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首页> 外文OA文献 >Hydration of Dicalcium Silicate and Diffusion through Neo-Formed Calcium-Silicate- Hydrates at Weathered Surfaces Control the Long-Term Leaching Behaviour of Basic Oxygen Furnace (BOF) Steelmaking Slag.
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Hydration of Dicalcium Silicate and Diffusion through Neo-Formed Calcium-Silicate- Hydrates at Weathered Surfaces Control the Long-Term Leaching Behaviour of Basic Oxygen Furnace (BOF) Steelmaking Slag.

机译：硅酸二钙的水化和在风化表面通过新形成的钙 - 硅酸盐 - 水合物的扩散控制了碱性氧气炉（BOF）炼钢炉渣的长期浸出行为。

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Alkalinity generation and toxic trace metal (such as vanadium) leaching from BOF steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5-1.0 mm, 2-5 mm and 10 x 10 x 20 mm blocks) and a 6 month pre-weathered block. There were several distinct leaching stages observed over time associated with different phases controlling the solution chemistry: (1) free lime (CaO) dissolution (days 0-2); (2) dicalcium silicate (Ca2SiO4) dissolution (days 2-14); and (3) Ca-Si-H and CaCO3 formation and subsequent dissolution (days 14-73). Experiments with the smallest size fraction resulted in the highest Ca, Si, and V concentrations, highlighting the role of surface area in controlling initial leaching. After ~2 weeks the solution Ca/Si ratio (0.7-0.9) evolved to equal those found within a Ca-Si-H phase that replaced dicalcium silicate and free lime phases in a 30-150 µm altered surface region. V release was a two stage process; initially V was released by dicalcium silicate dissolution, but V also isomorphically substituted for Si into the neo-formed Ca-Si-H in the alteration zone. Therefore, on longer timescales the release of V to solution was primarily controlled by considerably slower Ca-Si-H dissolution rates, which decreased the rate of V release by an order of magnitude. Overall the results indicate that the BOF slag leaching mechanism evolves from a situation initially dominated by rapid hydration and dissolution of primary dicalcium silicate / free lime phases, to a slow diffusion limited process controlled by the solubility of secondary Ca-Si-H and CaCO3 phases that replace and cover more reactive primary slag phases at particle surfaces.
机译：如果要最大程度地利用炉渣，必须通过预处理适当地理解和管理从BOF钢渣颗粒中产生的碱度和有毒的痕量金属（例如钒）。使用三种不同粒径（0.5-1.0 mm，2-5 mm和10 x 10 x 20 mm块）和6个月预风化块的新鲜BOF炉渣研究了充气条件下的水浸出。随着时间的推移，观察到几个不同的浸出阶段，与控制溶液化学的不同阶段有关：（1）游离石灰（CaO）溶解（第0-2天）； （2）溶解硅酸二钙（Ca2SiO4）（2-14天）； （3）Ca-Si-H和CaCO3的形成以及随后的溶解（第14-73天）。尺寸分数最小的实验导致最高的Ca，Si和V浓度，突出了表面积在控制初始浸出中的作用。约2周后，溶液中的Ca / Si比（0.7-0.9）演变为与在30-150 µm改变的表面积中取代硅酸二钙和游离石灰相的Ca-Si-H相相同。 V释放是一个分为两个阶段的过程。最初，V是通过硅酸二钙的溶解而释放的，但V也同构地替代了Si，使其进入蚀变区中新形成的Ca-Si-H中。因此，在较长的时间尺度上，V到溶液的释放主要是由相当慢的Ca-Si-H溶解速率控制的，这将V释放的速率降低了一个数量级。总体而言，结果表明，BOF炉渣的浸出机理已从最初以快速水化和一级硅酸二钙/游离石灰相的溶解为主的状态演变为由次级Ca-Si-H和CaCO3相的溶解度控制的缓慢扩散受限的过程。替代并覆盖了颗粒表面更具反应性的主要炉渣相。

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