TECHNOLOGY FOCUS - ENVIRONMENT - Preferred materials: In (I), the combustible waste is paper and plastic (especially it also contains at least one from coal, coal tar, pitch, activated sludge and oil residue; or it also contains mill scale and electric dust collector dust). In (I), the process exhaust is at least one from refuse incinerator, electric power plant, steel production electric furnace, scrap melt furnace and iron sintering equipment exhaust gases. In (I), (II) and (III), the combustible waste is refuse-derived fuel (RDF). In (II), the combustible waste contains RDF. In (II), the combustible waste has 0.2-0.8 O/C and 0.5-2.3 H/C atomic ratios. In (III), the combustible waste is RDF and coal or high carbon material refuse.Preferred methods: Step (a) is at 400 degrees C or more (especially 600 degrees C or more; more especially 1000-1300 degrees C). Step (a) is in an inert atmosphere. In step (a), the carbonized product is activation treated.In (I), a further step is added to pulverize the carbonized product to at most 5 mm particle diameter. In (I), the carbonized product has at most 5 (especially at most 1) wt.% volatiles. In (I), a further step is added to use the recovered carbonized product as a fuel or raw material (especially the fuel is used for the production of sintered ore in sintering equipment for iron production). In (I), the fuel is used in iron sintering or sintered ore production. In (I), a further step is added to use the combustible gas as a heat source for destructive distillation or iron production processes. In (I), the combustible waste is paper and/or plastic and also mill scale and/or electric dust collector dust, and step (a) is at 1000-1300 degrees C. Step (i) is at 300-800 degrees C. In step (ii) a briquette machine is used for molding, to make briquettes. Step (iii) is at 600-1000 degrees C in the presence of steam. In (II) and (III), the destructive distillation gas is used as the heat source for destructive distillation.In (II), further steps are added to break up the preliminary carbonized product, and remove iron and non-ferrous metals. In (II), a further step is added in which coal or coke is added to the preliminary carbonized product. In (II), a further step is added in which a binder is added to the preliminary carbonized product and mixed in. In (II), a further step is added in which the carbonized product is used to treat an exhaust gas. In (II), a further step is added in which fine particulate carbonized product is removed from the carbonized product, and returned to step (ii). In (II), a further step is added in which fine particulate carbonized product is removed from the carbonized product, and used as a fuel for blowing in.In (III), the destructive distillation is at 0.5-50 MPa. In (III), the residue obtained by destructive distillation is pulverized and the carbonaceous substance and ash are separated. In (III) a preliminary step is added to prepare the RDF, especially by impregnating with a binder (optionally followed by compression molding); especially carrying out destructive distillation in the presence of steam; especially carrying out activation treatment on the carbonized product; especially using the destructive distillation gas as a heat source for destructive distillation. EXAMPLE - A refuse-derived fuel (water content = 3.2 wt.%; volatiles = 72.3 wt.%; solid carbon = 13.1 wt.%; ash content = 14.7 wt.%; exothermic amount = 3850 kcal) was heated to 600 degrees C at 10 degrees C/minute under 50 ml/minute nitrogen gas flow, and heated at 600 degrees C for 10 minutes at atmospheric pressure, to give a particulate carbonized product (activated C = 30 wt.%; ash = 44 wt.%; specific surface area = 116 m2/g; JIS M8812).