CN104232884A - Agglomeration method of iron ore powder - Google Patents

Abstract

The invention provides an agglomeration method of iron ore powder, and belongs to the technical field of iron ore smelting. The agglomeration method is realized by the technical scheme comprising the following steps: (1) adding little dolomite into fine-grinded iron ore concentrate powder or other iron powder materials, and adding water to wet and uniformly mix the materials to prepare a material mixture; (2) before mixing the materials, paving a layer of small sintered ore blocks with grain size of 10-25mm and thickness of 20-25 mm as grate-layer materials; (3) controlling an ignition temperature to 1250 +/-50 DEG C, ignition time to 40-60s, ignition vacuum degree to 4-6kPa and ignition depth to 10-20mm; and (4) controlling the machine rotation speed to 1.5-4m/min and guaranteeing sintering feed to sinter thoroughly at a predetermined sintering end point. According to the agglomeration method of iron ore powder, the resources are comprehensively utilized, the raw material varieties for iron-making are increased, harmful impurities are removed, beneficial elements are recycled, the environment is protected, the metallurgical performances of the ores are improved, and the quality requirements of blast furnace process on the iron ores are adapted.

Description

The method of iron mineral powder agglomeration

Technical field

The invention belongs to iron ore technical field of smelting, particularly relate to a kind of method of iron mineral powder agglomeration.

Background technology

In order to ensure to supply blast furnace iron ore in iron level even, and ensure the ventilation property of blast furnace, need the block stock iron ore concentrate of ore-dressing technique output being made 10-25mm.Sintering is an important step in process for producing steel and iron, and it is mixed according to a certain ratio powdered iron ore, powder (hard coal) and lime, blast furnace dust, roll scale, slag.The agglomerate of sufficient intensity and granularity that has through sintering can be used as the grog of ironmaking.Utilize sintered clinker to smelt iron for the raising capacity factor of a blast furnace, reduce coke ratio, raising blast furnace permeability ensures that operation of blast furnace all has the certain significance.

Summary of the invention

The invention provides a kind of method of iron mineral powder agglomeration.The method of iron mineral powder agglomeration of the present invention, is realized by following technical proposals:

(1) fine grinding fine iron breeze or other iron content powders are added a small amount of rhombspar to add water-wet and mix obtained compound;

(2) before cloth compound, first spreading one deck granularity is 10 ~ 25mm, and thickness is that the fritter agglomerate of 20 ~ 25mm is as grate-layer material;

(3) ignition temperature controls at 1250 ± 50 DEG C, ignition time usual 40 ~ 60s, vacuum ignition degree 4 ~ 6kPa, the igniting degree of depth is 10 ~ 20mm;

(4) machine speed controls at 1.5 ~ 4m/min, and sintered material is grilled thoroughly at sintering end point.

The method of iron mineral powder agglomeration of the present invention, utilize resources synthetically, expands the raw material type of ironmaking, removes detrimental impurity, and reclaim beneficial element, protection of the environment, improves the metallurgical performance of ore, adapts to blast-furnace smelting to the specification of quality of iron ore.

Embodiment

Below by specific embodiment, the present invention is further illustrated.

The starting material of sintering prepare:

Iron-bearing material: iron-holder is higher, the breeze of granularity <5mm, iron ore concentrate, blast furnace dust, roll scale, slag etc.General requirement iron-bearing material is of high grade, stable components, and impurity is few.

Flux: require that in flux, effective CaO content is high, impurity is few, stable components, moisture about 3%, what granularity was less than 3mm accounts for more than 90%.In sintered material, add a certain amount of rhombspar, make agglomerate contain suitable MgO, have good effect to sintering process, the quality of agglomerate can be improved.

Fuel: be mainly coke powder and hard coal.Be that fixed carbon content is high to the requirement of fuel, ash content is low, and volatile matter is low, and sulfur-bearing is low, stable components, is moisturely less than 10%, and what granularity was less than 3mm accounts for more than 95%.

The batching of sintering with mix, batching object: obtain chemical composition and the stable agglomerate of physical properties, meet the requirement of blast-furnace smelting.Distribution: quality dosing method, namely presses the quality batching of raw material; By electrical metering device, dissolve starting material by a certain percentage.Mixing object: the uniform composition making sintered material, moisture is suitable, is easy to pelletizing, thus obtains the good sinter mixture of size composition, to ensure the quality of agglomerate and to improve output.The method of mixing: add water-wet, mixing and pelletizing.Different according to feedstock property, mixed once or secondary can be adopted to mix two kinds of flow processs.The object of mixed once: wetting and mixing, also can make material preheating when adding hot returning ore.The object of secondary mixing: continue mixing, pelletizing, to improve permeability of sintering material bed.When sintering with the rich ore powder of granularity 10 ~ 0mm, because its granularity has reached pelletizing needs, adopt mixed once, mixing time is about 50s.When using fine grinding fine ore sintering, because granularity is meticulous, bed permeability is poor, for improving blast furnace permeability, must in mixing process pelletizing, so adopt secondary to mix, mixing time is generally no less than 2.5 ~ 3min.China's sintering plant adopts secondary to mix mostly.

Prepare burden and the major equipment mixed

Electronic weighing balance: to be placed on belt and to carry out the weighing apparatus of automatic weighing with the bulk material that belt continues through.Mainly contain mechanical type (common is roller belt scale) and the large class of polarity formula two.Belted electronic balance is most popular weighing belt.The automated production mainly used is made up of: LOAD CELLS, velocity sensor, digital display meter, frequency transformer, electric motor mixing machine: mixing machinery utilizes mechanical force and gravity etc., by the machinery that two or more material Homogeneous phase mixing gets up load carrier, LOAD CELLS, velocity sensor and weight display.Mixing machinery is widely used in all types of industries and daily life.Conventional mixing machinery is divided into gas and the large class of low-viscosity (mobile) liquid mixing tank, medium-high viscosity liquid and paste mixing machinery, thermoplastic mixing machine, powdery and particulate solid material mixing machinery four.

SINTERING PRODUCTION

Sintering work is the key link of SINTERING PRODUCTION, and it comprises the master operations such as cloth, igniting, sintering.

Cloth: grate-layer material, compound are layered on the operation on sintering pallet, igniting: ignition operation lights the bed of material surface on chassis, and make it burning.Sintering: accurately control the air quantity of sintering, vacuum tightness, bed thickness, machine speed and sintering end point.

The pellet technological process of production

After fine grinding fine iron breeze or other iron content powders are added the mixing of a small amount of additive, under the condition adding water-wet, by pelletizer rolling balling, then through drying and roasting, consolidation becomes the ball-type iron-bearing material with some strength and metallurgical performance.

The flow process that pellet is produced

Generally comprise raw material preparation, batching, mixing, pelletizing, drying and roasting, cooling, finished product and the operations such as process of returning mine, in the Production Flow Chart of pellet, batching, mixing consistent with the method for agglomerate; The raw material mixed is made the spherical of 10-25mm through pelletizer.

Major equipment in pellet production: balling disc: after coke powder, limestone powder or unslaked lime, fine iron breeze mixing, in the blending bun on input balling disc top, equably to pelletizer cloth, supply vaporific spray water by water pipe simultaneously, the balling disc that inclination (inclination angle is generally 40 1 50 °) is arranged, rotated by mechanical transmission, compound adds spray water rolling balling in disk.Belt type roasting machine: belt type roasting machine technique makes the whole technological process of pellet roasting---drying, preheating, roasting, cooling complete all on one device, there is the features such as technological process is simple, characteristics of compact layout, required equipment tonnage are light, reduce floor space for factory, reduce quantities, realize the recycle of roasting gas and reduce hear rate and power consumption creates condition.

Cloth: grate-layer material, compound are layered on the operation on sintering pallet.

When adopting grate-layer material technique, before cloth compound, first spreading one deck granularity is 10 ~ 25mm; thickness be the fritter agglomerate of 20 ~ 25mm as grate-layer material, its objective is protection fire grate, reduce load of dust remove; extend the fan rotor life-span, reduce or eliminate fire grate sizing.After having spread bed material, carry out cloth thereupon.Require during cloth that the granularity of compound and chemical composition etc. are uniformly distributed in direction in length and breadth along chassis, and have certain free-running property, surfacing.What current employing was more is round roller material distributing machine cloth.

Igniting: ignition operation lights the bed of material surface on chassis, and make it burning.

Igniting requires enough ignition temperatures, suitable high temperature hold time, along the igniting of chassis width evenly.Ignition temperature depends on the temperature of fusion of sintering resultant.Often control at 1250 ± 50 DEG C, ignition time usual 40 ~ 60s, vacuum ignition degree 4 ~ 6kPa, the igniting degree of depth is 10 ~ 20mm.

Sintering: accurately control the air quantity of sintering, vacuum tightness, bed thickness, machine speed and sintering end point.

Sintering air quantity: average agglomerate required airflow per ton is 3200m3, is calculated as (70 ~ 90) m3/ (cm2.min) by sintering area.Vacuum tightness: be decided by fan capacity, exhausting system resistance, bed permeability and damaed cordition of leaking out.Bed thickness: high yield and high-quality should be combined consideration by suitable bed thickness.Domestic general employing bed thickness is 250 ~ 500mm.Machine speed: suitable machine speed should ensure that sintered material is grilled thoroughly burned at predetermined sintering end point.In actual production, machine speed general control is advisable at 1.5 ~ 4m/min.

The judgement of sintering end point and control: control sintering end point, namely control the position residing for chassis when sintering process all completes.Middle-size and small-size sinter machine terminal general control is at penultimate bellows place, and large-type sinterer controls at third from the bottom bellows place.Dwight-Lloyd sintering machine down draft sintering process is carried out from top to bottom, and the situation along its bed depth temperature variation generally can be divided into 5 layers.After igniting starts, there is sintering ore bed, zone of combustion, preliminary heating zone, drying layer and excessive moistening layer successively.Then latter four layers disappear again in succession, final only surplus sintering ore bed.Sintering ore bed is after high-temperature ignition, in sintered material, amount of heat is released in fuel combustion, make bed of material Minerals produce melting, along with zone of combustion moves down and the passing through of freezing air, the melting liquid phase of generation is cooled and recrystallize (1000-1100 DEG C) is frozen into mesh-structured agglomerate.The Main change of this layer is solidifying of melts, and along with crystallization and precipitation new mineral, also have the freezing air sucked to be preheated, agglomerate is cooled simultaneously, and when contacting with air, suboxide may be reoxidized.Zone of combustion, fuel burns at this grate firing, temperatures as high 1350 ~ 1600 DEG C, makes mineral soften melting and coheres into block.Except combustion reactions, also there is the reactions such as the decomposition of the fusing of solid materials, reduction, oxidation and Wingdale and sulfide in this layer.Preliminary heating zone, the high-temp waste gas got off by zone of combustion, is preheating to kindling temperature very soon bottom compound, is generally 400 ~ 800 DEG C.Start in this layer to carry out solid state reaction, crystal water and part thereof, sulphate decomposition, magnetite local is oxidized.The waste gas that drying layer gets off by preliminary heating zone heats, and temperature rises to more than 100 DEG C very soon, and the free-water in compound evaporates in a large number, and this layer thickness is generally l0 ~ 30mm.In fact drying layer and preliminary heating zone are difficult to well-separated, can be referred to as drying and preheating layer.In this layer, pellet is sharply heated, dry rapidly, is easily destroyed, worsens bed permeability.The hot waste gas that excessive moistening layer gets off from drying layer contains large quantity of moisture, and during the dew-point temperature of material temperature lower than water vapour, the water vapour in waste gas can regelation, makes moisture in compound roll up and form excessive moistening layer.This layer of excess moisture, makes bed permeability degenerate, and reduces sintering velocity.

Basic chemical reaction in sintering process

Generate C0 and C02 after the combustion reactions of 1. solid carbon, also have some residual oxygen, for other reactions provide redox gas and heat.The exhaust gas constituents that burning produces depend on the material condition of sintering, firing rate, reduction and oxidizing reaction development degree and be pumped through the factor such as gaseous constituent of zone of combustion;

2. the decomposition of carbonate and mineralization: the carbonate in sintered material has CaC03, MgC03, FeC03, MnC03 etc., wherein based on CaC03.Under sintering condition, CaC03 starts to decompose at about 720 DEG C, and start chemistry boiling when 880 DEG C, the corresponding decomposition temperature of other carbonate is lower.Decomposition of Calcium Carbonate product C a0 can react with other mineral in sintered material, generates new compound, mineralization that Here it is.Reaction formula is: if CaCO3+SiO2=CaSiO3+CO2 CaCO3+Fe2O3=CaO Fe2O3+ CO2 mineralization is incomplete, exist there being residual free Ca0, depositing in process, the moisture in same air is carried out digestion by it: CaO+H2O=Ca (OH) 2 makes the volumetric expansion of agglomerate and efflorescence;

3. the decomposition of iron and Mn oxide, reduction and oxidation: the oxide compound of iron is under sintering condition, when temperature is higher than l300 DEG C, Fe203 can decompose, and Fe304 decomposition pressure under sintering condition is very little, but have Si02 exist, temperature be greater than 1300 DEG C time, also may decompose.

Claims (1)

1. a method for iron mineral powder agglomeration, is characterized in that comprising the following steps:

(1) fine grinding fine iron breeze or other iron content powders are added a small amount of rhombspar to add water-wet and mix obtained compound;

(2) before cloth compound, first spreading one deck granularity is 10 ~ 25mm, and thickness is that the fritter agglomerate of 20 ~ 25mm is as grate-layer material;

(3) ignition temperature controls at 1250 ± 50 DEG C, ignition time usual 40 ~ 60s, vacuum ignition degree 4 ~ 6kPa, the igniting degree of depth is 10 ~ 20mm;

(4) machine speed controls at 1.5 ~ 4m/min, and sintered material is grilled thoroughly at sintering end point.