RU2486232C1 - Method of making fuel briquettes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of making fuel briquettes, which involves mixing carbon filler with ground coal, adding a binding substance and briquetting the mixture under pressure. The carbon filler, which is in form of aluminium wastes, anode paste and electrodes in amount of 25.1-85.00 wt %, is dry-mixed with ground brown coal until a 100% dry mass is obtained, followed by addition of the binding substance to the dry mass. The binding substance used is bitumen or polyvinyl alcohol in amount of 2-10 wt %, in excess of 100% of the dry mass. If polyvinyl alcohol is used as the binder, hydrophobic additives are added to the obtained mixture in amount of 1-5 wt %, in excess of 100% of the obtained mixture.

EFFECT: improved properties.

3 cl, 3 tbl, 2 dwg

Description

The invention relates to the field of non-ferrous metallurgy, in particular for the processing of carbon-containing waste from the aluminum and electrode industries, and can be used in the production of alumina, cement and heat and power resources.

In the production of aluminum and electrodes, a significant amount of carbon-containing waste is generated, which is used in a limited way and is mainly exported to the industrial and household waste landfill. The material composition of a number of wastes is predominantly represented by amorphous carbon, constituting more than 90%. This determines the possible niche of using carbon waste as a component of the charge in the production of fuel briquettes. Due to the low volatile content, the process of burning carbon-containing waste under oxidizing conditions begins at temperatures above 500 ° C, which complicates the ignition of the material and limits its use for energy purposes without mixing with higher reactive fuels, such as brown coal.

Known methods for producing fuel briquettes based on mixed compositions of brown coal, various types of waste and binder.

A known method of briquetting coal sludge and small classes of brown coal, including mixing sludge or coal with water-soluble binders and subsequent packaging, while drying and subsequent curing of briquettes occurs during heating and subsequent burning of briquettes (1). The disadvantages of this method are the need to use expensive packaging and create conditions during transportation to ensure tightness.

A known method of producing fuel briquettes based on coal and hydrolysis lignin in the ratio of coal / lignin 70/30%, while briquetting is carried out at a temperature of 270-330 ° C and a pressure of 90-110 MPa (2). The disadvantage of this method is the high energy consumption for production.

A known method of producing a fuel briquette, comprising pressing under pressure the recycled wood chips, saturated with petroleum products, in the treatment of wastewater contaminated with petroleum products, which add wood flour. The disadvantage of this invention is the low calorific value, low strength characteristics of the briquette (3).

A known method of producing fuel briquettes from brown coal, where household waste polyethylene is used as a binder, in the form of crushed particles, less than 7 mm in size, in the amount of 6-7% by weight of dry coal, the briquetted mixture is heated to a temperature of 90-130 ° C and briquettes are pressed at a pressure of 98-99 MPa. The disadvantage of this invention is the low calorific value, low strength characteristics of the briquette and carcinogenic emissions during the combustion of polyethylene (4).

The closest technical solution is a method for producing fuel briquettes, comprising impregnating a porous carbon filler with a hydrocarbon-containing binder with stirring and heating, followed by mixing with ground coal and bracketing the mixture with the addition of the obtained material to ground brown coal in an amount of 5-25 wt.%, Mixing and pressing at 40-80 ° C and 80-120 MPa.

The disadvantage of this method is the need for preliminary impregnation of the carbon filler with stirring and heating in order to exclude lubrication of the matrix channel of the stamp press with a binder, which leads to a decrease in the strength of the briquette (5).

The objective of the proposed technical solution is the disposal of industrial waste and improving environmental safety.

The technical result of the invention is the production of high-strength fuel briquettes from carbon-containing waste without preliminary impregnation of the carbon filler, which ensures its higher manufacturability and lower cost of production of briquettes.

The technical result is achieved by the fact that the method of producing a fuel briquette, including mixing the dry components of the charge, adding a binder and pressing is carried out using carbon wastes from the production of aluminum, anode mass and electrodes having high calorific value at a high ignition temperature and brown coal having low calorific value ability and low flash point in the following ratio, wt.%:

- Carbon waste - 25.01 ÷ 85.00%;

- Brown coal - 15.00 ÷ 74.99%.

The invention consists in mixing carbon wastes from the production of aluminum, anode paste and electrodes (suction dust, screenings of fine fractions) with brown coal, followed by the addition of a binder (bitumen, polyvinyl alcohol) in a ratio of 25.01 ÷ 85.00 wt.% Carbon wastes, 15.00 ÷ 74.99 wt.% Brown coal, 2 ÷ 10 wt.% Binder in excess of 100% dry weight.

The method complements a particular distinguishing feature, also contributing to the achievement of a technical result.

The composition of the mixture can be introduced 1 ÷ 5% hydrophobic additives (fuel oil) in excess of 100% of the resulting mass, when used as a binder polyvinyl alcohol.

Hydrophobic additives are used to increase the moisture resistance of briquettes.

An increase in the strength of briquettes is achieved due to the uniform distribution of particles of finely dispersed (dusty) carbon filler (carbon waste from aluminum production) and particles of crushed brown coal during the dry mixing stage, which subsequently, when a binder is added, helps to obtain the maximum density of the composition of the briquette components and at the same time to achieve the required strength minimum binder required. The minimum content of brown coal in the briquette and the amount of binder are selected in such a way as to ensure maximum penetration of the binder into the pores of the brown coal and the formation of a monolithic briquette when filling the space between particles with a minimum amount of binder. Thus, the probability of wetting the stamp press channel with an excess binder is eliminated and the factor contributing to a decrease in the briquette strength is leveled.

Pre-mixing the carbon filler and the binder, according to the prototype, will not solve the problem of wetting the matrix channel of the stamp press due to the low porosity of the carbon filler.

The method is illustrated by drawings, where in FIG. 1 shows the calculated lower calorific value of fuel briquettes without taking into account the binder depending on the content of carbon-containing waste; FIG. 2 - dynamics of changes in the mass and yield of volatile compounds when heating pulverized coal briquettes

(Composition No. 83: 50 wt.% - brown coal + 50 wt.% - suction dust + 8 wt.% (In excess of 100%) - bitumen.

In the process of briquette preparation, dry mixing of brown coal, previously crushed to a fraction of 13 mm, with pulverized carbon wastes is carried out, followed by mixing of the mixed composition with a binder and hydrophobic additives at a temperature of 40 ÷ 90 ° C. Next, the resulting mixture is fed for briquetting at 50 ÷ 120 MPa. The resulting briquettes are naturally cooled during transportation to the discharge site.

To achieve a technical result in terms of increasing the calorific value and ensuring economic efficiency when burning fuel briquettes based on carbon wastes, their calorific value should not be lower than 20,000 kJ / kg (Figure 1). To ensure this condition, the amount of carbon-containing waste in briquettes should be at least 25%. From the analysis of the TG and DSC curves it follows that the suction dust has a lower reactivity during thermo-oxidative heating in comparison with brown coal. It follows that the reactivity of pulverized coal briquettes will also vary and depend on the dust content in the composition of the fuel briquettes.

The results of changes in the mass of pulverized coal briquettes with increasing temperature and the allocation of intermediate products are shown in figure 2. As can be seen from the drawing, the process of thermal oxidative degradation of this sample begins in the region of 200-300 ° C. The combustion process is described by a wide exothermic effect with maximums at 457.8 and 652.2 ° C. To 700 ° C, the weight loss is 43.63% of the initial mass. With further heating (region 700-1100 ° C), the process of weight loss of the sample continues due to the release of the main combustion products of the mixture: СО ₂ and SO ₂ .

An analysis of the data shows that the maximum content of carbon-containing waste in the briquette, at which they ignite due to the combustion of brown coal, is limited to 85%.

The analysis of volatile compounds during thermo-oxidative heating of briquettes shows that during the combustion of aspiration dust no additional harmful emissions in comparison with coal occur.

The novelty of the proposed proposal is due to the fact that through the use of carbon wastes from the production of aluminum, the anode mass and electrodes, the heat of combustion of the briquettes is increased, the percentage of ash content is reduced and the environmental problem of recycling industrial waste is solved.

Since the proposed technical solution can be used for the manufacture of fuel briquettes with a calorific value higher than T grade coal, and a lower cost, it can be argued that the proposal meets the criterion of "industrial applicability". In the case of using high fluorine content carbon waste as a filler, briquettes are applicable for use in the cement industry both as a fuel and as a mineralizer, which ensures a decrease in the temperature of the clinker formation process.

Table 1 presents the physicomechanical properties of briquettes based on various variants of mixed compositions with various types of binders. As follows from table 1, the best physico-mechanical properties have briquettes when adding bitumen and polyvinyl alcohol (PVA).

Example 1: The composition of the briquette: 50 wt.% - brown coal; 50 wt.% - carbon waste; 6 wt.% (In excess of 100%) - bitumen.

Table 2 presents the test results of the obtained fuel briquettes.

table 2 Name and designation of an indicator unit of measurement Test method documentation Sample Test Results

The moisture is common $$W_t^r$$

% GOST R 52911-08 2,4 Dry Ash, A ^d % GOST 11022-95 4.0 Volatiles yield, dry ashless state, V ^daf % GOST 6382-2001 25.5 Sulfur content, dry condition, $$S_t^d$$

% GOST 8606-93 1.15 Carbon Content, Dry Ashless, C ^daf % GOST 2408.1-95 88.1 Hydrogen Content, Dry Ashless, H ^daf % GOST 2408.1-95 2,5 Higher calorific value, dry condition, $$Q_s^d$$

kJ / kg GOST 147-95 30942 Higher calorific value, dry ashless condition, $$Q_s^{daf}$$

kJ / kg GOST 147-95 32240 Lower calorific value, working condition, $$Q_t^r$$

kJ / kg GOST 147-95 29602 Compressive strength MPa GOST 21289-75 12.7 Drop resistance % GOST 21289 87 Apparent density kg / m ³ GOST 2160-92 1295 Water absorption % GOST 21290-75 1.3

Example 2: The composition of the briquette: 50 wt.% - brown coal; 50 wt.% - carbon waste; 3 wt.% (In excess of 100%) - polyvinyl alcohol.

Table 3 presents the test results of the obtained fuel briquettes.

Table 3 Name and designation of indicator unit of measurement Test method documentation Sample Test Results

The moisture is common $$W_t^r$$

% GOST R 52911-08 7.3 Dry Ash, A ^d % GOST 11022-95 4.4 Volatiles yield, dry ashless state, V ^daf % GOST 6382-2001 23,2 Sulfur content, dry condition, $$S_t^d$$

% GOST 8606-93 0.97 Carbon Content, Dry Ashless, C ^daf % GOST 2408.1-95 85,2 Hydrogen Content, Dry Ashless, H ^daf % GOST 2408.1-95 2,5 Higher calorific value, dry condition, $$Q_s^d$$

kJ / kg GOST 147-95 29560 Higher calorific value, dry ashless condition, $$Q_s^{daf}$$

kJ / kg GOST 147-95 30942 Lower calorific value, working condition, $$Q_t^r$$

kJ / kg GOST 147-95 26713 Compressive strength MPa GOST 21289-75 5.7 Water absorption % GOST 21290-75 3.4

Information sources

(1) Patent No. 94034400.

(2) Patent No. 94024381.

(3) Patent No. 2309976.

(4) Patent No. 2296794.

(5) Patent No. 20055770.

Claims (3)

1. A method of producing fuel briquettes, comprising mixing a carbon filler with crushed coal, adding a binder and briquetting the mixture under pressure, characterized in that dry mixing of the carbon filler, which is waste production of aluminum, anode mass and electrodes in an amount of 25.01 85.00 wt.% With crushed brown coal to obtain 100% dry weight, followed by adding to the dry weight of the binder, in an amount of 2-10 wt.% In excess of 100% dry weight. 2. The method according to claim 1, characterized in that bitumen or polyvinyl alcohol is used as a binder. 3. The method according to claim 2, characterized in that the composition of the resulting mixture is introduced hydrophobic additives in an amount of 1 ÷ 5 wt.% In excess of 100% of the mixture when used as a binder polyvinyl alcohol.

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