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By Y. Kusuda

Since 1981, the Annaka refinery has recovered zinc from zinc leach residues by the Waelz Process. The important considerations of this process are the prevention of the growth of coating accretions in the Waelz kiln and the improvement of the zinc volatilization rate. In this paper, simulation predictions and the results of the industrial operation regarding the prevention of coating accretions in the Waelz kiln and the improvement of the zinc volatilization rate at the Annaka refinery are reported and compared.

Jan 1, 2006

By P. E. Cavanagh

Abstract Many investigators have been interested in developing some non-destructive method for detecting or determining the changes in physical properties in steel occurring during endurance tests or normal service life of a part which fails in fatigue. This paper presents a broad discussion of some of this work and the possibilities of developing useful test procedures based on some of the information obtained in the past. Changes in magnetic properties, electrical resistance, damping capacity, X-ray diffraction patterns, and remaining fatigue life at load different from service load have all been investigated as possible means for following the sequence of events during fatigue failure. In some special instances, tests such as these may be used to predict fatigue failure. As an in stance of practical application of the continuous determination of changes in magnetic properties during fatigue, a brief account is given of work done in non-destructive inspection of mine hoist-rope. As a result of extensive experiments and field crisis, it has been found possible to detect the beginnings of failure in a wire rope in service. The test method used will detect plastic deformation in a wire rope, no matter what its cause. There is no possibility of determining the remaining useful life of a rope by calibrating changes in magnetic properties in terms of remaining fatigue life. A change in magnetic properties at a point in a rope may indicate a decrease or increase in fatigue life, depending on the overload history of the rope. A continuing change in magnetic properties ac a point, however, does reliably indicate a developing weak point which will eventually lead to failure. The important point about any change in magnetic properties is not the magnitude of the change, but whether or not it continues.

Jan 1, 1947

By A. W. Jacobs

SHORTLY after Denny, Robson, and Irwin(l) published their first paper, in 1937, on the prevention of silicosis by metallic aluminium, experiments were begun on the practical application of the discovery. It was thought at that time that aluminium powder, to be effective in aluminium therapy, would have to be intimately admixed with siliceous dust at the latter's source. There followed several years of experimental work underground, during which the application of aluminium powder was tested in: (1) Shakers on machine columns, vibrated? by drills (2) Vials placed in drill holes to be blasted (3) Both homogeneous and heterogeneous. mixture with explosives ( 4) Packages with tamping (5) Compressed-air lines (6) Special compressed-air ejectors for use while drilling and after blasting (7) The discharge of ventilation fans (8) The filters of respirators It was concluded from this research that any adequate method of introducing aluminium powder into a mine atmosphere would require too much extra gear, supervision, and aluminium powder, and would interfere unduly with underground routine. Later, animal experiments by Denny, Robson, and Irwin(2) showed that aluminium powder provided effective therapy when inhaled independent of silica dust. Therefore, some means of surface treatment was deemed more practical.

Jan 1, 1944

By Y. M. Shneerson, P. V. Zaytsev, I. V. Fomenko, M. A. Pleshkov

A thermodynamic description of the equilibrium in liquid and gas phases under specific conditions of refractory gold pressure oxidation was generated using the HKF theory. The gold behavior was considered at 190-225°C in the presence of 1-100 mg/L of chloride ion, and under oxidationreduction potential (ORP) of +700 to +1030 mV. The calculations show that the predominant form of gold(I) occurrence is [AuOH]° compared to [AuCl2]?. High ORP favors the formation of [AuCl4]? as a predominant form of gold(III). It is noted that this complex is responsible for the gold losses buildup during POX. Laboratory test results for double refractory concentrate POX are shown. The combined negative effect of (i) organic carbon of the concentrate and (ii) dissolved chlorides in POX slurry on gold recovery is demonstrated. The effects of carbonate blending to the POX feed concentrate and incomplete oxidation of sulfides on POX performance were studied. The pilot tests results of continuous pressure oxidation are also shown and generally confirm the laboratory results and theoretic dependencies. A comparison of the experimental data with the results of thermodynamic calculations is made. As a result of current research, an effective process for POX treatment of carbonaceous sulfide concentrates in the presence of chlorides was developed.

Jan 1, 2014

By J. F. Hazzard, R. J. Chalaturnyk, C. Khazaei

"Various measurement, monitoring and verification (MMV) techniques are used to ensure the safety of operations in petroleum projects. One of these techniques is microseismic (MS) monitoring of the caprock. A challenge in MS monitoring of caprock is that unlike projects such as tunnelling in hard rocks, the number of recorded events are much smaller and also wide spread through the rock mass which makes interpretation of the physical meaning behind the events very difficult.In this paper, a numerical technique is introduced and validated for coupling a finite difference code, FLAC3D (Fast Lagrangian Analysis of Continua), with a discrete element code, PFC3D (Particle Flow Code). Then, a similar approach is adopted for modeling microseismic events in the caprock. For this purpose, the underburden, reservoir and overburden layers are modeled by FLAC3D. A rather small section of caprock above the reservoir is nulled in the FLAC3D model and substituted by a PFC3D inclusion. The reservoir pressures are then applied to the reservoir section of FLAC3D. Once the FLAC3D cycles, there will be induced pressures in the caprock due to its undrained response to the change in pressures within the reservoir. These induced pressures are transferred to PFC3D as boundary velocities. Then the PFC3D cycles and sends back the boundary forces to FLAC3D. This back and forth process continues until equilibrium is reached. During this process, there will be bond breakages within the PFC3D inclusion that can be regarded as MS events. An algorithm for recording the microseismic energies based on a change in local strains is also implemented. The results are then compared with real data. The effect of injection fluid temperature is also studied. No significant appearance of microseismic events was observed due to injection of CO2 in both cases (i.e. with or without considering temperature). However, this continuum/discontinuum approach seems promising for understanding the microseismic response of caprock in more detail and also using the MS data for validation of geomechanical models."

Jan 1, 2015

By M. Rafati

In this investigation, the effects of T4 and T6 heat treatments of AZ91 magnesium cast alloy have been studied. The effects of different microstructural details such as morphology, size and distribution of precipitates and their influence on fracture mechanisms were investigated by optical and scanning electron microscopy. The mechanical strength of the alloy after T6 treatment was found to increase in comparison to the T4 treatment, due to the formation of discontinuous precipitates in the grain boundaries. Precipitation in this alloy occurs in two ways: continuous precipitation, which nucleates and grows inside the grains, and discontinuous precipitation, which forms at the grain boundaries. During ageing, the length of the continuous precipitates increases, and, hence, interprecipitate distance decreases. The formation of discontinuous precipitates causes initiation and propagation of cracks at and the weakening of the grain boundaries. This is the principal reason for the reduction of the ultimate tensile strength in T6 heat treatment in comparison to the T4 condition.

Jan 1, 2006

By C. D. M. Chisholm

Introduction The Sullivan orebody is a sulphide replacement deposit in beds of argillaceous quartzites. The general strike of the vein is north and south, with rather an abrupt change to northwest in the north limits, and a pronounced steepening of the dip in the same area. An east-west section across the orebody in the vicinity where the change in strike occurs will show the dip-to the east-to be about 10° to 20° above the 4500 level, 20° to 30° between the 4500 and 3900 levels, and 35° to 45° between the 3900 and 3500 levels. It is this last section, averaging 75 feet in thickness, that is being mined by the blast hole method discussed in this paper. Typically, the mineralization throughout this section follows the same general pattern between footwall and hanging-wall, there being solid sulphides for a width of 30 to 50 feet, above which lie quartzite beds of varying widths separated by ore bands which also vary in width and in grade. This banded part of the vein usually extends for 30 to 40 feet above the solid sulphides, with commercial ore terminating on reaching a siltstone bed. Development is generally carried to the highest ore band which, when averaged with the underlying quartzite band, will assay about the marginal limit in lead and zinc. When wide stopes are opened, sloughing to the siltstone usually occurs and, although the values are too low to carry the cost of developing and mining, the caved muck can be handled profitably with only haulage and treatment to be considered.

Jan 1, 1946

By Bert S. Hall

"IntroductionThe purpose o f this paper is to review the evidence at hand concerning the earliest centuries of cast iron in Europe, from roughly 1400 A.D. until the second half of the sixteenth century. For the most part it is concerned with the relationship between two technologies which emerged first in China and then later appear in Western lands, gunpowder weapons and iron founding. We should not assume, as I hope to show later in this discussion, that weapons constituted the only product for which the iron founder had any market, but it is clearly true that attempts to produce weapons constituted the most severe technical challenge for the early founder. Firearms appear for the first time in Europe in the 1320s and develop into significant weapons on the field of battle by the end of the century. Theirs is a complex history, subject neither to easy summary treatment nor to simplified models of development. I hope to be able, through the analysis of the evidence concerning cast iron, to show that one important strand in the fabric of gunpowder's history concerns the materials from which cannon could be made. This question is subject to a number of shades of meaning, because ""cannon"" can be made for many purposes under a profusion of different names, and under sharply varying conditions of use. As a result, the question of materials is frequently really a question of competing materials, and involves a complex set of factors, of which production costs and the ultimate safety of the user seem the most important. Judged in this manner cast iron was an important but unsatisfactory metal for weapons purposes until 1543, at which time English founders learned to make iron muzzle-loading cannon which could rival bronze ordinance in most important performance criteria, but which cost much less to produce. With that event, the history of cast iron and the history of weapons entered into the close relationship that persisted until the advent of rifled artillery made of steel in the middle of the nineteenth century."

Jan 1, 1983

By J. C. Kurnia

Presence of fine dust in air causes serious health hazard for mine operators resulting in such serious problems as coal workers? pneumoconiosis and silicosis. Major sources of dust appear of course along the mining face where the minerals are extracted. Proper control and management are required to ensure safe working environment in the mine. Presented here is the use of a computational fluid dynamic (CFD) approach to investigate the flow and dust behaviour in mining tunnels. The objective of this study is to propose and examine various strategies to mitigate dust dispersion from the mining face and reduce dust concentration to a safe level for the operator. In a companion study, the authors investigated various methods for mitigating dust dispersion from the mining face to ensure safe dust concentration levels in the mine tunnel. Among the examined methods, implementation of brattice to direct the flow from the main airway to the mining face is the most effective method to disperse dust particles away from the mining face. The installation of brattice, however, will limit the movement of mine operators and vehicles in the tunnel. Hence, application of a hybrid brattice which is a combination of a physical brattice along with suitable directed and located air curtains is proposed and examined. Based on the CFD simulation results, over a range of parameters of interest, it was found that the physical brattice blocks the ventilation air and directs it to the mine face while an air curtain located along the brattice outlet offers flexibility in keeping the dust away from the operator allowing more freedom for the operator and the equipment. Results of the modelling over a range of parameters of interest are presented and discussed with the goal of managing dust concentrations within safe limits for the operator.

Aug 1, 2013

By C. M. Acuna, M. Sherrington

In high temperature processes thermodynamic equilibrium is assumed and therefore chemical potential of elements, among the condensed phases, have to be the same. In such situation impurities distribute accordingly and their fractional distributions are affected by the masses of the coexisting phases. It has been claimed Teniente Converters perform quite well for smelting high impurity concentrates, especially in respect to volatilization and/or slagging. Production of high matte grade near white metal composition, requiring moderate oxygen enrichment in the process air, results in a huge mass of gas and therefore a high fraction of impurities report to it. Similarly, by recycling different sources of slag, flue dust or other materials, the mass of the final slag is increased and so do the masses of impurities reporting to the slag. Nevertheless, above a certain level the recycling of smelter byproducts is no longer feasible and the cycle has to be halted, unless higher impurity mattes are accepted. Although the process might be continued during converting and refining, lengthy and expensive measures have to be taken if suitable anode copper for electrolytic refining is to be achieved. In the present study samples of high arsenic matte grade and slag were obtained on a pilot scale. The matte samples, on the order 75%Cu, were equilibrated with slag at varying ratios in magnesia crucibles under CO/C02 atmospheres at 1523 K. After 24 hours equilibrium matte and slag were rapidly solidified and analyzed by copper, sulfur, iron and arsenic. Furthermore, industrial samples of matte and slag, in the order 75%Cu at 1523 K, were obtained via a special quenching sampling device to determine the association of copper and suspension of matte and copper in slag. Based on the results, the distribution coefficient of arsenic between slag and matte was evaluated along with copper species in slag and the fractional distribution of arsenic, in the coexisting phases, was determined as a function of the ratio mass of slag to mass of matte.

Jan 1, 2007

By C. Juers

Laboratory chromate coating was applied on AM50 and AZ91D alloys and compared to phosphate-permanganate one. Evaluation of the corrosion behaviour was performed using electrochemical DC and AC methods in ASTM water D1384-87. This electrolyte was chosen because it was moderately aggressive and found to give generally good correlations with long period exposure results in atmospheric conditions. Electrochemical impedance spectroscopy was used to determine more accurately the corrosion rates from the analyses of the high frequency capacitive loop. Anodic polarization was applied in order to evaluate the pitting resistance of the different coatings. These results were correlated with weight loss data evaluated from experiments performed by immersion tests in ASTM water D1384-87 and climatic cyclic chamber tests.

Jan 1, 2006

By Y. A. Topkaya

In this research work, a process was described for the recovery of copper and zinc in copper converter flue dust from the Black Sea Copper Works' Samsun Smelter Plant. After characterization of a representative flue dust sample, the process included roasting of the flue dust and then leaching in dilute sulfuric acid solution. Roasting time and temperature were studied to determine the optimum roasting conditions. Sulphuric acid concentration, duration, temperature of leaching and solid to liquid ratio were the parameters studied in the bench scale laboratory leaching experiments.

Jan 1, 2007

By Zhang. L.

Ordered intermetallic PtSb had been synthesized by arc-melted and then sintering treatment. The electro-oxidation of formic acid on PtSb was investigated at room temperature by cyclic voltammetry and chronoamperometry. The results are compared to those at a polycrystalline platinum electrode surface. It was found that PtSb intermetallic was catalytically more active than pure platinum according to the onset potential and current density. XRD and XPS technologies had been used to investigate the crystal structure and electron effect. We think formic acid decomposition on PtSb favors the reactive intermediate route and is not very much affected by the CO intermediate as compared to Pt.

Jan 1, 2005

By P. Fellner, A. Sýkorová, J. Thonstad, J. Jurišová, V. Khandl

Adsorption of S02 on alumina used in the aluminium industry, so-called smelter grade alumina, was studied in the temperature range 15 C-120 C. The specific surface area of the smelter grade alumina was 88 m2/g. It was found that at temperatures lower than 40 C, sulphur dioxide is bonded to alumina reversibly by physical forces, and the adsorption can be described satisfactorily by the Langmuir adsorption isotherm. The heat of adsorption was estimated to be -33 kJ.mor1. At temperatures in the range 80 C- 120 C, which prevail in dry scrubbers in the aluminium industry, the heat of adsorption was determined to be -56 kJ.mor1. When S02 was adsorbed at temperatures higher than 80 C, about 30 % of the S02 could not be desorbed when heating the samples up to 250 C. In the presence of S02 and oxygen, the formation of sulphate was determined at temperatures above 90 C.

Jan 1, 2006

By G. E. Bogin, C. Strebinger, J. F. Brune

"Evidence shows that methane gas emanates from the mined-out area or gob of a longwall coal mine and can travel towards the working face, posing an explosion risk. Since the gob consists of varying levels of compacted rock, many researchers have modeled fluid flow through the gob as a Darcy-type porous media with a specified porosity and permeability. When studying methane gas explosions near the gob fringe, the Darcy flow assumption may not be applicable to describe the methane flame interaction with the gob. Computational fluid dynamic studies were performed modeling methane flame propagation across a simulated gob which was modeled as both a Darcy porous medium and as discrete rock objects with varying sphericity. Modeling the gob as a Darcy porous medium results in unrealistic methane flame propagation since the porous media assumption does not consider any differences in rock size and/or distribution. Additionally, the porous media model does not allow for ignition within and subsequent flame propagation through the porous medium, which must be modeled to understand the potential for methane gas explosions in the gob area. Modeling the gob as discrete rock objects produces more realistic methane flame dynamics and agrees with experimental observations. Modeling results show flame propagation across circles, hexagons, and squares, meant to represent rock rubble in the gob, produce different levels of turbulence which affects methane flame propagation velocity. This research demonstrates that modeling methane gas explosions in a longwall coal mine environment, specifically near the gob area, requires modeling obstacles, such as rock rubble, as discrete physical objects to capture the complex coupling of fluid dynamics, thermodynamics, and heat transfer. INTRODUCTION Although there are methods to mitigating methane accumulations in a longwall coal mine, explosive gas zones (EGZs) of methane and air may exist and pose an explosion risk to nearby miners and equipment (Brune, 2014) (Karacan, Ruiz, Cote, & Phipps, 2011). In the event of an explosion, the resulting methane flame and pressure wave can be catastrophic as evidenced by the Upper Big Branch explosion in 2010 that killed 29 miners (Page, et al., 2011). Since the mining process is transient, it is difficult to determine exactly where these EGZs exist, but investigative reports show in many cases, these EGZs can be near the working face, behind the shields, or within the gob area (Brune, 2014) (McKinney, et al., 2001). Additionally, miners have recounted seeing flames moving back and forth within the gob and under the roof supports (McKinney, et al., 2001) and in other cases, anecdotal evidence of hearing small pressure pops deep within the gob area (Brune, 2014)."

Jan 1, 2019

By S. Vaidya, R. C. McKellar, N. K. Sinha

Nominally [001]-oriented nickel-base single crystal (SX) superalloy CMSX-10 was investigated at 900°C under constant load, equivalent to an initial stress of 700 MPa, for creep strains from 7% to fracture strain (18.2%). The cross-sectional dimensions of initially uniform cylindrical specimens were measured along their entire length after the tests. The cross-section changed from circular to near elliptical shape. The anisotropic deformation, measured in terms of eccentricity, increased with the increasing strain level, but for a given strain level, it remained constant along the entire length of the initially uniform gauge section. The results are discussed in terms of diameter, eccentricity, area, local stress and microstructural observations. The most striking observation was the fact that all the specimens displayed a yoke-like shape, or the reduction of cross sectional area, at two locations within the originally uniform gauge section. Such observations have not been reported in the literature for single crystal superalloys.

Jan 1, 2006

By G. Ergin

The interactions taking place between Al-Mg alloys and the bed media during aluminum filtration are not yet well understood. These interactions were studied using the infiltration technique. The reaction interface was analyzed using different techniques such as SEM and TEM. Only spinel formation was observed at the interface regardless of the type of alumina and contact time. This paper discusses the results of the study.

Jan 1, 2004

By J. M. R. Carvalho, M. T. A. Reis, M. R. C. Ismael, M. J. N. Correia, S. M. C. Santos, J. M. Carvajal

A sulphide zinc concentrate (Zn-40%) has been leached in sulphuric and chloride media to optimize the conditions for the recovery of zinc and copper. Previous results showed that extractions of 95% zinc and 20% copper can be achieved in just one stage, after two hours of leaching at 80°C with a solution 0.5M in Fe2(SO4)3 and H2SO4 and a solid/liquid ratio of 5%. This work presents the results obtained in the leaching experiments carried out in sulphuric and chloride media using two and three crosscurrent stages and a countercurrent process simulation for a solid/liquid ratio of 10%.

Jan 1, 2008

By S McQuitty

The metallurgical treatment of Falconbridge ore re-quires an extremely fine grind of the pyrrhotite portion ? for maximum liberation and recovery of nickel. This paper describes the operation of a grate discharge pebble mill in closed circuit with cyclones regrinding 25 to 30 tons per hour of sulphides to approximately 90 per cent minus 325 mesh. The consumption of the screened ore grinding medium is of the order of 2.5 pounds per kw.-hour, or less than 1 per cent of the tonnage of re-ground sulphides. IN RECENT years, there has been a considerable interest in pebble grinding in the uranium industry, and a number of installations have appeared. However, the use of sulphide ore pebbles as a grinding medium has so far been relatively limited. There has also been some question as to their suitability for the very fine grinding of sulphide concentrates. This paper describes the preliminary results of a commercial operation involving the

Jan 1, 1964

By James Tuer, John R. Goode, Jim Cambon

"Hudson Resources Inc. (Hudson) has defined a major resource of high purity anorthosite (calcium feldspar) assaying about 30% Al2O3 at the White Mountain (Naajat) deposit in Western Greenland. Extensive beneficiation and evaluation testwork has shown that the material can be simply beneficiated to produce a feed material ideal for the production of low-alkali E-glass used for making glass fibre. An offtake agreement is in place with a major US fibreglass manufacturer and, subject to the mine construction schedule, shipments are scheduled for late 2016 or early 2017. In parallel with the E-glass program, Hudson has completed an initial program of metallurgical testwork which shows that the White Mountain anorthosite can be processed by hydro- and pyro-metallurgical processes to yield either smelter-grade alumina (SGA), suitable for conversion to aluminium metal, or a high purity, chemical/specialty-grade alpha-alumina (CGA) commanding a premium price. The process includes dissolution of the anorthosite in hydrochloric acid, HCl sparging to precipitate aluminium chloride hexahydrate (ACH), recycle of the ACH filtrate to leaching with a bleed stream processed for HCl regeneration from CaCl2, and two-stage calcination of the ACH to regenerate HCl and produce SGA and/or CGA. Calcium silicate and amorphous silica are marketable by-products. This paper discusses the White Mountain anorthosite deposit; the process testwork completed to develop production processes for SGA and CGA; production plans, and indicative economics.INTRODUCTIONHudson Resources Inc. (Hudson) holds a 100% interest in the Naajat Exploitation Licence in Western Greenland that cover the White Mountain high-calcic anorthosite deposit. Anorthosite is a calcium aluminosilicate of slightly variable composition but generally containing about 30% Al2O3. The alumina content is similar to that in bauxite and anorthosite has long been studied as a feedstock for the production of alumina. Other potential uses include feedstock for the high-end fiberglass (E-glass) industry and as a filler for use in paint and plastics."

Jan 1, 2016