I don't believe you can sort the file sample you gave in the way you expect it to be sorted using just sort command. Sort command does depend on a field separator, which is a space or a tab character unless otherwise specified.
In your example, you are expecting sort to recognize a certain range of characters (say 10-to-19 for the employee number) as a field. It is not going to happen as far as my understanding of sort man pages go.
You will need to use some interim parsing of the input file, otherwise all the spaces trailing any line, in the first field is going to be interpreted as a field separator and your first key field for sort is going to be the employee number, whereas when the line starts with that digit "8" your employee number will be key field 2. So, as JRF said, you have non-uniform fields for sort to interpret. And to be perfectly honest, JRF's solution, using awk in conjunction with sort is the most elegant solution you can come up with in your case. If the pipes in that command chain is not working due to the large input file size, the only thing you can do is to parse that command into separate commands and create interim files as you go. That should give you some flexibility.
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UNIX because I majored in cryptology...
