Calcium Ferrite Slag Research Articles

Experimental Study and Thermodynamic Modelling of Equilibrium Distributions of Ni, Sn and Zn Between Slag and Black Copper for E-Scrap Recycling Applications

The recycling of waste electronic and electrical equipment (WEEE) and other secondary copper-containing materials through the "black copper" process relies on the selective distribution of metals among the gas, slag, and copper-rich liquid phase. This distribution is controlled by the effective oxidation/reduction potential, often expressed in terms of oxygen partial pressure. Separation of Ni and Sn presents a certain challenge in recycling though black copper route due to similar distribution coefficients over a wide range of oxygen partial pressures and possibly can be improved by optimizing the slag chemistry. This study provides experimental information on the distribution of Ni, Sn, and Zn between fayalite slags or calcium ferrite slags and copper-rich metal at 1250°C. The study uses high-temperature equilibration, quenching, and electron probe X-ray microanalysis (EPMA) techniques along with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for selected measurements of low concentrations. The oxygen partial pressure is controlled by the CO/CO2/Ar gas flow or by measuring the concentration of copper oxide in the slag. The effect of slag composition in terms of Fe/SiO2 or Fe/CaO ratio is studied by using different holding materials, such as silica (SiO2) ampoule, solid spinel (Fe3O4), wüstite (FeO), or dicalcium ferrite (Ca2Fe2O5). The experimental results are compared with literature data and used to optimize thermodynamic models for FactSage® software. The results demonstrate an opportunity for more effective separation of Ni and Sn using at oxidizing stage by using calcium ferrite slag promoting the formation of Sn4+.

Direct-to-blister smelting of copper concentrate based on a calcium ferrite slag system

The direct-to-blister smelting process realizes single furnace smelting from chalcocite to blister copper. This process saves the matte transport process, avoids multiple feeding in the smelting process, and has the advantages of high productivity, a short production process, and less SO2 pollution. By comparing with the phase diagram of iron silicate slag system, it shows that calcium ferrite slag system is more suitable for direct-to-blister smelting under the condition of high oxygen potential. In this study, high-grade copper concentrate was used as the raw material and direct-to-blister smelting experiments were carried out at the laboratory scale. The variation of copper recovery with CaO/Fe ratio, smelting temperature and sedimentation time was studied. The phase composition of slag and the loss of copper in slag were analyzed by X-ray diffraction (XRD) and scanning electron microscopy with an energy spectrometer (SEM-EDS). The results showed that by adjusting process parameters, the copper recovery can reach 90.15 wt.% and the blister copper grade is more than 98.50 wt.%. It provides a theoretical basis for the industrial application of calcium ferrite slag in direct-to-blister smelting.

Experimental Study of the Cu2O-FeOx-CaO System in Equilibrium With Metallic Copper at 1200 °C to 1300 °C and at P(O2)s = 10−5 to 10−7 Atm

The experimental study of the phase equilibria between calcium ferrite slag, metallic copper, spinel and/or dicalcium ferrite in the Cu2O-FeOx-CaO system has been carried out. Effects of temperature, oxygen partial pressure and Fe/CaO ratio on phase assemblages and compositions have been estimated. The advanced experimental technique including high-temperature equilibration on primary phase substrates, rapid quenching of the samples and quantitative measurements of equilibrated phase compositions using electron probe X-ray microanalysis has been applied. Spinel and dicalcium ferrite substrates have been specially designed to study phase equilibria at certain primary phase fields. Obtained experimental results have been compared with thermodynamic assessment of the Cu2O-FeOx-CaO system and available literature data.

Hot metal dephosphorization process using calcium ferrite slag without fluorite

ABSTRACT To solve environmental pollution caused by using fluorite slagging in the process of hot metal dephosphorization, this paper applies pre-melted calcium ferrite slag in the production of stainless steel powder injection and oxygen dephosphorization process to replace fluorite slagging. The results show that the average hot metal dephosphorization rate of calcium ferrite slagging is 88.06%, and its dephosphorization effect is better than that of fluorite slagging. The average hot metal dephosphorization rate of fluorite slagging is 77.7%. The slag melting temperature during calcium ferrite slagging is 1137°C on average, which is lower than the melting temperature of fluorite slagging, and the slag melting temperature during fluorite slagging is 1296°C on average. When calcium ferrite slagging, the slag melting condition is good during the blow process. According to the results of material cost estimation, it is completely feasible to substitute calcium ferrite slag for fluorite slagging.

Equilibrium Distributions of Pb, Bi, and Ag between Fayalite Slag and Copper-Rich Metal, Calcium Ferrite Slag and Copper-Rich Metal. Thermodynamic Assessment and Experimental Study at 1250 °C

Rising concentrations of impurities are expected at copper fire-refining stage due to lower availability of high-quality copper concentrates and due to increasing recycling of electronics and other secondary materials in primary copper smelting. Extra steps involving the removal of impurities from copper into the slag phase may provide a solution, but better understanding of thermochemistry is needed to evaluate the feasibility of changes in the process. In the present study, the distribution coefficients of Pb, Bi, and Ag between the fayalite or calcium ferrite slags and copper-based metal at 1250 °C were measured experimentally, using high-temperature equilibration, rapid quenching, and electron probe X-ray microanalysis (EPMA). The experiments were undertaken in a closed system using a modified substrate support technique, at relatively high oxidizing conditions typical for copper refining. The improved substrate technique enables the measurement of distributions coefficients for slags in equilibrium with solid spinel (Fe3O4) or dicalcium ferrite (Ca2Fe2O5). Experimental results of the present study and the literature data were analyzed together using thermodynamic modeling. As a result, thermodynamic database has been developed and used to predict the effects of oxygen partial pressure, wt% Cu in slag, temperature, and Fe/SiO2 and Fe/CaO in slags on the distribution coefficients of Pb, Bi, and Ag for the fayalite and calcium ferrite slag systems.

Study on the Occurrence of Phosphorus in the Slag of Hot Metal Dephosphorization for Stainless Steel Production

The dephosphorization process for producing stainless steel hot metal is divided into desiliconization period and dephosphorization period, and the ability to contain phosphorus in the slag is important for the dephosphorization effect of hot metal. The phase structure of the slags during the desiliconization and dephosphorization phases is studied by X‐ray diffraction (XRD), petrographic analysis, and scanning electron microscopy (SEM). The ability of slag to contain phosphorus during the slagging process of calcium ferrite is discussed. The final slag petrographic composition in the desiliconization stage is mainly free calcium oxide, dicalcium silicate and calcium phosphate solid solution, RO phase, calcium ferrite and metallic iron. The final slag petrographic composition in the dephosphorization phase is mainly composed of tricalcium silicate, dicalcium silicate and calcium phosphate solid solution, RO phase, dicalcium ferrite and free calcium oxide. Compared with the desiliconization phase, the crystal phase obtained during the dephosphorization phase is more stable. The terminal ferrous slag phosphorus in calcium ferrite slag system mainly exists in the form of 2CaO⋅SiO2−3CaO⋅P2O5 solid solution, whereas the content in other phases is small.

Effects of calcium ferrite slag on dephosphorization of hot metal during pretreatment in the BOF converter

A study was carried out to examine effects of calcium ferrite slag on dephosphorization of hot metal in the steelmaking BOF, with aims to pick up the speed of slag-forming, increase the slag dumping rate. Laboratory tests using a resistance furnace were performed to examine melting characteristics of calcium ferrite pellets, designed with the optimum ratio of iron oxides (total Fe 55%) to CaO of 3:1. The pellets were put in crucibles with furnace temperature held in the range of 1250–1350 °C for 10 min. The results showed that the melting of pellets was nearly completed at 1250°C and main mineral phases, detected by XRD, in the melted samples were CaO•Fe2O3 and 2CaO•Fe2O3. Based on results of the laboratory tests, experiments of full scale were performed using a converter of 120t, charging the hot metal with C 3.46–6.81%, Si 0.1–1.16%, Mn 0.12–0.30%, P 0.10–0.18%, S 0.017–0.13% and temperature of 1234–1430 °C. For the 13 test heats with 6 min of oxygen blowing, the rate of dephosphorization and phosphorus distribution ratio reached to 50–60% and 55.9, respectively, when the calcium ferrite pellets were charged. Averaged slag basicity 1.5–2.0, slag melting point 1280–1310℃, slag viscosity 0.5 pa.s were obtained for the BOF heats adding the calcium ferrite pellet, which ensured the slag foaming height controlled at 2.5–3.0 m during the early stages of the blow. Using above smelting process has increased the rate of slag dumping controlled at 50–70% and enhanced the rate of hot metal dephosphorization over 90%.

Thermodynamic assessment of the CaO–Cu2O–FeO–Fe2O3 system

Thermodynamic assessment of the CaO–Cu2O–FeO–Fe2O3 system is presented. Effects of temperature and P(O2) on the phase equilibria involving slag, solubility of copper and the Fe3+/Fe2+ ratio in slag have been modeled using available experimental data. Subsolidus phase equilibria and concentration of iron in liquid copper were evaluated as well. Different ways of representing phase equilibria in a quaternary system are illustrated. The slag model, [Ca2+, Cu+, Fe2+, Fe3+][O2−], was developed using the Modified Quasichemical Model (MQM). Liquid metal phase is modeled using the MQM, but as a separate solution, (CuI, FeII, OII). Spinel phase is modeled using the Compound Energy Formalism (CEF) and takes into account the solubility of copper and calcium. A thermodynamic database produced in the present study can be used for predictions in pyrometallurgical processing of copper involving calcium ferrite slags. The database is internally consistent with the binary and ternary sub-systems published earlier, as well as with higher-order systems. It works in the environment of FactSage, ChemApp, ChemSheet and SimuSage software packages.

Distribution of Bi Between Slags and Liquid Copper

The distribution of Bi between liquid copper and calcium ferrite slag containing 24 wt pct CaO, iron silicate slag with 25 wt pct SiO2, and calcium iron silicate slags was measured at 1573 K (1300 °C) under controlled CO-CO2 atmosphere. The experimental results showed that bismuth distribution is affected by the oxygen partial pressure, and bismuth is likely to exist in slags in the 2+ oxidation state, i.e., as BiO. The distribution ratio between calcium ferrite slag and metal was found to be close to that of iron silicate slag. The Bi distribution ratio was found to decrease with increasing SiO2 and Al2O3 content in slag. Increasing temperature was found to decrease the Bi distribution ratio between slag and metal. Using the measured equilibrium data on Bi content of the metal and slag and composition dependence of the activity of Bi in liquid copper, the activity and hence activity coefficient of BiO in the slag was calculated. The close value of activity coefficient of BiO in both slags at the same oxygen partial pressure indicates that the CaO-BiO and SiO2-BiO interactions are likely to be at the same level, or the FeOx-BiO interaction is the predominant interaction for BiO in the slag. Therefore at a constant FeOx content in the slag, the CaO-BiO and SiO2-BiO interactions doesn’t affect \( \gamma_{\text{BiO}} \) significantly.

Freeze lining formation in continuous converting calcium ferrite slags. II

The heat transfer properties of freeze linings generated in laboratory conditions, by industrial calcium ferrite slags from a continuous copper matte flash converting furnace, have been studied in situ in the molten slag using a water cooled probe technique. The measured heat conductivity of the freeze lining formed, estimated from direct measurements in steady state conditions, was 8·0±1·5 W m−1 K−1. The obtained heat conductivity of the freeze lining is 50–100% higher than that of the iron silicate slag freeze linings. The calcium ferrite slag forms a fully crystalline freeze lining. Various ferrites and metallic copper develop the observed high heat conductivity when copper precipitated from the slag during solidification fills the intergranular cavities of the ferrite crystals tightly in forming the freeze lining layer.On a étudié les propriétés de transfert de chaleur de revêtements de gel engendrés en laboratoire par des scories industrielles de ferrite de calcium, à partir d’un four éclair en continu de cémentation de matte de cuivre, dans la scorie fondue en utilisant la technique du capteur refroidi à l’eau. La conductibilité thermique mesurée du revêtement de gel formé, estimée par des mesures directes en conditions de régime permanent, était de 8·0±1·5 W m−1 K−1. La conductibilité thermique obtenue du revêtement de gel est de 50 à 100% plus élevée que celle des revêtements de gel de scorie de silicate de fer. La scorie de ferrite de calcium forme un revêtement de gel entièrement cristallin. Les différentes ferrites et le cuivre métallique développent la conductibilité thermique élevée observée lorsque le cuivre précipité à partir de la scorie pendant la solidification remplit hermétiquement les cavités intergranulaires des cristaux de ferrite dans la couche de revêtement de gel en formation.

Freeze lining formation in continuous converting calcium ferrite slags. I

The initial freeze-lining growth rate in calcium ferrite slags at copper saturation is high and comparable to iron silicate slags. The entire freeze-lining layer is crystalline, from the cold end to its hot-face in contact with the molten slag. Industrial copper converting slags from a continuous flash converting furnace, processing solid high-grade matte to blister copper, generate a thin calcium sulphate bonding layer against the water-cooled metal surface during the very first minutes of the slag-to-cooling element contact. The rare solidification behaviour was observed using the water-cooled probe technique in rotating MgO crucibles, at slag temperatures of 1325°C when liquidus temperature of the flash converting slag was estimated to locate at about 1245°C. The body of the freeze lining is mostly composed of magnetite, various mixed calcium–copper ferrites and delafossite embedded in an intergranular phase of metallic copper and some copper oxide. The arsenic oxides dissolved in the slag are precipitated as solid calcium arsenates in the freeze lining.La vitesse initiale de croissance du revêtement de gel des scories de ferrite de calcium saturées en cuivre est élevée et comparable à celle des scories de silicate de fer. Toute la couche du revêtement de gel est cristalline, de l’extrémité froide jusqu’à sa face chaude en contact avec la scorie fondue. Les scories industrielles de cémentation de cuivre d’un four éclair de cémentation en continu, transformant une matte solide de haute qualité en un cuivre ampoulé, engendrent une mince couche de liaison de sulphate de calcium contre la surface de métal refroidie à l’eau lors des toutes premières minutes du contact de la scorie avec l’élément de refroidissement. On a observé ce comportement rare de solidification en utilisant la technique de la sonde refroidie à l’eau dans des creusets de MgO en rotation. La température de la scorie était de 1325°C alors que la température de liquidus de la scorie de cémentation éclair était estimée à environ 1245°C. Le corps du revêtement de gel est composé principalement de magnétite, de diverses ferrites mélangées de calcium et cuivre et de délafossite, qui sont incluses dans une phase intergranulaire de cuivre métallique et d’un peu d’oxyde de cuivre. Les oxydes d’arsenic dissous dans la scorie sont précipités dans le revêtement de gel sous forme d’arséniates solides de calcium.

Investigation of the Freeze-Lining Formed in an Industrial Copper Converting Calcium Ferrite Slag

Pyrometallurgical coppermaking processes are operated under intensive reaction conditions; high process temperatures and vigorous bath agitation is used to increase the kinetics of reactions and to achieve high smelter throughput. Slag freeze-lining reactor wall protection is a widely used technology in coppermaking processes, such as flash smelting and converting reactors. Freeze-linings mitigate and resist the effects of thermal and chemical attack by aggressive slags. In this laboratory-based study, a water-cooled probe “cold finger” technique has been used to investigate freeze-lining formation with calcium ferrite slags in equilibrium with metallic copper; the slag composition reflects that used in the industrial copper flash converting furnace of Rio Tinto—Kennecott Utah Copper. The effects of probe immersion times on the thickness and microstructures in the freeze-lining deposits have been investigated. A range of complex oxide solutions and copper-containing phases have been found in the deposits. The phase assemblages formed from the industrial calcium ferrite slag in the steady-state deposit are very complex and information on the phase equilibria of the multi-component systems with addition of minor elements may not be available. Subsolidus and subliquidus phase equilibria in the Cu-Ca-Fe-O system at metallic copper saturation along with interpolated temperature across the deposit, microstructural changes and compositional trends in the phases in the deposit have been used to understand the formation and characteristics of the phases in the steady-state freeze-lining. Also, it has been shown that under steady-state conditions a dense sealing layer consisting primarily of the spinel primary phase is formed at the deposit/liquid interface; however, the interface temperature is below the liquidus temperature. The findings of the study have potentially important implications for the operation of the converting furnace and the design of freeze linings in metallurgical systems.

Refractory Wear Mechanisms in the Nonferrous Metal Industry: Testing and Modeling Results

Nonferrous pyrometallurgical processes today operate at a high intensity requiring the best standards for the furnace refractory systems. From one plant to another, there is a range of process conditions such as temperature, slag chemistry, and feed types, and each of these parameters can influence refractory life. It is generally understood that process changes at plants can impact refractory life. The ability to test and understand refractory responses to a wide range of furnace operating conditions is therefore important. The RHI Technology Centre in Leoben, Austria is well equipped with laboratory and pilot plant facilities to evaluate refractory suitability over the range of conditions encountered in modern nonferrous pyrometallurgical systems. This article describes refractory testing at the RHI Technology Centre of the impact of two metallurgical slags on a number of different RHI test bricks. The slags were a fayalite slag and a calcium ferrite slag supplied by two smelter plants. High-temperature corrosion tests were carried out in a 250-mm-diameter induction furnace and a 165-mm-diameter short rotary kiln; each unit was lined with a number of refractory bricks and tested against attack by the particular slag. After testing, the refractory bricks were subjected to several laboratory tests to determine the extent of corrosion. Optimal refractory choices for the customers’ plants were developed based on the test results.

Distribution of bismuth between copper and FeOx–CaO–SiO2 slags under copper converting conditions

Ferrous calcium silicate (FCS) slags (FeOx–CaO–SiO2) have been proposed for use in continuous copper converting, because they attack refractories to a much lesser extent than calcium ferrite slag. However, their ability to absorb unwanted minor elements, such as bismuth, from the molten copper is less well known. Bismuth in copper anodes causes problems in the electrorefinery, while in finished copper products it adversely affects their mechanical properties. In this work, the distribution ratio of bismuth between copper and copper saturated FCS slags at 1300°C and an oxygen partial pressure of 10−7 MPa (10−6 atm) was determined by three-phase equilibration. Copper entrainment in slag caused difficulties during data analysis. It was found that the slag/metal bismuth distribution ratio decreased as the CaO content of the slag increased but was much less affected by the Fe/SiO2 (w/w) ratio. The inferred distribution ratios were projected onto the FeO–CaO–SiO2 phase diagram, as was the calculated value of the limiting activity coefficient of BiO1·5 in the slags. The strong similarity between the way in which both bismuth and copper distributions are affected by the slag composition, as well as theoretical considerations, show that BiO1·5 behaves in slags as a neutral metal oxide. As a result, bismuth removal from blister copper is maximized with FCS slags of low CaO content, the Fe/SiO2 (w/w) ratio being relatively unimportant.

Comparative analysis of slag systems Cu–Fe–O–SiO2 and Cu–Fe–O–CaO between 1100 and 1300°C

The present work reviews the state of the art of the quaternary systems Cu–Fe–O–SiO2 and Cu–Fe–O–CaO during copper pyrometallurgy processes, mainly, matte converting and blister copper fire refining. Both systems are particularly important to be considered in physicochemical understanding and modelling of pyrometallurgical processes today, then their knowledge become of particular interest for fundamental research and its applications to the copper industry. This analysis includes Cu losses, behaviour of impurities, and the interaction of MgO/Cr2O3 refractories with Cu2O both in fayalite and calcium ferrite slags.

ISACONVERT™—Continuous converting of nickel/PGM matte with calcium ferrite slag

The ISASMELT™ process is a top submerged lance (TSL) bath smelting technology which has been developed and optimized over the last 25 years. By the end of 2011, the total installed capacity of the ISASMELT technology will exceed 9,000,000 tonnes per year of feed materials in copper and lead smelters around the world. Commercial plants, operating in Belgium and Germany, are also batch converting copper materials in ISASMELT furnaces. This TSL technology is equally effective for continuous converting processes, whereupon it is called ISACONVERT™. Xstrata Technology (XT) has recently patented a new ISACONVERT process for the continuous converting of nickel/platinum group metal (PGM) mattes using the calcium ferrite slag system. This paper outlines the development of this new process and presents a conceptual flowsheet for how it can be integrated into an existing nickel/PGM smelter.

Comparison of Ferrous Calcium Silicate Slag and Calcium Ferrite Slag Interactions with Magnesia-Chrome Refractories

The cost of maintaining and eventually replacing refractories as a result of slag attack is a significant cost component in the copper industry. Converting matte to blister copper takes place in reactors lined with direct-bonded magnesia-chrome refractories, and several continuous converting operations use calcium ferrite slag. Unfortunately, the low viscosity of calcium ferrite slag makes it aggressive toward the refractories. Ferrous calcium silicate (FCS) slag has been proposed as a replacement; however, the effect of this slag on magnesia-chrome refractories has not been studied. In this work, the interactions between FCS slag and magnesia-chrome refractory at 1573 K (1300 °C) with an oxygen partial pressure of 10−6 atm were studied and compared with that experienced with calcium ferrite slag under the same conditions. Both slags penetrated the pores in the refractory and caused compositional change in the chromite spinel intergranular bonding phase through cation interdiffusion, which resulted in cracking and debonding of periclase grains. It was observed that the refractory was penetrated much more deeply by calcium ferrite slag than FCS slag because of the higher surface tension and lower viscosity of calcium ferrite slag. As a result, the refractory was attacked less by FCS slag than it was by calcium ferrite slag. It is concluded that the use of FCS slag in continuous copper converting is likely to extend refractory life.

酸化鉄含有スラグの粘度

Physical property of molten slag is important to clarify various reaction kinetics and to optimize the metallurgical processes at elevated temperature. In addition, viscosity is also important for understanding the microstructure of the slags. It is well known that most of the metallurgical slags contain the iron oxide. However, the behavior of the iron oxide in the molten slag is still not well understood. Iron oxide has two oxidation states (FeO and Fe2O3) and Fe2O3 is an amphoteric oxide. Therefore, the structural role of the iron oxide could be changed with several factors, such as melting temperature, basicity (chemical composition) and the oxygen partial pressure.In the present review paper, we outlined some of the highlight data of the viscosity and the structural information for iron oxide containing slags, which include calcium ferrite slag and iron oxide containing silicate slags.

Thermodynamics of Arsenic in FeOx-CaO-SiO2 Slags

The distribution of arsenic between calcium ferrite slag and liquid silver (wt pct As in slag/ wt pct As in liquid silver) with 22 wt pct CaO and between iron silicate slag with 24 wt pct SiO2 and calcium iron silicate slags was measured at 1573 K (1300 °C) under a controlled CO-CO2-Ar atmosphere. For the calcium ferrite slags, a broad range of oxygen partial pressure (10–11 to 0.21 atm) was covered, whereas for the silicate slags, the oxygen partial pressure was varied from 10–9 to 3.1 × 10–7 atm. The measured relations between the distribution ratio of As and the oxygen partial pressure indicates that the oxidation state of arsenic in these slags is predominantly As3+ or AsO1.5. The measured distribution ratio of arsenic between the calcium ferrite slag and the liquid silver was about an order of magnitude higher than that of the iron silicate slag. In addition, an increasing concentration of SiO2 in the calcium-ferrite-based melts resulted in decreases in the distribution of arsenic into the slag. Through the use of measured equilibrium data on the arsenic content of the metal and slag in conjunction with the composition dependent on the activity of arsenic in the metal, the activity of AsO1.5 in the slags was deduced. These activity data on AsO1.5 show a negative deviation from the ideal behavior in these slags.

Liquidus Temperatures in the “Cu2O”-FeO-Fe2O3-CaO-SiO2 System at Metallic Copper Saturation, at Fixed Oxygen Partial Pressures, and in Equilibrium with Spinel or Dicalcium Ferrite at 1200 °C and 1250 °C

Calcium ferrite slags, which are represented by the “Cu2O”-FeO-Fe2O3-CaO system at copper saturation, have been applied successfully to existing copper-converting processes. Because of the industrial importance of this system, the characterization of the effects of oxygen partial pressure and silica on the phase equilibria is necessary to improve the control of process parameters, which include fluxing and operating temperatures. In the current study, experimental methods, which use the equilibration/quenching/electron probe X-ray microanalysis (EPMA) techniques with primary phase substrate support, were subsequently developed to incorporate fixed oxygen partial pressure experiments. Experiments were carried out at 1200 °C and 1250 °C both with and without silica additions; both liquidus and solidus data were reported for the primary phase field of spinel and dicalcium ferrite between the oxygen partial pressures of 10−5.0 and 10−6.5 atm. The analyzed compositions of the liquid and solid phases are used to construct the phase diagram of the pseudoternary “Cu2O”-“Fe2O3”-CaO system in equilibrium with metallic copper at fixed oxygen partial pressures and with additions of silica. The maximum solubility of silica within the liquid slag phase, prior to dicalcium silicate precipitation, was measured at specific conditions. Two empirical equations used for the calculation of the copper oxide concentration in calcium ferrite slag are evaluated with the new experimental data defined in the current study.