BR102016025630A2 - cold sintering cement composition of iron ore fines and its use in the pelletizing process - Google Patents

Abstract

The present invention belongs to the field of special cements, more particularly it relates to a cement for use in cold agglomeration processes of iron ore fines. The present composition is capable of increasing the efficiency of the ore fines agglomeration process by reducing energy consumption, since thermal input to the agglomeration processes is no longer required. thus, the present disclosure discloses a mixture a mixture of clinker and calcium sulfate, corresponding to a concentration range of 98.0 to 100.0%; fluorite in the concentration range from zero to 2.0%; magnesium oxide (mgo) with a concentration of 4,0% or less; sulfur trioxide (so3) with concentration range from 3.5 to 5.0%; carbon dioxide (co2) with a concentration less than or equal to 0.1%; alumina (al2o3), with a concentration less than or equal to 6.0%; calcium oxide (cao) with a concentration range of 60% to 65%; sodium oxide (na2o) with a concentration of less than or equal to 0.25%; potassium oxide (k2o) with a concentration of 1,2% or less; sulfur (s) with a concentration of 0,05% or less; soluble diphosphorus (p2o5) pentoxide with a concentration of 0,05% or less. The present invention further discloses the use of the present cement composition in the cold pelletizing process in a particle size range of 1.0 micron to 0.8 mm iron ore fines.

Description

(54) Title: CEMENT COMPOSITION FOR COLD AGLOMERATION OF IRON ORE FINE AND ITS USE IN THE PELLETIZING PROCESS (51) Int. Cl .: C04B 11/28; C04B 11/30 (73) Owner (s): INTERCEMENT BRASIL S / A., COSTA EMPREENDIMENTOS INDUSTRIAIS LTDA.

(72) Inventor (s): SEIITI SUZUKI; ANDERSON ESTEVES PEREIRA; DANIEL TRAVASSOS DA ROSA COSTA (74) Attorney (s): RICCI & ASSOCIADOS PROPRIEDADE INTELECTUAL S / S LTDA (57) Abstract: The present invention belongs to the field of special cements, more particularly it refers to a cement for use in processes cold agglomeration of iron ore fines. The present composition is able to increase the efficiency of the ore fines agglomeration process by reducing energy consumption, since it is no longer necessary to provide thermal input to agglomeration processes. Thus, this document discloses a mixture of a mixture of clinker and calcium sulfate, corresponding to a concentration range of 98.0 to 100.0%; fluorite in the concentration range from zero to 2.0%; magnesium oxide (MgO) with a concentration less than or equal to 4.0%; sulfur trioxide (SO3) with a concentration range of 3.5 to 5.0%; carbon dioxide (CO2) with a concentration less than or equal to 0.1%; alumina (AI2O3), with a concentration less than or equal to 6.0%; calcium oxide (CaO) with a concentration range of 60% to 65%; sodium oxide (Na2O) with a concentration less than or equal to 0.25%; potassium oxide (K2O) with a concentration less than or equal to 1.2%; sulfur (S) with a concentration less than or equal to 0.05%; diphosphorus pentoxide (P2O5) soluble with co (...)

2/11 agglomeration cohesive bodies or materials are obtained by means of rigid connections between them with a chemical and / or physical basis.

[005] The most used processes for agglomerating iron ores in order to be used as cargo for blast furnaces in the steel industry are: briquetting, sintering and pelletizing.

[006] The briquetting technique was the first agglomeration technique to be used in the recovery and transformation of waste into products with added value. This process allows the formation of solid agglomerates of varying sizes and shapes through the pressure exerted on the ore. In order that the final product of the briquetting (the briquette) has adequate properties, it is necessary, in most cases, the addition of binder. Briquetting can run hot or cold. However, in the state of the art, cold compaction leads to low productivity, thus preventing the use of this process in blast furnaces. In order to provide the desired mechanical strength, heat treatment is very commonly used for briquetting.

[007] Sintering and pelletizing are the most common forms of agglomeration. The decision on whether to use one or the other process depends on the analysis of the physical and chemical parameters of the ore and also on the volume to be processed.

[008] Sintering is based on the incipient fusion of the components of a mixture consisting of a main component and additions of fluxes, promoting the rigid bonding of the particles. In the sintering of fines, heat is used, which makes it possible to transform a fine-grained mass into a load suitable for the blast furnace. Iron ore sintering is preferably carried out with particles from 0.15 to 0.6 mm. The product resulting from sintering is the sinter.

[009] Pelletizing is the agglomeration of fines, between 1.0 micron and 0.15 mm (or 100 mesh) and which are not suitable for sintering. This concentrated ore is sent to the mill, which has the

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3/11 aim to increase the specific surface, that is, further reducing the size of the particles and increasing the reactivity. This grinding reduces the granulometry that was already less than 0.15 mm (or 100 mesh) to less than 44 microns or (325 mesh), which corresponds to about 98% of the bitten material.

[010] Green (or raw) pellets do not have adequate mechanical resistance, which is why it is common to use binders such as bentonite and limestone to give resistance to pellets so that they can move between the pelletizing disc and the ceramic oven grids without mechanical degradation.

[011] Thus, to perform cold agglomeration, resins, cements or tar must be added to provide better mechanical resistance to the pellets, in addition to other properties suitable for use in blast furnaces.

[012] In hot agglomeration, the moistened spheres are still subjected to firing for their hardening. Hot pelletizing of iron ore fines involves temperatures reaching 1,350 ° C. In this way, hot pelletization leads to high energy consumption.

[013] In the current state of the art, bentonite and limestone are used to process the pellet, providing mechanical conditions for the raw pellets to resist the transport of the pelletizing disc to the ceramic grids. In addition, it is necessary that the pellets, at the end of the process, adjust to the desired chemical requirements.

STATE OF THE TECHNIQUE [014] The variation in the composition of the different types of cement makes it possible to add to the mixture some adjuvants that give specific characteristics and performance for each use of the cement.

[015] In the patent literature some documents are found that show the use of cements as binders in several processes and with the addition of various adjuvants.

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4/11 [016] US patent document US4597790 discloses a method of producing pellets without the need for heat treatment. Agglomerates are produced by adding 5 to 30% reduced iron powder, rolling powder or iron sand and also by adding a binder consisting of cement or blast furnace slag granules.

[017] The Brazilian patent document PI 0314315-5 discloses the process of pellet formation containing iron oxide, where the fine particles of iron oxide can be agglomerated by binders. The binding agents described in the document can be organic or inorganic, containing the elements boron or calcium fluoride, improving the resistance of the agglomerated particles.

[018] Patent EP1579016B1 discloses a process for cold briquetting and pelletizing of earth ore ore fines or mineral using iron, having hydraulic mineral binders for metallurgical applications.

scientific or described what revealed at the

[019] Thus, a cement with the composition here does not describe in the scientific literature or patent a cement that provides the agglutinating characteristics revealed here in the cold agglomeration process.

SUMMARY OF THE INVENTION [020] Thus, the cement composition taught here aims at the cold agglomeration of iron ore fines according to the following fractions of the total mass: a mixture of clinker and calcium sulfate, corresponding to a concentration range from 98.0 to 100%; fluorite in the concentration range from zero to 2.0%; magnesium oxide (MgO) with a concentration less than or equal

4.0%; sulfur trioxide (SO3) with a concentration range of 3.5 to 5.0%; concentration less than or equal to concentration less than or equal to carbon dioxide (CO2) with 0.1%; alumina (A12O3), with 6.0%; calcium oxide (CaO) with a concentration range of 60% to 65%; sodium oxide (Na2O) with a concentration less than or equal to 0.25%; potassium oxide (K2O) with

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5/11 concentration less than or equal to 1.2%; sulfur (S) with a concentration less than or equal to 0.05%; soluble diphosphorus pentoxide (P2O5) with a concentration less than or equal to 0.05%.

[021] The present invention also reveals the use of the present cement composition in the cold pelletizing process, in a particle size range of 1.0 micron to 0.8 mm iron ore fines.

DETAILED DECISION [022] The present invention deals with the composition of a special cement with the objective of enabling the cold agglomeration of iron ore fines and, thus, eliminating the thermal consumption of the pellet which is currently 220 Kcal / Kg.

[023] In the pelletizing process of iron ore fines, carried out by means of the need to contribute the composition described here, there is no thermal to the pellets and the granulometric range of the iron ore fines can be more elastic, between 1.0 microns and 0.8 mm as opposed to the range described in the prior art which is between 1 micron and 44 microns (less than 2%). This property of the cement composition taught here reduces the energy consumption for commercial processes from 55 KWH / Ton to 8 KWH / Ton. Thus, the present cement composition has an alternative design, capable of generating a porous agglomeration, but based on the technique of concrete micros. Concrete micros are those with reduced particle size.

[024] The special cement composition described here allows to meet the mechanical, chemical and metallurgical parameters required for the pellets suitable for feeding pig iron blast furnaces, as well as the production of mini pellets for the production of sinter.

[025] The composition taught here has chemical and physical parameters capable of providing a new and surprising technical effect which is the possibility of agglomerating particles of fine iron ore of larger granulometry for the

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6/11 pelletizing, providing great energy savings also in the grinding process.

[026] The chemical composition of the special cement of this invention mainly presents a mixture of clinker plus calcium sulfate, corresponding to a concentration range of 98.0 to 100.0% of the total mass. This concentration range ensures pellet resistance.

[027] Another component of the formula is fluorite, which in the present composition has a concentration range from zero to 2.0% of the total mass. Fluorite has the property of acting as a fluxing agent helping in the process of guseification and scorification.

[028] The other components are: magnesium oxide (MgO) with a concentration less than or equal to 4.0% of the total mass; sulfur trioxide (SO3) with a concentration range of 3.5 to 5.0%; carbon dioxide (CO2) with a concentration less than or equal to 0.1%; alumina (A12O3), with a concentration less than or equal to 6.0% of the total mass, with preferential concentration less than or equal to 5.0%,

that component, in this range concentration, improves scorification; oxide in calcium (CaO) with strip concentration 60% The 65% of the total gives pasta. [029] THE composition in cement is still characterized by absence of materials carbonates. The materials carbonates

in most cement compositions it provides a more workable mixture, serving as a lubricant between the particles of the other components of the cement, in addition to reducing the capillarity and permeability of mortars and concretes. However, in the present special steel cement, to meet the requirement related to pellet swelling, which concerns the geometric behavior of the iron when it changes to the metallic form (needling), post-reduction, the presence of limestone has been eliminated, reducing the index of steel basicity in the pellet to the minimum level of (<0.03), bringing the actual swelling to less than 15%.

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7/11 [030] The presence of alkalis has also been limited. The alkalis remaining in the special cement meet the maximum limits required for the good running of the furnaces, in addition to being in the form of sulphates, therefore easily extractable in the slag.

[031] Thus, the composition taught here starts from some premises. The current basicity index considered by the industry is stoichiometric, that is, equal to CaO / SiO2. This index impacts the needling shape that occurs when reducing hematite (Fe2O3) to iron (Fe).

[032] The graph in figure 1 shows the swelling curve resulting from the basicity index (Meyer, Kurt. Pellotizing of Iron Ores. 1980). It is observed that between 0.1 and 0.8 is when the highest rates of swelling are observed. By eliminating carbonate addition, this index is strongly reduced, which is known as the steel basicity index, that is, the one that disregards the CaO present in cement silicates and considers only free CaO.

Example:

[033] For a free CaO cement of 1.5% we have: 1.5 x 0.075 (percentage of binder in the mixture) which results in 0.1125.

[034] Therefore, if the silicon dioxide (SiO2) in the pellet is 7.5% and, disregarding the part present in cement silicates, we have the same approach, that is: 7.5 - (22 x 0.075 ) = 5.85.

[035] This way, the steel basicity index = 0.1125 / 5.85 = 0.0192 is reached. When referring to the graph in figure 1, for this steel index the swelling is approximately 15%.

[036] In addition, in the present composition, alkalis: sodium oxide (Na2O) and potassium oxide (K2O) are kept in low concentrations, with the objective of protecting the blast furnace. Alkali contributes to the following harmful effects at high

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Invention Patent Descriptive Report for CEMENT COMPOSITION FOR COLD AGGLOMERATION OF IRON ORE FINE AND ITS USE IN THE PELLETIZING PROCESS

FIELD OF THE INVENTION [001] The present invention belongs to the field of special cements, more particularly it relates to a cement for use in cold agglomeration processes of iron ore fines. The present composition is capable of increasing the efficiency of the ore fines agglomeration process by reducing energy consumption, since, when using the cement taught here, there is no longer a need for thermal input in the pelletizing processes. In addition, pellets produced with special cement are capable of meeting the mechanical, chemical and metallurgical parameters required for the supply of pig iron blast furnaces, as well as in the production of mini pellets for the production of sinter or even to carry out briquetting.

HISTORY OF THE INVENTION [002] Most of the minerals present in the rocks are very useful in our daily lives, being applied in different economic sectors. The search by emerging countries for basic infrastructure, transportation and the modernization of the industrial park promoted an increase in the demand for pig iron.

[003] In order to produce pig iron in adequate quantities the agglomeration process has an important role. The main objective of the ore agglomeration is to give the loads, to be fed into the blast furnace, an adequate shape and also the appropriate mechanical resistance to the course of that load in the blast furnace, with the percolation of gases by the load.

[004] In metallurgy, the term agglomeration lends itself to designate operations applied to fine-grained ores that are not suitable for feeding blast furnaces. So, with the

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8/11 furnace: formation of pellets, irregular drop in the load, attack on the refractory lining and increased thermal losses in the furnace and reduced slag viscosity.

[037] Thus, sodium oxide (Na20), in this composition, has a concentration less than or equal to 0.25% of the total mass, preferably less than or equal to 0.15% and potassium oxide (K2O) with a concentration less than or equal to 1.2% of the total mass.

[038] In addition, sulfur (S) and diphosphorus pentoxide (P2O5) have been reduced to a maximum of 0.05% in this composition. The pig iron clean of these elements harmful to steel is more valued, as it avoids treatments in the melt shop to reduce these elements to acceptable levels, which are expensive.

[039] Thus, sulfur (S), in the present composition, has a concentration less than or equal to 0.05% of the total mass and the soluble diphosphorus pentoxide (P2O5) with a concentration less than or equal to 0.05% of the total of the dough.

[040] That is, both sulfur (S) and diphosphorus pentoxide (P2O5) worsen scoring. These components are undesirable to pig iron, since they require complementary and expensive treatments in the next phase of obtaining the steel.

[041] In addition, insoluble residues in the present composition must be less than or equal to 1.0% and the loss to fire less than or equal to 2.0%, preferably less than or equal to 1.5%, according to procedures described in NM 15: 2012 and 18: 2012, respectively.

NM [042] It is important to highlight that alumina (A12O3), sodium oxide (Na2O) and potassium oxide (K2O), in the concentration ranges taught here, play an important role in the present steel cement composition, as they greatly improve the scoring.

[043] The chemical parameters summarized for the present cement are found in table 1.

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11/11 [048] The manufacture of pellets, with the present composition of steel cement allows the necessary chemical-stoichiometric balance, since the rich calcium silicates, at temperatures of the order of 1,050 ° C, provide CaO for the proper removal of silicon and aluminum oxides, through scorification, facilitated by the intimate contact established by the good mixing and consequent packaging of the materials by the present cement composition.

[049] Thus, the composition taught here provides the following results to the pellets.

Table 4: Comparison of the results obtained with the standard.

ITEM STANDARD RESULT Pellet produced with gift steel cement Kgf compression res (test method ISO 4700) Average 150 Average 145 Drumming -% (ISO test method 3271) > 90 > 95 degradation rate under reduction (RDI) -% (ISO 13930) > 80 > 90 Swelling-% (ISO4698) <20 <15 Reducibility-% (ISO7215) > 70 > 75 Scoring Normal High Softening & melting Normal Normal

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Table 1: Chemical parameters of the composition, preferred ranges and comparison with CP I cement, in addition to the characteristics of each component.

Components Banner preferential Specification cement Special (% by weight) NBR 5732 (CP I) Feature Clinker + Calcium Sulfate -% 98.0 to 100 98.0 -100.0 100.0 Essential to ensure the least swelling (a) and highest resistance Improvement O Not there softening gives Fluorite -% 0.5 to 2.0 0.0 to 2.0 pellet and reduces the temperature of Fusion Material Carbonate - O 0.0 0.0 Same (a) Insoluble Residue -% <= 1.0 <= 1.0 Loss to fire O <= 1.5 <= 2.0 <= 2.0 Same (a) MgO -% <= 4.0 <= 6.5 SO3 -% 3.5 to 5.0 <= 4.0 CO2 -% <= 0.1 <= 1.0 Same (a) A12O3 -% <= 5.0 <= 6.0 Not there Improves scoring The (B) Dog - % 60 to 65 Not there Na2O -% <= 0.15 <= 0.25 Not there ditto (b) K2O -% <= 1.2 Not there ditto (b) Not Element S - % <= 0.05 there undesirable · steel, worsens at the The scorification (Ç) Soluble P2O5 O <= 0.05 Not there Same (c)

[044] The above composition must also present the following physical parameters: residue in the 75 micron sieve less than 0.1%; fineness in the 325 micron sieve less than 1.0%; specific area of 520 to 600 m ² / kg, with a preferential range of 560 to 600 m ² / kg; the above characteristics increase the pellet strength.

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10/11 [045] As a consequence, the present cement must present mechanical resistance to compression to a day greater than or equal to 30; mechanical resistance to compression for three days greater than or equal to 37; mechanical resistance to compression at seven days greater than or equal to 42, according to table 2.

Table 2: Physical parameters of special cement for use in the cold pelletizing process of iron ore fines.

Parameter Specification Residue on sieve 75 microns -% <0.1 Sieve fineness 325 microns -% <1.0 Specific Area - m2 / kg 520 to 600 Resistance to 01 days - Mpa > 30 Resistance to 03 days - Mpa > 37 Resistance to 07 days - Mpa > 42 [046] Physical parameters give the binder cement

better results for grain thickness and compressive strength, preferably within the following ranges: residue in the 75 micron sieve less than 0.1%; fineness in the 325 micron sieve less than 1.0%; preferential specific area of 560 to 600 m ² / kg.

[047] The present cement must also present mechanical resistance to preferential compression to a day greater than or equal to 30; mechanical resistance to compression preferential to three days greater than or equal to 40; mechanical resistance to compression preferential to seven days greater than or equal to 45, according to table 3.

Table 3: Preferred physical parameters of the special cement that gives the best results for grain thickness and resistance to compression.

Parameter Better efficiency Residue on sieve 75 pm -% <0.1 Fineness in the sieve 325 pm -% <1.0 Specific Area - m ² / kg 560 to 600 Resistance to 01 days - Mpa > 30 Resistance to 03 days - Mpa > 40 Resistance to 07 days - Mpa > 45

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2/3 characterized by the fact that alumina (A12O3) has preferential concentration less than or equal to 5.0% of the total mass.

7) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that sodium oxide (Na20) has preferential concentration less than or equal to 0.15% of the total mass.

8) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that potassium oxide (K2O) has preferential concentration less than or equal to 1.2% of the total mass.

9) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that it comprises the following physical parameters: residue in the 75 micron sieve less than 0.1%; fineness in the 325 micron sieve less than 1.0%; specific area of 520 to 600 m ² / kg.

characterized by

10) The cement composition for cold agglomeration of iron ore fines, according to claim 9, characterized by the fact that it comprises a preferential specific area of 560 to 600 m ² / kg.

11) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that it has mechanical resistance to compression for one day greater than or equal to 30; mechanical resistance to compression for three days greater than or equal 37; mechanical resistance to compression to seven days greater than or equal to 42.

12) The cement composition for the cold pelletizing of iron ore fines, according to claim 10, the fact that the present cement preferably presents greater or equal mechanical strength, compression to one day compression

30; mechanical resistance to preferential three days greater than or equal to 40; preferential mechanical resistance to compression for seven days greater than or equal to

45.

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Claims (6)

1) A cement composition for cold agglomeration of iron ore fines characterized by comprising a mixture of clinker and calcium sulfate, corresponding to a concentration range of 98.0 to 100%; fluorite in the concentration range from zero to 2.0%; magnesium oxide (MgO) with a concentration less than or equal to 4.0%; sulfur trioxide (SO3) with a concentration range of 3.5 to 5.0%; carbon dioxide (CO2) with a concentration less than or equal to 0.1%; alumina (A12O3), with a concentration less than or equal to 6.0%; calcium oxide (CaO) with a concentration range of 60% to 65%; sodium oxide (Na2O) with a concentration less than or equal to 0.25%; potassium oxide (K2O) with a concentration less than or equal to 1.2%; sulfur (S) with a concentration less than or equal to 0.05%; soluble diphosphorus pentoxide (P2O5) with a concentration less than or equal to 0.05% of the total mass. 2) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that fluorite has a preferential concentration range of 0.5 to 2.0% of the total mass. 3) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that insoluble residues are less than or equal to 1.0%. 4) The cement composition for cold agglomeration of iron ore fines, according to claim 1, characterized by the fact that the loss to fire is less than or equal to 2.0%. 5) The cement composition for cold agglomeration of iron ore fines, according to claim 4, characterized by the fact that the loss to fire is preferably less than or equal to 1.5%. 6) The cement composition for cold agglomeration of iron ore fines, according to claim 1, 23/27 3/3 13) Use, of the cement composition of claim 1, characterized by the fact that said use is in a cold pelletizing process. 14) Use of the cement composition, according to claim 13, characterized by the fact that said composition is used in the cold pelletizing process in a particle size range of 1.0 micron to 0.8 mm iron ore fines. 25/27 1/1 Inchanento (%) Basicity trdfce (State of the Art)