| 1. |
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| 2. |
- Wang, Feng, et al.
(författare)
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Influence of Mn oxides on chemical state and leaching of chromium in EAF slag
- 2013
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Ingår i: Metalugia International. - 1582-2214. ; 18:8
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Tidskriftsartikel (refereegranskat)abstract
- In order to study the influences of Mn oxides on Cr in Electronic Arc Furnace (EAF) slag produced in a stainless steelmaking plant. To simulate EAF slags, two synthetic slags (slag A and slag B) were prepared through melting the two groups of reagent-grade compounds, respectively. The phase composition of samples was characterized by means of XRD. In addition, the slags with different particle size and some mixture were leached following Europe standard procedure. There was only one main compound MgCr2O4 found in spinel phase in slag A. While there were two compounds MgCr2O4 and Mn2AlO4 co-existed in spinel phase in slag B, in which Mn and Cr occupy the octahehral sites. For leaching tests, the influence of different factors, such as slag types, slag particles size, mixed manganese oxides, were studied in detail. The leaching result shows that MnO2 melted in slag is the most important factor for improving Cr leaching. But Mn oxides mixed in Mn-free slag have a little influence on Cr leaching.
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| 3. |
- Xue, Peng, et al.
(författare)
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Formation of MgFe2O4 and recycling of iron from modified BOF slag by magnetic separation
- 2017
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Ingår i: Kang T'Ieh / Iron and Steel. - : Chinese Society for Metals. - 0449-749X. ; 52:7, s. 104-110
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Tidskriftsartikel (refereegranskat)abstract
- Recycling of iron oxide from BOF slagshas always been a difficult issue in metallurgy. The core of this study was transforming the iron oxide into ferromagnetic phase MgFe2O4 by modifying industrial BOF slag appropriately first, and then recycling the iron resources by magnetic separation. The effect of basicity and calcination temperature on the formation of MgFe2O4 in synthetic BOF slags was investigated first, and then the industrial BOF slag was modified. Various experiments and analyses such as XRD, SEM-EDS, Factsage thermodynamic simulation and chemical analyses were conducted.The results show that the optimal basicity was 2, and the optimal calcination temperatures were 1 250 and 1 300℃. Moreover, MgFe2O4 was formed in modified BOF slag by mixing the industrial BOF slag with 6% SiO2 first, and then cooling the modified BOF slag from 1 400 to 1 270℃ at a rate of 1℃/min. After magnetic separation, the total Fe content in magnetic slag increased by 15.80%, to 37.00%, compared with that in the industrial BOF slag. This is better than the direct magnetic separation of iron oxide without any treatment
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| 4. |
- Xue, Peng, et al.
(författare)
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Modification of industrial BOF slag : Formation of MgFe2O4 and recycling of iron
- 2017
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Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 712, s. 640-648
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Tidskriftsartikel (refereegranskat)abstract
- Efficient recycling of iron oxide from industrial BOF (basic oxygen furnace) slags has always been an issue in metallurgy. In this study, a new method was developed for the efficient recycling of iron oxide: It was transformed into magnesioferrite spinel (MgFe2O4) by mixing the industrial BOF slag with 6.00% SiO2 first, and then the modified slag got cooled down from 1400 °C to 1270 °C at a rate of 1 °C/min. Finally, the Fe resources were recycled by magnetic separation. Various experiments and analyses such as XRD, SEM–EDS analyses, Factsage thermodynamic simulation, magnetization characterization, dry magnetic separation, and chemical analysis were carried out. The results show that the obtained MgFe2O4 has a high melting point (1716.76 °C in theory) and ferromagnetism (specific magnetic susceptibility of (8.03–206.84) × 10−5 m3/kg). Therefore, it could be separated from the weakly magnetic industrial BOF slag (specific magnetic susceptibility of (0.024–0.136) × 10−5 m3/kg). Furthermore, this new method could be applied to different BOF slags. The yield of MgFe2O4 increased to above 80% when the content of Fe2O3 was in the range 25.81–46.90%. After the modification and magnetic separation, the total Fe content increased by 15.80%, from 21.20% in the industrial BOF slag to 37.00% in the magnetic slag. This is better than the direct magnetic separation of iron oxide without any treatment. The magnetic slag could be reused as either a sintering or slag splashing material. The nonmagnetic slag can be used to produce high value-added building materials. Hence, this new method can be used to recycle the iron oxide from industrial BOF slags, achieving the sustainable development of the iron and steel industry.
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| 5. |
- Xue, Peng, et al.
(författare)
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Research on the sintering process and characteristics of belite sulphoaluminate cement produced by BOF slag
- 2016
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 122, s. 567-576
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Tidskriftsartikel (refereegranskat)abstract
- The sintering process of belite sulphoaluminate cement (CSA1) clinker is still not clear to date. Besides, there are few reports concerning producing CSA by recycled BOF slag. Therefore, the sintering process of CSA was investigated from this perspective and the results can be a reference for BOF slag disposal. Four kinds of CSA clinkers with different additions of BOF slag were sintered at 1300 °C for 30 min. The sintering process was traced by heating microscope and the characteristics were analyzed by XRD, SEM-EDS and TAM Air. The results showed that the sintering degree of CSA clinker could be predicted by analyzing its sintering process. Furthermore, BOF slag could improve the melting state of CSA clinkers due to its composition containing iron oxide, manganese oxide and magnesium oxide. However, expansion was detected when the temperature reached 420 °C, which was arose by combined factors, namely volatilization of CO2 decomposed from MgCO3 and the thermal expansion of raw materials itself. The rational ratios of C2S, C4A3View the MathML sourceS¯, C4AF in CSA clinker with 14% BOF slag as raw material stood at 50%, 30%, 20% and its early hydration behavior was better than that of ordinary Portland cement (OPC) at the initial 16 h.
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| 6. |
- Yang, Qixing, et al.
(författare)
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Dissolution behavior of fluorine from AOD slag after treatments for volume stabilization
- 2014
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Ingår i: Applied Mechanics and Materials. - 1660-9336 .- 1662-7482. ; 587-589, s. 849-855
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Tidskriftsartikel (refereegranskat)abstract
- AOD slag samples from steel works of Outokumpu Stainless Company were used to study F-dissolution relating to treatments for volume stabilization. Results from the slag tests and sample characterizations indicate that the slag re-melting with or without reduction and granulation with either water or gas have rather small effects on F leaching, as well as formation of different C2S polymorphs. The chemical composition and cooling condition are the two important parameters to control F leaching from slag samples. These two parameters should be combined together in an optimum way by the steel industry to treat slags for F-immobilization.
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| 7. |
- Yang, Qixing, et al.
(författare)
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Dissolution behavior of fluorine in AOD slag from the production of stainless steel after treatment for volume stabilization
- 2012
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Ingår i: Scanmet IV. - Luleå : MEFOS. - 9789163708596 ; , s. 517-526
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Konferensbidrag (refereegranskat)abstract
- The slag tapped from AOD (Argon Oxygen Decarburization) converter disintegrates, sometimes, during cooling. Slag fines from the disintegration are difficult to handle and to use as materials for construction purposes. In our early research work, AOD slag samples were modified by agents containing B or P elements. Different slag cooling procedures were also used, including cooling inside crucibles after re-melting and granulation by water and gas. By the modification, the slag samples gained the volume stability and mechanical properties required for its utilization as construction materials.Different types of stainless steel slag from Outokumpu Stainless Company have been used to manufacture environmentally sound and ce-marked construction products. Fluorine leaching from some of the AOD slag samples were investigated. In some other steelmaking processes, such as hot metal pretreatment, secondary steel refining and the production of high alloyed steels, fluorite can be charged as a slag forming agent, with some F and CaF2 existing in the slag. When these slags are reused as road construction or landfill materials, a potential fluorine contamination to the ground water may occur.The present research work is carried out regarding both the volume stability and F-immobilization for AOD slag samples. The studied slag samples consist of new ones from plant gas granulation tests and some old ones from our early studies. Compositions and cooling conditions are selected as main parameters for slag tests using laboratory equipment. Samples from the plant and laboratory slag tests are characterized by XRD, SEM and leaching with EN12457-2/3. Formations of mineral phases for F-immobilization in the slag samples are also predict using FACTSAGE program.Results from the present study indicate that the chemical composition and cooling condition for a slag are the two important parameters to control F leaching. These two parameters should be considered together in an optimum way to treat the slag for fluorine immobilization.It may be possible, based on the results obtained, to develop some environmental friendly and cost effective methods for the stainless steel industry to treat the AOD slag. Some slag products with high volume stability and minimum F-dissolution may thus be obtained to use as construction materials for saving valuable natural resources.
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| 8. |
- Yang, Qixing, et al.
(författare)
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Laboratory treatments of EAF slag for its use in construction
- 2013
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Ingår i: Advanced Materials Research. - 1022-6680 .- 1662-8985. ; 726-731, s. 2921-2930
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Tidskriftsartikel (refereegranskat)abstract
- Laboratory treatments of a plant EAF slag sample 71686 were conducted using stabilizers containing P2O5 and air granulation. The results show that it is necessary to add the stabilizers to increase contents of P2O5 from 0.39% to 0.7% for the slag stabilization. By a fast air cooling, most of the granules from the granulation are spherical, with a low internal porosity and dense structure. Content of Fe2O3 in the granules increased from 7.92% to 18.4% and FeO decreased from 14.3% to 7.8%, due to an oxidation during the slag granulation. Contents of metal elements, As, Cd, Cr, Mo, Pb, Ni and Zn, in the leachates from the treated slag samples were lower than the limit values for leaching from inert wastes pursuant to Directive 1999/31/EC. The slag samples after the treatments may then be regarded as environmentally friendly to use in construction
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| 9. |
- Yang, Qixing, et al.
(författare)
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Plant treatments of EAF slag for its use as construction materials
- 2013
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Ingår i: Advanced Materials Research. - 1022-6680 .- 1662-8985. ; 750-752, s. 1244-1253
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Tidskriftsartikel (refereegranskat)abstract
- At the steel plant of Höganäs Sweden AB, different steel grades were produced using an Electric Arc Furnaces (EAF). The slag tapped by the EAF often disintegrated during cooling. Slag fines from the disintegration are difficult to handle and to use as materials in construction. The plant tests of EAF slag treatments using stabilizer MCP-F of high P2O5 content were thus conducted, with 1st and 2nd campaign adding 10 and 20 kg MCP-F/ton slag, respectively. The MCP-F addition in slag pots and other test operations were carried out smoothly, without impacting the EAF steel production. Rates P2O5 recovery in the EAF slag were lower in some test heats. Studies may thus be carried out in future to increase the P2O5 recovery from MCP-F, hence, achieving a higher efficiency of stabilization treatments for the slag from the EAF plant.
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