What with the rise in Zinc stocks on the LME overnite and...

What with the rise in Zinc stocks on the LME overnite and ensueing fall in price Id like to put a question to the forum, How are the LME stockpiles actually compiled,is it actual physical tonnes in LME registered warehouses,is it done useing "promises to deliver" or maybe a combination of both, or even something completely different?. If useing "promises "or part therof, surely this leaves it wide open for manipulation(up or down!) Another little niggle I have is, if the demand for Iron Ore is so strong(and tipped to continue to rise!) and zinc is the primary form of rust prevention(galvanising) is mine production of zinc going to be able to rise enough to meet the need?.I see reports of a rise in zinc production as to put the market into surplus but has the Iron Ore Factor been given due consideration?
regards