So theoretically the extruder can pump solder through it, it shouldn't have any problem getting to the melting point. But metal doesn't have whats called a "glass transition temperature" which in human terms means "the temperature when things get gooey". Plastics can be used for 3D printing because they can be heated just passed their glass transition temperature (often written Tg), to a point of gooeyness and then stuck together in layers. Metal never gets gooey, it is either a liquid or a solid, so if you just tried to print with it, then you would end up with a puddle, not a thing.
Now if you are trying to use the printer to solder and not to print, that is possible, though would be so hard that it wouldn't be worth doing. If you want to look into a more automated way of soldering look at reflow soldering. here's the wiki link [
en.wikipedia.org] . As i understand it this is how a lot of professional/industrial soldering is done, though it is not my area of expertise.
I would say, make sure you have a spare hotend/nozzle just to be safe, but try it. At worst you have to replace some parts, just learn something in the process. And post what you learned so we can keep building the rep-rap community knowledge. and pictures, pictures are always fun.
