1 LITHIUM STRATEGY UPDATE // Sept. 15, 2022

2 This presentation may contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, including, without limitation, statements about the company’s efforts to create a safe and inclusive workplace and manage its environmental impact, the company’s ESG approach, and the company’s proposed lithium resource development, including its expected production, required permitting, environmental impact, growth potential, ability to reduce the company’s weather dependency, value, costs, cash flow, synergies with existing operations, ability to leverage existing infrastructure, ability to produce high-quality, battery-grade lithium, lithium demand and pricing, emissions footprint, resource life, development timing and phases, operating costs, CAPEX, NPV, IRR, capital intensity, global warming potential, finalization of definitive agreements with partners, timeline of project milestones, funding considerations, capital requirements, and upside for share valuation. Forward-looking statements are those that predict or describe future events or trends and that do not relate solely to historical matters. The Company uses words such as “may,” “would,” “could,” “should,” “will,” “likely,” “expect,” “anticipate,” “believe,” “intend,” “plan,” “forecast,” “outlook,” “project,” “estimate” and similar expressions suggesting future outcomes or events to identify forward-looking statements or forward-looking information. These statements are based on the company’s current expectations and involve risks and uncertainties that could cause the company’s actual results to differ materially. The differences could be caused by a number of factors, including, without limitation: (i) uncertainties in estimating the company’s lithium resource; (ii) assumptions underlying the estimates of NPV and IRR in the economic model used to demonstrate economic potential of the lithium resource, including expected production rates, estimates of capital and operating costs, and anticipated synergies with the existing operations at the GSL/Ogden site, may prove inaccurate; (iii) the timing of obtaining necessary governmental authorizations; (iv) the company’s ability to convert all or any part of the lithium mineral resource identified by the initial assessment into an economically extractable mineral reserve, including the availability and cost of capital for related capital expenditures and the development of applicable processing technologies; (v) the company’s ability to replicate the results of pilot testing of the selected DLE technology at scale; (vi) weather conditions; (vii) foreign exchange rates and the cost and availability of transportation for the distribution of the company’s products; (viii) changes in market demand, pressure on prices and impact from competitive products; (ix) any inability by the company to successfully implement its strategic priorities or its cost-saving or enterprise optimization initiatives; (x) the risk that the company may not realize the expected financial or other benefits from the proposed development of its lithium mineral resource or its investment in Fortress North America; (xi) inflation; (xii) impacts of the COVID-19 pandemic, or other outbreaks of infectious disease or similar public health threats; (xiii) changes in laws, industry standards and regulatory requirements; and (xiv) other risks referenced from time to time in the company’s filings with the Securities and Exchange Commission (SEC), including in Part I, Item 1A, “Risk Factors” of the company’s Transition Report on Form 10-KT for the transition period ended September 30, 2021 and Part II, Item 1A, “Risk Factors” of the company’s Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2022. The company undertakes no obligation to update any forward-looking statements made in this presentation to reflect future events or developments, except as required by law. Because it is not possible to predict or identify all such factors, this list cannot be considered a complete set of all potential risks or uncertainties. Forward-Looking Statements

3 Certain information in this presentation concerning the proposed lithium development project, including expected production, projected life-of-project, mineral resource estimates and the sensitivity analysis presented at the end of this presentation, has been derived from the Technical Report Summary: Updated Initial Assessment, Lithium Mineral Resource Estimate, Compass Minerals International, Inc. GSL/Ogden Site; Updated Report Date: Sept. 14, 2022 (the Updated Compass Minerals Lithium TRS). The Updated Compass Minerals Lithium TRS, which updates the company’s previous technical report summary with respect to lithium and LCE mineral resource estimates filed with the SEC in 2021, was prepared by qualified persons and summarizes the results of an initial assessment to define the lithium resource at Compass Minerals’ existing operations in accordance with applicable SEC regulations, including Subpart 1300. Pursuant to Subpart 1300, mineral resources are not mineral reserves and do not have demonstrated economic viability. The company’s mineral resource estimates, including estimates of the lithium resource, are based on many factors, including assumptions regarding extraction rates and duration of mining operations, and the quality of in-place resources. For example, the process technology for commercial extraction of lithium from brines with low lithium and high impurity (primarily magnesium) is still developing. Accordingly, there is no certainty that all or any part of the lithium mineral resource identified by the company’s initial assessment will be converted into an economically extractable mineral reserve. Reference should be made to the full text of the Updated Compass Minerals Lithium TRS for further information regarding the assumptions, qualifications and procedures relating to the estimates of mineral resources as defined in Subpart 1300. Certain other information in this presentation concerning the proposed lithium development project, including estimated capital expenditures and operating costs, expected after-tax NPV and IRR and assumed average lithium carbonate selling price, are based on estimates that management used for corporate planning purposes. Cautionary Statement Regarding Material Resource Estimate

4 A G E N D A Lithium Strategy and Investment Thesis | Kevin Crutchfield, President and CEO Lithium Project Overview | Chris Yandell, Head of Lithium Direct Lithium Extraction (DLE) Technology | Dr. Ryan Bartlett, Senior Vice President, Lithium Commercial and Technology Project Economics | Chris Yandell, Head of Lithium Funding Strategy & Valuation Considerations | Lorin Crenshaw, Chief Financial Officer Q&A | Kevin Crutchfield, Chris Yandell, Ryan Bartlett, Lorin Crenshaw

5 Focused on sustainability and safety Our Workforce. We strive to create a safe and inclusive workplace where everyone has a voice and every voice matters Our Communities. We value partnerships with local stakeholders and play an integral role in supporting local economies Our Environment. We are dedicated to the responsible transformation of the Earth’s natural resources while managing our environmental impact ~2.4M metric tons LCE total lithium mineral resource3 ~$185M Adjusted EBITDA1,2 175+ years in operation ~$1.2B in annual revenue1 Leading salt producer in North America and the U.K. Largest sulfate of potash (SOP) producer in the Western Hemisphere Compass Minerals at a Glance 1 TTM results are reported for the twelve-month period from July 1, 2021, to June 30, 2022; representing only the continuing operations of the company. 2 Non-GAAP measure; see appendix for reconciliation to operating earnings, the most directly comparable GAAP financial measure. 3 Technical Report Summary: Updated Initial Assessment, Lithium Mineral Resource Estimate, Compass Minerals International, Inc. GSL/Ogden Site; Updated Report Date: Sept. 14, 2022. (Updated Compass Minerals Lithium TRS).

6 Led by an Experienced Senior Management Team Kevin S. Crutchfield PRESIDENT AND CHIEF EXECUTIVE OFFICER Rick Axthelm CHIEF PUBLIC AFFAIRS AND SUSTAINABILITY OFFICER Dr. Ryan Bartlett SENIOR VICE PRESIDENT, LITHIUM COMMERCIAL AND TECHNOLOGY Lorin Crenshaw CHIEF FINANCIAL OFFICER Rob Fisher CHIEF INFORMATION AND TRANSFORMATION OFFICER Mary Frontczak CHIEF LEGAL AND ADMINISTRATIVE OFFICER AND CORPORATE SECRETARY George Schuller, Jr. CHIEF OPERATIONS OFFICER Jamie Standen CHIEF COMMERCIAL OFFICER Chris Yandell HEAD OF LITHIUM Speaking Today

7 Kickoff formal Li project and team Total Lithium Resource1 ~2.4M (metric tons LCE) Interstitial Brine Resource1 ~127k (metric tons LCE) Existing Evaporation Ponds ~55k (acres) Minimal environment impact anticipated Utilizing existing ponds, pumps and transportation infrastructure 1 See Updated Compass Minerals Lithium TRS. 2018 2019 2020 2021 2022 Retained SRK to complete scope of opportunity/industry Drilling and sampling campaign begins Engaged first potential DLE provider First DLE pilot plant on site Engaged EnergySource Minerals EnergySource Minerals pilot on site Additional potential DLE pilot on site EnergySource Minerals pilot complete Publicly announced lithium resource Ogden site formed as part of Lithium Corporation of America 19701962 First production of sulfate of potash from Ogden site EnergySource Minerals selected as DLE provider On-track for expected production in 2025 Compass Minerals Lithium Journey and Overview Acquired Ogden in 1993 Annual Target Production (metric tons LCE) ~11k in Phase 1 ~24k in Phase 2

8 8 World-Class Assets Provide Potential New Growth Avenues ASSET FOOTPRINT CORE COMPETENCIES PRODUCTS MARKETS Goderich Mine Cote Blanche Mine Winsford Mine Ogden Goderich Plant Lyons Unity Amherst Deicing Industrial Applications Solar & Mechanical Evaporation Sulfate of Potash Magnesium Chloride Consumer & Industrial Salt Lithium1 Rock Salt Chemical Salt Packaged Deicing Plant Nutrients Water Softeners Culinary Animal Nutrition Lithium-ion Batteries (future) Fire Retardants (future) Underground Extraction 1 Expect to enter the market by 2025. Safety Culture, Market Leadership, Logistics Network and Expertise, Experience in Optimizing Mining and Manufacturing Assets Leveraging Core Competencies in Adjacent Markets Expected to Accelerate Growth and Reduce Weather Dependency

9 We approach our environmental, social and governance (ESG) work through a fundamental commitment to four key pillars: safety, growth, transparency and stewardship; together, these pillars form our sustainability compass, guiding our decisions and business practices across all aspects of our company Firmly committed to a culture of trust, transparency and accountability, we seek open and honest communication with our stakeholders, while showing respect for diversity in all its forms We honor our responsibility to serve as good stewards of the natural resources we rely on to produce, manufacture and market essential mineral products, minimize the impact we have on our environment, and recognize the markets we serve may be impacted by a changing climate Striving toward zero harm, our highest priority is ensuring the health and safety of our employees and communities in which we operate We work to enable sustainable, profitable growth by maximizing the value and efficiency of our production assets, investing in our people, driving innovation and exceeding customer expectations ESG “A” Rating Our ESG Approach Guides Our Decisions and Business Practices

10 Unique low-cost, brine-based, brownfield U.S. lithium development project Value Proposition 1 Major Permits in Place, Brownfield Asset Leveraging Existing Infrastructure o One of the largest U.S. brine resources, fully permitted for extraction, expect minimal additional permitting for production, facilitating near-term commercialization Integrated Lithium Capacity in Favorable Geography – U.S. o Anticipate producing high-quality, battery-grade lithium to address significant domestic supply shortage o Strong lithium demand growth projections create favorable pricing environment Operator with Proven Expertise in Brine Extraction o Long-standing operator with deep knowledge in brine processing o +50-year operating history in Ogden Experienced Leadership Team in Place o Development and commercialization led by a leadership team with deep industry and advanced battery supply chain expertise as well as proven track record of delivering on mission critical projects Low Emissions Footprint o Lower emissions footprint compared to other projects anticipated due to use of solar evaporation for brine processing 2 3 4 5 6 Domestic Supply Speed to Market Sustainable Operations Compass Minerals Lithium Low-Cost Position Low-Cost Resource with Attractive Projected Financial Returns o Synergies with existing operations and infrastructure at Ogden expected to facilitate leading cost profile and strong cash flow generation; full project funding1 through 2024 o Large and growing supply shortage continues to fuel robust price environment Compass Minerals is Fully Funded1 through 2024 and Poised to Execute on Lithium and Deliver Value 1 Subject to closing of Koch strategic equity investment and based on FEL-1 level project cost estimates. 10

11 Delivering Responsible Domestic Lithium From an Advanced Brine Project

12 • <1 year at Compass Minerals • 23 years of experience in chemical engineering, chemical production, and commercial leadership Chris Yandell HEAD OF LITHIUM ALBEMARLE PRAXAIR BASF • 5+ years at Compass Minerals • 19 years of experience in innovation, product development, and commercial strategy MONSANTO Dr. Ryan Bartlett SENIOR VICE PRESIDENT, LITHIUM COMMERCIAL AND TECHNOLOGY Clint Parham VICE PRESIDENT, LITHIUM PROCESS AND TECHNOLOGY • <1 year at Compass Minerals • 27 years of experience in chemical production including lithium ALBEMARLE Jordan Taylor VICE PRESIDENT, LITHIUM OPERATIONS • 2+ years at Compass Minerals • 16 years of experience in mining operations, safety, engineering, and greenfield development BHP ANGLO AMERICAN COVIA Vinny Pires LITHIUM SENIOR BUSINESS DIRECTOR • 2+ years at Compass Minerals • 20+ years of experience in commercial strategy, strategic marketing, product management, and business development Jake Prestwich SENIOR DIRECTOR, PROJECTS - LITHIUM • <1 year at Compass Minerals • 20+ years of experience in project management FLSMIDTH RIO TINTO DYNO NOBELCOORSTEK GERDAU Proven Lithium Leadership Team with over 100 Years Combined Experience

13 48% 68% 21% 19% 21% 5% 4% 3% 2% 1% 3% 2% 2% 0% 20% 40% 60% 80% 100% Extraction Capacity Refining Capacity Extraction Capacity vs. Refining Capacity by Country1, % 1 United States Congress, Wood Mackenzie| Wood Mackenzie Estimate, 2022 Capacity. Rest of World Rest of World THE INFLATION REDUCTION ACT OF 2022 Passed into law on August 16, 2022 and includes several new or expanded sources of government support for the development of a domestic clean energy industry Contains up to $7,500 tax credit for electric-vehicle purchases through 2032 1. Requires 40% of the battery minerals for electric vehicles to be mined and processed in the U.S. or partner countries or recycled in North America through 2023, rising to 80% after 2026 2. The target for North American battery-component manufacturing and assembly would rise from 50% to 100% after 2028 Tell [Auto OEMs] to get aggressive and make sure that we’re extracting in North America, that we’re processing in North America and we quit relying on China - Senator Joe Manchin, August 2022 “ “ The Need for Domestically Sourced Lithium has Never Been More Acute and Limited Capacity Exists Today

14 2022 2025 2030 ~500k ~950k ~2,000k 2022 2025 2030 ~40k ~280k ~550k ~5k ~60k ~180k Projected Global Supply2 Projected Global Demand ~470k ~800k ~1,600k ~2% ~2% ~4% ~5% ~19% Aluminum Copper Polypropylene Nickel LCE Battery-grade lithium demand is expected to increase by 7x in North America by 2025 and more than 10x by 2030 1 Wood Mackenzie HIS. 2 Excludes possible projects (defined as those with 60% or less probability); company internal estimates. 3 Benchmark Mineral Intelligence Q2 2022 Report. 4 Demand based on GWh capacity projections. Global Commodity Demand Growth (CAGR 2022 – 2030)1 Projected NA Supply2 Projected NA Demand Global Battery Grade Lithium Supply & Demand3,4 (LCE MT) North American Battery Grade Lithium Supply & Demand3,4 (LCE MT) Exceptional EV Market Fundamentals Continue to Drive Lithium Demand

15Source: Benchmark Mineral Intelligence Lithium Price Forecast Q2 2022, Q1 2022 and Q4 2021; Spot Price: Platts Metals Daily Volume 11- Issue 169 – Sept. 02, 2022. Prices expected to remain high for the next few years and then normalize to a new equilibrium as more supply comes online A low-cost position is essential for projects to deliver long-term value as price normalizes YEAR YEAR Lithium Price Outlook Indicates a Step-Change from Previous Decade

16 Our asset in Ogden, Utah, near the Great Salt Lake, has direct road and rail connectivity and has been operating for 50+ years Compass Minerals has lease rights for 177k acres at the Great Salt Lake Compass Minerals currently extracts three essential minerals from the Great Salt Lake, with distribution across North America No additional permits are expected for accessing the lithium resource; expect minimal additional permitting for lithium production Ogden operations utilize a 3-year pond process cycle to extract essential minerals, creating an effective lithium resource life expectancy of 30+ years Planned domestic lithium production with experienced enterprise support Utilizing existing infrastructure to ramp-up production Utilizing solar evaporation for a sustainable lithium operation Foundational Operations and Anticipated Synergies Drive Project Attractiveness

17 Ogden Lithium Resource: A Two-Phase Growth Opportunity GREAT SALT LAKE Ogden Grantsville Salt Lake City Great Salt Lake – South Arm Provo and Jordan Rivers West Ponds East Ponds Legend Union Pacific RR Causeway Behrens Trench Brine flow through the lake Existing pond structure Bear River Weber River Great Salt Lake – North Arm The advancement of our lithium project is intended to occur over the course of two distinct development phases PHASE 2 WEST SIDE (~24k MT LCE)1 On the east side of the Great Salt Lake, where much of our existing infrastructure is currently located. Anticipated to produce Li2CO3 PHASE 1 EAST SIDE (~11k MT LCE)1 On the west side of the Great Salt Lake, will provide the potential to build an additional DLE processing facility and conversion plant. Anticipated to produce LiOH-H2O 1 See updated Compass Minerals Lithium TRS.

18 Existing Ogden Operations – East Ponds Proposed Phase 1 Site Adjacent to Existing Operations Salt Production Compass Minerals is fully permitted to access its lithium resource and expects minimal additional permitting requirements to produce battery-grade lithium SOP Production MgCl2 Production Proposed Lithium Production ✓ Minerals Rights ✓ Water Rights Royalty Agreement​ with State Revision to Air Permit Revision to Water Discharge Permit Mineral Rights and Permitting Status Enables Speed to Market

19 Traditional Hybrid Purification Crystallization Crystallization Solar Evaporation Brine salt pans, underground brine pools Solar Evaporation Purification ~[Li] ppmStarting Brine Geothermal – Salton Sea5 Great Salt Lake1 North Arm Brine Salar del Hombre Muerto2 Qarhan, Qinghai Lake3 Arkansas Smackover4 CMP post evap. ponds, pre-DLE [Li] ~3857 ppm Commercial Operation Commercial Operation 716 520 210 168 211 10,500 540 66,500 3,000 106 ~[Mg] ppmProcess DLE Only Evaporation + DLE Evaporation + DLE DLE Only DLE Only B R IN E 200Silver Peak, Nevada2 Evaporation 300 Commercial Operation Sources: 1 Updated Compass Minerals Lithium TRS. 2 Jurgen Deberitz, Die Bibliothek der Wissenschaft Vol.2, Lithium. 3 Alex Grant, April 2020: From Catamarca to Qinghai: The Commercial Scale Direct Lithium Extraction Operations. 4 NI 43 – 101 Technical Report, Preliminary Economic Assessment. 5 D. Gagne et al., The Potential for Renewable Energy Development to Benefit Restoration of the Salton Sea: Analysis of Technical and Market Potential Technical Report NREL/TP-7A4. 6 Based on average concentration at our North Arm intake canal. 7 Average, volume weighted concentration considered for Phase 1. Sources of lithium for extraction can include spodumene (hard rock), brine and clay DLE Technology is a Potential Driving Force to Unlock Additional Lithium Supply DLE

20 Direct Lithium Extraction Technology Overview: Selection Process Leading to EnergySource Minerals ILiADTM Technology for Phase 1

21 DLE Type Commercial Examples N/A Potential Advantages/Disadvantages  High lithium elution concentration  Large volumes of acid required 2 Ion Exchange Resin/Material Manganese, Titanium or Lead based C M P D L E C h o ic e 1 Adsorption/ Desorption Catamarca, Argentina Qinghai, China Alumina or Ligand based  Elution with water  Lower lithium elution concentration  Higher operational temperature No acid required  In production currently “Commercially Operating DLE Installations Produced ~12% of the World’s Lithium Supply in 2019” - Alex Grant1 3 Solvent Extraction Organic Solvent based Environmental concern with solvent material  High lithium elution concentration N/A • Compass Minerals has tested both Adsorption/Desorption and Ion Exchange DLE technologies • Adsorption/Desorption technology constitutes the only commercial DLE examples known today • Every brine is unique and not all DLE technologies are as efficient on the same brine • The technology must be tailored to the makeup and specifications of the brine, Compass Minerals has done just this by testing multiple providers DLE Technology Types – Advantages and Disadvantages 1 Alex Grant, April 2020; From Catamarca to Qinghai: The Commercial Scale Direct Lithium Extraction Operations.

22 • Compass Minerals trialed multiple DLE technologies to determine the best fit for our resource and our brine and has assessed five technologies over the past three years • Three DLE technologies have progressed to pilot plants on-site in Ogden, testing brine and different operating parameters to provide detailed data for technology selection, scalability and to help inform next stages of engineering • Two technologies have provided positive results in lithium recovery, magnesium rejection and low environmental impact +++ ++ +++ ++ 2 +++ +++ +++ + 31 ++ ++ ++ ++ 4 ++ + +++ Not Evaluated 5 ++ + +++ Not Evaluated DLE Technology Lithium Recovery Magnesium Rejection Low Environmental Impact Commercial Readiness Li Lithium 3 6,941 Mg Magnesium 12 3s2 24,305 Rigorous Evaluation of DLE Technologies to Identify Best Fit for Our Brine Resource Complete for Phase 1 1 Ion-exchange technology. Compass Minerals has selected EnergySource Minerals as the DLE technology provider for Phase 1

23 ✓ EnergySource Minerals (ESM) is a privately held company leading the development of Project ATLiS, a premier battery-grade lithium hydroxide project located in Imperial County, California ✓ ESM’s experienced team has extensive commercial experience in every stage of lithium project origination, permitting, plant engineering, construction, project financing and operations ✓ ESM has commercialized its patented ILiADTM Technology, a direct lithium extraction technology platform that can unlock brine resources ✓ ESM team includes industry-leading experts in continuous adsorption, ion exchange processes, and battery materials – a few team members are highlighted here: ✓ ESM has developed Integrated ILiAD technology specifically to work with lithium brine resources around the world and has successfully tested on geothermal, salar and petrobrine sources ✓ ESM has tested the ILiAD technology at multiple scales and for more than 5 years ✓ In collaboration with Compass Minerals, ESM has tested ILiAD on Compass Minerals’ brines sourced from the company’s Ogden production facility for more than 3,800 hours For more information: https://www.esminerals.com/i EnergySource Minerals – Background and Information Dr. Charles Marston Senior Development Officer (Leads ILiAD Project) Experience: 30 years of experience in ion exchange and adsorption technology John Featherstone Chief Technical Officer Experience: Over 42 years of geothermal power and mineral extraction experience Dr. David Deak Chief Development Officer Experience: President of Marbex LLC, former CTO of Lithium Americas, ex-Tesla) ILiAD Technology: Forefront of Global Lithium Brine Extraction 23

24 Expected Benefits of ILiAD DLE Technology: ✓ Continuous flow ✓ Countercurrent operation ✓ Globally patent protected ✓ Limited reagents required ✓ Opportunity to recycle ~90% of water used in the DLE process ILiAD TM Direct Lithium Extraction Technology at a Glance % Li Recovery 90%+ 711 3852 1,830 10,500 52,771 1,670 Li Concentration (average ppm) Mg Concentration (average ppm) % Mg Rejection 97%+ On to refining and processing Pre-evap. ponds Pre-DLE Post-DLE Compass Minerals ILiAD testing results have demonstrated robust Li recoveries and Mg rejection rates Feed Brine Li Depleted Brine Strip Water LiCl Product ILiAD Adsorbent Vessels Multi-Port Valve Only two inputs and two outputs with consistent composition; No external recycles, washes, or displacements required All Steps are Performed Simultaneously Return to ponds or other product 1 Based on average concentration at our North Arm intake canal. 2 Average, volume weighted concentration considered for Phase 1.

25 Step 1: Ponds Step 1: Evaporation Ponds Step 2: Pre-Filtration Step 3: ILiADTM DLE Step 4: Softening Step 5: Ion Exchange & Reverse Osmosis Step 6: Evaporation Step 7: Crystallization Step 9: Packaging and Storage Step 8: Drying Inputs Outputs and Co-products North Arm Lake Brine Sodium, Potassium and Magnesium based products Concentrated LiCl brine from DLE and NaOH Softened LiCl Brine and Mg(OH)2 MgCl2 Brine or Interstitial Brine Output and/or Co-product Fate Sales to other industries Pre-filtered Brine and Water Concentrated LiCl brine and spent brine Spent brine recycled to Mg product stream or pond system Mg(OH)2 utilized in other industries or landfill Pre-filtered Brine for DLE Softened LiCl Brine and Mg(OH)2 Purified LiCl Permeate recycled back to DLE Purified LiCl Concentrated LiCl Concentrated LiCl and Soda Ash Crystalized Li2CO3 Crystalized Li2CO3 Final Product Li2CO3 Packaged finished battery grade product Co-product Water recycled back to process Water recycled back to process Residual liquids recycled back to process or to ponds Final productRecycle Recycle Recycle Recycle Recycle Final Product Li2CO3 Option to continue conversion process to LiOHꞏH2O Commonly Used in Li and Other Chemical Process TodayCommonly Used Today Compass Minerals Planned Lithium Production Process – Phase 1 ti Proposed process largely leverages established technologies

26 Low-Cost Operations Expected to Deliver Strong Returns with Minimal Environmental Impact

27 Phase 1 Project Economics Support Substantial Value Creation and Competitive Cost Position Expect to Deliver Strong Financial Returns with Minimal Environmental Impact ~11k (MT LCE/yr) 2025 Production $262M CAPEX $20,645/MT LCE Selling Price (Base +30%) $985M After-tax NPV1 36% After-tax IRR1 $4,347 Cash Cost/MT LCE2 Based on FEL-1 $15,881/MT LCE Selling Price (Base) $626M After-tax NPV1 28% After-tax IRR1 $4,159 Cash Cost/MT LCE2 1 Calculations for NPV and IRR calculated on LOM basis (34 years for East Side) as reflected in the Updated Compass Minerals Lithium TRS. 2 Cash cost includes OPEX with 10% contingency, G&A, and technology license fee based on FEL-1 assumptions (royalties are excluded consistent with industry practice).

28 North American Assets (Brine Evaporation, DLE, and Hard Rock with Conversion)1 Brine - Evaporation Only Brine - DLE Hard Rock with Conversion Brine - Evaporation Only Brine - DLE Global Brine Assets2 • Compass Minerals' lithium project is expected to be among the lowest cost brine-based global lithium producers • Anticipated synergies with existing operations and decades of experience in managing brine are strong advantages over other projects Source: Benchmark Mineral Intelligence Lithium Total Cost Model Q2 2022. 1 Lithium Carbonate C1 cost curve – 2030. 2 Lithium Carbonate C1 cost curve – 2025; C1 Costs include OPEX, G&A, technology license fee and exclude royalties and Sustaining CAPEX. Positioned Favorably Across Global and North American Cost Curves

29 Global Lithium Brine Projects Capital Intensity • Anticipated synergies with existing operations and infrastructure at Ogden facility support competitive capital intensity profile relative to other global brine resources • DLE process adds capital costs versus traditional brine projects; optimization of DLE processes in Phase 2 should lead to lower associated CAPEX Phase 1 Capital Intensity In-Line with Announced Projects Source: Publicly released reports. Size of bubble indicates magnitude of CAPEX.

30 In one year, the sun provides free energy for evaporation equivalent to ~14 million tons of coal Past Awards: • Utah DNR Earth Day • Governor’s Energy Excellence Leadership on: • GSL Advisory Council • GSL Salinity Advisory Committee • Utah Water Quality Board Source: European Metals Cinovec LCA press release, November 2021, Prospective LCA study of CMP potential Phase 1 production. *Compass Minerals' Phase 1 is expected to produce a Lithium Carbonate product while the GWP comparisons shown are the intended battery-grade product of sale. Global Warming Potential (GWP) Comparisons of Battery-Grade Lithium Products Leader in Environmental Stewardship, Sustainability and Engagement 0 5 10 15 20 25 Brine (CL) Compass Minerals Phase 1 Spodumene (AU-CN) Sediment Clay (US) k g C O 2 e q . p e r k g L i C h e m ic a l* LiCO3 LiCO3 LiOH LiOH

314 • Signed non-binding MOUs with Ford and LG Energy Solution • Expect to finalize definitive agreement(s) by end of CY 2022 • Option to commit majority of Phase 2 volume • Pricing based on market / index Phase 1 Phase 2 All Phases ~11k MT LCE ~24k MT LCE ~35k MT LCE Phase 1 - Under negotiation Phase 2 - Under negotiation Available Partnering with leading companies in the EV supply chain will enable us to diversify across a broad spectrum of battery platforms Progressing Our Go-to-Market Strategy with Leading Companies

32 2022 H1 2023 H2 2023 2024 2025 2026 2027 2028 Phase 1 – East Side (estimated at ~11kMT LCE) Phase 2 – West Side (estimated at ~24kMT LCE) FEL 2 (PFS) Commercial scale DLE unit FEL 3 (DFS) Construct East Side Li2CO3 Asset Operate Define FEL 2 / FEL 3 Construct West Side LiOHꞏH2O Asset Operate • Recruitment and development of expertise in lithium conversion process technology • Plan to partner with EPC with a proven track record across multiple projects and industries • Plan to build Phase 2 off learnings from Phase 1 to lower capital intensity and accelerate schedule • Progressing methodically through each stage gate, enabling operational readiness Success through people, partners and process Project timeline and key milestones reflect calendar years. Focused Efforts Across Anticipated Project Timeline and Key Milestones

33 Funding Strategy and Valuation Considerations

344 Funding Considerations • Maintain current credit profile • Strategic partnerships that reduce execution risk and offer value beyond simply capital • Minimize all-in cost of capital • Maximize lithium ownership / exposure to upside • Match funding timing with when capital is needed to enable speed to market and maintain schedule Maximize Value of Lithium and Compass Minerals while Adhering to Financial Policy

35 1H 2023 2H 2023 1H 2024 2H 2024 1H 2025 2H 2025 Project Milestones Capital Requirements Calendar Year: Complete FEL-2 Construct and operate commercial-scale DLE demonstration unit Complete FEL-3 (DFS) Phase 1 East side construction/commissioning ~$100M in 2023 (fully funded1) ~$100M in 2024 (fully funded1) and ~$60M in 2025 ~$262M projected capital requirement between 2023 and 2025 Phase 1 Project Milestones and Capital Requirements • FEL-1 level estimate of 2023 and 2024 funding requirements fully funded1 • ~75% ($200M) of FEL-1 level estimate of total funding requirements has been secured1 • Additional funding requirements to occur after project / technology is de-risked 1 Subject to closing of Koch strategic equity investment and based on FEL-1 level project cost estimates.

36 110 88 78 42 34 32 31 27 24 20 29x 27x 19x 12x Lithium Valuation Benchmarking Market Cap / Transaction Value (US$Bn) 2.0 4.2 2.0 2.8 1.1 1.0 1.2 2.6 0.8 1.0 Key Jurisdiction Major Permits Finalized? ✓ ✘ ✓ ✓ ✘ ✘ ✘ ✓ ✘ ? Market Capitalization / Expected Annual Production, US$ 000 / t LCE Market Cap (US$Bn)1 23 6 26 35 31 Key Jurisdiction 2021A Production (kMt LCE)5 ~90 ~20 ~45 120 ~100 3-year Average EV / NTM EBITDA Lithium Producers43x Average: 26x Source: S&P Global Market Intelligence as of Sept. 13, 2022, Company Filings, Company Presentations. 1 Converted to USD based on 0.76 USD/CAD, 0.68 USD/AUD, 0.14 USD/CNY. 2 Includes production from Thacker Pass (100%) and Cauchari-Olaroz (~45%) Projects. 3 Includes production from Xuxa and Barreiro Projects. 4 Includes production from Lanxess and South-West Arkansas Projects. 5 Production based on company filings and presentations, and converted into LCE based on capacities where historical production split by product not disclosed. Implied Valuation of Ogden Resource Suggests Considerable Upside to Compass Minerals Shares Over Time Brine Developer Hardrock DeveloperPrecedent Transactions Average: 49 Compass Minerals Lithium In-Place Major Permits Brine Resource $626M - $985M Phase 1 NPV ~11k/year Phase 1 Production (MT LCE) $1.4B - $2.2B Phase 2 NPV ~24k/year Phase 2 Production (MT LCE) Lithea 2 3 4

37 Phase 2 Project Economics Support Substantial Value Creation and Competitive Cost Position Expect to Deliver Strong Financial Returns with Minimal Environmental Impact ~28k (MT LiOH/yr) 2028 Production ~$710M CAPEX $21,753/MT LiOH Selling Price (Base +30%) $2.2B After-tax NPV1 30% After-tax IRR $4,462 Cash Cost/MT LiOH2 Based on FEL-1 $16,733/MT LiOH Selling Price (Base) $1.4B After-tax NPV1 23% After-tax IRR $4,216 Cash Cost/MT LiOH2 1 Calculations for NPV and IRR calculated on LOM basis (31 years for West Side) as reflected in the Updated Compass Minerals Lithium TRS. 2 Cash cost includes OPEX with 10% contingency, G&A, and technology license fee based on FEL-1 assumptions (royalties are excluded consistent with industry practice).

38 Capable and Ready to Deliver Our Vision Major Permits in Place, Long-Life Brownfield Asset, Leveraging Existing Infrastructure o One of the largest U.S. brine resources, fully permitted for extraction, expect minimal additional permitting for production, facilitating near-term commercialization Operator with Proven Expertise in Brine Extraction o Long-standing operator with deep knowledge in brine processing o +50-year operating history in Ogden Experienced Leadership Team in Place o Development and commercialization led by a leadership team with deep industry and advanced battery supply chain expertise as well as proven track record of delivering on mission critical projects Low-Cost Resource with Attractive Projected Financial Returns o Synergies with existing operations and infrastructure at Ogden expected to facilitate leading cost profile and strong cash flow generation; full project funding1 through 2024 o Large and growing supply shortage continues to fuel robust price environment Low Emissions Footprint o Lower emissions footprint compared to other projects anticipated due to use of solar evaporation for brine processing Integrated Lithium Capacity in Favorable Geography – U.S. o Anticipate producing high-quality, battery-grade lithium to address significant domestic supply shortage o Strong lithium demand growth projections create favorable pricing environment 1 Subject to closing of Koch strategic equity investment and based on FEL-1 level project cost estimates.

39

40 Appendix

41 Reconciliation of Non-GAAP Information Reconciliation for EBITDA and Adjusted EBITDA (unaudited, in millions) Twelve months ended June 30, 2022 Net loss from continuing operations $ (36.4) Interest expense 54.8 Income tax expense 24.6 Depreciation, depletion and amortization 113.1 EBITDA from continuing operations 156.1 Adjustments to EBITDA: Stock-based compensation - non cash 12.6 Gain on foreign exchange (7.3) Executive transition costs 4.3 Accrued loss and legal costs related to SEC investigation 19.8 Other income, net (0.4) Adjusted EBITDA from continuing operations 185.1 Adjusted EBITDA from discontinued operations 26.0 Adjusted EBITDA $ 211.1

42 10% 15% 20% 25% 30% 35% 17.8% 21.1% 25.9% 35.9% 38.4% 29.4% $268 $509 $549 $985 $743 $704 15.2% 18.0% 21.7% 30.3% 32.4% 25.1% $568 $1,108 $1,213 $2,233 $1,693 $1,588 After-Tax NPV: $626M After-Tax IRR: 27.7% Lithium Sales Price Capex3 Opex Lithium Sales Price Capex3 Opex After-Tax NPV: $1,400B After-Tax IRR: 23.4% Lithium Sales Price Capex3 Opex Lithium Sales Price Capex3 Opex Source: Updated Compass Minerals Lithium TRS | 1 Based on 34-year life; 2 Based on 31-year life; 3 Capex represents development capex and sustaining capex over the life of the asset; 4 Opex includes 10% contingency, G&A, technology license fee based on FEL-1 assumptions and royalties over the life of the asset. Sensitivity Analysis Indicates Economic Value Creation Across a Wide Range of Scenarios Valuation of Phase 1 – East Side (~11k MT LCE)1 Valuation of Phase 2 – West Side (~24k MT LCE)2 $200M $400M $600M $800M $1M 15% 20% 25% 30% 35% 40% -30% -30% +30% +30% $600M $1.0B $1.4B $1.8B $2.2B -30%+30% -30%+30% +30% -30% -30% +30% -30%+30% -30%+30% +30%-30% -30%+30% -30%+30% +30%-30%