APPARATUS FOR TURNING AND/OR MIXING A FLAT BED COMPOST

Abstract: The invention relates to an apparatus (7) for turning and/or mixing a flat bed compost. The apparatus (7) is provided with substantially vertical mixer elements (1, 2) which, during the operation of the apparatus, are adapted to travel within a composting mass and to mix the mass. The apparatus is adapted to travel freely on top of the composting mass without external support and/or guide structures. The apparatus can be towable by a vehicle, e.g. a tractor, or self-propelled.

Description: Apparatus for turning and/or mixing a flat bed compost The present invention relates to an apparatus for turning and/or mixing a flat bed compost. The apparatus can be towable by a vehicle, e.g. a tractor, or self- propelled. The term flat bed compost refers to a continuous "mattress", which is most commonly 0,8 - 2,5 metres in height and made up by compostable organic waste. In flat bed composting, the compostable waste is not worked into separate stacks like in traditional composts. Flat bed composting is a common practice, especially in mechanically aerated composting systems. Flat bed composting is a common composting process used in composting carried out in special buildings or in separate silos. Thus, the turning and mixing of a compost mass is generally effected by implements which are mounted e.g. on a separate guide bridge, rails constructed alongside the bridges, or other such support structures present outside the composting mass. Such turning implements are not suitable for working large continuous flat bed composts. The working of flat bed composts is also performed by using motor-driven or tractor-drawn turning or mixing implements which travel along the field surface and remove compostable mass from one side of the path thereof over to the other. In this case, the removal of compost is effected either by means of a separate conveyor or by centrifuging. An object of the present invention is to provide an apparatus, which is suitable for the effective and frequently repeated turning and mixing of a shallow flat bed compost (0,8 - 1 ,5 m in thickness) in particular, and which apparatus is also effectively useful for turning and mixing large, e.g. multi-hectare outdoor flat bed composts. In order to achieve this objective, an apparatus of the invention is characterized in that the mixer elements comprise an even number of mixing worms rotating around a vertical shaft, said mixing worms being adapted to rotate in directions opposite to each other in such a way that half of the mixing worms rotate clockwise and the other half rotate counter-clockwise, and said mixing worms being adapted to bring compost mass from the bottom upwards. A few preferred embodiments of the invention are set forth in dependent claims 2-6. The benefits offered by an apparatus of the invention with respect to prior art methods of working a flat bed compost include, e.g. the following: - Since the apparatus of the invention travels along the surface of a composting mass, said apparatus does not require any clear passage for its working. Thus, the field area can be exploited as thoroughly as possible. It is also true that, as the work is interrupted, the composting mass will not be left with an empty furrow which, e.g. in case of abundant rains, may become drenched and turn into unmanageable mud. - Since the apparatus of the invention moves a composting mass to be treated only a short way from its original place, the relationship between the input of said apparatus and the amount of mass manageable per time unit is more favourable than what is achievable with presently available equipment. - Particularly in cold conditions, the apparatus of the invention is beneficial in terms of its operation. The apparatus primarily aerates and mixes the mass to be treated and supplies air within the mass. When using equipment designed earlier for the same purpose, the compost mass to be treated is exposed to chilling ambient air for a considerably longer period of time, whereby the mass to be composted in cold conditions may cool too much. The aeration of a compost mass performed by an apparatus of the invention can be enhanced by using mixing elements in the form of hollow shaft mixing worms, having the shafts thereof provided with holes for supplying air more effectively into the bottom portion of a composting mass. As the mixing worms work a composting mass upward, the bottom section of the mixing worms develop inherently a negative pressure which enables the air to migrate effectively into the mass. The migration of air can be further enhanced by fitting the apparatus with a fan for blowing air into the shafts of the mixing worms. The invention will now be described in more detail with reference to the accompanying drawings, wherein fig. 1 shows one embodiment for an apparatus of the invention in a view from behind, fig. 2 shows the embodiment of fig. 1 in a plan view, and fig. 3 shows the embodiment of fig. 1 in a lateral view. In the embodiment of figs. 1 -3, a turning and mixing apparatus intended for working a flat bed compost is depicted as a tractor-operated application. The illustrated embodiment shows an apparatus 7 provided with four mixing worms 1 , 2. The mixing worms are located pairwise on either side of the median in the advancing direction (an arrow A in fig. 2) of the apparatus, whereby the mixing worms 1 on the left-hand side in a rear-end view (fig. 1 ) rotate clockwise and the right-hand mixing worms 2 rotate counter-clockwise. The mixing worms are also conceivable to be designed e.g. in such a way that the left-hand mixing worms rotate in opposite directions relative to each other and, respectively, the right- hand mixing worms in opposite directions relative to each other. The clockwise running mixing worms are provided with a right-hand thread and those running counter-clockwise with a left-hand one, whereby both pairs of mixing worms bring compost mass from the bottom upwards. In the illustrated embodiment, the apparatus receives its drive from the output shaft of a tractor by way of a wide- angle cardan shaft. The tractor which operates the apparatus is provided with a hydraulic push rod and wide wheels. Transmission in the apparatus 7 is effected by way of angle transmission 3 and chains 4. The mixing worms 1 , 2 include shafts 5 which are hollow and provided with holes for aspirating air thereby through the shaft 5 into the bottom portion of a composting mass. The air has an access into the shaft by way of holes arranged on the top end of the shaft. The shafts have the bottom end thereof provided with a wear-resistant element 6 whereby, when using the apparatus e.g. on a concrete- or asphalt bed, the apparatus 7 can be maneuvered upon the durable elements 6 along the bed. On a soft ground, e.g. a sand bed, the apparatus is most preferably supported exclusively by the three-point linkage of a tractor. Designated in the figures with reference numeral 8 are wheels, functioning in an indoor space as crash protectors. The test apparatus according to the described embodiment has a working width of 3500 mm and a working depth of 1300 mm and a weight of 1150 kg. Such an apparatus is capable of mixing and turning about 1000 to 2000 cubic metres of compost per hour. These dimensions and performance figures for the apparatus are only given to represent one exemplary apparatus and by no means intended to limit the scope of protection for the invention as defined in the claims. In the present embodiment, the apparatus is described as a towable implement attached to a tractor, provided with mixer elements which receive the drive therefor from the output shaft of a tractor, but it is also conceivable to construct the same provided with a separate drive motor for the mixer elements. The apparatus can also be designed as a self-propelled implement fitted with its own engine.

Claims: Claims 1. An apparatus (7) for turning and/or mixing a flat bed compost, said apparatus being provided with substantially vertical mixer elements (1, 2) which, during the operation of the apparatus, are adapted to travel within a composting mass and to mix the mass, and said apparatus, or a machine driving said apparatus, being adapted to travel freely on top of the composting mass without external support and/or guide structures, characterized in that the mixer elements comprise an even number of mixing worms (1 , 2) rotating around a vertical shaft, said mixing worms being adapted to rotate in directions opposite to each other in such a way that half of the mixing worms rotate clockwise and the other half rotate counterclockwise, and said mixing worms being adapted to bring compost mass from the bottom upwards. 2. An apparatus as set forth in claim 1 , characterized in that the shaft of the mixing worm (1 , 2) comprises a hollow shaft (5), and that the shaft (5) has its bottom portion provided with at least one hole for supplying air into the bottom portion of a composting mass. 3. An apparatus as set forth in claim 2, characterized in that the apparatus is further provided with at least one fan for supplying air into the shaft (5) and through said air hole into a composting mass. 4. An apparatus as set forth in any of the preceding claims, characterized in that the mixing worms have the bottom end thereof provided with a replaceable durable element (6) which, if necessary, can be adapted to travel along the surface of a bed for a flat bed compost mattress. 5. An apparatus as set forth in any of the preceding claims 1-4, characterized in that the apparatus (7) is adapted to be towed by a tractor or the like machine or to be attached to the hoist mechanisms of a tractor or the like machine, and that the apparatus is connectable to the drive output means of a tractor or the like machine for driving the mixing worms. 6. An apparatus as set forth in any of the preceding claims 1 -4, characterized in that the apparatus (7) is self-propelled.

Inventors: HAASLAHTI MIKKO, HAASLAHTI OSMO, HAUKIOJA MARKKU, MAELKIAEINEN PAAVO, HAASLAHTI, MIKKO, HAASLAHTI, OSMO, HAUKIOJA, MARKKU, MAELKIAEINEN, PAAVO
Applicants: BIOLAN OY, HAASLAHTI MIKKO, HAASLAHTI OSMO, HAUKIOJA MARKKU, MAELKIAEINEN PAAVO, HAASLAHTI, MIKKO, HAASLAHTI, OSMO, HAUKIOJA, MARKKU, MAELKIAEINEN, PAAVO
Application year: 1999
Main classification: C05F17
IPC codes: B01F7, C05F17