Abstract In the present work we investigate the possibility of reusing phosphate sludge, which is considered as a mining by-product from beneficiation plants of the Moroccan phosphate rocks (OCP, Youssoufia), through the geopolymerization process. This process allows to evaluate the alkaline behaviour of thermally untreated phosphate sludge (UPS) as a partial replacement of metakaolin. The geopolymers were synthesized with various activator modulus (Ms = 1.40, 1.30, 1.24, 1.20, and 1.15) made from a mixture of different alkaline (NaOH and KOH) solutions and sodium silicate. The effect of 0–60% untreated sludge (UPS) powder in metakaolin based geopolymer materials cured at 60 °C was investigated. Compressive strength and apparent porosity were determined after 28 days of curing and the reaction products were tested by different techniques including: X-Ray Diffraction (XRD), Fourier Transformed Infrared spectroscopy (FTIR), thermal gravimetric analyses (TGA) and Electron microscope scanning coupled with energy dispersive spectroscopy (SEM-EDX). For up to 50% of UPS, physical properties of the hardened products are induced, especially when the activator modulus (Ms = 1.30) is used. In these blends, the presence of UPS is favorable to ensure the better connectivity between grains in the system. In fact, the sludge has been suggested to have a dual role, it has a filler effect and/or a small precipitation of Ca-bearing phases co-existing with (Na, K)-A-S-H-type gel.

中文翻译：

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碱混合量和未热处理磷酸盐污泥用量对偏高岭土基地聚物材料性能的影响

摘要 在目前的工作中，我们研究了通过地质聚合过程重复利用磷酸盐污泥的可能性，磷酸盐污泥被认为是摩洛哥磷酸盐岩（OCP，Youssoufia）选矿厂的采矿副产品。该过程允许评估未经热处理的磷酸盐污泥 (UPS) 作为偏高岭土的部分替代品的碱性行为。地质聚合物由不同的碱性（NaOH 和 KOH）溶液和硅酸钠的混合物制成，具有不同的活化剂模量（Ms = 1.40、1.30、1.24、1.20 和 1.15）。研究了 0-60% 未处理污泥 (UPS) 粉末在 60 °C 固化的偏高岭土基地质聚合物材料中的影响。固化 28 天后测定抗压强度和表观孔隙率，并通过不同技术测试反应产物，包括：X 射线衍射 (XRD)、傅里叶变换红外光谱 (FTIR)、热重分析 (TGA) 和电子显微镜扫描结合能量色散光谱 (SEM-EDX)。对于高达 50% 的 UPS，会引起硬化产品的物理特性，尤其是在使用活化剂模量 (Ms = 1.30) 时。在这些混合中，UPS 的存在有利于确保系统中谷物之间更好的连接。事实上，污泥被认为具有双重作用，它具有填料作用和/或与 (Na, K)-ASH 型凝胶共存的含 Ca 相的少量沉淀。会诱发硬化产品的物理特性，尤其是在使用活化剂模量 (Ms = 1.30) 时。在这些混合中，UPS 的存在有利于确保系统中谷物之间更好的连接。事实上，污泥被认为具有双重作用，它具有填料作用和/或与 (Na, K)-ASH 型凝胶共存的含 Ca 相的少量沉淀。会诱发硬化产品的物理特性，尤其是在使用活化剂模量 (Ms = 1.30) 时。在这些混合中，UPS 的存在有利于确保系统中谷物之间更好的连接。事实上，污泥被认为具有双重作用，它具有填料作用和/或与 (Na, K)-ASH 型凝胶共存的含 Ca 相的少量沉淀。