From what I researched, construction started around June 18, so 2.5 years to complete it looks good.
Delays to start btw 2005 and 2008 was because they had some major permitting issues which resulted in long delays with the PNG government.
Also, Ramu was a greenfields site, with zero infrastructure in place, they had to build port facilities, all infrastructure meaning they had a long lead time on early works, before they could even start on the mine/processing plant
http://pg2.mofcom.gov.cn/article/supplydemandofchina/cooperation/200509/20050900484583.shtml
file:///C:/Users/bovef/Downloads/Ramu_Construction.pdf
