Maybe you are mixing the gerund (dispărând) and the gerundive (dispărare). I think they are the same in Spanish – desapariciendo, could that be? – and in English – disappearing – but not in Romanian: dispărând = who disappears, dispărare = the (process of) disappearing. And by the way – can't you say el desaparecer in Spanish?
Edit: See RotariuAna1's correction below. Thanks.