Name the depressant which is used to separate ZnS and PbS ores in Froth floatation process.
Sodium cyanide(NaCN) is used to separate ZnS and PbS ores in Froth floatation process.
A depressant is used to separate two sulphide ores like ZnS and PbS. It does so by selectively preventing froth formation of one ore while allowing the other to come up with froth.
When NaCN is added to ZnS and PbS ores, NaCN complexes with ZnS to form Na2[Zn(CN)4] which settles at the bottom while PbS floats with the froth, hence can be separated.