DE2512167A1 - Concrete mixing drum with bitumen spray - longitudinal channels in sections along inside, staggered, width varying - Google Patents

Abstract

The large cement mixing installation has a horizontal mixer drum (14) mounted on rollers, with a hot air feed at one end, adjacent the entry (11) for the granular material, discharging into a finned compartment that end, followed by a mixer chamber divided into sections by annular rings (15), with an injection pipe (23) down the middle with a spray head (24) near the feed end for injecting bitumen, and a discharge connection (6) at the other end. The quantity of heat used and the materials fed in are controlled for an optimum product, the bitumen serving as a binder being 20 to 40% by weight of the solids. Between the annular dividers are longitudinal channels (16) formed by curved plates, varying in width in a given pattern, the channels being staggered.

Description

PROCESS FOR PREPARING CONCRETE MIXTURES ON THE BASIS OF A ORGANIC BINDING AGENT AND MINE-RALIC BULK COMPONENTS AND EQUIPMENT FOR DRYING AND HEATING BULK INGREDIENTS WHEN CARRYING OUT THIS PROCEDURE The invention relates to methods for preparing concrete mixtures on the basis an organic binder and mineral bulk components as well as a for drying and heating bulk components when performing this process Specific facility used in the building materials industry for the preparation of asphalt concrete mixes is used, which is used as a binding agent petroleum bitumen, and tar concrete mixtures, the coal tar obtained as a binder, these types of concrete depending on the used mineral bulk stock rush as gravel asphalt concrete, sand asphalt concrete and Earth asphalt concrete can be distinguished.

It is largely a process for preparing asphalt concrete mixes known, which consists of the following.

The mineral material (sand, gravel) is dosed naturally moist, placed in a rotating drying drum, dried in this and up to 120 ... 160 ° C, but for cast concrete mixes heated up to 2400C, whereby in the drum the heat transfer medium and the bulk material flow towards each other. The dried and Heated sand and gravel then pass through a lifter into a screening plant, in which they are sorted by grain group and directed to different bunkers. Thereafter sand and gravel of various grain sizes, additives as mineral powder and surfactants as well as bitumen dosed and an asphalt concrete mixer in which all components of the mixture are carefully mixed.

To carry out the drying and heating sequences of sand and gravel when preparing the amphalt concrete mixture, a facility is known in which the most important component is a rotating drying drum that sits on top of it Inner surface has blades, which a dislocation of the bulk components over the drum and a distribution of the bulk components over the drum cross-section favor.

The drum is equipped with a loading and unloading device, a Furnace and gas extraction system equipped.

The firing system is in the front wall of the drying drum Unloading device side built in, which is why the heat transfer medium runs in the opposite direction in the drum and the bulk components of the mixture takes place.

When drying the mineral material in the drying drum as well also when conveying, sorting according to grain size, when dosing and mixing with other mixture components in the asphalt concrete mixer takes place an abundant Excretion of the fine / fraction present in the bulk material in the form of dust., Granular together with the exhaust gases from the combustion products and the air through the ventilation systems sucked off and fed to a dedusting device, in which part of the Dust is separated and collected, but the remaining part is blown to the outside.

The dust excreted from sand and crushed stone is from 0.5 to 10% of the weight of these components, the mass of dust being greater, the the speed of the exhaust gas and air flow is higher.

A multi-stage dedusting of gases provides: Elechanische Ab sealing of all equipment groups, dust deposits from the drying drum together with the exhaust gases as well from all other dust elimination points while creating a negative pressure within the equipment, blowing in the extracted Gases in the first and second cleaning stage, trapping and collecting the dust, Exploitation of the captured dust it for the preparation of asphalt concrete and the like Mixtures as well as the discharge at a certain height from the subgrade of the exhaust gases with non-intercepted Residual dust.

The exhaust gases and air, saturated with dust, flow first by cyclone separator batteries, in which dust from particles whose size is more than 5 am is deposited and collected in a bunker. After that they pour Gases through a second cleaning stage, in which a lot of the dust consists of particles, the size of which is less than 5 µm, the one remaining in the gases is also deposited But dust is ejected into the atmosphere.

The secondary gas cleaning takes place both in gas scrubbing devices: self-inductive Atomizers, foam devices, etc., as well as in dry cleaners: with cloth filters or Filters for electrostatic separation. The gases get through in the gas scrubber the wetting of the dust with water dedusted, then the latter in the sedimentation tank, in which to precipitate the dust in the form of mud is, is pumped.

The shortcomings of gas scrubbers are as follows: Large consumption # Amount of water, great need for pipes and pumps as well as settling tanks and difficulties while removing the sludge. The effectiveness of these gas scrubbers is reduced by that some types of dust cannot be wetted by means of Viasser and cannot be attached to the water are.

In the case of the smoke filters, the gases are dedusted as they flow through bags made from special types of cloth. The one knocked down on the walls of the bag Dust is regularly removed by mechanical shaking and ventilation in opposite Direction deposited and then collected in the bunker.

The lack of these filter systems is the high temperature sensitivity, whereby the filter bags burn at wick temperatures of the exhaust gases But lowering the exhaust gas temperature until dew is formed, the bags are filled with sludge dirty.

The complicated automatic systems used here for Reduction of the exhaust gas temperature before entering the filter by means of exhaust gas cooling However, injected cold air does not completely eliminate the existing deficiencies.

The dedusting of the exhaust gases in filters with electrostatic deposition is very rarely used in asphalt concrete plants, as this type of dedusting is very important is costly. An effective operation of such dust collectors can be at a optimal amount of gases flowing through these systems and with calculated flow velocity the gases are secured. In actual operation, however, the amount of exhaust gas changes very significant as a result of several circumstances, causing a change in the gas flow rate caused by the dust collection system.

This phenomenon can be explained by the fact that that of the drying drum added mineral LCmaterial usually has a natural moisture content of 1 to 9%, while the fuel consumption for moisture evaporation changes and for heating the sand and crushed stone from 6 to 10 kg per 1 ton of mixture, creating a Exhaust gas volume change is caused, which the set work flow of the dust extraction system disturbs.

From the explanations given above it can be seen that the defects the known method for the preparation of concrete mixtures on the basis of a organic binders and mineral bulk components, especially when The process of drying and heating the latter in a self-excretion of finely dispersed htorn groups of the mineral material in the form consist of dust as well as in the implementation of exhaust and air dedusting in robust, complicated and expensive nntstai £ o systems, the value of which is up to 30% the cost of the entire asphalt concrete plant.

Despite the great expense of purchasing and operating the Dust collectors are the health regulations for gas and air dedusting not adhered to.

Therefore, the known devices for drying and heating of loose components for the preparation of asphalt concrete mixtures and the whole Asphalt concrete atmosphere were exposed to sources of pollution of the @ by dust the mineral material.

The invention aims to eliminate the mentioned problems.

The invention is based on the object to experience such Preparation of a concrete mix on the basis of an organic binder and mineral bulk components using <-> when drying and heating of the mineral bulk components <such work processes and their characteristics> to develop the dust development, i.e. the separation of fine grain groups of the mineral material as well as such a facility to the Carrying out the drying and heating processes for mineral bulk components when preparing concrete mixes on the basis of an organic binder and to construct mineral bulk components, in which the type of Tremmel an improvement in the health conditions for the work of the operating personnel guaranteed and no use of complicated and expensive dedusting systems requires, whereby the cost of the finished mixture can be reduced.

The task was thereby. solved that in the preparation of concrete mixes based on an organic binder and mineral bulk components by dosing, drying, heating the latter by means of heat transfer media and sorting according to grain groups, weight dosage of all components, including the organic bindeittels, and subsequent mixing, according to the invention drying and Heating of the mineral components in parallel with the latter with the heat transfer medium takes place and is in the stream of the essential (dried bulk components, which continue to run with the heat transfer medium, an organic binder is injected whose X! close a certain part of the preparation of the concrete mixture represents required organic binder, and to carry out the Drying and heating of liners Components of the Preparation of concrete mixes based on an organic binder and A facility serving mineral constituents, which has a bathing device and drum which has blades on the inner surface that embody the Displacement over the drum of the bulk components and the distribution of the latter Benefit via the drum cross-section in the drying process, one in the front wall of the drum built-in combustion system, a gas extraction group and unloading device is according to the invention the furnace is located on the side of the loading device of the rotary drum, which is extended on the opposite side and has a chamber forms several partitions in the form of rings attached to the drum side, between them, channel-shaped compartments with a cross-section that varies along their length are arranged that one compartment with respect to the other by 1d00 in the plane of the drum side is pivoted, but in the chamber there is a barrel with atomizers on the drum rotation axis built in to inject the binding agent onto the dry bulk components.

For the treatment of bulk components during the drying and heating process of these, it is expedient to add 20 to 40% of the total binder weight required to use.

The essence of the invention consists in the following: By the fact that drying of the bulk material in synchronism takes place with the heat transfer medium, the moist material enters a high temperature with the one just fed to the drum (approx.

14000) having heat transfer medium in contact, the material becomes fast Warmed up to 100.120 ° C and dried, but the temperature of the heat carrier drops to 300 ... 800 ° C, depending on the type of binder.

This temperature is up to heating the mineral material to 160 ... 240 ° C, i.e. up to a temperature that is sufficient for the work processes when preparing asphalt-concrete and similar mixtures.

im essential in injecting the binder into the stream of the # In the dried bulk material, it is essentially covered Coarse particles, afterwards the partially treated one is put into the chamber when it is placed Material evenly distributed over the cross section of the drum, additionally through the binding agent splattered and all dusty material particles appear as they run out of the drum connected by the binder. This will generate dust from the dried and heated material intended for the preparation of concrete mixes prevented.

The even distribution of the partially treated by the binder Material across the drum cross-section is attached to the drum side by the trough-shaped compartments favored.

As a result of the variable cross-section of these subjects, this will be the case lying material is gradually thrown off when the drum rotates around 1800 and forms at the same time a veil, but by the fact that the channel-shaped compartments against each other are pivoted by 1800 in the plane of the drum side, there is an opposite direction Throwing off the material and the closeness of this veil is guaranteed.

The division of the chamber into individual cells by dividing walls designed as rings ensures multiple successive rejuvenation and expansion of the Material flow with the heat carrier (through the exhaust gases from the furnace) and an extension of the material flow path, which means that the binding agent acts more carefully on the Dust-like particles of the bulk material favored.

The process and the device according to the invention are now in progress on the basis of the description of specific examples and the accompanying drawings explained.

1 shows the relationship between the amount of bitumen required for treatment of sand and gravel during the drying of this material during preparation an asphalt concrete mixture and with the amount contained in the sand and gravel dusty particles. On the abscissa is the bitumen consumption in, on the ordinate the kenge of the dusty particles in the sand and gravel given in percent by weight.

Fig. 2 longitudinal section of the device for drying and heating the Mixture of sand and crushed stone in the preparation of asphalt concrete mixes; Fig. 3 section along the line III-III of FIG. 2 through the chamber of the drying drum; 4 shows a view in the direction of arrow A in FIG. 3 of the inner surface of the chamber; Fig. 5 section along the line V-V of Fig. 4; Fig. 6 section along the line VI-WI of Fig. 4; FIG. 7 a section along the line VII-VII in FIG. 4.

The device shown in the drawings for drying and Heating sand and crushed stone when preparing asphalt concrete mixes contains: Drying drum 1 (Fig. 2), which rotates around its longitudinal axis, u.zw. as a result of consolidation on the drum side of rims 2 and 3, which are supported against rollers 4 and 5, which are arranged on a base plate 6, and ring gear 7, which is in engagement is with a gear 8, which is also via a reduction gear 9 by a on the base plate 6 arranged electric motor 10 is driven.

A loading device is located in one of the drum end walls 11 and furnace 12 are installed, but there are blades on the inner surface of the drum 13 and 13 'provided, moving sand and gravel over the drum 1 and its distribution when rotating the drum over its cross section favor.

At the aer charging device 11 is opposite side the drum 1 is elongated and thus forms a chamber 14.

In the chamber 14 are designed as rings on the drum side Partition walls 15 attached, in the cells between these partition walls 15 are rinnenformige Compartments 16 (Fig. 3 to 7) arranged, which are made of sheet steel and one have variable cross-section in the longitudinal direction.

The compartments are against each other around 1800 in the side plane of the drum 1 pivoted.

The last ring 15, which serves as the outlet end wall of the drum 1 is equipped with spoons 17 and a channel 1d, which together form an unloading device form.

The spoons 17 are on the drum side and on the last ring 15, the However, the channel 18 is attached to a console 19.

The facility is also equipped with a gas exhaust system that a box 20 comprising the outlet end wall of the drum 1 and one with a Fan 22 connected pipeline 21 contains.

i> er pasten 20 has an opening for mounting the channel 18.

In aer chamber 14, the tube is on the drum axis of rotation 23 with atomizers designed as nozzles 24 for injecting the bitumen into the chamber 14 mounted.

The tube 23 is led into the chamber 14 through the box 20 # and is fastened to the bracket 19 mounted on the base plate 6. By a pump 25 and a metering device 26, the pipe 23 is connected to a bitumen container 27.

There are @ier concrete implementation examples of the invention Procedure listed.

Example 1.

A fine-grained asphalt concrete mix was prepared on an aer basis of petroleum hits with a degree of penetration of 60/90 units. The composition per 1 ton of mixture (in kg and percent by weight) was: kg 1 granite gravel, grain size 0 ... 10 mm ... 550 55 2 river sand 0 ... 5 mm ................... 295 29.5 3 bitumen ............................... 50 5 4 Additive activated lime powder with a content of at least 60% of particles smaller than 0.071 ................................. 105 10.5 The mineral bulk components were used to prepare the asphalt concrete mixture (Sand and gravel) dosed by weight dosers and the rotating drying drum fed into the high-temperature flue gases from the furnace streamed. The bulk components were aerated by moving over the drum as it rotated move the latter, dry in cocurrent with the flue gases and then with Bitumen sprayed, the amount of which in this example is 16.25 kg, i.e. 32.5.6U of the total bitumen weight (50 kg), which is required to prepare the mixture, was. This amount of bitumen was due to the 6.3% content of dusty particles in the sand and gravel accepted.

Experiments have shown that the bulk constituents are used for the treatment The amount of bitumen required in the drying drum is the amount of dusty particles in the mixture bulk components is directly proportional (the straight line I in the diagram of Fig. 1).

When running through the stream the mineral components became these heated up to 1600C by the flue gases.

The bitumen-treated sand and crushed stone were placed in an elevator and fed from here to a screening plant in which they are separated according to grain groups will. Then the sand and gravel, separated into grain groups, were weighed out dimensioned and fed into the asphalt concrete mixer. This was also where the pre-weighed The amount of bitumen that corresponds to the remainder (67.5 percent by weight, i.e. 33.25 kg).

From the asphalt concrete mixing machine, the finished mix became available to the consumer delivered.

Example 2.

A fine-grained asphalt concrete mix was prepared on the base of petroleum bitumen with a degree of penetration of 90/130 units.

The composition per 1 ton of mixture was: 1 granite crushed stone Grain size O .. 15 mm .... 360 36 2 River sand, grain size 0 ... 5 mm ............ 459 45.9 3 bitumen ............................... 51 5.1 4 additional material-activated Lime powder with a content of at least 60% of particles smaller than 0.071 mm ....... 130 13 The course of the mixture preparation took place in the main features in a similar way to example 1.

The one required to treat the bulk material in the drum The amount of bitumen was determined with the aid of the straight line I (Fig. 1) shown in the diagram. The content of dusty particles in the sand and gravel was assumed to be 3.8%.

The amount of bitumen injected into the drying drum was 14 kg, i.e. 27.5 percent by weight of the total amount of bitumen.

example 3.

An asphalt concrete mixture was prepared on the basis of Petroleum umen with a degree of penetration of 100/200 units.

The composition per 1 ton of mixture was 1. River sand, grain size 0 ... 5 mm ....... ,, 722 72.2 2. Bitumen ............................ .. 68 6.8 3. Activated lime powder ............... 210 21 The course of the mixture preparation took place in the main features in a manner similar to that in example 1.

The amount of bitumen fed to the drying drum was measured using the in the diagram shown straight line I (Fig. 1) determined. This was the salary assumed 1% of dusty particles in the sand. This amount was 14.96 kg, i.e. 22 percent by weight of the total amount required to prepare the mixture of bitumen.

In a similar way (with the course described above) concrete mixes based on other organic binders, e.g. coal tar and the like Material to be prepared.

The operation of the drying and heating equipment described above of sand and crushed stone for the preparation of asphalt concrete mix proceeds in the following Way.

The drum 1 (Fig. 2) is driven about its longitudinal axis. In addition the electric motor 10 is switched on; doing this is done by the on the output shaft of the reduction gear 9 seated gear 6, the ring gear 7 and thus also the drum 1 is driven.

In the furnace 12, fuel combustion (liquid or gaseous fuel) high-temperature flue gases flowing into the drum. If necessary, quantities are pre-weighed here by the loading device 11 fed by sand and gravel.

The bulk material is removed from the end wall by the blades 13 the drum 1 is removed (thrown off) and comes into the range of action of the blades 13 '. The latter lift and move the material particles when the drum rotates them along; in the process, the material particles are thrown off, causing the Drum forms a veil of material from individual streams.

The high temperature smoke gases flowing in parallel with the material the mixture components dry out.

in the dieÇessential (dried sand and crushed stone are upon entry into the cell of the chamber 14 formed by the first pair of rings 15 by bitumen sprayed, which by means of the pump 25 from the bitumen container 27 via the metering device 26 by the pipe 23 with the nozzles 24 is fed.

The sand and gravel are partially treated by bitumen through the channel-shaped compartments 16 (Fig. 3 ...

passed into the second cell of the chamber 14 formed by the rings 15, in which an additional spraying takes place.

Characterized that the Eaterialstrom in the chamber 14 a constriction and Propagation is exposed to the passage of the material from a chamber cell in which others are generated, eddies are created when the flue gases flow, which favor the sticking of the dusty particles to the bitumen. By the Presence of channel-shaped compartments 16 is the even distribution of the haterial particles on the drum cross-section and the formation of a dense veil when moving the material particles via the drum to the unloading device. At the exit end wall of the drum, the bitumen-treated and up to Bulk components heated to 1600C are discharged through the spoons 17 into the channel 18 and then transported further for the preparation of the asphalt oetone mixture.

The dedusted flue gases are out of the box 20 through the Ronrleitung 21 sucked off by means of a fan 22 and passed into the outside air.

From the description it can be seen that the method according to the invention for the preparation of concrete mixes on the basis of an organic Binder and the device for drying and heating mineral bulk components enables complete prevention of dust generation in all work processes, whereby the health conditions during operation are considerably improved and adhered to health regulations regarding environmental dust, the costs the mixture preparation is reduced and the lines of the system are increased.

Claims (3)

P A T E N T A N S P R U C H E: 1. Process for the preparation of concrete mixtures on the basis of a organic binding agent and mineral debris by dosing, drying, ffirhitzen aer last by means of a heat transfer medium as well as sorting according to grain groups, weight dosing all ingredients, including the organic binder, and the following Mixing, that is, drying and heating of the mineral components takes place in the same course of the latter with the heat transfer medium and in the stream of the essentially dried loose ingredients that have their Continue the run with the heat transfer medium, an organic binder injected is whose tongue a certain part of the preparation of the concrete mixture required organic binder. 2. The method according to claim 1, d a d u r c h g e k e n nz e i c h n e t that part of the binder injected into the stream of bulk ingredients 20 to 40% of the total weight of the latter. 3. Device for carrying out the drying and heating of mineral Ingredients for the preparation of concrete mixtures on the basis of an organic Binder and mineral components according to the method according to claim 1 including a loader and rotating drum which has blades on the inner surface, which allow the bulk components to be displaced over the drum as well as the distribution of the latter over the drum cross-section in the drying process favor a furnace built into the front wall of the drum, a gas extraction group and The unloading device has, that is, the firing (12) is on the side of the loading device (11) of the rotary drum, whose full length in the running direction of the bulk components that of the rommelim in part, in which the bulk components are # essentially dried, and in a drum section the aforesaid; extensive drying, in the next Section but the post-drying of the ingredients, injection of the binder and Heating take place, and this other section a chamber (14) with several partitions in the form of ring (15) attached to the drum side, between which Channel-shaped compartments (16) with a cross-section that is variable over their length are arranged in this way are that one subject in relation to the other around 1800 in the plane of the drum side pivoted, and in the chamber on the axis of rotation of the drum (1) with a tube (23) Atomizers (24) is built in.