In a transaction expected to close in the first quarter, US titanium dioxide specialist Tronox has agreed to acquire the Alkali Chemicals unit of compatriot FMC for $1.64 billion.

With the takeover, the company's sales will rise to about $2.6 billion annually.

FMC is considered to be the largest global producer of natural soda ash, with mining and processing facilities located at Green River, Wyoming, and annual sales of around $800 million.

In September 2014, FMC announced plans to acquire agrochemicals producer Cheminova of Harboøre, Denmark for around $1.8 billion, saying it would divest the soda ash business to reduce acquisition-related debt and in future would focus on global agriculture, health and nutrition in high-growth markets.

Tronox plans to finance the purchase through about $1 billion in cash and about $600 million of new debt, pursuant to signed commitments received from UBS Investment Bank, Credit Suisse, and RBC Capital Markets.

The transaction is expected to be significantly accretive to EBITDA, free cash flow, and earnings upon closing, the company said.

"With its industry-leading position in markets complementary to ours, alkali chemicals brings strong operational and financial performance," said Tom Casey, chairman and CEO of Tronox.

FMC's soda ash business has consistently delivered EBITDA margins in excess of 20% and converted approximately 75% of its EBITDA to free cash flow, Tronox added.