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By D. E. Cameron

The Cannon mine, located in north-central Washington is mining gold hosted in silicified Eocene-age arkosic sediments arrayed along a regional strike-slip fault system. Branches of the Eagle Creek fault have broken the Chumstick Formation into blocks and wedges, and have caused intense deformation of stratigraphy in the mine. Mineralization at the Cannon mine (B-Reef) and O-Reef (L-O mine) is a bulk silicification with high grade cross-cutting veins containing principally electrum, silver sulfosalts and pyrite in a gangue of quartz, adularia and calcite. Orebodies have very irregular shapes, but tend to follow stratigraphy and high-angle pre-mineral fault breccias and splays developed adjacent to the major faults. Both B-Reef and O-Reef occur at significant bends in the regional trend of major fault strands. Mean gold grades decrease upward from near sea level to the 300 m elevation at the Cannon mine. A new discovery, the A-Reef is hosted by a moderately dipping structure which is at a low angle to bedding. Fluid inclusion studies of B-Reef ore zones indicate dilute ore-bearing fluids boiled at temperatures between 185 and 2850 C at a depth of 1 km. Many ore zones are bounded by sheared mudstone and claystone and a much broader halo of argillic alteration comprising illite, smectite and sericite. Trace and major element analysis by ICP-ES for 33 elements, LECO for S, Hg by CVAA and gold by AA-FA shows dispersion patterns hundreds of meters outward from the known orebodies in the Cannon mine. Geometric mean comparisons, hierarchical R-mode cluster analysis and single element spatial plots show that Hg, As, Sb, S and K/Al compose a suite of elements which are significantly dispersed away from, and increase toward mineralization. Ba, Ca, Na, Mn, V and Zr decrease toward mineralization. The suite is more selective than gold with respect to known mineralization within the exploration area.

Jan 1, 1992

By B. K. Cantrell

The use of diesel equipment in underground coal mines is controversial because "whole diesel exhaust" is regarded as "a potential occupational carcinogen" by the National Institute for Occupational Safety and Health (NIOSH). Threshold limit values (TLVs) are recommended for the gaseous pollutants; CO, CO2, NO, NO2, SO2' and some hydrocarbons emitted in diesel exhaust. There is, however, no TLV recommended for diesel exhaust aerosols (DEA) nor is there a standard method for sampling these aerosols. The University of Minnesota and the Bureau of Mines have collaborated to develop a personal diesel exhaust aerosol sampler (PDEAS) which utilizes size selective, inertial impaction and gravimetric analysis. During the field tests of this sampler, numerous air quality measurements were conducted in underground coal mines using diesel equipment. The objective of this report is to present these data and to assess the impact of diesel face haulage equipment on mine air quality.

Jan 1, 1991

By E. R. Bauer

The ground control aspects and occupational safety concerns of extended depth-of-cut mining are presented in this U.S. Bureau of Mines (USBM) report. The scope of extended cut use and typical face operations while extracting extended cuts is reported. A comparative review of roof fall fatalities and a statistical analysis of accidents and injuries for both extended and nonextended cut mining is included. The views and opinions on extended cutting from a series of interviews with mine workers in five states are summarized. In addition, some of the problems and safety concerns of this extraction system are mentioned.

Jan 1, 1995

By W. E. Crandall

The Star-Morning mine is a. 1000-ton-per-day lead-zinc producer located in the easterly part of the Coeur d'Alene Mining District of North Idaho. The property includes both the Star and Morning mines which are located on the westerly and easterly portions of the same complex of veins. The mine is 70% owned by the Bunker Hill Company (Gulf Resources, Inc.) of Kellogg, Idaho, 30% owned by Hecla Mining Company, and operated by Hecla Mining Company with head-quarters in Wallace, Idaho. One of the characteristics of mines in the Coeur d'Alene District is that many of the ore bodies extend to very great depths. The Star is no exception, but rather a leading example. The complex of near vertical veins and ore shoots extend some 7000 feet below the surface at present, with a maximum strike length of about 4000 feet. Ore has been mined on 20 separate veins and ore structures. More than 50 miles of headings have been driven and nearly 23 million tons of ore mined since the Morning mine started in.189S. The problems of mining at such depths are formidable temperature on the bottom level is 1100 F and high humidity problem. Pressure from the sheer weight of rock is as high foot. This paper will deal with providing a new access to the deeper levels of the mine and the installation of a hoist and related items to service these levels. By the time development had reached the 7100 level (Figure 1), it became apparent that a different 'hoisting system was going to be necessary if we were going to continue to mine at a profit. The main shaft extended to the 4000 level at which point a ?:3100"'foot winze shaft provided access to the 7100 level. The two hoists were limited to handling 3-ton payloads at 1200 to 1500 feet per minute. Some ores are still produced from above the 4000 level but as these ore reserves become depleted the hoisting of the desired tonnage (1000+/day-) from the lower levels of the mine would exceed the capacity of the existing hoisting system. A decision was made to sink a new vertical shaft at a point well in the south wall of the ore bodies where strong rocks and a minimum of faulting was expected and to purchase and install a new hoist capable of hoisting over 7000 feet. This new' shaft, designated as the No. 4 Shaft, was planned to reach 2000 feet below the 7100 level which was the deepest level at that time. The hoist would be in-stalled on the ,main 2000 Adit level which is used as an access and haulage level to the concentrator and surface plant in Burke.

Jan 1, 1971

By J. C. Motz

With ore grades continually decreasing and finer mill feed requirements, it becomes increasingly important to have the capability to handle the larger tonnages economically. With the 10 ft. Standard capable of reducing 1,633 metric tons per hour (1,800 short tons per hour) to 80 percent passing 50 MM (2 inches) and the 10 ft. Short Head following to produce a mill feed of all minus 12 MM (1/2 inch) at a rate of 608 metric tons per hour (670 short tons per hour), we feel significant savings will be realized in installation and operating costs. The largest concentration of cost in the secondary and tertiary crushing stations is the building itself that houses the process equipment. An example of the savings to be attained can be seen from an examination of a 40,820 metric ton (45,000 short ton) per day crushing plant. A total of nine 7 ft. Symons Cone crushers is used to generate 12 MM (1/2 inch) ball mill feed. The average center distance between units is 6.1 M (20 feet) and allowing a 6.1 M (20 feet) nominal distance from the centerline to the wails, the building becomes 61 M (200 feet) long. For this production rate, four 10 ft. Symons Cone crushers would be required. With the 10 ft. crushing plant requiring a center distance spacing of 7.6 M (25 feet), the building length totals approximately 38 M (125 feet). Construction costs vary depending on location, but a reduction in building length from 61 M (200 feet) to 38 M (125 feet) will result in estimated savings of between $2,500,000 and S4,000,000. While the 10 ft. Symons Cone has been involved in a number of feasibility studies for some time, the Process Machinery Division of Rexnord commenced detail design work on the 10 ft. Cone crusher in 1972. For comparison purposes, the 10 ft. and 7 ft. capacities are given in Table 1.

Jan 1, 1978

By V. Rajagopal

Corrosion and abrasion properties of a series of chromium-containing cast iron balls with Cr contents ranging from 0 to 29% was evaluated and compared with austenitic stainless steel and mild steel balls. Marked ball wear tests were performed on artificial ore samples consisting of 95% quartzite with either 5% pyrrhotite or 5% chalcopyrite under a nitrogen or oxygen atmosphere. The electrochemical mechanism was investigated by correlating the corrosive wear with the corrosion currents obtained from potentiodynamic polarization curves under abrasion. An offset in their electrochemical activities was observed somewhere between 16 and 26% Cr. In fact, 26 and 29% Cr cast irons showed an excellent corrosion resistance approaching that of austenitic stainless steel. Flotation recoveries were estimated on a 95% quartzite + 5% pyrrhotite sample ground with various cast iron ball materials under an oxygen or nitrogen atmosphere. Electrochemical results are found to be in good agreement with corrosive wear obtained from marked ball wear test and with flotation results.

Jan 1, 1991

By X. X. Jiang

An efficient recovery of finely divided magnetite particles of 400/500 mesh from a mixture of magnetite/silica particles has been investigated by imposing a delicate balance between centrifugal and surface tensional forces on these particles. The effect of centrifugal force, surface tensional force, density and size of particles on the overall metallurgical efficiency has been examined. A mathematical model based on a momentum balance on the particles at the liquid/liquid interface has been developed. The validity and limitations of the model are discussed in view of the experimental results obtained.

Jan 1, 1992

By Gary Brieley

Until well into the 20th century, most construction work was performed under the auspices of a master builder or in a manner that would be described today as design-build. In addition, many civil engineers served as ?interns? under the tutelage of a master builder in order to learn how to design and construct a certain type of structure. This was certainly the case for tunneling projects with various individuals having been identified as tunneling experts as a result of successfully completed projects The master builder approach began to change in the early 1900s to a model that would be referred to today as design-bid-build. A design-bid-build approach to project procurement gives the owner more control over the final product and al-lows the contractor to know exactly what is expected of them before the work is constructed. As a result of this transition in project procurement, civil engineering schools placed a greater emphasis on the training of ?design? professionals. This article will document how the training of tunnel design professionals progressed within the United States. Although it is difficult to generalize about the hundreds of tunnels that were constructed in the first four decades of the 20th century, there is one project that stands out as having resulted in a university program related directly to tunneling and that is the Chicago Subway. During a visit to the United States in 1938, Dr. Karl Terzaghi met a student named Ralph Peck who was then studying at Harvard University in a pro-gram established by Arthur Casagrande. Shortly thereafter, Terzaghi traveled to Chicago for a lecture and was asked to consult on the Chicago subway project that was then under construction. The Chicago subway was being constructed in clay, and the owners were worried about possible settlements to nearby buildings. Terzaghi asked Peck to serve as his field engineer for that project. Thus was established one of the most productive relationships in the history of civil engineering in the United States. Peck, who would become Dr. Peck, moved to Chicago in 1939 to participate in an extensive research project that con-tinued until subway construction was halted in 1941 because of World War II. During that time, the cost of subway construction in Chicago was reduced substantially as a result of Peck?s observations and Terzaghi?s recommendations. In fact, it was reported that subway construction in Chicago cost less than one-half of similar projects in London even though the clay in London is considerably stiffer compared to Chicago. Upon the completion of his work on the Chicago Subway, Peck accepted a professorship with the University of Illinois in Champaign/Urbana.

Jun 1, 2010

When science and the human spirit come together amazing things can happen. This was perhaps never more evident than through the events that unfolded during August and October in a remote desert in northern Chile. On Aug. 5, the main shaft of the San José copper and gold mine near Copiapó in Chile?s Atacama Region collapsed, leaving 33 miners trapped more than 624 m (2,000 ft) beneath the earth?s surface.

Jan 1, 2010

By P. R. Taylor

This investigation (Bowles, 1990) involves consideration of technology utilized by three separate fields of metallurgy and materials science: 1) The recovery of metals employing the use of solvent extraction, 2) The fabrication of materials using powder metallurgy, and 3) The use of composite materials in fabrication of engineering materials. The research considers each of the processes in order to realize the benefits of each. In light of the fact that materials have an intended use -it does seem plausible to simplify the process required between "mother earth" and final use. For instance, a primary copper producer that already employs a solvent extraction and electrowinning process could produce value added products directly. Part of the existing extractant flow could be diverted into a pressurized hydrogen stripping process in order to produce specialty composite powders. Innumerable methods have been employed for the recovery of metals; solvent extraction, the one considered in this study, was used due to the possibility of it providing a pure powdered metal. The use of solvent extraction in the recovery of metals has gained wide acceptance and its use proves beneficial in many applications (Ritchey and Ashbrook, 1984). Pressure hydrogen stripping of solvent extractants may provide the benefit of flowsheet simplification compared to conventional solvent extraction followed by electrowinning. It may also provide the benefit of direct production of high purity metal powder (Demopoulos and Distin, 1985).

Jan 1, 1992

By D. C. Seidel

The role of surface charge in soluble salt flotation, which was developed in Part 1, is extended to relate the theory to the specific phenomena of KCI- NaCl separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed.

Jan 1, 1967

By J. G. Groppo

A beneficiation process has been developed to provide selective separation of unburned carbon from high loss-of-ignition (LOI)fly ash. Using froth flotation to achieve selective separations requires long residence times and high reagent costs. A proprietary reagent system has been developed to address these limitations. Based on the results obtained from laboratory and pilot-scale investigations, a flowsheet design has been developed to produce two distinct usable products from class F fly ash — low LOI ash and a high-carbon product suit-able for reburning or further upgrading.

Jan 1, 1996

By S. Gaillard, E. Cauda

"Diesel particulate matter (DPM) is an occupational health hazard in underground mines. It generally occurs in the submicron range, and is often present in the mine atmosphere with significant concentrations of dust particles that tend to occur in the supramicron range. Since dust can interfere with analytical methods to measure DPM, it is often removed from a sample stream using impactor-type size selector (diesel particulate matter impactor, DPMI). Because the DPMI physically removes oversized particles from the stream, its performance may be gradually reduced with aging. Sharp-cut cyclones (SCCs) represent an alternative size selector for DPM sampling applications, with a major advantage being that, by design, they should not be susceptible to rapid aging. This paper presents results of a field study designed to compare the performance of aged versus new/clean DPMIs and SCCs in an underground mine. DPMI aging resulted in clogging of the device, and eventually a reduction of its effective particle cut size – though, when sample flow rate was maintained, DPM sample mass collection was not affected until significant aging had occurred. Under the conditions present for this study, effects of SCC aging were observed to be minimal by the end of the study period. INTRODUCTION Submicron particles are increasingly recognized as significant respiratory health hazards (Cantrell and Watts, 1997; Kenny, et al., 2000; Ristovski, et al., 2012). Diesel particulate matter (DPM) represents a major source of submicron particles in both public and occupational environments (Kittleson, 1998; Abdul-Khalek et al., 1998). Due to their work around large equipment in confined spaces, underground miners have some of the highest exposures to DPM (EPA, 2002; Grau et al., 2004). DPM largely consists of solid elemental carbon (EC), commonly known as “soot”, and organic carbon (OC) that may be sorbed to EC particles (Kittleson, 1998; Abdul-Khalek et al., 1998). EC and OC can be measured by thermal-optical methods such as the NIOSH 5040 Standard Method (Birch, 2016), and their sum is referred to as total carbon (TC). While the complex nature of DPM does not allow for its direct measurement, both TC and EC have been accepted as suitable surrogates for monitoring occupational exposures to DPM (Noll et al., 2007 and Birch, 2016)."

Jan 1, 2018

By J. D. Noll

An effective technique to minimize miners? respirable dust and diesel exposure on mobile mining equipment is to place mine operators in enclosed cabs with designed filtration and pressurization systems. Many factors affect the performance of these enclosed cab systems, and one of the most significant factors is the effectiveness of the filtration system. High-efficiency particulate air (HEPA)-type filters are typically used because they are highly efficient at capturing all types and sizes of particles, including those in the submicron range such as diesel particulate matter (DPM). However, in laboratory tests, minimum efficiency reporting value (MERV) 16 filters have proven to be highly efficient for capturing DPM and respirable dust. Also, MERV 16 filters can be less restrictive to cab airflow and less expensive than HEPA filters. To verify their effectiveness in the field, MERV 16 filters were used in the enclosed cab filtration system on a face drill and roof bolting mining machine and tested at an underground limestone mine. Test results showed that DPM and respirable dust concentrations were reduced by more than 90% when the cabs were properly sealed. However, when the cab door was opened periodically throughout the shift, the reduction efficiency of the MERV 16 filters was reduced to 80% on average.

Feb 1, 2014

By I. Weir-Jones

[Currently the cost of carrying out 'in situ' geotechnical investigation programmes or installing and operating monitoring systems at construction or mining sites is rising var." rapidly. This is primarily because of our ever increasing labour rates. As a result of this problem efforts are no,, being made develop techniques for the economical; collection of large quantities of geotechnical data relating, to such problems as done stability evaluation, the behaviour of underground openings, or 'in situ' testing procedures. The efforts to reduce the labour content. are particularly apparent in those procedures which have traditionally been manpower intensive e.g. 'in situ' permeability testing where an entire drilling crew and their associated eguipment have been on standby while testis has been carried out; or data collection in underground construction operations where much tine is typically wasted obtaining or maintaining access to instrument sites. In an attempt to illustrate one specialist consulting company's approach to the problem of reducing investigation costs, this rarer examines four recent developments in the field of geotechnical investigation and monitoring which have come about during the last two Years as a result of cur research and development programme. Although these techniques and devices have been developed for specific projects, they all have broad applications in the geotechnical field and they are indicative of the direction in which this company feels developments will take place.]

Jan 1, 1975

By L. Schlink

Impacted waters, often complex, are created in mining which at some point in the mine life cycle will need to be attended. The simplest and most cost effective method of handling impacted water is to reuse it as makeup water for operations. At the end of mine life, operational reuse will not be an option and the impacted water will require treatment to achieve alternative reuse goals. Conventional mine impacted water treatment is successful in removing unwanted constituents but create brine and sludge that may require special handling or additional treatment, resulting in additional liabilities and costs. Freeport-McMoRan Copper & Gold has taken an approach to water treatment that focuses on transformation not concentration. The Water Treatment Test Facility located at Sierrita Mine has three test plants that are piloting the mine impacted water transformation process. Two plants have been designed for the removal of calcium and sulfate with products of gypsum and sulfur. The third plant removes metals from process water and transforms them into marketable metal sulfides. The transformation, rather than concentration, of mine impacted water solutes greatly reduce long term risks.

Feb 23, 2014

By P. Guliov

In the first part of this paper the authors present an overview of industrial minerals produced in the Canadian provinces of British Columbia, Alberta and Saskatchewan, and supplied to the Pacific Rim countries. The second part outlines some of the unique opportunities for industrial minerals that exist in the three western Canadian provinces and those minerals we feel have development potential for overseas markets. Because of time constraints, it is not an exhaustive presentation on industrial minerals, but is focused on a few selected minerals that we believe have high potential.

Jan 1, 1990

By H. M. Castrantas

Caro's (peroxymonosulfuric) acid has been reported to destroy WAD (weakly acid dissociable) CN-but, until recently, the technology has not been demonstrated in other than a laboratory setting. During the last two years, Caro's acid has been shown to successfully detoxify WAD CN-in tailings at two large North American gold mines. Using on-site FMC generators, Caro's acid reduced the WAD CN-from 40-55 ppm to below 20-35 ppm WAD CN-, the target range for the two mines. The detoxification costs using Caro's acid were less than 50% of the treatment cost of using hydrogen peroxide, the previous oxidant of choice. In addition to the considerable savings in CN-detoxification costs, lower WAD CN-values were achieved and the detoxification time with Caro's acid was greatly reduced compared to hydrogen peroxide.

Jan 1, 1995

By L. A. Baker

The presence of goethite in a hematite ore has been shown to strongly affect the time of heating to the firing temperature. The investigation of spalling of single pellets and of packed beds has enabled free water and goethite spalling to be identified as separate phenomena. In addition, it has been shown that even for an 18 inch deep bed of green balls the free water and goethite drying periods can be considered separately. Based on this observation, a method of predicting production rate and hood temperature profile is presented. The method required knowledge of the ore goethite content, ore grind and the green pellet bulk density. Laboratory results were found to be in good agreement with actual plant practice and have led to improved process performance.

Jan 1, 1972

By Arthur B. Johnson

Potassium, is one of the three basic plant nutrients along with nitrogen and phosphorus. There is no substitute for potassium compounds in agriculture; they are essential to maintain and expand food production. Potash is found throughout the world in both soluble and insoluble forms. It is only the soluble forms that are economically attractive to process, primarily chlorides and sulfates, with potassium chloride by far the most important potash salt. Sylvinite ore, a mechanical mixture of sylvite (KCl) and halite (NaCl), is a natural mineral of potassium. This ore is found in commercial quantities in the Permian sin region near Carlsbad, New Mexico. Vast tonnages of high-grade de, low-clay-content ores have been mined and concentrated during the past 40 years; however, these deposits are rapidly being depleted leaving high-clay, low-grade ore reserves of over 135 million tons. These ores, containing 13 to 22 percent K20 and 3 to 8 percent clay slimes; cannot be effectively processed by current commercial flotation methods. The present concentration processes for potash minerals in Carlsbad relate mainly to ores containing 1 percent or less of clay-slimes with a K20 content of 20 to 25 percent to yield products to meet the requirements of the agriculture market, namely, 95 percent KC1 equivalent to 60 percent K20. Discoveries of potash ore in Saskatchewan, Canada, have shifted the emphasis on expansion outside the United States. Presently, the American companies are looking to Canada for future growth, expenditures, and expansion. Four of the seven companies operating near Carlsbad are produces of Canadian potash despite the large investment sons required for shaft sinking and milling installations.

Jan 1, 1970