Ann: CENTURY OPERATIONS AGAIN DELIVER RECORD METAL PRODUCTION, page-158

If you think most of the flows out of LME warehouses from 2013/2014 were due to high demand that is just not correct.
It was mostly moving material from LME to non LME warehouses due to changes in load-out rules in 2013. This article looks at aluminium but the dynamic was the same for the zinc market (especially large volumes of zinc stored in LME warehouses in New Orleans):

https://uk.reuters.com/article/uk-lme-warehousing-ahome/column-why-london-metal-exchange-warehouses-thrive-in-the-shadows-idUKKCN1UL1OG

https://www.reuters.com/article/us-zinc-stocks-ahome/the-zinc-carousel-keeps-turning-in-new-orleans-andy-home-idUSKCN0RF29O20150915

Sure since then due to lower production from smelters/mines on C&M significantly drew down LME & shadow stocks but saying that the LME stock movements out = Physical demand is not correct.

If you actually want to look at the strength of physical demand look at the premium levels for zinc and whether there is a positive arbitrage for zinc to flow into China.