Wistow opened in 1983 and set a European production record in 1995. It is the third of five mines slated for closure by owners, UK Coal, with the remaining two due to end production by August.
The company is confident of securing a long-term future if it can maintain the progress of last year.
Chief executive Gordon McPhie, quoted in UK Coal newsletter NewScene, said while unit costs had been reduced further improvements were required to compete with foreign imports.
“We can improve the utilisation of our costly equipment by about 50% without anyone having to work more hours, by employing more people. We need to change our attitude to working arrangements largely unchanged since 1947. It is now down to us,” he said.
Production costs last year were trimmed 2p to £1.16 a gigajoule but income only averaged £1.12p.
“We are planning to treble our investment program in 2004 but we’ll only do what we can afford,” he said.