| 1. |
- Lindvall, Mikael, et al.
(författare)
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Recovery of vanadium from v-bearing bof-slag using an eaf
- 2010
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Ingår i: Proceedings of the 12th International Ferroalloys Congress: Sustainable Future. - 9789529273409 ; , s. 189-195
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Konferensbidrag (refereegranskat)abstract
- Experiments on a vanadium recovery method from vanadium containing BOF-slag using a 10 tons electric arc furnace (EAF) were conducted. The aim was not only to recover vanadium efficiently but also to make the treated BOF-slag useful for external markets. The vanadium and other valuable metals were extracted into a metal phase by pre-reduction using carbon-based reductants and finalreduction by injection of ferrosilicon- and/or aluminium powder. The results did show that in excess of 98% of vanadium could be recovered to the metal by this method, most of the iron and phosphorus was also successfully recovered to the metal. The reduced BOF-slag has a vanadium-content as low as 0.02mass% and thus has good opportunity to be used as construction material. The tested parameters important for the process are described and discussed in details in this paper.
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| 2. |
- Midander, Klara, et al.
(författare)
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Bioaccessibility of FERRO-chromium and ferrosilicon-chromium particles compared to pure metals and stainless steel-Aspects of human exposure
- 2010
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Ingår i: Proceedings of the 12th International Ferroalloys Congress: Sustainable Future. - 9789529273409 ; , s. 43-51
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Konferensbidrag (refereegranskat)abstract
- Product safety legislation requires that industry indentifies and demonstrates any human risks associated with the manufacture and use of products which are placed on the market throughout their entire life cycle. This process involves detailed assessment of potential hazards of the products/material related to health effect endpoints, and requires accurate generation and interpretation of data which can be used to determine essential characteristics of the material. Temporary or permanent adverse health effects depend either on the shape or physical characteristics of the particles, and/or on chemical interactions with the particle surface upon human exposure. Since alloys represent the most significant and widespread use of many engineering metals, it is important to develop a detailed understanding of the characteristics and behaviour of this group of materials with a minimum dependence on in-vivo testing. The aim of this presentation is to summarize generated bioaccessibility data for ferro-chromium and ferro-silicon-chromium alloys in particulate form when exposed to different synthetic biological media. The selection of test media aims to mimic relevant human exposures, as far as practical, with the focus on inhalation and subsequent ingestion of inhaled particles. The generation of bioaccessibility data combined with detailed particle and material characterization, also from a surface perspective, is essential for accurate risk assessment and understanding of potential adverse effects that may be caused by ferro-chromium and ferro-silicon-chromium alloys. For comparison, a similar approach has been conducted on particles of pure iron, pure chromium and stainless steel grade AISI 316L. Generated data is used within the framework of risk assessment on ferro-chromium and ferro-siliconchromium alloys conducted by the Finnish Institute of Occupational Health, Helsinki, Finland.
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| 3. |
- Stockmann-Juvala, H., et al.
(författare)
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Use of read-Across in the health risk assessment of ferrochromium alloys under reach
- 2010
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Ingår i: Proceedings of the 12th International Ferroalloys Congress. - 9789529273409 ; , s. 35-42
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Konferensbidrag (refereegranskat)abstract
- In REACH regulation there is a category of substances called special preparations, to which alloys belong. In the assessment of special preparations not only the bulk composition of an alloy, but also the way the constituent metals are bonded in the chemical matrix, shall be taken into account. The surface of the alloy may limit the ability of constituent metals to be released from the matrix and thus affect the toxicological profile of an alloy. Therefore, the surface characteristics and the release rates of metals shall be taken into account. Finnish Institute of Occupational Health has been carrying out REACH-compliant chemical safety assessment of ferrochromium in collaboration with International Chromium Development Association. Ferrochromium is composed mainly of chromium and iron with small amounts of other metals, e.g. nickel. Since almost no studies have been published on the health effects of ferrochromium, the assessment of ferrochromium should be based on its constituent metals. An approach used in this study included the use of data on surface composition and release of metal constituents from ferrochromium. The chromium oxide surface layer limits the release of nickel and other constituents from ferrochromium and affects the toxicological profile. As a result it can be concluded that ferrochromium alloys can be likened to chromium metal and stainless steel when assessing their health hazards. Thus, the risk assessment can be based largely on existing human, animal and in vitro toxicity data on chromium metal, chromium(III)oxide and stainless steel. By referring to this data, it was possible to make conclusions on health hazards of ferrochromium without need to carry out any new toxicity tests.
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| 4. |
- Wang, Haijuan, et al.
(författare)
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Oxidation kinetics of ferrochrom under controlled oxygen pressures
- 2010
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Ingår i: Proceedings of the 12th International Ferroalloys Congress. - 9789529273409 ; , s. 411-419
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Konferensbidrag (refereegranskat)abstract
- In order to make the stainless steel making process efficient and environment friendly, it is essential to minimize the loss of chromium to the slag phase. With a view to investigate the advantages of using CO2 to attain moderate oxygen partial pressures in the oxidant gas during the decarbirization of stainless steel, the present experiments were carried out to understand the oxidation kinetics of Fe-Cr alloy and Fe-Cr-C alloy with gas mixtures containing CO2. In the present work, the oxidation behavior of Fe-Cr was examined by thermogravimetric analysis (TGA). Various mixtures of O2 and CO2 were used as the oxidant gas and the oxidation rate was followed by the weight changes as a function of time. One trial was made on the oxidation of Fe-Cr-C alloy with CO2 as the oxidant. The experiments demonstrated that the oxidation rate is independent of temperature at present experimental situation, but has strongly related to the Cr-content of the alloy as well as the oxygen partial pressure in the oxidant gas mixture. The wetting of alumina by the iron drop and the change of the drop shape during the course of the oxidation were investigated by X-ray radiography.
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