if we assume a seasoned addict without any nostrils left, at 100mg a snort with a 20 minute cooldown before the next hit:

• 2.4 tonnes * 1x10⁹ mg/tonne = 2.4x10⁹ mg of coke
• 2.4x10⁹ mg ÷ 100 mg/snort = 2.4x10⁷ snorts.
• 2.4x10⁷ snorts ÷ (60/20) snorts/hour = 8000000 hours
  • ~ 912 years for a seasoned addict
  • ~ 3.6 years for 500 seasoned addicts who catch 12 hours of sleep too

I've probably made a mistake somewhere