Geological resources: exploitation and responsible use

Classify these geological resources as metallic, non-metallic (industrial) and energy resources: copper, gypsum, coal, silica sand, oil and iron, and give one application of each.

Explain why coal, oil and natural gas are called fossil fuels and what the expression "fossil sunlight" means applied to the energy they release when burned.

Define ore and gangue in a metallic deposit and explain what determines whether a deposit is profitable to mine, considering the metal price and the proportion of ore.

Explain the difference between an open-pit quarry and an underground mine, what type of resources is extracted in each, and give a Spanish example of each type of operation.

What is the grade of an ore? Explain why the average grade of mined deposits falls over time and what consequences this has for profitability and for future mining (could deposits discarded today be exploited?).

Describe two environmental impacts of open-cast mining (on the landscape, water, or atmosphere) and explain what the subsequent restoration of a site consists of, citing a specific land recovery measure.

Almadén (Ciudad Real) hosted the largest mercury mine in the world. Explain its historical importance (the silver of America and amalgamation), why it closed and what persistent environmental problems it left (mercury in soils and fish), as well as its present value as heritage.

Describe the phases of the life cycle of a mining operation (prospecting, extraction, ore concentration, closure and restoration) and discuss why the closure plan must be approved and funded before digging begins.

Lithium, cobalt, and rare earths are considered strategic resources. Explain for which technologies they are essential, what external dependency problem they pose for Europe, and what alternatives are being explored.

Sand is, after water, the most extracted resource on the planet. Explain what it is used for (concrete, glass), what impacts its extraction has on rivers and beaches (deepening of riverbeds, coastal retreat) and why not all sand is suitable (what problem does desert sand have?).

The International Energy Agency estimates that manufacturing an electric vehicle requires an average of about 205 kg of critical minerals (copper, lithium, nickel, manganese, cobalt, and rare earths), compared to the 35 kg needed for a conventional internal combustion vehicle.

1. a) Analyse the environmental paradox: if the rollout of electric vehicles aims to decarbonise transport to curb climate change, predict which local geomorphological, hydrological, and geochemical pressures will shift to mining areas if the global vehicle fleet (1.400 million cars) is replaced at a 1:1 ratio.
2. b) A corporate report forecasts that by the year 2032, 100% of the critical metals in its batteries will come from recycling its own vehicles. Using the concept of residence time and the growth rate of the vehicle fleet, demonstrate why this goal is mathematically impossible in the medium term.
3. c) Justify how substituting battery technologies (for example, sodium-ion cells instead of lithium-ion, or lithium iron phosphate cathodes free of cobalt and nickel) reduces the geological risk of supply shortages, taking into account the crustal abundance of each element.

Reason why geological resources are considered non-renewable on a human scale and what two strategies make it possible to extend their availability — recycling and substitution with other materials —, providing an example of each.

Compare obtaining one tonne of copper from a mine with recovering it from electronic scrap: energy consumption, $\text{CO}_2$ emissions, waste generated and employment created. Conclude what role recycling can play in the future supply of the metal.

An open-pit gold mine exploits an ore with an average grade of 1,5 g of Au per ton of displaced rock, with a carbon footprint of 14.000 kg of CO₂ eq per kilogram of refined metal obtained. In contrast, printed circuit boards from discarded mobile phones have average concentrations of 300 g of Au and 120 kg of Cu per ton of waste.

1. a) Calculate how many tons of mineralized rock must be extracted and crushed in the primary mine to obtain the same amount of gold contained in 2 t of mobile phone circuit boards. Interpret the comparative geomorphological impact of both sources.
2. b) If the metal concentration is so much higher in electronic waste, justify why primary mining still provides more than 80 % of the world's gold: analyze two thermodynamic or technological limitations linked to material dispersion (complex alloys, solders, miniaturization) and one logistical collection barrier.
3. c) Predict what environmental impact on soils and groundwater would be caused by recovering these metals through artisanal or informal acid leaching, comparing it to closed-loop industrial hydrometallurgy.