**4. Conclusions**

SAD is a hazardous solid waste as well as an alumina-rich resource. The safe disposal and cost-effective recycling of SAD are serious challenges. A combined dry pressing and alkali roasting process was developed for the sustainable extraction of the valuable Al element from SAD. Based upon the results, the following conclusions can be drawn:


seed decomposition can be conducted on synthesized metallurgical grade alumina in future.

**Author Contributions:** Conceptualization, H.L. and F.L.; methodology, M.X.; software, Z.W. and L.L.; investigation, R.Y. and J.H.; writing—original draft preparation, H.L.; writing—review and editing, H.Z. and F.L.; funding acquisition, F.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the National Key Research and Development Program of China, grant number 2019YFC1908403.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
