<PAGE>
                                                                     Exhibit 4.6

                           SECOND AMENDED AND RESTATED

                                 TRUST AGREEMENT

                                       OF

                               PD CAPITAL TRUST I

         THIS SECOND AMENDED AND RESTATED TRUST AGREEMENT OF PD CAPITAL TRUST I
is dated as of April 18, 2003 (this "Trust Agreement"), by and among Phelps
Dodge Corporation, a New York corporation, as depositor (the "Depositor"),
Wachovia Bank, National Association (formerly known as First Union National
Bank), a national banking association, as property trustee (the "Property
Trustee") and Wachovia Trust Company, National Association (formerly known as
the First Union Trust Company, N.A.), a national association as Delaware trustee
(the "Delaware Trustee") (jointly with the Property Trustee, the "Trustees") and
amends and restates in entirety the Amended and Restated Trust Agreement, dated
as of August 1, 2001, by and among the parties hereto, which amended and
restated the Trust Agreement, dated as of August 3, 2000, by and among the
parties hereto, pursuant to which a certificate of trust was filed with the
Secretary of State of the State of Delaware. The Depositor and the Trustees
hereby agree as follows:

         1. The trust created hereby shall be known as "PD Capital Trust I" (the
"Trust"), in which name the Trustees or the Depositor, to the extent provided
herein, may conduct the business of the Trust, make and execute contracts, and
sue and be sued.

         2. The Depositor hereby assigns, transfers, conveys and sets over to
the Trust the sum of $10. Such amount shall constitute the initial trust estate.
It is the intention of the parties hereto that the Trust created hereby
constitute a statutory trust under Chapter 38 of Title 12 of the Delaware Code,
12 Del. C. Section 3801, et seq. (the "Statutory Trust Act"), and that this
document constitute the governing instrument of the Trust. The Trustees are
hereby authorized and directed to execute and file a certificate of trust with
the Secretary of State of the State of Delaware in such form as the Trustees may
approve.

         3. The Depositor and the Trustees will enter into an amended and
restated Trust Agreement satisfactory to each such party to provide for the
contemplated operation of the Trust created hereby and the issuance of the
preferred securities and common securities referred to therein. Prior to the
execution and delivery of such amended and restated Trust Agreement, the
Trustees shall not have any duty or obligation hereunder or with respect of the
trust estate, except as otherwise contemplated by this Trust Agreement, required
by applicable law or as may be necessary to obtain prior to such execution and
delivery any licenses, consents or approvals required by applicable law or
otherwise.
<PAGE>
         Notwithstanding the foregoing, the Trustees may take all actions deemed
proper as are necessary to effect the transactions contemplated herein.

         4. The Depositor, as agent of the Trust, is hereby authorized (i) to
prepare and file with the Securities and Exchange Commission (the "Commission")
and to execute, in the case of the 1933 Act Registration Statement and 1934 Act
Registration Statement (as herein defined), on behalf of the Trust, (a) one or
more Registration Statements (each a "1933 Act Registration Statement"),
including all pre-effective and post-effective amendments thereto, and any
registration statement filed in accordance with Rule 462(b) of the Securities
Act of 1933, as amended (the "1933 Act"), relating to the registration under the
Securities Act of the preferred securities of the Trust, (b) any preliminary
prospectus or prospectus or supplement thereto relating to the preferred
securities of the Trust required to be filed pursuant to the 1933 Act, and (c)
one or more Registration Statements on Form 8-A or other appropriate form (each
a "1934 Act Registration Statement"), including all pre-effective and
post-effective amendments thereto, relating to the registration of the preferred
securities of the Trust under the Securities Exchange Act of 1934, as amended;
(ii) if and at such time as determined by the Depositor, to file with the New
York Stock Exchange or other exchange, or the National Association of Securities
Dealers ("NASD"), and execute on behalf of the Trust one or more listing
applications and all other applications, statements, certificates, agreements
and other instruments as shall be necessary or desirable to cause the preferred
securities of the Trust to be listed on the New York Stock Exchange or such
other exchange, or the NASD's Nasdaq National Market; (iii) to file and execute
on behalf of the Trust, such applications, reports, surety bonds, irrevocable
consents, appointments of attorney for service of process and other papers and
documents that shall be necessary or desirable to register the preferred
securities of the Trust under the securities or "blue sky" laws of such
jurisdictions as the Depositor, on behalf of the Trust, may deem necessary or
desirable; (iv) to execute and deliver letters or documents to, or instruments
for filing with, a depository relating to the preferred securities of the Trust;
and (v) to execute, deliver and perform on behalf of the Trust one or more
underwriting agreements with one or more underwriters relating to the offering
of the preferred securities of the Trust. In the event that any filing referred
to in this Section 4 is required by the rules and regulations of the Commission,
the New York Stock Exchange or other exchange, NASD, or state securities or
"blue sky" laws to be executed on behalf of the Trust by the Trustees, the
Trustees, in their capacity as trustees of the Trust, are hereby authorized to
join in any such filing and to execute on behalf of the Trust any and all of the
foregoing.

         5.   This Trust Agreement may be executed in one or more counterparts.
<PAGE>
         6. The number of trustees of the Trust initially shall be two and
thereafter the number of trustees of the Trust shall be such number as shall be
fixed from time to time by a written instrument signed by the Depositor which
may increase or decrease the number of trustees of the Trust; provided, however,
that to the extent required by the Statutory Trust Act, one trustee of the Trust
shall either be a natural person who is a resident of the State of Delaware or,
if not a natural person, an entity which has its principal place of business in
the State of Delaware and otherwise meets the requirements of applicable law.
Subject to the foregoing, the Depositor is entitled to appoint or remove without
cause any trustee of the Trust at any time. Any trustee of the Trust may resign
upon thirty days' prior written notice to the Depositor.

         7. The Depositor hereby agrees to (i) reimburse the Trustees for all
reasonable expenses (including reasonable fees and expenses of counsel and other
experts) and (ii) indemnify, defend and hold harmless the Trustees and any of
the officers, directors, employees and agents of the Trustees (the "Indemnified
Persons") from and against and all losses, damages, liabilities, claims,
actions, suits, costs, expenses, disbursements (including the reasonable fees
and expenses of counsel), taxes and penalties of any kind and nature whatsoever
(collectively, "Expenses"), to the extent that such Expenses arise out of or are
imposed upon or asserted at any time against such Indemnified Persons with
respect to the performance of this Trust Agreement, the creation, operation or
termination of the Trust or the transactions contemplated hereby; provided,
however, that the Depositor shall not be required to indemnify any Indemnified
Person for any Expenses which are a result of the willful misconduct, bad faith
or gross negligence of such Indemnified Person.

         8. The Trust may be dissolved and terminated before the issuance of the
preferred securities of the Trust at the election of the Depositor.

         9. This Trust Agreement shall be governed by, and construed in
accordance with, the laws of the State of Delaware (without regard to conflict
of laws principles).
<PAGE>
         IN WITNESS WHEREOF, the parties hereto have caused this Trust Agreement
to be duly executed as of the day and year first above written.

                                     PHELPS DODGE CORPORATION,
                                     as Depositor

                                     By:  /s/ GREGORY W. STEVENS
                                          -----------------------------------
                                          Name:  Gregory W. Stevens
                                          Title: Vice President and Treasurer


                                     WACHOVIA TRUST COMPANY,
                                     NATIONAL ASSOCIATION (formerly known
                                     as First Union Trust Company, N.A.),
                                     as Delaware Trustee

                                     By:  /s/ STERLING C. CORREIA
                                          -----------------------------------
                                          Name:  Sterling C. Correia
                                          Title: Vice President


                                     WACHOVIA BANK, NATIONAL ASSOCIATION
                                     (formerly known as First Union
                                     National Bank), as Property Trustee

                                     By:  /s/ KEVIN M. DOBRAVA
                                          -----------------------------------
                                          Name:  Kevin M. Dobrava
                                          Title: Vice President