A device for removing heavy metals and slags from synthesis gas produced from refinery wastes includes a gas deflecting device (3, 4), in which the hot synthesis gas, flowing vertically in the downward direction, is deflected into the horizontal direction and enters a known waste heat cooler (2). The gas deflecting device is arranged under a prior-art synthesis gas reactor (1). A ceramic deflecting wall (5), around the lower end of which the synthesis gas is guided, is built in within the deflecting device (3, 4). Since synthesis gas produced from refinery wastes contains a relatively high percentage of heavy metals and slags, there is a risk that these particles will contaminate the [heat] exchanger walls of the subsequent waste heat cooler (2). The heavy metals and slags are separated frown the gas flow in the deflecting device (3, 4). The heavy metal and slag particles present in the liquid form within the hot gas follow a downward path due to their higher specific gravity compared with that of the gas and enter a water quencher (7) arranged under the deflecting device (3, 4), in which they granulate. The synthesis gas, freed from heavy metals and slags, enters the downstream waste heat cooler (2).