The agreement signed with Bengbu Zhongheng New Materials S&T Co is based on a five-year minimum annual supply of 150,000 tonnes of low temperature roast ilmenite, representing about 50% of the estimated total volume of LTR ilmenite to be produced from the first stage project.

All initial zircon production is already contracted under binding agreements, with Sheffield's feasibility work modelling 62% of revenue from Thunderbird to be generated by the zircon produced and 38% by the titanium feedstocks.

Thunderbird will cost A$348 million to build, with capital markets group Taurus mandated last October as lead arrangers and underwriters for a US$200 million debt finance facility package.

Taurus' due diligence was anticipated to be completed a few months ago, with Sheffield saying in April "the due diligence process continues to support the key BFS process design and cost assumptions and has identified a number of opportunities to improve operability of the process plant".

Sheffield started the current quarter with A$25 million of cash.

Shares in Sheffield were down 0.7% to 74.5c in early trade, capitalising the company at $171 million.

Sheffield raised around $30 million late last year by issuing new shares priced at 70c each.