RU2345150C2 - Charge used for agglomerate manufacture - Google Patents

Abstract

FIELD: metallurgy industry.

SUBSTANCE: invention refers to ferrous metallurgy, and namely to agglomerate manufacture, and can be used when iron-ore raw material is being prepared for metallurgical treatment. Charge consists of iron-ore concentrate, iron-bearing material, lime, small-sized coke, and slag metal-oxide concentrate. Charge component ratio is the following, wt %: iron-bearing material - 12-30, lime - 4-9, small-sized coke - 3-5, slag metal-oxide concentrate - 7-18, and iron-ore concentrate - the rest. Grain size of slag metal-oxide concentrate is up to 1 mm, and it contains slag metal mixture obtained from processed steel-making slags - 3-20%, and iron-ore half-finished product - the rest. Beneficiated iron ore is used as iron-ore half-finished product. Blast furnace dust, blast furnace and steel-making slags, scale, screenings of agglomerate and pellets are used as iron-bearing material.

EFFECT: reducing content of expensive iron-ore concentrates in the agglomerate charge, and reducing solid fuel consumption with agglomerate strength properties maintained.

3 cl, 3 tbl, 1 ex

Description

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

The increase in the production of sinter with a high iron content without large capital investments is a problem for many metallurgical plants.

A known mixture for the production of iron flux and a method for its production [1], containing slag from steelmaking and iron-containing additives, in addition, with the aim of utilizing metallurgical waste and increasing the strength of granules as iron-containing additives, it contains scale and screening of sinter and pellets in the following ratio of components, the weight.%:

- steelmaking slag - 30-50 - scale - 10-20 - screening of agglomerate and pellets fractions 0.1-3.5 - the rest.

Known mixture for agglomeration of iron-containing materials containing dust and scale, and also additionally contains steel sludge and lime, in the following ratio of ingredients, wt.% [2]:

- steel sludge - 10-30 - blast furnace slurry - 20-40 - dust - 20-40 - scale - 5-15 - steelmaking slag - 5-15 - lime - 5-20.

The disadvantage of these charges is the low strength characteristics of the agglomerates, as well as the unstable content of iron. The agglomerate shipped from the sintering plant is subsequently subjected to predominantly abrasive loads upon delivery to the blast furnace during the interaction of the pieces during transportation and lowering in the bunkers of the blast furnace. In this case, predominantly dusty fractions are formed, break off and pass into the fines cantilever sections of the lumpy product.

A known mixture for the preparation of material for metallurgical production, containing components at their ratio, in wt.%: As a carbon-containing material - powdered iron carbide 75-85, iron-containing material 12-18, as a binder - freshly prepared calcium and / or magnesium hydroxide 3 -7. The mixture contains iron ore concentrate, blast furnace dust, and slag of ferrovanadium production as iron-containing material [3].

The disadvantage of this mixture is that when introducing briquettes from the proposed mixture into the steelmaking unit, unwanted impurities, for example, phosphorus, sulfur, etc. are introduced.

The closest technical solution to the claimed is a mixture for the production of sinter, including iron ore concentrate, iron-containing material, limestone, solid fuel, and additionally contains a vanadium-containing metal product for processing slag dumps. The ratio of ingredients in the charge is as follows, wt.%: Iron-containing material 15-40, limestone 3-8, solid fuel 4-7, vanadium-containing metal product for processing slag dumps 4-12, iron ore concentrate - the rest. The fineness of the vanadium-containing metal product is up to 10 mm. As the iron-containing material used metallurgical dust, sludge blast furnace, returns sinter and blast furnace [4].

A positive result of this technical solution is the possibility of using metallurgical waste, in particular products of processing slag dumps, in the sinter mixture, which improves the environmental situation of metallurgical enterprises.

The disadvantage of the prototype is the low iron content in the metal product (about 50%), which leads to the additional introduction into the charge of expensive high-iron materials-concentrates, as well as to increased fuel consumption.

The technical result of the invention is to reduce the content of high-cost iron ore concentrates in the sinter mixture, reduce the consumption of solid fuel, and also increase the strength characteristics of the sinter.

The technical result is achieved due to the fact that the composition of the charge of the sinter is additionally introduced slag metal oxide concentrate, in the following ratio of the ingredients of the charge, wt.%:

- iron-containing material - 12-30 - slag metal oxide concentrate - 7-18 - limestone - 4-9 - coke breeze - 3-5 - iron ore concentrate - the rest,

while the slag metal oxide concentrate contains, wt.%:

slag-metal mixture from the processing of steelmaking slags 3-20, iron ore intermediate - the rest, in addition, the size of the slag metal oxide concentrate is 0-1 mm,

enriched iron ore is used as an iron ore intermediate, and blast furnace dust, blast furnace and steel sludge, scale, screenings of sinter and pellets are used as iron-containing material.

The invention consists in the following.

Waste treatment at the factory site does not always allow to utilize all iron-containing components, due to the impossibility of direct involvement in the smelting due to the low iron content in the raw materials.

These circumstances require the involvement of these wastes as additives in the sintering process. The most effective additive in the agglomeration process is a slag metal oxide concentrate having the following chemical. composition,%: Fe 58.5-64.0, FeO 34.6, Fe ₂ O ₃ 43.5, CaO 10.0, SiO ₂ 8.0, AlO ₃ 2.0, S 0.09, C 1 , 3, MgO 5.3, V ₂ O ₅ 0.6, MnO 2.02, P ₂ O ₅ 0.21, as well as a small content of TiO ₂ , Cu, Zn, Na ₂ O.

Slag-metal oxide concentrate is obtained by joint grinding to a fraction of 0-1 mm and subsequent wet magnetic enrichment of the following components: slag-metal mixture from the processing of steelmaking slag and iron ore intermediate. The iron content in the concentrate is at least 58%.

Iron ore intermediate is an enriched iron ore with an iron content of 35-45%.

The introduction of components useful for the agglomerate at the stage of formation of the concentrate determines their more uniform distribution in the sinter charge, and therefore better sintering ability, strength, and stability of the quality of the agglomerate. The addition of a slag-metal mixture to obtain a concentrate fulfills this task, while CaO, MgO, MnO, V ₂ O ₅ , etc. are additionally introduced into the sinter.

The slag metal oxide product used for the sintering charge contains ferrite-type compounds (MgO, FeO, SiO ₂ ), (MgO, FeO, V ₂ O ₅ ).

Under the agglomeration process, when heating and high-temperature processing of materials lasts for a very short time, the presence of ready-made compounds that do not require time for solid-phase processes contributes to their rapid melting and the formation of slag bundles uniformly distributed over the agglomerate structure. Such agglomerates are durable both in the initial state and during reduction. The improvement of the physical and mechanical properties of the agglomerates is facilitated by the uniform distribution of ferrite and other ligaments preformed at the stage of firing-magnetic enrichment.

The chemical composition of the charge materials is shown in table No. 1.

Improving the process of forming the ligament helps to reduce fuel consumption for the production of sinter, increase its quality in general.

The limits of the content of solid fuel in the mixture are determined by the strength and reducibility of the sinter.

The decrease in fuel content (coke breeze) in the mixture below 3.0 wt.% Does not provide the sintering process, which leads to a decrease in the strength characteristics of the sinter.

An increase in the content of coke breeze in the sinter charge above 5.0 wt.% Leads to a decrease in the cold strength of the sinter due to an increase in the content of ferrous oxide.

The limits of the content of limestone in the mixture due to the basicity of the sinter, equal to 1.1-1.3. With less than 4% limestone content, the basicity of the sinter will be less than 1.1%, while in the blast furnace process additional input of limestone is necessary, which leads to an increase in coke consumption and a decrease in furnace productivity. With a greater than 9% limestone content, the basicity of CaO / SiO ₂ agglomerate exceeds 1.3. The increase in limestone content above 9.0 wt.% Leads to a decrease in the strength properties of the agglomerate.

The introduction of a slag metal mixture (SHMS) in the production of a concentrate of less than 3% does not give tangible results on sintering of sinter charge and the necessary increase in components useful for sinter (CaO, MgO, MnO, V ₂ O ₅ ).

A higher proportion of SHMS - more than 20% increases the output of the "tailings", also increases energy consumption when grinding components of the concentrate.

The indicated limits of the charge components correspond to the need to concentrate the binder compositions in the crystallization regions of ferrite solid solutions corresponding to equilibrium systems of the CaO - FeO - MgO - V ₂ O ₅ - SiO _{2 type} . The optimum content of the slag metal oxide concentrate in the mixture was experimentally established, namely, the best results on the strength of the sinter and its reducibility were obtained with a content of slag metal oxide concentrate equal to 7-18% and a particle size of 1-0 mm and containing: slag metal mixture from the processing of steel sludge in an amount 3-20% and iron ore intermediate in the form of enriched iron ore.

The results of experimental sintering of sinter with the addition of slag metal oxide concentrate are shown in table No. 3.

The sintering method of the agglomerate is as follows.

When preparing materials for sintering, stacks are formed that are mixtures of concentrates of different iron contents and iron-containing materials.

Mixtures from each stack are fed into a feed hopper.

Fluxes (limestone and lime) and coke breeze are fed directly into the bunkers of the charge compartment intended for them in order to precisely control the basicity of the sinter in relation to CaO / SiO ₂ .

The mixture mixed in the drum with the return formed after screening the cake is pelletized and laid on a conveyor sinter machine with a layer height of 200-400 mm corresponding to the type of draft devices. Solid fuel mixture in the form of coke breeze ignite when passing the conveyor under the mountain with gas burners. The ignition temperature is 1100-1150 ° C. After ignition, the mixture is sintered by sucking air through the layer under the influence of a fan (exhauster), which develops a maximum vacuum of 600-1100 mm of water. Art. The speed of sintering is controlled by the maximum temperature at the end of the sintering zone 120-150 ° C and is controlled by the absence of noticeable amounts of residual carbon in the sinter.

After leaving the conveyor, the cake is subjected to crushing and screening with the release of substandard return with a particle size of 5-0 mm. The main fraction of more than 5 mm is sent to the consumer in the blast furnace shop.

Example 1

Iron ore concentrate, metal-containing material, limestone and solid fuel (coke breeze) were mixed, moistened, pelletized and sintered on an sinter machine. The height of the charge layer was 335 mm. The amount of limestone and coke breeze in the charge was 4.0–9.0 and 3.0–5.0%, respectively. To improve the strength characteristics of the agglomerate, a slag-metal oxide concentrate for processing metallurgical waste was added to the charge in an amount of 7-18%, with a grain size of 0-1 mm. The moisture content of the slag metal oxide concentrate was 3-5%. The charge was ignited by the combustion products of a propane-butane mixture in air with a temperature of 1150 ° С. After cooling, the sinter was subjected to drum tests to determine mechanical strength.

After processing in a drum, the material was dispersed on sieves to determine the number of fractions +5.0 and -0.5 mm. The strength of the finished agglomerate was determined in a standard drum according to GOST 15137-77 with an assessment of the yield of cells. more than 5 mm and abrasion - cl. less than 0.5 mm.

The strength of the agglomerate after recovery and the degree of recovery at 800 ° C were determined in a Linder-type installation in accordance with GOST 19576-76. The viscosity of blast furnace slag during sinter melting was calculated using a special PC program compiled on experimental viscosity diagrams in the CaO-SiO ₂ - Al ₂ O ₃ - MgO system.

The test results are shown in table No. 2 and No. 3.

The analysis of the results of agglomerate tests shows that the use of slag metal oxide concentrate increases the yield by 0.7 to 0.75-0.78 kg / m ² , the sintering time of the agglomerate decreases from 17.25 min to 15.5-15.8 min (see table. No. 3), the strength in the drum (impact resistance) from 63.6 to 68.9%, the sulfur content does not exceed 0.070%, the consumption of coke breeze decreases from 7.7 to 3-5%.

A pilot test of the sinter was carried out on a blast furnace No. 5 of the Nizhny Tagil Metallurgical Combine. Agglomerate contributed to the improvement of the process of slag formation in the furnace and reduced the viscosity of the final blast furnace slag, due to which an improvement in the separation of smelting products at the outlet from the furnace was achieved and losses of pig iron and slag were significantly reduced. The decrease in the viscosity of blast furnace slag occurred due to the lesser formation of titanium carbonitrides in the furnace and granulated, due to the favorable chemical composition of the slag metal oxide concentrate, its low melting point (1250-1300 ° C), and good fluid mobility in the molten state. The slag viscosity decreased from 0.30 to 0.22 Pa · s, which ensured a decrease in the concentration of metal in the slag at the outlet from the furnace by 11-23%.

Thus, the tests of the inventive charge showed that the addition of slag metal oxide concentrate for processing metallurgical waste and enriched iron ore in the range of 7-18% and a particle size of 0-1 mm in the sinter charge of VGOK allows to increase the productivity of machines upon receipt of a strong agglomerate with a low viscosity formed when its melting slag. Increasing the strength of the sinter obtained by the claimed technical solution, while reducing the viscosity of the slag will provide an improvement in the technical and economic indicators of blast-furnace melting.

Thus, the proposed technical solution meets the criterion of "novelty." The analysis of patents and scientific and technical information did not reveal the use of new significant features used in the present invention for its functional purpose.

Therefore, the present invention meets the criterion of "inventive step".

The proposed version of the charge for the sinter was tested at JSC Vysokogorsky mining and processing plant.

Information sources

1. A.S. 713919, С22В 1/24, publ. in BI No. 5, 1980.

2. A.S. 630301, С22В 1/14, publ. in BI No. 40, 1978.

3. RF patent No. 2103377, C21C 5/28, C21C 5/52, publ. 01/27/1998.

4. RF patent No. 2281976, C22B 1/16, publ. 08/20/2006.

Table number 1
The chemical composition of the main components of the sinter charge when checking the proposed technical solution Items Mass fraction of elements in sinter charge components,% Iron material Slag metal oxide concentrate Iron ore concentrate Limestone Coke trifle Fe commonly 48.5 58.5-64.0 61.5 - - FeO 10.5 34.6 23.6 - - Fe ₂ O ₃ 58.0 43.5 62.0 - - CaO 5.9 10.0 1.8 54.3 5,4 SiO ₂ 6.1 8.0 5.2 1,2 42.8 MgO 6.8 5.3 1,6 0.5 2,4 MnO 1,1 2.02 0.6 - - S total 0.2 0.09 0.3 0.04 0.2 RFP 8.7 4,5 1.4 41.0 - Σ oxides 97.3 96.02 95.1 -

Table number 2 Examples The composition of the mixture,% Agglomerate Strength Indicators Sulfur content,% Iron ore concentrate Limestone Coke trifle Iron material Slag metal oxide concentrate Impact resistance, fraction output +5 mm,% Abrasion resistance, fraction yield - 5 mm,% Famous 53.5 9.2 7.7 28.6 - 63.6 8.5 0,072 one. 47.7 8.6 5.7 31.5 6.5 65.5 7.7 0,077 2. 52.8 7.8 4.4 23.0 12.0 65,2 8.6 0,078 3. 46.2 7.0 4.3 25.0 17.5 67.7 8.8 0,069 four. 50.3 6.5 5,0 22.2 16,0 68.9 8.5 0,070 5. 47.1 5,0 4.8 26.3 16.8 67.8 8.6 0,068 6. 44.9 6.9 4.7 29.0 14.5 66,2 8.9 0,071 7. 54,4 8.4 5.2 14.0 18.0 63.5 8.2 0,077 8. 46.3 9.1 6.0 31,0 7.0 62.8 8.1 0,079

Table number 3
The results of experimental sintering of sinter with the addition of slag metal concentrate Indicators Basic indicators The use of slag metal concentrate, in% 7 eleven eighteen 1. The layer of the charge, mm 335 335 335 335 2. Moisture charge,% 6.8 6.5 6.2 6.7 3. The temperature of the mixture, ° C 74 75 75 74 4. Sintering time, min 17.25 16,4 15,5 15.8 5. Sintering speed, mm / min 19,4 20.5 21.6 24.7 6. Productivity, kg / m ² 0.7 0.73 0.78 0.75 7. The chemical composition of the agglomerate, ppm Fe 58.5 59.9 58.6 57.5 ppm FeO 30.5 31,4 31.3 31,0 8. Ud. productivity, kg / m ² 0.80 0.82 1,08 1,04 9. The degree of pelletization,% 33.6 35.8 39.2 36.6

Claims (3)

1. The mixture for the production of sinter, including iron ore concentrate, iron-containing material, solid fuel in the form of coke breeze and limestone, characterized in that it additionally contains slag metal oxide concentrate in the following ratio of ingredients, wt.%:
iron material 12-30 slag metal oxide concentrate 7-18 coke breeze 3-5 limestone 4-9 iron ore concentrate rest
while the slag metal oxide concentrate consists of 3-20 wt.% slag metal mixture from the processing of steelmaking slag and iron ore intermediate, the rest, and the fineness of the slag metal oxide concentrate is up to 1 mm. 2. The mixture according to claim 1, characterized in that the iron ore intermediate used enriched iron ore. 3. The mixture according to claim 1, characterized in that as the iron-containing material used blast furnace dust, blast furnace and steel sludge, scale, screenings of sinter and pellets.