Abstract: Fine-grained substances which do not soften below 800.degree. C., such as oil coke, coking duff, pitch coke and/or fine-grained coal with less than 14% volatile constituents, sand, ores, metal oxides, metals or mixtures of such substances, are introduced in at least two places into a carrier gas stream and are thermally heated to 550-650.degree. C. in the solid discharge of a first cyclone. Then the same carrier gas stream heats coking coal amounting to 18-38% of the intended briquettable product material to 200-400.degree. C. in the solid discharge of a second cyclone. The two solid flows are mixed and treated, producing the briquettable material at 500.+-.50.degree. C. The carrier gas stream is produced by the combustion of liquid and/or gaseous fuels with an excess air factor of 2 or more. Thermally inert, low-ash solid fuels, such as oil coke, pitch coke and/or low-ash, fine-grained, low-volatility coal, amounting to 20-40% of the briquetting material, are initially introduced.