Indeed, but let me expand on your numbers above. Looking at...

Indeed, but let me expand on your numbers above. Looking at their yearly production estimate and recent base metal prices (USD) 12/04/2018.
Zn 70,000 dMt @ $3,238 = $226,6606,000
Cu 30,000 dMt @ $6,887 = $206,610,000
Pb 25,000 dMt @ $2,500 = $60,000,000

These guys are looking at an NPAT of $493,270,000 once in production!
This doesn't even include the precious metals by-product which the company does not forecast.

Cons:
- Heron/Woodlawn is a junior miner with a large possibility of production delays.
- Zinc has a low price trend risk during tepid economic growth
- Historically Zinc can be priced well below the cost of production for years at a time
- Supply side story and not demand

Pros:
Heron is...
- Funded up to production Q1 2019
- High quality sulphide deposit resource base
- Existing transport infrastructure and power, strong community support
- Brand new state of the art processing plant and equipment
- 9 Year mine life (9.24 million tons reserve starter case)
- Plant has capacity to produce an average 1.25 million tonnes of tailings and underground ore per year that means 150,000 tonnes of lead copper and zinc equivalent annually
- Most of Chinas Zinc production has shut down
- Tight zinc market
- Zinc battery technology will boost demand
- Dwindling world supply (Conjecture - LME Zinc/Copper showing up on its door recently due to higher prices)

But I'm not complaining as I'm planning to buy some more....