I had noticed that the share price had doubled in the last 12...

I had noticed that the share price had doubled in the last 12 months. I was wondering if the fact that they made $342.9m in net profit over the 12 months has anything to do with it.
In any event we are looking at the situation today and not 12 months ago.
The fact is that the best use of capital today is a buyback and the directors have a duty to manage the company for the benefit of all shareholders, not just the major shareholder. If the directors do not act in the best interests of shareholders they will have to explain why they did not. It is not good enough to say we are not doing it. If enough shareholders complain they will have to consider it. Of course if shareholders want to sit on their hands so be it.

The second best option for directors is to spend the money on expansion/new projects.
Subject to the feasibility study the expansion/upgrading at S R would seem reasonable.

However, a new mine in W A is a bridge too far. What political risk do you put into the model to account for the fact that China dominates the world steel and iron ore market and is currently run by a very unstable person, to put it mildly. Australia is in the gun and the only reason iron ore has been spared is they have little choice at this stage. A lot can change in 3 years. More scrap will become available in China, new iron ore production, an end to new towns that no-one lives in etc. etc. I could go on but you get the picture.

Premier Zi has everyone in the gun not least of which are the well off in China. Shagang is a private company and would have no special influence with Zi. Probably the opposite in fact. Zi's latest crusade is "common prosperity" which involves "encouraging" the billionaires to redistribute their wealth. What happens if they do not comply is an interesting question.
Jack Ma appears to be still in "reeducation" camp as he has not been sighted for over 6 month after having the cheek to criticise the system. Jack's US$20b float of ANT withdrawn a day before it was due to launch. A whole host of other controlling policies have been put in place in China/Hong Kong, too great to mention.
The point is that the man appears very unstable and can shut an industry down at any time. The Chinese owners of the Australian products banned in China got no special exemption. He will do it to iron ore when he gets a chance. As Zi has appointed himself Chairman for life he could be around for a long time yet.

Best to leave the balance of the money in the bank, after the buyback.