that is a major concern for operators whose responsibility is to achieve the optimum mining production.Currently, underground coal conveyor belts are examined for the presence of any overheating, smouldering or unsafe conditions likely to cause a fire. Periodic inspection of operating conveyor belts is carried out with the aim of detecting any local heat sources in an early stage. This includes temperature measurements of the driving head, idlers and rollers using hand-held temperature sensors such as infrared cameras or laser temperature sensors. The disadvantages of current conveyor belt temperature monitoring systems include high labour and equipment costs, safety risk to personnel who are in close proximity to moving conveyors, the ability to take line of site measurements only and potential for missed overheated idlers. Some of the conveyor idlers in underground coal operations cannot be accessed for traditional temperature measurements. This introduces a significant risk to the operation of critical infrastructure.A distributed temperature sensing (DTS) system can be used to develop an advanced conveyor belt temperature monitoring system that provides real-time, accurate and continuous temperature measurements along a conveyor belt particularly at the rolling components. The DTS system comprises of fibre optic detection cable, DTS controller and interfacing module. The advantages of the system include the accuracy, low-cost, easy installation, robustness, safety, immunity to radio frequency and electromagnetic interference, real-time data collection, and secure data transmission. This paper presents a scoping study on the development and utilisation of a fibre optic-based DTS system for underground coal conveyor belts. The mechanism of heat generation, the operation temperature range and the installation issues of fibre optic cable along the conveyor belt particularly in close proximity to each end of the spindle on every idler will be discussed.CITATION:Aminossadati, S M and Yang, B, 2013. A scoping study on fibre optic-based temperature monitoring of underground coal conveyor belts, in Proceedings The Australian Mine Ventilation Conference , pp 35-42 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By C. H. Wayman, D. W. Fuerstenau

The effect of bubble size and concentration of certain reagents on the terminal velocity, shape, path, and drag coefficients of single air bubbles in distilled water has been investigated. Bubbles of a certain size range rise considerably faster than Reynolds number-drag coefficient relationships predict, whereas a small amount of frothing agent reduces their terminal velocity. The rapid velocity at which bubbles rise in distilled water appears to result from slip at the boundary and from circulation within the bubbles. Surface-active agents retard bubble motion through prevention of both circulation and slip at the boundary. A surface tension concentration gradient helps maintain bubble sphericity. HE gas phase is one of the indispensible in-gredients in flotation operations. Flotation depends on the collision of an air bubble and a mineral particle in a pulp and their ability to remain in contact long enough for adherence to take place. Before it is possible to understand the mechanics of air bubble-mineral particle encounter, it is necessary to learn more about the nature of bubbles themselves before collision with a mineral particle has taken place. To date, little work has been done on air bubbles in flotation systems. In 1945 Fahren-wald' presented a study of the role of frothers on air bubbles and on aeration in flotation, and recently Wark and Sutherland' discussed the work of Rosenberg- in relation to flotation. The research reported in this present article was undertaken to investigate systematically the effect of bubble size and the concentration of certain reagents on the terminal velocity, shape, path, and drag coefficient of single bubbles in distilled water. Most of the work is concerned with the effect of a-terpineol on bubble motion in water, but studies were made with potassium chloride, potassium hydroxide, potassium ethyl xanthate, and potassium amyl xanthate. Experimental Method and Materials: To obtain free bubble rise and reduce wall and surface effects, the investigators used a tank of 5½x5½x30-in. internal dimensions, filled with water to within 4 % in. of the top.' The tank was made of acrylic plastic so that the walls would have good optical properties. Distilled water, which was re-distilled in a block tin still and saturated with air before each test, was used in all the experiments. All solutions were made with reagent-grade chemicals. During each experiment the water was at room temperature, and during the course of an experiment the temperature did not fluctuate more than 0.5°C. Since the experiments were performed over a period of six months, the temperature varied between 25° and 27°C. The temperature at which each series of experiments was conducted is recorded with the data. The experimental apparatus is presented dia-grammatically in Fig. l. Individual air bubbles were generated from purified compressed air through a capillary of 0.003-cm internal diameter at a rate

Jan 1, 1959

By Shimi Tzobery, Jay Davenport, Raymond Henn, Sam Bandimere

Over the past several decades, the use of cement-based grouts using ultra fine cement as a replacement for portland cement has begun to gain acceptance as an alternative to chemical solution grouts used in permeation grouting. The amount of information currently available on grouts made with ultrafine cement is limited. The authors used a previously developed field testing program to perform additional tests to evaluate the permeation performance of portland and ultrafine cement-based grouts. For the first time, the 2003 testing program included an attempt to determine the 28 day compressive strength of the sand permeated by the grout.

Jan 1, 2005

By S Dirdjosuwondo, R Plaisance, L Thoma

PT Freeport Indonesia, a subsidiary of New Orleans-based Freeport McMoran Copper and Gold of New Orleans, operates a large mining complex on the Western half of the Island of New Guinea in Tembagapura, Irian Jaya, Indonesia. The IOZ (Intermediate Ore Zone) mine, one of the underground orebodies, is mined by block caving. The area affected by the cave collects a large quantity of rain and ground waters mixing with fine rock particles. The mixture, commonly called æwet muckÆ, sometimes spills into drawpoints and makes the working environment hazardous to the loader operators. Wet muck is observed in an increasing number of drawpoints in the IOZ mine and remote LHD (Load-Haul-Dump) technology has been implemented to handle the ore. The driving force for this automation project has been the safety of the loader operators. The system has been developed mainly in-house and incorporates state-of-the-art features. Up to eight remote loaders and nine rock breakers are controlled from an underground control room located approximately 400 metres from the active extraction panels. The two underground crushers and nine conveyor feeders are also operated remotely from an adjacent control room. The development of FreeportÆs remote system has taken time and considerable effort. Not only the success of the IOZ mine was at stake but also the fulfillment of environmental commitments pertaining to the mill tailings. Approximately eight per cent of the mill feed must come from underground skarn deposits to neutralise the acid-generating tailings generated by the huge Grasberg open pit ores.

Jan 1, 2000

By P N. Holtham

As part of a long-term study of titanium minerals processing being undertaken by the Julius Kruttschnitt Mineral Research Centre (JKMRC), techniques have been developed to measure the electrical properties of the various minerals. The measured values will be used to model the behaviour of the various minerals in high-tension roll and electrostatic plate separators. The resistivities of ilmenite, rutile and zircon from a number of Australian producers have been measured by applying a DC voltage across a test sample and measuring the resulting very small current flow. By appropriate design of the measurement cell and attention to the experimental procedure, reproducible resistivity values have been obtained, ranging from 106Ωm for ilmenite to 1013Ωm for zircon. However, the conditions of measurement are radically different from those under which electrical separation takes place. It is not certain that the measured values reflect the resistivities seen under high-tension separation, during which the particles are subject to a high intensity corona field. Consequently, an alternative technique for measurement of resistivity under conditions of corona bombardment has been developed. It is based on the experimental procedure of Castle and Yelle (1979) used to measure the resistivity of fly ash under the conditions occurring in electrostatic precipitators. This paper describes the development of the segmented ground plane measurement surface and a high-voltage switched resistor network which comprises the in situ resistivity apparatus. Results are presented comparing the measurements made under corona bombardment with those made using the DC measurement cell. The equipment has also been used to study the current distribution from a corona wire, as a function of high-tension voltage and wire-to-plane spacing.

Jan 1, 2001

By K. L. Paciorek

The primary objective of this program was to determine the toxic fume and fire hazard of elastomeric noise abatement materials with a limited effort expended on the evaluation of specific treatments applied to mine timbers. Under the conditions employed, for a dimethyl silicone rubber, formaldehyde presented the major toxic threat; acrolein was the main toxic species for both polyester and polyether urethanes and an acrylonitrile-butadiene-styrene resin; in the case of flame-retardant styrene-butadiene rubber compositions, hydrogen chloride, and in the case of PFA-treated timber, furfural, were the major toxic compounds. Of the materials studied, the flame-retardant styrene-butadiene rubbers presented the greatest toxic hazard. The generated data have been reduced to toxic load tabulations amenable to employment for potential hazard assessment.

Jan 1, 1982

Mining is a fundamental activity on which modern society and the world's economy are entirely dependent. Mining investors, large and small, invest on an international scale, frequently being active in several countries.   Prior to committing investment to new countries, the prudent investor will consider the risk involved by analysing a number of physical, financial, administrative and political parameters that impact on the potential financial returns it is seeking. This paper considers these risk factors in relationship to New Zealand and six competitor countries. The conclusion is that for reasons largely within the control of our politicians, New Zealand is a high risk country for mining investors.

Jan 1, 1993

By John J. Deutsch

"1T is a great pleasure for me to be present at the Annual Dinner of the C.I.M.; a pleasure which is combined with a mutual opportunity that I value highly. First of all, this occasion gives me a chance to meet again many Members of your Institute and to become more fully informed of the special problems of the mining industry. This alone is ample reason for me to welcome the invitation to join you tonight. In addition, this occasion provides me with an opportunity to tell you something about the work of the Economic Council which might be of particular interest to your industry.In the mining industry, keen competition and constant change are basic facts of life. The continuing prosperity of the Canadian mining industry depends fundamentally on how successfully it is able to adapt both to the changing conditions within the industry and to major trends which operate throughout the world.First of all, the scale and organization of the industry are evolving to new and different dimensions. As one authority has put it, ""The cream of the small high-grade, easy-to-mine ore deposits of this world have been consumed and mining is becoming more and more an industry of very large scale, complex operations. It has already become in most countries a capital intensive industry and its problems, scientific, technical and economic, are growing in difficulty."""

Jan 1, 1966

By Roger Malmström, H. Heden, Kjell Lidin

INTRODUCTION LKAB was formed at the turn of the century when the railways between the ore fields and harbors were built. The mines are situated north of the Arctic Circle in Sweden. Kiirunavaara is the largest mine, with a pro¬duction capacity of approximately 30 Mt/a. Malm¬berget has a capacity of about 12 Mt/ a. Both are under¬ground mines. Svappavaara, the only opencast mine currently in operation, has a capacity of about 4.5 Mt/a. The ore harbors are at Narvik for the Kiruna and Svappavaara mines and at Lulea for the Malmberget mine (see Fig. 1). Production in the form of finished products is shown in Fig. 2a, b, c, and d. Due to poor ore markets in re¬cent years, production and shipments have been cut back, but there was a positive swing in 1978. LKAB has been 96% state-owned since 1957. In addition to the iron mines in northern Sweden, LKAB has subsidiaries in central Sweden which produce sulfide ores, quartz sand, and uranium (Fig. 3). The mining methods employed are opencast bench stoping at Svappavaara and sublevel caving at Kiirunavaara and Malmberget. GEOLOGY The Kiirunavaara ore body is 4000 m long and av¬erages about 90 m wide, with variations in width from a few meters to around 150 m. The ore has been ex¬plored by deep drilling down to about 1000 m, but mag¬netic measurements indicate a depth of at least 1500 m. The Kiirunavaara ore is oriented in a north-northeasterly direction with a number of ores in the boundaries be¬tween the wall rock types. The ore in Kiirunavaara is mainly a fine-grained magnetite with a varying content of fine-grained apatite. The apatite content of the ore decreases with increasing depth. The other ores are all apatite-bearing and a couple are hematite ores (Fig. 4a, b). The ores are sedimentary, tilted, and tectonically de¬formed. They have a lateral dip of 0.87 to 1.2 rad (50 to 70°). The contacts between ore and wall rock are distinct and sharp, but both the hanging wall and the footwall are brecciated and impregnated with magnetite. The footwall of the Kiirunavaara ore consists of syenite porphyry with a low quartz content and rela¬tively good strength; the hanging wall consists of quartz porphyry. Both types are known as Kiruna porphyries. The ore at the boundary with the hanging wall is often rich in kaolin. There are a few veins of syenite porphyry running through the ore, which has a few major faults (Fig. 4c, d). There are two sharply delineated ore grades in Kiirunavaara: low phosphorus ore with less than 0.1 % phosphorus (about one-third of the ore) and high phos¬phorus ore with greater than 0.5% phosphorus. The iron content is 67% in the low phosphorus ore and 60% in the high phosphorus ore. These ore types are sold as different grades and so are kept separate during mining. MINING AT KIIRUNAVAARA The Kiirunavaara and Luossavaara ores were first mined using opencast bench stoping in 1902. When mining costs rose owing to higher waste removal, under¬ground methods were adopted. In the mid-1950s, the ores were still being mined on the surface at the same

Jan 1, 1982

By Sofia Martins, Anna Lichtschlag, Sven Petersen, Fernando Barriga, Bramley Murton, Adeline Dutrieux

"Sediments in the vicinity of the hydrothermal seafloor massive sulphide (SMS) mounds are characterized by high concentration of metallic particles. They result from a long process of weathering of the primary mineral deposits and have been accumulated in depressions by mass wasting and hydrothermal plume fall-out. We present here the first results obtained on pore waters analyses of such sediments in distinct geological seafloor environments (in low-temperature hydrothermally active zones, on extinct hydrothermal mounds and in a remote depositional channel). Vertical concentration profiles suggest that the pore fluid composition is affected more by seawater circulation compared with hydrothermal fluid flow in all environments. The composition of pore fluids is affected by diagenesis and redox processes in the distal depositional channel where Mn2+ is released at depth with Cu2+.IntroductionMarine hydrothermal fields, hosting seafloor massive sulphides, are potential resources for future deep-sea mining and might become economic reserves for the industries. They are widespread at mid-oceanic ridges, arcs and back-arc spreading centers (Hannington et al., 2011; German et al., 2016). Sediments in the vicinity of these fields can contain unusually high concentration of Fe, Mn, Zn and Cu among other metal elements (Shearme et al., 1983). These hydrothermal, or metalliferous, sediments result from a combination of processes such as collapsing and weathering of chimney material, filling of the channels by turbidite-like mass wasting, in situ authigenic mineralization and hydrothermal plume fall-out (Goulding et al., 1998; German et al., 1990). The sediments contain important indicators reflecting the development of the hydrothermal systems. Because of their widespread distribution and metal content, they themselves can be considered potential mineral resources. Circulation of seawater through these deposits, however, often modifies the sediment composition by oxidizing the sulphides into oxyhydroxides and clays causing mobilization of the metals. To address the importance of alteration and diagenesis of these hydrothermal sediments, including the result of seawater circulation, we investigated the post-depositional processes occurring in the hydrothermal sediments at the TAG Hydrothermal Field (Mid-Atlantic Ridge, 26°N), focusing on the mobility of metallic cations in a number of different seafloor environments."

Jan 1, 2017

By W. James Marold

The New Croton Aqueduct (NCA) was the first major water supply tunnel for New York City. The 50-km (31-mi) long tunnel has 33 open shafts 6 m (20 ft) to 121 m (397 ft) deep. The tunnel and shafts are lined with brick and mortar, with cast iron lining and pressure covers in six pressurized shafts. Details of the 1895 construction are provided and compared to modern construction techniques. The paper provides rehabilitation techniques for the shafts and pressure covers, including grouting, epoxy lining, temporary bulkhead design and installation and placement of tremie concrete 98 m (320ft) below the water level in a 122 m (400ft)deep shaft using a Remote Operated Vehicle (ROV) to monitor the placement.

Jan 1, 2008

Major activities of the Bureau of Mines Explosives Research Center during fiscal year 1966 (July 1, 1965 to June 30, 1966) are reviewed briefly. Part 1 summarizes significant accomplishments of the projects that were active during the report period. Part 2 presents short abstracts of the publications that appeared in the Bureau series and in other media during fiscal year 1966. Publications issued after June 30, 1966, are noted where pertinent in foot- notes but are not abstracted. ACKNOWLEDGMENTS The Bureau of Mines gratefully acknowledges the support given through cooperative agreements by the following organizations to investigations conducted by the Explosives Research Center during fiscal year 1966: Manufacturing Chemists' Association. The Sulphur Institute.

Jan 1, 1967

By J. J. Forbes

First - aid training is an essential part of safety programs in the mining industry , but it is only a means to an end ; first -aid training will not eliminate accidents , but unquestionably it is of considerable value in any accident prevention program . Numerous features should be incorporated in any efficient , well - developed safety plan ; in addition to first -aid training safety work , to be reasonably effective , should include the establishment and maintenance of a safety organization , safety competitions between mines or sections of mines , safety- inspection committees , accident - investigation committees , safety meetings of mine officials , safety bulletins and posters , employees ' safety publications , Holmes Safety Chapters (which provide for monthly safety meetings of all employees ) , and numerous other activities looking to safe operation of mine or plant . These features are supplementary to the fundamentals of safety-- adequate and effective supervision and discipline . Years of experience , however , have demonstrated that first - aid training is a good accident -prevention auxiliary and should be made an integral part of every company's safety program . Many safety-organization plans have failed because they have been based upon the assumption that the supervisory force should be given full authority and responsibility for achieving safety and eliminating accidents and that the workers , who are most vitally concerned , are nonessential . First -aid training causes the employees to feel that they have a personal and full participation in the safety program and is now available so readily that no individual or organization has any valid excuse for not having it . Early investigations made with a view to bettering health and safety conditions among the employees in the mineral industries demonstrated the need of prompt care of injured employees because , under the difficulties inherent in the occupation , seemingly unimportant wounds , when not treated promptly, became infected and caused permanent disability and even death . Many seriously injured persons , brought out of mines and plants by fellow workers who were ignorant of the approved methods of giving first aid or of safe means of transportation

Aug 1, 1934

By Brianna M. Eiter, Jennica L. Bellanca

Mineworkers face a challenging and dynamic work environment every workday. To maintain a safe workplace, mineworkers must be able to recognize worksite hazards while they perform their jobs. Though hazard recognition is a critical skill, recent research from the National Institute for Occupational Safety and Health (NIOSH) indicates that mineworkers fail to identify a significant number of hazards. To further the understanding of mineworkers’ hazard recognition ability and to begin to address hazard recognition performance, NIOSH researchers analyzed data collected during a laboratory research study to determine the effect of individual mineworker factors including risk attitude, work experience, and safety training on hazard recognition accuracy. The results of this study show that mineworker risk attitude and safety-specific work experience affect hazard recognition performance while hazard-specific safety training does not. These results suggest that some of these individual factors can be overcome through experience and training. Potential strategies that can be used to address these factors are also discussed.

Aug 31, 2020

By S Henderson

The Thames gold-silver deposits are part of the Hauraki goldfield, situated within the Miocene to Pliocene calc-alkaline Coromandel Volcanic Zone (CVZ). The Waitangi vein system is one of the mineralised ore shoots in the Thames district. The Thames gold deposits are characterised by shallow level epithermal vein mineralisation with phyllic to advanced argillic alteration assemblages and abundant sulphide minerals including pyrite, arsenopyrite, chalcopyrite, galena and sphalerite. Gold occurs as electrum in association with sulphide minerals. Microprobe analyses.of sphalerite grains from the Waitangi deposit mostly range from 0.8 to 1.5 mole % FeS, although one sample contains 9.5 mole % FeS. Arsenopyrite from Waitangi yields a range from 33.1 to 34.6 atomic As (%). There is no discernible correlation between the FeS content of sphalerite and gold grade in the Waitangi deposit suggesting that gold deposition is probably not controlled by changes in temperature and activity of sulphur aS2 that control the FeS content of sphalerite. The possible causes for gold deposition are thought to be boiling, mixing and changes in pH. Sulphur isotope analyses of mixed sphalerite-galena and sphalerite-galena-ehalcopyrite samples yield a narrow range of d34SCDT values (-1.0 to 0.9 ë;n=5), whereas late spongy pyrite gives unusually light sulphur isotope values (-16.7 to -27.9 ë; n=4). The sulphur isotopic values of base metal sulphides from Waitangi suggest that the sulphur was derived from a magmatic source. However, the source of light sulphur in the late pyrite grains is not known. Preliminary fluid inclusion+studies indicate homogenisation temperatures between 173¦ and 284¦C and salinities of 0.23.0 NaCI equiv. wt % (uncorrected for C02). Vein quartz at Waitangi yields d18OSMOW values from 6.8 to 12.7 ë (n=23). The calculated oxygen isotopic composition of ore fluids is between -2.1 to 3.8 ë at 250¦C and -0.1-5.8 ë at 300¦C. Oxygen isotope analyses have revealed significant variations in d18O values with elevation and gold grades. Zones of gold enrichment coincide with a zone of variable oxygen isotope values at the top of the vein system, where boiling and/or fluid mixing most likely occurred. Oxygen isotope values varying with gold grades within the Waitangi conduits suggest that d18O values may be useful in targeting bonanza grade gold mineralisation in epithermal vein systems.

Jan 1, 1993

The ore treatment expansion programme at Mount Isa Mines required the erection of a new lead-zinc concentrator to be known as No. 2 Concentrator. This concentrator was designed by Western-Knapp Engineering Company in conjunction with staff of Mount Isa Mines Limited. Metallurgical design followed conventional wet milling practice, but the size of many plant units is larger than previously used at Mount Isa. The. total capacity of the new plant is 150,000 tons per four weekly period, and the plant is designed to operate in two equal parallel sections.Erection was contracted on a turnkey basis, and the plant was commissioned as a production unit on 23rd June 1966.The existing concentrator, No. I, was converted to treat all copper ore, and the total capacity of the two plants is now 390,000 tons per four weekly period.

Jan 1, 1968