RU2550874C2 - Coal charge preparation for coking - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention may be used in by-product coke industry. Proposed method comprises batching, sorting, crushing, drying and mixing of coals. Prior to final crushing, coal charge is sized to separate fraction smaller than or equal to 6 mm and the remaining fraction of the charge is mixed with aforesaid fraction and dried to 4-6% of residual moisture content. Dusty fraction equal to or smaller than 0.5 mm is separated in drier and briquetted. Briquettes are mixed with dried charge and transferred to coke side.

EFFECT: dense coal load, higher efficiency of coking, higher yield of better CSR, CRI indices and between mechanical strength M₄₀.

2 dwg, 1 tbl

Description

The invention relates to the coke industry and can be used to develop technology for the production of coke with lower costs when converting coal into coke, increase its quality characteristics, reduce the environmental load on the production environment.

One of the main directions and ways to improve the quality of coke in the preparation of coals for coking is to increase the bulk density of the coal charge, which is achieved in the following ways:

1. reducing the moisture load of the coal charge;

2. the application of technology of selective grinding, granulation, briquetting, ramming, thermal preparation, oiling of the charge.

When using multicomponent coal mixtures with unstable physicochemical properties for coking, it is important to eliminate factors that negatively affect the bulk density of the charge, reduce the productivity of coke oven units and the quality characteristics of coke for blast furnace production for the preparation of a charge.

Known technology for the preparation of the charge for coking, which provides for the regulation of coal moisture by partially removing moisture to a level of 4-6%. This technology is called CMC (Coal Moisture Control) [1].

The essence of the technology lies in the fact that to stabilize the density of the coal load and reduce the heat consumption for coking, the finished mixture is dried in a drum dryer to 4-6% residual moisture before being transferred to coke ovens.

The disadvantage of CMC technology is the increased dust removal of small classes of coal during transportation and loading, which worsens the condition of the production environment, enhances graphite deposits on the walls of coke ovens, and has a negative impact on the quality of coking chemical products.

In order to reduce the negative factors of CMC technology in 1992, Nippon Steel (Japan) developed and introduced coal preparation technology, which was called DAPS (Dry - cleaned & Agglomerated Precompation System) [1].

The technology of preparing coal blend DAPS is as follows. The finished mixture (crushed and mixed by components) is dried in a dryer - classifier. During the circulation of the generator gas, the captured coal classes 0-0.3 mm are briquetted by dry pressing on a roller press. When using this technology, the density of the coal load reaches 800 kg / m ^{3 the} volume of the furnace, which favorably affects the improvement of quality indicators of coke.

The disadvantages of this technology:

1. in the process of preparing the coal charge (crushing) there is a significant up to 30% increase in small classes (0-0.3 mm), which negatively affects the quality characteristics of coal: sintering and coking ability;

2. the complexity of the hardware design.

A known method of selective crushing (ID), including the dosing of coals of various grades from silos, mixing, crushing and separation in the apparatus of the ACS (fluidized bed separator) on the prepared product and material, requiring additional crushing, in which pulverized coal circulates in a reagent-air that supports boiling coal in the ACS (Akhmetov SA Technology of processing oil, gas and solid fossil fuels. - S-Pb .: Nedra, 2009) [2].

The disadvantage of this method is that the crushing process of the selected large product is repeated, in which there is a re-grinding of "soft" coals, providing sintering of the coal charge. As a result, a negative effect is realized - self-depletion of the mixture with an increase in class 0-0.5 mm With high humidity of coal, the efficiency of selective grinding is low.

The objective of the invention is to improve the technology for preparing a coal charge for coking, providing an increase in the loading density of coke ovens, increasing their productivity, improving the quality indicators of metallurgical coke, reducing energy costs (electricity and heat for coking), reducing the environmental load: the amount of polluted water discharged, chemical waste , reduction of diffuse emissions during loading of furnaces and in the process of coking, increasing the efficiency of use imicheskih waste in the preparation of the coal charge.

The problem is achieved in that in a method of preparing a coal charge for coking, including dosing, sorting (classification), crushing, drying, mixing coal, according to the invention, before the final crushing, the coal charge is classified according to particle size distribution, while separating the class with a fraction of less than or equal to 6 mm, without subjecting it to grinding, and the remainder of the charge is crushed and mixed with a pre-allocated fraction of less than or equal to 6 mm, dried to 4-6% residual moisture, where the pulverized the first class is less than or equal to 0.5 mm, followed by briquetting and mixing briquettes with a dried charge for transfer to coke production. The proposed technology for the preparation of a coal charge for coking effectively implements the principle of "do not crush the excess." This principle is partially implemented in the technology of preparation of the mixture using selective grinding [2]. However, just as when applying DAPS technology, the coal charge is first crushed and only at the next stage is the separation of the finished product — coal of the 0-3 mm class.

An increase in dusty particles of coal - 0.5 mm class - in the finished mixture adversely affects a decrease in loading density and a deterioration in the quality characteristics of coal and coke.

Depending on the quality of the components of the coal charge when separating from the large and middle class of coals, the grain size of the finished product can vary from 3 to 6 mm, as well as the size of the screen sieves - classifier.

To stabilize bulk weight, reduce heat consumption for coking, the finished mixture is dried to a moisture content of 4-6%.

When applying this scheme for the preparation of a coal charge for coking, an increase in the bulk density of the coal charge in the coke oven is achieved due to:

1. reduce the effect of grinding (crushing) on the increase in the content in the finished product - the mixture - dust-like class 0-0.5 mm;

2. reduce the moisture content of coal loading from 9.6-10% to 4-6%. In this case, one can predict positive trends in the change in the coal maceral composition: an increase in the vitrinite content Vt, a decrease in the sum (Σ) of sludge components (OK) - Σ OK, and, as a result, an improvement in the sintering ability and coking ability of the coal charge and qualitative indicators of coke.

During the drying process, when using drying units of the type: pipe dryer, shaft dryer, fluidized-bed dryer, dust-like classes of coal 0-0.5 mm are captured in equipment for cleaning circulating heat carrier gas, then briquetted with the addition of chemical waste products ( fusov, neutralized acid tar, etc.).

Briquetted coal is mixed with the dried charge and transferred to the coal tower. In order to reduce the cost of coke production, coke dust UTKK, coke and pitch coke breeze can be added as additives to briquetted materials.

Comparative analysis with the prototype allows us to conclude that the inventive method of preparing a coal charge for coking differs in that:

1. grinding coal for coking is carried out after preliminary separation of the finished product by size.

2. in the process of drying the coal charge, the dust-like class of coal 0-0.5 mm is separated, briquetted using the above binders.

Analysis of known technical solutions (analogues) in the studied area, i.e. metallurgy, allows us to conclude that they lack features similar to the essential distinguishing features in the inventive method for preparing a coal charge for coking and recognize the solution as meeting the criterion of “significant differences”.

The invention is illustrated in FIG. 1, 2, which show the preparation of a coal charge. The diagram shows coal silos 1-3 for filling with coal of different grades, sorting equipment 4, 5 (in the embodiment of Fig. 2 - crushing and screening), 6, 7 - crushing equipment, 8 - dryer, 9 - equipment for briquetting dusty classes of coal , 10 - mixer.

The work of the proposed method for the preparation of a coal charge for coking is as follows (Fig. 1). Before transferring coal mixtures to silos 1-3, coal enters the sorting equipment 4 (option in Fig. 2 - crushing and screening), where it is divided into classes: large 25-150 mm, medium 0-25 mm. Large (25-150 mm) enters the grinding equipment 6, is crushed and connected with a class of 0-25 mm in the stream before loading into the silo. After dosing the components from the silos 1, 2, 3, the charge is fed to the sorting equipment 5 - screen (group of screens), where the finished product is 0-6 mm. Oversize product is fed to grinding 7 (in the embodiment of Fig. 2, grinding equipment 6, 7 can be combined). The crushed product is mixed with a class of 0-6 mm and enters the dryer 8, where the finished mixture is dried to a residual moisture content of 4-6%. In this case, the dust-like classes of coal 0-0.5 mm are separated, followed by their briquetting. The dried charge and briquettes are mixed on equipment 10 and fed into the coal tower of coke oven batteries. In a particular embodiment (Fig. 2), classification and preliminary crushing on equipment 4, 6 can be after mixing of coal on equipment 4 (after silos 1, 2, 3). At the same time, the class of the under-sieve product can be 0-15 mm, and the over-sieve - 150-15 mm.

In the process of conducting experiments on the preparation of the mixture according to the claimed technology in comparison with the preparation with selective crushing followed by experimental coking in metal boxes, in coke ovens, comparative results were obtained, which are presented in table 1.

When conducting tests using this technology in comparison with the known method according to table 1 it is seen that:

- increased bulk weight of coal;

- the content of the coal class 0-0.5 mm in the finished charge decreased from 39.6 to 27.2;

- increased output of gross and metallurgical coke;

- increased mechanical strength M40, decreased Μ10;

- improved coke strength CSR and CRI;

- improved coke structure characteristics.

The application of the claimed method with obtaining coke of higher quality in terms of M ₄₀ , M ₁₀ , CSR, CRI allows to reduce the consumption of coke for pig iron production by 5-10%, to increase the productivity of furnaces by more than or equal to 5%. For industries without a metallurgical cycle, the effect consists of the possibility of increasing the volume of coke production, reducing the consumption of scarce expensive coals, and the possibility of increasing prices and demand for metallurgical coke.

Using the claimed method of preparing a coal charge for coking allows:

1. increase the density of coal loading in coke ovens, the productivity of coke production, the qualitative characteristics of coke for blast furnace production;

2. reduce costs for the production of coke due to the possibility of using up to 20% low-caking coals without compromising the quality of coke, the use of additional additives: dust USTK, coke and pitch coke fines;

3. reduce energy costs: electricity during coal crushing, fuel consumption for coking;

4. reduce the environmental load on the production environment by reducing diffuse emissions during coking, reduce the amount of chemical waste and the resulting contaminated water after chemical workshops.

Information sources

1. OJSC "Chermetinformation". Ferrous metallurgy news abroad, No. 6, 2010, pp. 8-12.

2. S.A. Akhmetov, M.Kh. Ishmiyarov, A.A. Kaufman. Technology for the processing of oil, gas and solid fossil fuels. - St. Petersburg: Nedra, 2002, pp. 478-451.

Claims (1)

A method of preparing a coal charge for coking, including dosing, sorting, crushing, drying, mixing the coals, characterized in that before the final crushing, the coal charge is separated by the size of the coal grains, separating the class with a fraction of less than or equal to 6 mm, and the remainder of the charge is crushed and mixed with a pre-isolated fraction of less than or equal to 6 mm and dried to 4-6% residual moisture, where a pulverized class of less than or equal to 0.5 mm is separated, which is briquetted, mixed with a dried charge and transferred to coke production Odinstvo.

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