Not being a material expert, I think I can give some additional information to the above (mainly concerning application to fertilizers), since I worked in the operations of a phosphoric acid plant (treating phosphates) in 1976-1979. For mentioned tank size (3000 m3), only rubber lined tanks were considered economical, and I believe this is also true today. At that time Glass Reinforced Plastic tanks could be used for capacities up to (say) 200 m3 and 316 L tanks (or of similar grade) for much lower sizes. In 1964 "lead cladded" tanks (400 m3 each) were erected, which had many maintenance troubles and went out of service in early 1980s. For the mentioned rubber-lined tanks (30% or 50% P2O5, open, vertically agitated, max liq temp about 60 oC) no excessive maintenance problems were encountered. It is however noted that rubber lining needs to be implemented by a contractor of proven experience; and sandblasting of tank internal steel walls should be "meticulous".