Exhibit (a)(5)(I)

PERSONAL AND CONFIDENTIAL

March 4, 2014

Board of Directors

AMCOL International Corporation

2870 Forbs Avenue,

Hoffman Estates, IL 60192

Ladies and Gentlemen:

You have requested our opinion as to the fairness from a financial point of view to the holders (other than Imerys SA (“Imerys”) and its affiliates) of the outstanding shares of common stock, par value $0.01 per share (the “Shares”), of AMCOL International Corporation (the “Company”) of the $45.25 in cash per Share (the “Consideration”) to be paid to such holders of Shares pursuant to the Agreement and Plan of Merger, dated as of February 11, 2014, as amended by Amendment No. 1, dated as of February 26, 2014, and Amendment No. 2, dated as of March 4, 2014 (the “Agreement”), by and among Imerys, Imerys Minerals Delaware, Inc., a wholly owned subsidiary of Imerys (“Acquisition Sub”), and the Company. The Agreement provides for a tender offer for all of the Shares (the “Tender Offer”) pursuant to which Acquisition Sub will pay the Consideration for each Share accepted. The Agreement further provides that, following completion of the Tender Offer, Acquisition Sub will be merged with and into the Company (the “Merger”) and each outstanding Share (other than Shares already owned by Imerys or Acquisition Sub, Shares owned by the Company as treasury stock and Shares which are held by a stockholder who is entitled to demand and properly demands appraisal of such shares) will be converted into the right to be paid the Consideration.

Goldman, Sachs & Co. and its affiliates are engaged in advisory, underwriting and financing, principal investing, sales and trading, research, investment management and other financial and non-financial activities and services for various persons and entities. Goldman, Sachs & Co. and its affiliates and employees, and funds or other entities they manage or in which they invest or have other economic interests or with which they co-invest, may at any time purchase, sell, hold or vote long or short positions and investments in securities, derivatives, loans, commodities, currencies, credit default swaps and other financial instruments of the Company, Imerys, any of their respective affiliates and third parties, including Groupe Bruxelles Lambert SA, a significant shareholder of Imerys (“GBL”), or any currency or commodity that may be involved in the transaction contemplated by the Agreement (the “Transaction”) for the accounts of Goldman, Sachs & Co. and its affiliates and employees and their customers. We have acted as financial advisor to the Company in connection with, and have participated in certain of the negotiations leading to, the Transaction. We expect to receive fees for our services in connection with the Transaction, all of which are contingent upon consummation of the Tender Offer, and the Company has agreed to reimburse certain of our expenses arising, and indemnify us against certain liabilities that may arise, out of our engagement. We have provided certain investment banking services to affiliates of GBL from time to time. We may also in the future provide investment banking services to the Company, Imerys, GBL and their respective affiliates for which our Investment Banking Division may receive compensation.

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In connection with this opinion, we have reviewed, among other things, the Agreement; the Offer to Purchase on Schedule TO of Acquisition Sub; the Solicitation/Recommendation Statement of the Company filed on Schedule 14D-9; annual reports to stockholders and Annual Reports on Form 10-K of the Company for the five years ended December 31, 2013; certain interim reports to stockholders and Quarterly Reports on Form 10-Q of the Company; certain other communications from the Company to its stockholders; certain publicly available research analyst reports for the Company; and certain internal financial analyses and forecasts for the Company prepared by its management, as approved for our use by the Company (the “Forecasts”). We have also held discussions with members of the senior management of the Company regarding their assessment of the past and current business operations, financial condition and future prospects of the Company; reviewed the reported price and trading activity for the Shares; compared certain financial and stock market information for the Company with similar information for certain other companies the securities of which are publicly traded; reviewed the financial terms of certain recent business combinations in the specialty chemicals industry and in other industries; and performed such other studies and analyses, and considered such other factors, as we deemed appropriate.

For purposes of rendering this opinion, we have, with your consent, relied upon and assumed the accuracy and completeness of all of the financial, legal, regulatory, tax, accounting and other information provided to, discussed with or reviewed by, us, without assuming any responsibility for independent verification thereof. In that regard, we have assumed with your consent that the Forecasts have been reasonably prepared on a basis reflecting the best currently available estimates and judgments of the management of the Company. We have not made an independent evaluation, appraisal or geological or technical assessment of the assets and liabilities (including any contingent, derivative or other off-balance-sheet assets and liabilities) of the Company or any of its subsidiaries and we have not been furnished with any such evaluation, appraisal, geological or technical assessment. We have assumed that all governmental, regulatory or other consents and approvals necessary for the consummation of the Transaction will be obtained without any adverse effect on the expected benefits of the Transaction in any way meaningful to our analysis. We have assumed that the Transaction will be consummated on the terms set forth in the Agreement, without the waiver or modification of any term or condition the effect of which would be in any way meaningful to our analysis.

Our opinion does not address the underlying business decision of the Company to engage in the Transaction, or the relative merits of the Transaction as compared to any strategic alternatives that may be available to the Company; nor does it address any legal, regulatory, tax or accounting matters. This opinion addresses only the fairness from a financial point of view to the holders (other than Imerys and its affiliates) of Shares, as of the date hereof, of the Consideration to be paid to such holders pursuant to the Agreement. We do not express any view on, and our opinion does not address, any other term or aspect of the Agreement or Transaction or any term or aspect of any other agreement or instrument contemplated by the Agreement or entered into or amended in connection with the Transaction, including, the fairness of the Transaction to, or any consideration received in connection therewith by, the holders of any other class of securities, creditors, or other constituencies of the Company; nor as to the fairness of the amount or nature of any compensation to be paid or payable to any of the officers, directors or employees of the Company, or class of such persons, in connection with the Transaction, whether relative to the Consideration to be paid to the holders (other than Imerys and its affiliates) of Shares pursuant to the Agreement or otherwise. We are not expressing any opinion as to the impact of the Transaction on the solvency or viability of the Company or Imerys or the ability of the Company or Imerys to pay their respective obligations when they come due. Our opinion is necessarily based on economic, monetary, market and

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other conditions as in effect on, and the information made available to us as of, the date hereof and we assume no responsibility for updating, revising or reaffirming this opinion based on circumstances, developments or events occurring after the date hereof. Our advisory services and the opinion expressed herein are provided for the information and assistance of the Board of Directors of the Company in connection with its consideration of the Transaction and such opinion does not constitute a recommendation as to whether or not any holder of Shares should tender such Shares in connection with the Tender Offer or how any holder of Shares should vote with respect to the Merger or any other matter. This opinion has been approved by a fairness committee of Goldman, Sachs & Co.

Based upon and subject to the foregoing, it is our opinion that, as of the date hereof, the Consideration to be paid to the holders (other than Imerys and its affiliates) of Shares pursuant to the Agreement is fair from a financial point of view to such holders.

Very truly yours,

/s/ Goldman, Sachs & Co.

(GOLDMAN, SACHS & CO.)

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