System and process for processing milled asphalt
A mobile beneficiation system for milled asphalt addresses environmental and logistical challenges by using a rotary sieve and controlled heating to enhance recycling efficiency and product quality, enabling up to 50% RAP usage.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ALLKAZ EQUIP EIRELI
- Filing Date
- 2025-12-12
- Publication Date
- 2026-06-25
Smart Images
Figure BR2025050578_25062026_PF_FP_ABST
Abstract
Description
[0001] SYSTEM AND PROCESS FOR BENEFITING MILLED ASPHALT
[0002]
[0001] This invention patent refers to a system and process for beneficiating milled asphalt, more specifically, recycled asphalt - RAP (Reclaimed Asphalt Pavement), which allows for the beneficiation and bagging of recycled asphalt under specific conditions, in order to meet current standards for asphalt manufacturing. Advantageously, the system can be mobile or fixed, meaning it can be easily transferred to the desired location for asphalt use, and can also be installed on large vehicles, such as a semi-trailer or a truck.
[0003] History of the Invention
[0004]
[0002] The asphalt plant, also known as Hot Mix Asphalt (HMA), is the basis for the production of raw material for paving traffic routes, being, in its great majority, responsible for the stages of dosing, drying and mixing of the raw material for asphalt production.
[0005]
[0003] These asphalt plants can be classified as continuous or intermittent, the main difference between them being the volume of raw material and the transport between each stage.
[0006]
[0004] Intermittent plants are generally fixed plants, which require anchoring points to the ground, which, disadvantageously, prevents the movement of the plant components to a location closer to the work site, bringing the need for means of transporting the asphalt to the place of use.
[0007]
[0005] Continuous plants, due to their smaller equipment compared to intermittent plants, can be found in mobile configurations, which provides greater flexibility in asphalt production, since the mobile plant allows for reduced delivery time of raw materials to the construction site, in addition to meeting different standards for paving raw material configuration, meeting different granulometry and permeability parameters.
[0008]
[0006] However, one of the main disadvantages of existing plants is the exclusive use of virgin materials as raw material (aggregates, crushed stone, sand, among others), which contributes to the aggravation of environmental problems, since asphalt is the residue obtained from the fractional distillation of petroleum, in which mixtures are separated and various harmful gases are released. The residue generated is called bituminous binder.
[0009]
[0007] In view of the environmental impacts of asphalt, experts in the field continue to investigate alternative materials to make the production and application process more sustainable or to allow the reuse of leftover or discarded bituminous material.
[0010]
[0008] For applications where the material used to produce asphalt is recycled, it is necessary to use a rejuvenating compound capable of restoring the binding properties of the asphalt, reducing the permeability of the asphalt surface to external agents, and increasing durability. In this condition, it is necessary to use a batch mixer, usually a 1000-liter vertical mixer, which allows dosing the appropriate amount of rejuvenator and performing the proper mixing based on the particle size of the crushed material.
[0011]
[0009] One disadvantage of using concrete mixers is related to the difficulty of automating the process, since they do not have an integrated dosing system, requiring the operator to control the mixture properly, which makes the process more susceptible to errors, reducing the quality and properties of the final product. Another disadvantage of using 1000-liter vertical concrete mixers is related to the large size of the equipment, which can exceed 3 meters in length. Therefore, in applications that require plant mobility and on-site raw material production, it is necessary to use equipment that fits in the cargo compartment of a truck or trailer, which by default has a maximum width of 2.6 meters.This characteristic also makes automating the process difficult, since in order to fit in the vehicle's cargo compartment, the automated feeding of the concrete mixer is compromised, as it would exceed the maximum dimensions of the compartment.
[0012]
[0010] Furthermore, another disadvantage is the moisture present in the material, which interferes with the asphalt production process, as well as the final quality of the product, since it impairs the adhesion of the asphalt binder (bitumen) to the aggregates, forming a barrier that hinders proper bonding between them. Also, during the heating process of the materials, the water present evaporates rapidly, generating vapors and bubbles that can create voids in the pavement, making the asphalt more porous and less resistant, contributing to the formation of potholes.
[0013]
[0011] An example of the state of the art is the asphalt plant disclosed by document BR112021014348-3, entitled “ASPHALT PLANT APPLIED IN A CONTAINER”, published on 04 / 10 / 2019, which describes a mobile asphalt processing plant that can be housed inside a container. Disadvantageously, the plant has a virgin aggregate system, a drying system, and a mixer, components that require a large space to accommodate them. Furthermore, the plant requires special operator care, since among the components there is a heating system in the lower region, thermal oil piping, and fuel piping. This also causes environmental damage, as it involves the burning of fossil fuels.
[0012] The American document US9322138, on the other hand, discloses industrial equipment for the hot recycling of asphalt mixtures.However, these approaches often employ heating systems (such as open-flame burners) that, by transferring heat indirectly, operate at temperatures that can deteriorate the asphalt binder (bitumen). Such methods and equipment heat the milled asphalt material (RAP) to high temperatures (between 160°C and 20°F). g C and 180 g C) result in bitumen oxidation and thermal degradation. Furthermore, the processing generally involves the complete crushing of the material, which causes excessive fragmentation of the aggregates and, consequently, requires the application of a greater quantity of virgin asphalt cement to cover exposed surfaces, thus limiting the percentage of asphalt cement that can be used in the final mixture.
[0014]
[0013] Another deficiency observed in many known solutions relates to pre-treatment and particle size classification. Document US9322138, for example, does not contemplate the existence of a screening system and fails to mention magnetic separation, which compromises the removal of metallic contaminants that can damage subsequent machinery, such as crushers. Although there are processes, such as US20170211243, that include pre-treatment with screening, these are limited to obtaining a maximum of two particle size fractions (fine and coarse). The absence of a mechanism that uses multiple types of sieve openings to obtain a three-dimensional classification is not taught or motivated by the state of the art and limits the versatility and sustainable use of the material in various applications, such as micro-coatings.
[0015]
[0014] Another less widespread, but already used technique, given its environmental appeal, is the reuse of milled material (also known as RAP, from the English Reclaimed Asphalt Pavement), which consists of reusing it in the same condition as it is immediately after the milling process. This material can be incorporated into the soil and used in the execution of base and sub-base layers; however, it is necessary to know its particle size distribution in order to adapt it to the parameters used for these specific layers. Using this residue saves on the volumes of soil and aggregates needed to execute a granular layer, bringing environmental and socioeconomic benefits.
[0016]
[0015] Currently, processes that use RAP in asphalt production employ only crushers and sieves to prepare the material before its incorporation into the hot asphalt mix. In this method, all the RAP is crushed without distinction, which results in greater exposure of the surfaces of particles smaller than % of an inch, that is, the material fractures, becoming exposed and needing to be covered by CAP.
[0017]
[0016] Thus, these exposed surfaces require the application of petroleum asphalt cement (PAC) to ensure adequate adhesion. This technical limitation is the main reason why only 20% RAP is integrated into asphalt production, aiming to preserve product quality. Furthermore, virgin material is processed at the plant at a temperature between 160 °C and 180 °C, aiming to remove moisture and incorporate the PAC, which must also be heated to a temperature between 160 °C and 180 °C. When RAP, at ambient temperature, is added to the system, a reduction in the mixture temperature occurs, potentially compromising process performance. Therefore, to avoid this temperature drop and maintain system efficiency, the addition of RAP is also limited to 20%.
[0018]
[0017] Thus, the present invention aims to provide a functional and productive system for the beneficiation of milled asphalt (RAP), which comprises a raw material unloading silo; a magnetic separator for removing ferrous materials; a hollow rotary screen with three types of openings of different particle sizes - 3 / 16 inch, 3 / 8 inch and 3 / 4 inch - in accordance with international standards; a crusher for particles larger than 3 / 4 inch; a set of conveyor belts for moving the processed material; a set of dosing hoppers; a heated mixer for thermal processing of the RAP; and, optionally, a bagging machine for packaging the material when it is not used directly hot at the processing site.
[0019]
[0018] Another objective of the present invention is to provide a system capable of classifying materials with a particle size smaller than 4.75 mm (3 / 16 inch), allowing their reuse and application as raw material in various applications, such as micro-surfacing. This classification is essential to ensure the technical suitability of the material, especially in paving processes, where the use of fine aggregates provides a uniform finish, greater adhesion, and lower consumption of asphalt binder. Furthermore, by promoting the precise separation and classification of materials, the system expands the possibilities for sustainable reuse, optimizing resources that would be discarded in conventional processes.
[0020]
[0019] Another objective of the present invention is to provide a system that allows for the complete utilization of all slag generated in the hot asphalt machining process, including the crushed stone used in the cleaning stage, which is also called slag. In conventional processes, both the slag generated before reaching the ideal conditions for asphalt and the crushed stone used in cleaning are discarded, resulting in significant waste. The proposed system, on the other hand, reuses these materials, eliminating substantial losses that occur in conventional plants, where tons of material are discarded. In this way, the process becomes more efficient and sustainable.
[0021]
[0020] Another objective of the present invention is to provide a diffuser system interconnected to the set of dosing hoppers, configured to manage excess material in the hoppers, preventing spillage and allowing the excess material to be diverted and recirculated through the set of conveyor belts, optimizing the processing flow and maximizing the use of raw material.
[0022]
[0021] Another objective of the present invention is to provide a mobile and compact asphalt processing system that can be installed and transported in the cargo compartment of a large vehicle.
[0023]
[0022] Another objective of the present invention is to provide an efficient and versatile asphalt beneficiation process that allows its operation in different locations, reducing logistical costs and material transportation time. This feature is particularly advantageous in infrastructure works located in remote regions or in urban areas with difficult access, where mobility facilitates immediate response to paving or maintenance demands.
[0024]
[0023] A schematic figure of a particular embodiment of the invention will be presented below, whose dimensions and proportions are not necessarily the actual ones, since the figure is only intended to didactically present its various aspects, whose scope of protection is determined only by the scope of the appended claims.
[0025] Brief description of the drawings
[0026]
[0024] Figure 1 illustrates a perspective view of the asphalt beneficiation system (S) mounted on large vehicles.
[0027]
[0025] Figure 2 illustrates a perspective view of the asphalt beneficiation system (S), highlighting the diffuser system (4) and auxiliary conveyor belts (40).
[0028] Description of the Invention
[0029]
[0026] This invention patent relates to a system (S) and a process for beneficiating milled asphalt, which allows for the beneficiation and bagging of recycled asphalt (RAP). The said system (S) can be mobile and therefore has the flexibility to be transferred to the region of interest, and can also be installed on large vehicles, such as a semi-trailer or truck.
[0030]
[0027] According to the attached figures, the milled asphalt beneficiation system (S) comprises at least one raw material receiving silo (1), preferably raw material from recyclable material (RAP), which comprises in its upper portion a grate (10) with an opening of 200 to 300 mm, more specifically 250 mm, making a first separation of the material, at least one rotary screen (2) configured by a hollow cylindrical body (24), a set of dosing hoppers (5) and at least one heated mixer (6).
[0031]
[0028] The rotary sieve (2) with a hollow cylindrical body (24), which simultaneously promotes classification according to particle size and fragmentation of lumps and clumps due to the friction generated during the rotary movement. This occurs because the material is raised to a height greater than one meter inside the rotary sieve (2), resulting in natural friction that facilitates fragmentation.
[0032]
[0029] It is important to highlight that, during the rotary screening process, the material does not fracture, preserving the CAP (Petroleum Asphalt Cement) present in the aggregates. This characteristic represents a significant advantage compared to vibrating screens, which do not have this fragmenting effect and require a crusher, where the material fractures, becoming exposed and needing to be covered by CAP.
[0033]
[0030] Thus, the rotary sieve (2), which has no axis or radius, thus increasing process efficiency by 20%, is equipped with at least one opening size with defined particle size distribution, designed in accordance with international standards, which guarantees precise classification of the material. The use of this particle size classification offers several advantages, such as ensuring that each classified fraction is directed to the most appropriate application, which reduces waste and improves the quality of the final product.
[0034]
[0031] In one embodiment of the invention, it is understood that the rotary sieve (2) may comprise at least three opening sizes with defined particle sizes, these being 3 / 16 inch, 3 / 8 inch and 3 / 4 inch, respectively.
[0035]
[0032] The rotary screen (2) is located downstream of the silo (1), being connected to said silo (1) by a conveyor belt (12), which includes a magnetic separator (120), responsible for removing metallic particles and other unwanted materials, which is fundamental to protecting the crushers and other plant components, preventing mechanical damage and ensuring the longevity of the equipment. This initial stage is crucial for the efficiency and safety of the production process.
[0036]
[0033] In this way, the material with the desired and classified particle size, after passing through the rotary sieve (2), is deposited in the dosing hoppers (5) and, after proper dosing, is sent to the interior of the mixer (6), while particles larger than % inch are sent to the crusher (3).
[0037]
[0034] Normally, less than 10% of the total processed material needs to pass through the crusher (3), since most of it has already been fragmented in the rotary screen (2). This approach optimizes the efficiency of the crusher (3), reduces energy consumption and ensures that the final material meets the technical standards required for asphalt production. Thus, the material after being crushed in the crusher (3) can return to the system (S), being disposed of in the raw material supply silo (1).
[0038]
[0035] It is further understood that the system (S) comprises a diffuser system (4), or "relief" system, functionally associated with the set of dosing hoppers (5). The diffuser system (4) is preferably configured with one or more mechanical or electronic level sensors, configured to continuously monitor the filling rate of the dosing hoppers (5). When it detects an abrupt increase in feed or a limiting capacity condition that could result in overflow, the diffuser system (4) acts automatically by diverting the excess to one or more auxiliary conveyor belts (40), integrated into the set of conveyor belts (CE).
[0039]
[0036] Advantageously, the diversion occurs before the material causes obstructions or reductions in efficiency in the main flow, ensuring operational continuity. The recirculated material is directed to an earlier stage of the process, either returning to the silo (1) or being reintroduced into the rotary screen feed (2). In this way, all the material is reused, avoiding waste, unnecessary overloads in the hopper and interruptions in the processing cycle.
[0040]
[0037] Thus, the system (S), by incorporating the diffuser system (4), operates in a coordinated manner with the rotary screen (2) and the dosing hoppers (5). Therefore, when the rotary screen (2) exhibits high efficiency in fragmentation and particle size classification, generating an accelerated flow of material to the dosing hoppers (5), the diffuser system (4) automatically equalizes this dynamic, preventing the inlet speed from exceeding the dosing capacity. The excess is immediately channeled for rework via the auxiliary conveyors (40), ensuring operational stability, reduced downtime, longer lifespan of mechanical components, and maintenance of process uniformity.
[0041]
[0038] Additionally, it should be noted that the different particle sizes obtained from the rotary sieve (2) can be directed to different purposes according to their physical characteristics. Advantageously, the finer fractions can be directly destined for the production of asphalt micro-surfacing or other applications that demand materials with a high specific surface area, while medium or coarse fractions can be sent to subsequent mixing, recomposition or reworking stages. This ability to segregate and reuse each particle size according to its specific application constitutes a technical differential of the system (S), allowing greater use of the processed material, expansion of the portfolio of possible products and reduction of waste.
[0042]
[0039] The mixer (6) comprises heating, thus it is configured by a double-walled structure through which thermal oil circulates, used to heat the material inside the mixer to a controlled temperature from ambient temperature up to 340°C. This indirect heating system, in addition to maintaining the necessary temperature, prevents the oxidation of the materials contained in its composition, preserving the essential physicochemical properties of the CAP. This occurs because CAP, when exposed directly to flame or excessive temperatures, suffers thermal and chemical degradation, resulting in the loss of its structural and performance characteristics. To avoid this damage, the heating must be precisely controlled, maintaining the temperature up to 100°C, while the CAP remains in constant motion.This continuous movement prevents the formation of hot spots and sedimentation, ensuring a uniform distribution of heat and the stability of the material throughout the process.
[0043]
[0040] It is understood, but not limited to, that thermal oil is heated by different energy sources, such as LPG gas, diesel oil, or even by means of a gasifier (as described in document BR102022018025-3), which uses the combustion of pellets as fuel. This flexibility in the heating system allows adaptation to different available energy resources, making the process more efficient and sustainable.
[0044]
[0041] The mixer's thermal control ensures that the milled asphalt (RAP) maintains an average temperature of 100 °C, approaching the temperature of asphalt mixes produced with virgin material. This minimizes heat loss during the process, allowing the incorporation of up to 50% RAP into the mix. This advancement, compared to conventional techniques, offers numerous benefits, such as reduced consumption of aggregates (sand, gravel, and crushed stone) and asphalt binder, and the sustainable use of recycled materials, without compromising the quality and performance of the pavement.
[0045]
[0042] Furthermore, in another embodiment of the invention, the RAP is heated to remove all moisture present, which improves its workability and quality in the process. This method allows the application of rejuvenators through the sprayer, which restore the binding properties of the aged material, expanding its possibilities for use. Thus, the treated RAP can be used in various applications, such as pothole repair, shoulder surfacing, highway sub-base, and paving of streets and alleys with low volume of heavy traffic. This approach provides greater flexibility in the use of recycled material, contributing to sustainability and efficiency in the construction and maintenance of pavements.
[0046]
[0043] In summary, system (S) allows the use of the material in two distinct ways: the first involves mixing virgin material with up to 50% RAP (recycled asphalt) produced by said system (S), which contributes to sustainability and cost reduction, while maintaining asphalt quality. The second way of using it consists of using 100% of the milled asphalt produced by said system (S) with the application of rejuvenators.
[0047]
[0044] In another embodiment of the invention, the system (S) further comprises a bagging machine (7), which is connected to the mixer (6) by means of a conveyor belt. Thus, after the material reaches a homogeneous mixture in the mixer (6), the conveyor belt directs the material to the bagging machine (7).
[0048]
[0045] Thus, the material can be bagged using the bagging machine (7) or sent to be used directly on the construction site, without being stored, since the system (S) can be placed on the cargo compartment of a mobile vehicle.
[0049]
[0046] It is understood that the beneficiation system (S) comprises a set of conveyor belts (CE), which are responsible for moving the material being processed from one piece of equipment to the next.
[0050]
[0047] Thus, the beneficiation process of the present invention comprises the following steps: a) Passing the material through the grate (10) and inserting the milled asphalt into the raw material receiving silo (1); b) Sending the raw material to the rotary sieve (2), by means of the conveyor belt (12), wherein metallic particles are removed by the magnetic separator (120); c) Fragmenting the lumps and classifying them into at least three types of granulometries, these being 3 / 16 inch, 3 / 8 inch and 3 / 4 inch, while particles larger than % inch are sent to the crusher (3) by means of conveyor belts; d) Sending the material classified in the granulometries 3 / 16 inch, 3 / 8 inch and 3 / 4 inch to the set of dosing hoppers (5), each classification comprising a corresponding dosing hopper (5);e) Manage excess material in the dosing hoppers (5) using the diffuser system (4), diverting the excess material to auxiliary conveyor belts (40) for recirculation, preventing spills; f) Transfer the material from the dosing hoppers (5), with the desired dosage and particle size, to the mixer (6); g) Homogenize and heat the material in the mixer (6) to a controlled temperature between 100 °C and 140 °C; h) Use up to 50% of the material obtained directly from the hot processing plant in conjunction with virgin material.
[0051]
[0048] In one embodiment of the invention, the beneficiation process further comprises a step h) in which up to 100% of the material is mixed with a rejuvenating compound.
[0052]
[0049] In another embodiment of the invention, the material obtained by step h) is transferred to a bagging machine (7) to be stored and used in other applications, such as, for example, pothole patching, road shoulder surfacing, highway sub-base and paving of streets and alleys with low volume of heavy traffic.
[0053]
[0050] In another embodiment of the invention, the system (S) uses at least three large vehicles, such as a semi-trailer or truck, one for the RAP clod breaking and classification, a second for the dosers and mixers with heating of the milled RAP, and a third which is the plant itself.
[0054]
[0051] Anyone skilled in the art will readily recognize, from the description and the drawings provided, various ways of carrying out the invention without departing from the scope of the appended claims.
Claims
CLAIMS 1- “MILLED ASPHALT PROCESSING SYSTEM” characterized by the system (S) comprising at least one raw material receiving silo (1), equipped with a grid (10), at least one rotary screen (2) configured by a hollow cylindrical body (24) and equipped with at least one defined opening size, being disposed downstream of the silo (1) and connected to a first conveyor belt (12), which comprises a magnetic separator (120); the system (S) comprising a set of dosing hoppers (5), interconnected to a diffuser system (4) configured for managing excess material in said dosing hoppers (5), which are disposed upstream of at least one mixer (6), wherein said mixer (6) comprises a means for heating the thermal processing of the milled asphalt; the system (S) comprising a set of conveyor belts (CE) for moving the processed material. 2 - “MILLED ASPHALT PROCESSING SYSTEM” according to claim 1, characterized in that the sieve (2) has at least three types of openings of 3 / 16 inch, 3 / 8 inch and 3 / 4 inch, respectively. 3 - “MILLED ASPHALT PROCESSING SYSTEM” according to claim 1, characterized in that the system (S) comprises a crusher (3) intended for particles larger than 3 / 4 inch, said crusher (3) being connected to the rotary screen (2) and to the silo (1). 4 - “MILLED ASPHALT PROCESSING SYSTEM” according to claim 1, characterized in that the system (S) comprises a bagging machine (7) connected to the mixer (6). 5 - “MILLED ASPHALT PROCESSING SYSTEM” according to claim 1, characterized in that the system (S) is placed on the cargo compartment of at least one large vehicle. 6- "MILLED ASPHALT PROCESSING SYSTEM" according to claim 1, characterized in that the diffuser system (4) comprises at least one auxiliary conveyor belt (40), configured to receive excess material and redirect it to the set of conveyor belts (CE) for recirculation in the system (S). 7- “MILLED ASPHALT BENEFICIATION PROCESS” using the plant defined in claim 1, characterized by comprising the following steps: a) Passing the material through the grate (10) and inserting the milled asphalt into the raw material receiving silo (1); b) Sending the raw material to the rotary screen (2), by means of the conveyor belt (12), wherein metallic particles are removed by the magnetic separator (120); c) Fragmenting the lumps and classifying them into at least three types of particle sizes, namely 3 / 16 inch, 3 / 8 inch and 3 / 4 inch, while particles larger than % inch are sent to the crusher (3) by means of a conveyor belt; d) Forward the material classified in the 3 / 16 inch, 3 / 8 inch and 3 / 4 inch particle sizes to the set of dosing hoppers (5), each classification comprising a corresponding dosing hopper (5);e) Manage excess material in the dosing hoppers (5) using the diffuser system (4), diverting the excess material to auxiliary conveyor belts (40) for recirculation, avoiding spills; f) Transfer the material with the desired dosage and particle size; for the mixer (6); g) Homogenize and heat the material from the mixer (6) to a controlled temperature between 100 °C and 140 °C; h) Use up to 50% of the material obtained directly from the hot processing plant together with the virgin material. 8- “MILLED ASPHALT BENEFICIATION PROCESS” according to claim 7, characterized by comprising a step h) in which up to 100% of the material is mixed with a rejuvenating compound. 9- “MILLED ASPHALT BENEFICIATION PROCESS” according to claim 7, characterized in that the material obtained by step h) is transferred to a bagging machine (7) to be stored and used in other applications, such as pothole patching, shoulder surfacing, highway sub-base and paving of streets and alleys with low volume of heavy traffic.