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By H. P. Greenwald

About mid-December 1936, the safety director of a large coal corporation visited the authors at the Bureau's Experimental coal mine to discuss a rock-dust barrier he had invented primarily for use in trackless entries of coal mines. The rock dust in this device was carried in its original paper containers and means were provided for ripping these open so that the dust might be scattered in the path of an explosion. The inventor termed the device a "bag barrier", and this term has been adopted in the present paper for convenience. At that time the device was in an early stage of development, and the inventor felt that the barrier should be tested to determine whether it had enough promise of being successful to justify further development. The matter was taken under consideration and finally three tests were made during the week of February 15, 1937. It was concluded that while the device did stop an explosion in two of the three tests, it was much loss effective than ordinary rock dusting, and that too few data were obtained to permit direct comparison with tests of other barriers. Apparently, the conditions under which the device could, be successful 'Were somewhat limited, out the limits could not be defined without additional tests.

Jan 1, 1938

By S. R. Dismukes

Mining is likely to be targeted by The United States Environmental Protection Agency (“EPA”) as one of its key enforcement targets for fiscal year 2002-2003. Identifying the mining industry as an enforcement target, coupled with an increase in enforcement activity in recent years, places each mining operation at increased risk of receiving enforcement attention. A properly developed and implemented Environmental Management System (“EMS”) tailored for your operation is invaluable in reducing the risk of incurring liability for non-compliance. At the heart of an effective EMS is an audit program that checks the company’s compliance with environmental requirements. In addition, audit privilege (in select states), voluntary self-disclosure, and the attorney-client privilege serve as very effective tools for managing those liabilities that may arise during auditing a well-developed program. Of course, these latter tools are effective only if the auditing program is properly structured and properly managed. EPA and some states also provide varying degrees of immunity for environmental violations that are voluntarily disclosed in writing by the company. However, self-disclosure laws and policies typically prescribe stringent requirements for parties seeking to take advantage of them. For example: U.S. EPA has recently extended the time period in which to provide full written self-disclosure to 21 days. However, U.S. EPA’s revised Self-Disclosure guidance also addresses when a company obtains knowledge of a violation for purposes of triggering the 21-day clock and specifically extends the knowledge requirement to include the company’s agents and consultants. This expansion increases the difficulty companies may have in clearly defining and managing when they obtained knowledge. This difficulty increases the importance of managing factual development and the strategic use of other

Jan 1, 2001

By L. Harris

Los finos de coque son materiales que se producen en toda planta de gas y coque y que no pueden ser usados directamente en los hornos metalúrgicos debido que sus propiedades físicas y quimicas ison ndeseables. En este sentido, los finos de coque se producen en altos hornos de fierro y plomo, donde una capa de carbón sin aglomerar y parcialmente coquificado, permanece en la parte superior de la carga y es durante esta descarga que se separa del coque grueso. Sin embargo, el coque descargado es muy grande para el horno y debe reducirse a un tamaño pequeño. Por tanto, el texto señala que para que el coque llegue a los hornos debe contener más de 20% de finos y en el caso de los hornos de plomo, es necesario que se separe de los finos debido a que puede generar un sofocamiento en el rendimiento de los hornos. Así también, describe la operación de la planta de coque en La Oroya, como las características deseadas del coque.

Nov 20, 1967

El objetivo del presente texto es describir la geografía, petrografía, geotectónica, geología histórica y las vetas en la región minera SantoToribio, situado en Ancash. La parte occidental del cerro Santo Toribio tiene un perfil más abrupto, donde la roca volcánica aflora en grandes extensiones y en pocos lugares, la sedimentaria. Su petrografía la conforman dos tipos de rocas: las ígneas, cuya textura afanítica corresponde a una inalteración en su composición superficial, y las sedimentarias o calizas de grano fino, que se encuentran en San Juan. De otro lado, sobre la veta del túnel de Santo Toribio se desarrollan algunos fallas tectónicas, pero de menor consideración. En su geología histórica, las calizas de esta región son de origen marino y pertenecen al periodo cretácico inferior, y dentro de este, los pisos superiores al barreniano. Finalmente la descripción de las vetas tales como Santo Toribio, Soledad, Lumbrera, Pascua, San Juan, Santa Rosa, San José, San Luis, San Dimas, Yolanda, Raquel, Paquita, Blanca, ayudan a incrementar las posibilidades de afloramiento.

Jul 20, 1957

By J. A. Bowersmith

The environment in which the surface mining industry operates today is considerably different than that of a few years ago. Increased pressure from the public, government, labor and internal industry factors calling for the fulfillment of rapidly changing expectations is especially intense in the surface coal mining industry. Such things as requirements for increased production, the Mine Health and Safety Act, environmental concerns and land reclamation, shortages of qualified and enthusiastic employees and market cycles coupled with price competition are but some of the specific items that are requiring the surface mining industry to better utilize equipment, materials, and labor resources available, There is one technical tool available which will assist management to increase productivity, improve cost control and assist in planning, organizing and operating surface mines. Industrial Engineering is that tool. Before a discussion of specific applications of Industrial Engineering to surface mining is conducted, it is worthwhile to review a definition of Industrial Engineering and the history of its development. The following definition has been adopted by the American Institute of Industrial Engineers: "Industrial Engineering is concerned with the design, improvement and installation of integrated systems of men, materials and equipment. It draws upon specialized know- ledge and skill in the mathematical, physical and social sciences, together with the principles and methods of engineering analysis and design, to specify, predict and evaluate the results to be obtained from such systems."

Jan 1, 1976

By L. O. Bacon, D. O. Wyble

THERE has been considerable speculation among mining geologists and mining men in general as to the relative merits of gravity methods in iron-ore exploration. Most of the investigations which have been carried out in recent years have been done by mining companies, and few if any of the results have been published. Three gravity surveys have been made in the Iron River-Crystal Falls area,1,2 one by the U. S. Bureau of Mines, with inconclusive results, and the other two by Radar Exploration Co. for the Cleveland-Cliffs and the M. A. Hanna companies, with results not known to the writers. Both the last-mentioned surveys were detailed investigations, the stations being spaced as close as 10 ft along traverses,1 and were made to determine the feasibility of locating iron ore by gravitational methods. Because of the presence of a large body of ore already extensively drilled, Dr. Harold L. James of the U. S. Geological Survey, Iron River, Mich., suggested that a further test of gravitational methods of exploration be made in the Round Lake area of Iron County, see Figs. 1 and 2. This survey indicated a considerable regional gradient and led to a study of the surrounding gravity field and its relation to the major structural features of the syncline within which the iron formation lies. The southwestern part of Iron County presents a series of hills and hollows elongated in a roughly north-south direction. The bedrock topography is of pre-glacial origin. Relief is moderate; a maximum elevation difference of approximately 350 ft was observed during the survey. Major drainage is dendritic with the larger streams: the Brule to the south, the Paint to the north, and the Iron in the central part. Hills are thickly grown with hardwoods, and lowland areas, not under cultivation, are usually covered by second-growth softwoods. The area covered in this paper includes the southern half of Iron County, Mich., with a deep synclinal basin occupying the central part of the area, and the southeast corner of Gogebic County, immediately to the west of Iron County. The upper Huronian iron formation, slates, and graywackes which form the synclinal basin rest upon a greenstone basement. The basin has not been completely outlined by exposures, drill records or other means, as outcrops are scarce and the thick mantle of glacial drift makes geological investigations extremely difficult. Glacial drift varies in depth up to 300 ft or more. The drift is usually thickest under the hills and is thinnest in the depressions and along drainage courses where most of the bedrock exposures occur. The area over which gravity investigations were made is almost entirely covered by glacial material. Bedrock of the basin consists of a complexly folded series of iron formation, slates, and graywackes. One of the series of slates has a high magnetic susceptibility due to the fine-grained magnetite it contains. This formation can be detected readily by magnetic methods and provides a marker horizon which can be easily followed. The magnetic slates are stratigraphically above the iron formation, and much of the geological interpretation of the area is based upon the magneticc anomalies they produce.

Jan 1, 1952

By Glastonbury J. R

The kinetics of the direct chlorination of, zircon in the presence of carbon was studied at temperatures between 9000C and 12000 C. From the experimental data it is prop- osed that the most likely mechanism for metal oxide (MeO2) chlorination is as follows: At I Surfaceon zMeO2+ZMeCl - MeOC12 (1) At Carbon MeOC12+C+Cl MeC14+CO (2) Surface It.is envisaged that this type of mechan- ism would occur for both the zirconium and, silicon. constituents of the ore. In the above mechanism; the surface re- actions appear to be fast and not rate controll- ing. In a carbon surface deficient bed the diff- usion of oxychloride intermediate through the boundary layer to the carbon surface becomes the rate controlling step. In a zircon surface deficient bed the diffusion of oxychloride away from the zircon surface controls the reaction. This postulated mechanism can be used to ex-, plain the observed experimental effects.

Jan 1, 1973

Hard rock TBMs are very often open machine layouts, with just a part roof shield over the front of the machine. The whole system is designed for fast face advance and the economy of the project often depends entirely on the rate of advance. Typically, hard rock conditions will demonstrate stable and good ground for a major part of the tunnel. However, short sections of crushed shear zones with clay and gouge material may cause serious time delays. Spiling rock bolting has been proven to be very efficient under such circumstances, provided the fully grouted rebar bolts can be placed in a controlled and practical manner.Environmental restrictions are becoming more and more a part of tunnel excavation projects. Even hard rock TBM tunnelling may require a strict ground water control, because of consequences on the ground surface from lowering the ground water level. Such consequences may be surface settlement, negative influence on ground water resources or damage to vegetation.Pressure injection ahead of the advancing tunnel face (in this paper named pre-injection), using microfine cement and chemical grouts, is today a proven technology. As examples can be mentioned (Garshol, 1997) about 100 km of pre-injected tunnels below Oslo City and about the same length of subsea tunnelling elsewhere in Norway. Examples from other parts of the world are also available, like below Stockholm, Sweden, the Inland Feeder project and Hollywood Metro both in Southern California.To take advantage of spiling rockbolts and pre-injection, it is an obvious prerequisite to be able to drill the necessary boreholes in the right positions and at the correct angle. In drill and blast excavation this is simple, but in TBM projects it has repeatedly turned out to be difficult. More than once owners have accepted bids containing reassurance from the contractor that the drilling method will be sorted out later. Experience shows that if ælaterÆ means after start of the TBM operation, it is often too late.

Jan 1, 1999

By J. T. Norton, N. J. Grant, A. M. Gervais

An investigation of the creep deformation of coarse-grained high-purity aluminum at temperatures approaching the melting point permitted the formulation of a theory of subgrain formation. Subgrain boundaries were found to be formed by two different processes: kinking and polygonization. Polygonization is considered as the main factor in subgrain formation. SINCE "slipless flow" was first discussed in detail by Hanson and Wheeler,' many studies have been undertaken to determine how metals deform at high temperatures. Several types of observations have been reported. Jenkins and Mellor,² working on the creep of mild steels and various grades of commercial irons, found metallographic evidence of a kind of substructure within the grains after deformation at high temperatures. Homes" observed after creep deformation of steel at high temperatures that the original X-ray spots were sharply divided into several small ones. The same phenomenon was reported by Hirst4 from his studies on lead and later by Crussard5 from his work on aluminum. The works of these investigators demonstrated beyond any doubt that the splitting of the X-ray spots was due to the fact that the grains underwent a division into subgrains during deformation at high temperatures. Since then, numerous experiments have been undertaken on aluminum in order to determine the mechanism of formation of subgrains. Research workers can be divided, for the purpose of discussion, into two different groups as regards thinking on subgrain formation. On one hand, based on the work on polygonization by Cahn,6 Guinier and Lacombe,7 Greenough and Smith," Crussard,10,11 and Servi, Norton, and Grant," it was concluded that subgrain formation was a consequence of the simultaneous effects, first, of inhomogeneous deformation which produced bending of the lattice, and second, polygonization. On the other hand, Wood and coworkers13-16 based their work on the results of an earlier report" which dealt with crystallite size and a fragmentation theory. It is interesting to note that while Greenough and Smith8 and Wood et al. performed similar experiments, their conclusions were quite different. Wood et al. did not recognize polygonization as a fundamental mechanism and said that aluminum, at the beginning of the deformation, fragmented immedi- ately into subgrains in order to permit deformation of the metal, the number of these subgrains being a function of strain rate and temperature. They concluded that deformation of grains occurred by flow along the subgrain boundaries. In view of the contradictory conclusions, it would appear that the data were not explicit enough to provide an unambiguous conclusion. It appears that the techniques by which most of the results were obtained, namely, X-ray work, were not enough by themselves to solve the problem. Another approach was needed. In the present research, therefore, an extensive metallographic study was planned to supplement the X-ray work. The importance of revealing the subgrain boundaries metallographically was realized, and this will explain the extensive development and use of etching techniques. In order that subgrains would be considerably larger and therefore more readily visible under a microscope, the creep experiments were performed at very high temperatures approaching the melting point of aluminum. Development of Experimental Technique Creep tests were run at constant load on high purity (99.995 pct) aluminum specimens having a very coarse grain size. None of the specimens was run to fracture. The specimens were originally round (diameter, 0.187 in.; gage length, 1 in.) and had parallel flats milled in the gage section to permit

Jan 1, 1954

The Tick Hill Gold Mine is situated approximately 110 kilometres south of Mount Isa, and 14 kilometres north of the township of The Monument. It was discovered in October 1989 by Mount Isa Mines Exploration in an area which had been targeted as high in potential for copper-gold mineralization.A mining lease application was made in March 1990. Mining, and the construction of the plant and infrastructure, began'in early August 1991 after the lease was granted on 20 June of that year. Commissioning of the plant began in December 1991, and the first gold was poured on site on 31 December 1991.The development of the underground mining operation commenced in January 1992 with the drilling of the ventilation shaft. The access decline was started in March of the same year, with the first ore produced from underground in August.

Jan 1, 1993

By J. F. Perreault, J. Paraszczak

"The profitability of an underground mine depends to a great extent on the production cost.Random equipment failures and their consequences have significant influence on the total operating cost of a mining system. Having this in mind, a reliability study has been initiated for loadhaul- dump machines in an underground mine. The main purpose of this study is to identify the critical machine subsystems, determine their failure pattern and help work out an effective maintenance strategy. In the first part of this study, the failure data of diesel powered LHDs, gathered during an I8-month period have been analyzed. For the purpose of the analysis, the machines have been treated as systems comprising seven subsystems connected in series. The most critical subsystems, i.e. electrical and hydraulic, were further investigated, and analyzed by graphical and analytical methods. Different failure distribution models were applied and discussed. Basic Defmitions and ConceptsIn order to avoid confusion, several terms used in this paper are defined below, as compiled by O'Connor (1991). The acronymsBS and MIL-STD stand respectively for: British Standard and US Military Standard.Failure: the termination of the ability of an item to perform a required function (after BS 4778).Time Between Failures (TBF): the length of time between two consecutive failures.Observed Mean Time Between Failures (MTBF): For a stated period in the life of an item, the mean value of the length of time between consecutive failures computed as a ratio of the cumulative observed time to the number of failures under stated conditions (after BS 4778).Maintenance, Corrective: The actions performed, as a result of failure, to restore an item to a specified condition (after MIL-STD-721 B).Maintenance, Preventive: The actions performed in attempt to retain an item in a specified condition by providing systematic inspection, detection and prevention of incipient failure (after MIL-STD-721B)."

Jan 1, 1994

By Jozef S. Stachulak

Inco Limited operates 11 underground mines in the Sudbury District. The mines are located on the rim of the Sudbury Basin, an oval with the axis in the range of 27 and 60 km. The ore dips to at least 3000 m below surface. The ores are mined primarily for nickel and copper. Total ore production from underground is in excess of 55,000 tons per day. Over 40 surface fans have been installed since the late 1960's. All of the fans are adjustable pitch, axial flow units. A major factor influencing ventilation design in the last 30 years has been the introduction of diesel equipment underground. Volumes per fan have ranged from 60 to 330 (cubic metres per second), with motors from 100 to 2500 hp. Fans of the axial flow type have been in common use for main fan installations at Canadian mines for many years. The standard arrangement has been to mount these fans horizontally, i.e. with the fan shaft and the long axis of the housing horizontal. This is a natural arrangement for an underground fan, but for a surface installation, a vertically mounted fan has definite advantages. The surface area taken up by a typical vertical fan installation is generally about one quarter of that with a horizontal fan of the same capacity. (1) This is not a problem with isolated fans and flat surface outcrop sites, but where the installation is to be near existing buildings, or where there are poor surface soil conditions, space and cost considerations greatly favour vertical fans. MAIN FANS INSTALLED There are 43 main surface fans in operation at 11 mines. Twenty-seven of these fans are supply units, and 75% of them are vertical installation. The remaining 16 units are main surface exhaust fans, with predominantly horizontal installation. Within the last five years, some 20 main booster fans have been installed underground at several mines. Axial flow fans, with adjustable pitch blades, are used for both surface and underground installations. Exhaust fans are equipped with stainless steel or cast aluminum blades. Main underground fans are arranged horizontally and the majority of them have a floating shaft between the fan shaft and the motor. (2) The size of the fans in service varies from 1.8 m to 5 m in diameter, with the majority ranging from 1.8 to 2.5 m. The pressure produced by these fans varies from 0.25 kPa to 2.0 kPa. At Inco Limited, two main fans in parallel are preferred, rather than a single fan, so that if one fan fails, the remaining fan can still supply up to 70% of normal air quantities, while the damaged fan is repaired. This requires closure doors on each of the fans so the fan can be isolated in case of failure. It is more expensive than a single fan, but results in less production interruptions. The fan installations are well away from sharp inlet and outlet bends. FAN DESIGN INTEGRITY Both the mine operator and the fan manufacturer must understand that the main fan is critical to the mine operation, and that everything technically possible must be done in design and manufacture to ensure the highest degree of reliability. Some of the design parameters and criteria, based on Inco experience, are outlined and discussed below. RESONANT FREQUENCIES AND HOUSING MODEL ANALYSIS Any fan assembly will have many different resonant frequencies. It is a challenge to the designer to arrive at a design in which forcing frequencies do not coincide with any of these resonant frequencies to produce unacceptable vibration levels in operation. Finite element analysis is a useful tool that can be used to identify the most critical of these, so that housing and blade stiffness can be adjusted to change any resonances that might be close to forcing frequencies. Shaft critical speeds should be at least 25% above the fan operating speed, and there should be sufficient separation between other resonant and forcing frequencies to avoid excitation that might result in high vibration levels. QUALITY ASSURANCE Radiographic Blade Examination Mine fan blades are normally cast in small lots. To ensure that the castings are sound, a full radiographic examination is recommended in the highly stressed lower 1/3 of the blade.

Jan 1, 1995

By M. H. Harrington

The Transaclions of the Institute afford abundant evidence of the general recognition by mining engineers of the importance of a safety-lamp which will not only give warning of the presence of fire-damp, but will also indicate the proportion in which it is present.' Mining-men are only too familiar with the frequent and sudden changes that habitually occur at the working-face of a gaseous mine. Nothing illustrates more forcibly the pregnant condition of the strata enfolding the seam and the seam itself, than the fact that a circulation of perhaps 150,000 cu. ft. of air

Jan 1, 1907

By G. M. Molinda

The U.S. Bureau of Mines conducted an investigation to determine the nature and frequency of coal mine roof failure beneath valleys. A mechanism for this failure and suggestions for controlling this problem are presented. Hazardous roof conditions identified in some mines were positively correlated with mining activities beneath stream valleys. Mine maps with overlays of unstable roof and locations of stream valleys show that 52 pct of the instances of all unstable roof in the surveyed mines occurred directly beneath the bottom-most part of the valley. The survey also showed that broad, flat-bottomed valleys were more likely to be sites of hazardous roof than narrow-bottomed valleys. Evidence of valley stress relief was found beneath several valleys in the form of bedding plane faults and low-angle thrust faults. This type of failure, previously believed to be only a shallow phenomena, was found at mining depths as great as 300 ft. In situ, horizontal stress measurements beneath a valley and the adjacent hillsides, confirmed valley stress relief. Numerical analysis of 13 valleys overlying one mine property showed the effect of the valley excavation on horizontal and vertical stress.

Jan 1, 2010

By A. R. T. Denues

[Liquid oxygen explosives are ordinarily made from a carbonaceous absorbent and from liquid oxygen of high purity. These explosives have a limited but definite field of usefulness; their properties have been described in the literature, which includes several publications of the Bureau of Mines, the most recent dealing with fire-retardant treatments.3/ It seems generally conceded that the outstanding hazards in the use of these explosives are their high inflammability and their relative sensitivity to mechanical action. Each of these topics has been studied, and some interesting practical results have been obtained. Treatments have been described that render liquid-oxygen explosives prepared from granular carbonaceous absorbents practically immune to the action of igniting agents representing or exceeding practical hazards in violence.]

Jan 1, 1941

By Tianjiao Luo

Some literatures discussed on how to recycle the various reagent, but the discussion on how to reuse the waste liquid directly is very little. How to reuse the waste liquid directly was researched in this paper. Firstly, the waste liquid should be filtrated to remove the impurity; then some quantity of H2O2 solution was dripped into the waste liquid to pretreat it; finally, CuSO4solution was added into the treated waste liquid and the pH was adjusted to about 12, then some HCHO solution was added into the waste liquid, in which the treated carbon fiber can be plated. The morphology and composition of coatings were investigated by means of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), the deposition rate was mensurated by the way of dissolution. The results indicated that, the plating effect was basically identical with new plating solution, and the solution is stable, and the plating rate is still about 0.8µm/h, and the copper coating is even and combines closely with carbon fiber. According to this way, the waste liquid can be reuse 5~7 times.

Jan 1, 2006

By G. Karahalios

Industrial minerals always play an important part in the technological growth of a country. The extraction and trading of industrial minerals continues to expand, but the industry is now subject to stricter environmental guidelines. This paper presents the current status and growth potential of industrial mineral exploitation in the southeastern European region, i.e. Albania, Bosnia-Herzegovina, Bulgaria, Croatia, the Former Yugoslav Republic of Macedonia, Greece, Italy, Serbia and Montenegro, Slovenia and Turkey. Annual production figures per country are presented for 1992-1998. These figures are compared to each other, and, where applicable, they are compared to world production figures. The marketing of industrial minerals to Europe and other regions of the world and the effects of such trade on the local economies are also evaluated when such data are available.

Jan 1, 2000

By J. C. Motz

Introduction The variations in crushing plant design seen during the past 30 years provide a valuable source of information and experience from which one can select the optimum arrangement for a specific requirement. The purpose of this paper is to examine some specific equipment configurations as they relate to operating efficiency, plant availability and final product size in the form of mill feed. Due to the varied ore properties, physical space limitations, size of ore body and financial resources, there is no single crushing or grinding flowsheet that is best. Since energy costs have risen dramatically during the recent past, it became obvious that significant savings are possible by selecting equipment and a circuit which offers low power requirements balanced with low wear metal and installed equipment costs. Relatively clear and measurable are the metal and maintenance costs and the ever increasing cost of energy. Metal costs in the form of crusher liners have not quite doubled in the last 20 years, while power costs have increased by a factor of four or five, depending on the region considered. Estimates made only a few years ago on the increased cost of energy are obsolete in view of the recent unstable conditions. Since power is therefore becoming the largest cost area, it behooves us to investigate potential cost saving methods in the form of lowering the KWH/Ton of crude. Crushing To reduce run-of-mine to mill feed requires reduction in a series of stages. The physical size and power requirements of a crusher capable of reducing hard rock vary depending on the application. Extended experience in most crushing plants show that a minus 19MM (3/4 in.) rod mill feed can be and is being produced in three stages of crushing. In the majority of cases, the last crushing stage is closed circuited using anywhere from 19MM (3/4 in.) to 14MM (9/16 in.) slotted openings on the sizing deck. In some copper concentrators, the mill feed is all passing 13MM (1/2 in.) using three stages of crushing and 14MM (9/16 in.) square openings on the closed circuit screens. It was felt by some that crushing to this fine size is only possible if the ore is friable and is relatively soft in comparison to the harder ores. Our results show that some of the copper ores are as hard as taconite and are crush-

Jan 1, 1982

By Theron Wasson

The Central Michigan area held first place in the state during the year. Midland and Isabella, the leading counties in 1932, produced most of the oil in 1933. The Porter field southeast of Mt. Pleasant and along the same structural trend saw the greatest drilling activity. In Porter during the year 117 new wells were drilled. Under proration these wells produced 3,583,617 bbl., or nearly one-half the total for the state, which has been estimated at 7,947,695 bbl. The Porter field is already outlined on all sides except the northwest. It probably reached its peak in 1933. Unless a new field of some magnitude is developed in 1934, Michigan will see a continuous decline. The Greendale extension to the old Mt. Pleasant field furnished the new flush for 1932. In 1933

Jan 1, 1934

By J. Y. Foley, K. Eden, A. E. Grosz, C. J. Giles, J. E. Grosz

"Portions of the Icy Cape placer Au district have been described and exploited since the early 1900s. Industrial studies of Au-bearing garnetrich intervals established a 3.5 million troy ounce resource in the western half of the district. This estimate is not compliant with CIM and SME definition standards for Mineral Resources and Mineral Reserves. We note high variability in the textures of sediments and their heavy mineral (HM) content and composition in the district, probably as a function of the depositional environment. Sediments are medium- to fine-grained sands with a valuable HM assemblage that averages 26.0% in a range of 1.1– 72.6%. Valuable heavy minerals (VHMs) garnet, magnetite, ilmenite, rutile, and zircon, but excluding Au, average 7.9% in a range of 1.0–37.6% of the HM assemblage. Trace quantities of uraninite, thorite, monazite, xenotime, and others are noted. Garnets have an average Y content of 726 ppm with a range of 0–2150 ppm. Energy-dispersive X-ray fluorescence confirms compositions commensurate with Ca, Al, and Mg silicates. We provide empirical analytical data and note high variability in the textures, HM content, and compositions as a probable function of depositional environment. Icy Cape District land and resources are owned by the Alaska Mental Health Trust Authority and managed by the Trust Land Office (TLO). IntroductionThe Icy Cape Heavy Minerals (HM) District in Alaska subtends more than 200 km2 fronting the Pacific Ocean and backing to the foot of the Robinson Mountains at about 1700 m above sea level. We classify the district into geomorphic provinces; the eastern region as deltaic (Figure 1) and the western region as coastal plain (Figure 2), based on geomorphologic expressions. The coastal plain is entirely built up of unconsolidated outwash sediments and ancient beach sand deposits."

Jan 1, 2017