Mineral Dependencies Flashcards
What is the difference between a traditional linear vs circular economy?
- Linear: A traditional economic model where raw materials are extracted, used to manufacture products, and then discarded as waste after use: “take, make & dispose”
- Circular: A sustainable economic model designed to minimise waste and keep materials in use for as long as possible by focusing on recycling, repurposing, and designing for longevity: “reduce, reuse & recycle”
What is the issue with our current linear economy of mobile phones
- Mobile phones are a complex mixture of elements, each with high value
- Quite often mixed together with other thing, which makes it difficult to reseperate them out into primary materials (cost + chemical research)
- Hence there is a need to recycle these metals of these spent electronic devices
Precious metals exist in the earths crust in which form
- Oxides
- Therefore there is the need to separate these mixtures and refine them to make pure elements
- These can then be made into complex materials depending on its application
What are the 6 key step behind sourcing gold + other precious metals
- Ore characterisation helps us to understand what we have got in terms of metals
*Ore preparation involves crushing it down to increase the surface area - Cyanide is used to extract the gold- using ligand formation
- Then those ligands are removed once impurites have gone
Are mines specific for one type of metal
No - they usually mine multiple
Therefore there is a need to evaluate ore composition
What types of techniques might we consider to evaluate ore composition?
And magnetic moment
What is communution?
It is physically crushing the ore using a rotating iron barrel
(3% of the earth CO₂ is used to produce the energy for these kilns)
After comminution what happens?
- Gold is separated from complex mistures via coordination chemistry
- They are oxidised using H₂O₂ and then for a linear complex using cyanide - Au(CN)₂
- The target complex is extracted into a suitable solvent and adsorbed onto solid like activated carbon (large SA) and let to dry
- The residual liquids are sent to the “tailings dams” where further re-extraction can occur
- Gold is recovered via reduction (chemical or electrochemical winning)
What are the issues with using Cyanide?
- Cyanide inhibits the cyctochrome oxidase enzyme, preventing the body’s cells from using oxygen
What is the was associated with 1kg of gold?
- 2m tonnes in waste
- 691000 litres of water
- 141 kg cyanide
What are some core impacts of the process of producing gold?
- Chemical loading
- Toxicity
- Energy
- Impacts to STG of having it tho?
What are some issues associated with smaller scale artisanal mining?
- Modern-day slavery
- Equality
- Soil erosion + water course damage + significant environmental degradation - high pressure water
- Biodiversity
Smaller scale artisanal mining uses what to extract the gold?
Heating with Mercury
Allowing gold to be recovered from road dust (catalystic coverters)
What is the issue with mergury and bioaccumulation?
- Murcury can exist in mutltiple forms and redox states
- It can be oxidised into the air, in a 2+ state, rained down into water bodies etc
- Here is can be taken up by plants, and enter the food chain, and eaten by humans (think Minemata)
What does this graph show?
- That developing countries have high levels of mercury emissions associated with energy production from coal
