KR20060024378A - Methods for producing low density products - Google Patents

Abstract

The method of preparing a low-density material and precursor for forming a low-density material. An aqueous mixture of inorganic primary component and a blowing agent is formed, the mixture is dried and optionally ground to form an expandable precursor. Such a precursor is then fired with activation of the blowing agent being controlled such that it is activated within a predetermined optimal temperature range. Control of the blowing agent can be accomplished via a variety of means including appropriate distribution throughout the precursor, addition of a control agent into the precursor, or modification of the firing conditions i.e. oxygen deficient or fuel rich environment, plasma heating etc.

Description

Method for producing low density products

The present invention relates to a process for the formation of low density products and, in particular, to methods and formulations for the synthetic production of synthesized expanded fine particles.

Any discussion of the prior art throughout this specification assumes that such prior art is not widely known or acknowledged as part of the general general knowledge in the art.

Ceno spares are spherical inorganic hollow fine particles (microspheres) found in fly ash generated as a by-product of coal-fired power plants. Ceno spares typically make up about 1 to 2% of the fly ash, and “encapsulated” xeno spares are widely commercially available. The composition, form, size, shape and density of senofares provides particular advantages in the formulation and preparation of many low density products.

One of the characteristic properties of Cenospare is its very high chemical durability. This very high chemical durability is understood as the content of alkali metal oxides, especially sodium oxide, in its composition is very low. Thus, the low density composites made from the captured senofares have desirable properties of high strength to weight ratio and chemical specificity. Chemical inertness is particularly important in Portland cement applications where proper chemical inertness plays an important role in providing durable cement products. Thus, the captured senofares have been found to be particularly useful in building materials, and in general applications that may encounter corrosive environments.

Despite the known usefulness, the captured senofares are expensive and difficult to purchase, limiting their widespread use. Recovering large amounts of senofares from fly ash is a labor intensive and expensive process. Improving the collection process may increase the recovery of senofare from the fly ash, but due to the cost of improved recovery it is not economically viable.

It is also possible to increase the yield of xeno spares in fly ash by varying the combustion conditions of the thermal power plant, but the combustion conditions of the thermal power plant are optimized for coal combustion rather than the production of xeno spares. It is not economically feasible to increase the production efficiency of senofare while losing coal combustion efficiency.

Various methods for producing microspheres have been disclosed in the prior art. The initial method of preparing glassy microspheres comprises mixing sodium silicate and borax with a suitable blowing agent, drying and pulverizing the mixture, adjusting the size of the pulverized particles, and calcining the particles. However, because the method requires the use of expensive starting materials (eg borax), the microspheres obtained are inexpensive. Moreover, the product has a high content of sodium oxide in the glassy composition, resulting in poor chemical durability.

U.S. Patent No. 3,365,315 discloses the preparation of glassy microspheres from glass beads by heating in the presence of water vapor at a temperature of about 1,200 ° C. This method requires excessive use of preformed amorphous glass as starting material.

U.S. Patent No. 2,978,340 discloses a process for forming vitreous microspheres from discrete solid particles consisting essentially of alkali metal silicates. Microspheres are formed by heating alkali metal silicates in the presence of a gasifying agent such as urea or Na ₂ CO ₃ at a temperature in the range from 1,000 to 2,500 ° F.

U.S. Patent Application No. 2001/0043996 (corresponding to European Patent Application No. 1156021) discloses a spray combustion method for producing fine hollow spheres having a diameter of 1 to 20 mu. However, this method is not suitable for producing fine hollow spheres with diameters similar to the diameters of known xeno spares (ie, about 200 microns). In the spray combustion method, rapid steam explosion destroys large particles, which prevents the formation of fine hollow spheres larger than about 20 microns in diameter.

U.S. Patent Application 2002/0025436 discloses a process for producing solid phase microspheres from fly ash. This method is said to improve the ellipsoid uniformity of fly ash particles and to provide a fly ash ellipsoid with a density of about 1.8 g / cm 3.

US Pat. No. 4,826,788 describes a method of using two blowing agents activated at different temperatures to produce large foam glass granules with a diameter of at least 1 mm. However, the blowing agent mentioned in the patent is limited to the blowing agent mentioned in the patent, and one of the two blowing agents must be an oxygen generating agent.

Generally speaking, conventional techniques for forming synthesized expanded fine particles involve the firing of inorganic materials in the presence of blowing agents, gasifying agents or foaming agents.

Such blowing agents, vaporizing agents or foaming agents should only be activated when the material producing the fine particles is in the proper form, ie liquid. However, it is often very difficult to match the blowing agent to a material capable of forming fine particles using the blowing agent in the most efficient manner.

It would be desirable to have a system that allows for a high degree of control compared to the method.

It is an object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art or to provide a useful alternative.

Summary of the Invention

In a first aspect, the present invention provides a method for preparing a precursor comprising forming an aqueous mixture of an inorganic main component and a blowing agent, drying the mixture, and optionally grinding to a predetermined size;

Firing the precursor to activate the blowing agent, wherein activation of the blowing agent is controlled to activate the blowing agent in a predetermined optimum temperature range, thereby expanding the precursor and forming a low density material. to provide.

In a preferred embodiment, the control of the blowing agent is achieved by providing a control agent in the precursor that preserves and / or protects the blowing agent until the mixture reaches the above-mentioned optimum temperature range.

Modulators may be provided in a number of forms. In one form, the modifier includes a material that modulates the activation of the blowing agent by changing the environment of the precursor in response to specific process conditions. For example, modifiers may be present in the form of additional blowing agents. To illustrate, the precursor formulation may primarily comprise a primary blowing agent that acts to expand the precursor material and form expanded fine particles. Modifiers in the form of secondary and tertiary blowing agents can be included in the precursor mixture. These blowing agents can be activated at lower temperatures than the primary blowing agents. Many blowing agents are activated by oxidation. Activation of the tertiary and / or secondary blowing agents controls the activation of the primary blowing agents by removing oxygen from the process environment. As will be apparent to one of ordinary skill in the art, this allows for the preservation and release of the blowing agent in the desired optimum temperature range which provides better control and more efficient use of the blowing agent in the process.

Control of the blowing agent can be achieved by various means. For example, the process can be carried out in an oxygen deficient environment to reduce exposure of the foaming components to oxygen. When the precursor mixture reaches the optimum temperature range, oxygen can be introduced into the process to activate the blowing agent.

Another method is to carry out the firing process in a fuel rich manner, ie less oxidative. Other firing mechanisms, such as plasma heating, can be used with the appropriate dosing of O ₂ deficient gas or O ₂ rich gas to control activation of the blowing agent.

In a further embodiment, preservation of the blowing agent can be physically achieved. Dispersion of the blowing agent throughout the precursor particles may allow at least some of the foaming components to remain in the precursor core away from the surface. When such precursor particles are heated, the surface temperature will rise and the core temperature will drop below the surface temperature. This temperature difference is manipulated so that the blowing agent is activated only when substantially all precursor particles reach the optimum temperature.

In this regard, the optimum temperature range is the temperature at which the precursor mixture reaches the optimum viscosity for the expansion process. The optimum temperature range depends on a number of variables including the composition of the inorganic main component, the composition of the blowing agent and the regulator, the precursor particle size, and the desired density of the resulting low density material.

Preferably, the low density material is made in the form of fine particles, most preferably with a particle size of up to 1,000 microns.

In a second aspect, the present invention provides a method for preparing an inorganic active ingredient comprising the steps of (a) providing an inorganic active ingredient,

(B) forming an aqueous mixture of inorganic main ingredient, blowing agent and modifier, wherein the blowing agent and modulator are selected to modulate the activation of the blowing agent so that the blowing agent is activated at a predetermined optimum temperature range; and

A method of forming a precursor for a low density material, comprising the step (c) of drying the mixture to provide an expandable precursor for forming a low density material.

In a third aspect, the present invention provides a method for preparing an inorganic active ingredient comprising the steps of (d) providing an inorganic active ingredient,

(E) forming an aqueous mixture of the inorganic main component and the blowing agent, wherein the blowing agent controls the activation of the blowing agent upon firing of the precursor so that the blowing agent is selected to be activated in a predetermined optimum temperature range and / or distributed in the precursor; and

A method of forming a precursor for a low density material is provided, comprising the step (f) of drying the mixture to provide an expandable precursor for forming a low density material.

In a fourth aspect, the present invention provides an expanded fine particle comprising an expandable inorganic main component, a blowing agent adapted to activate and expand the main component, and a regulator selected to regulate activation of the blowing agent so that the blowing agent is activated in a predetermined optimum temperature range. It provides a precursor suitable for the preparation of the compound.

In a fifth aspect, the present invention relates to an expandable inorganic main component and a foaming agent selected and / or distributed within the precursor to control the activation of the blowing agent to produce expanded fine particles upon firing of the precursor and to be activated at a predetermined optimum temperature range. It provides a precursor suitable for the production of expanded fine particles, comprising.

In a sixth aspect, the present invention provides one or more blowing agents that are activated under certain conditions to release foaming gas and produce expanded fine particles, and the conditions are adjusted to allow activation in a predetermined optimum viscosity range of the inorganic mixture. It provides a method of controlling the activation of the blowing agent in the inorganic mixture to produce expanded fine particles, comprising causing to occur.

In a seventh aspect, the invention comprises a primary blowing agent and a predetermined amount of miscibility control agent, wherein when the blowing agent component is included in the expandable mixture, the controlling agent is activated in advance or simultaneously with the blowing agent to control and preserve the blowing agent. It is possible to provide a foaming component for producing expanded fine particles.

In a preferred embodiment, the modifier is activated at a lower temperature than the blowing agent. Modulators can act to alter the process environment and make them less involved in the activation of the blowing agent. For example, modulators can act to alter the oxygen content for removal of oxygen from the process environment so that such environment is less involved in oxidatively activatable blowing agents.

In another preferred form, the foaming component / foaming agent comprises a series of foaming compounds adapted to be activated sequentially over a range of process conditions.

In another aspect, the present invention provides a process for providing one or more blowing agents that are activated under certain conditions to release foaming gases and produce expanded microparticles, and by adjusting such conditions, activation of the inorganic mixture in a predetermined optimum viscosity range is achieved. It provides a method of controlling the activation of the blowing agent in the inorganic mixture to produce expanded fine particles, comprising causing to occur.

The inorganic mixture melts at relatively high temperatures. It is important that the blowing agent is activated only when the inorganic mixture is present at the optimum viscosity, as it will be evident to one of ordinary skill in the art, to provide the maximum yield from the expansion process. Accordingly, the present invention provides a mechanism for adjusting the blowing agent such that the blowing agent is activated at the optimum viscosity of the inorganic mixture, that is, at a specific temperature range.

Unless stated otherwise in the specification and claims, the terms "comprises", "comprising," and the like are intended to be construed to include, without limitation, in a comprehensive sense as opposed to limiting or limiting.

As used herein, the term “synthesized / expanded fine particles” means fine particles synthesized as the main target product of the synthesis process. The term does not include entrapped senospares, which occur, for example, simply as a byproduct of coal combustion in coal-fired power plants.

The terms “microspheres” and “fine particles” as used throughout this specification are intended to encompass any discrete fine particles that are almost spherical, including fine particles that are not geometrically substantially spherical.

As used herein, the term “precursor” means an aggregate or particle prepared from a suitable formulation prior to expansion to form one or more expanded fine particles. The term "modulator" means a component included in the precursor that modulates the activation of the foaming component.

As used herein, the term "main ingredient" usually means the main ingredient of a formulation / precursor in the sense that its content exceeds the content of other ingredients. Moreover, the term "inorganic main ingredient" means that the main ingredient consists essentially of an inorganic material. However, small amounts (eg, up to about 10% by weight) of other materials may also be included in the inorganic main component.

As used herein, the term "activation" refers to conditions, such as temperature, oxidation-reduction of oxides present in the formulation, and heat treatment (eg, oxygen) in which the foaming component is activated to release its foaming gas. Partial pressure).

Preferred methods of the present invention advantageously provide a means for producing expanded fine particles in good yield from a widely available inexpensive starting material. Thus, in its preferred form, the process of the present invention reduces the total cost of production of fine particles, thereby leading to the construction industry, and polymers, where their use is relatively limited due to the enormously expensive price and difficulty of availability of currently available xenospares. It is possible to broaden its use in all filler fields such as composites. The present invention recognizes that it is particularly important to control the activation of the blowing agent (s) when achieving reliable synthesis of expanded fine particles from a wide range of materials.

Preferred features of all aspects of the invention are described in more detail below.

How to Form Precursors for Expanded Fine Particles

Precursors for preparing expanded fine particles can be prepared by combining the main component, the foaming component and, optionally, the regulator in an aqueous mixture. This aqueous mixture is then dried to produce agglomerated precursors.

As mentioned above, the present invention provides a method for preparing a precursor comprising mixing and drying steps. The resulting precursor is generally a substantially solid flocculating mixture of its constituent materials.

Typically, the mixing step provides an aqueous dispersion or paste that is subsequently dried. The mixing can be carried out by conventional means used for mixing the ceramic powder. Examples of preferred mixing techniques include, but are not limited to, shaking tanks, ball milling, uniaxial and biaxial mixing and friction milling.

If appropriate, certain mixing aids (eg surfactants) may be added in the drying step. Surfactants can be used, for example, to assist in mixing, suspending and dispersing the particles.

Drying is usually carried out in the range of 30 to 600 ° C. and can be carried out in about 48 hours or less depending on the drying technique used. All kinds of dryers commonly used in the drying industry of slurries and pastes can be used in the present invention.

Drying can be performed, for example by the batch type process using a fixed bed or a container. Alternatively, drying may be carried out in a spray dryer, fluid bed dryer, rotary dryer, rotary tray dryer or flash dryer.

Preferably, the mixture has a water content of the resulting aggregated precursor of less than about 14 weight percent, more preferably less than about 10 weight percent, more preferably less than about 5 weight percent, and even more preferably about 3 weight percent or less To dry. It has been found that above 14% by weight of the precursor tends to explode into particulates upon firing. The inventors understand that such an explosion is caused by a rapid vapor explosion in the presence of excess water.

Thus, the resulting precursor should preferably be substantially dried, although a small amount of residual moisture may be present after the solution based process for its formation. Indeed, small amounts of moisture can assist in binding the particles in the precursor together when the particles in the precursor are water reactive.

Preferably, the average particle size of the dried precursor particles ranges from 10 to 1000 microns, more preferably from 30 to 1000 microns, more preferably from 40 to 500 microns, even more preferably from 50 to 300 microns. The particle size of the precursor may, of course, be approximate, but will be related to the particle size of the resulting synthetic microspheres. If desired, standard grinding / sizing / sorting techniques can be used to achieve this preferred average particle size.

Drying is most preferably carried out using a spray dryer with an aqueous feed. Spray drying has been found to have several advantages when used in the present invention.

Precursor Formation Method Using Spray Dryer

As mentioned above, the present invention encompasses a variety of techniques for controlling the activation of the blowing agent to be activated at the optimum point in the manufacturing process. Such control can be accomplished by incorporating a series of modulators in the precursor formulation. Another embodiment includes a series of regulators and / or blowing agents such that there is sufficient foaming / expanding gas available at the optimum temperature. In one embodiment, a series of blowing agents may be used that are activated continuously as the temperature rises.

A further aspect includes dispersing the blowing agent throughout the precursor so that while firing the precursor, the blowing agent distributed near the surface is exposed to high temperature but the blowing agent near the core of the precursor is "physically" protected. To illustrate, the thermal conductivity of the formulation results in a delay between the application of heat on the precursor surface and the heat rise in the precursor core. Thus, the blowing agent present in the precursor core will not be activated until the major part of the precursor particles has already reached its optimum temperature.

In addition, as mentioned above, many blowing agents are activated by oxidation. The particles in the precursor core are not exposed to oxygen to the same extent as the blowing agent on the surface and protect the blowing agent in the particle core.

Surprisingly, the applicant has found that the spray dryer is not only useful for forming the precursor into expanded fine particles, but also excellent in providing the above-described optimum dispersion of blowing agent in the precursor. Without wishing to be bound by any particular theory, it is likely that water soluble blowing agents tend to appear on the surface during spray drying production techniques. No water soluble blowing agent tends to remain in the core. Thus, it is possible to design blowing agent mixtures that provide initial, subsequent and final activation depending on their water solubility. One example may be a sugar that is useful as a blowing agent but is water soluble. During spray drying techniques, these blowing agents tend to migrate to the precursor surface. Silicon carbide, a useful blowing agent, on the other hand, is water insoluble and does not migrate to the precursor surface.

Spray dryers are described in a number of standard literature [Industrial Drying Equipment, C.M. van't Land; Handbook of Industrial Drying 2nd Edition, Arun S. Mujumbar, and is known to those of ordinary skill in the art.

In addition to the advantages described above, it is generally desirable to synthesize expanded fine particles having a predetermined average particle size and a predetermined (preferably narrow) particle size distribution. The use of spray dryers in the present invention has been found to reduce the need for sizing / classifying precursors or ultimately synthetic expanded fine particles. Spray drying has the added advantage of allowing high throughput of materials and fast drying time. Thus, in a preferred embodiment of the invention, the drying step is carried out using a spray dryer.

Particle size and particle size distribution were determined to be affected by one or more of the following parameters in the spray drying process:

Inlet slurry pressure and speed (particle size tends to decrease with increasing pressure),

-Design of the sprayer (rotary sprayer, pressure nozzle, two fluid nozzles, etc.),

-Design of gas inlet nozzles,

The volumetric flow rate and flow pattern of the gas and

Slurry speed and effective slurry surface tension.

Preferably, the aqueous slurry supplied to the spray dryer contains 25 to 75% (w / v) solids, more preferably 40 to 60% (w / v) solids.

In addition to the components described above, the aqueous slurry may contain additional processing aids or additives to enhance mixing, fluidity or droplet formation in the spray dryer. Suitable additives are known in the spray drying art. Examples of such additives are sulfonates, glycol ethers, cellulose ethers, and the like. They may be contained in an aqueous slurry in an amount of 0 to 5% (w / v).

In the spray drying process, the aqueous slurry is usually pumped to the nebulizer at a predetermined pressure and temperature to form slurry droplets. The nebulizer may be one or a combination of the following: an atomizer based on a rotary atomizer (centrifugal spray), a pressure nozzle (hydraulic spray) or a two-liquid pressure nozzle, where the slurry is mixed with another fluid (air spray) ).

In order to ensure that the droplets formed have a suitable size, the nebulizer may also be treated with an annular mechanical or sonic pulse. Atomization can be effected from the top or bottom of the dryer chamber. The hot drying gas may be injected into the dryer in the same direction or in the reverse direction of the spraying direction.

It has been found that by controlling spray drying conditions, the average particle size distribution and precursor particle size distribution of the precursors can be controlled. For example, rotary atomizers have been found to produce a more uniform aggregate particle size distribution than pressure nozzles. In addition, rotary atomizers enable higher feed rates suitable for abrasive materials, and blocking or disturbances can be ignored. In some embodiments, a combination of known spraying techniques can be used to achieve aggregated precursors with the desired properties.

Spray droplets of the slurry are dried in a spray dryer for a predetermined residence time. The residence time can affect the average particle size, particle size distribution and moisture content of the resulting precursor. The residence time is preferably adjusted to provide the desired properties of the precursor as described above. The residence time can be controlled by the water content of the slurry in the spray dryer, the droplet size (total surface area), the dry gas inlet temperature and gas flow pattern and the particle flow path in the spray dryer. Preferably, the residence time in the spray drier ranges from 0.1 to 10 seconds, with longer residence times exceeding 2 seconds being more preferred.

Preferably, the inlet temperature in the spray dryer is in the range from 300 to 600 ° C. and the outlet temperature is in the range from 90 to 220 ° C.

Spray drying advantageously produces precursors having such a narrow particle size distribution. As a result, the synthetic expanded fine particles that produce these precursors will have similarly narrow particle size distributions and constant properties for subsequent use.

A further surprising advantage of using a spray dryer is that the resulting precursor has an improved internal particle distribution of the components. The sprayed droplets remain in the spray drier, and the moisture is quickly discharged from the inside to the outside, forming a concentration gradient of the soluble species in the aggregate, and the relatively soluble species are more concentrated in the outward direction. Another advantage of spray drying is the formation of dried organized coagulation precursors according to the process of the invention (eg prefoaming). The trapped gas may further expand during the foaming process, further lowering the density of the product that cannot be achieved by multiple blowing agents. By these optional and novel methods, the low temperature gas forming compound is added to the precursor before the drying process. Gas-forming compounds can be activated by physical means, for example by degassing (reverse temperature solubility) due to a decrease in surface tension or by chemical means. An example of chemical vaporization at low temperatures is the decomposition of carbonates to CO ₂ by changes in pH or the use of suitable organic compounds such as air trapping agents commonly used in spheres.

For efficient and reliable synthesis of micro hollow spheres, the precursor should ideally comprise a high concentration of glass forming material at the surface, which can form a molten glassy surface during firing. In addition, the precursor should ideally comprise a certain concentration of blowing agent in the vicinity of the core, which can release the foaming gas for capture in the glassy surface during firing. Depending on the careful selection of the material, this ideal internal particle distribution can be achieved using a spray drying method.

Inorganic main ingredient

Preferably, the amount of the inorganic main component is at least 40% by weight, more preferably at least 50% by weight, more preferably at least 60% by weight, particularly preferably 70% by weight, based on the total dry weight of the aggregated precursor. As mentioned above, More preferably, it is 80 weight% or more.

The preferred ratio of main component to other components, such as blowing agent, will depend on the composition of each of these components. Typically, the ratio of main ingredient to blowing agent will range from 1,000: 1 to 10: 1, more preferably 700: 1 to 15: 1, particularly preferably 500: 1 to 20: 1.

Preferably, the inorganic main component comprises one or more materials selected from inorganic oxides, nonoxides, salts or mixtures thereof. Such materials may be industrial and / or household by-products, minerals, rocks, clays, technical grade chemicals or mixtures thereof. One of the advantages of the present invention is the synthesis of micro hollow spheres from inexpensive industrial and / or household waste. Thus, the inorganic main components are fly ash, bottom ash, blast-furnace slag, paper ash, waste glass (e.g., soda lime glass, borosilicate glass or other). Waste glass), waste ceramics, kiln dust, waste fiber cement, concrete, incinerator, diatomaceous earth, silica sand, fumed silica, or mixtures thereof.

Preferably, the inorganic main component can form a viscoelastic liquid when heated to a predetermined temperature. Such viscoelastic liquids are preferably glass forming liquids.

Preferably, the inorganic main component comprises one or more compounds in oxide form, which can form most of the glass phase. The non-oxide component oxidizes or becomes part of the glass phase, except in the absence of halides or the like, which are present in the dissolved state but are not oxidized.

In one preferred embodiment, the inorganic main component comprises one or more silicate materials. Silicate materials are well known to those skilled in the art. In general, they are materials having a major component of silica (SiO ₂ ) (ie, greater than about 30%, preferably greater than about 50%, more preferably greater than 60%). In most cases, alumina is also the main oxide component of the silicate material. Thus, the term silicate in the present invention includes all aluminosilicate materials suitable as main components.

The amount of silica and alumina in the silicate material is source dependent and may even vary within the same source. For example, the fly ash will contain varying amounts of silica and alumina depending on the type of coal used and the combustion conditions. Preferably, the weight ratio of silica (SiO ₂ ) to alumina (Al ₂ O ₃ ) is greater than about 1. Typically, the silicate material for use in the preferred embodiment of the present invention is 30 to 95% by weight of SiO ₂ ; 0 to 45 weight percent (preferably 2 to 45 weight percent) of Al ₂ O ₃ ; About 30% or less (preferably about 15% or less) divalent metal oxides (eg, MgO, CaO, SrO, BaO); Up to about 50 weight percent monovalent metal oxides (eg, Li ₂ O, Na ₂ O, K ₂ O) and up to about 20 weight percent of other metal oxides (eg, SnO ₂ , MnO ₂ , Fe ₂ O _3, etc. As well as metal oxides present in a plurality of oxidation states.

Typical silicates that can be used in this aspect of the invention include fly ash (type F fly ash and type C fly ash, etc.), waste glass, bottom ash, blast-furnace slag, paper ash. ash), basalt rock, andesite rock, feldspar, silicate clay (e.g. kaolin, ocher, beadite clay, bentonite clay, white clay, refractory clay, etc.), bauxite, obsidian, volcanic ash, volcanic rock, volcanic glass, Geopolymers or mixtures thereof.

Silicates as described above can form most of the inorganic active ingredient. For example, the silicates may form at least 50%, at least 70%, or at least 90% by weight of the inorganic main component, based on the total weight of the inorganic main component.

Fly ash, soda lime waste glass, andesite rock, basalt rock and / or clay are the preferred feedstocks for the inorganic main component. Fly ash is a particularly preferred inorganic active ingredient because it is inexpensive and widely available. In one form of the invention, the main component contains at least 5% by weight, more preferably at least 10% by weight, of fly ash, based on the total weight of the main component. In another aspect of the present invention, the inorganic main component comprises at least 50%, at least 70%, or at least 90% by weight fly ash, based on the total amount of the inorganic main component. In some embodiments of the invention, the inorganic main component may comprise a geopolymer, which is formed when the silicate is contacted with an aqueous solution of a metal hydroxide such as NaOH or KOH. Geopolymers are well known in the art.

The inorganic main component may or may not be calcined. The term “calcination” means heating the inorganic material to a predetermined calcination temperature for a predetermined time in the air to oxidize or pre-react certain component (s). Calcination of the inorganic material may be advantageous in the present invention because the foaming (expansion) process may be sensitive to the redox state of the multivalent oxide (s) present in the inorganic material. Without wishing to be bound by theory, it is believed that activation of the blowing agent is affected by the release of oxygen (eg, by redox reactions) from the polyvalent oxide (s) present in the inorganic material. For example, the carbonaceous blowing agent reacts with oxygenation released from ferric oxide (Fe ₂ O ₃ ) to form CO _x (where x may be 1 or 2 depending on the carbon oxidation state), which is further iron ferric oxide Reduced to (FeO). Release of CO _x from the blowing agent expands the microspheres. Therefore, the relative amount of ferric oxide is increased by precalcination of the inorganic material in air, which is used as an oxygen source for the blowing agent to reduce the density of the fine particles by generating more gas.

In addition, calcination may promote partial pre-reaction of the oxide component and / or cause partial magnetization in the inorganic material which may be advantageous for producing high quality fine particles.

If high chemical durability is required, the inorganic main component is preferably a low alkali material. By "low alkali material" is meant a material having an alkali metal oxide content of less than about 10% by weight. In this aspect of the invention, a high alkali material can also be included in the inorganic main component. Thus, waste glass powders, such as soda lime glass (often called cullet) with an alkali content of about 15% by weight or less, may also be included.

Preferably, the inorganic main component may have an average primary particle size in the range of 0.01 to 100 microns, more preferably 0.05 to 50 microns, more preferably 0.1 to 25 microns, more preferably 0.2 to 10 microns. Preferred particle sizes can be achieved by suitable grinding and sorting. All forms of grinding, milling and overall size reduction techniques used in the ceramic industry are available for the present invention. Without being limited to other size reduction methods used for brittle solids, preferred methods according to the present invention are ball milling (wet and dry), high energy centrifugal milling, jet milling and friction milling. If more than one inorganic material is used, the multiple components may be simultaneously ground together. In one method of the invention, all the constituent materials of the aggregated precursors are co-milled together (eg, wet ball mill) prior to mixing.

Foaming ingredients

Blowing agents used in the present invention are materials which liberate the foaming gas upon heating by one or more of combustion, evaporation, sublimation, thermal decomposition, vaporization or diffusion. The effervescent gas can be, for example, CO ₂ , CO, O ₂ , N ₂ , N ₂ O, NO, NO ₂ , SO ₂ , SO ₃ , H ₂ O or mixtures thereof. The effervescent gas preferably comprises CO ₂ and / or CO.

Preferably, the amount of foam component is in the range of 0.05 to 10% by weight, more preferably 0.1 to 6% by weight, more preferably 0.2 to 4% by weight, based on the total dry weight of the precursor. The exact amount of foam component will depend on the inorganic main component, the type of blowing agent and the required density of the final microhollowers.

In one embodiment, the foaming component comprises a primary blowing agent and a secondary blowing agent. The primary blowing agent has a first activation temperature and the secondary blowing agent has a second activation temperature lower than the first activation temperature. In other words, in use, the secondary blowing agent is activated initially with increasing temperature, and then the primary blowing agent is activated. This preserves the primary blowing agent.

Preferably, the primary blowing agent is powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, carbohydrates (e.g. sugars, corn syrup, starch, etc.), PVA (polyvinyl alcohol), various amines, carbonates, Carbides (e.g. silicon carbide, aluminum carbide, etc.), sulfates, sulfides, nitrides (e.g. aluminum nitride, silicon nitride, boron nitride, etc.), nitrates, polyols, glycols, glycerin, and mixtures thereof . Silicon carbide and carbon black are particularly preferred primary blowing agents.

Preferably, the secondary blowing agent is carbon, carbonaceous polymer organics, oils, carbohydrates (e.g. sugars, corn syrup, starch), PVA, various amines, carbonates, sulfates, sulfides, nitrides, nitrates, polyols, glycols, Glycerin or mixtures thereof. Carbon black, sugar, corn syrup and starch are particularly preferred secondary blowing agents.

In another aspect of the invention, the foaming component comprises further blowing agents in addition to the above mentioned primary and secondary blowing agents. These additional blowing agents are designated as blowing agents such as tertiary and quaternary having activation temperatures such as third, fourth and the like.

Thus, in one further embodiment the foaming component comprises a tertiary blowing agent having a third activation temperature, wherein the tertiary activation temperature is lower than the first activation temperature. Preferably, the third activation temperature is also lower than the second activation temperature. The tertiary blowing agent can be selected from carbonaceous polymeric organics (eg, sugars, corn syrups, starches), PVAs, various amines, sulfates, sulfides, nitrides, nitrates, polyols, glycols, glycerin and mixtures thereof. Sugars, corn syrups and starches are particularly preferred tertiary blowing agents.

Preferably, and especially when the blowing agent is water-insoluble, the blowing agent has an average particle size of about 10 microns.

The use of multiple blowing agents has been found to have particular advantages in the synthesis of expanded fine particles. When providing control of the foaming (expansion) process, expanded fine particles can be reliably synthesized from a variety of readily available and inexpensive inorganic materials. In addition, this maximizes the efficiency of the high quality (and relatively expensive) primary blowing agent, which reduces the cost of synthetic preparation of expanded fine particles.

Without being bound by theory, it is believed that the primary blowing agent produces most of the gas during the foaming (expansion) process. Secondary (and, optionally, tertiary, quaternary, etc.) blowing agents may be used, for example, by evaporation and / or oxidation, of the primary blowing agent before the precursor material is sufficiently molten to capture It acts as a sacrificial material by reducing or preventing premature consumption.

For example, preferred blowing agent compositions include silicon carbide as the primary blowing agent and carbon or powdered coal as the secondary blowing agent. The carbon acts as a sacrificial blowing agent and starts to oxidize first to release oxygen from the carbide until the precursor melts. Once the precursor is melted, most of the CO and CO ₂ gases produced by the oxidation of the carbide are trapped in the molten precursor.

Still other blowing agent compositions include silicon carbide as primary blowing agent, carbon as secondary blowing agent and sugars as tertiary blowing agent. Without being bound by theory, sugars begin to oxidize first to prevent oxidation of carbon and carbides, carbon begins to oxidize to prevent oxidation of carbides, and finally carbides are primarily involved in the expansion (expansion) of fine particles. Oxidize with CO and CO ₂ . One advantage of the process of the invention is to reduce the overall cost of the blowing agent. Sugars are less expensive than carbon, and silicon carbide is much cheaper than sugars and carbon. By using multiple blowing agents, the amount of expensive silicon carbide required for the production of a given low density product is significantly reduced. 2 shows TGA (thermal gravity analysis) of sugar, carbon and silicon carbide in air. The ascending activation temperature starts with sugar followed by carbon and finally silicon carbide.

This new mixture of blowing agents uses inexpensive sacrificial blowing agents (eg, sugar, carbon and / or powdered coal) to maximize the efficiency and foaming performance of more expensive primary blowing agents (eg, silicon carbide).

As mentioned above, a further and important advantage is realized when preparing precursors using spray drying methods. Advantageous internal particle distributions of the primary and secondary blowing agents can be achieved by venting relatively water-soluble species out of the precursor during spray drying using the mechanism described above.

Therefore, when using a relatively water insoluble primary blowing agent and a relatively water-soluble secondary blowing agent, the secondary blowing agent can be moved toward the precursor surface to obtain a uniformly dispersed primary blowing agent. For primary and secondary blowing agents separated in this manner, the secondary blowing agent can more effectively "remove" oxygen from the primary blowing agent within a critical period during firing where the glassy surface has not yet formed around the precursor. This removal effect protects the primary blowing agent from premature consumption, thereby maximizing its foaming performance after (or during) the formation of the glassy surface.

Sugars are examples of useful secondary blowing agents. The sugar is soluble in water and will migrate in the outward direction of the precursor during spray drying. At the same time, the sugar will be converted to carbon at the spray drying temperature, producing a microdispersion of carbon particles throughout the outer portion of the precursor. This fine dispersion of carbon particles acts as an effective secondary (sacrificial) blowing agent by removing oxygen from the primary blowing agent (eg, silicon carbide) during the initial firing.

In addition, organic compounds, such as sugars and starches, help to bind the aggregated precursors together. Thus, materials such as sugar and starch can act as both binder and blowing agent in the present invention.

Regulator

The secondary and tertiary blowing agents mentioned above act as regulators to protect and preserve the primary blowing agent in the precursor formulation. One of ordinary skill in the art will recognize other materials that can be included in the precursor formulation and can serve to regulate activation of the blowing agent, for example, by removing oxygen from the process environment.

Binder

In a preferred embodiment of the invention, the binder / binders (or binders) may mix an inorganic main component with a blowing agent. The main function of the binder is to intimately bind the silicate particles in the precursor together. The binder may also be selected to react with the silicate to lower the viscosity of the resulting glassy fine particles at the firing temperature.

In general, any chemicals that react with and / or adhere to the inorganic main component may be used as the binder. The binder can be any commercially available material used as a binder in the ceramic industry.

Preferably, the binder is an alkali metal silicate (eg sodium silicate), alkali metal aluminosilicate, alkali metal borate (eg sodium tetraborate), alkali metal or alkaline earth metal carbonate, alkali metal or alkaline earth metal nitrate, alkali metal Or alkaline earth metal nitrites, boric acid, alkali or alkaline earth metal sulfates, alkali or alkaline earth metal phosphates, alkali or alkaline earth metal hydroxides (e.g., NaOH, KOH or Ca (OH) ₂ ), carbohydrates (e.g., sugars, Starch, etc.), colloidal silica, inorganic silicate cement, portland cement, lime cement, phosphate cement, organic polymers such as polyacrylates, or mixtures thereof. In some cases, fly ashes such as type C or type F ultrafine fly ashes may also act as binders.

In some cases (eg sugars, starches, etc.) the same material may have the dual nature of the blowing agent / binder as described above, but typically the binder and blowing agent are different.

As used herein, the term “binder” or “binder” includes all the binders mentioned above as well as the reaction product in situ of these binders with other components in the aggregate. For example, an alkali metal hydroxide (eg, NaOH) will react with at least a portion of the inorganic main component comprising the silicate in situ to produce an alkali metal silicate. Sodium hydroxide can also form sodium carbonate upon exposure to ambient air containing CO ₂ , and the rate of the reaction increases at high temperatures (eg 400 ° C.). The sodium carbonate obtained can be reacted with silicate to form sodium silicate.

Preferably, the amount of binder is in the range of 0.1 to 50% by weight, more preferably 0.5 to 40% by weight, particularly preferably 1 to 30% by weight, based on the total dry weight of the aggregate precursor.

It has already been mentioned that it is desirable to have the binder in the outward direction of the precursor so that the binder forms a molten surface during firing. The formation of such a molten surface should preferably take place before or during the activation of the foaming component, in particular during the activation of the primary blowing agent. This formation of the molten surface not only provides additional protection for the blowing agent in the precursor, but also advantageously provides low density synthetic expanded fine particles.

Using spray drying methods to form aggregated precursors, it was unexpectedly found that the concentration of binder (also blowing agent) in different regions of the aggregated precursor could be controlled by appropriate choice of solubility limitations of these components. Thus, when using a spray drying method, the binder preferably has a relatively high water solubility so that it is more concentrated outside of the flocculent precursor to form a molten surface during subsequent firing. Alkali compounds such as alkali hydroxides or in particular compounds of sodium silicate or sodium aluminosilicate are preferred binders in this regard because they are water soluble and can therefore move outwardly in the aggregate precursor.

Method of Forming Synthetic Expanded Fine Particles

Precursors prepared by the methods described above can be used for the synthesis of expanded fine particles by firing at a predetermined temperature profile.

Preferably, the temperature profile during firing melts the precursor into the melt, reduces the viscosity of the melt, seals the surface of the precursor and promotes the expansion of gas in the melt to form bubbles. In addition, the temperature profile should preferably maintain the melt at a temperature and time sufficient for the gas bubbles to coalesce and form a single primary void. After foaming, the newly expanded particles cool rapidly, thus forming hollow glassy fine particles. Thus, the temperature profile is preferably provided by a furnace having at least one temperature region with an upward or downward air stream, for example a dropping tube furnace, a vortex furnace, a fluidized bed furnace or a fuel fired furnace. . Fuel-fired furnaces include a furnace form in which precursors are introduced directly into one or a plurality of combustion zones causing expansion or foaming of the particles. This type of furnace is preferred because it has the advantage of heating the particles directly to high temperature directly. The heat source may be electricity or may be supplied by burning fossil fuels such as natural gas or fuel oil. However, the method by combustion of natural gas is a preferred heating method because it is more economical than electrical heating and cleaner than combustion of fuel oil.

Typically, the maximum firing temperature in the firing step (b) is in the range of 600 to 2,500 ° C., preferably 800 to 2,000 ° C., more preferably 1,000 to 1,500 ° C., particularly preferably 1,100 to 1,400 ° C. However, it is understood that the required temperature profile will vary depending on the type of inorganic principal and foam components used.

Preferably, the exposure time to the above-mentioned maximum firing temperature will be 0.05 to 20 seconds, more preferably 0.1 to 10 seconds.

Synthetic fine hollow phrase

The invention further provides synthetic fine hollow spheres obtained by the process described above. Such fine hollow spheres are inexpensive to manufacture and can be advantageously used as an inexpensive alternative to the collected xenospares. Synthetic hollow microparticles according to the present invention typically comprise a substantially spherical wall having a closed shell (pore) structure. Synthetic hollow microparticles preferably have one or more of the following characteristics, which are the general characteristics of the captured xeno spares.

(Iii) an aspect ratio of about 0.8 to 1;

(Ii) a pore volume of about 30 to 95% based on the total volume of the microspheres;

(Iii) a wall thickness of about 5-30% of the microsphere radius;

(Iii) 30 to 85 weight percent SiO ₂ , 2 to 45 weight percent (preferably 6 to 40 weight percent) Al ₂ O ₃ , up to about 30 weight percent divalent metal oxide (eg MgO, CaO, SrO, BaO), about 2 to 10% by weight of monovalent metal oxides (e.g. Na ₂ O, K ₂ O) and up to about 20% by weight of other metal oxides (TiO ₂ , Fe ₂ O _3, etc. Composition of the metal oxide);

(Iii) a silica to alumina ratio greater than about 1;

(Iii) an average diameter of 30 to 1,000 μ, more preferably 40 to 500 μ (average diameters of 30 μ or more are advantageous because such particles are not considered to be respirable dust);

(Iii) an outer wall thickness of 1 to 100 µ, preferably 1 to 70 µ, more preferably 2.5 to 20 µ;

(Iii) a particle density of 0.1 to 2.0 g / cm 3, preferably 0.2 to 1.5 g / cm 3, more preferably 0.4 to 1.0 g / cm 3, or

(Iii) a bulk density of less than about 1.4 g / cm 3, preferably less than about 1.0 g / cm 3.

Use of Synthetic Expanded Fine Particles

Synthetic expanded fine particles according to the invention can be used in a wide range of applications, for example fillers, modifiers, containers and substrate applications. Due to the low cost and consistent nature of synthetic microspheres, the application range is wider than the use of captured xeno spares.

The synthetic fine particles according to the invention can be used as fillers in composite materials, in which case the fine particles are endowed with the properties of cost reduction, weight reduction, improved machinability, performance improvement, improved machinability and / or improved workability . More specifically, synthetic fine particles can be prepared from polymers (including thermosets, thermoplastics and inorganic geopolymers), inorganic cement materials (portland cement, lime cement, alumina cements, plasters, phosphate cements, magnesia cements and other hydraulic curables). Materials including binders), concrete systems (including precision concrete structures, tilt-up concrete panels, columns, suspended concrete structures, etc.), putty (e.g. for filling and patching voids), wood composites (particleboards, fiberboards) , Wood / polymer composites and other composite wood structures), clays and ceramics. One particularly preferred use is in fiber cement building materials.

Synthetic expanded fine particles may be used in combination with other materials as a modifier. Fine particles can be mixed with certain materials by appropriate choice of size and shape to provide unique properties such as increased film thickness, improved distribution, improved flowability and the like. Typical modifier applications include light reflection applications (e.g. highway signs and signals), industrial explosives, explosive energy absorbing structures (e.g. energy absorption of bombs and explosives), paint and powder coating applications, grinding and blasting applications, excavation applications ( Eg cement for drilling oil wells), adhesive compositions, and soundproof or heat dissipation applications.

Synthetic expanded fine particles may be used to contain and / or store other materials. Typical container applications include medical and pharmaceutical applications (eg, micro containers for drugs), micro containers for radioactive or toxic substances, and micro containers for gases and liquids.

Synthetic expanded fine particles can also be used to provide specific surface activity in many applications where surface reactions are used (ie, substrate applications). Surface activity can be further improved by subjecting the fine particles to a secondary treatment such as metal or ceramic coating treatment or acid impregnation treatment. Typical substrate applications include ion exchange applications (to remove contaminants from fluids), catalytic applications (surfaces of fine particles are treated to act as catalysts in synthesis, conversion or decomposition reactions), filtration (contaminants from gas or liquid streams) Removed), conductive fillers or RF shielding fillers for polymer composites, and medical imaging applications.

The invention will now be described by way of example only with reference to the following figures.

1 is a phase equilibrium diagram of a Na ₂ O—SiO ₂ binary system, the composition of which is expressed as weight percentage of SiO ₂ .

2 is a TGA plot of three preferred blowing agents, sugar, carbon black and silicon carbide, showing the continuous activation temperatures of the cheapest sugars and the most expensive carbides.

3 to 8 are scanning electron micrographs of the synthetic fine hollow spheres obtained in Example 1. FIG.

9 to 14 are scanning electron micrographs of the synthetic fine hollow spheres obtained in Example 2. FIG.

15 to 17 are scanning electron micrographs of the synthetic fine hollow spheres obtained in Example 3. FIG.

18 and 19 are scanning electron micrographs of the synthetic fine hollow spheres obtained in Example 4. FIG.

20 is a scanning electron micrograph of the synthetic fine hollow sphere obtained in Example 5. FIG.

Example 1

This example describes a method of making expanded micro inclusions from a formulation consisting of basalt and sodium hydroxide.

The formulation is prepared by mixing milled basalt with solid sodium hydroxide and water. Various mixtures of blowing agents and modifiers comprising silicon carbide, sugars, carbon black and coal are added in combination or alone. The formulations are listed in Table 1. The composition of the basalt is listed in Table 2.

Formulation 1A

This formulation describes a process for preparing expanded microinclusions from formulations consisting of basalt, sodium hydroxide and sugars as blowing agents.

Samples are prepared by mixing 92 g of crushed basalt with a d ₅₀ particle size of about 2 μ with 5 g of solid sodium hydroxide (flakes), 3 g of commercially available sugar and 23 ml of water. The formulations are listed in Table 1.

Formulation 1B

This formulation describes a method of making expanded micro inclusions from a formulation consisting of basalt, sodium hydroxide and carbon black as blowing agents.

Samples are prepared by mixing 94 g of crushed basalt with a d ₅₀ particle size of about 2 μ with 5 g of solid sodium hydroxide (flakes), 1 g of commercial grade carbon black and 38 ml of water. The formulations are listed in Table 1.

Formulation 1C

This formulation describes a method of making expanded micro inclusions from a formulation consisting of basalt, sodium hydroxide and silicon carbide as blowing agents.

Samples are prepared by mixing 94.5 g of basalt ground to a d ₅₀ particle size of about 1 μ with 5 g of solid sodium hydroxide (flakes), 0.5 g of commercial grade silicon carbide and 38 ml of water. The formulations are listed in Table 1.

Formulation 1D

The formulation describes a process for producing expanded microinclusions from formulations consisting of basalt, sodium hydroxide and silicon carbide as primary blowing agents and coal as modifiers or secondary blowing agents.

Samples are prepared by mixing 93.5 g of basalt, 0.5 g of commercial grade silicon carbide and 1 g of commercial grade coal, and co-pulverize the resulting blend to a d ₅₀ particle size of about 1 μ. The blend is then mixed with 5 g of solid sodium hydroxide (flakes) and 38 ml of water. The formulations are listed in Table 1.

Formulation 1E

This formulation describes a process for preparing expanded microinclusions from formulations consisting of basalt, sodium hydroxide and silicon carbide as primary blowing agents and sugars as modifiers or secondary blowing agents.

Samples are prepared by mixing 92 g of crushed basalt with a d ₅₀ particle size of about 1 μ with 5 g of solid sodium hydroxide (flakes), 0.5 g of commercial grade silicon carbide, 2.5 g per commercially available and 37 ml of water. The formulations are listed in Table 1.

Formulation 1F

This formulation describes a process for preparing expanded microinclusions from formulations consisting of basalt, sodium hydroxide and carbon black as primary blowing agents and sugars as modifiers or secondary blowing agents.

Samples are prepared by mixing 91.4 g of basalt crushed to a d ₅₀ particle size of about 2μ with 4.8 g of solid sodium hydroxide (flakes), 0.8 g of commercial grade carbon black, 3 g per commercially available and 38 ml of water.

Each mixture is blended into a homogeneous slurry, poured into a flat dish and solidified for about 5 minutes at room temperature. The resulting product is further dried at about 50 ° C. for about 20 hours, followed by grinding and sieving to yield a powder with a size range of 106 to 180 μ. In the next step, the powder is fed to a vertical heating tube furnace at a feed rate of approximately 0.14 g / min. The constant temperature range of the furnace is adjusted to provide a residence time of less than one second to about several seconds at the maximum firing temperature. The foamed fine inclusions are collected with a funnel-shaped collection device covered with a fine mesh screen disposed at the bottom of the furnace. Gentle suction is applied to the distal end of the furnace to facilitate the collection of fine inclusions. The product is characterized for particle density (eg, apparent density) and microscopic examination by SEM. The results are summarized in Table 3.

3 to 9 show SEM inspection of the products obtained from Formulations 1A to 1F, respectively.

Formula (g) 1A-1F Formulation Number basalt Sodium hydroxide blowing agent Regulator Water (ml) 1A 92.0 5.0 3.0 per - 23 1B 94.0 5.0 1.0 carbon black - 38 1C 94.5 5.0 0.5 SiC - 1D 93.5 5.0 0.5 SiC 1.0 powdered coal 38 1E 92.0 5.0 0.5 SiC 2.5 per 37 1F 91.4 4.8 0.8 carbon black 3.0 per 38

Composition of basalt SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ Na ₂ O K ₂ O TiO ₂ Mn ₂ O ₃ P ₂ O ₅ gun 46.1 15.8 11.4 9.5 9.6 0.0 2.8 1.5 2.4 0.25 0.59 99.94

Summary of results Formulation Number Temperature (℃) Retention time (seconds) Apparent density (g / cm ³ ) 1A 1300 0.6-1.1 1.28 1B 1300 0.6-1.1 1.13 1C 1250 0.6-1.1 1.13 1D 1300 0.6-1.1 0.82 1E 1300 0.6-1.1 0.85 1F 1300 0.6-1.1 1.21

The following conclusion can be drawn from Table 1.

1. SiC is a primary blowing agent more effective than carbon and sugars in lowering particle density. The total content of SiC (30 wt% carbon) is less than the equivalent of carbon in carbon (100 wt%) and sugar (40 wt%).

2. The use of SiC with one or more modifiers is more effective at lowering the particle density compared to all single blowing agents used in this example.

3. Any single blowing agent can be mixed with the optimizing agent to optimize the particle density of the product. That is, all SiC mixtures are more effective at lowering particle density compared to carbon-sugar mixtures.

Example 2

This example describes a method of making expanded micro inclusions from a formulation consisting of various silicate compounds, sodium hydroxide and multiple blowing agents.

Expanded fine inclusions are made using a blend of soda lime waste glass and various silicate materials. These blends also include mixtures of modifiers of primary carbides and silicon carbide with modifiers, sugars and / or carbon blacks. The formulations are listed in Table 4. The composition of the waste glass used in this study is described in Table 5.

Formulation 2A

The formulation describes a process for producing expanded micro inclusions from a formulation consisting of free and sodium hydroxide with silicon carbide as blowing agent and carbon black as controlling agent.

Samples are prepared by mixing 95.6 g of crushed glass with a d ₅₀ particle size of about 1 μ with 3 g of solid sodium hydroxide (flakes), 0.4 g of commercial grade silicon carbide, 1 g of commercial grade carbon black and 58 ml of water. The formulations are listed in Table 4.

Formulation 2B

This formulation describes a method of making expanded microinclusions from a formulation consisting of glass, fly ash and sodium hydroxide together with silicon carbide as blowing agent and carbon black as controlling agent.

Samples are prepared by mixing 65.5 g of glass and 28.1 g of fly ash, where the mixture is co-pulverized to a d ₅₀ particle size of about 2 μ. The glass / fly ash blend is mixed with 5 g of solid sodium hydroxide (flakes), 0.4 g of commercial grade silicon carbide, 1 g of commercial grade carbon black and 42 ml of water. The formulations are listed in Table 4. The composition of the fly ash is listed in Table 5.

Formulation 2C

This formulation describes a process for preparing expanded fine inclusions from a formulation consisting of glass, basalt and sodium hydroxide, with silicon carbide as a blowing agent and carbon black as a modifier.

Samples are prepared by mixing 46.8 g of glass and 46.8 g of basalt, where the mixture is co-pulverized to a d ₅₀ particle size of about 2 μ. The glass / basalt blend is mixed with 5 g of solid sodium hydroxide (flakes), 0.4 g of commercial grade silicon carbide, 1 g of commercial grade carbon black and 37 ml of water. The formulations are listed in Table 4. The composition of the basalt is listed in Table 5.

Formulation 2D

This formulation describes a process for preparing expanded microinclusions from formulations consisting of glass, ash and sodium hydroxide, with silicon carbide as blowing agent and carbon black as modifier.

Samples are prepared by mixing 46.8 g of glass and 46.8 g of ash, where the mixture is co-pulverized to a d ₅₀ particle size of about 2 μ. The glass / volcanic blend is mixed with 5 g of solid sodium hydroxide (flakes), 0.4 g of commercial grade silicon carbide, 1 g of commercial grade carbon black and 50 ml of water. The formulations are listed in Table 4. The composition of the ash is shown in Table 5.

Formulation 2E

This formulation describes a process for preparing expanded microinclusions from formulations consisting of free, andesite and sodium hydroxide, with silicon carbide as primary blowing agent and sugar as modulator.

Samples are prepared by mixing 47.1 g of glass and 47.1 g of andesite, where the mixture is co-pulverized to a d ₅₀ particle size of about 2 μ. The glass / andite blend is mixed with 3 g of solid sodium hydroxide (flakes), 0.4 g of commercial grade silicon carbide, 2.5 g per sugar and 50 ml of water. The formulations are listed in Table 4. The composition of the andesite is listed in Table 5.

Formulation 2F

This formulation describes a process for producing expanded microinclusions from formulations consisting of glass, andesite and sodium hydroxide together with silicon carbide as blowing agent and carbon black as controlling agent.

Samples are prepared by mixing 47.8 g of glass and 47.8 g of andesite, where the mixture is co-pulverized to a d ₅₀ particle size of about 1 μ. The glass / andite blend is mixed with 3 g of solid sodium hydroxide (flakes), 0.4 g of commercial grade silicon carbide, 1 g of commercial grade carbon black and 43 ml of water. The formulations are listed in Table 4.

Each mixture is blended into a homogeneous slurry, poured into a flat dish and solidified for about 5 minutes at room temperature. The resulting product is further dried at about 50 ° C. for about 20 hours, followed by grinding and sieving to yield a powder with a size range of 106 to 180 μ. In the next step, the powder is fed to a vertical heating tube furnace at a feed rate of approximately 0.14 g / min. The constant temperature range of the furnace is adjusted to provide a residence time of less than one second to about several seconds at the maximum firing temperature. The foamed fine inclusions are collected with a funnel-shaped collection device covered with a fine mesh screen disposed at the bottom of the furnace. Gentle suction is applied to the distal end of the furnace to facilitate the collection of fine inclusions. The product is characterized for particle density (eg, apparent density) and microscopic examination by SEM.

The results are summarized in Table 6.

10-16 show SEM inspection of the products obtained from Formulations 2A to 2F, respectively.

Formulation (g) 2A to 2F Formulation Number Waste glass Additional ingredients Sodium hydroxide blowing agent Regulator Water (ml) 2A 95.6 - 3.0 0.4 SiC 1.0 carbon black 58 2B 65.5 28.1 fly ash 5.0 0.4 SiC 1.0 carbon black 42 2C 46.8 46.8 basalt 5.0 0.4 SiC 1.0 carbon black 37 2D 46.8 46.8 Ash 5.0 0.4 SiC 1.0 carbon black 50 2E 47.1 47.1 Andesite 3.0 0.4 SiC 2.5 per 42 2F 47.8 47.8 Andesite 3.0 0.4 SiC 1.0 carbon black 43

Chemical composition SiO ₂ Al ₂ O Fe ₂ O ₃ CaO MgO SO ₃ Na ₂ O K ₂ O TiO ₂ Mn ₂ O ₃ P ₂ O ₅ gun Glass 74.7 2.0 0.9 11.1 0.6 0.0 10.0 0.5 0.06 0.06 0.02 99.94 Fly ash 52.7 20.2 13.2 7.6 2.5 0.4 0.4 1.3 1.3 0.16 0.08 99.84 Volcanic ash 76.4 12.4 2.1 0.9 0.3 0.0 2.1 5.5 0.15 0.08 0.03 99.96 Andesite 67.8 15.2 4.6 2.1 0.6 0.0 2.7 4.9 0.7 0.9 0.28 99.78

Summary of results Formulation Number Temperature (℃) Retention time (seconds) Apparent density (g / cm ³ ) 2A 1200 0.6-1.1 0.98 2B 1300 0.6-1.1 1.11 2C 1200 0.6-1.1 0.93 2D 1200 0.6-1.1 0.94 2E 1300 0.6-1.1 0.93 2F 1300 0.6-1.1 0.77

The following conclusion can be drawn from Example 2.

1. A mixture of blowing agents and modifiers, namely silicon carbide-carbon and silicon carbide-sugars, is very effective for the production of expanded fine inclusions.

2. Waste glass is an economical and suitable additive to various silicate mixtures.

3. The silicate raw material suitable for the preparation of the expanded fine inclusions according to the present invention can be selected from a wide range of waste by-products, minerals, chemicals and rocks.

Example 3

This example describes a process for preparing expanded microinclusions from formulations consisting of varying amounts of volcanic ash, sodium hydroxide, mixtures of blowing and control agents, and other minor additives.

Formulation 3A

The sample was mixed 78.2 g of volcanic ash ground to a d ₅₀ particle size of about 3μ with 20 g of solid sodium hydroxide (flakes), 0.8 g of commercial grade silicon carbide as the primary blowing agent, 1 g of commercial grade carbon black as the regulator and 43 ml of water. Manufacture.

Formulations 3B and 3C

Samples are prepared using a blend of volcanic ash and iron (III) co-milled to a d ₅₀ particle size of about 1 μ. The formulations are listed in Table 7. The composition of the ash is shown in Table 5. The mixture is blended into a homogeneous slurry, poured into a flat dish and solidified for about 5 minutes at room temperature. The resulting product is further dried at about 50 ° C. for about 20 hours, followed by grinding and sieving to yield a powder with a size range of 106 to 180 μ. In the next step, the powder is fed to a vertical heating tube furnace at a feed rate of approximately 0.14 g / min. The constant temperature range of the furnace is adjusted to provide a residence time of less than one second to about several seconds at the maximum firing temperature. The foamed fine inclusions are collected with a funnel-shaped collection device covered with a fine mesh screen disposed at the bottom of the furnace. Gentle suction is applied to the distal end of the furnace to facilitate the collection of fine inclusions. The product is characterized for particle density (eg, apparent density) and microscopic examination by SEM.

The results are summarized in Table 8.

17-20 show two cross sectional areas per sample of the product obtained from Formulations 3A to 3C, respectively.

Formulation (g) 3A-3C Formulation Number Volcanic ash Sodium hydroxide blowing agent Regulator Iron oxide (III) Water (ml) 3A 78.2 20.0 0.8 SiC 1.0 carbon black 43 3B 76.6 19.6 0.8 1.0 carbon black 2.0 43 3C 86.2 9.8 0.8 1.0 carbon black 2.2 43

Summary of results Formulation Number Temperature (℃) Retention time (seconds) Apparent density (g / cm ³ ) 3A 1200 0.6-1.1 0.71 3B 1200 0.6-1.1 0.60 3C 1200 0.6-1.1 0.59

The following conclusion can be drawn from Example 3.

1. The mixing of silicon carbide as primary blowing agent and carbon black as controlling agent is very effective in expanding volcanic ash into very hard cyclic products.

2. As the sodium concentration increases in the formulation, the roundness of the product reaches approximately spherical shape. Sodium oxide is a strong melt for silicate glasses, for example viscosity reducing agents. Therefore, formulations with lower viscosities tend to form spherical expanded particles than cyclic fine particles, mainly due to lower surface tension at firing temperatures.

Example 4

This example describes a method of making expanded microinclusions from a formulation consisting of fly ash, sodium hydroxide and foam control agents.

Formulation 4A

The sample mixed 79 g of a Type F fly ash with a d ₅₀ particle size of about 4μ with 19 g of solid sodium hydroxide (flakes), 1 g of commercial grade silicon carbide as the primary blowing agent, 1 g of commercial grade carbon black as the regulator and 42 ml of water. To prepare.

Formulation 4B

Samples are prepared by mixing 68.7 g of Type F fly ash similar to that used in Formulation 4A with 29.5 g of solid sodium hydroxide as described in Table 9. The composition of the fly ash is shown in Table 5.

The mixture is blended into a homogeneous slurry, poured into a flat dish and solidified for about 5 minutes at room temperature. The resulting product is further dried at about 50 ° C. for about 20 hours, followed by grinding and sieving to yield a powder with a size range of 106 to 180 μ. In the next step, the powder is fed to a vertical heating tube furnace at a feed rate of approximately 0.14 g / min. The constant temperature range of the furnace is adjusted to provide a residence time of less than one second to about several seconds at the maximum firing temperature. The foamed fine inclusions are collected with a funnel-shaped collection device covered with a fine mesh screen disposed at the bottom of the furnace. Gentle suction is applied to the distal end of the furnace to facilitate the collection of fine inclusions. The product is characterized for particle density (eg, apparent density) and microscopic examination by SEM.

The results are summarized in Table 10.

21-22 show two cross sectional areas per sample of product obtained from Formulations 4A and 4B, respectively.

Formulation (g) 4A and 4B Formulation Number Fly ash Sodium hydroxide blowing agent Regulator Water (ml) 4A 79.0 19.0 1.0 SiC 1.0 carbon black 42.0 4B 68.7 29.5 0.8 SiC 1.0 carbon black 42.0

Summary of results Formulation Number Temperature (℃) Retention time (seconds) Apparent density (g / cm ³ ) 4A 1200 0.6-1.1 0.67 4B 1200 0.6-1.1 1.03

The following conclusion can be drawn from Example 4.

1. A mixture of silicon carbide as primary blowing agent and carbon as modifier is very effective in producing low density fine inclusions from silicate waste by-products, ie fly ash.

2. By optimizing the concentration of the molten compound (eg sodium hydroxide), excellent spherical fine inclusions with low particle density can be produced.

3. If the concentration of the melt is higher than the optimum value, not only the particle density of the product increases, but also adversely affects the economics. Lung fly ash is less expensive than sodium hydroxide.

Example 5

This example describes a process for preparing expanded inclusions from a formulation consisting of waste products phosphate clay, sodium hydroxide, silicon carbide and carbon black from phosphate ore spectroscopy.

Formulation 5A

Samples are prepared by mixing 88.4 g of ground phosphate clay with a d ₅₀ particle size of 0.6 μg with 9.8 g of solid sodium hydroxide (flakes), 0.8 g of commercial grade silicon carbide, 1.0 g of commercial grade carbon black and 85 ml of water. The composition of phosphate clays is listed in Table 11.

The mixture is blended into a homogeneous slurry, poured into a flat dish and solidified for about 5 minutes at room temperature. The resulting product is further dried at about 50 ° C. for about 20 hours, followed by grinding and sieving to yield a powder with a size range of 106 to 180 μ. In the next step, the powder is fed to a vertical heating tube furnace at a feed rate of approximately 0.14 g / min. The constant temperature range of the furnace is adjusted to provide a residence time of less than one second to about several seconds at the maximum firing temperature. The foamed fine inclusions are collected with a funnel-shaped collection device covered with a fine mesh screen disposed at the bottom of the furnace. Gentle suction is applied to the distal end of the furnace to facilitate the collection of fine inclusions. The product is characterized for particle density (eg, apparent density) and microscopic examination by SEM.

The results are summarized in Table 12.

35 and 36 show cross sections of the product.

Chemical Composition Of Phosphate Clay SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO SO ₃ Na ₂ O K ₂ O TiO ₂ Mn ₂ O ₃ P ₂ O ₅ gun 36.5 17.8 2.7 20.8 3.4 0.33 0.29 0.88 0.57 0.05 16.7 100.0

Summary of results Temperature (℃) Retention time (seconds) Apparent density (g / cm ³ ) 1300 0.8-1.5 0.92

The following conclusion can be drawn from Example 5.

1. Multiple blowing agent mixtures of silicon carbide and carbon are effectively used to produce low density fine inclusions from waste clay by-products.

2. The P ₂ O ₅ -CaO combined concentration is at least 33% by weight, based on the total weight% of the product. The mixture can strongly form an amorphous apatite phase in the product.

Apatite containing products may exhibit useful bioactive reactions in medical applications.

It is to be understood that the present invention may be embodied in other forms without departing from the spirit or scope of the invention.

Claims (111)

Providing an precursor by forming an aqueous mixture of an inorganic main component and a blowing agent, drying the mixture and optionally grinding to a predetermined size; and Firing the precursor to activate the blowing agent, wherein activation of the blowing agent is controlled to activate the blowing agent at a predetermined optimum temperature range, thereby expanding the precursor and forming a low density material. The method of claim 1, wherein the low density material is fine particles of 1,000 μm or less in diameter. The process according to claim 1 or 2, wherein the blowing agent is activated in the temperature range in which the inorganic main component is melted and is present in the optimum viscosity range. The process according to claim 1, wherein the blowing agent is controlled by the addition of modifiers. The method according to claim 1, wherein the blowing agent is provided as the primary blowing agent and the regulator is provided as the secondary blowing agent. 6. The method of claim 1, wherein the primary blowing agent has a first activation temperature and the secondary blowing agent has a second activation temperature lower than the first activation temperature. 7. The method of claim 1, wherein the primary blowing agent is powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, sugars, carbohydrates such as corn syrup or starch, PVA, carbonate, carbide , Sulfates, sulfides, nitrides, nitrates, amines, polyols, glycols and glycerin. 8. The secondary blowing agent according to claim 1, wherein the secondary blowing agent is powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, sugars, carbohydrates such as corn syrup or starch, PVA, carbonate, carbide , Sulfates, sulfides, nitrides, nitrates, amines, polyols, glycols and glycerin. The method of claim 1, wherein the precursor further comprises a tertiary blowing agent having a third activation temperature lower than the first activation temperature. 10. The tertiary blowing agent is selected from powdered coal, carbon black, activated carbon, graphite, carbonaceous polymeric organics, oils, carbohydrates, PVA, carbonates, sulfates, sulfides, nitrates, amines, polyols, glycols and glycerin. Way. The method of claim 1, wherein the precursor is calcined under conditions that control activation of the blowing agent. The method according to any one of claims 1 to 11, wherein the precursor is calcined in an oxygen deficient environment. The method of claim 12, wherein the precursor is calcined in a fuel rich / lean oxidation environment. The method according to any one of claims 1 to 13, wherein activation of the blowing agent is controlled by appropriately introducing an O ₂ deficient gas or an O ₂ rich gas during firing of the precursor. The method according to claim 1, wherein the precursor is formed of a predetermined distribution of blowing agent that provides for controlled activation of the blowing agent during firing of the precursor. The process of claim 1 wherein the drying step is performed using a spray dryer having an aqueous slurry feed. The method of claim 16, wherein the inlet temperature range of the spray dryer is from 300 to 600 ° C. 18. 18. The method of claim 16 or 17, wherein the discharge temperature range of the spray dryer is from 90 to 220 ° C. The method according to any one of claims 1 to 18, wherein the amount of the inorganic main component is 50% by weight or more based on the total dry weight of the aggregated precursor. The method according to claim 1, wherein the amount of foam component is in the range of 0.05 to 10% by weight, based on the total dry weight of the aggregated precursor. 21. The method of any one of claims 1-20, wherein the ratio of inorganic main component to foaming component is in the range of 1000: 1 to 10: 1. 22. The method of any one of claims 1 to 21, wherein the mixture is dried such that the water content of the precursor is less than about 14 weight percent. 23. The method of any one of claims 1 to 22, wherein the average aggregate particle size range of the resulting aggregate precursor is 10 to 1000 microns. 24. The method of any one of claims 1 to 23, wherein the total alkali metal oxide content of the resulting aggregated precursor is about 10% by weight or less based on the total dry weight of the aggregated precursor. The method of claim 1, wherein the inorganic main component comprises one or more materials selected from inorganic oxides, nonoxides, salts, and mixtures thereof. 26. The method of any one of claims 1 to 25, wherein the inorganic main component comprises one or more materials selected from industrial and / or domestic by-products, minerals, rocks, clays, technical grade chemicals, and mixtures thereof. 27. The method of any one of claims 1 to 26, wherein the inorganic principal component comprises one or more silicate materials. 30. The method of claim 27, wherein the one or more silicate materials are fly ash, bottom ash, blast-furnace slag, paper ash, basalt rock, andesite rock, feldspar , Aluminosilicate clay, bauxite, volcanic ash, volcanic rock, volcanic glass, geopolymer and mixtures thereof. 29. The method of any one of claims 1 to 28, wherein the inorganic main component can form a viscoelastic liquid. 30. The method of any one of claims 1 to 29, wherein the average primary particle size range of the inorganic main component is 0.01 to 100 microns. 31. The method of any one of claims 1-30, wherein the primary blowing agent is relatively less water soluble than the secondary blowing agent. 32. The method of any one of claims 1 to 31 wherein the average particle size range of the blowing agent is from 0.01 to 10 microns. 33. The method of any one of claims 1 to 32, further comprising mixing the binder with the inorganic main component and the blowing agent. The method of claim 33, wherein the binder is an alkali metal silicate, an alkali metal aluminosilicate, an alkali metal borate, an alkali metal or an alkaline earth metal carbonate, an alkali metal or an alkaline earth metal nitrate, an alkali metal or an alkaline earth metal nitrite, a boric acid, an alkali metal or Alkaline Earth Metal Sulfate, Alkali or Alkaline Earth Metal Phosphate, Alkali or Alkaline Earth Metal Hydroxide, Carbohydrates, Colloidal Silica, Ultrafine Fly Ash, Type C Fly Ash, Type F Fly Ash, Inorganic Silicate Cement, Portland Cement , Alumina cement, lime cement, phosphate cement, organic polymers and mixtures thereof. 35. The method of claim 33 or 34, wherein the binder has a melting point lower than the melting point of the aggregated precursor as a whole. 35. The method of any one of claims 32-34, wherein the melting point range of the binder is 700-1000 ° C. 37. The method of claim 35 or 36, wherein the binder is a silicate. 37. The process of claim 35 or 36 wherein the binder is an alkali metal silicate produced by in situ reaction of an alkali metal hydroxide with a silicate main component. 39. The method of any one of claims 35 to 38, wherein the amount of binder is in the range of 0.1 to 50% by weight, based on the total dry weight of the aggregated precursor. 40. The method of any one of claims 35-39, wherein the binder is relatively more water soluble than the primary blowing agent. 41. The process according to any one of claims 1 to 40, wherein the main component, the foaming component and, optionally, the binder are ground together simultaneously. Providing an inorganic active ingredient (g), (H) forming an aqueous mixture of the inorganic main ingredient, blowing agent and modifier, wherein the blowing agent and modulator are selected to regulate the activation of the blowing agent so that the blowing agent is activated in a predetermined optimum temperature range; and Drying the mixture to provide an expandable precursor for forming a low density material, the method comprising forming a precursor for a low density material. 43. The method of claim 42, wherein the blowing agent is provided as the primary blowing agent and the regulator is provided as the secondary blowing agent. 44. The method of claim 42 or 43, wherein the primary blowing agent has a first activation temperature and the secondary blowing agent has a second activation temperature that is lower than the first activation temperature. 44. The method of claim 42 or 43, wherein the primary blowing agent is carbohydrates such as powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, sugars, corn syrups or starches, PVA, carbonates, carbides, sulfates, sulfides. , Nitrides, nitrates, amines, polyols, glycols and glycerin. 46. The method of any of claims 42-45, wherein the secondary blowing agent is a powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, sugars, carbohydrates such as corn syrup or starch, PVA, carbonate, carbide , Sulfates, sulfides, nitrides, nitrates, amines, polyols, glycols and glycerin. 47. The method of any one of claims 42-46, wherein the precursor further comprises a tertiary blowing agent having a third activation temperature lower than the first activation temperature. 48. The tertiary blowing agent is selected from powdered coal, carbon black, activated carbon, graphite, carbonaceous polymeric organics, oils, carbohydrates, PVA, carbonates, sulfates, sulfides, nitrates, amines, polyols, glycols and glycerin. Way. 49. The method of any one of claims 42-48, wherein activation of the blowing agent is controlled by appropriately introducing an O ₂ deficiency gas or an O ₂ rich gas during firing of the precursor. The method of any one of claims 42-49, wherein the precursor is formed from a predetermined distribution of blowing agent that provides controlled activation of the blowing agent during firing of the precursor. 43. The process of claim 42, wherein the drying step is performed using a spray drier with an aqueous slurry feed. 52. The method of claim 51 wherein the inlet temperature range of the spray dryer is from 300 to 600 ° C. 53. The method of claim 51 or 52, wherein the discharge temperature range of the spray dryer is from 90 to 220 ° C. 54. The method of any one of claims 42-53, wherein the amount of inorganic main component is at least 50% by weight, based on the total dry weight of the aggregated precursor. 55. The method of any one of claims 42-54, wherein the amount of foam component is in the range of 0.05-10% by weight, based on the total dry weight of the aggregated precursor. The method of any one of claims 42-55, wherein the ratio of inorganic main component to foaming component is in the range from 1000: 1 to 10: 1. 57. The method of any one of claims 42-56, wherein the mixture is dried such that the water content of the precursor is less than about 14 weight percent. 59. The method of any one of claims 42-57, wherein the average aggregate particle size range of the resulting aggregate precursor is 10-1000 microns. 59. The method of any one of claims 42-58, wherein the total alkali metal oxide content of the resulting aggregated precursor is about 10% by weight or less based on the total dry weight of the aggregated precursor. 60. The method of any one of claims 42-59, wherein the inorganic main component comprises one or more materials selected from inorganic oxides, nonoxides, salts, and mixtures thereof. 61. The method of any one of claims 42-60, wherein the inorganic main component comprises one or more materials selected from industrial and / or domestic by-products, minerals, rocks, clays, technical grade chemicals, and mixtures thereof. 62. The method of any one of claims 42-61, wherein the inorganic main component comprises one or more silicate materials. 63. The method of claim 62, wherein the one or more silicate materials are fly ash, bottom ash, blast furnace slag, paper ash, basalt rock, andesite rock, feldspar, aluminosilicate clay, bauxite, volcanic ash, volcanic rock, volcanic glass, paper Selected from polymers and mixtures thereof. 64. The method of any one of claims 42-63, wherein the inorganic main component can form a viscoelastic liquid. 65. The method of any one of claims 42 to 64, wherein the average primary particle size range of the inorganic main component is 0.01 to 100 microns. 66. The method of any one of claims 42-65, wherein the primary blowing agent is relatively less water soluble than the secondary blowing agent. 67. The method of any one of claims 42-66, wherein the average particle size range of the blowing agent is from 0.01 to 10 microns. 68. The method of any one of claims 42-67, further comprising mixing the binder with an inorganic main ingredient and a blowing agent. 69. The method of claim 68, wherein the binder is an alkali metal silicate, an alkali metal aluminosilicate, an alkali metal borate, an alkali metal or alkaline earth metal carbonate, an alkali metal or alkaline earth metal nitrate, an alkali metal or alkaline earth metal nitrite, boric acid, alkali metal or Alkaline earth metal sulfates, alkali or alkaline earth metal phosphates, alkali metal or alkaline earth metal hydroxides, carbohydrates, colloidal silica, ultrafine fly ash, type C fly ash, type F fly ash, inorganic silicate cement, portland cement, alumina cement , Lime based cements, phosphate based cements, organic polymers and mixtures thereof. 70. The method of claim 68 or 69, wherein the melting point of the binder is lower than the melting point of the aggregated precursor as a whole. 71. The method of any one of claims 68-70, wherein the melting point range of the binder is 700-1000 ° C. The method of claim 70 or 71, wherein the binder is a silicate. 72. The method of claim 70 or 71, wherein the binder is an alkali metal silicate produced by in situ reaction of an alkali metal hydroxide with a silicate main component. 74. The method of any one of claims 70-73, wherein the amount of binder is in the range of 0.1-50% by weight, based on the total dry weight of the aggregate precursor. 75. The method of any one of claims 70-74, wherein the binder is relatively more water soluble than the primary blowing agent. 76. The method of any one of claims 42-75, wherein the main component, the foaming component and optionally the binder are simultaneously ground together. (J) providing an inorganic principal component, (K) forming an aqueous mixture of the inorganic main component and the blowing agent, wherein the blowing agent controls the activation of the blowing agent upon firing of the precursor so that the blowing agent is selected to be activated in a predetermined optimum temperature range and / or is distributed in the precursor; and Drying the mixture to provide an expandable precursor for forming a low density material, the method of forming a precursor for a low density material. A precursor suitable for the production of expanded fine particles comprising an expandable inorganic main component, a blowing agent adapted to activate and expand the main ingredient, and a control agent selected to regulate activation of the blowing agent so that the blowing agent is activated in a predetermined optimum temperature range. 79. The precursor of claim 78, wherein the blowing agent is provided as the primary blowing agent and the regulator is provided as the secondary blowing agent. 80. The precursor of claim 78 or 79, wherein the primary blowing agent has a first activation temperature and the secondary blowing agent has a second activation temperature lower than the first activation temperature. 81. The process of any of claims 78 to 80, wherein the primary blowing agent is carbohydrates such as powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, sugars, corn syrups or starches, PVA, carbonates, carbides. , Precursors selected from sulfates, sulfides, nitrides, nitrates, amines, polyols, glycols and glycerin. 82. The method of any of claims 78-81, wherein the secondary blowing agent is carbohydrates such as powdered coal, carbon black, activated carbon, graphite, carbonaceous polymer organics, oils, sugars, corn syrups or starches, PVA, carbonates, carbides. , Precursors selected from sulfates, sulfides, nitrides, nitrates, amines, polyols, glycols and glycerin. 83. The precursor of claim 78, wherein the precursor further comprises a tertiary blowing agent having a third activation temperature lower than the first activation temperature. 84. The method of claim 83, wherein the tertiary blowing agent is selected from powdered coal, carbon black, activated carbon, graphite, carbonaceous polymeric organics, oils, carbohydrates, PVA, carbonates, sulfates, sulfides, nitrates, amines, polyols, glycols and glycerin Precursor. 85. The precursor of claim 78, wherein the activation of the blowing agent is controlled by appropriately introducing an O ₂ deficient gas or an O ₂ rich gas during firing of the precursor. 86. The precursor of claim 78, wherein the precursor is formed from a distribution of blowing agent that provides controlled activation of the blowing agent during firing of the precursor. The precursor according to any one of claims 78 to 86, wherein the amount of the inorganic main component is at least 50% by weight, based on the total dry weight of the aggregated precursor. 88. The precursor according to any one of claims 78 to 87, wherein the amount of foam component is in the range of 0.05 to 10% by weight, based on the total dry weight of the aggregated precursor. The precursor of claim 78, wherein the ratio of inorganic main component to foaming component is in the range from 1000: 1 to 10: 1. 90. The precursor of any of claims 78-89, wherein the mixture is dried such that the water content of the precursor is less than about 14 weight percent. 91. The precursor of any of claims 78-90, wherein the average aggregate particle size range of the resulting aggregate precursor is 10-1000 microns. 92. The precursor of any of claims 78-91, wherein the total alkali metal oxide content of the resulting aggregated precursor is about 10% by weight or less based on the total dry weight of the aggregated precursor. 93. The precursor of any of claims 78-92, wherein the inorganic main component comprises one or more materials selected from inorganic oxides, nonoxides, salts, and mixtures thereof. 95. The precursor of any of claims 78-93, wherein the inorganic main component comprises one or more materials selected from industrial and / or domestic by-products, minerals, rocks, clays, technical grade chemicals, and mixtures thereof. 95. The precursor of any of claims 79-94, wherein the inorganic main component comprises one or more silicate materials. 97. The method of claim 95, wherein the one or more silicate materials are fly ash, bottom ash, blast furnace slag, paper ash, basalt rock, andesite rock, feldspar, aluminosilicate clay, bauxite, volcanic ash, volcanic rock, volcanic glass, paper Precursors selected from polymers and mixtures thereof. 97. The precursor of any of claims 78-96, wherein the inorganic main component can form a viscoelastic liquid. 98. The precursor according to any one of claims 78 to 97, wherein the average primary particle size range of the inorganic main component is 0.01 to 100 microns. 99. The precursor of any of claims 78-98, wherein the primary blowing agent is relatively less water soluble than the secondary blowing agent. 100. The precursor of any of claims 78-99, wherein the average particle size range of the blowing agent is from 0.01 to 10 microns. 101. The precursor of any one of claims 78-100, further comprising mixing the binder with an inorganic main component and a blowing agent. 102. The method of claim 101, wherein the binder is an alkali metal silicate, alkali metal aluminosilicate, alkali metal borate, alkali metal or alkaline earth metal carbonate, alkali metal or alkaline earth metal nitrate, alkali metal or alkaline earth metal nitrite, boric acid, alkali metal or Alkaline earth metal sulfates, alkali or alkaline earth metal phosphates, alkali metal or alkaline earth metal hydroxides, carbohydrates, colloidal silica, ultrafine fly ash, type C fly ash, type F fly ash, inorganic silicate cement, portland cement, alumina cement Precursors selected from lime cement, phosphate cement, organic polymers and mixtures thereof. 103. The precursor of claim 101 or 102, wherein the binder has a melting point lower than the melting point of the aggregated precursor as a whole. 103. The precursor of any one of claims 101-103 wherein the binder has a melting point in the range of 700-1000 ° C. 105. The precursor of claim 103 or 104 wherein the binder is a silicate. 107. The precursor of claim 103 or 104, wherein the binder is an alkali metal silicate produced by in situ reaction of an alkali metal hydroxide with a silicate main component. 107. The precursor of any one of claims 103-106, wherein the amount of binder is in the range of 0.1 to 50 weight percent, based on the total dry weight of the aggregated precursor. 107. The precursor of any of claims 103-107, wherein the binder is relatively more water soluble than the primary blowing agent. Preparation of expanded microparticles comprising an expandable inorganic main component and a blowing agent selected to be activated at a predetermined optimum temperature range and / or distributed in the precursor to provide expanded microparticles upon firing of the precursor by controlling activation of the blowing agent Suitable precursors. Providing at least one blowing agent that is activated under predetermined conditions to release foaming gas and provide expanded fine particles, and adjusting the conditions to cause activation to occur in a predetermined optimum viscosity range of the inorganic mixture. To control the activation of the blowing agent in the inorganic mixture to produce fine particles. A foaming component for preparing expanded microparticles, comprising a primary blowing agent and a predetermined amount of miscibility regulator, wherein when the foaming component is included in an expandable mixture, the controlling agent is activated in advance or simultaneously with the foaming agent to control and preserve the foaming agent. Foam component for the production of expanded fine particles.

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