Steel slags generally swell when subjected to water or humidity, which prevents proper recycling in the cement or asphalt industries. The MgO and CaO phases in steel slags are responsible for this phenomenon, as both minerals easily absorb water to form their respective hydroxides. MgO is often present in steel slags in a solid solution with several oxides, constituting the so-called RO phase. This study investigates the hydration rate of an RO phase consisting of FeO and MgO called ferropericlase. The material was synthesized in a laboratory furnace by sintering a FeO–MgO powder mixture with varying initial FeO contents (approximately 10, 15, and 20 wt%). Thereafter, electron probe micro-analyzer (EPMA) and X-ray diffraction (XRD) spectroscopies were used to characterize the structure of the samples, which were mainly composed of ferropericlase and an exsolution of magnesioferrite. Also, Mössbauer spectra showed that the total ferrous iron proportion (Fe²⁺/ΣFe) of the sintered samples was in the range of 0.55–0.72. To measure the hydration behavior, the samples in powder form were cured in an autoclave at an H₂O partial pressure of 2 atm. Thereafter, thermal gravimetric analysis (TGA) was performed to measure the amount of water absorbed during the autoclave curing from the mass drop associated with the dehydration of the hydroxide. The study found a linear correlation between the initial FeO content and the weight loss after TGA, with a reduction down to 6% in the sample with an initial FeO content of 20 wt% content compared to pure MgO.

Graphical Abstract

中文翻译：

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低铁氧化物浓度的合成除草剂的水化行为防止钢渣膨胀的研究

钢渣在遇水或受潮时通常会膨胀，这会阻碍水泥或沥青工业中的适当回收利用。钢渣中的MgO和CaO相是造成这种现象的原因，因为两种矿物都容易吸收水形成各自的氢氧化物。MgO通常以固溶体形式与几种氧化物一起存在于钢渣中，构成所谓的RO相。这项研究调查了由FeO和MgO组成的RO相的水合速率，该相称为Ferropericlase。该材料是在实验室炉中通过烧结具有不同初始FeO含量（约10、15和20 wt％）的FeO-MgO粉末混合物来合成的。之后，使用电子探针显微分析仪（EPMA）和X射线衍射（XRD）光谱仪表征样品的结构，它们主要由阿魏酸酯酶和镁铁矿的析出物组成。此外，穆斯堡尔光谱显示，总亚铁比例（Fe烧结样品的²⁺ /ΣFe）范围为0.55-0.72。为了测量水合行为，将粉末形式的样品在高压釜中于2 atm的H ₂ O分压下固化。此后，进行热重分析（TGA），以测量在高压釜固化过程中从与氢氧化物脱水有关的质量下降中吸收的水量。研究发现，初始FeO含量与TGA后的重量损失之间存在线性关系，与纯MgO相比，初始FeO含量为20 wt％时样品中的FeO含量降低了6％。

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