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By N. Langsford

The Archaean Yilgam craton has been a major gold province since 1888 with production and reserves of about 4700 tonnes. Production in 1994 was about 135 tonnes. The largest deposit, the famous Kalgoorlie Golden Mile, contains about 2000 tonnes of gold. About 40 deposits containing more than 35 tonnes (1Moz) of gold has been discovered so far in the Yilgarn. Most of the craton has deep weathering profiles inherited from previous tropical climatic conditions, modified by subsequent arid conditions. A mantle of transported material covers much of the variably stripped weathering profiles. Resolving the geology of the volcanic-sedimentary units (greenstones) and the structures that host the gold mineralization relies heavily on aeromagnetics and shallow drilling.

Jan 1, 1995

By V. G. Lofftus

Since plant start-up in January 1983, Golden Sunlight Mines, Inc. has implemented several process changes and improvements. Among these are a pulp preaeration circuit and a sand tailings retreatment circuit. The purpose of the preaeration circuit is to reduce reagent consumption during gold dissolution. The sand tailings retreatment circuit was added to recover and process separately pyrite concentrate to maintain acceptable overall gold recoveries with the more refractory sulfide ores. Research and plant operating data along with process and improvement descriptions are presented.

Jan 1, 1987

By Robert Rautenberg, Paul McDermott

This paper will discuss the construction of 15.9 km (9.88 mi) of tunnels on a project in Chicago, Illinois. The tunnels were driven utilizing two rock and four soft ground TBMs ranging in sizes from 7.39 m (24.25 ft) in rock down to 1.95 m (77 in) in soft ground. In addition to the mining, there are 63 upper level structures and 16 dropshafts averaging 61.5 m (202 ft) deep included on this project. Many diverse mining, excavation, support and lining techniques were employed on this project.

Jan 1, 1997

By Adrian Brown

The primary method of slope stabilization is ground water-control. Recent research has established the properties which slope materials must exhibit in order for stabilization measures to be feasible, but there is little guidance in the literature about suitable field tests to develop the parameters needed for this evaluation. This paper presents a proven method for large scale testing which allows an evaluation of the feasibility of ground water pressure control in a reasonable cost and time frame. Methods of performance and analysis of the test are presented, and the method is illustrated by reference to case examples.

Jan 1, 1984

By J. W. Francis

The paper about to be presented deals with the relatively straightforward problem of mining two seams of coal separated by an interval. This may seem to be a simple problem but within a twenty-mile radius of Consolidation Coal Company's Burning Star # 4 Mine at least seven (7) different techniques of two-seam mining have either been tried or are now in use. This great variety of techniques should point out that there is no single simple solution; a conclusion often reached when dealing with mining problems. As a background for the techniques presently in use at the Burning Star # 4 Mine, we will briefly outline the other five (5) stripping techniques used in the area: 1. Captain Hine 6360 Range Diagram (Figure 1) 2. Leahy Mine Range Diagram (Figure 2) 3. Burning Star # 3 Mine 5860 Range Diagram (Figure 3) 4. Burning Star # 3 and # 4 Mines Dragline in Pit Range Diagram (Figure 4) 5. Captain Hine 2570/5561 Range Diagram (Figure 5) Each of these techniques was chosen because it provided the best and least expensive alternative for mining the coal under the particular restraints encountered. The Mine Engineers at our Burning Star # 4 Mine, Mr. Dennis Mahan and Mr. William Weaver, will now detail two additional mining techniques, out-lining our experience to date.

Jan 1, 1977

By T. W. Camm

The Bureau of Mines conducts studies of the economic impacts of regulations on federal lands. These studies are part of the Bureau Potential Supply Analysis (PSA) program. To meet the needs of these studies, a methodology was developed to estimate operating and capital costs for a mineral deposit given its tonnage, grade, and depth. The format for the cost models in this study was developed at the Bureau's Western Field Operations Center (WFOC), Spokane, W. A., for studies of known and undiscovered resources on Federal lands. These cost models are described in a Bureau publication by Camm (1991).

Jan 1, 1993

By J. McMurray

Introduction Uranium was recovered from mining of collapse breccia pipe deposits in the Arizona Strip district in northwestern Arizona (Figure 1) intermittently between 1956 and 1990, with cumulative production having totaled 23.3 million pounds of U3O8 (8960 tU) at an average grade of 0.6% U3O8. Production was suspended in 1990 because of low uranium prices, but the recent resurgence in market price once again makes the breccia pipe deposits potentially attractive exploration and development targets. This paper describes: (1) formation of the pipe structures and their metallogenesis; (2) mining and milling of breccia ore; and (3) potential roadblocks to development of new breccia pipe mines. Breccia Pipe Formation Formation of the breccia pipes began in cave systems formed during development of karst topography in the Mississippian Redwall Limestone. The karst Redwall surface was eventually covered by up to 900 meters of shallow marine to continental sediments ranging in age from Pennsylvanian to Triassic. The pipes were formed by progressive upward stoping caused by groundwater ascending under hydraulic head along near-vertical faults, joints and fractures. The stoping process involved both chemical disaggregation and mechanical failure of roof and wall rock. Upward stoping of successively younger units allowed for upward propagation of a pipe and resulted in a chimney-like column of breccia between the steep walls of the pipe. Syndepositional thickening of sedimentary units of varying ages indicates that pipe formation began as early as early Pennsylvanian time and continued intermittently through Triassic time.

Jan 1, 2007

By Aditya Rana, A. K. Mishra, M. M. Singh, N. K. Bhagat

Many cases of derailments, train accidents and traffic interruptions due to the slope failure and rockfall have been reported in the past on Konkan Railway trackline because of unstable rock slopes. The authorities installed stability enhancement measures such as wire netting, rock bolting and shotcreting which were found insufficient. The failed geotechnical measures prompted authorities to excavate the unstable slopes. Rock blasting is generally not preferred for the excavation of slopes along the transportation route. Stabilisation and widening of slopes by blasting need closure of the route for a considerable time. Discontinuing traffic on Konkan Railway route was undesirable as it connects two important port cities Mumbai and Mangalore. The paper presents an innovative directional controlled blasting (DCB) technique for excavating three unstable slopes (i.e. cuttings) in hilly terrain without disturbing the traffic. New empirical formulae for small geometry blasting to estimate burden and throw have been developed. A unique sequence of firing and excavation with powder factor varying between 0.04 and 0.39 kg/m3 irrespective of the actual free face was used for rock blasting. The process controlled the throw of blasted material over the track and resulted in a smooth and stable wall. The slope angle has been changed from 80 to 82° to 45–47° and probability of wedge, planar and toppling failures was eliminated. About 100 such accident-prone slopes (52 km cumulative length, 7% of total route) situated at discrete locations along Konkan Railway route were stabilised using the technique. No incident of rockfall and slope failures along these slopes has been observed after the stabilisation.

By William G. Doepken

The extensive use of rubber-tired support vehicles as a complement to a fleet of load-haul-dump and drill jumbo units has proved invaluable in maintaining scheduled multilevel/multiheading development drifting advances at the Henderson Mine. Support equipment, whether self-powered or towed, releases primary drill-blast-muck equipment from the supportive functions of ground control, utilities installation, steel and concrete construction and supply handling, thus providing both balance and increased flexibility to an underground, rubber-tired mining system. Experience has indicated that increases in man productivity and improved safety and working conditions coupled with decreases in overall costs and mining cycle times are realized with the inclusion of support vehicles in the mining fleet.

Jan 1, 1976

By J. Singh

Recently, a Maryland bank became the overnight owner of a toxic waste site through a foreclosure. The original property owners had operated a crash and garbage business on the site and obtained loans for their business venture through the bank. In 1980, their son purchased the property from his parents with mortgage monies obtained from the bank. Failing to make his loan payments, the son defaulted on the mortgage. The bank foreclosed on the property and eventually purchased the property at a foreclosure sale. Shortly after the bank's purchase of the site, toxic wastes were found on the property--the result of disposing solid wastes on the site for 10 years. The bank declined responsibility for contaminating the site and consequently for its cleanup. The Environmental Protection Agency (EPA) took corrective actions to clean up the site. EPA then handed the bill to the bank, citing the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) of 1980 (more commonly known as "Superfund"). CERCLA imposes liability on the current owners and operators of hazardous waste sites.

Jan 1, 1988

By Ramkrishna Agarwal

A low grade iron ore is mined underground at Grace Mine using the panel caving method. Most of the development work is located in footwall. The runways for LHD equipments are heavily supported with steel sets on five foot centers. The sets are embedded in two to three feet of concrete. The initial cost of support is one of the largest single costs of production. During the process of ore-win¬ning, supports frequently fail, necessitating expensive repair. There is no systematic pattern to the failure of supports. A rock mechanics program was launched to isolate causes and their relative contributions to the failure of supports. The preliminary results are presented. A typical portion of a runway is instrumented to monitor rock mass movements around the runway and the corresponding response of supports as various mining activities are carried out in the neighborhood. We believe that such a program is a prerequisite to any remedial measure to alleviate pressure problem at Grace Mine.

Jan 1, 1973

By William J. Wiehagen

The training of mining personnel is a large and continuing activity for the mineral industries. Although safety and skills training has long been recognized as an essential element for reducing injuries and improving productivity, the research literature lacks definitive reports documenting the specific value of such training. The training literature presents a variety of testimonials as to the "benefits of training," but lacks data that specifically tie that training to the performance of the worker.

Jan 1, 1983

By Joseph G. Selmeczi

Lime and limestone-based SO2 scrubbing processes have demonstrated reasonably good success in removing low concentrations of SO2 from flue gases. While most of the operating problems experienced in the early days of scrubbing have been worked out, problems usually increase and removal efficiency drops with increased amounts of SO2 present in the gas stream. In order to overcome these difficulties, yet still taking advantage of lime and limestone as the lowest cost neutralizing agents, a host of so-called double- alkali systems were developed. These processes take advantage of cations such as Na+ and NH4+ capable of forming highly water soluble bases or basic salts, such as hydroxide, carbonate or sulfite, which having been neutralized or acidified by the absorbed SO2 can be regenerated with a lower cost base such as lime.

Jan 1, 1974

By Weibai Hu

The flotation separation of wolframite from fluorite and quartz is investigated with chelating agents and neutral oil as synergic collectors. Test results indicated that a-nitroso-ß-naphthol has a strong collectivity for wolframite and selectivity against fluorite and quartz. The 8-hydroxyquinoline has collectivity and selectivity also. They both have a better activity than sodium oleate. However, the cupferron is slightly inferior. The synergism of chelating agents and neutral oil looks promising, especially for fine wolframite particles. The activation effect of Fe2+ and Ca2+ ions on separation of wolframite from fluorite and quartz is slight. The UV absorb-spectra measurements showed that the adsorption of chelating agent on wolframite is multilayer, and flotation behavior is related to chemisorption. The chelating agent which bonds to Fe and Mn sits on the wolframite surface, and the reaction between Mn2+ ion with collector is more significant. The essentials affecting reagent activities are the bonding factor and the hydrophobic factor. These factors are discussed by structure-activity relationship theory. The synergism of neutral oil is a secondary collector likely to lengthen the hydrocarbon chain of chelating agents.

Jan 1, 1985

By G. Reed Marchant

The control systems engineer is often faced with the problem of designing tests or experiments where the cost of obtaining information is expensive. This is true in aerospace as well as in process industries. In these situations the details of test design should be carefully evaluated before any test is executed so that the maximum amount of information is obtained for the effort expended. In recent years there has been a steady trend towards increased automation, In the process industries this has resulted in extensive review of process variables and, instrumentation techniques, development of more accurate system mathematical models, and extensive investments in complex control system as well as completely automated plants. When planning and developing these systems, where each measure of a process variable is usually expensive, it behooves the design engineer to give considerable thought to the details of test design before instrumentation is procured and installed so that the maximum amount of information can be obtained for the expense incurred.

Jan 1, 1968

By W. Dan Hausel

Archean supracrustal rocks of the South Pass greenstone belt of western Wyoming have been an important source of gold and iron ore. Actual gold production statistics are incom- plete although gold production estimates for the South Pass- Atlantic City district range from a low of 2.0 Mg (70,000 oz) (Koschmann and Bergendal, 1968) to a high of 9.8 Mg (327,000 oz) (Hausel, 1980). From 1962 to 1983 iron ore was also mined from the greenstone belt and production totaled more than 91 Mt (90 million It). The supracrustal rocks of the South Pass greenstone belt occur in a tightly folded synform bounded by Late Archean granite and granodiorite. The youngest of the Archean successions has a reported Rb-Sr isochron age of 2.8 b.y. (Stuckess, et al., 1985). Metamorphism of the supracrustals increases towards the flanks of the belt and is amphibolite-grade enclosing a small island of greenschist facies rocks. The supracrustal sequence consists of metasedimentary and metaigneous rocks that are divisible into four mappable units. The metasediments include metagraywacke, quartzite, pelitic schist, banded iron formation, metaconglomerate, and graphitic schist. Metavolcanics include metabasalt, meta-andesite, and ultramafic schist. These supracrustals have been intruded by mafic sills and dikes and tonalitic stocks and dikes. Two granite plutons and associated pegmatites intrude the supracrustals in the western portion of the belt, and the supracrustals exhibit both fault and intrusive contacts with granitic batholiths along the western and eastern margins. The northeastern flank of the Archean belt is unconformably over- lain by Paleozoic sediments, and the southern portion of the belt is onlaped by Tertiary sediments.

Jan 1, 1990

By R. E. Gundersen

I have to express my surprise and must send a note of warning concerning the use of polyurethane foam as described in a paper by R.N. Torbin and R.F. Kovar, entitled "Innovative Shaft Lining Method," published in your February 1989 edition. In September, 1986, 177 miners lost their lives when they were exposed to fumes downwind from a fire in a tunnel lined with polyurethane foam. Whilst polyurethane exhibits reasonable fire retardent properties in small-scale tests, mass use in a tubular configuration, exacerbated by the furnace effect of cross-radiation, can lead to a rapid, uncontrollable conflagration.

Jan 1, 1990

By Jean-Michel Rendu

Accurate modeling of the semivariogram is an extremely important step in the geostatistical analysis of mineral deposits. Automatic fitting of a mathematical model is often possible but not necessarily desirable. Significant geologic and statistical information must be taken into account in the fitting process, which is not always available to the computer. Manual fitting of the model is, on the other hand, extremely time consuming. Interactive graphics are best suited to optimize the process. A number of interactive methods are described, which are adapted to the modeling of semivariograms in one-, two-, or three-dimensional environments.

Jan 1, 1982

By J. W. Cooksley

Pyrometasomatic zones are a type of replacement deposit, normally in a carbonate rock unit, which consists of a zoned, coarse-grained, generally iron-rich mixture of calcium and magnesium silicates. These zones or rock masses are also called ?skarn,? and ?tactite?. They are formed as a result of the interaction of a shallow intrusion of magma with a carbonate or calcareous host rock and are considered to be of hydrothermal origin. Three environments of pyrometasomatic deposits are depicted in Figure 1. Of course, the interaction takes place at high temperatures. Pyrometasomatic zones are categorized as calcic or magnesian, depending on whether the intrusive interacts with a limestone or a dolomite. Common pyrometasomatic zone minerals are garnet, epidote, quartz, calcite, wollastonite, actinolite, hedenbergite and diopside. Pyrometasomatic zones are of considerable economic importance because they contain ore deposits of tungsten, molybdenum, copper, lead, zinc and iron. According to Rose and Burt (1979), the chronological sequence in the formation of a ?typical? pyrometasomatic deposit is as follows: 1. Shallow intrusion of magma at 900-700°C into carbonate sediments.

Jan 1, 1981

By Madeline Mello, Michael Low, Nick Karlin, Bryce Scofield

The LA Effluent Outfall Tunnel is the first tunnel in the United States to incorporate post- tensioning into the precast segmental lining. Several unique components were integrated to ensure that the post tensioning could be carried out successfully in the tunnel, even concurrently with the TBM excavation. This also required the development of new processes both in the casting facility and in the TBM to ensure that the almost 3,700 rings could be successfully manufactured, threaded, stressed, and grouted. This paper will discuss the material selection, fabrication, and installation of, as well as lessons learned from, this first in country tunnel lining.

Jun 23, 2024