KR101638447B1

KR101638447B1 - Method for producting iron concentrate as sources of direct reduced iron

Info

Publication number: KR101638447B1
Application number: KR1020150047354A
Authority: KR
Inventors: 정수복; 조슬기
Original assignee: 한국지질자원연구원
Priority date: 2015-04-03
Filing date: 2015-04-03
Publication date: 2016-07-13

Abstract

The present invention relates to a high-grade iron concentrate recovering method. The high-grade iron concentrate recovering method comprises: a crushing step of crushing a raw iron ore to a size within a range of 0.5-2.0 mm or smaller; a first magnetic force separation step of forming an ore solution by mixing the crushed iron ore crushed in the crushing step with water, and separating a first iron concentrate attached to a magnet and a first gangue mineral not attached to the magnet from each other by the magnetic separation of the ore solution; a grinding step of grinding the first ore concentrate to penetrate at least 80% or more of the ground iron concentrate through a mesh with a size of 200 mesh having an opening of 0.075 mm; a second magnetic force separation step of separating a secondary iron concentrate attached to the magnet and a second gangue mineral not attached to the magnet from each other by the magnetic separation of the first iron concentrate ground in the grinding step; and a gravity separation step of separating a third gangue mineral with relatively low gravity and a final iron concentrate with relatively large gravity from each other by the gravity separation of the second iron concentrate. The purpose of the present invention is to economically manufacture the high-grade iron concentrate capable of being used as the material for the direct reduction iron.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for recovering a high-quality iron concentrate,

TECHNICAL FIELD The present invention relates to an optoelectronic technology for producing iron concentrates from iron ores, and more particularly, to an optoelectronic technology for producing high-quality iron concentrates from iron ores so that they can be used as raw materials for direct reduced iron produced in electric furnaces.

The production method of iron is divided into the blast furnace steelmaking method using iron ore as a raw material and the direct reduction steel making method using high quality iron ore as high as 68%.

The direct reduction method is a method of producing high-purity concentrate by reducing iron ore by using a reducing gas such as carbon monoxide or hydrogen, and then dissolving the reduced iron in an electric furnace.

On the other hand, steel production using electric furnace is mainly used scrap and waste scrap. As the electric furnace is shorter in initial investment and facility construction period compared to blast furnace, the introduction of electric furnace facilities is increasing in emerging industrial countries. However, the supply of scrap and scrap is not stable, and labor costs and technical problems have been caused to remove impurities from the low grade scrap.

Despite the increase in the introduction of electric furnace production facilities, it has become difficult to supply scrap metal and waste scrap in a stable manner. As a result, Steel manufacturing is increasing.

As raw materials of direct reduced iron, iron ore such as hematite and magnetite, which are produced naturally, is used, and strict quality requirements are required for iron grade and particle size. That is, in order to satisfy the raw material condition of the directly reduced iron, the iron grade should be 68% or more and the impurity element should be hardly mixed, and the particle size may pass 80% or more of the 200 mesh having the sieve of 0.075 mm It should have a particle size distribution.

Iron ore, which is produced naturally, is a high-quality gemstone, and its iron content is about 60% and is produced in mass. Therefore, in order to use it as a raw material of reduced iron, it is necessary to carry out a screening process for grinding and improving iron quality.

However, the conventional process for producing raw materials having a fine iron content of 68% or more from iron ore has been problematic in that it is uneconomical. Particularly, prior to enlightenment, a group separation process of crushing and crushing iron ore into fine particles must precede the process, which was the most uneconomical factor.

Therefore, it is necessary to develop an economical method for selectively recovering only iron minerals from iron ores using the mineralogical difference between iron minerals and impurity minerals.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a method and apparatus for recovering gangue minerals by sequentially pulverizing iron ores containing a large amount of gangue minerals, The present invention is directed to a method for economically producing a high-quality iron concentrate which can be used as a raw material of a directly reduced iron by recovering iron minerals in the form of iron.

According to an aspect of the present invention, there is provided a high-grade iron concentrate recovery method comprising: a crushing step of crushing an iron ore ore source into a range of 0.5 to 2.0 mm or less; And a first magnetic force for separating the primary iron concentrate adhered to the magnet and the primary gangue minerals not attached to the magnet through magnetic force sorting to the optical fluid by mixing water to the iron ore which is impregnated in the crushing step, Selection step; Crushing the primary iron concentrate so as to pass at least 80% of a 200 mesh sieve having a sieve of 0.075 mm; A second magnetic force separation step of separating the secondary iron concentrate attached to the magnet and the secondary gangue minerals not attached to the magnet from each other through magnetic force selection of the primary iron concentrate pulverized in the pulverization step; And a specific gravity separation step of separating a specific gravity from the secondary iron concentrate to separate the tertiary gangue minerals having a relatively small specific gravity from the relatively large final iron concentrate.

In particular, it is preferable that the high-quality iron concentrate recovered by the present invention is used as a raw material of the direct reduced iron.

In an embodiment of the present invention, a magnet having a magnetic force in the range of 1,000 to 3,000 Gauss is used in the first magnetic force selecting step, and in the second magnetic force selecting step, a magnetic force of 1,000 to 2,000 It is preferable to use a magnet having a Gaussian range strength.

Further, in an embodiment of the present invention, the classifier is used in a spiral shape along the vertical direction in the specific gravity separation step.

In the first magnetic force selecting step, the iron ores are mixed in a total amount of 5 to 15 wt% in the whole of the optical fluids.

According to the present invention, a high-grade iron concentrate which can be used as a raw material for directly reduced iron can be produced by treating iron ore. Therefore, it is expected that the iron concentrate prepared by the present invention can be used as a feedstock in electric furnace steel production, but it can be substituted for high grade scrap, which is not stable at present. In addition, it is expected to increase the utilization of iron ore, which is produced naturally, and to enhance added value.

In addition, the crushing cost occupies a large portion in the entire rounding process of natural mineral resources. In the method of the present invention, the crushing is sequentially carried out and the crushing products are sorted according to the particle size, And cost can be reduced.

Above all, in the present invention, it is important that the grinding and magnetic force selection are alternately performed one by one, and the magnitude of the magnets and the particle size according to the pulverization are optimized to improve the recovery rate and the degree of separation of the iron ore and ensure the economical efficiency.

FIG. 1 is a schematic flowchart of a high-grade iron concentrate recovery method according to an embodiment of the present invention.
2 is a schematic configuration diagram of a magnetic separator used in the magnetic force selecting step.
3 is a schematic view of a spiral classifier used in the specific gravity separation step.
The table in FIG. 4 shows the iron content and the recovery rate of the primary iron concentrate recovered in the first magnetic force sorting step by the particle size of the crushed product in the crushing step.
The table of FIG. 5 shows the iron content and the recovery rate of the primary iron concentrate recovered by the magnetic force intensity of the magnet in the first magnetic force selecting step.
The table of FIG. 6 shows the iron content and the recovery rate of the secondary iron concentrate recovered by the magnetic force intensity of the magnet in the second magnetic force selecting step.
The table of FIG. 7 shows the chemical composition of the iron ore ore to be treated in the experiment of the high-grade iron concentrate recovery method according to the present invention.
The table of FIG. 8 shows the results of the experiment of the iron ore described in the table of FIG. 7 by the method according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a high-grade iron concentrate recovery method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic flowchart of a high-grade iron concentrate recovery method according to an embodiment of the present invention.

Referring to FIG. 1, the high-grade iron concentrate recovery method according to an embodiment of the present invention includes a crushing step M10, a first magnetic force selecting step M20, a crushing step M30, a second magnetic force selecting step M40, And a specific gravity separation step (M50).

In general, iron ore is composed of iron-bearing minerals such as iron magnetite, hematite, and gangue minerals such as quartz, feldspar, and amphibole. In terms of elements, iron ore contains silicon (Si), aluminum (Al), calcium (Ca), magnesium (Mg), sodium (Na), potassium (K) and the like as impurity components in addition to the iron component.

The quality of iron ore is determined by the content of iron ore minerals and the amount of gangue minerals incorporated. Removal of gangue minerals is therefore essential to produce high-grade iron concentrates.

In order to separate minerals from gangue minerals and gangue minerals, it is first necessary to separate them. Group separation refers to the crushing of useful minerals and dancing minerals, in this case crushed minerals and gangue minerals, into fine particles, that is, single particles, so as to have the characteristics inherent to each mineral. When the hammerite and gangue minerals are combined in one lump, the hammer minerals and gangue minerals are separated from each other by finely crushing the lumps. However, the group separation does not mean that it is strictly separated by mineral at the chemical level, so gangue minerals are partially contained in the single particles separated by the iron minerals, and the gangue minerals are partially contained in the gangue minerals.

In the present invention, the crushing step (M10) is for separating the iron ores from each other. The important point is the determination of iron ore size. The determination of iron ore size should take into account two factors: improvement in group separation and economic improvement. In view of the improvement of the group separation, the iron ore must be crushed to a certain size to determine whether the iron and gangue minerals can be clearly separated. Generally, the smaller the size of the particles due to the increased amount of pulverization, the greater the degree of single separation, which is advantageous for the subsequent separation process. However, from the viewpoint of economy, it is very disadvantageous to reduce the particle size. Crushing iron ore finely means increasing the crushing cost. The cost of crushing is the largest portion of the costs required for the entire optical fiber. Therefore, it is not preferable from the viewpoint of economical efficiency to reduce the unconditional particle size in order to improve the degree of group separation.

Since the iron concentrate produced in the present invention is intended to be used as a raw material of the direct reduced iron, it is necessary to satisfy the conditions of the raw material of the direct reduced iron. That is, the raw material of the directly reduced iron should pass at least 80% of the 200 mesh sieve having the 0.075 mm sieve. However, in order to crush the iron ore to the above level in a state where there is no group separation, the cost of crushing is excessively demanded, and the economical efficiency of the beneficiation is seriously degraded. Accordingly, in the present invention, a crushing step (M10) for crushing the iron ore ore (A) to a size of about 0.5 to 2 mm is preceded.

The table in FIG. 4 shows the iron content and recovery rate of the primary iron concentrate separated by using 2,000 gauss magnets in the first magnetic force selecting step (M20), which is performed after the iron ore is crushed to various particle sizes in the crushing step (M10) Lt; / RTI > As shown in the table in FIG. 4, the smaller the particle size of the crushed product in the crushing step, the higher the iron content and the lower the recovery rate. However, considering the iron content and recovery rate against crushing cost, Or less.

As described above, if the iron ore is crushed to a size of about 0.5 to 2 mm in the crushing step (M10), the degree of separation of iron and gangue minerals is about 50% or more.

When the crushing step M10 is completed, the first magnetic force selecting step M20 is performed. That is, water is added to the crushed iron ore in a size of 0.5 to 2 mm to prepare a slurry-like optical fluid. At this time, the mixing amount of iron ore in the entire optical fluid is maintained in the range of 5 to 15% by weight with respect to the whole optical fluid. If the concentration of the light liquid is lower than 5% by weight, the amount of iron ore that can be treated at one time is too low, and if it is more than 15% by weight, the separation due to magnetic force is lowered.

After the formation of the mineral liquid, the primary magnet concentrate and the primary gangue mineral (B) are separated by wet magnetization using a permanent magnet. The primary iron concentrate contains iron so that it is easily attached to the permanent magnet due to the magnetic force, but the gangue minerals are not attached to the permanent magnet because they are not sensitive to the magnetic force. Of course, gangue minerals are included in the primary iron concentrates separated by magnetic separation, and the iron gangue minerals are included in the primary gangue minerals (B). The content of gangue minerals in the primary iron concentrate or the content of iron ore in the primary gangue minerals (B) is determined by the strength of the magnet. If the magnitude of the magnet is very large, only a small amount of iron concentrate will remain in the primary gangue minerals, but primary iron concentrates may contain gangue minerals in large quantities. That is, when the intensity of the magnet is large, the recovery rate of iron is increased, but the degree of separation is lowered. This is because all of them are separated into primary iron concentrates even if they are slightly magnetic.

Conversely, lowering the magnitude of the magnet will rarely include gangue minerals in iron concentrates, but primary gangue minerals will contain many iron minerals. That is, although the separation degree is increased, the iron recovery rate is lowered, which is not preferable.

In the field of beneficiation, it is the two most important points, namely, the above-mentioned recovery rate and separation, and how to harmonize economic efficiency. Since the principle of iron ore selection is well known, the important point is how to set the conditions when implementing these principles. In the present invention, the strength of the permanent magnet used in the first magnetic force selecting step (M20) is set to a range of 1,000 to 3,000 Gauss through a number of experiments as an optimum condition for achieving the above three objects.

The table of FIG. 5 shows the iron content and the recovery rate of the recovered primary iron concentrate while changing the magnetic force intensity in the first magnetic force sorting step for the product crushed to a particle size of 1 mm or less in the crushing step. As shown in the table of FIG. 5, the primary iron concentrate recovered in the magnetic force range of 1,000 to 3,000 Gauss showed a good iron quality and recovery rate although there was a slight difference according to the magnetic strength.

As shown in FIG. 2, when iron ore (A) is supplied to a cylindrical magnet pulley (11) having permanent magnets embedded therein, the iron ores, which are sensitive to the magnetic force, The primary gangue minerals B which are not responded are discharged together with water to the lower part of the separation tank 12. Particularly, in the present invention, when the first magnetic force sorting is conducted in a wet manner, the crushed iron ore particles are easily dispersed, thereby increasing the screening efficiency.

As described above, after completing the first magnetic force selecting step M20, the milling step M30 is performed on the primary iron concentrate. In the pulverization step (M20), the primary iron concentrate is pulverized to a level at which 80% of the primary iron concentrate passes through a 200 mesh sieve having a 0.075 mm sieve so that the primary iron concentrate satisfies the raw material conditions of the directly reduced iron. The important point is that since the gangue minerals were primarily removed in the first magnetic separation stage (M20), the amount of pulverization was remarkably reduced. If the mill is to be crushed to a degree satisfying the raw material condition of the reduced iron directly in the crushing step (M10), the entire amount of the iron ore must be crushed, so that the amount of crushed must be increased and the economical efficiency is inevitably lowered. However, in the present invention, the economical efficiency of the bar grinding process which has been subjected to the preceding step of already separating the primary gangue minerals is improved.

After the pulverization step (M30), the secondary iron concentrate and the secondary gangue mineral (C) are separated again from the primary iron concentrate through a second magnetic force selection step (M40). The secondary gangue minerals C are separated from the primary iron concentrate through the second magnetic force selecting step M40 since the primary iron concentrate is changed into fine particles through the pulverization step M30, Can be removed. That is, in the second magnetic force selecting step (M40), the magnetic minerals including iron are attached to the magnets and classified as the secondary iron concentrates. Since the non-magnetic minerals not containing iron are not attached to the magnets, (C). The second magnetic force selecting step (M40) is also performed by a wet type, and the magnet uses a magnet having a Gaussian intensity of 1,000 to 2,000 which is weaker in intensity than the magnet used in the first magnetic force selecting step (M20). If the recovery rate of iron is increased by using a magnet having a relatively large intensity in the first magnetic force selecting step M20, the second magnetic force selecting step (M40) .

The table in FIG. 6 shows the iron content and recovery rate of the secondary iron concentrate attached to the magnet according to the magnetic force intensity in the second magnetic force selecting step. As shown in the table of FIG. 6, when the magnetic force is increased, the iron content is lowered and the recovery rate is increased. In the range of the magnetic force of 1,000 to 2,000 Gauss, the screening efficiency is good.

As described above, after the second magnetic force selecting step (M40), the specific gravity separation step (M50) is performed on the secondary iron concentrate. Secondary iron concentrates may contain aggregates of fine gingival minerals. That is, the minerals formed by the two crushing and crushing steps can be adhered to the secondary iron concentrate in a state of aggregation by electrical action or the like. When the particle size is large, the coagulation phenomenon does not appear. However, if the particle size is large, the iron ore and gangue minerals may be weakly bound by aggregation. In the specific gravity separation step (M50), separation is performed using the fact that the sedimentation speed of the particles in the water differs depending on the specific gravity.

In particular, in this embodiment, as shown in FIG. 3, a spiral classifier 20 having a spiral screw is used along the vertical direction. In other words, when the secondary iron concentrate is mixed with water and put into a spiral classifier, the tertiary gangue mineral (D) with a low specific gravity is discharged along with water to the bottom of the classifier due to gravity, The iron concentrate E) is transferred to the upper part by the rotation of the helical screw and discharged. The third gangue mineral (D) is removed from the secondary iron concentrate, and the final product, the tertiary iron concentrate (E), can be obtained. The spiral classifier is a device that simultaneously transfers and classifies fine particles by rotating a helical screw, which enables large-scale processing, and is economical and easy to operate. As a result of classifying secondary iron concentrate with iron grade of 69.9wt%, the final iron concentrate with iron grade of 70.6wt.% Was recovered.

The naturally occurring iron ores according to the present invention can effectively remove gangue minerals containing impurity components contained in iron ores and recover iron minerals composed only of iron components. The present invention is based on the difference in mineralogical characteristics between iron ore and gangue minerals, and in separating and selecting two materials, the iron ore is sequentially pulverized in two stages, Can be minimized. The final iron concentrate to be finally separated and recovered has a quality standard that can be used as a directly reduced iron raw material because it passes over iron content of more than 68% and particle size of 200 mesh is more than 80%.

Hereinafter, an example of an experiment of a high-grade iron concentrate recovery method according to the present invention will be described.

In this study, iron (Fe), iron (Fe), and iron (Fe) were investigated. The iron (Fe) , Sodium (Na), etc. The chemical composition of iron ore is shown in the table of FIG. In the iron ore having the chemical composition as shown in the table of FIG. 7, the same process as shown in FIG. 1 was applied to remove impurities and recover only the iron component. The particle size and the magnetic field strength , And the name of the product.

The iron ore (A) was crushed to a particle size of 1 mm or less by the method shown in FIG. 1, and water was added to adjust the concentration of the solution to 10 wt.%. The produced mineral fluid was recovered by adhering the iron mineral to a cylindrical magnet pulley having a magnetic force of 2,000 gauss in the primary magnetic force sorting, and removing the gangue minerals (B) not attached to the magnet.

Since the recovered primary iron concentrate contains particles that are not completely separated from the iron minerals and gangue minerals, they are crushed to have a particle size suitable for the quality standard of the directly reduced iron raw material, 80% of the total.

Secondary iron concentrates and secondary gangue minerals (C) were separated and separated in the second magnetic force screening with a magnetic force of 1,000 Gauss. The secondary iron concentrate was classified to remove the impurity components (tertiary gangue minerals (D)) that had been aggregated in the iron concentrate and recover the final iron concentrate (E). FIG. 8 is a table showing the iron content and the iron recovery rate of each product.

As shown in the table of FIG. 8, iron ore having an iron content of 34.9 wt.% Was treated with 43.2 wt.% Of final iron concentrate having an iron content of 70.3 wt.%, And the iron recovery rate was 86.7% Respectively. The recovered final iron concentrate, such as grain size and iron quality, were suitable to the quality standard of the directly reduced iron raw material.

M10 ... crushing step, M20 ... first magnetic force selecting step
M20 ... crushing step, M30 ... second magnetic force selecting step
M50 ... specific gravity separation step
10 ... magnetic separator 20 ... spiral classifier

Claims

A crushing step of crushing the iron ore ore into a range of 0.5 to 2.0 mm or less;
The pulverized iron ore is mixed with water to form a light liquid. The pulverized primary iron concentrate is attached to a magnet having a magnetic force in the range of 1,000 to 3,000 Gauss through the magnetic force, and the primary gangue A first magnetic force selecting step of mutually separating minerals;
A pulverizing step of pulverizing the primary iron concentrate so as to pass at least 80% of a 200 mesh sieve having a sieve of 0.075 mm;
A second magnetically separating step of separating the secondary iron concentrate attached to the magnet having a magnetic force in the range of 1,000 to 2,000 Gauss and the secondary gangue minerals not attached to the magnet through magnetic force selection to the primary iron concentrate pulverized in the pulverization step ; And
And a specific gravity separation step of separating the secondary iron concentrate from the tertiary gangue minerals having a relatively small specific gravity and relatively large final iron concentrate by separating the specific gravity from the secondary iron concentrate,
Wherein the final iron concentrate is used as a raw material of the direct reduced iron.

delete

The method according to claim 1,
Wherein a spiral separtor formed in a spiral shape along a vertical direction is used in the step of separating the specific gravity.

The method according to claim 1,
Wherein the iron ores are mixed in an amount ranging from 5 to 15% by weight based on the total weight of the optical fluids.