RU2375414C1 - Method of brick fuel manufacturing - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to manufacturing of solid fuel and can be used in metallurgical and other industries and also in boiler houses for heating. Manufacturing method of brick fuel includes mixing of carbon-bearing raw material with binding agent, compressing of mixture and following solidification of bricks in oxidising atmosphere at temperature 150-300°C, herewith in the capacity of binding agent it is used resin of low-temperature semi-coking, received at temperature up to 650°C.

EFFECT: invention provides enrichment of raw materials base for receiving of brick fuel, simplification and reduction the price of receiving technology of brick fuel, reduction of time and man-hours for its manufacturing.

4 cl, 5 ex, 4 tbl

Description

The invention relates to the production of solid fuels and can be used in the metallurgical and other industries, as well as in boiler rooms for heating.

A known method of producing briquette fuel by mixing carbon-containing raw materials and part of the resin of high-temperature (at a temperature of 850-900 ° C) semi-coking, remaining after distillation of fractions boiling up to 300 ° C, followed by pressing and heat-curing briquettes at a temperature of 220-280 ° C (" Coke and iron coke based on briquetting. ”E. M. Taits, B. M. Ravich, I. A. Andreeva. M.: Publishing House Metallurgy, 1965, pp. 19-24). The disadvantage of this method is its complexity, due to the need for special production for the manufacture of a binder. In the known method, only the pitch portion of the resin, which remains after distillation of the fractions boiling up to 300 ° C, is actually used. Since in the known method only part of the high-temperature semi-coking resin is used, the resources of the binder are reduced.

The problem solved by the invention is the expansion of the raw material base for the production of briquette fuel, the simplification and cheapening of the technology for producing briquette fuel, reducing the time and labor costs for its production.

The problem is solved in that in a method for the production of briquette fuel, comprising mixing carbon-containing raw materials with a binder, pressing the mixture and then curing the briquettes in an oxidizing atmosphere at a temperature of 150-300 ° C, a low-temperature semi-coking resin obtained at temperatures up to 650 ° is used as a binder FROM.

It is advisable to serve the semi-coking resin at a temperature of from 20 to 60 ° C.

As carbon-containing raw materials, coke breeze and / or pitch coke breeze and / or petrocoke breeze and / or anthracite breeze and / or coal breeze are used.

The amount of binder is from 7 to 20 wt.%.

Semi-coking resin - a by-product formed in the process of semi-coking of coal. Semicoking resins are characterized by the presence of phenols in them. For this reason, semi-coking resin is the raw material for the production of phenols in the processing of solid fossil fuels of humic origin. However, at present, in connection with the development of more advanced methods for the production of phenols (for example, the production of phenol and acetone by the cumene method, which is cheaper and therefore more promising), the problem of marketing and the qualified use of semi-coking resins has arisen.

Semi-coking resins vary significantly in composition and properties depending on the chemical nature and degree of maturity of the processed fuel and the process conditions. In most cases, the difference in chemical composition boils down to other quantitative ratios of the components (groups) that make up the resins. The similarity of all semi-coking resins lies in the fact that they include both hydrocarbons of all classes and oxygen compounds of an acidic and neutral nature. The relations between these groups are determined primarily by the nature of solid fossil fuels and the content of heteroatoms in them, and the qualitative composition and number of components of the same class - by technological conditions.

The term semi-coking combines technological processes of pyrolysis of coal, occurring in the temperature range 500-900 ° C. In this case, a solid carbon-containing residue is formed - semi-coke with a yield of volatile substances from 15.0 to 2.5-3.0% and a semi-coking resin. Therefore, the chemical composition of resins obtained in different semi-coking modes and from various coals can vary widely.

In the present invention, a low-temperature semi-coking resin (500-650 ° C) of coal, not exposed to (pyrolysis) above 650 ° C, is used as a binder.

The high reactivity of the resin components in an oxidizing environment at temperatures of 150-250 ° C allows you to get durable heat-resistant briquettes without removing fractions boiling up to 300 ° C.

The possible reasons for the high reactivity of this type of binder have been studied. The composition of the low-temperature semi-coking resin was investigated. Resins are characterized by a high content of phenols, both in the part boiling up to 300 ° C and in the pitch-forming residue.

According to the invention, the thermal curing of briquettes is carried out at temperatures from 150 to 300 ° C, mainly at 200-250 ° C. This temperature is enough to obtain briquettes with a strength of up to 300 kgf / cm ² .

Semi-coking resin, it is advisable to serve at temperatures from 20 to 60 ° C. When using the resin at temperatures below 20 ° C, the resin will be too viscous and inconvenient to feed. At semi-coking resin temperatures above 60 ° C, the release of its volatile components may begin, which is not a positive quality from the point of view of compliance with the environmental friendliness of the process.

The applicant conducted a method of PMR spectroscopy to study the distribution of hydrogen types in fractions of semi-coking resin (in all fractions, both boiling at temperatures from 230 to 300 ° C, and in fractions boiling at temperatures above 300 ° C and in pitch). It was found that all fractions of the semi-coking resin are characterized by a significant amount of hydrogen at double bonds, as well as hydrogen in the α-position to aromatic rings and double bonds. These features of the composition of the semi-coking resin determine the high reactivity of the resin as a whole to polymerization and oxidation by atmospheric oxygen. It is known that hydrogen in the α-position to aromatic rings and double bonds is most easily oxidized by oxygen with the formation of peroxide compounds. Free radicals formed during the thermal decomposition of peroxide compounds can enter into various reactions leading to the formation of larger molecules, and can also initiate polymerization reactions of unsaturated compounds. It is possible to accelerate these reactions in the presence of an active surface of a carbon-containing filler, coke. Thus, it is the increased reactivity of the components of the low-temperature semi-coking resin with a high content of phenols, unsaturated compounds and aliphatic hydrogen in the α-position to aromatic rings and double bonds that make it possible to use it as a binder in the production of briquette fuel.

Based on the studies, the applicant established the possibility of using a low-temperature semi-coking resin as a binder.

The semi-coking resin was mixed with highly carbonized fillers, pressed into briquettes and thermally cured at temperatures of 150-300 ° C. As a result, we obtained heat-resistant briquettes with compressive strength after thermal hardening of 120-150 kgf / cm ² and subsequent hardening during technological use up to 300-390 kgf / cm ² in furnaces at temperatures of 1000 ° C and more. Such strength is high and meets the requirements for the strength of briquettes used as fuel in metallurgical furnaces. The strength value was established during the calcination of briquettes, as well as by the method of “beacons” passed from coke “ears” before knocking out iron foundry cupolas.

This value of the strength of the obtained briquettes allows us to conclude that it is possible to use low-temperature semi-coking resins as a binder in the manufacture of briquettes from carbon-containing raw materials.

The use of low-temperature semi-coking resins as a binder will expand the raw material base of binders in the manufacture of briquette fuel from carbon-containing raw materials. Such briquettes are cheap, because do not require high temperature heat treatment. Mixing of the components occurs at a temperature of from 20 to 100 ° C.

The cost and simplification of the technology for the production of briquette fuel is due to the fact that in the inventive method, the entire primary resin of low-temperature semi-coking is used in its original state without separation into fractions, i.e. unlike the prototype and known methods, the organization of special production is not required in order to isolate the desired fraction from the resin.

The claimed invention is illustrated by examples.

Example 1

To coke breeze (ash content 14.5%, sulfur content up to 0.6%, volatiles yield 1.8%) with a particle size of less than 10 mm, 12% of industrial coal tar low-temperature semi-coking of long-flame coal is added. The components are mixed in a laboratory mixer with a working chamber volume of 5 liters at a temperature of 20 ° C for 5 minutes until a homogeneous (homogeneous) mixture is obtained. The characteristics of the semi-coking resin are shown in tables 1-4. Studies have shown that the used semi-coking resin contains 25% phenols, and the phenol homologues, xylenols and cresols, are the predominant components. By NMR spectroscopy on a Bruker DRx400 spectrometer, the chemical distribution of hydrogen was used to determine its distribution by structural groups in fractions and pitch. Tetramethylsilane in a CDH ₃ solution at room temperature was used as an internal standard. 10 kg of the mixture were pressed at a pressure of 400 kgf / cm ² in molds with double compression in the briquettes in the form of a biconvex lens of 50 mm diameter weighing 80 g, and also in the form close to a pad weight of 250 grams in the form of parallelepipeds with a size of 130 × 110 × ( 75-85) mm weighing up to 1500 g. Briquettes were placed in an oven or muffle and thermoset by curing for 3-4 hours at a temperature of 180-250 ° C in an oxidizing atmosphere with a content of 12-16% oxygen. The strength of thermoset briquettes compressive 120-150 kgf / cm ² . Such strength is sufficient to transport briquettes. Thermo-cured briquettes were tested for heat resistance by heating to 1000 ° C in a muffle in a coke powder bed, as well as by the method of “beacons” (briquettes) passed through an iron foundry cupola together with a coke spike before “knocking out” the cupola at the end of the working cycle. In this case, briquettes (“beacons”), together with coke, are lowered in the cupola and pass all temperature zones in the atmosphere of aggressive gases characteristic of the cupola and, thus, experience the full thermomechanical and thermochemical stresses associated with the technological use of coke.

The tests in the muffle consisted in the rapid (within 1.5 hours) heating of the briquettes from 450 ° C to 950-1000 ° C (a mode close to the heating rate in shaft furnaces). Tests when heating briquettes in a muffle showed that the briquettes remain intact, without cracks and microcracks. The strength of the briquettes in compression increases to 390 kgf / cm ² .

Tests of briquettes weighing 250 g and 1500 g in a cast-iron cupola showed that the briquettes withstand thermomechanical and thermochemical stresses without breaking. The compressive strength of briquettes after knocking out a cupola working with cast iron temperature at the outlet of 1400 ° C was 400 kgf / cm ² .

Thus, based on previous experience and research, it can be expected that the briquettes according to the present method are a good technological fuel, with which one can expect either a decrease in fuel consumption (briquettes) compared with metallurgical coke, or an increase in technological parameters - an increase in the temperature of cast iron at the exit of the cupola at 20-40 ° C.

Example 2

Coke breeze (according to example 1), pitch coke breeze (ash content 0.3%, volatiles yield 1.8%, particle size less than 10 mm) in a 1: 1 ratio are mixed with 14% of coal-tar industrial semi-coking tar of long-flame coal (according to example 1 ) 5 kg of the mixture are pressed into products weighing from 80 to 250 g in the form from a biconvex lens to a pillow-shaped and thermoset for 3 hours at 220 ° C. The strength of thermoset briquettes 140-150 kgf / cm ² . The strength of briquettes after heating to 1000 ° C in the conditions of shaft furnaces increases to 390-400 kgf / cm ² . Briquettes are suitable for use in shaft furnaces such as metallurgical and slag cupola furnaces, as well as for shaft furnaces of non-ferrous metallurgy.

Example 3

Coke breeze (as in Example 1), petroleum coke breeze (ash content 0.5%, sulfur content 3.2%, volatiles yield less than 1.0%) with a particle size of less than 10 mm in a ratio of 1: 1 is heated to 100 ° C and mixes up with 14% of coal-tar industrial resin of semi-coking of long-flame coal (characteristic according to example 1) at a temperature of 40-60 ° C until a homogeneous (homogeneous) mixture is obtained. 5 kg of the mixture are pressed into briquettes weighing from 80 to 250 g. The briquettes are thermoset at a temperature of 180-220 ° C for 4 hours. The strength of thermoset briquettes 140-150 kgf / cm ² . The strength of briquettes during technological use in mine furnaces such as cupolas increases to 400 kgf / cm ² (test briquettes by the method of "beacons"). Such briquettes can be used in the mine smelting of oxidized nickel ores, in the mine smelting of secondary copper raw materials and concentrates, etc.

Example 5

Anthracite fines (ash content 4.5%, volatiles yield 3.5%, sulfur content 1.8%) with a particle size of less than 5 mm were mixed with 7% low-temperature semi-coking coal tar with the characteristic given in Example 1. The mixture was pressed into briquettes weighing about 300 g. Briquettes were thermoset at a temperature of 250 ° C. After thermosetting in an oxidizing medium, briquettes withstand compressive stresses of up to 150 kgf / cm ² . Briquettes after heating to 1000 ° C in cupola furnaces withstand a compressive stress of 300 kgf / cm ² . Such briquettes are suitable for use as process fuel for cupola furnaces and shaft furnaces of non-ferrous metallurgy.

Example 6

Coke dust with a particle size of less than 0.5 mm is heated to 100 ° C and mixed in a heated five-liter laboratory biaxial mixer with 20 wt.% Pre-heated to 60 ° C semi-coking resin with the characteristic given in example 1. Stirring is carried out for 5 minutes to obtain 5 kg of a homogeneous homogeneous mixture. The mixture was pressed at a pressure of 400 kgf / cm ² into cylindrical products with a diameter of 15 to 30 mm. In addition, part of the mixture was processed by extrusion at a pressure of 200-600 kgf / cm ² through dies with a diameter of from 7 to 20 mm. Briquettes and extrudate were thermoset at a temperature of 180-250 ° C in a muffle with a content of 12-16 wt.% Oxygen in a gas medium. The strength of thermoset briquettes and extrudate is 120-150 kgf / cm ² . The strength of the products after heating to 1000 ° C in industrial furnaces reaches 300 kgf / cm ² . This indicates a high thermomechanical and thermochemical strength of the carbon pressed material. Such material can be successfully used in electrothermics, as it has an increased electrical resistance (30-60 Ohm × cm) compared to coke nut. The test of thermoset briquettes in the muffle consisted in the rapid (within 1.5 hours) heating of the briquettes to 1000 ° C (a mode close to the heating rate in shaft furnaces). Tests when heating briquettes in the muffle showed that the briquettes remain intact, and the compressive strength of the briquettes increases to 350-380 kgf / cm ² . Testing briquettes weighing 250 g and 1500 g by the “beacons” method in a cast iron cupola showed that the compressive strength of briquettes after passing a cupola working with cast iron at the outlet of a cupola of 1400 ° C increases to 400-450 kgf / cm ² . Briquettes remain intact. On the surface of the briquettes there are sticking droplets of slag and metal. Thus, the briquettes according to the claimed method are a good fuel suitable for technology. Based on existing experience, one can expect when using briquettes according to the claimed method of increasing technological parameters, reducing fuel consumption, increasing productivity, and increasing the temperature of cast iron at the exit of the cupola.

Example 7

The low-temperature semi-coking coal tar of Example 1 is used as a binder for partial briquetting of low-sintering components of coal mixtures or concentrates of low-sintering coal, which are briquetted in the amount of up to 30% in coal mixtures. KO brand coal concentrate with a plastic layer of 6-7 mm is mixed with 7% semi-coking resin according to Example 1, briquetted into briquettes of 25 × 25 × 15 mm in size, introduced into the coking charge in an amount of up to 30% and coked with the charge. The compressive strength of coke in coked briquettes reaches 300-350 kgf / cm ² . This allows you to expand the coal resource base. At the same time, it allows qualified processing of non-pyrolyzed resin and obtain pyrolyzed products from the decay products of the used resin.

Table 1 "Comparison of the technical characteristics of low-temperature semi-coking coal tar and high-temperature coking" No. p / p Indicator Type of resin Determination method Low temperature semi-coking High temperature coking one Volume fraction of water,% 10,4 four GOST 2477; GOST 2770 2 Density at 20 ° С, kg / m ³ 1042 1190 GOST 3900; GOST 11126 3 - Fractional composition, mass fraction (from anhydrous resin),%: up to 180 ° C 3.0 OK. one 180-230 ° C 7.2 13 230-270 ° C 15.1 10 270-300 ° C 17.1 10 final temperature 300 ° C; 6.2 eighteen - total distillation,% 48.9 OK. 40 - The temperature of the end of boiling, ° C: in pairs 315 320 in fluid 390 400 four The output of the pitch,% 50,0 60 5 Mass fraction of substances insoluble in toluene (α-fraction),% 3.8 6-10 GOST 7847
TU 14-7-100-89 6 Mass fraction of substances insoluble in quinoline (α ₁ fraction),% out 4-6 TU 14-7-100-89 7 Ash content,% 0.12 not> 0.3 TU 14-7-100-89 8 The content of phenols,% 25 1-2 9 The content of naphthalene,% traces 7-12

table 2 "The content of total phenols in the fractions of the resin low-temperature semi-coking" Fraction selection limits, ° С The output fraction from the resin,% The content of phenols,% in fraction in terms of resin <230 10.5 41.5 4.4 230-270 15.1 37.0 5,6 270-300 17.1 41.0 7.0 > 300 6.2 35.5 2.2 Total> 230 38,4 38.6 14.8 Pitch 50,0 11.3 5,6 Total 98.9 25

Table 3 "The composition of phenols in the fractions of the resin of low-temperature semi-coking" The selection limits, ° C Content total phenols,% Content% phenol o-cresol mp cresols xylenols Total <230 41.5 15.8 19.0 28.9 36,2 99.9 230-270 37.0 5.3 10.6 28,2 50.3 94.4 270-300 41.0 0.7 1,2 4.1 33.9 39.9 300-360 35.5 not def. Total 230-360 38.6 Like mass of phenols 115 94 108 108 122

Table 4 “Characterization of low-temperature semi-coking resin fractions by the distribution of hydrogen types” Fraction (boiling point, ° С) H _γ H _β H _α N _olef. N _ag <230 8.1 34,4 28.3 7.1 22.2 230-270 9.1 32,5 30.1 10,2 18.3 270-300 9.1 37.6 30.1 9.1 15.1 > 300 6.1 45.8 27.1 5,0 16,0 Pitch 7.2 33.0 32,0 3.0 25.1

Claims (4)

1. A method of manufacturing a briquette fuel, including mixing a carbon-containing raw material with a binder, compressing the mixture and then curing the briquettes in an oxidizing atmosphere at a temperature of 150-300 ° C, using a low-temperature semi-coking resin obtained at temperatures up to 650 ° C as a binder. 2. The method according to claim 1, characterized in that the semi-coking resin is served at a temperature of from 20 to 60 ° C. 3. The method according to claim 1, characterized in that coke breeze and / or pitch coke breeze and / or petrocoke breeze and / or anthracite bite and / or coal bite are used as carbon-containing raw materials. 4. The method according to claim 1, characterized in that the amount of binder is from 7 to 20 wt.%.