PROCESS FOR TREATMENT OF COAL CONTAINING ALKALINE EARTH

Coal feedstock, pref. lignite, for hydrogenative liquefaction, contg. alkaline earths, is ground and if necessary dried, pref. to a water content below 20%. It is mixed with a high b.pt. hydrocarbon oil, pref. contg. oxygen cpds., and heated for 1-60 min. under pressure and at 200-450 deg.C. CO2, N2 or H2 may be present. The catalyst for the subsequent hydrogenation may be partly or wholly added before this pretreatment. The reactor deposits obtd. without pretreatment from Ca-contg. coals, esp. lignites, are chiefly calcium carbonate. The pretreatment largely converts the Ca content to CaCO3, which is ultimately removed from the hydrogenator in the reaction residues and does not deposit on reactor or preheater walls. The oil used may be e.g. a heavy oil from coal hydrogenation, a coal carbonisation oil, or a petroleum fraction.