Fuel gas prodn. from wastes contaminated with heavy metals - by partial oxidn. in presence of sulphur@ to convert volatilised metals to solid sulphide

摘要

Combustible residues (A), polluted with heavy metals, are utilised by partial oxidn. with an O2-contg. agent in a high-pressure flame reaction to produce a crude gas rich in CO and H2 while at least part of the heavy metals are converted to vapour in this gas. The new feature is that oxidn. is carried out in presence of sulphur (in any suitable form) which is at least partly converted to H2S which becomes mixed with the crude gas. This gas is cooled with water under pressure (and becomes satd. by partial evapn. of water) so that H2S dissolves and reacts with the vaporised metals to form the corresponding sulphides which are sepd. as a sludge from the remaining (unevaporated) water. Enough S is used to provide an H2S partial pressure of at least 10 kPa and it is supplied to the oxidn. reaction together with (A). USE/ADVANTAGE - The method is applied to waste materials such as clarified sludge, used oil, drilling emulsions, etc. It provides simple control of volatile heavy metals and no metal-polluted waste waters are generated.