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By H. M. Chikashi

Keywords: Pyrometallurgy, furnace, bath agitation, regression analysis, entrainment This paper presents the results of linear regression analysis of the influence that each component of slag has on the losses of copper in slag-cleaning-furnace slag. Data used for the analysis are actual plant data collected over the past two years of operation. Facts obtained from the study will be helpful for smelter management to control these components in the flash smelting furnace feed and slag, to levels which will enable better control of copper in slag, and smoother operation of the KCM slag-cleaning furnace.

Jan 1, 2011

By Keizo Uematsu, Satoshi Tanaka, Nozomu Uchida, Anze Shui, Joaquin Lira, Cyril Lavelle, Midori Saito, Thierry Poirier

"Dispersed and flocculated alumina (non-spherical particles) slurries were prepared by pH controlling with HCL Spray-drying of these resulted in dimpled granules with a smooth surface and high density, and spherical granules with rough surface and low-density, respectively. Detailed characterization on granules and their compacts includes: SEM observation, density measuring (mercury porosimetry and Archimedes's Principle) and liquid immersion optical microscopy. Compaction of these granules originated a larger particles rearrangement in the samples made with the spherical granules than with the dimpled granules. This was verified through the orientation of alumina particles, which was pronounced in the compact made with the former granules.IntroductionOn immersing a ceramic powder in water, the surface usually acquires a charge by interaction with ionic species in solution. The charge is affected by pH and the electrolyte concentration of the water. 1 The dispersion in a slurry is achieved through the interaction of charges on the particle surface with the media. In the ceramic processing, especially in the process of casting, the dispersion of slurry has been one of the most important topics studied for many years. Recently the attention is paid on its role in the pressing. The granule characteristics are governed by the dispersion state of slurry. Takahashi et al2 , Tsubaki et al3 and Walker et al4 showed that the granules from dispersed slurry were dimpled and of high density, while granules from flocculated slurry were spherical and of low density. This variation in the granules characteristics should have a marked effect on the structure of compact.This paper presents the influence of the dispersion state of alumina slurry on the granules characteristics and also on the internal structure of compacts. Different dispersion states were elaborated by adjusting pH of the slurry. In this method, the particles are dispersed or flocculated only by the effect of surface charging, and thus some secondary effect such as the steric hindrance from an electrolyte dispersant is avoided. The characteristics of granules and compacts are examined with SEM, density measurements by mercury porosimetry and by Archimedes's Principle and liquid immersion optical microscopy. This novel microscopy provides various important information on packing structure of particles, such as their orientation. 5"

Jan 1, 2000

By Chen Tian, Sen Zhang, Qinghai Pang, Junhong Zhang, Wenlong Zhan, Zhijun He

Alkali metal is one of the key critical factors that determine the coke degradation. Previous studies on the influence of alkali metal on coke structure were mostly focus on the catalysis of alkali carbonates for coke gasification reaction. Besides, the difference of alkali metal and coke gasification effects on coke degradation was still not clear. Highly reactive coke developed by Nippon Steel was proved to increase the reaction efficiency and to decrease CO2 emission effectively. Therefore, conventional coke and highly reactive coke adsorbed 5% sodium were studied in this paper. Coke degradation tests were undertaken in atmosphere of N2 and CO2. SEM, EDS and XRD were employed to analyze samples. Results showed that the degradation of conventional coke strength by sodium was stronger than highly reactive coke in the atmosphere of N2. The effect of CaO catalyst on the coke reactivity has been interpreted as a change in highly reactive coke microstructure and strength.

Mar 1, 2017

By O. -J. Siljan

"Refractory materials are an integral part of aluminium production. One special feature of aluminium making is the prominent role of sodium in all parts of the production process. This presence of sodium inflicts stresses on the refractory materials through reactions and may cause severe damages to the refractory linings. The present paper address possible reactions between sodium and refractories in anode bake furnaces, electrolytic pots and casting furnaces. The discussions presented in the paper points to the importance of selecting materials with excellent alkali resistance in all parts of the aluminium making process, although alkali resistance is not the sole parameter to determine refractory life-time. ""Acid"", i.e. silica-rich alumino-silicate refractories are shown to be the best materials for aluminium electrolysis cell potlinings, whereas high- alumina refractories based on minerals like andalusite seems to be the preferred choice for anode bake furnaces as well as cast house furnaces."

Jan 1, 2004

By Christopher Haycocks, Lawrence P. Johnson, George M. Neall, James M. Townsend

INTRODUCTION Conventional roof support methods such as mechanical and resin bolting provide adequate support for a wide variety of coal mine roof conditions. However, roof falls remain the single largest cause of death and injury in underground mines and seriously hamper production in many operations, demonstrating that these methods of roof support are not universally effective. One of the most recent and successful advances in coal mine roof control has been the introduction of the roof truss. Although past work on roof trusses (Gambrel1 and Haynes, 1970; Sheory, et al, 1973) shows little quantification of this support technique, numerous field examples have been cited where the truss effectively supported roof which could not be controlled by either mechanical or resin bolts (Kegel, 1969). The truss combines the advantages of both inclined roof bolts and post-stressing the roof. However, the full benefits of roof trusses will only be realized when design criteria to optimize support capacity are determined. The number of trusses required for a given roof condition can then be minimized, reducing installation time and making them economically more feasible. The purpose of this research is to develop roof truss design criteria based initially on laboratory studies of gravity-loaded multi-layered photoelastic mine models. Laboratory test results will then be modified where necessary following future field testing. The ensuing relationships should provide the field engineer with a reliable means of calculating optimum truss configuration, capacity, and spacing for a set of known roof conditions.

Jan 1, 1977

By O. S. Bogdanov, I. I. Maximov, L. A. Otrozhdennova, M. F. Emelyanov

Results of a study of flotation kinetics of martite particles as a function of bubble size and agitation intensity are presented. Effect of pulp dispersion on flotation separation of galena and secondary copper sulphides--bornite and chalcocite--are also discussed.

Jan 1, 1980

By Laurindo De Salles Leal Filho

Microflotation tests with sodium oleate, in alkaline pH, were performed with apatite and some silicates (phlogopite, quartz, and chlorite) that commonly occur in Brazilian phosphate ores. Further flotation tests were carried out with selected ores containing the same silicates as important gangue minerals. The results showed that apatite recovery is highly affected by competition with silicate minerals, probably activated by calcium ions dissolved in flotation pulp. Inorganic chemical species (sodium tripolyphosphate, sodium carbonate/ bicarbonate, and carbon dioxide) that could act as water softeners were used as modifier agents. They proved to be capable of improving flotation recovery and selectivity.

Jan 1, 1999

By R. R. Tatiya

Data obtained from a copper mine were used in a comparative study of the reserve estimates generated by applying geostatistical methods to surface borehole data, underground core drilling results and assay values from chip sampling. Global estimation of the deposit performed by kriging of the low-density sampling data from the surface boreholes did not provide reliable results, but could identify the potentially mineralised zones. The reserve generated from core drilling results correlated well with that estimated from chip sample data and with that estimated by the conventional methods used at the mine. A satisfactory reserve evaluation could, therefore, be obtained by kriging of the data from the underground core drilling alone, provided that a systematic sampling procedure was adopted. Estimates based on chip sampling information could be used as a check, which could avoid the current practice of chip sampling of most of the mine workings. The aim should be to develop a semi-variogram for the deposit, which could be used to estimate the reserves by kriging

Jun 19, 1905

By P. Ashtari

Influence of Sr and Mn single and combined additions on the modification of the Fe-containing intermetallic compounds and mechanical properties of Fe-rich AA319 aluminum alloys have been investigated, The microstructural features e,g, morphology of the Fe compounds and eutectic Si has been correlated to the mechanical properties, It was demonstrated that modification of the Fe compounds from the platelet ß-Al5FeSi to the Chinese script a-Al8Fe2Si compound improves the UTS and elongation of the alloys by 10.3% and 83.9%, respectively. Moreover, the simultaneous modification of the Fe compounds and eutectic Si increases the UTS and elongation of the alloys by 15,3% and 116,1%, respectively.

Jan 1, 2005

By Sureshan K. Moothedath

This paper provides a mechanistic representation for floc formation, growth and degradation and presents results from an experimental study of batch flocculation in which step changes were made in the impeller speed, flocculant addition, and slurry concentration. A discussion of the experimental results is included in terms of the mechanisms of floc formation and size-change.

Jan 1, 1993

By D. J. McAdam, G. W. Geil, D. H. Woodard, W. D. Jenkins

INTRODUCTION IN a series of papers, the authors and their associates have shown the influence of four important factors on the technical cohesion limit.3-16 By "technical cohesion limit" is meant the technically determinable resistance to fracture. The four important factors are the stress system, plastic deformation, temperature, and the strain rate. The influence of any one of these factors may be represented by a curve of cohesion limits, although only one point on the curve may represent actual fracture. As the term "fracture stress" has come into general use with the same significance as technical cohesion limit, the authors are here using the shorter term with the understanding that it does not always refer to actual fracture. The previously-mentioned series of papers contains ample evidence that plastic extension increases the fracture stress of any polycrystalline metal. In a recent paper of the series,15 moreover, it has been shown that the effect of plastic deformation on the fracture stress cannot be attributed to reorientation of internal flaws but is a work-strengthening effect, similar to the effect on the flow stress.[$] Plastic deformation of steels, however, may not only cause work hardening, but may result in additional hardness because of strain aging. Some evidence that strain aging affects not only the flow stress but also the fracture stress, has been presented in a recent paper.14 In that paper, a study is made of the influence of plastic deformation at room temperature on the fracture stress of ferritic steels at -188°C. The study is based on the results of two-stage tests. In the first stage each specimen was extended a predetermined amount at room temperature; in the second stage the specimen was tested to fracture in liquid air. In most of these tests the specimen remained in the testing machine during the interval of about one hour between the first and second stages, it was kept under a tensile load of about 500 lb and maintained at liquid air temperature. The effects of various amounts of plastic deformation on the fracture stress were thus determined and curves were obtained to represent the influence of plastic deformation at room temperature on the stress at brittle fracture in liquid air.14 Two specimens of ingot iron, however, were removed from the testing machine at the end of the first stage and several days elapsed before the specimens were tested to fracture in liquid air. As shown in Fig 8 of that paper," the points representing fracture of these specimens are far above the curve representing the results of two-stage tests without a rest interval between the stages. The evidence thus indicated that the fracture stresses of these two specimens were increased not only by the work-strengthening, but also by strain aging. The present paper presents results of further investigation of the influence of strain aging on the fracture stress. There are two kinds of aging of steel.

Jan 1, 1948

By Mariana Carla Mendes Rodrigues

The present study deals with the effects of strain rate on the functional behavior of NiTi thin wires. The samples, in the austenitic condition at room temperature, were mechanically cycled 20 times by loading up to 6% strain followed by complete unloading, at 25°C. Four different quasi-static strain rates were assessed: 1x10-4, 1x10-3, 1x10-2 and 5x10-2s-1. The functional properties are described by means of critical stress to induce martensite, stress at maximum strain, energy dissipated per cycle and residual strain. The sensitivity of repeated cyclic deformation to strain rate is also analyzed in terms of phase stability. The results show that the fluctuation in the loading plateau, due to non-homogeneous transformation, increases with increasing strain rate. During cycling, it is observed that higher strain rates result in lower critical stress to induce martensite after the 5th cycle. However, the stress at maximum strain is higher at high strain rates, regardless the number of cycles. The accumulation of residual strain also increases with the strain rate due to the higher applied stress. During unloading, both the elastic deformation of stress-induced martensite and the reverse transformation seem to overlap at high strain rates. The dissipated energy behavior changes between the 1st and 20th cycle. No martensite is stabilized after training, but the intensity of the X-ray diffraction peaks of austenite increases with strain rate, as a result of stress relaxation.

Aug 17, 2017

By Joshua Hofman, Braden Lusk, Erin Morris

Explosions in urban environments, whether of accidental or malicious cause, often result in extensive injuries, loss of life, and property damage. The ability to predict the damage inflicted by these events is highly sought after; in order to predict damage, the behavior of blast waves within these environments must be quantified and understood. Urban constructs such as buildings and roadway intersections affect the natural propagation of a blast wave, intensifying or rarefying the wave depending on their arrangement.

Jan 1, 2012

By D. J. Jr. McAdam

PART I.-OUTLINE OF INVESTIGATION, DESCRIPTION OF METHODS AND MATERIAL Previous Investigation of the Influence of Stress on Corrosion IN 1917 Haigh1 presented evidence that under simultaneous corrosion and cyclic stress metals may fail at lower stresses than if the corrosion is prior to the cyclic stress. In 1926 the author, while investigating the cooling effect of water on the fatigue resistance of metals, found that under these conditions steel specimens fail at stresses far below the endurance limit.2 (By "endurance limit" is here meant the fatigue limit obtained with specimens as free as possible from stress concentration and corrosive influences.) This led to an investigation (at the Naval Engineering Experiment Station, Annapolis, Md.) of the influence of cyclic stress on corrosion. This investigation maybe divided into three parts. The first part was a general survey of the conditions necessary to cause complete failure under corrosion and cyclic stress of relatively high frequency. The entire process by which metals fail under these conditions was-called "corrosion-fatigue." "Corrosion-fatigue limits" for a large number of metals were determined and the relationships of these limits to chemical composition, heat treatment and physical properties were established. The conclusion was reached that corrosion-fatigue is due to the accelerating influence of cyclic stress on corrosion. Results of this part of the investigation were presented in five papers.2-6 The second part of the investigation was a preliminary study of the influence of cyclic stress on corrosion. Each experiment was conducted in two stages. The first was a corrosion stage in which the specimen was corroded under cyclic stress; the second was a fatigue stage, in which the previously corroded specimen was tested (without further corrosion) to determine its fatigue limit. The difference between this fatigue limit and the endurance limit was used as a criterion of the "damage" due to

Jan 1, 1931

By Daniel Su

Following several roof falls in the E3 longwall development of a Consol Pennsylvania Coal Company underground coal mine, an underground roof geology reconnaissance program consisting of twenty-nine 20-foot deep roof holes had identified the presence of thick sandstone layers with abundant shale and micaceous streaks. The base of the sandstone was 4 to 8 feet above the roof line within the fall areas. The presence of micaceous streaks created extremely pronounced planes of weakness in the sandstone. A structural irregularity, which extends into the E4 and E5 developments, exists between crosscuts I 1 and 30,where all roof falls occurred. Immediately to the east of this structural irregularity lies a huge syncline. The presence of thick sandstone units within the typically all shale environment and within such a structural irregularity helps to maximize stress concentration and creates closely spaced joints in the sandstone, which explains why many cracks are present in the macroscopically massive sandstone upon development. The approaching E2 longwall gob to the south and on the down-dip side, on the other hand, provided horizontal stress relief in the sandstone, which helps to explain the many roof falls in the E3 development that occurred during or immediately after the formation of the E2 gob. Finite element modeling confirmed the presence of such horizontal stress relief. Since the E3 longwall was a right-handed face, stress concentration was expected at the longwall headgate T -junctions, and further delamination of the sandstone was expected upon arrival of the E3 longwall face. Based on the results of the roof geology reconnaissance program and a roof stability analysis that took into account up to eleven parameters, supplemental headgate and track roof support consisting of 16-foot and 20-foot long cable bolts was successfully implemented within the zone of thick sandstone with micaceous streaks and structural irregularity and at other potential roof instability areas along the E3 development. The cable bolts were designed to be anchored at least 4 feet above the sandstone unit into the mostly competent sandy shale layers. No headgate roof control problem was reported within the sandstone and structural irregularity zone during E3 and the subsequent E4 longwall extractions.

Jan 1, 2002

By Jirí Faltus

The paper deals with studying the impact of structural properties and anodizing of surface on the corrosion properties of extruded rods from commercial aluminium alloys: AA6082, AA6262, AA6012, AA2007 and new lead-free aluminium alloys AA6023, AA2015 and AA2111B. Samples were exposed to the corrosive atmosphere NSS, AASS in the chamber by EN ISO 9227. Surface of samples were either in the original state or anodizing by selected mode. The depth of corrosion attack and the form of corrosion attack are evaluated depending on the type of alloy, the metallurgical condition and surface treatment of the samples.

Jan 1, 2015

By Gregor Kücher

Lack of basic knowledge on the semi-direct recycling methods for hard metals hinders the application on an industrial scale. However, advantages like reduced expenses and lower environmental impact draw interest at future potentials. Consequently, this report aims to offer insight into the influence of varying bulky hard metal substrates during their lixiviation in acidic media with an oxidant. The statistical software Modde 11 assisted in the development of a design of experiments (DOE) for evaluation of the impact of average grain size, binder and tantalum carbide (TaC) content on the leaching characteristics. The other experimental parameters were constant. Among them were temperature, solution concentration and quantity, duration and substrate surface exposed to liquid volume. Eventually, prediction plots and factors of the computed model equation describe the effects of varying substrate qualities on leached binder metal and selectivity.

By WILLIAM M. CROSS, ALBERT ROMKES, BERNARDO MORENO BAQUEIRO SANSAO, Jon J. Kellar

In this research study, the interaction of particles with substrates of different roughness magnitude was investigated. Particle surface treatment, relative humidity (RH), and surface roughness levels were controlled in order to achieve separation of different particles by applying removal forces. Three different approaches to reproducibly roughen surfaces were used. Initially, glass disks were laser engraved to create a reproducible, controlled roughness substrate. However, the laser engraving method produced surface features that were much greater in scale than the particles. These scale differences were such that the substrates produced were not of value to this research. The second option investigated to induce reproducible substrate roughness was to scratch the glass disk using sandpapers of known grain size. A third approach to establish reproducible roughness was to use fine stainless-steel wire mesh substrates. In tests with sanded glass disks, the interfacial energy of plasma-cleaned (hydrophilic) glass beads had a high variation at 40% RH, showing non-uniformity of area of contact between particles and substrates. As the RH increased, it was expected that the interfacial energy of hydrophilic particles would increase, but this behavior was not observed. In addition, comparing the interfacial energy results of hydrophilic particles with hydrophobic particles, a region with significant interfacial energy difference was not identified. In the case of the stainless-steel mesh substrate, the mesh asperities and particle dimensions were comparable. Thus, the smaller particles had more area of contact with the substrate than the larger particles. For the plasma-cleaned (hydrophilic) beads, the recovery values had an average of 92.5% recovery when the RH was between 46 and 85%. For the hydrophobic beads, the average recovery was 19.0% when the RH was between 46 and 75%. Thus, the hydrophobic characteristic of the particle influenced its lower interaction with the mesh substrate. The difference in recovery can be exploited to achieve separation of particles based upon adhesive forces.

Nov 30, 2021

By WILLIAM M. CROSS, ALBERT ROMKES, BERNARDO MORENO BAQUEIRO SANSAO, Jon J. Kellar

The mineral industry uses significant amounts of water in processing. Thus, sustainable practices with the processing of ores are of critical importance. An impact tester was used to measure the adhesion force between particles and a glass disk [1,2]. A removal force was caused by the impact of the disk/particle containing a puck with a stopper. Johnson-Kendall-Roberts (JKR) theory [3] was used to determine the interfacial energy between the particles and the substrate. Capillary condensation of water can occur between the particle and surfaces in humid environments. The adhesion of particles on rough surfaces has been studied previously [4-10]. The research presented herein combines both variables to separate particle types with minimal water usage.

By Kexin Jiao, Huichang Song, Zhijia Zhang, Jianliang Zhang, Zhengjian Liu

A clear understanding of iron carburization reaction occurring between molten iron and carbonaceous materials is of great importance in blast furnace, and it is one of the hot spots that ironmaking workers pay close attention to. Although carburization rates between iron and coke have been studied, the factors directly controlling it have not been clearly identified. This study focused on the kinetics analysis of iron carburization reaction. Sulfur content was determined as having positive influence on graphite carburizing reaction rate in the range of 0.02% - 0.06%. The values of apparent activation energy calculated by the experiment are consistent with the existing literature, which in turn proved the reliability of the experimental data.

Jan 1, 2015