Nowadays in the world, due to the constant desire for recycling, many countries are considering the use of recycled plastics on roads. Modification of bitumen for roads in Kazakhstan is considered one of the most suitable and popular approaches. This paper presents the results of research on the modification of bitumen by recycled plastics from waste materials. The paper describes the details of the use of plastic waste as bitumen modifiers, with a specific focus on recycled plastics and how they can potentially be used to enhance bitumen performance and the road durability. The main physical and mechanical characteristics of the modified bitumen were determined after routine tests, penetration and plasticity, softening temperature, brittleness temperature on Fraas and microscopic analysis. The morphology of the modified bitumen was studied using scanning electron microscopy. The results confirm that the modified bitumen complies with the requirements for polymer-bitumen binder of Kazakhstani standards and is suitable for the production of modified bitumen by its physical and chemical characteristics.
The article presents the results of research on the production of polymer-bitumen binder (PBB) based on mixtures of non-oxidized and oxidized petroleum products, namely high-viscosity tar, darkened vacuum distillate, and oxidized petroleum bitumen 70/100, obtained at technological installations of Limited Liability Partnership (LLP) “JV Caspi Bitum’’ and styrene-butadiene-styrene (SBS) block copolymer brand L 30-01A modifier in the presence of a stabilizer. The results obtained show that the introduction of the SBS modifier in the presence of a sulfur stabilizer improves the performance characteristics of PBB, such as elasticity, ductility, softening temperature, penetration, and brittleness temperature.
Lead sludge from copper production is a source of rare metals, such as rhenium and osmium, whose content reaches 0.06–0.08% and 0.0025–0.0050%, respectively. The base of the sludge consists of lead sulfate. A method of reductive smelting of lead sludge from copper smelting production at 1000–1100 °C has been developed. Coke was used as a reducing agent and sodium sulfate as a slag-forming material. Optimal conditions for selective extraction of rare metals in smelting products were found: osmium in the form of metallic form into raw lead and rhenium in the form of perrhenate compound Na5ReO6 into sodium-sulfate slag. The developed technology makes it possible to extract rhenium with a high degree of extraction in the form of water-soluble compounds for the subsequent production of commercial salts of rhenium by the known hydrometallurgical methods. The content of rhenium in the slag phase is 0.18–0.25%, with its initial content in the slime of 0.06–0.08%. The degree of rhenium concentration at the first stage of processing is 3–3.2 times in the form of water-soluble perrhenate. Osmium and lead do not form solid solutions; osmium in crude lead is mainly concentrated in the lower zones of lead. A method of obtaining a concentrate containing 53–67% osmium from raw lead with an initial content of 0.0025–0.0050% in the slurry and a concentration number of 13,000–21,000 times has been proposed.
The article examinee the characteristics of sewage sludge and its impact on the environment. The description of technical installations, sludge sites in the municipal wastewater treatment systems, which are sources of unfavorable sanitary and epidemiological condition of the studied territory, was presented. A detailed analysis of the structure, composition and morphology of sludge sediment was given. It was found that the sludge presents a loose, rough heterogeneous porous structure represented by the presence of a fibrous substrate with amorphous scalycrystalline inclusions. During laboratory analyses of the composition of the dry residue, the presence of such types of heavy metals as chromium, manganese, nickel, copper, zinc, lead, cobalt, molybdenum, cadmium was revealed. The excess of permissible concentrations of various elements was observed: chromium more than 7.1 at MPC -6.0 by 1.18 times; copper more than 3.3 at MPC -3.0 by 1.1 times; zinc more than 27.3 at MPC -23.0 by 1.18 times; lead more than 34.3 at MPC -32.0 by 1.07 times; cobalt more than 6.4 at MPC -5.0 by 1.28 times; molybdenum more than 6.9 at MPC -5.0 by 1.3 times. Soil analysis revealed a pH of 7.1, which is neutral, may be optimal for plants; the concentration of calcium, iron and chromium does not exceed the established maximum permissible values. When analyzing the air environment of the territory of the treatment facilities, the presence of gaseous pollutants, such as methane, ammonia, nitrogen dioxide, hydrogen sulfide, carbon monoxide, was established. It has been established that anthropogenic sludge landfills are the sources that create a technogenic load on the atmospheric air, polluting it with methane, since the concentration of methane exceeds the MPC by more than 3 times.
It is proposed to use plastic waste as bitumen modifiers with a special emphasis on recycled plastics. The potential use for improving the characteristics of bitumen and durability of roads is being considered. For the preparation of modified bitumen, it was used the BND 100/130 bitumen produced by LLP "JV CASPI BITUMEN" (Kazakhstan). Polymer household waste based on plastic bottles was used as objects of the research. Polymer waste was obtained by mechanical recycling. The main physical and mechanical characteristics of the modified bitumen were determined after routine tests, penetration and plasticity, softening temperature, Fraas brittleness temperature and microscopic analysis. The morphology of the modified bitumen was studied using scanning electron microscopy. An original formulation of the polymer-bitumen binder with improved performance characteristics compared to petroleum bitumen has been developed. The introduction of used polymer waste as a modifier does not require the installation of an additional homogenizer (colloidal mill), and there is no need to introduce a plasticizer to achieve the desired uniformity of the system and required by the Kazakhstan standard PMB 40 and PMB 90. Thanks to the use of this technological solution, it is possible to level the problem of disposal of household polymer waste with the polymer-bitumen binder production. This polymer modifier is characterized by low cost of its production. The advantage of the used polymer additive is the stage of polymer preparation - the process of joint chemical destruction of secondary polyethylene terephthalate in the presence of a highly elastic styrene-butadiene-styrene polymer to inhibit the delamination of polymer components in bitumen, due to which the problem of manufacturing high-quality homogenization of the product is solved.
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