Impact of the Replacement of Pitch Binder by the Environmentally Friendly Binder System Based on Lactose and Tannin on the Properties of Carbon‐Bonded Alumina Filters

Carbon‐bonded alumina filters have been established in the steel industry for decades to increase the quality of cast steel components. The carbon bonding of the filter materials is commonly achieved by using pitches or resins. However, the pyrolysis of both substances results in the release of carcinogenic substances such as free phenols or benzo[a]pyrene. An alternative binder system is provided by lactose and tannin, which is considered to be more environmentally friendly, but they tend to result in insufficient mechanical filter properties.To ensure higher environmental sustainability and good mechanical properties, the effect of the stepwise replacement of the pitch‐binder CarboresP by lactose and tannin is investigated in the present study. Additionally, the impact of semiconductive additives (P‐doped n–Si and SiC) and the filter manufacturing method on the filter properties is analyzed. Based on the most promising filter composition, different lactose/tannin ( L / T ) ratios (5:1, 4:1, 3:1) are applied and the resulting properties evaluated. The results suggested that the pitch binder can be completely replaced by lactose and tannin by using SiC as additive and adjusting the filter manufacturing process. The variation of the L / T ratio shows no significant impact on the filter prope.