BHP now owns 2.43% of ordinary shares of the coal briquetting company, which were bought at a 10% discount.
Last year BHP and White Energy entered into a $35 million, seven-year funding arrangement.
Through the deal BHP became White Energy’s exclusive marketing agent for its export coal.
White Energy holds the patent to the binderless coal briquetting process which upgrades lower rank coal to increase its energy efficiency.
Earlier this week the company gave the go-ahead for its US subsidiary, White Energy Coal North America, to develop a coal upgrading plant in the Powder River Basin.