DE2809224A1 - METHOD AND DEVICE FOR PRODUCING FIRED MATERIALS - Google Patents

Description

March 3, 1978 5537

SHERWEN ENGINEERIIiG- COMPANY LIMITED, Mile End Green, Dartford, Kent, England

Method and device for manufacturing fired materials

The invention relates to methods and apparatus for burning mineral products and is involved in the use of such methods and devices when burning concerned with minerals which have particles of a grain size not significantly larger than 0.06 mm. In particular, however it is not exclusively concerned with the burning of clay or clay materials, i.e. materials in which clay or Clay minerals of such nature and proportions are present that the material becomes an extrudable or extrudable mass, if necessary with the addition of water, can be shaped, the material being fired can to form an expanded or puffed product with numerous small voids, a process known as

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"Swelling" is known, and it is particularly associated with the burning of loam or clay materials in pelletized form form, e.g. for the production of a synthetic aggregate for use as a building material,

The production of such synthetic aggregates is known, with a cylindrical, brick-lined rotary kiln used for heating and burning the raw material, which will first be ground and mixed with oil before it is extruded and chopped into pellets or pieces of appropriate size. The pellets are the The input end of the rotary kiln is supplied, which is of considerable length and has a combustion zone at its other end with a burner or burners. The furnace cylinder is slightly inclined so that the pellets are due to gravity advance lengthways as they are circulated by the rotation of the furnace. The combustion gases out the burners in the firing zone are aligned lengthways to the furnace to access the material from the entrance to the To act in the furnace, so that the material is dried and continuously heated up to the firing temperature.

It has been found that this process can be difficult to control, mainly because the conditions in the furnace cannot be easily regulated to meet the various requirements for processing the material when it is from its initially cold state to being another contains a considerable amount of water, reaches the final state in which it is exposed ^{to an intense heating temperature of about 120O 0 C.}

In the early stages, if the heating is too rapid, the pellets will break open before the moisture is driven off. In the final state, the circulation must be able to prevent the pellets from becoming large molten slag or Clinker masses grow, since the rise in temperature

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rial makes plastic, while on the other hand the circulation effect must not be so strong that the pellets are damaged while they are still mechanically weak Are between the drying and firing stages. All the different requirements have to be regulated by regulating the Burner and the speed of travel of the material through the furnace are controlled, which dictates the conditions on the The length of the furnace can vary, although it may be desirable to have the material in only one stage to influence. It can therefore take a few days after the start until a stable operating state is reached which achieves a satisfactory compromise between the various parameters controlling the processing of the material is. The high thermal mass of the furnace also contributes to the difficulty of controlling the working conditions to adjust.

Since the firing stage is considered to be the most critical, furnace operation is usually the primary objective in practice regulated to avoid the formation of slag or clinker which must be discarded and because of the size the masses that form once the growth process has started can be difficult to remove. Therefore must other, less serious disadvantages have to be accepted, some of which are of poor quality than the quality of the product Standard.

Another disadvantage of the known method for synthetic aggregate lies in the mass of the plant and its high capital costs which, since the supplement is essentially a cheap product, can be lost if the local Material supplies fail or local demand for the product declines.

According to the invention a method for firing clay or clay-like materials is provided in which a

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particulate starting material of classified particle size (e.g. by sieving to remove only particles in the desired particle size range or by pelletizing or briquetting to produce larger particles from one finely dividing material) selected, moisture from the material with heating to a temperature below the firing temperature removed, the dried material is heated to firing temperature and then the fired material is cooled is * where at least the drying and firing stages are carried out in separate rotary heating chambers will.

With such a method it is possible to have a flexible Maintain control of the treatment of the material. In particular, the heat sources and the type of movement of the Material in the different chambers can be chosen quite independently to meet the requirements of the material in the to correspond to the respective stage of the procedure.

In order to obtain the heat generated in the combustion and cooling stage, the combustion gases from these two stages can be used Drying the pellets and / or preheating them, if necessary with the supply of additional heat from another Source to be exploited. An advantage of this mode of operation is that a relatively large flow of hot gas is available for the first heating stage, for example if it should be necessary to remove large amounts of moisture from the material without significant Amounts of free oxygen are present which could cause undesirable chemical reactions that could affect the subsequent Irenn process.

The method is preferably carried out in a device whose rotation chambers are each made of metal and whose combustion chamber is a sandwich lightweight construction with heat-insulating material between an inner, heat-

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has solid metal lining and an outer load-bearing structure. However, it can also be provided that respective control devices for heat regulation are created in each heat supply stage.

The use of such a lightweight construction in the kiln avoids the need for a brick lining in the rotation chamber so that each unit can be relatively light. This enables a completely different kind of thing Solution of the design of the gate direction for the production of building materials, such as slamming, which makes it possible is to provide a door direction that can be transported from one place to another. So this is how the previous one is Avoid the need for a capital-intensive facility that works in a fixed location, and when building the gate direction Significant economical door parts and savings are possible, whereby the construction is most advantageous at all times Space can be made to meet market needs.

In the case of a preferred 3-shape of the door direction, a A series of separately transportable units may be arranged, each including units for pelletizing or classifying (sieving), drying, calcining and cooling. These units can even be used as standard container units be designed so that they can be handled and transported by commercially available facilities can, at least some of the units, e.g. those for drying, baking and cooling can be arranged so that they can be placed on top of one another, the material being transferred by gravity into each adjoining unit will.

The control of the individual units can not only extend up to the heat supply speed, but also is possible up to the individual, separate setting of the

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Material throughput rate. Will be gravity feed applied, it can simply be arranged so that in each unit facilities for adjusting the inclination the rotating chamber to change the dwell time of the "located in it." Materials are provided. In any case, the rotating chamber can be shaped and divided so that one can Material throughput is given the type of movement that is most relevant to the physical state at this stage of the process is most suitable.

The turning or rotation chambers preferably have non-circular passages and can have a multi-arced cross-section as described in a (simultaneously filed) patent application P ..., in particular in! the case of the combustion chamber or the furnace.

Examples according to the invention are described with reference to Figures described from which further features of the invention emerge. The examples shown relate to refers to the production of a puffed light product, but it goes without saying that a denser, non-puffed product can also be made Product can also be manufactured. Show it

Pig. 1 is a chemical flow diagram of one according to the invention Method of making lightweight synthetic aggregate,

Figures 2 and 3 are a side view and a plan view of a Outline of a device using the method according to the invention according to Fig. 1,

Figures 4 and 5 are a side view and a cross-sectional view, respectively, of the cryogenic dryer in the apparatus according to Fig. 2 and 3,

Fig. 6 is a cross-sectional view of the high temperature dryer, Fig. 7 is a schematic end view of the vertical shaft

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oven,

Figures 8 and 9 are a side view and a cross-sectional view, respectively of the rotary kiln,

10 is a cross-sectional view of the rotating cooler;

Fig. 11 is a schematic flow diagram of another according to the invention Procedure for the production of aggregate,

FIG. 12 shows a schematic outline of an apparatus using the method according to the invention from FIG. 11;

Figs. 13 to 16 are side views of the respective units in the device of Fig. 12,

Figure 17 is an end view of the unit of Figures 13 and 13

18 to 20 are sectional views in the planes X-X, X-Y and Z-Z in FIGS. 14 to 16.

With reference to FIGS. 1 to 3, the device initially shows an input conveyor 2, the raw clay or carries clay to a cutting feed unit 4, which may be conventional, designed and used to break up the material and a low-temperature rotary dryer 6, in which the clay is subjected to a first drying process reducing the moisture content to no more than practically 18%, e.g., 12-14%. A lifting conveyor 8 then takes the partially dry material to a pelletizing unit 10, which is not shown in detail is conventional machinery including a crusher or grinder 10a where oil or other fuel can be added to the loam or clay, and can comprise one or more pelleting devices 10b.

The pellets of practically uniform size come off the conveyor 12 led to a high temperature rotary dryer 14 to remove all remaining free water and at least some of the water chemically bound in the material. the

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Pellets then fall through at a controlled speed a fixed shaft furnace 16 to heat the material close to the firing temperature. The fixed one Furnace leads to a rotary furnace 18 where the sintering or firing of the material takes place, in this example the The material is of such a type that the above-mentioned swelling effect occurs. At the discharge end of the kiln the product is entrained by a flow of cooling air through a transport line 20 to a rotary cooler 22 when the End product is discharged from the cooler onto a discharge conveyor 24.

The cryogenic dryer 6, the shaft furnace 16 and the Rotary kilns 18 each have their own heat source in the form of one or more burners 26, 28, 30. The high-temperature dryer 14 is heated using the exhaust gases from the shaft furnace, the rotary kiln and the cooler, with the gases are passed directly from these units to the dryer 14. For this purpose lines 32, 34 from the rotary kiln and provided by the cooler.

Disregarding radiation and other external heat losses, the internal heat requirements for the various stages of the processed material are divided into 15% for the low-temperature dryer, 55 % for the high-temperature dryer, 17 % for the shaft furnace and 11% for the rotary kiln. The cooler can supply up to about 40 % of the total internal heat demand as circulating heat retained in the process. This goes to the high-temperature dryer, supported by the heat in the exhaust gases from the shaft furnace and the rotary kiln, the proportion of which is 2: 1. The burner feed of the cryogenic dryer, the shaft furnace and the rotary kiln are at an approximate ratio of 15:29:16.

The different process stages and the device

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are described in detail below.

At the entry end, loam or clay with a moisture content of about 22 percent by weight is broken up in the cutting conveyor 4 so that a feed material with particles of less than 2.5 cm in size for the cryogenic dryer 6, shown in FIGS. 4 and 5, is produced. The dryer comprises a container 42 with an outer heat insulating layer (not shown) and has an internal cross-section of the shape of a clover with deep arches 44, as best seen in Fig. 5, described in more detail in the (simultaneous) patent application P ... .. ... The container has end rings 45 arranged on rollers 46 for rotation about the axis of symmetry of the cross section and is driven by a motor 48. A compressed air fan 50 at the material discharge end and an induced draft fan 51 at the material input end work together with the burner 26 at the material ^{discharge end to form an air stream heated to approximately 300 °} C. through elongated outlet slots 52 of a line 54 which extends along the center of the container. Control devices 55 enable the burner output and / or the fan suction speed to be set to control this first drying stage independently of later process stages.

The moisture-laden air exits at about 90 ^° C. through a chimney 56. The clay or clay is fed to the dryer through a feed hopper 58 which protrudes into the interior of the container and runs the length of the container under propulsion by the rotation of the container to expose it to the countercurrent of warm gases which heat and increase the clay or clay dry to a final moisture content of about 18 %.

Due to the shape of the container with an arcuate cross-section, the material is rotated in the bottom

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constant arch raised to the point where the angle of repose is exceeded, and a thick top layer then slips and falls into the subsequent lower arch, which is quickly followed by the rest of the material that was before the lower layers formed, which now fall on the first material portion, whereby this process is continuous repeated as each arc rises from a low point. The material is actually circulated continuously, when it falls in free flow on a localized area of the container cross-section, and the slits in the line direct the flow of hot gas to this area, so that the entire material three times with each circulation The concentration of the container is similar to that of being exposed to a fresh stream of hot gas in a fluidized bed.

In order to obtain the circulation effect described, the dryer must not rotate so fast that the material is on it is prevented from falling like a waterfall from each ascending arch into the next arch, but within the frame this restriction leads to an increase in the speed of rotation to an increase in the drying rate and the speed at which the loam or clay particles deteriorated or destroyed, thereby lowering the energy consumption when the dried material is broken before pelletizing.

The speed of material migration through the dryer 6 is determined by changing the downward slope of the longitudinal axis of the Dryer controlled by the end of the clay input, including support facilities 59 are vertically adjustable at one end of the drum 42. The dryer 6 is available as having its own heat source shown equipped, but can be designed so that he the heated exhaust gases from the high-temperature dryer exploited to supply part of the required heat and gas flow supply, or the dryer 6

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can with modifications of the heating arrangements for the High-temperature dryer 14 utilize heat in the exhaust gases of a later stage, such as the furnace 18.

Because the crushing and pelletizing processes after the first drying stage are performed with conventional equipment, they are not further described here. At the end of the discharge The pelletizing unit is used to screen the processed material from which dust and small particles have been removed are conveyed up to the high temperature dryer 14 by a box conveyor 12. A box conveyor is preferred since, although the pellets have been compacted to mechanical stability at this stage, they are rapidly supplied with heat not withstand unscathed when subjected to mechanical impacts at the same time. For the same Basically, the dryer 14 should move the pellets relatively gently. As can be seen from the cross section in Mg. 6 is, the drum 62 of the high temperature dryer has cylindrical inner and outer walls 64, 66 between which a series of radial partitions 68 extend around a large number of small cross-sectional passages 70 to form the throughput of the pellets. The drum is provided with end rings 72 and rollers 74 and is powered by a motor 76 powered. It also has means 78 for adjusting its inclination to the horizontal.

Material entering the drum through the flared entrance is distributed through passages 70, when the drum rotates and the material flows along the drum, but at a slower speed for a given inclination of the axis of rotation compared to the cryogenic dryer, because of the smaller cross-section of the passages. These smaller passages also keep the impact forces caused by the circulation low. The pellets form a series of thin streams that flow through

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The force of gravity are continuously circulated _P when the drum rotates, whereby they are heated by the hot gases flowing through the drum, which with the help of the fan 59 flow in countercurrent to the material through the drum _o As already described, the heating is carried out by the hot exhaust gases directly from the vertical shaft furnace, the rotary furnace and the cooler to the material discharge end of the high-temperature _{dryer, as well as some additional air 9} which was heated by convection current through an outer jacket of the shaft furnace. The gases completely dry the pellets from their initial moisture content of 18% and raise their temperature to around 50O ⁰ C.

When they are discharged from the high-temperature dryer, the pellets enter the vertical shaft furnace 16, the one Has chamber with rectangular cross-section through which a series of narrow baffles 82 (Pig. 7) made of rods with Angular cross-section protrude, with their vertices pointing upwards. Jet burners 84 (Pig. 2) are attached to the provided on opposite sides of the chamber, their nozzles in the chamber immediately below the respective Impact members protrude so that in each Pall the burner flame is parallel to an associated impact member in is aligned with the space immediately below the impactor. In the impact members (not shown) openings be provided to make the hot combustion gases easier to escape up through the chamber.

The pellets can fill the chamber, but any baffle member keeps the space immediately below free. During operation, for example, there are a number of cavities that extend through extending the chamber with the tops of each cavity defined by the lower surfaces of an impact member and the undersides are determined by the angle of repose of the material filling the chamber. The burner flames

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protrude into these voids and the burners preferably produce a flame length that is substantial length of each void, so that uniform heating of the material in the longitudinal direction of the associated Impact member is promoted. The air flow associated with a burner is preferably applied to such a burner ■ limited as necessary for stoichiometric combustion is to keep the gas velocity low and so the required energy and the need for dust removal and also to avoid or limit the presence of free oxygen.

To control the heating process, thermocouples 86 above the level of the respective groups of burners that they are to be controlled, and an automatic controller 88 can be used to regulate burner operation be provided depending on the signals of the thermocouples. The heating speed can also be from the shape of the chamber can be influenced, as in a flow of material through them under the force of gravity and with a given material discharge speed per unit area The larger the chamber, the longer the material heating time.

In the individual spaces within the chamber, where the material is directly exposed to the combustion process, exists a radiant heating effect and also a clear path for the flow of hot gases upwards so that relatively rapid Heating can be achieved. It is possible to have the temperature conditions in a narrow range and quite independently to be regulated by the other procedural stages. The temperature profile in the furnace can also be controlled as the burner are arranged at different heights, and each height can, if necessary, by respective control means 88 individually being controlled·

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The shaft furnace has a relatively compact design ₀ which favors its manufacture in a transportable form _- although it may be necessary to remove the cladding from the structure for this purpose. For example, the burners can be attached to side walls 90 which are separate from the main heater body and can be suspended from an overlying roller track 92, a feature that also promotes maintenance and handling.

At the exit of the shaft furnace, the material must move at a sufficiently uniform speed from its relatively large Width to be fed to the narrower, conically tapered entry opening of the rotary kiln. To do this the material falls from the bottom of the shaft furnace into a collecting container 94 of the same width as the shaft furnace. In this box it sits up against a curfew 96 with the natural resting angle. Behind this lock lies a tapered chute 98 leading to the entry port 99 of the rotary kiln leads, and immediately in front of the barrier is a rotary conveyor with a number of spaced apart arranged disks 100, which are mounted on a shaft 102 which extends across the width of the exit opening. If the conveyor is set in rotation, the Movement of the trapped pellets, their angles of repose, and therefore pellets begin to slide over the barrier. The material is evenly removed from all points across the width of the container 94, so that there is no risk of formation uneven removal pattern occurs, which would occur if the discharge opening of the shaft furnace was simple would be a funnel that led directly to the rotary kiln. A drive motor 104 for the conveyor controls the speed of material movement.

The rotary kiln is detailed in the (simultaneous) Patent application P described. In his-

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In its main area it has a similar clover leaf shape as The low temperature dryer, but without internal impact cross members, It is made of a metal sandwich lightweight construction with an intervening heat insulating layer or layers of ceramic fiber. The arched one Cross-section circulates the pellets vigorously and ensures that they are heated more evenly, and prevents that is that the individual pellets adhere to each other when they reach expansion temperatures and go through a stage, in which they become sticky and relatively soft.

The furnace burner 30 can be a spear gas burner or a heat lance (FIG. 8), the flame of which extends over extending a considerable part of the length of the furnace, or an elongated radiant surface burner (Fig. 9), which is described in the mentioned (simultaneous) patent application. Control devices 106 for the burner are regulated by a thermocouple 108 in the furnace. Of the Burner is preferably operated under practically stoichiometric conditions in order to avoid undesired chemical reactions in the pellets, which leads to a lower gas velocity and thus to reduced requirements Dust removal leads. Because of the arcuate cross-section of the furnace, the radiant energy is better focuses the material so that it is exposed to a high radiant heat flux density, and together allow this with the type of rolling effect created by the arcuate cross-section, the use of a relatively short kiln. To change the inclination of the furnace and thus to adjust the dwell time of the material facilities 109 are provided.

Although the burners in the system have so far been described as gas burners, any suitable fuel can of course be used can be used to generate the process heat.

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At the end of the rotary furnace, the fired pellets come out with a temperature of about 115o C ⁰ through a chute 110 which leads to an upwardly inclined air line 112 from a pressure air blower 114th The room temperature air flow from the fan acts as a jet pump as it flows through a constriction 115 in the conduit at its junction with the chute so that the pellets are immediately entrained in the air flow. The pellets are vigorously moved in the air stream and suddenly cooled, so that any still plastic material immediately hardens. This combination of cooling and agitation prevents a large number of pellets from melting together and forming unmanageable masses of slag or clinker.

However, there is still a considerable amount of heat in the pellets and they are therefore passed through the rotary cooler led in countercurrent to a larger flow of cooling air from a motor fan 126. As can be seen from FIG. 9 the container also has an arcuate cross-section 118 and is similar in many respects to the cryogenic dryer with transverse baffles 120, which ensure a minimum bed of material in the chamber, and one centrally-axially located air line 112 with longitudinal slots 124 through which the cooling flow from the fan 126 is directed. Arrangement and drive of the container are similar to the cryogenic dryer, and it also has means 128 for independently adjusting the inclination of its axis.

The circulation of the pellets, similar to the other curved rotating containers, continuously exposes the individual pellets to the cooling gas flow and ensures maximum heat dissipation before the pellets are finally discharged onto a discharge conveyor with an outlet temperature of around 200 ^° C.

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The installation described above is of a semi-permanent nature in that, albeit a number of units, are mounted on mobile Underframes is mounted, fixed support structures for some of the apparatus, and on-site assembly and construction work is therefore required Construction of the plant required. The system shown in FIGS. 11 to 20, however, is a transportable system intended to manufacture a similar product but requires a minimum of on-site construction Job.

The system comprises four individual units, each contained in a standard ISO container frame. The first unit 210 is a manufacturing unit with the equipment to produce pellets from the raw material supply. The remaining three units 212, 214 and 216 are arranged one above the other for gravity feeding of the process material through them, and a conveyor 218 lifts the pellets from the first unit into the second unit, which has a preheater which in this case functions as a high temperature heating system. The preheater and the vertical furnace of the first embodiment are combined. The pellets leave this unit dried and ^{heated to 900 °} C., near their firing temperature, in order to enter the third unit, in which there is a rotary kiln, generally similar to the rotary kiln of the embodiment described first, while a rotary cooler is provided in the fourth unit is.

In the first unit 210, a twin shaft feed mixer 222 receives coarsely crushed feedstock through a feed hopper 224 and feeds it to a pan mill 226. The material fed to the mill should not be Moisture content higher than about 18% and an additional drying unit may be required (not shown) to be incorporated in the unit 210, e.g.

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taking advantage of waste heat from another part of the process when the raw material has an unacceptable moisture content having. If the material is too dry when it reaches the mill, water can be used at this stage Fuel oil can be added. The mill can be a batch process unit with an imperforate bottom be, then successive batches of material each fully ground before they are removed from the mill. On the other hand, it can be a continuously operating one Be a mill that feeds the product through a perforated floor to the discharge conveyor 228, which leads to an or several pelletizing units 230 of the type in which the finely divided material is pressurized to compress it into a mechanically stable pelletized form. Fuel can also be supplied at this stage, in particular solid fuel such as pulverized coal from hopper 232, but the fuel can alternatively be added to the mill. A sieve device 234 returns all of the fines of the pelletized product to the mill 226 with a conveyor 236. The sifted Pellets are fed to a hopper 238 in the second Unit supplied via conveyor belt 218. All of the devices in unit 210 can be hydraulically operated from one central energy system (not shown) can be driven, and each of them can be equipped with speed controls be provided.

In the second unit 212, some of the heat for the rotary drying and heating chamber 240 is taken from the hot exhaust gases supplied from the firing and cooling equipment in the units 214, 216. Is sufficient in the first unit Fuel has been mixed with the pelletized material, it can provide enough additional heat for the stage before firing with a suitably controlled air supply, on the other hand, however, the material discharge cap 242 the rotary chamber may be provided with fuel burners 243.

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The rotary chamber of the drying and preheating stage is a double wall construction with an insulating jacket and is similar to the high temperature dryer of the embodiment described first, by providing a tubular space 244 for flow between inner and outer cylinder walls 246, 248 is provided and radial partitions 250 subdivide this space axially so that a relatively gentle agitation occurs, which is particularly desirable when the pellets are completely dry have been. This internal chamber structure is made of a heat insulating layer within an outer housing 252 and not mechanically fixed to the outer housing, but simply prevented from rotating to participate or to move axially relative to it. The inner structure of the chamber can therefore be completely can be removed from the outer housing if this is necessary for inspection and repair.

This second unit has an articulated connection 254 to the third unit 214 below and is supported near its other end by a motorized lifting device 256. Their inclination can therefore be adjusted in order to change the material throughput rate. The normal operating angle would be about 1 to 2 degrees from horizontal.

The third structural unit 214 contains the kiln 260, which has the double-shell insulated and arch-like lightweight construction has, as they are in detail in the already mentioned

(simultaneous) patent application P .. · described

is. Material from the discharge cap 242 falls into the intake chute 262 for entry into the furnace, and the hot furnace exhaust gases flow in the same way up into the Chamber 240. A built-in burning platform 264 in unit 214 also serves as a control room for the facility. The single-stage control devices are not shown in full, as they are those of the system described first

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same. Like the second unit, the third unit has a hinge connection 266 at one end to the unit 216 below and a motorized lift near the other end for adjusting the working angle of the rotary kiln.

The fired pellets leave the furnace at a temperature of about 115O ⁰ C and fall into an entry chute of the fourth unit 216, which contains a rotary drying chamber 272, the interior of which is cylindrical in shape, with cross-shaped, axially extending partitions 274 having a series of separate passages 276 which lead from the chute 270. A compressed air blower 280 supplies cooling air from the discharge end, where a discharge chute is located for discharging the finished product, and the heated gases from chamber 272 flow directly through conduit 278 to drying and heating chamber 240.

In this facility, the rotating chambers are also shown as being mounted on rollers, but the chambers are each rotated by its own chain drive 286, what the friction wheel motor drive of the first described Investment is equivalent.

The fourth unit 216 rests on self-lifting, adjustable ones Legs 280 to vary both the inclination of the axis of the drying chamber to control throughput and also the height of the discharge chute 282 from the drum to adapt to the conveying device (not shown) for the discharge material. Like the rotary chamber of the second unit the inner structure of the dryer can be completely removed from the insulating outer casing if this is required.

The invention thus offers the advantage of a plant for the production of synthetic aggregate, expanded or unexpanded, in a number of relatively compact structural units that are sufficiently light in weight and small in size for transport

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between different locations and sufficient flexibility of working conditions to cope with a variety of To be able to produce turning materials, namely materials such as loam or clays (including Mudstones or mud clays and shale), soil, dredged river mud, waste of various kinds Type, such as mine tailings and porcelain clay waste as well as material mixtures, such as sand and loam or clay, or Sand and shale mixtures, incinerator marriage and Clay mixtures or calcium bauxite and clay mixtures. It should be understood, however, that different starting materials May make modifications to the treatment necessary, e.g. with regard to the type of grinder before pelletizing, and pre-treatment devices can be installed in front of the first dryer to be required. In special cases, a device for adding additives to the Starting material may be required. In all cases, the starting material should be graded to allow for large variations particle size, whether by sieving a mixture of large and small particles or by pelletizing of a finely divided material.

The portability of the installation described and illustrated above is facilitated by a number of features. First of all, it should be noted that the method is designed so that the amount of dust formed is reduced and so the need for extensive dust separation equipment, as is conventional Used in conjunction with burning products such as synthetic aggregates is avoided. In particular it should be noted that violent mechanical vibration of the material is avoided until it solidifies Has undergone heat treatment. The use of separate burners in different stages of the process that can all be controlled automatically, eliminating the need

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to supply a large excess of combustion air, so that the reduced gas flow to lower gas velocities resulting in less dust being entrained, with the added benefit of less fan power and to avoid the risk of material contamination through the formation of undesired metal oxides.

The portability is also due to the relatively high Heating power of the arc-shaped heating chambers with the continuous circulation of their contents facilitates what means that these chambers can be much shorter than a fully cylindrical chamber, especially what the Kiln concerns. In the case of the stove, the light insulation also greatly promotes transportability in comparison with a conventional brick-lined furnace.

The division of the process into a number of separate controlled Stages, together with the rapid cooling and heating, made possible by the lightweight construction of the chamber, means also that many repairs are made easier because it is possible to turn off only the affected stage and to hold the material in the remaining stages for a relatively short time, thereby preventing the whole System must be switched off.

D098.3S / 0840

Claims (18)

Claims 1. Process for firing e.g. loam or clay containing materials with steps for selecting a particulate starting material classified particle size, removing moisture from the material with heating to a Temperature below its firing temperature, heating the dried material to firing temperature and then of cooling the fired particles, characterized in that at least the drying and firing stages in each separate heater rotary chambers (14,18) are carried out. 2. The method according to claim 1, characterized in that the burned particles in a further rotary chamber (22) be cooled. 3. The method according to claim 1 or 2, wherein the burned particles are cooled in a gas stream, characterized in that that the gas thus heated directly to the chamber (14) for the drying stage for heating the therein located material is fed. 4. The method according to any one of claims 1 to 3, characterized in that that it is made with a finely divided starting material, by pelletizing and on a moisture content is not treated significantly above 18% prior to pelletizing. 5. The method according to any one of the preceding claims, characterized in that the material by gravity is passed through the drying, firing and cooling stages. 6. The method according to any one of the preceding claims, characterized in that a heated gas stream from the Combustion chamber (18) to chamber (14) to the drying stage for Heating of the material therein is performed. 7. The method according to any one of the preceding claims, characterized in that the material between the The drying and firing stages (14, 18) are passed through a further chamber (16) with its own heat source (28) will. 8. The method according to claim 6 and 7, characterized in that the heated exhaust gases from the combustion stage (18) directly the drying stage (14) bypassing the further heating chamber (28) are supplied. 9. Device for performing the method according to one of the preceding claims, characterized in that that the rotary chambers (14, 18, 22) are each made of metal and the combustion chamber (18) is a sandwich lightweight construction with heat-insulating material between a heat-resistant metal inner liner and a Has outer load-bearing structure. 10. Apparatus according to claim 9, characterized in that control devices (55, 59, 78, 88, 109) are provided for regulating the heat in each heat supply stage are. 11. The device according to claim 9 or 10, characterized in that it has a number of separately transportable units including respective units for the pelletizing stage (210), the drying stage (212), the firing stage (214) and the cooling stage (216). 12. The apparatus according to claim 11, characterized in that the units as standard container units are trained. 13. Apparatus according to claim 11 or 12, characterized in that that the units (212, 214, 216) for drying, firing and cooling for gravity transport 0 3 8 3 6/0 Ö A 0 2809724 of the material to the next unit on top of each other are arranged. 14. Device according to one of claims 11 "to 13, characterized in that devices (256, 26C ₉ 280) are provided in each unit for adjusting the inclination of its rotary chamber to change the dwell time of the material located therein. 15. Apparatus according to claim 9 or 10, characterized in that that they are connected to a further heating chamber in the form of a shaft furnace (16), between the drying and Combustion chamber (14, 18) is arranged, is provided. 16. The apparatus according to claim 15, characterized in that a discharge space (94) at the bottom of the shaft furnace for Receipt of material falling through the furnace is provided having a restraint lock (96) and a conveyor (100) in the space for decreasing the angle of repose of the material is provided to control the flow rate across this barrier. _R that the combustion chamber (16) 17. Device according to one of claims 9 "to 16, characterized in that a non-circular internal cross-section with a number gleichräumiger arcs. 18. Device according to one of claims 9 to 17, characterized in that the drying and / or the cooling chamber one into a plurality of smaller passages (70 or 276) through axially extending baffles (68 or 274) has or have subdivided internal cross-section. £ 09836/0840