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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - REMINE (Reuse of mining waste into innovative geopolymeric-based structural panels, precast, ready mixes and insitu applications)

Teaser

Summary

Access to raw materials and resource efficiency are at the forefront of the EU political debate and recycling is a main part of the solution of many strategic objectives. Economic activities in Europe produced 2.5 billion tons of wastes in 2012, of which 29% comes from mining and quarrying activities. Mining and quarrying activities cause significant environmental, economic and social impacts. One of the consequences is the accumulation of mineral wastes in deposit fields. In this context, this RISE programme aims to promote international and inter-sector collaboration through research and innovation staff exchanges, share knowledge and ideas from research to market (and vice-versa) for the advancement of science and the development of innovation within the recycling and valorization of mining and quarrying wastes, promoting the utilization of innovative alkali activated materials (aka geopolymeric materials) in the construction sector, and foster a shared culture of research and innovation that welcomes and rewards creativity and entrepreneurship and helps turn creative ideas into innovative products, services or processes in the materials industry thorough recycling mining wastes, by taking advantage of the integrated knowledge acquired in the complementary areas of the RISE partners. In this scenario, this RISE action aims at taking advantage of the recent developments in the areas of materials science, processing engineering, structural engineering, infrastructure systems, arts and design and market perspectives, turning mining waste into valuable materials for infrastructure and building products.

Work performed

During the first 24 months of H2020-MSCA-RISE-2014 REMINE project, a survey of relevant sources of waste with potential for alkali-activation/geopolymeric reaction was carried out first. Blends of waste glass (WG), tungsten mine waste (TMW) and spent bentonite clay (UD) derived from the food industry, was a top priority to access potential alkali-activation and reaction extent. Macro-encapsulated aggregates (ME-LWAs) consisting of expanded clay lightweight aggregates (LWAs) impregnated with a paraffin wax phase change material (PCM) were developed for thermal energy storage. ME-LWAs were successfully incorporated into an alkali-activated/geopolymer binder, creating a novel composite material. This novel composite was evaluated for a precast panel application. Thus, different proportions of WG and TMW have been assessed to provide the most suitable workability/ strength ratio. Additionally, novel ideas for combining of ceramic materials with expanded cork (CTII materials) for architectural and historical heritage restoration have been studied. As well, studies for the development of specially shaped artificial aggregates for infrastructure applications (AAI) obtained from only 100% wastes, namely TMW and UD, have been carried out during the research period. Besides, it was also found out that since the chemical composition of tungsten mineÂ´s wastes is mainly silica and alumina and therefore it can be reused, without additional treatment, in refractory materials as silico-aluminous aggregates. Thus, aggregates samples from different stages in the tungstenâ€™s extraction in Panasqueira processes have been introduced in refractory materials with promising results. More details about activities and publications can be found on the project website: https://reminemsca.wordpress.com.

Final results

Chemically activated binder materials are certainly an emerging technology for the (re)utilization of industrial by-products such as fly ash and slag. However, researchersâ€™ have recognised the need to expand the range of precursor materials to include many of the other emerging and non-conventional waste materials, as it is being developed within REMINE project regarding tungsten and coal mining waste. Successful novel blends of precursor materials including tungsten mining waste have been found out in REMINE. It includes its combination with waste glass and metakaolin. Tungsten mining waste (TMW) has accumulated in the billions of tonnes in the mines of Western Europe, which is problematic because reuse options for this material are limited. TMW is inherently an aluminosilicate and therefore possesses the capacity to be used as a suitable raw material to produce alkali activated binders (AAB) that exhibit high strength, rapid setting, good durability and high resistance to chemical attack.Â According to the ongoing research studies, thermal energy storing macro-encapsulated aggregates were for the first time successfully incorporated into an alkali-activated binder, creating a novel composite material, opening a wide selection of applications for its inclusion e.g. surface cooling systems, construction materials such as wallboards and ceiling tiles, roads and pavements. Besides, waste-based alkali activated precasted panels (with various properties) is another promising industrial application for the future of tungsten mining waste mud recycling using this processing technology. It was also found out it is feasible to produce foamed light weight alkali-activated materials (foamed LWAAM) using Panasqueira waste mud and other precursor materials, as well incorporating expanded granulated cork. Foamed LWAAM can be used in several applications where low density and fire resistance is required. Based on the initial results obtained, the use of Panasqueira mine waste aggregates and fillers in the production of materials for the construction of transportation infrastructures is technically feasible. As well, artificial aggregates for infrastructures (AAI) through alkali-activation of tungsten mining waste mud combined with other industrial waste is a viable technical solution to compete with crushed natural stone. It can lead to the industrial manufacturing of eco-friendly aggregates to produce most of the road paving materials. Panasqueira mud and coarse waste can also be introduced in insulate castables.Â Since the behaviour of the castables is like the reference materials it can be reused, without any treatment, in refractory materials for several industrial applications. Furthermore, the combination of ceramic materials with cork will result in novel materials for novel architectural and historical heritage applications. Such products can exhibit a high heat-inhibiting capacity, high water-inhibiting capacity together with enhance texture, brightness and colour. Thus, this novel form of recycling mining/industrial waste by alkali activation will certainly cause positive economic and social impacts on the local communities as well as on the perspective of other mining activities in Europe. However, there is still a strong gap between fundamental research on alkali activated materials and their industrial applications. Conducting more applied research and pilot tests could significantly reduce the waste generation and will increase its recycling potential.