SU1073309A1 - Method of sintering concentrates of magnomagnetite and titanomagnetite ores - Google Patents

Abstract

1. The method of sintering of concentrates from magnetically magnetite and titanium-magnetite ores, including their mixing, moistening and pelletization with fuel and flux during the two-stage introduction of fuel into the mixture and rolling in the second stage of the pellet, which is the same pattern, I can use. fuels, in the sintering mixture, containing 2560% of the total fuel used, before the primary mixing, crushed alumina ore is introduced in the amount of 0.08-0.30 wt.h. per unit of concentrate, while the amount of fuel being rolled with an equivalent granule diameter of 1.2-1.7 mm is 40-50%, and with an increase in grain size for every 0.5 mm over 1.7 mm the amount of fuel rolled increase by 10%. 2. Method POP.1, characterized in that before entering the sintering alumina i the ore is crushed together with lime in a ratio (L providing the basicity of the mixture 1.5-2.5 times higher than the basicity of the main mass of the mixture, mixed with fuel -, in the amount of 2.5-3.5% and pelletized to a particle size exceeding the bulk of the ground mass of the pelleted mixture in dj) by 3-5 times, while the amount of the mixture is 10-30% of the mass of the mixture. : o o

Description

The invention relates to the agglomeration of iron ore for ferrous metallurgy. The known method of preparation of charges for which, in order to increase the efficiency of pelletizing and the strength of granules, 2/3 of the ore material is crushed to a content of 80% of particles of a fraction less than 0.4 mm and 1/3 to a content of 80% of particles of a fraction less than 0.08 mm. Fine-grained steel-slag slag in the amount of 2-20, lime up to 10% and cement up to 10% by weight of the charge l is used as a binder. The so-called method of preparing the charge is known, according to which in order to increase the strength of the fluxed pellets, the alumina ore and flux are added to the mixture in a ratio of 0.515% 2. However, the known methods of increasing the efficiency of pelletizing and increasing the strength of the pellets are not acceptable for the production of pellets, but are not very effective for sinter production, since during sintering the mixture its size has a clearly defined maximum size which leads to negative results. The closest to the proposed technical essence and the achieved result is a method of preliminary treatment of the sintering mixture, which includes mixing, moistening and pelletizing of iron ore concentrates with fuel and flux during the two-stage introduction of fuel into the mixture and rolling it in the second stage of pelletizing (Z. Industrial tests show high efficiency of separate fuel injection: when 50% of the fuel is injected with a coarse-grained mixture that does not undergo pelletizing, the very high the unit capacity is 39.9. This is 20.5% more than when all the fuel is introduced into the primary mixer (the specific capacity in this case is 31.7 t / m day). The disadvantage of this method is its low efficiency in relation to magnetite and magnetite magnetite concentrates, the separation of these concentrates into a separate stream does not exceed the degree of their pelletization and does not allow them to produce 75% pellets 1–7 mm in size, since the grain composition of these concentrates does not meet the requirements of high granulation rate. In addition, it is necessary to use special binders, for example bentonite, in the amount of 1.0-1.5% by weight of the charge. This is associated with additional costs for the acquisition and preparation of bentonite and, in addition, the addition of bentonite reduces the iron content in the agglomerate. The purpose of the invention is to increase the efficiency and decrease the specific fuel consumption. The goal is achieved by the method of sintering concentrates from magnetite and titanomagnetite ores, including their mixing, moistening and pelletizing with fuel and flux during the two-stage introduction of fuel into the mixture and rolling it into the second stage pelletizing, in the sintering mixture, containing 25-60% of the total fuel used, before the primary mixing, crushed alumina ore in the amount of 0.08-0.30 parts by weight, per units in concentrate, the amount of fuel being rolled with an equivalent diameter of pellets fc equal to 1.21, 7 mm is 40-50%, and with increasing grain size for every 0.5 mm over 1.7 mm the amount of fuel being rolled increases by 10 % Before entering into the sintering mixture, the alumina ore is preliminary crushed together with lime in a ratio that ensures the basicity of the mixture i, 5-2.5 times higher than the basicity of the main mass of the mixture, mixed with fuel in the amount of 2.5-3.5% and pelletized to size The size of the bulk of the pelleted charge is higher by dji by 3-5 times, while the amount of the mixture is 10-30% of the weight of the charge. . The criterion for the suitability of ore for use as an intensifying additive is recommended to consider the ratio and content of siderite-leptochlorite-hydrohebitic formations, which fine particles have coagulation ability. Ores with the ratio SiOj: Alg0.ji3, 5 should be used as additives. Quantitative limits for the addition of alumina ore are established, based on the results of the study of magnetmagnet concentrates. The beginning of the growth of the granularity of the granules corresponds to 7% of the aluminous crushed ore, which corresponds to the lower limit of the recommended amount of 0.08 parts per one part of the concentrate. . The upper limit, 0.3 parts per one part of the concentrate, corresponds to the beginning of the decrease in the growth curve of the strength of the granules, depending on the amount of crushed alumina ore added to the magnetite magnetites of the concentrate. The degree of pelletizing of the charge, which determines its size, is determined not only by the efficiency of the pelletizing mode, but also by the conditions of teyl and mass transfer. During sintering of concentrates from magnetic and titanomagnetite ores, requiring higher thermal stresses, the optimum size does not exceed,. (djj {) 0qT 1.2-1.5 mm. With such an optimal size, the content of the 0-0.5 mm fraction in the pelletized mixture is 10-15%. This is 5–7 times more than is allowed when sintering concentrates from ferruginous quartzites, and is one of the main factors limiting the intensity of sintering. A part of fuel is offered for sintering a larger particle size (40-75% of the total) enter into the charge at the end of pelletizing by rolling on preformed granules. The accumulated experience of fuel supply at the end of pelletizing shows that with this method of introducing fuel, the temperature in the combustion zone rises, and this intensifies the heat and mass transfer processes. Unlike other 1Sh1Ht sintering of magnetic and titanomagnetite concentrates, the maximum amount. in the rolled fuel does not exceed 75%. In this case, it is required that the degree of granulation of the charge corresponds to the complete absence of frium 0-Q, 5 mm in it. Under the usual process of preparation of the charge, when the content of this fraction is 10–15%, the optimal amount of rolled fuel is 40–50% of the total amount of fuel. And only increase the degree. pelletizing charge, i.e. its size to the level of 2.2-2.7 mm mm shifts the absolute value of the fuel that is optimal to the amount of rolled fuel towards higher values (65-75%). The following relationship was established between the granulometric composition of the pelletized mixture and the optimum amount of fuel (the criteria for the granulometric composition of the mixture were taken d and the content,%, fraction 0-0.5 mm): d g mm 0-0.5 mm. Amount of rolled fuel 1.2-1.7, 10-15 1.7-2.2 5-10 2.2-2.7 0-5 However, the usual sintering mixture containing 65-85% as the iron ore part because of the insufficient amount of the rolled mass (particles less than 0.05 NfMj. And only dabavka crushed material (best of alumina ore) imparts to the charge the ability to pelletize to large sizes. Thus, the recommended parameters of the proposed technology in terms of the amount of crushed, ore and roll This fuel is rigidly interconnected and dictated by the conditions of intensive heat and mass transfer in the furnace.The addition of finely ground aluminous ore provides an increase in the size of the pelleted mixture to dm%. at the end of the pelletizing by rolling. The alumina ore is crushed in a ball mill with lime, and then subjected to pelletizing. The addition of such granules is effective from the point of view of the gas permeability of the layer, starting with 15-20% (by weight of the mixture). At the same time, the maximum size of pelletizing should meet, the condition that the equivalent diameter of the granules (dju) of the ground mixture does not exceed (3-5) of the main mass of the mixture. However, during sintering, the granules from the ground mixture do not undergo complete assimilation by the main mass of the mixture and remain in the cake in the form of calcined pellets. In order to better assimilate the granules of the charge melts, their basicity should be increased higher than the basicity of the main mass of the charge 1.5-2.5 times and add 2.0-3.5% (by weight) of fuel. With such basicity, the main structural component of the crystallized melt is the aluminoferrite phase (a solid solution of calcium alumoferrites of different composition), which ensures a strong adhesion of all the constituent phases of the agglomerate. The added mixture of alumina ore (concentrate from it) and lime due to the high basicity (1.5-2.5 times the basicity of the main mass of the mixture) favors more complete melting of the entire mass of the mixture, and this itself contributes to obtaining high-quality sinter. The requirement for fuel content (2.5-3.5%) is dictated by that, to enhance the efficiency of the mixture as a source of melt formation during

sintering charge. Due to the fact that the mixture is added to the mixture in the form of a coarse-grained material (3-5 times higher than the size of the main mass of the mixture, i5-8.5 mm), in the absence of fuel, the mass transfer processes for it are limited by thermal conductivity. Studies have shown that, in the absence of fuel, the particles (granules) of the mixture remain in the cake unreacted in the form of calcined pellets. With this method of input, the mixture serves only as an intensifier of the sintering process, but does not contribute to the increase in the strength of the cake.

The values of the fuel content in the mixture (2.5-3.5%) were established experimentally. The indicated interval corresponds to the recommended size range of the granulated mixture. This ratio of the mixture size is established on the basis of the data of gas dynamics of bulk materials, prescribing the optimal ratio of the number and size of mixes from the point of view of the maximum free volume

The proposed amount of the mixture (10-30% of the mass of the charge) is due to the requirement to provide the maximum free volume in the sinter layer in order to achieve a higher sintering speed, to obtain high-strength sinter and the requirement of an economic order - the minimum consumption of the added mixture.

From the point of view of the gas permeability of the layer and the quality of the agglomerate, the consumption of the mixture could be increased. But since this mixture is a grinding product, its value will be higher than the cost of other components of the charge. Therefore, the proposed parameters correspond to the quantities whose addition has the greatest effect.

In tab. Figure 1 presents data illustrating the effectiveness of using the proposed parameters of the method of sintering concentrates of magnetite and titanium supernatant ores.

As a base case, the results of sintering Kovdorsky concentrate using conventional technology: alumina ore and lime are set into a mixture before mixing in the usual form in an amount corresponding to 20% of the added mixture (options 2, 5, 6 and 7).

The analysis of the data presented shows that the deviation of the parameters of the mixture of fuel and co-crushed alumina ore (oxidized stahlensk ore from the western wing of the open pit) and the

lime from the proposed leads to a decrease in the efficiency of its use.

Example. The iron ore portion of the charge consists of a concentrate from the Kovdorsky GOK, which is fed to the KLMZ sinter plant.

Grain analysis of the concentrate with mechanical sieving next;

mm

Content of fraction in concentrate,%

5.8 .9.5

7.4 10.2 22.3

2.1

Grain analysis of concentrate during sedimentation sieving,%

nd, mm

Content of fraction in concentrate,%

0.030

30.82 0.010

1.42 0.005

0.22 0.0

- 0,24

The chemical composition of the concentrate,% Fe 62,34; FeO 22.97; CaO 1.30; SiO 1.40; MgO 4.8.

The binder additive used is Stalensk ore (CMA) with the following chemical composition: Re 52.10; PeO 0.80; CaO 0.90; SiOg 11.48; 5.67; MgO 0.50; 2.02.

Two batches of stablesk ore, 10 tons each, are crushed. One of them is crushed without additives (after drying), the other - together with lime in an amount of 100 kg (.% By weight).

Grinding is carried out in an industrial dry grinding ball mill in the ferroalloy shop of NLMZ. Ore without lime is dried before grinding, with the addition of lime it is not dried (, 7%).

Grain a: analysis of crushed ore and a mixture of ore with lime during mechanical sieving is as follows:

Grain analysis of crushed ore during sedimentation sieving is as follows:

Ore,%

Fractions, mm 11.7 0.05-0.030 0.030-0.010 28.9 21.3 0.010-0.005 18.2, 005 -0.0

The following options are explored. batch preparation for sintering.

In the first variant, crushed ore is added to the mixture of Kovdorsky concentrate, flux (Studenovsky limestone), lime 2% and fuel 1.9% (35% of the total). All of the above components of the mixture are mixed, moistened and pelletized. 20 seconds before the end of the pelletizing, the rest of the fuel is introduced into the charge (65% of the total flow rate).

In the second aluminist variance, the ore is crushed in a ball mill together with lime (10,000 kg of ore + 1000 kg of quicklime). After grinding, the mixture is pelleted together with the fuel (.2.5% by weight).

All other components of the process are metered in the usual way, with the exception of fuel, the amount of which is set at the first stage before mixing (50% of the total consumption).

The granular product is introduced into the mixture before pelletizing. 20 seconds before the end of the pelletizing, the residual amount of fuel is introduced into the charge.

For the basic experience, indicators of sintering of the charge prepared according to the conventional technology without the use of special additives and without the use of a topkol rolling are accepted. Return amount in charge

0 in all experiments is 35%, lime 2% ,.

Sintering indicators are presented in table. 2

Analysis of the results of the experiments shows that the proposed sintering technology of the charge provides an increase in specific productivity by 20-40% or 3-5% per kilogram of the addition of crushed alumina ore, a decrease in specific fuel consumption by 7-12%, increase in the strength of the agglomerate by 10- 15%. In addition, a significant decrease in the content of nitrogen oxides in suction gases to 0.05 MVT agglomerate. The degree of oxidation of nitrogen contained in coke is inversely proportional to the sintering rate of the charge; therefore, an increase in the intensity of sintering resulting from an increase in the particle size of the pelletized charge and fuel rolling contributes to a decrease in NOn emissions into the atmosphere, which helps to solve the problem of environmental protection. environment.

Table

Height of oil, mm 220 280 Amount of added mixture Size of pelletized mixture, (, mm 1.28 1.32 Particle size, dj |., Mm Frequency ratio Mainness of the mixture (CaO / SiOj) 1.25 1.25 O 2.0 Mainness mixtures 3.96 3.0 350 400 450 350 350 350 20 20 30 40 1.31 1.28 1.40 1.28 1.28 1.2V 4.58 6.01 7.07 7.04 7.04 5.12 3.5 4.7 5.0 2.5 5.5 5.5 4.0 1.25 1.25 1.25 1.25 1.25 1.25 2.50 3.0 0.50 2, 50 2.50 2.50 Basic multiplicity factor 1, 6 basicity Specific productivity, t / (m / h) 1,310 1,441 1,00 1,10 Same, rel, unit Density of sinter,% 32,00 30,40 1 , 00 0.95 The same, otn.

The amount of fines of 5–0 mm produced during the work of destruction corresponding to the stresses experienced by the production agglomerate on the way to the blast furnace skips. The amount of crushed additives,% Bulk weight of the mixture, kg / m The height of the layer, m Sintering speed, mm / min Same, rel. The yield,% The same, rel. units Specific productivity, .Т (m. H) The same, rel. units Fe content in the agglomerate,% Fuel consumption, kg / t as agglomerate.

, T and l and c and 2 -2,02,4 2,02,02,0 1,0 1,55,66,737 1,703 1,467 1,48,415 1,181,25 1,30 1,12 1,13 1 , 08 29.1228.16 27.8428.4830.72 31.04 0.910.88 0.87 0.89 0.96 0.97

The same, rel. units

1.00

Content in exhaust gases: GOST 15137-77 Note.

.Continued t "bl. 2

0.88

0.93

0.87

0.93 Options 1-1, 1-2 and 11-1.11-2 correspond to two methods of the proposed technology of sintering of magnetic and titanomagnetite concentrates (fn.l and 2 formulas of the invention).

Claims (2)

1. METHOD OF Sintering CONCENTRATES FROM MAGNETO-MAGNETITE AND TITANOMAGNETITE ORES, including mixing, moistening and pelletizing with fuel and flux during two-stage introduction of fuel into the charge and rolling it at the second stage of pelletizing, which is characterized by a decrease in the specificity and hedge reduction fuel consumption, in the sinter charge containing 2560% of the total fuel used, crushed alumina ore in the amount of 0.08-0.30 wt.h. is introduced before primary mixing. per unit of concentrate, while the amount of fuel to be rolled in with an equivalent pellet diameter of 1.2-1.7 mm is 40-50%, and when the granule size is increased for every 0.5 mm in excess of 1.7 mm, the amount of fuel to be rolled is increased on 10%./ 2. The method of pop. 1, characterized in that before entering into the sintering mixture, alumina ore is pre-crushed together with lime in a ratio that ensures the basicity of the mixture in 1.5-2.5 times higher than the basicity of the bulk of the charge, mixed with fuel in an amount of 2.5-3.5% and pelletized to a particle size exceeding the size of the bulk of the pelletized charge by 3-5 times, while the amount of the mixture is 10-30% of the mass of the charge.