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By R. Pandher, R. Schonewille, N. Tripathi

Advanced process modelling tools were developed for the Xstrata Nickel Sudbury Smelter flow sheet using a combination of FACTSAGE TM METSIMTM and ARENATM software. These tools were employed to assist with plant optimisation, emission control, process design, troubleshooting and case studies as applied to the smelter. The development of process modelling tools in pyro-metallurgy commonly involves an in-depth study of the therm o-chemical properties (heat capacity, liquidus temperature, etc.) of all high temperature phases, usually matte and slag. The preferred tool for this purpose is FACTSAGETM, a well-known then-no-chemical modelling software package. The results from the therm o-chemical model have been subsequently incorporated into the development of a process model for the entire smelting facility using the METSIMTM platform. Such process model also includes a number of special features adopted to effectively simulate the complex industrial phases; matte and slag systems. To ensure the robustness and reliability of the process model, several process parameters and assumptions were verified with laboratory and plant data. Consequently, the model includes the ability to examine the impact of a number of plant parameters on potential plant performance. Primary variables are the percent sulphur elimination during concentrate roasting, furnace matte grade and degree of matte metallization. Key output parameters include operating temperature, furnace coke requirement, sulphuric acid production, CO2 emissions and overall energy requirements. Selected outputs from the process model (for example blowing time, slag production rate and matte converting rate) can then be utilised in the development of a discrete event model (DEM) for the smelter using ARENATM software. Incorporation of reliable and validated mass balance parameters enhances the robustness and reliability of the DEM model. The integration of then-no-chemical, process and DEM modeling tools has a distinct advantage in planning plant trials and examining process design initiatives at Xstrata Nickel's Sudbury Smelter. The present paper discusses the development of these three models and the synergies existing among them. Typical results from all three models are also presented.

Jan 1, 2011

By Gregory Hempen, Thomas Keevin, Russell Wilcox, William Wild

The Department of Defense Strategic Environmental Research & Development Program (SERDP) awarded funding for evaluation of procedures to mitigate peak pressures and energy flux density in the water column from ordnance being detonated on the ocean floor. The research purpose was to conduct scaled testing to resolve whether a theoretically-viable covering technology was operationally effective in reducing blast effects and the impacts of shrapnel. An additional objective was testing effectiveness of this method for hard-bottom units (rock or coral) and (unconsolidated) sediment substrate.

Jan 1, 2011

By Z X. Zhang

In sublevel caving mines, eyebrow break usually gives rise to lower ore recovery and worse safety in the field. Eyebrow break is caused mainly by two tensile stress waves: one from the front surface of a blasting ring, and the other from the roof of the drift. In order to reduce the two waves and finally to reduce eyebrow break at Malmberget mine, we employed two methods: (1) cartridge charge, and (2) double-primers in each blasthole. The two methods were tested in one ore body called ViRi. A total of 10 rings with the cartridge charge and 25 rings with the double-primers were blasted. At the same time a total of 34 ordinary rings were blasted in the same ore body. The result shows that the eyebrow break is 3.0 m for the ordinary rings, 2.3 m for the cartridge charge rings, and 2.1 m for the double-primer rings, respectively. In addition, the ore recovery for the double-primer rings is increased by 3% on the level of ViRi930, compared with that for the ordinary rings.

Jan 1, 2011

By K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in-situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in-situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in one area of the mine that contains Argillite and is relatively homogeneous. This also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for Argillite will be updated as more tests are conducted, and the model will be extended to the other four primary rock types at the Asarco Mission mine.

Jan 1, 2011

By B. S. -J. Kang, M. A. Alvin, J. M. Tannenbaum

"A load-based micro-indentation technique has been developed for damage assessment and non-destructive spallation detection of TBCs at room temperature. This micro-indentation technology has been further extended to the development of a high temperature (HT) test methodology. Elastic modulus calibration tests performed on Hl 3 Tool Steel to 500°C and Haynes 230 at 1000°C displayed excellent agreement with reported values. Moreover, indentation creep tests of Haynes 230 at 1200°C were found to be in agreement with known creep exponents as well. Finally, a HT thermal flux indentation apparatus was assembled for conducting TBC turbine component testing under high temperature moisture-containing environments (= 50% steam with controlled gas content temperatures up to 1250°C). Description and design considerations of this test apparatus are discussed. Preliminary tests of ReneN5/MCrAlY/APS TBC coupons in steam/air environments with in-situ HT micro-indentation testing are conducted. Furthermore, the coupon is removed and examined for damage assessment at periodical intervals.IntroductionLoad and depth relationships acquired throughout the indentation process provide insight to material mechanical properties such as elastic modulus and hardness. Unloading segment analysis of these load displacement curves are utilized in the acquisition of a material's elastic properties. Yet, indentation tests are complex processes involving contact mechanics, material nonlinearity and even fracture mechanics. Thus exact analytical solutions for these processes are difficult to obtain. As a result, much of the current knowledge regarding the indentation process has been acquired through experimental methods and finite element simulations. Initial efforts by Tabor resulted in the application of spherical indentation to obtain post-yielding stress/strain relationships [1]. Soon thereafter, analytical load-depth relations for elastic indentation were developed [2], yet it was Lure who further derived the explicit relationships for both spherical and conical indenters [3]. Improving upon this, these interactions were later extended to indenters with various geometries by various researchers [ 4]. Additionally, by establishing the linearity of the initial unloading slope within the load-depth curve, a relationship between elastic indentation depth, maximum load, unloading slope and indenter geometry was established [5]. From this a theoretical method by which elastic modulus could be determined was established."

Jan 1, 2011

By J. P. McDonald

Exposure to particulates containing metals and metal fumes (PCMMF) is a potential concern in ore refining and smelting. Some metals of primary interest are arsenic, cadmium, copper and lead, which have been linked to various adverse health effects. The current National Institute for Occupational Safety and Health (NIOSH) sampling method for metals in particulates requires the use of a filter, precision airflow pump and laboratory analysis. A major concern with this method is the one-to-two weeks? wait before laboratory results are available for use in determining if additional controls are needed to assure adequate exposure protection for workers. Particulates containing these metals were sampled during sixteen sampling events at a copper smelter using the traditional NIOSH methods. Monitoring of particulates was simultaneously conducted using a TSI 8520 Dust-Trak real-time aerosol monitor with a 10-µm-cutpoint sampling inlet. NIOSH analytical methods related to particulates and metals (methods 0500, 0600 and 7300) were used to determine particulate mass and individual mass contributions of metals on sample filters. Linear regressions with y-intercepts forced to zero were developed to determine the relationship between the PM10 measurements recorded by the DustTrak and laboratory-reported total particulate mass, PM10 and respirable arsenic, cadmium, copper and lead concentrations. These linear regressions yielded correction factors that can be applied to DustTrak readings to obtain total particulate mass, PM10 and respirable concentration estimates for each of the four metals. The R2 (coefficient of determination) values from the linear regressions ranged from 0.65 for total lead to 0.91 for total copper. These results suggest that the DustTrak may produce real-time data useful in providing estimates for airborne concentrations of arsenic, cadmium, copper and lead in copper smelter particulates.

Jan 1, 2011

By Braden Lusk

A typical rural house surrounded by a surface coal mine was instrumented in 2008. Information regarding ground vibration, airblast, and sounds inside the house was collected. Previous publications have included conclusions about this data with regard to blasting source (far-field or near-field) and results as to how the residents experience the blast were made. Several events were also recorded that were not related to blasting due to the nature of the trigger system. The trigger of the monitoring system was attached to one of the mid walls of the house, thus other normal daily events produced vibration levels significant enough to trigger the monitoring system.

Jan 1, 2011

By M. T. Ansari

"This article explains the ways in which investment on mining infrastructure is a geopolitical issue. It discusses the effect of installing sufficient infra structure to get the product to the world market, and argues that there is a risk involved in depending on traditional suppliers who wish to invest in the infrastructure. It explains how to make a distinction between dedicated purpose infrastructure and general use infrastructure by examining the positions of the main actors in mining projects. It argues that these positions can not be understood as analogous to projects in developed countries. To conclude, infrastructure is a crucial link in the supply chain to market but the relative size of such projects in relation to the economy means that investors decisions in developing countries have quite different implications from those in developed countries."

Jan 1, 2011

By Donna Kliche, Charles Kliche

It has been previously documented that various weather conditions such as wind direction and speed, cloud cover and, especially, temperature inversions can significantly affect the overpressure generated by a blast event (Siskind et al, 1980; Oriard, 1999; Siskind, 2000). The overpressure can be magnified downwind and reduced upwind; a change in the regular profile of temperature with elevation can magnify or focus the sound intensity at some distance from the blast event.

Jan 1, 2011

By Ling-yun Yi, Yuan-bo Zhang, Bing Hu, Zhu-Cheng Huang, Zhen-yuan Liao

"Nucleation and growth mechanism of iron crystal grain in coal-based shaft furnace direct reduction process by microwave heating were investigated by optical microscope, scanning electron microscope and EDX. The results indicate that microwave has selectivity on various minerals which absorb microwaves. The high temperature in certain area of pellets and thermal stress on the interface of minerals are formed, results in the wustite grain smashed along the joints, and iron crystal grains turned out a spherical shape obviously. The iron crystal nucleus is formed firstly at the edge of wustite, on the interface between grains and in the holes in pellets, and grows gradually while reduction carries on from surface layer to inner core. Microwave heating promotes the rate of transportation and accumulation of the iron crystal grain, increases growth rate of iron crystal grain and contributes to formation of dense iron-jointed crystal texture eventually.IntroductionMicrowave energy as a new energy, which selectively heating materials through internal energy dissipation, has the advantages of heating uniformity, high thermal efficiency, fast heating, clean and pollution-free compared to conventional heating motheds. Microwave energy also has obvious superiority in increasing productivity. Thus, it has been widely used in many areas, including electronics, food processing, chemical, medicine, environmental protection, and family life etc [1]. As a rapidly developed green metallurgical method, microwave heating also has been widely recognized by areas of grinding, pretreatment, pre-reduction, drying, furnacing, metal extraction, and waste materials processing and utilization. Some research achievements are gradually putting into practice, showing great potential in chemical and metallurgical industry [2-3]."

Jan 1, 2011

By S. Šolar

The countries of Southeast Europe are rich in aggregates, but neither management nor supply are coordinated within or across this area. There are open issues in SEE on the local scale as well as on regional/national and transnational scales that will need to be addressed in order to meet societal expectations related not only to the security of aggregates supply for economy, but also those linked to environmental concerns and social issues. The Sustainable Aggregates Resource Management project (SARMa), an EU Southeast Europe (SEE) activity, has as its objectives the development of common approaches to sustainable aggregate resource management (SARM) and sustainable supply mix (SSM) planning in SEE. In this paper we describe the SARMa project structure and report results for Work Package 3 activities pertaining to best practices for environmental management, the reduction of illegal quarrying, and the promotion of recycling of quarry wastes, construction and demolition wastes and other materials.

Jan 1, 2011

By Walter D. Holland

This is one of a series of instruction guides developed to help instructors present health and safety training courses to workers in the metal and nonmetal mining industry. This course is intended for training those, usually the safety officers, who perform surveys for inhalation contaminants in above ground work areas. The handbook entitled ?Handbook for Surveys of Inhalation Contaminants in Above Ground Metal and Nonmetal Mining and Processing Work Areas? is used as a manual for the course and as a prime reference when performing the actual surveys or interpreting the sampling results. There are six experiments for the students to perform during the course to familiarize them with the sampling devices routinely used during the surveys.

Jan 1, 2011

By Wenya Du, Qingbo Yu, Peng Li, Qin Qin

"A new heat recovery system is proposed. This system uses the endothermic heat of gasification reaction instead of sensible heat to recover the energy of molten blast furnace slag. The gasification technological parameter in molten blast furnace was calculated and the exergy of the system was analyzed. The gasification reactions were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer. The results showed that, according to different gasification agent, this system can produce syngas with different C-H ratio. The exergy efficiency of this system is high and its internal exergy loss rate is about 11%. This method can bring huge economic and environmental benefits which are important to the survival and sustainable development of iron-steel enterprises. The molten BF slag acts as not only thermal media but also good catalyst. The kinetic parameters on gasification reaction with different types of coal used differ from each other.IntroductionEnergy consumption in the iron-making process is about 50%~60% of the total energy input. The blast furnace is very important in the iron & steel process. So energy conservation and emission reduction about blast furnace is very important. In recent years, in order to recovery energy, many new technologies such as TRT (Top gas pressure Recovery Turbine) and CCPP (Combined Cycle Power Plant) were used in iron-making. But the energy of molten blast furnace (BF) slag has only been used limitedly so far.Molten BF (Blast Furnace) slag is the byproduct of iron-making at the high temperatures range from 1723 to 1923K, and has a large amount of sensible heat remaining. The yield of molten BF slag is about 300 kg per ton of pig iron. In conventional processes, molten BF slag is quenched rapidly using a large amount of water to produce a glassy-granulated slag. The quenching slag must be dried before it can be used in cement manufacture. During the process, a large amount of water was consumed and the energy of molten slag can not be recovered. At the same time, it causes environmental pollution problems. So the critical problems of the process are not only energy recovery of molten slag and reducing emission of H2S and SO2, but also guaranteeing the subsequent use value of slag. For this propose, many new technologies were investigated to recover the thermal energy of molten slag. The promising methods are dry granulation [1-4] and reforming of methane [5-9]. The method, utilization of reaction heat instead of latent heat and sensible heat, is quite attractive from viewpoints of energy storage without heat loss, and makes a connection to other industry. But both of them are in laboratory. In this paper, coal gasification in molten BF slag was used to recover the energy of molten BF slag. The gasification technological parameter in molten BF was calculated and the exergy of the system was analyzed. The gasification reactions were studied kinetically by the isothermal thermogravimetry using STA409PC thermal analyzer."

Jan 1, 2011

By Shuji Owada

Scrap electrical and electronic appliances, so called "E-waste", are not a present target to be collected and recycled under Japanese regulations. This material, however, contains considerable amounts of base, precious, and rare metals and it is necessary to recover these elements for maintaining stable supply and establishing "the society of environmentally-sound material-cycle". This paper describes recent trends of rare metals recycling in Japan and technological approaches to achieve the above objective. Also a research work to concentrate rare metals from the printed wiring boards by combining brand new comminution and physical separation methods is discussed.

Jan 1, 2011

By S. Joshi, E. Asselin

An electrochemical quartz crystal microbalance (EQCM) was used to study the leaching of pure gold in deaerated 1 M Na2S solution. Multiple cyclic voltammograms were measured between -0.76 and 1.242 V (SHE) at 20 mV/sec and 2 mV/sec and the frequency shift of the quartz crystal was simultaneously measured. Both the forward and reverse scans showed oxidation occurred between -0.40 to 0.20V. The frequency shift increased during both the forward and reverse scans in the potential range of -0.40 to -0.06 V indicating electrode mass decreased. Since at -0.40 to 0.20 V oxidation peaks were also observed, part of the oxidation was due to oxidation of gold. Eh-pH diagrams were constructed and showed soluble Au(I)-S(IV) species formed between -0.30 and 0.10 V (SHE). Atomic absorption spectroscopy of the test solutions and the mass change recorded by EQCM both showed about 0.015 mg of gold leached. Since the majority of the frequency shift increase corresponding to gold oxidation occurred at -0.40 to -0.06 V during multiple cyclic voltammogram measurement, the total leaching of gold could be approximated to occur at this potential interval to give a leaching rate of ca. 6.4x10-5 mg/s-cm2.

Jan 1, 2011

By P. Koh

A novel approach incorporating computational fluid dynamics (CFD) and flotation modelling has been used for investigating flotation cell designs. CFD modelling has increasingly been employed to enhance understanding of the cell hydrodynamics in mineral and coal flotation. Opportunities for improving the flotation cell performance can be identify by modelling. The CFD-flotation model from CSIRO incorporates cell hydrodynamics that affect particle-bubble interactions. Information from the model includes velocities, turbulent dissipation rates, gas hold-up, particle-bubble attachment and detachment rates. The attachment and detachment rates have been found to be effective measures of cell performance for cell design.

Jan 1, 2011

By I. Fedotov

One of the most effective methods of metal surface heat treatment is through laser hardening. In most cases, laser parameters are determined experimentally, which is expensive and time-consuming. A mathematical model for the surface heat treatment process will allow a significant decrease in costs, and reduce the time required for optimization. In the present work, the authors present a mathematical model for laser heat treatment with forced cooling which can be applied to medium carbon steel. The model is based on a three-dimensional heat transfer equation using Green?s function. The model allows one to calculate the temperature of the treated steel at different depths below the surface with and without cooling, for set values of the laser power and travelling speed, when the heat transfer coefficient is a known constant. It also takes variations in the radiation adsorption coefficient on the metal surface and laser beam spot size into account. The model was illustrated by comparing calculated and experimental temperature profiles of mild carbon steel with 0.5% C with and without cooling. A reasonably good agreement was achieved between experimental and predicted values to ensure that a high enough austenizing temperature with short enough cooling time was reached for direct martensite formation. It also predicted the depth of treatment accurately. The incorporation of cooling in the model substantially improves previous models based on heat transfer only. It delivers a tool that can with a reasonable accuracy predict the depth of surface heat treatment and cooling time required from operational parameters, such as laser power, speed of motion, and distance between laser and cooling source, that can be controlled in the work set-up. This can eliminate trial and error efforts and result insignificant time and cost savings. Keywords Laser, surface treatment, martensite transformation, carbon steel, heat treatment.

Jan 1, 2011

By S. P. Narayan

The hot deformation behavior of Pure Mg and Mg-0.29Ce alloy were studied by isothermal hot compression tests in the temperature range of 250 - 500°C and strain rate range of 10-3 - 102 s-1 in a computer-controlled 50kN servo hydraulic universal testing machine (UTM). The results show that the flow stress of Mg pure and Mg-0.29Ce alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. Process efficiency was increased by nearly 10 to 12% by addition of Ce in Mg. Mg pure exhibits instability zones between 250-275°C at 10 ? 102 s-1 and 400¬500°C at 101 ? 102 s-1 temperatures and strain rates respectively, rest is the safe deformation zone. Wherein, Mg-0.29 Ce exhibits two low efficiency zones from 250 ? 300°C at 10-2? 10° s-1, 400 ? 500°C at 101 ? 102s-1 and high efficiency zone at 450 ? 500°C at 10-3? 10-1s-1. 4D process maps were generated for the above said alloys which illustrate contours of power dissipation and instability in the 3D space of strain rate, temperature and strain.

Jan 1, 2011

By Parissa Mirjafari, Ron Martel, Susan A. Baldwin, Luke Moger

Mine drainage contains metals and sulfate, which may be toxic to aquatic life at certain concentrations and should be removed to acceptable levels before release of any drainage to the environment. One method for treating mine drainage is passive treatment, which is increasing in popularity due to lower construction and operating costs. This method is based on the activity of sulfate reducing bacteria (SRB) respiring on sulfate while using fermentation products from decomposing complex organic materials. The product of this biological process is hydrogen sulfide, which reacts with metals in mine drainage and precipitates them as metal sulfides. However, in practice passive treatment systems are not always effective, reducing the reliability of this approach. In this study, a mixture of hay, cow manure and wood chips was tested in continuous flow experiments for efficacy at sustainable treatment of sulfate and selenium containing water from a mine tailings pond. Factors that contributed to a decline in performance included lowering of the pH due to acids leaching out of the organics, re-oxidation of sulfide back to sulfate and a reduction in dissolved organic compounds over time. In this paper methods are described to overcome these problems so that treatment is made more reliable.

Jan 1, 2011

By H. Kinilakodi

In 2008, the authors developed a methodology for identifying underground coal mines at high risk for major-hazard events. It focused on major hazard-related violations of safety standards associated with high-risk conditions. Later, using a sample of 103 mines with 2008 and 2009 data, injury measures and U.S. Mine Safety and Health Administration (MSHA) citation data were combined into a safe performance index (SPI). The SPI was used to assess the relative safety-related risk of mines, including by mine-size category. In this paper, comparisons are made of SPI-associated, normalized safety performance measures across mine-size categories, with emphasis on small-mine safety performance as compared to large and medium-sized mines. Mining Engineering, 2011, Vol. 63, No. 10, pp. 73-77. Official publication of the Society for Mining, Metallurgy and Exploration, Inc.

Jan 1, 2011