Investigation of chemical associations and leaching behavior of heavy metals in sodium sulfide hydrate stabilized stainless steel pickling sludge

Add time:08/15/2019    Source:sciencedirect.com

This article presents an original study on stabilization of heavy metals in SSPS using sodium sulfide hydrate. The speciation and pH dependent leaching of the target heavy metals (Cr, Cu, Ni and Zn) based on GB 5085.3 and GB 16889 in both raw SSPS and stabilized products were examined. Results indicated that Cr and Ni are the two main toxic elements in SSPS. The BCR sequential extraction indicated that 55.2% of Cr in raw SSPS exist as Fe-Mn oxides, while water soluble Cr which is mainly consists of Cr(VI) accounts for 3.50%. After stabilization, the residual fraction Cr reached to more than 60% and Cr(VI) was not detected. The leaching concentration of Ni meets the limit of reuse SSPS, meanwhile, the sum proportion of sulfides and residual Ni increased from 8.68% to a maximum value of 31.82%. pH dependent leaching tests expound that the leaching concentrations of Cr, Ni, Cu and Zn are significantly high at pH = 2. The leaching concentrations of Cu, Ni and Zn are extremely low when pH varied from 7 to 13. The best stabilization pH span is from 5.5 to 10 for SSPS. The XRD and SEM-EDS analysis showed that the major compounds in treated SSPS were bassanite and plaster of Paris (POP). Since the extreme conditions such as pH = 2 or pH = 13 are infrequently, the stabilized SSPS can be safely reused in roadbed materials, bricks and concrete aggregates based on China HJ/T 301.

We also recommend Trading Suppliers and Manufacturers of SODIUM SULPHIDE HYDRATE (cas 1313-84-4). Pls Click Website Link as below: cas 1313-84-4 suppliers

Prev:Preparation & Characterization of Sodium Sulfide Hydrates for Application in Thermochemical Storage Systems☆
Next:Strength and hydration products of cemented paste backfill from sulphide-rich tailings using reactive MgO-activated slag as a binder)