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Burra was the largest metalliferous mine in Aus- tralia between 1845 and 1860 and employed as many as 1000 men and boys. The workforce was predominantly Cornish, Burra being the first con- centration of Cornish folk in Australia. The sur- face and underground mining operations were typically Cornish and virtually all positions of responsibility were held by Cornishmen. Beam pumping and winding engines were imported from Cornwall and housed in traditional Cornish engi- nehouses. Burra had the first significant number of beam engines in Australia: six were installed between 1849 and 1861. These engines, ranging in size from 20 inches to 80 inches in diameter, were used for pumping, hauling, and driving Cornish roll crush- ers and dressing machinery. Derelict enginehouses of the great beam engines are a striking reminder of former mining activity in Cornwall and South Australia. In South Aus- tralia about 35 enginehouses were erected between 1848 and 1887, of which eight still remain, three of them at Burra (Figure 1). These remain as a tangible link with the Industrial Revolution.

Jan 1, 1987

By Thomas J. Peters

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied a 17,320-acre portion of the 52,143-acre Little High Rock Canyon Wilderness Study Area (CA-020-913/NV-020-008) in order to evaluate its identified mineral resources. The study area is located in Humboldt and Washoe Counties, NV, about 42 miles north from Gerlach. Three areas of epithermal alteration, similar to alteration associated with disseminated gold deposits, were found in the study area. One of the areas occurs along a northeast-trending structural lineament. Southwest of the study area two gold prospects undergoing active exploration, as well JS a gold deposit being prepared for production, occur along the same lineament. The Bureau of Mines examination, however, did not find evidence for gold resources in the study area.

Jan 1, 1987

By O. D. Christensen

The Carlin Trend is a 60 km (38 mi) long northwest alignment of epithermal, sediment-hosted, disseminated gold deposits. Collectively, these orebodies contained more than 620 t (20 million troy ounces) of gold. The Carlin deposit, located near the center of the Trend, has become the "type" deposit of this class. There are, however, significant differences between the individual deposits. Six subdistricts can be distinguished, based upon geographic, structural, lithologic, alteration, mineralization style, and geochemical characteristics. They are, from northwest to southeast, the Bootstrap, Bluestar-Goldstrike, Lynn, Maggie Creek, Rain and Bullion (Railroad) subdistricts. Regional Geologic Setting The Carlin District is located centrally within the Great Basin Geologic Province. Host rocks for the deposits include sedimentary units that range in age from Ordovician to Mississippian, as well as a Jurassic-Cretaceous granodiorite stock. During the Early Paleozoic, the area that is now Nevada lay along the western margin of the North American continent. A westward-thickening wedge of sedimentary units was deposited offshore in a eugeoclinal basin; these vary from continental shelf carbonates toward the east to fine-grained siliceous clastic and cherty units to the west. Tectonic activity associated with the Antler Orogeny in Late Devonian to Early Mississippian time resulted in the eugeoclinal Western Assemblage rocks being thrust as much as 140 km (90 mi) eastward over time-equivalent transitional to miogeoclinal Eastern Assemblage rocks along the Roberts Mountains Thrust fault system. The leading edge of the Roberts Mountains Thrust plate formed the emergent Antler highland from which siliceous clastic sediment, eroded from the overriding eugeoclinal rocks, was shed eastward into the adjacent foreland basin. Erosional products derived from the overthrust plate are termed the Overlap Assemblage.

Jan 1, 1987

A dual rate kinetic model consisting of differential equations is used to describe the kinetics of the adsorption of gold cyanide on activated carbon. The partial differential equation describing the material balance in the liquid phase is written for the special case of a fixed bed system. It is shown that an isotherm for the case of a closed system is required to yield accurate simulations of the equilibrium in a column of activated carbon. Whereas the equilibrium loading of gold cyanide is influenced by the free access of oxygen to the system, the traditional open batch stirred tank experiments, which are used to estimate parameters for the calculation of breakthrough curves for organic solutes, cannot be used here. The program solves this model at incremental heights in the column at a specific future point in time. Runge-Kutta and backwards- difference methods are used in the numerical solution. A Von Neumann method is used to show that the solution is stable. Kinetic parameters can be estimated either from batch experiments or from short column runs. In the latter method the column should not be long enough to contain the concentration wavefront for the system of interest. Results obtained from bench scale continuous column experiments were used to verify the computer model. Pure gold solutions as well as real leach liquor were used in both short column and countercurrent moving bed experiments.

Jan 1, 1987

By T. M. Sukel

Engelhard Corporation is one of the leading producers of kaolin based products in the world, having acquired the assets of Freeport Kaolin company in 1985. Much of the production technology used in the kaolin industry was pioneered by Engelhard and Freeport, including Ultraflotation for improving product brightness, delamination to produce kaolin platelet products, calcination to produce ANSILEX® high opacity titanium dioxide pigment extender and pipeline slurry operations to economically transport kaolin from the mine to beneficiation facilities. Engelhard traces its roots back to 1870 when the Edgar family discovered kaolin behind their property in Bonhamtown, New Jersey. Today the company produces the broadest line of premium coating pigments with extensive sales throughout the world. The international scope of the company's business has led Engelhard to evaluate kaolin deposits throughout the world as possible grass roots production sites. Most kaolin products are used in the paper industry -- the largest volume end-user 80% of the total market -- as filler and coating pigments. Lower volume specialized applications include fillers and reinforcements for plastics and TiO2 extender pigments for paints and coatings.

Jan 1, 1987

By W. H. Su, S. S. Peng

Extensive investigation has been conducted to determine the causes of a series of roof falls occurring in an underground coal mine located in southern West Virginia. Underground observation, along with laboratory testings and finite element analyses, were conducted to search for possible mechanisms for the roof falls. Results of the investigation have led to a better understanding of the mechanisms involved in the roof falls. Necessary modifications of mine layout and roof support plan are proposed for improving safety and profitability at the mine.

Jan 1, 1987

By Anna Szostak-Chrzanowski, Adam Chrzanowski

"New techniques in monitoring surveys and new methods in the analysis and prediction of ground subsidence are being developed in the Department of Surveying Engineering at the University of New Brunswick (UNB). The new surveying techniques include a telemetry monitoring system developed at UNB in cooperation with CANMET, and use of the satellite Global Positioning System. A generalized approach to the analysis of deformation surveys has been developed which permits an integrated analysis of geodetic and geotechnical measurements in geometrical modelling of ground subsidence. A computer program, FEMMA, has been developed for the elastic and non-linear elastic analysis and the deterministic prediction of deformations using the finite element method.IntroductionResearch and development of new monitoring techniques and new methods in the analysis and prediction of ground subsidence in mining areas is an integral part of a broad research program on deformation surveys which is being carried out in the Department of Surveying Engineering at the University of New Brunswick.The research concentrates on:developmentof a general method for predicting deformations with an emphasis on the use of the non-linear elastic finite element analysis; development of a generalized approach to the geometrical analysis of deformation surveys with an integration of geodetic and geotechnical measurements; and development of new monitoring techniques with an emphasis on continuous data acquisition and application of new space techniques such as the satellite Global Positioning System (GPS).This paper gives a brief report on the progress and recent developments within the above program."

Jan 1, 1987

By John Wilson

"The unconformity beneath 75 per cent or over 6000 km2 of the Athabasca Basin in Alberta lies within economically exploitable depths. The basement beneath this unconformity consists of an extension of the Wylie Lake Pluton, locally faulted and containing areas of mylonitic rocks. While the rocks of the Wylie Lake Pluton are not promising host rocks for uranium ore deposits, the areas of mylonites, graphitic rocks and possible remnants of granitegneiss would bear closer examination. One area of maficmylonites shows a weathering zone enriched in Si, Ca, Na, Pb, Ni, Ba, Co, Sr, Zn and U in addition to reported values of 0.08 oz/ton gold. This zone occurs beneath 800 m to 900 m of Athabasca Group sediments, but similar rock types are present beneath much thinner cover elsewhere. Detailed geophysical exploration is required over the area of thinner Athabasca Group rocks to define more precisely the areas of promising basement rock type.IntroductionThe Athabasca Basin in Alberta has considerable economic potential which has not yet been realized. The geological setting is closely analogous to parts of the basin in Saskatchewan which host major uranium deposits. Recent advances in geophysical techniques have led to deposits being located in Saskatchewan below 600 m of cover. This means that the unconformity between the Athabasca Group and the basement lies at exploitable depths over 6000 km2 or 75 per cent of the Alberta portion of the basin. Much of this area was only cursorily examined almost a decade ago. In addition, Alberta's new Metallic Mineral Regulations have clarified the regulatory situation in the area, and opened up much land for exploration. This article is based on Wilson's (1985a) study of the Athabasca Group and Wilson's (1986) work on the basement and alteration beneath the Athabasca Group in Alberta."

Jan 1, 1987

By Steven E. Paulson

In situ mining is emerging as a potential alternative to conventional surf ace and underground mining techniques. A major factor in determining recoveries by in situ mining is the proportion of ore minerals that can be contacted and solubilized by the leach solutions. To provide basic information on the processes occurring during in situ leaching, particularly at the microscopic scale, the Bureau of Mines has developed a geologic characterization research program. This includes laboratory experiments using leaching apparatus that can accommodate whole core samples. Whole core experiments result in higher leach solution-ore mineral contact ratios than packed column experiments, and also allow for the assessment of permeability changes taking place as the result of mineral dissolution, precipitation, and clay swelling within the flow channels in the rock. A nonreactive, reusable reaction cell has been designed and tested. The leaching apparatus can be used for constant-pressure or constant-flow experiments and allows for the control of flow rate, pressure, and temperature during the experiments, thus permitting studies on a wide variety of ore samples. Details of the experimental apparatus and design are presented, as well as preliminary results from the first series of experiments on an oxide copper ore from the Casa Grande, AZ, area.

Jan 1, 1987

By Vladimir Adamek

This paper describes the Bureau of Mines development of a novel subsidence prediction methodology suitable to the mining and geologic conditions in the Northern Appalachian Coal Region. It describes the computation of vertical and horizontal movements, inclination, curvature, and horizontal strains. The substance of this method is the separation of the effects of lithology by introducing a correlation between hypothetically homogeneous overburden and existing lithologic conditions, while providing for different mining conditions, i.e., underground geometry and overburden thickness. The effects of lithology have been expressed in the form of a variable subsidence coefficient within the subsidence trough. The subsidence coefficient is considered a constant for other predictive methods. Field data from 16 test sites at 11 Bureau longwall panel studies were used in the analysis. For each panel, the characteristics of the variability of the subsidence coefficient were defined. Regression analysis of the subsidence coefficients from all test sites on their locations relative to the edges of their respective panels yielded a third-degree polynomial equation. The results from additional longwall panel studies, not included in the regression analysis, were used to prove the validity of this method. To facilitate the use of this precalculation methodology, a computer program was written in BASIC for use on a personal computer.

Jan 1, 1987

By John Berney-Ficklin

Large scale grinding mills can reduce both capital and operating costs for concentrators. These mills can be effectively used, but they must be free from design and manufacturing deficiencies if they are to reach their full potential and avoid costly downtime. This paper presents the evolution of today's complex grinding mill specifications and discusses the most important items to look for when buying new equipment. It emphasizes the need to monitor specification requirements during design and manufacture. It also discusses the growing trend to have grinding mills fabricated in overseas plants, and the importance of recognizing this when preparing specifications.

Jan 1, 1987

By Weimin F

In the last decade, great strides have been made in the raise boring technique in China. Extensively, the drilling and blasting method has been replaced by the mechanized raising method since 1980. There are now over 3C raise drills operating in more than 20 mines. The diameters for shaft boring varies from 500mm to 2000mm, and to depths up to 90m. Tlis paper mainly describes the performance, mtLin technical achievments and applications of all four kinds of raise drills, and auxiliary equipment. Finally, some recommend- ations for future improvement in the raise boring technique are presented also.

Jan 1, 1987

By Lu Jiam Zhang

Coal and gas outburst is one of the serious natural disasters in the coal mines of China. Since 1950, more than 10,000 coal or gas outbursts have occurred in more than 200 underground coal mines of different types. The outburst prone coal mines are widely spread out. It occurs in different types of coal -ma and is very serious in some areas. Most outbursts occurred at the time of roadway driving in coal seam, serious outbursts occurred mainly when entering the coal seam during the cross-cut driving; of the outbursts, coal and gas outbursts We UP major proportion, while pressing out and pouring out ah account for a large proportion; outburst. occur under different operating conditions, but mostly occur during shotfiring. This paper introduces the prevention and control measures as practiced in China and illustrates the three types of outburst cla8sification. Both technology and management are equally important in outburst prevention and control. Measurement of the volume of drilling cuttings and the initial gas outflow rate fm- boreholes have proven to be effective. A special team and organization must be set up to deal with the problems.

Jan 1, 1987

The Abra mineralized body is regarded as a significant new style of mineralization for its environment. It is a blind polymetallic deposit, located in the Bangemall Basin of Western Australia. It was discovered by Geopeko in 1981 by diamond drilling a coincident magnetic gravity target, which revealed a large low grade epithermal Fe-Ba-Pb-Ag-Cu-(AuW) deposit, hosted by chemogenic and clastic sedimentary rocks, overlain by 200-500 m of clastic sedimentary rocks, of Middle Proterozoic age. The mineralization occurs as an upper stratabound phase, and a lower vein "stringer" style phase within a pervasive chlorite alteration envelope.

Jan 1, 1987

By L. B. Phelps

The nation is confronted with thousands of acres of abandoned coal lands. In Pennsylvania alone, these lands have been estimated to cost $15 billion to reclaim (Pennsylvania Bulletin, 1985). One way to deal with this problem is to provide a mechanism by which the active mining industry can undertake to remine certain of these abandoned mine areas. Remining is classified as reaffecting previously mined areas in order td extract the remaining coal reserves while improving the environmental quality of these lands through land restogation and abatement of pollutional discharges. However, there currently is a disincentive for operators to plan to extract reserves on these abandoned mine lands which have preexisting pollutional discharges. Therefore, they presently avoid them. This is because of the "potentially unlimited liability of post- mining treatment for any discharges that would remain after mining? (Pennsylvania Bulletin, 1985).

Jan 1, 1987

By Satya Harpalani

An investigation was carried out to study the microscopic structure of coal in order to understand the phenomenon of methane migration. A Scanning Electron Microscope (SEH) was used to study the surface and pore structure of bituminous coal taken from an underground mine. Micrographs obtained showed the highly porous nature of coal which explains the large quantities of gases that remain within the pores in the compressed and adsorbed forms. These micrographs further showed that most of the pores within the coal matrix are the 'dead-end' type and do not contribute much towards the flow of gas. The most important finding was that solid coal has a network of cracks and fractures indicating that it is these cracks that are primarily responsible for the gas flow, rather than the pores. The size and distribution of the pores within coal influence the capacity of coal to retain methane but movement of the gas molecules is the responsibility of the microfractures. Any mathematical modeling to simulate gas flow through coal must take this into account. For purposes of modeling, the structure of coal can be considered to have dual porosity. First, the gas molecules are released from the pores and there is a gradual migration towards the fractures. Once the gas reaches the fractures, its movement is eased greatly along these fractures.

Jan 1, 1987

By Baynes F. J, Bermingham A. G

The 6000m long King Headrace Tunnel will be driven through hard Owen Conglomerate in the Eastern third and feldspar porphyry in the Western two thirds, with the anticipated hardness up to 350MPa unconfined compressive strength. Since the Commission had not driven a long, large diameter tunnel for some twenty years, major research was undertaken to assess the current tunnelling trends. Tunnel boring machines were compared with drill and fire equipment. Rail equipment was compared with rubber tyred equipment. Tenders were called with tenderers invited to submit alternatives if desired. Commissioning and production excavation using the equipment is discussed with the final conclusion being that the individual items of equipment purchased combined to make an efficient hard rock drill and blast system capable of progressing through all rock conditions likely to be encountered on the King and Anthony Schemes.

Jan 1, 1987

By George G

The Circum-Pacific Map Project is a cooperative international effort to prepare and publish geological, geophysical and mineral resource maps of the Pacific Basin and adjacent land areas. Earth scientists representing 180 organizations from more than 40 Pacific Rim countries are participating in the work. The project is directed by a committee established 14 years ago as an activity of the non-profit Circuin-Pacific Council for Energy and Mineral Resources. Technical and cartographic support is provided by the U.S. Geological Survey. The Circum-Pacific Map Project is organized under five regional panels of experts on the geology and resources of the four quadrants of the Pacific and Antarctica. A series of five 1:10,000,000-scale regional maps and a 1:17,000,000-scale map of the entire Project area, the Pacific Basin Sheet, provide the cartographic base. Forty-eight individual sheets are planned and thirty have been published in eight different series, including base maps, geography, plate tectonics, geology, energy resources, mineral resources, tectonics and geodynamics. Additional special single-sheet thematic maps on the Pacific Basin base have been published and are planned for a total of more than 50 individual sheets.

Jan 1, 1987

By Raczej I, Defant M

Pre-Miocene igneous rocks from the Phili pine island arc are characterised by 87Sr/86Sr and 143Nd/144Nd ratios typical for intra-oceanic island arcs where sediment involvement in the magma genesis was minor. Lead isotopic ratios are similar to Indian Ocean MORB (Mukasa et al., 1986a,b). Pliocene to recent volcanics, however, have more radiogenic Sr and Pb and less radiogenic Nd, except for the volcanics of the Bicol Arc, which have similar isotopic signatures as the Pre-Miocene rocks. We suggest that Pre-Miocene magmas and Bicol-Arc magmas have been generated in response to the subduction of the Philippine Sea Plate, their isotopic characteristics reflecting the composition of Philippine Sea crust. The Bataan arc magmas may reflect the larger amounts of sediments available for subduction in the South China Sea, while magmas of the Mindoro Arc, which are characterised by the most radiogenic Sr and least radiogenic Nd, may have been contaminated by slivers of the Mindoro-North Palawan terrane, which have been carried down to mantle depths after the collision of this terrane and the Philippine arc in Miocene (McCabe et al., 1982). This interpretation implies that Nd (and by inference other REE) can migrate from the subducted slab to the mantle wedge. Thus, variable Nd-isotopic ratios in island arc magmas (e.g. Sunda, Lesser Antillas) may not he a primary feature of the mantle wedge but a consequence of the release of Nd from the subducted slab.

Jan 1, 1987

By M. Guarascio

Microseismic monitoring of mining areas is a developing technique, described here for the Belvedere Spinello Mine, southern Italy, where dissolution cavities in the mining area have proved problematic. The preliminary condition for locating seismic impulses has been found to be a reliable seismic ground model. Ground signals are continuously recorded by means of data from piezometric wells, for sinkhole data, and linked gephones, for microseismic data. A computer system has been implemented to collect, analyse and interpret the incoming signals consequently, identification and classification of hypocentres of activity is facilitated, with advantages in terms of safety, preventing harmful side-effects, including rock bursts, and for environmental conservation.

Jan 1, 1987