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By T. S. Golosinski, J. Wolski

Procedures are presented for determining the hourly production rate, mechanical and physical availability, utilization, use of availability, and global performance factors for the bucket wheel excavator (BWE) itself, as well as for the system composed for the BWE, conveyors, and stacker. An example demonstrates the flow of calculations. Using available data from mines that use BWE technology, the ranges of values of the BWE performance factors are presented in tabular form. They can be used as a guide during mine planning as well as to evaluate existing systems.

Jan 1, 1987

By Colin C. West

On August 7, 1986, Barge 45, while being towed near the mouth of the Niagara River, was swept downstream and pinned against one of the central piers of the Peace Bridge. The barge rested against the pier with 125 feet overlying the Canadian border and 50 feet overlying the American border. The tug boat which was towing the barge was lost further downstream. Fortunately, the crew escaped and were rescued with no loss of life. There was serious concern about the potential erosion effects of the river currents on the foundation of the bridge pier as caused by the flow concentrations around the barge structure. Due to the time of year, with the approaching Fall and associated worsening weather conditions, it was imperative that the barge be removed as soon as possible. Donjon Marine of New Jersey, the United States Navy's Atlantic Zone Contractor, was called on to retrieve the barge. By this time the original owner had abandoned the wreck.

Jan 1, 1987

This paper describes an interactive personal computer program, ENVIRON, which simulates cooling and ventilating systems on gold mines. An example of the practical application of the program is given and proposed future developments are discussed. The program consists of two main modules, HEATFLOW and VENT- FLOW. HEATFLOW calculates the heat loads and the effect of air coolers, while VENTFLOW estimates the air flow distribution. As the calculation of the heat loads requires a knowledge of the air flow and vice versa, the two modules are run iteratively until the solution converges. The program is written in Pascal and runs on any IBM-compatible personal computer.

Jan 1, 1987

By W. C. Smith

This Bureau of Mines report discusses how pull-test data can help establish polyester resin column length criteria for roof bolts in evaporite minerals. The study evaluates the effectiveness of partial to full columns of resin in anchoring 4-ft, No.6, grade 40 rebar roof bolts in potash, salt, trona, gypsum, and borate mine roofs. Pull tests were performed on over 600 roof bolts in 11 evaporite mines. Column lengths ranging from 6 to 48 in (fully grouted) were evaluated for each test site. In general, comparative results among all test sites indicate that pull-out loads in excess of 10 tons (force) were attained with resin-grouted bolts having 13 to 75 pet less than a full column of polyester resin. Ten tons (force) of load-carrying capability compared favorably, in terms of strength, with the calculated yield strength of the rebar used in the tests, which was 8.8 tons (force). The site-specific nature of each test site, due to the unique combinations of geology, mine-induced stresses, and other unknown parameters, prevented the establishment of valid generic column-length criteria. For these reasons, data to evaluate resin-column-length effectiveness are best obtained on a mine-specific basis.

Jan 1, 1987

By A. F. van Weele

In general cast-in place piles will have an irregular pile shape. However, it is possible that these irregularities are so large that they may lead to pile deficiencies. It is very rarely possible to examine the pile foundations visually. Also the performance of a static or dynamic load test on each individual pile is not practical and much too expensive. This is the reason why pile integrity tests have been developed: to reduce the risk of inadequate pile foundations by performing a simple test. Pile integrity tests are non destructive tests which are carried out after a pile has been installed. Over the years a number of techniques have been developed of which the most important techniques are briefly described in this paper. Of all pile integrity testing methods, Sonic Integrity Testing is the most widely used method in western Europe. This method has been developed by TNO some 15 years ago. Since then the method has been improved, largely due to advances in micro-processing. A major improvement was made by the introduction of digital signal processing techniques. This made the Sonic Integrity Testing method more accurate (smaller defects can be detected), faster (more than 200 piles can be tested on a single working-day) and more reliable (the results are easier to interprete). A few cases will be presented which will show the usefulness of the Sonic Integrity Testing method. In one of these cases, a helpful tool for interpretation of the results is explained: the Sonic Integrity Testing Simulation program TNOWAVE. Notwithstanding the fact that Sonic Integrity Testing is a powerful method, it has also some strict limitations. These will be discussed at the end of the paper.

Jan 1, 1987

By V. E. Ross

A computer program was developed that incorporates a novel analysis of the behaviour of the froth in full-scale cells to predict the performance of the froth over a wide range of operating conditions. The program has the distinct advantage that it can be easily implemented on a microcomputer, which allows rapid computation and processing of the results. The program utilizes experimental data obtained in flotation-plant and laboratory testwork to provide parameters for the froth model under an initial set of operating conditions. These parameters can then be used in conjunction with a model describing the transfer of material from the pulp to the froth to predict the performance of the cell when its dimensions and operating variables are changed during scale-up.

Jan 1, 1987

By Thompson AG, Cadby GW

The New Austrian Tunnelling Method (NATM) is a proven concept for the safe and economic construction of underground facilities. This is especially true for tunnelling activity where changing ground conditions are often encountered. However, the principles central to the NATM have gained only limited use within Australia, presumably due to the measurement process inter- fering with tunnel driving and the cost associated with instrumentation and interpre- tation expertise. The design and operating principles of two basic instruments are explained together with laboratory simulated test results and suggest- ions for use in an integrated NATM style approach to underground excavation and construc- tion. The two instruments monitor load in rock reinforcement and deformation in rock or primary and secondary linings. The instruments may be fitted with a miniature display module which outputs the measured parameter in engineering units directly. The design of the sensing components allows the instruments to be installed in various configurations suitable for routine performance monitoring, quality control, support element testing or detailed investigations. The display module which reduces the need for instrumenta- tion expertise should suit contractors and allow performance data to be obtained which quickly may be used to modify support procedures to suit ground conditions. When complemented by convergence measurements the devices enable most facets of the NATM to be implemented.

Jan 1, 1987

A critical appraisal of the wide variety of processes used in the pyrometallurgical production of metals and non-metals shows that there is a strong physico-chemical and, in particular thermodynamic, basis for the variety. Based on this, a simple classif- ication scheme has been developed which makes it possible to understand the methods for extracting individual metals and non-metals pyrometallurgically and to assess which are the more attractive routes. The analysis presented shows why there are essentially two broad routes for pyrometallurgical production of metals and non-metals; viz., the reduce- refine and the refine-reduce routes. Halides have the role in pyrometall- urgical processing of producing pure compounds for subsequent reduction. The criteria which determine the selection of reduction method for oxide raw materials and intermediate halides (e.g., use of carbon, hydrogen, a more reactive metal or electrowinning) are examined critically in the paper. The treatment of sulfide raw materials is considered also, particularly the criterion for smelting sulfides directly to the metal.

Jan 1, 1987

By Peter N. Gabby

A mineral purvey of 40,000 acres of the 42,213-acre Little Humboldt River Wilderness Study Area was conducted by the U.S. Bureau of Mines in 1985 at the request of the U.S. Bureau of Land Management. There are no identified mineral resources but anomalous gold, silver, mercury, and arsenic concentrations were found. The study area is located in Elko County, NV, in the Owyhee Upland geomorphic subprovince. It is underlain by mid- to late-Miocene-age rhyolite, basalt, tuff, vitric ash, and tuffaceous siltstone. On the south side and partly within the study area, a mining company recently (January 1986) located 125 contiguous claims over an area of hydrothermally-altered volcanic rocks that have anomalous surface concentrations of gold, mercury, arsenic, and silver. Anomalous gold-silver concentrations in altered rocks were encountered at several other widely scattered localities in the study area. These elevated metal concentrations and associated hydrothermal alteration indicate gold resources may be present in the study area. A 20-ft-thick bed of diatomaceous earth, which contains 60 to 85 percent diatoms, crops out 0.3 mi north of the study area. Elsewhere, three samples of altered volcanic tuff taken within the study area contain from 46 to 70 percent zeolite (clinoptilolite). The diatomaceous earth and zeolite sampled are not of sufficient quality to compete with materials presently being marketed. There has been no mineral production from the study area, but a caved adit, about 25 ft long, and six prospect pits were found.

Jan 1, 1987

By Sowerby BD

The CSIRU Division of Mineral Engineering is developing various techniques for the on-line determination of moisture in coal and coke, and some instruments are now commercially available. These techniques permit accurate and rapid determination of moisture in materials directly on conveyor belts or in bins. The most promising techniques for direct on-belt measurement of moisture in coal are capacitance and microwave transmission. A non-contacting under-belt capacitance and gamma-ray backscatter technique has determined moisture in coal to better than 0.5 wt'/. in field tests at BHP Stockton Borehole Colliery, NSW. Mineral Control Instrumentation Pty Ltd have been licensed to manufacture the capacitance gauges and have installed five commercial units in the coal industry and other industries. Microwave transmission techniques have an advantage over the under-belt capacitance technique in that they are not sensitive to vertical segregation of moisture in coal on the conveyor belt. A laboratory prototype of a microwave transmission gauge has been constructed and tested. Microwave techniques, based on a measurement of attenuation and phase shift, are under development and are expected to be field tested in 1987. These new techniques will enable a wide range of thickness changes to be accommodated. Capacitance and microwave transmission methods are unsuitable for materials of high electrical conductivity, such as coke. CSIRO is therefore developing a fast neutron and gamma-ray transmission technique, which is proving very accurate in laboratory tests. This technique overcomes many of the limitations of thermal neutron moisture gauges and it is expected to be field tested in 1987.

Jan 1, 1987

By T. H. Bagan

The Sixteen-to-One Mine was originally designed and operated using Blasthole Stoping with end slicing as the primary mining method. This method changed to Modified VCR Stoping in response to efforts to control dilution. The new method combines Blasthole Stoping with shrinkage methods, pillars, and reduced sublevel intervals to provide the most practical dilution control avail- able for low cost bulk mining.

Jan 1, 1987

By Ron Robinson, Trevor Harrison

The planning, installation and commissioning of the first scheme of controlled recirculation of air flow in a section of coal mine in Great Britain is described, together with the proposals for a second installation. The work updates a previous paper (Robinson and Harrison, l986) on the subject. The special problems of ventilating the increasingly distant faces of the undersea mines in the North East Area of the British Coal Corporation are discussed and the alternative solutions stated. The advantages of using a system of controlled recirculation of air are proposed together with the safety features considered necessary. Design and installation details of the recirculation fans and a new booster fan are described.

Jan 1, 1987

By A. Sainato, S. J. Kravits, G. L. Finfinger

This report describes a project conducted by the Bureau of Mines in which the accurate directional drilling of a borehole was demonstrated with the objective of intercepting a designated target. The project was conducted at Navajo Dam in northern New Mexico at the request of the Bureau of Reclamation. Borehole survey and drill logs are provided in an appendix. The trajectory of the demonstration borehole was designed to intercept a 5-ft-radius target at the final or "punchout" distance of 885 ft. The elevation of the borehole at this distance was within the target; the borehole punchout coordinates were 8.81 ft southwest of the target. As a result of the demonstrated accuracy, the Bureau of Reclamation has contracted the accurate drilling of boreholes as long as 600 ft from the inside of a short tunnel, to control water seepage in the right abut- ment. This resulted in a substantial cost savings compared to the orig- inal plan of constructing a longer tunnel and drilling 150-ft boreholes.

Jan 1, 1987

By D. S. Cavers

INTRODUCTION This paper discusses aspects of rock engineering applicable to surface gold mines. Discussion particularly centers on areas in which rock mechanics can enhance the mine productivity or profit- ability. Methods of analysis are discussed briefly but for more detai1s the reader is referred to the appropriate references. A team approach to the overall design of the pit generally pro- duces a better result at an overall lower cost. In particular, money is wasted by asking for a "report on slopes" and then input- ting this slope angle into a pit design and economic analysis study without further reference to the geotechnical engineer. Pit slope angle depends on slope orientation, location, pit shape, pre-existing discontinuities and mining methods. Preliminary slope angles can be produced but optimization depends on ongoing inter- action between the mining engineers, geologists and geotechnical engineers. This interaction can a1 so substantially reduce overall design time which may be critical in bringing remote plays into production. Most surface gold mines in North America are in igneous or metamorphic environments. Rock mechanics aspects discussed in this paper will be discussed with reference to these environments al- though most of the principles and comments are applicable to sedimentary environments as we1 1.

Jan 1, 1987

By Garg R. K

Himalayan ranges on the northern border of India are source of many perennial rivers and suitable sites for large dams have been located therein. However, Himalayas are young mountains and comprise of comparatively weaker rocks having adverse geological features like shear seams, thrust zones, minor and major faults and intense jointing. Tehri dam project under construction, is located in lower Himalayas. It envisages construction of a 260.5 m high earth and rock fill dam and an underground power station of 2000 MW (Eight machines of 250 MW each, four of which will be reversible) installed capacity. This dam will be the highest and the underground complex will be the largest to be constructed in India in the Himalayas. The under- ground complex comprises of 25 km of tunnels varying in diameter from 6 m to 11 m and seven large cavities of various sizes, the biggest being 22 m in width, 194 m in length and 65 m in height. Rock formation in the power house complex belong to phyllites having various joint sets spaced from 0.5 m to 3 m. Due to the poor geological conditions and closely spaced net work of large cavities, the planning, analysis and design of the cavities is a challenging job. Many aspects have to be considered in determining the sizes, locations and orientations of the various cavities taking into account the properties and jointing pattern of rock mass, functional requirements and economics. Correct evaluation of loads and forces is necessary for economical design of supporting system for the various cavities. Rock loads on the roof of cavities and their supporting system will be assessed with the help of the latest methods. The stability of the rock mass around the cavity will be evaluated by elasto- plastic method using finite or boundary element techniques. A scheme of field investigations, laboratory tests and instrumentation for deter- mining rock properties in preconstruction stage and for monitoring behaviour of the underground cavities during and after construction is envisaged.

Jan 1, 1987

The elements of consistent structural de sign models for underground structures are explained. Such models should comprise at least ground properties, excavation and support methods, computational models for analysis, failure hypotheses, and in-situ monitoring. The fundamental characteristics of the interaction between ground and support are investigated. Then, plane strain models for soft ground tun- nelling and design models for rock tunnelling employing stress release at the tunnel face are elaborated. Some numerical evaluations are gi- ven in diagrams, comparing approaches of dif- ferent authors. Comments are presented on nume- rical three-dimensional models (visualized by structural models for mining in rock salt), on the interaction of in-situ monitoring and design, on structural safety for underground structures, and finally on the general develop- ment of structural design models in geo- Techniques.

Jan 1, 1987

This paper briefly discusses the negotia- tion of the more important provisions in agree- ments for exploration and mining rights with Pacific countries. LAND RIGHTS Land rights are complicated and sometimes controversial in many of the Pacific countries. In some countries, a company will have to deal with land owners directly; in others, the government will act as intermediary. Inevit- ably, a company will have to deal with both. Mining companies need to be sensitive to the culture and particular interests of the land owners and of their history in defending their rights. The issues are too complicated to be dealt with here. Some mining companies have spent, and will continue to spend, considerable time trying to understand them. It will " require patience, perseverance, sensitivity and unflagging optimism. The better advised companies will ensure that their local repre- sentatives get to know the land owners, under- stand their concerns, and will pursue a policy of keeping them informed on a regular basis of all of the company's activities and proposed activities. Good community relations are the keystone for good mining operations in the Pacific. Most countries will require the submission of an environmental impact statement so that they will know in advance what effects a pro- posted mining operation are expected to have on the environment and how it is intended to deal with them. They will also want to approve the company's environmental reclamation and rehabilitation plan. Let's face facts right away - mining, by its very nature, is not going to improve the environment. There will be waste discharges, emissions and deposits. They will affect the land, air and water and hence human, marine and animal life and vegetation. There will be sounds and odours and the esthetics of mining operations, though perhaps pleasing to geolo- gists and mining engineers, will not please Others.

Jan 1, 1987

By Dennis P. Bryan

The southwestern United States has an abundance of natural lightweight aggregate (NLA) deposits of volcanic origin that are being used in the construction industry within the region. New Mexico, Arizona, Nevada and California utilize NLA in portland cement concrete and concrete masonry units for weight reduction and related economic reasons. The geological environment of the western United States is amenable to the occurrence of natural lightweight rocks because it contains Tertiary and Quaternary volcanic products that include low-density glass and vesicular material. There are two major classical types of natural lightweight materials of igneous origin; pumice and cinder. These account for the vast majority of volcanic rocks that are presently utilized as NLA. Pumice is an ejecta product generally found as part of tuffaceous units associated with nearby siliceous volcanic centers. Cinder, also an ejecta product, is associated with mafic volcanics and is most often found as a cinder cone. Both are highly vesicular. A third type of natural lightweight material, though also associated with siliceous volcanics, is less vesicular than pumice. It is best described as being a slightly pumiceous rhyolite or rhyolite-tuff breccia that occurs as a siliceous dome or tuft unit that is most likely to be glassy. Uses of these natural lightweight rocks center on the construction industry where they are utilized in lightweight portland cement concrete and lightweight concrete masonry units. The major reason for usage in portland cement concrete is cost saving effected by weight reduction in high-rise construction. The major usage in concrete masonry units, or "block", is for weight reduction that enables a mason to lay more lock.

Jan 1, 1987

By S. P. Singh

Destress blasting is commonly used in the mines to minimize the occurrence of rockbursts. The fracturing created by destressing in the vicinity of the face reduces the stress concentration by pushing the zone of high stress deeper into the rock mass. But the destressing practice by blasting may be devastating near the faults or other sensitive high stress zones. To avoid severe rockbursts in such situations, the application of chemical destressing has been proposed in this paper. A laboratory investigation was conducted on the rocks in the Sudbury basin to examine the change in the material properties with an aim of assessing the feasibility of destressing by chemical means. The favourable change observed in the rock properties led to the suggestion that the injection of surfactants in boreholes would enhance fracture propagation similar to what is currently done by blasting but in a safer, inexpensive and non-violent manner. The current destressing practices in Ontario mines have also been reviewed in this paper.

Jan 1, 1987

By A. Mcdonald

"An X-Met Analyzer was purchased from Outokumpu in late 1983for use in the Hudson Bay Mining and Smelting smelter. Its first use was in the fuming plant to give zinc assays of each charge of slag tapped from the fuming furnaces. This quickly told the operators exactly when each charge had reached its economic tap-out point, and gave supervision a fool-proof method of identifying good operation. These and other factors led to major improvements in coal utilization in the fumers and to major increases in zinc oxide production. A second unit was later purchased for the reverberatory furnace to give silica and iron assays of the slag, and these were used to make adjustments in the feed composition to maintain the desired SiO2:Fe ratio in the slag. Since purchasing the units for the furnace, the oil consumption and copper content of the slag have dropped significantly. IntroductionSmelters have lagged far behind concentrators in process control by mean s of rapid product analysis. The on-stream X-ray analyzer was developed about seventeen years ago, and soon concentrators around the world were getting assays of the incoming ore, .concentrates and tailings every fifteen minutes, and using these to control reagent additions and other process variables. Almost always, the concentrate grade and recovery improved.In smelters, product streams are solids or molten materials, not the more easily handled slurries, and until seven years ago no inexpensive equipment was available to provide rapid analysis of this type of material. In approximately 1980, several companies developed instruments based on irradiating solid samples with low-intensity gamma rays from radio-isotope sources, and measuring the secondary X-rays emitted from different elements in the sample to provide an analysis of the elements desired.The smelter staff had a close look at what was needed and listed the following points as being critical:1. ability to provide Zn assays of a sample of slag within 15 minutes of taking it, in order to achieve optimum fuming times (zinc fuming , being a batch process, had the greatest potential benefit from rapid slag analysis);2. ability to give Cu and Fe assays on the slag, and on other smelter products, such as matte and converter slag;3. ability to give Si02 assays since the SiO2 content of the slag has a strong effect on fuming rate; and4. ability to stand up to an industrial atmosphere such as exists in the fuming plant."

Jan 1, 1987