RU2718808C1 - Method of producing a polymer-bitumen binder concentrate - Google Patents

Abstract

FIELD: production technology.

SUBSTANCE: invention relates to production of bitumen-polymer compositions used in road construction. Disclosed is a method of producing a concentrate of polymer-bitumen binder, which includes dosing initial raw material, mixing and homogenization, granulating mixture on extruder, granulation of powders, their sieving and packaging, wherein the starting material includes a thermoplastic elastomer based on block copolymers of butadiene and styrene of a linear and/or radial type, a plasticizing component and an oil bitumen. Feedstock is mixed for not more than 6 minutes at temperature not higher than 90 °C until formation of homogeneous medium. Further, the obtained mixture is shaped into a strip or a bundle fed to an extruder for subsequent granulation on a granules end cutting device, which is a granulating device. Said extruder is equipped with cooling system of all working zones of extruder, and is also configured to maintain preset temperature of granulating device, at that during pellets cutting mineral powder is supplied to granulating device to prevent granules sticking together. Further, the granules are transported to a vibration screen where the stuck granules are screened.

EFFECT: technical result consists in improvement of productivity of polymer-bitumen binder concentrate due to reduction of production cycle with simultaneous increase of storage life of concentrate.

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Description

The invention relates to the field of producing bitumen-polymer compositions used in road construction.

State of the art

There is a polymer-bitumen binder (PBB), widely used in the construction of roads. PBB is a modified binder, a mixture of bitumen (about 93%), plasticizer (about 3%) and SBS polymer (styrene-butadiene-styrene) (about 3%). The exact composition is selected depending on the quality (parameters) of the starting components, so that the finished product is ready-made according to GOST R 52056-2003.

PBB improves the quality and durability of roads, but has a number of shortcomings in terms of manufacturability. All the disadvantages are due to the fact that PBB is produced, transported, stored and used in liquid form and in a heated state. The main disadvantages:

• Special conditions for the transportation and storage of PBB presented by GOST 1510 for viscous road petroleum bitumen.

The temperature of heating of PBB during transportation and storage should not exceed 160 ° C. The storage time of PBB without stirring at a temperature not exceeding 160 ° C should not exceed 8 hours. If it is necessary to store the PBB in a heated state for more than 8 hours, in order to avoid delamination, it is necessary to ensure its mechanical mixing or effective circulation with a frequency of not more than 2 hours, which should not begin later than 3 hours after the start of storage.

PBBs are transported to the place of use in bitumen trucks, asphalt distributors or heated tanks.

WSP transportation with a duration of more than 3 hours in a heated state should be carried out in bitumen trucks equipped with binder heating elements and provided with bitumen pumps, while no later than 3 hours after the start of transportation, the bitumen truck should be stopped every 2 hours and the WSP should be mixed using a bitumen pump by circulating yourself.

After long-term storage or transportation, PBB is allowed to be used only after stirring at 160 ° C until it is homogeneous and if its properties meet the requirements of this standard.

The maximum shelf life of the PBB does not exceed two weeks.

• Small transport shoulder. Since the maximum temperature for storage and transportation of PBB is limited to 160 ° C, and the temperature during unloading should not be lower than 140 ° C - this imposes a limitation on the transportation distance (usually not more than 1000 km.).

• The limited range of transportation requires the construction of local plants for the production of PBB. Moreover, the production cycle of a batch of PBB is about 8 hours.

CPBV is a concentrate of polymer-bitumen binder in dry granular form, designed to modify bitumen and asphalt mixes, used in the road industry on highways of federal, regional and municipal significance.

The prior art method for producing polymer-bitumen compositions according to patent RU2522618, including heating with stirring bitumen and a polymer modifier, the polymer modifier obtained directly in the medium of bitumen by radical polymerization of vinyl monomers at a temperature of 60-80 ° C in the presence of a radical polymerization initiator . The process of obtaining the composition is carried out for 2-4 hours at the same temperature. In this case, oil bitumen is used as bitumen. The ratio of the components is as follows, wt.%: Vinyl monomer - 2-10; initiator, wt.% by weight of the monomer - 0.5-4; petroleum bitumen - the rest. The result is the expansion of the range of polymer-bitumen compositions with improved performance characteristics while simplifying the technology for preparing the composition, providing the possibility of the process of preparing the compositions in a continuous mode and the absence of expensive ingredients in their preparation.

Also known is a method of producing a bitumen-polymer composition according to patent application RU 200819888 consisting in mixing thermoplastic elastomer, bitumen and mineral filler when heated, the crushed bitumen and thermoplastic elastomer are fed into a heated mixture of a liquid pyrolysis product with hydrocarbon oil up to 80 ° C, after which mineral fillers, the resulting composition is whipped for 30 minutes

The disadvantages of these production methods are low productivity, increased energy consumption and short shelf life of the resulting substances.

The closest analogue of the claimed invention is a method for producing a bitumen-polymer composition according to patent RU 2177969, which consists in the fact that they mix 100 wt. including thermoplastic elastomer based on conjugated diene and vinyl aromatic monomer, 70-200 wt. including pre-heated to a temperature of 90-110 ° C bitumen, 30-250 wt. including mineral filler and mixing at a temperature of 70-100 ° C for 10-15 minutes, the resulting mixture is homogenized at a temperature of 130-160 ° C for 10-15 minutes in a screw extruder equipped with a granulating device, cooled with water having a temperature 20-40 ° C, through which the composite mass passes, then the obtained granules of the composition are dried and packaged.

The disadvantage of this method is the increased energy consumption and low productivity due to the complexity of the method, in particular the presence of pre-heating of the bitumen, the duration of mixing of the mixture, the need to maintain a high temperature during mixing, as well as the presence of a separate homogenization step, short shelf life.

The technical problem is to eliminate these drawbacks with the achievement of the technical result, which consists in increasing the productivity of the production of polymer-bitumen binder concentrate by reducing the production cycle while increasing the shelf life of the concentrate.

The specified technical result is achieved in a method for the production of a polymer-bitumen binder concentrate, including dosing of feedstock, mixing and homogenizing it, granulating the mixture on an extruder, dusting the granules, sieving them and packing them . The feedstock includes thermoplastic elastomer based on block copolymers of butadiene and styrene of linear and / or radial type, a plasticizing component, petroleum bitumen. Mixing the feedstock is carried out until a homogeneous medium is formed. The resulting homogeneous mixture is profiled and fed to the extruder for subsequent granulation on the device for face cutting of granules, which is a granulating device. The said extruder is equipped with a cooling system for the working areas of the extruder, and is also configured to maintain a predetermined temperature of the granulating device. In the process of cutting granules on a granulating device, they are dusted with mineral powder. The obtained granules are transported to a vibrating screen for sifting.

An additional feature is that the raw materials are mixed for no more than 6 minutes at a temperature not exceeding 90 ° C.

An additional feature is that the mixture is profiled into a strip or bundle.

An additional feature is that it contains thermoplastic elastomer based on block copolymers - butadiene and styrene of linear and / or radial type - 30 parts, plasticizing component - 32 parts; oil bitumen - 38 parts.

An additional feature is that the feedstock additionally contains target additives, which are used as components that ensure the manufacturability of the production of polymer-bitumen binder concentrate and do not affect its functional properties.

An additional feature is that the feedstock additionally contains surfactants and / or stabilizing additives that improve the performance of asphalt concrete.

An additional feature is that mineral oil is used as a plasticizing component.

An additional feature is that the batching of the feedstock is carried out automatically using dispensers of bulk and liquid materials controlled by an automatic process control system.

An additional feature is that the mixing of the components is carried out in a closed-loop rubber mixer of periodic type high-speed or low-speed.

An additional feature is that the rubber mixer contains a chamber, two rotors placed in the specified chamber, and are made to rotate towards each other, while in this chamber there are windows for loading components and unloading the finished mixture, which are closed by protective mechanisms during operation.

An additional feature is that the extruder contains both one and several cooling zones in the range of 30-100 degrees, equipped with temperature sensors.

An additional feature is that the granules are additionally dusted by the device for additional dusting of granules, in an amount not exceeding 3% by weight of the granules.

An additional feature is that an extruder compound is used as a rubber mixer and extruder.

Disclosure of Invention

The claimed concentrate is used directly at the asphalt concrete plant, does not require modification of the plant and installation of additional equipment. The use of CBPV is an alternative technology for producing asphalt concrete mixtures on PBB (polymer-asphalt concrete), which is free from the disadvantages and limitations of traditional technology (short life of PBB, short transport shoulder, aging of bitumen during its modification with SBS polymer, the need to build PBB plants, inconvenience of storage finished product, etc.).

There are two ways to introduce CPBV into the asphalt mix - dry and wet:

With the dry method, CPBV is introduced into the asphalt mixture immediately at the time of its preparation at the ABZ for these purposes, as a rule, the stabilizing additive supply line is used.

With the wet method - CPBV is introduced into bitumen with the preparation of a modifying binder, which in turn is used to prepare asphalt mixes at the ABZ.

The use of CBPB allows one to obtain an asphalt concrete mixture identical in composition and parameters to the mixture using PBB; only the method of introducing a modifying additive into the asphalt mix changes: in the case of PBB, this is a wet modification method, in the case of CBPV, a dry and wet modification method is also possible.

So, in the case of using the CPBV in the dry way: when preparing polymer-asphalt concrete and alkali-concrete mixtures, the modification is carried out directly when preparing asphalt-concrete mixtures by adding CPBV through the supply line of a stabilizing additive. The modification time is commensurate with the time of preparation of asphalt concrete and gravel-mastic mixtures and is about 20-30 seconds. This is the most preferred and popular method of modifying a binder.

With the wet method: the modification of oil road bitumen can be done by adding CPBV directly to the bitumen storage, equipped with a mechanical stirrer or circulation pump. Complete dissolution of the CBPB occurs in a time not exceeding 60 minutes in the temperature range 170-180 ° C. In the future, storage of a binder, modified CBPB does not differ from storage of PBB. This method has much less advantages and can be used, for example, for evaluating, in laboratory conditions, an astringent for compliance with the requirements of current standards.

CPBV is a mixture of:

- block copolymers of butadiene and styrene linear and / or radial type;

- plasticizing component;

- petroleum bitumen;

Additionally, the CPBV may contain:

- Target additives are components that ensure the manufacturability of the manufacture of a polymer-bitumen binder concentrate and do not affect its functional properties, for example, mineral powder.

- Functional additives - surface-active substances (surfactants), stabilizing additives or other components that improve the performance properties of asphalt concrete.

All components are taken in certain proportions. After mixing, the finished product is a dark-colored material with a density of 0.7-0.8, in hardness it resembles medium-hard rubber, uniform in volume, prone to sticking especially at elevated temperatures (50 degrees or more), at a temperature of about 80 degrees softens.

Process Stages:

• Warehousing of raw materials;

• Dosing of starting materials;

• Mixing the starting materials to form a mixture;

• Profiling the mixture;

• Granulation of the mixture;

• Dusting and cooling, sieving and aspiration of granules;

• Taring and packaging.

The implementation of the invention

The feedstock arrives at the feedstock warehouse where it passes input control for compliance with the passports with the data and requirements of the manufacturer.

The components of the polymer-bitumen binder concentrate are taken in the following ratio:

- thermoplastic elastomer based on block copolymers of butadiene and styrene linear and / or radial type - 30 parts,

- plasticizing component - 32 parts;

- oil bitumen - 38 parts.

In special cases, depending on the formulation and the required properties of the finished product, there may be a different composition and ratio of components, as well as a different sequence of loading and mixing them.

Dosing of feedstock in the simplest case is a manual or automatic dosing of each component in the amount necessary for one batch. To automate the process, it is possible to provide dispensers of bulk and liquid materials, which are controlled by an automatic process control system (APCS) and provide the required composition of the CBPV. The dispenser and the process control system are elements of the technological line aimed at automating the process. These elements can be excluded (both or separately) and this will not affect the final result (product) in any way, just manual labor will be added.

After dosing (from the dispensers), the raw material in the required quantity enters the rubber mixer, where the components are mixed and homogenized. Mixing of components is possible in a rubber mixer of periodic action, closed type, slow or high-speed. The working bodies of such mixers are two rotors placed in the chamber and rotating towards each other. The camera has windows for loading components and unloading the finished mixture. During the preparation of the mixture, the windows are closed with protective mechanisms. The volume of the rubber mixer is 70-90 liters. Mixing cycle - no more than 6 minutes at a temperature of no higher than 90 ° C.

To supply the mixture to the granulation line, it is necessary to profile the finished mixture from the rubber mixer into the strip or go to the harness. The specific profile and dimensions depend on the design and performance of the granulation line. There is experience profiling in a strip measuring 120x15 mm.

For profiling, rubber mixing rollers or a cold-action screw extruder can be used. The productivity of the profiling line should be equal to or a multiple of the productivity of the rubber mixer. Constructive implementation of the profiling line - does not affect the final result (product).

After profiling, the mixture enters the extruder having one or more cooling zones in the range of 30-100 degrees, equipped with temperature sensors with the ability to maintain the desired temperature in the extruder zones. The extruder also has a face cutting device for granules on a die with a cooling and heating system, with the ability to maintain a given temperature.

The granule sticks together during the cutting process on the die; to prevent sticking, slaked lime must be fed into the cutting chamber. Further, the granule should be transported by pneumatic transport to a vibrating screen. The working bodies of the blower and cyclone break the adhered, powdered granule. The length of the pneumatic conveying line should be selected in such a way as to ensure cooling of the granule before it enters the closed type vibrating screen with a device for additional dusting of granules. Granules are additionally dusted in an amount not exceeding 3% of their mass.

Additional dusting of the granules is necessary to prevent caking of the material in big bags. The vibrating screen should filter out the sticky granule. The percentage of non-passed filter granules does not exceed 10%.

Further transportation of powdered granules should be carried out on a conveyor belt to the tare and packaging station.

The entire transportation system is airtight and has cyclone filters. The ingress of slaked lime into the surrounding air is excluded.

The finished granule arrives at the tare and packaging station, then it is placed in the finished product warehouse where acceptance tests are carried out.

As a rubber mixer and an extruder, an extruder compound may be used.

The time for preparing PBB using CBPB does not exceed the time for preparing the asphalt concrete mixture, as a result of which the bitumen is not exposed to a prolonged temperature effect, which means its oxidation decreases and the aging of bitumen decreases. A short production cycle prevents stratification of the WSP.

CPBV is delivered in soft “big bags” containers, transported by ordinary freight transport and does not require special storage conditions. Shelf life of CPBV is 1 year.

CPBV consumption rates for the modification of bitumen and asphalt mixes:

• The consumption of PPBV for the preparation of PBB is 7-12% by weight of the binder.

• Consumption of CBPBV (without stabilizing additive) for the preparation of asphalt mixtures of type A and B is 0.4 - 0.7% by weight of the mineral part.

• Consumption of CBPBV (with stabilizing additive) for mixtures of alkali alkali metal is 0.6 - 0.9% by weight of the mineral part.

The exact amount of CBPB is determined by the selection of the composition of the PBB or asphalt mix that satisfy the specified requirements.

The production of CBPV is characterized by low energy consumption, low cost of basic equipment, ease of operation and maintenance.

The production technology of the modifier is unique, has no analogues, while the production line can be built on the basis of commercially available domestic or imported equipment with modification and refinement according to an additional technical task for 4-6 months.

Claims (19)

1. Method for the production of polymer-bitumen binder concentrate, including dosing of feedstock, mixing and homogenizing it, granulating the mixture on an extruder, dusting granules and packaging, characterized in that the production of polymer-bitumen binder concentrate is carried out at a temperature not exceeding 90-100 ° FROM, - the feedstock includes thermoplastic elastomer based on block copolymers of butadiene and styrene of a linear or linear and radial type, a plasticizing component, petroleum bitumen; - mixing of the feedstock is carried out until a homogeneous medium is formed; - the resulting homogeneous mixture is profiled and fed to the extruder for subsequent granulation on the device for face cutting of granules, which is a granulating device that is part of the specified extruder; - while the said extruder is equipped with a cooling system for the working areas of the extruder, and is also configured to maintain a predetermined temperature of the granulating device, while - in the process of cutting granules on a granulating device, they are dusted with mineral powder;  - the resulting granules are transported to a vibrating screen for sifting. 2. The method according to p. 1, characterized in that the mixing of raw materials is carried out for no more than 6 minutes at a temperature not exceeding 90 ° C. 3. The method according to p. 1, characterized in that the mixture is profiled into a strip or bundle. 4. The method according to p. 1, characterized in that it contains thermoplastic elastomer based on block copolymers of butadiene and styrene linear and / or radial type - 30 parts, plasticizing component - 32 parts; oil bitumen - 38 parts. 5. The method according to p. 1, characterized in that the feedstock additionally contains target additives, which are used as components that ensure the manufacturability of the production of polymer-bitumen binder concentrate and do not affect its functional properties. 6. The method according to p. 1, characterized in that the feedstock additionally contains surfactants and / or stabilizing additives that improve the operational properties of asphalt concrete. 7. The method according to claim 1, characterized in that mineral oil is used as the plasticizing component. 8. The method according to p. 1, characterized in that the dosing of the feedstock is carried out automatically using dispensers of bulk and liquid materials controlled by an automatic process control system. 9. The method according to p. 1, characterized in that the mixing of the components is carried out in a batch rubber mixer of the closed type high-speed or low-speed. 10. The method according to p. 9, characterized in that the rubber mixer contains a chamber, two rotors placed in the specified chamber are made to rotate towards each other, while in this chamber there are windows for loading components and unloading the finished mixture, which are closed by protective mechanisms during operation. 11. The method according to p. 1, characterized in that the extruder contains both one and several cooling zones in the range of 30-100 ° C, equipped with temperature sensors. 12. The method according to p. 1, characterized in that the granules are additionally dusted with a device for additional dusting of granules in an amount not exceeding 3% of their mass. 13. The method according to p. 1, characterized in that the extruder-compound is used as a rubber mixer and extruder.