The removal of heavy metals, especially cadmium, from wet phosphoric acid is still a challenging stage during the manufacturing of phosphate fertilizers. In this work, a novel approach was developed to improve the performance of the sulfide precipitation process as a purification technique. This is based on NaHS rather than Na₂S as a precipitating agent in both batch and continuous modes for cadmium removal from synthetic wet phosphoric acid. First, the respective performance of Na₂S and NaHS was compared in the batch mode. NaHS was shown to improve decadmiation in comparison to Na₂S even though the same trends were observed for both precipitating agents as a function of operating conditions. An increase in Sulfur/Cd²⁺ molar ratio improved cadmium sulfide precipitation. Conversely, increasing temperature and phosphoric acid concentration impaired the effectiveness of cadmium removal efficiency. An apparent kinetic model was developed taking into consideration the reaction mechanisms and supersaturation to predict the residual cadmium concentration in phosphoric acid solutions. The feasibility of the continuous process based on NaHS was also assessed. The results showed that a residence time of 40 min was needed to achieve 85.6 % of Cd²⁺ elimination at 25 °C. As aggregation seemed to be the main mechanism governing particle size, this increased with the Sulfur/Cd²⁺ ratio, which could improve downstream solid separation. Eventually, these findings of this study provide useful insights into the feasibility of chemical precipitation using NaHS as a technology of phosphoric acid decadmiation in the industry.

从湿磷酸中去除重金属，尤其是镉，仍然是磷肥生产过程中的一个具有挑战性的阶段。在这项工作中，开发了一种新方法来提高硫化物沉淀工艺作为纯化技术的性能。这是基于 NaHS 而不是 Na ₂ S 作为沉淀剂，以间歇和连续模式从合成湿磷酸中去除镉。首先，在批处理模式下比较了Na ₂ S和NaHS各自的性能。_{与 Na 2} S相比，NaHS 被证明可以改善脱镉，尽管对于两种沉淀剂都观察到作为操作条件的函数的相同趋势。硫/镉^2+增加摩尔比改善了硫化镉的沉淀。相反，提高温度和磷酸浓度会降低镉去除效率的有效性。考虑到反应机理和过饱和度，开发了一个表观动力学模型来预测磷酸溶液中的残留镉浓度。还评估了基于 NaHS 的连续工艺的可行性。结果表明，在 25 °C时需要 40 分钟的停留时间才能实现 85.6% 的 Cd ^2+消除。由于聚集似乎是控制粒径的主要机制，这随着硫/镉^{2+的增加而增加}比，这可以改善下游的固体分离。最终，本研究的这些发现为工业中使用 NaHS 作为磷酸脱镉技术进行化学沉淀的可行性提供了有用的见解。