According to the reaction (12) calcium sulphide
What is the common name for hydrated calcium sulphide
, the setting agent for plaster of Paris?
It is known from earlier studies  that oxidation of iron sulphide can occur in semicoke and that calcium sulphide
hydrolyzes easily, and hydrogen sulphide ion in water in turn oxidizes to thiosulphate and sulphate.
Halton Borough Council is now awaiting a scientific report in the New Year which will detail exactly what chemicals have been fo und but large quan-tities of calcium sulphide
waste are belie ved to have been un-earthed.
In this case chemisorption of hydrogen sulphide from the vapor-and-gas mixture in the reactor takes place, and sulphide sulphur in the ash residue occurs mainly as calcium sulphide
However, even the burning residue, so-called black ash, causes environmental concerns, as it contains some organic carbon and decomposable calcium sulphide