* Lithium producer posts Q3 profit of 33.4 mln yuan, -86.5% y/y
* Result is Ganfeng’s worst since net loss in Q4 2016
* Company sees full-year earnings declining by 55-65%
By Tom Daly
BEIJING, Oct 28 (Reuters) – China’s Ganfeng Lithium said on Monday its net profit slumped 86.5% year-on-year in the third quarter as a sharp drop in the value of its financial assets exacerbated a fall in prices for the metal used in electric vehicle batteries.