RU2202471C2 - Method of reworking used rubber-containing articles - Google Patents

Abstract

FIELD: chemical processing of organic wastes, utilization of used rubber-containing articles; metallurgy. SUBSTANCE: proposed method includes grinding and extraction of metal cord. Rubber crumb thus obtained at size no more than 2.5 mm is fed to charge for coking with coal in the amount of 2-5% of mass of charge for obtaining metallurgical coke. Yield of coke increases size classes: +40 mm by 3- 4% and +25 mm by 1.0-1.5% and its mechanical strength is enhanced by parameters: П₂₅ by 0.8-0.9% and П₁₀ by 0.2-0.4%. Yield of chemical coking products increases by 0.9-1.1%. Proposed method makes it possible to obtain metallurgical coke and to increase yield of valuable chemical products: resin and benzene. EFFECT: enhanced efficiency. 2 tbl

Description

 The invention relates to the field of chemical processing of organic waste, in particular to the field of disposal of waste rubber products, and can be used in the metallurgical industry.

Known use as a substitute for coke in blast furnace smelting of rubber products - worn-out tires, which are crushed into pieces weighing 0.3-2.0 kg. The consumption of a coke substitute is 20-50% by weight of cast iron obtained from one feed; pieces of tires are loaded with layers between the layers of the flux-ore part of the charge and the overlying layer of coke in each feed; the reactivity of rubber should be 1.5-15 cm ³ / g • s and the equality between the amount of oxygen in the iron oxides of the ore part of the charge and carbon in the coke substitute must be observed [Pat. of Russia N 2074895. Arshansky MN, Volkov D. N., Komratov Yu.S. et al. Method of blast furnace smelting. BI. N 33, 1998]. Disadvantages of the disposal method: complexity, low technological implementation, limited reactivity, i.e. not all types of rubber-containing products can be used, the chemical potential of rubber is not used at all, soot and polycyclic hydrocarbon emissions in blast-furnace gas increase during rubber burning, carbonization of cast iron due to increased soot emission and negative influence of sulfur on the quality of cast iron take place.

The closest in technical essence and the achieved result is a method of recycling rubber waste by pyrolysis and copyrolysis with coal. When high-temperature coprolysis of rubber waste with a large excess of coal at a low heating rate (3 ^o C / min) corresponding to the coking conditions, heating coke was obtained with a yield of 70-75% with low ash and high reactivity, used as smokeless fuel; hydrocarbon mixtures with a yield of 7-8% are substitutes for scarce fuel oil and gas with a yield of 10-12% [Straka Pavel, Srogl San / Pyrolyza a kopyrolyza organickych odpadu. Cast // Uhli - rudy.- 1992.- 1, N 10.- p. 351-355. - Czech Abstract journal "Chemistry". N.9.1999. 9P27. p.4-5]. The disadvantages of the method: the production of only heating, but not metallurgical coke, its low yield; the production of fuel oil, and not valuable aromatic products, the need to build special pyrolysis plants and workshops for collecting chemical pyrolysis products, i.e., high capital costs and high operating costs due to the need to collect and transport rubber waste over long distances.

 The objective of the proposed invention is the disposal of waste rubber products in the charge for coking in order to improve the quality and yield of metallurgical coke and chemical coking products.

 A method is proposed for processing waste rubber-containing products, including grinding, removing a metal-containing skeleton, characterized in that the rubber-containing crumb with a grain size of 0-2.5 mm is fed into the charge for coking with coal in an amount of 2-5% by weight of the mixture, which increases the yield and quality metallurgical coke and chemical coking products.

The technical result achieved using the proposed method is as follows:
- rubber-containing wastes are utilized in a more qualified manner to produce valuable chemical products and metallurgical coke;
- increases the yield and quality of metallurgical coke;
- increases the yield of coke benzene and coal tar;
- the exhaust gases are processed in a qualified and more efficient way from the processing of spent rubber together with coking products in the workshops for collecting and processing chemical coking products;
- all types of rubber-containing products are processed directly at the place of their most mass formation at metallurgical enterprises (spent tire covers, conveyor belts, etc.):
- simplified technology for the disposal of rubber waste;
- excludes capital costs for the construction of plants for the pyrolysis of rubber, as the equipment of the existing coke production is used.

 Verification of compliance of the claimed invention with the requirements of novelty was carried out taking into account all published inventions, technical and informational literature, and other sources. A comparison of the claimed technical solution with the prototype made it possible to establish its compliance with the criteria of the invention of "novelty."

 The combination of essential features: particle size distribution of rubber crumb, its specific percentage in the charge for coking, and directly the physicochemical properties of rubber allow us to solve the problem of its qualified large-scale utilization with obtaining the technical effect of improving the strength properties of coke and increasing the yield of valuable chemical coking products. This allows us to talk about the materiality of the differences of the proposed invention and its satisfaction with this criterion.

 Signs that distinguish the claimed method from the prototype were not identified in other technical solutions in the study of this field and provide the claimed solution with the criterion of "inventive step".

 A new technical result of the claimed method is as follows: in the comprehensive large-scale disposal of all types of rubber-containing waste in the existing coke production; in increasing the yield and quality of metallurgical coke and increasing the yield of valuable chemical coking products - benzene, coal tar.

 Physico-chemical characteristics of rubber crumb are presented in table 1. It describes the basic properties of crumb rubber in terms of the possibility of its use as a component of a coal charge. From the data of table 1 it is seen that the rubber crumb is mainly a hydrocarbon material containing 87-89% carbon. These data, as well as studies described in the literature, suggest that thermal decomposition of rubber leads to the formation of hydrocarbon structures chemically compatible with the pyrolysis products of coal material. This makes it possible to use rubber waste as a component of a coal charge in the process of high-temperature coking.

 Examples confirming the proposed method for processing rubber-containing waste in a charge for coking are presented in table 2.

 Tests of rubber crumb in a coal charge were carried out by coking the base and experimental charges in a laboratory furnace with a charge of 2 kg in accordance with GOST 9521-74. The basic charge was composed of the components of the production coal charge of ZSMK OJSC. As the used material, tire crumb of various sizes was studied: 0-0.63, 0.8-1.5, 0-2.5, 2.5-5.0 mm, which was introduced into the base charge instead of part of the coal component in the amount of 2-7% of the mass of the charge.

 Studies of the quality of the components of the charge, charge and coking products were carried out in accordance with existing methods: technical analysis GOST 11014-81, 27589-91, 11022-95, 6382-91, 8606-93; plastic analysis of GOST 1186-87; elemental analysis GOST 27044-86, 2408.275; determination of coal coking ability GOST 9521-74; yield of coking chemicals GOST 18635-73.

 The data in Table 2 show that the introduction of crumb rubber into coal blends affects the yield and quality of coking products. A significant role is played by the size and amount of added rubber.

Durable coke at the base level (example 2, example 1 - gas coke) or increased strength in terms of mechanical and structural strength - P ₂₅ , P ₁₀ , P _s obtained by adding rubber crumb to the charge with a grain size of: 0-0.63; 0.8-1.5; 2.5 and 0-2.5 mm in an amount of 2 and 5% by weight of the mixture. At the same time, the yield of large classes of coke significantly increased (examples 3, 4, 5, 7). So, coke from a mixture containing rubber crumb with a particle size of 0-2.5 mm in an amount of 2% (Example 5) had the following quality indicators: yield of class +40 mm - 74.5%: yield +25 mm - 94.1% ; P ₂₅ - 91.9%; P ₁₀ - 6.4%; P _s - 89.7%.

Coke from the mixture with the addition of crumb rubber of the same size - 0-2.5 mm in an amount of 5% (example 7) also had improved quality compared to the base: yield classes +40 mm - 73.4%, + 25 mm - 94 6%; P ₂₅ = 92.0%; P ₁₀ = 6.6%: P _s = 89.4%.

The increased content (7%) of rubber crumb in the mixture with a particle size of 0-2.5 mm led to a decrease in the structural strength of the obtained coke (examples 8, 9, 10, 11). Other indicators of coke quality remained high. Coke from such a charge (example 11) was characterized by the following quality indicators - the yield of classes, mm: +40 - 72.6%, +25 - 94.9%; P ₂₅ = 92.0%, P ₁₀ = 6.6%, P _C = 87.9%.

 The introduction into the mixture of rubber crumb of a larger size (2.5-5.0 mm) adversely affected all coke quality indicators (examples 6, 12).

 The addition of rubber to coal blends increased the yield of valuable chemical coking products: resin and crude benzene (examples of Table 2).

 The increased sulfur content in rubber (1.30-1.37%) led to a slight increase in the sulfur content in coke: from 0.38 (base coke) to 0.41-0.42% when rubber crumb was added in an amount of 2-5 % (examples 5, 7).

Thus, the introduction into the coal charge of rubber crumb with a grain size of 0-2.5 mm in the amount of 2-5% by weight of the charge positively affected the yield and quality of the obtained coke - the yield of classes, mm: +40 increased by 3-4%, +25 - by 1-1.5%, mechanical strength in P ₂₅ increased by 0.8-0.9%, in P ₁₀ - by 0.2-0.4%. Structural strength P _s remained at the base level (examples 5, 7). The yield of tar and crude benzene increased.

 The development of the claimed method will allow qualified disposal of on-site rubber-containing waste, reduce capital and operating costs for their disposal, increase the yield and quality of coking products. The claimed method is industrially applicable at each coke production.

Claims (1)

A method of processing waste rubber-containing products, including grinding, metal cord extraction, characterized in that the rubber-containing crumb with a grain size of not more than 2.5 mm is fed into the charge for coking with coal in an amount of 2-5% by weight of the mixture to obtain metallurgical coke with an increase in yield larger classes: +40 mm by 3-4%, +25 mm by 1.0-1.5%, increase in mechanical strength in terms of: P ₂₅ by 0.8-0.9%, P ₁₀ by 0.2 -0.4%, an increase in the yield of chemical coking products by 0.9-1.1%.

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