A method for gasifying a carbonaceous material includes supplying a main slurry flow to a main cavity of a two-stage slurry splitter, dividing the main slurry flow into secondary slurry flows that flow into secondary cavities extending from the main cavity at distal ends of first stage flow dividers, dividing each secondary slurry flow into tertiary slurry flows that flow into slurry injection tubes extending from each secondary cavity at distal ends or second stage flow dividers, injecting the tertiary slurry flows into a gasification chamber coupled to the injector module, impinging annular shaped sprays of a reactant onto corresponding ones of the tertiary slurry flows within the gasification chamber using annular impinging orifices in a face plate of the injector module, and cooling the face plate to withstand high temperatures and abrasion.