Originally Posted by macropod

You could use a field construction like:
{=INT({MERGEFIELD Minutes}/60) \# "0' hr '"}{=MOD({MERGEFIELD Minutes},60) \# "0' min'"}
or
{=INT(«Minutes»/60) \# "0' hr '"}{=MOD(«Minutes»,60) \# "0' min'"}
where 'Minutes' is your datafield name.

NOTE: The field brace pairs (i.e. '{ }') for the above field code examples are created in the mailmerge main document itself, via Ctrl-F9 (Cmd-F9 on a Mac); you can't simply type them or copy & paste them from here. Nor is it practicable (for the most part) to add them via the standard Word dialogues. Likewise, the chevrons (i.e. '« »') - are part of the actual mergefields, inserted via the 'Insert Merge Field' dropdown (i.e. you can't type them or copy & paste them from here). The spaces shown in the field constructions are all required.