RU2539186C1 - Method of obtaining high-quality coke - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining high-quality coke by application of borate on red-hot coke after discharge from coke furnaces with temperature 1050±50°C, with its extinguishing being carried out with water solution of borates with content of borates 3-10 g/dm³ in form of solution or pulp in quencher car under quenching tower for 90-120 sec, with tetraborate sodium pentahydrate, borax decahydrate, disodium octaborate tetrahydrate being used as borates.

EFFECT: increased quality of blast furnace coke by parameter of hot strength after reaction with CO₂ and reduction of its reaction ability.

1 dwg, 3 tbl

Description

The invention relates to the field of coke oven and blast furnace production.

In modern production, the quality of blast furnace coke must meet the requirements of the international standard ASTM: D5341-99 in terms of CSR - coke strength after reaction with CO ₂ and CRI - reactivity.

In coke production, improvement of its mechanical strength is mainly achieved using methods based on the preparation of a coal charge for coking by varying its brand composition, tamping, briquetting, heat treatment and processing with various organic and inorganic additives, etc. Nevertheless, the effectiveness of such technologies is unsatisfactory due to the limited choice of coal grades, the dependence of the coke strength index on the quality of the charge used, the unsatisfactory ratio of reactivity and strength of the obtained coke, etc.

In this sense, technologies for improving CSR and CRI by chemical treatment of finished coke are more effective.

A known method of processing blast furnace coke by applying borate to pieces of blast furnace coke, characterized in that after unloading from a coke oven, quenching and sorting pieces of blast furnace coke having a temperature of 20-50 ° C, is treated by spraying a 2-20% aqueous solution of borate, selected from the series: sodium tetraborate, potassium tetraborate, calcium tetraborate, and such a volume of solution is used for processing that the amount of dry borate in coke is 0.2-0.50% (wt.) in terms of coke (RF patent 2336297 C1, IPC C10L 9/10, priority 05.07.2007).

The disadvantages of the known method of processing blast furnace coke are:

- the heat of hot coke is not used for melting borates on the coke surface with the improvement of its quality at the quenching stage, the borate aqueous solution on cold coke is not chemisorbed on the coke surface, and the moisture content in blast furnace coke is regulated for the +40 mm class - 5%, for + 25 mm - 6%. Repeated wet processing of coke only reduces its quality;

- the processing uniformity of all pieces of coke in the stream is not ensured due to the lack of vaporization;

- the need for an additional stage of out-of-furnace coke treatment in the stream after the quenching stage.

There is a method of improving the quality indicators of blast furnace coke, including spraying at a temperature of at least 20 ° C into pieces of blast furnace coke of a 2-20% aqueous solution of borate metal selected from the range: sodium, potassium, calcium, containing 0.1-0.2 wt.% non-ionic surfactants in the form of mono- and / or dialkyl ethers of polyethylene glycol in an amount providing a content of surfactant in coke of 0.0035-0.0070 wt.%, moreover, as a metal borate selected from the range: sodium, potassium, calcium, use foam one metal’s metaborate, and the solution is used in an amount providing a dry pentaborate content in coke of 0.09-0.68 wt.% (RF patent 2445348 C1, IPC C10L 9/10, priority 03/21/2011).

The disadvantages of this method of processing blast furnace coke are:

- heat of hot coke is not used for melting borates on the coke surface with improvement of its quality at the quenching stage;

- the need for an additional stage of out-of-furnace coke treatment in the stream after the quenching stage;

- the processing uniformity of all pieces of coke in the stream is not ensured due to the lack of vaporization;

- the complexity of the technological scheme for the preparation and maintenance of the concentration of a solution of borates and mono- and / or dialkyl ethers of polyethylene glycol.

The closest to the proposed method, in essence and the achieved result, is a well-known known method for processing blast furnace coke selected as a prototype, which involves spraying a finely divided solid inorganic compound onto hot pieces of coke (t≥850 ° C) using a preheated gas stream (GB 1423187 , published on January 28, 1976, IPC C10L 5/00). According to a known method, boric acid or borates are used as an inorganic compound for coating coke. In this case, coke is deactivated in reaction with oxygen (O ₂ ) and carbon dioxide (CO ₂ ) due to the formation of a protective film of molten borates on the surface of coke pieces at high temperature.

The disadvantages of this method include:

- the need for an additional stage of out-of-furnace coke processing after the quenching stage;

- the lack of effectiveness of the technology, which is expressed in a slight decrease in reactivity (CRI) and a slight increase in the strength of coke after the reaction (CSR);

- uneconomical technology, since a high temperature (≥850 ° C) is required to carry out the process of forming a protective film on the coke surface;

- the complexity of the hardware design of the process of applying an inorganic substance to coke, heat treatment and monitoring the progress of applying a protective film to coke (the use of gas nozzles, borate powder atomizers, high temperature reactors, monitoring devices, etc.);

- increased danger to the environment and the health of staff using finely divided solid boric acid or borates at high temperatures.

The problem to which the invention is directed, is to improve the quality of blast furnace coke in terms of hot strength after reaction with CO ₂ (CSR) and reduce its reactivity (CRI) in the framework of the existing wet quenching technology.

The problem was solved due to the fact that in the method of producing high-quality coke, coke with a temperature of 1050 ± 50 ° C after being unloaded from a coke oven into a quencher is extinguished by an aqueous solution of borates with a content of 3-10 g / dm ³ borates (sodium tetraborate pentahydrate, borax ten-water, dysodium octaborate tetrahydrate) in the form of a solution and pulp for 90-120 seconds directly in the extinguishing car, located under the extinguishing tower.

Process water with a temperature of 70-90 ° C is used to dissolve borates.

Borates contained in the form of a solution and pulp, when extinguished, are first melted on the surface of the hot coke and during further extinguishing remain in the pores and cracks of coke. After quenching, the coke processed in the stewing car is scattered into classes to produce blast furnace coke.

It was experimentally established that the pore volume of a typical metallurgical wet quenching coke is on average 8.1 * 10 ^-3 ml / g (Coke and Chemistry. 2012. No. 1. P.18-27). After filling pores and cracks of coke with borates with the formation of a monolithic film of glaze on the walls of pores, cracks, and the surface of a piece of coke, the pore volume decreases by an average of 2.3 times and amounts to 3.5 * 10 ^-3 ml / g. Thus, the volume filled with the reagent is 4.6 * 10 ^-3 ml / g or 7.9 * 10 ^-3 g of aqueous sodium tetraborate per 1 g of coke (10 kg per 1 ton of coke).

Theoretically, this corresponds to a borate content of 2.5 g / dm ^{3 of} solution for quenching.

Practically under production conditions and taking into account losses, the optimum borate content in an aqueous solution during coke processing is determined to be 3-10 g / dm ³ .

The content of borates in an aqueous solution of less than 3 g / dm ^{3 is} not enough to create a protective layer on the walls of pores, cracks, and the entire surface of the piece, and there is no improvement in CSR and CR1.

The content of borates in an aqueous solution of more than 10 g / DM ³ technologically and economically impractical.

Quenching of coke with water containing 3-10 g / dm ^{3 of} borate in the form of a solution and pulp is carried out for 90-120 seconds. This time is enough to fill all the pores of coke with an aqueous solution of borates with the creation of a protective layer and reduce the temperature of coke.

The claimed method for producing high-quality coke is implemented as follows (see the scheme for producing high-quality coke with borate water).

From the sump 1 of the extinguishing tower 3, hot water is pumped into the mixing vessel 5 at a temperature of 70-90 ° C. A hopper 7 with a dispenser 6 is installed on the tank. Borate powder (sodium tetraborate pentahydrate, ten-water borax, diode octaborate tetrahydrate) is installed from the hopper into the tank for mixing and dissolution. Mixing water in the tank is done by supplying hot steam to the bottom. The solution from the upper part of the tank flows into the sump 1 of the extinguishing tower 3 and is pumped into the extinguishing car 4 by a pump 2 for quenching coke. The content of borates in the water of the sump is maintained at a level of 3-10 g / dm ³ in the form of a solution and pulp.

In the process of quenching coke with water containing 3-10 g / dm ^{3 of} borate in the form of a solution and pulp, the borates are melted on the hot surface of the coke, and with further cooling of the coke, the borate solution uniformly covers the surface of the coke piece and penetrates into the pores and cracks. Such a protective layer reliably prevents the penetration and influence of oxidizing gases on coke, respectively, reducing the CRI reactivity index and increasing the CSR strength index of blast furnace coke.

The claimed method for producing high-quality coke with a temperature of 1050 ± 50 ° C in a stew car when it is extinguished in a stew tower with water containing 3-10 g / dm ³ borates in the form of a solution and pulp was tested at the Chelyabinsk Plant for 90-120 seconds production of coke and chemical products ”(Mechel-Coke LLC) and Moskoks OJSC.

After sieving the coke into fractions, the CSR and CRI quality parameters of blast furnace coke were determined according to ASTM standard: D5341-99.

Tables 1-3 show the results of blast furnace coke tests. As can be seen from the tables with relatively low CSR and high CRI of the original blast furnace coke, quenching of coke with water containing 3-10 g / dm ^{3 of} borate in the form of a solution and pulp allows directly in the framework of the existing production:

- increase the strength of coke after the reaction with CO ₂ (CSR) by 9.4-13.1% (rel.);

- reduce reactivity (CRI) by 5.3-11.9% (rel.);

- increase the efficiency of the process by simplifying the technology of processing coke with an inorganic additive that occurs when it is quenched at high temperatures to obtain a protective film;

- increase the efficiency of the pig iron smelting process through the use of better coke in terms of CSR and CRI, which allows to reduce the coke consumption for the smelting of 1 ton of pig iron and reduce its cost.

The proposed method for producing high-quality coke differs from analogues in that coke with a temperature of 1050 ± 50 ° C after being dispensed from the ovens is extinguished in an extinguishing car with an aqueous solution of borates with a content of 3-10 g / dm ³ in the form of a solution and pulp. When treating coke with large amounts of water (4 m ³ per tonne of coke), all pores of coke are filled with a solution and pulp of borates, then water evaporates under the influence of high coke temperatures (1050 ± 50 ° C), and borates remain in the pores of coke. The coke temperature at the end of the quenching process drops to ~ 250 ° C.

Processing coke with aqueous solutions of borates allows one to obtain coke that meets international standards in terms of quality indicators CSR> 55-70% and CRI≤30-22%, from coke having lower rates, and accordingly expand the raw material base of coking.

Table 1
Quenching of coke with 10-aqueous sodium tetraborate (N2B4O7-10 H2O)
Name of PF					Concentration, g / dm	Coke quality
The composition of the charge,%
Pechor sky 2zh	Tomusinskaya KO + OS	Siberia OS + KS	Neryungrinskaya K (2K)	Cd		M 25%	M 10%	CRI,%	CSR,%
40	35	10	10	5	-	87.6	8.5	31.8	54.8
40	35	10	10	5	10	88.1	8.0	28.0	62.0
40	35	10	10	5	3	88.4	7.8	30,0	59.0
* KD - coking additive

table 2
Coke quenching with 5 aqueous sodium tetraborate (N2B4O7-5H2O)
Name of PF						Concentration, g / dm 3	Coke quality
The composition of the charge,%
GJ collapse	Blacksmith GJ + F	Tomusinskaya KO + KS	Siberia OS	Neryungrinskaya K (2K)	Cd		M 25%	M 10%	CRI,%	CSR,%
twenty	twenty	25	fifteen	fifteen	5	-	86.5	8.9	35.5	48.9
twenty	twenty	25	fifteen	fifteen	5	5,0	86.9	8.6	32,7	53.6
twenty	twenty	25	fifteen	fifteen	5	7.0	86.5	8.0	32,0	54.5
* KD - coking additive

Table 3
Quenching of coke, diode octaborate with tetrahydrate (Na2B8O13-4H2O)
Name of PF						Concentration, g / dm 3	Coke quality
The composition of the charge,%
Taybinskaya, GZ	Pechor Skye, W	Tomusinsky KO + KS	Schedrukhinskaya, GZ	Neryungrinskaya K (2K)	Cd		M 25%	M 10%	CRI,%	CSR,%
5	16	33	29th	eleven	6	-	84.5	9.2	35.5	48.0
5	16	33	29th	eleven	6	10.0	87.5	7.9	31.5	54.0
5	16	33	29th	eleven	6	3.0	86.5	8.3	33.6	52,5
* KD - coking additive

Claims (1)

1. A method of producing high-quality coke by applying borate to incandescent coke, characterized in that after the issuance of incandescent coke from coke ovens to a quencher with a temperature of 1050 ± 50 ° C, it is quenched with an aqueous solution of borates containing 3-10 g / dm ³ in the form of a solution and pulps in a stew car under the stew tower for 90-120 sec, while sodium tetraborate pentahydrate, ten-water borax, diode octaborate tetrahydrate are used as borates.