<PAGE>

                               AMENDMENT NO. 4 TO
                           LOAN AND SECURITY AGREEMENT

         THIS AMENDMENT NO. 4 TO LOAN AND SECURITY AGREEMENT, dated as of June
11, 1999, is by and among The Doe Run Resources Corporation, a New York
corporation ("Doe Run"), Fabricated Products, Inc., a Delaware corporation
("Fabricated Products", and together with Doe Run, collectively, "Borrowers")
and Congress Financial Corporation, a Delaware corporation ("Lender").


                              W I T N E S S E T H:
                              - - - - - - - - - -


         WHEREAS, Lender has entered into financing arrangements with Borrowers
pursuant to which Lender has made and may make loans and advances and provide
other financial accommodations to Borrowers as set forth in the Loan and
Security Agreement, dated March 12, 1998, by and among Lender and Borrowers, as
amended pursuant to Amendment No. 1 to Loan and Security Agreement, dated
September 1, 1998, Amendment No. 2 to Loan and Security Agreement, dated as of
January 13, 1999, and Amendment No. 3 to Loan and Security Agreement, dated as
of February 1, 1999, as further amended by this Amendment No. 4 to Loan and
Security Agreement (this "Amendment", and together with the foregoing described
agreements, as the same may hereafter be further amended, modified,
supplemented, extended, renewed, restated or replaced, the "Loan Agreement") and
the agreements, documents and instruments referred to therein or at any time
executed and/or delivered in connection therewith or related thereto (all of the
foregoing, together with the Loan Agreement, as the same now exists or may
hereafter be amended, modified, supplemented, extended, renewed, restated or
replaced, being collectively referred to herein as the "Financing Agreements");

         WHEREAS, Doe Run has entered into certain agreements to purchase a Bell
model 412EP helicopter ("Helicopter No. 36213"; as hereinafter further defined)
from Bell Helicopter Textron Inc. as set forth in the Helicopter Purchase
Agreements (as hereinafter defined) and the Boeing Loan Documents (as
hereinafter defined);

         WHEREAS, in connection with that transaction, Borrowers have requested
that, among other things, Lender (a) permit Doe Run to establish a new
Subsidiary for the purpose of, among other things, acquiring title to Helicopter
No. 36213, (b) permit Doe Run to guarantee the obligations of that new
Subsidiary to Boeing Capital Corporation, (c) permit Doe Run to incur certain
Indebtedness to Bell Helicopter Textron, Inc., and (d) enter into certain
amendments to the Loan Agreement in connection with such transactions, and
Lender is willing to agree to the foregoing, subject to the terms and conditions
contained in this Amendment;

         NOW, THEREFORE, in consideration of the mutual conditions and
agreements and covenants set forth herein, and for other good and valuable
consideration, the adequacy and sufficiency of which are hereby acknowledged,
the parties hereto agree as follows:



<PAGE>

         1.  DEFINITIONS.

         1.1 ADDITIONAL DEFINITIONS. As used herein, the following terms shall
have the respective meanings given to them below and the Loan Agreement shall be
deemed and is hereby amended to include, in addition and not in limitation of,
each of the following definitions:

                  (a) "AERO TRANSPORTE" shall mean Aero Transporte, S.A., a
sociedad anonima organized under the laws of Peru, and its successors and
assigns, or any successor or replacement Peruvian air transport company
appointed in accordance with the terms of the Helicopter Purchase Agreements and
the Boeing Loan Documents.

                  (b) "BELL TEXTRON" shall mean Bell Helicopter Textron Inc., a
Delaware corporation, and its successors and assigns.

                  (c) "BELL TEXTRON INDEMNITY" shall mean the Indemnity
Agreement, dated as of June 11, 1999, by Doe Run in favor of Bell Textron, as
the same now exists or may hereafter be amended, modified, supplemented,
extended, renewed, restated or replaced.

                  (d) "BELL TEXTRON SELLER NOTE" shall mean the Promissory Note,
dated as of June 11, 1999, issued by Doe Run to Bell Textron in the maximum
principal amount of up to $4,574,600, as the same now exists or may hereafter be
amended, modified, supplemented, extended, renewed, restated or replaced.

                  (e) "BOEING" shall mean Boeing Capital Corporation, a Delaware
corporation, and its successors and assigns.

                  (f) "BOEING GUARANTY" shall mean the Guaranty, dated as of
June 11, 1999, by Doe Run in favor of Boeing with respect to the obligations of
First Security under the Boeing Note, as the same now exists or may hereafter be
amended, modified, supplemented, extended, renewed, restated or replaced.

                  (g) "BOEING LOAN DOCUMENTS" shall mean, individually and
collectively, (i) the Loan and Security Agreement, dated as of June 11, 1999, by
and between First Security, and Boeing, (ii) the Boeing Guaranty, (iii) the
Boeing Note, (iv) the Assignment of Rent, dated as of June 11, 1999, between Jet
Aviation and Aero Transporte, and (v) any other agreements, documents or
instruments executed or delivered in connection therewith, as the same now exist
or may hereafter be amended, modified, supplemented, extended, renewed, restated
or replaced.

                  (h) "BOEING NOTE" shall mean the Promissory Note, dated as of
June 11, 1999, issued by First Security to Boeing in the maximum principal
amount of $5,900,000, as the same now exists or may hereafter be amended,
modified, supplemented, extended, renewed, restated or replaced.

                  (i) "FIRST SECURITY" shall mean First Security Bank, N.A., a
national banking association organized under the laws of the United States of
America, in its capacity as trustee


                                      - 2 -
<PAGE>

under the Helicopter Trust Agreement, and its successors and assigns, together
with any successor or replacement trustee appointed in accordance with the
Helicopter Trust Agreement.

                  (j) "HELICOPTER NO. 36213" shall mean the Bell 412EP
Helicopter Aircraft, Serial Number 36213, FAA Registration Number N426DR,
together with the engines attached thereon and the other equipment and material
incorporated therein, all as described more particularly in the Helicopter
Purchase Agreements.

                  (k) "HELICOPTER PURCHASE AGREEMENTS" shall mean,
individually and collectively, (i) the Purchase Agreement, dated February 16,
1999, between Bell Textron, as seller, and Doe Run, as purchaser, (ii) the
Assignment of Purchase Agreement, dated as of June 11, 1999, among Bell
Textron, Doe Run and First Security, (iii) the Trust Agreement, (iv) Aircraft
Lease Agreement, dated as of June 11, 1999, by and between Jet Aviation, as
lessor, and Aero Transporte, as lessee, (v) the Bell Textron Indemnity
Agreement, (vi) the Escrow Agreement, dated June 9, 1999 by and between
Morgan Aircraft Title Services, Inc, as escrow agent, Doe Run and Bell
Textron, (vii) the Aircraft Management Services Agreement, dated June 11,
1999, between First Security and Jet Aviation, (viii) the Air Transportation
Service Agreement, dated June11, 1999, between Doe Run Peru and Aero
Transporte, and (ix) any other agreements, documents or instruments executed
or delivered in connection therewith, as all of the foregoing now exist or
may hereafter be amended, modified, supplemented, extended, renewed, restated
or replaced.

                  (l) "HELICOPTER PURCHASE PRICE" shall mean the amount of not
more than $5,900,000.

                  (m) "HELICOPTER TRUST" shall mean Bell 412 Peru Trust No. 1
created pursuant to the Helicopter Trust Agreement, and its successors and
assigns, together with any successor or replacement trust.

                  (n) "HELICOPTER TRUST AGREEMENT" shall mean the Trust
Agreement, dated as of June 11, 1999, between Doe Run and First Security, as the
same now exists or may hereafter be amended, modified, supplemented, extended,
renewed, restated or replaced.

                  (o) "JET AVIATION" shall mean Jet Aviation Business Jets,
Inc., a Maryland corporation, and its successors and assigns.

         1.2 AMENDMENTS TO DEFINITIONS. All references to the term "Subsidiary"
or "subsidiary" in the Loan Agreement and the other Financing Agreements shall
be deemed and each such reference is hereby amended to mean any corporation,
association or organization, active or inactive, as to which more than fifty
(50%) percent of the outstanding voting stock or shares or interests shall now
or hereafter be owned or controlled, directly or indirectly, by a Borrower, any
subsidiary of Borrower, any subsidiary of a Borrower, or any subsidiary of each
subsidiary; PROVIDED, THAT, (a) the term "Subsidiary" as used elsewhere in the
Loan Agreement, as to Doe Run, shall not include Doe Run Cayman and its
Subsidiaries or DR Exploration Company (Proprietary) Ltd. (South Africa), except
(i) as otherwise expressly provided in any specific


                                      - 3 -
<PAGE>

section of the Loan Agreement, (ii) for purposes of Section 5.1(b) hereof, and
(iii) for purposes of this definition and (b) the term "Subsidiary" as used
elsewhere in the Loan Agreement shall include neither First Security nor the
Helicopter Trust.

         1.3 INTERPRETATION. For purposes of this Amendment, all terms used
herein, including but not limited to, those terms used or defined in the
recitals hereto shall have the respective meanings assigned thereto in the Loan
Agreement.

         2. CONSENTS. Subject to the terms and conditions contained herein,
Lender hereby consents to the following:

                  (a) the formation of the Helicopter Trust pursuant to the
Helicopter Trust Agreement;

                  (b) the transfer by Doe Run to First Security of all of the
right, title and interest of Doe Run in and to the Helicopter Purchase
Agreements as in effect on the date hereof (other than the Helicopter Trust
Agreement and the Bell Textron Indemnity), including, without limitation, the
sale and transfer by Doe Run to First Security of Helicopter No. 36213 in
accordance with the terms Helicopter Purchase Agreements as in effect on the
date hereof and with the Boeing Loan Documents as in effect on the date hereof;

                  (c) the payment by Doe Run to First Security of the reasonable
cost, fees and expenses of First Security in an amount not to exceed $10,000 in
any calendar year payable in accordance with the Helicopter Trust Agreement as
in effect on the date hereof;

                  (d) the contingent, unsecured Indebtedness of Doe Run to Bell
Textron evidenced by the Bell Textron Seller Note as in effect on the date
hereof;

                  (e) the contingent, unsecured guarantee by Doe Run in favor of
Boeing with respect to the secured Indebtedness of First Security to Boeing
arising under the Boeing Loan Documents as set for in the Boeing Guaranty as in
effect on the date hereof;

                  (f) the indemnification by Doe Run in favor of First Security
as set forth in Sections 4.06 and 6.01 of the Helicopter Trust Agreement as in
effect on the date hereof; and

                  (g) the direct and indirect payments by Doe Run Peru arising
under the Helicopter Purchase Agreements as in effect on the date hereof and
under the Boeing Loan Documents as in effect on the date hereof.

         3.  AMENDMENTS.

         3.1 INDEBTEDNESS. Section 6.3 of the Loan Agreement is hereby amended
by adding new Sections 6.3(n), (o), (p) and (q) immediately after Section
6.3(m), as follows:


                                      - 4 -
<PAGE>

                  "(n) the contingent, unsecured Indebtedness of Doe Run to Bell
         Textron evidenced by the Bell Textron Seller Note (as in effect on the
         execution and delivery date thereof); PROVIDED, THAT,

                           (i)      such Indebtedness is and shall be unsecured;

                           (ii)     such Indebtedness shall not exceed
                                    $4,574,000;

                           (iii)    Doe Run shall not, directly or indirectly,
                                    make any payments in respect of such
                                    Indebtedness, including, but not limited to,
                                    any prepayments or other non-mandatory
                                    payment without the prior written consent of
                                    Lender, except to the extent such payments
                                    are made using proceeds of the loan made
                                    under the Boeing Loan Documents as in effect
                                    on the execution and delivery date thereof;

                           (iv)     Doe Run shall not, directly or indirectly,
                                    (A) amend, modify, alter or change any terms
                                    of such Indebtedness or any of the
                                    provisions of any agreement, document or
                                    instrument to the extent such provision
                                    governs or affects the Indebtedness or as
                                    otherwise permitted herein or consented to
                                    in writing by Lender, or (B) except to the
                                    extent permitted in this Section 6.3(n),
                                    redeem, retire, defease, purchase or
                                    otherwise acquire such Indebtedness, or set
                                    aside or otherwise deposit or invest any
                                    sums for such purpose; and

                           (v)      Doe Run shall furnish to Lender all notices
                                    or demands in connection with such
                                    Indebtedness either received by Doe Run or
                                    on its behalf, promptly after the receipt
                                    thereof, or sent by Doe Run or on its
                                    behalf, concurrently with the sending
                                    thereof, as the case may be;

                  (o) the contingent, unsecured Indebtedness of Doe Run to
         Boeing arising under the Boeing Guaranty; PROVIDED, THAT,

                           (i)      such Indebtedness shall not be secured by
                                    any assets of Borrowers or any of their
                                    Subsidiaries;

                           (ii)     Doe Run shall not, directly or indirectly,
                                    (A) amend, modify, alter or change any terms
                                    of such Indebtedness or any of the
                                    provisions of any agreement, document or
                                    instrument to the extent such provision
                                    governs or affects such Indebtedness or as
                                    otherwise permitted herein or consented to
                                    in writing by Lender, or (B) redeem, retire,
                                    defease, purchase or otherwise acquire such
                                    Indebtedness, or set aside or otherwise
                                    deposit or invest any sums for such purpose;
                                    and


                                      - 5 -
<PAGE>

                           (iii)    Doe Run shall furnish to Lender all notices
                                    or demands in connection with such
                                    Indebtedness either received by Doe Run or
                                    on its behalf, promptly after the receipt
                                    thereof, or sent by Doe Run or on its
                                    behalf, concurrently with the sending
                                    thereof, as the case may be;

                  (p) the contingent, unsecured Indebtedness of Doe Run to First
         Security arising under the indemnification by Doe Run in favor of First
         Security as set forth in Sections 4.06 and 6.01 of the Helicopter Trust
         Agreement as in effect on the execution and delivery date thereof;
         PROVIDED, THAT, (i) Doe Run gives Lender written notice promptly after
         First Security takes any action to seek payment in respect of any
         indemnified item as set forth in the Helicopter Purchase Agreements;
         (ii) Lender shall have received not less than ten (10) Business Days'
         prior written notice of the intention of Doe Run to make a payment in
         respect thereof; and (iii) as of the date of and after giving effect to
         such payment, no Event of Default or act, condition or event, which
         with notice or passage of time or both would constitute an Event of
         Default, shall exist or have occurred and be continuing; and

                  (q) the contingent, unsecured Indebtedness of Doe Run to Bell
         Textron arising under the indemnification by Doe Run in favor of Bell
         Textron as set forth in the Bell Textron Indemnity as in effect on the
         execution and delivery date thereof; PROVIDED, THAT, (i) Doe Run gives
         Lender written notice promptly after Bell Textron takes any action to
         seek payment in respect of any indemnified item as set forth in the
         Bell Textron Indemnity; (ii) Lender shall have received not less than
         ten (10) Business Days' prior written notice of the intention of Doe
         Run to make a payment in respect thereof; and (iii) as of the date of
         and after giving effect to such payment, no Event of Default or act,
         condition or event, which with notice or passage of time or both would
         constitute an Event of Default, shall exist or have occurred and be
         continuing."

         3.2  LOANS, INVESTMENTS AND GUARANTEES.

                  (a) Section 6.5 of the Loan Agreement is hereby amended by
adding new Sections 6.5(r), (s) and (t), as follows:

                  "(r) the transfer by Doe Run to First Security of all of the
         right, title and interest of Doe Run in and to the Helicopter Purchase
         Agreements as in effect on the execution and delivery date thereof
         (other than the Helicopter Trust Agreement and the Bell Textron
         Indemnity), including, without limitation, the sale and transfer by Doe
         Run to First Security of its interest in Helicopter No. 36213 in
         accordance with the terms Helicopter Purchase Agreements as in effect
         on the execution and delivery date thereof;

                   (s) the payment by Doe Run Peru in respect of the
         Indebtedness arising under the Boeing Loan Documents in accordance with
         the Helicopter Purchase Agreements as in effect on the execution and
         delivery date thereof and with the


                                      - 6 -
<PAGE>

         Boeing Loan Documents as in effect on the execution and delivery date
         thereof; and

                  (t) the guarantee by Doe Run in favor of Boeing of the
         Indebtedness of First Security evidenced by the Boeing Note as in
         effect on the execution and delivery date thereof permitted hereunder
         as set forth in the Helicopter Guaranty as in effect on the execution
         and delivery date thereof."

                  (b) The acquisition of Helicopter No. 36213, and the financing
of that acquisition, pursuant to the Helicopter Purchase Agreements as in effect
on the date hereof and the Boeing Loan Documents as in effect on the date
hereof, and subject to the terms and conditions set forth in this Amendment,
shall be deemed to and does hereby amend and replace the acquisition and
financing of the helicopter by Doe Run permitted by Section 6.5 as set forth in
Schedule 6.5 to the Loan Agreement, and no other or future acquisitions are
intended or implied pursuant to Section 6.5 and that Schedule 6.5.

         4. REPRESENTATIONS, WARRANTIES AND COVENANTS. In addition to the
continuing representations, warranties and covenants heretofore or hereafter
made by Borrower to Lender pursuant to the other Financing Agreements, each of
Borrowers, jointly and severally, hereby represents, warrants and covenants with
and to Lender as follows (which representations, warranties and covenants are
continuing and shall survive the execution and delivery hereof and shall be
incorporated into and made a part of the Financing Agreements):

         4.1  ACQUISITION OF HELICOPTER NO. 36213.

                  (a) The Helicopter Purchase Agreements and the transactions
contemplated thereunder that are required thereby to be completed on or before
the date hereof, shall have been, substantially contemporaneously with the
execution and delivery of this Amendment, duly executed, delivered and performed
in accordance with their terms by the respective parties thereto in all
respects, including the fulfillment of all conditions precedent set forth
therein. After giving effect to the Helicopter Purchase Agreements and subject
to the Boeing Loan Documents, First Security has acquired good and marketable
title to Helicopter No. 36213.

                  (b) The consummation of the transactions contemplated by the
Helicopter Purchase Agreements and the Boeing Loan Documents shall not result in
the imposition of any lien, security interest or encumbrance on or in any of the
assets of Borrowers or their Subsidiaries.

                  (c) All actions and proceedings required to be taken on or
before the date hereof by the Helicopter Purchase Agreements, applicable law or
regulation (including, without limitation, the Federal Aviation Act laws, being
Title 49 of the United States Code, as amended together with all rules,
regulations and interpretations thereunder or related thereto) have been taken
and the transactions contemplated thereunder required to be consummated on or
before the date hereof have been duly and validly consummated. Borrowers, Doe
Run Peru and First Security have obtained all necessary consents and approvals
of third parties to the transactions


                                      - 7 -
<PAGE>

contemplated by the Helicopter Purchase Agreements and the Boeing Loan Documents
and required thereby to be completed on or before the date hereof, including,
without limitation, the Senior Secured Note Agreements.

                  (d) By no later than August 31, 1999, (i) the transactions
contemplated under the Helicopter Purchase Agreements that are required to be
completed after the date hereof, shall have been performed in accordance with
their terms by the respective parties thereto in all respects, and (ii) all
actions and proceedings required to be taken after the date hereof by the
Helicopter Purchase Agreements, applicable law or regulation shall have been
taken and the transactions contemplated thereunder required to be consummated
after the date hereof will be duly and validly consummated.

                  (e) No court of competent jurisdiction has issued any
injunction, restraining order or other order which prohibits consummation of the
transactions described in the Helicopter Purchase Agreements or in the Boeing
Loan Documents and, to the best of Borrower's knowledge, no governmental or
other action or proceeding has been threatened or commenced, seeking any
injunction, restraining order or other order which seeks to void or otherwise
modify the transactions described in the Helicopter Purchase Agreements.

                  (f) Doe Run shall not permit the Helicopter Trust to conduct
any business or engage in any commercial activities, except to the extent
required by and as specified in the Helicopter Trust Agreement as in effect on
the date hereof.

                  (g) This Amendment has been duly executed and delivered by
Borrowers and is in full force and effect as of the date hereof and the
agreements and obligations of Borrowers contained herein constitute legal, valid
and binding obligations of Borrowers enforceable against Borrowers in accordance
with their respective terms.

                  (h) Borrowers have delivered, or caused to be delivered, to
Lender true, correct and complete copies of the Helicopter Purchase Agreements
and of the Boeing Loan Documents.

                  (i) No Event of Default or act, condition or event, which with
notice or passage of time or both would constitute an Event of Default, exists
or has occurred and is continuing (after giving effect to the amendments made
and the consents given by Lender under this Amendment.)

         5. CONDITIONS PRECEDENT. The effectiveness of the consent, waiver and
other terms and conditions contained herein shall be subject to the satisfaction
of each of the following conditions as determined by Lender:

         5.1 DELIVERY OF DOCUMENTS. Lender shall have received, in form and
substance satisfactory to Lender, each of the following:

                  (a) an original of this Amendment, duly authorized, executed
and delivered by Borrowers to Lender;


                                      - 8 -
<PAGE>

                  (b) evidence that the Helicopter Purchase Agreements and the
Boeing Loan Documents have been duly authorized, executed and delivered by and
to the appropriate parties thereto and that the transactions contemplated under
the terms and conditions of the Helicopter Purchase Agreements and the Boeing
Loan Documents have been consummated contemporaneously with the execution and
delivery of this Amendment, together with opinions of counsel with respect to
such transactions and agreements, if any, addressed to Lender or upon which
Lender is expressly permitted to rely; and

                  (c) true, correct and complete copies of the Helicopter
Purchase Agreements and the Boeing Loan Documents.

         5.2 NO DEFAULT. No Event of Default exists on the date hereof after
giving effect to the amendment to the Loan Agreement made by the provisions of
this Amendment.

         6.  MISCELLANEOUS.

         6.1 ADDITIONAL EVENT OF DEFAULT. The parties hereto acknowledge,
confirm and agree that the failure of Borrowers to comply with the covenants,
conditions and agreements contained herein shall constitute an Event of Default
under the Financing Agreements (subject to the applicable cure period, if any,
with respect thereto provided for in the Loan Agreement as in effect on the date
hereof).

         6.2 EFFECT OF THIS AMENDMENT. Except as modified pursuant hereto, no
other consents, changes or modifications to the Financing Agreements are
intended or implied, and in all other respects, the Financing Agreements are
hereby specifically ratified, restated and confirmed by all parties hereto as of
effective date hereof. Any acknowledgment or consent contained herein shall not
be construed to constitute a consent to any other or further action by Borrower
or to entitle Borrowers to any other consent. The Loan Agreement and this
Amendment shall be read and construed as one agreement. To the extent of
conflict between the terms of this Amendment and the other Financing Agreements,
the terms of this Amendment shall control.

         6.3 FURTHER ASSURANCES. The parties hereto shall execute and deliver
such additional documents and take such additional actions as may be necessary
to effectuate the provisions and purposes of this Amendment.

         6.4 GOVERNING LAW. The rights and obligations hereunder of each of the
parties hereto shall be governed by and interpreted and determined in accordance
with the laws of the State of New York (without giving effect to principals of
conflict of laws).

         6.5 BINDING EFFECT. This Amendment shall be binding upon and inure to
the benefit of each of the parties hereto and their respective successors and
assigns.

         6.6 COUNTERPARTS. This Amendment may be executed in any number of
counterparts, but all of such counterparts shall together constitute but one and
the same agreement. In making


                                      - 9 -
<PAGE>

proof of this Amendment, it shall not be necessary to produce or account for
more than one counterpart thereof signed by each of the parties thereto.

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed and delivered by their authorized officers as of the date and year
first above written.

                                                CONGRESS FINANCIAL CORPORATION

                                                By: /s/ Herbert Korn
                                                   -----------------------------

                                                Title: Assistant Vice President
                                                      --------------------------

                                                THE DOE RUN RESOURCES
                                                   CORPORATION

                                                By:  /s/ David Chaput
                                                   -----------------------------

                                                Title:  Treasurer
                                                      --------------------------

                                                FABRICATED PRODUCTS, INC.

                                                By: /s/ David Chaput
                                                   -----------------------------

                                                Title:  Treasurer
                                                      --------------------------


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