It is desirable from an environmental viewpoint to reduce such mixtures, such as manure or industrial effluent, to a dry mixture. This simplifies processing thereof and, in the case of manure, the fertilizer constituents are moreover preserved.

Different devices are known for drying such mixtures. A device is known for instance wherein a drying bed is present through which air can be blown and on which the mixture, preferably a stackable mixture, is spread out. The mixture can optionally be arranged on a special carrier layer. This results in a layer of several centimetres on the drying bed which has to be dried by the air blown therethrough.

It has been found however that the drying process progresses slowly in such devices, and that a good air permeability is not always ensured.

It is an object of the invention to provide a device with which the drying process can be accelerated compared to existing devices and wherein the energy consumption is also kept low.

This objective is achieved with a device according to the invention, which device comprises: - a storage tank for holding the mixture; - an evaporation surface which is at least displaceable between a wetting position, in which the surface is wetted by the mixture, and an evaporating position in

which moisture is evaporated from the arranged mixture; - ventilation means for causing an airflow in order to dry the wetted surface.

Because the evaporation surface is displaced between the wetting position in for instance a storage tank and an evaporating position outside it, it is ensured that the surface of the evaporation surface is always wetted with a small quantity of the mixture. This wetting can take place in that the surface runs through the mixture or in that the mixture is for instance sprayed onto the surface. The ventilation means then ensure that an airflow flows along or through this evaporation surface, thereby drying the mixture that is present. A subsequent quantity of mixture can then be arranged on the surface and dried. By repetition hereof all the mixture in the storage tank can eventually be dried.

An additional advantage is that the ventilating air is also washed. Dust is therefore left behind in the evaporation surface. In addition, odour and ammonia can likewise be absorbed by the mixture on the evaporation surface.

In a preferred embodiment agents are added to the mixture for reaction with constituents contained in the air.

Agents can thus be added for instance which react with aromatic substances or other substances in the air or which increase or decrease the pH.

A preferred embodiment of the device according to the invention comprises at least one conveyor belt, which conveyor belt forms at least a part of the evaporation surface. The conveyor belt can preferably extend between two reversing rollers, one reversing roller of which is situated at least partially in the mixture. The surface of the conveyor belt is thus provided at all times with a part of the mixture by driving the conveyor belt.

In another embodiment of the device according to the invention the evaporation surface is perforated. It hereby becomes possible to also blow a part of the airflow or the full airflow through the evaporation surface. Evaporation of the moisture is hereby stimulated even further.

In yet another embodiment of the device according to the invention, the longitudinal axis of the at least one conveyor belt extends substantially vertically relative to the mixture surface. It is moreover possible hereby to place a number of conveyor belts adjacently of each other and thus obtain a very large evaporation surface.

Yet another embodiment of the device according to the invention comprises discharge means for discharging dried mixture out of the storage tank. These discharge means can comprise a pump.

In a preferred embodiment of the device according to the invention, control means can further be arranged for periodic or continuous wetting of the evaporation surface. In the case of conveyor belts the control means can drive these conveyor belts such that the conveyor belts run continuously or periodically. This control can take place in combination with measurements by sensors, for instance sensors which can measure the moisture content of the mixture arranged on the evaporation surfaces, the air humidity, the air temperature, the air flow rate and/or the weight of the arranged mixture.

On the basis of these measurements the wetting can for instance then take place more frequently or less frequently.

The dryer according to the invention can be very readily used with a further dryer. The mixture dried with the dryer according to the invention can be further dried very well with a further dryer. The usual fluctuations in the effectiveness of the further dryer are hereby prevented.

These and other features of the invention are

further elucidated with reference to the annexed drawings.

Figure 1 shows a front view of a device according to the invention.

Figure 2 shows the device of figure 1 in side view.

Figure 3 shows the device of figure 1 in top view.

Figure 4 shows a second embodiment of the invention.

In figure 1 the device 1 is arranged schematically in a space 2. Device 1 has a frame 3 with a storage tank 4 at the bottom. The mixture for drying is arranged in this storage tank 4.

On the upper part of frame 3 are arranged shafts 5 having thereon a number of reversing rollers 6. Arranged over these reversing rollers 6 is a belt 7 which hangs down into storage tank 4. Shaft 5 is driven by a motor 8. In the bottom of cloth 7 is arranged a roller 9 which ensures that the cloth hangs tautly and in the mixture in storage tank 4.

The device 1 is shown in side view in figure 2.

Clearly shown here is that the various conveyor belts 7 are disposed vertically and all hang with a part in storage tank 4.

Figure 3 shows a top view of device 1 according to the invention. The various shafts 5 are driven by means of a single motor 8 and are mutually connected by means of for instance chain wheels. In order to dry the mixture arranged on conveyor belts 7, air L can for instance be blown in between the conveyor belts from the side, which air flows through the preferably perforated conveyor belts and then flows away. The air from an animal living quarters can for instance be used as dry air. This air is already heated, whereby it is able to absorb more moisture.

Figure 4 shows a second embodiment of a device 10 according to the invention. Device 10 has a vertically

disposed conveyor belt 11 with two reversing wheels 12. At the bottom of conveyor belt 11 sprayers 13 are arranged on either side which spray a mixture from a storage tank 14 onto conveyor belt 11. The mixture on conveyor belt 11 is then dried by an airflow.

A drip-tray 15 is further provided under conveyor belt 11 which collects excess sprayed mixture.

A scraper (not shown) can further be arranged to scrape dried mixture from conveyor belt 11.

An optionally perforated flat plate or rotating drum for instance can of course also be used as evaporation surface as well as a conveyor belt.

Substances present in the mixture for drying can settle in the storage tank. In order to prevent problems with pumping the dried mixture out of the storage tank, the slurry is preferably pumped out of the storage tank at the same location as where the mixture for drying is carried into the storage tank. the content of the storage tank can optionally be pumped round and thus homogenized.