U.S. patent application number 11/845591 was filed with the patent office on 2018-04-12 for hybrid composite hydroponic substrate system.
The applicant listed for this patent is W. Gene Ramsey, Andrew Ungerleider. Invention is credited to W. Gene Ramsey, Andrew Ungerleider.
Application Number | 20180099891 11/845591 |
Document ID | / |
Family ID | 40388112 |
Filed Date | 2018-04-12 |
United States Patent
Application |
20180099891 |
Kind Code |
A9 |
Ramsey; W. Gene ; et
al. |
April 12, 2018 |
HYBRID COMPOSITE HYDROPONIC SUBSTRATE SYSTEM
Abstract
A porous glass plant growth support structure, including a
porous glass substrate and a plurality of interconnected pores
distributed throughout the substrate. The substrate is typically
formed from foamed glass and/or fused glass spheres and is
characterized by a porosity of at least about 80 percent. The pore
size is substantially between about 0.2 and about 5 millimeters and
the substrate is sufficiently chemically stable such that water
filling the plurality of interconnected pores experiences a pH
shift of less than 0.5.
Inventors: |
Ramsey; W. Gene; (Las
Cruces, NM) ; Ungerleider; Andrew; (Santa Fe,
NM) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ramsey; W. Gene
Ungerleider; Andrew |
Las Cruces
Santa Fe |
NM
NM |
US
US |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20090056221 A1 |
March 5, 2009 |
|
|
Family ID: |
40388112 |
Appl. No.: |
11/845591 |
Filed: |
August 27, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11776995 |
Jul 12, 2007 |
|
|
|
11845591 |
|
|
|
|
11276027 |
Feb 10, 2006 |
7739833 |
|
|
11776995 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A01G 31/00 20130101;
C03C 11/00 20130101; C03B 19/08 20130101; A01G 24/00 20180201; A01G
24/48 20180201 |
International
Class: |
C03B 19/08 20060101
C03B019/08; C03C 11/00 20060101 C03C011/00; A01G 31/00 20060101
A01G031/00 |
Claims
1. A method of growing plants, comprising the steps of: a)
providing a plurality of chemically stable porous glass pellets
defining a substrate, each respective pellet characterized by a
plurality of interconnected pores distributed throughout the
pellet; b) at least partially filling the plurality of
interconnected pores with a nutrient fluid; and c) at least
partially infiltrating the plurality of interconnected pores with
roots; wherein the substrate is characterized by a porosity of at
least about 80 percent.
2. The method of claim 1 wherein the substrate is sufficiently
chemically stable such that water filling the plurality of
interconnected pores experiences a pH shift of less than 0.5.
3. The method of claim 1 wherein the substrate is filled with
between about 3 and about 4 times its own weight in water in the
plurality of interconnected pores.
4. The method of claim 1 wherein the pore size is substantially
between about 0.5 and about 5 millimeters.
5. The method of claim 1 wherein the substrate includes about 2
weight percent plant growth nutrients incorporated therein.
6. The method of claim 1 wherein the substrate is at least
partially composed of glass spheres.
7. The method of claim 1 wherein the glass spheres are agglomerated
and fused together to define a substantially porous substantially
vitreous body.
8. The method of claim 1 wherein the substrate is at least
partially composed of fibrous organic material.
9. The method of claim 8 wherein the substrate is at least
partially composed of coconut cuir.
10. The method of claim 1 and further comprising: d) providing a
porous substrate member substantially covering the plurality of
chemically stable porous foamed glass pellets.
11. The method of claim 10 wherein the substrate member is a foamed
glass slab characterized by about 80 percent open porosity and
characterized by a typical pore size generally between about 0.5
and about 5 millimeters.
12. The method of claim 11 wherein the plurality of chemically
stable porous foamed glass pellets defines a bottom layer, wherein
the foamed glass slab defines a top layer, wherein roots grow
through the porous top layer and into the interconnected pores of
the bottom layer.
13. The method of claim 10 wherein the porous substrate member is
formed from a material selected from the group comprising foamed
glass, glass spheres, coconut cuir, rockwool, polymer spheres,
metal spheres, and combinations thereof.
14. A method of nourishing and anchoring roots, comprising the
steps of: a) positioning a plurality of chemically stable porous
pellets, each respective pellet characterized by a plurality of
interconnected pores distributed throughout the pellet to define a
bottom layer; b) covering the bottom layer of chemically stable
porous pellets with a unitary slab characterized by interconnected
open porosity and defining a top layer; c) at least partially
filling the plurality of interconnected pores with a nutrient
fluid; and d) at least partially infiltrating the plurality of
interconnected pores with roots.
15. The method of claim 14 wherein the unitary slab is foamed
glass.
16. The method of claim 14 wherein the plurality of interconnected
pores are generally sized between about 0.5 and about 5 millimeters
and wherein the unitary slab is characterized by an open porosity
of between abut 0.5 and about 5 millimeters.
17. The method of claim 14 wherein the unitary slab and
substantially each respective pellet may hold at least about 3
times its respective weight in water.
18. The method of claim 14 wherein the chemically stable porous
pellets are formed from a material selected from the group
comprising foamed glass, glass spheres, coconut cuir, rockwool,
polymer spheres, metal spheres, and combinations thereof.
19. A method of nourishing and anchoring roots, comprising the
steps of: a) positioning a plurality of chemically stable porous
glass pellets, to define a first layer; b) positioning a unitary
porous foamed glass slab adjacent the a first layer to define a
second layer; c) at least partially infiltrating the first and
second layers with a nutrient fluid; and d) at least partially
infiltrating the plurality of interconnected pores with roots;
wherein the respective first and second layers hold at least about
3 times their respective weights in water; and wherein the
respective first and second layers are characterized by open,
interconnected pores sized to allow passage of plant roots
therethrough.
20. The method of claim 19 wherein the first and second layers are
sufficiently chemically stable such that water filling infiltrating
a respective layer experiences a pH shift of less than 0.5.
21. The method of claim 19 wherein at least one layer includes
plant growth nutrients adsorbed onto pore surfaces.
22. The method of claim 19 wherein at least one layer includes
about herbicide adsorbed onto pore surfaces.
23. The method of claim 19 wherein at least one layer includes
pesticide adsorbed onto pore surfaces.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a utility application claiming
priority to, and based upon, co-pending U.S. patent application
Ser. No. 11/276,027, filed Feb. 10, 2006.
TECHNICAL FIELD
[0002] The novel technology relates generally to the field of
ceramic materials and, specifically, to a substrate system having a
solid layer of porous foamed vitreous material overlaying a loosely
packed aggregate layer of porous foamed vitreous material for water
storage and root propagation.
BACKGROUND
[0003] Hydroponics is the science of growing plants in a nutrient
solution with the mechanical support of an inert medium.
Hydroponics is an old art, and a variety of inert media are known
as suitable for the germination, rooting and growth of plants. Such
substrates include peat, vermiculite, perlite, fly ash, pumice,
rock wool, glass wool, organic and inorganic fibers, polymers such
as polyurethane, polystyrene, polyethylene, and the like. These
substrates have been used for true hydroponics or in
quasi-hydroponic environments such as in admixtures with soil.
Typically, the inert medium is either in the form of a contained
loose particulate, such as sand, or as a rigid and self-supporting
structure that can support growth of the plant. The rigid structure
has some notable advantages over the loose particulates, in
particular the ability to stand alone without a requisite
container. However, the loose particulate media tend to offer
better pathways for water and gasses to be delivered to and from
the root systems.
[0004] One problem common to hydroponic gardening is overwatering.
Hydroponic techniques lend themselves to the provision of excessive
water to the plant root system, which may result in chlorosis,
retarded growth, pallor, and, eventually death. In such situations,
the water around the roots becomes stagnant and gasses dissolved
therein are only urged to and from the roots through diffusion.
Moreover, vital gasses quickly become depleted and waste gasses
saturated in the water proximate the roots, exacerbating the
situation. Thus, it is desired to reduce the stagnant water around
the roots by circulating the water.
[0005] Most of the substrates currently known are solids with
limited porosity. Some known substrates have attempted to add or
increase the porosity of the substrate in order to better provide
for gas exchange to the roots. One such substrate has been produced
in the form of a sponge-like or foraminous foamed polymer body with
conduits 1-5 millimeter in nominal diameter, spaced about 1-8 mm
apart and extending throughout the substrate. The conduits drain
water from the substrate and provide reservoirs of oxygen for the
plant roots and at the same time allow substrate to hold some water
that may then be available to the roots. The porosity of this
substrate ranges from between 6 and 53 percent. Soil or the like is
deposited on top of the substrate and a seed, cutting or small
plant is placed in the soil. With the substrate under the soil
layer, over-watering induced problems are prevented, as excess
water drains from the substrate, filling the conduits with air and
oxygen will be readily available to the roots.
[0006] Similarly to hydroponic agriculture, soil amendment is a
common practice for growing plants in places where adequate amounts
of fertile soil are unavailable. In soil amendment, media similar
to those discussed above are added to soils (especially in
greenhouse applications) to improve water retention and aeration
around the root bed. Water is used as a means to deliver nutrition
and oxygen--soil amendments that increase the effective soil
porosity and water retention potential are vital for plant life and
growth rate.
[0007] While useful in hydroponic and soil amendment applications,
the above substrates are still hampered by a lower than optimal
porosity and low capacity for water infiltration and retention.
Thus, there remains a need for a highly porous substrate for
supporting plant growth. There also remains a need for improves the
aeration of soil and allows for better water filtration and
irrigation. The present novel technology addresses these needs.
SUMMARY OF THE NOVEL TECHNOLOGY
[0008] The present novel technology relates to a layered foamed
glass material system for supporting plant growth, and the method
for making the same. One object of the present novel technology is
to provide an improved foamed glass plant support substrate
material. Related objects and advantages of the present novel
technology will be apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1A is a schematic view of a process for mixing a batch
of precursors for a foamed glass article according to a first
embodiment of the present novel technology.
[0010] FIG. 1B is a schematic view of a process for firing a foamed
glass article mixed according to FIG. 1A.
[0011] FIG. 2 is a partial perspective view of roots infiltrating
the porosity of the foamed glass article of FIG. 1B.
[0012] FIG. 3 is a cutaway elevation view of the article of FIG. 2
as partially immersed in water and supporting plant growth.
[0013] FIG. 4 is a plan view of a plurality of crushed foamed glass
pebbles according to a second embodiment of the present novel
technology.
[0014] FIG. 5 is a cutaway elevation view of the article of a
hydroponic system including foamed glass media as shown in FIG. 4
mixed with soil and supporting root growth.
[0015] FIG. 6 is a cutaway elevation view of the article of a
hydroponic system including foamed glass media as shown in FIG. 4
and supporting root growth.
[0016] FIG. 7 is a cutaway elevation view of the article of a
hydroponic system including a foamed glass substrate member over a
layer of foamed glass media as shown in FIG. 4 and supporting root
growth.
[0017] FIG. 8 is an enlarged view of FIG. 7.
[0018] FIG. 9 is a cutaway elevation view of a hydrop[onic system
like that of FIG. 7, except the porous media are formed of
agglomerated glass, metal and/or polymer spheres.
[0019] FIG. 10 is a cutaway view of a porous substrate or pellet
formed of a foamed glass/sphere composite.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] For the purposes of promoting an understanding of the
principles of the novel technology and presenting its currently
understood best mode of operation, reference will now be made to
the embodiments illustrated in the drawings and specific language
will be used to describe the same. It will nevertheless be
understood that no limitation of the scope of the novel technology
is thereby intended, with such alterations and further
modifications in the illustrated device and such further
applications of the principles of the novel technology as
illustrated therein being contemplated as would normally occur to
one skilled in the art to which the novel technology relates.
[0021] FIGS. 1A-4 illustrate a first embodiment of the present
novel technology, a lightweight foamed glass substrate 10
characterized by voluminous, interconnecting pores 15 for
supporting plant growth. As illustrated schematically in FIGS.
1A-B, a powdered glass precursor 20, such as recycled waste glass,
is mixed with a foaming agent 22 (typically a finely ground
non-sulfur based foaming agent, such as calcium carbonate). The
foaming agent is typically sized in the average range of about 80
to minus 325 mesh (i.e. any particles smaller than this will pass
through--typically, the apertures in 80 mesh are between about 150
and about 200 micrometers across and the apertures in -352 mesh are
between about 40 and about 60 micrometers across). More typically,
the foaming agent has a particle size between about 5 and about 150
microns. Additional plant growth nutrient material 24 is also
typically added to the starting mixture to vary or enhance the
plant growth characteristic of the final product 10. Further,
foamed glass, like most ceramics, is naturally hydrophobic. As
hydrophobic surfaces are not conducive to wetting and impede
capillary action, an agent is typically added to amend the surface
properties to make the foamed glass more hydrophilic. Such an agent
may be a large divalent cation contributor, such as ZnO, BaO, SrO
or the like. The hydrophilic agent is typically added in small
amounts, typically less than 1.5 weight percent and more typically
in amounts of about 0.1 weight percent.
[0022] The combination is mixed 26, and the resulting dry mixture
is then placed into a mold 28. Typically, the mixture is placed
into the mold 28 in the form of several rows of the mixture, such
as in mounds or piles of mixture typically having a natural angle
of repose of about 15 to 50 degrees, although even greater angles
to the horizontal can be achieved by compressing the dry mixture.
The mold 28 is typically a refractory material, such as a steel or
ceramic, and is more typically made in the shape of a frustum so as
to facilitate easy release of the final foamed glass substrate 10.
Typically, the inside surfaces of the mold 28 are coated with a
soft refractory release agent to further facilitate separation of
the foam glass substrate from the mold 28.
[0023] The so-loaded mold 28 is placed into a furnace for either a
batch or continuous foaming process, and the mixture is then heated
30 in order to sinter, fuse, soften and foam the mixture and
thereby produce a foamed glass substrate 10 having a desired
density, pore size and hardness. As the powdered mixture is heated
to above the softening point of glass (approximately 1050 degrees
Fahrenheit) the mixture begins to soften, sinter, and shrink. The
division of the powdered mixture into rows or mounds allows the
glass to absorb heat more rapidly and to therefore foam faster by
reducing the ability of the foaming glass to insulate itself. At
approximately 1058 degrees Fahrenheit, the calcium carbonate, if
calcium carbonate has been used as the foaming agent, begins to
react with some of the silicon dioxide in the glass to produce
calcium silicate and carbon dioxide. Carbon dioxide is also formed
by any remaining calcium carbonate once the mixture reaches 1274
degrees Fahrenheit, above which calcium carbonate breaks down into
calcium oxide and carbon dioxide gas. The release of carbon dioxide
and its expansion and escape through the softened, viscous glass is
primarily responsible for the formation of cells and pores in the
softened glass mass. The mixture in the mold 28 is held for a
period of time at a peak foaming temperature of, for example,
between about 1275 and about 1700 degrees Fahrenheit, or even
higher, depending on the properties that are desired. By adjusting
the firing temperatures and times, the density and hardness as well
as other properties of the resultant substrate 10 may be closely
controlled.
[0024] As the furnace reaches foaming temperatures, each mass of
foaming glass, originating from one of the discrete rows or mounds,
foams until it comes into contact and fuses with its neighbors. The
fused mass of foaming glass then expands to conform to the shape of
the walls of the mold, filling all of the corners. The shapes and
sizes of the initial mounds of mixture are determined with the
anticipation that the foaming mixture exactly fill the mold. After
the glass is foamed to the desired density and pore structure, the
temperature of the furnace is rapidly reduced to halt foaming of
the glass. When the exterior of the foamed glass in the mold has
rigidified sufficiently, the resultant body 10 of foamed glass is
removed from the mold 28 and is typically then placed into a lehr
for annealing. The temperature of the lehr is typically slowly
lowered from the softening temperature of the glass to ambient
temperature to anneal the porous block of foamed glass 10. Once
cooled, any skin or crust is typically cut off of the foamed glass
substrate 10, which may then be cut or otherwise formed into a
variety of desired shapes. Pore size can be carefully controlled
within the range of about 5 mm to about 0.5 mm, and is typically
controlled such that the interconnected or open porosity may
readily accommodate a typical plant root 35 (see FIG. 2). Substrate
density can be controlled from about 0.4 g/cc to about 0.15 g/cc.
Typically, the bulk density of the crushed foam may be as low as
50% of the polyhedral density.
[0025] The substrate 10 is typically either formed as either
crushed pebbles 50 (typically sized to be less than 1 inch in
diameter) or machined polyhedral shape (see FIG. 4). The crushed
substrate material 50 may be used to retain water and increase air
volume in given soil combinations. The polyhedrally shaped
substrate bodies 10 are typically sized and shaped as growing media
for seeds and immature plants, such as for use in soil or
hydroponic systems 40 (see FIGS. 3 and 5). The foamed glass
substrate material 10 is thus used to improve aeration and water
retention in agricultural systems, and the porous polyhedral
material 10 also provides a sufficiently spacious path for root
growth and attenuation. The foamed material 10 is typically
resistant to aqueous corrosion and has minimal impact on solution
pH. Typically, the foamed material 10 is doped (in batch stage,
prior to foaming) with specific nutritional species 24 (such as,
but not limited to including P, Mg, Ca, K, and transition metals)
as may be desired by the grower. The foamed glass substrate 10 can
typically hold between about 1.5 and about 5 times its own weight
in water in the plurality of interconnected pores. The foamed glass
substrate 10 is typically chemically stable as formed, but may be
given a pretreatment wash to further increase its chemical
stability.
[0026] Crushed foam bodies 50 may be rapidly made by an alternate
method. Using soda-lime glass frit or powder as the glass component
22, the processing is similar to that described above but without
the annealing step. The alternate method employs the same foaming
temperature ranges as related above. The batch material consists of
up to 8 percent by mass limestone, magnesite, or other applicable
foaming agent 22, usually less than 2 percent by mass nutrients 24
(added as oxides, carbonates, nitrates, or other suitable forms),
with the balance being a borosilicate, silicate, borate or
phosphate glass frit 22. The batch is then placed in a typically
shallow mold 28, more typically having a configuration of less than
2'' batch for every square yard of mold surface. The mold 28 is
typically then heated to approximately 250.degree. C. above the
dilatometric softening point for soda-lime glass (or the equivalent
viscosity for other glass compositions) and allowed to foam. The
mold 28 is held at the foaming temperature for less than 30 minutes
and then pan quenched, i.e. substantially no annealing is allowed
to occur This method yields a material 10 of density typically less
than 0.15 g/cc, and more typically as low as about 0.03 g/cc. This
material 10 is then crushed into pebbles, with a corresponding
lower bulk density as per the above-described method. Material made
by this alternate method has similar chemical properties as
described above, can accommodate an even larger nutrient content,
but has substantially lower strength.
[0027] Still another alternate method of preparing foamed glass
substrate material 10 is as follows. A batch is prepared as
discussed above and pressed into small (typically less than 5 mm
diameter) pellets. The pellets are rapidly heated, such as by
passage through a flame source, passage through a rotary furnace,
or the like. Typically, the pellets are heated to about 1500
degrees Fahrenheit, such as to cause the pellet to expand as a foam
particulate without the need for a mold. This material yields the
weakest, but least dense foam particles. The typical density may be
as low as 0.02 g/cc or as high as 0.2 g/cc.
[0028] The foamed glass substrate 10, either in polyhedral body
form or crushed product form, may serve as a root system support
and an aeration and/or water retention aid. The material 10
typically enjoys a void fraction of at least about 80 percent. The
substrate 10 is typically mechanically mixed with as little as 15%
by volume soil or soil mixture and this new mixture will still
generate solution chemistry dominated by soil.
[0029] The polyhedral product 10 typically functions as a
supporting substrate for both soil based and hydroponic
applications. The polyhedral substrate 10 may be tailored to be
compatible with mildly acidic, neutral, or mildly alkaline solution
pH. The pore network 15 is compatible with root propagation through
the material 10. The pore network typically has surface adhesion or
adsorption properties such that chemical additives 51, such as
plant growth nutrients, herbicides, pesticides or combinations
thereof, may be physically adsorbed thereonto for later release.
Typically, these additives are added in small amounts, such as a
few weight percent (0.5 1, 2, 5, or the like) of the substrate
product 10.
EXAMPLE 1
[0030] A plant growth support substrate 10 having a pore network 15
and plant nutrients embedded therein is produced from a precursor
batch of about 3 weight percent calcium carbonate sized at minus
200 mesh, about 2 weight percent high-potassium nutrient, about 0.1
weight percent ZnO hydrophilic agent, and about 95 weight percent
recycled plate glass ground to minus 140 mesh, 60 to 100 mesh, are
mixed together. The resulting mixture is placed into a stainless
steel mold having inside dimensions of 4.25 inches by 4 inches by
8.25 inches. The mold is covered with a 1/2 inch stainless steel
plate. The mold with the mixture therein is then fired to 1250
degrees Fahrenheit for 60 minutes. The temperature is next ramped
to 1450 degrees Fahrenheit for 30 minutes, where foaming takes
place. The foamed glass in the mold is annealed by cooling slowly
to room temperature over 120 minutes. The cooled block of foamed
glass is removed from the mold, and the outer layer of crust is
removed (such as with a band saw) to expose the open porosity. The
resulting block typically has a density of about 14 pounds per
cubic foot and a pore size distribution ranging from about 0.5 to 2
mm. The resulting block has final dimensions of 4 inches by 3.75
inches by 8 inches. The resulting block has open, interconnected
cells.
EXAMPLE 2
[0031] Plant growth media is formed by preparing a mixture of about
3 weight percent calcium carbonate foaming agent sized at minus 200
mesh, about 3 weight percent high phosphorous nutrient powder,
about 0.1 weight percent BaO hydrophilic agent, with the balance
being recycled container glass sized at minus 325 mesh. The mixture
is then was positioned in a mold and heated to a foaming
temperature of 1400 degrees Fahrenheit for 45 minutes followed by a
rapid quench to room temperature. The resulting foamed glass
article is then crushed to produce foamed glass media with an open
porosity of between about 80 and 90 percent with pores ranging from
between about 1 and about 3 mm in diameter.
EXAMPLE 3
[0032] To prepare a block for cleaning tile, porcelain or enameled
surfaces, a procedure similar to that of Example 1 was used by
mixing together about 1.5 weight percent magnesite foaming agent
(minus 200 mesh), about 3 weight percent oxide nutrient, about 0.1
weight percent SrO hydrophilic agent, with the balance being
recycled container glass (minus 325 mesh). The mixture is placed in
a mold and heated to a foaming temperature of about 1360 degrees
Fahrenheit for 60 minutes. The resultant foamed glass body is then
allowed to anneal and then cool, to yield a foamed glass article
with a porosity of about 85 percent and a pore size distribution
ranging from about 0.05 to 0.2 mm. The article may be machined to
shape or crushed to form pebbles.
EXAMPLE 4
[0033] A foamed glass article may be prepared by mixing together
about 0.1 weight percent calcium carbonate foaming agent, about 0.1
weight percent ZnO hydrophilic agent, about 2 weight percent oxide
nutrient, and the balance recycled container glass, with all
powders being sized at minus 325 mesh. The mixture is placed in a
mold and heated to a foaming temperature of about 1425 degrees
Fahrenheit for about 25 minutes. The resulting foamed glass article
is typically annealed. The resulting article will have a porosity
of about 90 to about 95 percent, with a pore size distribution
ranging from about 0.01 to 0.1 mm. The resulting block can be
machined into a desired shape, cut into smaller blocks, or crushed
into pebbles.
EXAMPLE 5
[0034] Crushed glass pebbles are prepared by mixing together about
2.5 weight percent calcium carbonate foaming agent sized at minus
200 mesh, about 3 weigh percent phosphorous and potassium oxides,
about 0.1 weight percent ZnO, about 20 weight percent sand sized at
between 60 and 100 mesh, with the remainder being powdered
soda-lime-silica glass. The mixture is loaded into a mold and fired
to about 1500 degrees Fahrenheit for foaming for about 20 minutes,
followed by a rapid quench. The resulting article has a porosity of
between about 70 and about 80 percent with a pore size distribution
ranging from about 1 to 3 mm. The resulting article is crushed to
produce pebbles between about 1 and about 2 centimeters in
diameter.
EXAMPLE 6
[0035] A porous crushed glass substrate is produced by mixing
together between about 5 and about 10% weight percent calcium
carbonate sized at minus 200 mesh, about 0.1 weight percent ZnO,
about 3 weight percent K.sub.2O, with the balance being crushed
recycled container glass ground to minus 325 mesh. The mixture is
loaded into a mold and heated to a 1600 degree Fahrenheit foaming
temperature for 15 minutes. The resultant foamed glass article is
annealed and cooled and has a porosity of between about 90 and
about 95 percent and a pore size distribution ranging from about 2
to 4 mm. The resulting article may be cut or machined into a
desired shape or may be crushed into pebbles. Alternately, the
annealing step may be replaced by a rapid quench and the block
crushed into pebbles.
EXAMPLE 7
[0036] A foamed glass block may be produced by mixing together
about 3 weight percent minus 200 mesh calcium carbonate, about 3
weight percent P.sub.2O.sub.3, about 0.1 weight percent ZnO with
the balance minus 60 mesh recycled container glass. The mixture is
loaded into a mold and heated to a foaming temperature of 1500
degrees Fahrenheit for 40 minutes. The resulting article has a
density of about 85 percent and a pore size distribution ranging
from about 2 to 4 mm.
EXAMPLE 8
[0037] Glass pebbles are prepared by mixing together about 1
percent calcium carbonate foaming agent sized about 10-20 micron
median particle size, about 1 percent ZnO, about 0.2 percent
calcium borate, with the remainder powdered soda-lime glass. The
mixture is pressed into 2 mm diameter pellets and fired without a
mold to about 1500 degrees Fahrenheit for foaming with a residence
time of about 20 minutes, followed by a rapid air quench. The
resulting articles have a porosity of between about 80 and 95
percent with a pore size ranging between 0.1 and 2.5 mm. The
resulting articles can be crushed to 3.times. pore size as
needed.
EXAMPLE 9
[0038] This Example provides some additional detail concerning the
expedient mounding of the foamable mixture. A block of foamed glass
material suitable for use as a plant growth support substrate is
produced by thoroughly mixing together (such as for 20 minutes in a
mechanical mixer) about 2.5 weight percent calcium carbonate powder
(100% of which passes through a 200 mesh screen), about 20 weight
percent common sand (100% of which passes through a 40 mesh screen
but which does not pass through an 80 mesh screen), about 0.1
weight percent ZnO (100% of which passes through a 200 mesh
screen), about 3 weight percent K.sub.2O (100% of which passes
through a 200 mesh screen) with the balance being ground recycled
container glass (100% of which passes through a 325 mesh
screen).
[0039] A 1/4 inch stainless steel plate having a dimension of 20
inches.times.26 inches is coated with a thin slurry of talc and
alumina as agents to prevent sticking. A stainless steel mold is
coated with the same slurry. The mold has the shape of a frustum
and was open at the base. The base dimensions are 20 inches by 26
inches, and the peak dimensions are 19 inches by 26 inches; the
mold is 6 inches deep. The four portions of 3 kg are divided from
the batch, and each portion is placed on the 20 inch by 26 inch
plate in a row such that it has base dimensions of 4.5 inches by 16
inches. The four rows are typically evenly spaced 2 inches apart.
The rows, which typically are oriented parallel to the long
dimension of the plate, are spaced 1 inch away from the edge of the
plate. The ends of the rows are placed 2 inches away from the short
edges of the plate. Each row typically has a trapezoidal
cross-section the base of which, such as 4.5 inches and the top of
which is 3.5 inches, with a height of 3 inches. Each portion may be
compacted into the above shape, and the bulk density of the powder
after being compacted is about 72 pounds per cubic foot. A frustum
shaped lid is lowered onto the plate supporting the mounds of
foamable mixture, whereupon the entire assembly is placed into a
furnace.
[0040] The furnace is rapidly heated to about 1250 degrees
Fahrenheit and is held for a one-hour soak to allow the foamable
mixture to sinter and absorb heat evenly. The temperature is then
rapidly increased to 1500 degrees Fahrenheit and held there for a
one-hour soak. The mounds of powder then foam, fuse, and fill the
mold. The temperature may then be rapidly lowered to about 1050
degrees Fahrenheit and held there for at least about 15 minutes to
halt the foaming process and to solidify the outside skin of the
mass of foamed glass. The frustum shaped portion of the mold may
then be removed from the mass of solidified foamed glass. The block
of foamed glass article may then be placed in an annealing lehr to
slowly cool the foamed glass article to ambient temperature, or
alternately, the foamed glass article may be rapidly quenched to
room temperature. The finished and cooled annealed block of foamed
glass may then be planed and trimmed to remove the glassy skin and
traces of release agent, and the finished cut block of foamed glass
may be cut or machined into any desired shape. The foamed glass
article will have a porosity of about 90 percent and a pore size
distribution ranging from about 2.0 to 5.0 mm.
[0041] FIGS. 3 and 5 illustrate other embodiments of the novel
technology, hydroponic systems 40, 55 for growing plants. In FIG.
3, a hydroponic system 40 is disclosed wherein a substrate block 10
is partially immersed in a fluid medium 42, such as water or an
aqueous nutrient solution. Roots 35 extend downwardly into the top
of the substrate block 10 through the interconnected open pores 15.
Nutrient solution 42 is carried upwardly into the block 10 via
capillary action through the open pores.
[0042] FIG. 5 illustrates another embodiment of the present novel
technology, a system 55 including foamed glass pebbles or pellets
50 prepared as detailed above and used in a soil-pellet mixture 57
into which plant roots 35 may extend. The pellets 50 are typically
made of porous foamed glass material, but may alternately be made
of porous glass material, such as formed by agglomerating and
fusing together glass, metal or polymer bodies, such as spheres 99
(see FIG. 9). The mixture 57 may, in addition to the pellets 50,
include soil, clay, peat moss, nitrates, fertilizer, manure or the
like and mixtures thereof. Likewise, the pellets 50 may be used in
place of perlite in soil admixtures. The pellets 50 contribute by
picking up, holding, and slowly releasing water, as well as by
providing a network of `anchors` for the roots 35 to extend into
and through.
[0043] FIG. 6 illustrates still another embodiment of the present
novel technology, a hydroponic system 70 including a bed 71 of
foamed glass agglomerate media 50 into which roots 35 are growing.
The media 50 are prepared and characterized as discussed above.
Typically, the bed 71 is prepared in the form of bags of media 50
containing a substantially constant, predetermined volume (such as,
for example, 15 liters) of media 50. More typically, the media 50
are loosely packed to define a bed. The bags may be perforated and
root systems 35 may extend through the bags and into the media 50.
Likewise, water and nutrients may be applied to the media 50
through the bags. Alternately, the media may be placed into
preformed containers, vessels, depressions or the like and roots
growing thereinto may be fed and irrigated by any convenient
technique.
[0044] FIGS. 7 and 8 illustrate yet another embodiment of the
present novel technology, a hydroponic system 80 similar to that
discussed above regarding FIG. 6, but with a top unitary porous
slab member or portion 85 overlaying a layer 87 of loose crushed,
pelletized or otherwise particulate media 50. Typically, the
unitary slab portion 85 is positioned atop the pelletized media
layer 87, but the slab portion 85 may alternately be positioned
below the pelletized media layer 87. More typically, the slab
member 85 and media 50 are formed from porous foamed glass as
discussed above. Alternately, the slab portion 85 may be formed
from rockwool, coconut coir, or other convenient fibrous or
cellular material, glass particles, glass or polymer or metal
spheres (solid or hollow), or the like and combinations thereof
(see FIG. 10). In some embodiments, the slab portion 85 and/or
media 50 are formed from agglomerations of (typically hollow) glass
spheres, which may be packed together to define a porous material;
more typically, the glass spheres are cemented or fused together to
form a porous agglomerate body 85, 50. Likewise, the bottom layer
87 of particulate media 50 may alternately consist of E-Stone,
expanded clay, perlite, coco husk, agglomerated glass
particles/spheres, or other media and, more typically, allows for
water uptake at a lesser value than the top slab portion 85.
Typically, the slab layer 85 is about as thick as the media layer
87, although the thickness of the slab portion 85 to the media
layer 87 may be varied according to the growth needs of specific
plants and/or in response to specific growing conditions and/or
climactic differences. The top layer 85 typically allows for
uniform or near uniform absorption of irrigation or nutrient fluid
and, more typically, accepts at least twice it's mass in
water/nutrient fluid through capillary infiltration. More
typically, the top layer accepts at least thrice its mass in
water/nutrient fluid, and still more typically, the top layer
accepts at least four times its mass in water/nutrient fluid.
[0045] While the novel technology has been illustrated and
described in detail in the drawings and foregoing description, the
same is to be considered as illustrative and not restrictive in
character. It is understood that the embodiments have been shown
and described in the foregoing specification in satisfaction of the
best mode and enablement requirements. It is understood that one of
ordinary skill in the art could readily make a nigh-infinite number
of insubstantial changes and modifications to the above-described
embodiments and that it would be impractical to attempt to describe
all such embodiment variations in the present specification.
Accordingly, it is understood that all changes and modifications
that come within the spirit of the novel technology are desired to
be protected.
* * * * *