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By C. A. Rowland

"Plant owners and operators, plant designers and grinding mill manufacturers are giving much attention to the design and manufacture of autogenous and semi-autogenous grinding mills, particularly the mills that have large diameters and draw power up to 10,000 hp and greater. Reliable designs giving long operating lives are required in today 's ore processing plants.This paper reviews bench-scale and pilot-plant testing to determine first if the ore is suitable .to be ground by these methods and then reviews the data obtained from pilot-plant testing that is used to select the mills and the grinding circuit. The paper then discusses the use of the pilot-plant results to design the mills. The most important pilot-plant data used for mill design are power and the amount of ball charge to be used. The mill size selected is a combination of these factors. Pilot-plant data not only establish power requirements, but can be used in the selection of the type of drive, variable speed or fixed speed, and the operating procedure to be followed. This leads into the mill control circuit to be used. The total charge in the mill, the type of drive and mill discharge arrangements are needed in the calculation of stresses and bearing loads. Conclusions reached from pilot-plant work are used to obtain data for process design, and autogenous and semiautogenous mill design should be part of any test program incorporating either or both of these grinding methods."

Jan 1, 1981

By B. A. Peppley

The current most common method of hydrogen production for fuel cell systems, including SOFC systems, is autothermal reforming. Autothermal reformers have a number of advantages including fast start up and load following and ease of control. However, there are a number of problems inherent with the addition of air into a system connected to the anode feed such as dilution of the fuel with nitrogen and the potential for oxygen to reach the anode chamber directly. Pure steam reforming, which does not involve air addition, provides a richer fuel mixture to the SOFC anode and is inherently safer than autothermal reforming. Although in theory pure steam reforming can be shown to provide these advantages, a number of technical problems need to be overcome before such a system can be practical. In particular, issues such as catalyst degradation due to poisoning and thermal sintering, coking, as well as fuel-steam mixing need to be addressed. Experimental results from a prototype reformer will be presented to illustrate a number of these points. This paper will compare differences in system efficiency, safety and complexity between autothermal/SOFC systems versus a steam reformer/SOFC system. A system simulation will be utilized that is able to account for material and energy balances for a SOFC power generator operating on diesel fuel. The requirements for improved catalysts will be discussed and an analysis of the potential benefits of sulfur tolerance and lower temperature activity will be considered.

Jan 1, 2005

By Peter A. Hacquebard

"Two continuous coal zones occurring in a 2500f t (762 m) thick section of the Upper Carboniferous Pictou Group (Westphalian C and D) have been encountered in five offshore wells drilled f or oil and gas in the Gulf of St. Lawrence. They correlate, by means of fossil spores, with thick coals of the Mabou and Inverness coalfields situated at the eastern margin of the Basin. Therefore, the presence of a large submarine coalfield of at least 18000 sq mi. (46 620 km'] is indicated. This compares with an estimated size of 14 000 sq mi. (36260 km' ) for the Sydney Coal Basin.Accessibility is provided only by the small onshore parts of the Mabou and Inverness fields, because farther offshore the coals lie too deep to be mined (below 4 OOO f t ([ 219 m)).Two near-shore coal exploration wells indicate that at Mabou Mines the younger Inverness coals occur at a mineable depth to at least 5 km from land. A structure contour map of this area shows a reserve of 125 million tons in two Inverness equivalent seams that are 8.5 ft (2.6 m) and 4.5 ft (f.4 m) thick. The Mabou coals, however, reach too great a depth close to shore to possess mineable resources.A structure contour map of the Inverness submarine area, based on mine data and one off shore seismic profile, indicates inferred mineable resources of 160 million tons, in two seams that are 7ft (2.1 m) and 4.5 ft (f.4 m) thick . A detailed deep seismic survey will be necessary to substantiate the structure and resource estimates"",Maceral and coal quality percentage diagrams of five column samples of these seams (the 7 Foot and 13 Foot Seams of Inverness Equivalents) show a bright banded coal, high in reactive macerals, which will produce a weak coke unsuitable f or metallurgical purposes. A thermal coal with a rank of H. V. ""B"" Bituminous (0.64% Ro) is present, averaging 12000 btu llb (6 660 kcai/kg), 10% ash and 6% sulphur, of which 60 to 80% is derived from pyrite.Microlithotype profiles of the major Mabou and Inverness coals show characteristic successions that can be used f or seam identification and proved valuable f or structural interpretations.The time of faulting in the major fracture zone on the eastern margin of the Gulf of St. Lawrence Basin has been deduced from coal rank variations. It occurred in pos tPermian, probably Early Triassic time."

Jan 1, 1986

By A. L. Williamson

Bio-mining is a cost-effective, energy efficient and potentially environmentally protective method of exploiting a variety of ore deposits, from high-grade base metal deposits of nickel to lower-grade uranium and rare earth deposits such as are found in the uraniferous quartz-pebble conglomerate beds of the Quirke Syncline, Elliot Lake, Ontario. The effectiveness of bio-mining in Elliot Lake depends on the success of bacterially-influenced dissolution of metals of economic importance. The determination of both the dissolution efficiency and rate controls for uranium and rare earth elements from bio-extraction processes is critical to assess the potential for success of bio-mining along the Quirke Syncline. This poster provides an overview of proton-mediated biogeochemical dissolution of more than 50 elements, including uranium and rare earth elements from samples of the low grade uraniferous ore collected as drill core from the Elliot Lake area. The elemental data is quantified using advanced spectroscopic tools (ICP-MS and ICP-AES) to analyze solutions obtained from a series of environmentally controlled biologically-mediated uranium ore extraction experiments. The findings are being to guide design of larger scale bio-leaching experiments to further assess the potential for success of bio-mining along the Quirke Syncline.

Aug 1, 2010

By A. Boucher, D. Marcotte

"Abstract- The accepted practice for the estimation of thin (2D) vein deposits recommends the use of the grade x thickness service variable (i.e., the accumulation). Grade estimates are obtained indirectly by the estimated accumulation/estimated thickness ratio. This practice stems from the varying support (thickness) problem and the resulting non-additive nature of the grade variable. We compare the actual performance of the direct grade estimation approach used by some practitioners to that of the indirect approach using accumulation. Our simulated and real data indicate that the direct approach is more accurate for point grade estimation where the grade-thickness correlation coefficient is positive (and vice-versa). Moreover, the relative gain of the direct method increases with the (positive) correlation coefficient. This finding contradicts common thinking that the indirect approach should be the preferred method where grade-thickness correlation is strongly positive. Also, for a given positive grade-thickness correlation, the relative gain of the direct method increases with the coefficient of variation of the grade and thickness. Résumé - L’estimation de veines minces (2D) minéralisées est normalement réalisée à l’aide de la variable auxiliaire épaisseur x teneur (i.e., accumulation). Les estimés des teneurs sont alors obtenus indirectement du rapport accumulation estimée/épaisseur estimée. Cette pratique découle du problème du support variable pour la teneur, l’épaisseur de la veine, qui fait que la teneur est alors une variable non-additive. Nous comparons les performances de l’estimation directe de la teneur, utilisée par certains praticiens, à celle de l’approche indirecte. Pour l’estimation ponctuelle des teneurs, nos données simulées et réelles indiquent une meilleure justesse de l’approche directe quand la corrélation teneur-épaisseur est positive (et vice-versa). De plus, le gain relatif de la méthode directe s’accroît avec la valeur de cette corrélation (positive). Ce résultat contredit l’opinion répandue que l’approche indirecte devrait être utilisée en présence de forte corrélation positive de la teneur et de l’épaisseur. Nous montrons également que pour une corrélation positive teneur-épaisseur donnée, le gain de l’approche directe augmente avec les coefficients de variation de l’épaisseur et de la teneur."

Jan 1, 2001

By K. Kawagishi, K. Matsumoto, Y Koizumi, H. Harada

A new burner rig for cyclic and hot corrosion testing of Ni-base superalloys and high-temperature coatings has been developed at the National Institute for Materials Science (NIMS) in Japan. The concepts of the rig design include: use of kerosene as fuel, easy operation for materials research and multi-specimen testing capability per test run. The burner rig consists of six blocks including combustion block, corrosion-solution injection block, furnace block, specimen block, controller block and outdoor facility block. During verification testing, it was confirmed that the rig had accurate specimen temperature control within ±1? from 600 to 1100? and automated easy operation. Cyclic testing of several Ni-base superalloys was conducted. The results from 50 cycle testing indicated that a new NIMS alloy developed for 1700? class gas turbine had higher oxidation resistance than CMSX-4. This new burner rig testing capability at NIMS can be very useful for future oxidation, hot corrosion and coating durability studies.

Jan 1, 2010

By A. Danaei, A. McLean, M. Barati, C. Ravindran

"The aluminum industry generates about 90 million tonnes of red mud each year. Previous research shows it could be utilized as a refining flux with a high capacity to absorb phosphorus and sulphur from hot metal in the steel industry. The present study was undertaken to evaluate the melting properties of such fluxes, as it affects the effectiveness of the flux. The results show that the melting behavior of red mud is strongly affected by lime addition and the characteristic melting/softening temperatures reach minimum VALUES (at 32.7 wt% CaO. From these findings, a correlation was established between melting behavior and optical basicity. This allows one to adjust the composition of the flux based on the process requirements. INTRODUCTIONThe aluminum industry generates about 90 million tonnes of bauxite residues each year. This residue is usually red in color because it contains a substantial amount of iron oxide. The red mud, as it is called, is a solid waste with a high concentration of sodium oxide, high pH (10 to 13), and high alkalinity, and thus is harmful to many forms of life. Traditionally, the material is stored in large tailings ponds within the plant’s vicinity (Power, Grafe, & Klauber, 2009). Development of solutions for safe disposal or preferably using this residue for other industrial processes or applications could help restore polluted locations and eliminate a negative impact on the environment (Haake, 1988; Power et al., 2009; Yan & Xuegong, 2010).The mineralogy and chemical composition of red mud depends on the quality of the bauxite and refining process parameters. In general, it consists of iron oxide (Fe2O3), aluminum oxide (Al2O3), titanium oxide (TiO2), sodium oxide (Na2O), silicon oxide (SiO2), and calcium oxide (CaO) (Power et al., 2009). Like most ores and soils, bauxite can contain trace quantities of metals such as arsenic, beryllium, cadmium, chromium, lead, manganese, mercury, nickel, and naturally-occurring radioactive materials, such as thorium and uranium. Most of these trace elements stay in the residue (Power et al., 2009)."

Jan 1, 2012

By A G. Rogers

This paper discusses the lubrication of surface and underground mining machinery and equipment from the standpoint of machine components. The machine components considered are bearings, cylinders, gears, chains, couplings, fluid drives, hydraulic systems, screws and wire ropes. The best selection of lubricants for these machine components, and for sub-divisions of the components, are outlined. They form general recommendations, for average operating conditions in both surface and under-ground mining operations. The American Petroleum Institute's service classification of both engine crankcase oils and gear oils is de-scribed and used in recommending products for these applications. The practical aspect of lubrication is kept foremost in the recommendations, which are designed to meet the requirements of a wide variety of equipment with the minimum number of lubricants. THE lubrication of mining machinery and equipment presents a variety of problems peculiar to the industry. The type of mine, the ambient temperature, water, dust, and operating and maintenance practices, as well as the age and condition of the equipment, are variables which have to be considered in making lubricant recommendations.

Jan 1, 1963

By A. C. Bonnier

"INTRODUCTIONI have been asked to make available our method of determining the ""Live Inventory"" within a gravity type thickener. The ""Live Inventory"" being that tonnage compatible with the optimum underflow density that satisfies the process requirements.One prerequisite of the calculations is the proper determination of the final pumpable underflow density. A further requirement is that, prior to shutdown, the thickener has been operated properly, particularly that it has not been operated for storage capacity.Until recently I had few chances to check the method. However, I was most fortunate to have had a recent opportunity covering several months on a 300 ft diameter thickener at a plant in the U.S.A., wherein the method was tested and verified many times. The method proved accurate in that our calculated tonnage checked with the actual dried physical inventory of the drying facility.At the precise moment that the feed to the thickener was shut down, a per cent solid determination was made at the critical place and the tonnage in ""Live Inventory"" determined. Let us say that at the moment the thickener U' Flow solids was 20%. The thickener then was allowed to cperate until the U' Flow solids dropped below 20%, at which time the thickener was deemed to be relieved. Anything much less than 20% was not suitable to the subsequent centrifuge operation.Most large metallurgical thickeners have a configuration of three slopes at the thickener ""bed"". These slopes are dictated by the raking blades and are shown on the manufacturers' erection drawings. The first slope is from the outer periphery and generally takes up a distance of about 60% of the radius, the second slope generally taking up the remaining 40%. Within this 40% area, there is usually another slope taken up by the cone on ""B"" type thickeners or an actual steeper inner slope on ""C"" type thickeners."

Jan 1, 1989

By A. R. Turner

AERIAL survey methods have made enormous technical advances and gained new recognition since World War II. Before enlarging on this statement and reviewing some of the uses of aerial survey in industrial development it is important to de-fine what is meant by "aerial survey". The subject will be discussed in the broadest sense and references will be made to the four sections that compose the overall field of surveying operations from the air. These are: 1. Aerial photography and photo-graphic mapping. 2. The use of airborne electronic instruments for geodetic distance measurement and the determination of ground elevations. 3. Airborne geophysical surveying. 4. The extraction of qualitative and quantitative information from aerial photographs through the processes of "reading", analysis and interpretation. Many sciences and techniques are combined in aerial survey operations. The tools of the business include aircraft, finely engineered cameras, elaborate film processing and printing equipment, ground survey instruments, precision stereo-plotting instruments, map -

Jan 1, 1961

By S. Yue, P. Vo, M. Jahazi

The flow behaviour and microstructure development of a near-alpha titanium alloy during beta working has been investigated. Typical cogging conditions were simulated through compression testing of IMI834 at temperatures of 1025°C-1100°C, strain rates of 0.01 s-1 - 1 s-1 and post-deformation heat treatments up to 4h. Using a synthesis of available literature models, a finite element model has been developed and validated through quantitative measures of flow stress-strain data and beta grain characteristics. Flow behaviour was analyzed through a self-consistent method while the microstructure development was considered with regard to the kinetics of beta recrystallization. Deformation at beta or high alpha/beta working temperatures (T>l025°C) produced minor flow softening with complete grain refinement achieved through metadynamic recrystallization.

Jan 1, 2006

By V. Songmene, R. Khettabi, J. Masounave, R. D. Njoya

L'augmentation régulière des règlements environnementaux et de la sécurité au travail deviennent de plus en plus strictes. L'usinage fait partie des opérations industrielles qui peuvent causer des problèmes de santé au travail et sur l'environnement. La plupart des particules de poussières produites pendant toutes les opérations d'usinage à sec ou lubrifie causent des nuisances environnementales graves. Le travail propose étudie l’influence des paramètres de coupe, des alliages et des états des matériaux sur la formation des copeaux et sur la génération de poussière lors de l'usinage à sec. Deux modes d'usinage (le fraisage et le perçage) sont abordés. Une loi reliant la ténacité des matériaux aux émissions de poussières est proposée. Les effets des matériaux et de leurs conditions, ainsi que des procédés d'usinage sur la génération des poussières ont été mis en évidence. Des mécanismes de formation de poussières sont identifiés et reliés à la formation des copeaux.

Jan 1, 2006

By Lex L. Udy

External-detonation-generated plasmas, highly ionized zones of reacting material ejected from the surface of detonating explosive charges, are shown to be the cause of channel desensitization, i.e., the self-quenching of a detonating explosive column loaded in a borehole with an air annulus between the explosive and the borehole wall. The effects of this phenomenon on several explosive compositions and types are demonstrated and discussed. The explosives tested include aluminum-sensitized and explosive-sensitized slurries, ANFO, liquid explosives and dynamites. Various techniques are described that can be used to reduce or eliminate the plasma effect.

Jan 1, 1979

By D. Yuan, L. Yan, R. Kalanchey, M. J. Collins, I. M. Masters

Pressure oxidation tests have been conducted by Sherritt for a refractory gold-silver project located in China. The feed contained 39 g/t Au and 970 g/t Ag; the major gold-bearing minerals were pyrite and arsenopyrite. Since the feed contained a significant amount of silver, which can be refractory to cyanide leaching after pressure oxidation due to the formation of argentojarosite, the test program included investigation of methods to enhance silver recovery. The "lime boil" process proved successful and was incorporated into the flowsheet. Gold extraction from the lime boil product solids was 95 to 98%; silver extraction was up to 94%.

Jan 1, 2011

By A. S. Robb

SAMPLING of an ore-body is one of the fundamentals in its exploration, development, and exploitation. It is carried out to determine the gold value per ton of an ore-shoot and the probable gold output of the refinery. Sampling also places any broken ground in one of two classes, ore or waste. The value and importance of correct sampling has been shown repeatedly in the past. On the other hand, instances could be given where those in charge of mines have not believed in sampling, and the result has been the same in every case-disaster. This has in all probability been due to assuming that good-looking, well-mineralized rock was ore. Sampling in some form might have averted this misfortune. In this essay, only the method of sampling and the estimation of ore reserves is treated. All titles, figures, and values are fictitious. None of the illustrations can be directly applied to any portion of the Hollinger mine, except Figures 1 and 2, which are included with the special permission of the Canadian Mining Journal. METHODS OF SAMPLING Hollinger Consolidated Gold Mines, Limited, has, from the very beginning of operations, carried out an extensive system of sampling, and the results of this sampling have completely governed the whole mining programme. The Hollinger discovery was made in 1909 and prospecting and exploration of 'the surface began at once. Four men were given jobs as samplers and they sampled thoroughly all the outcrops and all bed-rock which could be exposed to view by removing the overburden. When shaft sinking began, samples were taken at two-foot intervals. In 1912, an underground gang of six samplers was organized, and the number was increased at a rate of about two men per year as the size and extent of the workings grew. No permanent record of sampling was kept until 1919, in which year an average of 11.6 men took 28,458 samples, cutting 113,894 feet of sample. From that time until the end of 1934, the average number of samplers varied, but the total number of samples cut, and the total footage sampled, increased.

Jan 1, 1937

By A. D. McKay

Uranium exploration expenditure in Australia reached a record level of A$220.5 million in 2008, which has subsequently declined to A$185.2 million for the year ended 30 June 2009. Recent discoveries include: Ranger 3 Deeps east of Ranger open pit (Northern Territory), Pepegoona and Yadglin sandstone hosted deposits (South Australia), and Thunderball project (Northern Territory). Australia?s Reasonably Assured Resources recoverable at costs of <US$80/kg U at June 2009 are estimated to be 1,210,000 t U, 4% higher than the estimate for December 2008. The main additions were in the south eastern portion of the Olympic Dam orebody. The Olympic Dam Expansion is based on a large open pit and will increase output to an annual capacity of 19,000 t U3O8; 750,000 t copper; 800,000 ounces gold. The Four Mile in situ recovery project was approved in July 2009. An ion exchange facility is to be constructed at Four Mile and uranium-bearing resins will be transported to the Beverley plant to recover the uranium. Recent developments at Ranger mine, and Honeymoon, Oban and Yeelirrie projects are discussed.

Aug 1, 2010

By K. Torigoe, S. Owad, C. Tokoro, Y Tsunazawa

The mechanism of an abrasion process to recover metal values by removing components from printed circuit boards (PCBs) is modeled using a discrete element method (DEM) simulation. To simulate the abrasion process, a model PCB geometry was constructed consisting of bonded particulates. The simulation allowed connections between particles to be broken if the bonding force calculated from DEM exceeded a threshold level. Simulation results were compared with experimental comminution data using an agitation mill with test PCBs on which nine capacitors were surface solder-mounted. Simulation results obtained from the DEM with the anchoring model corresponded to experimental observations.

Jan 1, 2011

By Jochen Petersen, Caroline Muzawazi

The technical feasibility of ammonia leaching of PGM bearing Platreef flotation concentrates was investigated as an alternative method for the recovery of base metals prior to precious metal recovery. The composition of the concentrates includes 2.02% Cu and 3.17% Ni, and the major base metal minerals are chalcopyrite and pentlandite. Optimal leaching conditions were initially established in shake flask experiments to be a solution containing 4 M NH4OH, 4 M (NH4)2CO3 and a pH range between 9 and 10. These were used as base case conditions in column and batch stirred tank reactor tests, where the effects of total ammonia concentration and operating temperature were explored further. At optimal conditions nearly 100% Cu and Ni extraction were obtained in the batch stirred tank reactor, and 95% Cu and 60% Ni extraction was obtained in columns. The activation energy for chalcopyrite and pentlandite was 36 kJ/mol and 16 kJ/mol, respectively, in both reactors, indicating different reaction pathways for the two minerals. Gas-liquid mass transfer appears to be the limiting reaction step in columns much more than in tanks, and the degree of ammonia loss to air is significant. This initial test work indicates the feasibility of using ammonia leaching for this and similar materials as an alternative route to conventional smelting and refining prior to PGM recovery, but a number of technical challenges still need to be overcome.

Jan 1, 2014

By Fathi Habashi

"Hydrochloric acid (HCl), although more expensive than sulfuric, find uses as a leaching agent in reactions involving iron oxide. The reason for this substitution was the discovery that oxyhydrolysis of ferrous chloride by which HCl can be recycled economically. This avoided the pollution of the environment by ferrous sulfate. It was found further that the rate of leaching of sulfides is faster when HCl is used as compared with sulfuric apparently due to the formation of aqueous chlorine. In case of refractory gold ores, HCl leaching under pressure avoids the use of cyanide solution since gold chloride is produced which can be recovered by standard methods. Hydrochloric acid find also uses in the leaching of scheelite and apatite but its use in leaching clay and anorthosite is questionable.INTRODUCTION Sulfuric acid is the cheapest acid and is used as a leaching agent in many hydrometallurgical processes. However, hydrochloric acid (HCl), although more expensive since it is prepared by reaction of sulfuric with sodium chloride, has replaced sulfuric acid in many reactions involving iron oxide. It replaced sulfuric acid for the first time in 1960s in pickling of steel because of pollution problems (Habashi, 2000). Ferrous chloride produced in pickling can be economically decomposed to ferric oxide and HCl according to:2FeCl2 + 2H2O + 1/2O2 ? Fe2O3 + 4HCl (1)which also shows that the acid can be regenerated but ferrous sulfate cannot be economically decomposed to recover sulfuric acid for recycle. Since then, HCl has been used in many leaching processes. Hydrochloric acid is a corrosive acid and is usually handled in rubber-lined equipment. REGENERATION OF HYDROCHLORIC ACID Regeneration of HCl is conducted in fluidized bed or in spray roaster Fluidized bed oxyhydrolysis In a fluidized bed, ferrous chloride solution is introduced onto a bed of hot ferric oxide where heating is provided by the hot fluidizing combustion gases (Figure 1). The solution is fed on top of the bed of oxides. The liquid feed wets the outer layer of the hot oxide particles and is quickly evaporated to form a layer of new solid oxide on top of the existing oxide, thereby producing dense homogeneous particles."

Jan 1, 2017

By A. I. A. Salama, M. W. Mikhail

"A comprehensive software package has been developed at the Western Research Centre to meet many of the coal preparation requirements in the Canadian coal industry. This package performs three main functions: (1) data handling and manipulation; (2) data analysis, including the generation of washability data, performance evaluation and prediction, density and size modelling, evaluation of density and size partition characteristics, and attrition curves; and (3) graphics output.The software described in this paper is potentially a valuable tool for coal preparation plant engineers and operators for evaluating process performance and adjusting plant density separator cutpoints. Moreover, the analytical laboratory technician could find this package very useful in manipulating and presenting laboratory results."

Jan 1, 1997