Development of bioflocculants for mineral processing

Mining and minerals processing are essential to modern society, and the demand for metals and minerals is increasing due to the rapid development of clean energy technologies, such as electric vehicles, solar panels, wind turbines, etc. The mining industry, however, is facing significant challenges in meeting sustainability and environmental goals. As more minerals are extracted, the use of water increases, leading to greater wastewater and tailings production. To tackle this issue, flocculants are commonly used across mining sites to dewater waste streams by binding and settling particles, to allow for improved solid-liquid separation. While conventional flocculants (synthetic polymers often derived from petrochemicals) are effective in rapidly settling particles, they present several issues, such as high levels of entrapped water, ineffective fine particle separation, and environmental and health concerns. To address these challenges, bioflocculants have been proposed as alternative flocculants. This review explores three main bioflocculant research directions, including plant based, graft copolymers, and microbial flocculants, discussing the advantages and disadvantages of each. The ratio of flocculant dose to suspended solids (i.e. flocculant dose ratio) and the flocculation efficiency in these studies related to mineral and mining wastewater solid-liquid separation are evaluated. Finally, the review proposes future opportunities and directions to mitigate issues that have historically made bioflocculants less appealing. These include enhancing the recyclability of flocculants as well as advancing protein design and modification.