The original inquiry is below.  There should not be a chemical reaction to worry about (CO2 is a byproduct of producing iron metal in the blast furnace; CO is used to reduce the iron oxides to Fe + CO2), but you would have to worry about potential frostbite because CO2 extinguishers produce temperatures that are below -40 C and there is no effective way to measure the temperature during the "treatment".   See https://escholarship.org/uc/item/17r2w1z9

While water would normally ideal, in this case there is a significant risk of a steam explosion when water contacts molten iron:  see https://www.osha.gov/pls/imis/accidentsearch.search?sic=&sicgroup=&acc_description=&acc_abstract=&acc_keyword=%22Molten%20Metal%22&inspnr=&fatal=&officetype=&office=&startmonth=&startday=&startyear=&endmonth=&endday=&endyear=&keyword_list=on&p_sort=event_date&p_desc=ASC and http://link.springer.com/article/10.1007%2FBF02588540#page-1     In fact, there is a notorious case of a classroom thermite demo that caused injuries when a few grams of molten iron was deliberately dropped into a bucket of water.

Presumably, once the metal is removed from the victim, water is the fastest and best method for cooling the person, but one would have to take appropriate precautions to remove the victim from the area before treatment - large quantities of water in use near large quantities of molten iron could cause a major catastrophe.

I figure there's someone on the list who must already have figured out the proper procedure or knows where to find one.  DCHAS rocks!

Thanks,

Rob Toreki