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By H. A. Kortmann

Blast furnace operators have been steadily increasing their quality requirements on burden material. These requirements include a high reduction rate of the ore burden as well as good strength at the beginning and during the whole blast furnace operation. Special requirements are made on the softening and melting behavior which ensures an optimal formation of the cohesive zone in the blast furnace. On the whole, the self-fluxed and olivine-based pellets meet these higher requirements due to their chemical composition, especially in the pure pellet operation. In the mixed sinter/pellet operation partly-fluxed and acid iron ore pellets can be appropriately used. The paper describes the demands on, and characteristics of, different kinds of pellets used in the Federal Republic of Germany.

Jan 1, 1989

By A. F. Sidorov

A method of improving mineral recoveries from ores by modifying the physical and chemical properties of minerals using radioisotope radiation was tested. It was observed that irradiation modifies mineral cell sizes, changes the crystal structure of some minerals, reduces the sulfur content 1 to 1.5 % in sulfides, changes the zeta potential, alters the surface properties of mineral grains I and produces other changes. Preliminary tests indicate that accelerated electron treatment of ores in connection with mineral processing has a potential for improving mineral recoveries by flotation and by magnetic separations.

Jan 1, 1989

By H. Zhu

Qualitative and interpretative information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system pro-vides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data.

Jan 1, 1989

By Mao Bai

In predicting the integrity of under-mined structures, surface horizontal displacements and curvatures are frequently of greater importance than the more homogeneous vertical displacements. Accurate evaluation of mining induced subsidence and horizontal displacement further requires that the predictive model adequately represents the subsurface geology, mining geometry and extraction sequencing. The following documents an extension of the Subsidence Prediction and System Identification method (SPASID) to the evaluation of horizontal strains. Comparisons are made between predictions from SPASID and two other empirical methods against measured data from a case study. The system identification method is illustrated to predict horizontal displacements and strains most consistently with the in situ data.

Jan 1, 1989

By James R. Arnold

Gold Fields Mining Corporation started processing ore from it's Chimney Creek operation in northern Nevada in November, 1987. Since that time production has averaged about 200,000 ounces per year from the milling and dump leaching circuits combined. The events that led up to commissioning of the plant started in January of 1985 when the Gold Fields exploration team drilled their first hole in an area now known as Discovery Hill. The major orebody was located later in the year in what is currently the major focus of activity, the North Pit. Subsequent drilling since plant startup has found another 14 million tons of ore two miles south of the original orebody. This South Pit orebody is currently being stripped and metallurgical testing is underway. Engineering Engineering on the Chimney Creek plant started in earnest in May, 1986. Davy McKee Corporation from San Ramon, California, did both the engineering and the construction management. Before engineering began the entire senior staff of the Plant Department was hired and assigned to the project. Senior staff included the Plant Superintendent, Plant General Foreman, Maintenance General Foreman and Chief Metallurgist. Gold Fields does not employ an internal central engineering staff to design their plants. We feel that the people who design the plant should be the ones who will be required to run it once it has been commissioned. This philosophy affords a continuous accountability from start of design through commissioning and operations. All four of the senior staff spent the most critical phase of the engineering stage at Davy McKee, so the plant is truly a reflection of all four disciplines. In bringing on the Maintenance General Foreman from the start, there was a focus placed on ease of maintaining the plant. Another philosophy that was adopted from the start was that the plant be easy to work in and maintain for both operators and maintenance personnel. Numerous design criteria were given to Davy McKee to ensure this. For example, we required that every piece of equipment could be reached easily with a crane or fork lift. All conveyors were required to have walkways on both sides for ease of maintenance and a minimum of 30 inches of clearance under them for ease of cleanup. Visibility for operators was considered very important and the control rooms and general plant layout were designed with this in mind. A list of about 100 general rules were given to Davy McKee during the early layout meetings and these were held as the general design criteria throughout engineering and construction. While engineering was progressing in San Ramon, California, dump leach test work was being done at the site. Three 6 foot diameter fiberglass columns were constructed and filled to a 20 foot height with low grade ore. Leaching characteristics were determined and the dump leach design was based on information collected from these columns. Construction The major contractors on the project were The Industrial Company for the bulk of the piping and structural, EMKO on the electrical/ instrumentation and Hunewill for most of the earth work and leach pad construction. All plant operating and maintenance personnel were employed eight weeks before startup for intensive training. Instructors were Gold Fields personnel, including foremen, and Davy McKee engineers. On occasion, selected suppliers representatives were brought in to discuss major pieces of equipment. Project completion was targeted for January, 1988 at a projected cost of 78.9 million dollars. Actual startup was about 1 1/2 months ahead of schedule and slightly under budget. Full design capacity was achieved the first full month of operation. Crushing Run of mine ore is delivered to the crusher and dumped into a 90 ton hopper which is topped with a 30" X 30" opening stationary grizzly. Ore is fed to a 50" X 60" Telsmith jaw crusher with a 5' wide apron feeder. The closed size setting of the

Jan 1, 1989

By F. L. Wilke

The prototype of an expert system, designed to assist layout planning of face operations, is presented. By specific combination of knowledge-based and conventional EDP techniques it has been possible to extend the known Kepner-Tregoe method up to the determination of mature layout solutions in difficult planning cases. It has been proven that the presented strategy - which can be applied to any kind of problem with similar structure - is apt to provide efficient EDP support for handling complex mining problems. Such support goes far beyond the purely numeric evaluation of envisaged alternatives.

Jan 1, 1989

By Pentti Kallio

From the aspect of economic feasibility of mining, ineffective use of expensive mechanization investments is becoming a problem. In many cases, the machinery is in operation only 50 - 60 % of the total working time. The lost time when the machines are idle means a considerable over-investment in machines. The lost time, with LHD equipment in particular, accumulates from the following constituents: - the needs of the person operating the machine trips to the work site, lunch, coffee and other breaks, want for comfort, etc. - deficiencies in the monitoring and control systems for machine operation waiting periods at loading and unloading stations, unnecessary and erroneous actions, inefficient work, etc. - deficiencies in the machine condition monitoring system , and inefficient service and maintenance work The data transfer and computer technology of today provides means for resolving problems in several areas - including the area of underground loading operations. In the paper those areas of automation and data handling are considered which make possible an improvement in the usage and monitoring of LHD equipment. These fields are: remote control of equipment, use of TV cameras and monitors in remote control, locating equipment and data transfer down the mine, measurement of the load and the data storing system, systems for following the condition of the equipment, unmanned operation of equipment.

Jan 1, 1989

By Siegfried Zell

Preface Pipe heading is a customary and proven technology for the underground installation of all types of piping. In over 90 % of all cases, straight pipe sections are used between shaft constructions since, e.g. this follows roadways or it is necessary from the operational aspect due to pipe control methods, e.g. to use a remote control pipe sensor or comparable control devices within sight from shaft to shaft. Frequently, a straight pipeline is impossible, and is replaced by a more or less spatial alignment due to surface conditions, structures in the ground or foundations. This situation applied for the construction of the Nebensammler Neuland (intercepting sewer) in Hamburg-Neuland for sections IV and V. The following paper is not intended as a description of the complete project. It deals mainly with the special features of this pipe heading, with what I believe to be its somewhat unusual route. The task The building authority design issued by the Main Department for Urban Sewerage of the Free and Hanseatic City of Hamburg consisted of the construction of the collector by a pipe heading using NW 1300 pipes in 2 heading sections. One short straight and one long

Jan 1, 1989

The International Colloquium on Developments in Froth Flotation, which replaced the Annual University of Cape Town (UCT)/University of Stelenbosch (US) Minerals Processing Symposium, was held at the Van Riebeeck Hotel in Gordon's Bay on 3rd and 4th August, 1989. The Colloquium attracted 150 delegates from the mining, metallurgical, and chemical industries, including 9 from overseas.

Jan 1, 1989

By Jon I. Voltz

The U.S. Bureau of Mines has conducted fundamental coal fragmentation studies to evaluate the effects of impact energy and direction of bedding planes on dust generation, size distribution, and impact-output energy relationships. Product size distributions were obtained for the fragmented samples by screening to minus 150 mesh. The minus lS0-mesh fines were analyzed with a light scattering photometer with a measurement range of 176 to 1.9 /.tm. Increased input energy produced a significant increase in the weight of plus 3/8-in material for impact perpendicular to the bedding planes. No significant trend was observed for parallel impact. Impact direction had little influence on dust size distribution, and input versus output energy relationships. As expected, total airborne dust measured at time of impact and percent particulates below 11 /.tm in size generally increased with increased input energy for both directions of impact. Energy used for sample fragmentation increased with increased energy input.

Jan 1, 1989

By Ryan CG, Cousens DR, Suter GF, Griffin WL

A novel method utilizing PIXE with microbeams following fire-assay has been developed to determine PGE and Au at sub-ppm levels suitable for application in exploration. Analyses of the prills from the lead and silver fire-assay yield Pt, Pd and Au concentrations readily. NiS must be used as collector if the complete suite of PGE is required, but this method is not as Convenient.

Jan 1, 1989

By A. Wahab Khair, S. Jung

"This paper deals with the fracturing process of laterally confined blocks of coal subjected to impact indentation. During the test, blocks of coal with approximate dimensions of 10 in. x 10 in. x 6 in. were laterally confined to predetermined equivalent in-situ stresses and then subjected to an impact indentation by dropping coal cutting bits (various shapes) attached to a known weight from a known height. During the test a number of parameters, namely surface strains (using strain gages), penetration depth (using L.V.D.T.) and acoustic emission characteristics were measured. After the test, the fractured surfaces were photographed with the aid of a camera attached to a microscope. The fracture, its intensity and extended zone within the coal blocks were mapped using sonic techniques. By correlating measured parameters, fractured zones under a given set of test parameters were identified and characterized.INTRODUCTION To improve the understanding of basic failure mechanisms in coal cutting, a better knowledge of fracture and crack regions caused by the indentation in coal is needed. This study reports the detailed experimental procedure used in fracture analysis of indentation experiments on coal specimens using the Acoustic Emission (A.E. hereafter) and sonic techniques. The relationship between microcracking and the inelastic deformation of rock was confirmed by a series of experiments in which the A. E. generated by the cracking in the rock specimen were recorded and the number of events were compared to the strain measurement. (Scholz, 1967).According to fracture mechanism theory, crack initiation in brittle materials such as rocks begins from ""flaws"" either pre-existing or induced by the indentation process itself. Rocks are pervaded by natural cracks and pores, from which numerous possibilities for crack initiation arise (Lindquist, Lai and Alm, 1984)."

Jan 1, 1989

By Thomas J. Lien

AMAX Coal Company has constructed the first commercial demonstration sub-bituminous coal dryer at its Belle Ayr Mine south of Gillette, Wyoming. This 215 ton per hour facility is projected to produce 165 tons per hour of dried coal at 10 percent moisture and 10,800 Btulpound (6,000 KCIkg). Approximately 43 tons per hour of water will be removed from the coal and seven tons per hour of coal burned as fuel.

Jan 1, 1989

By Jon C. Volkwein

The U.S. Bureau of Mines conducted a study to assess the impact of a directional water spray system on a unique single inlet dust scrubber on a low-profile mining machine. Tests were conducted in a full-scale model mine using a continuous mining machine. Tracer gas was introduced at the face and concentrations of the tracer gas were monitored at the face and in the return. Various parameters tested included mining position, depth of cut, brattice setback, and combinations of scrubber, and directional or symmetrical sprays. Results indicated that either water spray configuration improved the ventilation effectiveness of the scrubber by a factor of 2 to 3. Average face ventilation effectiveness (FVE) values for all testing of the scrubber and directional sprays were 0.95, versus 0.37 for a standard 20-ft blowing curtain without sprays. No FVE values were less than the standard 20-ft blowing results.

Jan 1, 1989

By Robert A. Jankowski, Charles A. Babbitt, Natesa I. Jayaraman

Today, approximately 31% of underground coal mining operations have designated occupations or areas with more stringent (below 2.0 mg/m3) respirable dust standards in place. Many U.S. coal mines have been able to maintain compliance with very low dust levels, and the Bureau of Mines, in an effort to identify those factors contributing to low dust levels, completed a survey of twelve continuous miner sections which were able to maintain their dust levels at or below 0.5 mg/m3. The quantity and quality of face ventilation appeared to be the most important factor in controlling dust exposure. The results directed Bureau research towards identifying improved face ventilation techniques for reducing quartz dust levels on continuous mining operations. This research has involved the evaluation of a half-curtain face ventilation technique which reduces the cross-sectional area of the entry, thus increasing the air velocity over the operator. The Bureau has also conducted extensive laboratory studies to compare tubing versus brattice, including an evaluation of both systems in a crosscut turn. In an effort to improve ventilation and reduce dust exposures of roof bolter operators working downwind of the continuous mining machine, the Bureau has evaluated two novel face ventilation systems. The first system consists of a fan discharge tubing technique which routes dusty air away from the return entry being bolted. In a technique similar to the fan/tubing concept, exhaust air from the upwind continuous miner face can be scrubbed using a dust collector to capture a portion of the dusty air, clean it, and supply it to the bolter operators as a split of clean intake air. A better understanding of face ventilation techniques should lead to solutions to the problem of more stringent dust standards due to quartz.

Jan 1, 1989

By A. R. Gaba

Phase I of the Canary Wharf development in London's docklands involves the construction of six fifteen storey buildings located predominantly over water of the West India Docks. The buildings are supported on some 1000 No., 25m long, open ended steel tubular piles driven through 10m of dock water to found in dense sand at a depth of about 15m below dock bed level. The piles are of composite section with reinforced concrete within the upper 17m of the steel tube. Three trial piles were installed in the dock to investigate the driveability and performance of the driven steel tubular piles. The piles were subjected to dynamic and static load testing. Loads were applied in both vertical and horizontal directions. Vibrating wire strain gauges were installed on the inside of the steel piles, on the reinforcement and in the concrete to determine the relative proportions of the applied load carried by the steel tube and concrete infill and to establish how these proportions varied along the length of the piles. Inclinometers were also installed to monitor the lateral deflection of the piles. This paper describes the driving, construction and testing of the three trial piles. The results of the vertical and horizontal loading tests are discussed and comparisons are made between dynamic and static tests carried out on the piles.

Jan 1, 1989

By J. K. Szymanski, Val Srajer

In this decade mining companies in western Canada have searched for reliable and inexpensive ways to improve mine productivity. Truck dispatching systems, equipment vital sign monitoring and sensing, vehicle guidance systems, have all been considered. In this paper the off -highway vehicle monitoring systems used or planned to be installed at surface coal mines in western Canada are described. The monitoring systems are divided according to their function and application; installation and testing procedures are described, as well as the economic benefits to the mining operation.

Jan 1, 1989

By G. R. Larocque

"The Loss Prevention Program and management style applied at Kidd Creek enabled them to maintain a 1.02/200 000 man-hours accident frequency over a 20-year period. Falconbridge Limited, Kidd Creek Division operates a major zinc, copper, silver mine, two gold mines and a metallurgical facility in Timmins, Ontario. The metallurgical site and the base metal mine are 17 miles apart and joined by their own railroad. The minesite consists of two shafts, one 3000 feet deep and the other to 5200 feet deep, as well as the necessary maintenance and service shops. The metallurgical site consists of a 14 000 STPD concentrator, a zinc refining plant, copper smelter, copper refinery, and the necessary maintenance shops. The two gold mining operations are adjacent to the metallurgical site.At the time of writing this paper the workforce consisted of some 2500 people divided between the two sites. Nine hundred and ninety-two employees are stationed at the minesite, with the remainder at the metallurgical site and gold mines. The workforce in the Timmins operation is non-unionized and reflects the belief that employee interests are well served.Beside providing competitive wages and an excellent benefit package, Kidd Creek takes special pride in its employee relations practices and continued efforts in communication.In each of the programs referred to, there have been equal involvement by both management and the employees. Each crew, under the direction of a supervisor, makes up its own health and safety committee. To maintain a successful Loss Prevention Program, it is essential that management and the employees work closely together and provide meaningful input and effort to succeed.At this point, refer to the lost time injury frequency as a measure of failure and refer to the opposite end of the scale as the measure of success. The ultimate goal of every operating company is to have a zero frequency, therefore denoting 100070 success. The company uses most of the tangible safety aids found in other mining operations, such as safety posters, safety reminders, check lists, and the use of the Neil George Safety System. The difference is the manner and style of management at the Kidd Creek Division. Their ""open door"" policy and the close association, between management and the employees, has always served them well. Also, at Kidd Creek they believe they have a well-trained and dedicated workforce."

Jan 1, 1989

The achievement of high availability of the Grey River Gold Mining Limited's alluvial gold dredge is a tortuous task which will rely upon the dedication of all staff employed at Grey River Gold Mining Limited (GRGML). The persistent adoption of new technology and better operating procedures, combined with a strong commitment to preventative and predictive maintenance, is necessary. The Grey River Gold Mining Limited alluvial gold dredge is operating in a relatively low grade alluvial gold deposit and hence relies on a high throughput of ore to be profitable. To achieve the required high material throughput the dredge incorporates an overburden removal system which operates simultaneously with a conventional bucketline system.   The overburden system incorporates a cutter wheel and suction pump configuration which is dedicated to removing the low grade (5 mg gold/m3 gravel) overburden. The bucketline conveys the richer grade payzone gravels (up to 890 mg/m3 gravel) to the recovery plant mounted onboard the dredge. The horizon for the overburden system approximates 15 m and the payzone terminates at the interface of the old man rock and the alluvial gravels at a variable depth averaging 22 m.   From a mechanical engineering perspective the dredge is a machine comprised of two materials handling systems which are controlled by Operations Staff and electronic process control systems.   The availability of such a materials handling system is a function of four variables: 1. The environment that the machine operates in. 2. The ability of the people operating the machine. 3. The design of the mechanisms, the configuration that they are grouped in and the effectiveness of the process control systems which control the mechanisms. 4. The procedures utilised to predict the performance of the machines and the skill of staff to analyse that data and carry out effective maintenance.

Jan 1, 1989

By Stephen J. Klein, Fernando Orduz, Randall J. Essex

INTRODUCTION The Keystone Tunnel project consists of widening an existing 7.3 m-wide (24 ft) highway tunnel to a width of 13.7 m (45 ft) to provide a three-lane, two-directional highway tunnel. The 13.7 m-wide tunnel was excavated in a staged drill-and-blast sequence through foliated schist, and was supported using pattern rock reinforcement and shotcrete. Notable project features are: the low vertical cover over the tunnel is less than the span of the opening; the project is the second instance where the Federal Highway Administration (FHWA) has accepted rock reinforcement as a permanent support element; and the project is the first instance where the FHWA is accepting shotcrete as the final interior surface of the tunnel. This paper covers the design and construction phases of the project. PROJECT DESCRIPTION The South Dakota Department of Transportation (SDDOT) retained Woodward-Clyde Consultants (WCC) to evaluate the feasibility, prepare construction plans and specifications, and provide construction management services for the widening of the Keystone Tunnel. The tunnel is located in the Black Hills National Forest area of South Dakota near the southwest corner of the state. The Keystone Tunnel is on U.S. Highway 16A, about 0.8 km (1/2 mile) north of Keystone which is approximately 32 km (20 miles) south of Rapid City (Figure 1). Highway 16A serves as an important transportation link between Rapid City and the Mount Rushmore National Monument which is located about 2 miles west of Keystone. The road through the tunnel consisted of two lanes about 7.3 m (24 ft) wide, and is being widened [ ]

Jan 1, 1989