The invention refers to a plant consists of a cylindrical rotary furnace and of a filter for the smokes to be used for producing bituminous conglomerate in continuous cycle. Said cylindrical furnace consists of an initial part of smaller diameter, forming the drying chamber, and of an other part of larger diameter and it provides in its inner a cylindrical structure with fixed duct, brought on head, which lets in the heat flow from the burner to the combustion chamber countercurrent compared to the way of advancement of the inert product. Inside the cylindrical furnace a mixing chamber is then provided. It consists of a closed unit lying behind the wall where is placed the inlet of the heat flow. Moreover the unloading of the product ready to be used from the mixing chamber of the furnace to a programmed time is provided. The filter realizes the blasting of the smokes with continuous unloading towards outside of the purified air. Said filter makes the total recovery and dosing of the fine dust of the cement suspended in the air flow for its prompt use into the mixing chamber. Moreover the filter permits the complete use of the heat flow acting into a closed cycle.

According to the prior art is know the plant described and shown in the Italian Patent Application BO91A 000487.

In comparison with said plant the invented plant providing the heat flow countercurrent compared to the direction of advancement of the inert product into the drying and and combustion chmbers permits, for contact, to increase the heat exchan ge effect so assuring a better yield of the furnace. Being the combustion chamber provides in a closed unit, thanks to the different placing of the unit generating the heat flow, it is avoided the product volatization in particular of the fine dust of the cement and it is permitted to keep the product mixing to a right dosing. The invented cylindrical furnace with its inital part of smaller diameter, contrary to the furnace described in the italian document BO91A 000487 with an unchanged diameter, permits to actuate the widths of the drying and combustion chambers related to the use necessities; this considering that into the drying chamber is prevalent necessary to move the product onto the wall to increase the licking up effect while into the combustion chamber is prevalent the necessity to bring the product onto the heat source.

In the plant described in the Italian document BO91A 000487 the unloading of the product ready to be used from the mixing chamber is actuated in continuous way according to the casuality so determining heterogeneous product.

The invented plant is provided with programmed times for the unloading to avoiding heterogeneous product. Moreover the invented plant permits the complete recovery and dosing of the fine dust of cement for its prompt re-use. Providing the invented plant an isolated filter consists of a closed unit and acts following to the cylindrical rotary furnace, it is possibile to realize the blasting of the smokes present into the circulation air and also to realize the complete use of the plant heat. Moreover being actuated the feeding of the bitumen in the mixing chamber, where there is not a circulation flow, is avoided the dispersion of the same bitumen and consequently it is avoided the air pollution.

Other apparatuses are known, as for instance the apparatuses described and shown in the documents US-A-4 211 490 and US-A-54 054 931.

The invented plant consists of a cylindrical rotary furnace in continuous cyle with upper filter. Said plant brought on a frame with three bridges 1 completed with a bearing structure 2. Said structure 2 provides beams 3, slanting towards the unloading, which bring on couple of rotaring bearings 4 with rollers 5 a cylindrical furnace with initial part of smaller diameter 6 and other part of larger diameter 7. Said furnace having emerging on its outside rims 8 for the contact of the rollers 5 with motion given by a motor 9 which trasmits on the gear 10 of the rotary support 11 to the rack 12. The inert product, after to have being dosed, from the elevator 13, through the inlet 14 present on the transversal fixed wall 15, coming into the drying chamber 16 formed by the inital part of smaller diameter 6 of the furnace. In said drying chamber the product, in continuous movement by means of the vanes, goes on gradually by gravity effect and it arrives into the combustion chamber 17 formed by the other part of larger diameter 7 of the cylindrical furnace. At the end of said combustion chamber the product climbs on a rotary elevator equipped with vanes 18 radially placed on the circular crown 19 emerging from the cylindrical furnace 6-7. Said crown 19 rotates together with the furnace and it forms, with the inner circular fixed part 20 centrally brought by a cylindrical structure 21 housing into the fixed frame 22 sets out on the bearing structure 2, an orifice plate which devides the combustion chamber from the mixing chamber 23. The inert product, after to have being dryed into the drying chamber 16 and to have being baked into the combustion chamber 17, climbs by means of the vanes 18 and it is unloaded in continuous cycle by means of the chute 24 into the mixing chamber 23. In said mixing chamber, through a duct 25, is let in nonasphaltic road oil at 140° coming from a feeder. Contemporary through a screw conveyor 26, coaxially placed around the duct 25, is unloaded into the mixing chamber 23 other material made by fine dust of cement coming from an other feeder and acting as binder. The mixing is facilitated by vanes 27 placed in parallel on the wall mixing chamber 23. To better mix the product it is provided its intermittent unloading. The intermitted unloading actuated by three hydraulic cylinders 28 equipped with timers to regulate the operating times. The hydraulic cylinders 28 open equidistant portholes 29 for the unloading of the product ready to be used which goes on in continuous and is unloaded through the opening 30 of the hopper 31. The product going out from the hopper 31 is then loaded on transport means or used for the different necessities. The cylindrical rotary fornace 6-7 uses a burner 32 which, through a duct provided into the cylindrical structure 21, lets in the flame into the cylindrical furnace through the mouth 33 creating a heat flow countercurrent compared to the material advancing into the drying chamber 16 and into the combustion chamber 17. Upper to the cylindrical furnace, always supported by the bearing structure 2, a parallelepipedal filter 34 is provided with separators 35 which divide the inside space in sectors 36 equipped with fiber filters 37. An intake manifold 38 with air propeller 39 is used for the getting out of the air purified by smokes through the stack 40. With the inert product into the combustion chamber 17 run into the heat jet coming out from the mouth 33, through the collector 41 housing into the head 42, the smokes sucked up by the air propeller 39 pass into an upper duct 43 and coming into a pre-separator 44. Said smokes then arrive into the chamber 45 where, going through the fiber filters 37, are purified. The purified air goes out from the duct 46 and through the intake manifold 38 by the air propeller 39 goes out from the stack 40. The dusts which have being kept into the fiber filters 37 fall into the cone-shaped duct 47 with at its end the Archimedes'screw 48. Said Archimedes' screw 48 unloads the dusts into a duct 49 with a Archimedes' screw 50 where the load cells 51 of fine recovery product are weighed. The Archimedes' screw 50 then unload the fine recovery product into the mixing chamber 23 through the screw conveyor 26. In this way is realized the prompt re-use of the fine dust of cement dispelled into the plant. The invented plant is illustrated in schematic view in the drawings of sheets 1, 2, 3 and 4. Fig. 1 is longitudinal section view of the plant in its initial part with view of the cylindrical furnace 6-7 and of the upper filter 34. Fig. 2 is longitudinal section view of the plant in its end part with view of the mixing chamber 23. Fig. 3 is back view of the plant. Fig. 4 is side view of the plant with view of the frame with three bridges 1.