You are right but you got fooled by "ramo". If this were right, it would mean "branch" of a tree for example, which obviously doesn't make sense.
It is almost certainly (check it with the context) a misspelling of "rame" i.e. Copper (chemical symbol Cu) which is clearly the majour constituent.
With that it becomes clear: the stuff is sold in packaged units (pallets etc) but also in bulk. In this case it will come in lorry loads, already liquid, with all substances dissolved.
"Motrice" means "tractor" and it refers to the bigger tanker lorries, where the tractor is a separate unit and the tanker is just the trailer. In other words, it assures you it's not a piddly lorry, it's a big one, an articulated lorry. Sometimes we Italians like to play it big...