I work in the titanium industry and typically we do everything we can to avoid metal fires. Most metal fines are very reactive (ie titanium, aluminum, magnesium). At high temperatures they react with oxygen or nitrogen to for their respective oxides/nitrides. With titanium and magnesium at high enough temperatures they will react with the oxygen from water and take it. This results in an exothermal reaction (heat realeased) making it possible for other particles of metal to react.

So that being said story time. A couple of years ago I was told about a titanium melt furnace fire that happened about 20 years ago. For those of you who don't know this titanium is melted in a vacuum and melted with an arc in a copper cladded and water cooled crucible. Think of a water cooled copper jacket. It's purpose is to solidify the molten titanium as quick as possible since titanium will react with copper and any other refractory materials at molten temperatures. Well anyways during melting the electric arc jumped to the copper walls. This arc melted the copper, which allowed water to come in contact with molten or near molten titanium. This ended up creating a hydrogen bomb since the oxygen from the water was stolen from the water leaving only hydrogen gas. The furnace is now destroyed allowing the titanium out in the atmosphere. The high temperature titanium ingot/molten metal catches fire. The responders do what they can to contain the fire which is creating a circle pit with salt (might be sand can't recall). Well after the fire runs it course they investigate the damage. The concrete underneath the titanium that melted and caught fire is now turned into sand. The titanium reacted with all of the available oxygen including the oxygen that was in the concrete.

Some fire departments use titanium swarf (titanium fines that have low water content) for training with metal fires.

That being said respect metal fires.