Expanding Datatable to a Dictionary of datatables

Question

I have a Parent Datatable that contains 4.5 records, I want to now create Dictionary of datatables from Parent Datatable until all records are process each table should have no more than the max number of records. At the end I want iterate through the dictionary of tables and export to a textfile. I am doing this becuase I am getting a system out of memory exception writing 4.5 million records to an textfile, so I now have to break up into pieces until all records are process.

any ideals?