WO2002079113A1 - Traitement thermique de materiaux expansibles dans le but de former des agregats legers - Google Patents

Traitement thermique de materiaux expansibles dans le but de former des agregats legers Download PDF

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Publication number
WO2002079113A1
WO2002079113A1 PCT/GB2002/001391 GB0201391W WO02079113A1 WO 2002079113 A1 WO2002079113 A1 WO 2002079113A1 GB 0201391 W GB0201391 W GB 0201391W WO 02079113 A1 WO02079113 A1 WO 02079113A1
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WO
WIPO (PCT)
Prior art keywords
kiln
heat treatment
chamber
microwave
temperature
Prior art date
Application number
PCT/GB2002/001391
Other languages
English (en)
Inventor
Robin Anthony Kyffin
Eifion Wyn Williams
Original Assignee
Ffestiniog Expanded Slate Company Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ffestiniog Expanded Slate Company Limited filed Critical Ffestiniog Expanded Slate Company Limited
Publication of WO2002079113A1 publication Critical patent/WO2002079113A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/34—Arrangements of heating devices
    • 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
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/02—Treatment
    • C04B20/04—Heat treatment
    • C04B20/06—Expanding clay, perlite, vermiculite or like granular materials
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/64—Heating using microwaves
    • H05B6/80—Apparatus for specific applications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B1/00—Shaft or like vertical or substantially vertical furnaces
    • F27B1/10—Details, accessories, or equipment peculiar to furnaces of these types
    • 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
    • F27D15/00—Handling or treating discharged material; Supports or receiving chambers therefor
    • 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
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F27D2099/0028—Microwave heating

Definitions

  • This invention relates to heat treatment of expansible materials to form lightweight aggregate.
  • lightweight aggregate can be produced commercially by suitable heat treatment of certain mineral and rock materials. These include clays, shales and slates of suitable chemical and mineral composition. Before such treatment, in general these materials have to be prepared by size grading and drying. Most usually, the minerals are formed into particles; slates and shales are used in such processes in the form of chippings whereas clays are formed as pellets. Sizes are usually in the range 4 mm to 20 mm.
  • Treatment involves heating of the particulate material to the point where fusion starts to occur with the material being taken into a plastic state.
  • temperatures There is a wide variation of such temperatures, depending on the material under treatment. These are usually in the range 1100 to 1300 °C.
  • the material under treatment starts to fuse, each particle on its outer surface first. This tends to seal the particle. Then, as heat penetrates to raise the interior temperature, gases are formed within the particle. Such gases cannot easily escape through the sealed surface and they act on the plastic material of each particle, forcing expansion to take place.
  • the material is removed from the heat source as speedily as practicable and cooled to preserve the expanded structure. Expansions of up to five times the original volume are possible and the resulting aggregate has a hard outer skin with a cellular structured interior full of voids. The resulting bulk density can be as low as one fifth of that of the original feed stock.
  • Heat treatment can be effected in a number of devices including travelling grate furnaces, fluidised bed furnaces, rotary kilns, tunnel kilns and more including any device capable of transporting material through a heat transfer zone at high temperature and heating the same to that temperature, rotary kilns being used most commonly.
  • the process temperature may be reduced. For example, in the hottest zone, the temperature may be reduced by some 20 to 50 °C below the optimum for expansion. By this means the sticktion problem is eliminated. However, the product is then only partially expanded.
  • a refractory usually coarse-grained powder is mixed with the feed particles.
  • This powder typically has a grain size of 0.25 mm to 1 mm, and a melting point substantially greater than that of the material under treatment.
  • Fairly pure silica sand could be used. Amounts of powder are typically 20% by weight. However in order to obtain the very best expansions by using a slightly higher temperature again, a greater proportion of powder is needed.
  • the powder acts in two ways, firstly to line the kiln refractory providing it with a non sticky surface at high temperature and secondly to keep the individual feed particles from sticking together by coating them with a non- sticky layer a high temperature.
  • the powder can be separated from the product after cooling and can thus be reused. The method is effective but does carry a penalty in that additional energy is needed merely to heat the powder to temperature.
  • a principal aim of this invention is to overcome, or at least ameliorate, the sticktion problem in a manner that is compatible with a wide range of treatment apparatus, and with rotary kilns most especially, without encountering disadvantages of known approaches.
  • this invention provides a method of heat treatment of expansible materials to form lightweight aggregate in which material is heated within a kiln to a temperature less than that required for optimum expansion, and then further heated by application of microwave energy.
  • the outer surface of the material remains below its full fusion temperature within the kiln, it does not have a chance to agglomerate and stick to the lining of the kiln. Heating with microwave radiation tends to heat the core of the particles, providing the internal temperature required for full expansion. The surface of the particles preferably remains below the full fusion temperature.
  • the material may be heated by microwave energy externally of the kiln or within the kiln, typically at a region near to a discharge of the kiln.
  • the material is preferably heated in the kiln to a temperature just (a small amount) below that required to achieve full expansion prior to application of microwave energy.
  • the material may be heated in the kiln to a temperature less than 50° or 60 °C (for example, in the range of 20 to 30 °C or 30 to 40 °C) below the optimum expansion temperature.
  • refractory powder In order to further reduce the risk of sticktion and agglomeration of the material under treatment, it is preferable to add a proportion (e.g. 10% by weight) of refractory powder along with the material. Both the material and the refractory powder are subject to microwave energy towards the end of the treatment process. Some of the refractory powder may advantageously remain as an adhesion-resistant coating in parts of the apparatus. In such embodiments, the refractory powder is most preferably selected as to be non-absorbent of microwave radiation in order than it is not heated by the microwave energy.
  • Such refractory material may include highly aluminous materials. A material of being largely alumina or of highly aluminous bauxite may be suitable.
  • references to refractory materials in this specification can be taken as typically referring to materials of this type.
  • the same considerations apply to refractory materials that are used within the construction of the apparatus.
  • the region of the apparatus in which microwave energy is applied is most typically enclosed within a microwave containment casing, typically of microwave-reflective metal to prevent leakage of microwave energy into the environment. Any aperture that penetrates the casing must be equipped with suitable seals or filters to prevent leakage.
  • the temperature (at least within the core of the particles) of the material is preferably raised to the optimum for expansion by the application of microwave energy of suitable frequency either in the kiln close to discharge or after discharge from the kiln. In the latter case, microwave radiation is preferably applied immediately after the material has exited the kiln, in order that it has a minimum amount of time in which to cool.
  • the material may, for example, include slate, typically in the form of chippings.
  • the material may be heated in the kiln (or in the kiln and subsequently in a microwave chamber) to a temperature of approximately 1210 °C.
  • Other materials may be used, such as shale, clay or other minerals, each being heated to a particular temperature to achieve full expansion.
  • this invention provides heat treatment apparatus for production of expanded aggregates comprising a kiln for heating particles, and a microwave system for supplying microwave energy to material that has exited the kiln.
  • Apparatus embodying this aspect of the invention can typically be used in carrying out a method according to the first aspect.
  • the kiln is most usually a rotary kiln, but could be any other device suitable for heating the material to the temperature required.
  • it may be a travelling grate furnace, a fluidised bed furnace or a tunnel kiln.
  • the microwave system may include an elongate chamber through which particles that have exited the kiln can pass under the action of gravity.
  • the chamber rotates axially in use to assist the transport of material through the chamber.
  • the chamber may formed with a plurality of axially extending pockets between which material falls when the chamber rotates. The effect of this is to tumble the material form one pocket to the next during exposure to microwave energy.
  • the chamber is disposed with its axis approximately vertical. Such a chamber need not rotate to cause the material to pass through it; indeed, it is typically necessary to provide internal formations that control the speed at which material passes through the chamber under the action of gravity.
  • the chamber has a refractory lining that is highly transparent to microwave radiation.
  • the refractory material is most usually contained within an enclosure that contains microwave radiation to prevent leakage of microwave energy into the environment.
  • apertures in the enclosure through which material under treatment pass are advantageously provided with filters that inhibit passage of microwave radiation through the apertures.
  • This invention also provides a method and an apparatus for production of expanded aggregates substantially as herein described with reference to the accompanying drawings.
  • Figure 1 shows diagrammatically a section through the discharge end of heat treatment apparatus being a first embodiment of the invention
  • Figure 2 shows diagrammatically a section A-A through the discharge end of heat treatment apparatus being a second embodiment of the invention
  • Figures 3 shows a section of a kiln rotor of the embodiment of Figure 2;
  • FIGS 4 and 5 are diagrammatic elevations of a microwave chamber of a third embodiment of the invention.
  • the embodiments will be described with reference to a system for expanding materials in a rotary kiln and the following discourse on the invention relates to this device.
  • the invention has equal application to systems that are based on other types of treatment apparatus.
  • Kiln chamber lengths and types vary but the sticktion problem is encountered with all of them.
  • the material Towards discharge, over the final quarter or so of the chamber's length, the material reaches incipient fusion at high temperature and then the transit time to discharge must be sufficiently long for heating of the interior of each particle to take place. The result is that there is then a strong tendency for the particles to stick together and form large agglomerations and also for some sticktion of the material to the lining to take place. This impinges on the reliability of the process and prevents an orderly transit of material through the hottest zone of the kiln.
  • heat treatment apparatus being a first embodiment of the invention includes a rotary kiln that has an inclined tubular chamber 10 (only a hot discharge end portion of it being shown in Figure 1), usually lined with refractory material, which is made to rotate about an axis that is inclined slightly to the horizontal. Particulate feed material as above described is fed into the upper end of the chamber 10 and is progressively heated as it travels along the chamber 10 as this rotates. Residence time within the chamber 10 is determined by a combination of speed of rotation and angle of inclination. Heat is supplied by a burner 12 at the lower end of the chamber 10, the material being discharged there after having been heated to the required temperature. A hood 14 of refractory material seals the chamber 10 (except for an exit route through a discharge chute 16) and provides a burner aperture.
  • Heated material exiting the chamber 10 falls into a refractory lined and insulated enclosed discharge chute 16, and from there, enters a conically shaped microwave chamber 18, insulated and refractory lined.
  • the microwave chamber 18 has an exit that through which material can leave it. Material flow through this exit to a cooler below is induced by a conveyor at the cooler discharge at a rate such that a body 20 of material is formed within the microwave chamber 18, whereby the material has a dwell time within the chamber. A control system is employed to adjust the rate of the conveyor to maintain the body 20 at an optimum level within the microwave chamber 18.
  • Microwave radiation is introduced into the chamber by an array of several waveguides 22.
  • the waveguides are disposed such that they apply microwave radiation as evenly as possible to the surface of the body 20. They are also constructed to be resistant to heat that will be absorbed from material being treated.
  • slate chippings and an admix of refractory powder move down the kiln chamber 10 at a rate of 7000 kg/hour and 700 kg/hour respectively. Both are discharged at a temperature of 1210 °C.
  • the chippings By the time the chippings reach discharge they will have been heated right through and their surfaces will have lightly fused providing a sealed surface.
  • the chippings will be sealed but only partially expanded.
  • Chippings and admix then fall down the exit chute 16 to the microwave chamber 18 to form a cone-shaped body 20 in the microwave chamber 18.
  • the chamber 18 is well insulated as is chute the exit so that heat loss is small in relation to the mass flow rate of materials arriving. This ensures that there will be insignificant loss of particle surface temperature on arrival in the microwave chamber 18.
  • the surface of the body of partially expanded slate chippings will be under the influence of a microwave flux supplied from the waveguides 22.
  • the microwave energy incident on the conical surface then heats the interior of the slate pieces preferentially to a temperature of 1230 to 1240 °C with only a small rise in particle surface temperature. This internal rise of temperature causes maximum gas generation within the particles and thus ensures maximum expansion.
  • the surface of the body 20 will be under continuous renewal by material under treatment falling from above. This being so, the degree of penetration of microwave energy into the bulk of the deposit is not of crucial importance.
  • the microwave power needed to cause this 20 to 30 °C temperature rise on 7000 kg/hour is expected to be in the order of 40 kW, although experimentation may show that more or less power is required in a particular installation. Calculations suggest that the energy supplied in the form of microwave radiation represents only some 2 to 3 % of the total power requirement., provided that efficient heat recovery and insulation systems are used.
  • FIG. 2 A second embodiment of the invention is shown in Figures 2 and 3.
  • heat treatment apparatus embodying the invention shows the discharge trunk of a rotary kiln 110. coupled by a gaiter or packing 112 to an inclined insulated chute 114.
  • the apparatus includes a microwave chamber 118 that comprises an inclined cylindrical rotary vessel 124 of microwave reflective stainless steel. (Support rollers, thrust and drive arrangements are provided for the camber but these are not shown.)
  • the angle of inclination is typically between 3° and 15° to the horizontal and is adjustable.
  • the rotary vessel 124 is lined with high alumina microwave transparent refractory 120 which is backed with high alumina fibre microwave transparent insulation 122.
  • the refractory lining 120 is in the form of sixteen deep, rounded, concave pockets 150 as shown in Figure 2.
  • the design speed for the rotor is 0 to 10 r. p. m.
  • a stationary end wall 126 is provided to close the feed end of rotary vessel 124. This is of similar construction to the chamber 118 having high alumina refractory backed by high alumina fibre insulation all contained within a microwave-reflective stainless steel casing.
  • Microwave seals 132 are provided between the fixed end walls and the rotor.
  • a chute 114 feeds material exiting the kiln 110 as far as a stainless steel of the end wall 126 of the vessel 124.
  • a microwave filter 116 prevents escape of microwave energy from the chamber 124 where it is penetrated by the chute 114.
  • the filter includes a stainless steel tube or set of tubes with dimensions related to the microwave wavelength. In the case of the normal industrial microwaves of frequency 915 MHz as used in this embodiment, the tube diameter is of the order of 140 mm with a corresponding length of about 450 mm.
  • the filter tube (or tubes) 116 feed into a high alumina, non-absorbent refractory feed chute 128.
  • a flue 142 as shown in Figure 2.
  • the flue 142 similarly incorporates a microwave filter similar to that employed at 116.
  • a waveguide 134 feeds microwave energy at 915 MHz.
  • the waveguide 134 connects accurately with the stainless steel casing and directs the microwave energy through the transparent alumina of the linings.
  • an additional wave guide supply is provided at the other end of the vessel 124.
  • the actual number and disposition of the wave guides to introduce the energy into the chamber can readily be determined by routine experimentation or calculation.
  • a stationary discharge hood 130 again of constructed with a stainless steel casing and alumina refractory and insulation lined. Material falling from the discharge end of the vessel 124 enters the discharge hood 130 and falls through it. Opposite the path taken by the charge of material entering the discharge hood 130, there is provided a low-output burner 136 with a correspondingly positioned flue 142 in the stationary end wall 126 of the vessel 124. Both the flue and burner are provided with microwave filter or barrier arrangements as previously discussed.
  • a window 138 At the bottom of the end wall approximately opposite the feed chute 114, there is provided a window 138, for viewing the regime within the chamber and for optical or radiative temperature measurements.
  • a microwave barrier or filter is incorporated into the window 138.
  • a set of microwave filter tubes 140 is positioned and the output of expanded aggregate and refractory powder fall out of the system through these tubes 140 to a disposal route incorporating a cooler and thence to stockpiles.
  • the whole system in its entirety between rotary kiln 110 discharge and disposal route is capable of adjustment in terms of angle of inclination of the rotor axis to the horizontal.
  • angle of inclination and speed of rotation the residence time of material within the chamber 118 can be controlled.
  • the whole device In order to line up with the rotary kiln 110 discharge, the whole device is capable of being moved bodily in the horizontal plane to allow for misalignment caused by adjustment of angle of inclination.
  • the disposal route is capable of adjustment as necessary to effect alignment
  • This embodiment has the following important features that make for effective working and operation.
  • the residence time of material within the microwave chamber is entirely adjustable. Operational residence times are typically between 5 and 20 seconds. There has to be a minimum acceptable residence time to enable the material to respond to the energy and to enable a control system to operate in terms of microwave energy supplied in relation to the chamber throughput and temperature rise achieved.
  • the profile of the rotor refractory in the form of sixteen deep, rounded pockets has the effect of dividing the charge into discrete bundles thereby tending to limit the size of any agglomeration that might form. Furthermore the pockets will retain their contents for approximately 120° of rotation and at 6 r. p. m. this equates to some 3 seconds only. During this time the particles will rearrange themselves by reason of expansion. Being stationary in relation to the lining, the expansion will tend to cause rearrangement without compaction and after the short time of approximately 3 seconds the material will fall out.
  • the heat transfer relationship between lining and charge is different to that existing within a rotary kiln. Instead of transfer from lining to charge the reverse takes place in that the lining loses heat to the casing which is then replenished by heat loss from the charge. If the burner 136 is not brought into play, the lining will settle in equilibrium at a lower temperature than the materials in transit for any set of steady-state conditions. This contributes to the prevention of sticktion.
  • the chamber is also supplied with refractory powder. The risk of sticktion to the lining is therefore small. In any event the regime can be observed and more refractory powder can be supplied in the event of sticktion appearing to be imminent. Additionally, although microwave heating is in progress, heat transfer from the particles in transit to the lining will tend to lower their surface temperature. This reduces the likelihood that agglomeration will occur.
  • the principal purpose of the low output burner 136 is to raise the chamber temperature to that required for operation prior to start-up. However, it can also be used to supply casing losses, and to control the temperature of the lining consistent with safe operation of the chamber. This allows greater control of product quality and particularly the condition of aggregate skin by being able to exert some influence on particle skin temperature. Again, the viewing window 138 allows an operator to judge what is safe. With regard to the profile of the rotary chamber, all manner of rib and pocket designs are possible all within the scope of the invention. This example is intended to demonstrate a particular arrangement of what is possible under the invention.
  • the chamber dimensions could be approximately as follows:
  • Rotary chamber 124 length 1800 mm
  • Each pocket 150 when full to the brim can contain at least 18 litres of material (the volume of refractory powder is ignored in this figure, since it will be small and will not affect the overall volume).
  • partially expanded aggregate will arrive with a bulk density of about 650 kg/m 3 . Therefore, each pocket 150 can contain as much as 11.5 kg.
  • the lightest aggregate is expected to be some 280 kg/m 3 and at this density each pocket 150 could contain 5 kg. This is the extreme case where the aggregate is at its lightest.
  • the rotary kiln 110 is operated in an entirely reliable manner with an operating temperature of 1160 °C.
  • the feed rate is 7000 kg/hr of 4 to 12 mm slate (or other) chippings accompanied by 700 kg/hr (10%) bauxite powder sized 300 to 900 ⁇ m.
  • Partially expanded slate with a bulk density of approximately 650 kg/m 3 with the bauxite falls out of the kiln and passes into the microwave chamber 118. This partially expanded slate at approximately 1160 °C will be just starting to fuse and will be thus sealed and will have been heated right through.
  • the speed of rotation of the chamber 118 is set at 6 r. p. m. with an angle of inclination to effect a residence time of 15 seconds. 7000 kg/hour equates to a throughput of approx. 2 kg/s. This means that the chamber will only contain approximately 30 kg of chippings.
  • the product is discharged from the chamber 118 via the outlet microwave filter 140.
  • pockets 150 At any time, approximately six pockets 150 contain a total of 30 kg of slate chippings (i.e. approximately 5 kg per pocket). At the lightest envisaged density of around 280 kg/m 3 , this will not exceed the pocket capacity of 18 litres. Even if this were to happen, some spill-over towards the discharge end, in the time scale of 15 seconds residence time would not matter.
  • the product leaves the chamber fully expanded at an average temperature of 1200- 1210 °C. In the time scale of 15 seconds, and with the charge divided as described, agglomeration is unlikely to be a problem.
  • a particular advantage of this embodiment is the degree of control of the process that is possible, and that the control can be judged by observation through the window 138, this being additional to information provided by instrumentation. For any set throughput, there is provided:
  • FIGS 4 and 5 are diagrammatic elevations of a microwave chamber that includes a cascade of tiles which slow material in free fall to provide a useable residence time for the microwave energy to effect the desired degree of heating.
  • a rotary kiln discharge trunk 160 feeds partially expanded slate mixed with refractory powder into a microwave chamber 164 through a microwave filter 162.
  • the chamber 164 has a microwave-reflective stainless steel casing 166 lined with a microwave- transparent refractory and insulating system similar to that described in the second embodiment.
  • a cascade of microwave transparent (aluminous) tiles 170 is incorporated in to the system. These are set at approx. 35° to the horizontal.
  • Exit filter tubes 160 are provided to seal the chamber - a requirement that has already been discussed.
  • Microwave energy is introduced into the chamber via wave guides 172 and the energy passes through the transparent lining. The height and number and exact disposition of the tiles will be determined by experiment and modelling.
  • the microwave power needed to effect 50 °C rise in temperature on 7000 kg/hour is about 80 kW. Allowing for losses in the microwave generator and its system the actual power input would be some 120 kW. Investigations show that at this level the microwave energy would be only some 5-6 % of the total energy requirement of a modern thermally efficient expanded aggregate production plant incorporating all available energy saving measures.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Ceramic Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)

Abstract

L'invention concerne un procédé et un appareil de traitement thermique de matériaux expansibles permettant de former un agrégat léger. Le matériau est chauffé à l'intérieur d'un four à une température inférieure à celle requise pour obtenir une expansion maximale. Puis ce matériau est chauffé par application d'énergie micro-onde afin de compléter son expansion. Dans un mode de réalisation typique, le chauffage initial du matériau est réalisé dans un four à une température inférieure à sa température optimale d'expansion. On lui applique ensuite une énergie micro-onde à l'intérieur ou à l'extérieur du four. Le procédé et l'appareil peuvent être utilisés avec un matériau tel que des déchets d'ardoise, du schiste, de l'argile ou un autre matériau. Ce matériau peut être mélangé à un matériau réfractaire n'absorbant pas le rayonnement micro-onde, notamment l'alumine ou la bauxite.
PCT/GB2002/001391 2001-03-29 2002-03-22 Traitement thermique de materiaux expansibles dans le but de former des agregats legers WO2002079113A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0107827A GB2373842A (en) 2001-03-29 2001-03-29 Heat treatment of expansible materials to form lightweight aggregate
GB0107827.8 2001-03-29

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT512271A3 (de) * 2011-11-17 2016-01-15 Horst Wustinger Verfahren für das Herstellen von porösen Körnern aus Wasserglas
EP2625482A4 (fr) * 2010-10-07 2017-06-07 Milt D. Mathis Four rotatif à micro-ondes
WO2023242289A1 (fr) * 2022-06-17 2023-12-21 Colas Procédé de production industrielle d'argiles calcinées

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2850520B1 (fr) * 2003-01-24 2006-09-15 Entema Dispositif de chauffage par rayonnement micro-ondes et procede de mise en oeuvre
FR2850519B1 (fr) * 2003-01-24 2010-09-24 Entema Procede et installation pour le chauffage de granules par un rayonnement micro-ondes

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62260741A (ja) * 1986-05-01 1987-11-13 株式会社神戸製鋼所 軽量骨材の製造方法
US6104015A (en) * 1999-01-08 2000-08-15 Jayan; Ponnarassery Sukumaran Continuous microwave rotary furnace for processing sintered ceramics

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1103852A (en) * 1964-02-11 1968-02-21 Osaka Cement Company Ltd Methods and apparatus for manufacturing high-strength, light-weight aggregates for light-weight concretes
US5352275A (en) * 1989-07-31 1994-10-04 Cyclean, Inc. Method of producing hot mix asphalt
WO2001047829A1 (fr) * 1999-12-28 2001-07-05 Corning Incorporated Procede hybride destine a la chauffe de ceramiques

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62260741A (ja) * 1986-05-01 1987-11-13 株式会社神戸製鋼所 軽量骨材の製造方法
US6104015A (en) * 1999-01-08 2000-08-15 Jayan; Ponnarassery Sukumaran Continuous microwave rotary furnace for processing sintered ceramics

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 198751, Derwent World Patents Index; Class L02, AN 1987-358702, XP002206243 *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2625482A4 (fr) * 2010-10-07 2017-06-07 Milt D. Mathis Four rotatif à micro-ondes
US11425800B2 (en) 2010-10-07 2022-08-23 Milt Mathis Microwave rotary kiln
AT512271A3 (de) * 2011-11-17 2016-01-15 Horst Wustinger Verfahren für das Herstellen von porösen Körnern aus Wasserglas
WO2023242289A1 (fr) * 2022-06-17 2023-12-21 Colas Procédé de production industrielle d'argiles calcinées
FR3136766A1 (fr) * 2022-06-17 2023-12-22 Colas Procédé de production industrielle d’argiles calcinées

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