RU2793684C1 - Furnace charge for sinter production - Google Patents

Abstract

FIELD: preparation of iron ore.

SUBSTANCE: invention can be used in production of sinter for metallurgical processing. The furnace charge includes iron ore material, limestone, solid fuel and a binder in the form of an organic surfactant - an aqueous solution of ethoxylated alkylphenol. The mass ratio of ingredients in the charge is as follows, in % by weight: limestone 5-10, solid fuel 5-10, ethoxylated alkylphenol 0.06·10^-5-0.07·10^-5, the rest is iron ore material.

EFFECT: obtaining high-quality sinter, increasing yield and reducing fuel consumption.

1 cl, 3 tbl

Description

The invention relates to ferrous and non-ferrous metallurgy, in particular, in the preparation of iron ore, and can be used in the production of sinter for metallurgical processing.

Known mixture for the production of sinter, including iron ore, fuel, flux and a binder containing organic surfactants. As a binder, it contains wastewater from laundry factories in the following ratio of ingredients, wt. %:

flux 5-10 fuel 5-10 sewage from laundry factories 5-10 iron ore material rest

(see ed. St. USSR No. 1770414, S22V1 / 244).

The disadvantage of this mixture is the low quality of the agglomerate, due to the high consumption of wastewater from laundry factories. The incoming moisture, together with the moisture of the wet iron ore concentrate, flux and fuel, leads to overmoistening of the charge, and this leads to a deterioration in pelletization and, as a result, to a decrease in the productivity of the sintering machine. The lack of agglomerate has to be compensated by the consumption of raw ore.

The closest analogue to the claimed object is a mixture for the production of sinter, including iron ore material, fuel, flux and organic surfactant, which is used as "Katamine" in the following ratios of ingredients, wt. %:

flux 5-10 fuel 5-10 catamine 0.01-0.03 iron ore material rest

(See RF patent No. 2255125, C22B1/244).

The disadvantage of such a charge is a reduced yield, low quality of the agglomerate, in addition, a high consumption of a binder due to the relatively high particle size of this charge, as a result of which unfilled free volumes are formed between the particles of the charge during the pelletizing process. This leads to a decrease in intermolecular cohesive forces. The relatively high consumption of the binder does not provide optimal compressibility of the mixture. For these reasons, it is not possible to achieve a high level of specific productivity of the sinter plant and the quality of the sinter.

The technical objective of the claimed invention is to increase the yield of suitable agglomerate while improving its quality, as well as reducing the consumption of the binder.

The problem is solved by the fact that in the known mixture for the production of sinter, including iron ore material, limestone, solid fuel and a binder in the form of an organic surfactant, according to the change, it contains an aqueous solution of ethoxylated alkylphenol as a binder in the following ratio of ingredients, wt. %:

limestone 5-10 solid fuel 5-10 ethoxylated alkylphenol 0.06 10 ^-5 -0.07 10 ^-5 iron ore material rest

Oxyethylated alkylphenol - (polyoxyethylene alkylphenyl ether), the technical name for compounds of the general formula RC ₆ H ₄ O (CH ₂ CH ₂ O) n⋅H, where usually R-alkyl C ₇ and above, n>1. Ethoxylated alkylphenol (hereinafter "Neonol AF ₉ -6") is an organic compound in appearance resembling a transparent oily liquid from colorless to light yellow [Lebedev, N.N. Theory of chemical processes of basic organic and petrochemical synthesis. N.N. Lebedev, M.N. Manakov, V.F. Shvets M.: Chemistry, 1984. - 376 p.].

Physico-chemical characteristics of ethoxylated alkylphenol, "Neonol AF _9-6 ":

- density at a temperature of 50 ° C, kg / m ³ 1046 - pour point, °С -17 - self-ignition temperature, °С 412 - mass fraction of water, % no more 0.5 - mass fraction of polyethylene glycols, % no more 1.0 - mass fraction of the main substance, % not less than 98 - maximum permissible concentration, mg/l 1.5 - boiling point, °C 84.5 - melting point, °C 215 - content of the main substance, % 95

It is known the use of ethoxylated alkylphenols in oil production as reagents for hydrophobization of the bottomhole formation zone in order to increase oil recovery; when drilling as stabilizers, regulators of filterability and rheological properties of drilling fluids, accelerators of penetration of rocks and soil structure formers to strengthen the walls of wells; in secondary oil production, binder additives reduce the mobility of water injected into the reservoir, which contributes to better oil displacement from porous rocks.

Also, alkylphenols are used as selective flocculants in the extraction, enrichment of ores and the regeneration of valuable minerals [Mastobaev, B.N. The history of the use of chemical reagents and technologies in the pipeline transport of oil and oil products: Abstract of the thesis. doctor of technical sciences / Ufim. state oil tech. un-t. Ufa, 2003. 50 p.; Abramzon, A.A. Surfactants: Properties and applications / A. A. Abramzon. - 2nd ed., revised. and additional - L.: Chemistry: Leningrad. 1981. 304 p.].

In the claimed mixture, along with the above properties, this additive exhibits a new technical property - it helps to improve the pelletization of the mixture, due to a decrease in the surface tension of water. Concentrating on the phase interface, alkylphenol enhances bonds in the liquid-solid system. The bonding of individual small particles of the charge with an additive solution is due to a kind of "adhesive bridge", which is formed due to the presence of adsorption binder films between the surfaces of the particles. Due to the high surface activity of an aqueous solution of ethoxylated alkylphenol, the elastic resistance of the water film is overcome, intermolecular interaction forces between solid particles increase, resulting in an increase in the size and strength of the resulting granules, thereby improving the lumpability of the charge. This leads to an increase in the gas permeability of the charge layer during sintering, an increase in the quality of the resulting product, i.e. increasing the productivity of the process of agglomeration of iron ore material.

It is known that dispersed systems (in this case, the claimed mixture) are characterized by a large excess of surface energy. At the liquid-solid interface, processes spontaneously occur in the direction of decreasing surface energy (U), equal to the product of surface tension (σ) and surface area (S) [Frolov, Yu.G. Course of colloid chemistry. Surface phenomena and dispersed systems. Textbook for high schools. - 2nd ed., revised. and additional - M.: Chemistry, 1988. - 464 p.]. The product σ·S tends to the minimum value possible for the given system. Solids, as a rule, reduce their surface energy by reducing surface tension, due to the adsorption of other substances. In the claimed invention, the molecules of ethoxylated alkylphenol, being adsorbed on the surface of the particles of iron ore material, help to reduce the dispersion of the medium, i.e. particle coagulation.

When the limestone content in the sinter mixture is less than 5%, the porosity of the agglomerate decreases, as well as the binding of iron oxide FeO to fayalite (2FeO·SiO ₂ ), which degrades the quality of the agglomerate in terms of reducibility.

When the limestone content in the sinter charge is more than 10%, sulfur is absorbed by calcium oxides with the formation of calcium sulfide CaS, which complicates the desulfurization process, thereby reducing the quality of the sinter in terms of sulfur content.

When using solid fuel in the sinter charge less than 5%, the agglomerate turns out to be unbaked and therefore has increased values of abrasion, fines content of 0–5 mm, and sulfur content. Specific productivity becomes lower due to a decrease in the yield of suitable sinter.

When the content of solid fuel in the sinter charge is more than 10%, the sinter has a low reducibility due to a decrease in the porosity of the sinter and the formation of hard-to-recover minerals. Elevated temperatures impair the removal of sulfur from the sinter due to the exothermicity of the desulfurization reactions. The agglomerate is obtained with a high sulfur content. The specific productivity decreases due to the decrease in the vertical speed of sintering due to the excess formation of the liquid phase.

In the claimed ratio of the components of the sinter charge, the use of "Neonol AF ₉ -6" provides the minimum value of the surface energy. The content of ethoxylated alkylphenol in the sintering charge is experimentally set within the range of 0.06·10 ^-5 -0.07·10 ^-5 % by weight. Within these limits, the improvement in charge pelletization is most fully manifested and the best indicators of the sintering process are achieved.

The content of "Neonol AF ₉ -6" in the agglomeration mixture less than 0.06·10 ^-5 % is impractical, since the free surface energy increases due to the increase in the total surface of the mixture. The optimal lumpability of the charge is not achieved, i.e. part of the charge remains non-granulated, the granules are small. The gas permeability of the sinter charge deteriorates, which makes it difficult for air to enter the fuel and leads to a decrease in the specific productivity of the sintering machine.

The content of "Neonol AF ₉ -6" in the agglomeration charge more than 0.07·10 ^-5 % is also impractical. In this case, the free surface energy increases due to the increase in surface tension. The granules are large and not strong. The resulting granules are destroyed in the drying zone during the agglomeration process, which reduces the gas permeability of the mixture and the quality of the resulting product.

To substantiate the advantages of the claimed charge for the production of sinter in comparison with the prototype, tests were carried out on laboratory facilities of the Department of Ferrous Metallurgy of the FGBOU HE “MSTU im. G.I. Nosov" according to the method developed by A.G. Neyasov.

Charge materials were preliminarily prepared. The preparation of the charge for sintering the agglomerate from it consists in weighing the required amount of materials of natural moisture, mixing them, moistening and pelletizing.

The materials were weighed in a strict sequence to avoid errors and “missing” of the material into a separate pan. In addition, 30 g of coke with a fraction of 2-3 mm was dosed into a separate dish, which was subsequently used to ignite the charge.

Next, the mixture was moistened. To do this, pre-dosed water with a binder additive of ethoxylated alkylphenol dissolved in it was sprayed onto the surface of the mixed charge by means of a spray gun. Then the moistened mixture was pelletized. Mixing and pelletizing was carried out in a drum-type pelletizer with an inner diameter of 320 mm and a rotation speed of 30 rpm. An aqueous solution of "Neonol AF _9-6 " was prepared as follows: the required amount of pure ethoxylated alkylphenol was weighed in the initial state and dissolved in 1 liter of ordinary tap water without time exposure until its concentration required in the experiment was obtained (according to the data in Table 2), then the solution was thoroughly mixed to obtain a homogeneous concentration. An aqueous solution of ethoxylated alkylphenol was added directly to the rotating drum during pelletizing in order to achieve the maximum gas permeability of the charge.

To ensure an effective pelletizing process, the dosage of "Neonol AF ₉ -6" in the charge should be 55-68 mg per ton of iron ore material (depending on humidity). The low efficiency of using this binder with a dosage outside the specified range is associated with the peculiarities of the mechanism of interaction of ethoxylated alkylphenols and iron ore materials.

At the first stage of each experiment, the gas permeability of the raw pelletized charge was evaluated on a specialized installation, which included a tin cylinder 310 mm high and 74 mm in diameter with a mesh bottom. A vacuum chamber was located under the grid, connected through a dust collector by a tube with a vacuum cleaner, creating a vacuum in it, thanks to the latter, air was sucked through the charge layer from top to bottom. The charge resistance was evaluated by the value of the coefficient a found from equation (1):

where a is the charge resistance coefficient;

h is the pressure drop in the layer;

ω _about - the amount of air passing through a unit area;

n = 1 for the conditions of the agglomeration process (according to E.F. Vegman and V.I. Korotich) [Bazilevich, S.V. Agglomeration / S. V. Bazilevich, E. F. Wegman. - Moscow: Metallurgy, 1967. - 368 p.; Korotich V.I. Fundamentals of the theory and technology of preparing raw materials for blast-furnace smelting: A textbook for universities on special. "Metallurgy black. Metals. - Moscow: Metallurgy, 1978. 208 p.].

After testing the gas permeability, the mixed and moistened mixture of fine concentrates was sintered in a sintering bowl with a diameter of 70 mm and a height of 250 mm at a rarefaction in a vacuum chamber of 8-9 kPa. In the course of sintering, the values of the main process parameters were recorded at regular intervals. After the end of the sintering process, the contents of the bowl were cooled by sucked air. The resulting sinter was subjected to crushing in a jaw crusher with a gap size of 15 mm, after which it was divided into fractions of 0-5 mm (return) and +5 mm (usable agglomerate). The fit sinter was subjected to a strength test in a rotating tube.

The component composition of the iron ore part of the sinter charge corresponded to the data in Table 1.

Tests have shown that the declared (concentration of 0.5 and 1 mg/l) content of "Neonol AF ₉ -6" provides greater specific productivity, yield, obtaining high quality agglomerate (table 2).

Under the conditions of the prototype, "Katamine" was used as a binder in an amount of 0.02 wt.% with the following ratio of the remaining ingredients, wt.%: flux 7.5; fuel 7.5; iron ore material - the rest. The flux was limestone from the Agapovskoye deposit, and the fuel was coke obtained from coke fines with a fraction of 40-0 mm.

Under the conditions of the proposed method, the composition of the mixture was as follows, wt.%: limestone - 7.5; solid fuel - 7.5; "Neonol AF ₉ -6" - 0.065 10 ^-5 ; iron ore material - the rest. Limestone of the Agapovskoe deposit was used, coke obtained from coke fines with a fraction of 40-0 mm served as solid fuel.

Thus, in the claimed mixture, the quality of the agglomerate has improved, compared with the prototype, the specific fuel consumption has decreased, the yield of good has increased, the yield of fines has decreased. Thus, the use of the claimed mixture will bring a positive economic effect in industrial applications by increasing the quality of the resulting product and saving fuel for the process.

Table 1

The composition of iron ore in the claimed charge

for the production of sinter (and prototype) during testing

Material name Content in the composition of raw materials, % Sinter ore Mikhailovskaya 11.4 Local raw materials: Sludge 5.8 converter slag 0.5 Agglomeloch 2.7 Scale 2.8 Fur-furnace dust 1.3 Total local raw materials 13.2 Concentrate Sokolovsko-Sarbayskoye GPO 39.6 Lebedinsky 3.3 Mikhailovsky 22.9 Kovdorsky 9.5 Total concentrate 75.4

table 2

Sintering process parameters

Concentration of "Neonol AF ₉ -6", mg/l 0 0.2 0.5 1 5 10 Vertical sintering speed, mm/min 14.60 15.01 16.62 15.50 15.43 14.27 Yield, % 75.83 77.4 89.43 80.85 72.33 71.8 Class output + 5 after
tests, % 74.70 79.2 82.17 82.12 74.83 64.63 Specific productivity t / m ² * hour 1.2796 1.3145 1.5091 1.3643 1.2205 1.0945 Drag coefficient, a 1796.55 1559.6 1272.57 1337.23 1558.48 2010.90

Table 3

Key indicators for the production of sinter

in the sintering bowl on the claimed charge and according to the prototype

The name of indicators Prototype Claimed charge 1. Layer height, mm 216 216 2.Vertical sintering speed, mm/min 22.6 16.47 3. Carbon content in the charge, % 3.8 6.5 4. Yield, % 76.4 89.43 5. Specific productivity, t / (m ² ⋅ h) 1.27 1.51 6. Drum,% hit 55.8 82.15 abrasion 5.9 3.9 7. Yield of fines 5-0 mm from the sinter, % 14.2 9.15 9. Basicity of the agglomerate 1.35 1.75

Claims (2)

A mixture for the production of sinter, including iron ore, limestone, solid fuel and a binder in the form of an organic surfactant, characterized in that it contains an aqueous solution of ethoxylated alkylphenol as a binder in the following ratio of ingredients, wt.%: limestone 5-10 solid fuel 5-10 ethoxylated alkylphenol 0.06 10 ^-5 -0.07 10 ^-5 iron ore material rest