Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C13/00—Fibre or filament compositions
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/14—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
  • C04B35/18—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in aluminium oxide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
  • C04B35/6303—Inorganic additives
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/71—Ceramic products containing macroscopic reinforcing agents
  • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
  • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/0003—Linings or walls
  • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D1/00—Casings; Linings; Walls; Roofs
  • F27D1/0003—Linings or walls
  • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
  • F27D1/0009—Comprising ceramic fibre elements
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/3418—Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
  • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
  • C04B2235/349—Clays, e.g. bentonites, smectites such as montmorillonite, vermiculites or kaolines, e.g. illite, talc or sepiolite
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5216—Inorganic
  • C04B2235/522—Oxidic
  • C04B2235/5232—Silica or silicates other than aluminosilicates, e.g. quartz
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/526—Fibers characterised by the length of the fibers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5208—Fibers
  • C04B2235/5264—Fibers characterised by the diameter of the fibers
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5276—Whiskers, spindles, needles or pins
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5284—Hollow fibers, e.g. nanotubes
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
  • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
  • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
  • C04B2235/52—Constituents or additives characterised by their shapes
  • C04B2235/5296—Constituents or additives characterised by their shapes with a defined aspect ratio, e.g. indicating sphericity

Definitions

• the present invention relates to a composition of microfibrous texture essentially comprising siliceous spicules of spongiaria, as well as processes and equipment for obtaining them. Said microfibrous composition may be used, among other uses, for thermal insulation.
• the techniques in- volved in the making of it are related to the ceramic industrial sector and the sector of manufacturing artifacts for civil architecture.
• the glass fibers are relatively noble products and may be long, continuous or short filaments, of great chemical and physical homogeneity. They resist up to 800° C and are commercialized in webs, being relatively expensive.
• the calcium silicate fibers are less expensive fibers, but are intended to be used at temperature no higher than 600° C. They are also sold in webs or as semi-rigid aggregate products.
• the "rock wools" are products derived from the basaltic rock melting. They sand temperatures around 800°C and are cheaper than glass fi- bers. They are commercialized in webs or in semi-rigid pieces.
• the "ceramic fibers” are more refractive having types which stand temperatures from 1.250°C to 1.400°C, being some of them able to stand even higher temperatures. They have, generally, silico-aluminous to aluminous composition, and their refractoriness increases according to the amount of aluminum comprised therein. There is also the pure silica fiber with good refractory properties. The costs of the manufacturing theses fibers depend on their deterioration resistance under high temperatures. Generally, all types of this fiber have good thermal insulation properties. However, theses fibers, under high temperatures, deteriorate by melting or get fragile by recristalization mainly of christobalite in the glass mass.
• the ceramic fibers are commercialized in long fibers constituting webs, or then, in short fibers, generally, aggregated by resin binding components constituting semi-rigid products. Ceramic fibers exhibit, as a restriction to its use, low compression strength or bending strength, even in the so-called "rigid" products, and a high linear retraction of up to 8%, found in the first burning at temperatures of continuous use. In addition, such products are quite expensive with res- pect to other high-temperature insulators.
• the microfibrous composition of the present invention comprises siliceous spicules of spongiaria (explained in greater detail later) and often look like synthetic products constituted by short ceramic fibers.
• Siliceous spicules of spongiaria are cylindrical microneedles with length on the order of 500 ⁇ m, thickness on the order of 10 ⁇ m, essentially composed of silica. Such spicules can be qualified as fibers or microfibers due to said dimensions. Such terminology will be used hereinafter, in this context.
• Said siliceous spicules of spongiaria are parts remaining from skeletons of colonies of certain organisms that are scientifically called sponges. Sponges are minute animals of aquatic life, which form colonies called spongiaria. Cyclically, the colonies die, releasing the spicules that are dispersed in the aquatic medium, settling on the beds of lakes or sea, and are then fossilized.
• An objective of the present invention is to provide a microfibrous composition comprising siliceous spicules of spongiaria, the amount thereof ranging from 70% to 99% by weight, based on the total weight of the composition. This amount is much higher than that already obtained in the prior art, and resulting in relevant improvements of the physico-chemical properties inherent in the pieces made with this composition.
• Another objective of the present invention is to provide the pro- Waits and the respective equipment for obtaining the microfibrous composition aimed at.
• microfibrous composition particularly used for heat insulation and sound insulation, characterized by comprising an amount of siliceous spicules of spongiaria ranging from 70% to 99% by weight, based on the total weight of the composition.
• the objectives of the present invention are also achieved by means of a process for obtaining the microfibrous composition, which comprises the following steps: a - mixing the microfibers with water and at least one binding component in a friction tank; b - stirring said mixture until a homogeneous pulp is achieved; c - shaping the pulp in a shaping equipment to eliminate the ex- cess of water and binding components and to obtain a residual cake; d - curing the residual cake by a curing process, so as to obtain the microfibrous composition.
• an equipment to promote the shaping of the residual cake which comprises: - a mold associated, at its upper part, to a container and, at its lower part, to a bulkhead; said mold being further associated, at its lower part, to a liquid collec- tor and to an outlet for the residual pulp.
• the microfibrous composition presented now has many advantages over the products based on synthetic fibers and over the products that comprise a lower concentration of siliceous microfibers, above all in heat in- sulation, strength and dimensional stability when used at high temperatures, some of which are listed below.
• microfibrous composition of the present invention exhibits dimensional stability, configured by linear retraction in the re-burning on the order of 1 mm/m, or 0.10%, whereas pieces made from ceramic fibers exhibit values even higher than 4.5%.
• bodies composed of the microfibrous composition of the present invention exhibit values on the order of 0.47 and 0.41 MPa of compres- sion strength and fending strength, respectively, while bodies composed of ceramic fibers exhibit compression strength on the order of 0.25 MPa and a virtually null value with regard to the bending strength.
• the pieces comprising the microfibrous composition of the present invention exhibit heat-insulation properties very similar to those inherent in the best ceramic-fiber pieces. For example, at a temperature of the hot face on the order of 1 ,000° C, pieces made from the microfibrous composition e- xhibit a heat conductivity coefficient of 0.192 W/m.K, whereas an optimum product constituted by ceramic fibers exhibit a heat conductivity coefficient of 0.190 W/m.K.
• microfibrous composition of the present invention with compositions made from rock wool and calcium silicate wool: • the microfibrous composition exhibits higher values of refractoriness properties with respect to the pieces made from rock wool and calcium silicate wool.
• the pieces (bricks) made from kaolin/diatomite usually exhibit dimensions corresponding to 224 x112 x 76 mm.
• the methods of making pieces explained in greater detail later, it is possible to make larger pieces comprising the microfibrous composition of the present invention, with at least one of the dimensions even larger than 1.0 meter each.
• Figure 1 illustrates a flow diagram of the industrial processing for obtaining the microfibrous composition of the present invention
• Figure 2 illustrates a first schematized embodiment of the equipment used in the process of obtaining the microfibrous composition of the present invention
• Figure 3 illustrates a second schematized embodiment of the equipment used in the process of obtaining the microfibrous composition of the present invention
• Figure 4 illustrates a third schematized embodiment of the equipment used in the process of obtaining the microfibrous composition of the present invention.
• the microfibrous composition of the present invention is composed of microfibers of siliceous spicules of spongiaria and binding components such as various kinds of clay. It is intended for uses the require refractoriness properties at high temperatures of up to 1,250° C or higher. 1 - Microfibers of Spongiaria The microfibers must be cleaned, loosened and sorted according to their size in order to be used in the microfibrous composition of the present invention. In order to obtain microfibers free from natural impurities industrially, ores are processed. The processes comprise hydration and attrition by using chemical dispersants, thus obtaining a pulp in which grains are sorted later. Sand and fine residues are removed by hydrocycloning and settling, respectively.
• the microfibers may have varied shapes, that is, they may be constituted by entire or fragmented original spicules, either mixed or not, as long as they exhibit the properties and characteristics listed below.
• the spicules of spongiaria are needles or acicules, the maximum length of which is of 0.5 millimeters, being transparent, rigid, composed of amorphous silica and volatile components.
• a ratio between length and thickness on the order of from 10 to 20 times and length smaller than 0.5 mm enable them to be technically called fibers or microfibers.
• 2 - Microfibrous Composition As shown before, the microfibrous composition has a microfibrous texture and is essentially constituted by siliceous spicules of spongiari- a. It has mainly the characteristics described below:
• the mechanical properties of the microfibrous composition depend u- pon the binding component chosen to be used in its composition.
• the function of the binding component is to provide adhesion of the microfibers.
• the main binding components that may be used in the present composition are: aluminous clays, kaolinitic clays, smectitic clays, mixed clays, colloidal silica and silicic acids.
• other binding components may be used since they exhibit the characteristics necessary for the formulation of the microfibrous composition already described. Tests carried out have shown a relative success with: aluminous clays, kaolinitic clays, smectitic clays, mixed clays or mixture thereof and col- loidal silica, among others.
• microfibrous composition The choice thereof will be conditioned to the final destination of the microfibrous composition.
• kaolinitic clays or aluminous clays may be used and, for low temperatures, smectictic clays.
• the process of curing said microfibrous composition also varies, depending upon the binding component chosen. This process may be carried out: in open air, in ovens or in calcining fumages.
• the apparent specific mass of the microfibrous composition is a function of the special arrangement of the microfibers, as well as of the distribution of average sizes thereof. Values on the order from 0.40 to 0.60 g/cm 3 are more commonly obtained.
• microfiber mesh For lower values, it is necessary to apply procedures that open the microfiber mesh, as for example, by introducing fillers with volatile components and, for higher values, procedures like the application of vibrations that cause approximation thereof, making the aggregate dense. Values from 0.06 to 1.2 g/cm 3 have already been obtained in this way.
• the porosity is inversely proportional to the apparent specific mass, in this case, with very high values, ranging from 45% to 95%.
• the melting temperature of the microfibrous composition will depend upon the type of binding component used.
• the microfibrous composition exhibits melting strength close to this value.
• the melting point will be on the order of from 1550 to 1600° C.
• Aluminous clays permit higher melting temperatures, on the order of from 1600 to 1650° C.
• the mechanical properties of the microfibrous composition will also depend upon the type of binding component used. There are destinations for which there is no interest in high mechanical performance, as is the case of certain heat insulators for "back-up" furnaces, that is to say, those heat insulators that do not receive heat directly from the hottest portion of the furnace.
• the best binding component to be used in the constitution of the microfibrous composition is smectitic clay, when the wish is to obtain high values of strength.
• the strength variation configured by the various types of binding components there are naturally other variations that result from the final apparent specific masses of the microfibrous composition obtained.
• the table below illustrates the values of compression strength obtained after burning, at a temperature of 1 ,250° C, test bodies having kaolinitic cla s as bindin com onents:
• the microfibrous composition comprises kaolinitic clay as a binding component
• the cold compression s- trength increases proportionally with the increase in the apparent specific mass.
• the microfibrous composition generally comprises at least 70% of microfibers and the rest of binding components.
• the a- mount of microfibers is higher than 90%, reaching 99% of the composition, and the remaining amount is of binding components, which compose an extremely thin film enclosing the microfibers.
• the amount of silicon dioxide ranges from about 80% to about 99.0%, and this latter value may be obtained when siliceous chemical binding components are used, like colloidal silica.
• microfibrous composition is basically composed of microfibers and binding components, the microfibers being the main components, the amount of which ranges from 70 to 99%. Examples of microfibrous composition are described below (values in weight, dry base):
• compositions for the production of articles having excellent heat and sound insulation properties preferably contain about 90% by weight of microfibers.
• the binding component is colloidal silica, this amount then becomes 96%.
• FIG. 1 Processes for Obtaining the Microfibrous Composition
• the process for obtaining the microfibrous composition is illustrated in figure 1 and comprises the following steps: a) a mixture of water and at least one binding components is prepared in the proportions of from 80% to 90% of water and the rest of binding compo- nents, obtaining the pulp called barbotine; b) an amount of previously cleaned and loosened microfibers 1 is added, together with the barbotine pulp at a ratio ranging from 1 :3 to 1:5 in an attrition tank 2, provided with rotary tabs driven by reducing mechanisms, to be mixed and homogenized so as to yield a homogeneous pulp 4; c) the pulp 4 is routed through tubes to a shaping equipment 5, where the shape and the consistency of the microfiber agglomerate are checked; settling processes with or
• the microfibrous composition obtained with the curing process 7 may then undergo a firing process 8 at temperatures of up to 800° C, carried out in ceramic furnaces.
• This process is suitable for the microfibrous composition the binding components of which are clays that should be sintered at high temperatures.
• This firing process 8 may be of the continuous type, with the use of tunnel furnaces or roller furnaces or else intermittent, using various types of furnaces, such as the traditional type, called "demijohn furnace", or others.
• the cured microfibrous composition depending upon the requirements of the field of utilization, may be mechanically rectified, whereby warps and imperfections beyond the standard dimension are eliminated. Such grinding 9 is carried out by using grinders.
• the processes are three: a) settling including the variants "simple” or “with vibrations”; b) filtration under pressure, and c) Vacuum filtration.
• the settling process consists of the physical actuation of this process on pulps held in containers, called molds, during an interval of time of about 20 minutes per operation, resulting in a relatively rigid body, configured by the entanglement of the microfibers. Vibrations may be applied in the course of the settling, promoting a decrease in empty spaces between the microfibers, generating a microfibrous composition of greater relative density.
• the pressure-filtration process consists in obtaining a filtered cake, by forced passage of the pulps containing binding components and microfibers through a semipermeable partition, usually a thin web, which contains the microfibers and part of the binding components.
• a filtered cake is wet, consistent to the extent that it can be handled with shapes that are given by molds coupled to the semipermeable partition.
• the pressure is provided by the compressed air to be injected in bell jars o- verlapping the web, or else by forced pumping of the pulp itself. This process will be described in greater detail later.
• the vacuum-filtration process is similar to that described before, with the difference that the filtration accelerating agent is vacuum, which is applies in a hermetic chamber positioned below the semipermeable partition.
• the cake obtained will also be subjected to drying and may also be fired at high temperatures, depending upon the choice of the binding component and upon the destination thereof. All the residual pulps of the three processes defined before are re-used after being reconditioned, the consumed portions of binding compo- nent being replaced.
• the microfibrous composition may be obtained by means of a process called settling process, which consists in the actuation of this process on pulps containing microfibers, where water and the binding compo- nents are also mixed.
• the shaping may be made by means of a simple settling process, wherein the particles settle according to the viscosity of the pulp at speeds ranging from 0.5 to 2.0 cm/min, resting on the bottom of the mold, on top of each other, forming a settled cake.
• settling under vibrations unlike the simple settling, one applies vibrations of frequencies ranging from 0.02 Hz to 40 KHz, provided by mechanical, electric and also ultrasonic vibrators.
• microfibers which are settled on the bottom, intricate arrangements in a single, permeable cake, exhibiting density on the order from 0.8 to 1.0 g/cm 3 , varying according to the degree of aeration to which the residual cake is subjected, which enables the handling thereof on special trays.
• FIG 2 a schematic drawing of equipment designed for molding pieces by settling is illustrated, with or without application of vibrations, with removal of the residual pulp by pouring through the settled cake.
• This equipment comprises a mold 10, where the mixture of the microfibrous composition is held, at its upper part, a container 11 is applied, intended to hold a large amount of pulp 4.
• a partition 12 constituted by a very thin web, which provides a very slow outflow of permeable liquids in the settled material.
• a liquid collecting trough 13 which is welded to the mold 10; this trough 13 has a bore for letting out the residual pump 14 and, at its bottom, it may have a coupled vibrator 15.
• the whole equipment is supported by a s- pring device 16, which may be composed of helical springs or rubber pads of high strength, fixed to the bottom of the trough 13.
• the mold 10 may be of any shape, as long as it will hold the volume of pulp that comprises the microfibers and the binging component(s).
• the mold 10 is triangular in shape with dimensions on the order of 1.40 m x 0.70 m.
• the container 11 may be of any shape that may be use- ful to the equipment, that is to say, it may represent a space corresponding to the pulp volume to be processed.
• the web 12 is preferably very thin, in order to provide better retention of liquid, including a product with less water, but the mesh aperture of the web may vary according to the final product to be obtained.
• one uses a web made of stainless still in meshes of 60 - 200 mesh-tyler.
• the liquid collecting trough 13 has the function of collecting the liquid removed from the initial cake; so, its shape or size are not relevant.
• the pulp 4 containing known amounts of microfibers and binding components (obtained by the process schematized in figure 1) is placed in the mold 10.
• the pulp 4 remains settling for an interval of time ranging from 20 to 30 minutes, so as to achieve the total settling of the particles and the outpour of the residual liquids through the web 12, being collected by the trough 13 and eliminated by the outlet 14.
• vibrations may be applied by actuating the vibrator 5, which will make the whole assembly vibrate, from the spring device 16, which is preferably com- posed of helical springs, whereby the settled cake is made dense.
• use manual techniques or suitable mechanisms may be used for removal of the intermediate product formed here.
• a manual technique indica- ted for removal of the intermediate product above consists in placing a preferably metallic or wooden tray on it, securing it to the side of the mold, turning the whole equipment and supporting the tray on an easel. Once this has been done, the tray is released and the equipment is raised, while the filtered piece remains, now released from the mold, on the easel.
• This technique may be carried out mechanically; for this purpose, all you need is a turning mechanism at the whole equipment via cranes and a mechanism for removing the tray by means of a platform intended to collecting the tray containing the piece thereon, which moves vertically by mechanical actuation.
• the choi- ce of the best technique for removing the intermediate product depends upon the type and dimensions of the pieces to be made.
• the process of filtration under pressure consists in applying pressure onto the pulps containing microfibers, forcing the passage thereof through a partition having small bores, generating a filtered, wet and consistent cake that may be handled (it exhibits a density on the order of 0.8 to 1.0 g/cm 3 , varying according to the degree of aeration to which the residual cake is subjected), the shape of which is given by molds coupled to the partition.
• the filtration under pressure is an intermittent process, in which pressure on the order of 0.5 kg/cm 2 is applied, which will promote acceleration of the process. This operation consists in the forced passage of the pulp through partitions having small bores, smaller than 0.30 mm.
• Such partitions may be webs made of steel, organic materials such as fabrics, sleeves or plastic webs, or else papers suitable for filtration.
• Two mechanisms are used for applying pressure: introduction of compressed air and hydrostatic pressu- rization by pumping the pulp; this latter case is similar to filtration in sleeve filters.
• the pressure applied will depend upon the mechanism used, and it is commonplace to use pressure values on the order of 0.2 to 10.0 kg/cm2.
• the microfibers become a wet cake with some consistency (density on the order of from 0.8 to 1.0 g/cm 3 ), which enables the handling thereof on special trays.
• FIG 3 one illustrates a schematic drawing of a filter driven by pressurized air.
• a filter is usually composed by two main pieces: upper bells 17 and mold 18.
• the upper bell 17 is a container large enough for holding the amount of pulp 4 of a filtration operation; one inserted into it a feed tube 19, which has a coupled diaphragm 19a, which automatically closes when the upper bell 17 is pressurized. Also at this upper bell 17 there is an inlet 20 for compressed air and a safety manometer.
• the mold 18 is a reinforced piece having, at its bottom, a thin web 22 and a lower container for collecting residual pulps 23, in which a tube 24 is installed for discharging such pulps. Between the upper bell 17 and the mold 18 there are moveable claws 25 intended for joining or disjointing the joining of both pieces.
• the pulp 4 the volume of which is previously measured, is introduced in the machine through a feed tube 19 until the desired amount is reached. Compressed air under controlled pressure is injected, which will actuate the diaphragm 19a, closing it and pressurizing the upper bell 17.
• the pressure then forces the passage of the liquids through the single outlet, which is the web 22 situated below the mold 18, forming a filtered cake on said web 22, and the residual pulp flows through the lower container 23, being discharged by the outlet tube 24.
• the filtration process ends when only compressed air comes out of the outlet tube 24.
• the compressed-air inlet should be clo- sed, disjointing the movable claws 25, the upper bell 17 and the filtered piece should be removed.
• the mold 18 may have any shape, as long as it can hold the pulp volume, which comprises the microfibers and the binding component(s).
• the containers 17 and 23 may have any shape that is useful for the equipment, that is, they may have a space corresponding to the pulp volume that is to be worked on.
• the web 22 is preferably very thin in order to promote better retention of the liquid, yielding a product with less water, but the aperture of the web mesh may vary according to the final product that is to be obtained.
• a web made of stainless steel in meshes ranging from 60 to 200 mesh-tyler is used.
• the mold 18,.as well as the bell 17, have particularly rectangular shape, with dimensions on the order of 1.40 x 0.70 m, being hermetic to leakages of liquids or compressed air. They consist of robust pieces, of steel, at least 5 mm thick, made to bear high pressures.
• the movable claws 25 are very resistant pieces, being constructed to bear pressures higher than 15 tons.
• the vacuum filtration process is an intermediate process, wherein the vacuum causes acceleration of the filtration process.
• This operation consists of the forced passage of the pulp through partitions having small bores of less than 0.30 mm.
• partitions may be of steel, organic materi- als like fabrics, sleeves or plastic webs, or else papers suitable for filtration.
• vacuum is applied, so as to bring about suction of the pulp through the partition.
• the microfibers are retained on the partition, and the other liquids are let through the newly formed cake, settling in the lower chamber. The processes end when the whole overlying liquid has been sucked and only air passes through the filtered cake.
• the vacuum is generated by a conventional vacuum pump.
• the industrial plant should have a reservoir where large volumes are accumulated with dif- ference in negative pressure.
• the microfibers become a wet cake with some consistency (density on the order of 0.8 to 1.0 g/cm3), which enables the handling thereof on special trays.
• the mixture containing water and the binding component(s) resulting from the filtration is eliminated or recovered for recirculation.
• a schematic drawing of a vacuum-actuated filter is illustrated. It is basically composed of three main pieces: a pulp reservoir 26, a mold 27 and the vacuum chamber 29.
• the reservoir 26 is a container totally open at its upper part, sufficiently large to hold the amount of pulp of a filtration operation, which is coupled to the mold 27 at its lower part.
• the mold 27 is closed at its lower part by means of a partition 28, which may be, for example, a very thin screen.
• a partition 28 which may be, for example, a very thin screen.
• a vacuum conduit 31 In order to bring about vacuum in the chamber 29, it is necessary to introduce a vacuum conduit 31 , which can make the communication between the chamber 29 and the vacuum reservoir 32.
• a vacuum gauge 33 may be installed for better operational control over the filtration.
• the pulp 4 In filtration operations, the pulp 4, the volume of which is previously measured, the reservoir 26 until the pre-established amount if reached is introduced. Vacuum is applied through the conduit 31 , which causes a difference in negative pressure in the vacuum chamber 29, which in turn causes the diaphragm 30 to close, thus depressurizing the vacuum chamber 29. The vacuum then causes suction of the liquids, forcing them to pass through the partition 28, situated below the mold 27, forming a filtered cake on said partition 28, throughout the mold 27. The residual liquids remain accumulated in the vacuum chamber 29. The filtration operation ends when there is no more overlying liquid over the filtered cake.
• the mold 27 may have any shape, provided that it will hold the pulp volume that comprises the microfibers and the binding component(s). Particularly, the mold 27 has a rectangular shape with dimensions on the or- der of 1.40 m x 0.70 m.
• the container 26 may have any shape that is useful for the equipment, that is, it may represent a space corresponding to the pulp volume that is to be worked on.
• the partition 28 by preference, is a stainless-steel web in meshes from 60 to 200 mesh-tyler.
• the filtration operation does not imply settling processes, differing from the latter by its rapidity, and it is often possible to obtain filtered pieces at intervals shorter than 3 minutes, depending upon the degree of automation and adjust of the operations.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Organic Chemistry (AREA)
• Structural Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Nanotechnology (AREA)
• Geochemistry & Mineralogy (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Composite Materials (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Paper (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
• Filtering Materials (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=34318715

Family Applications (1)

Country Status (7)

Families Citing this family (3)

Family Cites Families (7)

• 2003
  • 2003-09-19 BR BR0304176-0A patent/BR0304176A/pt not_active Application Discontinuation
• 2004
  • 2004-09-17 US US10/572,520 patent/US20070200083A1/en not_active Abandoned
  • 2004-09-17 KR KR1020067006987A patent/KR20070051764A/ko not_active Application Discontinuation
  • 2004-09-17 WO PCT/BR2004/000176 patent/WO2005028389A2/en active Search and Examination
  • 2004-09-17 MX MXPA06003147A patent/MXPA06003147A/es unknown
  • 2004-09-17 CN CNA2004800341373A patent/CN1890195A/zh active Pending
  • 2004-09-17 EP EP04761537A patent/EP1694612A2/en not_active Withdrawn

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events