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This paper describes a proposal to reopen the Sylvia gold mine for underground exploration and development for an initial production of 10 000 tpa. A combination of trackless mining equipment and railtrack would be utilised for development with ore extraction being carried out by undercut and fill methods. The use of the smallest LHD units for mucking, and rail track for the main haulage together with airleg drilling will form the basis for development and stoping. The proposal has been subjected to an environmental impact assessment report to evaluate the impacts of the proposal on the natural and social environment in the area.

Jan 1, 1987

By E. R. Cole

Laboratory heats of an 80 percent copper high-leaded tin-bronze alloy, similar to Brass and Bronze Ingot Institute (BBII) alloy 3A, were made with reduced tin content to determine whether an alloy comparable to BBII alloy 3A could be produced using less tin to aid in conserving this strategic metal. The tin content was lowered from 10 percent to 8 percent and 5 percent (nominal values), respectively, and the reduction in tin was offset by either increasing the lead content or adding zinc. Mechanical properties, machinability, and corrosion characteristics of the resultant alloys were investigated, and the mechanical properties were compared with BBII typical values and American Society for Testing Materials (ASTM) minimums for high-leaded tin-bronze alloy. Results indicate that the tin content of this alloy could be reduced approximately 1 percent (difference between the 8.4 percent actual tin composition obtained and the 9.3 percent BBII minimum) without seriously affecting the desired properties. Results also show the tin content could be reduced without significantly increasing the chances of rejects for mechanical property failures, which might result from normal variations in the casting process.

Jan 1, 1972

By Walter E. Pittman

In its role of providing technical assistance to the mining industry, the Bureau of Mines' Tuscaloosa Research Center has conducted research to develop trapped miner location systems which would aid in locating miners trapped by underground mining disasters. Efforts to produce electromagnetic systems for the location of trapped miners underground and to communicate with them were surveyed, from the 1920's to 1981. Theoretical studies of through-the-earth electromagnetic transmissions are described as well as studies of the electrical characteristics of various rocks, minerals, and soil. Several trapped miner location systems are reviewed including the Westinghouse systems, the DEVELCO system, and an automated three-dimensional location system, and the phase difference of arrival technique. Tangential research, relevant to trapped miner location systems is described. A comprehensive bibliography covering all aspects of trapped miner, through-the-earth electromagnetic location and communications systems is appended.

Jan 1, 1982

Provide long-term measurement of mine sidewall closure in backfilled stapes subject to flooding. Approach A water resistant extensometer is made by enclosing a rod-actuated transducer in a telescoping tube which is enclosed within an oil-filled outer housing. How It Works To assemble a water resistant extensometer, a cylinder -shaped transducer and two support rings are pushed into the small-diameter section of the telescoping tube where the transducer is held in place by friction. The outside of the small-diameter section of the telescoping tube is then greased and slid into the slightly larger-diameter section. See drawing. The cylinder-shaped transducer contains a potentiometer whose actuating arm is attached to a stainless steel extension rod that passes through one end of the telescoping tube. A similar rod is attached to the opposite end of the transducer body, and extends through the other end of the telescoping tube. A coil spring inside the large diameter end of the telescoping tube extends the tube

Jan 1, 1978

By Benoît Demers

Dans ses opérations de traitement de concentré de zinc, l?usine de Zinc Électrolytique du Canada à Valleyfield génère un résidu minier appelé « jarosite ». Jusqu?en 1998, le jarosite était transporté hydrauliquement dans des bassins construits en argile. Le jarosite sédimenté possède une consistance très molle (impossible de circuler à pied sur le résidu consolidé) avec une eau interstitielle acide contenant des teneurs élevées en métaux. Ces caractéristiques particulières au jarosite rendaient très coûteuses la construction et la fermeture des bassins de résidus. En 1998, Zinc Électrolytique du Canada a implanté un nouveau procédé, développé chez Noranda, dont le principal objectif était de stabiliser chimiquement et physiquement le jarosite. Un nouveau concept de déposition a été élaboré pour le nouveau résidu minier appelé « jarofix ». Les grandes caractéristiques du nouveau procédé et du concept de déposition sont : ? Le jarosite est lavé et déshydraté à l?usine avec un système de filtre; ? De la chaux, du ciment et de l?eau sont ajoutés pour former le jarofix; ? Le jarofix est transporté par camions jusqu?à l?aire d?accumulation; ? À l?aire d?accumulation, le résidu est géré selon un concept d?empilement. L?élaboration du concept d?empilement et de l?aire d?accumulation devait tenir compte des caractéristiques de déposition du jarofix, de sa résistance à l?érosion hydrique et éolienne, de la gestion de l?eau de ruissellement, de la faisabilité de construire les digues de ceinture en utilisant du jarofix durci et de la nécessité de restaurer progressivement l?aire d?accumulation. Le déchargement du jarofix se fait à partir d?une rampe qui progresse avec une pente ascendante pour développer un front de déversement de plus en plus haut. La hauteur du tas de jarofix atteindra 30 m au centre du site. L?aménagement initial de 1998 a inclut une digue d?amorce de 3 m de hauteur, une rampe de déversement de 8 m de hauteur et un bassin pour la gestion de l?eau de ruissellement. Les propriétés du jarofix consolidé dans l?aire d?accumulation sont déterminées annuellement. Le jarofix durci possède la consistance et la résistance d?une argile très raide. Sa conductivité hydraulique est similaire à celle d?un silt et il résiste bien à l?érosion éolienne. Après trois années de déposition, la température du jarofix au milieu du dépôt demeure élevée. Le jarofix durci est facile à excaver et à compacter, ce qui en fait un excellent matériau pour la construction des digues de ceinture en périphérie du site.

Nov 1, 2002

By Mutombo Nombe, Avimanyu Das, Rick Honaker

Enhanced gravity separators (EGS) provide a more efficient separation than froth flotation when cleaning coal in the 150 x 25 µm particle size range. To improve the performance of an EGS unit, air bubbles were injected into the feed stream in an attempt to decrease the apparent density of the coal particles due to the formation of bubble-coal particle agglomerates. Air injection had a significant impact on operating characteristics and separation performance. Coal recovery was increased by 10 to 20 absolute percentage points while a 2 percentage point drop in the minimum product ash content was also achieved.

Jan 1, 2005

By L. H. Banning

This investigation was undertaken to obtain basic information necessary for the design and operation of a plant for recovering metallic values from nickeliferous laterite and serpentine of the Philippine Islands. It was divided into three parts: (1) Mineralogical studies and preliminary mineral dressing tests; (2) electric smelting of the ores, upgrading of ferronickel by blowing with oxygen, smelting laterite slag to produce crude iron, and the production of mild steel; and (3) nickel and cobalt recovery from upgraded ferronickel. Results of the investigation indicate that it should be feasible to recover nickel, iron, and possibly cobalt products from the laterite and ferro-nickel from the serpentine. Mineralogical studies were made on representative fractions of the laterite and serpentine tonnage samples and on five selected samples; mineral dressing tests were made only on laterite. The nickel occurs principally associated with hydrous iron oxides and chemically combined with serpentine; garnierite was the only discrete nickel mineral identified, and it was found in a highly decomposed serpentine. The bulk of the cobalt was found in wadlike manganese oxide material. Approximately twice as much chromite was found in the laterite as in the serpentine, By mineral dressing techniques, laterite was separated into two fractions: one fraction contained over 90 percent of the nickel and cobalt, and 83 percent of the iron; the other fraction contained 74 percent of the chromium. A cobalt concentrate (1.1 percent Co) was produced by a scrubbing and sizing procedure.

Jan 1, 1962

By Steven I. Majtenyi

There is a growing interest among transportation planners to make more use of the subsurface to preserve the landscape and make transportation more efficient and economical. At the present time, utilization of the underground for transportation facilities is severely restrained by the adverse environmental impact and high construction costs. However, recent studies performed by the United States Department of Transportation indicate that, in spite of such problems, the volume of underground construction has significantly increased during recent years and projections point to continuation of these trends(1). It is estimated that the total volume of transportation tunnel construction will exceed $4 billion in this decade. This level of Investment justifies a significant research program. Due to the common interest in transportation tunnels and to the similarities of problems encountered during their construction, the tunneling research activities of the Federal Highway Administration (FHWA) are closely coordinated with the programs other agencies of the U. S. Department of Transportation DOT); specifically, the Federal Railroad Administration (PRA) and the Urban mass Transportation Administration (UMTA). The FHWA is responsive to the particular needs of these agencies but will benefit from the research results obtained also. In 1971, the Office of Secretary, DOT, initiated plans for an overall coordination of the DOT, FICA, UMTA, and FHWA tunneling research activities. The objectives of this effort have been to reduce tunneling costs by 30% and to increase the rate of excavation by 200% within 10 years. This coordinated program was developed and promoted during 1972 and 1973 by Dr. Eugene L. Foster, at that

Jan 1, 1974

By Gustavo Henrique Bolognesi Donato

A utilização de materiais cerâmicos em componentes que operam em elevadas temperaturas (p. ex.: trocadores de calor cerâmicos que operam acima de 800°C) é vantajosa do ponto de vista térmico, mas não é trivial em termos estruturais, uma vez que estes materiais são frágeis e portanto, suscetíveis à fratura catastrófica. Considerando a necessidade de materiais resistentes a elevadas temperaturas e que garantam a integridade de aplicações como tais trocadores de calor, este trabalho investiga as propriedades mecânicas da alumina a (Al2O3) como função da temperatura na faixa de 23°C a 850°C. Para tal, cem ensaios de flexão em 4 pontos e ensaios adicionais selecionados em 3 pontos foram realizados em amostras de seção transversal retangular de ~ 45 mm2 produzidas por gelcasting, técnica esta que tem grande potencial para moldar peças de geometria complexa. Os ensaios foram conduzidos empregando um dispositivo fabricado em Inconel (superliga de Níquel-Cromo) especialmente desenvolvido para esta finalidade e contendo articulações objetivando autocompensação de desalinhamentos. Os resultados experimentais puderam ser muito bem descritos usando a estatística biparamétrica de Weibull e demonstram o efeito da temperatura na redução da resistência à flexão. Adicionalmente, o dispositivo proposto facilitou e dinamizou a realização dos ensaios, além de garantir pequena dispersão das propriedades mecânicas obtidas, especialmente se considerado o micromecanismo frágil de fraturamento desta classe de materiais.

Aug 8, 2018

By J. L. Robson, C. M. Bristow

mass flow rates of particles and air (the loading ratio).

Dec 1, 1994

By X. Cao

Friction stir processing (FSP) is used to produce wrought microstructures at the surface of sand-cast aerospace grade magnesium alloy ZE41A-T5. It is found that the microstructure is significantly refined in the stir zone and the flow arm. The stir zone is largely comprised of equiaxed magnesium grains of approximately 4.5 pm compared with about 50 µm in the base cast material. In the stir zone, however, abnormal growth of some grains is also observed. Vickers microindentation hardness tests indicated that the stir zone experiences some increases in hardness. Single surface passes with low distortion, lack of pores and cracks were successfully obtained indicating the great potential of the FSP technique for modifying, improving and repairing magnesium alloy castings. This will probably open new opportunities to apply magnesium alloys in aerospace industry.

Jan 1, 2007

By S. J. Hussey

This Bureau of Mines report presents a discussion of the statistical approach to the design of experiments and indicates, by concrete examples, how and when statistical design is essential for obtaining meaningful data with a minimum number of experiments. Every research worker plans his work and designs his experiments in a manner which, based on his experience, seems most rational to him and which he believes will produce the information essential for resolving the problems. If the results obtained are open to multiple interpretations and are not of definitive reliability, the failure of the experiment design to produce the desired information may be due to several causes, These include faulty judgment in selecting the factors to be tested, ignoring the importance of interaction between factors, failure to adequately control test variables, and assuming that meaningful trends in the results can be identified without comparison to a predetermined experimental error. An experienced researcher probably will deduce from the nature of the data obtained that the design is faulty and may by trial and error ultimately arrive at the correct solution to the problem. Statistical methods of planning research minimize the chance of faulty experiment design, embody concrete procedures for testing the validity and reliability of the test data and for indicating mandatory changes in the design, and enable the researcher to obtain meaningful information with the least number of tests.

Jan 1, 1963

By David L. Anderson

"The government o f Canada has, since 1981, been under intense political pressure to modify its foreign direct investment (FOI) regulatory regime(1). To date the government's response has been limited to administrative and ""cosmetic"" changes: substantive issues have been largely ignored(2). However, as long as the economy continues to flounder , the Foreign Investment Review Agency (FIRA), as it is presently formulated , will continue to be an easy target for government critics . This phenomenon, in conjunction with the virtual certainty of a federal general election within two years, suggests that changes to the FIR Act will be seriously entertained by the present government.Recent events indicate that if change s are made, they will likely entail the adoption of a special-sector approach within the existing framework of a general screening system(3). Since this approach is currently employed in Australia(4), it would seem to be appropriate, from a public policy perspective to study that country's experience in developing and operating such a scheme. In doing so, I shall focus on the mineral sector; the rationale for doing so is as follows. First, this sector served as the focal point of the Australian FOI regulatory debater(5), Second , with the exception of the oil and gas industries, the non-petroleum mineral sector is one of the few areas of the Canadian economy wherein the Trudeau government has adopted an explicit domestic ownership target(6). Third, the non-petroleum mineral sector is, undoubtedly, a prime candidate to be denoted a s a special-sector if such a framework were to be utilized by the Canadian government!"".Although international comparisons are fraught with danger , a Canadian/Australian comparison is particularly appropriate(8). Both countries have reasonably similar economic, political and social structures . Furthermore, as noted above , Australia is the only other western country which employs a general screening mechanism for FOI. In addition, it utilizes a special area approach ; within this scheme, an explicit target of a minimum of 50% Australian ownership of all new resource projects has been formulated and clearly promulgated to all of the relevant interest groups. This policy, broadly defined, has been in place for more than six years and during this time the Australian mineral sector has, by world standards, prospered(9). Hence, the Australian experience in designating the mineral sector as a key area within a general screening system, should be of interest to Canadian policy-makers."

Jan 1, 1984

By H. Brandhorst, C. G. Dunn

THE main purpose of the present note is to provide further information on the effect of orientation on strain-induced grain boundary migration in sheet material. A secondary purpose is to draw attention to the presence of a possible (hkl) dependent surface energy driving force, when the two grains of a bicrystal specimen have different (hk2) planes at the gas-metal interface, and to suggest means of eliminating this effect from the strain effect. If two grains A and B of a bicrystal have specific surface energies ? A and ? B respectively, there exists a driving force for grain boundary migration equal to 2(? B - ? A)/t, where t is the thickness of the specimen.' When t is quite small and the residual strain energy densities €A and €B of grains A and B, respectively, adjacent to the boundary are nearly equal, it is possible that the surface effect may be larger than the strain effect. he difference € B - € A gives a driving force per unit area of grain boundary due to an applied strain.)2 However, with increasing t the surface effect decreases while the strain effect presumably remains constant. Therefore, at some sufficiently large value of t, it is possible to ignore surface energy driving forces.* On the other hand, the surface effect is eliminated for all value of t when both grains have the same (hkl) orientation or have identical values of surface energy. Although the previous study provided information on the effect of orientation on strain-induced erain boundary migration,' no orientations with the (100) plane in the plane of the sheet were included. The present paper provides information of this kind. A seed crystal reorientation technique4 was used to prepare a large bicrystal of silicon iron (3 1/4 pct Si) consisting of two (100) grains in the (100) [001] and (100) [Oil] orientations. After a cold rolling strain (7 pct reduction to 3/4 mm final thickness), small specimens were prepared as before2 and then annealed in hydrogen. The boundary migration was such that the grain in the (100) [011] orientation always grew. After overnight anneals at 1100° or 1000°C, none of the initial (100) [001] grain remained. An anneal of 30 min at 950°c, however, provided information on the start of boundary migration. Fig. 1 shows both the initial position (lower line) and the final position (upper curved line) of part of the boundary, as revealed by thermal grooves. In a different area, part of the final boundary was not revealed by thermal grooves; the rate of boundary migration presumably was too high for the growth front to be defined by the time dependent thermal grooving process. In another area there was a vacated intermediate position connected to the initial position of the grain boundary. This indicates that only part of the boundary

Jan 1, 1962

By R. A. Vik

The influence of thermal treatments on the grindability of low-grade hematitic iron ores from Michigan and Minnesota was examined in bench-scale tests. Treatment factors were roasting temperature, roasting atmosphere, and ore cooling conditions. Bond ball mill grindability and work indices were used as response indicators in evaluating the condition of the ore. Of the three treatment factors evaluated, roasting atmosphere, which brought about the con version of iron oxides to magnetite, had the most significant effect; roasting temperature had the next most important effect; and cooling condition had the least effect. Optimum grindability was obtained with reduced-quenched products of both ores at 650° C, near the alpha-beta phase transformation of quartz.

Jan 1, 1971

By W. T. Abel

The rate of the steam-carbon reaction, which is of fundamental importance to coal gasification, was determined by passing steam over graphite specimens suspended in an electrically heated tube. The measurements were made at 1,900° to 2,400° F. and at steam-feed rates of 0.1 to 2.0 moles of steam per mole of carbon per minute. At the maximum steam-feed rate, the reaction rate of carbon ranged from 0.4 percent per minute at 1,900° F. to 7 percent per minute at 2,400° F. Up to about 2,200° F., the steam-feed rate had only a slight effect; above this temperature, it limited the reaction velocity when the final mole fraction of steam in the reaction products was much less than 1.

Jan 1, 1962

By Jack Kadlecik

This final technical report describes the concept feasibility study, testing, design and development effort which went into. The quick opening enclosure access cover and flame path tolerance checking system. A detailed definition of the explosion-proof multiple start threads is shown for two (2) sized electrical enclosures.

Jan 1, 1972

By Terry R. Neumann

During 1984, at the request of the U. S. Bureau of Land Management, U.S. Bureau of Mines personnel conducted a mineral survey of the 28,600-acre South Pahroc Range Wilderness Study Area (NV-050-0132). The Wit derness Study Area is located in Lincoln County, NV, about 900 miles north of Las Vegas. Five mineral properties and two mineralized zones were examined during this study; of these, one mineralized zone, two small prospect pits, and part of two claims are within Wilderness Study Area boundaries. Perlite resources were identified in the study area; however, no significant metallic mineral values were noted at any of the sites. The Wilderness Study Area is dominated by a Tertiary volcanic sequence consisting of an interlayered series of tuffs containing thin beds of volcanic pebble gravel, sandstone, and perlite. At the base of the exposed volcanic section, perlite occurs along a 2.4-mile-long zone that parallel s the study area's northeastern boundary. The perlite is suitable for filtration, insulation, and soil conditioning purposes, Because of prohibitive operation and transportation costs, the estimated 6 million tons of perlite occurring inside the South Pahroc Range Wilderness Study Area are classified as an indicated subeconomic resource.

Jan 1, 1986

By Walter R. Hibbard

THE increased strength of a polycrystal-line metallic aggregate compared with that of its individual crystals generally has been associated with complex stress distributions at the grain boundaries resulting from atomic irregularity between grains. This disregistry, together with the necessity for adjacent crystals to deform 'compatibly regardless of the single crystal crystallographic strain mechanism, complicates this mechanism so as to increase the metal's resistance to deformation. Although Taylor1 has shown from purely mechanical considerations the requirement for at least five active slip systems to absorb the complexities during the homogeneous deformation of polycrystalline face-centered cubic metals, experimental studies by Barrett and Levenson2 indicate that this is feasible only in a qualitative sense because of deviations from homogeneous deformation. Seitz and Read in their review3 state: "Unfortunately . . . present knowledge of the grain boundary influence is not sufficient to complement the work in single crystals and provide us with a good foundation for treating polycrystals." The purpose of this investigation was to attempt to clarify the gap between single crystals and crystalline aggregates by an analysis of the effects of deformational stresses. Some of the results were described by C. H. Mathewson in his 1943 Campbell Memorial Lecture.21 PREVIOUS INVESTIGATIONS Since the performance of single crystals deformed under pure stresses has been relatively thoroughly investigated, the most significant researches are concerned primarily with deviations from single crystal behavior of large grained specimens. Qualitative grain boundary effects involving the observed amount of slip were reported by Carpenter and Elam5 in 1921. Individual crystals in a two or three grained aluminum specimen deformed by tension acted in the normal manner described by Taylor and Elam4 except for marked modifications at the grain boundaries. There the power to withstand deformation was considerably increased, leaving a ridge on the specimen where decreased slip occurred, often noticeable 34 in: from the boundary. Adcock,6 Yamaguchi,7 Seumel,8 Hirst9 and others have also reported this phenomenon as a qualitative trend. Yet attempts by O'Neill10 and Ljunggren11 to measure a difference in hardness at grain boundaries in undeformed specimens were unsuccessful. Miller12 measured quantitatively the reduction in slip near the boundary between the single crystal and polycrystalline areas of zinc specimens. These effects consisted of two parts: I. Next to the polycrystalline interface the distribution of stresses was so altered

Jan 1, 1948

By M. Drozd, M. Somppi, Z. Yamak

"Granular activated carbon is widely used in the gold mining industry for gold extraction from aurocyanide-containing slurry. The extraction process can employ carbon as part of the gold recovery operation for various circuit designs including carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) circuits. However, various qualities of activated carbon exist and the durability of the material can change significantly from source to source. Handling this expensive reagent can pose challenges when fine carbon losses occur in the CIP, CIC, and CIL circuits. Additionally, any gold that is adsorbed to these carbon fines can also be lost by various mechanisms including carbon attrition and fracturing, inefficient coarse-fine separation, and poor carbon fines capture. With the above in mind, a series of tests were conducted to investigate standardizing simple laboratory methods for testing carbon quality. A standard procedure beyond or enhancing ASTM methods can serve as additional starting points for evaluating carbon specific to the gold industry. The investigation focused on size distribution, flatness, wet attrition resistance, surface area, gold kinetics, and gold loading. The final results provided information to generate an equation for ranking carbon samples to plant performance.IntroductionActivated carbon for use in gold extraction is amongst the most commonly found processes in modern gold-milling plants. Although gold losses are inevitable in the milling process, operators often focus on the importance of maximizing gold recovery. One focus area that is important in gold recovery is optimizing the use of activated carbon and examining potential changes to realize improved economics for carbon-in-pulp (CIP), carbon-in-column (CIC), and carbon-in-leach (CIL) processes."

Jan 1, 2017