RU2378320C1 - Method of receiving pitch coke - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to methods of receiving of pitch coke - raw materials for manufacturing of electrode products with usage of carbon-bearing components, which can be used in by-product-coking industry, and the received by this method "raw" coke - in electrode industry in the capacity of raw materials for manufacturing of graphitised, bake electrode products, and also anode mass. Method of pitch coke receiving includes mixing of medium-temperature coal-tar asphalt with carbon-bearing thin-grinned component with following coking at temperature up to 500°C, herewith into raw materials of coking in the capacity of thin-grinned component there are introduced carbon-bearing graphitised or baked carbonic dusty wastes of electrode manufacturing at following ratio of components, wt %: carbon-bearing wastes - 10.1-30; carboniferous pitch- the rest, furthermore, introduction of dusty wastes is implemented at loading of raw materials into coking furnace.

EFFECT: increasing of yield of pitch coke with simultaneous utilisation of carbon-bearing dusty wastes.

6 ex, 4 tbl

Description

The invention relates to the field of metallurgy, in particular to methods for producing pitch coke, a raw material for the production of electrode products using carbon-containing components, which can be used in the coke industry, and raw coke obtained in this way in the electrode industry as a raw material for the production of graphite calcined electrode products, as well as the anode mass.

A known method of producing pitch electrode coke at a temperature of 1000-1100 ° C from high-temperature pitch (HTP) with a softening temperature of 135-150 ° C without the introduction of fillers (Privalov V.B. Coal tar pitch / VB Privalov, M.A. Stepanenko . - M.: Metallurgy, 1981, 208 p.). The coke yield is 65-69%. In turn, high-temperature pitch is a product of heat treatment of medium-temperature pitch (STP). At the same time, the output of HTP from STP is 84.6-88.6%, that is, the yield of coke proper from 1 t of STP by this technology is 550-610 kg / t. In addition, the known method involves an additional technological operation of obtaining high-temperature pitch; coking temperature 1000-1100 ° С.

A known method of producing crude pitch coke (ibid., P. 159) at a coking temperature of 475-515 ° C from high-temperature pitch. The coke yield is 680-750 kg / t.

A known method of producing pitch coke with the introduction of powder fillers (pitch coke, wood coke, natural graphite) in an amount of 20-90% (Veselovsky B.C. Coal and graphite structural materials / B.C. Veselovsky. - M .: Nauka, 1966, 226 S.). The total yield of coke is in the range of 49.5-67.4%. The disadvantage of this method is that with the introduction of powder fillers in an amount of 20-30%, the coke yield is 49.5-55.9%, which, in terms of 1 ton of the original pitch, is 619-798 kg / t. The maximum coking temperature is 750 ° C. The authors noted that pitch coke on the surface of graphite powder was obtained less durable.

As a prototype adopted a method of producing raw pitch coke and isotropic carbon material of high density. As raw materials for the production of pitch coke (PC), coal tar pitch is used, which has been filtered or centrifuged in order to remove substances insoluble in quinoline, to a residual content of not more than 0.1%. The pitch prepared in this way is kneaded with finely divided carbon powder (for example, graphite) or soot at a flow rate of not more than 10 parts by weight, and 100 parts by weight of pitch. The mixture is subjected to delayed coking at a temperature of 420-500 ° C, obtaining crude pitch coke with a yield of volatiles of 5-25%. To produce carbonaceous material (UM), crude PC is crushed, molded, and calcined at an increase in temperature to 1100 ° С at a rate of 0.05 ° С / min, after which it is subjected to graphitization at a temperature increase of 10 ° С / min (JP 36-218281, IPC СВВ 31/00, published on March 8, 1990. “Production of raw pitch coke and high-density carbon isotropic material.” Mukai Koichiro).

This method requires a special additional operation of refining pitch from quinoline insoluble substances. Medium-temperature coal tar pitch contains up to 12% of the substances insoluble in quinoline (Fialkov A.S. Formation of the structure and properties of carbon-graphite materials / A.S. Fialkov. - M .: Metallurgy, 1965, 288 p.). That is, refining up to 0.1% is accompanied by a total weight loss of up to 11.9%, which cannot be compensated by the introduction of 10% additives of solid carbon-containing graphite or carbon black. Further, losses during coking of refined pitch according to the data given in the work (Veselovsky B.C. Coal and graphite structural materials / B.C. Veselovsky. - M .: Nauka, 1966, 226 pp.), 20.5% more than unrefined. In terms of 1 ton of the initial STP, the yield of crude pitch coke will be 396 kg / t.

The objective of the invention is to increase the yield of pitch coke with the simultaneous disposal of carbon-containing dust waste.

To solve the problem in a method for the production of pitch coke, comprising mixing medium-temperature coal tar pitch with a carbon-containing finely ground component, followed by coking at temperatures up to 500 ° C, according to the invention, carbon-containing graphitized or calcined coal-based coal dust is introduced into the coking feed as a finely ground component during the following electrode waste the ratio of components, wt.%:

- carbon waste 10.1-30 - coal tar pitch rest

in addition, the introduction of dust waste is carried out when loading raw materials into a coking oven.

Carbon-containing wastes that are introduced into coal tar pitch (table 1) are dusts captured by electrostatic precipitators during graphite machining, and electrostatic dusts from mechanical treatment of calcined coal products made on the basis of thermoanthracite (table 2).

Table 1
Characteristics of coal tar pitch Name of indicator Indicator values Softening point, ° С 63-73 The yield of volatiles,% 53-63 The content of substances insoluble in quinoline,% 1-12 Ash content,% 0.1-0.3

table 2
Characterization of samples of carbon-containing electrostatic dust EF dust samples Ash content,% D _and g / cm ³ S, wt.% Mass fraction of particles less than 0.071 mm,% graphite 0.2-1.2 2.18-2.22 0.03-0.35 0.1-100 coal 0.5-2.0 1.70-1.95 0.30-0.55 0.1-100

An increase in the output of pitch electrode coke and at the same time utilization of UPR are achieved by combining coking raw materials and conducting the process under different conditions. The process is started by mixing medium-temperature coal tar pitch with a softening temperature of 65-73 ° C, instead of high-temperature with a softening temperature of 135-150 ° C, used in the technology of pitch coke and UPO with a mass ratio of STP: UPO 70,0-89,9: 10, 1 - 30%, then the mixture is subjected to coking at a temperature of 500 ± 10 ° C, get crude pitch coke with a yield of volatiles of 7.9-14.5%. The total yield of raw pitch coke per 1 ton of initial pitch is 770-1060 kg / t, against 680-750 t / t (V.E. Privalov, M.A. Stepanenko. Coal tar pitch. M., 1981, 208 S., tab. 43 on p. 127), at the same time 0.110-0.428 t / t of carbon-containing dust waste is disposed of.

The increased yield of crude pitch coke during coking of medium-temperature pitch with the introduction of dust particles is explained by the fact that dust particles, on the one hand, serve as local centers of coke formation, and, on the other hand, medium-temperature pitch, which is less viscous than high-temperature pitch, to a lesser extent prevents the passage of coxogens to the surface of dust particles. In addition, carbon-containing dust particles have a higher thermal conductivity than coal tar pitch. Therefore, they play the role of a heating substrate that promotes the coking of the pitch from the inside of the system. In this case, the thermal conductivity of graphite is greater than that of the calcined material, as a result of which there is some “overheating”, contributing to the decomposition of the pitch and a slight decrease in the yield of coke, but the resulting coke is characterized by a lower yield of volatiles than when using calcined dust.

With the introduction of dust in the claimed range (10.1-30.0%), the coke yield from the pitch itself ranges from 61-63%. An increase in dust of more than 30.0% reduces this indicator to 56-58%, and also does not contribute to the production of lump coke. That is, with an increase in the amount of dust filler, the thickness of the pitch layer decreases, the decomposition rate increases to values exceeding the rate of coke formation processes. The introduction of dust less than 10.1% leads to insufficient utilization of dusty waste from electrode production.

The content of components in the range of 10.1-30.0% ensures the achievement of the necessary technical result. When using dusts with a higher sulfur and ash content, it is not guaranteed to obtain electrode coke that meets the sulfur requirements (not more than 1.0% for the manufacture of graphite products; not more than 1.5% for the manufacture of anodes used to produce aluminum by electrolysis of cryolite Alumina melts). The characteristics of the components, coking conditions and pitch coke yield are presented in table 3.

The pitch coke obtained by the present method, the quality of low ash, low sulfur with the release of volatiles at the level of petroleum coke delayed coking (table 4), can be used as raw materials for graphite products according to the following technological scheme: calcination - crushing - classification - dosing - pressing.

Examples of specific implementation of the method

Example 1. Graphite dust captured by electrostatic precipitators during the machining of graphite products (actual density 2.18 g / cm ³ , ash content 0.5%, mass fraction of sulfur 0.35%) and coal tar pitch GOST 10200-83, grade A (temperature softening 66.5 ° C, ash 0.2%, mass fraction of sulfur 0.25%, volatiles yield 62.5%) in the amount of 20 and 80%, respectively, thoroughly mixed, then placed in an oven, heated to a temperature of 500 ° C . Duration of coking 5 hours. The coke yield was 86.3 tons per tonne of initial pitch (table 3). The quality of the pitch coke obtained meets the requirements for grade B pitch electrode coke (table 4).

Example 2. The method is carried out in the same way as in example 1, but carbon dust is used as a carbon-containing additive (actual density 1.71 g / cm ³ , ash content 2.0%, mass fraction of sulfur 0.55%) in an amount of 20 % and brand A coal tar pitch (softening temperature 66.5 ° C, ash content 0.2%, mass fraction of sulfur 0.25%, volatiles yield 62.5%). The coke yield was 69.1% (table 4).

Example 3. The method is carried out as in example 1, but the ratio of components (STP) and carbon-containing additives is 30-70%, graphite dust is used as a carbon-containing additive (actual density 2.22 g / cm ³ , ash 0.2 %, sulfur mass fraction 0.3%) and grade A coal tar pitch (softening temperature 73.0 ° C, ash content 0.3%, sulfur mass fraction 0.30%, volatiles yield 62.5%). The coke yield was 73.1% (table 4).

Example 4. The method is carried out in the same way as in example 1, but the ratio of the components (STP) and carbon-containing additives is 30-70%, carbon dust is used as a carbon-containing additive (actual density 1.95 g / cm, ash 1.2% , sulfur mass fraction 0.3%) and grade A coal tar pitch (softening temperature 73.0 ° C, ash content 0.3%, sulfur mass fraction 0.30%, volatiles yield 62.5%). The coke yield was 72.2% (table 4).

Example 5. The method is carried out in the same way as in example 1, but the ratio of components (STP) and carbon-containing additives is 10.1%, graphitized dust is used as a carbon-containing additive (actual density 2.20 g / cm ³ , ash 0.7 %, sulfur mass fraction 0.21%) and grade A coal tar pitch (softening temperature 70.3 ° C, ash content 0.1%, sulfur mass fraction 0.20%, volatiles yield 62.5%). The coke yield was 66.3% (table 4).

Example 6. The method is carried out in the same way as in example 1, but the ratio of components (STP) and carbon-containing additives is 10.1%, carbon dust is used as a carbon-containing additive (actual density 1.83 g / cm ³ , ash content 0.5 %, sulfur mass fraction 0.42%) and brand A coal tar pitch (softening temperature 70.3 ° C, ash content 0.1%, sulfur mass fraction 0.20%, volatile matter yield 62.5%). The coke yield was 66.2% (table 4).

The implementation of the proposed method will increase the output of electrode coke per unit consumption of pitch, suitable in terms of quality characteristics for the production of graphite electrodes and other graphite products that require low-sulfur coke.

For this purpose, in Russia there is no production of low-sulfur coke.

In addition, the environmental problem of the disposal of carbon-containing waste from electrode production is being addressed; the number is reduced and the area of industrial landfills is reduced.

Table 4
The quality of electrode coke Coke Ash content,% Sulfur,% The yield of volatiles,% Norms, no more KPE-1 brand 0.30 0.30 0.8 ** KPI-2 0.30 0.70 0.8 KPI-3 0.50 0.70 0.8 KZ brand * 0.60 1.00 9.0 Example 1g 0.26 0.68 9.0 / 0.4 ** Example 2u 0.50 0.31 14.5 / 0.4 3G example 0.27 0.10 9.8 / 0.3 Example 4y 0.51 0.30 13.5 / 0.3 Example 5g 0.16 0.20 7.9 / 0.5 Example 6u 0.15 0.23 8.4 / 0.5 Prototype 5-25 / 0.5 Notes. * KZ - delayed coking coke (490-500 ° С) ** Volatiles yield after coking at 1000 ° С; in the numerator, the yield of volatiles from raw coke (500 ± 10 ° С), in the denominator, from calcined.

Claims (1)

A method for producing pitch coke, comprising mixing medium-temperature coal tar pitch with a carbon-containing finely ground component, followed by coking at temperatures up to 500 ° C, characterized in that carbon-containing graphitized or calcined coal dust components of the electrode production are introduced into the coking feed as a finely ground component in the following ratio wt.%:
carbon waste 10.1-30 coal tar pitch rest,
in addition, the introduction of dust waste is carried out when loading raw materials into a coking oven.