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By Gunnar Eriksson

Computer simulation has become an everyday practice in thennodynamic and materials research. Advanced thennochemical algorithms take into account heat transfer effects and salient reaction kinetics when applied for process models. In particular, the combination of mass transfer or overall reaction rates with multi-component Gibbs energy minimisation provides an effective tool for simulation of industrial thennochemical processes and processing of materials. In this work the combination of rate factors with the Gibbs energy technique was studied by using the novel program ChemSheet, which operates through Microsoft's Excel® spreadsheets. Such processes as, for example, CVD of pure silicon production, titania pigment manufacturing, vapour pressure of Mercury in amalgams (in Hg-Iamp manufacturing) and melting behaviour of low-temperature alloys have been modelled. Provided that the thennochemical data is available simulations can be performed with any thennodynamic system. The calculation can be performed as an affinity study without a particular reactor model or with a specific reactor scheme.

Jan 1, 2001

By Timothy J. Matthews, Timothy J. Batchler, Ted M. Klemetti

"From 2011–2016, there were 1,511 documented injuries, including 7 fatalities, from ground falls in underground coal mines in the United States. The majority of these ground-fall injuries were not caused by a major roof collapse, but from falls of smaller rocks from the immediate roof. Roof screen can significantly reduce the number of these injuries and has been widely used in underground coal mines for surface control. Because of the potential of reducing ground-fall injuries, the National Institute for Occupational Safety and Health (NIOSH) is further evaluating the performance characteristics of welded wire screen as used in underground coal mines by conducting a laboratory testing program using the Mine Roof Simulator (MRS) in Pittsburgh, PA.The load-displacement characteristics of an 8-ft x 12-ft panel of 8-gauge welded screen were evaluated using a newly designed, large laboratory screen test frame with multiple load pull locations. This screen was tested in a configuration that simulates current installation practices in U.S. coal mines. In this study, the effects of varying the number and position of the load pull location on the screen performance were evaluated. Ultimately, the type of information obtained in this and similar studies can be used to aid in developing wire roof screen design criteria and to assist mine operators in the selection and use of roof screen in underground mines.INTRODUCTIONThe large majority of ground-fall injuries are caused by falls of smaller rocks from the immediate roof. Various controls are currently being used in mines to control this surface rock, including the use of wire roof screen. In mines where wire roof screen has been installed, injuries from rock falls have been reduced dramatically (Robertson and Hinshaw, 2001). Roof screen has the potential to prevent hundreds of injuries caused by the fall of small rocks between permanent roof supports (Compton et al., 2007). Because of this potential for reducing ground-fall injuries, the National Institute for Occupational Safety and Health (NIOSH) is evaluating the performance characteristics of welded wire screen as used in underground coal mines by conducting a laboratory testing program in the Mine Roof Simulator (MRS) in Pittsburgh, PA."

Jan 1, 2018

By Peter J. Nicholson

"IntroductionDuring my more than 40 years in the practice of underground construction and engineering, the industry has seen progress from the dig down to rock or hardpan or alternatively drive concrete or steel into the ground and count the blows; then you can be sure of you have a solid foundation; to the modern day, I’m willing to try anything to save money. Of course these are both exaggerations, but not gross ones. After getting bored being supervision on jobs counting blows, I struck out into the new field of “tie-backs” as they were called in the United States, or “ground anchors” as they were then termed in the United Kingdom. After installing some of the first permanent ground anchors for the Corps of Engineers on Lake Michigan as well as the highest loaded rock anchors of the time at two dams on the Ohio River, we were at the top of our game in the 1970’s. Subsequently in the 1980’s when my view of the future of ground anchors saw their installation becoming a commodity item, we branched out into “Pin Piles” now known as Micro Piles, high capacity, steel tube encased, small diameter (5-12” or so), high capacity (100-500 tons) piling. Next came soil nailing, both temporary and permanent retaining walls, as at Cumberland Gap Kentucky. My next morph was into “Cement Deep Soil Mixing” earlier on, known simply as “soil mixing”. For this education I traveled to Japan several times and established a long-term, Joint Venture, relationship with one of the better known Japanese specialty ground modification companies. In Boston at the “Big Dig” we established the then record size soil mixing project, 500,000 or so cubic meters of CDSM concluding in the year 2000. Since then I’ve been involved as a consultant mainly for dams and levees. Below is the story of how I came to be at this place in the road to innovation in Geotechnical processes."

Jan 1, 2017

By Stephen Njoloma, Ivan Hee, Ravi Jain, Mina Shinouda

"INTRODUCTION DC Water’s First Street Tunnel (FST) is comprised of a collaborative effort between DC Water, DC Water’s Project Consultants Organization (PCO) led by Greeley & Hansen and McMillen Jacobs Associates and the design-build team of Skanska, Jay Dee, and Parsons Brinckerhoff. The fast-track project includes elements that were designed by the PCO and released for construction by DC Water prior to Notice to Proceed (NTP) and elements designed by the Design-Builder from 30% to released for construction after NTP. This required effective communication and technical coordination for integrated engineering and efficient construction. The project, constructed in an urban residential neighborhood, included innovative construction methods such as multiple location ground freezing, utilizing a centralized freeze plant, to minimize community impact. The means and methods chosen for cast-in-place shaft linings, precast segmental tunnel lining, microtunneling, sequential excavation method (SEM) adits and near surface elements reflected the immediate and sensitive surroundings, which varied by construction staging area (CSA). Technical aspects of the project, relative to the evolution from pre-bid to construction documents, are discussed along with modified designs to suit means and methods. SCOPE OF WORK In 2012, four major storm events swept through the District of Columbia and hit the Northeast Boundary sewer shed particularly hard with the neighborhood experiencing severe flooding. The extreme nature of the flooding, the damage to private property, and the health risks associated with exposure to sewage led to a multi-agency response and community calls for answers and action. The Mayor assembled a Task Force to evaluate a range of potential actions to address combined sewer flooding including engineering, regulatory, code revision, and management improvements. The Northeast Boundary Neighborhood Protection Project was the outcome of the Mayor’s Task Force; it is a three-step infrastructure initiative designed to offload the undersized sections of the existing collection system that serves the Northeast Boundary drainage area by implementing the McMillan Stormwater Storage Project, First Street Tunnel Project and the future Northeast Boundary Tunnel Project. Until the Northeast Boundary Tunnel Project is completed, the First Street Tunnel Project will add 8 million gallons of combined temporary sewer storage in a new tunnel under First Street NW to relieve undersized sewers that traverse the Bloomingdale neighborhood."

Jan 1, 2016

By M. Seerane, R. Machaka, P. Ndlangamandla

"Metal injection moulding (MIM) is a near-net-shaping powder metallurgy technique suitable for the cost-effective mass production of small and complex components. In this paper, the effects of the metal powder particle size on the final properties of 17-4 PH stainless steel are reported. Three different particle sizes (d50 33.0, 7.91 and 4.04 µm) were used to prepare the injectable MIM feedstocks using a CSIR-developed wax-based binder system at a fixed solids loading of 60 vol.%. The distribution slope parameter and the rheological flow index behaviour were used to predict the flowability of the feedstocks. The effects of the particle size on MIM products were established. The results are discussed in terms of the subsequent microstructural and mechanical properties of MIM 17-4 PH stainless steel against the established MPIF Standard 35. IntroductionMetal injection moulding (MIM) is a near-netshape manufacturing process established as an alternative to produce complex small-tomedium shaped components that were previously fabricated by conventional methods at higher costs (Attia and Alcock, 2011; Todd and Sidambe, 2013).Although recent advances in micromanufacturing (mainly machining and electrodeposition-based) have enabled the fabrication of complex micro-size geometries directly into miniaturized parts, these processes are generally neither routine nor easily accessible at present (Attia and Alcock, 2011).Typically, the MIM process consists of four steps: mixing, injection moulding, debinding and sintering. Mixing involves blending of the desired metal powder composition with carefully selected multicomponent organic binders at the right proportion. This mixture, which is called feedstock, is then injected into a mould of a required shape to form a ‘green part’. Debinding is the removal of the binders by chemical, thermal, or catalytic means while maintaining the shape of the part. Finally, the debound part is sintered to a full or near-full density part (Sotomayor, Varez and Levenfeld, 2010). The MIM process is essentially a combination of plastic injection moulding with conventional powder metallurgy technologies."

Jan 1, 2016

By J J. Boshoff

This iron ore mine site, located in the Pilbara region of Western Australia, commenced operations in 1998, with ore derived by mining of open-cut pits in Channel Iron Deposits (CIDs). A portion of the ore extracted at the mine is processed at wet processing plants that produce both ore saleable product and waste fines (i.e. tailings) slurry. The waste fines produced at the wet plants are presently stored within Waste Fines Cells (WFCs).Waste fines cells A (WFCA) and B (WFCB) are located within an Autonomous Haul System (AHS) area and consist of embankments that span the width of the pit in east-west alignments. Technical studies and design analyses were carried out to support embankment raises and ongoing development of the WFCs. During operation and development of the WFCs, a multitude of simultaneous activities took place to the immediate north and south of WFCA respectively. These activities included the construction of the embankment raises using the AHS fleet, mining of the CID to not only mine the ore but to also create future deposition space for WFCB, blasting next to the WFC embankments as part of the mining activities, seepage collection and dewatering of the pit in the vicinity of the WFC.This paper discusses the material characteristics, design approach, construction staging and equipment requirements, blasting near embankments, water management, facility consequence category and closure concept.CITATION:Boshoff, J J, 2018. A waste fines cell with a multitude of concurrent activities, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 39–49 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

By Joseph W. Johnson

General Electric introduced electric drive systems on 85 ton Off-Highway mining trucks in the early sixties. Due to favorable economics, trucks have increased in size to handle larger payloads. Series Motorized Wheel systems were developed to meet this demand. When the technology was available, General Electric switched from use of Series motors to separately excited motors with the added benefits of static exciters and simplified control. Over 20 years of electric drive experience have been incorporated in the STATEX drive systems, which covers truck sizes from 85 to 220 tons. This paper traces the drive system developments from the early stages to the present and takes a look at what's ahead.

Jan 1, 1983

By P C. Hagan, J Chen, S Saydam

Fully grouted cable bolts have been used in underground mining industry for more than 40 years and are becoming more and more popular especially when severe geological conditions are encountered, such as high stresses and large cross-section excavations. The axial performance of cable bolts are mainly relied on the load transfer process between the cables themselves and surrounding rock masses via grout annulus. Therefore, the selected grouts play a significant role in determining the reinforcement quality for underground openings. In order to better understand the mechanical properties of Stratabinder HP grout, which is one type of cementitious grouts commonly used in Australian underground coalmines, plenty of unconfined compressive tests are conducted on it. Following diverse standards, two different kinds of samples are prepared and tested with the w/c ratio ranging from 0.35 to 0.45. During the test important mechanical properties including uniaxial compressive strength (UCS) values, Young’s modulus, Poisson’s ratios and so forth are recorded. Based on experimental results, the effect of w/c ratio on the mechanical properties of Stratabinder HP grout is studied. Beyond that, influences of sample size on the failure mode, peak strength as well as residual strength of this kind of grout are summarised and analysed.CITATION:Chen, J, Hagan, P C and Saydam, S, 2014. Mechanical properties of cementitious grout serving in fully grouted cable bolting systems, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 269–276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Art Hamid, Manfred Wong, R. John Caulfield

"The proposed Channel Tunnel is a critical component of the San Francisco Public Utilities Commission’s (SFPUC) Central Bayside System Improvements Project (CBSIP), which is a key element of a $6.9-billion sewer system improvement program to upgrade its aging and seismically vulnerable wastewater facilities. The tunnel will provide gravity conveyance and storage of combined sewage flows from the northeast sector of San Francisco, CA to the Southeast Water Pollution Control Plant for treatment. The tunnel will be approximately 2.7 km (1.7 miles) long and 7.3 m (24 ft) in internal diameter. It will utilize a single-pass precast concrete segmental lining system. Tunneling challenges include excavating with pressurized face tunnel boring machine (TBM) technology through highly variable ground conditions including the Franciscan Complex (rock and mélange), clayey/silty sands, stiff to hard clay (Old Bay Clay) and mixed-face conditions. The project will also require several deep shafts that will be technically challenging. Project backgroundThe SFPUC is a department of the City and County of San Francisco, CA that provides municipal power, drinking water and wastewater services to San Francisco.San Francisco’s combined sewer system collects both wastewater and stormwater in the same sewers, which is then pumped, treated to stringent state standards and discharged into the San Francisco Bay and Pacific Ocean. The sewer system includes tunnels, large storage/transport boxes, 1,600 km (1,000 miles) of collection sewers, 28 pump stations and three wastewater treatment plants. After decades of service, much of the system is nearing the end of its useful life.The existing system is also vulnerable to seismic damage. During the 1989 Loma Prieta earthquake, damage to SFPUC wastewater infrastructure was extensive. This included the 3,415 m (11,200-ft) long, 1.7m (66-in.) diameter Channel Force Main, built in 1976, and a critical component of the conveyance system. The Channel Force Main carries 70 percent of the bayside dry weather sewage flow from the northern and central part of the city to the Southeast Water Pollution Control Plant for treatment. It is antiquated, not pile-supported and not constructed to current seismic codes. There is also currently no conveyance redundancy for north/central bayside flows to the treatment plant. Figure 1 shows the SFPUC’s wastewater collection system, the existing Channel Force Main and the project location."

Jan 5, 2017

By B. Abedian, L. M. Racz, S. R. Berry, R. W. Hyers

"The presented work represents an effort to improve understanding and prediction of turbulent flow inside electromagnetically-levitated droplets. We show that the flow field in a test case, a nickel droplet levitated under microgravity conditions, is a low Reynolds number turbulent flow, i.e. in the transitional regime between laminar and turbulent. Past research efforts have used laminar, enhanced viscosity, and k - E turbulence models to describe these flows. In our study, we compare the RNG algorithm to laminar and k - E turbulence model results. We show that accurate description of the turbulent eddy viscosity µr is critical in order to obtain realistic velocity fields, and that µr cannot be uniform in levitated droplets. In the RNG method there are no characteristic length or time scales associated with the flow, thus allowing such anisotropic features to be captured. We perform calculations and analyses for two cases (1) a small, non-deforming, spherical nickel droplet and (2) a deforming, oscillating droplet. In addition to flow field calculations, we compare numerically-obtained surface tension and viscosity values to those obtained experimentally by the oscillating drop technique.IntroductionElectromagnetic levitation (EML) is a containerless processing technique for conductive materials. Its advantages are the avoidance of contamination or chemical reaction at container walls and the ability to perform long-term experiments in a metastable state. Because of its current limitation to small sample sizes, its primary use is in the laboratory. One application of interest is the measurement of thermophysical properties of undercooled liquid metals [1, 2, 3, 4]. In EML, a sample weighing approximately 1 gram is positioned inside an electromagnetic field generated by alternating currents flowing through an axisymmetric water-cooled copper coil. The coil must be designed appropriately so that thesample levitates in a stable manner.Traditionally, mathematical modeling has been performed in tandem with both earth-and spacebound electromagnetic levitation experiments, in order to determine the effect of the magnetic field on material and flow characteristics [5, 6, 7, 8]. These calculations are important because they allow design, planning, and correct interpretation of experiments. In addition, the calculations are of fundamental scientific interest, as they can be applied to other electromagnetic materials processing applications [9]."

Jan 1, 1999

By E. Onal, C. Craddock, A. Chapman, M. R. Endsley

ABSTRACT Mining equipment operators must interpret and respond to complex information delivered by technology-centric rather than user-centric systems. The ability to achieve high situation awareness (SA) in the face of this data overload is a key challenge to effective decision-making and information exploitation. Incidents attributed to human error that compromise safety and result in loss of revenue, or even life, are often the result of system designs that overload human cognitive capabilities. This paper defines SA as it relates to the operation of mining equipment and describes the design and preliminary evaluation of a new electric shovel operator user interfa

Jan 1, 2013

The ball level and pulp load play a key role in the operation of industrial scale ball mills. These two operating variables have a significant influence on the performance of the ball mill and any attempts to optimize these devices require manipulating either one or both of these variables. There are several models that can be employed to perform simulations to optimize the performance of industrial ball mills. However, most of these models require ball load and pulp load measurements as inputs to calibrate the model. The changes suggested by the simulator also provide operating regimes that involve moving either the ball level or pulp load and sometimes both of these variables. A ball mill model coded in JKSimMet was used in conjunction with the Sensomag to optimize the secondary ball mill at Waterval concentrator in South Africa. The results show that the perfect mixing ball mill model can be used in conjunction with the Sensomag to optimize the performance of the secondary ball mill.

Sep 1, 2012

By John Oskam

In 1873 Barton tines Corporation mining Garnets for Abrasives. From providing bulk Garnet Concentrate the technology has advanced to the sizing and classification of micron sized particles utilizing a Barton process. Processing of Garnet involves extensive quality control at all steps, first to insure product purity and secondly to insure the correct size range. Barton Mines produces about 30 different sizes of Garnet products to lead the world in the manufacture of technical abrasive Garnet. This paper will examine the present technology of Garnet Abrasive Manufacture and the specification to which the sizes are produced as well as some of the markets served.

Jan 1, 1980

By P. Condori

In spite of the importance of the slurry transport and discharge in autogenous and semiautogen-ous (AG/SAG) mills, it is evident that a more comprehensive and useful model is still required. Semi-empirical models used up to now have many limitations and cannot be used beyond the ranges in which they were developed. The breakage of particles as they are transported along a mill com-plicates the experimental analysis and the modelling of the transport process within the mill. The interaction of the grate discharge and the pulp lifters, with the added issue of backflow from the pulp chamber into the mill, makes the discharge modelling process difficult. In order to overcome these difficulties, a mechanistic approach has been applied. The general transport and discharge model was subdivided into four independent models: Flow through the charge, flow through the grate, flow in the pulp lifter, and flow-back. This paper gives an overall description of the modelling approach and discusses in particular the modelling of transport of fluids through the charge. In order to evaluate and calibrate the model, experimental work was carried out. To evaluate the gradient pressure under different conditions of charge packing and flow rate, a specialised experimental rig with a highly sensitive pressure gauge was used. Preliminary results identify the differences of the charge and grate on the restriction of flow. The existence of a dynamic voidage in our particular system was more evident and as a result, a semi-empirical correlation for the voidage was developed. In general, results show that the me-chanistic model derived from Ergun?s equation for flow through a packed bed can be satisfactorily adapted.

Jan 1, 2014

By C. G. Williams

IN preparing this paper on Canadian mine taxation, there has been no attempt to detail the requirements of the various taxing bodies; but rather to consider the matter from the standpoint of its underlying principles and give a general idea of the methods adopted. I have added an Appendix setting forth the principal features of the various Acts, which should be used for general reference only, since new rulings alter minor details from time to time. In current legislation, many important points are left to the discretion of the Ministers and their deputies. We are, indeed, fortunate in having in Canada an able and conscientious body of permanent officials, who bring a sense of justice and courtesy to their work which is most commendable, and which has done much to simplify the working out of general problems. The production of metals may rightly be deemed a form of manufacture, but differs from the average manufacturing business in three important respects: (1) In its early stages, it is wholly speculative, since it is impossible to make any definite appraisal of value or possibilities. (2) The principal asset of any mine, i.e., the ore in the ground, is a wasting asset, and is irreplaceable. (3) Any additional burden by way of taxation cannot be passed on to the public but must be borne entirely by the producer. Having regard to the first of these differences, it is apparent that, since the risk of loss is great, the reward in case of success must be correspondingly great. This fact seems to be constantly overlooked by those who regard the all too few outstanding successes in Canadian mining history as fit prey for predatory legislation. As an illustration of the speculative nature of early mining development, let us consider the Province of Ontario-and I take this illustration simply because I am more familiar with conditions there, and not because I believe it differs greatly from any other province. From 1907 to 1933, 165,243 claims were staked and recorded, from which 43 mines were developed which paid one or more dividends. There was, of course, some duplication through re-staking; also, on some claims very little work was done, and most mines have more than one claim. But, since staking and recording cost real money and effort, each of these claims must have been considered to have had merit.

Jan 1, 1935

By Kevin Galvin, James Dickinson

"The Reflux Flotation Cell (RFC) consists of an inverted fluidized bubbly bed, located above a system of parallel inclined channels. This novel arrangement enhances the hydrodynamics of flotation in a number of ways. Firstly, the free-surface of the flotation cell is enclosed via a fluidized bed distributor, ensuring uniform application of wash water to promote desliming. Secondly, foams can be variable in their stability and lack permeability. Hence this system is preferably operated in the absence of foam, instead opting for a bubbly zone of high bubble volume fraction through the use of a very high gas flux and/or wash water flux. Discharge of the product proceeds upwards through a central port of narrow cross-sectional area. Thirdly, the system of inclined channels increases the segregation between the bubbles and the water, ensuring the bubbly zone remains contained within the upper vertical zone, and the liquid flux reporting to the overflow is low. The expanded operating regime of the RFC was investigated by covering a very broad range of gas fluxes, up to 5.5 cm/s, and wash water fluxes, over 2 cm/s. Both laboratory and pilot plant performances were quantified by the recovery of hydrophobic particles and rejection of the hydrophilic particles, using model and industrial coal feeds. The new system hydrodynamics was found to offer significant advantages in flotation kinetics, desliming, and particle recovery across a broad particle size range. Bubble interfacial flux reached as high as 600 m2/m-2s-1. The upper system consists entirely of a high volume fraction of bubbles, which provides a "safety-net" to protect against the detachment of coarse particles, and a highly permeable zone for counter-current washing of the flotation product. Under relatively extreme conditions selective stripping of the product is observed, resulting in grade recovery values beyond those achievable using the tree flotation method."

Jan 1, 2014

By James A. Browning

Following an unsuccessful attempt earlier in the program to develop and market a drill channelling machine, we have designed and tested a new continuous channelling method which reduces operating sound levels to below 100 db. This new method relies on a small diameter oxygen-enriched burner to produce narrow channels. Sound intensities are reduced substantially compared to conventional channel widths. They are further reduced by a water spray directed immediately above the flame. Baffles placed along the top of the channel will reduce sound levels to below 90 db. Cutting rates are greater than those of existing channelling burners with costs per unit of channel area substantially reduced for those cases where oxygen costs are reasonable.

Jan 1, 1981

By W. K. Kleysteuber

This report covers the design and testing of a novel bulk materials conveying device by the Bureau of Mines. The transport concept of the device is to create a traveling wave with a steep front so that the bulk material slides and cascades down the front of the wave with some horizontal motion. Ideally, the front should act like a continuous chute. The concept of moving bulk materials along a belt without any forward movement of the belt itself was demonstrated. The conclusions reached were that the mechanism as designed could not overcome the inherent major disadvantages that would make the undulatory conveyor suitable for practical applications.

Jan 1, 1974

By Raymond M. Stateham

The Bureau of Mines evaluated temperature increases on the heads of resin-grouted bolts as indicators of the integrity of the anchoring of the bolt. Expected increases were calculated by the finite difference method; the calculations were checked by bolthead temperature measurements, both in the laboratory and in the field. The accuracy of the calculations varies with the validity of assumptions necessary to the process. Measurements in the laboratory produced a temperature rise of about 4.00 F on the head of a 4-foot bolt when installed with a full column of resin. This increase remained for about 30 minutes. Similar increases were noted on bolts installed at the White Pine mine, White Pine, Mich., but bolthead temperature increases in the mine lasted only about 10 to 15 minutes. When partial columns (reduced amounts) were used, the temperature increases were smaller.

Jan 1, 1976

By Gary H. Higgins

The paper by Lewis and Braun l presents experimental and calculational evidence that primary chalcopyrite ores are rapidly oxidized by warm oxygen-bearing water. Resulting solutions contained copper sulfate products of the matrix rock decomposition such as magnesium sulfate and sulphuric acid. Iron was oxidized to insoluble hematite and hydrous iron sulfates. Oxygen injection near the base of a broken and permeable flooded ore deposit was calculated to cause circulation of oxidizing solutions to the entire permeable region. The rate of dissolution of copper and degree of oxygen saturation for given oxygen injection rates were presented. Their work suggests that in-situ recovery of deep, disseminate primary copper deposits is technically feasible. The actual feasibility depends on economics and environmental safety as well, and it is the purpose of this paper to address these two aspects.

Jan 1, 1972