**Author details**

*Iron Ores*

**5. Conclusion**

Du et al. [102–103] combined the magnetic flocculation technology with ironcontaining materials to prepare porous magnetic seeds with core-shell structure, which achieved simultaneous removal of starch and phosphate in wastewater. As shown in **Figure 10**, the core-shell magnetic seeds prepared by sulfation roasting of fine magnetite particles have a porous α-Fe2O3 structure on the surface, and the specific surface area is three times larger [103–106]. As shown in **Figure 10**, the phosphate and starch in the wastewater can be adsorbed on magnetic seeds surface, and then separated from the wastewater by magnetic separation. The phosphorus and starch content in the wastewater are reduced to 1.51 and 9.51 mg/L, respec-

The iron removal method of the hydrometallurgical leachate is still dominated by the goethite process. The goethite process faces the disadvantages of high loss rate of valuable metals and difficulty in separation and filtration, which must be solved to get qualitative improvement. Careful adjustment of the pH value can help reduce metal loss, and inducing crystallization can increase the crystallinity of goethite and improve the separation and filtration efficiency. However, both methods can only focus on solving one of the problems and cannot reduce loss and promote filtration at the same time. The magnetite produced during the precipitation (crystallization) process opened a new path for magnetic separation, while the magnetite method is currently limited to laboratory research. In the present paper, the authors combined the goethite precipitation (crystallization) method with magnetic seed separation technology and developed a novel route. Goethite precipitates on the surface of the external magnetic seeds to form core-shell structured particles, which are efficiently separated by magnetic separation, and at the same time solve the two major problems of the traditional goethite process. This new method also shows advantages in the fields of arsenic and chromium removal from the leachate, phosphorus, and starch removal from wastewater and other fields. Goethite is the most common and stable crystalline iron oxide in soil and sediment. We expect that the goethite method combined with magnetic seed separation technology will show better results in the removal of organic dyeing, heavy metal ions, anions in wastewater and soil, and the adsorption and passivation of chemicals,

This work was supported by the Hunan Natural Science Foundation of China

(No. 2020JJ5727), Innovation Driven Plan of Central South University (No. 2018CX036), National 111 Project (No. B14034), and Collaborative Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources, Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic

tively, and the removal rate reaches more than 75% [102].

nutrients, and harmful compounds in environments.

Calcium-containing Mineral Resources (No. 2018TP1002).

**Acknowledgements**

**44**

Haisheng Han1,2\*, Wenjuan Sun1,2, Wei Sun1,2 and Yuehua Hu1,2

1 School of Minerals Processing and Bioengineering, Central South University, Changsha, China

2 Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources, Central South University, Changsha, China

\*Address all correspondence to: hanhai5086@csu.edu.cn

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
