I am trying to get a throughput value from a time to volume ratio.

For example;
I have the working time of 1:15 and want to divide my volume of 3200 into it
to get a through put value.

What i would really like is to figure out a way to convert time formats from
the standard HH:MM to just minutes, ie: 1:15 (1 hour 15 minutes) to be 75
minutes.