A reference you cited but did not point out the technology breakthrough: Please note that Green Phosphate Technology Breakthrough may increase phosphate sustainability 3 fold. The Improved Hard Process does not use sulfuric acid and can use marginal and contaminated ore. Ref: View PDF. Note: more than double mine yield. Also the fertilizer product is fluid which can increase crop uptake and reduce runoff again increasing phosphate yield. This results in a 3 fold sustainability advantage.