This work was undertaken to determine whether thermodynamic calculations can predict the amount and composition of ash produced by combustion of nickel hyperaccumulator (HA) plants in the context of agromining. To this end, three HA plants containing about 1 wt% of nickel were submitted to isothermal combustion at 550, 815, 900 °C and the solid residues were characterized by complementary techniques (TGA, XRD, ICP-OES, ion chromatography, SEM-EDX), while thermodynamic calculations were performed with the FactSage software using the dry biomass composition as input. We present an in-depth evaluation of inorganics behavior based on the combination and comparison of experimental data and calculations: effect of temperature on ash yield, nature of crystallized phases, ash elemental composition and inorganics volatilization. Our work confirms that equilibrium calculation is a powerful method to evaluate the behavior of inorganic elements during thermal treatment of biomass, despite some lacks in the databases. For the nickel HA plants, an innovative result is that, after combustion, nickel is always in the form of NiO particles, that can mix with MgO to form (Ni,Mg)O solid solutions. These results have direct implications for understanding the combustion process and for better design of the following leaching step aiming at Ni recovery.

进行这项工作是为了确定热力学计算是否可以预测在农耕条件下镍超蓄积（HA）植物燃烧产生的灰分的数量和组成。为此，将三份含约1 wt％镍的HA设备在550、815、900°C下进行等温燃烧，并通过互补技术（TGA，XRD，ICP-OES，离子色谱，SEM- EDX），同时使用干燥的生物质成分作为输入，使用FactSage软件进行热力学计算。我们结合实验数据和计算结果的比较和比较，对无机物的行为进行了深入评估：温度对灰分产率，结晶相性质，灰分元素组成和无机物挥发的影响。我们的工作证实，尽管数据库中存在一些不足，但平衡计算是评估生物质热处理过程中无机元素行为的有效方法。对于镍HA工厂而言，一个创新的结果是，燃烧后镍总是以NiO颗粒的形式存在，可以与MgO混合形成（Ni，Mg）O固溶体。这些结果对理解燃烧过程以及对旨在回收镍的后续浸出步骤的更好设计具有直接的启示。