Method for lumping small-dispersed iron-containing material for metallurgic conversion by using organic binding agent

FIELD: metallurgy.

SUBSTANCE: invention relates to methods for lumping ground iron-ore raw in aim for it preparing to metallurgic conversion and utilization of iron-containing waste. At least one iron-containing material and a binding agent are mixed, the mixture is subjected for aggregation and prepared aggregates are strengthened. As a binding material method involves using a synthetic copolymer of acrylamide and sodium acrylate wherein the mole part of sodium acrylate can be from 0.5 to 99.5% and molecular mass in the range = (1 x 104)-(2 x 107) Da. Dosing synthetic copolymer of acrylamide and sodium acrylate is from 0.02 to 0.10 kg per a ton of iron-containing material. Copolymer of acrylamide and sodium acrylate can be used as a dry powder, solution, emulsion, suspension or aerosol, in pure state or as a mixture with additional material. Invention provides retaining the maximally high content of iron in lumped material possessing required physical and metallurgic properties, enhancing output of the technological process and creating additional parameters in operation of the lumping process.

EFFECT: improved lumping method.

2 tbl, 2 dwg, 1 ex

 

The invention relates to a method of agglomeration of the crushed iron ore raw materials for the purpose of its preparation for metallurgical treatment and recycling of iron-containing waste, such as sludge, mill scale, flue dust, and other.

Known methods of agglomeration, including agglomeration, pelletizing and briquetting, involve the use of various types of mineral or organic binding agents. However, all mineral binder additives are diluting materials, the use of which leads to the reduction of iron content in the finished Ososkova product and contamination by impurities, harmful for further refining. Therefore, the use of organic binders is preferred.

The closest in technical essence and the achieved result is a method of sintering described in patent No. 662021 "Charge for the production of sinter or pellets," which includes the use as a binder material alkali-metal salt of carboxymethyl cellulose (No. 662021, With 22 In 1/224, publ. 05.05.79).

This document describes a method of agglomeration of iron ore materials, in which the mixture contains alkali-metal salt of carboxymethyl cellulose in an amount of 0.01 to 1.0% by weight of iron ore material and the ol low molecular weight alkali metal weak acid in a quantity of 0.001 to 10.0%.

The disadvantage of this method is the characteristic properties of the proposed binder (alkali-metal salt of carboxymethyl cellulose), which determines the relatively high binder consumption (up to 10 kg/t) and the need to use additional material (alkali metal salt of low molecular weight weak acid) in an amount of up to 10 kg/t, which significantly complicates the acceptance and storage of blended materials, the preparation process of the charge and leads to dilution okuskovannogo product. In addition, with sufficient effectiveness of this type of binding can only be used for sintering hematite iron ore concentrates. During sintering of magnetite concentrates the effectiveness of salt of carboxymethyl cellulose is low.

Object of the invention is to provide a method for agglomeration of fine iron-bearing materials are technologically simple and affordable, and also the creation on the basis of this method technologies agglomeration, production of pellets and briquette.

The expected technical result is the preservation in Ososkova product the highest iron content determined by the characteristics of the original iron-bearing material, obtaining okuskovannogo product with the desired physical and metallurgical properties, the behavior of the solution performance of the technological process, improving the controllability of the process, the creation of additional parameters control the sintering process.

The technical result is achieved by the fact that the iron-containing material is mixed with a binder, if necessary, moisturize, shytobuy mixture is subjected to aggregation and the resulting aggregates strengthen. According to the invention as a binder using a synthetic copolymer of acrylamide and sodium acrylate in which the mole fraction of sodium acrylate may be from 0.5 to 99.5%, a molecular weight in the range from 1·104up to 2·107while the dosage of the synthetic copolymer of acrylamide and sodium acrylate is from 0.02 to 0.10 kg per tonne of iron-bearing material. According to the invention in the charge can also be used for more material. As an additional material may be used fluxing material such as various clays (bentonite, nontronite and any other types), a variety of limestone, bauxite, chalk, marl, flask. Also as an additional material may be used fuels, including coke, toxic, coal and fossil fuel. If additional material is a copolymer of acrylamide and sodium acrylate may be introduced into the mixture either separately or in the form of two - or multicomponent mixtures of any additional mater what Alami. The aggregation process carried out by the method of work, briquetting or extrusion, the final hardening method of firing or sintering.

The invention consists in the following.

Known methods include the use of different binders during sintering of iron ore concentrates, iron ore, metallurgical sludge production, crushed slag, dross and other fine iron-bearing materials. The main functions of the binders are the required size and required strength obtained from charge units before the beginning of the hardening process, the formation of the structure of the aggregates and further properties okuskovannogo product.

As binders typically use different types of clay, lime and organic resin and bitumen. The consumption of these substances is quite high and is determined by the properties of the binder and the necessary quality okuskovannogo product.

According to the invention as a binder using a synthetic copolymer of acrylamide and sodium acrylate linear or branched structure, or a mixture of linear and branched copolymers in which the molar proportion of sodium acrylate may be from 0.5 to 99.5%, a molecular weight in the range from 1·104up to 2·107. Dosage synthetic copoly the EPA of acrylamide and sodium acrylate is from 0.02 to 0.10 kg per tonne of iron-bearing material.

Copolymer of acrylamide and sodium acrylate are added to the mixture in the form of a powder or solution, depending on the initial moisture content of the mixture. In case of high humidity the original binder mixture is metered in the form of a powder, which dissolves in the moisture of the mixture during its extracts after mixing before aggregation. In the case of using the binder solution, its concentration is chosen in such a way as to obtain the solution of the desired viscosity. taking into account the interaction of the dosed solution with moisture mixture.

In some cases, to increase the degree of absorption of the binder mixture, to improve the distribution of the binder in the charge and, consequently, reduce the amount of the binder is a copolymer of acrylamide and sodium acrylate may be added to the mixture in the form of emulsions, suspensions or aerosol. The input form is determined by a given technological scheme and the characteristics of the processes of aggregation and hardening.

When choosing the physical state of a copolymer of acrylamide and sodium acrylate, you must consider that it is necessary to provide a shutter charge before aggregation. When dosing undissolved binder shutter speed longer. In addition, in most cases you want to keep the range of the optimum moisture content of the mixture. Therefore, when the dispensing dry with sousage need to control the humidity of the charge materials, and when dosing dissolved to provide hydration charge mixture to the optimum level.

To ensure an effective process work dosage of a copolymer of acrylamide and sodium acrylate should be 0,02 0,10...kg per tonne of iron-bearing material. Low efficiency of use of a copolymer of acrylamide and sodium acrylate with dosage is outside the specified range associated with features of the mechanism of interaction between the polymer and iron ore concentrate.

First of all, for the effective work it is necessary uniform distribution of the binder in the charge. Interacting with the moisture of the mixture, a copolymer of acrylamide and sodium acrylate forms a solution, the mobility of which wetting ability with respect to the surface of the magnetite depends on the concentration, table 1.

Table 1.

Properties generated in the charge solutions.
The flow of polymer in the mixture, kg/tComposition moisture chargeThe viscosity of the solution, MPa·Square drops of moisture mixture, mm2
0,00Water1,038,47
0,070.07% polymer solution8,642,07
0,30 0,30% solution of polymer13,261,54
1,001,00% solution of polymer21,637,26

As can be seen from table 1, by increasing the dosage of a copolymer of acrylamide and sodium acrylate viscosity of the solution increases. The dependence of the square drops of solution on the surface of magnetite (an indirect measure of the wetting ability) from the dosage of the polymer is an extreme character, at the dosage of a copolymer of acrylamide and sodium acrylate over 0.3 kg/t of the area of the drops decreases.

In table 1 data on the properties of solutions of a copolymer of acrylamide and sodium acrylate, and their interaction with the surface of magnetite are the results of the study of model systems. In practice, the optimal dosage is somewhat lower and corresponds to the above range: 0,02...0,10 kg per tonne of iron ore concentrate. However, the mechanism of interaction and the nature of the dependencies when changing dosages are stored.

When the moisture content of the mixture is about 10% (which is typical for most of the conditions of production of pellets) polymer in the specified range of dosage forms are the most mobile solution with the most high wetting ability. At lower doses and, consequently, the concentration of the resulting solution of the polymer does not have the necessary environmenta what I properties moisture mixture. When the dosage of a copolymer of acrylamide and sodium acrylate higher than the specified range, the viscosity of the resulting solution exceeds the optimum. The processes of wetting and distribution of the binder in the amount of charge substantially deteriorate due to a substantial increase in viscosity forces.

The second condition for effective work is the formation of a large number of stable nuclei that do not collapse under the application of mechanical loads. The stability of nuclei at the pelletizing polimersoderzhashchie charge is determined by the density strictly oriented spatial coagulation patterns formed by the molecules of the polymer. With increasing dosages of a copolymer of acrylamide and sodium acrylate density of this structure is increased, resulting in increased yields of embryos from a unit volume of the mixture (figure 1) and, further, to obtain a more durable raw pellets (figure 2).

Thus, the above range of dosages of a copolymer of acrylamide and sodium acrylate (0,02...of 0.10 kg/t) corresponds to the optimal density of coagulation patterns in damp pellets. Lower doses do not provide the necessary density of structures and, accordingly, the strength of the nuclei at the initial stage of the formation of pellets. Large - have a positive impact on p is echnosti germ, however, reducing the efficiency of the process of agglomeration due to violations of the processes of wetting and distribution of the binder (see above) and, consequently, a decrease in the efficiency of work.

Under certain conditions, the use of a copolymer of acrylamide and sodium acrylate can significantly increase the productivity of the process layer firing pellets. This is due to the change in the structural properties of the raw pellets, allowing them to better withstand the stresses of the layer to heat treatment.

First, according to the invention the use of a copolymer of acrylamide and sodium acrylate as a binder provides the ability to get raw pellets narrow particle size distribution. It is known that a layer of granules of the same size has a higher permeability than the layer of the heterogeneous granules.

Secondly, in comparison with known binder is a copolymer of acrylamide and sodium acrylate allows to obtain the crude pellets with higher porosity and thermal stability, which allows to significantly increase the speed of drying.

Thirdly, at the stage of drying when the effect of wetlands, the pellets containing the copolymer of acrylamide and sodium acrylate, dissolved in a small degree and well retain a spherical shape. As a result, the permeability of the layer dried on the of Atisha high enough, which allows you to accelerate the subsequent processes of heating, firing and cooling.

Thus, when using a copolymer of acrylamide and sodium acrylate are prerequisites to accelerate all stages of the process of heat treatment and, thereby, to increase performance.

According to the invention is a copolymer of acrylamide and sodium acrylate can be used as a self-binder, and combined with a mineral binder previously known: the bentonites and other clay, marl, lime, etc. In the second case, when the combined use of organic and mineral binding, regulation of their correlation allows to optimize the quality of the end product, the progress and performance of the process of agglomeration. Depending on the initial conditions (as charge materials, equipment and tasks, the regulation of the ratio of the binder to achieve maximum performance, highest quality and low cost processing.

During sintering the mixture containing the original wet ingredients, additive mineral binders may be used to absorb the excess (with respect to optimal in the given technological conditions) the amount of moisture and, thereby, stabilize the aggregation process with a copolymer of acrylic is IDA and sodium acrylate. When using mineral polymer binder can also be used as a fluxing material. In other cases, it is preferable to use a copolymer of acrylamide and sodium acrylate in the role of the self-binder.

In the production fluconazolo okuskovannogo product of fluxing material (limestone, dolomitic limestone, dolomite, bauxite, chalk etc) to impose, as a rule, in the form of crushed dry powder. According to the invention is a copolymer of acrylamide and sodium acrylate may be introduced into the mixture either separately or in the form of pre-prepared multicomponent mixture of fluxing materials.

In the production of iron ore sinter (hardening sintering method) in the charge to use the fuel, mainly toxic and coal. With the aim of reducing fuel consumption in the kiln and improve product quality in the production of pellets and briquettes in the charge can also be used fuels, including coal and coal dust, as well as peat and other combustible organic substances. In these cases, the copolymer of acrylamide and sodium acrylate is metered separately or in a mixture with the used fuel.

All materials listed above (copolymer of acrylamide and sodium acrylate, mineral binders, fluxing materials and fuel) can be added to the mixture in the form of pre-training is blennow two, three or any multicomponent mixture.

Evaluation of the effectiveness of the invention was carried out on the Oskol Electrometallurgical plant.

Example.

As one component of the mixture used iron ore concentrate containing, wt.%: Fetotal69,70; SiO22,90; CaO 0,25; with a specific surface area 2130 cm2/g, the initial moisture content of 9.6%. As a binder used is a copolymer of acrylamide and sodium acrylate - anionic polyacrylamide in the form of dry, free-flowing powder of particle size less than 200 microns. The dosage of binder ranged from 0.07 to 0.10 kg per tonne of iron ore concentrate. Additionally, limestone was used as the fluxing component of the charge. After stirring the mixture in a rotary mixer she was subjected to aging for 30 to 40 minutes. Pelletizing the mixture held in the drum okomkovatelej. The compressive strength of raw pellets amounted to 1.2 kg/pellet, which corresponds to the desired transport strength (not less than 1.0 kg/pellet). The heat treatment was carried out on a conveyor kiln car.

Experiments with different content of the binder in the mixture depending on changes in the moisture content of iron ore concentrate, and adding to the mixture of bentonite. The use of the invention allows to obtain pellets with increased in comparison with the prototype of the iron content of 0.4% and the S. and of sufficient strength for subsequent processing. Comparative information, are shown in table 2.

1. Method of sintering fine material for metallurgical, comprising mixing particles of at least one iron-containing material and a binder, the aggregate mixture and further strengthening of the obtained aggregates, characterized in that the binder material used is a synthetic copolymer of acrylamide and sodium acrylate in which the mole fraction of sodium acrylate may be from 0.5 to 99.5%, a molecular weight in the range from 1·104up to 2·107while the dosage of the synthetic copolymer of acrylamide and sodium acrylate is from 0.02 to 0.10 kg per tonne of iron-bearing material.

2. The method according to claim 1, characterized in that as the iron-containing material used iron ore concentrate, iron ore, tailings, metallurgical production, crushed slag, and other fine iron-containing materials.

3. The method according to claim 1, characterized in that the composition of the charge mixture can be used additional material, including bentonite or other clays, limestone, dolomitic limestone, dolomite, bauxite, chalk, marl, flask, Cox, toxic, coal, coal dust, Thor and other organic combustible substances, as well as mixtures of these materials.

4. The method according to claim 1, characterized in that the copolymer of acrylamide and sodium acrylate can be used in the form of powder, solution, emulsion, suspension, or aerosol.

5. The method according to claim 3, characterized in that the copolymer of acrylamide and sodium acrylate can be used in pure form or in mixture with additional material.

6. The method according to claim 1, characterized in that any of the components of the mixture may be in the wet state.

7. The method according to claim 1, characterized in that when there is insufficient moisture charge mixture, it may be moist.

8. The method according to claim 1, characterized in that between the processes of mixing and aggregation charge matured.

9. The method according to claim 1, characterized in that the aggregation of the charge mixture is carried out by methods of work, briquetting or extrusion.

10. The method according to claim 1, characterized in that the hardening is conducted by the methods of firing or sintering.



 

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