Which of the following statements are correct?

In the concentration of galena ore, sodium cyanide is added as a depressant for zinc sulphide $(ZnS)$. $NaCN$ forms a layer of zinc complex and deposits on the surface of $ZnS$ while prevents it for the formation of froth while $PbS$ forms a froth. Thus, by using depressants two sulphide ores can be separated. 

The solidified copper obtained from reverberatory furnace has blistered appearance due to evolution of $S{O}_2$ during the extraction. Therefore, it is called blistered copper. 

Zinc is extracted first by roasting and then by reduction with carbon.

Copper matte contains copper sulfide and iron sulfide.

Hence, the correct options are (A) and (C).