RU2613501C1 - Charge for metallurgical coke production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: charge for metallurgical coke production from carbonaceous materials containing heavy sulphurous oil refining residues in the amount not less than 10 % contains oil shale from 0.1 to 30 % by weight of the charge. As heavy sulphurous oil refining residues, char oil is used with volatile substances output in the amount of 14-25 %.

EFFECT: coke production simplification, reduced consumption of coke obtained by coking material having a high sulfur content, with simultaneous ensuring of the required coke quality and maximum neutralizing of sulfur impact in coking.

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Description

The invention relates to the coke industry, in particular to a technology for the production of metallurgical coke from a mixture including oil refining products.

The quality of metallurgical coke is determined mainly by the quality of the initial charge and, to a lesser extent, by coking conditions. In this regard, the main attention in solving the problem of improving the quality of coke at coke plants is paid to optimizing the composition of the coal charge.

In order to improve some indicators of the quality of metallurgical coke (reducing reactivity and ash content), small amounts of coal charge additives are practiced, in particular petroleum coke fines (“Metallurgical coke from charges involving petroleum coke and its behavior in blast furnaces.” - Coke and Chemistry , 1967, No. 9, p. 52). However, petrocoke fines are characterized by low coking properties and at the same time a high sulfur content (up to 6-8%). This complicates the use of coke in industry. The presence of sulfur in the composition of metallurgical coke, which is mainly represented in organic form, significantly reduces the value of this raw material, since it is converted to metal by 70-75% during the metallurgical process.

Another way to improve the quality indicators of metallurgical coke and reduce its cost is to include coking additives in the coal mixture (RF patent No. 2355729). The disadvantage of this method is the negative effect of the increased sulfur content, passing into metallurgical coke.

A known method of neutralizing the influence of sulfur in the production of coke components (RF patent No. 2451056), selected for the prototype. In accordance with this method, which includes introducing a reagent — alkaline-earth metal oxide, or alkaline-earth metal carbonate, or alkaline-earth metal hydroxide into heavy sulfur residues of oil refining, preheating the carbon-containing feed to a temperature of 150-500 ° C, and subsequent coking while the amount of reagent is 0.1-1.7% for each percentage of sulfur content in heavy refinery residues.

The disadvantage of this method is the complexity of the production technology of metallurgical coke (coking additives), the use of expensive reagents (oxides or carbonates of alkaline earth metals). In addition, the decrease in sulfur content in this way reduces the cokeability of the resulting product.

The technical result achieved by the claimed invention is to simplify the production of coke, reducing the consumption of coke obtained by coking a material having a high sulfur content, while ensuring the required quality of coke and maximally neutralizing the effect of sulfur during coking.

The claimed technical result is achieved in that in a charge for producing metallurgical coke from carbon-containing materials with a content of heavy sulfur residues of oil refining in an amount of at least 10%, according to the invention contains oil shale in an amount of from 0.1 to 30% by weight of the charge, as heavy Sulfur refinery residues used petroleum coke with a yield of volatiles in the amount of 14-25%.

It is known that heavy sulphurous refining residues (tar, asphalt, visbreaking residues, petroleum coke, etc.) contain sulfur in an amount greater than is permissible, for example, when smelting cast iron in blast furnaces (more than 0.8%).

The choice of oil shale as an additive to the charge for coking is determined by the fact that when the content of its combustible part is 15-40%, the content of mineral components is from 60 to 85%; the main component of the mineral part (over 60%) is the carbonates of Ca (calcium) and Mg (magnesium). Carbonates of alkaline-earth metals (metals of the main subgroup of the second group of the periodic table Mg-Ra) are sulfur inhibitors, i.e. substances that neutralize the influence of sulfur ("Iron metallurgy", -M.: ed. Metallurgy, 1989, pp. 232-233; AD Gottlieb. "Blast furnace process", ed. Metallurgy, 1966, p. 316-317; EF Wegman. “A quick reference of a domain manager”, -M .: Metallurgy, 1981, p. 195 - requirements for cast iron; pages 197-198 - the main requirements for slag).

The nature of the reactions of oxides of alkaline earth metals with sulfur proceeds according to the formulas:

CaCO ₃ = CaO + CO ₂

CaO + C + S = CaS + CO

According to the above formulas, during coking, when the temperature rises to 900-1050 ° C, a stable chemical compound of sulfur with an alkaline-earth metal is formed, which is highly stable in pyrometallurgical processes and completely transforms into slag. By converting organic sulfur to a stable mineral compound, the amount of sulfur compounds in coke oven gas will decrease. This leads to a decrease in sulfur content in coking chemicals and in air emissions.

It is known to use oil (carbonate shale) for desulfurization (desulfurization) of oil and oil products (USSR Author's Certificate No. 257661). From this source it is known that the mineral part of oil shale contains carbonates of alkaline-earth metals (mainly calcium). When interacting under conditions of elevated temperatures of oil or oil products with oil shale, sulfur compounds contained in oil or oil products decompose, sulfur is bound by calcium oxide, which is formed upon decomposition of the mineral part of oil shale, and then is removed.

Also known are methods of reducing the formation of sulfur oxides in the combustion products during the burning of sour coals (USSR author's certificate No. 544826, RF patent No. 2079543) by ensuring the interaction of sulfur oxides formed during the burning of coals with oil shale. Limestones contained in oil shale decompose in the course of combustion with the release of calcium and magnesium oxides, which ensure the binding of sulfur oxides.

However, the introduction of oil shale into the coking charge in order to obtain metallurgical coke is not obvious.

It is known that metallurgical coke contains ash (in an amount of up to 12-18%), which is mainly represented by a refractory component - silica, and which negatively affects the formation of slag regime of shaft furnaces, causing a violation of the gas-dynamic mode of their operation. The melting temperature of coke ash is 1520-1550 ° C, and a significant amount of thermal energy is spent on its melting. (Blast furnace production. Handbook. T. II, M.: Metallurgizdat, 1963. 643 p.). Accordingly, it is traditionally believed that increasing the ash content of coke affects its quality.

The addition of oil shale to a traditional coal charge for coking is impractical (rather even impossible) due to the high ash content of the shale (the mineral content of the shale is from 60 to 85%).

However, blends with a high content of low-ash oil refining products make it possible to introduce oil shale into the blend.

The inventive charge for producing metallurgical coke contains heavy sulfur residues of oil refining and oil shale. The amount of oil shale in the charge is from 0.1 to 30% by weight, and the amount of heavy sulphurous oil refining residues in the charge is from 10 to 100% of the starting carbon-containing materials.

The indicated limits for the content of heavy sulfur residues of oil refining are determined by the authors, taking into account the fact that, with the amount of sulfur residues of oil refining, the charge properties will approach the properties of coal blends containing a low amount of sulfur. In this case, the addition of oil shale will increase the ash content of coke. If the content of heavy sulphurous refinery residues in the charge is less than 100%, the rest of the charge is any known carbon-containing materials that are traditionally used in the charge for producing metallurgical coke.

The limits of oil shale content are determined taking into account the maximum possible sulfur content in the sulfur residues of oil refining.

The authors found that in the process of coking a charge containing heavy sulfur residues of oil refining and oil shale, sulfate compounds formed during heating of heavy sulfur residues of oil refining provide a decrease in the melting temperature of coke ash by an average of 3-6 ° C for each percentage of oil shale.

In addition, the melting temperature of oil shale ash (1250-1255 ° C) is lower than the melting temperature of coke ash (1520-1550 ° C) and sulfate compounds formed during the passivation of sulfur provide an additional reduction in the melting temperature of ash. Therefore, each percentage of the replacement of coke ash by shale ash provides an additional decrease in the melting point of the melt by 20-22 ° C. A decrease in the melting temperature of the ash leads to a decrease in the fuel consumption necessary for melting the ash. So, for example, in a standard cupola room with a specific coke consumption of 150 kg per ton of metal, a decrease in the melting temperature by 20 ° C will lead to a decrease in coke consumption by 2.5%.

Thus, when oil shale is added to a mixture to produce metallurgical coke, it exhibits well-known properties related to the ability of oil shale to neutralize the influence of sulfur contained in oil products, namely, by ensuring the interaction of sulfur oxides formed during heating of oil products with oil shale, in which the limestones contained in oil shale decompose during combustion with the release of calcium and magnesium oxides, which ensure the binding of sulfur oxides.

Simultaneously with the neutralization of sulfur contained in heavy sulfur residues of oil refining, oil shale in the composition of the mixture for producing metallurgical coke causes the presence of ash in the coke, the melting temperature of which is lower than the melting temperature of coke ash formed from the carbon-containing part of the charge. In addition, the replacement of a portion of the charge with oil shale in the presence of refinery residues in the charge does not lead to an increase in coke ash, since heavy refinery residues have a low ash content (up to 0.8%).

Thus, the replacement of part of the carbon-containing mixture containing heavy sulfur residues of oil refining, oil shale increases the efficiency of smelting by reducing the consumption of coke, and also expands the field of use of the inventive charge.

In addition, the method allows to utilize small fractions (screenings) of oil shale, which are currently waste products and are stored in dumps.

The present invention allows to reduce or completely eliminate the negative effects of sulfur in coke to reduce coke consumption, improve the slag mode of the melting unit by lowering the temperature range of the melting of charge components when using the invention in the metallurgical industry.

From 0.1 to 30% of crushed fuel (carbonate) shale is introduced into the coking charge. Such an amount of oil shale is enough to neutralize as much as possible sulfur contained in heavy sulphurous refinery residues.

A coking charge containing a heavy oil residue is mixed with crushed oil shale and then coked using conventional layered coking technology in coke ovens. In the process of coking, sulfur binds to a stable compound, for example CaS, passing from an organic state to a mineral one. The result is metallurgical coke with passivated sulfur. The resulting sulfur compounds reduce the melting temperature of coke ash by an average of 3-6 ° C for each additional percentage in its composition. In addition, each percent replacement of coke ash with oil shale ash provides an additional reduction in the melting temperature of the ash.

Thus, coke obtained from blends containing heavy refinery residues and oil shale is suitable for use as metallurgical in strength, ash and sulfur content. And by reducing the melting temperature of the ash, the consumption of such coke in metallurgy can be significantly reduced.

Examples of carrying out the invention

Example 1

The composition of the charge for coking:

- 90% petroleum semi-coke according to TU 0258-229-00190437-2008 (Ad = 0.4%, Vdaf = 17.7%, Sd = 4.1%).

- 10% oil shale of the Baltic basin fraction 0-6 mm with a mineral content of 73.3%. The total content of Ca and Mg carbonates in the ash is 64%. Before adding to the charge, the slate was crushed to a particle size of 0-1 mm.

The resulting mixture was coked in a Nikolaev furnace until a temperature in the loading center of 1000 ° C was reached.

The resulting metallurgical coke has the following characteristics:

Ad = 7.7%; Vdaf = 1.0%; CRI = 30.1%; CSR = 66.8% .; Stotal = 3.47%, S = 2.19% (bound), Sd = 1.28% ( _unbound ), T _pl . _Ash = 1280 ° C, where:

Ad - ash content;

Vdaf - volatile matter content;

CRI - reactivity;

CSR - hot strength;

Stot - total sulfur content;

S is the content of mineral (bound) sulfur;

Sd is the content of organic (unbound) sulfur.

Example 2

The composition of the charge for coking:

- 85% petroleum semi-coke according to TU 0258-229-00190437-2008 (Ad = 0.4%, Vdaf = 17.7%. Sd = 4.1%).

- 15% oil shale of the Baltic basin fraction 0-6 mm with a mineral content of 73.3%. The total content of Ca and Mg carbonates in the ash is 64%. Before adding to the charge, the slate was crushed to a particle size of 0-1 mm.

The resulting metallurgical coke has the following characteristics:

Ad = 11.4%; Vdaf = 1.0%; CRI = 35.2%; CSR = 58.3%; Stotal = 3.18%, S = 2.60% (bound), Sd = 0.58% ( _unbound ), _{Tm of ash} = 1257 ° C.

Example 3

The composition of the charge for coking:

- 47.5% petroleum semi-coke according to TU 0258-229-00190437-2008 (Ad = 0.4%, Vdaf = 17.7%, Sd = 4.1%);

- 47.5% production coal charge of OJSC Ural Steel (Ad ⁼ 8.5%, Vdaf = 26.6%, Sd = 0.39%). (The composition of the production coal batch of Ural Steel OJSC: a mixture of coal concentrates POC Pechorskaya - 12%; POC Berezovskaya + PF Bachatskaya + PF Mezhdurechenskaya - 55%; PF Antonovskaya + PF Raspadskaya - 33%);

- 5% oil shale of the Baltic basin fraction 0-6 mm with a mineral content of 73.3%. The total content of Ca and Mg carbonates in the ash is 64%. Before adding to the charge, the slate was crushed to a particle size of 0-1 mm.

The resulting metallurgical coke has the following characteristics:

Ad = 9.7%; Vdaf = 1.0%; CRI = 31.1%; CSR = 61.8%; Stotal = 2.03%, S = 1.31% (bound), Sd = 0.72% ( _unbound ), T _pl . _Ash = 1485 ° C.

As follows from the above examples, coke obtained from the inventive charge, according to its characteristics, is suitable for use as metallurgical. Mineral sulfur contained in it during smelting of pig iron will turn into slag, and a lower (compared to conventional metallurgical coke) ash and melting ash will significantly reduce coke consumption. The invention allows to reduce the consumption of coke in the range of 1-12%.

Claims (1)

The mixture for producing metallurgical coke from carbon-containing materials with a content of heavy sulfur residues of oil refining in an amount of at least 10%, characterized in that it contains oil shale in an amount of from 0.1 to 30% by weight of the charge, petroleum semi-coke is used as heavy sulfur residue of oil refining with the release of volatiles in an amount of 14-25%.