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By A. J. Erickson

In mid 1970, Park City Ventures, a Utah partnership of ASARCO and TAC, initiated a six phase exploration and development program in the Park City District, Utah. Geologic studies had delineated a number of exploration tar¬gets in several areas of the district. Discovery of ore in any of the target areas and continued favorable down dip development below then productive ore bodies would allow for reserve expansion and mill construction. The targets were: Mississippian Humbug Formation replacement mineralization below productive ore bodies on the east flank of the Park City Anticline; Humbug replacement mineralization in an unexplored fault block in the footwall of the Hawkeye structure on the east flank of the anticline; vein and replacement mineralization along the Silver Fissure; potentially higher grade Humbug replacement mineralization in a theorized structural block on the west flank of the anticline beneath the Ontario Vein; Permian Park City Formation replacement mineralization in the West End Shaft Area of the Silver King mine; vein mineralization along the Back Vein in the Judge Mine. Chilean Nationalization in 1971 resulted in a 30% budget cutback. The Judge and Silver King Projects were suspended. In spite of the cutback additional reserves were developed below the Humbug East Flank ore bodies; a major zone of ore grade mineralization was discovered along the Silver Fissure; five new ore bodies were found in the Humbug, and Doughnut Formations on the west flank of the anticline beneath the Ontario Vein. First concentrates were shipped from a new mill in May 1975.

Jan 1, 1976

The deformation, failure, and filling characteristics of a caving roof in the initial and normal mining stages of a pitching oblique longwall mining area are analyzed using large-scale threedimensional physical-similitude experiments and numerical calculations to study the characteristics of roof fracture and migration in a steeply dipping seam. The results show that the roof fracture development has evident sequential and spatial characteristics. Among them, immediate roof breaking in different parts of the mining area shows difference in time and space. The failure sequence of the immediate roof in different areas changes with the mining; unique regional stability evolution characteristics are observed in the suspended immediate roof simultaneously, resulting in its significant regional stability on the goaf filling.

Jan 7, 2020

By M. D. Lawton

Anglo-Rouyn Mines Limited, managed by Rio Algom Mines Limited is a subsidiary of the British-based Rio Tinto-Zinc Corporation Limited. This mining operation is situated in Northern Saskatchewan, 250 miles north of Saskatoon and represents the first base-metal mine of any importance served by this relatively new mining province. The outcrop of Copper-bearing Chalcopyrite was first discovered by prospectors in 1915, but was not mined until 1965 due to the absence of any form of road into the area prior to this latter date. The mine, mill and concentrator were designed to handle 900 tons per day of comparatively hard, abrasive ore containing chalcopyrite with traces of gold and silver. The flow sheet, Figure 1, is, we believe, elementary, designed with low cost in mind and utilises much old equipment from closed¬-down mines. Due to some difficulty in attaining the designed grinding capacity, changes were made in the crusher circuit. This, unfortunately, lowered the crushing rate too much. A series of changes have taken place to re-establish the original crusher capacity of better than 100 tons per hour. In the quest for a better recovery certain modifications have been tested in the concentrator circuit. These steps are discussed in minor detail.

Jan 1, 1970

By W. J. Wolfe

Using a combined fire assay-atomic absorption method, gold determinations with a minimum detection limit of 5 ppb were made on 345 samples of Early Precambrian felsic plutonic rocks collected 2 2 from intrusions ranging in size from 4 km to 88 km and in composition from syenite to granodiorite. Gold levels in unmineralized stocks are consistently below the 5 ppb detection limit of the analytical method used. In contrast, analyses of samples from stocks containing gold mines within their borders and in nearby metavolcanic-metasedimentary host rocks show a strongly skewed trace element gold population with a substantial percentage of gold values exceeding 5 ppb and ranging as high as 320 ppb. The data indicate that (1) ore-stage hydrothermal metasomatism has produced widespread Au enrichment in Precambrian intrusions that host epigenetic vein-type gold deposits, and (2) geochemical Au analysis of samples collected from 30 to 50 randomly distributed sites can be used to estimate the gold exploration potential of stock-sized bodies and to outline internal patterns of Au variation which may be useful in directing exploration to particular contacts or portions of a stock. The results do not conclusively indicate unusually high Au content in primary unaltered igneous rocks.

Jan 1, 1975

By Dan Nilsson

Open pit mining is the strong sector of the American mining industry. In the middle of the 60's. 17-18% of the ore in metal mines was mined with underground methods. From the middle of the 60's to 1980 the production in open pit metallic mines increased from about 400 to close to 600 million short tons while at the same time the underground mine production decreased a little, from about 90 to about 80 million tons. Less than 15% of the ore prodction now come from underground mines. Large amounts of waste rock were also handled in the open pits. In the middle of the 60's about 600 milion tons were handled, in 1980 1,200 million tons were moved. This means that the average stripping ratio increased from about 1.5 to over 2.0 tons of waste rock per ton of ore, figure 1.

Jan 1, 1983

By Gunter Fauth

The setting of tasks for the process control of coal cleaning, and in this connection the requirements for instrumentation can be classified into the following three fields: - Monitoring the operation of individual units, or process steps, - Control of units or process steps, - Control of the entire coal cleaning process with the intention of optimizing the operation and the profitability of the process. Instrumentation is affected by the type of cleaning processes. For introduction Figure 1 shows the simplified flow sheet of coal preparation which is usual in the German Ruhr District and in which desirable places for the measurement of ash, moisture and sulfur content are marked. The preparation plant is supplied with run-of-mine coal from the shaft via a homogenization facility. In a first step of primary classifying the raw feed coal is screened at about 10 mm. The raw coarse coal ( = 10 mm) is sorted by jig washers or heavy-medium separators. the raw fine coal (< 10 mm) at first is pneumatically sized at about 0.5 to 0.75 mm. The fines, the aspirated dust, are a finished partial product which will be added to the final metallurgical or steam coal. The material 10 to 0.75 mm subsequently is sorted in fine coal jigs and dewatered in centrifuges. The sludge obtained with the wet cleaning processes is dewatered in thickeners and fed to the flotation. Concentrate and tailings are dewatered by filters or bowl centrifuges and by chamber filter presses or belt filter presses, respectively. The partial products coarse coal, fine coal, flotation concentrate, aspirated dust, and middlings are blended to result in the sellable products metallurgical and steam coal.

Jan 1, 1984

By M. N. Herrera

The bioleaching of mineral sulfide pulps in a bench-scale rotating drum reactor has been studied. The reactor includes horizontal paddles in the inner wall for lifting of the mineral pulp. The performance of the reactor was tested in the bioleaching of a refractory pyritic gold concentrate in the presence of pure Thiobacillus ferrooxidans strain (ATCC 19859). The concentrate was efficiently bioleached at 50% pulp density with the drum operating at 0.5 -1.0 rpm Attempts of bioleaching the concentrate at the same pulp density in conventional stirred reactor showed severe inhibition of bacterial activity. The results demonstrated that the drum reactor allows to operate at much higher pulp densities than the conventional stirred tank reactor. This behavior is explained in terms of an improvement of the bacterial activity due to a better control of the attrition of the mineral particles.

Jan 1, 1997

By Adrian Brown

Floor heave can be a major problem in large open pit mines. Unrestrained floor heave can lead to flooding, equipment destruction, slope instability and subsidence. It is particularly troublesome in coal mines where the floor is frequently relatively flat, and is often underlain by major water Searing units. This paper examines methods of analysis used in computing floor stability, and sets out a simple rational method of evaluating the required level of water pressure control to maintain acceptable floor stability. The approach is illustrated by reference to the stability of the floor of the Morwell open cut lignite project in Southeast Australia, where this approach has been used successfully for over a decade.

Jan 1, 1982

By F. E. Kottlowski

Widespread high-calcium limestones in New Mexico region are low -in magnesium, but some units include shale interbeds deleterious for sulfur removal usage. Thick limestones in Mississippian Escabrosa, Lake Valley, and Leadville, Pennsylvanian Madera and Hermosa, Pennsylvanian-Permian Horquilla, Permian Hueco and Capitan, Cretaceous U-Bar, and some Cenozoic travertines are high-calcium units. Significant outcrops are in mountains of southwestern, south-central, central, southeastern and north-central New Mexico, southeastern Arizona, southwestern Colorado, and northwestern Chihuahua. Coal-fired powerplants are mainly in northwestern New Mexico and eastern Arizona, thus transport is mainly by railroad.

Jan 1, 1994

By R. M. Clowes

Lithoprobe is a collaborative, multidisciplinary research project which is providing new insights into the tectonic evolution of the North American continent through its work within ten study areas across Canada. For the mining industry, such results provide a well-constrained regional framework and better understanding of tectonic processes which lead to the development of ore deposits. In mining camps, seismic reflection methods have proven effective in imaging shallow to moderately dipping litho logic contacts as well as structural features, and in some cases have been used for the direct detection of ore bodies. Here, short case histories are provided for the Abitibi greenstone belt (VMS deposits) in Quebec and the Thompson nickel belt in Manitoba.

Jan 1, 1999

By R. M. Clowes

LITHOPROBE is a collaborative, multidisciplinary research project that is providing new insights into the tectonic evolution of the North American continent through its work within 10 study areas across Canada. For the mining industry, such results provide a well-constrained regional framework and better understanding of the tectonic processes that lead to the development of ore deposits. In mining camps, seismic-reflection methods have proven effective in imaging shallow to moderately dipping lithologic contacts as well as structural features and, in some cases, have been used for the direct detection of orebodies. Here, short case histories are provided for the Abitibi greenstone belt (VMS deposits) in Quebec and the Thompson nickel belt in Manitoba.

Jan 1, 2002

By M. E. Kuchta

Research is currently being conducted at the Colorado School of Mines in the use of high-pressure water for scaling down loose rocks in underground mine openings. In addition to improved miner safety, the adhesion strength of shotcrete applied to rock surfaces treated with high-pressure water is also increased significantly, resulting in improved overall support capabilities of the shotcrete layer. Test results show an increase in adhesion strength by a factor of four on a concrete test wall cleaned with water at 21 MPa (3,000 psi) as compared to a surface cleaned at 0.7 MPa (100 psi).

Jan 1, 2003

By Gordon F. Revey

In underground construction and mining work, situations occasionally occur where hard rock or concrete must be excavated at locations near critical structures or utilities. Fearing damage from blasting, contractors and engineers often explore the viability of using mechanical methods or expansive concrete to facilitate the excavation work. However, for moderate to large excavations, the prolonged duration and high cost of using these methods is often impractical. In these situations, under the right conditions, controlled blasting and blast-management methods can be used to speedup the work and lessen costs. The process of determining whether or not blasting is practical is often complex, particularly when risks are high. In this paper, general methods of conducting blasting risk evaluations and outlined and considerations for blast design and risk management are reviewed. This paper also includes three blasting case histories demonstrating how these techniques were used at recent projects. In the first case, a cautious blasting program was developed to facilitate the removal of concrete and rock within a large section of an active mineshaft. The second case involved critical blasting to excavate a dry lake-tap connection between a tunnel and a shaft at the Southern Nevada Water Intake No. 2 project in Henderson, Nevada. The third case history describes how novel blasting methods were used to carefully drop a 2,721,500-kg (6,000,000-lb) concrete caisson into a1.2-m (4-ft) rock socket at the Detroit Outfall No. 2 project in Detroit, MI.

Jan 1, 2001

By Catherine M. Dentan, Yosry A. Attia

The presence of finely divided carbonaceous matter, particularly graphite, in gold ores, adversely affects the adsorption - recovery of gold by activated carbon from cyanide solutions of such ores. Competitive adsorption of gold by graphite and other carbonaceous matter, is thought to be responsible for this deleterious effect In this study, adsorption of gold cyanide complex AU(CN)2- by the activated carbon used in carbon-in- pulp or carbon-in-leach processes, was compared with that by graphite which was chosen to represent the carbonaceous matter. Similar adsorption studies were made with gold chloride complex AuC14-. Correlation of adsorption with surface characteristics and thermodynamics were presented in detail, and a flowsheet for graphite-in-leach was proposed.

Jan 1, 1990

By D. Bizier, B. H. Gardner, Y. P. Wang, S. Serata

As part of an ongoing effort to develop more cost-effective and “user friendly” hardware for geomechanical measurements required for underground mine design, Serata Geomechanics, Inc. (SGI) has investigated the potential of borehole pressure cells (WCs) for in situ measurement of stress states and continuous monitoring of changes in ground stress. In particular, because of certain advantages gained thereby, WCs utilizing an elastomer, instead of metal (e.g., copper), for the skin of the pressure cell have been developed. A data analysis technique for determining ground stress state directly from BPC data has been developed. This technique has been tested for salt ground through both in situ applications and computer simulation analysis of the BPC/borehole boundary interaction. This paper discusses the data analysis technique, the results of field and computer simulation testing of its validity, and evaluates the advantages of elastomeric BPCs in relation thereto. It utilizes field data from recent elastomeric BPC applications in the salt mine at Goderich, Ontario operated by the Sifto Division of Damtarn Inc.

Jan 1, 1986

By W. W. Vaughn

In the technique described and evaluated, detection of mercury is based on the principle of atomic absorption. An analog signal, produced when mercury vapor absorbs ultraviolet light, is converted to digital form and calibrated to mercury concentration. Interferences are eliminated by selectively trapping the mercury on gold. The lower limit of sensitivity, using a 1-gram sample, is 5 parts per billion. A model of the instrument mounted in a station wagon has been tested successfully in the field.

Jan 1, 1964

By J. J. Carlson

Studies were carried out to determine whether filtration rate changes observed in an iron ore concentrator were due to variations in particle shape. It was confirmed that ores mined from different locations differed in filtration rates by as much as 60%. However, when image analysis was used to quantify the shapes of the individual particles in the filtration feed, it was found that the particle shapes showed almost no variation, and the shapes did not correlate with the filtration rate. It was also determined that the filtration rate variations were not caused by changes in particle size distribution. These results suggest that the differences in filtration rate are due to factors other than size and shape, such as surface chemistry.

Jan 1, 2008

By Zhenqi Cai, Mike Lichte, Kimberly Kennedy

The Ohio River Tunnel is the first of three combined sewer overflow tunnels to be constructed under Allegheny County Sanitary Authority's Clean Water Plan. The project consists of a total of approximately 5.5 miles of 18-ft and 14-ft finished diameter, segmentally lined deep rock tunnels and smaller diameter dewater and flow connector tunnels, as well as 8 deep flow drop and access shafts varying from 25-ft to 70-ft in finished diameter and 130-ft to 170-ft in depth. This paper describes the project components and the primary engineering challenges faced during design, including tunnel alignments and shaft site optimization with tight right-of-way constraints and multiple railroad and highway crossings. Assessment of tunneling methodology as well as tunnel and shaft designs and constructability included overcoming 5-bar hydrostatic pressure, abrasive bedrock, and the selection of the appropriate support of excavation systems in high-permeability alluvial soils adjacent to the Ohio River.

Jun 23, 2024

By Gy. Deák

The Romanian mining and especially the salt mining industry is going through a restructuring phase; among others it has to respect the European Environment Act. One of the most important deficits of the salt mining industry is the implementation of monitoring systems for geomechanics phenomena, in order to develop an important information database and form a real base for salt mines stability, prediction and prevention measures. Monitoring system solutions, involving discontinuous and continuous measurements of displacement / deformation fields, around underground excavations, are presented and discussed. In addition, a case study for the stability prediction of an experimental salt off-set, located in the Praid salt mine, using DKRControl method, is presented. The two monitoring systems use different tools, namely measuring tapes (to determine distance between markers in T-D station) and ultrasonic transducers (SM-TDA equipment).

Jan 1, 2006

By Karin Bäppler

"When considering large-scale infrastructure projects worldwide special attention has to be paid to the large diameter tunnel construction projects that were successfully completed in the Southern Hemisphere. The projects that are highlighted in this paper are large-scale infrastructure projects in the sector of transport. In focus are four road tunnel projects that were constructed in Australia and New Zealand using mechanized tunnelling technology. The tunnel boring machines (TBMs) that were reliably applied to these four major projects all exceed the bore diameter of 12 meters. These TBMs are therefore in the range of large to very large diameter TBMs. The technology used demonstrates state of the art technology with tailored tunnelling technology adapted to the specific project demands. Two Double Shielded Hard Rock TBMs (Ø 12.35 meters) were used for the construction of the Clem Jones Tunnel in Brisbane crossing beneath the Brisbane River and these two machines have been reused for the excavation of a 4.3km long two-lane highway tunnel for Legacy Way in Brisbane creating a new traffic artery towards the city centre. Two EPB Shields (Ø 12.48 meters) excavated and lined the twin-tube road tunnel for the Brisbane Airport Link. Excavation diameters in excess of 14 meters, such as the Earth Pressure Balance Shield (Ø 14.41 meters) involved in the Waterview Connection Project in New Zealand, are understood in the tunnelling industry as very large diameters. The machine is customized to the requirements and subsurface conditions of Auckland. The paper spotlights the large to very large diameter TBMs that were used and focuses on the comprehensive solutions developed by the machine manufacturer to provide a system with benefits for the contractor especially for the Waterview Project. INTRODUCTION Extensive large-scale road infrastructure projects like the ones implemented in Brisbane (Australia) and currently under construction in Auckland (New Zealand) show the tendency of today’s infrastructure construction projects. Functional infrastructures need to be put in place to cope with the demand of mobility and flexibility of people living in cities and metropolises. Impact during construction work to people or environment has to be kept as low as possible to ensure the quality of life is not disrupted."

Jan 1, 2016