[0002] Rotating and cylindrical drums, in which material to be treated can be mixed or washed, are known for treatment of material, such as various types of crushed aggregate and earth. Washing refers to treating e. g. polluted soil in a rotating drum, in which chemicals are mixed with the material or it is treated with superheated steam so as to remove impurities from the material. Prior art drums are intended either for continuous or batch treatment.

In other words, the different drum types are intended for different types of treatment. Thus, it is impossible to use one drum equipment for different treatments.

[0003] Most typically, a continuously operating drum is constructed such that material to be treated is introduced into an elongated, cylindrical ro- tating drum at a first end thereof. The material passes in the axial direction of the drum towards a second end of the drum, wherefrom the material is dis- charged treated. Within the drum, there are typically screw-like spirals that convey the material forwards. In addition, wing-like blades that ruffle the mate- rial are arranged inside the drum for the treatment. A drawback with these drums is that they take a lot of space in transport, because the drum is several meters in length. Moreover, it is very difficult to adjust the drum treatment and the treatment time, because the interior conveyor means of the drum convey the material forwards at an even speed.

BRIEF DESCRIPTION OF THE INVENTION [0004] The object of the present invention is to provide a drum for treating material, which avoids the above drawbacks and which can be oper- ated both on a batch basis and on a continuous basis. This is achieved by a drum according to the invention, which is characterized in that a feed opening and a discharge opening for material to be treated are arranged in a hollow centre piece that is arranged inside a cylindrical piece, the feed opening being

located substantially in a lower portion of the hollow centre piece interior as the drum is in its operating position, and the discharge opening being located substantially in an upper portion of the hollow centre piece interior as the drum is in its operating position, whereby the drum structure enables batch use and continuous use of the drum.

[0005] The invention is based on the idea that the drum for treating material comprises an outer cylindrical part that is arranged to be rotatable about its axis and an inner part that is stationary. Material is introduced through this stationary part to the actual material treatment space which forms between the outer, rotary piece and the inner, stationary piece. In the drum according to the invention, the material is also discharged from the treatment space through the inner part.

[0006] By this arrangement, it is possible to make the drum for treating material relatively short in the axial direction, which enables easy transport of the drum. In addition, when the material is introduced and dis- charged according to the invention, the drum permits both batch use and con- tinuous use.

BRIEF DESCRIPTION OF THE DRAWINGS [0007] In the following, the invention will be described in connection with preferred embodiments, with reference to the attached drawings, wherein Figure 1 is a front view of a drum of the invention partly cut open; Figure 2 is a side view of a drum of the invention in partial cross section.

DETAILED DESCRIPTION OF THE INVENTION [0008] Figure 1 shows a drum of the invention cut open, seen in the axial direction of the drum. The drum is shown in its operating position, i. e. such that the drum axis is substantially horizontal. According to the invention, the drum comprises a cylindrical piece 1 that is arranged to receive material to be treated. This piece is also arranged to rotate about its axis and thus to mix the material introduced therein. A material treatment part of the drum accord- ing to the invention is made to rotate about its axis by means of rollers, belts or wheels connected to electric motors, for instance. Such wheels 2 supported to the outer surface of the cylindrical piece are shown in Figure 1, by way of ex- ample.

[0009] The drum of the invention comprises a centre piece 3 ar- ranged inside the cylindrical piece 1. The centre piece is secured fixedly into place, whereby the cylindrical piece can freely rotate around the centre piece.

The stationary centre piece and the cylindrical piece are connected by a mo- tion joint 4, at which the centre piece and the cylindrical piece partly overlap.

The cylindrical piece, whose interior constitutes a treatment space of the mate- rial, is thus a cylinder whose end parts are open in the middle.

[0010] The structure of the centre piece 3 is such that its centre portion, which is substantially located at the rotation axis of the cylindrical piece, is hollow. The hollowness of the centre piece 3 enables the material to be introduced into the treatment space inside the cylindrical piece 1 through the centre piece. For this purpose, the centre piece is provided with a feed opening 5 for the material to be treated, which feed opening is located sub- stantially in a lower portion of the hollow interior of the centre piece. It is simple to feed the material into the drum through this feed opening, because the feed opening is disposed in the stationary centre part. Substantially leak-proof hatches that can be opened and closed are also arranged in connection with the feed opening.

[0011] For feeding material, according to one preferred embodiment of the invention, it is possible to use a material feeding means, such as a con- veyor belt 20, which is shown in the schematic cross section of the drum in Figure 2. By using the conveyor belt, the material can be transferred for treat- ment continuously in a simple manner while the belt supplies material above the hatch, wherefrom it can fall freely into the drum, into the treatment space.

[0012] A plurality of material lifting means 7 are arranged inside the rotary cylindrical piece, the lifting means consisting of plates disposed in the axial direction of the cylindrical piece. These plates are secured to the inner surface of the cylindrical piece such that as the piece rotates the planar sur- faces of the lifting means face the direction of motion, and the lifting means extend from the first end to the second end of the cylindrical piece. Thus, the lifting means efficiently mix the material in the treatment space, ruffling and lifting it due to the rotating motion. The lifting means 7 are designed such, or may comprise a particular control, that the material is allowed to fall off from the lifting means at a desired point. The controlled lifting means permit to ad- just the treatment time of material.

[0013] A material discharge opening 6 is also arranged in the cen- tre piece, according to the invention, through which discharge opening the material that has been treated in the drum is discharged treated. The dis- charge opening is located substantially in the upper portion of the hollow inte- rior of the centre piece as the drum is in its operating position. According to the preferred embodiment of the invention, one or more openable hatches are ar- ranged to cover the discharge opening, the opening degree of the hatches being adjustable.

[0014] According to one embodiment of the invention, a material discharge means 21 is arranged below the discharge opening as the drum is in its operating position. This discharge means can be a conveyor belt, for in- stance. The material, which is lifted up by the lifting means 7 and whose dis- charge from the drum is desired, is dropped through the discharge opening onto the conveyor belt or the like, which conveys the treated and discharged material for further processing or use.

[0015] According to the preferred embodiment of the invention, an auxiliary agent dispensing means 8, which can be e. g. an extruder-type noz- zle, is arranged in the hollow centre piece of the drum. The function of the auxiliary agent dispensing means is to add auxiliary agent, such as binding agent, detergent or steam, needed in the treatment to the material to be treated. For instance, when polluted soil is purified the above-mentioned steam or detergent can serve as the auxiliary agent. The dispensing of the auxiliary agent is simple to perform into the drum of the invention, because the dispensing means 8 is disposed in the stationary centre piece 3 of the drum.

Thus, the dispensing can be directed accurately to the desired point in the treatment space. Generally, an appropriate dispensing point is at point 9, where the material to be treated falls downwardly in the treatment space, off from the lifting means 7. When the material falls, it is aired, whereby the dis- pensing of auxiliary agent, for instance, as a spray, becomes in contact with as large amount of material as possible.

[0016] Because the material may fall from the lifting means on a wide area, it can be appropriate, in certain cases, to make the falling point nar- rower and to guide the material more focused by a separate guide means 10, which is adjustably secured to the stationary centre piece 3 of the drum of the invention. According to one preferred embodiment of the invention, the centre piece 3 is cylindrical.

[0017] The drum of the invention allows both batch use and con- tinuous use, thanks to its characteristics. When operated on a batch basis, a desired amount of material to be treated is introduced into the drum through the feed opening 5. The drum is allowed to operate, with the same material inside the drum, until the desired treatment, e. g. washing, is carried out. To prevent the material from being discharged through the discharge opening from the drum as it rotates, it is possible to close said opening or adjust the lifting means of the material such that the material cannot rise so high that it could fall from the discharge opening. When the material should be discharged from the treatment space, said discharge opening is opened, the fixed lifting means being concerned, whereby the material can fall from the discharge opening little by little onto a discharge conveyor, and be transported by said conveyor for use or further processing. If the drum is provided with adjustable lifting means, they allow the material to fall at a right point for discharge.

[0018] When the drum of the invention is operated continuously, desired amounts of material to be treated are introduced into the treatment space of the drum through the feed opening 5. For continuous feeding, a con- veyor belt, by which material can be fed steadily into the drum, is a good solu- tion for a feeding means 20. As the drum rotates, the lifting means 7 lift the material, small amounts at a time, from the drum through the discharge open- ing 6. The lifting means are designed such, or controlled at such an angle, that some of the material falls from ; the lifting means prior to the discharge opening and is reintroduced into the treatment space. The treated material that is dis- charged through the discharge opening falls from the treatment space onto the conveyor means that transports the material for further processing or use.

[0019] In connection with the continuous operation, the amount of material inside the drum equalizes as the drum rotates, if the feeding remains substantially equal. In a balanced situation of this kind, the whole amount of material is treated evenly.

[0020] The drum of the invention is extremely versatile in use, and it can be readily transported wherever needed thanks to its short axial meas- urement. The diameter of the cylindrical piece can be e. g. 4 m and the axial length only 2 m. A structure of this kind permits simple transportation, for in- stance, as a whole constructed on a carriage of a drawing vehicle, comprising necessary support structures and a drive for rotating the drum.

[0021] It is obvious to the person skilled in the art that as technol- ogy progresses the basic idea of the invention can be implemented in a variety of ways. Thus, the invention and its embodiments are not restricted to the above-described examples but they may vary within the scope of the claims.