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By Frederick McNeill, John Harper, Mahmood Khwaja, Shawn Lavoie, Timothy Cloughert, David Polcari

City of Manchester, NH, is implementing a 20-year plan to control and significantly reduce overflow of its sewer system. The long-term control plan had called for large scale box culvert installation through downtown Manchester. The City and the project team evaluated, and eventually selected, tunneling as an alternative to mitigate construction related impacts for open trench approach. This paper provides an overview of the alternative evaluation process; discusses the development of the preliminary design for the 12,000 feet long, 12-ft internal diameter tunnel, including plan and profile selection, subsurface conditions, drop shafts and the anticipated packaging of the separation areas.

Dec 1, 2022

By K. S. McClure, S. B. Chitralekha, R. B. Gopaluni, Chmylek. T., S. L. Shah

This is a tutorial paper on industrially successful approaches for nonlinear process monitoring. Online process monitoring is essential to continuous operation of plants at high efficiency. The problem of process monitoring is one where an impending but undesirable process condition has to be identified and used to alert process engineers. This problem has traditionally been solved by practicing engineers using statistical techniques that detect a change in the underlying correlation structure of process variables. For linear correlation structures, algorithms such as principal components analysis, independent component analysis and partial least squares have been proposed. However, many industrial processes exhibit nonlinear correlation structure between the process variables. In this tutorial we describe various nonlinear monitoring techniques and elaborate on two recently developed methods, namely Support Vector Machine and Local Linear Embedding. The two methods are evaluated by application on two experimental case studies, a SAG mill and a polymer extruder.

Jan 1, 2014

By H. Lagendijk, I. J. Reinecke

Mintek was contracted by Oriel Resources plc in 2004 to conduct a preliminary assessment study on smelting ferronickel from the large but relatively low grade Shevchenko nickel ore deposit in Kazakhstan. A detailed feasibility study (?DFS?) was awarded to Bateman BV following promising results from the preliminary assessment study (?PAS?) and small-scale pilot plant test work. As part of the DFS, a total of 450metric tons of ore was collected from three different locations in the deposit and shipped to Mintek. After sampling, the bulk sample was prepared for smelting. This comprised crushing, screening and calcining with each step done separately for the three different lots. The chemical composition of the ore from the deposit is relatively high in silica and therefore falls out of the MgO to SiO2 range that is normally processed by pyrometallurgical means to produce ferronickel. The main objective of the testwork was to demonstrate that a method could be found and successfully applied to smelt these siliceous ores and produce an acceptable nickel-containing alloy. A 2-m ID DC arc furnace was installed with a twin-cathode (electrode) configuration to replicate the proposed commercial-scale furnace and also incorporated an advanced design of water-cooled copper panels in the lower furnace sidewalls to withstand the aggressive nature of the high SiO2-containing slags. The reductant used was a high-volatile coal from Karaganda in Kazakhstan. The reductant addition was adjusted to achieve a 90% recovery of nickel. In the assessment of the process metallurgy, some deviation from equilibrium conditions was observed. This deviation is ascribed to the intermittent existence of a smelting bath partially covered with feed during the testwork. Optimization of smelting conditions should result in the metallurgy (slag metal equilibrium) being closer to the theoretical predictions and make the production of a 20% nickel alloy possible at 90% nickel recovery. The solution for the successful processing of these siliceous ores was found in the attainment of the necessary operational stability through the control of arc length, operating temperature, open-bath smelting conditions and flux additions of up to 10% dolime for the most siliceous of the three ore types. The test work carried out by Mintek provided the basis for the process flow sheet and engineering design of the DC arc smelting furnaces for the Shevchenko Nickel project.

Jan 1, 2007

By Jerome S. Brower

Quadrex-L is a two component liquid explosive which was developed by J. S. Brower & Associates, Inc. to facilitate handling and shipping, and use in unique applications, while emphasizing safety. It may be advantageously used for all explosive applications. Quadrex-L can be introduced into a preinstalled container configuration and may be easily drained or flushed from these containers when necessary to do so. This characteristic can be effectively utilized to reduce the hazard period during assembly or disassembly operations.

Jan 1, 1975

By Ross W. Smith, Xiapeng Zheng, Merrill P. Allen

The results of flotation of a primary desliming hydrosizer overflow material containing 14.6 wt.% P20, and 3.6 wt.% MgO are presented. The phosphate minerals were collophane and francolite and all minerals appeared to be liberated. The material had not been previously treated with flotation reagents. In the experimentation, various collectors were evaluated for effectiveness. The relative effectiveness of flotation in different flotation devices was determined. Finally a two-stage flotation scheme is proposed using column flotation of dolomite in the first stage and Denver cell flotation in the second.

Jan 1, 2002

Prediction of fragmentation by blasting is most commonly based on theassumption that a single distribution of pre-existing discontinuities is present within a blasted rock volume and that the underlying mechanism of failure is tensile failure. It is assumed that the tensile stress field created by a blast initiates and extends radial cracks around the blastholes. Interaction between radial cracks from different blastholes and the free surface creates rock fragments. In reality, fragmentation of the rock occurs due to two mechanisms.One is related to the compressive-shear failure of the rock (mainly rock matrix) close to the blastholes, while the second mechanism is the previously mentioned tensile failure of the rock mass. The secondmechanism of failure occurs in the form of extension of the larger cracks in the region beyond the crushed rock, and this type of fragmentation occurs after the crushing phase. In the case of hard rock or blasting where the extent of crushing is minimal, the currently used prediction methods give a reasonably good result. However, there are many blasting conditions where the amount of rock crushing is significant. In the case where fragmentation of the given rock volume occurs dueto two different mechanisms, modeling of the rock fragmentation with a single distribution function is not appropriate. To model the fragment size distribution generated by two different mechanisms, it is necessary to use a two-component fragment size distribution function and a scaling parameter that will determine the proportion of the fragmented volume created by each mechanism. The purpose of this paper is to present results of blast fragmentation modeling based on two mechanisms of failure. The two-component model (TCM) utilises experimentally determined parameters from small scale blasting and parameters of the Kuz-Ram model, for more accurate prediction of the complete rock fragment size distribution curve. The methodology is such that it is possible to predict complete fragment size distribution, including fines, of ROM product for a future mine, at the feasibility phase of mine design.

Jan 1, 1999

By Anthony D. Hammond

INTRODUCTION A two-dimensional approach for modeling narrow-vein deposits using the TECHBASE® software was implemented at Sunshine Mining for its use in the evaluation of mineral properties. This 2-D approach prevents the overestimation of high-grade tons typically associated with the use of fixed 3-D blocks and reduces the size of the model in computer memory. The method consists of constructing a two-dimensional model oriented along the average plane of the mineralized structure. This approach works well for single, multiple and intersecting veins with the condition that each vein is roughly planar with variation in dip or strike less than 30" in order to maintain a reasonable resolution in the process of projecting data onto a plane (Figure 1). Also, a precise identification of the hanging-wall and foot-wall location is critical in ensuring an accurate representation of the vein. By using various modeling techniques, the two-dimensional model estimates metal content, thickness, tonnage, economic and dilution parameters which will be ultimately used in the identification of minable reserves. The following is a generic description of the steps involved in modeling a steeply dipping vein. DATA ENTRY A typical project database consists of drillhole coordinates, survey information, assay data and any other quantitative or qualitative data. This database can be created inside the software or imported from any spreadsheet. TECHBASE® utilizes the concept of "fields" and "records" (columns and rows) for storing data. The use of "calculated fields" enables the user to expand on the manipulation of the database with minimum memory requirements. Another important feature of TECHBASE® is the ability to replicate the structure and format of the "tables" for its use in another project and the capability of running a series of repetitive tasks by means of batch and "runlog" files.

Jan 1, 1998

By Rilung Xu, Jerry C. Tien, Jian Liu

As underground mines become deeper and ventilation networs more complex, ventilation data becomes more complicated and voluminous, making timely ventilation planning and necessary changes more difficult. Oftentimes, ventilation engineers have to rely on special techques using graphs and schematic maps to carry out necessary ventilation planning [1, 4, 5, 6, 9, 10, 11, 12]. A different graphical method, similar to that reported by Taminago and Isobe [10], has been developed in China [13]. This method uses a two-dimensional diagram drawn from available ventilation survey results. It combines both the customary pressure-quantity diagram and ventilation schematic map, and can greatly expedite the interpretation of survey results, facilitate ventilation system design, short and long-range planning, and emergency planning.

Jan 1, 1993

By A. Deneys

An experimental technique has been devised for studying the reaction kinetics of the reaction: ZnO + 2Fe0 = Zn(g) + Fe203, by which zinc evolution can occur from a molten slag bath in the absence of a carbonaceous reductant. When studying the reaction kinetics by heating from room temperature, solid state reactions and poorly defined melting points may obscure the starting point of the reaction. In order to eliminate this problem, an experimental technique was devised whereby two molten slags could be melted independently, and then mixed, to provide a well defined starting point from which to begin taking measurements. Two crucibles were mounted in a vertical reaction cylinder. The upper, mild steel, crucible had a bottom pouring plug which was sealed by a steel stopper rod. A fayalite mixture was contained in this crucible. The lower crucible contained an A12O3-CaO-SiO2-ZnO solution. Once the two slags had been melted, the steel stopper rod was removed from the upper crucible. The upper, reduced slag (fayalite in equilibrium with the upper steel crucible), drained into the lower crucible where the two slags were mixed by submerged argon stirring. Dip samples were taken to measure the zinc content of the final mixture as a function of time. The experimental procedure will be described, as well as results of experiments which were conducted on synthetic slags. The system investigated was similar to the lead blast furnace slag which is produced by the primary lead smelters of Missouri, USA.

Jan 1, 1997

By Emilie S. Williams

The Doyon Mine?s Zone 1 (Altered Zone), found along the southern boundary of the mine, encompasses approximately 20% of the mining reserves. The mineralisation is found in a series of steeply dipping narrow veinlets, which are contained in an extremely weak host rock: a sericitic schist with RQD values ranging from 0 to 20. Longhole mining methods are used, with either longitudinal or transverse approaches, depending on the width of the ore zone. Dilution is of critical importance in the mining of this zone, particularly in longitudinal stopes, where dilution levels have averaged 55% since 2000. Major factors influencing dilution in this zone include the stope geometry and standup time. A two-phase approach has been developed to mine and backfill longitudinal stopes: the top of the stope is pastefilled after approximately half of the broken ore has been extracted; the remainder of the ore is extracted once the plug has cured; and the remaining void is filled. This method has been used in six stopes to date, resulting in an average dilution of 17%. This paper details the application of this technique and its effect on dilution.

Oct 1, 2004

By W. Song, C. Richards, B. Q. Li

"This paper presents a two-phase flow numerical model for spouting gas-particle flow reactors used in chemical vapor deposition processes for manufacturing heart valves and other biomedical implants. The model is developed based on the Eulerian-Eulerian formulation of gas-particle flows, with the k-e engineering model modified with the presence of particles for the description of turbulent gas flows. In parallel with the numerical model development, physical models are set up, where the particle image velocimetry is used for visualizing the particle flows and spout shapes and heights and optical probes are used to measure the particle velocities. The numerical model predictions are compared reasonably well with the experimental measurements.IntroductionVarious biomedical implant components, such as bone joints, dental components and heart valves, are coated with bio-compatible thin films by chemical vapor deposition in particle-laden chemical reactors [l-5]. In these reactors fine particles are used as packing and supporting media. During the coating operation, these packed particles are fluidized by an upward gas jet from the nozzle, reach a certain height and fall back on the top of an annulus region. These recirculating particles are mainly for levitating the implant components (usually one or two in a reactor at one time) so that every portion of them is equally exposed to the gaseous atmosphere. An equal exposure is critical for forming a uniform, mechanically strong and corrosion-resistant coating on implants. Plant experience shows that the quality of the coating is directly related to a stream of operating parameters such as temperature, particle size and loading, and gas flow rates [6]. Optimization of these operating parameters for improved reactor performance depends crucially upon our fundamental understanding of the physics governing the gas-particle flow, heat, and mass transfer phenomena taking place in these reactors."

Jan 1, 2004

By A. García-Gutiérrez, A. Aragón-Jerónimo, R. Salazar-Mendoza

A theoretical analysis of a two-region solid-liquid flow system in horizontal pipes is presented, which considers a stationary bed of drill cuttings as a porous medium (-region) below of a two-phase dispersed flow (-region).The method of volume averaging was applied in this study to derive a rigorous mathematical model in which each variable is precisely defined. This model includes the volume-averaged transport equations for both the two-phase dispersed flow and the porous medium regions and terms from a macroscopic forces balance. The solution of the two-region model allowed evaluation of the behaviour of pressure gradient as a function of velocity, total volume fraction of cuttings and the relationship of the height of the stationary bed and pipe diameter. The solution is based on a backward finite difference explicit scheme. The simulated physical system is a pipe of 4.135 m in horizontal length and 0.0508 m in diameter. A one-dimensional, mesh-centred grid, consisting of 100 nodes, is used. The numerical results were compared with experimental data on slurry flows and a good agreement was found. Keywords: two-phase, cuttings transport, solid-liquid flow, drilling modelling, volume averaging.

Jan 1, 2007

By R. H. Nafziger

A novel process has been developed for preparing directly workable steel ingots from prereduced iron ore pellets by a two-stage process. The pellets are continuously charged into an electric arc furnace, where molten metal is separated from the gangue. The molten metal flows out of this furnace through a hollow nonconsumable graphite electrode immersed in a molten flux in an electroslag furnace. The molten metal solidifies on a continuously withdrawing base plate to form the ingot. A variety of standard carbon and alloy steel ingots . free of porosity , were produced using suitable decarburizers and ferroalloy additions. Some advantages of the two-stage process include: (a) consumable electrode fabrication is eliminated; (b ) no expensive deoxidizers are required; (c ) the uncontaminated electros lap flux can be reused; (d) energy consumption averages 25% less than in a conventional electric arc - electroslag operation ; and (e) the operation is continuous.

Jan 1, 1977

By Alireza Kamrani, Yashar Pourrahimian, Hooman Askari-Nasab

In-pit crushing and conveying (IPCC) is an option to decrease the enormous operating costs that a truck shovel can introduce in an open-pit mine. Finding the best locations for the IPCC over the mine life will impose a new set of requirements for the mine planning. Through a two-step mathematical programming model alongside the road network, this method finds the optimal in-pit crusher locations and relocation times first and then optimizes the long-term mine schedule. The model is verified by a real mine. The results show that the truck travel time could be reduced by 500% and the discounted cash flow increased by 8% with an optimized schedule considering the crusher placement.

Jun 25, 2023

By HaiWen Luo, Bin Hu

A ultra-high strength medium Mn steel with good ductility was designed and manufactured via the combination of warm rolling and V alloying, which produced not only the extensive precipitation of fine VC particles in both ferrite and austenite but also the bimodal size distribution of retained austenite (RA) grains. A substantial increase of yield strength up to 650 MPa was achieved due to the addition of V without deteriorating ductility. The coarse RA grains firstly transformed to martensite during yielding at the much higher stress threshold, followed by a significant work hardening due to dislocations multiplication, twinning-induced-plasticity (TWIP) and transformation-induced-plasticity (TRIP) in the ultrafine RA grains. The best combination of strength and ductility included 1.5 GPa ultimate tensile strength and 28% total elongation. This was achieved due to the sustainable TRIP and TWIP effects in the later straining stage resulting from the ultrafine austenite grains, the latter were reversely transformed from the recrystallized ferrite grains.

Oct 1, 2019

By P. T. Nguyen

The analysis of particle capture by an air bubble by two separate phenomena of collision and attachment has been difficult due to the uncertainty in determining when and where the two phenomena begin and terminate at the bubble surface, respectively. Therefore, a unified analysis was developed by solving the motion equation for the particle capture as one process. No distinction be-tween collision and attachment was made. Both the liquid film described by the micro-hydrodynamic resistance functions and the surface forces were included in the new model. The model predictions with the DLVO (Derjaguin-Landau-Verwey-Overbeek) surface forces did not agree with the experimental trajectories of latex and silica spheres. The model predictions with the inclusion of the non-DLVO attractive surface force agreed with the experimental data. The non-DLVO force reduced the repulsion between the non-attaching particle and the bubble, and significantly increased the attraction between the attaching particle and the bubble. The unified analysis is capable of predicting particle capture without the use of the induction time. The unified analysis also shows significant influence of the short-range hydrodynamic interactions on the collision which has been previously ignored.

Jan 1, 2014

By G. V. Krishnan, L. Adler

A rock classification for drilling and boring is presented covering most equipment types and providing an estimation of the key parameters for operation, such as thrust and speed, and of performance such as penetration rate and bit life. Drilling and boring are significant and integral aspects of both the mining and heavy construction industries. Together these constitute over 20% of the G.N.P. Drilling and boring represent the most arduous mechanical processes performed in industry. Their misapplication quickly leads to equipment destruction, hazards, and to major delays. The classification is unified in two ways: 1) for a particular rock class several parameters can be estimated, 2) the classification integrates most excavating activities (i.e. digging, ripping and even blasting), and is derived from ground control. The rock classification provides a job property, based on fundamental and index properties, which yields quick and rough estimates of vital information. However it does not obviate the need for a more thorough analysis, and maintaining field records. BACKGROUND In order to adequately describe a drilling operation the conditions, activity, and equipment must be characterized. Of these the major independent variables are the conditions. Conditions focus on the geologic mass and also consider whether the site is surface or underground. The primary component of the geologic mass is the rock type, detailed below in Rock Characteristics. The other components

Jan 1, 1983

By Heather Wright

Shovel operators are one step closer to having a better tool to operate and monitor their equipment. The development of a unified shovel interface is proceeding into phase three, focused on producing a standard application programming interface (API) for connecting onboard devices. This solution will positively impact safety, performance and productivity, and is the result of collaborative work driven by the Global Mining Standards and Guidelines Group (GMSG). Proof of concept revealed During the spring of 2013, Peck Tech Consulting was engaged to develop the working proof of concept (POC) software implementation, which integrates multiple vendors? systems into a single interface using one-to-two displays. As a result, the GMSG developed a functioning, manipulatable, unified shovel interface proof of concept and unveiled it at the World Mining Conference in August in Montreal. The proof of concept effectively provides a unified operator interface that pulls together the many divergent systems onboard large shovels.

Mar 1, 2014

By Sherwin Kelly

THE need for geophysicists to adopt a uniform mode of expressing the electrical resistivity of geological formations has been stressed by Dr. A. S. Eve.1 The present paper is to emphasize the point he raised, to bring the weight of disinterested authority to bear on the matter, and to urge the adoption henceforth, save in exceptional cases, of a standard expression for resistivity; all in the hope that the needed reform will thus actually be brought about. The general definition of the resistivity of a material is the resistance in ohms between two opposite faces of a unit cube of that, material. No account need be taken here of the cases in which the unit volume is not a cube, and the units of length and cross-section are different, encountered principally when dealing with metallic conductors such as wires. The idea of the resistance of a unit volume of earth or rock has found expres-sion in geophysical literature in a number of forms and with a variety of units. Fortunately, the metric system has been adhered to in most cases, so ordinarily the meter or the centimeter, usually the latter, has been the measure chosen. The resistivity is then the resistance of a cube of the given rock, or soil, one centimeter on, an edge. This is far from always being the same thing, however, as the resistance of a cubic centimeter. A long thin wire could contain a cubic centimeter and have a high resistance, whereas the same volume formed into a flat plate would have an entirely different, and quite low, resistance between faces. Con-sequently, it is not proper to express resistivity in ohms per cubic centi-meter, inch, etc., as has been done occasionally by .some writers. In an effort to emphasize the idea of cubic volume, some geophysicists, the writer among them, have used the phrase, ohms per centimeter cubed. This is a graphic way of picturing the measure, but is not in favor among highly qualified authorities. In this connection, an appeal was made to the U. S. Bureau of Standards for advice, and the Director, George K. Burgess, kindly replied in detail as to the practice adopted by his Bureau: ." . .' such expressions as ohms per centimeter cubed' or any similar expressions are objectionable, because they certainly carry the implica-tion that the resistivity is found by dividing ohms resistance by the volume in cubic centimeters." Actually, of course, resistivity is found

Jan 1, 1932

By John Randall

IT is a fair assumption that the main purpose of any diagram is to present facts to the eye in more convenient form than they could be tabulated in figures, and this implies that a screen diagram should set forth in a convenient and familiar form certain facts as to the character of the material screened regardless. of the screen standards used, and it seems particularly desirable on account of the well-known differences in the size of openings of different laboratory screens having the same nominal mesh. In making screen-sizing tests it has been customary to first consider the largest size, going progressively to the smallest, and this seems to have led to the practice of placing the smallest size at the right-hand side of the diagram and .measuring toward the left. This is not altogether convenient and might he changed to advantage, but for illustration I have preserved that feature and present the method just as I have used it for over 2 years. Direct plotting in which the intervals on the diagram are proportional to the sizes of the openings, or to the arithmetical difference between them, seems at first sight more natural and is extremely useful for certain purposes, but it makes the diagram very crowded in the smaller screen sizes while the larger ones occupy unnecessary space, snaking it less convenient for most purposes, and for that reason the method here discussed is the well-known one based oil the ratio between openings, and is plotted in logarithms instead of the direct values of the screen opening. Metric coordinate paper is convenient, although .not necessary; it is recommended, as the use of the metric scale gives a diagram of convenient size, but any scale of equal. parts may be used. In order to make any screen diagram translatable in terms of any standard screen size, it is necessary to have rioted on the size scale of the diagram all points corresponding to the openings of the various screens in question, instead of a single series 'of points as with a single screen. In drawing the diagram assume 0.001 in. (corresponding approximately to 0.025 mm.) to be the smallest size to be considered and fix this as the zero point at the lower right-hand corner of the diagram. This value is selected because the values are to be plotted in logarithms, and the logarithm of 1 is zero. Then lay off to the left for the position of each screen

Jan 9, 1917