Analyzing mining company's balance sheet to convert to market value in liquidation scenario - VALUE INVESTING

I have a question for anyone with experience in analyzing mining companies (especially if you have analyzed copper miners).

I am looking at a miner's balance sheet and trying to run a liquidation scenario i.e. how much major balance sheet items would be worth on the market less all financial debt. The result is a rough estimate of equity value which I want to compare against the current market place.

This stock, along with most miners, took some serious beating over the last 3-4 months.

My question is rather industry specific. This company has a copper mine under development, a very large project. If this company goes under (its leverage is eye watering), and it was to auction of its assets, what haircut to the book value is it better to assume when trying to make a quick estimate of how much this copper mine is going to sell for? This asset is sitting in a developing nation (think Africa or Central Asia) and very dependent on close ties to the ruling dictator.

This is a ballpark estimate but I am taking a haircut of 50% to BV of that asset. Is it too much, too little? How would you go about valuing a copper mine in that scenario?

Any thoughtful inputs would be greatly appreciated.

Regards,