Tronox, a producer of the white pigment titanium dioxide, has agreed to purchase FMC’s soda ash business for $1.6 billion. The FMC business is the world’s largest producer of natural soda ash, or sodium carbonate, which is used to make glass, detergents, sodium bicarbonate, and other chemicals. FMC has a 25% share of the natural soda ash market, and its mining operations in Green River, Wyo., sit atop the world’s largest reserves of trona, a mineral used to make soda ash. The business generated about $800 million in sales in 2014. Tronox, which merged with the mineral sands operation of South African mining giant Exxaro in 2012, is familiar with mining operations. Tronox says it is considering further acquisitions to help it diversify. FMC had originally intended to spin off the soda ash business and its lithium chemicals unit into a new company. However, when it agreed to purchase the agricultural chemicals maker Cheminova last September, it decided instead to keep lithium and divest soda ash.