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.     

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.     

Activities of As,Sb, Bi,and Pb in copper mattes— Effect of O,Ni, and Co

The effects of oxygen, nickel, and cobalt on the activity coefficients of As, Sb, Bi, and Pb in copper mattes were measured at 1200 °C (1473.15 K) using the transportation method. The transportation experiments concerning the effect of oxygen were carried out as a function of the SO₂ content (1 to 100 vol pct) in the carrier gas and using high- and low-grade matte samples, ≈80 and ≈40 wt pct Cu, respectively. The prevailing sulfur and oxygen partial pressures were evaluated on the basis of matte and carrier gas compositions. The effect of the SO₂ pressure on the activity coefficients was found to be very small compared with the effect of the sulfur pressure, whereas the effect of the SO₂ partial pressure on the vaporization behavior, especially of As, was very significant, due to the additional vaporization of As as AsO gas molecules, which caused an increase in the As removal rate. At a higher oxygen partial pressure than 10^−8.5 atm (3.2·10⁻⁴ Pa) a noticeable decrease in the Sb activity coefficients was observed due to the oxidation. This did not, however, decrease the Sb removal rate, since the relative proportion of the oxide gas molecules in the gas phase increased simultaneously. The interactions between dissolved Ni or Co and the impurity elements were investigated by doping (1 wt pct) the high grade (Cu ≈75 wt pct) matte samples with Ni or Co. At stoichiometric and sulfur-deficient matte compositions, Ni and especially Co decreased the activity coefficients of As and Sb, but did not have any effect on the activity coefficients of Bi and Pb, compared with the corresponding sulfur content in the Ni- and Co-free mattes. For mattes of higher sulfur content Ni and Co did not show any marked effect on the activity coefficients of As, Sb, Bi, and Pb. A. ROINE, formerly with Institution of Process Metallurgy, Helsinki University of Technology, SF-02150, ESPOO, Finland     

Electrocapillary motion of copper and nickel matte droplets on fayalite-based slag surfaces

The electrocapillary motion of Cu₂S and Ni₃S₂ droplets on the surface of fayalite-based slags under 50% Ar-CO atmosphere has been studied for the effects of droplet size, temperature, electric field strength. Cu content m Cu₂S-FeS droplets, Ni content in Ni₃S₂ FeS droplets and slag composition. The copper matte droplets migrate to the anode (positive electrode) while the nickel matte droplets migrate to the cathode (negative electrode). Typical speeds encountered are of the order of 0.05–0.80 cm/s (Cu) and 0.16–0.62 cm^−s (Ni) with droplet diameters between 0.10 and 0.28 cm, applied potentials between 0.17 and 2.0 V/cm (Cu) and 0.75 and 3.3 V cm (Ni) and for temperatures between 1473 and 1573 K. The migration rate appears to be independent of droplet size for droplet diameters between 0.10 and 0.28 cm, but it increases with applied potential field and temperature.The effects of matte and slag contents on the migratory behavior are complex. As the Cu content in the Cu₂S-FeS matte droplet increases above 40% Cu. the migration rates also increase. Below 40% Cu matte grade, the migration rates are not significantly different. As the Ni content in the Ni₃S₂-FeS matte droplet increases, the migration rates decrease. These migration rates are also affected by the slag composition. As the Cu and Ni matte droplets migrate in opposite directions under the influence of the electric field, electrocapillary phenomena may be used to enhance metal recovery in slag cleaning operations using electric furnaces.     

电感耦合等离子体原子发射光谱法测定铜熔炼渣中铅锌镍锑铋砷

铜熔炼渣是火法造锍捕金过程中产生的冶炼废渣,建立渣中铅、锌、镍等杂质元素的测定方法对底吹炉熔炼工艺控制极为重要.实验采用硝酸、盐酸、氢氟酸、高氯酸溶解样品,采用电感耦合等离子体原子发射光谱法测定铅、锌、镍、锑、铋、砷,选择Pb 220.353 nm、Zn 213.856 nm、Ni 231.604 nm、Sb 206....     

A thermodynamic database for copper smelting and converting

The thermodynamic properties of the slag, matte, and liquid copper phases in the Cu-Ca-Fe-Si-O-S system have been critically assessed and optimized over the ranges of compositions of importance to copper smelting/converting based on thermodynamic and phase equilibria information available in the literature and using the modified quasichemical model. A thermodynamic database has been developed, which can be used for the calculation of matte-slag-copper-gas phase equilibria of interest for the production of copper. The model reproduces within experimental error limits all available experimental data on phase diagrams, matte-alloy miscibility gap and tie-lines, enthalpies of mixing, and activities of Cu and S in the matte and liquid alloy. The calculated solubilities of Cu in both S-free slag and slag equilibrated with matte are also in good agreement with experiment under all studied conditions, such as at SiO₂ saturation, in equilibrium with Fe, Cu, or Cu-Au alloys, at fixed oxygen or SO₂ partial pressures and at different contents of CaO in the slag. Sulfide contents (sulfide capacities) of the slags are predicted within experimental error limits from the modified Reddy-Blander model, with no adjustable parameters. As an example of the application of the database, the stability field of matte/slag equilibrium is calculated, and the matte and slag compositions are plotted vs iron to silica ratio in the slag at various SO₂ pressures over this field. The matte-slag two-phase field is limited by the calculated lines corresponding to precipitation of copper, silica, and magnetite.     

Activities of As,Sb, Bi,and Pb in copper mattes

The transportation method was used to determine the activity coefficients of the minor impurity components As, Sb, Bi, and Pb in homogeneous copper mattes (Cu-Fe-S) as functions of the Cu/Fe mole fraction ratio and of the sulfur content of the matte at 1200 °C. All matte samples contained about 0.2 wt pct As, Sb, Bi, and Pb. The activity coefficients were calculated on the basis of primary experimental data and available thermodynamic values of the gas components, which exist over the mattes. The sulfur-to-metal ratio, which controls the activities of the main matte constituents, was found to be the most important factor influencing the activities. When the sulfur-to-metal ratio of the matte changed from sulfur deficit to sulfur excess, the activity coefficient of As varied from 0.52 to 38, Sb from 3.3 to 82, Bi from 75 to 3.4, and Pb from 25 to 0.079 in the matte. The activities of AsS_1.5, AsS, SbS_1.5, BiS_1.5, and PbS had negative deviations from the ideal behavior.     

基于MetCal的双底吹连续炼铜工艺全流程模拟计算

以"底吹造锍熔炼-底吹铜锍吹炼"铜冶炼工艺为设计计算对象,基于冶金工艺流程计算系统开发平台(MetCal),运用化学平衡、质量守恒、热量守恒、元素分配约束等原理建立了底吹熔炼配料、底吹造锍熔炼、底吹熔炼余热锅炉、底吹铜锍吹炼、铜锍吹炼余热锅炉等冶金单元数学模型.开发了双底吹炼铜工艺全流程模拟系统,通过计算得到了全流程物...     

Mathematical modeling of sulfide flash smelting process: Part III. Volatilization of minor elements

The mathematical model described in Part I^[14] was extended to include the minor element behavior inside a flash-furnace shaft during flash smelting of copper concentrate. The volatilization of As, Sb, Bi, and Pb was computed, and experiments were carried out for Sb and Pb in a laboratory flash furnace. Satisfactory agreement between the predicted and measured results was obtained for antimony and lead. From the computational results, the behavior of each minor element was predicted for various target matte grades. The model predictions show that the elimination of As and Bi to the gas phase increases sharply at about 0.3 m from the burner; however, that of the Sb increases gradually along the flash-furnace shaft, and that of lead occurs suddenly at about 0.6 m from the burner. The predicted results also show that the elimination increases for Bi and Pb as the target matte grade increases; however, it is relatively independent of the target matte grade between 50 and 60 pet Cu for As and Sb. At higher target matte grades above 60 pet Cu, the elimination of As and Sb decreases as matte grade increases. formerly Graduate Student, Department of Chemical Engineering, University of Utah,     

Thermodynamics of Copper Matte Converting: Part II. Distribution of Au,Ag, Pb,Zn, Ni,Se, Te,Bi, Sb and As Between Copper,Matte and Slag in the Noranda Process

The solubility of minor elements in fayalitic slags was assessed thermodynamically assuming exclusively oxidic dissolution for Pb, Zn and Ni, metallic dissolution for Au and Ag, molecular and monatomic dissolution for Se and Te, and monatomic dissolution for Bi, Sb and As. Based on these assumptions as well as the thermochemical data in the literature, an analytical method was developed to calculate the distribution equilibria of minor elements between copper, matte and slag phases. As an example of the application, the method was demonstrated for the analysis of behavior of minor elements in the Noranda Process producing metallic copper or high grade matte. The distribution of minor elements was expressed in terms of concentration ratios of an element for copper/matte, copper/slag and matte/slag phases. Using the concentration ratios and also formulae compensating for mechanical suspension, apparent distribution coefficients of the minor elements in the actual process were calculated as a function of the process parameters: temperature, partial pressure of SO₂, magnetite activity and matte grade. An excellent agreement was observed between the calculated and observed data, thus providing logical basis for interpreting operating data of the Noranda Process. The behavior of minor elements under various operating conditions can also be predicted by the present model.     

Distribution equilibria and slag chemistry of DON smelting

Equilibrium fluxing chemistry and metal value distributions of nickel matte smelting in the one-step direct nickel matte technology have been determined experimentally at 1350–1450°C in MgO-bearing iron silicate slags at silica saturation. The aim was to approach the detailed smelting chemistry at typical concentrations 2.5–10?wt-% iron in MgO-bearing iron silicate slags at silica saturation by quenching and X-ray microanalysis. The results obtained under controlled P(O₂) and P(S₂) as well as constant P(SO₂)?=?0.1?atm show that copper and nickel solubilities in the slag as well as matte-to-slag distributions favour matte when the slag is modified by magnesia. At the same time, along with increasing magnesia content of the slag, its iron activity is affected by the dissolution of MgO in the slag, and iron concentration of the formed nickel matte is lowered considerably, and its sulphur concentration increased at constant oxygen and sulphur pressures of the gas phase.     

Thermodynamic simulation model of the isasmelt process for copper matte

A computer model has been constructed to simulate thermodynamically the behavior of the minor elements Zn, Pb, As, Sb, and Bi as well as the major elements Cu, Fe, Si, O, and S in the Isasmelt process, producing copper matte. The model is based on the new concept that there are two independent reaction sites in a slag bath: one for fast oxidation and the other for slow reduction. The oxidizing reaction at the first site produces matte, magnetite-rich slag and gas from chalcopyritic concentrate and siliceous flux. The slag is then partially reduced with lump coal at a site removed from the first site. The oxidizing and reducing reactions are assumed to proceed under a separate set of equilibrium conditions. The process heat balance and thermodynamic distribution of the minor elements are united and expressed as functions of varying weights and compositions of concentrate, flux (silica, limestone), coal, oil, and oxygen-enriched air. The process chemistry was analyzed in terms of Fe₃O₄, FeO, and FeS activities, as well as SO₂ partial pressure. The thermodynamic model explains well the minor element distributions observed in the 15 tons per hour pilot furnace, and it is used to project the optimal smelting conditions for the full-scale 100 tons per hour Isasmelt furnace.     

Metal loss to slag: Part II. oxidic dissolution of nickel in fayalite slag and thermodynamics of continuous converting of nickel-copper matte

FeO-Fe₂O₃-SiO₂ slags were equilibrated in pure nickel crucibles under a CO-CO₂ atmosphere. The Fe/SiO₂ ratios in the slag were fixed at 1.51 and 1.97 at temperatures of 1200 and 1300°C. The CO₂/CO ratios were varied up to values corresponding to magnetite saturation. On the basis of solubility data obtained, a computer model was developed to predict the solubilities of nickel and copper in slag during the continuous converting of nickel-copper matte. These are given as a function of five parameters: temperature, iron content and Cu/Ni ratio in the matte, partial pressure of SO₂ in the gas phase, and magnetite activity in the slag. The model is helpful in comprehending converting reactions and of practical applicability in optimizing the conventional as well as continuous converting processes. Noranda Research Centre, Pointe Claire, Quebec.     

富氧底吹炼铅氧化熔炼元素分配热力学模拟

基于最小吉布斯自由能原理,模拟计算了铅精矿富氧底吹炼铅工艺氧化熔炼段的元素分配行为,并与半工业试验数据进行对比。在典型工业富氧底吹炼铅工艺参数条件下,重点考察了氧料比对Pb、Cu、As、Sb、Bi等元素分配行为的影响。计算结果表明,Pb、Cu、As、Sb和Bi在渣相中的分配率随氧料比的提高而增加。当氧料比为175kg/t时,Pb、Cu、Sb和Bi在金属相、渣相和气相中的分配比例基本符合半工业试验统计数据,但As计算结果与半工业数据存在一定偏差,原因可能是由于缺乏精确的活度系数。     

重金属加压浸出技术现状及展望

加压浸出作为一种高效的湿法冶金手段,迄今为止已在铜、锌、镍、钴等重金属行业,以及铀、钼、黄金和铂族等稀贵金属行业得到推广应用。总结了重有色金属铜、铅、锌、镍、钴行业和冶炼过程副产物加压浸出技术研究和工业化应用现状,包括复杂硫化铜矿、铜钴矿、硫化砷渣、黑铜泥、铜阳极泥、白烟尘和铜钴冶炼转炉渣加压浸出,复杂硫化锌矿、锌浸出渣、赤铁矿除铁、镓锗富集物、铜渣等加压浸出,硫化镍矿、红土镍矿、白合金、铜渣和钴冰铜加压浸出等。最后,对加压浸出技术在重有色金属行业未来发展趋势进行了展望。     

Thermochemical nature of minor elements in copper smelting mattes

Equilibrium distribution measurements of As, Sb, and Bi between molten copper and white metal were conducted at 1473 K using a static system. The results of this investigation have been used to evaluate the activity of those elements in white metal, and the results are compared to other data in the literature. An empirical model is presented and used to correlate the activity of As and Sb in matte as a function of the number of vacant electronegative sites in the matte, VS, and a parameter, ψ, used to represent the strength of the bond between Fe and the minor element in comparison to that which occurs with Cu. The activity coefficients of As and Sb in matte were found to be represented by the following equations:

渣中铁硅比对铜熔炼中伴生元素行为的影响

利用已开发的铜冶炼过程的计算机模型，模拟研究了渣中铁硅比对伴生元素Ni、Co、Sn、Ph、Zn、As、Sb和Bi在铜冶炼体系中分配行为的影响。研究表明：提高中铁硅比，不利于伴生元素在渣中的脱除。     

铜闪速熔炼影响规律的神经网络分析

基于已建立的神经网络模型,研究了富化率、吨矿氧量、熔剂率以及铜精矿主要成分对铜闪速熔炼过程的影响。结果表明:富化率的增大会使铜锍品位降低、铜锍温度升高,而对渣含Fe/SiO2影响不大;吨矿氧量的增加会使铜锍品位、铜锍温度及渣含Fe/SiO2都升高;熔剂率的增加会使渣含Fe/SiO2明显下降;精矿中Cu含量的增大会使铜锍品位升高,铜锍温度稍微降低;而Fe的影响与Cu相反;S/Cu一般控制在1.0±0.2,自热熔炼应控制在1.34以上。     

Transport phenomena in electric smelting of nickel matte: Part II. Mathematical modeling

A three-dimensional mathematical model was developed to simulate the distributions of electrical potential, heat release, temperature, and velocity in the slag and matte in a six-in-line 36 MVA capacity furnace for smelting nickel calcine. From Part I of this series, it was found that there was a substantial electrical potential drop at the electrode surface, likely due to arcing through evolved carbon monoxide. The incorporation of this phenomenon into the model permitted accurate calculation of the current, power, and temperature distributions in the slag and matte. The slag was found to be thermally homogenized due to the evolved gas, and to a lesser extent by natural convection. In contrast, the matte was thermally stratified; this finding was attributed to poor momentum transfer across the slag/matte interface. Ninety percent of the electrical energy was used in smelting reactions in the calcine; to simulate the heat transfer from the slag to the calcine, a heat transfer coefficient was deduced from plant data. The implications of these findings for stable furnace operation are discussed.     

辉锑矿富氧熔池熔炼的工艺研究

采用富氧顶吹装置模拟辉锑矿挥发熔池熔炼的行为,考察了氧气系数、初始渣Fe/SiO_2、CaO含量对熔炼渣中锑含量的影响。在氧气系数为1.04、初始渣Fe/SiO_2=0.94、CaO 15%的最优条件下,熔炼后渣含锑为1.8%。采用SEM-EDS对渣中锑的物相及分布行为进行了表征,发现熔渣中锑以微小的金属粒子形式存在。通过加入一定量的锑锍作为捕集剂,并在高温下对锑渣进行贫化,使渣中的锑含量由沉降前的2.36%降低至0.86%。辉锑矿可以采用富氧挥发熔池熔炼—熔炼渣高温贫化工艺进行处理。