Abstract

Fertilizers made of steelmaking slag are important inexpensive materials for recovering degraded paddy fields. The results of our previous works showed that essential Ca and Si elements were effectively supplied by the dicalcium silicate phase (C₂S) while the glassy phase of the CaO–SiO₂–FeO system served as an Fe source. In this study, we have developed a slag containing both the C₂S and glassy phases that are capable of simultaneously supplying Ca, Si, and Fe elements to paddy fields. To determine the optimum conditions for supplying Fe from the glassy phase, the molten slag of the CaO–SiO₂–FeO system was quenched from 1573 K, and the upper limits of its FeO content and basicity for glass formation were obtained. After that, slags consisting of the glassy phases with various compositions and the C₂S crystal phase were synthesized and subjected to a leaching test. By analyzing the dissolution behaviors of different phases, a kinetic model was established to estimate the dissolved amount of each element and determine the optimum slag composition, which was obtained at a quenching temperature of 1573 K, basicity of 1.6, and FeO concentration of approximately 25 mass%. The dissolved amounts of Fe and Si produced by this slag exceeded those of commercial fertilizers prepared from steelmaking slag by factors of 6 and 2–3, respectively, while their respective amounts of supplied Ca were close to each other.

Graphical Abstract

中文翻译：

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利用CaO-SiO 2 -FeO系统的玻璃态设计一种新型的炼钢渣肥料。第一部分：渣化学和组织的优化

摘要

炼钢炉渣制成的肥料是用于恢复退化稻田的重要廉价材料。我们先前工作的结果表明，硅酸二钙相（C ₂ S）有效地供应了必需的Ca和Si元素，而CaO-SiO ₂ -FeO系统的玻璃相则作为Fe的来源。在这项研究中，我们开发了一种既包含C ₂ S相又包含玻璃相的矿渣，这些矿渣能够同时向稻田供应Ca，Si和Fe元素。为了确定从玻璃态供应铁的最佳条件，CaO-SiO ₂的熔融炉渣-FeO体系从1573 K开始淬火，获得了其FeO含量和玻璃形成碱度的上限。之后，炉渣由各种组成的玻璃相和C _2组成合成S晶相并进行浸出试验。通过分析不同相的溶解行为，建立了动力学模型以估算每种元素的溶解量并确定最佳炉渣成分，该成分是在1573 K的淬火温度，1.6的碱度和大约25的FeO浓度下获得的质量％。由这种炉渣产生的铁和硅的溶解量分别比由炼钢炉渣制备的商业肥料的溶解量高6到2–3，而它们各自供应的Ca彼此接近。

图形概要