Champion has about $426 million cash on hand, with the remaining capital required for the expansion estimated to be $512.6 million.
The company produced nearly 2.27Mt of concentrate last quarter from Bloom Lake (in Canada), equivalent to an annual run rate of about 9Mt.
Cashflow from operations in the September quarter totaled $128.3 million.
The expansion will take about 18 months to complete.
Shares in Champion were unchanged at A$3.93 in morning trade, capitalising the company at $1.86 billion.
Champion's stock has doubled since the end of April.