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By T. Harrison

Surface coal mines in West Virginia are receiving stringent NPDES discharge limits for total recoverable selenium. With limits in the low parts-per-billion range, selection and implementation of proper sample collection and analytical methods are imperative for quality assurance and control and for consistency in results. Given the typical oxidized form of selenium in the water, the low limits and the large and variable flow rates from the watersheds, end-of-pipe treatment is difficult and cost-prohibitive to implement. Discharge locations in the remote and steep terrain exacerbate the problem. To evaluate options for end-of-pipe treatment at a Patriot Coal Corporation surface mining operation in West Virginia, CH2M HILL performed wastewater characterization for a range of key constituents and selenium species at three outfalls for selection and preliminary sizing of appropriate treatment processes. A preliminary evaluation of base and wet-weather flows was done to understand flow variability considerations for discharges. A conceptual evaluation of technologies to treat selenium to permitted levels was conducted in con-junction with order-of-magnitude life-cycle cost estimates.

Jan 1, 2010

By A. A. Sadegh

A laboratory investigation was carried out on the characterization and beneficiation of sillimanite ore. Petrographic analysis indicated that the ore consisted of massive elongated sillimanite grains in a matrix of hematite, garnet, feldspar and silica. A procedure for estimating the percentage of sillimanite was developed using float-sink and magnetic-separation techniques. A liberation study was carried out to determine the level of size reduction required to achieve sufficient liberation while ensuring that gravity concentration techniques would be applicable. Laboratory testing was performed on the liberated ore to investigate the applicability of using wide-angle dense-medium cycloning to upgrade this ore. Initially, medium-only tests were carried out using various size distributions of magnetite and ferrosilicon as the dense-medium solids to evaluate the effects of operating conditions on medium segregation. Depending on the medium solids and operating conditions, either positive of negative differentials (difference between the relative densities of the underflow and overflow streams) were obtained. Based on these results, separation tests were performed to process nominal -1.2-mm sillimanite ore. The results indicated that sillimanite concentration could be obtained using a medium relative density that was much lower than would typically be used in a dense-medium cyclone separation.

Jan 1, 2007

By C. Samuelsson, H. Ahmed, B Björkman, A. Andersson

The cost of raw material and energy is a continuing driving force towards working with increasing the recycling of ore based steelmaking residues. In Sweden no on-site sinter plants are operated at the integrated steelworks. Instead, selected residues from the plant are incorporated in a cold bonded briquette product which is recycled to the process via the blast furnace (BF). Since the BF sludge is the major bleed of zinc out of the furnace it is required to be de-zinced prior to recycling in the briquette product. In the present work landfilled BF sludge has been characterized with respect to chemical composition, particle size distribution, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The sludge was also subjected to laboratory scale hydrocyclone trials aiming at reducing the zinc content making the sludge viable for recycling. The results suggested that the sludge had been agglomerated prior to the characterization and hydrocyclone treatment. The zinc removal using the hydrocyclone was discussed.

Jan 1, 2015

By Donald R. Fosnacht

An investigation was initiated to obtain the scope of the problems associated with recycling various waste oxide materials generated at Inland Steel and to identify and? test techniques that could possibly aid in increasing the amount of waste oxide materials recycled to primary. operations. Based on the results of this work, several new techniques were developed ?and tested on ?a plant or laboratory scale. These include the use of cold-bond agglomeration methods for producing waste oxide agglomerates for use as a cooling agent or scrap substitute in steelmaking operations, and the use of various techniques for beneficiating blast furnace flue dust and soaking pit rubble so that the upgraded materials can be utilized in sinter plant or ironmaking operations. The physical and chemical characteristics of the waste oxide materials and the results of the laboratory and plant testing are discussed in this paper.

Jan 1, 1985

By D. Brion, J. J. Prédali, J. Hayer

The need to grind volcanic-sedimentary ores very finely (d80 < 20 µm) so as to liberate Pb, Zn, and Cu sulfides from their pyritic gangue causes difficulties in selective flotation. The pyrite, which accounts for 70-80% of the mineral content, is insufficiently depressed by the usual pH and NaCN techniques. To determine better depressing methods, the surface evolution of pyrite during flotation was followed by ESCA spectroscopy to compare the stability range in the Eh-pH diagram. Surface iron hydroxide was formed, which is the main pyrite-depressing factor. NaCN appears to play a more restrictive part, since no ferricyanides were detected, except for very small amounts at pH 7.

Jan 1, 1980

By J. B. Vander Sande, L. C. Rainey, P. Bolsaitis, B. Dirsa

"The structure and composition of silica-rich particles recovered by lavage from the lungs of three active miners with different medical histories were studied using high-resolution electron microscopy and chemical microanalysis. The results arc compared to the similarly determined structure and composition of respirable-size mineral particles obtained from roof-bolter dust-box samples from two coal mines of widely different bulk quartz concentrations. The results show that the lungs of the miners contain silica-based particles with structures not found in the mine samples. Also, the particle structures and compositions found in the macrophages were different in each of the miners. The rau.lu suggest the possibility that intracellular processes may affect the susceptibility of individuals to silica-induced pneumoconiosis. The cytotoxic and fibrogenic potentials of mine dusts result from the activity of their individual components. Whether this effect is additive or even mass (i.e., dose) related is questionable and has been the subject of many investigations. Particle size and size distribution of various constituent minerals, the surface structure and properties of individual particles, and the self-cleaning capability of the lung (i.e., the capacity of the macrophage system) may, among other variables, affect the pathogenic changes induced by dusts lodged inside lungs. Extensive epidemiological investigations conducted on miners from different coalmining districts, where equivalent dust exposures have been shown to result in vastly different frequencies of lung disease incidence, also confirm this hypothesis (1) In a recent study, Ferrer et al. (2) used energy-dispersive X-ray analysis (EDXA) to investigate the inorganic element content in pleura and lung in reference, silica exposed non-pneumoconiosis, and silicotic populations. Constant depositions of silicon and calcium were detected in visceral pleura, parietal pleura, and lung of the refence group and in visceral pleura and lung of the exposed non-pneumoconiosis and silicotic groups. Comparison of the silicon content in pleura between silicotic and exposed non-pneumoconiosis subjects showed a nonsignificant probability of difference, whereas there were no differences with respect to the silicon content in lungs."

Dec 1, 1995

By R. O. Suzuki, S. Natsui, R. Nashimoto, T. Kumagai, T. Kikuchi, H. Takai

A newly developed computational fluid dynamics model based on a multi-phase particle simulation is presented for predicting the entrainment behavior of liquid metal into slag due to rising single bubble. By comparing results calculated using this model against experimental data, it was found that the transient behavior of bubbles and the two immiscible liquids can be accurately estimated by this method. The rupturing of the thin water film surrounding the bubble was less reliably predicted, but this 3-dimensional unsteady numerical model still nevertheless provides valuable new information for directly predicting the change in the liquid-liquid interface over time. This model predicted the Young-Laplace pressure, and the interface shape was simulated with volume conservation using this model as opposed to the conventional particle method. This simulation model can calculate both of dispersed phase and continuous phase seamlessly.

Jan 1, 2015

By K. Gonçalves

One of Vale?s sponsored research project is aimed at the implementation of a practical scale-up procedure for flotation. In this context, detailed flotation kinetics characterization is of critical importance. This work presents the results of a campaign aimed at characterizing flotation kinetic parameters with respect to particle composition. MLA analysis was carried out for 40 narrow-sized iron ore particles with known flotation time from a controlled flotation kinetic test. The iron ore sample studied (59% hematite and 41% quartz) comes from a mine in the southeast of Brazil and the type of reagents applied are the same as used in the plant. For the reagent conditions tested, the overall rougher concentrate (sink) yielded 79.1%, pure quartz and hematite recoveries to the froth were 56.0% and 4.8%, respectively. The results from the kinetic tests show that the flotation rate of the particles doesn?t vary much (~0.03s-1) with composition and that the fraction of floatable particles in each grade controls the separation action. The results show that the rate of flotation is controlled by transport and that the selectivity is controlled by the fraction of floatable particle of each phase.

Sep 1, 2012

By C. H. L. Bastos

A physical and chemical characterization study was carried out on 483 kaolin samples from 2.9 km2area at the Para Pigmentos mine along the Capim river, northern Brazil. The samples obtained from cores, drilled with regular spacing of 100 m, were evaluated using grit percentage, particle size distribution (psd), brightness, leachability, magnetic response and viscosity. These parameters were correlated with each process step in the plant and also the physical and chemical properties of the ore and finished product. Cluster analysis was performed and four main groups of kaolin were identified. These were then related to their performance at the various process steps and the quality of the initial product. These groups are well defined by plotting grit X “psd” and TiO2x “psd” in scatter plots.

Jan 1, 2004

By Sergio Neves Monteiro

In the present work, a ceramic foam elaborated with illitic clays was characterized. Properties related to density and compression strength were determined in samples fired at 1300oC, a temperature that permits the clay structure to generate and retain gases that will produce the foamy structure. The microstructure of the ceramic foam was studied by X-ray diffraction, scanning electron microscopy and mercury porosimetry. The results showed that the ceramic foam presents a bulk density of 0.38 g/cm3. The microstructure is formed by large open pores, quartz particles and vitreous phase.

Jan 1, 2006

By Robert D. Schmidt

The US Bureau of Mines is cooperating with Cyprus Mineral Park Mining Co., Columbia University, and the US Geological Survey in investigating the feasibility of applying in situ leach mining methods to fracture-hosted, supergene copper sulfide (chalcocite) ores. This paper presents the initial findings of mineralogical, hydrogeological, and geochemical characterization studies conducted at the Mineral Park mine, located in the Wallapai mining district of northern Arizona. A design for in situ leaching is proposed that would minimize the need for blasting prior to leaching, and would enable economical development of deep reserves at the Mineral Park mine. The in situ leaching design would also reduce the potential for long term acid rock drainage.

Jan 1, 1995

By Adriana de Aquino Soeiro da Silva, Joao Alves Sampaioa, Luiz Carlos Bertolino, Francisco Manoel Garrido, Marta Eloisa Medeiros

"Brazil has a large agricultural potential and its production success is related to the chemicaland physical soil characteristics. Therefore, the demand in the use of a great quantity offertilizers to compensate the low amount of nutrients in the soil includes about 40% of foodproduction costs. In order to develop economical alternatives to traditional fertilizers, rockswith potential use in agriculture will be studied. In this work the potassium rock, a greensandslate, will be chemically and structurally characterized for the development of a potassiumthermophosphate. This alternative fertilizer will be obtained based on a fusion of a ponderedmixture of potassium, magnesium and phosphate rocks to be applied in the Brazilianagriculture. Preliminary characterization results indicate that the greensand slate presents ahigh percentage of glauconite, quartz and micas.Keywords: Potassium thermophosphate, alternative fertilizers, greensand slate.IntroductionBrazil has a great agricultural potential and its production success is closely related to thesoil's chemical and physical characteristics. However, the country's soils present lownutrients content and high acidity due to weather conditions. Thus, the use of a high amountof fertilizers makes up for the soils' lack of nutrients and accounts for 40% of food productioncosts. Therefore, research on obtaining new alternative fertilizers is a constant worry due tothe increase on food demand [ 1].The lack of raw material for the preparation of NPK fertilizers in Brazil is a concern and theissue of potassium fertilizers a priority. Such a fact is because in 2008 only 608.000 tons ofKCl were produced, corresponding to just 10% of the Brazilian necessity. Thus, the use ofrocks as agricultural nutrients can contribute to reduce the need for industrial fertilizers.This way, the development of a new agricultural raw material originated from a rock thatalready exists in the country's soil is of great importance for the mineral and agriculturalsectors."

Jan 1, 2011

By L. Yuan, R. A. Thomas

"Atmospheric monitoring systems (AMS) have been widely used in underground coal mines in the U.S. for the detection of fire in the belt entry and monitoring of other ventilation-related parameters such as airflow velocity and methane concentration in specific mine locations. In addition to an AMS being able to detect a mine fire, the AMS data has the potential to provide fire characteristic information such as fire growth (heat release rate) and exact fire location. This information is critical in making decisions regarding fire-fighting strategies, underground personnel evacuation, and optimal escape routes. In this study, a methodology was developed to calculate the fire heat release rate using AMS sensor data for carbon monoxide (CO), carbon dioxide (CO2), and airflow velocity based on the theory of heat and species transfer in ventilation airflow. Full-scale mine fire experiments were then conducted in the Pittsburgh Mining Research Division (PMRD) Safety Research Coal Mine using an AMS with different fire sources. Sensor data collected from the experiments were used to calculate the heat release rates of the fires using this methodology. The calculated heat release rate was compared with the value determined from the mass loss rate of the combustible material using a digital load cell. The experimental results show that the heat release rate of a mine fire can be calculated using AMS sensor data with reasonable accuracy. INTRODUCTION Fires at different stages generate different gases and smoke toxicity hazards. When fires occur in underground mines, a significant amount of toxic gases and smoke enter the mine ventilation system and are carried throughout the mine ventilation network, increasing the hazard potential for personnel even if far away from the actual fire. Although fires that develop to the point of rapid flame spread pose imminent hazards, fires in their smoldering, pre-flaming stages can also contaminate the mine atmosphere with debilitating levels of smoke and toxic gases. The most important parameter for evaluating the fire hazard in mines is the heat release rate (HRR), which is directly related to the rate at which heat, smoke, and toxic gases are produced and transported by the ventilation system, and provides an indication of the time available for escape or firefighting [1]. The HRR is also an important input parameter to mine fire simulation models. Measuring the HRR of an actual fire can be a difficult task. Early experimental measurement of HRR focused on the heat output as represented by the temperature of the product gases. In ASTM E1321 (LIFT test), an array of thermocouples was positioned in a duct which captured all gaseous combustion products to measure their average temperature. This approach assumed the flow is adiabatic, which is never a reality. Significant progress on measuring HRR was made when Huggett showed that, for most common materials containing C, H, O, and N, the average heat release per unit mass of oxygen is 13.1 MJ/kg O2 [2]. Thus, the oxygen deficit is a measure of the HRR in the flow that the duct captures. This approach is termed oxygen consumption calorimetry (or the oxygen consumption method), and is widely used in the fire protection community."

Jan 1, 2017

By L. Yuan, R. A. Thomas

"Atmospheric monitoring systems (AMS) have been widely used in underground coal mines in the United States for the detection of fire in the belt entry and the monitoring of other ventilation-related parameters such as airflow velocity and methane concentration in specific mine locations. In addition to an AMS being able to detect a mine fire, the AMS data have the potential to provide fire characteristic information such as fire growth — in terms of heat release rate — and exact fire location. Such information is critical in making decisions regarding firefighting strategies, underground personnel evacuation and optimal escape routes. In this study, a methodology was developed to calculate the fire heat release rate using AMS sensor data for carbon monoxide concentration, carbon dioxide concentration and airflow velocity based on the theory of heat and species transfer in ventilation airflow. Full-scale mine fire experiments were then conducted in the Pittsburgh Mining Research Division’s Safety Research Coal Mine using an AMS with different fire sources. Sensor data collected from the experiments were used to calculate the heat release rates of the fires using this methodology. The calculated heat release rate was compared with the value determined from the mass loss rate of the combustible material using a digital load cell. The experimental results show that the heat release rate of a mine fire can be calculated using AMS sensor data with reasonable accuracy.IntroductionFires at different stages generate different gases and smoke toxicity hazards. When fires occur in underground mines, a significant amount of toxic gases and smoke enter the mine ventilation system and are carried throughout the mine ventilation network, increasing the hazard potential for personnel even if far away from the actual fire. Although fires that develop to the point of rapid flame spread pose imminent hazards, fires in their smoldering, pre-flaming stages can also contaminate the mine atmosphere with debilitating levels of smoke and toxic gases.The most important parameter for evaluating the fire hazard in mines is the heat release rate (HRR), which is directly related to the rate at which heat, smoke and toxic gases are produced and transported by the ventilation system and which provides an indication of the time available for escape or firefighting (Babrauskas and Peacock, 1992). The HRR is also an important input parameter to mine fire simulation models."

Jan 6, 2017

By Lucas Lopes da Costa

In this work, a natural foam extracted from the Amazon buriti palm tree is investigated as possible substitute for synthetic foams. The basic physical and mechanical properties of this biofoam were evaluated. Its sponge-like structure was characterized by the amount of pores and morphological aspects. It was found that the buriti biofoam displays a very low density of the order of 0.1 g/cm3 with a relatively good compressive strength. This would be suitable for several engineering applications and as a new material with the potential for replacing currently applied synthetic polymeric foams.

Jan 1, 2010

By Mario González Ramírez

The safe transport of sour gas requires steels with enhanced hydrogen induced cracking (HIC) resistance. Centerline segregation bands of high hardness microconstituents and non-metallic inclusions are the heterogeneities usually linked to HIC failures in pipeline steels. Full-scale production heats of a new low Mn, Nb microalloyed steel were produced by different steel mills aiming at the application in sour gas environments. The new alloy design provides both effective strengthening and control of sulphide inclusions. Coil microstructure consisted of fine grained ferrite with a small volume fraction of uniformly dispersed eutectoid aggregates. Most importantly the microstructure was uniform in both the longitudinal and transverse directions and exhibited exceptional consistency. Samples from this steel were submitted to HIC testing according to NACE standards TM0284-2003 without any sign of cracking. The results, so far, confirm that this new alloy design provides the unique opportunity to economically produce a high strength pipe steel grade with improved sour service resistance for the linepipe industry.

Aug 8, 2018

By M. Fafard, R. Ahmed, O. Dion-Martin

"The optimization of aluminum sheet and tube forming needs the use of large strain finite elements software. The precision of the predicted results from those simulations depends mainly on the quality of constitutive law of the material used. In order to improve quality of these simulations, Barlat has suggested a new yield function named YLD2000-2d. This criterion describes the anisotropic behavior of the rolled aluminum plates. This work consists of characterizing the AA5754 alloy and estimating the material parameters needed for the YLD2000-2d criterion in LS-DYNA. In order to get these parameters, various mechanical testing were performed such as bulge and tensile tests. Moreover, the bulge test was also used to obtain an estimation of work hardening curve in large strain condition, up to 50%. The objective of this paper is to share the experimental results of the characterization of AA5754 aluminum alloy.IntroductionResearchers from National Research Council Canada's Aluminium Technology Center (NRCATC) and Aluminium Research Centre - REGAL, are working on aluminium tube hydroforming processes of AA-5754-0 alloy, used in automotive industries. Hydroforming process presents several difficulties such as wall thinning and section changes. In order to control them, some parameters can be set during the process like pressure rate and end feed level [1]. Given the complexity of the parts and the variability of the control parameters, the use of finite element method (FEA), like LS-DYNA, based on large strain theory is thus necessary. The accuracy of predicted results depends mainly on the quality of the constitutive law used to model the behavior of material. FEA results seem to be valid with the von Mises yield criterion used in some cases. But, given the anisotropic properties of the AA-5754 alloy, a more appropriate criterion could be used. The *MAT_ BARLAT YLD2000 shell material criterion, developed by Barlat [2], who's taking into account the anisotropic behaviour, was chosen due to its large flexibility and its good adaptation to particular elastoplastic behavior of aluminum. However, the use of this criterion needs to determine some material parameters by experimental way."

Jan 1, 2013

By H. Tutu

The legacy of gold mining operations continues to affect water quality in the Witwatersrand Basin in South Africa. The acid mine drainage (AMD) emanating from the tailings dumps liberates heavy metals from the ore minerals. The objective of this study was to characterise the geochemical processes that are important in understanding chemical evolution of polluted water in the study area. Analytical results for water samples collected in the catchment of the study area generally showed elevated concentrations of heavy metals in the vicinity of tailings dumps and mining operations and a decrease in the distal. Dams and wetlands, despite their proximity to the tailings dumps, recorded low concentrations of heavy metals and other pollutants. The characterisation of AMD was summarised in a conceptual model in which plots of redox potential versus pH and electrical conductivity versus pH were identified as the most important sub-models that captured the gross physical-chemical characteristics of polluted water and its interaction with the environment.

Jan 1, 2006

By Serge Payant, Michael G. Li, Lionel J. J. Catalan

Alkaline solution rinsing for decommissioning of an acid-leached residue was evaluated by column experiments, neutralization tests and solid characterization by XRD and SEM. It was found that consumption of a strong alkali during residue neutralization was much greater than that required to neutralize the soluble acidity. The excess alkalinity was consumed by solid-phase conversions unnecessary for the success of decommissioning. Alkaline rinsing did not reduce the time requirement for decommissioning when compared with plain water rinsing. Since no benefit is gained to compensate for the additional costs associated with excess alkali consumption, we conclude that strong alkaline solution rinsing is in fact inferior to simple water rinsing.

Jan 1, 1998

By Alfredo Romero Quispe, Carlos Hoffman Sampaio

This work presents a study of characterization of activated carbons for the adsorption of Au(CN)2- complex. A comparative study of six samples of activated carbons, three Brazilian and three produced out of Brazil was made in order to determine their qualification for a performance in adsorption circuits in the extractive metallurgy of gold. The adsorptive capacity and the kinetics of adsorption were compared to the physical and chemical properties of each one. The influence of poluant ions on the kinetics and loading capacity of aurocianyde anion was also determined.

Jan 1, 1995