Minnesota Commitment | Global Opportunity

Investor Presentation Minnesota Commitment Global Opportunity Cautionary Note Regarding Mineral Resource Estimates POLYMET MINING Resources quoted are sourced from the Technical Report prepared under Canadian National Instrument 43 101- Standards of Disclosure for Mineral Projects ("NI 43-101") for PolyMet entitled "North Met Copper Nickel Project Feasibility Update," dated December 30, 2022, ("PolyMet Technical Report") as filed under the Company's SEDAR and EDGAR profiles, and the Technical Report entitled "Mesaba Project Form 43-101F1 Technical Report Mineral Resource Statement" ("Mesaba Technical Report") effective as of November 28, 2022, as filed on SEDAR and SEDAR. PolyMet Technical Report Proven & Probable Reserves are from Table 1-1 of the PolyMet Technical Report. Measured, Indicated, Measured & Indicated, inclusive of Mineral Reserves, and Inferred resources are from Table 1-2 of that same report. Mineral resources are not mineral reserves and do not have demonstrated economic viability. There is no certainty that all or any part of the mineral resources estimated will be converted into mineral reserves. A copper price of $3.16 per pound, a nickel price of $5.90 per pound, a cobalt price of $25.00 per pound, a palladium price of $1150 per ounce, a platinum price of $1,100 per ounce, a gold price of $1,450 per ounce and a silver price of $20.00 per ounce was used to estimate mineral reserves at the NorthMet Project. A copper price of $3.66 per pound, a nickel price of $6.78 per pound, a cobalt price of $28.75 per pound, a palladium price of $1,323 per ounce, a platinum price of $1,265 per ounce, a gold price of $1,668 per ounce and a silver price of $23.00 per ounce was used to estimate mineral resources at the NorthMet Project. Mineral reserves are estimated at an NSR cut-off of $9.39 per ton inside of the final pit design which includes the estimated plant operating costs (including rail handling costs), all G&A costs and the water treatment costs during pit operation. For a description of the key assumptions, parameters and methods used to estimate mineral reserves and resources, as well as data verification procedures and a general discussion of the extent to which the estimates of scientific and technical information may be affected by any known environmental, permitting, legal title, taxation, sociopolitical, marketing or other relevant factors, please see the PolyMet Technical Report. The scientific and technical information contained in this presentation regarding the North Met Project has been reviewed and approved by: Alberto Bennett, Daniel Neff, Daniel Roth and Laurie Tahija of M3 Engineering & Technology Corporation, Nicholas Dempers of SENET (Pty) Ltd., Thomas J. Radue and Jeff Ubl of Barr Engineering Co., Richard Schwering of Hard Rock Consulting, Herbert E. Welhener of Independent Mining Consultants, and Tad Crowie of JDS Energy & Mining Inc., who are all Independent Qualified Persons within the meaning of NI 43-101. Mesaba Technical Report The Mesaba Technical Report is preliminary in nature, includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves, and there is no certainty that the mineral resources set out in the Mesaba Technical Report will be realized. Mineral resources that are not mineral reserves do not have demonstrated economic viability. There is no certainty that all or any part of the mineral resource will be converted into mineral reserve. It is uncertain if further exploration will allow improving the classification of the Indicated or Inferred mineral resource. The scientific and technical information contained in this presentation regarding the Mesaba Project has been reviewed and approved by: Andrew Ware, P.Geo. and a qualified person for purposes of NI 43-101. 3

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