Abstract
Supply of resources, a growing population, and environmental pollution are some of the main challenges facing the contemporary world. The rapid development of mining activities has produced huge amounts of waste. This waste, found in abandoned mine sites, provides the potential opportunity of extracting raw material. The current study, therefore, focuses on testing the validation of a shared methodology to recover extractive waste from abandoned mines, and applies this methodology to a case study in Gorno, northwest Italy. The methods focused on: (1) analyzing the impact of tailings and fine fraction of waste rock (<2 mm) on plants (Cress - Lepidium Sativum) to assess usability of both as soil additive, and (2) recovering raw materials from tailings and coarse fraction (>2 mm) of waste rock, by means of dressing methods like wet shaking table and froth flotation. The results indicated that the fine fraction of waste rock and tailings did not have detrimental effects on seed germination; however, there was marked decrease in plant growth. As for the recovery of raw materials, the coarse waste rock samples, crushed to <0.5 mm, produced a recovery of Cd, Ga, and Zn—as much as 66%, 56%, and 64%, respectively—using the wet shaking table. The same samples when crushed to 0.063–0.16 mm and used for froth flotation produced a recovery of Cd, Ga, and Zn of up to 61%, 72%, and 47%, respectively. The flotation experiment on tailings showed a recovery of Cd, Ga and Zn at pH 7 of 33%, 6% and 29% respectively. The present investigation highlights the methodologies used for extracting raw materials from extractive waste.
Highlights
Raw materials are crucial for modern society
Economic development depends on the supply of RM [3,4,5]—in the European Union (EU) alone, 30 million jobs depend on access to raw materials [6]
The use of extractive waste can result in recovery of RM and critical raw materials (CRM), along with reclamation of polluted areas and development of an economic system that aims at minimizing waste and exploiting resources [10,11]
Summary
Raw materials are crucial for modern society. The evident growth and prosperity is based on mineral reserves and fossil fuels. The United Nations’ Sustainable Development Goals, as well as implementation of the Paris Agreement, resulted in vast utilization of a wide range of minerals for green technologies, such as low-carbon applications [1]. This focus on growth, development, and increase in population has led to the scarcity of raw materials (RM) [2]. Considering the shortage of RM, research efforts should be directed towards the use of previously discarded EW [12] This idea of reusing EW as integrative feeding materials for industrial processes is closely linked to the circular economy’s perspectives, by integrating EW back into material cycles [13,14,15,16,17,18,19]. Care should be taken to perform life cycle assessment and cost-benefit analysis for handling waste on site [13]
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