He told the company's annual general meeting Yancoal was reaping the benefits of the assets it acquired in 2017, including the Mount Thorley Warkworth Complex and a 51% share in the Hunter Valley Operations joint venture with Glencore.
"The benefit of the first full year of volume and synergies generated by the expanded asset base was evident as new production records were set and operating costs remained stable despite the broader industry pressures," Zhang said.
"We continue to advance rapidly and with experience, approaching each new endeavour with the knowledge gained from past efforts, meeting the market and operational challenges front on.
"The Tier One assets of Moolarben, Mount Thorley Warkworth and the Hunter Valley Operations Joint Venture, are three of Australia's most efficient, low-cost and long-life assets, providing sustainable coal products to global customers."
Yancoal's 2019 guidance for saleable production is about 35 million tonnes, with stable production costs of $63.5 per tonne - on a free-on-board basis and excluding royalties - and capital expenditure of approximately $285 million.
Zhang said Yancoal was working towards a meaningful production increase at both the Moolarben and Mount Thorley Warkworth operations in future years.