The Moolarben complex produced 5.5Mt of ROM coal in the quarter as the open cut and underground both performed well.
"The mine, and in particular the open cut has started the year strongly," the company said.
"The longwall began the quarter in a location of low-cover. This slowed the cutting rate, but once it retreated to an area of higher cover the cutting rate improved.
"The longwall performed well in February, operating at the target rate of 2,200tph average."
According to Yancoal the longwall was able to run all month in automated mode with minimal corrections required.
"A new shearer software program installed in late February further improved the automation performance in March," it said.
"Two longwall moves are scheduled in 2019 to step around a dyke in the coal seam, but with the open-cut delivering almost two-thirds of the ROM coal the impact in any given quarter is manageable."
The company said there was no significant production impact on Yancoal from wet weather in Queensland, and there was no material sales volume impact related to the coal import delays into China during the March quarter.
"Throughout the March quarter pricing, higher grade coals held up better following the impediments to Australian thermal coal deliveries into China adversely impacting prices of lower quality coals," Yancoal said.
"Yancoal has the flexibility to reallocate cargoes to alternate buyers, and in the March quarter, it did not experience a significant impact on sales volumes, despite volatile regional market conditions."
The company said the demand for premium quality thermal coal in Asia remained strong and supply of this coal grade tight, which was expected to support prices in the medium term.