Method and apparatus for separation and volume measurement of components for lightweight concrete

A method and apparatus to simplify the measurement of lightweight concrete components and to recycle waste materials that result from lightweight concrete block manufacture. The method involves separating coarse and fine components of the waste. The apparatus uses several devices, separately or in combination, to separate the components, such as a sieve, auger, and blower. The coarse components are conveyed by auger, gravity or other means to be measured by weight in a first hopper. The fine components are conveyed by gravity, blower, auger or other means to be measured by volume in a second hopper. Fresh materials may be added to both hoppers. The materials from both hoppers are then mixed together in a primary mixing chamber and finally conveyed into molds for curing before use.

BACKGROUND OF THE INVENTION 
This invention relates generally to cement mixing, and more particularly to 
separating, measuring and mixing an admixture of components for 
lightweight cement. Recycled lightweight concrete waste materials may 
hereby be recycled. This method and apparatus is an improvement of the 
existing process described in my U.S. Pat. No. 4,895,450, incorporated 
herein by reference. 
Lightweight concrete consists mainly of cement, water, and an admixture of 
lightweight filler, the filler comprising such materials as polystyrene, 
crushed pumice, and perlite. Lightweight concrete blocks are formed from 
this cementious mixture by pouring the mixture into block forms, allowing 
the cement to cure, and cutting the blocks to the desired shape. Waste 
material is created when the blocks are cut, the waste comprising hydrated 
cement dust, lightweight filler, and concrete lumps. Because the residual 
cement has already been hydrated, the waste materials will no longer bind 
without additional binders. The waste material may be recycled, however, 
by adding it to a fresh mixture of lightweight cement, which will bind 
with the waste material. 
The prior art process is described in detail in U.S. Pat. No. 4,895,450, 
hereinafter the '450 patent. That process greatly simplified the measuring 
of the various ingredients by providing two different chambers into which 
the ingredients are placed. In a first hopper, filler material contained 
in hydrated cement and fresh filler material are measured by volume, and 
the hydrated cement is measured by weight. In a second hopper, water and 
cement are measured by weight. 
Before recycling residual lightweight concrete, it is necessary to separate 
the components of the waste materials. This involves separating the dust 
and lightweight filler from the heavier concrete lumps. Furthermore, 
lightweight filler particles that have adhered to the concrete lumps 
should be removed. Because the ratios of cement, water, and lightweight 
filler must be kept within narrow tolerances, all the components must be 
measured separately. This further complicates the process of making 
lightweight cement. 
Therefore, it is an object of this invention to provide a method and 
apparatus to use recycled lightweight concrete waste materials to produce 
lightweight concrete. It is a further object to provide a method and 
apparatus to separate and measure the waste materials. It is another 
object of this invention to simplify making lightweight cement blocks by 
providing a method and apparatus that separates ingredients into a first 
hopper for weighing materials and a second hopper for volume measuring 
materials. 
BRIEF SUMMARY OF THE INVENTION 
This invention is a method and apparatus to simplify the measurement of 
lightweight concrete components and to recycle waste materials that result 
from lightweight concrete block manufacture. The method involves 
separating coarse and fine components of the waste. The apparatus uses 
several devices, separately or in combination, to separate the components, 
such as a sieve, auger, and blower. The coarse components are conveyed by 
auger, gravity or other means to be measured by weight in a first hopper. 
The fine components are conveyed by gravity, blower, auger or other means 
to be measured by volume in a second hopper. Fresh materials may be added 
to both hoppers. The materials from both hoppers are then mixed together 
in a primary mixing chamber and finally conveyed into molds for curing 
before use.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Please refer to the accompanying FIGS. 1-5 where like numerals refer to 
like parts throughout the drawings. Lightweight concrete waste materials 
are best separated into two components: coarse particles comprising, in 
major part, filler material, and fine particles comprising, in major part, 
cement dust. Coarse particles may also be an aggregate of filler material 
adhered to cement lumps. The filler material may be broken apart from the 
cement lumps by use of a crushing device, such as an auger with a 
specialized crushing blade. FIGS. 3 and 4 illustrate this alternative 
blade in which small pieces of metal are attached to the edges of the 
screw, positioned in an angle towards the direction of the material flow. 
By this design, the lightweight filler material beads are wedged and more 
friction is applied to them during the travel along the auger and over the 
sieve. Alternatively, the recycled material may be crushed prior to being 
fed into the receiving means by a jaw crusher, roller crusher, ball mill 
or the like. 
FIG. 1 illustrates the prior art. FIG. 2 is a schematic illustration of the 
apparatus of the present invention, including a separating means 10, a 
first mixing chamber or hopper 11, a second mixing chamber or hopper 12, 
and a primary mixing chamber or hopper 13. The output from both the first 
hopper 11 and the second hopper 12 flow into the primary mixing chamber 
13. 
Recycled lightweight concrete waste materials are fed into the separating 
means through a conduit, bin 14 or the like. The separating means 
comprises means for separating the waste materials into coarse and fine 
components, means for conveying the coarse materials to the first hopper, 
and means for conveying the fine materials into the second hopper. 
In the preferred embodiment as shown in FIG. 2, the waste materials are 
conveyed by augers 21, 22 into the first hopper 11 and second hopper 12, 
respectively. Alternatively, a simple conveyor or other means may be 
employed. The materials are conveyed over a screen or sieve 23 of desired 
mesh size to be separated into various sizes of particles. For separation 
of more than two sizes of particles multiple sieves may be used. To 
facilitate separation, a vibrating sieve may be used. 
Coarse material is conveyed to the first hopper 11 through a conduit 24. 
Conveyance may be achieved by auger, belt or, because the coarse material 
is lightweight filler material, by blowing the particles through a conduit 
into the first hopper. In order to have flexibility in using the recycled 
materials, there may be a container between the separator and the first 
hopper to buffer a certain amount of the filler (not shown). Coarse 
material is added to the first hopper 11 through an input spout 25. 
The first hopper has a second input spout 26 through which new filler 
material may added to the hopper, if desired. A level sensor 16 or other 
means for measuring the volume of the materials in the first hopper is 
disposed in the first hopper. The level sensor 16 may be connected to a 
level adjustment drive 17, thus making is possible to predetermine a 
certain volume. An output conduit 18 is connected near the lower portion 
of the first hopper to an input conduit 19 of the primary mixing chamber. 
Fine material is conveyed to the second hopper through a conduit. 
Conveyance may be achieved by auger, belt or gravity. In order to have 
flexibility in using the recycled materials, there may be a container 
between the separator and the second hopper to buffer a certain amount of 
the fine material (not shown). Fine material is added to the second hopper 
12 through an input spout 45. 
The second hopper has an additional input spout 46. Both water and cement 
flow into the second hopper and chamber through the input spout 46. 
Alternatively, water may be filled by means of a nozzle arrangement inside 
the second hopper through a water connection 41. A mixer 48 is disposed in 
the second hopper for mixing the water and cement. A scale 50, weight 
cell, or other weighing means is connected to the second hopper to weigh 
the materials in the hopper, namely water, cement and fine recycled 
material. An output conduit 49 is connected near the lower portion of the 
second hopper 12 to an input conduit 59 of the primary mixing chamber. 
FIG. 5 illustrates an alternative embodiment of separation apparatus. The 
upper auger 51 conveys coarse material into a pipe 52 running at angle, 
preferably perpendicular, to the screw. FIG. 5 shows pipe 52 in 
cross-section, at a right angle to the screw and parallel to the ground. 
An air stream from a blower picks up the lightweight filler material and 
conveys it to the first hopper 11. An opening 53 in the pipe allows heavy 
lumps to drop by gravity out of the conduit, thereby preventing unwanted 
heavy aggregates of cement and filler from being recycled. FIG. 5 shows 
the opening in the elbow where pipe 52 meets the screw. Fine material is 
conveyed to the second hopper 12 by an auger 22 and conduit 44. 
The output from the first and second hoppers flows into the primary mixing 
chamber 13 and is mixed. Additives such as foaming agents, bonding agents 
and the like may be added to the primary chamber input conduit 80. 
The objects of this invention are achieved through the aforementioned 
improvements. Although certain preferred embodiments have been shown and 
described, it should be understood that other embodiments and 
modifications that achieve these objects may be apparent to those of skill 
in the art and are within the scope of the appended claims.