It could be compounding with interest capitalised during construction as money is drawn down (not all at once).
The construction time is much less than 5 years even including ramp up to full production and forecast CAPEX including contingencies is much less than $10b which you have used.
Such deals can include rights to equity in lieu of interest etc. We don't know the banks mandates or RRR.
Unfortunately the directors focus was only on the Chinese who want nothing less than 100% ownership.
SDL Price at posting:
40.5¢ Sentiment: Hold Disclosure: Held