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By Ian McFeat-Smith, Robert J. Fowell

Roadheader machines have a specific place in modern tunnelling, not simply as a compromise between drill and blast techniques and full face machines, but as an economic and versatile form of mechanised tunnelling where the method of excavation is easily integrated with tunnelling operations. In the past, roadheaders have been subjected to misuses by engineers who failed to realise that, as in all mechanised tunnelling, a planned and systematic approach is essential if the full potential of these machines is to be gained. An increasing awareness of this, together with the introduction of the more powerful roadheader carrying their cutting potential into the hard range of rock is changing this situation and now makes the prospect of using roadheaders particularly attractive (1). The advantages gained by employing these machines can be considerable and Table 1 lists some of them. This table illustrates that from both cost, and installation points of view, the roadheader has considerable benefits over the full face machine. However, the principal advantage gained is in broken ground where heavy supports can be installed immediately at the tunnel face. In addition, access for planned maintenance and repairs to most working parts of the machine is at a premium and average machine utilisations of 40 - 60% can be expected. In comparison to drill and blast methods, up to 40% better progress can be regularly achieved, and the subsequent savings in overbreak costs alone would more than pay for the cost of a roadheader used to drive a 3km long tunnel. As with full face machines, ground disturbance is minimal and for short tunnels in urban areas a road-

Jan 1, 1979

By Marion A. Goudie

The Devonian salt basin, which contains the Saskatchewan Potash deposits, extends from just east of the foothills in Alberta, north as far as the Peace River area, across Saskatchewan and into Manitoba as far east as Range 10 west of the First Meridian and south into Montana and North Dakota. The basin is closed everywhere except to the northwest. The known potash deposits are confined almost entirely to the Province of Saskatchewan, with the exception of a small area in western Manitoba bordering the Saskatchewan boundary. The following discussion will concern only the Saskatchewan part of the basin. The evaporite series in the basin is defined as the Prairie Evaporite Formation of the Elk Point Group, of Middle Devonian age. Recent work done by potassium-argon dating methods has indicated an Upper Middle Devonian (Givetian) age of from 265 to 347 million years for the potash. The Elk Point Group consists in ascending order of the Ashern, Winnipegosis and Prairie Evaporite Formations. The Ashern formation, sometimes called the Third Red Bed, consists of dolomitic shales or shaly dolomites. The Winnipegosis is a reef type dolomite, usually with good porosity, and in many cases oil-staining, although to date no production has been obtained. The Prairie Evaporite formation consists of anhydrite overlain by halite and finally, in Saskatchewan, by the potash beds. In almost all wells which have been cored for potash the lowest potash bed is underlain by one or two bands of anhydrtte, which are used as marker horizons. Cores from a few wells which cored to the bottom of the salt series have shown flecks of potash throughout the halite.

Jan 1, 1959

By Karl H. Bruemmer

1. TRENDS OF DEVELOPMENT IN THE MECHANICAL DRIVING OF UNDERGROUND EXCAVATIONS IN THE GERMAN COAL MINING INDUSTRY The demand for higher advance in underground excavations led, in the past ten years, to the development and application of various mechanical methods in the coal mining industry of the Federal Republic of Germany. Hence, a modern mine cannot operate anymore without tunneling machines for the driving of horizontal and inclined roads and shaft boring machines for the sinking of shafts. In future, boring operations will assume a high positional value in the mining industry, as the development of cutters has kept pace with the development of machines. In the past ten years, about 40 km of roadways have been bored by tunneling machines in the German coal mining industry, further 140 km will be bored by 1990, part of which are already under contract. The idea was tempting to apply the technology of horizontal tunnel borers also to the sinking of vertical shafts. The underground contractors Deilmann-Haniel GmbH of Dortmund and Thyssen Schachtbau GmbH of Mülheim/Ruhr developed already in 1970, together with Wirth of Erkelenz, a shaft boring machine working without drill pipes, capable of sinking shafts following a pilot borehole, according to the downward reaming method (Fig. 1). In the meantime, two such shaft borers are operating in coal mines with diameters of 4.50 m to 6.50 m. Recently an order was placed for a third Wirth shaft borer for diameters up to 8.50 m. Since 1971 about 3.800 m of open or blind shafts have been sunk by the reaming process (Fig. 2).

Jan 1, 1979

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

By Roy H. Werner

The environmental demands on the mining industry coupled with rising production costs have created a need for a low cost sludge removal system. The HYDRA* system meets these demands by offering a unique means of removing settled solids from the bottom of a clarifier or a thickener. This underflow system combines experience and proven concepts to form a low cost sludge removal system. The HYDRA system incorporates a flexible design that can be adapted to any settling area. The components are readily available and cost less than a conventional clarifier or thickener. Existing technology developed by preparation engineers provides for retrieval and recovery of mine preparation plant refuse. However, past retrieval methods have been extremely costly. The HYDRA system, because of its low cost, makes the complete process of retrieval and recovery economically feasible. This allows wasted resources to be converted to a saleable product.

Jan 1, 1975

By J. W. T. Ropkins, D. Allenby

The paper describes a technique by which large concrete boxes are unobtrusively inserted beneath existing highway and railway infrastructure to form new subways, culverts and under-bridges, thus avoiding the inconvenience and costs of disruption to traffic associated with traditional cut and cover techniques. A series of project examples, undertaken in the United Kingdom and United States, are used to illustrate the design and construction of the box structures, together with the technology required to control ground disturbance in the tunnel face and around the box, and the jacking systems necessary for box installation.

Jan 1, 2003

By James E. Breland

Society's growing concern over the number of deaths and serious injuries occurring in coal mines, coupled with a growing sentiment to develop and promulgate improved mandatory health or safety standards, was no doubt the basis for passage by Congress of the Federal Coal Mine Health and Safety Act of 1969, being Public Law 91-173 approved December 30, 1969. Even prior to passage of the Act, strong reaction was quick to arise concerning the effect of such legislation upon the coal mining industry. Initial response varied from mild forms of criticism to' the expressed fear of complete suspension of operations and mine closings. Primarily responsible for these early forms of skepticism were speculative or fanciful cost estimates which led operators to contemplate a less than prosperous existence. However, in spite of this unfavorable outlook, the majority of the operators have faced up to the situation and have been striving to comply with the Act and the regulations issued thereunder. While encouraging strides have been made toward implementation of the Act, it must be recognized that noticeable results have been attained only through many months of determined effort and, as anticipated, at quite heavy expense to the operator.

Jan 1, 1973

By William P. Shell

An important part of process control engineering is the implementation of the basic control system design through commissioning to routine operation. This is a period when basic concepts can be reviewed and improvements either implemented or recorded for application in future systems. The experience of commissioning the process control systems in the Homer City coal cleaning plant are described and discussed. The current level of operating control performance in individual sections and the overall system are also reported and discussed.

Jan 1, 1983

By Kailash Narayan

Atlantic Richfield Company began operating a commercial uranium solution mining project in April, 1975 in Live Oak County, 10 miles southwest of the town of George West (Figure 1). The operation is designed to produce 250,000 pounds of U303 per year and is jointly owned by Atlantic Richfield Company, Dalco and U. S. Steel. The proprietary process employed in this operation consists of injecting an alkaline leaching solution into the ore-bearing formation through a pattern of injection wells. The uranium-bearing solution is then removed through producing wells using submersible pumps in central production wells. The produced solution is pumped through a pipeline to the plant area where the uranium is extracted. The barren solution is refurbished and returned to the pattern area for reinjection. The injection field and plant site are located in the drainage of Spring Creek, a small intermittent stream tributary to the Nueces River. Land use in the area is primarily agricultural -- cattle ranching and farming -- but several producing gas fields are present in the areas as well.

Jan 1, 1976

By John J. Mulligan

Coal is found in every major geographic region throughout Alaska and in two offshore areas. Since about 1852 over 100 small mines have opened and closed. Last years production was almost entirely from one mine in central Alaska. Clearly the utilization of Alaska's abundant coal resources presents political, economic and technical problems that are far from solution. Location and Physical Features Figure one illustrates the geographical and geological similarity between Alaska and western United States. The Arctic region of Alaska generally resembles Wyoming and the Dakotas. The Brooks Range is an extension of the Rocky Mountains. The Central region of Alaska between the Brooks Range and the Alaska Range bears a general resemblance to the basin and range country of western United States. The Southcentral and Southeastern regions has a similar resemblance to the Sierra Nevadas and the west coast of the United States.

Jan 1, 1982

By Rubén Pavón] [H.

Mexico, that for various years held the second place among the elemental sulphur producers in the world, now occupies the fourth position. Nevertheless, taking advantage of the recent increase in the international prices of the metalloid, it is expected that Mexico recovers its traditional position producing, for the first time, over two million tons of sulphur during 1974. Drawing from material stockpiled during the last years sales are expected to reach 2.5 million tons, at excellent prices in the foreign markets, but not so in the domestic ones where prices have remained practically static since 1955, in spite of substantial escalation of production costs. Of the two sources of elemental sulphur in Mexico, the frasch process extraction from the salt domes of the Tehuantepec isthmus where the most important reserves are located - is the one that shall have an important increment. An increase of production of lesser magnitude is expected from sour gas, since sulphur recovery plants wilI go on stream toward the end of the year in the new oil fields recently located in the State of Chiapas. Two Mexican corporations are expanding and improving rational Frasch extraction operations. Together with Petroleos Mexicanos' sulphur recovery from sour gas it is estimated that production during 1975 shall reach 2.5 million tons and, consequently, supply the domestic market and generate an important sum of foreign currencies.

Jan 1, 1974

By Dennis A. Fenton

This paper presents some techniques and data required to design large ball mills. The advent of larger size mills leads to consideration of the gearless drive as a practical solution to utilize large horsepowwers. The particular shell structure under consideration is subjected to thermal as well as magnetic loads. The magnitude of the inertia, magnetic and shell temperature characteristics have a very significant effect on the design and performance of the hydrodynamic pivoted shoe bearing. Particularly since these bearings have lower frictional resistance properties than hydrostatic trunnion tee rings. The structure of the mill is designed for long life. Parameters involved with the fatigue life of the structure are discussed together with some of the more important aspects of the design.

Jan 1, 1975

By Alan Bye

Sandsloot open pit is situated on the northern limb of the Bushveld Complex, 250 km north east of Johannesburg, South Africa. Sandsloot is currently the largest open pit platinum mine in the world and is one of six potential open pits in the area. The geotechnical strength properties of the Platreef have posed significant mining and processing challenges to the PPRust operation since inception in 1992. In order to optimise the whole business as opposed to isolated cost centres a mine to mill initiative was embarked upon in 1997. Initial work focussed on ore characterisation and an entire suite of data was collected for each rock type. This included mineralogy, geochemistry, geotechnical, blastability indices as well as metallurgical strength data. The second phase involved the clear definition of customer requirements, namely the optimum performance criteria for the plant and mining departments. This involved extensive field trials and data capture to measure the interaction and influence of the mine to mill value chain. Once the design targets were defined a 3D geotechnical model was constructed to ensure that the targets were consistently achieved. The model is very similar to an ore reserve model however it is populated with geotechnical, metallurgical and blast index data. Through software queries the appropriate blast powder factor for each mining block can be obtained thereby ensuring the correct fragmentation is blasted for the plant and mining operation. The initiative has delivered significant results showing improvements across the mine to mill value chain. These include increased loading rates, reduced electricity and crushing consumables as well as higher plant throughput. Additionally, the initiative has benefited both Brownfield and Greenfield projects on the PPRust operation.

Jan 1, 2005

By Anil Kumar

In underground mine production units that employ discrete-vehicle face haulage, feeders are used in the belt network so that vehicles can unload rapidly without transmitting to the conveyor network the high material flow rates that result from rapid unloading. They prevent production bottlenecks at the face, while reducing capacity requirements for downstream materials handling equipment. Similarly, surge bins may be installed at intermediate locations in the network to smooth flows from a number of upstream sources, thereby reducing downstream belt capacity requirements. This paper introduces new stochastic process models to temporally describe loading patterns from unit operations and techniques for computing the probability of various fill levels for the feeder or surge bin. These results may be used to analyze the effect of alternative bin or feeder capacities and discharge rates on the performance and costs of the materials handling system.

Jan 1, 1994

By W. F. Mullen

Within the scope of this discussion, artificial dimension stone is defined as any manufactured product used as a substitute for natural dimension stone. The history of the development of these substitute materials is reviewed briefly, representative characteristics of each product are listed, several analyses of their market position are presented, and suggestions are made for recapturing markets lost to these products and preventing additional inroads.

Jan 1, 1959

By G. V. Henderson

Limestone and Dolomite quarries located near Salto-De-Pirapora, Arroia Grande Gaucho, Conde Francisco and Candioita probably represent the closest, major sources of high quality lime and cement grade carbonate rocks to the major population center of Sao Paulo Brazil. The nearest major city to most of the limestone - dolomite sources is Sorocaba and Palma. All of the mining properties visited during this study are located in the state of Rio Grande Do Sul at approximately -32 degrees south latitude and -52 degrees west longitude, southwest of the major port city of Porto Alegre.

Jan 1, 1981

By Lynn B. Hales

Everywhere you turn today there are articles on artificial intelligence and the rapid emergence of expert systems. Expert systems form a class of software that has developed as a result of the large research effort to develop computers and software that think intelligently. By definition, an expert system is a computer program that contains the knowledge component of an expert skill, can offer intelligent advice and justify its line of reasoning. Expert systems can advise people on what actions to take and when, assist in the diagnosis of the physical condition of a human patient or piece of equipment, or even take actions without human guidance, as in process control applications. Expert systems can also explain the line of reasoning behind a particular piece of advice or query for information from the user. Expert systems can be used as advisors to newcomers in any field in which mastery is attained by many years of experience. They often can provide expertise more uniformly and rapidly than human experts. Expert systems can also provide a means of documenting expert knowledge and procedures and provide a common repository for a changing knowledge base. The expert system can represent the best expertise available, thought out in the absence of pressure situations. Each of these attributes or characteristics should be helpful in improving typical concentrator control systems.

Jan 1, 1987

By C. J. Gauvin

The Geological Department, headed by the Chief Geologist, is part of the General Engineering Division and is under the direct supervision of the Chief Engineer. The Geological Department is responsible for the technical direction of all work concerned with the finding and outlining of ore. It provides the mine operating staffs, with the necessary plans and sections to enable them to design pit and underground layouts and to, extract ores' as required by outgoing cargoes. The department maintains grade and ore reserve statistics in conjunction with a mining recovery factor at year-end. These duties are performed through the co-operation of all departments participating in the overall operation. As a result, a steadily broadening use is being made of geology at Steep Rock.

Jan 1, 1960

By Robert C. Salak

The era of low-seam mining with continuous haulage has been here for quite some time. Typical tonnages in companies such as Terry Glenn Coal are currently averaging 405 tonnes per shift in .8m coal. JoAnn Coal has averaged 453.6 tonnes per shift in .775m to .825m coal for the past four years. John Chaney of Chaney Coal has averaged 297 tonnes per shift in .6m to .65m coal. There are many other mines that are experiencing similar success and with maintenance costs that are averaging $.10 to $.40 per tonne. These figures have been documented and can be verified by the operators.

Jan 1, 1981

By C. A. Rowland

Autogenous grinding, defined as grinding with like material, while quite an old art has recently been revitalized. Two phases of autogenous grinding, primary and secondary, have been the subject of recent papers, technical articles and discussions. The purpose of this paper is to discuss a third phase of autogenous grinding - Intermediate Autogenous Grinding - comparing it to and indicating advantages over the other two phases. Autogenous grinding can also be called ?Rock grinding?1; that is, grinding using ore or rock from the same deposit as the mill feed as grinding media contrasted with using as grinding media steel rods, steel or ironballs, natural or manufactured iron, free pebbles, or other shapes and materials foreign to the mill feed.

Jan 1, 1964