CARBONATION OF STAINLESS STEEL SLAG AS A PROCESS FOR CO2 STORAGE AND SLAG VALORISATION
This paper examines the main results of the accelerated carbonation treatment of different types and size fractions of stainless steel slag. The objectives of this work were essentially to assess the CO2 storage capacity of each type of slag under mild operating conditions, to study the influence on reaction kinetics of the main operational parameters (temperature, pressure and liquid to solid ratio) and finally to investigate the effects of carbonation on the mineralogy and leaching behaviour of the residues. The following types of materials were tested: AOD (Argon oxygen decarburization) slags and a mixture of AOD and EAF (Electric Arc Furnace) slags. This latter material was subdivided by sieving into 4 size fractions. Each fraction of both types of materials was thoroughly characterized in terms of physical properties, elemental composition, anion content, mineralogy and leaching behaviour. Accelerated aqueous carbonation batch experiments were performed in a stainless steel reactor, exposing humidified slag to a 100％ CO2 atmosphere for operating times between 0.5 and 24 hours, at controlled temperature and pressure. Maximum CO2 uptakes of 130 and 300 g CO2/kg slag were achieved (at 50 ℃ and 3 bar) for the finest fraction of the EAF-AOD mixture and for the AOD slag alone, respectively. The CO2 uptake capacity of the EAF-AOD mixture decreased with increasing particle size, owing to a lower availability of reacting species and especially a lower specific surface. The mineralogy of both types of slag was affected by the treatment in relation to the achieved extent of carbonation. The leaching behaviour of the carbonated slag was also modified, exhibiting a pH reduction by 1-2 units, depending on particle size, a decrease of Ca and an increase of Si leaching. In conclusion, the results of this study indicated that accelerated carbonation, carried out under mild operating conditions, affected several material properties. In particular, AOD slag appeared to be significantly more reactive with CO2 at the tested operating conditions; however, milling and higher operating temperature may prove effective techniques to enhance the carbonation yield of the EAF-AOD mixture.
stainless steel slag CO2 uptake carbonation kinetics particle size mineralogy leaching.
R. BACIOCCHI G. COSTA A. POLETTINI R. POMI
Dept. Civil Engineering, University of “Tor Vergata, Rome, Italy Dept. Hydraulics, Transportation and Roads, University of Rome “La Sapienza, Rome,Italy
国际会议
北京
英文
585-590
2010-05-17（万方平台首次上网日期，不代表论文的发表时间）