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Phytomining of Valuable Metals/Metalloids from Mining Wastes, Tailings and Contaminated Soils
Published in Hossain Md Anawar, Vladimir Strezov, Abhilash, Sustainable and Economic Waste Management, 2019
Hossain Md Anawar, Md Zabed Hossain, I. Santa-Regina, Vladimir Strezov, Farjana Akter
Phytomining of gold and other valuable metals is a ‘green’ approach to the environmentally sensitive and energy intensive practice of mining, involving the use of selective plants to extract valuable metals from both solid and liquid substrates, especially low grade gold ore bodies’ soil or phytomining of precious metals from mining waste and tailings. Gold phytomining not only produces gold ingots but also more importantly, gold nanoparticles (crystallite or primary particles measuring less than 100 nm in size), which have great importance for the rapidly expanding nanoparticle market (Gardea-Torresdey et al., 2005; Haverkamp et al., 2007). The phytomining process improves the quality of the soil for subsequent use of this soil. Phytomining removes metals and increases fertility of the land through improved management practices. The process can minimize the degree of residual leachate that could potentially pollute adjacent water catchments. Furthermore, there is potential to develop industrial synergies with related industries, e.g. by generating renewable energy during the combustion of the plant biomass during metal recovery. This further increases the profitability and sustainability of phytomining. The economics of phytomining basically depends on the soil metal content, metal uptake by the plant, plant biomass, and most importantly the metal price. Before the implementation of phytomining, it is necessary to consider the present metal prices. Gold market prices are increasing continuously and if high gold content and high plant biomass are obtained, phytomining for gold can be profitable.
The potential of Zambian copper-cobalt metallophytes for phytoremediation of minerals wastes
Published in Saleem H. Ali, Kathryn Sturman, Nina Collins, Africa’s Mineral Fortune, 2018
Antony van der Ent, Peter Erskine, Royd Vinya, Jolanta Mesjasz-Przybyłowicz, François Malaisse
Hyperaccumulator species can be used to extract metallic elements from minerals wastes or sub-economic ore bodies.31 As such, growing hyperaccumulator plants on an agricultural scale with subsequent harvesting and biomass incineration generates a metal-rich product termed bio-ore.32 Extensive trials have been undertaken for nickel phytomining around the world, which demonstrated yields up to 200 kilograms of nickel metal per hectare per year.33 The technology for nickel is now reasonably well established and understood, but the application to other metals remains largely untested. Phytomining, in principle, could be used to produce metals such as copper, cobalt, manganese, nickel, and zinc, because hyperaccumulator plants are known for all of these elements.34 Economic feasibility ultimately depends on the element market price, the annual yield per unit area of biomass and the target element, and the availability of surface areas enriched in this element.35 The metal value of elements such as copper, manganese, and zinc are low, and hence phytomining is unlikely to be economical. However, phytomining, or rather phytoextraction, could be undertaken as part of a remediation exercise on tailings in which the value does not lie in the metal obtained, but in the soil and minerals wastes cleaned up. The metal value of cobalt is, however, sufficient to warrant further work on the viability of cobalt phytomining.
Bioenergy Plants: A Sustainable Solution for Heavy Metal Phytoremediation
Published in Jos T. Puthur, Om Parkash Dhankher, Bioenergy Crops, 2022
P.P. Sameena, Nair G. Sarath, Louis Noble, M.S. Amritha, Om P. Dhankher, Jos T. Puthur
Phytomining is an eco-friendly method for the recovery of the soluble metals uptaken by the plant biomass. This process can generate revenue, depending upon the metal present in the ‘bio-ore’ (Patra and Mohanty 2013). The recovery methods are complicated and include hydrometallurgical processes, ion exchange, flotation, magnetic field, electrolysis, bio-electrochemical procedures, etc. (Elekes 2014). Phytomining can even be a substitute for environmentally destructive mining practices if undertaken at a large scale by growing high biomass yielding plants requiring less favorable environmental conditions such as reduced nutrient content, less water utilization, etc.
Heavy Metal Phytoremediation by Bioenergy Plants and Associated Tolerance Mechanisms
Published in Soil and Sediment Contamination: An International Journal, 2021
The heavy metals accumulated in the shoot biomass were below the standard toxicity levels in the case of majority of the bioenergy plants (Bauddh, Singh, and Singh 2015a; Palanivel, Pracejus, and Victor 2020). Therefore, the shoot biomass of bioenergy plants utilized for phytoremediation can be safely used for extracting bioenergy. In contrast to these observations, some bioenergy plants accumulate exceedingly higher amount of the toxic metal ions in the shoot biomass than the root biomass (Chang et al. 2014; Cutright, Gunda, and Kurt 2010), which are potentially hazardous and therefore disposal of them turns out to be crucial with respect to phytoremediation (Mohanty 2016). Therefore, to achieve a successful phytoremediation process, the bio-accumulated metals should be recovered without interfering in the bioenergy production (Kidd et al. 2018). For that, bioenergy is generally produced from the plant biomass by direct combustion processes or by thermo-chemical processes like pyrolysis, gasification, and catalytic liquefaction, or biological processes like fermentation/anaerobic digestion by using suitable microbial system (Singh, Kumar, and Rai 2014; Srivastava 2019). The remaining portion after bioenergy production is subjected to extraction procedures for separating out the metals and this is being referred to as phytomining (Jiang et al. 2015).
Fertilization regimes affecting nickel phytomining efficiency on a serpentine soil in the temperate climate zone
Published in International Journal of Phytoremediation, 2021
Christina Hipfinger, Theresa Rosenkranz, Julia Thüringer, Markus Puschenreiter
Phytomining is a technology based on the use of metal hyperaccumulator plants for mining metals on metal-rich soils (Chaney et al. 2018). Hyperaccumulators can tolerate and accumulate extraordinary amounts of metal(loids) in their aboveground living tissues (van der Ent, Baker, Reeves, et al. 2013). Research activities on hyperaccumulator plants, including potential applications in soil remediation and metal mining started in the 1970s (Chaney et al. 2018) and first phytomining field trials were established in the 1990s (Robinson et al. 1997). In recent years, the term agromining was introduced for describing the whole process chain from plant production to metal recovery (van der Ent et al. 2018).
Improving the growth of Ni-hyperaccumulating plants in serpentine quarry tailings
Published in International Journal of Phytoremediation, 2018
Zahra Ghasemi, Seyed Majid Ghaderian, Carmela Monterroso, Petra S. Kidd
Hyperaccumulating plant species are able to accumulate extreme concentrations of trace metals in their shoot tissues when growing in metal-enriched habitats without showing signs of toxicity (Baker and Brooks 1989). Most known hyperaccumulators (>450 taxa) accumulate Ni and the genus with the greatest number of Ni-hyperaccumulators is Alyssum (Brassicaceae) (Pollard et al.2014). Nickel phytomining cultivates hyperaccumulating plants which are able to absorb and accumulate Ni from Ni-enriched substrates/soils in their harvestable plant parts (Nkrumah et al.2016). Phytomining represents a non-destructive, sustainable approach for the recovery of high value metals (such as Ni) from such sub-economic ores. Harvested plant biomass can be incinerated to produce Ni-enriched ash or “bio-ore” from which Ni metal, Ni ecocatalysts or pure Ni salts can be recovered (Escande et al.2015; Zhang et al.2016). Implementing phytomining systems in serpentine quarry-affected areas could not only provide potentially valuable sources of metals but at the same time contribute towards site rehabilitation and waste stabilization. Phytomining has the potential to improve soil structure, functionality and quality (Chaney et al.2014; van der Ent et al.2013). Ni-hyperaccumulators are endemic to serpentine soils and can present up to 1–3% dry weight Ni content in their shoots (Reeves 2006). This characteristic makes these plants particularly useful for application in phytomining (Chaney et al.2010). However, the severe growth limiting factors and lack of soil structure are likely to affect the growth and development of even this type of plants. Thus, optimizing their growth and development is an essential component of the phytomining system (Alvarez-Lopez et al.2016; Nkrumah et al.2016).