Lithium mica slag is a byproduct acquired via the sulfate method of lithium extraction, and it contains a certain quantity of soluble sulfates. The improper storage of lithium mica slag not only takes up a large amount of land resources, but also poses a threat in terms of environmental pollution. Therefore, this study aimed to investigate the mechanism by which SO₄²⁻ dissolves in lithium mica slag, along with the impacts of internal sulfate attacks on mortar specimens with 10%, 20%, and 30% lithium mica slag contents. Testing was carried out in terms of the expansion, mass change, flexural and compressive strengths, porosity, composition, and contents of the products. It was determined that a significant quantity of SO₄²⁻ was generated in mortar specimens with lithium mica slag. The mortar specimens mixed with lithium mica slag produced more ettringite (AFt: 3CaO·Al₂O₃·3CaSO₄·32H₂O), which is the product of internal sulfate attacks. This demonstrates that there was an internal sulfate reaction in the mortar specimens mixed with lithium mica slag. The internal sulfate reaction in mortar samples with lithium mica slag was finished in the later stages. It is noteworthy that the reaction did not lead to any cracking or damage; instead, it later allowed for a retention of strength that was equivalent to the strength of mortar specimens without lithium mica slag. In addition, the partial replacement of cement with lithium mica slag not only reduced the environmental pollution caused by soluble sulfates in lithium mica slag, but also reduced the use of cement and, thus, lowered costs.

Large amounts of chloride ions (Cl⁻) and sulfate ions (SO₄²⁻) are present in salt-washing wastewater, making it unsuitable for direct release. Adsorption can be used to eliminate Cl⁻ and SO₄²⁻ from salt-washing wastewater, and hydrotalcite is an excellent adsorbent with high adsorption properties for these ions because of a layered bimetallic hydroxide structure. The selective extraction of various metals, such as calcium, magnesium, aluminum, and iron, from steel slag via acid leaching facilitates the utilization of steel slag in the preparation of hydrotalcite. In this study, the leaching mechanism of metal in steel slag was investigated using steel slag as a raw material and acetic acid as the reaction medium. The study obtained the optimal leaching mechanism for preparing hydrotalcite. Hydrotalcite was synthesized from the steel slag leaching solution by hydrothermal synthesis, and its structure was characterized. The adsorption performance of Cl⁻ and SO₄²⁻ in salt-washing wastewater was investigated by solution adsorption experiments. The removal rates of Cl⁻ and SO₄²⁻ in salt-washing wastewater reached 12.8% and 38.0%, respectively. After multiple adsorption cycles, the removal rates increased to 98.0% for Cl⁻ and 96.4% for SO₄²⁻.