Usage application of a machine for recycling gypsum plaster board

Usage application of a per se known in the art continuous-operation machine or the recycling of gypsum plaster board. A coarsely pre-pulverized material is introduced into a continuous-operation machine and, within the continuous-operation machine, the waste material 20 is guided along a product-cycle in a spiral-shaped fashion through the container 4 The tools 18, 18', 18", 18'", which are arranged along an axial length on the shaft 7, rotate in a Froude number region Fr.gtoreq.7 and break-up the pre-pulverized waste material 20 to a sufficient extent that a grain spectrum is produced which effectively facilitates the use of calcination devices.

BACKGROUND OF THE INVENTION 
The invention concerns a usage application of a continuous-operation 
machine, consisting essentially of a horizontally positioned cylindrical 
container having a product feed chute and a product exit chute, a 
driveable shaft in the container, preferentially mounted to front walls, 
tools mounted on the shaft, which are directed radially outward from the 
shaft, whereby the shaft is operated in the Froude number region 
FR.gtoreq.7. 
A continuous-operation machine of this type has become known through the 
brochure "Befeuchtungsmischer" (wetting-mixer) WD 12.79 SM/Rd-e 47.1500 
Gebruder Lodige Maschinenbau GmbH, Paderborn, Germany, 1979. 
The known rapid continuous-operation and compact machine is designed for 
large through-put. It processes, as is known in the art, powdered and 
short-fibered material with liquid media and is utilized in the area of 
solid-liquid mixing. The known machine is distinguished, on the one hand, 
by a good mixing precision at short dwell times and large through-put 
capacities are possible with small machine dimensions. 
The tools mounted onto the shaft rotate in a Froude number range of 7-20, 
whereby the Froude number is formed from the quotient of the revolution 
frequency n and the critical revolution frequency n.sub.c. 
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In this revolution frequency range the product flowing into the machine is 
subjected to centrifugal forces by the tools which press the product 
against the inner wall of the container. The product passes through the 
machine in a product-cycle. In this fashion, the known mixing processes 
occur. 
When manufacturing gypsum plaster board, a certain amount of unmarketable 
waste always occurs which consists essentially of damaged board or board 
which is not to specifications. The waste occurs partially directly 
following binding or sealing, and partially after drying of the bound 
boards. In the first case the waste comprises 30 to 40% moisture and in 
the second case the waste material is practically completely dry. The 
amount of waste material depends on the particular manufacturing procedure 
and differs; this amount lies in general between 2 and 8% of the product 
bulk and reaches, in extreme cases, even 10%. 
In practice the re-introduction of this waste as a secondary raw material 
back into the production process is known in the art. Towards this end one 
had initially coarsely pulverized the boards. This pre-pulverized material 
is a mixture between gypsum chips and cardboard shreds assuming sizes up 
to the size of a hand on which gypsum residue is firmly bonded. With the 
gypsum plaster boards which are most often used having an areal weight of 
approximately 8 kilograms per m.sup.2, the fraction of paper is between 
4.5 to 5%, and with boards having an areal weight of approximately 11 
kilograms per m.sup.2, from 3.4 to 3.8%. A practically acceptable 
separation of the paper and the gypsum, for example by sorting, has, up to 
this point, not been successfully implemented in technical production. 
The coarse pre-pulverized material cannot be processed in the conventional 
calcination devices. The paper shreds would, in for example an indirectly 
heated rotating pipe calcination device, float upon the gypsum grain bed 
to form balls which cannot be properly withdrawn and which, therefore, can 
clog the calcination device. There is also the risk that, when emptying 
the calcination device, dried paper remains in the calcination device 
which, when repowering up, causes an explosion. 
One had also introduced the coarsely pre-pulverized material together with 
fresh natural gypsum into a mill. The up to 30 mm large natural gypsum 
chips effect, in advantageous cases, a certain further pulverization of 
the shredded paper which, however, is not always sufficient. If small 
grain flue-gas gypsum or chemical gypsum is utilized as a raw material a 
satisfactory further pulverization is not possible. The procedure has, 
therefore, not been practically successful. 
SUMMARY OF THE INVENTION 
In accordance with the invention, the known continuous-operation machine is 
utilized, following coarse pre-pulverization, for the processing of waste 
material coming from the production of gypsum plaster board. 
The waste material flowing into the machine with the usage application in 
accordance with the invention is already pressed into a product-cycle path 
in the entrance region. The waste material is, by means of the tools, 
processed in a spirally running product motion in the product-cycle in a 
surprisingly more uniform and more effective fashion than achieved in the 
mills utilized up to this point and, at the same time, is thereby 
homogenized. 
By processed it is meant that the paper shreds are ground down to as small 
an extent as possible and that the remaining waste material is reduced to 
primary grain size to as great an extent as possible. At the product exit, 
the processed material manifests a grain spectrum which is particularly 
well suited for further processing in known calcination devices. The 
efficiency and the operational reliability of the subsequent processing 
steps is, in this fashion, significantly increased. Furthermore, the 
materials processed in accordance with the inventive usage application are 
also particularly well suited for mixing with fine raw gypsum. 
With the inventive usage application it is also possible for fluids to be 
brought into the product cycle. This is particularly advantageous when the 
degree of moisture desired for the processing operation has not yet been 
achieved and/or when a particular granularity or agglomerate formation is 
necessary. 
In addition, a return region comprising spatially fixed baffle walls and/or 
baffle rods, which are also useful for adding fluids, can be established 
in the processing volume which, together with the rotating tools, can 
effect an additional shearing of the product. 
In accordance with the inventive usage application, the mean dwell time of 
the waste material in the container is very short. That is to say, a mean 
dwell time of 15 seconds to 150 seconds is sufficient to break-up the 
plate-sized coarse pulverized pieces of gypsum plaster board to a 
sufficient extent that individual particle sizes are achieved, which can 
be further processed without difficulty in a direct or indirectly heated 
calcination device. 
If, in accordance with particular manufacturing conditions, it not be 
possible to achieve the desired grain size spectrum in one machine at the 
output of the machine, an additional machine can be positioned in series 
in accordance with the inventive usage application; in this machine, if 
required, additional dried material can also be mixed in while further 
breaking-up processing is carried out. 
If the waste material to be processed is too moist, it is possible for the 
shaft and/or the tools to be heated. If, frictional heat must, in 
addition, be removed from the machine, it is also possible to cool the 
shafts or the tools. In the utilized machines, the tools are screwed into 
shafts so that the free end of the tools, by screwing to a greater or 
lesser extent into the tool shaft, can be separated to a greater or lesser 
extent from the inner wall of the container in a simple fashion. 
It is furthermore advantageous to so configure the cylindrical container 
that it consists of two half shells which are pivotable with respect to 
each other. This allows a simple access and the tools, according to the 
requirements, can be rapidly exchanged. 
As can be derived from German patent application P 41 24 984.4, the machine 
in accordance with the inventive usage application can also be combined 
with a plough-blade mixer which, on the one hand, provides additional 
breaking-up action and, on the other hand, homogeneously mixes the 
materials to be processed by the procedure so that they can subsequently 
be introduced into a calcination device without any difficulty. 
It is also particularly advantageous when the pre-pulverization of the 
defective gypsum plaster board is already untertaken in the entrance 
region of the machine. With this configuration of differently functioning 
mechanisms, it is possible to achieve compact assembly units. 
With the machine in accordance with the inventive usage application, it is 
also possible, in contrast to the teaching in accordance with P 41 24 
984.4, to satisfactorally carry out the reprocessing of defective gypsum 
plaster board without using cutter heads. 
Further advantages can be derived from the description and the accompanying 
drawing. Likewise the above-mentioned features as well as those which will 
be additionally explained below in accordance with the invention can each 
be utilized individually or collectively in arbitrary combinations. The 
embodiments mentioned are not to be taken as exclusive enumeration but 
rather have exemplary character only.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In FIG. 1, 1 is an overall view of a machine utilized in accordance with 
the inventive usage application. Arrow 2 indicates the product flow as it 
passes through machine 1. Arrow 3 is the product flow for the 
homogeneously broken-up waste material of the gypsum plaster board when 
flowing out of the machine 1 in the processed state. The waste material 
passes through a container 4 along a spiral-shaped path. The product to be 
processed is passed through machine 1 in a product-cycle and is pressed 
tightly onto the inner wall of the container. The container 4 consists of 
a first half-shell 5 and a second half-shell 6. The half-shells 5, 6 are 
connected to each other in such a fashion that they can be pivoted with 
respect to each other. Container 4 has a shaft 7 which is preferentially 
mounted via front walls 8, 9. In the FIG. 7 indicates the shaft and 10 
indicates the bearing. The shaft 7 itself is driveable; the driving 
mechanisms suitable therefor are not shown in FIG. 1. Hand-screws 11 are 
provided for on the first and second half-shells 5, 6 by means of which 
the half-shells 5, 6 can be held together in a product-tight fashion. A 
product feed chute 12 is configured on the first half-shell 5 and a 
product exit chute 13 is provided for on the second half-shell 6. In the 
figure, the container 4 is provided with a jacket 14 by means of which the 
container 4 can be heated or cooled. Media such as water vapor, gases of 
various kinds and oil are suitable for heating or cooling. A directed 
temperature adjustment can be used to control deposit formation within 
container 4. In the figure, feed connectors 15 and exit connectors 16 are 
represented for the media. By means of mountings 17 it is possible to 
introduce fluids into the product-cycle. The mountings 17, in particular 
pipes, can also function as baffle-rods to define a return zone. The pipes 
can exhibit cross sections of arbitrary polygonal shape. In the return 
zone, the material being processed can be subjected to additional shearing 
forces. Semicircular shaped plate-segment baffle walls can replace the 
baffle rods. 
Pulverizing instruments with individual drive mechanisms can be provided 
for in the product feed chute 12 which can undertake a coarse 
pulverization of the waste material. 
FIG. 2 shows the cut II--II of FIG. 1. Further features of the machine 
which are still visible in the background of the cut II--II such as hand 
screws 11, mountings 17 and the product feed chute 12 are not represented 
in the figure for reasons of clarity. The same objects are given the same 
reference symbols in the figures. 
The sectional cut shows the shaft 7 with mounted tools 18, 18', 18" and 
18'". The tools 18, 18', 18", and 18'" consist of a shaft, into which the 
free cone-shaped ends of these tools are screwed. By means of the screw, 
it is possible to easily adjust the separation of the free ends of the 
tools 18, 18', 18", 18'" relative to the inner wall of the vessel. The 
shaft 7 rotates in the direction of the arrow 19 along with tools 18, 18', 
18" and 18'". 
Due to the rotational speed of the tools 18, 18', 18" and 18'", the waste 
material 20 is guided through the vessel 4 in a spiral-shaped fashion in 
the product-cycle. The product is thereby processed to such an extent that 
a grain spectrum is achieved whose grain size allows for its use in the 
above mentioned calcination devices, without difficulty. The waste 
material 20 is indicated by dots in FIG. 2. 
The half shells 5, 6 exhibit a jacket 14 by means of which the container 4 
can be heated or cooled. The shaft 7, represented in FIG. 2 as a solid 
shaft, can also be configured as a hollow shaft by means of which heating 
or cooling media can be introduced to the tools 18, 18', 18" and 18'". The 
tools 18, 18', 18" and 18'" are distributed in the axial direction along 
the entire shaft 7. The first half-shell 5 is pivotable with respect to 
the spacially fixed second half-shell 6. Arrows 19' and 19" indicate the 
pivot direction. The pivot bearing on the one side of the container 4, the 
closing mechanism on the other side, and the hand screws 11, are not shown 
in the figure. 
FIG. 3 shows a machine configuration 25, by way of example, as it can be 
utilized in the inventive usage application. A first machine 26, described 
in accordance with the inventive usage application, and a second machine 
27 are connected in series with a plough-blade mixer 28 which is per se 
known in the art. The waste material to be processed flows in the 
direction of arrows 29, 29', 29", 29'" through the machine configuration 
25. The individual machines 26, 27 and the plough-blade mixer 28 are 
driven by symbolically represented drive mechanisms 30, 30', 30". 
Additional pulverizing tools can be provided for in the product feed chute 
31 which are not shown in the figure and the processed waste material is 
fed into a calcination device, which is per se known in the art, via 
product exit chute 32. The machine configuration 25 shown in the figure 
can also have additional machines attached thereto according to need. 
Usage application of a per se known in the art continuous-operation machine 
for the recycling of gypsum plaster board. A coarsely pre-pulverized 
material is introduced into a continuous-operation machine and, within the 
continuous-operation machine, the waste material 20 is guided along a 
product-cycle in a spiral-shaped fashion through the container 4 The tools 
18, 18', 18", 18'", which are arranged along an axial length on the shaft 
7, rotate in a Froude number region Fr.gtoreq.7 and break-up the 
pre-pulverized waste material 20 to a sufficient extent that a grain 
spectrum is produced which effectively facilitates the use of calcination 
devices.