I suggest you try using a relational database to do the job for you. I'm not claiming that this will work for datasets as large as yours, but give it a try.

MySQL sample code:

CREATE DATABASE sorter;
USE sorter;
CREATE TABLE t619575 (
  c01 varchar(2), -- SK
  c02 integer,    -- 1242
  c03 integer,    -- 0180010100
  c04 varchar(3), -- AAR
  c05 varchar(3), -- CPH
  c06 varchar(3), -- AAR
  c07 integer,    -- 0735
  c08 varchar(3), -- CPH
  c09 integer,    -- 0810001
  c10 bigint(25), -- 20070521200705211
  c11 varchar(2), -- SK
  c12 integer     -- 1242
);

-- Assuming tab separated columns
LOAD DATA LOCAL INFILE '619575.csv'
  INTO TABLE t619575
    FIELDS TERMINATED BY '\t'
      ENCLOSED BY ''
      ESCAPED BY '\\';

-- Add index on the fields to sort
ALTER TABLE t619575 ADD INDEX idx_c02_c03_c04 (c02, c03, c04);

-- Create sorted output
SELECT * 
  INTO OUTFILE '619575.sorted.csv' 
  FROM t619575 
 ORDER BY c02, c03, c04 ;
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Some may claim that MySQL isn't up for this kind of job. If it doesn't, then you might consider downloading the free (as in gratis) versions of Oracle or DB2.