WO2016146518A1 - Granulés de verre moussé, leur préparation et utilisation - Google Patents

Granulés de verre moussé, leur préparation et utilisation Download PDF

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Publication number
WO2016146518A1
WO2016146518A1 PCT/EP2016/055273 EP2016055273W WO2016146518A1 WO 2016146518 A1 WO2016146518 A1 WO 2016146518A1 EP 2016055273 W EP2016055273 W EP 2016055273W WO 2016146518 A1 WO2016146518 A1 WO 2016146518A1
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WO
WIPO (PCT)
Prior art keywords
glass
granules
remains
binder
fibrous material
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Application number
PCT/EP2016/055273
Other languages
English (en)
Inventor
Christopher Robert Cheeseman
Veronica FERRANDIZ MAS
Rosemary Irene Whincup Greaves
Savi Madan
Original Assignee
Bob Martin (Uk) Ltd
Imperial Innovations Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bob Martin (Uk) Ltd, Imperial Innovations Limited filed Critical Bob Martin (Uk) Ltd
Priority to EP16709771.6A priority Critical patent/EP3268320A1/fr
Publication of WO2016146518A1 publication Critical patent/WO2016146518A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/08—Other methods of shaping glass by foaming
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01K—ANIMAL HUSBANDRY; AVICULTURE; APICULTURE; PISCICULTURE; FISHING; REARING OR BREEDING ANIMALS, NOT OTHERWISE PROVIDED FOR; NEW BREEDS OF ANIMALS
    • A01K1/00—Housing animals; Equipment therefor
    • A01K1/015—Floor coverings, e.g. bedding-down sheets ; Stable floors
    • A01K1/0152—Litter
    • A01K1/0154—Litter comprising inorganic material
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B1/00—Preparing the batches
    • C03B1/02—Compacting the glass batches, e.g. pelletising

Definitions

  • the present invention relates to a foamed glass composition, a process for making a foamed glass composition in the form of a granule having interconnected porosity, and the use of said foamed glass composition as an absorbent material.
  • One envisaged use of the foamed glass composition is as an animal litter product.
  • the invention also relates to an animal litter product comprising absorbent foamed glass granules.
  • Foamed glass products are known and have myriad uses. Exemplary applications of foamed glass substrates include use in construction materials, hydroponics, and as artificial pumice for use in the textile industry. Foamed glass typically displays low capacity for moisture absorption.
  • WO 2013/093509 relates to forming an aggregate of powdered glass, a silicate, and a foaming agent such as CaCO 3 or a fibrous carbonaceous material, such as cellulose, paper, or cardboard, for use in construction materials.
  • a refractory coating is applied to the pellets prior to firing to reduce stickiness.
  • the pellets may be pre-heated before the firing step.
  • the firing step creates a plurality of closed voids within the particles.
  • the outer layer of the particles is a substantially impermeable vitreous layer, resulting in non-absorbent particles.
  • CN 102633484 relates to glass beads for use as a lightweight filler in dry mortar, or as an ingredient in tile adhesive.
  • the beads comprise crushed glass (400 mesh or less; corresponding to a diameter of 37 ⁇ or less), mixed with a foaming agent (for example 5 wt.% CaCO 3 ) and a binder, and then fired at 800-820 °C.
  • the resulting particles have an internal honeycomb mesh structure and a bulk density of 310-460 kg/m 3 .
  • the particles exhibit small pores and low water absorption.
  • WO 94/14714 relates to a foamed glass substrate to make artificial pumice, used for stone washing of garments.
  • Powdered glass is mixed with a foaming agent, such as a carbonate, a binder, and water.
  • the mixture is heated to a first temperature to remove moisture and avoid the formation of steam during the foaming process, and subsequently heated to a second, higher temperature for the foaming process.
  • the heating stages are followed by three cooling stages.
  • US 4,933,306 relates to a foamed glass substrate to make artificial pumice, used for stone washing of garments.
  • Particles of waste glass are ground to ⁇ 1 mm and mixed with sand, basalt, and CaCO 3 or MgCO 3 .
  • a heating step is carried out at 700°C, followed by rapid cooling to break up the substrate.
  • Alkaline silicate can be added to promote the granules sticking together.
  • WO 2009/029645 relates to a porous foamed glass substrate for water storage in the field of hydroponics.
  • the substrate particles act as a mechanical support for plant root propagation.
  • a lightweight foamed glass substrate with voluminous, interconnecting pores is made by mixing powdered glass, with a foaming agent, such as CaCO 3 .
  • a plant growth nutrient material and a wetting agent are added to the starting materials. Pore sizes are between 0.5 and 5 mm, which can accommodate a plant root.
  • Animal litter products that are currently on the market are primarily made of clay minerals, such as bentonite (aluminosilicate), and sepiolite (magnesium silicate), used for their absorbent properties.
  • clay minerals such as bentonite (aluminosilicate), and sepiolite (magnesium silicate)
  • dust formation which can be hazardous to breathe.
  • Another problem is that the dust can be tracked out of the litter tray on the paws of the animal.
  • CN 103348923 relates to a low cost cat litter product, based on straw and other plant stalks. Plant materials, making up 64 to 88 weight % of the composition, are ground to 60-80 mesh (177-250 ⁇ diameter) and mixed with volcanic rock, sodium silicate, and 5 to 10 weight % of a superabsorbent.
  • Pellets of 2-3 mm diameter are formed and allowed to dry naturally - no heating of the pellets is carried out.
  • Glass is a readily available material. It is recyclable, environmentally friendly, low cost and has a highly consistent composition. In its usual form, glass is non-absorbent. Waste glass can be recycled from containers, such as glass bottles and jars. Crushed waste glass is generally referred to as glass cullet.
  • the present invention recycles waste glass into a useful product, for example, an absorbent animal litter product.
  • Standard foamed glass does not exhibit the required absorbency for such an application.
  • Standard foamed glass has a relatively low water absorption, typically less than 20 wt.%, and closed pores rather than open, interconnected pores. This absorbency is not sufficient for use as an absorbent animal litter product, or many other commercial uses where absorption is desired.
  • An animal litter should also have good odour retention and be essentially or completely dust free.
  • the present invention relates to pellets or granules having a high moisture absorbency, good strength, and low dust generation.
  • the terms 'pellet' and 'granule' are used interchangeably herein.
  • the production of highly absorbent granules is achieved by a controlled and engineered foamed glass formulation.
  • Absorbency of the granules of the present invention is significantly increased by inclusion of organic fibres into the glass mixture during the foaming process.
  • the present invention relates to a process for preparing said absorbent granules.
  • the granules having the described composition may be used as an animal litter.
  • the present invention also relates to an absorbent foamed glass composition manufactured from starting materials including glass, a fibrous material, a binder, and a foaming agent (also referred to as a 'bloating agent').
  • the present invention also relates to a foamed glass absorbent animal litter product manufactured from starting materials including glass, a fibrous material, a binder, and a foaming agent.
  • the 'green' granules formed by mixing together the starting materials of glass, foaming agent, organic fibrous material, binder and water, are subjected to a heating process, for example, in a kiln or furnace.
  • the absorbent granules produced by this process contain glass and the remains of the foaming agent, the organic fibrous material and the binder, after they have undergone decomposition reactions during the heating process, and may also contain some amounts of unreacted starting material.
  • the term 'green' relates to the state of the granule before it undergoes the firing process.
  • the glass may be finely powdered glass, preferably sourced and ground from waste glass, in particular from mixed-colour waste glass.
  • the components of the composition (glass, an organic fibrous material, and a foaming agent) are mixed together thoroughly.
  • the glass, foaming agent, and organic fibrous material make up what is referred to herein as the "glass mixture”.
  • a binder and water are added to the glass mixture, and then the mixture is formed into granules.
  • These granules may be coated with a refractory coating before being transferred to a rotary furnace or kiln, which is pre-heated to a temperature above the glass softening temperature (starting at about 573 °C), causing the components to fuse together. After the firing step, the granules are cooled to room temperature.
  • the composition is chemically foamed by the gas emitted from the organic fibrous material and the foaming agent.
  • a carbonated material is used as the foaming agent, which decomposes into CO 2 (g) and solids that stay behind, as it is calcined.
  • the inclusion of the fibrous material is also believed to contribute to the foaming process and to result in the formation of interconnected pores within the granules.
  • the resulting granules are porous with an interconnected network of channels throughout the granules, which also reach the surface of the granules.
  • the granules are lightweight and highly absorbent, able to absorb over 70 wt.% of moisture. In some embodiments, the absorbency is over 80 wt.%, over 90 wt.%, or over 100 wt.%.
  • Figure 1 shows a flowchart for a process of manufacturing a composition of the present invention
  • Figure 2 shows the effect of the furnace temperature, amount of binder and amount of foaming agent on absorbency
  • Figures 3, 4 and 5 show the absorbency of exemplary granules of the invention varying with composition and process conditions.
  • Figure 6 shows the pore diameter distribution of two granules of the present invention, compared to a reference granule without coconut fibres
  • Figure 7A and 7B show a Scanning Electron Microscopy (SEM) image of the interior and surface, showing the microstructure of a reference granule made without fibres.
  • SEM Scanning Electron Microscopy
  • Figure 8A and 8B show a Scanning Electron Microscopy (SEM) image of the interior and surface, showing the microstructure of a granule of the invention made with fibres.
  • SEM Scanning Electron Microscopy
  • Figure 9 shows an X-Ray Powder Diffraction pattern for a reference granule made without fibres (grey line) compared to a granule of the invention made with fibres (black line).
  • the 'raw' glass starting material is standard non-porous glass cullet.
  • waste glass is used, which may be coloured or colourless glass, such as container glass or window glass (soda-lime glass), or may be mixed-colour waste glass.
  • the present invention is particularly useful in that it can make use of mixed- colour waste glass.
  • the origin and type of glass are not determinative for the present invention and any glass may be used, including, for example, sodium borosilicate glass. Glass has a softening temperature starting at about 573 °C, which can vary, depending on the type of glass.
  • the glass cullet starting material may be provided in particles of 1 to 4 mm diameter, and most usually less than 2 mm diameter.
  • the glass particles can be of an irregular shape.
  • the diameter refers to the longest dimension of a particle.
  • the glass cullet is milled to a fine powder. The milled glass is sieved to remove any larger particles.
  • the particle size of the milled glass influences the sintering properties of the glass.
  • the glass is milled (for example dry milled) to have a maximum particle diameter of less than 212 ⁇ (e.g. 95 % of the particles will pass through a 70 mesh sieve; 70 mesh corresponds to sieve openings of 210 ⁇ ).
  • the volume of a spherical (or approximately spherical) particle having a diameter of 212 ⁇ is about 0.000005 cm 3 (particle volume 5 ⁇ 10 "6 cm 3 ).
  • the finely powdered glass is then mixed with further components in the proportions set out below.
  • foaming agent is added to the powdered glass.
  • foaming agent also referred to in the art as a “bloating agent” refers to a material or compound which generates gas when heated, and causes the glass mixture to foam, that is, to expand in volume.
  • foaming agents for the present invention are carbonates (for example, calcium carbonate (CaCO 3 ), magnesium carbonate (MgCO 3 )), precipitated silica, sulphides, Fe 2 O 3 , MnO 2 , SiC, water-glass, or mixtures thereof.
  • the foaming agent is a carbonate, for example, CaCO 3 or MgCO 3 , or a mixture thereof.
  • the foaming agent is preferably milled to have a maximum particle diameter of 1 to 250 ⁇ , with about 90 % of particles having a particle diameter of 1 to 150 ⁇ and about 75 % of particles having a particle diameter of 1 to 125 ⁇ .
  • a fibrous material preferably a plant-derived fibre is also added to the powdered glass.
  • the fibrous material is preferably an organic, carbonaceous material.
  • the fibrous material may, for example, be one or more of cellulose fibres, hemi-cellulose fibres, lignin fibres, coconut husk (i.e. the fibrous part of the husk, also referred to as coir), dried bagasse, or another suitable material, such as sisal, jute coir, oil palm coir, rice husk, or straw.
  • the fibrous material may be waste organic material.
  • the fibrous material is selected from one or more of cellulose fibres, hemi-cellulose fibres, lignin fibres, or coconut husk.
  • the fibrous material is milled, for example, hammer milled, to have a maximum average size of particles of 0.7 - 1 .2 mm in diameter, and preferably 0.1 to 1 mm in diameter.
  • the fibrous material may be sieved to remove any remaining larger particles.
  • Individual fibres of up to 10 mm in length, and 0.1 to 1 mm in diameter, may also be present.
  • additional components may be incorporated into the glass mixture, for example, perlite and/or vermiculite.
  • Perlite and vermiculite both release water vapour during firing.
  • the glass, foaming agent, organic fibrous material and said optional additional components make up what is referred to herein as the "glass mixture”.
  • Binder
  • a binder is added to the glass mixture described above.
  • the binder may be any material or compound which aids the formation of the granules prior to the heating step.
  • the binder can also lend strength to the granules formed from the mixture.
  • Suitable binders include clays, for example, bentonite clay, and silicates, for example sodium silicate (Na 2 SiO 3 ), potassium silicate, or organic polymers.
  • the binder is sodium silicate.
  • the binder is added in liquid form, dissolved in water.
  • the amount of water may be between 10 to 25 wt.% of the weight of the "glass mixture".
  • Preferably about 20 wt.% of water is added to the glass mixture, based on the total weight of the glass mixture.
  • approximately 0.5 to 3 wt.% sodium silicate binder may be included in the composition, based on the weight of the glass mixture.
  • Preferably, between 1 and 2 wt.% sodium silicate binder may be included, based on the weight of the glass mixture.
  • Na 2 SiO 3 may contribute to the foaming (the creation of the porous network) of the granules during the firing step.
  • the sodium silicate forms additional silicate during firing, contributing to the glass matrix.
  • one or more further binders may be added to the glass mixture described above.
  • Such one or more further binders may be selected from organic materials, such as, lignosulfonate, sodium lignosulfonate, calcium lignosulfonate, a carboxymethyl cellulose (CMC), and pregelatinised starch (starch that has been cooked and dried), for example, pregelatinised corn starch or pregelatinised potato starch.
  • Pregelatinised starches are available, for example, from Aminola BV, The Netherlands.
  • Calcium lignosulfonate is available, for example, as Lignobond DD from Borregaard AS, Norway.
  • a suitable carboxymethyl cellulose (CMC) is available, for example, as Peridur 386 from Akzo Nobel.
  • the function of the additional organic binder is as a granulation binder.
  • the organic binder also referred to herein as an organic granulation binder
  • the sodium silicate enhances green strength inside the furnace as the pellets begin to dry at elevated temperatures.
  • the 'green' mixture is pelletised.
  • the granules are preferably substantially spherical and typically between approximately 0.25 mm and 10 mm in diameter, for example, between approximately 1 and 5 mm in diameter.
  • the green granules may be coated with a refractory coating to prevent the granules sticking together during the heating (sintering) process.
  • the coating may also assist in the foaming process, possibly assisting in the creation of open pores on the surface of the pellets. This porosity leads to improved absorbency properties of the granular product.
  • Suitable coating agents include, for example, CaCO3, MgCO3, perlite, vermiculite, precipitated silica, clay, AI 2 O 3 , concrete, or mixtures thereof.
  • the coating agent on the green granules is CaCO 3 , MgCO 3 , precipitated silica, perlite or vermiculite, or a mixture of any two or more of CaCO3, MgCO3, precipitated silica, perlite and vermiculite, in any proportion.
  • a preferred coating agent on the green granules is CaCO 3 , MgCO 3 or precipitated silica.
  • the coating agent may be the same as, or different from, the foaming agent.
  • the CaCO 3 or MgCO 3 is converted to CaO or MgO during firing and CO 2 gas is released, which contributes to the formation of additional surface porosity of the granules. This reaction also leaves a coating of CaO or MgO on the granules.
  • water vapourising during the firing step is believed to cause additional surface porosity.
  • Perlite and vermiculite have a lower pH than CaCO3 and may be preferable in embodiments where a lower pH is advantageous.
  • precipitated silica emits water vapour.
  • the coating agent can be applied to the granules in powder form, where it will stick to the granules due to their moisture content, leaving a coating material remaining after the firing step, for example, CaO, MgO, fired precipitated silica, fired perlite or fired vermiculite.
  • a coating agent can be mixed with water and sprayed onto the granules. Spray coating methods are known to the person skilled in the art.
  • the amount of coating applied is preferably 0.01 - 0.1 wt. % based on the total weight of the granules.
  • the granules may be non-coated.
  • Surface porosity connected to the internal network of pores within each granule is still achieved by the foaming of the granule caused by the foaming agent and in particular, the interconnectivity of the pores is due to the fibrous material.
  • the surface connected porosity is particularly achieved by the fibrous material.
  • the granules are dried before being charged into the rotary furnace or kiln.
  • the granules are coated before firing.
  • a key feature of the heating (sintering) process is that the firing is rapid: the granule is provided into the furnace already pre-heated to a high temperature. The temperature of the granule increases from room temperature to sintering temperature within less than 30 seconds. This rapid firing causes the decomposition of the foaming agent and fibrous material at a temperature where the glass has simultaneously softened, so that the evolved gas is caught or trapped in the glass. Slow or gradual heating of the composition does not achieve this effect.
  • the powdered glass makes up at least 90 % by weight of the glass mixture, for example, between 91 and 98 wt.% of the glass mixture. In some aspects of the invention, the powdered glass makes up between 92 and 96 wt.% of the glass mixture. Most preferably, the powdered glass makes up 93, 94, 95, or 96 wt.% of the glass mixture.
  • the foaming agent makes up between 1 - 8 wt.% of the glass mixture, more preferably between 3-7 wt.% of the glass mixture. Even more preferably, the foaming agent makes up between 4-6 wt.% of the glass mixture. Most preferably, the foaming agent makes up 4, 5, or 6 wt.% of the glass mixture.
  • the foaming agent is CaCO 3 or MgCO 3 or a mixture of the two, in these quantities.
  • the carbonaceous fibrous material makes up between 0.5 and 3 wt.% of the glass mixture. More preferably, the fibrous material makes up 1 or 2 wt.% of the glass mixture. Most preferably, the fibrous material makes up between 0.5 to 1 .5 wt.%, for example, about 1 wt.% of the glass mixture.
  • the carbonaceous fibrous material is coconut husk.
  • Perlite and/or vermiculite may optionally be comprised in the glass mixture. If perlite and/or vermiculite are present in the glass mixture, these will form part of the fraction of the foaming agent - that is, the total amount of foaming agent in the glass mixture will be between 1 to 8 wt.% of the total weight of the glass mixture, and the foaming agent fraction may be made up of any combination and proportion of any of CaCO 3 , MgCO 3 , perlite and vermiculite.
  • the foaming agent may be CaCO3, MgCO3, perlite or vermiculite, or a mixture of any two or more of CaCO 3 , MgCO 3 , perlite or vermiculite, in any proportion.
  • the foaming agent may be 100% CaCO 3 ; 100% MgCO 3 ; 75% CaCO 3 and 25% perlite; 75% CaCO 3 and 25% MgCO 3 ; 60% CaCO 3 and 20% perlite and 20% vermiculite; 20% CaCO 3 and 80% perlite; 50% CaCO 3 and 50% MgCO 3 ; 100% perlite; 100% vermiculite; etc..
  • These exemplary percentages are purely for illustration and not intended to be limiting on the scope of the invention.
  • the glass mixture is then further mixed with a binder and water, and granules are then formed.
  • the binder is present in an additional 1 to 2 wt.% based on the weight of the glass mixture.
  • the binder is sodium silicate.
  • Water is added to plasticise the glass mixture and binder, such that granules can be formed. About 10 to 25 wt.% water is added based on the weight of the glass mixture. Preferably, about 15 to 25 wt.% water is added based on the weight of the glass mixture. Most preferably 20 wt. % of water is added based on the weight of the glass mixture.
  • the binder is sodium silicate solution, such that the water and the binder are added to the glass mixture at the same time.
  • a composition of the invention is in the form of green granules comprising:
  • composition of the invention is in the form of green granules comprising:
  • the composition may further comprise one or more organic binders.
  • the Organic binder' is also interchangeably referred to herein as an Organic granulation binder'.
  • the organic binder is selected from, for example, lignosulfonate, sodium lignosulfonate, calcium lignosulfonate, carboxymethyl cellulose (CMC), pregelatinised corn starch, or pregelatinised potato starch.
  • the organic binder is present in an additional 0.5 to 2 wt.% based on the weight of the glass mixture, for example, 1 to 2 wt.% based on the weight of the glass mixture.
  • the organic binder is one or more of lignosulfonate, sodium lignosulfonate, or prege!atinised corn starch .
  • a composition of the invention is in the form of green granules comprising:
  • composition of the invention is in the form of green granules comprising:
  • the foaming agent is a carbonate, such as CaCO3 or MgCO3, the carbonaceous fibrous material is cellulose, hemi-cellulose, lignin, or coconut husk, and the binder is Na 2 SiO 3 .
  • the organic granulation binder is lignosulfonate, sodium lignosulfonate, calcium lignosulfonate, a carboxymethyl cellulose (CMC), or pregelatinised corn starch.
  • the coating agent (if present) may be CaCO 3 or MgCO 3 (decomposing to CaO and MgO, respectively), perlite or vermiculite, or a mixture of any two or more of these, in any proportion.
  • An optional coating on the green granules may comprise 0 - 0.1 wt.% of the granule weight.
  • the green granules are fired in a kiln or rotary furnace, resulting in absorbent granules comprising glass and the remains of the further components, after they have undergone decomposition reactions during the heating process, and may also contain an amount of unreacted starting material.
  • the foamed glass granules of the invention comprise the sintered, or fused, glass particles, and the remains of the foaming agent, the fibrous material and the binder components remaining after the heating process, e.g. after the decomposition reaction, producing a gas.
  • Figure 1 illustrates steps of the process.
  • glass cullet particles of 1 to 4 mm diameter obtained from recycling facilities, are milled to a fine powder.
  • the milled glass is sieved to remove any larger particles.
  • the resulting glass powder has a maximum particle diameter of less than 212 ⁇ (e.g. 95 % of the particles will pass through a 70 mesh sieve; 70 mesh corresponds to sieve openings of 210 ⁇ ).
  • the foaming agent for example CaCO 3 (for example, obtained from a limestone quarry as the waste fines, but also obtainable, e.g., from Sigma-Aldrich Company Ltd., Dorset, UK), may be milled, for example in a ball mill, to have a maximum particle diameter of less than 212 ⁇ (e.g. 95 % of the particles will pass through a 70 mesh sieve; 70 mesh corresponds to sieve openings of 210 ⁇ ). About 90 % of particles will have a particle diameter of 1 to 150 ⁇ and about 75 % of particles having a particle diameter of 1 to 125 ⁇ .
  • CaCO 3 for example, obtained from a limestone quarry as the waste fines, but also obtainable, e.g., from Sigma-Aldrich Company Ltd., Dorset, UK
  • the fibrous material (for example coconut husk obtained from Van der Knaap Group, Netherlands), is milled, preferably hammer milled, to have a maximum average size of particles of 0.7 - 1 .2 mm, and preferably less than or equal to 1 mm, and preferably less than 1 mm, for example 0.2 to 0.9 mm.
  • Individual fibres of up to 10 mm in length and 50-500 ⁇ in diameter may also be present. The fibres may be sieved to remove any remaining larger particles.
  • the milled glass, foaming agent and fibrous material are thoroughly mixed together.
  • the binder for example sodium silicate
  • water is preferably mixed with water.
  • sodium silicate solution is used (obtainable e.g. from Sigma Aldrich Co. Ltd, as above).
  • the binder may be added to the glass mixture, and after further mixing of the dry ingredients, water is added.
  • An amount of 10 to 25 wt.% water is preferred based on the weight of the glass mixture.
  • the organic binder for example, lignosulfonate, sodium lignosulfonate, calcium lignosulfonate, a carboxymethyl cellulose (CMC), or pregelatinised corn starch, is preferably mixed with water prior to its addition to the glass mixture.
  • CMC carboxymethyl cellulose
  • the total amount of water for the binder is between about 15 to 25 wt.% water, more preferably 18-22 wt.% water, based on the weight of the glass mixture.
  • the mixture is pelletised.
  • Mixing and pelletisation may, for example, be carried out in an Eirich mixer.
  • the resulting granules are preferably substantially spherical and preferably approximately 0.25 - 10 mm in diameter, and more preferably 1 - 5 mm in diameter.
  • the granules may be coated or left uncoated. In a preferred embodiment, the granules are coated.
  • the granules may be coated with CaCO3, MgCO3, perlite, vermiculite, precipitated silica, clay, AI2O3, concrete, or mixtures thereof, by spray coating or simply by adding the coating component(s) into the mixer as a powder, once the green granules have been formed.
  • the coated granules can be placed directly into the furnace. Alternatively, if the coated granules are stored before being placed in the furnace, the granules are preferably kept in a humid or moist condition prior to firing. It has been found that if the coated granules are dried prior to firing, the resulting absorbency of the fired particles is substantially reduced. The Applicants have measured absorbency of only 23 wt.% in coated granules that were dried prior to the firing step (e.g. at 100 °C). Uncoated granules, on the other hand, are preferably dried before the firing step. Alternatively, these result in agglomerated granules, useful in other applications.
  • the green granules are placed into a pre-heated rotary furnace or kiln.
  • the temperature in the furnace or kiln may be between 750-900 °C.
  • the temperature in the furnace is between 790-830 °C.
  • the temperature in the furnace is about 800 °C, about 810 °C, about 820 °C, or about 830 °C.
  • the furnace temperature stability is preferably within ⁇ 10 °C of the set temperature.
  • Different types of furnace can be used for the firing step.
  • a belt furnace is used.
  • the belt may receive granules to a depth of 3 cm, having heating elements above and below the belt, different heating zones, and include an extractor system for organics.
  • a rotary furnace is used.
  • the dwell time of the granules in the furnace is between about 10 and about 40 minutes. Typical firing times are between about 10 and about 30 minutes, for example, 10, 20 or 30 minutes.
  • the composition as a whole is chemically foamed by the gases emitted from the foaming agent (e.g. CaCOs) as the foaming agent is calcined (decomposing to CO 2 gas and CaO), and the fibrous material, which also emits gaseous CO 2 as it decomposes.
  • the foaming agent e.g. CaCOs
  • Perlite and vermiculite are known to release water vapour when heated.
  • the moisture present in the granules prior to firing may also result in the emission of steam as the granules are heated. This may add to the pore formation within the granules during the foaming process.
  • the granules are allowed to cool to room temperature.
  • the initial cooling process is rapid, to 'lock' the interconnected internal and surface porosity into place, after which the granules are allowed to cool radiatively to room temperature.
  • the foaming of the granules during the firing step results in a lightweight porous product in granular form. This property is measured as the bulk density of the product.
  • the product granules have a bulk density of less than 0.33 kg/I, for example, less than 0.31 kg/I.
  • the bulk density is measured by pouring a sample of the product into a 50 ml container, for example, a beaker.
  • the product is poured into the container through a funnel, until it is overflowing. Any excess material is scraped off the beaker.
  • the beaker is weighed (M-i) taring the scale first with an empty beaker.
  • the foaming agent for example a carbonate, such as CaCOs
  • a carbonate such as CaCOs
  • Other substances such as MgCO3, sodium silicate, perlite and vermiculite, may also decompose by release of gas (such as CO 2 , and/or water vapour) during the firing step, causing formation of pores.
  • the incorporation of the fibres in the composition additionally influences the porosity of the granules.
  • the fibres affect the porous microstructure of the granules.
  • the fibres result in excellent internal interconnected porosity in the granules and allow for the internal porosity to be connected with the external (surface) porosity.
  • This interconnected porosity in the foamed glass granules of the present invention gives rise to their excellent absorption capacity.
  • the porosity enables liquid, such as animal urine, to be absorbed and retained inside the pores and channels inside the granules. This has the additional benefit of controlling odour, as the urine is retained inside the foamed glass granules.
  • the invention also relates to a foamed glass granule having an internal network of pores in the form of interconnected channels that extend to the surface of the granules; a bulk density of 0.33 kg/L or less; and an absorbency of 60 wt.% or more.
  • the bulk density is 0.32 kg/L or less, 0.31 kg/L or less, or 0.30 kg/L or less.
  • the absorbency is 70 wt.% or more, 80 wt.% or more, 90 wt.% or more, or 100 wt.% or more.
  • the granule comprises a mixture of a) 91 - 96 wt.% sintered milled glass particles, optionally having a particle volume of not greater than 5-10 "6 cm 3 ; b) the remains of a foaming agent, following the foaming agent being treated to produce a gas, the remains corresponding to the addition of 1 - 8 wt.% of the foaming agent; c) the remains of a fibrous material, following the fibrous material being treated to produce a gas, the remains corresponding to the addition of 0.5-3 wt.% of the fibrous material; and d) the remains of a binder, the remains corresponding to the addition of 1 -2 wt.% of, based on the total weight of components a) to c).
  • the invention also relates to an absorbent animal litter comprising porous foamed glass granules, each granule having an internal network of pores in the form of interconnected channels that extend to the surface of the granules, a bulk density of 0.33 kg/L or less, and an absorbency of 60 wt.% or more.
  • the bulk density is 0.32 kg/L or less, 0.31 kg/L or less, or 0.30 kg/L or less.
  • the absorbency is 70 wt.% or more, 80 wt.% or more, 90 wt.% or more, or 100 wt.% or more.
  • the granules comprise sintered glass particles; optionally having a particle volume of not greater than 5-10 "6 cm 3 ; the remains of a foaming agent, following it being treated to produce a gas; the remains of an organic fibrous material, following it being treated to produce a gas; and a binder, or the remains of a binder.
  • the amount of glass in the granules is between 90 and 98 wt.%.
  • the remains of the foaming agent in the granules corresponds to the addition of between 1 to 8 wt.% of the foaming agent, based on the total weight of the glass, foaming agent and fibrous material components, before the treatment to produce a gas, for example, being heated to a temperature sufficient to cause sintering of the glass.
  • the remains of the fibrous material corresponds to an amount between 0.5 to 3 wt.%, based on the total weight of the glass, foaming agent and fibrous material components, before the treatment to produce a gas, for example, being heated to a temperature sufficient to cause sintering of the glass.
  • the granules may be used as an absorbent animal litter.
  • Pore and channel volume and size can be determined by mercury intrusion porosimetry (for example using the Autopore IV 9500 V1.09, Micromeritics Instrument Corporation, USA), as known in the art.
  • Figure 6 shows a comparison between the pore diameter distributions for three granules: a reference granule made from glass and CaCO3 (without fibrous material) and two compositions of the invention (glass, CaCO 3 and fibrous material).
  • the sample without fibres and sample B2 were manufactured with 1 wt.% Na 2 SiO 3 as a binder, and sample D1 was manufactured with 2 wt.% Na 2 SiO3 as a binder, based on the total weight of the glass mixture. All three samples were fired at a temperature of 820 °C for a dwell time of 10 minutes.
  • Figure 6 illustrates the pore diameters found in the different granules, as well as the relative proportion of pore diameters (the pore diameter distribution), as measured by mercury intrusion porosimetry. Pore diameters were measured between less than 10 nm to larger than 0,1 mm.
  • the granules of the invention Comparing the granules with organic fibres to granules without fibres, the granules of the invention have a substantially larger proportion (more than double) of pores with diameters between 100 nm and 10 ⁇ , than the granules without fibres.
  • Granules "B2" also have substantially more pores larger than 0.1 mm in diameter than the granules without fibres.
  • Table 1 shows the porosity, intrusion volume, and water absorption of the granules without fibres and the granules of the invention.
  • the total intrusion volume for the sample without fibres is 1 .09 mL/g, whereas for samples B2 and D1 the total intrusion volume is 1 .99 and 1 .72 mL/g, respectively.
  • These data correlate with the water absorption of these samples, which are 20.7 ⁇ 5.2 wt. % for the sample without fibres, compared to 102.8 ⁇ 3.2 wt. %, and 91 .7 ⁇ 3.2 wt. %, for samples B2 and D1 , respectively.
  • Figures 7A and 7B are SEM images of a granule without fibres.
  • Figures 8A and 8B are SEM images of granule B2 of the invention.
  • Figures 7A and 8A show an internal cross section of the granules
  • Figures 7B and 8B show the external surface of the granules.
  • the B2 granule has more uniform pore sizes (most are between 100 and 500 ⁇ ) than the granule without fibres. Further, the darker pore colours in the B2 granule indicate the depth of the pore - the pores in B2 indicate channels extending through the interior of the granule.
  • the granule without fibres displays a larger proportion lighter grey coloured pores, indicating shallow pores and internal voids, rather than interconnected channels.
  • the surface of the B2 granule is smoother than the granule without fibres. The small black spots across the surface of the B2 granule are pore openings.
  • the granule without fibres displays a rough surface structure, but does not display this type of surface porosity.
  • the fibrous material contributes to the granules in multiple ways:
  • the fibres act as a foaming agent, in combination with the CaCO 3 .
  • the fibres facilitate the pelletisation process by acting as a reinforcement material making it possible to obtain larger and stronger green granules.
  • X-ray Powder Diffraction analysis was carried out on granules B2 of the invention and compared to reference granules without fibres (95 wt.% glass and 5 wt.% CaCO3, with 1 wt.% Na 2 SiO3, as described above).
  • An internal standard (10 wt.% silicon) was added to the samples in order to quantify the amorphous component.
  • the sample- standard mixture was placed in a flat plate sample holder and analysed using a
  • Panalytical X'Pert Pro MPD diffractometer Measurement conditions were as follows: Bragg-Brentano geometry, Cu Ka radiation, tube conditions 45 kV and 40 mA, measurement range 5-125° 2Theta, step size 0.02°, time per step 750-1000s, fixed diversion slit 0.25°.
  • the Rietveld method was applied to refine phase proportions (crystalline phases).
  • Phase identification was achieved by comparing the measured powder patterns with data from the International Centre for Diffraction Data - Powder Diffraction File2 (ICDD-PDF2) database (see: http://www.icdd.com/products/pdf2.htm). Crystal structure data for identified phases was taken from the Inorganic Crystal Structure Database (ICSD)
  • ICSD Inorganic Crystal Structure Database
  • the X-ray Powder Diffraction for the reference sample without fibres and for sample B2 show peaks at least as follows (Table 2), as shown in Figure 9 (the XRPD for the sample without fibres is depicted by the grey line and the XRPD for sample depicted by the black line).
  • the foamed glass granules of the invention are characterised in that the majority of the granule is amorphous.
  • the crystalline component of the granule comprises a mixture of at least calcium carbonate, calcium hydroxide, wollastonite and combeite.
  • the crystalline component of the granule comprises less than 5 wt.% Ca(OH) 2 ; for example, less than 2 wt.% Ca(OH) 2 ; for example, less than 1 wt.% Ca(OH) 2 .
  • the surface of the foamed glass granules may be treated with a mild organic acid, to lower the pH, which may result in further improved odour control.
  • a further optional component of the foamed glass granules of the invention is a probiotic agent, to assist with odour control of the animal litter, or alternatively, a biocide, which inhibits bacterial growth.
  • a probiotic or biocide may be added after firing, so that it is absorbed into the porous surfaces of the granule.
  • a probiotic agent and/or biocide may be present in an amount of up to 2 wt.% of the total weight of the granule. Dust generation from the foamed glass granules can be measured by attrition test ( ⁇ 0.25 mm), and has been measured to be less than 1 .5 wt.% based on the dry weight of the granules.
  • the foamed glass granules of the invention are light in colour.
  • the foamed glass granules are lightweight and highly absorbent, able to absorb over 70 wt.% of moisture.
  • Typical absorbencies for the foamed glass granules of the present invention are between 70 wt.% and 130 wt.%, for example between 80 and 1 10 wt.%.
  • compositions of the present invention demonstrate the effect of process conditions such as relative amounts of components, the temperature in the furnace, and the dwell time in the furnace, on the properties of the foamed glass granules of the present invention. Significant interactions are observed between:
  • Figure 2 shows the relationship between absorbency and: a) the amount of binder, b) the amount of foaming agent, and c) the furnace temperature, for a firing time of 10 minutes.
  • the dashed line shows that for a composition with 95 wt.% glass, 1 wt.% fibres (coconut husk), 4 wt.% CaCO 3 and 2 wt.% Na 2 SiO 3 , fired for 10 minutes, at either 800 °C, 810 °C, or 820 °C, the absorbency of the granules remains fairly constant.
  • the dotted line shows that for a composition with 94 wt.% glass, 1 wt.% fibres (coconut husk), 5 wt.% CaCO3 and 1 wt.% Na 2 SiO3, fired for 10 minutes, at either 800 °C, 810 °C, or 820 °C, the absorbency of the granules remains fairly constant between 800 °C and 810 °C, but is significantly higher if the furnace is at 820 °C.
  • the glass mixtures comprise glass ("G"), coconut husk fibres ("F") and foaming agent ("B") in the amounts indicated (wt.%).
  • "94G/1 F/5B” corresponds to a glass mixture comprising 94 wt.% glass, 1 wt.% coconut husk fibre and 5 wt.% foaming agent.
  • the foaming agent in each case is CaCO 3 .
  • the binder in each case is Na 2 SiO 3 .
  • the granules were coated with CaCO 3 prior to firing. After the firing step, and prior to testing of properties, the granules were dried to a constant mass. Measurements were carried out on granules having a diameter between 1 .18 mm and 4.75 mm.
  • compositions of the invention are set out below:
  • Granules were also formed from milled glass, CaCO3, coconut husk, sodium silicate and either lignosulfonate or pregelatinised starch (1-2 wt.%). These granules including an organic granulation binder were also found to have desirable absorbency and bulk density properties. Effect of the Coating Agent on Absorbencv
  • the foamed glass granules of the present invention display excellent absorbencies of over 60 wt.%, for example, over 70 wt.%, for example, over 80 wt.%, with preferred compositions and process conditions resulting in granules with absorbencies of over 90 wt.% or over 100 wt.%.
  • the absorbencies of some exemplary compositions using coconut husk fibres are depicted in Figures 3, 4 and 5.
  • the foamed glass granules of the present invention all display bulk density values of 0.33 kg/I or below, for example, 0.32 kg/I or below, 0.31 kg/I or below, or 0.30 kg/I or below.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Environmental Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Zoology (AREA)
  • Animal Husbandry (AREA)
  • Biodiversity & Conservation Biology (AREA)
  • Glass Compositions (AREA)

Abstract

L'invention concerne une composition de verre moussé, un procédé de préparation d'une composition de verre moussé sous la forme d'un granulé, et l'utilisation de ladite composition de verre moussé à titre de matériau absorbant. Une des utilisations envisagées de la composition de verre moussé est sous la forme d'un produit de litière pour animaux. Un produit de litière pour animaux comprenant des granulés de verre moussé absorbants est en outre décrit.
PCT/EP2016/055273 2015-03-13 2016-03-11 Granulés de verre moussé, leur préparation et utilisation WO2016146518A1 (fr)

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Publication number Priority date Publication date Assignee Title
CN112299770A (zh) * 2020-11-04 2021-02-02 郭伟江 一种保温隔热防火板及其制备方法和应用
US11013211B2 (en) 2014-01-25 2021-05-25 Pioneer Pet Products, Llc Method for making extruded granular absorbent and clumping granular absorbent product
WO2022066957A1 (fr) * 2020-09-23 2022-03-31 Jackson Marie D Systèmes et procédés pour système cimentaires auto-entretenus contenant des agrégats réactifs et de l'eau salée

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Publication number Priority date Publication date Assignee Title
CA808218A (en) * 1969-03-11 Werner H. Kreidl Cellular glass and method of making same
JP2000072480A (ja) * 1998-08-28 2000-03-07 Yutaka Kamaike 高吸水性塊状発泡ガラスの製造方法
WO2000061512A1 (fr) * 1999-04-12 2000-10-19 Quarzwerke Gmbh Procede de fabrication de granulats de verre multicellulaire
JP2001010832A (ja) * 1999-06-28 2001-01-16 Ishizuka Glass Co Ltd ガラス発泡材
WO2006042617A2 (fr) * 2004-10-14 2006-04-27 S & B Industrial Minerals Gmbh Procédé de production d'une litière pour animaux domestiques, absorbant en particulier les excrétions animales liquides
US20140338571A1 (en) * 2011-12-24 2014-11-20 Novagg Limited Aggregates

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA808218A (en) * 1969-03-11 Werner H. Kreidl Cellular glass and method of making same
JP2000072480A (ja) * 1998-08-28 2000-03-07 Yutaka Kamaike 高吸水性塊状発泡ガラスの製造方法
WO2000061512A1 (fr) * 1999-04-12 2000-10-19 Quarzwerke Gmbh Procede de fabrication de granulats de verre multicellulaire
JP2001010832A (ja) * 1999-06-28 2001-01-16 Ishizuka Glass Co Ltd ガラス発泡材
WO2006042617A2 (fr) * 2004-10-14 2006-04-27 S & B Industrial Minerals Gmbh Procédé de production d'une litière pour animaux domestiques, absorbant en particulier les excrétions animales liquides
US20140338571A1 (en) * 2011-12-24 2014-11-20 Novagg Limited Aggregates

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DATABASE WPI Week 200345, 16 January 2001 Derwent World Patents Index; AN 2003-472018, XP002758101 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11013211B2 (en) 2014-01-25 2021-05-25 Pioneer Pet Products, Llc Method for making extruded granular absorbent and clumping granular absorbent product
US11950565B2 (en) 2014-01-25 2024-04-09 Pioneer Pet Products, Llc Method for making extruded granular absorbent and clumping granular absorbent
WO2022066957A1 (fr) * 2020-09-23 2022-03-31 Jackson Marie D Systèmes et procédés pour système cimentaires auto-entretenus contenant des agrégats réactifs et de l'eau salée
CN112299770A (zh) * 2020-11-04 2021-02-02 郭伟江 一种保温隔热防火板及其制备方法和应用
CN112299770B (zh) * 2020-11-04 2022-09-09 郭伟江 一种保温隔热防火板及其制备方法和应用

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