International Tower Hill Mines Provides Progress Report on Antimony Metallurgy Study at the Livengood Gold Project

Rhea-AI Summary

International Tower Hill Mines (NYSE American: THM) has reported encouraging initial results from its antimony metallurgical study at the Livengood Gold Project. The study, which began in March 2025, focuses on examining antimony mineralization in the project's 54 massive stibnite veins.

The first phase testing on four vein composites, conducted by AMTEL, revealed that antimony is carried by stibnite, with most particles being of floatable size and showing good liberation at p80 250 micron grind size. The project already contains a 9.0 million ounce proven and probable gold reserve within a 13.6 million ounce measured and indicated resource, projecting 6.4 million ounces of gold production over 21 years.

The company will proceed with the next phase of testing at SGS Vancouver and SGS Lakefield to assess potential flowsheets and evaluate flotation responses. However, extensive additional metallurgical work is required before determining antimony recoverability or developing economic analyses.

Positive

• Initial metallurgical results show good antimony liberation potential from stibnite veins
• Project contains substantial 9.0M oz proven and probable gold reserves
• Projected 6.4M oz gold production over 21-year mine life

Negative

• Extensive additional metallurgical work required before determining antimony recoverability
• No economic analysis or resource estimates available for antimony content yet

Insights

Mining Industry Analyst

Promising antimony recovery potential could add value to Livengood's established 9M oz gold reserve, though still in early testing phases.

The preliminary metallurgical study results on antimony mineralization at International Tower Hill's Livengood project represent a potentially significant development for the project's economics. While Livengood is already substantial with 9.0 million ounces of proven and probable gold reserves within a 13.6 million ounce resource, the addition of recoverable antimony could enhance the project's value profile.

The initial results are technically encouraging. The four vein samples showed antimony concentrations ranging from 1.05% to 2.75%, with corresponding gold values between 3.21-4.19 g/t. The critical findings reveal that antimony is carried by stibnite in floatable size particles (>10 micron) with good liberation at the same grind size (p80 250 micron) already established for gold processing. This compatibility with the existing grinding parameters is particularly advantageous as it suggests antimony recovery could potentially be incorporated without major modifications to the planned processing circuit.

Antimony is classified as a critical mineral in many jurisdictions due to its applications in flame retardants, batteries, and military applications. The market for antimony has been volatile but generally trending upward with supply constraints from traditional sources. The ability to produce antimony as a by-product could provide valuable revenue diversification and potentially improve project economics.

However, investors should note the very preliminary nature of these findings. The company appropriately emphasizes that extensive additional metallurgical work and economic analysis would be required before any resource estimates or recovery projections for antimony could be established. The next phase at SGS facilities will determine flotation response and concentrate characteristics – critical factors in determining whether antimony recovery would be economically viable.

VANCOUVER, BC, Sept. 4, 2025 /PRNewswire/ - International Tower Hill Mines Ltd. (the "Company") - (TSX: ITH) (NYSE American: THM) today announced that it has received encouraging results from the first phase of the metallurgical study on antimony mineralization at the Livengood Gold Project that was announced on March 4, 2025. 

The Company's most recent S-K 1300 Technical Report Summary, "Pre-Feasibility Study of the Livengood Gold Project", as amended October 13, 2023, presented a new geologic model for the Livengood deposit and detailed gold metallurgical work that allowed the relationship between gold recovery and antimony mineralization to be characterized. During this geological modelling process, 54 veins of massive stibnite were detailed as presented in Table 11-8 "Livengood deposit massive stibnite grade estimates" of the S-K 1300 Technical Report Summary. While the pre-feasibility study detailed the 9.0 million ounce proven and probable gold reserve contained within the 13.6 million ounce measured and indicated gold resource, with 6.4 million ounces of gold production projected over 21 years, no metallurgical studies had been completed at that time to provide an understanding of whether antimony might be recoverable from the massive stibnite veins.

Subsequent to the announcement on March 4, 2025, the Company compiled four metallurgical composites, each from individual veins, and provided splits from the composites to Advanced Mineral Technology Laboratory Ltd., London, Ontario (AMTEL) for antimony deportment work. The gold and antimony assays for these samples are presented in Table 1 below.

Table 1. Livengood Gold Project Vein Composite Assays

Sample	Au g/mt	Sb%
SB12	4.19	2.75
SB24	3.72	2.31
SB40	3.31	1.41
SB46	3.21	1.05

The samples were milled to p80 of 250 micron (the same grind size as selected in the 2023 Technical Report Summary for the 9.0 million ounce proven and probable gold reserve based on optimization studies). The milled material was separated by size and mineralogy and then examined. Results for all samples indicate that the antimony is carried by stibnite, that most of the stibnite is of a floatable size (>10 micron), that the liberation of stibnite is very good at the grind size of p80 250 micron, and thus the samples have the potential to respond well to flotation.

These results warrant continuation into the next phase of the test work to assess potential flowsheets, to evaluate how the samples respond to flotation, and to determine what the characteristics of any concentrate obtained might be. The Company intends to commence this work immediately at SGS Vancouver and SGS Lakefield. The data presented here is very preliminary in nature and simply indicates a further examination of the metallurgy of the antimony carried by the stibnite veins is warranted. Much more metallurgical and extensive other work would be required before any determination of the recoverability of the antimony could be established, as well as before any economic analysis or estimates of tonnage, grade or resource could be developed.

Forward-Looking Statements

Statements in this press release that are not statements of historical or current fact constitute "forward-looking statements" within the meaning of the U.S. Private Securities Litigation Reform Act of 1995, as amended, Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended, and "forward-looking information" within the meaning of applicable Canadian securities laws (collectively, "forward-looking statements"). Such forward-looking statements involve known and unknown risks, uncertainties, and other factors that could cause the actual results of the Company to be materially different from historical results or from any future results expressed or implied by such forward-looking statements. In addition to statements which explicitly describe such risks and uncertainties, readers are urged to consider statements containing the terms "intends," "estimates," "may," "might", "will," or other similar expressions to be uncertain and forward-looking. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. The forward-looking statements in this press release, including statements regarding estimates of the quality and quantity of the mineral resources at the Livengood Gold Project, including gold and antimony, and the potential for production at the Livengood Gold Project are based upon the Company's current expectations and involve assumptions that may never materialize or may prove to be incorrect. Actual results and the timing of events could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties, including, without limitation: (i) the demand for, and level and volatility of the price of, gold, (ii) general business and economic conditions, (iii) the accuracy of the Company's resource estimates (including with respect to size and grade) and the geological, operational and price assumptions on which these are based, (iv) the timing of the Company's ability to commence and complete planned work programs at the Livengood Gold Project, including the antimony study, (v) the Company's ability to attract and retain key staff, particularly in connection with the permitting and development of any mine at the Livengood Gold Project, and (vi) the Company's ability to secure the necessary services and supplies on favorable terms in connection with its programs at the Livengood Gold Project and other activities. The foregoing list of important factors that could cause actual events to differ from expectations should not be construed as exhaustive and should be read in conjunction with statements that are included herein and elsewhere, including the risk factors detailed in the "Forward-Looking Statements," "Risk Factors" and "Management's Discussion and Analysis of Financial Condition and Results of Operations" sections of the Company's Annual Report on Form 10-K for the fiscal year ended December 31, 2024, Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025 and the Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2025 and other documents that have been and will be filed by the Company from time to time with the Securities and Exchange Commission and Canadian securities regulators. All forward-looking statements contained in this press release speak only as of the date on which they were made. The Company undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made, except as required by applicable securities laws.

About International Tower Hill Mines Ltd.

International Tower Hill Mines Ltd. has a 100% interest in its Livengood Gold Project located along the paved Elliott Highway, 70 miles north of Fairbanks, Alaska.

On behalf of
International Tower Hill Mines Ltd.

(signed) Karl L. Hanneman
Chief Executive Officer

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SOURCE International Tower Hill Mines Ltd.

FAQ

What are the key findings from THM's antimony metallurgical study at Livengood Gold Project?

The study revealed that antimony is carried by stibnite, with most particles being of floatable size and showing good liberation at p80 250 micron grind size, indicating potential for successful flotation processing.

How much gold reserves does THM's Livengood Gold Project contain?

The Livengood Gold Project contains 9.0 million ounces of proven and probable gold reserves within a larger 13.6 million ounce measured and indicated resource.

What is the projected gold production at THM's Livengood Project?

The project is projected to produce 6.4 million ounces of gold over a 21-year period.

What are the next steps in THM's antimony metallurgical study?

THM will proceed with testing at SGS Vancouver and SGS Lakefield to assess potential flowsheets, evaluate flotation responses, and determine concentrate characteristics.

What were the antimony grades in THM's test samples?

The test samples showed antimony grades ranging from 1.05% to 2.75% Sb across four vein composites, with corresponding gold grades of 3.21 to 4.19 g/mt.