In a deal that industry watchers say should trigger further consolidation in the coal industry, Tampa, Fla.-based Walter Energy Inc., a maker of coal for the steel industry, has offered to buy Vancouver, British Columbia-based Western Coal Corp. for $3.2 billion.

The deal is unusual, lawyers on the matter say, because of its sequencing. Rather than announcing an acquisition outright, the two companies announced an agreement to negotiate towards one. The nonbinding agreement states that they will talk exclusively with each other for 14 days with the intention of signing a deal at the end of that period.