This number they quote for 2012 as a surplus also looks questionable if demand & production grows by roughly the same.
Zinc Surplus 2012 +135,000t
Demand 2012 -13,350,000t (3.74% +500,000t)
Global production +13,370,000t 2012
Real Zinc surplus in 2012 just +20,000t
Zinc 2013 Deficit 13,849,290 - 13,416,000 = -433,290