RU2337895C2 - Method of natural clayey suspension manufacturing for electrode material production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention concerns method of binding receiving for production of electrode materials which are used for aluminium and ferrous metal manufacturing. Method of binding manufacturing provides preliminary pitch milling, its blending in dry condition with thermo-expanded graphite with receiving of composition containing 2.0-8.0 wt % of thermo-expanded graphite and pitch - the rest, further heating of received composition till 180-360°C with holding at heating temperature.

EFFECT: improving of binding operating characteristic, leading to rising of electrode materials electrical conductance, reduction of power inputs and improving of environmental conditions of production, in which there are used electrode materials with applied binding.

2 cl, 1 dwg, 4 tbl, 3 ex

Description

The level of technology.

The invention relates to carbon-containing electrode materials, in particular to a technology for producing a binder for the production of electrode materials. The level of technology.

Improving the characteristics of electrode materials, such as the anode mass, is carried out in two directions: 1) by making various additives to the materials; 2) by directly modifying the binder itself, which is currently mainly used for coal tar pitch with various softening points.

It is known that introducing elemental sulfur, aromatic nitro and chlorine compounds, other synthetic and natural binders, for example, phenol-formaldehyde resins, bitumen, etc. into the pitch as modifying additives. has a significant effect on the properties of coal tar pitch (see A. S. Fialkov "Carbon-interlayer compounds and composites based on it." M., 1997).

So, for example, from the patent RU 2080418, issued for “Method for the production of anode mass” it is known to use coal tar pitch with the addition of oil pitch as a binder in a ratio of 19: 1 to 2: 1, which reduces the emission of carcinogens.

For the same purpose, pitch distillate may be added as an additive: a plasticizing agent heated to 50 ° C is introduced into the coal tar melted at 140 ° C in a predetermined ratio of components, after which the mixture is thoroughly mixed (SU 1520899, 1987).

The closest binder for the manufacture of electrode products is the binder disclosed in patent RU 2088694 (see example 1). This binder contains coal tar pitch and an additive of activated carbon as an sorbent in an amount of 3-5% (to the weight of the pitch) with an average pore size of 2.6-3.7 nm.

A method of manufacturing a binder involves co-heating the pitch and adsorbent (activated carbon) in isothermal mode to 175-290 ° C and holding at this temperature for 1.0-2.0 hours

As follows from the materials of the cited patent, such an additive leads to a decrease in emissions of polyaromatic hydrocarbons (PAHs).

However, the disadvantages of this known technical solution include the deterioration of the physicomechanical characteristics of electrode products due to the introduction of an unplastic adsorbent additive, insufficient reduction of harmful emissions (including PAHs), and also this additive does not have a noticeable effect on electrical resistance.

Disclosure of the invention.

The objective of the invention is to improve the operational characteristics of the binder, leading to an increase in the electrical conductivity of the electrode materials, an increase in coke residue (CO), a reduction in energy consumption and an improvement in the environmental conditions of production in which electrode materials with the claimed binder are used.

The problem is solved by the method of manufacturing this binder for electrode materials, in accordance with which the pitch is ground, mixed in the dry state with thermally expanded graphite to obtain a mixture containing thermally expanded graphite 2.0-8.0 wt.% And coal tar pitch - the rest, followed by heating of the resulting mixture up to 180-360 ° C with exposure at heating temperature.

In particular embodiments of the invention, thermally expanded graphite is pretreated with a plasticizer.

Under the electrode materials in the present invention refers to a wide range of materials used, in particular, in the production of aluminum: the anode masses in the production of aluminum by the Soderberg method, materials for baked anodes, materials for cathode blocks, as well as materials for the pin anode mass. In addition, the proposed binder can be used for the manufacture of electrode materials for electrodes used in the manufacture of steel, etc.

Under the plasticizer in the present invention is meant a substance that increases the ductility and (or) the elasticity of the binder, reducing its viscosity. As plasticizers, petroleum products can be used, for example, petroleum oils; processing products of coal and wood materials, for example, coumarone-indene resins, rosin; epoxidized vegetable oils and others, preferably with a boiling point in excess of 150 ° C.

TEG obtained by the acid-free method is understood as TEG with a low sulfur content (0.1-0.3%) obtained by chemical or electrochemical treatment of graphite without the use of sulfuric acid, for example, TEG obtained by chemical or electrochemical treatment in nitric acid.

The essence of the invention lies in the fact that the binder of electrode materials, consisting of coal tar pitch and TEG (synonym - penografite (PG)) in an amount of 2-8% by weight can significantly improve the operational characteristics of the materials themselves (anode mass, pin anode mass, electrodes for ferrous metals, etc.).

Thermally expanded graphite additives can increase the electrical conductivity of electrode materials, as well as increase the KO. An increase in KO, in turn, leads to a decrease in emissions of volatile gases, which ultimately will improve the environmental conditions of production.

Moreover, an increase in the content of TEG> 8% does not lead to a further increase in the characteristics and increases the cost of the binder, and hence the electrode material.

A decrease in the amount of TWG of less than 2% is also undesirable, because in this case, the percolation effect is not formed and the electrically conductive frame is not created from the TEG particles, which are able to firmly adhere to each other due to the developed surface and a peculiar microstructure.

In addition, the introduction of an additive TRH may have an additional advantage, because TWG has a high adsorption capacity and can reduce the yield of PAHs.

As pitch can be used coal tar pitch grades A, B, B ₁ and C in accordance with GOST 10200-83.

To improve the mixing conditions of high-temperature pitch and TEG, the possibility of more uniform distribution of the modifying additive and to reduce the viscosity of the pitch, it is desirable to pre-treat the TEG with a plasticizer, which is desirable to use oils with a boiling point of more than 150 ° C (for example, absorption oil, etc.).

The amount of plasticizer does not exceed 15.0 wt.%.

To improve the quality of the binder pitch, it is necessary to grind it beforehand, which will allow for a uniform distribution of TEG having a low bulk density in the composition of the binder.

The implementation of the invention.

Example 1

To study the effect of TEG additives on the electrical conductive properties of the pitch, the initial grade B high-temperature sands obtained from JSC Ispat Karmet, Karaganda, the Republic of Kazakhstan were used.

The characteristics of the initial high-temperature pitch are shown in table 1.

For the study of the conductive properties of the pitch, 2 types of penografite (ТРГ1 and ТРГ7) with a nitrate background and waste products from the production of graphite foil (ТРГ27) were used as TRG additives. The characteristics of the carbon fillers used are shown in table 2.

To obtain samples of coal tar pitch / TEG, the pitch was pre-ground to a particle size of 100-1000 microns.

By mechanical mixing of pitch and TEG in an electric mixer, mixtures were obtained in which the mass fraction of TEG was 1-8 wt.%. The resulting mixture was kept at a temperature of from 180 to 360 ° C for 1-20 hours.

The conductivity (resistivity) was measured by a 4-contact method at room temperature (22 ° C). Samples for measuring the resistivity were prepared in the form of bars with a cross section of 5 × 5 mm and a length of 15 mm.

The conductivity results are presented in table 3.

As follows from this table, when the content of TEG is 1% (experimental compositions 1, 2, 3, 4, 5, 6), the percolation effect is not yet noticeable, and the increase in electrical conductivity begins with the content of TEG 2% by weight.

The addition of a plasticizer (compositions 9, 15, 21 and 27) allows to reduce the viscosity of the binder, practically without reducing its electrical conductivity.

Example 2

To study the effect of TRH additives on increasing the coke residue (KO) of the pitch, 2 types of penografite (TRG1 and TRG7) were used (see Table 2). A binder was obtained in the same manner as in Example 1.

To determine the CO, the method of two crucibles was used.

The results of the influence of the introduction of TWG on the coke residue are shown in figure 1.

Example 3

To determine the effect of the introduction of TEG in the binder on reducing the amount of PAHs, a binder was prepared in accordance with Example 1, only the grinding of the ground pitch and TEG was mixed mechanically and by the “drunken barrel” method.

To prepare the mixture, we used TRG with a bulk density of 2 g / l, foamed in air at 900 ° C (grade OP 96).

The experiments were carried out according to the following procedure. The analyzed sample weighing about 1 gram was weighed and subjected to sublimation in a tube under vacuum at a temperature of 600 ° C. The sample was removed from the tube and weighed. Sublimation products collected in the cold zone of the tube were dissolved in toluene and then analyzed by gas chromatography and mass spectrometry.

The results of the analysis are shown in table 4. As can be seen, the amount of high molecular weight PAHs released (starting with anthracene) in the case of using a mixture of coal tar pitch with penografit significantly decreases. It is extremely important that when using penografit and coal tar pitch as a binder, the release of benzo [a] pyrene is reduced by 10%

As follows from tables 3 and 4 and the graph shown in the drawing, the introduction of the claimed amounts of TEG into the coal tar pitch can increase the binder's electrical conductivity, increase its coke residue and reduce the amount of PAHs in the binder, which will ultimately reduce energy costs and improve the environmental conditions of production, in which use electrode materials with the claimed binder.

To obtain the anode mass, a metered amount of crushed binder with petroleum coke was mixed:

1. 20 wt.% Binder (composition 8 of table 3) with 80 wt.% Petroleum coke (main anode mass).

2. 25 wt.% Binder (composition 40 of table 3) with 75 wt.% Petroleum coke (main anode mass).

3. 30 wt.% Binder (composition 22 of table 3) with 70 wt.% Petroleum coke (underpinning anode mass).

4. 35 wt.% Binder (composition 6 of table 3) with 65 wt.% Petroleum coke (pin anode mass).

To assess the quality of the anode mass in accordance with TU 48-5-80-86 “Carbon anode mass”, the anode mass was fired in an iron casing by heating the mass at a speed of 100 ° C / h to 1000 ° C and holding at this temperature for 4 hours. Then, samples were cut out from the lower fully burnt part of the mass to measure electrical resistance.

Measurements of the electrical resistivity of the obtained anode masses (main and pin) showed that their conductivity is 1.2-1.5 times higher than the conductivity of similar anode masses with a typical binder.

Table 1 PITCH Coal electrode pitch brand B Softening temperature (by the method of “Rings and Balls”), ° С 110 Mass fraction of insoluble substances in toluene,% 31 Mass fraction of insoluble substances in quinoline,% 5 Ash content,% 0.2 Coke residue, weight% 57 The yield of volatiles, weight% 57 Appearance Molten

table 2 TRG1 TRG7 TRG27 Bulk density (d _us. ), G / l one 7 27

Table 3 The content of TWG, wt.% Electrical resistivity, μOhm · m pitch-TRG27v
T = 180 ° C pitch-TRG27v
T = 360 ° C pitch-TRG ¹
T = 180 ° C pitch-TRG1a
T = 360 ° C pitch-TRG7v
T = 180 ° C pitch-TRG7v
T = 360 ° C one 2.710 ⁶ (1) ² 1.7110 ⁶ (2) 4.52 · 10 ⁶ (3) 3.37 · 10 ⁶ (4) 3.2 · 10 ⁶ (5) 1.49-10 ⁶ (6) 2 2310 ⁴ (7) 3510 ⁴ (8) 3510 ⁴ (9) 2510 ⁴ (10) 3810 ⁴ (11) 3910 ⁴ (12) 3 1210 ⁴ (13) 6210 ³ (14) 2410 ⁴ (15) 15 x 10 ⁴ (16) 20 x 10 ⁴ (17) 16 10 ⁴ (18) four 1210 ⁴ (19) 8110 ³ (20) 2010 ⁴ (21) 17 10 ⁴ (22) 1510 ⁴ (23) 11 10 ⁴ (24) 5 3210 ³ (25) 6410 ³ (26) 18.510 ⁴ (27) 1510 ⁴ (28) 8010 ³ (29) 9010 ³ (30) 6 57 10 ³ (31) 7110 ³ (32) - - 90 10 ³ (33) 9010 ³ (34) 7 58 10 ³ (35) 7410 ³ (36) - - 9010 ³ (37) 90 10 ³ (38) 8 9110 ³ (39) 7010 ³ (40) - - - - ¹ With additives up to 15 wt.% Plasticizer - absorption oil
² In parentheses, the conditional composition number of the binder

Claims (2)

1. A method of manufacturing a binder for electrode materials, characterized in that the pitch is crushed, mixed in the dry state with thermally expanded graphite to obtain a mixture containing 2.0-8.0 wt.% Thermally expanded graphite and the rest is rest, followed by heating the resulting mixture up to 180-360 ° C with exposure at heating temperature. 2. The method according to claim 1, characterized in that the thermally expanded graphite is pre-treated with a plasticizer.