Copper Loss In Slag Research Articles

Flash Smelting Settler Design Modifications to Reduce Copper Losses Using Numerical Methods

A mathematical modeling approach was used to test different design modifications in a flash smelting settler to reduce the copper losses in slag, which is economically disadvantageous for copper processing using the pyrometallurgical route. The main purpose of this study was to find ways to reduce copper losses in slag by improving the settling and coalescence of copper matte droplets, in particular, the smallest droplet sizes of ≤100 µm. These improvements inside the flash smelting (FS) settler were targeted through different settler design modifications. Three different design schemes were tested using the commercial computational fluid dynamics (CFD) software, Ansys Fluent. These settler design modification schemes included the impact of various baffle types, positioning, the height inside the settler, and settler bottom inclinations. Simulations were carried out with and without coalescence and the results were compared with normal settler design. The results revealed that the settling phenomenon and coalescence efficiency were improved significantly with these design modifications. It was concluded that a single baffle design was optimal for reducing copper losses and increasing coalescence efficiency instead of using multiple baffle arrangements. The top-mounted baffle outperformed the bottom-mounted baffle and inclined settler design.

Experimental Study on the Phase Equilibrium of Copper Matte and Silica-Saturated FeOx-SiO2-Based Slags in Pyrometallurgical WEEE Processing

The effects of the amphoteric and basic oxides alumina and lime on the phase equilibria of copper matte and silica-saturated slags were investigated at 1300 °C and P_{{{text{SO}}_{ 2} }} = 0.1 atm in a controlled CO-CO2-SO2-Ar gas atmosphere using a high-temperature isothermal equilibration technique followed by rapid quenching. The equilibrium phase compositions were obtained by Electron Probe X-ray Microanalysis. The relationship between the copper concentration in matte and the oxygen partial pressure, iron, and sulfur in matte was quantified. The pure iron-silicate slag exhibited the highest copper loss in slag, although the addition of alumina and lime decreased its value by approximately a quarter and a half, respectively, at a matte grade of 65 wt pct Cu. In contrast, copper and sulfur were highly distributed in the matte phase, and their deportment to the matte was favored by addition of alumina and lime.

Recovery of valuable metals from spent lithium ion batteries by smelting reduction process based on FeO–SiO2–Al2O3 slag system

A novel smelting reduction process based on FeO–SiO2–Al2O3 slag system for spent lithium ion batteries with Al cans was developed, while using copper slag as the only slag former. The feasibility of the process and the mechanism of copper loss in slag were investigated. 98.83% Co, 98.39% Ni and 93.57% Cu were recovered under the optimum conditions of slag former/battery mass ratio of 4.0:1, smelting temperature of 1723 K, and smelting mass ratio of time of 30 min. The FeO–SiO2–Al2O3 slag system for the smelting process is appropriate under the conditions of m(FeO):m(SiO2)=0.58:1–1.03:1, and 17.19%–21.52% Al2O3 content. The obtained alloy was mainly composed of Fe–Co–Cu–Ni solid solution including small amounts of matte. The obtained slag mainly consisted of fayalite and hercynite. Meanwhile, the mechanism of copper loss is the mechanical entrainment from strip-like fayalite particles in the main form of copper sulfide and metallic copper.

Study of the Effect of Spinel Composition on Metallic Copper Losses in Slags

In both primary and secondary copper production, copper losses in slags are a decisive factor confining the process efficiency. An important cause for mechanical entrainment of metal droplets in slags is their attachment to solid spinel particles present in the slag phase, hindering sedimentation. To further optimize the production process, it is important to gain insights in the fundamental mechanisms governing this attachment. In the present study, the influence of the spinel composition on the attachment of copper droplets is investigated. First, the attachment is studied in an industrially relevant synthetic PbO–CaO–SiO2–Cu2O–Al2O3–FeO–ZnO slag system. Second, the wetting of copper on two spinel substrates (ZnFe2O4 and MgAl2O4) has been studied in the absence of a slag system, by sessile-drop experiments. Based on the results of both types of experiments, a clear influence of the spinel composition on the sticking behavior of copper droplets is noted. These observations might be transferred to industrial processes to adapt processing parameters to diminish copper losses in industrial slags.

Co-treatment of waste smelting slags and gypsum wastes via reductive-sulfurizing smelting for valuable metals recovery

In this work, a new innovative slag cleaning technique was presented to economically and environmentally friendly recover valuable metals from cobalt-bearing copper smelter slag. CaSO4-rich gypsum waste was used as sulfurizing agent to efficiently and selectively sulfurize and recover valuable metals lost in the slag at reductive atmosphere. Thermodynamic analysis and laboratory experiments were carried out to determine the feasibility and reliability of this new process. The optimum slag cleaning conditions were determined as follow: reductive agent coke dosage of 12%, 20% CaSO4 addition of smelter slag weight, smelting at 1350°C for 3h. Under the optimum conditions, 92.04% Cu and 95.62% Co were enriched and recovered in copper-cobalt matte. The contents of Cu and Co in cleaned slag dropped to levels lower than 0.2% and 0.045% respectively. Selectivity recovery ratio of Cu/Fe and Co/Fe can reach 6.00 and 6.24 respectively. Calcium-rich and iron-poor cleaned slag property was more beneficial for minimizing cobalt and copper losses in slag. The products were characterized by XRD and SEM-EDS techniques. The Cu-Co matte primarily comprised iron sulphide (FeS), geerite (Cu8S5), iron cobalt sulphide (Fe0.92Co0.08S), independent cobalt sulphide (CoS) and some metallic Cu, Co and Fe. Copper and cobalt in resultant matte attended to appear separately in different mineral phases. The cleaned slag mainly contained fayalite (Fe2SiO4), hedenbergite (CaFeSi2O6) and magnetite (Fe3O4).

Furnace structure analysis for copper flash continuous smelting based on numerical simulation

According to the innate characteristic of four types of furnace, the copper flash continuous smelting (CFCS) furnace can be considered a synthetic reactor of two relatively independent processes: flash matte smelting process (FMSP) and copper continuous converting process (CCCP). Then, the CFCS thermodynamic model was proposed by establishing the multi-phase equilibrium model of FMSP and the local-equilibrium model of CCCP, respectively, and by combining them through the smelting intermediates. Subsequently, the influences of the furnace structures were investigated using the model on the formation of blister copper, the Fe3O4 behavior, the copper loss in slag and the copper recovery rate. The results show that the type D furnace, with double flues and a slag partition wall, is an ideal CFCS reactor compared with the other three types furnaces. For CFCS, it is effective to design a partition wall in the furnace to make FMSP and CCCP perform in two relatively independent zones, respectively, and to make smelting gas and converting gas discharge from respective flues.

Minimization of Copper Losses in Copper Smelting Slag During Electric Furnace Treatment

In the quest to achieve the highest metal recovery during the smelting of copper concentrates, this study has evaluated the minimum level of soluble copper in iron-silicate slags. The experimental work was performed under slag-cleaning conditions for different levels of Fe in the matte and for a range of Fe/SiO2 ratios in the slag. All experiments were carried out under conditions where three phases were present (copper–matte–slag), which is the condition typically prevailing in many slag-cleaning electric furnaces. The %Fe in the electric furnace matte was varied between 0.5 wt.% and 11 wt.%, and two different Fe/SiO2 ratios in the slag were used (targeted values were 1.4 and 1.6). All experiments were performed at 1200°C. From thermodynamic considerations, from industrial experience, and from the results obtained in this study, the minimum soluble copper content in the electric furnace slag is expected to be near 0.55 wt.% Cu. This level does not account for a portion of the copper present as mechanically entrained matte/metal droplets. Taking this into account, the current authors believe an overall copper level in discard slag between 0.7 wt.% and 0.8 wt.% can be obtained with optimal operating conditions. For these conditions, the copper losses in the slag are roughly 75% as dissolved copper and 25% as entrained matte and copper. Such conditions include operating the electric furnace at metallic copper saturation, maintaining the %Fe in the electric furnace matte between 6 wt.% and 9 wt.%, not exceeding a slag temperature of 1250°C, and controlling the Fe/SiO2 ratio in the smelting furnace slag at ≤1.5. In addition, magnetite reduction needs to be performed efficiently during the slag-cleaning cycle so as to maintain a total magnetite content of ≤7 wt.% in the discard slag. The authors further consider that under exceptionally well-controlled conditions, a copper content in electric furnace discard slag between 0.55 wt.% and 0.7 wt.% can be obtained, by minimizing entrained matte and copper solubility in the discard slag.

Physical chemistry of copper smelting slags and copper losses at the Paipote smelterPart 1 – Thermodynamic modelling

Thermodynamic modelling was used in conjunction with the results of a sampling campaign to investigate the liquidus temperature and the copper losses in slag from the Teniente converter (TC) and from the slag cleaning electrical furnace (EF) at the Paipote smelter in Chile. The present paper (Part 1) describes the smelter flow sheet and discusses the results of thermodynamic calculations. The impact of process parameters such as the Fe/SiO2 ratio, the minor oxide levels in slag (CaO, Al2O3, MgO and ZnO), the sulphur dioxide partial pressure p(SO2), temperature and matte composition were examined with respect to the slag liquidus and copper level in the slags. The operating window of the Paipote TC to produce good slag quality correspond to a vessel temperature between 1200 and 1250°C, and an Fe/SiO2 ratio in slag between 1·5 and 1·8 when the iron content of the matte is in the range of 3–6 wt-%Fe (or 76·5–73·2 wt-%Cu). Under these conditions, the TC slag (average total copper in slag ∼6 wt-%Cu) contains less than 1 wt-%Cu as soluble copper with approximately 90% of total copper in the slag is entrained matte; it is noted that 0–10 wt-% solid magnetite is in suspension in the slag. As regards the EF, over the nominal temperature range from 1200 and 1270°C, the EF slag is fully molten over a wide range of Fe/SiO2 ratios for slag containing the present level of minor oxides. An operating temperature of about 1225°C and a Fe/SiO2 ratio in the range 1·4–1·8 are considered good conditions for optimum EF performance. The EF slag typically averages 0·82 wt-%Cu and it was estimated that under present conditions, about 50% of this copper was as soluble copper with the balance as entrained matte.La modélisation thermodynamique a été utilisée en conjonction avec les résultats d’une campagne d’échantillonnage pour examiner la température de liquidus et les pertes en cuivre dans le laitier du convertisseur de Teniente (TC) et du four électrique (EF) de nettoyage du laitier de la fonderie de Paipote au Chili. Le présent article (1iere Partie) décrit le schéma du procédé de la fonderie et discute les résultats des calculs thermodynamiques. On a examiné l’impact des paramètres du procédé, comme le rapport Fe/SiO2 dans le laitier, le niveau de CaO, Al2O3, MgO et ZnO dans le laitier, la pression partielle du dioxyde de soufre p(SO2), la température et la composition de la matte, sur le líquidus du laitier et sur le niveau de cuivre soluble dans le laitier. La fenêtre d’opération du TC de Paipote permettant de produire une bonne qualité de laitier correspond à une température entre 1200 et 1250C et à un rapport Fe/SiO2 dans le laitier entre 1·5–1·8 lorsque la teneur en fer de la matte est dans la gamme de 3 à 6% en poids (ou 76·5 à 73·2%Cu). Sous ces conditions, le laitier du TC contenant un cuivre moyen total d’environ 6% contient moins que 1% en poids de Cu sous forme de cuivre soluble. Ce rapport permet de déduire qu’approximativement 90% du cuivre total dans le laitier est sous forme de matte entraînée. On note également qu’entre 0 et 10% en poids de magnétite solide est en suspension dans le laitier, dans les conditions normales d’opération. En ce qui concerne le EF, le laitier est complètement fondu sur une large gamme de rapports de Fe/SiO2 pour une température comprise entre 1200 à 1270°C en considérant les niveaux actuels en CaO, Al2O3, MgO et ZnO dans le laitier. Une température de fonctionnement d’environ 1225C et un rapport Fe/SiO2 dans une gamme de 1·4 à 1·8 sont considérés comme des bonnes conditions pour le rendement optimal du EF. Le laitier du EF contient typiquement une moyenne de 0·82% Cu et l’on a estimé que sous les conditions présentes, environ 50% de ce cuivre se trouvait sous la forme de cuivre soluble, le reste étant sous la forme de matte entraînée.

Copper losses to slags obtained from the El Teniente process

The smelting and converting El Teniente process for copper concentrates as well as slag cleaning furnace technologies to treat slags coming out from the El Teniente furnaces are widely applied today in Chile and around the world. Several industrial applications of this process have shown their ability to treat copper concentrates in a wide range of chemical and mineralogical compositions. Main operational parameters determining performance of the process are: oxygen enriched air flow rate; degree of oxygen enrichment; moisture content of the solid materials processed; molten material levels inside the vessel; frequency of molten materials tapping; bath temperature; and copper losses in slags. In this work, the copper losses in the slags from the El Teniente pyrometallurgical process are predicted by calculation from thermodynamic data and compared with those determined by microscopic examination and slag industrial data. Results obtained show that the main part of copper losses in the slag from the El Teniente furnace are mechanically entrapped or floated unsettled droplets of the co-existing matte phase. Conversely, the very low copper losses in the slag from the slag cleaning furnace are limited by the physicochemical form.

Copper in solidified copper smelter slags

An appreciable amount of copper is slagged in high‐grade matte smelting and converting. The major part of copper lost in slag is recovered through slag‐cleaning operations. Copper losses in slag are of two main types: copper is either dissolved in molten slag as cuprous oxide (or as sulphide) or forms a mechanical dispersion in slag. For slag cleaning by froth flotation, mineralogy and morphology of solidified slag as well as chemical composition of copper‐bearing phases are of great interest. These phenomena are reviewed and discussed in this paper.

Kinetics of Reduction of Copper Oxide from Liquid Slag Using Carbon

Recent trends in oxidative continuous smelting of copper concentrates are leading to higher copper loss in slag (up to 6%) mostly in the form of copper oxide. Reduction of copper oxide from slag is further carried out in slag cleaning furnace with carbon as reductant. In the present study, reduction of copper oxide from a liquid slag by carbon was investigated. The experiments were carried out in a resistance heating furnace using a graphite lined alumina crucible. The influence of various parameters such as temperature, initial CuO 0 . 5 content in the slag, and stirring of the melt by argon, on the reduction kinetics of CuO 0 . 5 was studied. Based on the results obtained from this investigation the probable rate controlling mechanism was proposed. Results suggest that the reduction reaction was first order with respect to the concentration of CuO 0 . 5 and was controlled by chemical reaction at the slag/graphite interface. Activation energy for the reduction of CuO 0 . 5 by carbon was estimated to be 188.4 kJ/mol, which is comparable with the activation energy of the catalyzed Boudouard reaction.

The Copper Losses in the Slags From the El Teniente Process

The current El Teniente Pyrometallurgical Process for copper concentrate was commissioned at Caletones Smelter during the period 1988 - 1991 following an intensive research and development program that led to several improvements to the original process developed during the seventies. The Caletones Smelter production capacity is 370,000 tons of cast copper annually related to a concentrate smelting capacity of 1,250,000 tons per year.Several industrial applications of the process, in Chile and abroad, have shown its capability to treat copper concentrates in a wide range of chemical and mineralogical compositions. The main operational parameters that determine the performance of the process are oxygen enriched air flow rate, degree of oxygen enrichment, moisture content of the solid materials processed, molten material levels inside the vessel, frequency of molten materials tapping, bath temperature and copper losses in slags. The copper losses in the slags from the El Teniente Pyrometallurgical Process, predicted by calculation from thermodynamic data, have been compared with those determined by microscopic examination and quantitative electron microprobe analysis of the slag samples and by flotation tests of finely ground slag.Au cours de la periode 1988-1991, on a mis en service a la fonderie Caletones le procede pyrometallurgique actuel El Teniente pour le concentre de cuivre, suite a un programme intensif de R & D qui a conduit a plusieurs ameliorations du procede original developpe dans les annees 70’s. La capacite de production de la fonderie Caletones est de 370,000 t de cuivre coule annuellement, en relation avec une capacite de fonte de concentre de 1,250,000 t par année.Plusieurs applications industrielles du procede, au Chili et a l’etranger, ont montre sa capacite a traiter des concentres de cuivre couvrant une grande gamme de compositions chimiques et mineralogiques. Les principaux parametres operationnels, qui determinent la performance du procede, incluent le taux d’ecoulement d’air enrichi a l’oxygene, le degre d’enrichissement en oxygene, le contenu en humidite des materiaux solides traites, le niveau de materiel fondu a l’interieur du reacteur, la frequence de recolte des materiaux fondus, la temperature du bain et la perte de cuivre dans les scories. On a compare les pertes de cuivre dans les scories par le procede pyrometallurgique El Teniente, predites par les calculs a partir des donnees thermodynamiques, avec celles determinees par examen microscopique et par analyse quantitative par microsonde electronique des echantillons de scories ainsi que par des tests de flottation de scories pulverisees finement.

Copper losses and thermodynamic considerations in copper smelting

A relationship between copper in slag and copper in matte during copper sulfide smelting has been derived using industrial data from 42 plants employing blast furnaces, reverberatory furnaces, flash furnaces, and Mitsubishi smelting furnaces together with the available thermodynamic equilibrium data for Cu-Fe-S-O, FeO-SiO2, and Cu-Fe-S systems and laboratory slag-matte equilibrium information. A copper smelting diagram showing oxygen potential; sulfur potential; and copper, magnetite, and sulfur contents in slag during the smelting of different grades of copper mattes is developed for mattes containing less than 70 pct copper. The data presented can be used to determine the entrained copper losses in slag. Further, by combining the calculated value of the entrained matte with the corresponding plant data for the sulfur content of the slag, it is possible to derive the dissolved sulfur content of the slag. These calculated values were in excellent agreement with the experimentally determined sulfide capacity of fayalite slags. It is shown that there is no need to assume the presence of dissolved copper sulfide species in industrial slags. The existing equilibrium data that relate the copper content of slags to oxygen potential adequately describe the copper losses in industrial slags.

玉野製錬所における銅製錬

Tamano Smelter was constructed as the first copper smglter of Hibi Kyodo Smelting Co., Ltd. whichwasajoint venture of three Japanese pnmary copper producers; MITSUI Mining & Smelting Co., Ltd., NITTETSU Mining Co., Ltd. and FURUKAWA Co., Ltd.The Smelter started operations in January, 1972, and has the capacity now to produce 8500 tonnes of cathode copper per month. Though matte smelting was based on the flash smelting process of Outokumpu Oy., electrodes were inserted in the settler, which made it unnecessary to provide an external slag cleaning furnace. Copper loss in slag is less than 0.6wt% Cu while copper in matte is 54%. Moreover, the adoption of water jacketed steel plate uptake could avoid the dust trouble through a waste heat boiler.Matte is treated in one of two hot converters. Converter off-gases are led to a gas cleaning section of an acid plant where flash furnace gas is combined with them. Nearly all sulfur dioxide in these gases are recovered as 98% sulfuric acid.To aim at a non pollution smelter, off-gas and fugitive gas collecting systems were installed. Converter fugitive gases which are sent to a tall stack only during out of stack times in converter operations, are sucked to the uniquely developed collection systems. A desulfurization plant using the lime process was completed in 1976 to comply with strict regulations. By this more than 99.6% of sulfur is fixed at present.Blister from converters is treated in two refining furnaces. Old refining furnaces were replaced by larger ones with unit capacity of 330 tonnes in 1975, in order to increase the production capacity, to achive higher efficiency in the operation, and to reduce the cost. For the purpose of simplifying the operation and improving the anode quality, the casting process was throughly made automated and, as the result, high quality anodes suitable for high current density electrolysis have been produced.An oxygen plant is now under construction to achieve higher efficiency in the operation and to increase the production capacity. Coal milling plant is also to be completed to cut fuel cost.The refinery started operation with a monthly production capacity of 7, 000 tonnes of cathode copper. Feature of this refinery is the use of periodic current reversal with current density of 348A/m2. Developments of special cell bus bars and an automatic short circuit pair detector were useful for power saving. Present production capacity is 8500 tonnes per month.Purification of electrolyte is done by electrowinning, evaporation using a submerged combustion burner, and crystallization of nickel sulfate.Crude nickel sulfate and decopperized slimes are sent to Takehara refinery of Mitsui Mining & Smelting Co., Ltd. for further treatment.