RU2030438C1 - Process for preparation of liquid bitumens to produce cold asphalt-concrete mixes - Google Patents

Abstract

FIELD: industry of building materials. SUBSTANCE: heated crude oil with thinner - wood resin - in the amount of 3.0-4.5 % of crude oil is oxidized by blowing with air at 150-165 C for 60-90 min. Resin is introduced into petroleum feedstock immediately after blowing. EFFECT: higher efficiency. 5 dwg, 7 tbl

Description

 The method of producing liquid bitumen for the preparation of cold asphalt mixtures relates to road construction, and in particular to the technology for preparing compositions of organic binders, and can be used in the construction materials industry.

 In road construction, methods are known for preparing liquid bitumen by liquefying viscous bitumen with various thinners — naphtha, direct race kerosene [1].

For the preparation of liquid bitumen used: bitumohranilische fence and pumping station or unit (for viscous bitumen) from the heating system to the operating temperature of 60-90 ^{° C;} supply capacity (type D-335A or type D-594) with a pumping unit with a capacity of 500-1000 l / min (type D-379 or D-171A), a mobile steam generator (D-563) [3]. For the preparation of liquid MG class bitumen, thinners in the form of heavy oil products (non-paraffin oil), solar oil, etc.) are most effective [4]. Reducing the cost of liquid bitumen can be achieved by using bottoms of oil refining [5]. Deficiency of thinners - kerosene, naphtha, hydrochloric oil, etc. sharply limits the use of liquid bitumen. To expand the resource was requested diluents oil obtained from their thermal decomposition of tires at 350-800 ^{° C,} and waste transformer oil [6].

 The proposed methods for producing liquid bitumen include the production of viscous bitumen with their subsequent liquefaction by various thinners. They are very laborious, energy intensive and require additional equipment.

 The common disadvantages of the obtained liquid bitumen, apart from the foregoing, are their insufficient adhesion to mineral materials and low resistance to aging.

Closest to the proposed solution is a method for producing liquid bitumen by oxidation of petroleum feed with 10-15 wt.% Fractions of coal tar at 145-150 ^about With for 100-120 minutes This method allows to reduce the complexity and energy intensity of the production of liquid bitumen, improve adhesion to mineral materials, increase resistance to aging, reduce the caking properties of cold asphalt mixtures. However, the method under consideration has a number of drawbacks - a significant consumption of coal tar, which also went into the category of scarce materials, liquid bitumen obtained by this technology still has insufficient adhesion to the mineral part, and cold asphalt concrete has insufficient water resistance.

The advantage of the invention is the expansion of the resources of the organic binder, the reduction in the mass fraction of the additive in the crude oil, the increased adhesion of liquid bitumen obtained by the proposed technology with the mineral part and the water resistance of cold asphalt concrete. This is achieved by the fact that in the method of producing liquid bitumen for the preparation of cold asphalt mixtures, including oxidation by blowing air of heated oil feedstock with a diluent, according to the invention, wood resin is used as a diluent in an amount of 3.0-4.5% by weight of the crude oil, which introduced into the crude oil immediately after the start of its purge with air, and oxidation is carried out at 150-165 ^about With for 60-90 minutes

In FIG. 1 shows the kinetics of oxidation of petroleum feedstock with wood tar additives depending on the time of oxidation; figure 2 - dependence of the strength of cold asphalt using liquid bitumen with a relative viscosity of C ₅ ⁶⁰ = 150 s, the ratio of crushed stone to the seed and the mass fraction of bitumen; figure 3 - dependence of the caking properties of cold asphalt mixtures on the ratio of crushed stone to seed and the mass fraction of bitumen; figure 4 - dependence of the strength of cold asphalt using liquid bitumen with a nominal viscosity, With ₅ ⁶⁰ = 200 s, from the ratio of crushed stone to the seedlings and the mass fraction of bitumen; figure 5 - the dependence of the caking properties of cold asphalt mixtures on the ratio of crushed stone to seedings and the mass fraction of bitumen.

 PRI me R. The following were accepted for the study: petroleum feedstock for the production of viscous bitumen that meets the requirements of TU 38-101582-75, boiled sedimentary wood resin from the Verkhny Sinyachikhinsky timber chemical plant, corresponding to TU 13-4000177-67-85, grade B, coal oil (GOST 2770-59).

The preparation of liquid bitumen was carried out at the laboratory oxidation plant of the compressor type SI-204, with a capacitive reactor. 4 l Air consumption 1,5 l / kg˙min. The dewatered oil feedstock, preheated to ^{160 °} C was placed in a reactor. The compressor turned on. After the compressor starts to work for 10-15 minutes, dehydrated wood resin is introduced directly into the reactor onto the surface of the oil feed. The co-oxidation time is taken in minutes.

The intensity of oxidative processes depends on two factors - the temperature of oxidation and the mass fraction of wood tar in the oil feed. Exploratory studies established that the minimum temperature of the oxidation is 150 ° ^C. At this temperature, begin to manifest themselves in the presence of oxidative processes in the petroleum raw wood tar. This temperature, at which an increase in conditional viscosity is observed, which makes it possible to obtain liquid bitumen. It was also found that a 3% mass fraction of wood tar in petroleum feedstock is the minimum additive, at which a tangible effect is observed both in obtaining the necessary conditional viscosity of liquid bitumen and in improving its quality and cold asphalt concrete.

The maximum oxidation temperature - 180 ^{° C} taken from the condition of minimum flow of oxidative processes in the crude. For our task is to “select” the reactive elements in the petroleum feedstock with wood resin, while the temperature should not provoke the intensive formation of new reactive elements. The maximum proportion of wood tar in petroleum feeds is accepted 6%. An increase in this fraction leads to such a rapid increase in viscosity that it is not possible to obtain liquid bitumen. If the oxidation process is interrupted at an earlier stage, the liquid binder will be oversaturated with the reactive elements of the wood resin, which will also “work” in the coating, thereby causing its premature aging.

Thus, it is accepted:
Z ₁ is the oxidation temperature of the composition is petroleum feed + wood resin;
Z ₁ ^min = 150 ^° C; Z ₁ ^max = 180 ^° C;
Z ₂ - mass fraction of wood tar in petroleum feedstock,%.

Z ₂ ^min = 3%; Z ₂ ^max = 6%.

 For the experiment, 2-factor design of the experiment was adopted.

=

= 165^°C
Z $\genfrac{}{}{0ex}{}{\text{°}}{\text{2}}$ =

=

= 4,5%
Интервал варьирования
ΔZ $\genfrac{}{}{0ex}{}{\text{°}}{\text{1}}$ =

=

= 15^°C
ΔZ $\genfrac{}{}{0ex}{}{\text{°}}{\text{2}}$ =

=

= 1,5%
Закодированные переменные
X₁=

=

X₂=

=

Матрица эксперимента приведена в табл.1.Plan center
Z $\genfrac{}{}{0ex}{}{\text{°}}{\text{1}}$ =

=

= 165 ^° C
Z $\genfrac{}{}{0ex}{}{\text{°}}{\text{2}}$ =

=

= 4.5%
Range of variation
ΔZ $\genfrac{}{}{0ex}{}{\text{°}}{\text{1}}$ =

=

= 15 ^° C
ΔZ $\genfrac{}{}{0ex}{}{\text{°}}{\text{2}}$ =

=

= 1.5%
Encoded variables
X ₁ =

=

X ₂ =

=

The experimental matrix is shown in Table 1.

In accordance with the experimental matrix, 5 oxidations of petroleum feedstock with wood tar additives were carried out. The kinetics of their oxidation is shown in FIG. 1. The numbers of the curves correspond to the numbers of experience. To justify the lower limit of the temperature of oxidation was carried out the oxidation of crude oil at 150 ^about C (kr.6 figure 1).

The characters of curves 1, 6 are almost identical. It follows from them that a 3% addition of wood resin has a negligible effect on the oxidation rate of crude oil, i.e. that minimal additive, with the value of which the rate of oxidation of petroleum feedstock changes. Increasing the mass fraction of wood tar oil feedstock in 2 times (from 3 to 6%) at a temperature of 150 ° ^C oxidation changes the character of the curve. For a period of 30-60 minutes of oxidation, a decrease in the viscosity is observed due to the diluting effect of wood resin; for a period of 60-90 min - some intensification of the process, and after 90 minutes there is a significant acceleration of it. The latter indicates the presence of a large number of reactive elements, the neutralization of which is achieved after 150 minutes of oxidation. Further, the curve is more gentle. To interrupt the oxidation process earlier than 150 minutes, then leave the reactive elements of the wood resin to “work” already in the coating, which will cause its premature aging, and later to obtain bitumen with a higher conditional viscosity.

Curve 2, 4 (Fig. 1) indicates intense oxidation processes, which leads to a sharp increase in the viscosity, and the difficulty in obtaining liquid bitumen. For wood tar at ¹⁸⁰ ° C substantially initiate the oxidation process of the petroleum feedstock and interrupted at an early stage lead to it continue when preparing the mixture and the coating. Therefore, the upper limit of the mass fraction of liquid bitumen will be 4.5% at 165 ^{° C} (kr.5). It is in this mode that the maximum possible conditional viscosity of liquid bitumen C ₅ ⁶⁰ = 200 s is achieved. A large mass fraction of wood resin or an increase in the temperature of oxidation will inevitably lead to an increase in conditional viscosity and it will go beyond GOST. Thus, for the production of liquid bitumen optimal temperature range ^of 150-165 C, and mass fraction of wood tar 3-4.5%. The effect of coal and wood resins on the adhesion index of liquid bitumen obtained by the proposed technology and having approximately the same conditional viscosity was studied by the method based on the ability of some dyes to selectively adsorb from aqueous solutions on the mineral surface, not adsorbing on bitumen. Methylene blue was used as a dye.

Table 2 shows the adhesion indicators of liquid bitumen containing various amounts of additives with mineral materials:
a) marble of the Zestofoni quarry of the quarry of Georgia, characterized by the following composition: M _d = 0.47%, С _о О - 98.85%, insoluble sediment - 0.68%;
b) granite amounted to: O ₂ - 37%, potassium - 51%, X - 12%.

 The coefficient of adhesion of liquid bitumen to the mineral part is given in table 2.

 As can be seen from table 2, liquid bitumen obtained with wood resin have a higher adhesion rate than liquid bitumen with coal tar.

 The study of the physical and mechanical properties of cold asphalt concrete was carried out using local materials from the Yekaterinburg region.

 The name of the materials and particle size distribution are presented in table. 3.

The selection of compositions of cold asphalt mixes is given using the method of mathematical planning. The most acceptable for our research are V _n plans. The following are accepted as variables of the two-factor experiment:
Z ₁ - the ratio of gravel to sowing;
Z ₁ ^min = 40/60; Z ₁ ^max = 70/30;
Z ₂ - mass fraction of liquid bitumen in the asphalt mix.

For the study, two bitumen with a relative viscosity of C ₅ ⁶⁰ = 150 s (ind. 1) and C ₅ ⁶⁰ = 200 s (ind. 5) were taken.

 We accept the lower level of 3.5%, the upper - 6.5%.

 The experimental matrix is shown in Table 4.

 In accordance with the matrix of the experiment, samples were made of cold asphalt concrete mix on liquid bitumen (ind. 1) and tested in accordance with part of the requirements of GOST 9128-84. The test results are shown in table.5.

The physicomechanical properties of cold asphalt concrete prepared on liquid bitumen (ind. 1) with a conditional viscosity of C ₅ ⁶⁰ = 150 s are given in Table 5.

The dependence between the composition of asphalt mix with a tensile strength of asphalt concrete under compression at 20 ^C (R ₂₀₎ using a regression equation
Y = B _o + B ₁ X ₁ + B ₂ X ₂ + B ₁₁ X ₁ ² + B ₂₂ X ₂ ² +
+ B ₁₂ X ₁ X ₂ (1)
The calculated values of R _{20 are} presented in figure 2 in the form of dependences on the mineral composition and mass fraction of liquid bitumen with a nominal viscosity of C ₅ ⁶⁰ = 150 s.

In FIG. Figure 3 shows the dependence of the caking properties of cold asphalt on the particle size distribution of the mineral part and the mass fraction of liquid bitumen (ind. 1) with a conditional viscosity of C ₅ ⁶⁰ = 150 s. Thus, when using liquid bitumen obtained by the oxidation of petroleum feedstock with a 3% additive of wood resin, with a conditional viscosity of C ₅ ⁶⁰ = 150 s, it is possible to produce cold asphalt concrete that meets the requirements of GOST 9128-84 for grades I and II in terms of strength, water resistance, caking , water saturation and swelling at a flow rate of bitumen in the range of 3.5-4%.

A study of physico-mechanical properties of the cold asphalt concrete prepared in liquid bitumen, by oxidation of petroleum feedstock with addition of 4.5% rosin at 165 ^{° C} for 90 min. Conventional viscosity of liquid bitumen C ₅ ⁶⁰ = 200 s, i.e. the upper limit of viscosity at the request of GOST 22245-76. In accordance with the matrix of the experiment, table 4, samples were made from cold asphalt mixture and tested in accordance with the requirements of GOST 9128-84.

 The test results are shown in table.6.

The relationship between the composition of the mixture, the flow rate of liquid bitumen and the tensile strength (R ₂₀ ) using the regression equation (1) is established. The calculated values of R ₂₀ acting as the response function of two variables - the relationship to rubble sharps and mass fraction of liquid bitumen, obtained by oxidation of petroleum feedstock from 4.5% wood tar for 90 minutes at 165 ^{° C} are presented in Figure 4.

The physicomechanical properties of cold asphalt concrete prepared on liquid bitumen with a conditional viscosity of C ₅ ⁶⁰ = 200 s are given in Table 6.

A graphical dependence of the caking properties of cold asphalt mixtures on their grain size and mass fraction of liquid bitumen (C ₅ ⁶⁰ = 200 s) is presented in FIG. 5.

From the above data it follows that when using liquid bitumen obtained by the oxidation of petroleum feedstock with a 4.5% addition of wood resin, with a conditional viscosity of C ₅ ⁶⁰ = 200, it is possible to obtain cold asphalt concrete that meets the requirements of GOST 9128-84 for grades I and II.

 Thus, the optimal compositional ranges of cold asphalt mixtures were determined at various conditional viscosities of liquid bitumen.

 In order to verify the obtained data and compare them with cold asphalt concrete prepared on liquid bitumen using coal tar, cold mixtures were prepared on different liquid bitumen, but on the same particle size distribution. The test results are presented in table.7.

 From the data given in Table 7, it is seen that the water resistance of asphalt concrete prepared on liquid bitumen obtained by the oxidation of petroleum raw materials with the addition of wood tar is higher than that of cold asphalt concrete prepared on liquid bitumen obtained by the oxidation of petroleum raw materials with the addition of coal tar.

 Thus, the proposed method for the production of liquid bitumen allows you to expand the resources of an organic binder, to involve the waste of wood chemical plants - wood resin. Its consumption is reduced in comparison with coal tar more than 3 times. The adhesion of liquid bitumen obtained with wood resin to the mineral part increases significantly in comparison with the same indicator of liquid bitumen obtained by comparable technology. The water resistance of cold asphalt is also increasing.

Claims (1)

METHOD FOR PRODUCING LIQUID BITUMINS FOR PREPARING COLD ASPHALT-CONCRETE MIXTURES by air blowing of heated oil raw materials with a diluent, characterized in that as a diluent, wood resin is used in an amount of 3.0 - 4.5% by weight of the crude oil that is directly introduced into the oil raw material after the start of its purge with air, and the oxidation is carried out at 150 - 165 ^o C for 60 - 90 minutes

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