Search

During the pyrometallurgical processing of copper sulphide raw materials, part of the charge leaves the furnace space together with the exhaust gases in the form of dust entrainment. Volatile components also pass into the dust-gas flow, due to which it is enriched with impurities, some of which are harmful to the technological process. The formed dust-gas flow passes through dust collection equipment, where the main part of it is captured. Most often, the captured dust is recirculated, which leads to a decrease in the productivity of the furnace unit and a gradual increase in the content of impurities in the condensed products of the smelting. To overcome these disadvantages, it is necessary to take part or all the recirculating dust out of the melting cycle and process it independently to extract the valuable metals and dispose of the harmful substances. In metallurgical practice, industrial application for the processing of recirculating dust entrainment has mainly been accomplished by hydrometallurgical methods based on treating the flue dust in aqueous solutions of acid or alkaline reagents. In the present research work, laboratory results on hydrometallurgical leaching of flue dust from a flash furnace waste heat boiler (FF-WHB) are presented. The effect of the main technological parameters affecting the degrees of recovery of the main metals in solution was studied. Based on the experimental results, the optimal conditions for hydrometallurgical treatment of the FF-WHB flue dust were determined. By treating the dust under optimal conditions, the main tasks of the research are achieved - removal of impurities harmful to the technological process and reduction of the amount of flue dust processed in the flash furnace. [ABSTRACT FROM AUTHOR]

The distribution of copper, iron, and sulfur during the oxidation of La Caridad copper concentrate particles under simulated flash smelting conditions was studied in a laboratory reactor. Six wet-sieved size fractions and the unsieved copper concentrate were oxidized at 1123 K and 40% and 70% O2 by volume in the process gas during the experiments. Samples of partially oxidized particles were collected at 0.2, 0.8, and 0.9 m from the point of entry and analyzed in a QEMSCAN® unit to determine the elemental composition within the population of particles. The distribution of the major elements during oxidation was strongly dependent upon the size and chemical composition of the initial particles. Overall, the copper content tended to increase and sulfur content decreased along the reactor length within all sizes. In contrast, the distribution of iron did not follow a general trend, as it was found to increase, decrease, or remain unchanged depending on the particle size. This finding may represent a key feature to further investigate the reaction path followed by particles during flash smelting, especially those associated with particle fragmentation. In general, the larger the particle size was, the larger the change in the content of the major elements within the particle population. Based on the experimental results, particles within a size fraction of <45 µm tended to follow a reaction path consisting of rapid melting followed by the collision and coalescence of reacting droplets during flight. In contrast, particles within the fraction of 45–53 µm tended to react individually. The oxidation behavior of the unsieved concentrate particles showed a combination of both reaction paths. [ABSTRACT FROM AUTHOR]

• The ignition and combustion of nickel concentrates were investigated using a laminar flow furnace. • The effects of temperature and oxygen enrichment in the process gas were determined. • The ignition of the nickel concentrates started at a temperature below 800 °C. • The highest sulfur removal from nickel concentrates was achieved under the most oxidizing conditions. • Fe and S were preferentially oxidized forming SO 2 and a porous FeO x -rich rim. The suspension oxidation of nickel sulfide concentrates in flash smelting conditions was studied using a laboratory-scale laminar flow furnace. The effects of temperature (800–1100 °C) and oxygen concentration (40–85 vol%) in the process gas were investigated. The surface morphology and mineralogical compositions of samples were examined using scanning electron microscopy equipped with energy-dispersive X-ray spectrometry. The sulfur removal from concentrates was determined using chemical analysis assuming iron as a non-volatile component. It was found that ignition of the nickel concentrates started at a temperature below 800 °C. The sulfur removal from the sieved concentrates increased with increasing temperature. The oxidation was initiated with preferential oxidation of iron in sulfides forming an iron oxide-rich scale on sulfidic core. [ABSTRACT FROM AUTHOR]

The temperature of the flame of copper concentrates was determined through spectral measurements by using an optical and infrared spectrometer, where the experimental data were adequately processed by the two-colour pyrometer method. Experiments were carried out in a drop-tube, and the furnace temperature was 773 K ensuring the ignition of concentrates. This technique allowed an in-situ evaluation to be made of the effect of the oxygen content in the feed gas and the sulphur in the concentrate. Two intense peaks at 750 nm wavelength from spectral measurements may be explained by the oxidation of labile sulphur in concentrates. The flame temperature was between 1600 and 2100 K and this increased with both oxygen concentration and S/Cu ratio. The direct study of emission spectra through unique measurement probes can help to have a more profound vision of what is happening with the concentrated particles subjected to flash combustion conditions. This work has special interests in the pyrometallurgical industry, presenting a critical lack of non-invasive techniques for monitoring and controlling the process.

Soot is a necessary product in the smelting process. The soot is the peroxide particle that does not settle into the molten pool in the reaction tower of the flash furnace, and its particle size is very small and takes the molten spherical form. The generation of soot affects the direct yield of smelting, while the distribution of soot in different regions affects the selection of soot collection equipment, and the distribution of impurities in the smelting process is very important to the ingredients. In the case study of the smelting project of Zijin Copper Industry Co., Ltd., this paper explores the distribution of soot and impurities in the flash smelting process, so as to provide support for the refined management and control of subsequent production and improve the technical level of production and management of smelting enterprises. [ABSTRACT FROM AUTHOR]

While particle combustion and chalcopyrite oxidation in suspension smelting is well understood, few studies are available regarding the melt-melt reactions and the separation between copper matte and slag in matte smelting. In the present work, experimental investigations in air and argon atmosphere were conducted using a mixture of synthetic slag and chalcopyrite concentrate. The sequential reaction and separation processes occurring in matte smelting are outlined. Possible limiting factors in the overall process are also proposed. The result of the present work forms an important foundation for future work in the kinetic rate formulation of molten phase reactions between copper matte and slag in matte smelting.

Pyrite is the most common mineral in polymetallic sulphides ores. In order to apply the combustion group theory to the pyrometallurgical processes that occur in the reaction shaft, it is necessary to know the kinetic processes that happen in pyrite. In this study, thermogravimetric analysis was carried out under oxidative atmospheric conditions with 100% O2 and a heating ramp of 5, 10, 15 and 20 °C min−1. The material used was pyrite with a grain size of 63–125 μm. From the thermogravimetric data, we got the kinetic parameters of the oxidative reactions of pyrite. The different kinetic methods used in this study have been E1641-16 ASTM, Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman. These methods were used for obtaining the kinetic parameters through regression analysis, sum of squares, mean residuals between experimental and calculated values and Student coefficient (95%) and to determine which kinetic method is the most suitable to describe the kinetics of pyrite oxidation. [ABSTRACT FROM AUTHOR]

Slag chemistry of the direct nickel matte smelting was studied in typical industrial high-grade nickel matte smelting conditions at 1400 °C and 0.1 atm pSO2. The experimental technique used involved equilibration, quenching and direct elemental phase composition analysis by Electron Probe X-ray Microanalysis. Magnesia and potassia, a typical gangue constituent of sulfidic nickel concentrates and a common impurity of industrial grade silica flux (sand), respectively, were adopted as slag modifiers in concentrations typical to industrial operations. Their effects on oxidation degree of the nickel-copper-iron matte and equilibrium concentrations of Ni and Cu in the slag were studied as a function of oxygen partial pressure. Solubility of silica in the slag increased significantly with additions of MgO and K2O in the constrained case studied, at silica saturation. Equilibrium concentrations of Ni and Cu in the slag containing MgO and K2O were about a quarter lower compared to the pure iron silicate slag, in the entire oxygen partial pressure range studied. [ABSTRACT FROM AUTHOR]

Process control in flash smelting is based on mass and energy balance from which the operational parameters (oxygen coefficient, oxygen enrichment, and flux demand) are obtained to achieve matte and slag with defined compositions and at defined temperatures. Mineral compositions of copper concentrates, and their blends, have been used in order to optimize the heat process balance. The classical balance methodology has been improved by using equations for molecular ratios and distribution coefficients that have been calculated using FactSage™. This paper describes the development of balance equations and compares their theoretical (equilibrium) results with industrial data logs of the smelting process.

The pyrometallurgical processes for primary copper production have only off-line and time-demanding analytical techniques to characterize the in and out streams of the smelting and converting steps. Since these processes are highly exothermic, relevant process information could potentially be obtained from the visible and near-infrared radiation emitted to the environment. In this work, we apply spectral sensing and multivariate data analysis methodologies to identify and classify copper and iron sulfide minerals present in the blend from spectra measured during their combustion in a laboratory drop-tube setup, in which chemical reactions that take place in flash smelting furnaces can be reproduced. Controlled combustion experiments were conducted with two industrial concentrates and with high-grade mineral species as well, with a focus on pyrite and chalcopyrite. Exploratory analysis by means of Principal Component Analysis (PCA) applied on the spectral data depicted high correlation features among species with similar elemental compositions. Classification algorithms were tested on the spectral data, and a classification accuracy of 95.3% with a support vector machine (SVM) algorithm with a Gaussian kernel was achieved. The results obtained by the described procedures are shown to be very promising as a first step in the development of a predictive and analytical tool in search of fitting the current need for real-time control of pyrometallurgical processes.

In a technological process of copper production in the flash smelting furnace, slags with high metal contents, such as copper, lead and iron, are generated. These slags differ in their chemical compositions from slags obtained in processes of copper concentrate flash smelting or bath smelting. With the technology used at KGHM, the slag discussed in the article is processed during smelting reduction that is carried out in the electric furnace. As a result, a Cu-Pb-Fe alloy is obtained and subjected to the converting process along with waste slag which contains ca. 0,5 % mass Cu. The article presents an analysis of results of the research on behaviour of iron in the course of slag reduction where diverse fine-grained carbon-bearing materials function as reducers.

Blister copper smelting in a flash smelting furnace results in generation of slag that contains high amounts of copper, iron and lead. Most commonly, this material is subjected to reduction with coke in an electrical furnace. In the present paper, results of investigations on reduction of slag with another reducer, i.e. anthracite dust, are discussed. Each experimental slag was analysed for its microstructure, chemical composition and phase composition. Based on the results, a decopperisation level of the study material was estimated. It was shown that anthracite dust might be considered as an alternative for currently used reducers.

A novel mathematical model for combustion of a single copper concentrate particle is presented. The model includes particle volatilization, fragmentation, smelting, and combustion phenomena. This model has been incorporated into a general computational fluid dynamics code to calculate flow field and particle trajectories needed to simulate the smelting process in flash furnaces. In this model, Lagrangian approach was used to handle solid particles and droplets of liquid fuel charged, while Eulerian framework was used to handle the gas phase flow field. The results show that the effect of particle fragmentation was remarkable in flash smelting process as compared with experimental data and should be considered in combustion modeling. Moreover, the flash smelting process simulation results show that the reaction shaft design should be optimized based on a combination of furnace dimension and type of concentrate burners. [ABSTRACT FROM AUTHOR]

The aim of the work was to improve the understanding of deposit formation and corrosion in a copper flash smelting plant, focusing on the effects of process gas temperature (400-900 °C) and heat-transfer surface temperature (160-320 °C) on deposit formation and corrosion rate. The rate of build-up increased as a function of process gas temperature, which was explained by a larger extent of sintering at higher temperatures, resulting in slagging and thus, in better adhesion of particles hitting the surface. The corrosion rate increased as a function of process gas temperature. Iron sulphate (FeSO or Fe(SO)) was found at the interface between the deposit and the corroded metal surface, suggesting that corrosion was induced by sulphuric acid (HSO) from the reaction between SO (originating from SO in the process gas) and water vapour. [ABSTRACT FROM AUTHOR]