11:375:101 Lecture Notes - Lecture 15: Rare Earth Element, Tree Farm, Tantalum
4 Nov 2018
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Document Summary
There are 17 rare earth elements discovered in 1787. Tantalum is a mineral found in coltan which end up going to china. Tailings - ore left over after metals are extracted. They pollute soil and water and can contain heavy metals or acids. Open pit mining - used for evenly distributed minerals. Pits can fill with toxic water once abandoned. Provide raw materials and health benefits and economic benefits. Timber is economically valued, but forests are ecologically valuable. Uncut and no disturbed for 200 years or more. Tree plantation (tree farm or commercial forests) Used for supplying industrial wood in the future. All trees in an area are removed. Has the greatest impact on forest ecosystems. Intermediate or mature trees are cut individually or in groups. Products that are produced sustainably can be certified. International organization for standardization (iso) and forest stewardship council (fsc) both have different standards. Excess vegetation produces kindling for future fires and ecosystems depend on fires!
