Vashisth, Divakar (Indian Institute of Technology, Indian School of Mines, Dhanbad) | Srivastava, Shalivahan (Indian Institute of Technology, Indian School of Mines, Dhanbad) | Agarwal, Aayush (Indian Institute of Technology, Indian School of Mines, Dhanbad)
No Free Lunch (NFL) theorem has logically proved that there is no meta-heuristic algorithm best suited for solving all optimization problems. We optimize the symmetrical bell shaped function using Whale Optimization. It is a swarm based meta-heuristic algorithm inspired by the hunting behavior of humpback whales. The exploitation phase involves both encircling and spiral hunting. Spiral hunting simulates the bubble-net attacking mechanism of whales. Balance between both exploration and exploitation phases help in converging towards a better solution. The potential field data satisfies Laplace’s equation which on a routine basis can be interpreted through analytical signal and can be approximated by a symmetric bell shape function. It is a non linear equation and depends upon the amplitude factor which is related to the physical property, the horizontal location, depth and the shape of the causative source. We inverted a synthetic magnetic data over two thin dykes with opposite polarity, field magnetic data from Barraute in Canada and field SP data over a Copper deposit in India. The synthetic results are in agreement with the assumed model while the field example agrees with drill hole data. These examples were also inverted through other two swarm based algorithms i.e., Grey Wolf Optimization (GWO) and Particle Swarm Optimization (PSO). The performance of WOA is comparable or better than that of GWO and PSO.
Presentation Date: Wednesday, October 17, 2018
Start Time: 1:50:00 PM
Location: Poster Station 4
Presentation Type: Poster
ABSTRACT: The Doe Run Resources Corporation Southeast Mining and Milling division (SEMO) mines lead, zinc, and copper in the Missouri lead belt using the room and pillar mining method. Retreat mining of pillars is then performed, resulting in large nonentry open stopes. The extent of pillar extraction is dictated by the predicted stability of the remaining pillars and of the resulting open stopes. Computer stress analysis methods are used to assess pillar stability, and the stability of the backs of the open stopes are assessed using empirical methods. This paper presents the evolution and refinement of the empirical back stability assessments conducted by Golder Associates and the Doe Run Company.
The large and often irregularly shaped stopes at the Doe Run mines make it difficult to assess back stability using common stability assessment methods, which use geometric inputs of inscribed circle span and hydraulic radius. Instead the Effective Radius Factor (ERF) measurement developed by Milne, 1997 is applied to consistently assess irregular stope geometries. An extensive empirical database with information from over 1000 locations has been established and statistical relationships have been developed to relate maximum ERF, rock mass quality, and stope back stability. The collection of such information allows engineers at the mine to more accurately assess stope stability as part of the process of optimizing pillar extraction.
The Doe Run Resources Corporation (Doe Run) operates five underground lead/zinc/copper mines and four mills in Southeastern Missouri. The mines are approximately 195 kilometers southwest of St. Louis in the Mark Twain National Forest.
Doe Run and predecessors of the company have been mining in southeast Missouri for more than 150 years and in the Viburnum Trend for approximately 60 years. Southeast Missouri and more particularly the Viburnum Trend are well known for the high-purity of the mineral deposits. The Viburnum Trend is a tabular flat-lying orebody that contains lead, zinc, and copper. Mining depths range from approximately 150 meters below ground surface at the far north end of the trend to 365 meters below ground surface at the far south end of the trend, a distance of approximately 65 kilometers.
Aluminum molds are frequently used in the plastics manufacturing industry. Relative to steels, aluminum alloys offer such benefits as lower weight, improved machining and polishing, and reduced cycle time due to aluminum’s significantly higher thermal conductivity. However, corrosion within cooling water channels in aluminum alloy molds is a common challenge. Exfoliation and intergranular corrosion are the main types of attack observed. Copper-bearing alloys, such as those in the 7XXX series, are commonly used. Those alloys are particularly susceptible to exfoliation corrosion, though such corrosion can occur in other alloys as well. Factors that promote corrosion of aluminum alloys will be discussed, including microstructural features, water chemistry, and operational practices. Case histories will be presented that illustrate the exfoliation corrosion mechanism and the problems that occur in plastics manufacturing systems. Methods for control of corrosion in these systems will be proposed.
Aluminum offers numerous benefits compared to steel for the manufacture of molds in the plastics manufacturing industry. Fabrication of molds and tools is easier in many cases because of better machinability and polishing of some high-strength aluminum alloys. The thermal heat transfer can be 4-5 times better than steel. This results in improved cooling rates and reduced cycle time for producing plastic components. The significantly lower weight of aluminum reduces power consumption and wear and tear on equipment and personnel. However, the service life of a mold needs to be considered when using aluminum. High-strength aluminum alloys are typically chosen so that the molds are durable and cost-effective for an extended run time. The molds include cooling water channels for temperature control; however, the interaction of the cooling water with the aluminum alloy is often not considered as part of the design process. With good design, maintenance practices, and careful control of water chemistry and treatment, molds can last for 10-20 years or more; however, corrosion of the aluminum, especially exfoliation corrosion, can cause failures, sometimes within a few months. Corrosion also results in increased expenses for retooling and decreased heat transfer. This paper discusses material, design, operational, and chemical factors that can influence corrosion of aluminum alloys used for molds and provides detailed examples in case histories that illustrate the factors.
Kansanshi Mining plc (KMP) experienced a number of multiple-bench instabilities in saprolite zones of the open pit walls. Although detectable with current monitoring techniques, these instabilities caused production delays and necessitated a re-design of weathered slopes. This process started through back-analysis of old failures to validate the suitability of material properties. Calibration of 2D models with field observations resulted in a downrating of the material properties. Different combinations of bench heights, berm widths, bench face angles, and overall and inter-ramp slope angles were analysed. Based on the modelling results, it became evident that for the mine to maintain larger bench heights, in order to increase stability, shallower slope angles would be required. Given the financial implications of shallower slope angles, design objectives were re-evaluated and modified. Smaller (bench)-scale instabilities require the catchment capacity of the berms to exceed the expected failure volume. This allowed slopes to be steepened by 1.5°. A ’double pre-split’ technique has been implemented so that the mine is able to blast two benches simultaneously. This enables the mine to operate efficiently through reduced cleaning, improved equipment efficiency, and a reduction in stoppages for blasting activities.
Kansanshi Mining plc (KMP) operates a copper mine in the North-Western Province of Zambia (Figure 1). Mining activities occur in two open pits; the Main Pit is the larger of the two, with a current depth of 170 m below surface and a strike length of 2.5 km, while North West Pit is shallower and smaller. The climate is subtropical with an average annual rainfall of 1.26 m occurring between the months of November and April. The final planned depth of excavation will be 530 m below surface with highly weathered rock masses extending up to 230 m from the surface. The deposit comprises a repeated sequence of phyllites, schists, and marbles with varying degrees of mineralization and weathering, both of which increase with proximity to veins and faulting.
Vallée, Marc (Memorial University) | Farquharson, Colin (Memorial University) | Byrne, Kevin (University of Alberta) | Lee, Robert (University of British Columbia) | Lesage, Guillaume (Consultants) | King, Julia (Consultants) | Chouteau, Michel (École Polytechnique de Montréal) | Enkin, Randy (Geological Survey of Canada)
The Highland Valley Copper (HVC) district has been studied in great detail via multiple methods, and through different disciplines as part of the Canadian Mining Innovation Council (CMIC) Footprints project. Following geological and petro-physical investigations, this district was also the focus of detailed aeromagnetic inversions over the common host rock phases and altered rocks. The inversions were conducted using geological constraints obtained from surface and borehole geology and physical properties constraints from hand sample measurements. These inversions outline areas of alteration spatially related to the porphyry Cu systems and mapped alteration in the HVC district.
Presentation Date: Wednesday, September 27, 2017
Start Time: 3:30 PM
Presentation Type: ORAL
Zelinka, Samuel L. (USDA Forest Service) | Jakes, Joseph E. (USDA Forest Service) | Kirker, Grant T. (USDA Forest Service) | Vine, David (Argonne National Laboratory) | Vogt, Stefan (Argonne National Laboratory)
ABSTRACTCopper based waterborne wood preservatives are frequently used to extend the service life of wood products when subjected to frequent moisture exposure. While these copper based treatments protect the wood from fungal decay and insect attack, they increase the corrosion of metals embedded or in contact with the treated wood. Previous research has shown the most plausible corrosion mechanism involves the migration of copper ions from the wood treatment through the wood to the metal surface, where they are then reduced. Despite this, under almost all conditions, copper has not been detected in the corrosion products as the proposed mechanism would imply.Recently, synchrotron based X-ray fluorescence microscopy (XFM) was used to examine the wood that had been in direct contact with metal fasteners in a corrosion test. These measurements showed a copper depleted region in the wood directly adjacent to the metal fastener. Based on the size of the region and the copper concentration, the amount of copper in the corrosion products was calculated to be on the order of 500 parts per million. This low concentration explains why previous attempts to find copper in the corrosion products using scanning electron microscopy, energy dispersive X-ray spectroscopy, and powder X-ray diffraction were unsuccessful.Here, we present XFM maps of corrosion products removed from corroded fasteners that had been in contact with preservative treated wood. The XFM maps of the corrosion products clearly show the presence of copper. These measurements definitively confirm the mechanism of corrosion in treated wood and give further insights into where and how the cathodic reaction takes place.INTRODUCTIONIn typical wood construction, metal fasteners are used to join wood to wood or other construction materials. These metal connectors are subject to corrosion from moisture and organic acids within the wood.1-5 In certain cases, wood preservatives or fire retardants are added to the wood and these chemicals affect the corrosiveness of the wood.6
ABSTRACTNickel-Aluminum Bronzes often referred to as NAB are a group of Cu-based alloys containing about 3-6% Ni, 8-11% Al, 3-5% Fe and 1-3% Mn. These alloys have excellent physical properties such as fatigue, creep and wear as well as excellent resistance to different forms of corrosion such as general corrosion, cavitation, erosion and de-alloying. Hence, they find widespread use in marine environments as components of ships and industrial process equipment handling seawater. However, the corrosion resistance of these alloys can be adversely effected by their metallurgical structure which in turn depends upon the exact composition of the material and their manufacturing history - especially the thermal treatment to which they have been subjected.This paper will present two case studies of pre-mature failure of process equipment in seawater service which will illustrate the influence of metallurgical structure on the service performance of NAB in marine environments.INTRODUCTIONNickel-Aluminum Bronzes often referred to as NAB find widespread use in marine environments as components of ships and industrial process equipment handling seawater. They are used in a wide variety of marine applications including valves and fittings, ship propellers, pumps, valve stems, heat exchanger water-boxes, offshore structures as well as in chemical, petrochemical and desalination plants.1,2NAB are a group of Cu-based alloys containing about 3-6% Ni, 8-11% Al, 3-5% Fe and 1-3% Mn. These alloys have excellent physical properties such as fatigue, creep and wear as well as excellent resistance to different forms of corrosion such as general corrosion, cavitation, erosion and de-alloying. The corrosion resistance and service performance of these alloys can however, be adversely effected by their metallurgical structure which in turn depends upon the exact composition of the material and their manufacturing history - especially the thermal treatment to which they have been subjected. Nickel-aluminum bronzes are complex alloys from a metallurgical viewpoint and small variations in composition can result in the development of markedly different microstructures. The various alloying elements impart different properties to the alloy and together with specific heat treatments, alter the microstructure.2 Nickel improves corrosion resistance while Aluminum increases the tensile strength of the alloy. Iron acts as a grain refiner and enhances tensile strength. Nickel also improves yield strength, and both nickel and manganese act as microstructure stabilizers.2
ABSTRACTNickel Aluminium Bronze (Ni-Al Bronze) is a copper alloy with addition of Al, Ni and Fe. Several intermetallic particles precipitate during cooling of the alloy, contributing to a high complexity of both phase distribution and phase composition across the surface. Cu, Al, Ni and Fe have different corrosion potentials and corrosion properties in seawater, and for some of the elements, these properties are sensitive to changes in pH. The corrosion properties and pH sensitivity of Ni-Al Bronze reflect the behavior of its alloying elements, and behave like copper in neutral pH, and as Ni and Al at low pH. The work presented her is mainly focused on the corrosion mechanism at low pH (>4) and the order of which the discontinuous and continuous intermetallic phases dissolve. Further, the phase compositions of each phase, and the area ratio between intermetallic phases and the alpha matrix have been calculated as an average of 20 measurements. The corrosion properties and pH dependency of the alloy is compared to the corresponding properties of the alloying elements. The results suggest that Ni plays a significant role in the corrosion properties of Ni-Al Bronze.INTRODUCTIONNi-Al Bronze is a complex alloy where number of different intermetallic particles are precipitated during cooling from molten state. The main alloying element is Al (up to 12 wt. %), which contribute to a large increase in mechanical properties and corrosion resistance of the alloy. However, too much Al causes precipitation of a brittle and corrosive phase named Y2-phase. Additions of Ni and Fe decrease the risk of Y2 formation, as these elements precipitate together with Al to form other intermetallic phases named kappa-phases. The kappa-phases themselves also contribute to an increase in mechanical properties, and the presence of Ni increases the corrosion resistance of NAB. In brief, by adding some Fe and Ni, one can add more Al, and further increase the mechanical properties and corrosion resistance of the alloy, without risking formation of Y2-phase.1
Michel, James H. (Copper Development Association Inc) | Richardson, Ivan (Copper Alloys Ltd) | Powell, Carol (Copper Development Association Inc) | Phull, Bopinder (Copper Development Association Inc)
ABSTRACTSince antiquity both wrought and cast forms of copper alloys have exhibited significant corrosion resistance in marine environments. Their properties have been developed and modified over the years to meet today's exacting engineering challenges and continue to offer solutions to a range of industries requiring reliability in seawater including commercial and naval shipbuilding, offshore seawater- handling and firewater systems, and thermal desalination plants. This paper describes the range of copper alloys in marine service today and the evolution of applications which include ships' cannon and hull sheathing in 18th and 19th century and condenser and seawater piping requirements which spurred concentrated investigations in the 20th century. The latter led to the development and introduction of copper-nickels and nickel aluminum bronzes (NABs), which are now the most widely used marine engineering copper alloys. The direction of future developments is also discussed.Technically, the paper covers the influence of refined composition and/or heat treatment which have optimized the properties of copper-nickels and NABs in terms of localized corrosion and erosion- corrosion resistance. It also discusses the importance of correct commissioning and shut down procedures to ensure that the full capabilities of copper alloys are achieved.INTRODUCTIONAlongside gold, copper is the oldest metal used by man and its history of use dates back 10,000 years. Since antiquity both wrought and cast forms of copper alloys have shown high resistance to the ravages of the marine environment. Seawater is aggressive to most construction materials and, with properties which have been developed to meet today's exacting engineering challenges, copper alloys continue to offer reliable solutions to a range of seawater applications. Notable marine industries currently using copper alloys are commercial and naval shipping, thermal desalination, power generation and offshore oil and gas.Initially, copper was used for its availability, ease of fabrication and corrosion resistance. Additional properties, such as high thermal conductivity, excellent electrical conductivity and inherent high resistance to biofouling, became appreciated with time. Its facility to be easily alloyed with other elements such as tin, zinc, aluminum, lead, silicon, beryllium, iron, chromium and nickel led to a plethora of different alloys being produced providing a combination of improved strength, erosion- corrosion (impingement) resistance and galling resistance.
ABSTRACTTungum alloy (UNS C69100) is an aluminum-nickel-silicon brass and is reported to have a good corrosion performance in marine environments (fully wetted, splash zone and atmospheric conditions). In order to gain an in-depth understanding of the marine corrosion performance of this alloy, electrochemical test methods including open-circuit potential, electrochemical impedance spectroscopy, potentiodynamic polarization, and zero-resistance ammetry were used for corrosion investigation of UNS C69100 in a 3.5 wt.% sodium chloride aqueous testing solution, in combination with optical microscopy and scanning electron microscopy. The corrosion properties of UNS C69100 obtained by electrochemical methods were also compared with six alternative alloys: UNS S31603, UNS S31254, UNS S32750, UNS N04400, UNS N08904 and UNS C36000. Galvanic coupling behavior of wrought UNS C69100 bar and seamless tubing against these six alloys in a 3.5% NaCl solution for 30 days immersion are also reported in this paper.INTRODUCTIONTungum alloy(1) (UNS C69100) is an aluminum-nickel-silicon brass (chemical composition: 81-84% Cu, 0.70-1.20 Al, 0.8-1.40 Ni, 0.80-1.30 Si, with the remainder Zn) and is reported to have good corrosion performance in marine environments (fully wetted, splash zone and atmospheric conditions) from many years' service experience. UNS C69100 tubing was reported to have best localized corrosion resistance among six metallic materials (316L, Alloy 825, 317LMN, 254 SMO, Alloy 625 and UNS C69100), judged by crevice corrosion and pit depths when exposed to a cyclic salt fog environment (ASTM D 5894 – alternating 1 h wet and 1 h dry conditions, with temperatures varying between 35 °C and 45 °C).1 In the same report, eight alloys (316L, 317 LMN, Duplex, 254 SMO, Alloy 825, Alloy 625, Alloy 400 and UNS C69100) underwent field trials on two offshore platforms for one year. Again C69100 performed well, although there was evidence of shallow pits but with a relatively high pit density, the UNS C69100 outperformed 316L (30 μm vs. 90 μm seen on 316L). Overall, C69100 was recommended as a good alternative to 316L for small bore tubing in marine applications.1 To date, there appears to be scant data available about the corrosion behavior and galvanic performance of UNS C69100 alloy in marine environments. La Que2 has ranked the open-circuit potentials of many metals and the effects of coupling common alloys in seawater. This ranking on its own is often not necessarily sufficient to enable a satisfactory materials selection free from galvanic corrosion since it neither considers cathodic efficiency nor the underlying corrosion mechanisms of the couple components.3 The marine corrosion behavior of the least noble or anodic component is thus important. For instance, unlike stainless steels, copper alloys in seawater do not have a truly passive layer but rely on a tenacious protective oxide film, which limits the rate of metal dissolution, although copper-based alloys generally suffer general corrosion which is increased when coupled to a more noble metal / more corrosion resistant alloy. Wallen and Andersen4 reported that most copper alloys when coupled to equal areas of stainless steel have increased corrosion rates by a factor of seven in natural seawater. However, since the free corrosion (single metal / uncoupled) is generally very low, the increase can often be acceptable, especially for thick walled components.