SU1036810A1 - Electrode composition for self-roasting electrodes of ore reducing furnaces - Google Patents

Description

00 o: i

00 The invention relates to metal, namely, to electrometallurgy of manganese ferroalloys and is intended for the manufacture of continuous self-burning electrodes from ore electrodes for electric furnaces. The known electrode mass of burning electrodes of electrical furnaces of the following composition, wt.%: Thermo anthracite. 30 Coal coal 25 However, during the operation of self-burning electrodes of ore-installation electric furnaces of large unit power using electrode masses said electrode composition after calcining is not always about possesses thermal properties which leads to chipping and delamination ra bochego end and associated with the just m furnaces. The electrode mass of 2J self-burning electrodes of the composition is also known, wt.%: Thermoanthracite 25-50 K ameno nous. Cox25-50 Coal coal 18-28 However, changing the content of components also does not provide a significant improvement in the thermophysical properties, does not exclude fragments and chipping of working ends electrodes. The closest to the technical essence and the achieved effect of the present invention is the electrode mass of NW self-burning electrodes of ore-reducing electric furnaces of the following composition wt.%: Thermoanthracite 10-40 Cox10-40 Silicon carbide 25-50 Coal coal 18-28 Introduced specially made silicon carbide, by improving the properties of the mass, it is a highly abrasive material and, the passage through the paths of the technological scheme for the production of the electrode mass, with. leads to premature wear of technological equipment. The aim of the invention is to increase the electrical and thermal conductivity of the electrodes. This goal is achieved by the fact that the electrode mass for the self-firing electrodes of the electric furnaces, including thermoanthracite, coke and coal tar pitch, additionally contains a metal-slag mixture with the following; the ratio of components, wt.% 1 Thermoanthracite25-50 Coke .20-40 Slag metal mixture 1-30 Coal tar 20-28 It is also stipulated that the metal slag mixture has the following composition, wt.%: Manganese 10-75 Silicon 3-20 Iron 1-10 Carbon0, 05-5.0 Silicon Oxide 5-50 Calcium Oxide 1-15 Aluminum Oxide 0.1-10 Metalshyl component of the metal slag mixture in the composition of the electrode masses can be considered as acceptors of unpaired electrons. Proven as an inhibitor or trap of free radicals, the metal portion of the slag-metal mixture contributes to the concentration of the latter in the coking electrode mass. The decrease in the concentration of crystallization centers leads to the aggregation of aggregates (microcrystals J. Abruptly increasing the ability to graphitize electrode masses containing slag metal mixture, confirmed by the formation of a more perfect structure of the working end of the self-burning electrode. The presence of slag metal mixture in the composition of the electrode end in the active electrode environment, which reduces the oxidation of the working end of the electrode and reduce its consumption The presence of a slag-metal mixture in the composition of e.product masses also contributes to a decrease in the reactivity of the working end of the electrode in the active medium, which makes it possible to reduce the oxidisability of the working end of the electrode and to reduce its consumption.When used in the composition of the electrode mass for self-burning electrodes, the slag mixture During the formation of the electrode, crystallographic transformations occurring during graphitization are improved, thereby causing a decrease in the graphite formation temperature of the working end of the electrode. kind of. Consequently, the slag metal mixture in the composition of the electrode masses has a positive effect on heat and electrical conductivity, the nature of changes in the structure and porous structure of the carbon electrode block, and also has a passivating effect on the reactivity of the working end. Thus, the use of the cometary mixture in the composition of the electrode masses plays a very good important role in the operational durability of self-baking electrodes. The composition of the electrode mass using a slag-metal mixture which has a negligible abrasive ability, along with improving the properties of the electrode mass and the self-burning electrode, almost completely eliminates the wear and tear of the technological equipment that is inherent in the known mass with silicon carbide. For the manufacture of the electrode mass, the initial components are used. Thermoanthracite (IjXJCT 4794-75). Slag-metal mixture, seederct, -%: Mp 58; Si 5.7; Fe 2.5; C, 0.8; SiOj 10.4; CaO 2.1; AE203 0.75 and represented by a fraction of 0, 063 m including 0.005-0.015 mm 60%. Coke (GOST 18686-73). Medium temperature coal tar pitch with softening temperature of 65-70 s (GOST 10200-73). Electrode masses containing not less than 25% of thermoanthracite possess the highest physicomechanical characteristics. Increasing the content of thermoanthracite by more than 50% will entail a decrease in the mechanical strength of the working end of the electrode. The optimum coke content in the proposed composition of the electrode mass is 20-40%. A decrease in its amount of less than 20% will cause a deterioration in the mechanical properties of the electrode. With an increase of more than 40%, the thermal cost of the electrode will decrease. The content of the slag-metal mixture in the proposed composition of the electrode mass should be in the range of 1-30%. Reducing the amount to less than 1% does not significantly affect the properties of the electrode. Increasing the proportion of slag-meteor mixture over 30% is not. leads to a further change in the properties of the electrode masses. One of the factors in ensuring the operational durability of self-baking electrodes is the optimum content of the binder in the composition of the electrode masses. It has been established that the binder content should be 20-28%. The electrode mass with the content of coal tar pitch more than 28% requires a significant expenditure of energy for coking the electrode, does not ensure the optimum level and position of the coking zone. Reducing the amount of pitch to less than 20% does not provide a strong bond between the components, it dramatically reduces the physicomechanical properties of the self-burning electrodes. Example. Preparation of the electrode mass. The solid carbon components are calcined at 1200-1300 ° C, after which they and the slag metal mixture are crushed, followed by sieving on drum screens or screens. The prepared materials are metered by the types of raw materials and granulometric composition in accordance with this mass formulation, and then, with bondage, are fed to the mixer where they are mixed for 3-5 minutes at 130-180 ° C, after which the mass is poured into molds to obtain briquettes loaded into electrode self-firing. A comparative analysis of the proposed mass with the known. Manufactured electrode masses, the composition of which is given in table. 1. Table 1

Thermoanthracite

50

thirty

25 20

29

cream1 20

25

37

25

26

thirty

20.0 20

40

thirty

25

15 20

15 28

25

30 20

24

Each formulation is prepared separately in a 400-liter steam-heated mixer at 135-140 ° C and a stirring time of 50 minutes. The finished carbon electrode mass is formed in dry metal forms in a briquette weighing 2-3 kg. The mass produced is placed in a metal casing with a diameter of 60 mm and a height of 300 NJM and heated in a furnace. Thermal conductivity, W / m 2.4 2.5 4.7 Specific electrical resistance, Ω.mm / m2 95.4 95.2 86.1

As a result of the tests, it was established 30 that using the proposed electronic mass allows increasing the electrical and thermal conductivity of the electrodes by 15–20%, expanding the raw material base for the production of electrodes in 35

5еэ of air access up to 900 С with a speed of 100 ° С / h with an exposure at a final temperature of 3 hours. The obtained annealed samples of experimental carbon masses are subjected to technological testing according to TU-48-12-8-79.

The test results are presented in Table. 2

Table 2

by introducing into the composition of the mass of slag – mash-up mixture.

When using the invention on self-baking electrodes of electric furnaces, the annual economic effect will be about 350 thousand rubles. 5.0 4.3 4.0 4.8 84.2 87.9 92.4 84.8

Claims (1)

3. USSR Copyright Certificate No. 783366, cl. S 25 V 11/12, 1979. ι 1. ELECTRODE MASS FOR SELF-BURNING ELECTRODES. ORE REDUCING ELECTRIC FURNACES, including thermoanthracite, coke and coal tar pitch, characterized in that, in order to increase the electric and thermal conductivity of the electrodes, it additionally contains ! slag-metal mixture when the total ratio of components, wt.%: Thermoanthracite 25-50 Coke 20-40 Slag metal sky. mix 1-30 Stone coal pitch 20-28 2. The mass according to claim 1, excellent I am with me that slag the mixture has next composition BUT the weight.%: Manganese 10-75 | «| Silicon 3-20 from Iron 1-10 from Carbon 0.05-5.0 from Silica 5-50 one Calcium oxide 1-15 b * * - * Aluminium oxide 0,1-10 coal pitch, additionally contains a slag metal mixture with the following i ratio of components, wt.% 1