Abstract: A sinterable mixture comprising iron-containing materials and solid fuel is sintered on a sintering machine; to decrease the rate at which exhaust gas is to be removed and to produce a desirable sinter, a part of the exhaust gas is enriched to an oxygen content of up to 24% by the addition of higher-oxygen gases and is then recirculated as a recycle gas, and exhaust gas is removed as a tail gas from the process only at a rate which corresponds to the rate of the gas which is formed during the sintering process plus the rate of the gas added for enriching plus the rate of inleaked air which has infiltrated from the outside minus the rate of oxygen consumption.

Abstract: In a process of recovering oil from oil-containing minerals on a traveling grate, hot gases are passed through the bed in a retorting zone, oil is separated from the retort gases in a separating stage, solid carbon in the retorted bed is burnt in a succeeding combustion zone by means of oxygen-containing gases passed through, gases from which the oil has been removed in the separating zone are passed through the bed in a succeeding cooling zone and the heated gases are recycled to the retorting zone.

Abstract: Oil-containing materials and part of the hot burnt material which is available after the combustion of solid carbon are charged into a retorting shaft reactor and the oil-containing mineral in the mixture is heated to the retorting temperature.