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By Louis J. Cabri, Donald Hoy

"Samples with contrasting gold mineralization were studied quantitatively prior to metallurgical tests. The AD samples are coarser-grained and characterized by abundant Sb minerals (jamesonite, berthierite, stibnite). The finer-grained MW sample has abundant pyrite and pyrrhotite, with arsenopyrite and galena next in abundance. A large number of gold mineral particles were determined by SEM investigation of hydroseparation concentrates, ranging from 150 to 597 per sample. The grain-size distribution of the gold minerals shows evidence of bimodal grain-size distributions (volume %), with the coarse fraction being most significant in sample MW-1 (maximum ECD=308µm). The coarsest gold minerals in the AD samples range from 139µm to 281µm ECD.The deportment of gold minerals is as electrum, aurostibite, native gold, and a possible new mineral (AuNiSb4). Gold also occurs in nisbite. The gold minerals are dominated by electrum in three samples and aurostibite is next in abundance. The major gold minerals are probably representative of three stages of gold mineralization. The first stage is represented by electrum, which is partly to completely replaced by Sb-rich mineralization forming aurostibite, and the last stage is native gold, often occurring as rims on one or the other earlier gold mineral. The gold minerals are strongly associated with sulphides in the AD samples (55 to 60 vol.%). At the grind used for the hydroseparation the liberated gold mineral quantity (volume %) is also significant, ranging from 65% for sample MW-1 to 30 to 37% for the AD samples.INTRODUCTIONThe Clarence Stream deposit is located 70 km south-southwest of Fredericton and 25 km northnorthwest of St. George, south-western New Brunswick, near the international boundary with Maine (Fig. 1)."

Jan 1, 2007

By P. Nicholls

THOUGH the burning of fuels extends far back into antiquity, and though fuel beds are the most common and widely distributed example of chemical actions and engineering practice, there has been little attempt to group fuel beds by types or to define the principles associated with them. This paper does not profess to cover completely the subject of fuel beds. It suggests some of the over-all principles of the two more com-mon types. No new investigational data are included, but the deduc-tions are largely based on a recent publication of the U.S. Bureau of Mines1. DEFINITION OF TYPES There are three primary types of fuel beds: (1) Underfeed, in which the fuel and the air move in the same direction; (2) overfeed, in which the fuel and the air move in opposite directions; (3) crossfeed, in .which the fuel and the air move at right angles to each other. The principle that fixes the type is the relation between directions of the flow of fuel and of air. Fig. 1 shows the three types diagrammatically. All other types are compounded of these three in a simple or more or less complex manner. It does not follow that these three type designations are limited to the methods used in representing them in Fig. 1; they may be turned in any direction, and as long as the relative directions of the fuel and air are the same the type is not changed. For example, A as shown resembles a pot-type stoker, but the air and fuel can move downward as in the so-called smokeless heating boiler furnace. Also, C can be placed hori-zontal, as in chain-grate stokers. For this reason, the terms used to designate the three types are not all that could be desired; more logical ones could be coined, but those used probably are satisfactory until the discussion of fuel-bed types becomes more common.

Jan 1, 1935

By N. Arbiter, C. C. Harris

The economic advantages of large diameter ball mills can be compromised by unexpected capacity limiting conditions. These arise because media rotational flow to ore axial flow ratios, and the number of mill revolutions that ore is subjected to during residence, are both inversely proportional to mill diameter. Because of this, mixing efficiency and grinding kinetics may decrease and become capacity limiting when mill diameters reach a critical range. There are two possible scale-up problems involved in the design and use of mineral processing machinery: • Selecting the size and operating conditions for available larger equipment, to insure that operating results will match those obtained with smaller units; or •Extending the size ranges of equipment beyond existing limits. Previous research at Columbia University into flotation machine hydrodynamics has demonstrated the importance in scale-up of internal flow relationships; these perform a similar role in grinding (Arbiter and Harris, 1980).

Jan 1, 1982

By Peter Fullagar, Adel Vatandoost, Steve Walters, Toni Kojovic

"Traditional comminution tests are a vital component in every mine plant design. Comminution behavior governs both the cost of equipment and its operating efficiency. Most comminution tests are conducted off site on a limited number of samples, owing to the high costs and long lead times involved. Therefore a strong incentive exists to find alternative means for efficiently characterizing comminution behavior for a truly representative suite of samples. The potential for inferring comminution behavior from drill core is investigated in this paper. Our approach involves development of small scale comminution tests on the one hand, and measurement of a wide range of core attributes on the other. Our focus is the relationship between petrophysical properties and comminution behavior.Petrophysical properties of archival diamond drill core from the Ernest Henry Mine (Queensland, Australia) have been measured using a Geotek multi-sensor petrophysical core logger. We have investigated the relationship between the petrophysical properties and the corresponding small scale A*b and estimated Bond mill work index test results for 2m composites of the core. Core samples were petrophysically classified by means of cluster analysis. Comminution behaviour was then modeled for each cluster via multiple regression. The results suggest that prediction of the comminution behavior on the basis of petrophysics is viable at Ernest Henry.INTRODUCTIONMineral processing is the most important downstream operation for mining engineers and metallurgists since most mined materials are subjected to some type of comminution or beneficiation operation (SME, 1992). Comminution or size reduction is typically the first stage of processing. Size reduction steps (crushing and grinding) in any plant consume large amounts of energy, normally more than 50% of total energy (Weiss, 1985). Therefore, it is desirable to obtain laboratory results to design the size reduction equipment appropriately. One of the main factors that control the selection of hard-rock crushing equipment and the design of a crushing circuit is the mechanical character of the ore(s). Work index, density, abrasivity, compressive strength and clay content are essential parameters for ore characterisation (SME, 1992)."

Jan 1, 2009

By W. A. Wood, H. M. Bendler

Cylindrical fatigue specimens of OFHC* copper were subjected to alternating torsion while under axial tension. The superimposed tension strongly influenced the fatigue life of the specimens as well as causing characteristic changes in the structure of the fissures that form and develop throughout the life of the specimen. A further effect of the superimposed tension is a continuous extension of the specimen throughout its life in a manner formally similar to creep at elevated temperatures. RECENTLY, studies of the structural changes leading to fracture of metals by fatigue have been made by a technique which reveals, in section, the lattice distortion arising from slip movements inside the metal and the disturbances built up by these slip movements at the metal surface.1'2 According to this approach, fatigue develops as follows: a) fine slip movements concentrate in bands, producing little strain-hardening and thus permitting abnormal totals of plastic strain before fracture and, therefore, abnormal amounts of lattice distortion along each slip band; b) both forward and backward slip movements occur in each band which, according to their distribution across the band, may build up surface disturbances that include sharp notches; c) these notches early in the life of a specimen penetrate the distorted slip zones and transform them into deep, fine fissures; d) the fissures on continued cycling locally saturate the metal and cause local collapse in the form of a microcrack. Thus, the significant consequence of fatigue or cyclic

Jan 1, 1962

By David Harrison, Edward J. Walter, Meitra Ferek

Agreat tool in the prevention of blasting complaints and subsequent damage claims. In today’s highly competitive industry, we are always looking for ways to become more cost effective. This article investigates the importance of pre-blast surveys-not just for regulatory compliance, but as an overall long term cost cutting and public relations tool.

Jan 1, 1995

By Joseph Irons, David Westfall

Three rock tunnel sewer systems are underway in the Chicago Area. (Figure 1) The three are designed to act independently and to be later connected to the future tunnels of the master plan. The tunnel excavation for each of the systems has been completed. One is in the Northwest area within the City being built by the City, known as the Lawrence Ave. System. Another is in the Southwest suburbs, known as the LaGrange-Brookfield Sewer or Southwest 13A, being built by the Sanitary District, the third is in the South suburbs called the Crawford Avenue sewer or Calumet 18-E, Ext. A- being built as a joint venture between the City and the District. The three are similar in that they have the same purpose, the same component parts and their tunnels were constructed in the nigaran limestone using a mechanical mining machine. The purpose of each of the systems is two-fold. First to provide flood relief for existing inadequate sewer systems, and second to reduce the pollution load to the waterways caused by combined sewer overflows. The existing systems in the areas to be relieved are combined sewers built many years ago. The main outlet for the Village of LaGrange, for example, was built in 1908, is badly in need of repair and lacks the capacity to handle the flood flow from the heavily urbanized area it now serves. The dry weather flow from the area is taken off by intercepting sewers. However during

Jan 1, 1997

The Leuna Factory of the I. G. Farbenindustrie A. G., situated near Merseburg, is the biggest heavy-chemical plant in Germany and produces a very wide range of products, mainly based on hydrogen or hydrogen and carbon monoxide. Its principal products are ammonia, synthetic petrol derived from the hydrogenation of brown coal, and synthetic alcohols made from hydrogen and carbon monoxide. The plant was first, visited on April 21, 1945, by a team including E. Cotton, V. Haensel, E. B. Peck, P. K. Kuhne, H. M. Weir, L. L. Hirst, W. W. Odell, G. U. Hopton, H. Hollings, J. F. Ellis, and H. G. Simpson. It was again visited on May 8-24, 1945, by a combined British and American team consisting of R, Holroyd, M. A. G, Banks, D. A. Howes, A. J. V. Underwood, R. A. Taylor, W. F. Faragher, H. Schindler, and J. G. Allen. This team was later joined by J. F. Ellis and R. J. Morley. A third visit with particular reference to catalyst manufacture was made by W. F. Faragher and W. A. Horne, and the notes of these latest investigators have been taken into account in preparing the report. This report was edited by Dr. R. Holroyd.

Jan 1, 1946

By Rafael Humberto Mota de Siqueira

A conformação a laser (Laser Beam Forming – LBF) é um processo mecânico sem contato realizado pela introdução de tensões térmicas na superfície de um material com laser, a fim de induzir a deformação plástica. Neste estudo, foram realizadas conformações em chapas de 1,6 mm de espessura, de alumínio de alta resistência, classe AA6013-T4, com uso de um laser de Yb-fibra operando em modo contínuo. A potência do laser foi variada entre 200 e 1000 W e a velocidade entre 3 e 30 mm/s, com o feixe desfocalizado em 5 mm sobre a superfície da chapa. O ângulo de dobramento das chapas variou entre 0,1 e 2,5° por passe, dependendo das condições experimentais. Na condição de maior ângulo, 1000 W e 30 mm/s, a poça de fusão atingiu 0,6 mm de profundidade, porém sem alterar a microestrutura da parte inferior da chapa. Em todas as condições, a dureza se manteve constante em aproximadamente 100 HV, sendo semelhante ao material de base. Para verificar a aplicabilidade do método, foram desempenadas chapas previamente soldadas na configuração T. O método mostrou-se eficiente em corrigir o empenamento de chapas com inclinação de até 5°.

Aug 16, 2017

By J. MacFadyen

The U.S. cement industry, including Puerto Rico, again set a record in terms of production and shipments. The increase in shipments came primarily from imports of portland cement as domestic production from produced and imported clinker gained only 1.9 Mt (2.1 million st). Clinker production as reported to the U.S. Geological Survey (USGS) was 88.6 Mt (97.6 million st), an increase of 1 percent. Gray and white portland cement production from domestic and imported clinker, estimated at 93.5 Mt (103 million st), was up 1.9 Mt (2.1 million st). Masonry cement shipments of 5.5 Mt (6 million st), which equates closely to production, was up 6.3 percent. Blended ce-ment shipments were up 35.9 percent from 2004 at 2.35 Mt (2.6 million st).

Jan 1, 2006

By T. N. Williamson

Most U.S. coal production is bituminous coal. Some 90% of current production comes from a geographical area enclosed in a circle with a 300 mile radius and its center at about Huntington, West Virginia. There are important underground coal production areas in the western parts of the United States as well. Most U.S. coal production comes from fairly level seams, many of which pitch rather uniformly only a few feet per mile. Usually there will be several overlying seams of varying thicknesses, separated by several tens of feet. Fig. 1. 1. Seams have minor local undulations but these? are small enough not to be a major consideration in a horizontal drilling research program.

Jan 1, 1970

Recent and on-going studies on the leaching of gold, the properties and activity of carbon, developments in the elution of gold from carbon, and methods of recovering gold from solution are reviewed. Emphasis is placed on Australian contributions, and their impact on gold metallurgy. Consideration is given to the future development of selective solvent extractants, ion exchange resins or alternative reagents for cyanide.

Jan 1, 1987

By Gustavo Quiquia Mucha

El presente texto describe las experiencias realizadas por la Compañía Minera Milpo SAA en el marco de una gestión social basada en la consulta previa, libre e informada en la Exploración Minera Responsable. En ese sentido, es importante la cooperación entre la empresa minera y la comunidad, así como la incorporación del marco ideológico empresarial y metodológico, basado en los principios del Convenio 169 de la OIT sobre Pueblos Indígenas y Tribales en Países Independientes, las estrategias y las líneas de intervención social de la Compañía Minera Milpo SAA en los proyectos de exploración minera responsable.

Sep 12, 2011

By I. A. Mwamba

Plain and alloyed titanium aluminides of composition Ti-47.5 at.% Al were prepared by melting commercial-purity titanium and aluminium with additions of 1 at.% precious metal. The as-cast alloys were subjected to potentiodynamic scans in 5, 15, and 25 wt% HCl aqueous solutions at room temperature and compared for their abilities to spontaneously passivate. Addition of precious metals resulted in a general improvement of corrosion resistance by increasing the open circuit potential to more noble values. Addition of 1 at.% gold or silver to titanium aluminide did not significantly increase the corrosion potential (Ecorr) above that of the plain titanium aluminide alloy, indicating that gold and silver are not sufficient cathodic modifiers to improve the corrosion resistance of titanium aluminide in all the solutions tested. However, platinum, palladium, and iridium additions shifted the corrosion potentials to the position of the passive region of plain TiAl for all solution concentrations. This indicated that TiAl alloyed with these platinum group metals would passivate spontaneously by cathodic modification. TiAl alloyed with palladium performed the best in 5 wt% HCl solution with the most positive corrosion potential. In 15 wt% HCl solution, alloys with platinum exhibited the most positive corrosion potentials, while alloying with iridium or palladium revealed more negative corrosion potentials. Thus, palladium alloying led to the best cathodic modification of titanium aluminide in low-concentration HCl solution, whereas platinum and iridium alloying additions resulted in the best cathodic modification of titanium aluminide in high-concentration HCl solutions.

Jan 1, 2013

By S. Shi, J. Y. Hwang, B. Li

Silver, copper, and zinc are commonly known elements with antibacterial and antifungal capabilities. Attempts have been made to dope silver on minerals, glass, and ceramics and the resulting materials have been investigated for their antibacterial and antifungal properties. Since silver is expensive and very reactive, silver doped materials have been found inappropriate in some applications. Copper-vermiculite is investigated as an alternative. Vermiculite has high cation exchange capacity on the magnesium ion in the crystal structure. Copper ion may have a high tendency to replace magnesium because of similar charge interference and ionic radius. Copper-vermiculite is prepared by reacting vermiculite and copper chloride solution. By impregnating copper ions into the nanometer openings between the layers of vermiculite, it is possible to render the composite with antibacterial functions if the copper ions could be released gradually from the composite. The antibacterial efficiency of Cu-vermiculite against Escherichia coli was studied using the Halo method. The results show that Cu-vermiculite is effective for preventing the reproduction of the bacteria. Heat treatment of Cu-vermiculite at up to 400°C does not show significant changes in antibacterial activities.

Jan 1, 2002

The Appalachian Mountains divide Pennsylvania into two distinct coal regions, bituminous and anthracite. The western region of the the state, where the majority of bituminous mines are located, is characterized by mountains and gently rolling hills. Bituminous coal seams underlie about 12,000 square miles in 28 counties. The anthracite coal region, located in the northeast, covers approximately 3,300 square miles. This area contains more than 20 different coal beds that vary in thickness from a few inches to 50 or 60 feet. The anthracite region is characterized by steeply pitching seams that require highly specialized mining techniques and present unique challenges for solving problems such as the mine subsidence associated with abandoned underground anthracite mines. For more than a century, coal has played a major role in the economic and industrial development of Pennsylvania, particularly the steel industry. Estimated bituminous reserves total 23 billion tons, or 5.3 percent of U.S. reserves, and anthracite reserves total 7.1 billion tons, or 97 percent of U.S. anthracite reserves. Pennsylvania received conditional approval of its regulatory program July 31, 1982. Pennsylvania's Abandoned Mine Land Program was approved on the same date.

Jan 1, 1992

By Nn Li

Energy consumption in commercial buildings has been increasing rapidly in the past decade. The knowledge of future energy consumption can bring significant value to commercial building energy management. For example, prediction of energy consumption decomposition helps analyze the energy consumption patterns and efficiencies as well as waste, and identify the prime targets for energy conservation. Moreover, prediction of temporal energy consumption enables building managers to plan out the energy usage over time, shift energy usage to off-peak periods, and make more effective energy purchase plans. This paper proposes a novel model for predicting heating, ventilation and air conditioning (HVAC) energy consumption in commercial buildings. The model simulates energy behaviors of HVAC systems in commercial buildings, and interacts with a multiagent systems (MAS) based framework for energy consumption prediction. Prediction is done on a daily, weekly and monthly basis. Ground truth energy consumption data is collected from a test bed office building over 267 consecutive days, and is compared to predicted energy consumption for the same period. Results show that the prediction can match 92.6 to 98.2% of total HVAC energy consumption with coefficient of variation of the root mean square error (CV-RMSE) values of 7.8 to 22.2%. Ventilation energy consumption can be predicted at high accuracies (over 99%) and low variations (CV-RMSE values of 3.1 to 16.3%), while cooling energy consumption accounts for majority of inaccuracies and variations in total energy consumption prediction.

Aug 1, 2013

By V. E. Edlund

As part of a research program for recovering alumina from domestic nonbauxitic resources, the Bureau of Mines investigated a lime-sinter, caustic leach technology for anorthosite. This report discusses the unit operations--feed preparation, sintering, and leaching. Acceptable pellets for the bench-scale sintering studies were prepared from mixtures of minus 200-mesh anorthosite and limestone using water alone as the pelletizing agent. Heating pellets at 1,270° to 1,360° C for periods of 0.5 to 2 hr, followed by a 15-min soaking period at 700° C and cooling to room temperature, produced a sinter that dusted to more than 90 pct minus 65 mesh. The weight ratio of limestone to anorthnsite was critical in producing sinter exhibiting good dusting and leaching characteristics. A ratio of 2.0 was optimum for the bulk samples of anorthosite and limestone used in this research. Leach solutions from lower ratio sinters were unstable; gelation became progressively more severe with higher ratio sinters. Leaching the dusted sinter with 10-pct Na2CO3 at 60° C extracted 85 to 90 pct of the alumina in a product solution containing about 50 g/l A1203. Leach residue in contact with pregnant solution tended to set up as a rigid gel as a result of cementation, comp action, and gelation. The presence of a calcium-sodium zeolite [(Cn,Na2)6?(Al2Si04)12?27-3OH20] in the ungelled residues seemed to be the main difference between gelled and ungelled residues.

Jan 1, 1982

By R. K. Linn

The New Idria Mining and Chemical Co. owns and operates the New Idria mine in southern San Benito County, Calif. During 1957-59, the New Idria mine was the largest producer of mercury in the United States and its alltime production of over a half-million flasks was exceeded only by one mine. It is one of the oldest and most consistent producers in California. With the exception of 1921-22, the mine has an annual production of mercury dating back to 1854. This paper by the Federal Bureau of Mines describes the exploration, development, mining, and furnacing of mercury ore at the New Idria mine. Figure 1 is a view of the furnace plant of the New Idria mine. The purpose of this report is to promote the development and conservation of our mineral resources by dissemination of technological information on mining and processing procedures, and related practices at operating mines.

Jan 1, 1961

Two of the problems long associated with the complete extraction of level pillars in the wide ore bodies of Broken Hill have been: (1) The high cost of maintaining level gangways through areas of slow subsidence to provide adequate trucking roads for the transport of sand filling; and (2) The difficulty and high cost of completely filling depleted areas. This paper deals with the experiments conducted to devise an apparatus for transporting, with the aid of compressed air, sandfill from the underground sand passes to the stopes and describes the sand blower which has been developed. This apparatus has to a large degree overcome the difficulties and removed much of the hazard associated with the rapid extraction of level pillars.Special attention is drawn to the sizing analysis of the sand and to the fact that it is not dry material. It was early found that these factors were determinants in the design and development of the apparatus described.Acknowledgment is made to the General Manager of Broken Hill South Limited for permission to present this paper, to the engineering department for assisting in the design of the apparatus, and to the underground staff for their co-operation in training the operators and in bringing to success this method of stope filling.PREVIOUS FILLING METHODSThe South Mine, with a monthly production of approximately 32,000 tons of lead-sHver-zinc sulphide ore by cut-and-fill mining methods, requires about 11,000 cubic yards of filling per month. With the exception of a small and variable quantity of developmental mullock, all this filling is...

Jan 1, 1941