SU704896A1 - Carbon mass for self-roasting electrodes - Google Patents

Description

(54) CARBON MASS FOR SA SUSTAINED ELECTRODES

iiOTX voltages, which, as a rule, lead to the formation of microtomb in a block of self-burning electrode.

The aim of the invention is to improve the physicomechanical properties of the carbon mass and the self-baking floor / electrode and their reduction properties.

This goal is achieved by the fact that the proposed carbon mass includes, wt%;

Semi-coke 20-45

Coal tar pitch (with softening temperature of 65-70 ° C) 20-28 Thermo anthracite The remaining Difference of the proposed mass lies in the fact that it contains approximately half the coke and coke in the above ratio of components. . , / ;;, ... ,,;. ,,

The choice of semi-coke as a component of the carbon electrical compartment is due to the fact that in the semi-coke, the processes of primary shrinkage and heat treatment proceed together with the adjacent KaMeHHojtoj bHbiM pitch. The 5KID binder migrates in the semi-coke, their shrinkage and pyrolysis of volatile substances are combined, which causes the formation of the carbon block of the electroplate and a homogeneous pseudo-heterogeneous coke structure with a uniform distribution of thermal anthracite particles in it. The JtHNttnieCKMe connection is formed between the semi-coke and binder grains. This practically eliminates the formation of cracks, which occur in the practice of self-enrichment electrodrb when used in the composition of carbon electrode masses as a solid coal coke.

When ishrlzovaya semi-cokes in the composition

carbon electrode mass during firing

Electrode, along with: irolysis binder

Buzzp. - The processes of thermal decomposition of volatile substances contained in by Kokce will occur, as a result of which free carbon will be additionally deposited in the pores of the corner of the self-igniting electrode. This will cause a decrease in the porosity of the electrode, a significant improvement in quality, since free carbon has a large solid- and high electrical and thermal conductivity,. contributes to increased operational durability of the electrode.

The boundary values of the composition, carbon electrode masses are determined by the quality of the initial components, as well as by the mass assignments; Carbon masses containing 30–60% thermoanthraeart possess the best physicomechanical properties.

Increasing the content of thermoanthracite by more than 60% leads to a decrease in the mechanical strength of the self-burning electrode, and decrease its fraction below. 30% cause by pysen thermal stability. The optimum content of the semi-coke, in superior carbon composition, is 20-45%. Reducing the amount of semi-coke below 20% will reduce the mechanical properties of the electrode, increase the likelihood of microcracks in the carbon block of the electrode, and prevent the pseudohomogeneous coke-hygroscopic structure with a uniform distribution of thermoanthracite in it, which ensures high thermophysical properties. Increasing the amount of semi-coke by more than 45% is impractical, since this will cause a decrease in the thermal resistance of the electrode, increasing its porosity, which, with a constant optimal binder content, will lead to an increase in electrical resistivity and a decrease in thermal conductivity.

One of the main factors determining the quality of the electrode is the optimal binder content in the composition of the electrode mass of 20-28 wt.%. Otherwise, the strength characteristics of the electrode drop sharply. Mass, with contain thaw coal tar pitch more. 28% requires a significant amount of energy for coking, which leads to the destruction of the electrode on the coked part. A reduction in the fraction of a pitch of less than 20% causes a decrease in the physicomechanical properties of the electrode.

The preparation of a carbon electrode mass of the indicated component composition is carried out as follows. The solid components are crushed thermoanthracite and semi-coke (coal, oil, pitch, etc.) are metered and moved in a steam-heated screw preheaters of the mixer at 130- where they are loaded simultaneously .;

Then the mixed semi-coke and thermoanthracite enter the mixer, which simultaneously serves the appropriate amount of the original coal tar pitch and mix them thoroughly. In order to impart a mass of marketable appearance, it comes from the mixer to the molding machine, where it is molded into briquettes and conveyed to the boxes in a conveyor belt, in which they are delivered to the smelter to be loaded into the electrodes.

For the preparation of the carbon electrode mass, the initial components are used:

Thermoanthracite containing

in accordance with GOST 479475

Ash not more than 5

Moisture0,3

Sulfur not more than 1.9 Volatile not more than Specific resistivity not more than 2000 cm. More Density, d East. G, 85 g / cm Fractions, mm content,% 20 .. 10 30-40 Semi-coke, obtained at a final coking rate of 600-800 ° C, containing: Volatiles up to 10% Density, -d source1.75-1.86 g / cm Porosity 55-67% Fractions, mm0,07 not less - Medium-temperature coal tar pitch with a softening temperature of 63-70 ° C. In tab. Figure 1 shows the compositions of the carbon masses of the prototype and of the invention (for edge and optimum component content). The prepared mass was placed in a metal casing with a diameter of 60 mm and a height of 300 mm and burned in a furnace up to 900 ° C at a rate of 100 ° C / h with an exposure at a final temperature of 3 hours. In tab. Table 2 shows the results of burned carbon masses in turn and according to the proposed composition (TU 48-12-8-7 As a result of tests, it was found that the use of carbon masses according to the invention of SUN allows to increase its physics and mechanical characteristics in comparison with the prototype; So, mechanical tensile strength increases by 13–20%. Porosity and fluidity decrease by 25–30%. Testing the work of a self-burning electrode with a diameter of 100 mm, into which the carbonaceous electrode weight of the claimed composition was loaded, There was a single-phase arc electric furnace with a power of 140 KW during smelting of coal margins. To compare this furnace, the work on self-firing 1Sh1hs electrodes, into which the semi-coke-free mass was loaded, was tested using a prototype.With each electrode, up to 300 kg of charge was melted. showed the results of the operation of the self-burning electrode using an electrode mass containing semi-coke, during the smelting of silico-manganese, a more stable electrical and technological mode of the process was observed compared to the operation of the electric birth on the usual carbon mass. Along with an improvement in the operational durability of self-baking electrodes, in the Inventions of the present invention, a reduction in the cost of one ton of carbon monoxide by 10-15 p. due to the use of semi-coke instead of expensive and deo4) iced coke.

Thermoanthracite

Semi-coke (coal)

Coke (coal)

Binder-coal tar pitch

Table 1

thirty

45

60

40

45 o

20 o

32 o

About 30

9

25

23

20

Formula and 3 about b p e t ё n and

1. Carbon mass for self-firing electric rods, including juicer curvature pectonous, about 1 and 2, which, in order to improve the physical-mechanical properties of the carbon lyraccbi, self-calcined carbon electrc-176 semi-coke with the following components, wt%:

704896

8 Table 2

Semi-coke 20-45

Coal tar 20-28

ThermoanthraciteEmost

Sources of information taken into account in the examination

1. Auth., Over. N 358797, cl. H 05 B 7/09, for owner. 12.f71.

2. MI Gasik Self-igniting electrodes of ore-smelting electric furnaces. Moscow, Metallurgists, 1976, p. 386 (prototype).