I learnt about phosphogypsum in some 2011. After that I thought and read about it occasionally. How it can be reused? In January 2024 I realized that thinking without doing makes no progress and decided to do something.
What changed since 2011?
REE prices decreased some 10 times.
Solar energy increased its share in the energy pie. Solar electricity is intermittent energy source. Dealing with intermittency is a challenge, and reusing phosphogypsum could be a good opportunity to use solar energy.
How pure gypsum can be extracted from phosphogypsum?
Gypsum has solubility of 2 grams per liter of water – not too much. Dissolving gypsum and evaporating water will need 2,26 MJ of energy per 2 grams of gypsum, or 314 MWh per ton. This amount can be reduced some 50 times by distilation using mechanical vapor recompression, it means 6,28 MWh of energy per ton of gypsum. 1 MWh costs some $100, so this way is not economically viable.
What if change the temperature of the solution? Heating a liter of water by 100 degrees needs 420 kJ of energy. It means 58,3 MWh per ton of gypsum. And counter-flow heat exchangers can reduce this amount by some 50 times, so it could be 1,2 MWh per ton. It is better but still high.
And another problem with low solubility is huge amounts of the solution to pump, filter, store, etc. I needed to find another way to dissolve and precipitate gypsum.
Комментариев нет:
Отправить комментарий