Trade payables of $30mil seems like a normal figure to me given...

Trade payables of $30mil seems like a normal figure to me given their level of expenditure and I'm sure it's within normal terms. It's a growing business so I would expect to see a figure of around $40mil at Dec19
Other payables and accrued expenses of $16mil includes some $10mil in unpaid royalties to Qld govt, 2%NSR private entity and Varde silver royalty - you can definitely expect to see this figure increase as the royalties are not being paid yet and so there would be another $6mil for them at Dec19 so the total figure might be close to $25mil at Dec19.
The $200mil mine restoration obligation will still be there at Dec19 but could be substantially reduced later this year when it's replaced with our own bond with the Qld govt.
The $60mil loan from Varde will be there at Dec19 and is now $100mil from January.

At a zinc price of $1.05/lb and an exchange rate of 69c, they will have cashflow positive earnings at the rate of $20mil/qtr as from April20 for the next five years - that's $400mil pre-tax and they do have substantial tax losses to offset some of the tax - and this is just from the tailings - it does not include future earnings from the in-situ resource.

But it is the leverage here that makes this such an interesting investment - eg another US25c/lb($A36c/lb) and we're earning 60% of that after the smelting fees of 40% - so another $A21.6c/lb on 400mil lbs/pa and you've made another $A86mil pa or another $430mil pre-tax over five years.

IMO it's a good gamble when the market cap is only $165mil but each to their own - no one's forcing anyone to invest. Their zinc price was US$1.53/lb in the March19 qtr - now that would be nice if it was to come back again.