<p>This study investigates the leaching characteristics of rare-earth elements (REEs) from ion-adsorption clay-type weathered granite deposits sourced from the Sisoding area, North Sumatera Province, Indonesia. The leaching characteristics of REEs were firstly examined by a conventional ion-exchange leaching method utilizing ammonium sulfate/(NH₄)₂SO₄; however, the results revealed the ineffectiveness of this process for recovering REEs. Subsequently, the leaching of REEs was examined utilizing a non-ammonia solution, specifically hydrochloric acid (HCl). The effect of leaching variables and optimization were carried out by assessing the effects of HCl concentration, leaching time, pulp density, and temperature, utilizing the Taguhi method with L₉ orthogonal matrix. ANOVA was used to determine the most significant variable on the REE dissolution. The optimal conditions were determined as follows: 6.0&#xa0;M HCl, 2&#xa0;h leaching time, 200&#xa0;g/L pulp density, and 90&#xa0;°C, resulting in 82.1% leaching of REEs, along with 26.7% Al and 80.3% Fe co-extraction. The HCl leaching specifically demonstrates the occurrence of chemisorption of REEs in this deposit, hence, requiring more severe conditions for optimal REEs leaching. The kinetic study utilized the shrinking core model (SCM), revealing that the leaching of REEs was governed by mixed control (a combination of diffusion and chemical reaction control), with an activation energy of 44.0&#xa0;kJ/mol (in the temperature range of 50–90&#xa0;°C).</p> Graphical Abstract <p></p>