Abstract Torrefaction or hydrothermal carbonization processes were compared for conversion of olive pulp into metallurgical reducing agent. The dependence of yield, CO2 reactivity, and mechanical properties to reaction time and heat treatment temperature was investigated. Hydrochar yield increased with increasing residence time and the maximum solid yield was observed for a residence time of 15 h. On the other hand, CO2 reactivity slightly decreased with increasing heat treatment temperature at a residence time of 2 h. Notably, the CO2 reactivity of hydrochar was less than that of olive pulp char produced by torrefaction, approximating that of carbon-based reducing agents derived from non-renewable resources. An additional heat treatment improved hydrochar pellet durability to greater than 95%, whereas stable torrefied char pellets could not be produced under any set of conditions. Hydrothermal carbonization is superior to torrefaction for production of renewable reducing agents with reactivity and mechanical properties comparable to those afforded by reducing agents from non-renewable sources.

中文翻译：

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橄榄废料的水热碳化生产可再生、无粘合剂的球团，用作冶金还原剂

摘要 比较了烘焙或水热碳化工艺将橄榄果肉转化为冶金还原剂的过程。研究了产率、CO2 反应性和机械性能对反应时间和热处理温度的依赖性。Hydrochar 产量随着停留时间的增加而增加，并且在 15 小时的停留时间观察到最大固体产量。另一方面，在 2 小时的停留时间，随着热处理温度的升高，CO2 反应性略有下降。值得注意的是，hydrochar 的 CO2 反应性低于通过烘焙产生的橄榄果肉炭的 CO2 反应性，接近源自不可再生资源的碳基还原剂的 CO2 反应性。额外的热处理将 Hydrochar 颗粒的耐用性提高到 95% 以上，而在任何一组条件下都不能生产稳定的烘焙炭颗粒。水热碳化在生产可再生还原剂方面优于烘焙，其反应性和机械性能与来自不可再生来源的还原剂所提供的性能和机械性能相当。