The engineered sequestration of carbon dioxide (CO₂) emissions through mineral carbonation typically requires energy intensive conditions and chemical reagents to accelerate the naturally slow reaction processes. In order to be an effective carbon dioxide mitigation strategy, engineered mineral carbonation processes have to result in a net reduction of CO₂ emissions. This is particularly the case for feedstock such as platinum group metal (PGM) tailings, which are comprised largely of the relatively inert pyroxene mineral. This study evaluated the viability of using these tailings for carbon sequestration through mineral carbonation on the basis of an assessment of the potential carbon footprint of selected engineered processes. The processes selected include the ammonium salts process, the direct aqueous process, the Åbo Akademi University (ÅAU) multi-stage gas-solid route, a mineral acid pH swing process and Lackner’s multi-stage HCl extraction process. Aspen Plus v8 software was used for mass and energy balance modelling, whilst the Life Cycle Assessment (LCA) software programme SimaPro v7.7.3 was used for carbon emissions accounting. The selected processes all resulted in higher emissions of carbon dioxide than those sequestered. This was particularly the case for Lackner’s multi stage HCl process (18 295 kg-CO₂e) and the indirect aqueous ammonium salts (8 798 kg-CO₂e) processes. The process having the lowest carbon footprint was the ÅAU process (1 354 kg-CO₂e), followed by the direct aqueous process (2 364 kg-CO₂e) and the mineral acid pH swing (3 126 kg-CO₂e). The unit processes making the most significant contribution to the carbon footprint of the mineral carbonation process systems are heat requirements and chemical reagent make-up. Sensitivity analysis shows that the direct aqueous and ÅAU process emissions can be reduced beyond the CO₂ emissions threshold when conversion is increased.

通过矿物碳酸化工程化隔离二氧化碳（CO ₂）排放物通常需要消耗大量能量的条件和化学试剂来加速自然缓慢的反应过程。为了成为有效的二氧化碳减排策略，工程矿物质碳化过程必须导致CO ₂的净减少排放。对于诸如铂族金属（PGM）尾矿之类的原料尤其如此，它们主要由相对惰性的辉石矿物组成。这项研究基于对选定工程工艺的潜在碳足迹的评估，评估了使用这些尾矿通过矿物碳化进行碳固存的可行性。选择的工艺包括铵盐工艺，直接水工艺，ÅboAkademi大学（ÅAU）多级气固路线，无机酸pH值变动工艺和Lackner的多级HCl萃取工艺。Aspen Plus v8软件用于质量和能量平衡建模，而生命周期评估（LCA）软件程序SimaPro v7.7.3用于碳排放核算。选定的过程均导致二氧化碳排放量高​​于隔离的二氧化碳排放量。拉克纳（Lackner）多阶段HCl工艺（18295 kg-CO₂ e）和间接含水铵盐（8 798 kg-CO ₂ e）工艺。碳足迹最低的工艺是ÅAU工艺（1 354 kg-CO ₂ e），其次是直接水工艺（2 364 kg-CO ₂ e）和无机酸pH波动（3 126 kg-CO ₂ e） ）。对矿物碳化过程系统的碳足迹贡献最大的单元过程是热量需求和化学试剂补充。敏感性分析表明，当转化率增加时，直接水和AUAU过程的排放量可以减少到超过CO ₂排放阈值。