In pH-swing mineral carbonation, several acid/base systems has been investigated. Currently the main acid/base systems employed are HCl/NaOH and NH₄HSO₄/NH₄OH. However, the use of a HCl/NH₄OH system was not yet elucidated. This study proposes to evaluate the feasibility of a pH-swing mineral carbonation based on HCl/NH₄OH system at atmospheric pressure and moderate temperatures using mining waste from asbestos production from Goiás State, Brazil (S-GO) for two conditions (i.e. stoichiometric conditions (T2E) and acid excess (T2)). Results indicated that the Fe³⁺ content in S-GO acted as a catalyst, due to FeCl₃ hydrolysis in aqueous solutions. Thus, high Mg and Fe extraction efficiency (95 ± 2%), were achieved in the leaching stage for both conditions. The S₁ solid residue was mainly SiO₂ with 90 ± 1% purity content. In the purification stage 91.7 ± 1.9% of Fe_t were removed, however, a loss of Mg of 13.6 ± 2.3% was also detected. On the carbonation stage, high purity hydromagnesite was formed in T2E; this stage had a 85% efficiency, thus, 36.7% of CO₂ was fixed. On T2, excess H₂O and CO₂ promoted dypingite formation and reduced hydromagnesite formation. After carbonation, the formation of crystals was observed in the NH₄Cl aqueous solution at 25 °C, indicating NH₄Cl supersaturation. The results of mass balance indicate that 4 ton of mineral waste will be employed for each ton of captured CO₂, as well as 2.6 ton of HCl, and 4.5 ton of NH₄OH. However, 1.7 ton of SiO₂, 0.55 ton of iron oxides, and 2.7 ton of hydromagnesite could be produced.

在pH波动的矿物碳酸中，已经研究了几种酸/碱体系。当前使用的主要酸/碱体系是HCl / NaOH和NH ₄ HSO ₄ / NH ₄ OH。然而，尚未阐明使用HCl / NH ₄ OH系统。这项研究建议评估在大气压力和中等温度下，基于HCl / NH ₄ OH系统的pH摇摆式矿物碳酸化的可行性，该条件是使用来自巴西戈亚斯州（S-GO）的石棉生产中的采矿废料在两种情况下（即化学计量的）条件（T2E）和酸过量（T2））。结果表明，由于FeCl ₃，S-GO中的Fe ³⁺含量起催化剂的作用在水溶液中水解。因此，在两种条件下的浸出阶段均实现了较高的Mg和Fe提取效率（95±2％）。S ₁固体残余物主要是纯度为90±1％的SiO ₂。在纯化阶段，去除了91.7±1.9％的Fe _t，但是，还检测到Mg的损失为13.6±2.3％。在碳化阶段，T2E中形成了高纯度的菱镁矿。该阶段的效率为85％，因此固定了36.7％的CO ₂。在T2上，过量的H ₂ O和CO ₂促进了锂蒙脱石的形成并减少了菱镁矿的形成。碳化后，在25°C的NH ₄ Cl水溶液中观察到晶体的形成，表明NH₄ Cl过饱和。质量平衡的结果表明，每吨捕获的CO ₂将使用4吨矿物废物，以及2.6吨HCl和4.5吨NH ₄ OH。然而，1.7吨的SiO ₂，0.55吨铁氧化物，和2.7吨水菱镁矿的可能产生。