Search Documents

By A. H. Harvey, M. Delangen, A. D. Fernie

"A large-scale expansion to Pacific Coast Bulk Terminals Ltd. has now been completed and placed in operation. The original plant, built approximately eight years ago, consists of the direct rail-car to ship transfer of bulk commodities. The extension includes additional rail-car unloading, a transfer house system for directing commodities to storage or ship, major storage and reclaim facilities, a second shiploader and a second deep-sea berth. In addition to the facilities for overseas shipments, a wood-chip loader and a barge berth have been installed for domestic shipments of wood chips and, occasionally, for other local commodities. The design considerations imposed by the nature of the products to be handled are covered in this paper."

Jan 1, 1969

By M. R. Geer

Three coals from the Wilkes on - Carbonado district of Pierce County , Washington , were subjected to washability analyses to estimate the amount and quality of washed coal obtainable . Because the coals were unusually difficult to clean , the washability examinations were supplemented by table tests , tests in dense - medium cleaning units , and flotation tests . None of the coals could be reduced to the desired 10 percent ash by tabling and the response to flotation by two of them was poor . Dense -medium treatment provided coal of the desired quality , but with the most difficult coal the recovery efficiency was lower than usual .

Jan 1, 1964

By David J. Selleck, Eugene P. Pfleider

9.61. Introduction. Open pit mining methods produce more than 80% of all raw materials today in the United States. Much of this comes either from properties that formerly employed underground methods and were converted to open pit or from mines that ultimately must go underground when the economic stripping limit is reached. Generally the ores are transported over large vertical distances and techniques have been developed to do this economically. One approach is to combine conventional surface trucking, over relatively level roads, with the use of gravity and underground facilities. There are various modifications, depending upon the character of the orebody and the topography. Several schemes, as used in Sweden, Canada, and the United States, merit describing. One of the critical problems involved in the transference of ores from surface to underground is that of flow of bulk solids. Must it be crushed? Will it hang up in the transfer? What size and inclination of ore pass are required. How is the ore best fed onto the transporting device underground? As an example, the planning engineers for the Carol Project of the Iron Ore Company of Canada faced these problems in making their designs for the production and transportation of some 55,000 tpd from their Smallwood Mine in Labrador. Other operations, facing somewhat similar conditions, used other approaches of interest. This chapter describes some of the factors involved in the design, construction, and operation of a combination surface underground transportation system as applied to open pit mining operations. 9.62. Tunnel-Ore Pass Systems. The type, shape, dip, and size of the orebody, as well as the surface topographic features, generally estab-

Jan 1, 1968

• As part of $850,000 granted by the House Appropriations Committee for development of manganese in the U.S., the Bureau of Mines will build a pilot plant at Artillery Peak, Ariz., for development of low grade manganese ores. • The historic Argo tunnel and mill in Idaho Springs, Colo., will reopen shortly for the mining of uranium. The Uranium Co. of America has acquired control of the tunnel and mill and 12 nearby mining properties. J. H. Rodgers and G. C. Ridland will manage the operation. •The opening of a new 4000-ton per day coal mine in Washington Co., Pa., and the reopening of another mine of the same capacity in Fayette Co. has been announced by the H. C. Frick Coke Co. They'll help meet added war demands. •A 7000 bbl per day commercial synthetic liquid fuel plant, making gasoline from natural gas at Brownsville, Texas is being operated by the Carthage Hydro-col Corp., a Texaco subsidiary. The gasoline is produced by the Hydrocol process, chemically similar to the Fischer Tropsch process, but differing mechanically in several ways. To operate the process it has been necessary to build an oxygen plant producing 95 pct pure oxygen in quantities equal to U. S. production of commercial oxygen in 1946. •Over 96 pct of the class of 1950 at Montana School of Mines are now employed,, in industry, and they're scattered from MIT to the island of Cuba., • Cobalt, heretofore almost entirely imported, will soon be produced in Idaho. The Calera Mining Co. is building a 600-ton mill in which a cobalt and copper concentrate will be obtained from Idaho ores. •Plans for mining iron ore on the Conarky Peninsula in French Guinea, (an ECA project) call for equipment purchases as follows: 8 wagon drills, electric shovel for mining, conveyor for the port, 8 trucks, wrecker, 2 tractors, as well as miscellaneous accessories and spare parts. •A low-grade lead-zinc mineralization, located east of any known ore bodies in Utah's East Tintic district, has been located by a 2000-ft wildcat USGS drill hole. * Higher-than-going rates have been authorized by the Munitions Board for its stockpile program, where domestic production of scarce materials is low or uneconomical. Payment in excess of 25 pct over the foreign price is now permitted. •A new self-centering conveyor roll, developed by Carnegie-Illinois Steel, is expected to revolutionize materials handling. It completely eliminates the necessity for sideguides to keep materials on a conveyor. See P. 1028. •Great Britain's socialized coal industry employs twice as many miners, but produces less than half as much coal as America's coal industry. last year, British mines produced 28 million fewer tons of coal than the output of the same ,mines in 1939. Absenteeism amounted to a big 12 pot of working time. • Labor market conditions have tightened on almost a country-wide scale. Only 4 out of 143 major labor market areas have a substantial surplus -- less than half the total for May. Growing scarcities of skilled labor are in evidence.

Jan 10, 1950

By Donald P. Richards

West Elk Coal Company operates its Mt. Gunnison No. I mine on the western slope of the Rocky Mountains in Western Colorado. The mine is located along the north fork of the Gunnisson River near Somerset, Colorado as shown in Figure 1. The mine is designed for a sustained production of 1.4 million tons per year out of the "F" coal seam in the Mesa Verde formation. The coal seam is nominally 7 feet in thickness and dips at about 3 ½ degrees to the northeast. Mining of the seam is up dip with the entry portals on the north facing slope of Mount Gunnison. The mine is designed as a five entry system with four entries for ventilation and access and one entry for a coal-handling conveyor. The mine entry layout is shown in Figure 2. Initial mine planning began in 1979, with "permitting" complete and construction starting in the fall of 1981. A "turnkey" contract for design and construction of all five parallel mine entry tunnels was awarded by West Elk Coal Company to a Joint Venture of Jenny Engineering Corporation (design and contract management responsibility) and Affholder, Inc. (construction responsibility). The first entry access into the coal seam was completed in the early spring of 1982. The mine has been operating at full service (all five entries) for nearly 3 years.

Jan 1, 1984

By K. Hashiba, Y. Z. Liang, K. Fukui, M. Koizumi

"Efficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Development and modification of the rock drills based on test data are timeconsuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved. The objective of our research project is to construct a new realistic numerical model of continuous percussive drilling, which is based on the previous Okubo-Nishimatsu’s model. In this study, the parts of the previous model involved in stress wave propagation and attenuation were modified. The two models were prepared for HD712 hydraulic rock drill mounted on crawler drills and HD210 hydraulic rock drill mounted on drilling jumbos. Stress wave propagation was computed with the discretized one-dimensional wave equation. The calculated results were compared to the stress waves measured on a rod during percussive drilling. In both models for HD712 and HD210, the measured stress waves can be reproduced with the one-dimensional model of the same acoustic impedance as the actual piston, shank rod and rod combined with the CI+spring model as a rod joint. The calculated results indicate that the spring constant in the model of a rod joint needs to be set appropriately depending on drilling conditions. INTRODUCTIONEfficiency and penetration rate during percussive rock drilling significantly affect the speed of tunneling and excavation. Many researchers and engineers have continuously engaged in the advancement of rock drilling performance. Components related to the percussive drilling are a drill body, a piston, a shank rod, rods, rod joints, a bit and rock. The piston in the drill body is reciprocated by hydraulic pressure and collides with the shank rod a few thousand times per minute. Stress waves generated by the collision propagate and attenuate in the rods and rod joints, and then reach the bit. The bit penetrates and crushes rock. During percussive drilling, the components mutually affect each other and self-induced oscillation occurs. The number of blows and the rate of penetration are determined by the practical drilling conditions such as hydraulic pressure, thrust force, number of rods and mechanical properties of rock. Development and modification of the rock drills based on test data are time-consuming and costly. Hence it is essential to make effective use of numerical simulation. However, most of the numerical models proposed in previous studies were too simple in comparison with the actual percussive rock drilling in which many factors are involved."

Jan 1, 2015

By Wright R. J

The Commission called tenders for a four boom hydraulic jumbo, plus basket, on an art- iculated carrier in Sept. 1977. Atlas Copco submitted the successful tender in Jan. 1978 for the supply of a three boom jumbo, plus basket. The Promec TH470 jumbo was commiss- ioned in the 2000 m long Sophia tunnel in Nov. 1978. Adequate spare parts were not available during the first three months of operation and the hammers could not be overhauled at the recommended interval. One hammer was removed after drilling 13 600 m due to a crack in the intermediate housing. Tests were conducted with different types of drilling consumables. Both rope and Hi-teed threads were tested and found compar- able. The average penetration rate in the granite was 1.1 m/min. Initially the drillers were not experienced enough to operate the BUT 15ERH booms without causing damage to the booms and hoses. Drilling deviation espec- ially of the perimeter holes was greater than expected. It is now obvious that greater attention must be given to attracting, train- ing and retaining the right type of operator and maintenance fitter.

Jan 1, 1981

By Alex Lowson, Dan Tempelis

The Riverside Badlands Tunnel segment of the Metropolitan Water District of Southern California’s Inland Feeder Project, was lined with a segmented concrete primary lining and a welded steel final lining with the annulus filled with Low-Density Cellular Concrete (really a grout). The paper describes a numerical modeling technique that was developed to determine safe grout placement procedures to avoid pipe flotation, and shows the relationship between flotation and the rheology of the liquid grout. Design details of the steel liners are often not well suited to grout placement, and recommendations are given on how to improve this.

Jan 1, 2003

By P. M. Ambrose, A. C. Fieldner

This , the 11th annual report of research and technologic work conducted by the Bureau of Mines on coal and coal products , is issued following the closing of the Bureau's war work on fuels and contains references to most of the published articles containing results of war investigations . The few remaining papers will be discussed in next year's report . The trend in coal research in the Bureau of Mines was discussed in Mechaniza- tion . This publication , covering the period from the close of armed con- flict to resumption of normal coal -research activities , includes a section never previously presented . There is included for the first time a discussion of the Bureau's activities in the Liquid Fuels and Lubricants and the Solid Fuels Subcommittees of the Technical Industrial Intelligence Committee . This report does not replace the more comprehensive ones prepared by individual authors and listed as footnote references in this publication . purpose is to bring to the reader a résume of the work for the fiscal year ended June 30 , 1946. The material presented herein is based largely upon publications , but the results of some research and testing, which would not otherwise be published in the near future, are presented in detail .

Jul 1, 1947

By G. E. Goodspeed

The Cornucopia gold quartz veins form a parallel vein system traversing meta-morphic and granodioritic rocks. Field and petrographic evidence suggests that inetasomatism has played an important role both in the emplacement of the grano-diorite and in the formation of the veins. Structurally the veins appear to be related to the major tectonic features of the Wallowa Mountains and to be narrow shear zones rather than filled fissures. Petrographic studies indicate a complex history of formation starting from initial alteration along fractures or joints followed by recurrent fracturing and a quartz-forming stage, and closing with continued shearing and microbrecciation, which permitted the upward percolation of the later ore-forming solutions. The precipitation of ore minerals from these solutions formed ore shoots. Postmineral effects include the injection of Tertiary basaltic dikes, a shght amount of cross faulting, and some movement along the planes of the veins as well as oxidation. Introduction Cornucopia is in the southeastern part of the rugged Wallowa Mountains of northeastern Oregon. It was founded over 50 years ago following the discovery of its system of gold quartz veins. The major veins are roughly parallel and dip into the western side of Pine Valley, which drains the southern slope of the range. Previous operations had cut the upper portion of four major veins with two tunnels over 1000 ft. apart, when the present operating company drove a third tunnel, called the Coulter, at the level of the valley over 1000 ft. lower to intersect the most easterly major vein at over 6200 ft. from the portal. General Geology of District The oldest rocks in the vicinity are metamorphosed sediments and volcanics. These, for the most part, are presumably Mesozoic in age, although some black argillites outcropping along East Pine Creek are considered to be Permian.l,2 These rocks have been deformed and metamorphosed in general to hornfels at the close of the Jurassic. The series was then invaded by a granodiorite batholith, the origin of which is

Jan 1, 1941

By G. E. Goodspeed

The Cornucopia gold quartz veins form a parallel vein system traversing meta-morphic and granodioritic rocks. Field and petrographic evidence suggests that inetasomatism has played an important role both in the emplacement of the grano-diorite and in the formation of the veins. Structurally the veins appear to be related to the major tectonic features of the Wallowa Mountains and to be narrow shear zones rather than filled fissures. Petrographic studies indicate a complex history of formation starting from initial alteration along fractures or joints followed by recurrent fracturing and a quartz-forming stage, and closing with continued shearing and microbrecciation, which permitted the upward percolation of the later ore-forming solutions. The precipitation of ore minerals from these solutions formed ore shoots. Postmineral effects include the injection of Tertiary basaltic dikes, a shght amount of cross faulting, and some movement along the planes of the veins as well as oxidation. Introduction Cornucopia is in the southeastern part of the rugged Wallowa Mountains of northeastern Oregon. It was founded over 50 years ago following the discovery of its system of gold quartz veins. The major veins are roughly parallel and dip into the western side of Pine Valley, which drains the southern slope of the range. Previous operations had cut the upper portion of four major veins with two tunnels over 1000 ft. apart, when the present operating company drove a third tunnel, called the Coulter, at the level of the valley over 1000 ft. lower to intersect the most easterly major vein at over 6200 ft. from the portal. General Geology of District The oldest rocks in the vicinity are metamorphosed sediments and volcanics. These, for the most part, are presumably Mesozoic in age, although some black argillites outcropping along East Pine Creek are considered to be Permian.l,2 These rocks have been deformed and metamorphosed in general to hornfels at the close of the Jurassic. The series was then invaded by a granodiorite batholith, the origin of which is

Jan 1, 1941

By Hans M. Ewoldsen

The generation and evaluation of solutions to body force problems is of extreme interest to the geotechnical profession, as all natural stress states must necessarily include some contribution from the weight of the material. In this chapter the elastic solution for the stress field around a circular, horizontal tunnel at an arbitrary depth beneath the surface of a half-space is reexamined. The influences of body force, initial stress, and free surface proximity are examined and related to in-situ cases. The solution as presented deals only with an isotropically elastic medium; this medium is further considered only in a half-space configuration. It is readily apparent that these restrictions impose severe limitations if analogies are attempted with in-situ cases where geologic discontinuities, inhomogeneities, and irregular boundaries exist. The question might be raised as to the propriety of geotechnically oriented researchers even considering such idealized conditions. There is, however, much to be gained from study of such solutions. The lack of geologic discontinuities and inhomogeneities allows the investigator to separate and leisurely examine such parameters as are included in the solution, without worry of interrelationships of a host of other parameters. Further, elastic solutions have had extensive usage prior to the development of such techniques as the finite-element solution. It is interesting to compare body force solutions with the external field solutions which in the past have been used for design purposes. Finally, the exact solution may be used to verify the accuracy of the finite-element type of solution. The mathematical solution on which this chapter is based was originally developed by R. D. Mindlin.l Because of the complexity and length of the solution, no attempt was made to determine the resultant stress fields until the advent of the present-day high-speed digital computer. How-

Jan 1, 1972

By Joseph Clare, Elizabeth Anderson, Mike McGinley, Ron Hines, Judy Cochran

The South Lake Union Pipelines contract for King County Wastewater Treatment Division and Seattle Public Utilities in Seattle, Washington included three 1.8 m (72-in)inside diameter microtunneled pipeline segments totaling about 793 m (2,600 lf).Tunnel alignments were within street right-of-way of heavily traveled urban roadways. Project challenges recognized in the design included: high groundwater levels; contaminated soil and groundwater; variable soil conditions, including fill; and timber piles and other obstructions remaining from historic land uses. The tunnels were built using a Lovat MTS Microtunneling machine, beginning in spring 2003. Conditions encountered during construction presented additional challenges beyond those anticipated in the design process, and were successfully addressed by the owners, designer, and construction management consultant all working with the contractor. Problems included highly variable soil conditions, cracking of reinforced concrete pipe joints during pipe jacking, a timber pile trestle uncovered during shaft construction, and obstructions encountered in the second and third microtunnel runs.

Jan 1, 2005

In This Chapter [Ventilation: dilution and displacement Water sprays: wetting and airborne capture Water additives: foam and wetting agents Dust collectors: filtration efficiency and inlet capture efficiency Reducing the generation of dust for cutting, drilling, blasting, crushing, and conveying] [This chapter will give you a general perspective on what works or doesn’t work. The chapter will also help if your dust control problem doesn’t fit any of the circumstances described in later chapters. ] This chapter describes the three major control methods used to reduce airborne dust in tunnels and underground mines: ventilation, water, and dust collectors. It also describes methods to reduce the generation of dust, so less has to be removed from the mine air. The ventilation methods provide the best use of air in the vicinity of workers and in the vicinity of dust sources. In this sense, the methods described are local ventilation methods. Most of the emphasis is on so-called displacement ventilation because it is the most effective dust control technique available. The section on water sprays outlines the dual role of sprays—wetting and airborne capture—and describes why wetting is more important. It also corrects some of the misconceptions about spray effectiveness and describes circumstances where sprays can actually increase the dust exposure of workers. The section on dust collectors outlines the circumstances under which dust collectors can be expected to function effectively. It also describes some common design and maintenance problems. The final section describes how to reduce the amount of dust that gets into the air in the first place, since once the dust is airborne it is always harder to control.

Jan 6, 2003

By Michael A. Devane, Neil Duncan

Inclines and tunnels can extend from ground surface to considerable depths traversing a wide range of lithologies. The strata encountered may be affected by loosening and induced stresses at different locations along the route. It is suggested that Phase I of the pre- driving assessment process should include study of the geology, hydrogeology, rock material and rock mass characteristics. A rock mass disruption factor is used to express the ratio of the unconfined strength of intact rock material to the unconfined strength of in situ rock mass. It is suggested that there is a relationship between in situ (secondary) permeability values and the disruption factor, since the permeability of the rock mass is governed by parameters which influence strength. In Phase I1 of the pre-driving assessment, consideration should be given to the prediction of primary loosening which results largely from disturbances to the rock mass arising from the driving process. Also in Phase 11, preliminary assessments are made of the effects of induced stresses and of the geodurability characteristics of the rocks. In Phase 111, the mechanics of various secondary loosening pro- cesses are considered along with their relevance to estimates of stand up time and support requirements. Yield-line analysis is introduced for the study of plastic and brittle type bending deformations. Stand up time and support characteristics are also assessed. In Phase IV, the effects of induced stresses are analysed. It is suggested that even for broken rock in the Yield Zone, the rock mass disruption factor may not often increase above lo which is equivalent to an in situ permeability of 10-1 m/s.

Jan 1, 1983

By B. T. Stanley

Traditional methods of creating a water tight shaft liner involve the use of segmented or welded steel. When shafts are located in ground that exhibits extremely difficult conditions of high water inflow and hydraulic pressure, composite liners are often combined with ground freezing during construction. The authors were searching for a cost effective and more flexible solution to hydrostatic liners design than the traditional concrete/steel composite design used so far. Searching through new technologies developed for tunneling applications, sprayed on membranes systems seemed very promising but were not developed for the specific circumstances encountered in shaft sinking applications where ground freezing is involved. Even though freezing is a very effective technique, it creates adverse temperature conditions for the application of spray on membranes. In addition, application and hydrating cure times for those membranes products ranged between six to twenty-four hours under ideal conditions (usually temperatures well above freezing point), which eliminated them from consideration in a shaft sinking cycle. While researching different spray on membrane materials, it was discovered that Stirling Lloyd Polychem Ltd. has developed and proven a different membrane material for waterproofing liners in different tunneling applications. The characteristics of the membrane exceeds the pressure parameters encountered in frozen shaft sinking operations, and the chemical cure times were reduced to one hour per layer which worked well into the shaft sinking cycle times. More over their system included a quality control procedure that allowed insuring integrity of the membrane at application time, a very desirable feature for shaft liner construction. However, the frozen rock surface still presented an unknown in the cure time and stability equation. As all membrane products a shotcrete substrate is usually required prior to application. The hypothesis used by the author was to use this shotcrete layer, not only as a substrate, but also as a thermal insulation against the frozen rock and the membrane during both application and curing time. The authors knew from experience that shotcrete could be applied successfully over frozen rock. But the shotcrete temperature curve over time was unknown and no information were found in the available literature. Testing was required to determine whether a suitable mix of shotcrete could be applied to the frozen shaft wall to provide enough heat of hydration for a suitable period of time to create conditions suitable for membrane application and curing.

Jan 1, 2012

By S. A. Diatchkov

Introduction There is a misconception that mineral-project economic evaluations in the former Soviet Union are either nonexistent or very limited. This is not the case. In fact, there are at least two basic methods that can be utilized to evaluate the vast mineral resources of the Commonwealth of Independent States (CIS). Evaluation procedures are based either on a comparison to known projects, which may rely on limited available data, or on potential-profit calculations, which generally uses more extensive databases. Significant philosophical differences between these systems and those utilized in the Western world include the following: •Under the centralized-government system, the economic evaluation of a mineral project was based on artificially determined mineral prices and costs. Every ten to 12 years, prices for concentrates and metals were established by the Council of Ministers and remained unchanged until the next reconsideration of prices . •The time value of invested money was not considered to be important under these "stable" prices, and inflation was assumed to be nonexistent in the planned economy. •An overestimation of the value of social and economic factors such as keeping the local population employed and providing the country with strategic minerals biased the economic evaluations of projects. Sequence of exploration Geological exploration in the CIS countries typically includes two major phases: prospecting and exploration. Prospecting consists of the following: •Regional geological studies. •General prospecting. •Prospecting. •Prospect evaluation. Regional geological studies are conducted within large territories and utilize satellite images, deep seismic zoning and other state-of-the-art methods. Geological and geophysical maps on a scale of from 1:200000 to 1:1000000 are developed to help identify regional anomalies and mineral prospective areas. The areas of primary interest are then subjected to general prospecting, beginning with geological mapping of the area at 1:50000 (1:25000) scale. The prospecting phase determines mineral potential based on further geological mapping (mostly 1:10000 scale), surface geophysics and geochemistry. Finally, the most attractive targets are subjected to further detailed evaluation (prospect evaluation) to help identify "possible" projects by means of trenching and wide-spaced drilling. The results of the prospect evaluation are analyzed and conclusions regarding the economical potential of the project are drawn. If the initial-prospecting phase results are positive and the prospect is recognized as economical, it then moves into preliminary exploration, which is followed by detailed exploration. Preliminary exploration determines the feasibility of the project on the basis of limited data. For example, in some underground projects, the initial exploration drilling and tunneling is done at two or three times wider spacing than would be required by the assumed mining method. Detailed exploration focuses on preparing the project for mining development, such as completing drilling and tunneling, particularly in the portion of the ore body to be first mined. During the project's mining phase, further exploration is usually conducted along the flanks of the mineralized structures and deeper sections of the ore body. Finally, during exploitation, it is sometimes necessary to delineate the ore body within the mining-block limits. A comparison between the United States (US) sequence of exploration activities and the CIS system is given in the Table 1. There is no "additional" and "exploitation" exploration shown in the US system, but it is common knowledge that all mineral projects are subjected to "additional" and "exploitation" exploration while being mined. An economic evaluation should be performed after the [ ]

Jan 1, 1996

By Carl Johnson, D. R. Todd

The Blue Ridge Low Level Outlet (LLO) was a design/build contract to provide a secondary means of discharging water from the Blue Ridge Reservoir. The project involved driving a 3.25 m (11 ft) modified horseshoe tunnel by 293.5 m (963 ft) long utilizing conventional drill and blast methodology. The intake shaft and structure were constructed inside of a sheet pile cofferdam surrounded by a maximum of 20.1 m (66 ft) of water. The shaft was excavated 4.87 m(16 ft) diameter to a depth of 12.8 m (42 ft) below the tremie slab elevation. Steel lining, including a transition from 3.66 m to 2.74 m (12 to 9 ft) diameter and a90 degree elbow were installed in the inlet shaft and then backfilled with concrete. This paper will describe the RFP phase, the design phase, challenges of the underground construction and contractual challenges.

Jan 1, 2005

By William R. Nash

Introduction As ore grades decline and deposit depths increase, problems and costs of mining construction increase rapidly. Ground water greatly impacts the cost of mining construction. In developing or exploiting ore bodies or coal mines, stored ground water in waterbearing formations is often encountered. Man-made conduits or shafts are constructed, as are raise bores for ventilation (up to 6-m-diam or 20-ft-diam), or smaller diameter drill holes, used for either power cables or rock dust. In underground construction and mining, it is possible to inherit unmapped and abandoned drill holes either from oil or gas exploration, or from previous geological investigations. There also exists within underground work exposure to faults, fissures, and jointing. A mine development may encounter unknown aquifers or, unluckily, have an ore body that is an aquifer. Water may invade an existing underground structure, due to concrete deterioration or to damage that may occur to an existing shaft or tunnel concrete lining. An underground development may intersect a drill hole that was not properly grouted when abandoned. It subsequently formed a conduit or an active path to conduct water into the mine. Water inflow may range from insignificant to a magnitude sufficient to inundate an area or an entire underground development. Corrosion imposes major costs. In shafts, it can cause accelerated wear and deterioration, and subsequent early replacement of hoisting ropes. It can also cause deterioration, misalignment, and subsequent accelerated wear and replacement of timber and steel guides and buntons. Utility maintenance (power cables, air, water, and ventilation lines) also can become a problem. Corrosion imposes major costs. Skips and skiploaders provide a never-ending series of maintenance headaches when exposed to an ingress of water. Numerous problems are found in declines with invert and rail maintenance and with partitions in over-under coal mine slopes. Ground water interacting with an underground ventilation system can result in: • Increased ventilation resistance due to roof falls and the spalling of ribs caused by ice heaving. • Restriction in shaft or slope cross-sectional area due to ice buildup during winter months. This may be a safety hazard to access as well. • An increase in the moisture content entering the ventilation air that condenses underground and causes electrical and equipment maintenance problems. Underground structures also incur water-caused problems. The concrete lining in shafts, slopes, and tunnels may be subject to: • Active mine waters causing concrete and reinforcing steel to deteriorate - perhaps to the point of collapse. • Load redistribution around a concrete lining, caused by soil dislocation due to water movement. The resulting stress may be in excess of the calculated design loading. Backwall injection with grout of the completed concrete lining may solve these water inflow problems through low-pressure injections of cement and chemicals. This fills voids at the interface of the concrete lining with either the soil or rock excavation. Surface structures may be jeopardized by lowering the ground water table, resulting in surface settlements. Surface settlements can occur in buildings, headframes, hoist foundations, mills, conveyor structures, or in rail haulage. Areas of differential settlement can lead to derailments, improper wear of hoisting ropes on sheaves in headframes, and the misalignment of bearings and brakes. Mud jacking and compaction grouting may remedy these problems. To reduce operating costs, increase efficiency, and increase safety, inflow water to the mine should be minimized. For an operating mine with a water problem, a water inflow survey should be taken. Quantities of water flow should be examined at all accesses (shafts, slopes, bore holes, and raise bores) at the faces, haulages (rails or conveyors), and sump discharge. From this examination and quantity survey before and after heavy rainfalls, valuable data for elim-

Jan 3, 1984

O.F.S. Branch Proceedings of the Annual General Meeting on Wednesday, 30th July, 1975 The Aromal General Meeting of the Branch was held at the St. Helena Club on Wednesday, 30th July, 1975 at 7.45 p.m. Mr D. A. Smith (Chairman) was in the Chair. There was also present: Professor R. P. Plewman, President of the S.A. Institute of Mining and Metallurgy. Conference on Vacuum Metallurgy The Fifth International Conference on Vacuum Metallurgy is to be held in Munich from 11th to 15th October, 1976. Excavation and tunnelling A conference on 'Rapid Excavation and Tunneling' is to be held in Las Vegas from 14th to 17th June, 1976. Book reviews Mine filling. Queensland (Australia), Mt. Isa Mines, Limited, ] 973. 293 pp. $A20,00 incl. postage. Young, R. S. Cheml:cal phase analysis. London, Charles Griffin, 1974. 126 pp. £4.50. NIM reports Report no. 1714 The efficiency of the fire-assay procedure with nickel sulphide as the collector in the determination of platinum,silver, gold, and iridium. Report no. 1721 A preliminary investigation into the mechanism of depression in the flotation of sulphide minerals at the Prieska Copper Mine. Report no. 1725 The determination of silica in fluorspar by 14 Me V neutron-activation analysis. Report no. 1736 The determination, by atomic- absorption spectrophotometry and liquid extraction, of antimony (parts per million) in ores and concentrates. Report no. 1741 South African costs of equipment for the metall'urgical industry(1975}. Report no. 1744 The refining of the platinum-group metals . Report no. 1746 The determination, by atomic-absorption spectrophotometry, of minor elements in zinc, lead, and copper sulphide concentrates. Report no. 1747 Magnetohydrostatic separation of gold from gravity concentrates. Report no. 1750 A review of the present and future development of sulphur production in South Africa. Report no. 1754 A new three-dimensional anodic electrode for reduced power consumption du,ring the electrowinning of metals. Report no. 139 A preliminary survey of goldrecovery problems arising in the production of pyrite. (9th Feb., 1967, re-issued Jun. 1975.) 16 pp. Report no. 140 A preliminary mineralogical investigation of pyrite from the K imberley and the Main Reefs, VogelstruisbuU Gold Mine. (13th Feb., 1967, re-issued Jut 1975.) 11 pp. Report no. 165 Gold recovery from pyrite flotation mill products by cyanidation. Progress made up to 1st May, 1967. (5th May, 1967, re-issued Jun. 1975.) 8 pp. Report no. 133 Gold recovery by cyanidation from mill products obtained after pyrite flotation. Progress made up to ht July, 1967. (18th Jul., 1967, reissued Jun. 1975.) 14 pp. Report no. 219 A review of some of the mineralogical factors influencing the flotation of pyrite. (29th Nov., 1967 reissued Jun. 1975.) 20 pp. Report no. 278 Gold recovery by cyanidation from mill products obtained after pyrite flotation. (24th Jan., 1968, re-issued Sep. 1975.) 51 pp. Report no. 306 The effect of preaeration on two samples of thickener under flow from the Venterspost Gold Mine. (30th Mar., 1968, re-issued Jul. 1975.) 14 pp. Report no. 317 Results of tests carried out at the Loraine Gold Mine during the period 5th to 7th February, 1968. (21st Mar., 1968, re-issued Jul. 1975.) 11 pp. Report no. 321 Aeration of ore from the Loraine Gold Mine before theaddition of cyanide.(17th Apr., 1968, reissued Jul. 1975.) 30 pp. Report no. 380 The effect of aeration, before cyanidation, of pulps of gold ores containing xanthate. (14th Aug., 1968, re-issued Jul. 1975.) 44 pp.

Jan 10, 1975