Leaching Behavior and Risk Control of Waste Mercury Chloride Catalyst Through Mechanochemical Reaction Using Sulfur

Abstract

A large volume of waste mercury chloride catalyst (HgCl 2 ) is generated by calcium carbide-based polyvinyl chloride production in China, which accounts for 30% of global mercury consumption. However, there are few studies on the leaching behavior and risk control of waste catalyst where mercury is in the form of HgCl 2 , which is more soluble than metal mercury and poses great threat to human health and environment. This study investigated mechanochemical stabilization and leaching behavior of waste mercury catalyst using sulfur as additive. We found that mercuric sulfide (HgS) formed through mechanical milling, although the reaction between HgCl 2 and S is not thermodynamically favored. Moreover, toxicity characteristic leaching procedure (TCLP) results showed mercury leaching values are lower than the TCLP limit value of 0.2 mg/L after mechanochemical treatment. Results of sequential extraction procedure showed that ball mill could transfer more than 99.9% of the Hg in the catalyst to the least mobile fraction.

Methods review of recycling mercury from waste mercury chloride catalyst of PVC production

“…The recovery of Hg was over 99.9%, solventⅠand solvent Ⅱ all could recycle, and mercury content in the catalyst was less than 0.01%. Jianxin Zhu [12][13] added sodium sulphide for additives by means of mechanical ball mill to solidify and stabilize waste mercury catalyst. Mercury leaching value was lower than the United States environmental protection standard limit of 0.2 mg/L of hazardous wastes and the Chinese national hazardous waste identification standard limit of 0.1 mg/L.…”

Calcium‐Based Sustainable Chemical Technologies for Total Carbon Recycling

“…[188] Mercury chloride catalystw aste (HgCl 2 )s pontaneously forms through catalyste rosion in the presence of hydrogen chloride and acetylene during PVC manufacturing. [189] It can further transform into differentc hemical species of mercury. [190] Although PVC is produced from acetylene without direct involvement of calcium carbide, the manufacturing processesa re frequently combined to facilitatet heir optimization.…”

Non-Thermal Plasma Technology for Further Purification of Flue Gas in the Resource Utilization Process of Waste Mercury Catalyst: A Case Study in Xinjiang, China

“…invented a technology for treating waste mercury catalysts using hydrometallurgy. Ren et al [14] utilized ball mills to immobilize mercury in waste mercury catalysts by grinding it with sulfur, but their widespread application has not been observed. Distillation is the central component of the entire resource utilization process, and the distillation furnace is a sealed structure.…”