UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934
(Amendment No. 20)*

PolyMet Mining Corp.

(Name of Issuer)

Common Shares, without par value

(Title of Class of Securities)

731916102

(CUSIP Number)

Stephen Rowland and Rajiv Singhal

Glencore International AG

Baarermattstrasse 3

CH-6340 Baar

Switzerland

+41 41 709 2000

With copies to:

Matias Vega, Esq.

Curtis, Mallet-Prevost, Colt & Mosle LLP

101 Park Avenue

New York, NY 10178

(212) 696-6000

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

March 23, 2018

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

^* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP No. 731916102

CUSIP No. 731916102

CUSIP No. 731916102

Explanatory Note:

This Amendment No. 20 (this “Amendment No. 20”) amends and restates the Schedule 13D originally filed with the United States Securities and Exchange Commission (the “SEC”) by Glencore Holding AG, Glencore International AG and Glencore AG on November 10, 2008, and amended by Amendment No. 1 thereto filed on December 24, 2008, Amendment No. 2 thereto filed on June 22, 2009, Amendment No. 3 thereto filed on September 4, 2009, Amendment No. 4 thereto filed on November 3, 2009, Amendment No. 5 thereto filed on November 23, 2009, Amendment No. 6 thereto filed on January 27, 2010, Amendment No. 7 thereto filed on November 15, 2010, Amendment No. 8 thereto filed on June 2, 2011 (which amendment removed Glencore Holding AG as a Reporting Person and added Glencore International plc (now known as Glencore plc) as a Reporting Person), Amendment No. 9 thereto filed on July 15, 2011, Amendment No. 10 thereto filed on December 6, 2011, Amendment No. 11 thereto filed on October 16, 2012, Amendment No. 12 thereto filed on April 16, 2013, Amendment No. 13 thereto filed on June 10, 2013, Amendment No. 14 thereto filed on July 8, 2013, Amendment No. 15 thereto filed on April 29, 2014, Amendment No. 16 thereto filed on August 5, 2015, Amendment No. 17 thereto filed on December 18, 2015, Amendment No. 18 thereto filed on September 19, 2016 and Amendment No. 19 thereto filed on November 1, 2016 (as so amended, the “Statement”) relating to the common shares, no par value (“Common Shares”), of PolyMet Mining Corp., a corporation incorporated under the laws of the Province of British Columbia, Canada (the “Issuer”). This Amendment No. 20 reflects changes to Items 2, 3, 4, 5 and 7 of the Statement.

This Schedule 13D relates to the common shares, without par value (the “Common Shares”), of PolyMet Mining Corp., a corporation incorporated under the laws of the Province of British Columbia, Canada. The Issuer’s principal executive office is located at First Canadian Place, 100 King Street West, Suite 5700, Toronto, Ontario Canada M5X 1C7.

This Schedule 13D is being filed by (a) Glencore plc (formerly known as Glencore Xstrata plc) (“Glencore plc”), (b) Glencore International AG (“Glencore International”) and (c) Glencore AG (collectively, the “Reporting Persons”). Glencore plc is a company organized under the laws of Jersey. Each of Glencore International and Glencore AG is a company organized under the laws of Switzerland.

Glencore plc is a public company with its ordinary shares listed on the London Stock Exchange and the Johannesburg Stock Exchange. Glencore plc is the parent company of Glencore International which, together with its subsidiaries, including Glencore AG, is a leading integrated producer and marketer of natural resources, with worldwide activities in the production, refinement, processing, storage, transport and marketing of metals and minerals, energy products and agricultural products. Each of the Reporting Persons other than Glencore plc is a direct or indirect wholly-owned subsidiary of Glencore plc. Glencore AG is a direct wholly-owned subsidiary of Glencore International.

The address of the principal business and office of each of the Reporting Persons is Baarermattstrasse 3, CH-6340, Baar, Switzerland.

The name, citizenship, occupation and principal business address of each director and executive officer of the Reporting Persons are listed in Schedule 1 hereto (the “Schedule 1 Persons”), which Schedule 1 is incorporated herein by reference.

During the last five years, none of the Reporting Persons, or, to the Reporting Persons’ knowledge, any of the Schedule 1 Persons, has been (i) convicted in a criminal proceeding (excluding traffic violations and similar misdemeanors) or (ii) party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

On October 31, 2008, Glencore AG, the Issuer and the Issuer’s wholly owned subsidiary, Poly Met Mining, Inc., a Minnesota corporation (the “Issuer Subsidiary”), entered into a purchase agreement (the “Original Purchase Agreement”), as amended by a letter agreement (“Amendment No. 1”), dated as of November 28, 2008, and as further amended by a letter agreement (“Amendment No. 2”), dated as of December 12, 2008, a letter agreement (“Amendment No. 3”), dated as of December 19, 2008, a letter agreement (“Amendment No. 4”), dated as of January 30, 2009, a letter agreement (“Amendment No. 5”), dated as of February 24, 2009, a letter agreement (“Amendment No. 6”), dated as of March 30, 2009, a letter agreement (“Amendment No. 7”), dated as of April 28, 2009, a letter agreement (“Amendment No. 8”), dated as of June 4, 2009, a letter agreement (“Amendment No. 9”), dated as of August 31, 2009, a letter agreement (“Amendment No. 10”), dated as of October 20, 2009, and a letter agreement (“Amendment No. 11”), dated as of November 16, 2009 (the Original Purchase Agreement, as amended, the “Purchase Agreement”), which provided for, among other things, Glencore AG’s purchase of up to US$50,000,000 in aggregate principal amount of floating rate secured debentures due September 30, 2011 issued by the Issuer Subsidiary (collectively, the “Debentures”).

The initial closing of the transactions contemplated by the Original Purchase Agreement occurred on October 31, 2008. At the initial closing, the Issuer Subsidiary issued to Glencore AG an initial tranche of US$7,500,000 of the Debentures (the “Tranche A Debenture”). Subsequently, the Issuer Subsidiary issued to Glencore AG a second tranche of US$7,500,000 of the Debentures (the “Tranche B Debenture”) on December 22, 2008, a third tranche of US$5,000,000 of the Debentures (the “Tranche C Debenture”) on June 17, 2009 and a fourth tranche of US$5,000,000 of the Debentures (the “Tranche D Debenture”) on August 31, 2009. The Original Purchase Agreement had also provided for a fifth tranche of US$25,000,000 of the Debentures (the “Tranche E Debenture”) to be issued to Glencore AG upon the satisfaction of additional closing conditions set forth in the Original Purchase Agreement.

The Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture and the Tranche D Debenture initially bore interest at a rate equal to the 12-month US dollar LIBOR plus 4%. Interest is payable in cash or by increasing the principal amount of such Debentures. On or before September 30, 2009, the Issuer was able to elect in which form to make the interest payments; thereafter, Glencore AG may make such election. As of March 31, 2018, approximately US$26.2 million of capitalized and accrued interest has been added to the principal amount of such Debentures. The Issuer has guaranteed the Issuer Subsidiary’s obligations under such Debentures pursuant to a Parent Guarantee (the “Parent Guarantee”), dated as of October 31, 2008. The Issuer Subsidiary’s obligations under such Debentures are secured by (i) the assets of the Issuer pursuant to a security agreement (the “Issuer Security Agreement”), dated as of October 31, 2008, between the Issuer and Glencore AG, (ii) the assets of the Issuer Subsidiary pursuant to a security agreement (the “Issuer Subsidiary Security Agreement”), dated as of October 31, 2008, between the Issuer Subsidiary and Glencore AG, and (iii) a security interest in the Issuer’s equity interest in the Issuer Subsidiary pursuant to a pledge agreement (the “Pledge Agreement”), dated as of October 31, 2008, between the Issuer and Glencore AG.

In connection with the Original Purchase Agreement, on October 31, 2008, the Issuer issued to Glencore AG an exchange warrant pursuant to which the Debentures were exchangeable into Common Shares at any time at an exchange rate of US$4.00 per Common Share for the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture and the Tranche D Debenture, and an exchange rate of US$2.65 per Common Share for the Tranche E Debenture (the “Original Exchange Warrant”).

In connection with the Original Purchase Agreement, on October 31, 2008, the Issuer issued to Glencore AG a purchase warrant entitling Glencore AG to purchase 6,250,000 Common Shares at an exercise price of US$3.00 per Common Share (the “2008 Purchase Warrant”).

Concurrently with the issuance of the Tranche A Debenture and the 2008 Purchase Warrant, the Issuer and Glencore AG entered into a Registration Rights Agreement (the “2008 Registration Rights Agreement”). The 2008 Registration Rights Agreement granted Glencore AG demand and piggyback registration rights with respect to Common Shares issuable upon exercise of the Original Exchange Warrant and/or exercise of the 2008 Purchase Warrant.

Pursuant to a subscription agreement, dated as of November 17, 2009, between Glencore AG and the Issuer (the “First 2009 Subscription Agreement”), Glencore AG acquired from the Issuer, on a private placement basis, 3,773,585 Common Shares for an aggregate purchase price of US$10,000,000.25 (or US$2.65 per Common Share). Pursuant to another subscription agreement, dated as of November 23, 2009, between Glencore AG and the Issuer (the “Second 2009 Subscription Agreement”), on January 26, 2010, Glencore AG acquired from the Issuer, on a private placement basis, 5,660,377 Common Shares for an aggregate purchase price of US$14,999,999.05 (or US$2.65 per Common Share).

On November 12, 2010, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment and waiver agreement (the “2010 Amendment and Waiver”) pursuant to which the parties agreed, among other things, to:

On November 12, 2010, as contemplated by the 2010 Amendment and Waiver, the Issuer issued to Glencore AG a purchase warrant entitling Glencore AG to purchase 3,000,000 Common Shares at an exercise price of US$2.00 per Common Share until December 31, 2015 (the “2010 Purchase Warrant”).

In accordance with the terms of the 2010 Amendment and Waiver, the Issuer and Glencore AG also entered into a registration rights agreement, dated as of November 12, 2010 (the “2010 Registration Rights Agreement”), pursuant to which Glencore AG (and any transferee of Common Shares to whom Glencore AG transfers its registration rights) was granted demand and piggyback registration rights with respect to all Common Shares held by Glencore AG, including any Common Shares issuable upon exercise of the 2010 Purchase Warrant and/or exercise of the Original Exchange Warrant. The 2010 Registration Rights Agreement provides that the Issuer must effect an unlimited number of demand registration rights if holders of at least fifty percent (50%) of such registrable securities demand the registration of Common Shares covering at least twenty-five percent (25%) of the outstanding amount of such registrable securities (or a lesser percent if the anticipated aggregate offering price, net of underwriting discounts and commissions, would exceed US$5,000,000); provided, however, the Issuer is not obligated to effect (i) a registration covering the sale of Common Shares for an aggregate public offering price of less than US$5,000,000, (ii) more than two such registrations in any twelve-month period or (iii) any registration at a time when it is keeping three such registration statements effective.

Concurrently, Glencore AG and the Issuer entered into a Subscription Agreement, dated as of November 12, 2010 (the “2010 Subscription Agreement”), pursuant to which Glencore AG agreed to purchase from the Issuer, on a private placement basis, an aggregate of 15,000,000 Common Shares for a purchase price of US$2.00 per Common Share in three separate tranches of 5,000,000 Common Shares each.

On January 17, 2011, pursuant to the first tranche of the 2010 Subscription Agreement, Glencore AG acquired from the Issuer, on a private placement basis, 5,000,000 Common Shares for an aggregate purchase price of US$10,000,000 (or US$2.00 per Common Share).

The Issuer’s board of directors waived applicable provisions of the Issuer’s amended and restated shareholder rights plan agreement with respect to Glencore AG’s purchase of the remaining second and third tranches of the 2010 Subscription Agreement.

On July 15, 2011, pursuant to the second tranche of the 2010 Subscription Agreement, Glencore AG acquired an additional 5,000,000 Common Shares from the Issuer for an aggregate purchase price of US$10,000,000 (or US$2.00 per Common Share). Concurrently, Glencore AG granted a waiver to the Issuer pursuant to which Glencore AG waived the application of certain covenants contained in the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture and the Tranche D Debenture to the secured loan provided by the Iron Range Resources and Rehabilitation Board to the Issuer Subsidiary that previously closed on June 28, 2011 (the “IRRRB Loan Waiver”).

On October 15, 2012, pursuant to the remaining third tranche of the 2010 Subscription Agreement, Glencore AG acquired an additional 5,000,000 Common Shares from the Issuer for an aggregate purchase price of US$10,000,000 (or US$2.00 per Common Share).

On July 15, 2011, Glencore AG acquired pursuant to a private transaction 9,200,547 Common Shares at a price of US$1.4233 per share. These shares were purchased from Cliffs Erie L.L.C. (“Cliffs”) in accordance with the Issuer’s right to arrange for a purchaser of the shares upon notice from Cliffs of its desire to sell the shares. The purchase was made pursuant to a share purchase agreement, which was previously filed with the SEC as an exhibit to the Statement, and is hereby incorporated herein by reference.

In connection with Glencore AG’s purchase from Cliffs, the Issuer’s board of directors waived applicable provisions of the Issuer’s amended and restated shareholder rights plan agreement with respect to Glencore AG becoming the beneficial owner of more than 20% of the outstanding voting shares of the Issuer as a result of the purchases described above.

On December 6, 2011, pursuant to a subscription agreement, dated as of November 30, 2011, between Glencore AG and the Issuer (the “2011 Subscription Agreement”), Glencore AG acquired from the Issuer, on a private placement basis, an aggregate of 13,333,333 Common Shares and a warrant entitling Glencore AG to purchase up to an aggregate of 2,600,000 Common Shares at an exercise price of US$1.50 per Common Share until December 31, 2015 (the “2011 Purchase Warrant”) for an aggregate purchase price of US$19,999,999.50.

In connection with the 2011 Subscription Agreement, on December 6, 2011, an amendment and waiver agreement, dated as of November 30, 2011, among the Issuer, the Issuer Subsidiary and Glencore AG (the “2011 Amendment and Waiver”), became effective and amended, among other things:

In addition, pursuant to the 2011 Amendment and Waiver, on December 6, 2011, the Issuer issued to Glencore AG an amended and restated exchange warrant that amended and restated the Original Exchange Warrant (the “Amended and Restated Exchange Warrant”). Pursuant to the Amended and Restated Exchange Warrant, the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture and the Tranche D Debenture are exchangeable into Common Shares at an exchange rate of US$1.50 per Common Share for such Debentures at any time until the earlier of (i) the Issuer and/or the Issuer Subsidiary satisfying the Construction Prerequisites and (ii) September 30, 2014. The Amended and Restated Exchange Warrant further provides that the Issuer may, within 10 business days after the date on which the Issuer and/or the Issuer Subsidiary has satisfied the Construction Prerequisites, deliver a notice to Glencore AG requiring Glencore AG to exercise the Amended and Restated Exchange Warrant.

In addition, in connection with the 2011 Subscription Agreement and the 2011 Amendment and Waiver, on November 30, 2011, the Issuer and Glencore AG entered into a registration rights agreement and amendment to existing registration rights agreement (the “2011 Registration Rights Agreement”), pursuant to which (i) Glencore AG (and any transferee of Common Shares to whom Glencore AG transfers its registration rights) was granted demand and piggyback registration rights with respect to the Common Shares issued under the 2011 Subscription Agreement and the Common Shares issuable upon exercise of the 2011 Purchase Warrant and (ii) the 2010 Registration Rights Agreement was amended so that the registrable securities covered by the 2010 Registration Rights Agreement include the Common Shares issuable upon exercise of the 2010 Purchase Warrant, as amended by the 2011 Amendment and Waiver, and the Common Shares issuable upon exercise of the Amended and Restated Exchange Warrant.

The Issuer’s board of directors waived applicable provisions of the Issuer’s amended and restated shareholder rights plan agreement with respect to the transactions contemplated by the 2011 Subscription Agreement and the 2011 Amendment and Waiver.

On April 11, 2013, Glencore AG loaned US$20 million to the Issuer Subsidiary through the purchase of an amended Tranche E Debenture from the Issuer Subsidiary (as amended, the “Amended Tranche E Debenture”) pursuant to an amendment to the Purchase Agreement, dated as of April 10, 2013 (the “Amendment No. 14 to Purchase Agreement”), among the Issuer, the Issuer Subsidiary and Glencore AG. The Amended Tranche E Debenture had a maturity date of May 1, 2014, subject to mandatory repayment upon closing of the Rights Offering and carried a fixed interest rate of 4.721% per annum. Pursuant to a confirmation of secured obligations agreement (the “Confirmation of Secured Obligations Agreement”), dated as of April 10, 2013, among the Issuer Subsidiary, the Issuer and Glencore AG, the parties had confirmed that the Issuer Subsidiary’s obligations under the Amended Tranche E Debenture were guaranteed by the Issuer and secured by the assets of the Issuer and the Issuer Subsidiary on the same terms as the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture and the Tranche D Debenture. On July 5, 2013, the Amended Tranche E Debenture was fully repaid with proceeds from the Rights Offering (as described below).

On July 5, 2013, at the closing of an offering of rights (“Rights”) by the Issuer to holders of Common Shares to raise up to approximately US$60.5 million in gross proceeds (the “Rights Offering”) contemplated by a standby purchase agreement, dated as of April 10, 2013, between Glencore AG and the Issuer (the “Standby Purchase Agreement”), Glencore AG acquired from the Issuer 31,756,979 Common Shares for an aggregate purchase price of US$20,959,606.14 (or US$0.66 per Common Share), of which 23,483,921 Common Shares were acquired by Glencore AG pursuant to the exercise of its basic subscription privilege under the Rights Offering and 8,273,058 Common Shares of which were acquired by Glencore AG pursuant to the exercise of its additional subscription privilege under the Rights Offering. In consideration for Glencore AG’s agreement to provide a standby commitment for the Rights Offering pursuant to the Standby Purchase Agreement, Glencore AG received a cash fee of approximately US$1.06 million at the closing of the Rights Offering. In addition, on July 5, 2013, at the closing of the Rights Offering, the Issuer and Glencore AG entered into (i) a corporate governance agreement (the “Corporate Governance Agreement”) under which, effective January 1, 2014, Glencore AG may appoint that number of the directors of the Issuer which is proportionate to Glencore AG’s ownership of Common Shares (on a fully diluted basis), subject to certain limitations including that Glencore AG may not appoint more than 49% (rounding down) of the Issuer’s directors and (ii) a registration rights agreement (the “2013 Registration Rights Agreement”) pursuant to which Glencore AG (and any transferee of Common Shares to whom Glencore AG transfers its registration rights) was granted demand and piggyback registration rights with respect to all Common Shares acquired by Glencore AG pursuant to the Rights Offering.

Glencore AG waived its right of first refusal on material financings by the Issuer contained in the 2010 Subscription Agreement with respect to the Rights Offering. In addition, the Issuer’s board of directors waived applicable provisions of the Issuer’s amended and restated shareholder rights plan agreement with respect to Glencore AG in connection with (i) the issuance of the Rights and Common Shares issuable upon exercise of the Rights under the Rights Offering and (ii) the Standby Purchase Agreement.

At the closing of the Rights Offering, as a result of the Rights Offering’s triggering of customary anti-dilution provisions: (i) the exchange rate at which the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture and the Tranche D Debenture are exchangeable pursuant to the Amended and Restated Exchange Warrant was reduced from US$1.50 to US$1.2920 per Common Share, (ii) the exercise prices for the 2010 Purchase Warrant and the 2011 Purchase Warrant were reduced from US$1.50 to US$1.3007 per Common Share and (iii) the number of Common Shares issuable upon exercise of the 2010 Purchase Warrant and the 2011 Purchase Warrant were increased to 3,459,643 Common Shares and 2,998,358 Common Shares, respectively.

On April 25, 2014, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment agreement (the “2014 Amendment”) pursuant to which the parties agreed, among other things, to:

On January 28, 2015, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 16 to Purchase Agreement”) pursuant to which the parties agreed, among other things, for the Issuer Subsidiary to issue to Glencore AG new Tranche F, G, H, and I debentures (the “2015 Debentures”) with the total principal amount of US$30.0 million. Tranche F in the principal amount of US$8.0 million was issued on January 30, 2015. Tranche G in the principal amount of $8.0 million was issued on April 15, 2015. Tranche H in the principal amount of US$8.0 million was issued on July 1, 2015. Tranche I in the principal amount of US$6 million was issued on October 1, 2015. The 2015 Debentures bear interest at 12-month US dollar LIBOR plus 8.0% per annum payable in cash upon maturity and were issued with an initial maturity date of the earlier of (i) the availability of at least US$100 million of finance provided the Issuer demonstrates repayment is prudent or (ii) March 31, 2016. The Issuer and the Issuer Subsidiary provided security by way of a guarantee and a pledge of the assets of the Issuer and the Issuer Subsidiary.

On July 30, 2015, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 17 to Purchase Agreement”) pursuant to which the parties agreed, among other things, to:

On December 15, 2015, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 18 to Purchase Agreement”) pursuant to which the parties agreed, among other things, to:

On January 27, 2016, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 19 to Purchase Agreement”) pursuant to which the parties agreed for the Issuer Subsidiary to issue to Glencore AG a new Tranche J Debenture in the principal amount of US$11.0 million (the “Tranche J Debenture”). The Tranche J Debenture was issued on January 27, 2016. The Tranche J Debenture bears interest at 12-month US dollar LIBOR plus 15.0% per annum payable in cash upon maturity and were issued with an initial maturity date of the earlier of (i) the availability of at least US$80 million of debt or equity financing or (ii) March 31, 2017.

On June 2, 2016, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 20 to Purchase Agreement”) pursuant to which the parties agreed for the Issuer Subsidiary to issue to Glencore AG new Tranche K, L and M debentures (the “KLM Debentures”) in the aggregate principal amount of US$14.0 million. Tranche K in the principal amount of US$3.0 million was issued on June 3, 2016. On June 30, 2016, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 21 to Purchase Agreement”) pursuant to which the parties agreed for the Issuer Subsidiary to issue the Tranche L debenture to Glencore AG in two tranches, a Tranche L-1 debenture and a Tranche L-2 debenture. The Tranche L-1 debenture in the principal amount of US$5.0 million was issued on July 1, 2016. The Tranche L-2 debenture in the principal amount of US$3.0 million was issued on July 26, 2016. The Tranche M debenture in the principal amount of US$3.0 million was issued on August 5, 2016. The KLM Debentures bear interest at 12-month US dollar LIBOR plus 15.0% per annum payable in cash upon maturity and were issued with an initial maturity of the earlier of (i) the availability of at least US$100 million of debt or equity financing or (ii) March 31, 2017.

On September 14, 2016, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 22 to Purchase Agreement”) pursuant to which the parties agreed to extend the maturity date of the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture, the Tranche D Debenture, the 2015 Debentures, the Tranche J Debenture and the KLM Debentures to the earlier of (i) the availability of at least US$100 million of debt and/or equity financing or (ii) March 31, 2018.

On October 24, 2016, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 23 to Purchase Agreement”) pursuant to which:

The First 2016 Purchase Warrant was issued on October 28, 2016.

On October 28, 2016, in connection with Glencore’s exercise of its right to maintain its pro rata ownership following the Issuer’s private placement that closed on October 18, 2016, pursuant to a subscription agreement between Glencore AG and the Issuer (the “2016 Subscription Agreement”), Glencore AG acquired from the Issuer, on a private placement basis, an aggregate of 14,111,251 Common Shares and a warrant entitling Glencore AG to purchase up to an aggregate of 7,055,626 Common Shares at an exercise price of US$1.00 per Common Share until October 28, 2021 (the “Second 2016 Purchase Warrant”) for an aggregate purchase price of US$10,583,438.25.

On September 14, 2017, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 24 to Purchase Agreement”) pursuant to which the parties agreed for the Issuer Subsidiary to issue to Glencore AG new Tranche N and O debentures (the “NO Debentures”) in the aggregate principal amount of US$20.0 million, bearing interest at 12-month US dollar LIBOR plus 15.0% and due on the earlier of (i) March 31, 2018 or (ii) the availability of at least $100 million of debt or equity financing or (iii) when it is prudent for the Issuer Subsidiary to repay the debt, on which date all principal and interest accrued to such date will be due and payable. The Tranche N debenture in the amount of $15.0 million was issued in September 2017. The Tranche O debenture in the amount of $5.0 million was issued in January 2018.

On December 31, 2017, the 2010 Purchase Warrant and the 2011 Purchase Warrant expired.

On March 23, 2018, the Issuer, the Issuer Subsidiary and Glencore AG entered into an amendment to the Purchase Agreement (the “Amendment No. 25 to Purchase Agreement”) pursuant to which the parties agreed:

The 2018 Purchase Warrant was issued on March 23, 2018.

The foregoing summaries of the Original Purchase Agreement, Amendment No. 1, Amendment No. 2, Amendment No. 3, Amendment No. 4, Amendment No. 5, Amendment No. 6, Amendment No. 7, Amendment No. 8, Amendment No. 9, Amendment No. 10, Amendment No. 11, the Tranche A Debenture, the Tranche B Debenture, the Tranche C Debenture, the Tranche D Debenture, the Parent Guarantee, the Issuer Security Agreement, the Issuer Subsidiary Security Agreement, the Pledge Agreement, the Original Exchange Warrant, the 2008 Purchase Warrant, the 2008 Registration Rights Agreement, the First 2009 Subscription Agreement, the Second 2009 Subscription Agreement, the 2010 Amendment and Waiver, the 2010 Purchase Warrant, the 2010 Registration Rights Agreement, the 2010 Subscription Agreement, the IRRRB Loan Waiver, the 2011 Subscription Agreement, the 2011 Purchase Warrant, the 2011 Amendment and Waiver, the Amended and Restated Exchange Warrant, the 2011 Registration Rights Agreement, the Amended Tranche E Debenture, the Amendment No. 14 to Purchase Agreement, the Confirmation of Secured Obligations Agreement, the Standby Purchase Agreement, the Corporate Governance Agreement, the 2013 Registration Rights Agreement, the 2014 Amendment, the Amendment No. 16 to Purchase Agreement, the Amendment No. 17 to Purchase Agreement, the Amendment No. 18 to Purchase Agreement, the Amendment No. 19 to Purchase Agreement, the Amendment No. 20 to Purchase Agreement, the Amendment No. 21 to Purchase Agreement, the Amendment No. 22 to Purchase Agreement, the Amendment No. 23 to Purchase Agreement, the First 2016 Purchase Warrant, the 2016 Subscription Agreement and the Second 2016 Purchase Warrant do not purport to be complete and are qualified in their entirety by reference to the complete text of such agreements, which were previously filed with the SEC as exhibits to the Statement, and are hereby incorporated herein by reference. The foregoing summaries of the Amendment No. 24 to Purchase Agreement, the Amendment No. 25 to Purchase Agreement and the 2018 Purchase Warrant do not purport to be complete and are qualified in their entirety by reference to the complete text of such agreements, which have been incorporated by reference or attached as Exhibits 99.56, 99.57 and 99.58, respectively, to this Amendment No. 20 and are hereby incorporated herein by reference.

The source of funds for all of the purchases described above was working capital of the Reporting Persons. The Reporting Persons anticipate that the source of funds for any exercises of the the First 2016 Purchase Warrant, the Second 2016 Purchase Warrant and/or the 2018 Purchase Warrant will be working capital of the Reporting Persons.

The Reporting Persons acquired the securities of the Issuer covered by this Schedule 13D for investment purposes. The Reporting Persons intend to continue to evaluate the Issuer’s business, financial condition, results of operations, capital structure, financing requirements, management, stock market performance, competitive outlook and other relevant factors. As part of such evaluations, the Reporting Persons may seek the views of, hold discussions with and respond to inquiries from representatives of the Issuer and other persons regarding the Issuer’s affairs. In addition, the Reporting Persons have held discussions, and may continue to hold discussions, with the Issuer regarding the Issuer’s equity and debt financing requirements and sources, including the Issuer’s equity and debt financing requirements relating to the development and construction of the Issuer’s NorthMet Project. Depending on such evaluations and discussions, each Reporting Person may at any time and from time to time acquire Common Shares, debt securities and/or securities convertible, exercisable or exchangeable for Common Shares; dispose of securities which it has acquired; and/or enter into privately negotiated derivative transactions with institutional counterparts to hedge the market risk of some or all of the positions in the Common Shares which it has acquired. Any acquisition or disposition of Common Shares by the Reporting Persons may be effected through open market or privately negotiated transactions, or otherwise. Any such transactions may be effected at any time and from time to time subject to any applicable limitations of the United States Securities Act of 1933, as amended. In addition, in the interest of maximizing shareholder value, the Reporting Persons may, from time to time, develop plans respecting, or propose changes in the management, policies, operations, capital structure or business of the Reporting Persons. Such plans or proposals may include or relate to one or more of the transactions specified in Items 4(a) through (j) of Schedule 13D under Rule 13d-1(a), including without limitation, a merger, disposition, sale of the Issuer’s assets or changes in the Issuer’s capitalization. Each Reporting Person reserves the right to change its plans and intentions at any time, as it deems appropriate.

Mr. Mike Ciricillo, who is currently employed by Glencore, is a member of (i) the Issuer’s board of directors, (ii) the Issuer’s Health, Safety, Environment and Communities Committee and (iii) the Issuer’s Technical Steering Committee. Ms. Helen Harper, who is currently employed by Glencore, is a member of (i) the Issuer’s board of directors, (ii) the Issuer’s Audit Committee (as a non-voting participant), (iii) the Issuer’s Nominating and Corporate Governance Committee (as a non-voting participant), (iv) the Issuer’s Health, Safety, Environment and Communities Committee and (v) the Issuer’s Technical Steering Committee. Mr. Stephen Rowland, who is currently employed by Glencore, is a member of (i) the Issuer’s board of directors, (ii) the Issuer’s Compensation Committee and (iii) the Issuer’s Nominating and Corporate Governance Committee (as a non-voting participant).

As described in Item 3 of the Statement, on July 5, 2013, the Issuer and Glencore AG entered into the Corporate Governance Agreement under which, effective January 1, 2014, Glencore AG may appoint that number of the directors of the Issuer which is proportionate to Glencore AG’s ownership of Common Shares (on a fully diluted basis), subject to certain limitations including that Glencore AG may not appoint more than 49% (rounding down) of the Issuer’s directors.

Except as described herein, neither the Reporting Persons, nor, to the Reporting Persons’ knowledge, any of the Schedule 1 Persons has any present plans or proposals that relate to or would result in any of the actions described in Items 4(a) through (j) of Schedule 13D under Rule 13d-1(a). To the Reporting Persons’ knowledge, any of the Schedule 1 Persons may make the same evaluation and reserve the same rights.

(a) and (b)

The Reporting Persons collectively own, directly or indirectly, 92,836,072 Common Shares. However, the Reporting Persons may be deemed to collectively have direct or indirect “beneficial ownership” within the meaning of Rule 13d-3 under the United States Securities Exchange Act of 1934, as amended (the “Exchange Act”), of (i) an additional 40,314,280 Common Shares issuable upon exercise of the Amended and Restated Exchange Warrant (based on the principal amount of the Debentures that includes capitalized and accrued interest as of March 31, 2018), (ii) an additional 625,000 Common Shares issuable upon exercise of the First 2016 Purchase Warrant, (iii) an additional 7,055,626 Common Shares issuable upon exercise of the Second 2016 Purchase Warrant and (iv) an additional 6,458,001 Common Shares issuable upon exercise of the 2018 Purchase Warrant. Accordingly, each of the Reporting Persons may be deemed to beneficially own an aggregate of 147,288,979 Common Shares, representing 39.3% of the Issuer’s issued and outstanding Common Shares. This beneficial ownership percentage assumes that there are 374,755,628 Common Shares outstanding, which was calculated based on the sum of (i) 320,302,721 Common Shares outstanding as at March 22, 2018 as reported by the Issuer in its Management Discussion and Analysis as at December 31, 2017 and January 31, 2017 and for the eleven months ended December 31, 2017 and the twelve months ended January 31, 2017, filed as Exhibit 99.3 to the Issuer’s Annual Report on Form 40-F furnished with the SEC on March 28, 2018, (ii) the 40,314,280 Common Shares issuable upon exercise of the Amended and Restated Exchange Warrant (based on the principal amount of the Debentures that includes capitalized and accrued interest as of March 31, 2018), (iii) the 625,000 Common Shares issuable upon exercise of the First 2016 Purchase Warrant, (iv) the 7,055,626 Common Shares issuable upon exercise of the Second 2016 Purchase Warrant and (v) the 6,458,001 Common Shares issuable upon exercise of the 2018 Purchase Warrant. The Reporting Persons share the power to vote or to direct the vote and dispose or to direct the disposition of the 147,288,979 Common Shares set forth above.

(c)       Except as set forth in Item 3 and this Item 5 of the Statement, none of the Reporting Persons nor, to the Reporting Persons’ knowledge, any of the Schedule 1 Persons, has beneficial ownership of any other Common Shares, or has engaged in any other transaction during the past 60 days in any Common Shares.

Mr. Mike Ciricillo, who is currently employed by Glencore and is a member of the Issuer’s board of directors, holds deferred share units in respect of 42,254 Common Shares and options to purchase 250,000 Common Shares. Ms. Helen Harper, who is currently employed by Glencore and is a member of the Issuer’s board of directors, holds 10,000 Common Shares, deferred share units in respect of 73,119 Common Shares and options to purchase 250,000 Common Shares. Mr. Stephen Rowland, who is currently employed by Glencore and is a member of the Issuer’s board of directors, holds 232,641 Common Shares, deferred share units in respect of 73,119 Common Shares and options to purchase 750,000 Common Shares.

(d)       Not applicable.

(e)       Not applicable.

Except as set forth in Item 3 of the Statement, to the best knowledge of the Reporting Persons, there are no other contracts, arrangements, understandings or relationships (legal or otherwise) among the persons named in Item 2 or between such persons and any other person with respect to any securities of the Issuer, including but not limited to, transfer or voting of any of the securities of the Issuer, joint ventures, loan or option arrangements, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies, or a pledge or contingency the occurrence of which would give another person voting power over the securities of the Issuer.

Signature

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: April 4, 2018

SCHEDULE 1

Set forth below are the names, business addresses and present principal occupations of the directors and executive officers of Glencore plc, Glencore International AG and Glencore AG. Each executive officer of each of Glencore International AG and Glencore AG is also a director of such company. Where no business address is given for an executive officer or director, and such director’s principal employer is Glencore plc or one of its subsidiaries, the business address is Baarermattstrasse 3, CH-6340, Baar, Switzerland. To the best knowledge of the Reporting Persons, none of the persons listed below beneficially owns any Common Shares.

Directors of Glencore plc:

Executive Officers of Glencore plc:

Directors and Executive Officers of Glencore International AG:

Directors and Executive Officers of Glencore AG:

Exhibit 99.1

JOINT FILING AGREEMENT

Each of the undersigned hereby agrees that this Amendment No. 20 to the statement on Schedule 13D is being filed with the United States Securities and Exchange Commission on behalf of each of the undersigned pursuant to Rule 13d-1(k) under the United States Securities Exchange Act of 1934, as amended.

Dated: April 4, 2018

Exhibit 99.58

WARRANT CERTIFICATE

THE WARRANTS EVIDENCED HEREBY ARE EXERCISABLE DURING THE PERIOD BEGINNING ON MARCH 23, 2018 AND ENDING AT OR BEFORE 5:00 P.M. (TORONTO TIME) ON MARCH 31, 2019, AFTER WHICH TIME THESE WARRANTS SHALL BE NULL AND VOID AND OF NO FURTHER FORCE AND EFFECT.

UNLESS PERMITTED UNDER SECURITIES LEGISLATION, THE HOLDER OF THIS SECURITY MUST NOT TRADE THE SECURITY BEFORE MARCH 23, 2018.

THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE LISTED ON THE TORONTO STOCK EXCHANGE (“TSX”); HOWEVER, THE SAID SECURITIES CANNOT BE TRADED THROUGH THE FACILITIES OF THE TSX SINCE THEY ARE NOT FREELY TRANSFERABLE, AND CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH SECURITIES IS NOT “GOOD DELIVERY” IN SETTLEMENT OF TRANSACTIONS ON TSX.

NEITHER THE SECURITIES REPRESENTED HEREBY NOR THE COMMON SHARES TO BE ISSUED UPON THEIR EXERCISE HAVE BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933, AS AMENDED (THE “U.S. SECURITIES ACT”), OR THE SECURITIES LAWS OF ANY STATE OF THE UNITED STATES. THESE SECURITIES MAY NOT BE EXERCISED IN THE UNITED STATES BY OR ON BEHALF OF A U.S. PERSON (AS DEFINED IN REGULATION S UNDER THE U.S. SECURITIES ACT) OR A PERSON IN THE UNITED STATES UNLESS PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE U.S. SECURITIES ACT OR UNLESS AN EXEMPTION FROM REGISTRATION UNDER THE U.S. SECURITIES ACT AND APPLICABLE STATE SECURITIES LAWS IS AVAILABLE, AND THE COMPANY HAS RECEIVED AN OPINION OF COUNSEL OF RECOGNIZED STANDING REASONABLY SATISFACTORY TO THE ISSUER TO THAT EFFECT.

SERIES 2018 WARRANTS TO PURCHASE SHARES

OF

POLYMET MINING CORP.

THIS CERTIFIES THAT, for value received GLENCORE AG, is entitled, at any time prior to the Expiry Time, to purchase, at the Exercise Price, one Share in the capital stock of the Company, for each Warrant evidenced hereby, by surrendering to the Company at its principal office at 100 King Street West, Toronto, Ontario M5X 1C7, this Warrant Certificate, together with a Subscription Form, duly completed and executed, and cash, a certified cheque, money order or bank draft in lawful money of the United States payable to or to the order of the Company for the amount equal to the Exercise Price multiplied by the number of Shares subscribed for, on and subject to the terms and conditions set forth below.

Nothing contained herein shall confer any right upon the Holder to subscribe for or purchase any shares of the Company at any time from and after the Expiry Time, and from and after the Expiry Time

this Warrant Certificate and the Warrants represented hereby, and all rights hereunder shall be void and of no value.

In this Warrant Certificate, including the preamble, unless there is something in the subject matter or context inconsistent therewith, the following expressions shall have the following meanings;

during the 20 consecutive trading days (on each of which at least 500 Shares are traded in board lots) ending the third trading day before such date and the weighted average price shall be determined by dividing the aggregate sale price of all Shares sold in board lots on the exchange or market, as the case may be, during the 20 consecutive trading days by the number of Shares sold or, if not traded on any recognized market or exchange, as determined by the board of directors of the Company, acting reasonably. Whenever the Current Market Price is required to be determined hereunder, the Company shall deliver to the warrant agent a certificate of the Company specifying such Current Market Price and setting out the details of its calculation. In the event of any subsequent dispute as to the determination of the Current Market Price, the Company’s auditors shall make such determination which, absent manifest error, shall be binding for all purposes hereunder;

Subject to the applicable conditions for exercise set out in Section 4 having been satisfied and subject to adjustment in accordance with Section 13, each Warrant shall entitle each Warrantholder thereof, upon exercise at any time after the date that is six (6) months following the Issue Date and prior to the Expiry Time, to acquire one Share upon payment of the Exercise Price.

After the Expiry Time, all rights under any Warrants evidenced hereby, in respect of which the right of subscription and purchase herein provided for shall not theretofore have been exercised, shall wholly cease and terminate and such Warrants and this Warrant Certificate shall be void and of no value or effect.

The Holder may exercise the right of purchase herein provided for by surrendering or delivering to the Company prior to the Expiry Time at its principal office set out on the face page of this Warrant Certificate:

Any Warrant Certificate and cash, certified cheque, money order or bank draft referred to in the foregoing clauses (a) and (b) shall be deemed to be surrendered only upon delivery thereof to the Company at its principal office in the manner provided in Section 28.

This Warrant Certificate is exchangeable, upon the surrender hereof by the Holder, for new Warrant certificates of like tenor, and bearing the same legend, representing, in the aggregate, the right to subscribe for the number of Shares which may be subscribed for hereunder.

Upon delivery and payment as set out in Section 4, the Company shall cause to be issued to the Holder hereof the Shares subscribed for not exceeding those which such Holder is entitled to purchase pursuant to this Warrant Certificate and the Holder hereof shall become a shareholder of the Company in respect of such Shares with effect from the date of such delivery and payment and shall be entitled to delivery of a certificate or certificates evidencing such Shares and the Company shall cause such certificate or certificates to be mailed to the Holder hereof at the address or addresses specified in such subscription within five (5) Business Days of such delivery and payment.

The Company shall cause a register to be kept in which shall be entered the names and addresses of all holders of the Warrants and the number of Warrants held by them.

The Holder may subscribe for and purchase a number of Shares less than the number the Holder is entitled to purchase pursuant to this Warrant Certificate. In the event of any such subscription and purchase prior to the Expiry Time, the Holder shall in addition be entitled to receive, without charge, a new Warrant certificate in respect of the balance of the Shares of which he, she or it was entitled to purchase pursuant to this Warrant Certificate and which were then not purchased.

Notwithstanding any adjustments provided for in Section 13 or otherwise, the Company shall not be required upon the exercise of any Warrants, to issue fractional Shares in satisfaction of its obligations hereunder. Where a fractional Share would, but for this Section 8 have been issued upon exercise of a Warrant, in lieu thereof, there shall be paid to the Holder an amount equal (rounded down to the nearest $0.01) to the product obtained by multiplying such fractional share interest by the Current Market Price at the date of due exercise of the Warrants and delivery by the Holder of a Subscription Form and the Exercise Price in the manner provided in Section 4, which payment shall be made within five (5) Business Days of such delivery and payment.

Nothing in this Warrant Certificate or in the holding of the Warrants evidenced hereby shall be construed as conferring upon the Holder any right or interest whatsoever as a shareholder of the Company.

Nothing herein contained or done pursuant hereto shall obligate the Holder to purchase or pay for or the Company to issue any Shares except those Shares in respect of which the Holder shall have exercised its right to purchase hereunder in the manner provided herein.

All Series 2018 Warrants shall rank pari passu, notwithstanding the actual date of the issue thereof.

(any of such events in subsection 13(a) being called a “Share Reorganization”) then the Exercise Price shall be adjusted as of the effective date or record date of such subdivision, re-division, change, reduction, combination, consolidation or distribution, as the case may be, by multiplying the Exercise Price in effect immediately prior to such effective date or record date by a fraction, the numerator of which shall be the number of Shares outstanding on such effective date or record date before giving effect to such Share Reorganization and the denominator of which shall be the number of Shares outstanding as of the effective date or record date after giving effect to such Share Reorganization (including, in the case where securities exchangeable for or convertible into Shares are distributed, the number of Shares that would have been outstanding had such securities been exchanged for or converted into Shares on such record date or effective date).

Such adjustment shall be made successively whenever any event referred to in this Section shall occur. Upon any adjustment of the Exercise Price pursuant to subsection 1(b) the Exchange Rate shall be contemporaneously adjusted by multiplying the number of Shares theretofore obtainable on the exercise thereof by a fraction of which the numerator shall be the Exercise Price in effect immediately prior to such adjustment and the denominator shall be the Exercise Price resulting from such adjustment.

The Company hereby represents and warrants with and to the Holder that the Company is duly authorized and has the corporate and lawful power and authority to create and issue the Warrants and the Shares issuable upon the exercise hereof and perform its obligations hereunder and that this Warrant Certificate represents a valid, legal and binding obligation of the Company enforceable in accordance with its terms.

The Company shall not be required to deliver certificates for Shares while the share transfer books of the Company are properly closed, prior to any meeting of shareholders or for the payment of dividends or for any other purpose and in the event of the surrender of any Warrant in accordance with the provisions hereof and the making of any subscription and payment for the Shares called for thereby during any such period, delivery of the certificates for Shares may be postponed for a period not exceeding five (5) Business Days after the date of the re-opening of said share transfer books; provided, however, that any such postponement of delivery of such certificates shall be without prejudice to the right of the Holder, if the Holder has surrendered this Warrant Certificate and all required deliveries in accordance with the provisions hereof and made payment during such period, to receive such certificates for the Shares called for after the share transfer books have been re-opened.

Subject as herein provided, all or any of the rights conferred upon the Holder may be enforced by the Holder by appropriate legal proceedings. No recourse under or upon any obligation, covenant or agreement herein contained or in any of the Warrants represented hereby shall be taken against any shareholder, officer or director of the Company, either directly or through the Company, it being expressly agreed and declared that the obligations under the Warrants evidenced hereby, are solely corporate obligations of the Company and that no personal liability whatever shall attach to or be incurred by the shareholders, officers, or directors of the Company or any of them in respect thereof, and any and all rights and claims against every such shareholder, officer or director are being hereby expressly waived as a condition of and as a consideration for the issue of the Warrants evidenced hereby.

If the Warrant Certificate evidencing the Warrants issued hereby becomes stolen, lost, mutilated or destroyed, the Company may, on such terms, as it may in its discretion impose, acting reasonably, issue and countersign a new Warrant certificate of like denomination, tenor and date, and bearing the same legend, as the certificate so stolen, lost, mutilated or destroyed.

This Warrant Certificate shall be governed by, and construed in accordance with, the laws of the Province of Ontario and the federal laws of Canada applicable therein but the reference to such laws shall not, by conflict of laws rules or otherwise, require the application of the law of any jurisdiction other than the Province of Ontario. The parties hereto hereby irrevocably attorn to the non-exclusive jurisdiction of the Courts of the Province of Ontario.

If any one or more of the provisions or parts thereof contained in this Warrant Certificate should be or become invalid, illegal or unenforceable in any respect in any jurisdiction, the remaining provisions or parts thereof contained herein shall be and shall be conclusively deemed to be, as to such jurisdiction, severable therefrom and:

The headings of the articles, Sections, subsections and clauses of this Warrant Certificate have been inserted for convenience and reference only and do not define, limit, alter or enlarge the meaning of any provision of this Warrant Certificate.

Unless otherwise stated, a reference herein to a numbered or lettered article, Section, subsection, clause, subclause or schedule refers to the article, Section, subsection, clause, subclause or schedule bearing that number or letter in this Warrant Certificate.

Whenever used in this Warrant Certificate, words importing the singular number only shall include the plural, and vice versa, and words importing the masculine gender shall include the feminine gender.

In the event that any day on or before which any action is required to be taken hereunder is not a Business Day, then such action shall be required to be taken on or before the requisite time on the next succeeding day that is a Business Day. If the payment of any amount is deferred for any period, then such period shall be included for purposes of the computation of any interest payable hereunder.

Except to the extent otherwise provided herein, in the computation of a period of time from a specified date to a later specified date, the word “from” means “from and including” and the words “to” and “until” each mean “to but excluding”.

This Warrant Certificate and all of its provisions shall enure to the benefit of the Holder and his, her or its heirs, executors, administrators, legal personal representatives, permitted assigns and successors and shall be binding upon the Company and its successors and permitted assigns.

Any notice, document or communication required or permitted by this Warrant Certificate to be given by a party hereto shall be in writing and is sufficiently given if delivered personally, or if sent by prepaid registered mail, or if transmitted by any form of recorded telecommunication, to such party addressed as follows:

PolyMet Mining Corp.

100 King Street West, Suite 5700, Toronto, Ontario, M5X 1C7

Attention:           Patrick Keenan, Chief Financial Officer

Telephone:         (416) 915-4189

Notice so mailed shall be deemed to have been given on the fifth (5th) Business Day after deposit in a post office or public letter box. Neither party shall mail any notice, request or other communication hereunder during any period in which applicable postal workers are on strike or if such strike is imminent and may reasonably be anticipated to affect the normal delivery of mail. Notice transmitted by a form of recorded telecommunication or delivered personally shall be deemed given on the day of transmission or personal delivery, as the case may be. Any party may from time to time notify the other in the manner provided herein of any change of address which thereafter, until change by like notice, shall be the address of such party for all purposes hereof.

The Company hereby covenants and agrees that it will do, execute, acknowledge and deliver, or cause to be done, executed, acknowledged and delivered, all and every such other act, deed and assurance as the Holder shall reasonably require for the better accomplishing and effectuating of the intentions and provisions of this Warrant Certificate.

The parties hereto acknowledge and confirm that they have requested that this Warrant Certificate as well as all notices and other documents contemplated hereby be drawn up in the English language. Les parties aux présentes reconnaissent et confirment qu’elles ont exigé que la présente convention ainsi que tous les avis et documents qui s’y rattachent soient rédigés en langue anglaise.

Time shall be of the essence hereof.

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IN WITNESS WHEREOF the Company has caused this Warrant Certificate to be signed by its duly authorized officer as of this 23rd day of March, 2018.

SCHEDULE “A”

SUBSCRIPTION FORM

100 King Street West, Suite 5700, Toronto, Ontario, M5X 1C7

The undersigned holder of the Warrant Certificate hereby irrevocably subscribes for _____________Shares of PolyMet Mining Corp. (the “Company”) pursuant to the Warrant Certificate at the Exercise Price specified in the said Warrant Certificate and encloses herewith cash or a certified cheque, money order or bank draft payable to the order of the Company in payment of the subscription price therefor. Capitalized terms used but not defined herein have the meanings set forth in the Warrant Certificate.

This Warrant Certificate may only be exercised by the undersigned holder if the undersigned holder is outside of the United States at the time of exercise. The undersigned hereby certifies that the undersigned is not a U.S. Person or a person in the United States, and is not acquiring any of the Shares issuable upon the exercise of the Warrants for the account or benefit of a U.S. Person or a person in the United States. For purposes hereof, “United States” and “U.S. Person” shall have the meanings given to such terms in Regulation S under the United States Securities Act of 1933, as amended.

DATED this______day of___________________________, 20 ____.

If any Warrants represented by the Warrant Certificate are not being exercised, a new Warrant certificate bearing the same legend as the Warrant Certificate will be issued and delivered with the Share certificates.