Cobalt distribution during copper matte smelting

Many smelter operators subscribe to the “precautionary principle” and wish to understand the behavior of the metals and impurities during smelting, especially how they distribute between product and waste phases and whether these phases lead to environmental, health, or safety issues. In copper smelting, copper and other elements are partitioned between copper matte, iron silicate slag, and possibly the waste gas. Many copper concentrates contain small amounts of cobalt, a metal of considerable value but also of some environmental interest. In this work, the matte/slag distribution ratio (weight percent) of cobalt between copper matte (55 wt pct) and iron silicate slag was thermodynamically modeled and predicted to be approximately 5. Experiments were performed using synthetic matte and slag at 1250 °C under a low oxygen partial pressure and the distribution ratio was found to be 4.3, while between industrial matte and slag, the ratio was found to be 1.8. Both values are acceptably close to each other and to the predicted value, given the errors inherent in such measurements. The implications of these results for increasingly sustainable copper production are discussed.     

Investigation of effect of colemanite addition on copper losses in matte smelting slag

Abstract

In this study, the aim was to reduce copper losses to slag in copper production by using a boron compound, called colemanite (2CaO.3B₂O₃.5H₂O), as flux, besides silica. In order to achieve this purpose, two different matte–slag couples were used; the flash furnace matte-slag obtained from Eti Copper Inc. (EB?) and a master matte–slag without copper produced synthetically under laboratory conditions. Chemical analyses of flash furnace slag and synthetic master slag were 0·88%Cu–36·1%SiO₂–43·9%FeO–3·7%Fe₂O₃ and 37·6%SiO₂–60·0%FeO–2·4%Fe₂O₃ respectively. In each experiment, the same amounts of slag and matte were mixed with the addition of predefined amounts of colemanite and melted together at 1250°C for different durations under nitrogen atmosphere in a silica crucible. Results showed that it was possible to decrease the copper losses to about 0·3–0·4% by accelerating the settling rate of matte particles by the addition of colemanite, which was attained by the expected increase in flash furnace slag fluidity and lowering of its liquidus temperature.

Dans cette étude, le but était de réduire les pertes de cuivre dans la scorie lors de la production de cuivre en utilisant un composé de bore, appelé colémanite (2CaO.3B₂O₃.5H₂O), comme flux, en plus de la silice. Afin d’atteindre cet objectif, on a utilisé deux couples différents de matte-scorie; la matte-scorie du four éclair obtenu de Eti Copper Inc. (EB?) et une matte-scorie modèle sans cuivre, produite synthétiquement sous conditions de laboratoire. Les analyses chimiques de la scorie du four éclair et de la scorie synthétique modèle étaient de 0·88%Cu–36·1%SiO₂–43·9%FeO–3·7%Fe₂O₃ et de 37·6%SiO₂–60·0%FeO–2·4%Fe₂O₃, respectivement. Dans chaque expérience, on a mélangé la même quantité de scorie et de matte, avec addition de quantités prédéfinies de colémanite, et fondu ensemble à 1250°C à différentes durées sous atmosphère d’azote dans un creuset de silice. Les résultats ont montré qu’il était possible de diminuer les pertes de cuivre à environ 0·3–0·4% en accélérant la vitesse de sédimentation des particules de matte par l’addition de colémanite, ce qui était atteint par l’augmentation attendue de la fluidité de la scorie du four éclair et par l’abaissement de sa température de liquidus.     

Trace element distributions between matte and slag in direct nickel matte smelting

ABSTRACT

Behaviour of trace elements in the nickel matte smelting was studied at 1673 K (1400°C) by equilibration-quenching techniques followed by direct phase analyses using electron probe X-ray microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. The matte-slag samples at silica saturation were equilibrated with SO₂-CO-CO₂-Ar mixtures of fixed p_SO2, p_S2 and p_O2 in order to obtain a pre-determined oxidation degree for the sulphide matte, and thus to generate a targeted iron concentration of the nickel-copper–iron sulphide matte (Ni:Cu = 5, w/w), depending on the slag chemistry. The slag composition was varied from 0 to 2 wt-% K₂O and 0–10 wt-% MgO in silica saturation. The studied trace elements were Co, Ge, Pb, Se and Sn, but also the matte-to-slag distributions of the slag forming fluxing components Mg (MgO) and Si (SiO₂) were determined experimentally. Selenium was the only trace element studied which strongly enriched in the low-iron nickel mattes, and the deportment became larger when the sulphide matte depleted with iron. All the other trace elements behaved in the opposite way.     

Selenium partitioning between slag and matte during smelting

Copper concentrates usually contain a number of minor as well as precious elements, the control of which in copper smelting processes is often a key to the quality of the anode copper produced and may also have a bearing on the overall economics of the process. During copper smelting, the copper concentrates are partially oxidized to form slag and matte. The molten slag and matte are separated from each other in the settler. The matte being heavier in density settles at the bottom of the furnace and slag being lighter in density floats over the matte and is eventually discarded off. During the separation, selenium is distributed between slag and matte. Selenium is a value added by-product of copper process. The lower recovery of selenium from the copper process is attributed to the high loss of selenium to the discarded slag. Knowledge of the distribution and form of selenium in slag and matte is very important in the control of the selenium loss, although to date very little is known regarding their distribution. The samples of slag and matte were collected from the smelter exit before their separation. Selenium was added in different proportions in the sample. The experiments involving slag-matte separation were performed at 1250°C for 4 hours of soaking time under inert atmosphere in a vertical tubular furnace. The distribution of selenium and the mechanism by which selenium is dissolved in matte and slag have been established by this study.     

Thermodynamic behavior of bismuth in copper pyrometallurgy: Molten matte,white metal and blister copper phases

This study developed thermodynamic data relating to the behavior of bismuth in copper smelting, converting and refining processes. The activity of bismuth was set by establishing a known vapor pressure of bismuth over melts of various phases. The melts were equilibrated with the vapor, and the resulting bismuth content used to establish bismuth activity coefficients. Experiments were carried out, under controlled oxygen potentials, at 1200 and 1250 °C. Results show that bismuth deviates positively from Raoult's Law at both 1200 and 1250 °C in copper (γ_Bi = 2.17, 2.27), white metal (γ_Bi = 6.1, 6.1), Cu₂S with 2 wt pct FeS (γ_Bi = 8.0, 8.0), Cu₂S with 4 to 6 wt pct FeS (γ_Bii = 16.4, 16.4) and Cu2S with 8 to 70 wt pct FeS (γ_Bi = 13.6, 13.6), respectively. Sabri Arac formerly Research Assistant at University of Arizona Gordon H. Geiger formerly head of the Department of Metallurgical Engineering at the University of Arizona     

Oxidation of molten copper matte

An amount of 80 mg of molten copper matte of a pseudo-ternary Cu₂S-FeS-Fe system contained in a slender alumina sample tube was oxidized at 1503 and 1533 K in a mixed O₂-Ar gas stream and the oxidation path was followed, comparing the overall rate of oxidation with the gaseous diffusion in the sample tube. The following successive reactions were found to be controlled by gas diffusion. Initially, Fe was oxidized to form FeO. After the melt composition reached a pseudo-ternary Cu₂S-FeS-FeO system, FeS was oxidized to form FeO. As the amount of FeO increased, Fe₃O₄ was also formed and subsequently Cu was produced by the oxidation of Cu₂S. In the latter stage, the Cu was oxidized, and the final product under the condition of gas diffusion control was composed of Cu₂O, Fe₃O₄, and CuFeO₂. On the other hand, the rate of formation of Fe₂O₃, CuO, and CuFe₂O₄ was much slower and they were not formed during the oxidation duration where the overall rate of oxidation was controlled by gas diffusion.     

Activities of CoS and FeS in copper mattes and the behavior of cobalt in copper smelting

The distributions of cobalt and iron between metallic copper and high copper mattes were measured at 1400 and 1500 K. A value of 0.40 ±0.02 was found as the Raoultian activity coefficient of CoS at infinite dilution in the Cu₂S-FeS-CoS mattes. The present activities of FeS in the Cu-saturated Cu₂S-FeS mattes were found to deviate more positively than those reported by Krivsky and Schuhmann at 1623 K, and the positive deviation from the Temkin’s ideality was greater at 1400 K than at 1500 K. Using the activity coefficient of CoS, the partitions of cobalt between copper mattes and fayalitic slags were calculated for various conditions of copper smelting. It was found that cobalt exhibits, in the matte-slag equilibria, chemical properties intermediate between nickel and iron, but much closer to iron than to nickel. The overall recovery of cobalt in blister copper depends on matte grade, and is as low as 3 pct at best. When a high cobalt recovery is desired, therefore, a copper concentrate rich in cobalt must not be processed by conventional pyrometallurgical technology in view of the inevitably high loss to slag. M. NAGAMORI, formerly Associate Professor, Department of Metallurgical Engineering, University of Utah, Salt Lake City, Utah.     

铜渣熔融还原过程中硫的行为特征

对铜渣熔融还原过程中硫的行为特征进行了研究.结果表明,熔渣碱度从0.8增至1.4,渣硫容量增大脱硫作用增强,铁水硫含量由0.6%降至0.13%;铁水脱硫为吸热反应,熔渣温度由1 773 K升至1 823 K渣脱硫能力提升,铁水含硫由0.13%降至0.089%.熔渣-铁水硫理论分配比远大于实验时间条件下硫分配比,保温时间延长铁水脱硫率提高.熔渣碱度1.4、保温温度1 823 K和保温时间40 min时,处理后铁水含硫为0.11%,含量仍较高,需进一步对铁水进行脱硫预处理才可用于炼钢.     

Mathematical modeling of minor-element behavior in flash smelting of copper concentrates and flash converting of copper mattes

A mathematical model has been developed to describe the behavior of minor elements during flash smelting and flash converting. The model incorporates equations describing volatilization of minor elements from the molten particles and distribution of these elements between the molten phases in the settler. The basic premise of the volatilization model is that at the surface of the molten particle, the partial pressures of the minor-element species are those at equilibrium. Transport of the minor-element species to the gas then is described by external mass transfer. Good agreement has been obtained between observed and predicted behaviors. The effects of oxygen enrichment, matte grade, and wall temperature, as well as the bath temperature, on minor-element behavior have been elucidated. Formerly Assistant Professor, Department of Metallurgy and Metallurgical EngineeringUniversity of Utah, Salt Lake City, UT Formerly Metallurgical Engineer Kennecott, Salt Lake City, UT     

祥光铜冶炼厂冰铜研磨机的安装

介绍了冰铜研磨机的安装工序,详细叙述了施工要点、精度要求、使用的器具和人员安排等。     

祥光铜冶炼厂冰铜研磨机的安装

介绍了冰铜研磨机的安装工序,详细叙述了施工要点、精度要求、使用的器具和人员安排等.     

水口山炼铜法

全面介绍了水口山炼铜法的主要设备、流程、工艺参数、技术经济指标,对主要的技术指标进行了评述,并对该法的未来进行了展望。     

水口山炼铜法

全面介绍了水口山炼铜法的主要设备、流程、工艺参数、技术经济指标，对主要的技术指标进行了评述，并对该法的未来进行了展望。     

Studies on the anodic dissolution of copper matte

Anodic polarisation studies on copper matte revealed that a copper matte electrode polariess abruptly in H,SO, solution but not in HCl solution. Anodic dissolution of copper matte was studied at various anodic potentials in 2 N solutions of HCl and H,SO,. It was found that at lower anodic potential (around 0.4 volt vs. saturated calomel electrode) copper dissolves preferentially (at 90% current efficiency) over iron (8–10% C.E.), in both the acid solutions. It was further observed that this preferential dissolution of copper takes place over a longer period (about 6 h) in HCl than in H₂SO₄ solution (about 3 h). Preferential dissolution of copper from copper matte was found to be independent of HCl concentration (0.5 N to 4 N). From the X-ray diffraction analysis of the original copper matte and electrolysed copper matte, it was established that digenite and bornite phases of copper matte dissolved causing preferential dissolution of copper.     

铜富氧底吹熔池熔炼过程机理及多相界面行为

通过深入分析铜富氧底吹熔池熔炼过程,结合铜冶金过程相关理论,构建了底吹熔炼体系机理模型.该模型在反应区沿纵向分为7个功能层,分别为烟气层、矿料分解过渡层、渣层、造渣过渡层、造锍过渡层、弱氧化层和强氧化层;炉内沿横向分为反应区、分离过渡区和液相澄清区3个功能区;各层/区分别承担不同的功能,构成一个有机整体,在熔体流场作用下,体系中多相多组元如CuFeS2、FeS2、Cu2S、FeS、2FeO·SiO2、Cu2O、FeO、Fe3O4、SO2、H2O、N2、S2等因物化性质差异,通过层/区间的界面进行快速传质行为;底吹熔炼体系处于动态的非稳态相平衡状态,氧势-硫势在炉内纵向及横向方向上均有梯度变化,通过合理控制不同层/区的氧势-硫势大小,可强化反应过程,进一步提升底吹炉熔炼能力.     

Kinetics of copper dissolution during pressure oxidative leaching of lead-containing copper matte

The kinetics of pressure oxidative leaching of lead-containing copper matte with sulfuric acid was investigated. The effects of particle size, leaching temperature, oxygen partial pressure and sulfuric acid concentration on the kinetics and mechanism of copper extraction were studied. It was found that the reaction kinetic model follows the shrinking core model of chemical reaction control and the apparent activation energy was determined as 39.1 kJ/mol. The order of the reaction with respect to total pressure was found to be 0.64. The kinetic equations for the effect of particle size, leaching temperature, total pressure and sulfuric acid concentration were obtained and a mathematical model of copper extraction from lead-containing copper matte was developed as:

This equation estimates the extraction of copper with very good agreement (r = 0.99) between the experimental and calculated values.     

富氧侧吹熔池熔炼炉炼铜的生产实践

富氧侧吹熔池熔炼炉集物料的干燥、焙烧和熔炼于一炉。富氧侧吹熔池熔炼工艺投产后,对工艺控制参数和工艺的可变性及相应的控制方法进行了试验和摸索,试生产中出现了烟气中单体硫含量高、余热锅炉振动大、富氧侧吹熔池熔炼炉风眼砖和炉墙腐蚀严重、出口垂直烟道结渣及余热锅炉烟尘烧结等问题,通过分析提出了解决的方法,并对工艺的进一步优化提出建议。     

A thermodynamic model of nickel smelting and direct high-grade nickel matte smelting processes: Part I. Model development and validation

A thermodynamic model has been developed to predict the distribution behavior of Ni, Cu, Co, Fe, S, As, Sb, and Bi in the Outokumpu flash-smelting process, the Outokumpu direct high-grade matte smelting process, and the INCO flash-smelting process. In this model, as many as 16 elements (Ni, Cu, Co, Fe, As, Sb, Bi, S, O, Al, Ca, Mg, Si, N, C, and H) are considered, and two nickel sulfide species are used to allow for modeling of sulfur-deficient mattes. The compositions of the matte, slag, and gaseous phases in equilibrium are calculated using Gibbs free energies of formation and the activity coefficients of the components derived from the experimental data. The model predictions are compared with the known industrial data from the Kalgoorlie Nickel Smelter (Kalgoorlie, Australia), the Outokumpu Harjavalta Nickel Smelter (Harjavalta, Finland), the INCO Metals Company (Sudbury, Canada), and from a number of experimental data. An excellent agreement is obtained. It was found that the distribution behaviors of Ni, Co, Cu, Fe, S, As, Sb, and Bi in the nickel smelting furnace depend on process parameters such as the smelting temperature, matte grade, and partial pressure of oxygen in the process.     

Phase transformations of copper and nickel sulfides in granular converter matte

The phase composition and microstructure of a rapidly cooled high-copper converter matte are studied by electron probe microanalysis, high-temperature X-ray diffraction, and differential scanning calorimetry. The temperatures of phase transitions for copper and nickel sulfides and the unit cell parameters at various temperatures are determined. The high dispersity of the structure, the thermal deformation anisotropy of the lattices, and the deviations from the stoichiometry of copper and nickel sulfides due to fast cooling of the melts explain the enhanced reactivity of the granular converter matte in hydrometallurgical processes.