#Dwarf fortress dump water magma full

Once you have the magma in the carts, and no magma left on the floor of the loading room, unlock the door (and unforbid the carts if you used a dump zone to get them there), and your dwarves can now move them around. Make sure that there is a barrier so the evaporating magma can't flow back and set the pump operator on fire. Once the minecarts are full, stop the pump pushing magma in, and start a second pump one level up that pulls the magma out of the loading room, and dumps it in an open space to evaporate (3x3 lets the magma spread out to 1 deep on 7 tiles, which evaporates reasonably fast). The easiest way I have found to do that is to build a magma-safe pump (block, pipe/tube, and giant corkscrew, all made of magma-safe materials like iron, nickel, or glass), and set the pump up so that it is pushing magma into a locked 1x1 room that you have dumped all your magma-safe minecarts into. Any minecart submerged in 6/7 or 7/7 fluid will fill up with 2/7 fluid (subtracted from the amount on the tile, if you have multiple minecarts you are trying to fill at once), and once the minecart is full, you just need to get it back out of the magma, carry it upstairs, and set it on a track stop set to dump the contents into a hole.

#Dwarf fortress dump water magma full

and that 833 is only 2/7 depth, so to get the 4/7 depth you need to power a forge, you would need 170 buckets full even if the game did let you do it that way). (buckets hold 10 'fluid units', while a minecart holds 833. To move small quantities of magma, you would want to use mine carts.