Apparatus and Process for Producing Fiber from Igneous Rock

Abstract

Methods and apparatus for producing fibers from igneous rock, including basalt include heating igneous rock by electrical conductive coils to achieve an homogenous melt and forming homogenous fibers from the melt.

Claims

1. A method of producing fibers from igneous rock, said method comprising: adding a volume of crushed igneous rock to a furnace chamber, wherein the furnace chamber is at least partially surrounded in a first electrical induction coil; applying alternating current to the first induction coil, effective to heat the volume of crushed igneous rock added to the furnace chamber and to produce a homogenous rock melt in at least a portion of the volume of igneous rock; and passing at least a part of the homogenous rock melt portion through a fiber forming chamber and subsequently passing at least a portion of the volume of igneous rock from the fiber forming chamber through fiber forming orifices under controlled temperature effective to produce fibers, wherein the fiber forming chamber is at least partially surrounded by a second electrical induction coil and the temperature of the homogenous rock melt portion in the fiber forming chamber is controlled at least in part by the power and frequency of electrical current in the second induction coil.

2. The method of claim 1, wherein the controlled temperature at the fiber forming orifices is controlled to within 20° C. to 70° C. of a target temperature.

3. The method of claim 1, wherein the controlled temperature at the fiber forming orifices is controlled to within 30° C. to 60° C. of a target temperature

4. The method of claim 1, further comprising passing at least a portion of said homogenous rock melt portion through a conditioning chamber at least partially surrounded by in a third electrical induction coil and cooling the homogenous rock melt portion effective to produce a laminar flow in at least a portion of the conditioning chamber prior to passing the homogenous rock melt portion into the fiber forming chamber.

5. The method of claim 1, wherein the volume of crushed igneous rock is pre-heated prior to being added to the furnace chamber.

6. The method of claim 1, wherein the volume of crushed igneous rock is heated by exhaust gasses from the furnace chamber prior to being added to the furnace chamber.

7. The method of claim 6, wherein the volume of crushed igneous rock is held in a batch charger prior to being added to the furnace chamber, and wherein the exhaust gasses from the furnace chamber are pumped into the batch charger.

8. The method of claim 1, wherein the volume of crushed igneous rock is heated to a temperature of from about 1300° C. to about 3000° C. in the furnace chamber.

9. The method of claim 4, wherein the furnace chamber is divided into a first zone and a second zone and wherein said second zone is in fluid communication with said conditioning chamber through an opening in the wall of said furnace chamber.

10. The method of claim 9, wherein said first zone and said second zone are separated by an underflow baffle.

11. The method of claim 1, wherein the crushed igneous rock comprises basalt.

12. The method of claim 1, wherein the crushed igneous rock comprises at least one of feldspars, quartz, feldspathoids, olivines, pyroxenes, amphiboles, and micas.

13. The method of claim 1, wherein the crushed igneous rock comprises rhyolite, dacite, andesite, basalt, diabase, granite, granodiorite, diorite, or gabbro.

14. The method of claim 4, further comprising placing temperature sensors at least in the conditioning chamber and the fiber forming chamber and controlling the temperature in the conditioning chamber and fiber forming chamber through computerized control of the electrical current in said second and third induction coils based on feedback received by the computer from the temperature sensors.

15. A method of producing fibers, comprising the steps of: obtaining a quantity of crushed igneous rock to be converted to fiber; transporting said batch to a melting furnace, wherein the melting furnace is at least partially surrounded by a first electrical induction coil; applying alternating current to the first induction coil, effective to heat the batch to a temperature greater than the melting point of all minerals in the batch to produce an homogenous rock melt in at least a portion of said batch; flowing the homogenous rock melt into a conditioning chamber through an opening in an upper portion of a wall of said melting furnace, wherein said conditioning furnace is at least partially surrounded by a second induction coil; applying electrical current to the second induction coil effective to suppress conductive stirring of rock melt and to allow temperature to decrease to produce conditioned rock melt; flowing said conditioned rock melt into a plurality of fiber forming chambers, wherein each fiber forming chamber is at least partially surrounded by a fiber forming chamber inductive coil; applying electrical current to said fiber forming chamber inductive coils, effective to reach and maintain conditioned melt at fiber forming temperature; flowing conditioned melt from fiber forming chambers through a plurality of orifices in bottom surface of a fiber forming chamber to produce fibers extruded from at least a portion of said orifices, thereby forming fibers.

16. The method of claim 15, wherein said crushed igneous rock is preheated in a batch charger prior to being transported to said melting furnace.

17. The method of claim 15, wherein said melting furnace is divided into a first zone and a second zone and wherein said homogenous rock melt enters the conditioning chamber through an opening in the wall of the second zone of the melting furnace.

18. The method of claim 17, wherein said first zone is separated from said second zone by an underpass baffle.

19. The method of claim 15 further comprising shock cooling the fibers by spraying a water mist on said fibers as they emerge from the orifices.

20. The method of claim 15, further comprising gathering individual fibers into a plurality of strands with a gathering shoe.

21. The method of claim 20, further comprising winding one or more of said strands on a winder.

22. The method of claim 15, further comprising producing fibers in a continuous process by obtaining a second and subsequent quantities of crushed igneous rock to be converted to fiber and transporting said crushed igneous rock to said melting furnace to maintain the flow of homogenous rock melt from said melting furnace to said fiber forming chambers.

23. The method of claim 16, wherein heated gasses are removed from said melting furnace and flowed into said batch charger effective to preheat said crushed igneous rock in said batch charger.

24. The method of claim 15 further comprising controlling the temperature in said melting furnace conditioning chamber and fiber forming chambers with a computer; wherein the computer receives temperature data from temperature sensors placed in one or more of melting furnace, said conditioning chamber and said fiber forming chambers and controls power level and AC frequency based on data received from said temperature sensors.

25. A method of preparing igneous rock for use in production of fibers comprising: placing crushed igneous rock in a melting furnace, wherein the melting furnace is at least partially surrounded by an electrical induction coil electrically connected to a power generator; and applying high frequency AC electrical current to said induction coil from said generator with sufficient power to raise the temperature of the crushed igneous rock above the glass melting point of all mineral constituents of said igneous rock.

26. An apparatus for producing fibers comprising: a melting furnace configured with an opening to receive batches of raw basalt or igneous rock, wherein said melting furnace comprises a chamber divided into a first zone for receiving charged batches and a second zone for prepared melt, wherein the first and second zones are divided by an underflow baffle and wherein a wall of the second zone forms an exit opening positioned nearer to the top of the melting furnace chamber than to the passageway under the underpass baffle; a melting furnace electrical induction coil disposed at least partially around said melting furnace; a generator and high frequency converter electrically connected to said melting furnace electrical induction coil; a cooling jacket disposed in the walls of said melting furnace and connected to one or more water supply and heat exchanger units; a conditioning chamber comprising a horizontal channel with a first end and a second end, wherein the conditioning chamber is in fluid communication with said second zone through said exit opening, and wherein the bottom wall of the conditioning chamber forms a plurality of openings in spaced relation along the length of the conditioning chamber toward said second end; a conditioning chamber electrical induction coil disposed at least partially around the conditioning chamber; a generator and high frequency converter electrically connected to said conditioning chamber electrical induction coil; a cooling jacket disposed in the walls of said conditioning chamber and connected to one or more water supply and heat exchanger units; a plurality of fiber forming chambers, each disposed below the conditioning chamber and in fluid communication with the conditioning chamber through one of said openings in the bottom wall of the conditioning chamber, and each fiber forming chamber comprising a fiber forming surface disposed in the bottom of each of said fiber forming chambers, and further wherein each fiber forming surface comprises a plurality of orifices sized and configured to form filaments from rock melt as it passes through said orifices; a fiber forming chamber electrical induction coil disposed at least partially around each fiber forming chamber; a generator and high frequency converter electrically connected to each fiber forming chamber electrical induction coil; and a cooling jacket disposed in the walls of each fiber forming chamber and connected to a water supply and heat exchanger unit.

27. The apparatus of claim 26, further comprising a batch charger comprising a hopper for receiving crushed basalt or igneous rock and for flowing the crushed basalt or igneous rock into said first zone of said melting furnace.

28. The apparatus of claim 27, further comprising an air channel connecting said second zone to said batch charger and comprising a pump configured to draw gasses from the melting chamber and to deliver said gasses to batch charger.

29. The apparatus of claim 26, further comprising a plurality of temperature sensors disposed in the melting furnace, the conditioning chamber and in one or more fiber forming chambers.

30. The apparatus of claim 26, further comprising a plurality of water sprayers configured to spray mist on filaments as they emerge from said orifices.

31. The apparatus of claim 26, further comprising one or more gathering shoes each configured to consolidate fibers from one of said fiber forming chambers.

32. The apparatus of claim 26, further comprising one or more winders configured to receive filament from one or more of said shoes.

33. The apparatus of claim 26, further comprising a computer configured to receive temperature and water flow data from said apparatus and to control said power generators, frequency converters and water supplies.

34. The apparatus of claim 27, wherein said batch charger comprises a motor configured to provide vibration to said hopper configured to facilitate emptying of the hopper.

35. The apparatus of claim 26, wherein one or more of said cooling jackets comprises copper or stainless steel tubes in fluid communication with one or more water supply and heat exchange units.

36. The apparatus of claim 26, wherein at least one generator provides from 500 kW to 10 MW of power at a frequency of 100 kHz to 30 MHz.

37. The apparatus of claim 26, wherein at least one generator provides from 50 kW to 500 kW of power at a frequency of 60 Hz to 100 kHz.

38. The apparatus of claim 26, wherein each of said heat exchange units comprises an air cooler or a cooling tower.

39. The apparatus of claim 26, wherein each fiber forming surface comprises a metal plate.

40. The apparatus of claim 39, wherein the metal plate comprises platinum or a platinum alloy.

41. The apparatus of claim 26, wherein the wherein each of said fiber forming surfaces comprises from 100 to 4000 orifices.

42. The apparatus of claim 26, wherein said fiber forming chambers are cylindrical in shape and wherein the fiber forming surface is round and forms substantially the entire bottom surface of the fiber forming chamber.

43. A fiber made by the process of claim 1.

44. The fiber of claim 43, wherein the fiber has a diameter of from 1 μm to 100 μm.

45. The fiber of claim 43, wherein the fiber has a diameter of from 5 μm to 75 μm.

46. The fiber of claim 43, wherein the fiber has a diameter of from 8 μm to 15 μm.

47. The fiber of claim 33, wherein the fiber is substantially free of non-fused minerals when viewed microscopically.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present inventions. The disclosure can be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

[0068] FIG. 1 is a schematic drawing of a typical furnace system as known in the art for producing fibers from igneous rock.

[0069] FIG. 2 is a schematic drawing of a preferred embodiment of a fiber production apparatus.

[0070] FIG. 3 is a flow diagram of a preferred process.

[0071] FIG. 4A is a side cross-sectional view of an embodiment of a fiber forming device.

[0072] FIG. 4B is an isometric view from the bottom of the fiber forming device of FIG. 4A.

[0073] FIGS. 5A-5D are microscopic views of fibers made by conventional melt methods (5A and 5B) and fibers made by the disclosed method and apparatus (5C and 5D).

DETAILED DESCRIPTION

[0074] The disclosed apparatus and methods address at least some of the problems of producing fibers with conventional furnace technology at least because they do not utilize refractories for kiln heat insulation and they have the ability to heat the rock melt homogenously up to 3000° C. without a mechanical apparatus for stirring. This can achieve a 100% homogenous state of the rock melt even in the presence of such infusible minerals as quartz/quartzite, forsterite; corundum; zirconium, etc. Furthermore, the formation of a layer of skull on the furnace wall protects the furnace from the effects of high temperature and aggressive melt, reducing wear of the walls and greatly extending furnace life. A furnace of the present disclosure is believed to likely have a useful lifetime of 20 to 30 years, for example, as compared to a lifetime of 2-5 years for a furnace used in conventional rock melting technologies.

[0075] There are three basic stages of melting igneous rock in a furnace, startup (including initial lighting and/or heating to target temperature), routine operation, and shutdown, typically for repair or maintenance. Due to the technical limitations of conventional tank furnace design and refractory materials, the startup process of lighting and heating usually requires a gradual ramp up in temperature with adjustments to the structure as the temperature increases, a process that takes an average of up to 20 days. The time for shutdown for a conventional furnace is approximately equal to the startup, to avoid cracks and destruction of refractories during cooling. During the normal operational mode for conventional furnace tanks, inefficiencies are often experienced due to the inertia of the melt, especially dark melt, as with igneous rock. Conventional heating devices such as gas or heating electrodes act locally causing temperature discontinuities to exist throughout the volume. In certain cases it can take hours to achieve an homogenous temperature.

[0076] By contrast, the disclosed apparatus and methods can achieve a uniform thermal effect on the entire volume of the melt through circular electric currents, known as eddy currents, induced within the melt by a changing magnetic field. Eddy currents, also called Foucault currents, are loops of electric current induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. This process distributes heat evenly throughout the entire volume of the melt, which serves as the conductor in this case. The procedures for startup and shutdown for an apparatus of the present disclosure can take just an hour and adjusting the melt temperature of the entire body of melt can take minutes. The process is thus very flexible, and can be stopped and started at any time as needed without long delays.

[0077] An example of a preferred embodiment of an apparatus for manufacturing continuous fibers is shown in FIG. 2. The apparatus 100 includes a batch charger 101 which includes a hopper for receiving crushed basalt or raw igneous rock. The hopper can be designed to hold approximately 25 cubic feet in some embodiments, and up to 1200 cubic feet or more in an industry setting, and can include one or more small motors 128 of from 2 to 5 horsepower for example, or even 2.5 horsepower to vibrate the charge from the hopper to a tray for dumping the raw rock 130 into the melting chamber 102. The melting chamber 102 is divided into two zones, the charging zone 130 and the prepared melt zone 134. The two zones are separated by an underflow baffle 103 to maintain the melting ore in the charging zone until complete homogeneity is achieved. While described herein as a single melt and charging zone in a furnace chamber, it is understood that multiple chambered furnaces can be employed in the processes described herein, in which one or more melt zones are separated from one or more charging zones by one or more baffles, or that variations of baffles other than underflow baffles can be employed.

[0078] A generator and power supply 104 provide electrical current to an induction coil 105 that wraps the melting chamber 102. In certain embodiments a 500 kW power supply with a high frequency (HF) converter can be used. It is understood of course, that choice of power supply and converter frequency will depend on the particular application and furnace design, and that the described power is an example of a preferred embodiment. Additionally, the power supply and converter can be contained in a single device as shown, or can be in separate locations as required by individual furnace design. For example, a single electrical coil can serve multiple furnaces, or a single furnace or chamber can employ multiple induction coils.

[0079] A pump 106 draws gasses from the melting chamber through piping 126 and supplies the heated gas to the batch charger 101 for preheating. A water supply and heat exchanger unit 107 are also connected to the melting chamber 102 for cooling. A heating exchanger can be of any type known in the art and can be selected from dry air coolers and cooling towers, for example, or other types depending on the environment in which the furnace is operated.

[0080] The melted rock is drawn from the prepared melt zone 134 into a conditioning chamber 108 connected to melting chamber 102 in such a way that the melt flows from the charging zone 132 under the underflow baffle 103 and rises to the opening into the conditioning chamber. The conditioning chamber is preferably configured as a horizontal channel that cools the melt from the furnace temperature to the fiber forming temperature, and directs the melt to the fiber forming chambers. The melt can be cooled, for example from temperatures in the range of 3000° C. or 2000° C. or 1800° C. or 1400° C. to a temperature that reduces turbulence and produces laminar flow in the conditioning chamber 108. Flow can be controlled in response to temperature readings provided by temperature sensor devices 120 disposed at various points of the flow path including at the opening into the conditioning chamber 108 as shown. It is understood that sensors can be placed throughout the system as needed and that the placement of sensors in the embodiment shown in FIG. 2 is only an example and is not limiting.

[0081] The temperature in the conditioning chamber 108 is controlled in a preferred embodiment by a separate induction coil 109, powered by a separate generator and power supply 127, and cooled by a separate water supply and heat exchanger unit 111. The power supply 127 for the conditioning chamber 108 can be smaller, such as 250 kW for use in a particular embodiment, for example, and the water supply and heat exchanger can be separate but of the same types as the heat exchanger for the melting chamber. It is understood, however, that the conditioning chamber can have a lower cooling capacity requirement.

[0082] A plurality of fiber-forming chambers 125 extend from the bottom along the channel of the conditioning chamber 108 and include an upper opening 136 for flow of melt into each fiber-forming chamber 125. The number of fiber-forming chambers is determined by the capacity of the melting chamber and can be 2, 3, 4, 5, 10, 20 or more. The fiber-forming chambers can be considered as small furnaces with tightly controlled temperatures. Each fiber-forming chamber 125, in this particular embodiment, includes an induction coil 113 and in certain embodiments, individually controlled power supply and generator 140, and water supply and heat exchanger system 110. The bottom of each chamber 125 is formed at least in part by a fiber-forming device 115 which can be a metal plate such as a platinum or platinum alloy plate attached to the bottom of each fiber-forming chamber 125 and including a pattern of openings or orifices, optionally tipped by nozzles. As the cooling melt is drawn through the orifices to form fibers 142, cooling water sprayers 146 shock cool the fibers with mist to prevent recrystallization. The fibers are then gathered into filaments on a shoe device 145 and attenuated on winders 123. The process can be controlled and managed with a computerized process management system 122.

[0083] An embodiment of a fiber forming device 200 is shown in FIGS. 4A and 4B. As best seen in FIG. 4B, the fiber forming device 200 is round and the fiber forming chamber 125, which receives the molten rock is wrapped in a water jacket 206, which is wrapped with an induction coil 113. The entire bottom of the chamber forms the orifice (nozzle) plate 208 in which the nozzles 210 are formed. This configuration operates to minimize distortion under operating temperature and under the head of molten rock above the orifice (nozzle) plate; and to maintain the very large orifice (nozzle) plate at uniform temperature.

[0084] Hot melt contact with the water-cooled walls of the fiber forming device is solidified to form a thin layer of skull 212, which not only protects the walls from corrosion but offsets the exponential heat distribution from the walls to the center axis of the device. Skull is understood in the art to be a layer of iron or slag solidified on the inner surface of the furnace lining. In embodiments of the disclosure, a round shaped container body, an induction coil and regulation of water temperature and water flow rate in the walls of device make it possible to achieve a uniform heat distribution all over the melt body. With some additional arrangements such as installation of water cooled ribs, the disclosed device allows orifice (nozzle) plates of very large sizes (6000 tips and up) without adversely affecting the fiber attenuation process. This process is thus highly compatible in terms of capacity and production cost with existing conventional fiberglass production processes. It is also up to 50% more energy efficient than conventional orifice (nozzle) plate heating methods.

[0085] In the practice of the methods of the disclosure, raw material such as crushed igneous rocks with or without supplemental materials can be preheated in the batch charger 101 and transferred to the primary melt melting chamber 102. In the melting chamber 102 the raw material contacts hot melt within the chamber and is combined with the hot melt as a result of circular electric currents induced by the coil 105. The conductivity and thermal effect on the raw material increases until a complete change of state, from solid to liquid is complete. It is an aspect of the disclosure that the melt process can be enhanced by the addition of graphite, either a graphite ring or powder, to the initial batch. After the initial melt, no further enhancement is necessary. The first melt product that may or may not include an enhancer is typically discarded.

[0086] During operation, the frequency F1 and power P1 of a generator 104 are set to provide a stable and intense stirring effect throughout the melt volume, to melt all minerals in the initial raw material and to achieve a 100% homogenous material. By regulating F1 and P1, the melt temperature can be adjusted within a range of from about 1300° C. to about 3000° C., for example.

[0087] The melting chamber 102 and underflow baffle 103 can be composed of copper or stainless steel tubes, which can be continuously supplied with cooling water. The walls of the melting chamber 102 and underflow baffle 103 can be protected by skull which is formed between the wall and the melt and water flow can cool the melt at the heat exchanger unit 107.

[0088] Gases that are released during the melting process can be pumped out of the melting chamber 102 by pump 106 through special openings in the top of melting chamber 102 and routed to the batch charger 101 for preheating the raw material.

[0089] The homogeneous melt then can enter the conditioning chamber 108 located above the bottom level of the melting chamber 102. The conditioning chamber 108 can be connected to the melting chamber 102 on the opposite side from the raw material charger and the melting chamber 102 can include two zones separated by an underflow baffle 103. This baffle can prevent non-molten materials from the charging zone side of the melting chamber from entering the conditioning chamber prior to being fully melted.

[0090] The conditioning chamber 108 can be heated by currents induced by coil 109. Frequency F2 and power P2 generated by generator 109 can be set at levels that suppress the stirring effect inside the conditioning chamber 108 and lower the temperature of the melt to reduce turbulence and produce laminar flow in the conditioning chamber.

[0091] The conditioned and stabilized melt can then flow to the fiber-forming chambers 125. Each fiber-forming chamber 125 can be made of copper or stainless steel tubes or any appropriate material known in the art, which can be continuously supplied with cooling water provided by a separate water supply and heat exchanger units 110. The cooling of the walls of the fiber-forming chamber 125 by the water creates a layer of skull between the wall and the melt protecting the refractory from degradation by the melt. The temperature and viscosity of the melt inside each fiber-forming chamber 125 can be controlled by generators 140 and induction coils 113. Frequency F3 and power P3 can be set at levels that maintain temperature and viscosity within the narrow range as required for filament formation.

[0092] Fiber-forming devices 115 can be attached to the bottom of each fiber-forming chamber 125. Each fiber-forming device can be a specially shaped plate made of heat-resistant materials with numbers of orifices that let rock fiber filaments form as they pass through and out of the orifices Filaments that are coming out of fiber-forming devices can be exposed to shock cooling by means of fiber filament cooling devices 146. The fiber filament cooling devices 146 can be designed as a set of nozzles, which create a pressurized cold-water mist located just under the fiber-forming device; this arrangement can be necessary to avoid reverse crystallization during the fiber forming process. The process produces 100% homogenous filaments without any crystallinity or surface defects. Crystals and surface defects would significantly reduce the mechanical strength of the fibers. Microphotos of fibers formed by conventional technology and by the disclosed systems and methods are shown in FIG. 5. As can be seen in FIGS. 5A-5D fibers formed by the disclosed method are substantially free of crystalline particles caused by incomplete melting.

[0093] The formed filaments then pass through sizing agent applicators (not shown), and can be assembled in strand by gathering shoes 145 and wound on cakes by winders 123. The formed fibers can be preferably of about 8 to about 15 μm in diameter. The entire process can be controlled and managed by a computer process management system 122 that manages frequencies, powers, water flows and charger according to input data received from temperature sensors 120 and winders 123.

[0094] It is a further aspect of the disclosure that rock fibers produced by the apparatus and methods disclosed herein are contemplated to be of higher quality, e.g. free or substantially free of weaknesses caused by incomplete melt and produced at lower cost than conventionally produced fibers. The disclosed fibers are thus useful in numerous applications in a variety of industries, including but not limited to the computers and electronic industry, the construction industry; the chemical, cryogenic and oil industries; the automotive and marine industries; as well as for space, defense and ballistic applications; fire and heat protection; sound insulation; civil engineering and pipes; and high-pressure tanks and cylinders. Contemplated as an aspect of this disclosure are the many products that are likely to contain such fibers, including but not limited to, construction beams, concrete, insulation, pipes and tools, computers and electronic devices including antennas, sporting goods, protective equipment for police, defense and recreation as well as structural components of automobiles, boats, airplanes and other types of vehicles. The uses of the disclosed fibers mentioned above and all others apparent to those of skill in the art are contemplated to be within the scope of the present disclosure.

[0095] All of the apparatus, compositions and methods disclosed and claimed herein can be made and/or executed without undue experimentation in light of the present disclosure. While the apparatus, compositions and methods of this disclosure have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus and/ compositions and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain materials or structures that are chemically, functionally or structurally related may be substituted for those described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.