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Critical Raw Materials (CRMs) are those raw materials which are economically and strategically important for the European economy but have a high-risk associated with their supply. This document describes a card game and provides all the material to play. The goal of the activity is to learn the importance of critical raw materials, their properties and their applications. Teachers can use a detailed description of each of the elements (with information about their mineral source, production, economic importance, properties and main uses) and Kahoot! questions to test the knowledge of their students. Students work in groups, matching cards (property and use) to guess which elements made a jet engine, a solar panel, a phone screen and many more items necessary in our everyday life.

Fossil fuel is defined as “a natural fuel such as coal or gas formed in the geological past from the remains of living organisms” [1]. In this chapter we are going to focus on its solid form, coal, “a black or dark brown rock consisting chiefly of carbonized plant matter, found mainly in underground seams and used as fuel” [2].

Regardless the goal and final use of solid fuels, all these substances need to be handled, processed and stored. These steps involve several risks that need to be identified, characterised and treated in order to avoid, or at least reduce, the consequences of a possible accident.

The chemical composition of the materials has a high effect in their flammability and ignition risks. In the case of coals, it is well known that an increase on the volatiles content, meaning a decrease in the ash content, causes a rise in the flammability probability of the samples.

Self-ignition of solid fuels storage is one of the main causes of human and economic losses. Additionally, each fire caused by this phenomenon emits an amount of toxic gases that contributes on the development of climate change. Nowadays, several methodologies are used in order to detect the self-ignition tendency of solid fuels, but they have as main disadvantages the amount of money and time that they require. The aim of this study is to propose a methodology of detection of incipient self-ignition of solid fuels through the measurement of gas emissions. This study compares existing methodologies to detect self-ignition tendency, such as TG, DSC or susceptibility, and to combustion related gas emission results. Different methods have been used to evaluate the results from the gas emission test, showing that interval and inflexion methods provide early detection of the self-heating process. With this methodology, it is possible to determine this process in advance with the equipment currently available in every industrial facility, reducing costs and improving efficiency.

By adding H2 to CH4 the combustion characteristics improve considerably. The flammability characteristics of the CH4 are most well-known, but the CH4 enriched with H2 has a completely different behaviour regarding the flammability and the explosiveness. The understanding of the flammability of such mixture in the air is crucial to allow their safe use in industry. Lower and upper flammability limits are one of the most important parameters at the time of characterizing and handle flammable gases. This study is focused on the evaluation of the safety prevention measures more commonly apply to explosive atmospheres, specifically the inertization, by means of a nonflammable gas (CO2). This is defined through the limiting oxygen concentration (LOC), being the threshold value of inert gas concentration so that the propagation does not occur. The representation of the Flammability limits and the LOC in ternary diagrams allow separating the flammable mixtures and the non-flammable mixtures in two differentiate regions by means of a curve, named flammability interval. This interval is composed by the set of flammable mixtures of a ternary mixture. In previous studies, the flammability interval of the H2-CO2-air has been obtained, so this study intends to obtain the flammability interval of the CH4-CO2-air mixture in order to achieve the first step to define the flammability interval of the mixture CH4-CO2-H2-air.

The use of hydrogen as an energy vector seems today one of the most viable alternatives, although its use involves safety problems due to the generation of explosive atmospheres. Lower and upper flammability limits are one of the most important parameters at the time of characterize and handle flammable gases. This paper is focused on the evaluation of the safety prevention measures more commonly applied to explosive atmospheres, specifically the inertization, by means of a non-flammable gas (CO2) in air-hydrogen mixtures. In this study both theoretical and experimental methods to determine the flammability interval have been carried out. The flammability limits and the LOC value are represented in a ternary diagram enable to determine the explosive area containing the entire range of explosive mixtures. The experimental study has been conducted in a flameproof chamber of 0.5 dm3 volume, designed to withstand explosions inside. The results show that the theoretical approaches are only valid as a previous step to the experimental tests, since the observed differences between both implies that the use of such approaches could lead to important safety risks.