铁尾矿蒸压材料物相演变调控及其强度形成机制

Phase Evolution Regulation and Strength Formation Mechanism of the Autoclaved Materials from Iron Tailings

摘要:

本文以铁尾矿完全替代石英砂制备蒸压材料,研究了不同蒸压温度和恒温时间下蒸压材料强度发展,采用XRD、SEM和EDS,研究分析了水化产物物相组成和微观形貌。研究表明:最佳蒸压制度是在蒸压温度180 ℃恒温5 h；蒸压合成材料的主要产物物相有C-S-H(Ⅰ)、C-S-H(Ⅱ)和托勃莫来石,水化硅酸钙形貌有絮状、尖状、方形片状、细杆状等多种形貌；Tobermorite增长和减弱的规律,与抗压强度增减规律一致,揭示了托勃莫来石是强度产生的根源；蒸压材料物相演变和强度形成与发展,可分为水热合成初期、中期(快速增长期)、顶峰期(成熟期)、衰弱期4个阶段,各阶段物相组成与形貌、材料强度随蒸压制度而演变和发展。

Abstract:

This study investigates the strength development of autoclaved materials prepared by completely replacing quartz sand with iron tailings under different autoclaving temperatures and constant-temperature durations. The phase composition and microstructure of hydration products were analyzed using XRD, SEM, and EDS. The results show that the optimal autoclaving regime is 180 °C for 5 h. The primary phases formed during autoclaving include C-S-H(Ⅰ), C-S-H(Ⅱ), and tobermorite, with calcium silicate hydrate exhibiting various morphologies such as flocculent, needle-like, square-plate, and stick-like structures. The growth and decline of tobermorite align with the increase and decrease in compressive strength, confirming that tobermorite is the key phase governing strength development. The phase evolution and strength formation of autoclaved materials can be divided into four stages: initial synthesis, intermediate development, peak maturity, and decline. The phase composition, microstructure, and material strength evolve with the autoclaving regime.