Which process is used to convert hydrated alumina into anhydrous alumina?

Consider the following statements:
Roasting is carried out to:
$(i)$ convert sulphide to oxide and sulphate
$(ii)$ remove water of hydration
$(iii)$ melt the ore
$(iv)$ remove arsenic and sulphur impurities
Of these statements:

The processes of calcination and roasting in metallurgical industries,respectively,can lead to :-

Roasting involves

Extraction of zinc from zinc blende $(ZnS)$ is achieved by:

Heating of pyrites in air for oxidation of sulphur is called