Vangelatos I, Angelopoulos G N, Boufounos D
Department of Chemical Engineering, Laboratory of Materials and Metallurgy, University of Patras, Rio, Greece.
J Hazard Mater. 2009 Aug 30;168(1):473-8. doi: 10.1016/j.jhazmat.2009.02.049. Epub 2009 Feb 20.
Red mud (RM), the digestion by-product of bauxite processing from "Aluminum Hellas", was dewatered by means of a filter press. The filtrand with water content from 28 to 32 wt% was named ferroalumina (FA). In order to utilize it as a raw material in the production of Ordinary Portland Cement (OPC), mixtures were prepared with limestone, sandstone and 1, 3 and 5 wt% FA addition, respectively. The design of the mixtures was based on the cement's compositional indexes LSF, AM and SM. Burnability tests showed that less than 1 wt% free lime can be obtained in all cases for firing at 1450 degrees C, except for the mixture with 1 wt% FA addition, which requires 1550 degrees C. XRD analysis and optical microscopy examination showed that FA addition did not affect the mineralogical phases of the produced clinkers. The characterisation of the produced Portland cements indicated that differences on surface area, water requirement and setting time are negligible. Compressive strength results after 28 days of curing varies from 55 to 63 MPa, which ranks the produced cements in CEM I 42.5N category. More specifically, the cements with FA addition due to their relatively high 2-day strengths (>20 MPa) can be ranked in CEM I 52.5N category. Addition of FA increases the amount of water-soluble chromium proportionally to the amount of total chromium to the mixture; however, conversion of total Cr to hexavalent Cr remains practically constant, in the range of 32-35 wt%. The results indicate that FA can be used as raw material in the production of OPC up to 5 wt% according to the chemical composition of the other raw materials.
来自“希腊铝业”的铝土矿加工消化副产物赤泥（RM）通过压滤机进行脱水处理。含水量为28%至32%（重量）的滤饼被称为铁铝土（FA）。为了将其用作生产普通硅酸盐水泥（OPC）的原料，分别制备了添加1%、3%和5%（重量）FA的石灰石、砂岩混合物。混合物的设计基于水泥的组成指标LSF、AM和SM。易烧性试验表明，在1450℃煅烧时，除添加1%（重量）FA的混合物需要1550℃外，所有情况下均可获得低于1%（重量）的游离石灰。XRD分析和光学显微镜检查表明，添加FA不会影响所生产熟料的矿物相。所生产的波特兰水泥的特性表明，比表面积、需水量和凝结时间的差异可忽略不计。养护28天后的抗压强度结果在55至63MPa之间，所生产的水泥属于CEM I 42.5N类别。更具体地说，由于添加FA的水泥具有相对较高的2天强度（>20MPa），可属于CEM I 52.5N类别。添加FA会使水溶性铬的含量与混合物中总铬的含量成比例增加；然而，总Cr向六价Cr 的转化率实际上保持恒定，在32%至35%（重量）范围内。结果表明，根据其他原料的化学成分，FA可作为OPC生产中高达5%（重量）的原料使用。
