A system includes a quench chamber configured to continuously receive a mixture of a gas and slag, and a downstream end portion coupled to the quench chamber. The quench chamber includes a quench sump configured to continuously separate the gas from the slag in the mixture via a quench liquid. The downstream end portion is configured to continuously convey a slag slurry to a depressurization system. The downstream end portion includes a cooling system configured to directly cool the slag slurry with a cooling fluid, and the slag slurry includes the separated slag and at least a portion of the cooling fluid
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT
 This invention was made with Government support under contract number DE-FE0007859 awarded by the Department of Energy. The Government has certain rights in the invention.