If you start Excel then do File | Open and point to a .txt file, you
will be taken automatically into the Data Import Wizard - here you can
specify the start row for the import (up to 32k). If you leave this
blank then Excel will start on row 1 and will import up to 64k (65536
rows). If you import it again starting at 32k (32768) you will then be
able to import from 32k to 96k into a different workbook.

You can either delete the last 32k rows in the first workbook, or the
first 32k rows in the second workbook, and then copy the second
worksheet into the first workbook.

If your text file is named .csv, you should rename it to .txt.

Hope this helps.

Pete