The first version of the P-Hydroslag model for numerical simulations of steel slag filters is presented. This model main original feature is the implementation of slag exhaustion behavior, crystal growth and crystal size effect on crystal solubility, and crystal accumulation effect on slag dissolution. The model includes four mineral phases: calcite, monetite, homogeneous hydroxyapatite (constant size and solubility) and heterogeneous hydroxyapatite (increasing size and decreasing solubility). In the proposed model, slag behavior is represented by CaO dissolution kinetic rate and exhaustion equations; while slag dissolution is limited by a diffusion rate through a crystal layer. An experimental test for measurement of exhaustion equations is provided. The model was calibrated with an experimental program made of three phases. Firstly, batch tests with 300 g slag sample in synthetic solutions were conducted for the determination of exhaustion equation. Secondly, a slag filter column test fed with synthetic solution was run for 623 days, divided into 9 cells and sampled at the end of the experiment. Finally, the column was dismantled, sampled and analyzed with XRD, TEM and SEM. Experimental column curves for pH, oPO₄, Ca and inorganic carbon were well predicted by the model. Crystal sizes measured by XRD and TEM validated the hypothesis for homogeneous precipitation while SEM observations validated the thin crystal layer hypothesis. A preliminary validation of the model resulted in successful predictions of a steel slag filter longevity fed with real wastewater.

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使用P-水渣模型进行数值模拟以预测钢渣过滤器的除磷效果

提出了用于钢渣过滤器数值模拟的P-水渣模型的第一个版本。该模型的主要原始特征是实现排渣行为，晶体生长和晶体尺寸对晶体溶解度的影响，以及晶体累积对炉渣溶解的影响。该模型包括四个矿物相：方解石，三方沸石，均相羟基磷灰石（尺寸和溶解度恒定）和非均相羟基磷灰石（尺寸增加和溶解度减小）。在所提出的模型中，渣的行为由CaO的溶解动力学速率和耗竭方程表示。炉渣的溶解受结晶层中扩散速度的限制。提供了用于测量排气方程的实验测试。使用由三个阶段组成的实验程序对模型进行了校准。首先，用300 g炉渣样品在合成溶液中进行分批测试，以确定排气方程。其次，用合成溶液供料的矿渣过滤器柱测试进行了623天，分为9个小室，并在实验结束时进行了采样。最后，将色谱柱拆解，取样并用XRD，TEM和SEM分析。pH，oPO的实验色谱柱曲线_{如图4所示}，通过该模型可以很好地预测Ca和无机碳。通过XRD和TEM测量的晶体尺寸证实了均相沉淀的假设，而SEM观察证实了薄晶体层的假设。该模型的初步验证成功预测了掺有真实废水的钢渣过滤器寿命。