One of Lusorecursos concepts and policies is the Circular Economy, in which it has partners who carry out sustainable, modern and innovative development measures in processes and products, to make the company more efficient and competitive in the sector in which it operates. The Circular Economy in the case of “Romano” Mine is an approach ranging from the extraction of raw materials and the production of lithium hydroxide, to reuse, recovery and recycling of resources, also focusing on encouraging the reduction of consumption.
This paradigm shift will contribute to a more balanced and creative dynamic between society, consumers and natural resources, decoupling economic growth from the consumption of non-renewable resources. The transition to the Circular Economy implies a complete remodelling of the value chain, from design to the end of the life cycle of a product.
About the water cycle, a conceptual hydrological and hydrogeological study was carried out in the “Romano” Mine, in Montalegre. This study was carried out with a 21-year hydrological series of reliable data. The existing aquifer system is essentially free, at the level of the first 100 m of depth, being predictably of the same type or possibly of a mixed free/semi-captive type for higher depths.
The supply and use of the water cycle for all concession activities will fundamentally be the recycling of all the water in the industrial complex, whether domestic sewage or process water, as well as water from used in mining activity.
Thus, the installation of water reservoirs for different purposes is foreseen, so that they can receive water from multiple sources, opening the possibilities of water connection for the entire project horizon. The water from the various processes will be properly treated in the respective WWTP’s and subsequently forwarded in a way to recirculate to the various processes.
Regarding the supply and use of water for all concession activities, Lusorecursos' strategy is as follows:
• Use of all primary water resources within the complex, whether groundwater, surface water or rainwater;
• Recycling of all water that can be recycled, be it all water resulting from the complex's domestic sewage, or water resulting from industrial and mining processes;
• Minimization the use of water outside the complex;
• Minimization the use of drinking water by the complex;
• Minimization of wastewater production for final destination;
• Minimization of the amount of wastewater rejected out of the Mine and the industrial facilities;
• Minimization of costs associated with the complex's water supply and treatment systems;
• Diversification of the sources of water from the Mine and industrial facilities, in order to reduce the risk of lack of water for work.
Water like that found in nature, without any treatment or removal of bacteria, parasites, minerals, chemicals or ions. L1 - Raw water lagoon - The water will come from the pumping of the raft in the Alto Rabagão reservoir, from the rainwater used, from the water treated by the Domestic Wastewater Treatment Station and from the mining reservoir R1, essentially at the time of abundance of rainwater collected in the mine and in the retention basin. This lagoon will supply the industrial process water needs of the Concentrator, the Refinery and the Mine itself.
Reservoir R2 - To meet the needs of drinking water, the installation of a reservoir with two cells is foreseen. This reservoir will be filled from the water supply branch of the company Águas do Norte, S.A. The reservoir should meet the needs of drinking water in social facilities, namely cafeterias, bars, offices, toilets, medical center and infirmary.
Water used in the beneficiation and mineral transformation process. Pond for storage of process water from the concentrator (mixture of raw water + recycled water). The water will come from recycling the Concentrator process, although it may also come from: (1) the ETAI; (2) in the raw water lagoon L1; (3) from the R2 potable water reservoir, in the extreme case of need to reinforce industrial water from potable water.
Water used in hydrometallurgical processes - L3 - may be supplied by the Industrial Wastewater Treatment Station (ETAI), although it may also come from the raw water lagoon L1 or from the potable water reservoir R2, in the extreme case of need to reinforce industrial waters from potable waters.
Water to be used in any fires or other accidents that may occur. RIN- reservoir with 2 cells, can be supplied by water from the Industrial Wastewater Treatment Station (ETAI), from the raw water lagoon L1 or from the drinking water reservoir R2, according to water availability and respective precedences.
Water to be used in mining extraction processes – Reservoir R1 - water needs in the extraction area, the installation of a reservoir with four cells is foreseen. This reservoir must be connected to the Industrial Wastewater Treatment Station (ETAI), Mining Water Treatment Station (ETAM), retention basin and directly to the Mine, in order to be able to receive from multiple sources, opening the possibilities of water connection for the entire project horizon.
Water treatment facilities support a key role in the reuse of water in processes. Their location in the Complex of “Romano” Mine is due to the availability and needs of proximity to the processes and to the capacities of the pumping systems, with an analysis having been carried out for the final choices. Thus, the appropriate WWTP’s duly allocated to the filtering and reuse of water processes are set out below:
• Industrial Water Production System;
• Domestic Wastewater Treatment Plant;
• ndustrial Wastewater Treatment Plant;
• Concentrator Industrial Water Treatment Plant;
• Mining Water Treatment Plant;
• Drained Water Treatment Systems from impermeable zones.
The water used in the industrial process (concentrator) will also be treated at the Concentrator Industrial Water Treatment Station , with the following treatment valences:
• Coagulation / flocculation;
• Filtration in quicksand filters;
• Correction of PH.
This plant must carry out a treatment of the water that will be sent to the Industrial wastewater treatment plant and must be reused again in the same processes, in a circular return.
A Mining Water Treatment plant is also planned, which aims to treat water from the internal production of the underground mine. This plant, after water treatment, for the purpose of reuse, must send the treated water to the planned reservoir. The planned treatment will be a preliminary treatment, where the water will pass through a hydrocarbon separator, where the water will be decanted in a decantation basin.
The waste rock is designated as part of the mineral deposit that does not have ore content, in this case in particular, the host rock of the ore. On the other hand, resulting from the processes of concentration and industrial transformation are the so-called tailing. Thus, it is possible to divide the “Romano” Mine residues to waste rock and tailings.
The mining industry produces waste rock and tailings, however, in an environmentally sustainable format, these will be managed and stored provisionally, where according to best environmental practices and according to the development of underground work, these residues can be incorporated as full filling after completion of the extraction work.
The management of these residues, both during and after extraction, is fully the responsibility of Lusorecursos, which is committed to implementing the best innovative methodologies nowadays, so that waste management is effective throughout the life of “Romano” Mine, since the initial phase until the closure and post-closure of its activity in the region.
Materials resulting from mineral concentration processes result in tailings/sludges. These sludges will go through thickening and filtering processes for subsequent dry deposition. These sludges will be thickened and filtered, removing as much of the existing water as possible, which will be successively treated to enter the process cyclically. Although the option to filter tailings is more expensive, both in capital and operating costs, the environmental, landscape and social benefits largely offset the investment in this regard. In this approach, Lusorecursos joins the international partners of Outotec-Metso recognized worldwide for mineral processing and waste treatment.
This filtration methodology to be applied is performed in 3 steps: Hydrocyclones, Inclined Plate Thickeners and Filters.
The water removed during filtration is treated in WWTP’s and used again in upstream processes, thereby reusing up to 90%. Those dry tailings deposited will have a moisture content between 10 and 20% and should be used in the backfill constitution.
The filling of galleries or commonly called backfill is the result of the recovery of “Romano” Mine in the underground component, where after completion of the underground extraction works. The filling will be generated using a mixture of waste rock and dry tailings from the processes forming a mass, to increase the support of the massif. With this premise of filling galleries, the tailings will fulfil the function of filling supplementary underground cavities of rock extraction, thus contributing to a sustainable recovery of the mining site, with the reuse of materials from the mining activity.
