Recycling of blast furnace slag to prepare calcium silicate hydrate by mechanical-chemical co-activation and its application to calcium silicate fireproof board

摘要

The high-value utilization of water quenched slag (WQS), one of the bulk byproducts originating from the iron manufacturing industry, remains an important subject in the environment. Through a mechano-chemical coactivation strategy, WQS can be used to prepare porous calcium silicate hydrate (C-S-H), which was applied as gelling filler to prepare fiber-reinforced calcium silicate fireproof board (FCSFB) and extremely improved its high-temperature performance and non-combustibility. The optimal activation conditions for WQS are ball milling time of 30 min, reaction temperature of 90 degrees C, reaction time of 5 h, and Ca/Si molar ratio of 1.5:1. The thermal conductivity for FCSFB prepared by the optimal A-WQS is 0.17 W/(m center dot K), and its overheating time of the applied temperature at 803.7 degrees C is 1335.5 s. The improvement mechanism of the performance of FCSFB can be attributed to the transformation of C-S-H toward more high crystallinity flaky tobermorite, which uniformly and closely combined with pulp fiber to form a micro-porous cavity structure to delay flame penetration period. The application of WQS in FCSFB can provide essential guidance for the utilization of other similar solid wastes.

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