Hokkaido University · Engineering
Professor Marthias Silwamba's research lab specializes in sustainable metallurgy and environmental remediation, focusing on the recovery of critical and hazardous metals from secondary sources such as industrial residues, contaminated soils, and electronic waste. The lab develops innovative hydrometallurgical techniques—particularly concurrent leaching and cementation using zero-valent metals like aluminum and iron—to simultaneously extract and stabilize valuable or toxic metals such as lead, zinc, gallium, germanium, and indium. A key emphasis is placed on designing environmentally benign, resource-efficient processes that enable metal recovery while minimizing environmental impact, often integrating magnetic separation for efficient solid-liquid separation. The lab’s work bridges resource recovery, pollution control, and circular economy principles, with strong relevance to sustainable development and critical raw material security.
Figures are computed from collected data and may differ slightly.
Zinc plant leach residues (ZPLRs) contain significant amounts of metal compounds of lead (Pb), zinc (Zn), iron (Fe), etc., hence, they are considered as a secondary source of metals. On the other hand, ZPLRs are regarded as hazardous materials because they contain heavy metals that pollute the environment. Resources and environmental concerns of ZPLRs were addressed in this study by removing/recovering Pb and Zn using a concurrent dissolution and cementation technique. To cement the dissolved Pb
Zinc plant leach residues (ZPLRs), particularly those produced using old technologies, have both economic importance as secondary raw materials and have environmental impacts because they contain hazardous heavy metals that pose risks to human health and the environment. Therefore, the extraction and recovery of these metals from ZPLRs has both economic and environmental benefits. In this study, we investigated the removal of lead (Pb) and zinc (Zn) from ZPLRs by alkaline (NaOH) leaching and the
Lead (Pb) contaminated soils pose serious risks to human health and the environment. One remediation technique that permanently removes Pb is chemical soil washing. This study investigated a modified chemical soil washing technique whereby Pb extraction in citrate solution and recovery of dissolved Pb by reductive precipitation (cementation) were simultaneously carried out in a single reactor by the addition of micro-sized zero-valent iron (mZVI) to decontaminate Pb-contaminated soil from a shoo
Gallium (Ga), germanium (Ge), and indium (In) are essential elements that are extensively used in high-technology products in many fields. These metals are listed as critical elements by many governments and private players because they face potential supply risks due to geopolitics and stockpiling. Gallium, germanium, and indium do not form primary minerals that can be economically exploited on their own. Instead, they are obtained as by-products during the primary extraction of other minerals,
In 2015, 193 governments agreed to act on climate change by drastically reducing carbon dioxide (CO2) emissions as envisaged in the sustainable development goal (SDG) number 13 [...]
Zinc leach residues (ZLRs) are hazardous materials because they contain toxic heavy metals such as lead (Pb) and pose serious risks to the ecosystem and people living nearby. This study investigated Pb removal from ZLRs collected from Kabwe (Zambia), one of the most Pb-polluted towns in the world, using carrier-in-pulp method. ZLRs and zero-valent iron (ZVI), which was used as the carrier, were simultaneously mixed in NaCl solution. Pb was extracted from ZRLs and formed Pb-chloride complexes, wh
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