You can just make out one of the demolition contractors with his wheelbarrow at the base of the right stove. Two stoves have gone, and they are probably wrecking the refractory from these two by hand, which explains the pile of rubble all around. A ladder leans precariously against a part-demolished wall.

The ore bridge crane is in the background.

There is a similar photograph to this e in  Iron Mine Railroads of Northern New Jersey, which describes demolition of the plant around 1933.

Blast Furnace slag was tapped from the furnace into these ladles and hauled away to the slag pits. The ladles were tipped by steam, supplied by the slag locomotive which also had to have very good brakes!  This is almost certain to be a product of the William B Pollock Co. of Youngstown. It is probably one of their 300 cubic feet capacity cars, which could handle about 20 tons. 

The site plan suggests that slag was regarded as a saleable product and it may have been used as ballast for highway or railroad construction, or used in the manufacture of cement.