<p>Boron mud is an alkaline solid waste generated during the production of boron products, and its utilization ratio is low. The accumulation of boron mud not only poses environmental hazards but also results in resource waste. Therefore, it is imperative to develop a new method for the value-added utilization of boron mud. Because boron mud has a high MgO content, a process combining selective leaching and stepwise precipitation was proposed to recover MgO. The Mg-bearing magnesite and magnesian olivine were readily dissolved in the dilute acid solution compared to other mineral phases. Under optimal conditions (pH 2.0, temperature 60&#xa0;℃, solid-to-liquid ratio of 1:10, and 30% HCl), the leaching ratio of Mg from boron mud was the highest, reaching 63.26%, while the leaching ratios of Si and Fe were lower. The selective leaching of Mg was achieved. After leaching, a stepwise precipitation was employed to recover Mg from the leachate. The pH of leachate was first increased to 7.0 to precipitate Si and Fe. Then, the pH of the purified leachate was further increased to 11.0. A large amount of Mg(OH)₂ was precipitated and a MgO powder with purity of 96.52% was obtained after calcination. In this process, approximately 60% of Mg was recovered from the boron mud in the form of high-quality MgO. The residue without alkalinity mainly composed of SiO₂, Fe₂O₃ and MgO. An efficient and low-cost method for the comprehensive utilization of boron mud was developed.</p> Graphical Abstract <p></p>