A system for buoyant particle processing includes: a reaction vessel, a stirring mechanism, a set of one or more pumps, and a filter. The system can additionally or alternatively include a set of pathways and/or any other suitable component(s). A method for buoyant particle processing includes: stirring the contents of a reaction vessel; washing a set of buoyant particles; and filtering the contents of the reaction vessel. Additionally or alternatively, the method can include any or all of: preprocessing the set of buoyant particles; adding a set of inputs to the reaction vessel; washing the set of buoyant particles; repeating one or more; and/or any other suitable process(es).