Recovery of cobalt from converter slag of Chambishi Copper Smelter using reduction smelting process

The reduction smelting process for cobalt recovery from converter slag of the Chambishi Copper Smelter in Zambia was studied. The effects of reducing agent dosage, smelting temperature and time and the addition of slag modifiers （CaO and TiO2） were investigated. In addition, the depleted slag and cobalt-bearing alloy were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Under the determined conditions, 94.02% Co, 95.76% Cu and less than 18% Fe in the converter slag were recovered. It was found that the main phases of depleted slag were fayalite and hercynite; and the cobalt-bearing alloy mainly contained metallic copper, Fe-Co-Cu alloys and a small amount of sulfide.

φ-pH diagram of V-Ti-H_2O system during pressure acid leaching of converter slag containing vanadium and titanium

To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.

Comprehensive Utilization and Control Measures of Iron and Steel Slag

With the increase of steel production,the amount of steel slag piled up is on the rise.The article analyzes the current situation of blast furnace slag utilization,elaborates on the current treatment technology of blast furnace slag,and points out that in the future,the utilization of blast furnace slag will develop towards the direction of developing high value-added products,and the sensible heat recovery rate of blast furnace slag is expected to increase.Analyze the current application status and treatment process of converter slag.The comprehensive treat-ment technology of converter slag is limited by multiple factors,and it is proposed to control converter slag from the production source through"slag recycling".

Chemical and mineralogical characterizations of a copper converter slag

A copper converter slag was examined chemically and mineralogically to determine its existing phases, in particular those containing Co and Cu. The slag consists predominantly of fayalite and magnetite, together with some glass, chalcocite, and metallic copper. Copper is entrapped in the slag mostly as chalcocite and metallic copper, as well as trace copper oxide. There was no indication of any independent Co mineral in the slag, but Co was found to be enriched in fayalite and megnetite as solid solution, although Co was detected in all the phases of the slag by SEM-EDX (scanning electron microscopy equipped with model EDAX-9100 energy dispersive spectrometer) and WDS (model WDX-2A X-ray wave-length dispersive spectrometer).

Hydrophobic-surface of copper from converter slag in the flotation system

The converter slag from a smeltery in Daye contains 2.01% copper.The floatability of copper has a significant influence on the flotation of converter slag.Flotation tests,contact angle tests and FTIR were conducted to assess the influences of pH and different flotation concentrators on its hydrophobic process,mechanism and flotation.The results show that since chemisorptions are formed on the surface,hydrophobicity of copper is highly enhanced by xanthate,butylamine dithiophosphate and Z-200.The hydrophobic-surface of copper becomes worse with low recovery in strong acid and alkali situation.When pH value is 10,butylamine dithiophosphate and butyl xanthate are used as the mixed-collector,the grade of copper is 40.01%and that of tailings is 0.37%.

Recovery of Copper and Cobalt from Converter Slag with a New Flotation Method Using H_(2）S

In this study,two different samples were obtained from Küre Copper factory.It was determined that the samples contain:the sample of K.C.F.(Küre Copper Factory),0.70%Cu and 0.5%Co.This sample was firstly grounded at-100 mesh dimension.Flotation was done according to previously obtained optimum flotation conditions.The flotation yield of Cu and Co in concentrate phase was found to be low by collective flotation.Even when the samples were grounded at-160 mesh,no change was observed in the flotation result.Especially,Co could not float under the flotation conditions of the non-sulfurized samples.There,a new flotation method was applied which was not applied until now.For this aim,the samples were firstly sulphurised under the steam of H2S+H2O.By this method,the amount of Cu and Co in the samples get rich.According to the obtained results,the optimum reactions for flotation and sulphurization were determined.In the first sulphurization conditions for the sample of K.C.F.,the yield of flotation for the Co and Co were found to be 98.27%and 68.07%,respectively.The results indicate that Cu can be floated at low yield in the original samples.On the other hand,Co cannot float under these conditions.

The study of microstructure and phosphorus distribution in converter slag

An efficient slagging is a key process to improve the dephosphorization ability in converter operation. The microstructure analyses can provide the information of phosphorus distribution in various mineral phases to feature completely the dephosphorization process.Two kinds of converter slags were investigated in this study, including conventional slag with high basicity and dephosphorization slag with low basicity.The characteristics of high basicity converter slag have been reported widely.However,the investigations on the low basicity slag properties for dephosphorization in converter are less discussed in steelmaking slag system.This study focused on the microstructure and phosphorus-containing phases in converter slag.The slag composition and mineral phase were examined by the usual XRF chemical analysis and EPMA,XRD studies.The results indicated that the phosphorus-containing phase in high basicity slag was the dicalcium silicate(2CaO·SiO_2 or C_2S) phase,while phosphorus in low basicity slag was incorporated in CaFeSiO_4 structure.

Design and experiment on concentration of phosphorus in factory converter slags

The phosphorus-concentrating phase in the converter slags was designed and simulated by synthetic converter slag.The distribution of phosphorus in factory converter slags was also analyzed by scanning electron microscope(SEM) and X-ray diffraction(XRD).Then factory converter slags were modified by addition of SiO_2 and heated to 1540℃and then cooled to room temperature.The results showed that the phosphorus in the factory converter slags was mostly distributed in two phases:dicalcium silicate (C_2S) and tricalcium silicate(C_3S) by formation of solid solution,and with a little in matrix.Whereas,in the synthetic slags with the basicity close to 3,phosphorus was almost concentrated in phase of C_2S(Pconcentrating phase) in which the contents of P_2O_5 reach to 7.74%.This lays a good foundation for grinding and separation of P- concentrating phase.

Chemical Corrosion Mechanisms of Magnesite-chrome Bricks by Converter Slag

The corrosion resistance of four kinds magnesitechrome bricks against converter salg was investigated by static crucible slag tests. The microstructures of the asdelivered and tested refractories were analyzed by means of SEM and EDS. The results showed that： Different magnesite-chrome bricks have different slag resistances. Generally, the slag resiantance sequence is as follows： rebounded fused magnesite-chrome brick 〉 semi-reboun- ded magnesite-chrome brick 〉 direct-bonded magnesitechrome brick 〉 silicate bonded magnesite-chrome brick. Slag reacts with the periclase of magnesite-chrome refractories, which results in the dissoving of periclase in fayalite slag. However, the complex spinels have superior slag resistance.

Leaching behavior and microstructure of phosphorus in converter slag

Converter slag is a by-product of the steelmaking process and contains a large amount of Ca,Fe,P and other elements.If the phosphorus in the converter slag can be effectively extracted,the resulting phosphorus can be used as a phosphate fertilizer.Phosphorus in converter slag is mainly enriched in 2CaO·SiO_(2)-3CaO·P_(2)O_(5)(C_(2)S-C_(3)P)solid solution and is easily dissolved in water.Therefore,acid leaching method was used to dissolve the solid solution to extract phosphorus in converter slag,so as to realize the recycling of phosphorus resources in converter slag.The leaching behavior of three actual converter slags from different steel mills in acid leaching solutions composed of citric acid,sodium hydroxide,hydrochloric acid and deionized water was studied by X-ray diffraction,scanning electron microscopy combined with energy dispersive spectrometry,Fourier transform infrared spectroscopy and Raman spectroscopy to reveal the change in object image structure as well as SiO_(4) and PO_(4) tetrahedron before and after acid leaching.The results show that only a small amount of phosphorus in converter slag with too low basicity is enriched in C_(2)S-C_(3)P solid solution,resulting in poor leaching effect.When the converter slag has a high basicity,the removal effect of phosphorus is 70.64%-81.88%.In addition,when the basicity of converter slag is roughly the same,the dephosphorization effect of slag with high FeO content is relatively poor.And acid leaching will cause depolymerization behavior of SiO_(4) and PO_(4) tetrahedron,so that the mole fraction of Q0(Si)(asymmetric stretching vibration of Si-O bond in SiO_(4) tetrahedron with bridge oxygen number of 0)and NBO/Si(non-bridging oxygen in silicate tetrahedra)will increase.Phosphate-containing solids can be obtained from the solution after acid leaching through static precipitation,and the solids have the potential to make phosphate fertilizers.

A review on vanadium extraction techniques from major vanadium-containing resources

The critical role of vanadium in metallurgy and the increasing commercialization of vanadium redox flow batteries have contributed to a rise in market demand for vanadium,emphasizing the need to ensure the sustainability of vanadium production.Converter vanadium slag and stone coal,generated during the smelting process of vanadium–titanium magnetite,serve as primary raw materials for vanadium extraction.This paper reviews the process mineralogy of converter vanadium slag and stone coal,encompassing the chemical and physical phase compositions of the raw materials and the state of vanadium occurrence.The aim is to establish a theoretical foundation for the mechanistic study of the vanadium extraction techniques and to provide a reference for the optimization of the process afterward.This paper systematically summarizes the current vanadium extraction technology from converter vanadium slag,covering roasting,direct leaching,sub-molten salt method,and the technology and research status of vanadium extraction from stone coal.Most importantly,it identifies key issues in the current vanadium extraction techniques and challenges faced in actual production,based on the analysis of the current vanadium extraction process and mechanism research.The forward feasibility and prospects for the development of vanadium extraction technology are outlined.

Process of Re-Resourcing of Converter Slag

The process of ＂re-resourcing of converter slag＂ was put forward based on the analysis of the existing steel slag treatment process.The converter slag obtained from Jinan steel plant was studied.After grinding,the slag contained 3.3% of iron particles,54.84% of magnetic part（wTFe=20%）,and 41.84% of non-magnetic part,which could be used for making cement directly.At a temperature below 1000 ℃,the non-magnetic Fe2O3 in the slag could be efficiently reduced to magnetic iron by pure H2 and CO.The slag after precise reduction had high degree of dispersion and did not get sintered,which provided an optimum condition for the separation of iron and impurities.To separate the slag and enrich the iron after reduction,the laboratory-scale device of magnetic separation was designed and made.The process of slag re-resourcing,which included magnetic sorting,precise reduction,magnetic separation,and removal of free calcium oxide（f-CaO）,was proposed to obtain iron-rich magnetic materials and cement adulterant materials.Through this process,33 kg iron particles,150 kg iron-rich material and 700 kg cement could be obtained in each ton slag.Besides,this process to recycle converter slag had a lower energy and material consumption and no pollutant emission.

Phosphorous Enrichment in Molten Adjusted Converter Slag: Part I Effect of Adjusting Technological Conditions

The effects of adjusting technological conditions on the phosphorous enrichment of adjusted converter slag were investigated. The results showed that the phosphorus could he effectively enriched to 2CaO · SiO2 and 2CaO · SiO2-3CaO· P2O5 solid solution （SS, namely phosphorus-rich phase） to be formed with the decreasing of basicity and cooling rate. Moreover, the morphology of the phosphorus-rich phase changed from granular for the original converter slag with higher basicity to the coexistence of granular shape and rod-like for the adjusted slag with lower basicity. P2 05 content in phosphorus-rich phase exceeded 30° while the hasicity was 1.3 at the cooling rate of 1.0 ℃/min.

A Novel Method of Recycling CO_2 for Slag Splashing in Converter

Converter off-gas, an important energy resource for steel industries, is one of the weak points in the recov ery and utilization of secondary energy resources. To improve the level of recycling converter off-gas in steel plants, a novel approach to the recycle of CO2 separated from converter off-gas or other off-gas for the green slag splashing technique was developed, and the CO2 equilibrium conversion ratio of the green CO2 slag splashing under different technological conditions was calculated by the program of enthalpy （H）, entropy （S）, and heat capacity （C）, i.e. HSC software. Furthermore, the experiments of CO2 injected into molten converter slag were carried out, and the influencing factors of the green slag splashing technique using CO2 were analyzed. The experimental results showed that the carbon content for smooth slag splashing using COs was about 4.0%.

Preparation of V_2O_5 from converter slag containing vanadium

Preparation of V2O5 from converter slag （CS） was investigated through roasting, leaching, extracting, and precipitating processes. The corresponding roles of the parameters during every procedure were analyzed in detail. （NH4）2SO4 and KHSO4 were used as fusing agents to transform compounds containing vanadium into soluble species. Mass ratio of （NH4）2SO4 to CS, mass ratio of KHSO4 to CS, and roasting temperature during the roasting process can significantly influence leaching rate of vanadium （LRV）. With H2SO4 as leaching agent, 99.2 % vanadium in CS can be leached out under the optimum leaching conditions, which mainly refer to liquid-to-solid ratio, H2SO4 concentration, leaching temperature, and leaching time. Extracting and back-extracting processes were introduced to purify the vanadium from the H2SO4 lixivium. Extracting rate of vanadium （ERV） greatly depends on iron powder concentration, pH, diisooctyl phosphate （P2O4） content, volume ratio of extractant to H2SO4 lixivium, and extracting time. By adding ammonium hydroxide, 94.0 % vanadium in back-extracting solution can be separated in the form of precipitates. The product from the roasted precipitate mainly consists of V2O5, the content of which is higher than 90.0 %.

Wetting and corrosion behavior between magnesia-carbon refractory and converter slags with different MgO contents

The influence of MgO content in slag on wetting and corrosion behavior between slag and MgO–C refractory was investigated.It can be known from the high-temperature wetting experiment that as the MgO content in the slag increases,the final contact angle between the slag and the MgO–C refractory gradually increases and the penetration depth of the slag into the refractory gradually decreases from 60.54μm(when the MgO content is 8%)to 28.11μm(when the MgO content is 12%).The CaO and SiO_(2)in the slag penetrate into the MgO–C refractory along the pores or surface cracks formed by carbon oxidation and react with MgO to generate a large amount of low-melting compound CaO–MgO–SiO_(2),which accelerates the corrosion of the refractory.As the MgO content in slag increases,the viscosity of the slag increases and the fluidity becomes worse,so that the mass transfer and diffusion of molecules or ions in the slag are weakened.In addition,the increase in MgO reduces the activity of FeO in the slag,which inhibits the interfacial chemical reaction,thereby weakening the wetting effect caused by the reaction.