NL2028820B1 - A process for the preparation of an asphalt composition. - Google Patents
A process for the preparation of an asphalt composition. Download PDFInfo
- Publication number
- NL2028820B1 NL2028820B1 NL2028820A NL2028820A NL2028820B1 NL 2028820 B1 NL2028820 B1 NL 2028820B1 NL 2028820 A NL2028820 A NL 2028820A NL 2028820 A NL2028820 A NL 2028820A NL 2028820 B1 NL2028820 B1 NL 2028820B1
- Authority
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- Netherlands
- Prior art keywords
- reclaimed asphalt
- aggregates
- heated
- fraction
- coarse fraction
- Prior art date
Links
- 239000010426 asphalt Substances 0.000 title claims abstract description 239
- 239000000203 mixture Substances 0.000 title claims abstract description 56
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 238000002156 mixing Methods 0.000 claims abstract description 27
- 229910052500 inorganic mineral Inorganic materials 0.000 claims abstract description 21
- 239000011707 mineral Substances 0.000 claims abstract description 21
- 238000010438 heat treatment Methods 0.000 claims description 46
- 239000002245 particle Substances 0.000 claims description 21
- 239000000654 additive Substances 0.000 claims description 20
- 230000003716 rejuvenation Effects 0.000 claims description 18
- 239000003795 chemical substances by application Substances 0.000 claims description 17
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000000945 filler Substances 0.000 claims description 11
- 239000000306 component Substances 0.000 claims description 10
- 239000011874 heated mixture Substances 0.000 claims description 9
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 6
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 6
- 239000002318 adhesion promoter Substances 0.000 claims description 6
- 150000001412 amines Chemical class 0.000 claims description 6
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 6
- 239000000920 calcium hydroxide Substances 0.000 claims description 6
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 6
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 6
- 239000001913 cellulose Substances 0.000 claims description 6
- 229920002678 cellulose Polymers 0.000 claims description 6
- 239000003365 glass fiber Substances 0.000 claims description 6
- 239000004571 lime Substances 0.000 claims description 6
- 239000011490 mineral wool Substances 0.000 claims description 6
- 229920000642 polymer Polymers 0.000 claims description 6
- 238000007873 sieving Methods 0.000 claims description 3
- 238000003801 milling Methods 0.000 claims description 2
- 238000011144 upstream manufacturing Methods 0.000 claims description 2
- 239000003086 colorant Substances 0.000 claims 3
- 238000003860 storage Methods 0.000 description 29
- 239000000463 material Substances 0.000 description 23
- 239000011230 binding agent Substances 0.000 description 16
- 239000008187 granular material Substances 0.000 description 8
- 239000011362 coarse particle Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- 230000018109 developmental process Effects 0.000 description 4
- 230000008929 regeneration Effects 0.000 description 4
- 238000011069 regeneration method Methods 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 239000000975 dye Substances 0.000 description 3
- 239000000839 emulsion Substances 0.000 description 3
- 239000010419 fine particle Substances 0.000 description 3
- 239000013521 mastic Substances 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000001033 granulometry Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000012492 regenerant Substances 0.000 description 2
- 238000012216 screening Methods 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- 239000004575 stone Substances 0.000 description 2
- 239000012615 aggregate Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
- 235000013311 vegetables Nutrition 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C19/00—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving
- E01C19/02—Machines, tools or auxiliary devices for preparing or distributing paving materials, for working the placed materials, or for forming, consolidating, or finishing the paving for preparing the materials
- E01C19/10—Apparatus or plants for premixing or precoating aggregate or fillers with non-hydraulic binders, e.g. with bitumen, with resins, i.e. producing mixtures or coating aggregates otherwise than by penetrating or surface dressing; Apparatus for premixing non-hydraulic mixtures prior to placing or for reconditioning salvaged non-hydraulic compositions
- E01C19/1004—Reconditioning or reprocessing bituminous mixtures, e.g. salvaged paving, fresh patching mixtures grown unserviceable; Recycling salvaged bituminous mixtures; Apparatus for the in-plant recycling thereof
Landscapes
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The present invention relates to a process for the preparation of an asphalt composition comprising a step of mixing virgin minerals aggregates, reclaimed asphalt aggregates and optionally one or more other components. The present invention also relates to apparatus for the preparation of an asphalt composition comprising virgin minerals aggregates, reclaimed asphalt aggregates and optionally other components. An object of the present invention is to provide a method for the preparation of an asphalt composition wherein the emissions of unwanted components to the environment is reduced to a minimum.
Description
Title: A process for the preparation of an asphalt composition.
The present invention relates to a process for the preparation of an asphalt composition comprising a step of mixing virgin minerals aggregates, reclaimed asphalt aggregates and optionally one or more other components. The present invention also relates to apparatus for the preparation of an asphalt composition comprising virgin minerals aggregates, reclaimed asphalt aggregates and optionally other components.
Asphalt is a universal raw material used for roadways, parking lots and other surface applications. The asphalt material is generally a composition of minerals including aggregate and sand or stone filler and a bituminous binder. Additionally, asphalt mixtures may include various substitutes for the aggregate (coarse and fine) including; crushed glass, used tires, and other reclaimed materials. The bituminous binder is basically the glue that binds the mineral ingredients such that they are solid under normal operating or environmental temperatures but semi-liquid under elevated temperatures.
A process for the production of asphalt comprising reclaimed asphalt aggregates is known from WO2014168479 in the name of the present inventors. Such a process for the preparation of an asphalt composition comprising reclaimed asphalt aggregates comprising recycle bitumen, comprises the steps of providing at least a coarse fraction of reclaimed asphalt aggregates and at least a fine fraction of reclaimed asphalt aggregates, heating at least a part of the coarse fraction to a temperature of more than 130 °C to obtain a hot coarse fraction, providing fresh bitumen and heating the fresh bitumen to a temperature of at least 130 °C to obtain hot fresh bitumen; and mixing at least a portion of the hot coarse fraction and, optionally, at least a portion of the fine fraction with hot fresh bitumen to obtain an asphalt composition. The virgin coarse aggregates and/or the virgin fine aggregates have been heated before being added to the bitumen.
Another publication in the name of the present inventors is W02015126252 and that WO document relates to a process for preparing an asphalt composition comprising a bituminous binder material and solid particles composed of mineral aggregates and elastic particles, in which process the bituminous binder material is heated to an elevated temperature; the heated bituminous binder material at elevated temperature is passed to an expansion chamber, water is passed to the expansion chamber to contact the heated bituminous binder material to form steam, thereby forming foamed bitumen, and the foamed bitumen is combined with the solid particles, wherein the elastic particles have a maximum particle size of at most 2.8 mm, and which solid particles are gap-graded, the gap being defined by a lower and an upper limit, wherein solid particles of a size between the lower and upper limit are substantially absent, wherein the upper limit of the gap is bigger than the maximum particle size of the elastic particles, and wherein the aggregates include particles with particle sizes above the upper limit of the gap, yielding an asphalt composition.
WO2014168477 in the name of the present inventors relates to a process for the preparation of a mastic composition, comprising a step of providing a solid material comprising reclaimed granular asphalt aggregates which have a maximum diameter of at most 2 mm, and recycle bitumen, providing a fresh bitumen and, optionally, a rejuvenating agent, mixing the solid material with the fresh bitumen to obtain a mixture containing reclaimed granular asphalt aggregates and a bituminous binder material consisting of recycle bitumen and fresh bitumen and optionally the rejuvenating agent, and recovering the mixture as the mastic composition, wherein the amount of bitumen ranges from 15 to 75 %wt, calculated as recycle bitumen, fresh bitumen and optionally the rejuvenating agent, and based on the weight of the mastic composition.
EP 1 767 581 in the name of the present inventors relates to a method for preparing an asphalt mix, comprising contacting and mixing, at a temperature in the range from 75 - 110°C, foamed bitumen and aggregate material with a moisture content of less than 0.5% by weight, based on the mass of the aggregate material, in which the asphalt mix, after mixing, is compacted to form an asphalt, and in which the aggregate material is divided into a fine fraction and a coarse fraction, both fractions having a moisture content of less than 0.5% by weight, and in which the foamed bitumen is first contacted with the coarse fraction, and then, in a second step, the fine fraction is added to the mixture obtained in this way.
WO 2010/012597 in the name of the present inventors relates to a process for preparing an asphalt mixture from recycled asphalt pavement (RAP) , virgin aggregate, filler and first and second binder materials, comprising steps of transporting RAP through a first drum and thereby heating the RAP to a temperature of from 70 to 130 °C, transporting virgin aggregate through a second drum, thereby heating the virgin aggregate to a temperature of from 90 to 130 °C, adding a first binder material to the RAP in the first drum, to provide treated RAP, optionally supplying the treated RAP from the first drum to a first storage vessel, optionally supplying the virgin aggregate from the second drum to a second storage vessel, and supplying the treated
RAP from the first drum or from the first storage vessel to a mixing zone, supplying the virgin aggregate from the second drum or from the second storage vessel to the mixing zone, supplying filler to the mixing zone, supplying a second binder material to the mixing zone, and mixing to provide the asphalt mixture; wherein the first binder material is a mineral oil, an oil of vegetable or animal origin, or a soft bitumen component, wherein a hard bitumen component is added as a bitumen emulsion or as a foamed bitumen.
EP 3 173 526 relates to a continuous procedure for the production of tempered bituminous mixtures from reclaimed asphalt pavement and from a bituminous emulsion, comprising the following steps: provision of reclaimed asphalt pavement having a granulometry comprised between 0 and D3 mm, processing the reclaimed asphalt pavement to obtain at least two fractions, the maximum sizes whereof do not exceed 7 mm and 30 mm, subjection of predetermined quantities of the fractions to a process of mixing and heating by hot gas flow such that the heating times and the intensity of exposure of each fraction are adapted to the granulometry thereof, being shorter for a fraction of smaller size than for another of greater size, the temperature of the mixture at the end of the step being comprised between 90 °C and 120 °C, blending the mixture obtained in the foregoing step with a predetermined quantity of bituminous emulsion supplied at a temperature comprised between 60 °C and 80 °C, the final mixture subsequent to the previous step attaining a temperature of between 90 and 110 °C.
EP 3 467 045 relates to a preparation method of a plant-mixed warm recycled asphalt mixture, comprising the following steps of preparing reclaimed asphalt pavement materials, new aggregates, mineral powder, new asphalt and a regenerant with a total mass percentage of 100%, heating and stirring the reclaimed asphalt pavement materials, adding the regenerant, and then continuing to heat and stir the mixture, placing a product thus produced in a development bin for development, wherein a development temperature is 40°C to 150°C, and a development time is 0.5 h to 6 h, mixing, heating and stirring the product with the new aggregate; and mixing and heating the product thus produced with the new asphalt, adding the mineral powder, and stirring until the mixture is molded.
US 2018/186963 relates to a method to reclaim or recycle asphalt or asphalt components to produce reusable asphalt or asphalt components comprising providing crushed asphalt or asphalt components; and adding the asphalt or asphalt components to a solvent in which the bituminous binder is soluble, wherein the solvent is selected from the group consisting of heptane, hexane, naphtha, kerosene, gasoline or a petroleum based solvent. Such a method further comprises an additional step of screening or separating coarse aggregate and fine aggregate asphalt components from the solution and cleaning or removing bituminous binder and/or the solvent from the coarse aggregate and fine aggregate asphalt components thus screened or separate by centrifugal spinning or by adding a second solution effective to remove the bituminous binder and/or the first solution.
CN210946381U relates to an asphalt mixture regeneration device with cold addition function, comprising a coarse particle reclaimed asphalt pavement (RAP) cold silo, a coarse particle conveyor line, a coarse particle RAP regeneration drum, a hot material temporary storage silo, a fine particle RAP cold silo, a fine particle conveying line, a fine particle temporary storage bin, a RAP weighing scale and a mixer, wherein the coarse particle RAP cold storage bin is connected to the feed inlet of the coarse particle RAP regeneration drum through the coarse particle conveying line, and the discharge port of the regeneration drum is connected with the hot material temporary storage bin.
US 2012/263007 relates to an asphalt plant adapted to use RAP to produce asphalt, the asphalt plant comprising a bin, the bin being adapted to store the RAP, a heat source, the heat source being adapted to supply heat, a dryer, the dryer being adapted to dry the RAP, a mixer, the mixer being adapted the mix the RAP, a means for conveying the RAP from the bin to the dryer, wherein the asphalt plant uses substantially only the RAP to produce asphalt.
On basis of the above discussed documents it is clear that asphalt as such can be reused for the preparation of “new” asphalt. In a plant situation wherein reclaimed asphalt pavement materials are heated, the binding agent and the other building materials, such as mineral particles, will return to somewhat of their original condition, i.e. the binding agent will melt and the stones will become separate from each other.
In practice, reclaimed asphalt pavement materials will be heated in large quantities and at a high production rate. In order to meet these requirements a tumble dryer with an internal flame is often used. In such a tumble dryer the co-current principle is quite useful: the cold and wet reclaimed asphalt granulates briefly see the flame, but with further heating the reclaimed asphalt granulates will be carried away from the flame.
An aspect of such a process is that the larger granulates will initially remain cool on its outside and the effect thereof is no complete burning of the bitumen. The 5 disadvantage is that the finer granulates do not remain cold on the inside but directly absorb the temperature of the flame.
In a situation wherein asphalt granulate is produced by a milling and crushing process not only big chunks will be produced but small bitumen particles and bitumen dust are also released. These relatively small particles will also enter the flame in the tumble dryer and these particles will very quickly take on the temperature of the flame and the effect may be the combustion of the bitumen. This combustion of the bitumen and the direction of the necessary airflow through the tumble dryer means that the resulting gases are taken along and eventually escape through the chimney as unwanted emissions. In addition, it is also possible that the bitumen does not burn completely, but that it is overheated, resulting in a strong deterioration of its properties.
An object of the present invention is to provide a method for the preparation of an asphalt composition wherein the emissions of unwanted components to the environment is reduced to a minimum.
An object of the present invention is to provide a method for the preparation of an asphalt composition wherein combustion and degradation of the bitumen component of the reclaimed asphalt pavement materials is reduced to a minimum.
The present invention relates to a process for the preparation of an asphalt composition comprising a step of mixing virgin minerals aggregates, reclaimed asphalt aggregates and optionally one or more other components, wherein the reclaimed asphalt aggregates comprise recycle bitumen, the method comprising: a) providing a coarse fraction of reclaimed asphalt aggregates; b) providing a fine fraction of reclaimed asphalt aggregates; c) heating the coarse fraction of reclaimed asphalt aggregates of step a) in a heating drum wherein the coarse fraction of reclaimed asphalt aggregates is heated to a temperature in a range of 100 and 140 °C, to obtain a heated coarse fraction, d) withdrawing of at least a portion of the heated coarse fraction of step c) from the heating drum, and e) contacting the heated coarse fraction of reclaimed asphalt aggregates of step d) with the fine fraction of reclaimed asphalt aggregates of step b) in a storage bin, wherein the heated coarse fraction of reclaimed asphalt aggregates provides at least a part of the energy needed to dry and heat the fine fraction of reclaimed asphalt aggregates to obtain a heated mixture of reclaimed asphalt comprising the coarse fraction of reclaimed asphalt aggregates and the fine fraction of reclaimed asphalt aggregates.
On basis of the above process one or more objects are achieved. The present inventors found that a better way to heat up the fine asphalt particles, i.e. a fine fraction of reclaimed asphalt aggregates, without the formation of harmful emissions is to apply a method of indirect heating. The cold and wet fine fraction of reclaimed asphalt aggregates is brought into contact with the hot, coarse fraction of reclaimed asphalt aggregates material and the small bitumen particles are heated via indirect heating. According this way of processing of the fine fraction of reclaimed asphalt aggregates no burning and degradation of the bitumen takes place and the emissions are reduced to a minimum.
In an example of the present process for the preparation of an asphalt composition a rejuvenating agent may be added in step e) in a storage bin. In another example of the present process for the preparation of an asphalt composition a rejuvenating agent may be added in step ¢) in a heating drum.
In an example step e) further comprises adding one or more additives chosen from the group of adhesion promoters, such as amine components, lime and calcium hydroxide, anti-drainage additives, such as cellulose, glass fibres and rock wool, and dyes, such as iron oxide, and polymers.
The coarse fraction of reclaimed asphalt aggregates of step a) and the fine fraction of reclaimed asphalt aggregates of step b) are preferably obtained from raw reclaimed asphalt from road structures, wherein the raw reclaimed asphalt is objected to a step of crushing and/or sieving for separating the raw reclaimed asphalt aggregates thus objected into at least a coarse fraction of reclaimed asphalt aggregates and at least a fine fraction of reclaimed asphalt aggregates.
In an example the coarse fraction of reclaimed asphalt aggregates comprises granular particles with a diameter of more than about 2 mm and the fine fraction of reclaimed asphalt aggregates comprises granular particles with a diameter of at most about 6 mm. In practice it will be very difficult to have a sharp cut off between the two, i.e. coarse and fine, fractions of reclaimed asphalt aggregates.
In an example the temperature of the fine fraction of reclaimed asphalt aggregates before being contacted with at least a portion of the heated coarse fraction ofreclaimed asphalt aggregates is general around ambient temperature and preferably kept below 40 °C.
The weight ratio of heated coarse fraction of reclaimed asphalt aggregates to the fine fraction of reclaimed asphalt aggregates in step e) is preferably in a range of 3:1 to 20:1.
For obtaining the final asphalt composition the present process further comprises a step of mixing the heated mixture of reclaimed asphalt with virgin mineral aggregates and optionally one or more other components, such as fresh bitumen, fillers and additives, wherein the step of mixing is preferably carried after a residence or storage time of the mixture of reclaimed asphalt and optionally the rejuvenating agent in the storage bin of at least 3 minutes, preferably at least 7 minutes.
The present invention also relates to an apparatus for the preparation of an asphalt composition comprising virgin minerals aggregates, reclaimed asphalt aggregates and optionally one or more other components, such as fresh bitumen, fillers and additives, the apparatus comprising: i) a heating drum for heating a coarse fraction of reclaimed asphalt aggregates to a temperature in a range of 100 and 140 °C to obtain a heated coarse fraction, ii) a storage bin, located downstream from the heating drum, provided with an inlet for at least a portion of the heated coarse fraction from the heating drum, an inlet for a fine fraction of reclaimed asphalt aggregates, and an outlet for a heated mixture of reclaimed asphalt, wherein the heated coarse fraction of reclaimed asphalt aggregates provides at least a part of the energy needed to dry and heat the fine fraction of reclaimed asphalt aggregates to obtain the heated mixture of reclaimed asphalt comprising the coarse fraction of reclaimed asphalt aggregates and the fine fraction of reclaimed asphalt aggregates.
In an example the storage bin and/or the heating drum is provided with an inlet for a rejuvenating agent. In some embodiments it is preferred to prevent a close contact between the rejuvenating agent and the hot air from the flame in the heating drum because high temperatures may cause loss of rejuvenating agent, combustion and vaporization of the rejuvenating agent resulting in harmful emissions to the environment.
In an example the storage bin is further provided with an inlet for one or more additives chosen from the group of adhesion promoters, such as amine components, lime and calcium hydroxide, anti-drainage additives, such as cellulose, glass fibres and rock wool, and dyes, such as iron oxide, and polymers.
In an example the outlet of the storage bin is connected to a mixing device for obtaining the asphalt composition, the mixing device is further provided with one or more inlets for virgin minerals aggregates and optionally one or more other components, such as fresh bitumen, fillers or additives.
In an example a mixer is positioned downstream from the heating drum and upstream from storage bin, the mixer being provided with an inlet for at least a portion of the heated coarse fraction from the heating drum, an inlet for a fine fraction of reclaimed asphalt aggregates, and an outlet for the mixture thus obtained to the storage bin. The mixer may also be provided with one or more inlets for other components, such as adhesion promoters, such as amine components, lime and calcium hydroxide, anti-drainage additives, such as cellulose, glass fibres and rock wool, and dyes, such as iron oxide, and polymers. In such a mixer the fine fraction and optionally other components as mentioned before are intensively mixed into the heated coarse fraction resulting in an optimal contact between the heated asphalt granulate from the heating drum and the cold and wet fine fraction and optionally other components. This action improves the temperature exchange between the two fractions and the product obtained from this mixer is more homogeneous and the moisture can evaporate and escape better and faster. The mixer mentioned here is “sandwiched” between the heating drum and the storage bin.
According to the present invention the fine fraction of reclaimed asphalt aggregates is extracted from the reclaimed asphalt by means of sieving prior to entering the asphalt plant. This can take place in the pre-processing process of asphalt granulate which usually takes place via breaking and screening. The removal of this fine fraction may also be necessary because these fines are not desired in specific asphalt mixtures. It is also possible that such fine fractions of reclaimed asphalt aggregates are formed in other processes that are used for the pre-treatment of the asphalt granulate.
The present inventors found that is beneficial to introduce these fine asphalt/bitumen fractions cold and wet into the asphalt plant halfway through the production process, i.e. after the heating drum of the coarse fraction of reclaimed asphalt aggregates. Thus, there will be no direct contact between the flame of the heating drum and the fine fractions of reclaimed asphalt aggregates, and the fine fraction will thus not be carried away by the airflow running through the heating drum.
The fine fraction of reclaimed asphalt aggregates is introduced into the heated coarse fraction of reclaimed asphalt aggregates flowing out of the heating drum and is thus heated indirectly by this heated coarse fraction of reclaimed asphalt aggregates and away from the hot internal airflow coming from the outlet of the heating drum. After a period of temperature equalization in the storage bin, the composite mixture is then mixed into a final asphalt mixture, together with any new minerals that may have been heated in another drum and optionally other materials, such as fillers and new bitumen.
For the purpose of promating an understanding of the principles of the present invention, reference will now be made to the embodiments illustrated in the figures. It will, nevertheless, be understood that no limitation of the scope of the disclosure is thereby intended; any alterations and further modifications of the described or illustrated embodiments, and any further applications of the principles of the disclosure as illustrated therein are contemplated as would normally occur to one skilled in the art to which the invention relates. It is noted here that the disclosure is by no means to be interpreted as limited to any merely preferred features, unless essential for proper functioning as defined in the claims, where the scope of protection may even include obvious alternatives for specifically recited features in the appended independent claims.
Figure 1 shows a schematic view of an asphalt plant according to the present invention.
Figure 2 shows a schematic view of an asphalt plant according to the present invention.
A part 10f an asphalt plant is shown in Figure 1. A coarse fraction of reclaimed asphalt aggregates 8 is heated in a heating drum 2 to a temperature in a range of 100 and 140 °C to obtain a heated coarse fraction 11. A rejuvenating agent 15 may be added at or just before the outlet of heating drum 2. In storage bin 5 a fine fraction of reclaimed asphalt aggregates 9 is brought into contact with heated coarse fraction of reclaimed asphalt aggregates 11. The heated coarse fraction of reclaimed asphalt aggregates 11 provides at least a part of the energy needed to dry and heat the fine fraction of reclaimed asphalt aggregates 9 to obtain a heated mixture.
Rejuvenating agent 4 and one or more additives 3 may be added to the storage bin 5, as well. Outlet stream 7 of storage bin 5 comprises a mixture of fine fraction of reclaimed asphalt aggregates, coarse fraction of reclaimed asphalt aggregates, and optionally rejuvenating agent or other components. Outlet stream 7 of storage bin 5 is sent to a mixing device 6 provided with one or more inlets 14 for (heated) virgin minerals aggregates and optionally one or more other components, such as fillers, fresh bitumen and additives. Outlet stream 10 comprising an asphalt composition is stored in a storage vessel 12 for further transport as stream 13.
A part 20 of an asphalt plant is shown in Figure 2. A coarse fraction of reclaimed asphalt aggregates 8 is heated in a heating drum 2 to a temperature in a range of 100 and 140 °C to obtain a heated coarse fraction 11. A rejuvenating agent 15 may be added at or just before the outlet of heating drum 2. The outlet 11 of heating drum 2 is sent to a mixer 16. In mixer 16 a fine fraction of reclaimed asphalt aggregates 9 is brought into contact with heated coarse fraction of reclaimed asphalt aggregates 11.
The heated coarse fraction of reclaimed asphalt aggregates 11 provides at least a part of the energy needed to dry and heat the fine fraction of reclaimed asphalt aggregates 9 to obtain a heated mixture. Other components may be added via one or more inlets 3, 4 for additional components to mixer 16 as well, such as additives. The outlet stream 17 is sent to a storage bin 5. The outlet stream 7 of storage bin 5 comprises a mixture of fine fraction of reclaimed asphalt aggregates, coarse fraction of reclaimed asphalt aggregates, and optionally rejuvenating or other components. Outlet stream 7 of storage bin 5 is sent to a mixing device 6 provided with one or more inlets 14 for (heated) virgin minerals aggregates and optionally one or more other components, such as fillers, fresh bitumen and additives. Outlet stream 10 comprising an asphalt composition is stored in a storage vessel 12 for further transport as stream 13.
It is to be noted that coarse fraction of reclaimed asphalt aggregates 8 and fine fraction of reclaimed asphalt aggregates 9 may originate from different reclaimed asphalt streams.
Claims (16)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2028820A NL2028820B1 (en) | 2021-07-23 | 2021-07-23 | A process for the preparation of an asphalt composition. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2028820A NL2028820B1 (en) | 2021-07-23 | 2021-07-23 | A process for the preparation of an asphalt composition. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| NL2028820B1 true NL2028820B1 (en) | 2023-01-30 |
Family
ID=85111727
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NL2028820A NL2028820B1 (en) | 2021-07-23 | 2021-07-23 | A process for the preparation of an asphalt composition. |
Country Status (1)
| Country | Link |
|---|---|
| NL (1) | NL2028820B1 (en) |
-
2021
- 2021-07-23 NL NL2028820A patent/NL2028820B1/en active
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