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Notwithstanding full concurrence with the dictum of a famous scientist that "definitions are the most accursed of all things on the face of the earth," in view of the considerable confusion which exists in jigging nomenclature, it is considered advisable to commence this paper with the following explanations of the terms which will be used throughout the text.Jig Bed. The whole layer of material lying on top of the jig screen.Ragging. The layer of denser material lying immediately above the jig screen, which is too coarse to pass through this screen and is confined horizontally by the cells of the top grid.Ore Column. The layer of ore pulp between the ragging and the top-water.Top Water. The water, carrying fine material in suspension, which flOiWS over the surface of the jig bed.Hutch Water. The water added to the jig below the screen. (Except for the water discharged with the hutch concentrate, the "hutch-water" eventually becomes "top-water.")Feed Water. The water in the ore pulp fed to the jig.(This water becomes part of the "top-water.")Pulsion. The period of the jigging cycle during which the water is moving upwards relative to the particles in the jig bed.

Jan 1, 1937

By Jose A. Delgadillo

The hydrocyclone problem has been a challenging task for the last 30 years. In the 80’s and 90’s Computational Fluid Dynamics solution to this problem began to appear. These were unsuccessful due to over simplification. In the past 3 dimensional solution with ?-e model and Reynolds Stress Model have been published. In this paper RSM and ?-e models are compared with velocity profiles measured in 75 mm and 250 mm diameter hydrocyclones. It is shown that results are not satisfactory with RSM or ?-e and that a model called Large Eddy Simulation is needed to describe velocity profile evolution and size classification.

Jan 1, 2005

By D. A. Donato

It is often necessary for a mining company to extract coal from a seam underlying a previously mined coal seam. The impact of the overlying mine workings on the stress distribution within the underlying mine workings is very difficult to assess without the use of numerical modeling techniques. This paper demonstrates the usefulness of applying numerical modeling to evaluate alternate startup-room locations for a longwall panel considering the effects of multiple seam interaction. MULSIMIPC, a code adapted by the former U. S. Bureau of Mines, was used to compare stress patterns in two proposed startup-room locations. These model results were not only compared to each other, but also to results from a model with no overlying mine workings to provide baseline criteria for evaluation of the two proposed startup-room locations. The numerical modeling study was successful in providing useful information to the coal company and the regulatory agency (MSHA), resulting in a mine design that was both safe and efficient, and prevented the sterilization of a large volume of coal reserves.

Jan 1, 1996

By M. Rice, M. Stanley, J. Marlow

Arizona construction aggregate industry remains in the crosshairs of public debate, caught between the need for aggregate-based building materials and alternative, high-value land-uses. To better manage lands and improve land-use decisions, the Arizona State Land Department has need for a system to assess potential aggregate resources on State Trust lands, and assign dollar values accordingly. Thereafter aggregate values can be compared to residential, commercial, agricultural, recreational, and habitat values -- in a determination of highest and best land-use.

Jan 1, 2002

By Daniel N. Adams

The University Link project extends Seattle?s light rail from downtown to University of Washington (UW). It includes 5.0 kilometers (3.15 miles) of twin-bored, 6.4 meters (21 feet) excavated diameter tunnels, and two cut-and-cover stations. The Capitol Hill Station (CHS) requires an excavation 170.7 meters (560 feet) long, 22.6 meters (74 feet) wide, and 22.9 meters (75 feet) deep. The University of Washington Station (UWS) requires an excavation of about 238.4 meters (782 feet) long, 21.3 meters (70 feet) wide, and 33.5 meters (110 feet) deep. The project is within the glacially diverse soils of the Puget Sound region, below groundwater. This paper highlights major station and tunnel design elements, including the approach to support of excavation at both station boxes, and the site staging requirements.

Jan 1, 2008

By G. E. Perry, R. D. Seba

The steam soak process is the most widely applied and most successful thermal supplemental recovery process in use today. This process, which consists of injection of steam in various quantities into a well that is subsequently used as a producer, can be repeatedly applied to the same well. The treatment, if successful, will increase the production rate of the well for a given period. For this reason, the steam soak process should be considered primarily as an acceleration method rather than as a method for producing oil that could not be recovered by primary means. However, application of this process to reservoirs containing viscous crude may produce oil that otherwise would have zero present value or would be produced at such low rates by primary methods that it would not be profitable. A major necessity for the successful application of the steam soak process is a source of natural energy. This source of energy may exist in one or more of the following forms: expansion of fluids, compaction, gravity drainage. This study was undertaken to determine the effect of gravity drainage on steam soak production and recovery and to develop a method for predicting production rates, ultimate recovery, and heat requirements when applying this process to a reservoir in which the primary driving mechanism is gravity drainage. (For additional discussion of some of the factors that affect recovery of viscous oils by the steam soak process, see Ref. 5.) Model The model developed for analyzing the performance of the steam soak process in gravity drainage reservoirs is a modified form of that developed by Matthews and Lefkovits.1,2 The model used in this study consists of two concentric cylindrical volumes of productive formation with cap and base rock of impermeable material. The inner cylinder, extending from the radius of the wellbore to some predetermined radius, is referred to as the hot zone; and the outer cylinder extending from the exterior boundary of the hot zone to the outer drainage boundary will be referred to as the partially heated zone. Fig. 1 is a schematic cross-section of the model, indicating its thermal properties. Horizontally the reservoir is divided into two regions, the upper region having a high gas saturation and residual liquid saturation, and the lower region containing a high liquid saturation. The boundary between these two regions is referred to as the free surface, which drops and changes shape as fluid is produced from the reservoir. The model was used to analyze the steam soak process by applying the following assumptions: 1. The horizontal formation is composed of one or more homogeneous noninterconnected layers containing incompressible fluids. Each layer is treated separately. 2. The hot zone is heated by the initial soak and is maintained at the steam temperature corresponding to atmospheric pressure by resoaking. 3. The height of the free surface at the producing well is at all times zero (producing well is pumped off). 4. The position of the free surface at the start of

Jan 1, 1970

The Development of a Non-Roasting Technology for Polymetallic Gold and Silver-Bearing Sulfide Concentrates Treatment

Sep 13, 2010

By Cosmin Carpinisan, Erich J. Hofmann, Stephen J. Hall

"Since presenting a technical paper regarding their unique capabilities in Forged Steel Mill Gearing at the SAG-2006 Conference, Australian heavy engineering company Hofmann Engineering has pioneered a number of new manufacturing processes and design concepts for components of large comminution equipment. These include: 1. Novel design improvements for HPGR Rolls with forged steel tyres and a unique patented tungsten carbide insert designed to improve wear life, enhance autogenous layer build-up, and to reduce breakage & chipping under load. 2. Development of forged fabricated Mill Heads using rolled & welded high-tensile steel plate as alternatives to cast conical mill heads. 3. Insitu Girth Gear measurements for profile and wear via portable 6-axis CMM. 4. Gear and Pinion designs to AGMA-6114 for SAG mills of 38’-40’ diameter to 24MW and for Ball Mills of 26’ diameter to 18MW. The paper presents case studies from the Australian heavy manufacturing facilities of Hofmann Engineering, combined with news of their new gear manufacturing and gearbox overhaul facility in Canada."

Jan 1, 2012

By Johnny Zhang, Yang Anguo, Li Weifeng, Xueyi Guo

"SKSTM oxygen bottom blowing smelting technology was developed by SKS-ENFI at SKS Smelter, Hunan in the 1990s to replace the conventional sintering process and thus to meet the high national EHS standard for lead.Since then, two major milestones have been achieved:1. Since 2002, the SKS oxygen bottom blowing smelting-blast furnace reduction has been in operation at SKS, YGL, Chizhou smelter etc. Now in China, about 50% of the lead (4.2 millions t/year) is produced using SKS process; and2. Since 2008, the blast furnace has been replaced by direct reduction of molten rich lead slag at YGJ smelter, which is more energy-efficient since no slag cooling is required. This two stage process (SKS Oxidation- Direct Reduction) is named as the YGL process.Since 2008, numerous technological innovations have been implemented in the furnace design, process control, and maintenance at YGL. The plant has been successfully demonstrated its unique excellent performances on all aspects from processing capacity, product quality, energy reduction, cost reduction and emission reduction. The purpose of this report is to update all the improvements with proven tracks.Meanwhile, a preliminary comparison on the following aspects between the YGL process and other similar technologies has been discussed:1. Plant design and operating conditions;2. Mass and heat balances, metal (Pb, Ag) recovery;3. Consumables, oxygen gun and refractory lining life;4. Energy consumption and operating costs;5. Sulfur capture and emission reduction etc.It is concluded that the modified SKSTM process is a clean SO2-free emission process. The process is characteristic of other features such as no extra fuel addition, low capital with a small foot-print design, low OPEX, high throughput, easy operation, long refractory lining life and high productivity (95%+ on line time annually). It offers an alternative cost-effective technology for lead smelting industry."

Jan 1, 2014

By O. M. Arafat, J. A. Finch

"The Functional Performance Equation calculated from a plant grinding survey defines two distinct ball mill circuit efficiencies and how they relate to total production rate through the target grind size. The survey data are also used to calculate a complete ball mill size distribution model, represented by the energy specific grinding rates, not just through the target grind size, but through all the size classes. Cyclone separation performance is represented by individual size recoveries to underflow. When these two unit operation performances are entered into the circuit modelling program (Streamline™), along with the circuit feed rate and size distribution, all the circuit survey size distributions and mass flows are perfectly regenerated by the program. The many issues associated with the historical Epstein (breakage-selection) models are eliminated. Once the circuit program is populated, pump and cyclone performance changes can be evaluated using a step-by-step procedure in order to maximize Classification System Efficiency. Mill water use and media sizing opportunities are also diagnosed in order to maximize Mill Grinding Efficiency at the size of interest. An example is provided. This circuit analysis and modelling system, and related training, is provided through a web-based application.IntroductionSince its development (McIvor, 1988), the Functional Performance Equation for ball milling has facilitated new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this refreshing approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the Functional Performance “Mill Grinding Rate” at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining “selection rate” and “breakage size distribution” functions. The much simpler ball mill model presented here has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this extremely business-friendly ball mill model with optimization criteria from Functional Performance Analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/material provider, and circuit designer."

Jan 1, 2017

By Paul G. Marinos, Vassilis Marinos, Evert Hoek

The Geological Strength Index (GSI) is a system of rock mass characterization that has been developed in engineering rock mechanics to meet the need for reliable input data related to rock mass properties required as input for numerical analysis or closed-form solutions for designing tunnels, slopes, or foundations in rocks. The geological character of the rock material, together with the visual assessment of the mass it forms, is used as a direct input for the selection of parameters for predicting rock mass strength and deformability. This approach enables a rock mass to be considered as a mechanical continuum without losing the influence that geology has on its mechanical properties. It also provides a field method for characterizing difficult-to-describe rock masses. Recommendations on the use of GSI are given and, in addition, cases where the GSI is not applicable are discussed.

Jan 5, 2007

The commonly used Stopes-Heerlen coal petrographic classification and nomenclature has over the years been subject to variable interpretations. This paper discusses the problem with specific reference to the inertinite maceral group. The effect of various interpretations of the Stopes-Heerlen system on maceral analysis is discussed and illustrated by means of comparative analyses conducted by a number of laboratories in Australia.An attempt is made to define the reflectance thresholds used by the authors to subdivide the inertinite group; the genetic and technological significance of these thresholds are compared.The difficulties of distinguishing structured and nonstructured macerals of the inertinite group are discussed in terms of possible improvements to the present StopesHeerlen system by extending the classification to include transitional maceral types.

Jan 1, 1970

IT is not intended that this paper should be regarded as an account of the geology of the Lyell district. It is merely a synopsis of some of the conclusions recently arrived at in regard to the stratigraphic and structural geology, compiled to act as a guide to those members of the Australasian Institute of Mining and Metallurgy attending the Queenstown meeting who are interested in economic geology. The attempt has been made to present certain salient features, omitting a mass of detail, which, although important in the complete investigation and understanding of the economic geology, yet would be confusing to a group of geologists making a short visit. The location of some of the significant occurrences bearing on the main problems and conclusions are indicated in the text in order to enable members to plan the location and direction of their excursions...

Jan 1, 1927

By Kathryn L. Neale, Derek L. Mulligan, Robin E. Goad, Norman A. Duke, A. Hamid Mumin, W. John Camier

"Abstract - The NICO and Sue-Dianne deposits are being explored and delineated by Fortune Minerals Limited in the Mazenod Lake District of the Northwest Territories, using an Olympic Dam model. The deposits were discovered in the south part of the Great Bear magmatic zone (GBMZ) within the Proterozoic, Bear Structural Province of the Canadian Shield. They are the only known significant Canadian examples of Proterozoic iron oxide-hosted polymetallic deposits. Worldwide, this class includes such deposits as Olympic Dam and Ernest Henry in Australia, Kiruna-Aitik in Sweden, and Salobo in Brazil. Their considerable size, up to 2 billion tonnes, and polymetallic ore assemblages make them highly attractive targets for exploration. Common characteristics of this class include their Early to Middle Proterozoic cratonic settings with extensional rifting evolving from collisional tectonics. Deposits typically occur along major structural lineaments within the aureoles of a distinctive suite of anorogenic potassium-rich "A-type" granite intrusions. Although hosted by diverse lithologies, deposits of this class are characterized by a number of other diagnostic regional- and deposit-scale features, which may be recognized in reconnaissance- and propertyscale geological and geophysical surveys.The southern GBMZ in Canada has several characteristics (age, tectonic setting, geology and geophysical attributes) similar to those of the Olympic Dam deposit and its other significant global analogues. Airborne and ground geophysical surveys carried out in the GBMZ identified coincident potassium, uranium, magnetic, resistivity, chargeability, and gravity anomalies centered over the NICO deposit. The nearby Sue-Dianne deposit is characterized by coincident uranium, potassium, magnetic, resistivity and chargeability anomalies. Both deposits occur within a regional, northweststriking, arcuate trend of volcanic and sedimentary rocks characterized by significant positive Bouguer-gravity and magnetic responses and are believed to represent a major basement discontinuity. The NICO anomalies are at the intersection of this regional trend with a major transverse fault through Lou Lake. Regional and local geophysical data indicate the presence of significant concentrations of iron oxide within a broad area of intense potassium metasomatism. Geological mapping identified cobalt, gold, bismuth, and copper mineralization in biotite-magnetite-amphibole-sulfiderich ironstone and schist. This mineralization is localized within altered wackes of the Snare Group, which are unconformably overlain by potassium feldspar- (±hematite ±magnetite) altered rhyolite of the Faber Group. The Sue-Dianne deposit is a hematite-magnetite-Fe-silicate-cemented diatreme complex enriched in copper, silver, gold, and uranium within a broad zone of potassium, iron, quartz, and epidote metasomatism. The diatreme is located at the intersection of two major faults at the north end of the basement discontinuity and is hosted in rhyodacite ignimbrite marginal to the Faber Lake rapakivi-granite pluton. At both deposits, diatreme- and maar-facies iron oxide-cemented breccia straddle the regional metasedimentary-volcanic unconformity, suggesting that mineralization formed in a near-surface environment synchronous with the onset of volcanism."

Jan 1, 2000

By A. B. Hooker, L. C. IlsLey

"Observation of the use of trailing cables in ""mines shows that the chief limiting factor in the life of the cables and their safe use is the smashing or crushing of the cables in service, together with the effects of consequent splicing.Trailing cables are crushed when run over by cars, mining machines; and locomotives or when hit by falls of roof. Crushing damages the insulation and may cause failure at once or in later use. Failure may be either by short circuit between the conductors or by grounding to the track. The failure of a live cable causes electric arcs capable of igniting explosive mixtures of methane and air. Every cable failure in a gassy or dusty mine is, therefore, a real or potential hazard.Some mine operators do not allow the splicing of trailing cables for use in gassy mines, bet require that a damaged cable be immediately replaced and if repaired that it be used only in nongassy mines. Other operators allow the making of temporary splices to permit completion of the shift but require that such splices be remade and vulcanized before the cable is used again.Still other operators allow the continued use of temporary splices, which in general means that a cable is used until the splices give trouble in reeling, or overheat, or pull apart. Then the spliced sections are either cut out or the whole cable is replaced.Splices often determine the useful life of a cable. A splice poorly made may pull apart ueder mechanical strain and cause arcing that burn* the surrounding cable or ignites as or coal-dust. If it has lower conductivity a splice is the first part of the cable to heat; it may become so hot under load that it will burn apart and damage other parts of the cable, or, if it be a soldered splice, the solder may melt and allow parting of the cable. A poorly made splice often has insufficient insulation which may alloy short-circuiting between conductors or permit external contacts capable of giving an electric shock to one handling the cable. The splice is sometimes bulky from too much insulation and takes up too much room on the reel, causing uneven reeling; also by catching on the spooling device the oversized splice may receive expressive pulls and wear. Splicing is therefore a very important factor in the use of trailing cables."

Mar 1, 1932

By Jeffrey S. Newman

This report presents a summary of the results of a four-phase program conducted for the Bureau of Mines to evaluate underground mine fire detection systems. In addition, Phase IV is presented in detail. The major accomplishments of this program are: 1) quantification and prediction of the distribution of fire products in a mine pas¬sageway; 2) quantification of "equivalent protection" by fire detectors as contained in Title 30 of the Code of Federal Regulations; 3) definition of detection criteria; 4) design of a detector test program for determining detector spacing requirements; 5) design, construction, operation, and calibration of a fire test apparatus for evaluating mine fire detectors; 6) quantification of several mine fire sources; 7) evaluation of several fire detector types including heat, CO and CO2 gas, and ionization smoke detectors; 8) development of generalized spacing criteria for mine fire detectors; and 9) development of performance specifications. Reports for Phases I through III are included in Appendices.

Jan 1, 1984

By John E. Conley

The need for lightweight aggregate for use in concrete products ,and structures has caused the Bureau of Mines to undertake an investigation to determine the availability of suitable raw materials and to study methods, procedures, and equipment to supply that need. Evidence is at hand to prove that the shortage of lightweight aggregate is nationwide. A survey recently covered in a report (13)5/ by the Construction Branch of the National Housing Agency has pointed out the locations in which lightweight aggregates are produced. A study of this information discloses that the producing centers are widespread, and that certain areas, notably the region east of the Mississippi River, and especially the sections along the Atlantic coast line and the Southeastern States, have only a few such plants. Certainly, many localities are badly in need of installations equipped to provide an ample supply of high-grade lightweight aggregate. The work undertaken by the Bureau of Mines includes investigation of the use of clays, shales, slate wastes, coal-mine wastes, diatomite-clay combinations, and various other 'mineral mixtures as possible raw materials. Likewise, special consideration has been given to the development' of equipment and techniques to produce the lightweight products.

Jan 1, 1949

By J. Utt

Recent developments in circulating fluidized bed (CFB) once-through supercritical technology (OTSC) have enabled this technology to be offered as a utility-scale alternative competing head-to-head with pulverized fuel (PF) OTSC offerings. One clear example is the CFB supercritical unit at the Lagisza Power Plant in Poland, owned by PoludniowyKoncernEnergetyczny SA (PKE). This unit has now been in commercial operation for three full years, exhibiting very good performance, and has validated Foster Wheeler?s performance model at this utility scale as well as for units in the 600 MWe and 800 MWe size ranges offering net efficiency of ~43 per cent (LHV basis). This operating unit has also proven the use of the world?s first FW/BENSON? vertical-tube OTSC low mass flux technology. Since the Lagisza original international tender specified OTSC PF technology, it is important to note that the alternative selection of CFB OTSC technology over conventional PF technology is of historic significance, not only for the validation of the CFB supercritical platform as a viable alternative to conventional PF technology, but it also positions the CFB OTSC with fuel flexibility for offering of sizes up to and including 800 MWe units. This paper explores the differences between CFB OTSC technology and standard PF OTSC in utility power generation. Selection criteria, fuel burning range in both technologies, and other selection drivers are discussed. Economic analysis of both technologies, based on existing cases, is also provided. Also discussed are the technical advantages and uses of each technology. Foster Wheeler has recently been awarded a contract for four units of CFB OTSC technology, which utilizes a 2 on 1 configuration of two 550 MWe CFB OTSC boilers on two single 1000 MWe turbines. Essentially this provides a fuel-flexible low-emissions alternative to a 2 × 1000 MWe solid fuel power block.

Jan 1, 2012

By Alexander Filotti, Stanley Merjan

"Abstract. The paper shows the benefits and accomplishments of this relatively new but established product on the pile foundations market in the United States. The first part of the paper describes general aspects of the design, construction, and geotechnical capacity (designed and in situ) of Tapertube piles. The qualities resulting from the design and manufacturing of the Tapertube pile will be presented first.The second part of the paper describes the installation of Tapertube piles for an addition to Terminal One at JFK International Airport and The Edge development. A carbon print analysis for both projects is developed using the EFFC-DFI carbon print calculator. For the JFK project the benefits of using BIM in redesigning the project for Tapertube piles are explored.General description.The tapertube pile consists of a tapered tubular bottom section attached to a conventional pipe extension. The 50 ksi steel for the taper is mechanically folded into a polygonal cross-section (usually 12-sided) with a longitudinal welded seam. The tapers are fabricated in many sizes with bottom diameters varying from 8 to 14 inches, top diameters from 12 to 20 inches, lengths from 10 to 35 feet, and steel thicknesses from 3/16 to 1/2 inch. A conical steel shoe or a flat plate is welded to the bottom of the taper and the top of the taper is circularized to match the outside diameter of the pipe extension. The inclination of the tapers is generally between 1.5% and 2.5%.The pipe extension is fully butt welded to the taper and has the necessary length for the pile to develop the requisite capacity. Concrete fill for the piles is generally 4,000 p.s.i. or more. Typically the piles are shopassembled and shipped to jobsites in lengths to 80 feet."

Jan 1, 2014

This paper reviews the current techniques employed in the prediction of subsidence and how they have been applied to partial extraction systems. The method using influence functions to describe the shape of the profile is investigated in detail and has been adopted to model the subsidence over workings in Huntly. It is compared with the profile methods developed in the United Kingdom and found to predict the subsidence profile more accurately than these methods.

Jan 1, 1991