Understanding and enhancing the stability of arsenic by-product from sulphidization process for arsenic removal in metallurgical waste streams

火法冶金工艺，如焙烧、熔炼和吹炼，是从硫化矿石中提取金属的主要部分。这些过程产生的废气含有大量有毒气体，如二氧化硫和重金属。烟气脱硫是将二氧化硫转化为硫酸产品的必要步骤。同时，作为废物副产物产生了负载有从废气中洗涤的金属和污染物的弱酸性废物流。在这些污染物中，特别重要的是来自含砷矿石加工的砷（As），砷浓度通常为g/L的量级。这是一个非常大的砷量，远远超过了全球对该元素的需求。因此，酸性工厂废水处理主要是废物管理问题，其中应考虑两个关键因素：质量体积比和废物副产品的稳定性。为了解决砷管理的挑战，硫化过程中提出了产生的含砷废物的副产品相比，现有的替代品最少的体积。该工艺通过以砷含量高达60%的三硫化砷的形式沉淀砷来去除砷。然而，三硫化二砷的稳定性令人担忧，因为这种废物副产品中砷的释放和流动对周围的沃茨和土壤构成环境风险。本研究的目的是研究三硫化二砷在各种条件下的稳定性，特别是与现场安全储存相关的条件。这一信息将有助于开发硫化工艺，以管理含砷冶金废物流。

Pyrometallurgical processes, such as roasting, smelting and converting, are a major part of metal extraction from sulfide ores. Off-gases from these processes contain high quantities of toxic gases such as sulphur dioxide and heavy metals. Flue gas desulphurization is a necessary step in which sulphur dioxide is converted to sulphuric acid as the product in the sulphuric acid plant. Meanwhile, a weakly acidic waste stream loaded with metals and contaminants scrubbed from the off-gases is generated as the waste by-product. Of particular importance among these contaminants is arsenic (As) from processing of arsenic-bearing ores, with arsenic concentrations typically on the order of g/L. This is a very large quantity of arsenic and far exceeds the global demand for the element. Therefore, acid plant effluent treatment is primarily a matter of waste management where two crucial factors should be considered: mass to volume ratio and stability of the waste by-product. To address the arsenic management challenge, a sulphidization process is proposed that generates the least volume of arsenical waste by-product compared to existing alternatives. This process removes arsenic by precipitating it in the form of arsenic trisulphide with arsenic content as high as 60%. However, the stability of arsenic trisulphide is a concern because the release and mobilization of arsenic from this waste by-product poses environmental risks to the surrounding waters and soil. The objective of this research is to examine the stability of arsenic trisulphide under a variety of conditions specifically those relevant to safe storage in the field. This information will assist in developing the sulphidization process to manage arsenic-bearing metallurgical waste streams.**