Cupric chloride leaching is an attractive alternative for the treatment of pyritic refractory gold ores. In this context, the kinetics of pyrite dissolution was studied in cupric chloride solutions containing 4 M NaCl. Pyrite leaching experiments were conducted in a stirred tank reactor for 250 h. The effect of temperature was evaluated at 45°C, 60°C and 75°C, while the effect of [Cu (II)] was evaluated

The effects of leaching parameters on the metal dissolutions from Caldag laterite ore using hydrochloric acid at atmospheric pressure were investigated. The following leaching parameters were examined to understand their effects on the dissolution of the metals: hydrochloric acid concentration, solid/liquid ratio, particle size, leaching temperature and time. Extractions of 95.8%Ni, 94.5%Co and 94

The content of metallic impurities was studied in the fine particles of gold ore recovered from various types of deposits. Experimental data showed that the gold content in the particles with diameter D < 2 μm decreases alongside with the decrease of particles sizes. This dependence is explained by the increased thermodynamic activity of the gold dispersion and amorphisation in the linear dimensions

The oxygen pressure leaching of sphalerite in sulphuric acid solutions is a slow process in the absence of iron because of the limitations of the oxygen delivery carrier (redox couple: Fe3+/Fe2+). Herein, the artificial sphalerite with 25.70%, 15.20%, 5.75% iron contents and non-iron was prepared via the sintering of ZnS and FeS and used in the kinetic oxygen pressure leaching experiment. The results

A vertical tubular reactor is used for the oxidative leaching process in the mineral processing industry, especially sphalerite. Oxygen could oxidise ferrous ions (Fe2+), and ferric ions (Fe3+) are generated as the principal oxidation agent in the reactor afterward. The partial pressure of oxygen is an instrumental parameter that could change according to reactor height. Despite the extensive studies

The effect of high-pressure grinding roll (HPGR) comminution on the physical properties of ore particles and heap leaching of gold was investigated compared with that of conventional jaw crusher comminution. The comminuted products were evaluated in terms of particle size distribution, internal crack density, and saturated water content. Compared to conventional jaw crushers, the HPGR produced finer

This communication summarises the known thermodynamic properties of impurities in liquid silicon. This information may be used to evaluate different refining processes. Example calculations are presented. The known free energy of solution and Henrian activity coefficients are provided for impurity elements dissolved in nearly pure silicon. Distribution coefficients are also given.

In this work, the effects of the dynamic precipitation on the mechanical properties of Al 2024 alloy were investigated under as-received (AR), solution heat treated (SHT), peak aged (PA) and over aged (OA) conditions. The cold, warm and hot deformation were carried out at 25°C, 150°C, 250°C and 350°C for the strain rate of 5.55 × 10−4 s−1. The results indicated that dynamic precipitation takes place

A cyclic DSC method has been adapted to study the TLPB behaviour and isothermal solidification rate (IS) in an IN625/CPW475 base metal/filler metal joint at 1000°C. Analysis of the DSC data resulted in a prediction of the maximum brazing clearance (MBC) as a function of braze time. The rate of IS was determined to be linear with the square root of time with a rate constant k = 4.59 µm/min1/2, once

Failure analysis is a key concern in the development of composites. It not only helps to understand the material performance under severe loading conditions but also to decide the suitability of the material in particular applications. In this context, this paper highlights the behaviour of AZ91E with 2 wt-% nickel-coated alumina reinforced composites under different loading conditions. Composites

The effect of chloride exposure on copper cooling element corrosion was investigated in a simulated flash smelting furnace atmosphere. Field samples exposed to low and high chloride loads were first characterized with a scanning electron microscope. The main difference between the samples was the presence of a separate copper chloride layer in the samples that had been exposed to high chloride loads

Vortexing in continuous slab casting can entrain mould powder and thus damage the slab quality. In this investigation, a 0.4-scale water caster has been employed to explore the interaction between air and vortices. Black sesame seeds are injected into the water to get the better visualisation of air-vortex interaction. Momentum exchange between ascending air bubbles and vortexing has caused variations

In this research, the role of Si on the solidification behaviour of NiAl cladding produced by the GTAW process was studied. NiAl and Ni2AlSi compounds were synthesised by mechanical alloying. The produced powders were cladded on the surface of CK45 steel using the GTAW process. Phase evolutions, microstructural changes and fractography of the produced powders as well as the cladded layers were characterised

Particle size and shape of iron ore concentrate are effective parameters in the production of quality green pellets. In this research, the effect of particle morphology on green pellet quality was studied. It was concluded that pellet quality improved with increasing specific surface area. Drop number and green compression strength of pellets ground by HPGR were found to be superior over those ground

A mathematical model has been developed by coupling genetic algorithm (GA) with heat and material balance equations to estimate rate parameters and solid-phase evolution related to the reduction of iron ore-coal composite pellets in a multi-layer bed Rotary hearth Furnace (RHF). The present process involves treating iron ore-coal composite pellets in a crucible over the hearth in RHF. The various solid

The microstructure evolution for different post-homogenisation cooling rates and the flow stress behaviour in direct chill cast AA6060 alloys were studied. Results revealed that decreasing cooling rates reduced the flow stress owing to the precipitation of Mg2Si and reduction of the solid solution level. Micro-alloying of Mn generated a distribution of α-Al(FeMn)Si dispersoids during the homogenisation

Vortices at the meniscus of the continuous casting mould can entrain mould powder into the liquid pool. The entrained globules will form slivers in the subsequent downstream processing of the slabs. This article presents a three-dimensional computational study of the vortexing at the meniscus with an emphasis on capturing flow behaviours of vortices in continuous casting mould. We have used ANSYS FLUENT

This paper describes a detailed study of the segregation process in which nickel, cobalt and iron were extracted as volatile metal chlorides from a nontronite laterite, and concentrated as alloy onto carbon within a single step. Topics covered include: metal recovery, ferronickel grade, extraction kinetics, gaseous reduction of iron oxides, evolved gas volume and composition, carbon utilisation and

The character and cause of sliver defect on IF steel sheet surface are studied by means of SEM, unstable flow in mould could induce surface velocity and level fluctuations, leading to surface defects during continuous casting of steel. The nozzle clogging is a serious problem during the continuous casting of steel, due to its influence on the casting operations and products quality. In this study,

To promote biooxidation efficiency of a refractory high-sulphide gold concentrate, microwave technology has been applied. Two factors were investigated in the microwave stage including initial solution pH and microwave irradiation time. The results show that biooxidation efficiency of the gold concentrate increases with the increasing initial solution pH. The effect of microwave irradiation on biooxidation

This study evaluates iron recovery from low grade banded hematite quartzite iron ore. The ore was found susceptible to microwaves and hence carbothermal reduction was pursued. The susceptibility of iron phases to microwave exposure and their selective absorption assists in the liberation of iron values. It was observed that ferrite balls were formed when a small fraction of ore-charcoal mixture was

During the extraction of magnesium by the electrothermal process, the condensation of magnesium vapours in the condenser is critical to achieve operational efficiency. In the present work, a mathematical heat transfer model has been developed to predict the growth rate of a single liquid metal drop during dropwise condensation (DWC) of magnesium vapours in the electrothermal process. Homogeneous DWC

Argon gas is often injected from the bottom of the ladle during steel refining operations. The injected gas interacts with the liquid (metal and slag) bath and enhances the momentum, heat, and mass transfer rate in the melt. However, during these gas–liquid interactions, an opening of the slag layer called slag eye is formed, which exposes the molten metal surface to the atmosphere, which is generally

The foaming behaviour originating from the reduction of iron oxide in molten CaO–SiO2–MgO–Al2O3–TiO2 slag was studied at 1500°C with the aid of a real-time foaming process monitoring system. The effect of TiO2 content and binary basicity on the slag foaming were investigated. It was found that the TiO2 content has a significant influence on the foaming degree, while the basicity of the slag has a smaller