METHOD FOR MANUFACTURING FERTILIZER FROM TREE BARK

METHODE DE CONVERSION DE L'ECORCE D'ARBRES EN ENGRAIS

English Abstract

ABSTRACT OF THE DISCLOSURE
In a method for treating tree bark with molasses to render it
suitable for use as fertilizer, the improvement which comprises reducing
the pH value of the molasses to 3.5 and then passing the mixture of bark
and molasses through a rotating and pressurized oven.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:-




1. A method for manufacturing fertilizer from tree
bark refuse comprising supplying crushed tree bark refuse to
a mixing apparatus, supplying molasses refuse, the pH of which
has been lowered to approximately 3.5, to said mixing apparatus,
mixing the molasses refuse with said bark refuse, transporting
said mixture of bark and molasses in a continuous flow through
a rotating and pressurized oven wherein said mixture is heated
and whereby toxic substances are extracted from the tree bark
and the nutrients contained in the tree bark become soluble
and thus usable by plants.



2. A method as claimed in claim 1, wherein the mixture
of bark and molasses is transported through two of said ovens
in parallel arrangement.



3. A method as claimed in claim 1 or 2, wherein the
heated mixture is passed through at least one cooling device
and is finally deposited on a cooling conveyor.



4. A method according to claim 1 wherein said molasses
refuse is supplied by a sugar processing plant.


5. A method according to claim 1 or 4 wherein said
toxic substances extracted include bark acids.

6. A method according to claim 1, 2, or 4 wherein said
mixing apparatus comprises screw conveyor means which transport
the mixture into said oven.

Description

864


Tree bark has been used as a fuel and as ~ ~ertilizer.
For the latter purpose, tree bark has among other things been
composted using bacteria as an aid in decomposing the tree bark
over the period of a few months. However, the loss of nitrogen
in this process makes the end result unsuitable as fertilizer.
About ten years ago a method was invented, see Finnish patent
No. 44,124, in which the toxic substances contained in the tree
bark could be extracted, and where nitrogen and other mineral
nutrients were not lost. Bark refuse processed by this method
is very suitable as fertilizer. By the method in question,
crushed tree bark refuse i8 cooked for some time with molasses
refuse from the sugar industxy.
The nutrients contained in the lignin then become soluble
to such an extent that they can be used by plants. However,
a flaw in this method is that, due to the cooking process con-
tained in it, it is not suitable for continuous production,
and also, a more complete dislntegration of the nutrients con-
tained in the lignln would be apt to further improve the possi-
bilities of the plants to make use of these same nutrients.
The present invention consists of a meth~d for manufac-
turing fertilizer from tree bark refuse comprising supplying
crushed tree bark refuse to a mixing apparatus supplying molasses
refuse, the pH of which has been lowered to approximately 3.5,
to the mixing apparatus, mixing the molasses refuse with the
bar~ refuse, transporting the mixture of bark and molasses
in a continuous flow through a rotating and pressurized oven
wherein the mixture is heated and whereby toxic substances are
extracted from the tree bark and the nutrients contained in
the tree bark become soluble and thus usable by plants.
A better disintegration of the lignin than before is

B

86g

obtained by lowering the pH-value of the molasses to said value
of 3.5 , at which the pressure and the heat break it down extreme-
ly well.
A preferred embodiment of the invention will now be
described, by way of example, with reference to the accompanying
flow chart. Tree bark refuse is fed from the storage silo 1
into the hammer mill 2 and then to the dosing mill 3. On the
belt conveyor 4 molasses are added, the pH content of which
has been lowered in equipment 5 to approximately the value




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~1iI864

of 3.5. There are two rotating and pressurized ovens 7, into which the
screw conveyors 6 feed the compound, so that cleaning of the ovens does
not cause any breaks in production. The ingress and egress of the compound
to and from the ovens is aided by suction, pipes for which are marked 8.
After the ovens the compound is carried by the screw conveyor 9 to the
cooling devices 10, of which there are two, and lastly it is carried by the
cooling conveyor 11, which is a belt conveyor. The method may of course
be carried out in other ways than by using the equipment described above,
which, however, has proved itself to be very practical.