Challenges in the Management of Mining Waste †

The article aims to summarize the current challenges for tailing piles and ponds geologicalmining projects focusing on the waste deposited in southwestern Poland.


Introduction
The discussion on mineralization potential and relevant policy concerning anthropogenic deposits in Poland is coming back every few years. In recent years, those types of sites are becoming gaining more worldwide attention in scientific and practical terms, mostly because of geological inflation and the rising demand for raw materials but also due to the increasing environmental awareness [1]. The most crucial questions in this matter are how high the potential of the raw material is in tailing piles and how significant its impact on the environment is. It seems that scientists and researchers working on this issue should provide a specific answer.
The article aims to summarize the current challenges regarding the possible utilization of the materials deposited on tailing piles and tailing ponds in south-western Poland. Authors highlight the important aspects regarding environmental impact and technical solutions for the whole life-cycle, the economy of the investment, and the social license to operate. Moreover, the authors aim to bring circular economy thinking before the potential project planning.

Current Knowledge about Waste Management in Poland
In European regulations, the awareness of the need to neutralize the negative impact of waste on the environment has been noticeable for many years [1]. Recent years have also brought increased awareness of the possible use of waste to meet the raw material demands. In Poland, there are also noticeable trends of greater emphasis on documenting the generated and deposited waste. An example of an activity is the database on products, packaging, and waste management launched in 2018 [2]. Additionally, tasks related to the full use of waste are mobilized, which was highlighted in the polish circular economy roadmap and in the policy of European Union [3,4].
In the context of the generated waste, the mining industry and the processing of raw materials are undeniable leaders. As mentioned above, the current monitoring allows for the documentation of the amount and location of this waste. In recent years, the Polish Geological Institute-National Research Institute has undertaken the difficult task of making a digital inventory of former mining waste storage facilities in the Sudetes [5]. The result of the institute's work is a base of 568 tailing piles and ponds. Considering that it is the beginning of the work, this shows the scale of the amount of mining and processing waste deposited in Poland [5,6].
These objects, due to the specificity of the materials deposited in them, pose a potential environmental threat. At the same time, further research will allow to assess their potential in the context of obtaining valuable raw materials, such as copper, silver, cobalt, lead, and zinc. A holistic approach to the possibility of using these facilities seems inevitable in the face of the growing trend of implementing the circular economy [3].

Challenges for Potential Investments
The authors qualitatively defined the challenges in five mine areas (economical, environmental, social and governance, legal, technical) of tailing piles that appear at each stage of the geological and mining project life (current state, exploration, development, exploitation, processing, closure, reclamation) ( Table 1). The census was based on the experiences gathered by the Polish Geological Institute in the geodatabase Hałdy, the authors' experiences, and a review of the scientific literature. The issue of the operation of tailing piles and ponds combines aspects of environmental protection, waste management, mining, and processing. Many of the challenges facing a possible investment relate to best practices in these areas. There are, however, additional issues that need to be addressed for the deposited mining and processing waste. These are, amongst others, an inventory of existing sites, technical aspects of the exploration of heterogeneous geological media, assessment of the economic sense of this type of geological and mining investments, and the need to use the principles of circular economy management.
In the next stage, the significance of the given aspects was assessed in individual phases of the project. The environmental impact during the most impactful mining phases and the economic potential of obtaining raw materials at the exploration phase were identified as key challenges. Proving the possibility of obtaining profit and the simultaneous restoration of the environment gives a probability of making the investment sensible.

Case Study-Waste Deposited in the Area of Old Copper Basin (Poland)
An example of a potential investment opportunity is the tailing piles and tailing ponds deposited in the Old Copper basin (Lower Silesia, Poland) ( Figure 1) [5][6][7]. The potential of the deposited waste was estimated to even 0.3% of Cu and 13.7 g/t Ag. The occurrence of metals such as Au, Pt, and Pd was also documented [8]. The current environmental impact was estimated as a potential threat for humans, fauna, and flora [5]. The possible exploitation was part of the interest a few times in history, but it did not finish as an active project, which was mainly related to the lack of economically justified processing method (extraction of metals and the utilization of residue) [7][8][9].

Case Study-Waste Deposited in the Area of Old Copper Basin (Poland)
An example of a potential investment opportunity is the tailing piles and tailing ponds deposited in the Old Copper basin (Lower Silesia, Poland) ( Figure 1) [5][6][7]. The potential of the deposited waste was estimated to even 0.3% of Cu and 13.7 g/t Ag. The occurrence of metals such as Au, Pt, and Pd was also documented [8]. The current environmental impact was estimated as a potential threat for humans, fauna, and flora [5]. The possible exploitation was part of the interest a few times in history, but it did not finish as an active project, which was mainly related to the lack of economically justified processing method (extraction of metals and the utilization of residue) [7][8][9].

Conclusions
As the awareness of the potential of the raw material of tailing piles and ponds is growing, there is a need for determining the possible obstacles for geological-mining projects. The work conducted by the Polish Geological Institute showed the scale of deposited waste in south-western Poland. That results and the example of waste deposited in Old Copper Basin shows the opportunity for scientific and business activities; however, beforehand, the challenges have to be distinguished and considered by decision-makers. In this study, authors analyzed the current potential barriers and determined the most significant ones: the assurance of the environmental protection through the project life cycle, and the development of the circular economy implementation with the simultaneous economic justification.
Author Contributions: W.K. and H.W. created the concept; W.K., H.W., J.K. and C.S. compiled an overview; W.K. and J.K., analyzed the case study; W.K. wrote the paper; H.W., J.K. and C.S. supervised. All authors have read and agreed to the published version of the manuscript.

Conclusions
As the awareness of the potential of the raw material of tailing piles and ponds is growing, there is a need for determining the possible obstacles for geological-mining projects. The work conducted by the Polish Geological Institute showed the scale of deposited waste in south-western Poland. That results and the example of waste deposited in Old Copper Basin shows the opportunity for scientific and business activities; however, beforehand, the challenges have to be distinguished and considered by decision-makers. In this study, authors analyzed the current potential barriers and determined the most significant ones: the assurance of the environmental protection through the project life cycle, and the development of the circular economy implementation with the simultaneous economic justification.
Author Contributions: W.K. and H.W. created the concept; W.K., H.W., J.K. and C.S. compiled an overview; W.K. and J.K., analyzed the case study; W.K. wrote the paper; H.W., J.K. and C.S. supervised. All authors have read and agreed to the published version of the manuscript.

Acknowledgments:
Research funded by Department of Mining, Faculty of Geoengineering, Mining and Geology, Wrocław University of Science and Technology. Thanks to NT4C Tomasz Nowobiliski for taking the UAV photos.

Conflicts of Interest:
The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.