Agromining is an emerging technology aiming at recovering metals from soils using hyperaccumulator (HA) plants. Plant cultivation and pyro- and hydrometallurgical processes have been designed for nickel (Ni) recovery. In this chain of processes, dry plants are burnt to obtain Ni-rich ashes that are subsequently treated. To ensure the sustainability and the profitability of the process, energy recovered at the combustion stage would add some value. The combustion of three Ni HA plants (Odontarrhena chalcidica, Leptoplax emarginata and Berkheya coddii) was investigated. Namely the higher and lower heating values (HHV and LHV) were measured with a calorimeter bomb and calculated with correlations, thermo-gravimetric analysis was performed, dry plants and ashes were characterized, and gas emissions were monitored during combustion at two temperatures. In a complementary approach, the self-heating behaviour of plants and ashes were compared, and the activation energy of such phenomenon was determined. These results allowed the identification of the step limiting the self-inflammation of the plants, which gives relevant information for their safe storage.

农业化是一项新兴技术，旨在使用超富集（HA）植物从土壤中回收金属。已经设计了植物培养以及火法和湿法冶金工艺来回收镍（Ni）。在这一系列过程中，将干燥的植物燃烧以获得富含镍的灰烬，然后对其进行处理。为了确保过程的可持续性和盈利能力，在燃烧阶段回收的能量将增加一些价值。三种Ni HA植物的燃烧（Odontarrhena chalcidica，Leptoplax emarginata和Berkheya coddii）进行了调查。即，用热量计炸弹测量较高和较低的发热量（HHV和LHV）并进行相关计算，进行热重分析，表征干燥的植物和灰烬，并在两个温度下燃烧期间监测气体排放。在补充方法中，比较了植物和骨灰的自热行为，并确定了这种现象的活化能。这些结果允许鉴定限制植物自发炎的步骤，从而为植物的安全贮藏提供了相关信息。