EXHIBIT 3.15


                            CERTIFICATE OF AMENDMENT

                                       TO

                      RESTATED CERTIFICATE OF INCORPORATION

                                       OF

                           NORTH AMERICAN SALT COMPANY

                  The undersigned officers, Robert E. Fowler, Jr. and Rose Marie
Williams, President and CEO, and Secretary, respectively of North American Salt
Company, a corporation organized and existing under the General Corporation Law
of the State of Delaware (the "Corporation"), do hereby certify that:

1.   Paragraph FIRST of the Restated Certificate of Incorporation of the
     Corporation is hereby amended in its entirety as follows:

               "FIRST: The name of the corporation is IMC Salt Inc."

2.   This Certificate of Amendment was duly adopted by the sole director and
     sole voting stockholder of the Corporation according to the provisions of
     Sections 141(f), 229 and 242 of the General Corporation Law of the State of
     Delaware.

                  IN WITNESS WHEREOF, the undersigned have hereunto subscribed
their names this 1st day of May, 1998.

                                 NORTH AMERICAN SALT COMPANY


                                 By:
                                    --------------------------------------------
                                    Robert E. Fowler, Jr.



ATTEST:


- ----------------------------------
Rose Marie Williams
Secretary