R-strategies in circular economy : Textile, battery, and agri-food value chains

This report discusses the circular economy model through circular economy strategies, the R-strategies, in three different value chains: textile, battery, and agri-food. The R-strategies can be classified under three approaches: 1) smarter product use and manufacture (R0 Refuse, R1 Rethink, R2 Reduce), 2) life extension strategies (R3 Reuse, R4 Repair, R5 Refurbish, R6 Remanufacture, R7 Re-purpose), and 3) creative material application (R8 Recycle, R9 Recover). Often, the impact on circularity and overall sustainability is likely higher in the beginning of the material value chain. However, the selection of the most optimal R-strategy is always case specific and should be based on a holistic, system wide approach. The report gives several examples of business models applying different R-strategies in the selected value chains. The examples show the similarities and differences between the value chains and which strategies have more importance in which value chains. In the textile value chain, currently the most important aim is to replace fast fashion with longer product use (R3, R4, R5) and essentially reduce production and consumption volumes (R0, R1, R2). Textile fibres can be circulated (R6, R7, R8) to some extent, but in every round, there is some wearing of the material and the quality of the recycled fibre deteriorates in comparison to virgin fibre. In the battery value-chain, increased recycling of metals (R8) is crucial to meet the future need of batteries in various solutions including electric vehicles and energy storage. Thus, recycling technologies need to be further developed to meet the recycling targets. There is also active research and development activities in the field of substitution (R0) with new battery chemistries and even replacing graphite with renewable lignin-based material. In the agri-food value chain, avoiding food loss and food waste (R0) is clearly a low hanging fruit since even one third of all food is estimated of being wasted. When it comes to circularity in the agri-food value chain, it is best supported by increasing local food production, where transport distances are short and do not create a barrier for efficient utilization of side-streams (R8, R9). The circulation of nutrients in manure is also essential

Geological and mineralogical aspects on mineral carbonation

The mineralogical features that characterise each individual mineral and rock also influence every process they are part of. This is also the case with “the ÅA route” mineral carbonation method that has been under development at Åbo Akademi University for the past decade. The studies forming this thesis have been concentrating on specifying the geological and mineralogical raw material characteristics that need to be taken into consideration while this particular carbonation method is utilised. The studies this thesis is based on include altogether 24 different samples of rocks and minerals. The first rock samples were collected at mines in Finland and also included mine tailings. Mine waste material was introduced to the study in order to state whether the produced rock material would make a suitable raw material and in order to map the economic benefit from using a readily quarried and ground material. Based on the results from the mine waste rocks, the studies were continued with serpentinite rocks and serpentine mineral samples. Samples were collected from mines and natural areas. A closer look at serpentinites and serpentines were necessary in order to resolve why the results varied drastically and which mineralogical characteristics were affecting the varying results. Results gained from the first and second studies indicated that the mineral structure was an issue, therefore the third study included mineral samples covering each Mg-bearing mineral from each silicate group. The main method used in all the studies was the “the ÅA route” developed for carbon capture and mineralisation (CCM). The method is based on extraction and precipitation of magnesium and its fusion with carbon dioxide (CO2) through an exothermic reaction. The Mg is extracted as ions and precipitated as magnesium hydroxide (Mg(OH)2). The fusion with CO2 results in a carbonate rock, magnesium carbonate (MgCO3), also forming naturally all over the Earth as a result of natural carbonation processes. Before the experiments with “the ÅA route”, the mineralogical features in each sample were studied with an optical microscope, Scanning Electron Microscope with Energy Dispersive X-Ray Spectrometer (SEM -EDX), X-ray fluorescence (XRF) and X-ray Diffraction (XRD). All the results gained from the three separate studies support each other and give grounds to define the features essential for the successful utilization of “the ÅA route” method. Therefore this thesis supports these defining claims: a rock material suitable for mineral carbonation with “the ÅA route” should be an ultramafic phyllosilicate rock, descending from another phyllosilicate. The material should have at least 17 % Mg and it should contain over 10 % of crystalline H2O. If one feature does not meet the requirements but is close to the defined optimal value, it can be compensated by other positive features. Even though the experiments are focused on one particular carbonation method, there is no reason to state that the results could not be applied to other similar methods, as well. By utilising carbonation methods such as “the ÅA route”, a safe and long-term storage option for the anthropogenic CO2-emissions is created. Exploitation of waste materials as raw materials also solves other problems, as there is less need for waste storage and management. The produced end product also replaces the synthetically produced similar goods. In order to benefit from the excess waste minerals, rocks and gases, their characteristics need to be known. Therefore, it was essential to introduce a geological point of view to the “the ÅA route” in the form of this thesis