WO2019033187A1

WO2019033187A1 - Process of cold pelletization of iron-ore fines with mixture flexibility

Info

Publication number: WO2019033187A1
Application number: PCT/BR2018/050264
Authority: WO
Inventors: Daniel TRAVASSOS DA ROSA COSTA
Original assignee: Travassos Da Rosa Costa Daniel
Priority date: 2017-08-16
Filing date: 2018-07-31
Publication date: 2019-02-21
Also published as: BR102017017535A2

Abstract

The present invention patent pertains to the iron-ore treatment sector and relates to a process of cold pelletization of iron-ore fines with mixture flexibility, with a grain size range of zero to 6.4 mm, said fines being inevitably generated by miners and steel industries, which currently have as options for agglomerating said fines processes such as sintering, ceramming or hot pelletization and briquetting. The present invention describes a process of cold pelletization and an industrial plant suitable for carrying out the process of producing ore pellets.

Description

"COLD PELOTIZATION PROCESS OF IRON ORE FINES

WITH MIXTURE FLEXIBILITY "

The present patent applies to the treatment segment of iron ore and refers to the process of cold pelletizing of iron ore fines, with a grain size range of zero to 6.4 mm, fines which are compulsorily generated by miners and steel industries that currently have as options to agglomerate these fine processes such as sintering, ceramization or hot pelleting and briquetting. They are costly and operationally complex processes. The present invention features a cold pelletizing process and an industrial plant suitable for the production of ore pellets.

[02] Currently the steel industry, which has as its first stage of production pig iron obtained through blast furnaces, demands granulated materials to feed them that are supplied by the mining industry, which in turn, by benefiting the ore generates large amount of fines, either by the comminution of the minerals found, or by the need to concentrate them. These fine, sinter feed and pellet feed, meet the needs of sintering and pellet production through the process of ceramization or hot pelletizing.

[03] It is imperative to agglomerate these fines, so that they fit in shape and granulometry and thus the blast furnaces can be fed. For that, the known processes, described below, are used.

[04] Sintering: agglomerates materials in the granulometric range from 0.15mm to 6.4mm (sinter feed). It is a classic process that allows the particles to be bonded through a thermal process until the incipient fusion of the components of a mixture of iron ore fines and additions of fluxes, promoting the bonding of the particles. The product generated, called sinter cake, is crushed again so that the material reaches the size suitable for blast furnace feeding. In this fragmentation there is intense generation of fines, reaching up to 30%, which implies reprocessing and high costs. The sintering is installed in the steel complex itself, because the sinter does not have mechanical resistance to resist travel and transhipments. It has limitations in absorbing fines below 0.15mm due to the permeability of the material to be sintered.

[05] Hot pelletizing / ceramization: uses the pellet feed as raw material, which after fine grinding is available in granulometry 98% lower than 44 micronm. This high specific surface condition allows for the ceramization performed in this process. In order to make the bead possible, various binders, such as bentonite, resins, limestone and even cement, are used to provide mechanical resistance to the green pellets to resist transporting the disc or pelletizing drum to the ceramic grids. The intense grinding of the pellet feed (granulometry from zero to 0.15mm) represents high energy consumption or 55Kwh / T, and the ceramization presents high thermal energy consumption or 200 Kcal / kg. As the process takes the material to strong thermal stress, with a maximum temperature of 1350 ° C, it produces as a result a high degree of cracks and fissures (40%) of the pellets produced. It is observed that the lack of thermal equalization of the process, therefore, parts of the material under different conditions of thermal load, causes high standard deviation of the mechanical strength of the pellets, being able to fluctuate from 60 to 300 kg.

[06] Briquetting: allows the agglomeration of ore fines of varying sizes and shapes through the pressure exerted on the material. In order for the final product (briquette) to have suitable properties, the use of binder in the blend is required. It is a process of low productivity, which limits its application as a solution to the problem.

[07] In order to make it possible to exploit the iron ore fines (between zero and 6.4 mm) generated by the steel mills, between 8 and 12% of the total ore mass used in the blast furnace (residue), as well as the fines generated by the miners, of up to 60% of the total production, the process described in the present cold pelletizing patent was developed, presenting as a differential the following aspects:

[08] - significant reduction of electrical and thermal energy in the process: from 55Kwh / T to 8Kwh / T, since it works with thin and "thick" as well as thermal energy, and in dry periods the contribution is minimal, since the material is below 3.5% moisture content, and in wet periods with (7 + 3.5 + 5.2) / 3 = 5.2, which requires a calorific consumption of 25Kcal / kg of ball against 200Kcal / kg in the ceramization.

[09] - use of a flexible industrial installation in a production scale that demands low investment value (R $ 50.00 / T year of pellet), thus becoming a solution that serves large and small industries;

[010] - considerable environmental solutions, such as the reduction of energy demands with less carbon generation, use of waste generated by the steel industry and mining fines.

In order to optimize the cold agglomeration process, the system is based on the arrangement of particles from 0 to 0.8mm with continuous grain size distribution, generating the smallest possible contact surface for the formation of the spherical body (ball ), in order to reduce the need of cement for its agglomeration, without compromising the mechanical strength of the pellet, with the participation of fines (below 75 microns) from ore and special cement used (98% less than 44microns), packaging of the larger grains occurs in a suitable way, generating resistance of rupture of the ball of 12mm of diameter of up to 150Kg.

The amount of ultra fine ore in the blend, of a size below 75micron, depending on the content of special cement that can fluctuate between 5% and 8%, depending on the target strength of the pellets, ranges between 34% and 48% and allows the packaging of the coarser grains as shown (Figure 6). The pellet presents raw pellet microstructure with angular grains and high porosity; the matrix is composed of transparent phases under the optical microscope from the cementitious mortar; the pellet presents good packing by regions composed of cementitious matrix and fines of ores with good cohesion.

[013] This mortar, formed by superfine ore and special developed cement adhered to the coarser particles, gives the ball a high breaking strength of up to 150 kg while preserving the porosity between 25% and 30%, as described below . The homogeneous mixture places in close contact the substances that are expected to enter the chemical reaction inside the reactor. The microscopic slide shown in Figure 7 shows the homogeneity and the contact between the oxides entering the reaction even before reaching the liquid phase, due to the conditions favorable to the chemical reactions: chemical affinity, contact surface and high temperature. In the microchemical mapping it is possible to observe the marked presence of Ca and Si forming the pellet matrix, which surrounds and sustains the hematite grains.

[015] The binder, which is a special cement, should meet specific chemical and physical requirements as below:

[016] - shall not contain carbonaceous addition. (for control of pellet swelling);

- contain a high content of alite (C3S) in the clinker, between 63 and 65%, generating high mechanical resistance to cement and low free CaO content, at a maximum of 1.5% to eliminate risk of pellet swelling;

[018] - be finely ground: maximum residue at 44 microns. of 1% and minimum blaine of 560 m2 / kg (cement strength);

[019] - the gypsum dosage should be optimized through laboratory tests that optimize gypsum, aiming to raise the resistance of the cement; the gypsum to be dosed must be the natural mineral; the plasters generated from phosphoric rocks can not be used, under penalty of contamination of phosphorus in pig iron;

[020] - cement can only contain addition if it is bound to some steel interest (eg addition of dolomite or flux);

[021] - the resistances must reach a minimum of 30Mpa to 01 day;

[022] - must have low alkali (K2O + Na2O) in order to meet the maximum level of 1.5 kg of alkali / T of pig iron in the blast furnace feed; although these alkalis present in the form of alkali sulphates and therefore more stable.

[023] This special cement characterized above contains between 60 and 65% calcium oxide in the hydrated silicates, which at a temperature close to 1000 ° C are available to react with the polluting oxides (S102, Al3 O2, etc.) of the iron ore , which are scorched in the pig iron generation process. In Table 1.1 we present detailed specifications of a special cement that meets the above-mentioned attributes [024] The stoichiometric equilibrium of the mixture in the pellet presupposes the generation of acid slag, being necessary, therefore, the addition of complementary limestone in the case of the reactors that require basic slag. As can be seen in Table 1 below:

Table 1.1:

Chemical composition parameters, preferred ranges and comparison with CP I cement, in addition to the characteristics of each

component.

Specification

cement NBR 5732

Components Preferred range Special feature CP I

(% of weight)

Clinquer + Essential for Sulfate 98.0 to 100.0 98.0 - 100.0 100.0 ensure the lowest Calcium -% swelling (a) and higher resistance

Improves softening of

Fluorite% 0.5 to 2.0 0.0 to 2.0 no pellet and reduces melt temperature

Material

Carbonate - 0,0 0,0 idem (a)

%

Residue

<= 1.0 <= 1.0

insoluble -%

Loss to fire

<- 1.5 <= 2.0 <= 2.0 Idem (a)

-%

MgO -% <= 4.0 <= 6.5

S03 -% 3.5 to 5.0 <= 4.0

C02 -% <= 0.1 <= 0.1 Idem (a)

Does not Improve

AI203 -% <= 5.0 <= 6.0

there is escorting (b) no

CaO -% 60 to 65

consists

Not

Na 20 -% <= 0.15 <= 0.25 Idem (b) consists

Not

K20 -% <= 1.2 Idem (b) consists

Element

S -% <= 0.05 undesirable in steel, leading to scorching

Not

P205 soluble -% <= 0.05 Idem (c) consists

[044] The above composition should also present the following physical parameters: residue in the sieve of 75 micron less than 0,1%; fineness in the sieve of 325mcron less than 1.0%; area [025] Table 2 below illustrates the quality parameters of cold pelletized iron ore pellets:

[026] As a reference the sinter presents the following indices: drum> 70%; RDI <25%; Cracking <8%.

[027] Compressive strength: In this process of cold pelletizing of iron ore, there is flexibility to produce pellets with varying strengths, depending on the application and complementary needs such as the size of the blast furnace and the process of transportation of the product. The definition of the percentage of cement should be based on the real need for resistance, since the cement dilutes the percentage of iron in the ball.

The graph 1 shown in the attached Figure 8 illustrates the resistance of the pellet to the percentage of special cement.

[029] Drumming - this parameter has a direct correlation with the compressive strength of the pellet, the greater the resistance the greater the drumming and vice versa. The dosage of 7% of binder leads to a sufficient performance, with an index of more than 90% and compatible with the standard (ISO 3271).

[030] RDI: as in the case of the drum, a good correlation with the compressive strength of the ball is observed. The level required by the standard (ISO 13390) of 90% pellet integrity after the test can be achieved with 7% dosing of the binder. [031] Swelling - the physical integrity of the pellet depends on the control of this variable. For swelling greater than 20% there is already the risk of disintegration of the pellet before the material entering the process of chemical solution. In this case, the blast furnace may enter into process mismatch.

Basicity - follows the conditions of the steel binary basicity index of approximately 0.02, that is, the ratio between CaO and free S1O2, according to the following worksheet, guarantees a level of ball swelling below 15%, for percentage of S102 in the ore above 6%.

[033] In order to meet this variable, special cement must be used with the specifications defined above, and in this way the following conditions are obtained in Table 3 below:

[034] The IB-REAL impacting the swelling is calculated by taking into account the available CaO from ores and the free CaO of the clinker used in the manufacture of the special cement, which may not exceed 1.5%, and the oxide of silicon present in iron ore. The CaO and S1O2 that form the silicates of the cement are combined and do not change the conditions of basicity at this moment, where the transformation of the crystals of the iron ore happens from the rhomboidal form to the needle when the reduction takes place.

[035] With this index adjusted for basicity close to 0.02, the required swelling target is reached, as shown in Figure 9, which shows the curve of swelling due to the basicity index (Meyer, Kurt, Pellotizing of Iron Ores, 1980).

[036] Cracking - the porosity of the ball between 25% and 30% ensures zero crackling, this attribute reduces the release of fines in the high form.

[037] Redutibility: reducibility stands out as a strong point of this pellet due to porosity (25% to 30%) and pore size in the material, as shown in figure 3, shown in Figure 10, attached.

[038] Pellets - The cold pellet has a lower porosity when compared to the ceramized one. The pores present in the cold pellet have a diameter between 0.01 and

5μιη, while the pores in the pellet are concentrated in a narrow diameter

[039] It can be verified that the pores are of average dimension of 0.1 micronm versus pores of average size of the ceramized ball of 10 microm. This explains the high redutibility of the cold-drawn pellet. The extended contact surface enables this performance.

[040] Softening and melting - Softening occurs at a temperature in the vicinity of 1100 ° C and dripping at 1330 ° C or within the range considered satisfactory. The table 1 shown in the attached Figure 11 presents test carried out and compared with the ceramized pellets.

[041] Escorification and guzeification - With the whole process of chemical reactions facilitated by the high surface of contact and approach between the oxides, what is observed is the occurrence of high fluidity of the slag. The dead man applied to the retort of the softening and fusing test remains completely clean after the test.

[042] When using the pellets in the blast furnaces, even with the utilization rate of only 20% pellets in the total load, there is already significant gain of slag fluidity. [043] Flexibility of mixtures - Cold pelletizing allows a wide range of materials to be used as raw material: ores, veneer, sludge, dolomite, dedusting fines, balloon powder or filter fines, coal and other components which may lead to the pig iron production process. Pellets called "self-reducers" can be made with this technology, since they are not subjected to burning after the tip.

[044] A PI061 1558-6 "Material for coating discs and drums of iron ore of a different or different nature from the material being pelletized and constructive arrangement for pelletizing discs and drums" - comprises a mixture of products agglomerates with ores (ground or not) of the group consisting of iron, manganese or others, including the inclusion of fluxes. On the other hand, the disc or drum 5 has its bottom 1 coated by the material so as to form a layer of the cold curing coating bottom 2, vegetable oils, minerals and / or forming products (6) is further provided for incorporating polyethylene sheets (7) to assist in the separation of the fines from the pellets (6). It differs from the present patent because it has as its object the coating of disks and pelletizing drums and not the production of material for setting in blast furnaces.

A PI9402617-3 - "Process for recovery by briquetting, agglomeration, pelletizing and pressing of fine residues in metallurgical, iron alloys, steelworks, foundries and in the factories of additives in racing" refers to the process of briquetting, agglomeration, pelletizing and pressing of fine residues, raw materials, industrial residues and fine grain additions of metals and other products that can not be used in the furnaces because they are entrained by gases and fumes. By drying, sieving and sorting it is possible to separate the fine particles into various particle sizes, then adding suitable mixtures of solid or liquid binders, various materials and other binding substances, capable of providing sufficient hot and cold mechanical strength in suitable mixers, pellets, extruded or compacted in briquetting machines, discs or pelletizing drums, extruders or presses, resulting in dimensions, volumes and weights that allow loading in the furnaces, without being swept away by the gases and fumes of the industrial processes, being able to be consumed and allowing the recycling of what would be industrial waste, consuming resources in machinery, labor, transport and land for ecological deposition. It differs from the present patent because it is a process of non-specific agglomeration of waste in general, with the sole purpose of agglomerating the material so that it can be reintroduced to the furnaces. The patent does not focus on an agglomeration process that is alternative to the iron ore or hot pelletizing that deals with this problem and represents the current state of the art. The patent does not specify the agglomerated material to meet the requirements of blast furnaces, such as compressive strength, drumming, RDI, reducibility, swelling, and the chemical attributes required by blast furnaces. Neither does it deal with the granulometry of the materials for the bead, in order to meet the objectives related to the mechanical strength of the material, the porosity related aspects, which optimize the reducibility, of the binary basicity index that defines the swelling and, finally, does not present data on the "softening and melting" of the product "indicating whether such material will be normal at all stages of the blast furnace, from initial drying to melting and slagging.

A process for cold pelletizing slurry produced in blast furnaces comprising the following steps: 1) the blast furnace slab undergoes a first natural drying, reducing its moisture to approximately 15%; deposited or scattered in an open-air patio, and at this stage, the mud turns into fuzzy layers; 2) extermination of the mud already dried through exterminator or machine capable of breaking into small fragments; 3) the already fragmented slurry receives a suitable binder and passes through a mixing phase through a rotary mixer; 4) the mixed or homogenized material with dry slurry and binder is transferred to pelletizing where the processed material receives a controlled volume of water which, associated with the rotation of the disc and its inclination, promotes the agglomeration of the particles and is transformed into pellets, whose granulometry is defined as a function of the quantities of water, speed of rotation and angle of inclination of the rotary disc of the pelletizer; 5) Pellets are stored in the shade, maintaining a high humidity level through water spray for 3 consecutive days. After 15 days the pellets ^Q achieve consistency and a compression ratio above 40 kgf per pellet. It differs from the present patent because it is a process directed to the use of sludge generated in the treatment of the blast furnace gases, aiming at the re-formation of the material. In this case, the specification of the material or product generated focuses only the possibility of reintroduction to the oven.

[047] A PI BR0000321510049410 - "Cold Pelletizing Process of Iron Ore Fines", similarly owned by the Applicant of the present patent, refers to cold pelletizing process through mortar composed of superfine iron ore and Portland cement in an optimized ratio that allows the achievement of technical specifications and competitive costs. The production of the pellets obeys simplified flow chart in the different scales of production. It differs from the present patent because it does not present the detailed characteristics of the granulometric arrangement that allows the packaging of the grains and consequent attainment of the mechanical attributes of the pellet, without, however, of the fine porosity that enhances the material's reducibility. In addition to not treating the swelling that defines the mechanical strength of the pellet after the reduction of the material and therefore its behavior inside the blast furnace may make the use of the material unfeasible, since it does not define the characteristics of the binder or special cement that it confers to the product the appropriate specifications, and not to indicate the possibility of mixtures or flexibility of the process to include in the product materials of steel interest in order to produce pig iron of better quality; because it considers necessary the pre-drying chamber that requires considerable heat source, besides not defining the final sieving of the material discharged by the pelletizer, in order to reduce the fines contained in the final product and, finally, not to point out the importance of the transport of the material from the exit of the pelletizer to the curing stack on low speed conveyor belts, or 200mm / second, with low impact transitions between the conveyors and final deposition for curing in layers, with equipment that enables the maximum fall height of 1 m in the launch of the material on the already deposited. [048] The process described herein has the following advantages:

[049] - guarantee of mechanical resistances necessary for good use in blast furnaces of any size;

[050] - swelling that allows the material to reach the softening zone in an integral manner, avoiding process mismatches in the blast furnace;

[051] - suitable treatment of the material released by the disc or pelletizing drum, preventing the breaking of the pellets and consequent generation of fines in the final product;

[052] - reduction of thermal consumption, either through electric energy or alternative thermal source;

[053] - the possibility of using different percentages of binder additions or "special cement", to suit the mechanical strength required by blast furnace and logistic processes, which may require higher strengths (transoceanic travel);

[054] - the possibility of aggregating different materials to the pellets, in order to give the material attributes related to the treatment of the pig iron or optimization of the performance of the blast furnace.

[055] The present process allows the use of dry or wet materials below 3.5%, hence there is no need for process water treatment, which facilitates and makes the process more environmentally correct. However, if due to the process of beneficiation of the ore, the raw material to be pelletized is already wet, it is possible to opt for the wet route without prejudice to the final product.

[056] The present process may be better understood through the process flowcharts and the steps thereof described in the accompanying Figures.

[057] Figure 1 illustrates the flowchart of the entire process.

[058] Figure 2 shows the flowchart of the homogenization / drying step.

[059] Figure 3 illustrates the flow chart of the screening / milling step.

Figure 4 shows the flow chart of the dosing / mixing / beading step.

[061] Figure 5 illustrates the flow chart of the transport / stacking / curing step. [062] According to Figures 1 to 5, process (1) has the steps described below:

[063] Homogenization - Classic, Chevron process or other to choose. The stacker (01) performs the longitudinal ore deposition and the take-up (02) removes the material from the stack transversely, which promotes material mixing by reducing the standard deviation of material quality by up to 12 times.

[064] Drying - To ensure maximum humidity of 3.5% at the mill inlet. The dryer (03) removes excess moisture and ensures continuity of production in the wet periods, since drying in the sun is the preferred way of meeting the reduction of humidity.

[065] Screening and grinding - The sieve (04) separates the material with a size smaller than 0.8 mm from the larger one, so that it is then ground. The material that goes to the mill (05), has its granulometry variable depending on the raw material, sometimes richer in thicknesses. The grinding product should contain a high percentage of fines, from 40% to 50% below 75microns, so that all the materials meet the grain size curve required for the packaging of the beans at the bead. The material sieved and below 0.8 mm is cast in a dosing silo (07) and ground in another silo (06).

[066] Dosing, mixing and setting - At the dosing step, the other constituents, such as the special cement in the silo (08) and other material, if necessary, must be added to the silo (09). It is imperative that the dosage be very accurate, and therefore the dosers (10, 11, 12 and 13) must comply with the adjustments, so that the good quality of the final product is obtained. The dosage must obey the principle of the sequence of the mixture: from the smallest quantity to the largest quantity, increasing the efficiency of the mixture. The materials are then cast into a continuous rotary mixer (14) with blenders and low energy blades, since the materials are dry, or with low humidity, allowing perfect mixing. In the case of mixing with wet materials, the mixer should be changed and require more energy for mixing. The tip can be made with dry or wet material. If dry, the addition of water will occur through spray nozzles suitably disposed on the disc or drum (15) of the bead. If wet, there is also a need to atomizers but in smaller amount. When using dry material, the amount of water demanded is 80 to 90 kg / T of ball.

[067] Transport and stacking in the curing heap - At the exit of the pelletizer, although the green pellets are resistant (they will withstand the drop test of up to 1.5m in height), they need care. The pellets should be transported in low-speed (200mm / second) conveyor belts (16) in thick layers on the belts and, at transitions, the shuts or shuts should be of low impact or maximum drop height of 350mm and damping through soft surfaces such as rubber sheets. The equipment for depositing the material in the stacks or forklift (17) must have a variable and controlled discharge height in order to guarantee a maximum fall height of 0.5m on the material already deposited. The equipment must be movable so as to impact the layer already deposited only once with the new material. In this way, the pellets will be directly hammered by the new charge only once.

[068] Chemical reactions and the healing process - They begin after hydration of the special cement. In this initial period, it is necessary to avoid the loss of water and or excess water in the pellet, therefore, it should remain in an environment protected from sun and rain in the first three days. After this period, the reclaimer (19) will extract the material to launch it in open tanks (20), there being no need for protection, only surface wetting in the case of intense sun and until the seventh day. The ideal resistance is present at seven days, but depending on the blast furnace to be used, you can feed the material as early as four days.

[069] Storage - After the seven-day curing period, the pellet can be stored in the open without any risk to its quality and for as long as necessary. There is no degradation over time.

The loss of resistance test after 24 hours of immersion of the pellet in water presents reduction of the resistance in 25% of the resistance of the dried pellet.

Claims

1. A process for the cold-working of iron ore with melt flowability characterized by the arrangement of the particles from 0 to 0.8 mm with a continuous grain size distribution, generating a smaller contact surface for the formation of the spherical body (pellet), with the participation of fines (less than 75 microns) coming from the ore and the cement used (98% less than 44 microns), the bigger grain packaging occurs in a suitable way, pellet of 12mm of diameter of up to 150Kg.

2. PROCESS OF COLD PELOTIZATION PROCESS OF IRON ORE FIXES WITH MIX FLEXIBILITY, characterized by the amount of ultra fines in the ore mixture and special cement, of a size below 75micronm, depending on the content of special cement, which may to fluctuate between 5% and 8%, depending on the target resistance of the pellets, reaches a range between 34% and 48% and allows the packaging of the coarser grains; the pellet presents raw pellet microstructure with angular grains and high porosity; the matrix is composed of transparent phases under the optical microscope from the cementitious mortar; the pellet presents good packing by regions composed of cementitious matrix and fines of ores with high cohesion.

3. A process of cold pelletizing of iron ore with melt flowability characterized by pellet having a raw pellet microstructure with angular grains and high porosity; the matrix is composed of transparent phases under the optical microscope from the cementitious mortar; the pellet presents packaging by regions composed of cementitious matrix and fines of ores with high cohesion.

4. PROCESS OF COLD PELOTIZATION PROCESS OF IRON ORE FINES WITH MIX FLEXIBILITY, characterized by the mortar formed by the superfine of ore and cement, adhered to the coarser particles, gives to the ball high breaking resistance of up to 150 kg, preserving the porosity between 25% and 30%; The homogeneous mixture the substances that are expected to enter the chemical reaction inside the reactor.

5. PROCESS OF COLD PELOTIZATION OF IRON ORE FIXES WITH MIXTURE FLEXIBILITY, characterized by homogeneity of pellet constituents and contact between the oxides that enter the reaction even before reaching the liquid phase, due to the conditions of the chemical reactions : chemical affinity, contact surface and high temperature; with presence of Ca and Si forming the matrix of the pellet, which surrounds and sustains the hematite grains.

6. A process for cold deposition of iron ore with melt flowability characterized in that the binder contains alitrogen content (C3S) in the clinker, between 63 and 65%, low free CaO content, at most 1, 5%; finely milled: with maximum residue at 44 microns of 1% and minimum blaine of 560 m2 / kg; optimized natural gypsum dosing; minimum resistance of 30Mpa to 01 day; low alkali (K 2 O + Na 2 O); contain between 60 and 65% of calcium oxide in the hydrated silicates, which at a temperature close to 1000 ° C are available to react with the polluting oxides (S1O2, AI3O2, etc.) of the iron ore, which are scorched.

7. A process for the cold-working of iron ore with melt flowability characterized by process (1) having the following steps: Homogenization; Drying; Screening and milling; Dosing, mixing and capping; Transport and stacking in the healing pile; Chemical reactions and the healing process; Storage.

8. A process for the cold-melt deposition of iron ore with melt flowability according to claim 7 characterized in that homogenization is carried out by a forklift truck which makes the longitudinal deposit of the ore and the take-up (02) removes the material from the stack transversely, which promotes material mixing by reducing the material quality standard deviation by up to 12 times.

9. A process for the cold-working of iron ore with melt flowability according to claims 7 and 8 characterized by the drying which guarantees a maximum humidity of 3.5% at the inlet of the mill; the dryer apparatus (03) removes excess moisture.

10. A process of cold-melt pelluicing of iron ore with melt flowability according to claims 7 to 9 characterized by sieving and milling where the sieve

(04) separates the material with a dimension of less than 0.8 mm from that of larger dimension, so that it is then milled; the material that goes to the mill

(05), has variable granulometry; The grinding product should contain a high percentage of fines, 40% to 50% below 75microns, so that all the materials meet the grain size curve required for the packaging of the beans at the bead; the material sieved and below 0.8 mm is cast in a dosing silo (07) and ground in another silo (06).

11. A process for the cold-working of iron ore with melt flowability according to claims 7 to 10, characterized in that in the dosing step the other constituents are added, such as the special cement in the silo (08) ) and other material, if necessary, in the silo (09); the dispensers (10, 11, 12 and 13) must comply with the adjustments; the dosage must obey the principle of the sequence of the mixture: from the smallest amount to the largest amount, increasing the efficiency of the mixture; the materials are then cast into a continuous rotary mixer (14) with blenders and low energy blades, since the materials are dry, or with low humidity; in the case of mixing with wet materials, the mixer should be changed and require more energy for mixing; the bead may be made of dry or wet material, if dried, the addition of water will occur through atomizing nozzles suitably disposed on the disc or drum (15), if wet, there is also a need for atomizers but less amount; when using dry material, the amount of water demanded is 80 to 90 kg / T of ball.

A process for the cold-working of iron ore with melt flowability according to claims 7 to 11 characterized by the transport and stacking in the curing stack; at the exit of the pelletizer, the pellets should be transported in low-speed (200mm / second) conveyor belts (16mm) in thick layers on the belts, and in the transitions, discharges or shuts should be of low impact or maximum fall height 350mm and cushioning through soft surfaces such as rubber sheets; the equipment for depositing the material in the cells or forklift (17) must have a variable and controlled discharge height in order to guarantee a maximum fall height of 0,5 m on the material already deposited; the equipment must be movable so as to impact the layer already deposited only once with the new material.

13. A method according to Claims 7 to 12 characterized in that the chemical reactions and the curing process start after hydration of the special cement; in this initial period, one must avoid the loss of water and / or excess water in the pellet, therefore, it must remain in an environment protected from sun and rain in the first three days; after this period, the reclaimer 19 will extract the material to launch it into open containers 20, with surface wetting in the case of intense sun and up to the seventh day.

14. A method according to any one of claims 7 to 13 characterized in that the pellet can be stored in the open after the curing period of seven days. The resistance loss test after 24h of immersion of the pellet in water presents reduction of the resistance in 25% of the resistance of the dried ball.