About: http://webisa.webdatacommons.org/42092829

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	After the step S2, the solution thus filtered is added with hydrogen sulfide (H2 S) such that metal contaminants such as Cu, W, Mo, and the like, are removed from the solution by causing a precipitation.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com