RU2224782C1 - Charge for manufacture of metallurgical coke - Google Patents

Abstract

FIELD: metallurgy. SUBSTANCE: charge contains, wt %: medium volatile coals 20-30, gas fat coals 15-20, coke low-caking coals 20- 40, caking additive 3-6, and emaciated caking coals - the balance, said additive being prepared by mixing cake-like product with plastic production waste at ratio 1: (0.1-0.2) and heating resulting mixture to 300-350 C for 0.5-1.0 h. EFFECT: increased mechanical strength of coke. 2 tbl

Description

 The invention relates to the preparation of charge materials and can be used in the production of metallurgical coke.

Known mixture for producing metallurgical coke having the following ratio of components, wt.%:
gas coals - 15-25
fatty coals - 25-35
coke coals - 30-38
oil-sludge-containing sludge - 1-2
sintering coals - the rest
(Auth. Certificate. USSR 1736993, MKI 5 C 10 B 57/04, 1992).

 However, when oil-sinter-containing sludge is introduced into the charge, the ash content of the charge increases, and hence the ash content of coke. The mechanical strength of M25 coke increases slightly, for example, by 0.8%.

Known mixture for producing metallurgical coke containing, wt.%:
gas coals - 45-55
fatty coals - 17-25
coke coals - 10-15
sintering additive - the remains of the process of heat treatment of sulphurous tar in the presence of iron ore concentrate - 2-4
sintering coals - the rest
(Aut. Certificate. 1703674, MKI 5 C 10 B 57/04, 1992).

 This charge includes a sintering additive - the remains of the process of heat treatment of sulfur tars in the presence of iron ore concentrate with a sulfur content of 2.65%. During coking of the charge, sulfur goes into coke, and the sulfur content in coke is limited.

 The objective of the invention is to increase the mechanical strength of coke while recycling plastic waste.

The problem is achieved in that the mixture for producing metallurgical coke containing fatty, lean sintering coals and a sintering additive, according to the invention it additionally contains gas-fatty, coke low-sintering coals, and the sintering additive is obtained by mixing a pitch-like product with plastic waste in a ratio of 1 : 0.1-0.2, by heating the mixture to 300-350 ^o C for 0.5-1.0 hours in the following ratio of components, wt.%:
gas-fatty coals - 15-20
fatty coals - 20-30
low coking coals - 20-40
sintering additive - 3-6
sintering coals - the rest
The invention consists in compiling the optimal composition of the mixture to obtain metallurgical coke, in determining the optimal ratio of the components of this mixture, in a new technology for producing a new sintering additive, which is carried out in two stages:
- obtaining a pitch-like product by mixing coal with an additive, introducing a solvent to form a suspension, processing it under pressure of its own gases at an elevated temperature, with the catalyst being used as a transition metal salt in an amount of 4.0-6, previously 0 by weight of the additive, as the last use the waste of the dry coke quenching plant - pulverized coke in the amount of 1.0-1.5% by weight of coal, the solvent is introduced into the prepared coal in the ratio (1.0-2.5): 1, heat up to a temperature of 210-350 ^o C at which is held for 0.3-0.6 hours (Patent RU 2181746 IPC 7 C 10 G 1 / 04.1 / 06, 2002 YG).;
- obtaining the sintering additive itself by mixing a peciform product with plastic waste in a ratio of 1: 0.1-0.2, heating the mixture at a temperature of 300-350 ^o C for 0.5-1.0 hours

 It was experimentally established that the content of gas-fat coals in the charge of less than 15% is undesirable, because shrinkage properties of coke cake are deteriorating, the force of issuing (amperage) of its issuing is increasing.

 When the content of gas-fat coals in the charge is more than 20%, the yield of volatile substances in the charge increases, which leads to a decrease in the mechanical strength of coke due to an increase in crack formation in coke.

 The choice of limits for the content of fatty coal in the mixture is due to the following: an increase in the content of fatty coal in the mixture by more than 30% leads to a decrease in the coke size and its mechanical strength due to the development of high internal stresses during coking and an increase in the shrinkage gradient, as well as increased fluidity of the plastic mass.

 When the content of fatty coals in the charge is less than 20%, its sintering properties deteriorate, the strength of coke decreases and its abrasion increases.

 The content of coke low-caking coals in the mixture ranged from 20 to 40%. Studies have proven that the content of coke low-caking coals in the charge of less than 20% leads to an increase in the relative share of coals with a high yield of volatile substances (GF, G, OS), which contributes to an increase in the porosity and fracture of coke, its reactivity and a decrease in mechanical strength. The introduction of more than 40% coke low-sintering coals into the charge, on the contrary, reduces the yield of volatile substances from the charge, which reduces the shrinkage of the coke cake and makes it difficult to dispense from the coking chamber, as well as the sintering of the charge with a decrease in the mechanical strength of coke.

 When the content of the sintering additive in the mixture is less than 3%, its effect on the mechanical strength is insignificant.

 The increase in the content of sintering additives in the mixture of more than 6% is impractical, because the strength of coke decreases, and the abrasion of coke increases.

The dissolution of plastic waste (PWM) in a liquid pecky product (POP) is the process of the chemical interaction of hydrogen-saturated radicals of aliphatic plastic molecules with radicals of aromatic hydrogen-unsaturated molecules of a pecky product. It was experimentally established that the radicals formed during the heating of a mixture of plastic waste and a pecky product (fragments of OPM and POP macromolecules) interact most actively with the formation of stable macromolecules of a sintering additive in the temperature range 300-350 ^o С. When the mixture is heated below 300 ^o С, the radicals interacting components are not active enough, which makes it impossible to obtain a sintering additive of a uniform composition. Above 350 ^o With the heating of the mixture is impractical, because the equilibrium state of the processes of destruction and polymerization is violated with the prevalence of pyrolysis and dehydrogenation processes, which contributes to the removal of hydrogen atoms from the reaction mixture in the form of volatile substances, and the macromolecules remaining unsaturated with hydrogen lose their sintering ability.

 Studies have shown that the exposure time of the mixture at elevated temperature should be in the range of 0.5-1.0 hours. Exposure to the mixture of less than 0.5 hours is undesirable because the chemical dissolution of the plastic waste in the solder-like product does not have time to complete. Exposure to more than 1.0 h is impractical, because it does not improve the quality of the sintering additive due to the prevalence of polycondensation processes, longer exposure reduces the productivity of the process, increases the amount of energy expended on it.

 Upon receipt of the sintering additive, the amount of plastic waste added to the pitch-like product was determined on the basis of achieving the maximum possible amount of recyclable plastic waste in the process of obtaining a sintering additive with a uniform structure and optimal sintering properties. It was determined that when the ratio in the POP: OPM mixture was less than 1: 0.1, the sintering ability of the obtained product practically did not change, and the obtained product had an inhomogeneous structure. When the ratio in the POP: OPM mixture is more than 1: 0.2, the sintering ability of the final product does not improve and leads to a deterioration in its physical and mechanical properties - it becomes sticky and crushes worse.

 The proposed composition of the mixture to obtain metallurgical coke with the specified ratio of the components ensures the achievement of the technical result, which consists in obtaining coke with increased mechanical strength. The receipt of this technical result was achieved by solving the problem at the inventive step, in particular, by the optimally selected composition of the mixture, the technology for producing one of its components - sintering additive, and recycling plastic waste.

 The necessity of using a new product in the mixture as a sintering additive is due to the following. The mechanism of the chemical interaction of the pecky product with polymers is concluded in the process of polycondensation of aliphatic and aromatic structures with the evolution of hydrogen, which ensures hydrogenation of this process and the production of a product with sintering properties. The sintering additive introduced into the charge has high adhesion to coal, it moistens the coal particles, contributing to the achievement of better plastic contact between the particles of the coal charge. In addition, an additional amount of hydrogenated mesophase is introduced into the charge with a sintering additive, due to which deeper polycondensation processes occur, which are associated with the formation of more stable crystalline carbon systems that give strong coke.

 Example. The crushed coals were mixed in the ratio, wt.%: Gas-fatty (GF) - 15, fatty (G) - 22, slightly coking coking (KS) - 37, sintering additive - 5% and thin-caking (OS) - the rest, high-quality the characteristics of which are presented in table 1.

Pre-prepared sintering additive. First, a pitch-like product was obtained (Patent RU 2181746 IPC 7 C 10 G 1/04, 1/06, 2002). Then, plastic waste ground to a particle size of 1-10 mm (polyethylene terephthalate) in a ratio of 1: 0.15 was added to the obtained peaky product of uniform composition and heated for 1.0 h at a temperature of 300 ^° C. After cooling to ambient temperature, the additive was ground to fineness 0-3 mm. The resulting additive had an ash content of 3.6%, the yield of volatiles was 29.7%, it was easily crushed and was uniform in composition. It was mixed with a coal charge and coked in laboratory conditions according to GOST 9521-74. The mixture, weighing 2 kg, was loaded into a coking box, placed in a laboratory furnace heated to 1000 ^{o C.} The coke oven was heated at 650 ^{° C.} at a rate of 2 ^{° C.} per minute until a temperature of 950 ^{° C. was} established in the center of the coking mass. The resulting coke had the following quality indicators,%: mechanical strength (P25) -95.5; abrasion (P10) -4.0; structural strength (Ps) -86.7.

 The test results of cokes of various compositions of the coal charge are summarized in table 2. Studies have confirmed that cokes obtained from coal mixtures composed of components, the amount of which is taken within the claimed limits, have increased mechanical strength and reduced abrasion. Changing the content of the charge components beyond the claimed limits is undesirable, because characteristics of coke are worse.

 The proposed mixture is applicable in the coke industry for the production of metallurgical coke.

Claims (1)

The mixture for producing metallurgical coke containing fatty, lean-sintering coals and a sintering additive, characterized in that it additionally contains gas-fatty, coke low-sintering coals, and the sintering additive is obtained by mixing a pitch-like product with plastic waste in a ratio of 1: 0.1- 0.2, heating the mixture to 300-350 ° C for 0.5-1.0 hours in the following ratio of components, wt.%: Gas-fat coals 15-20 Fat coals 20-30 Coking low-sintering coals 20-40 Sintering additive 3-6 Sintered coals Else

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