KR101380806B1 - Method for processing sludge - Google Patents

Abstract

The present invention relates to a method of processing by-products. The method of processing by-products includes: a preparation step of preparing by-products generated in a steel making process; a dry disintegration step of disintegrating the by-products; a step of classifying the by-products into a plurality of treatment matters having related particle size ranges according to the difference in particle diameter between the disintegrated by-products; a dry-sorting process of sorting remaining treatment matters other than a treatment matter having the smallest particle size in order from a heavy treatment matter to a lightweight treatment matter based on the difference in weight between the treatment matters; and a dry magnetic-force classification step of classifying the treatment matters having the higher weight and the treatment matters having the lowest particle size range according to non-magnetic materials and magnetic materials. [Reference numerals] (AA) Prepare by-products; (BB) Dry-disintegration; (CC) Dry-sieving; (DD,EE,FF,GG,HH) Dry-classification; (II) Concentrate 1; (JJ) Dry-magnetic force classification; (KK) Magnetic concentrate (concentrate 2); (LL) Tailings

Description

[0001] The present invention relates to a method for processing sludge,

The present invention relates to a by-product treatment method, and more particularly to a by-product treatment method that can recycle by-products generated in the steelmaking process.

The burden on raw material costs for steelmaking costs is increasing due to rising raw material prices such as iron ore and coal. For example, annual imports of iron ore, steelmaking raw materials, amount to about 50 million tons, amounting to about 6.5 trillion won (110 ＄ / ton). By-products of steel are produced by-products of slag and dust types in all processes with dry / wet dust collectors in the steel manufacturing process. Such by-products contain a large amount of effective materials such as raw materials and fuel materials used in the steelmaking process. If 20% of 400,000 tons are recycled each year and 70% of direct reduced iron (60% or more of total iron) is recovered from the reprocessed by-products, 280,000 tons (200,000 won / ton) will be obtained. Raw material costs can be reduced. Here, if the by-product treatment capacity increases according to the recycling treatment technology, the economic effect will increase further. Therefore, various efforts are required to select effective substances from by-products in terms of cost reduction and resource recycling.

Dust generated in the steelmaking process contains a large amount of various impurity components generated in the process in addition to iron ore, which is a main component, which limits the amount of dust used in recycling as a raw material.

In addition, dust has the possibility of causing various obstacles in operation due to impurities. In recycling such dusts, a method of recycling the dusts by mixing with other raw materials and directly reducing iron manufacturing processes, etc. has been developed, rather than the process of removing the impurities from the dust itself. However, due to the characteristics of dust, its physical and chemical properties are not constant and fluctuate, and there is a limit to recycling dust as it is.

In addition, the main component content of steelmaking dust is Fe 20.93%, CaO 30.99%, C 7.27%, etc. Other components are too high and heterogeneous to be used as a raw material for iron or Ca as a substitute for Ca component in the steelmaking process. However, it is possible to recover kish, which can be recycled as a high value-added raw material from steelmaking dust. For example, Kish Graphite is a high value-added raw material that can be traded as of December 2012 at a price of £ 125 / 5g based on class 200, £ 200 / 0.2g based on class 300 and £ 350 / 0.5g based on class 300.

Conventionally, a wet beneficiation method and a flotation screening method using water to separate / recover kishi graphite and ferrous materials from steelmaking dust have been used.

The wet beneficiation method relatively easily separates / recovers active ingredients from steelmaking dust, but incurs additional costs such as dehydration and drying after screening. In addition, in the wet beneficiation process, secondary by-products, namely, waste water, are generated, and a problem arises that additional facilities for waste water treatment must be installed and operated.

Suspension sorting methods use various reagents such as acids to separate / recover active ingredients from dust. Adding additional raw materials (various reagents) to recover active ingredients incurs additional costs for water purification. The two methods generate secondary pollutants (waste water) during the separation / recovery process of the active ingredient from the dust. In addition, additional equipment should be provided for reprocessing secondary pollutants. Therefore, there is a difficulty in the economic aspect that additional costs are generated beyond the purpose of dust recycling technology to reduce initial raw material costs. Therefore, there is a need for a method for effectively screening and recycling effective materials from dust without polluting the environment during the dust recycling process.

KR 1989-0016186 A KR 0423440 B

The present invention provides a by-product treatment method that can extract a high quality raw material from the by-product generated in the steelmaking process.

The present invention provides a by-product treatment method capable of reducing the manufacturing cost by recycling by-products.

The by-product treatment method according to an embodiment of the present invention, a by-product treatment method, the process of preparing the by-products generated in the steelmaking process and the dry crushing process for crushing the by-products and the pulverized by-products according to the difference in particle size Separating the treatment into a plurality of treatments having a range and the treatment except for the treatment having the lowest particle size range of the plurality of treatments to a high mass treatment and a relatively low mass treatment according to the difference in mass A dry classification process and a dry magnetic screening process for sorting the high-mass treatments and the treatments having the lowest particle size range into magnetic and non-magnetic materials.

In addition, the by-product includes the dust generated in the steelmaking process.

In addition, the process of providing the dust includes a drying process for removing moisture.

In addition, the dry disintegration process of disintegrating the by-products includes disintegration under dry conditions using either a scrubber equipped with an impeller or a high speed stirring mixer.

In addition, the process of separating the disintegrated by-products into a plurality of treatments having respective particle size ranges in accordance with the difference in particle size, the electric sieve device having a plurality of sieves having a different mesh size, vertical movement or left and right movement It includes using.

In addition, the plurality of sieves include those having a mesh size of 0.06 mm, 0.075 mm, 0.1 mm, 0.15 mm, 0.2 mm, respectively.

In addition, the plurality of treatments are each greater than 0.2mm, 0.2mm or less to 0.15mm, 0.15mm or less to 0.1mm, 0.1mm or less to 0.075mm, 0.075mm or less to 0.06mm, and less than 0.06mm It includes those having a range.

In addition, the dry classification process, the product of more than 0.2mm 4 to 6L / min, the product of more than 2mm to 0.15mm 2 to 3L / min, the product of less than 0.15mm to 0.1mm 1 To 2 L / min, the product of less than 0.1mm to more than 0.075mm and the products of less than 0.075mm to more than 0.06mm include those selected under flow rate conditions in the range of 0.5 to 1.5L / min.

In addition, the dry classification process may include using at least one of a zigzag air classifier, a cyclone classifier, and an air pressure filtration device using the force of air.

In addition, the low mass treatment is a Kish graphite extract, and the relatively high mass treatment includes an extract mixed with iron and calcium.

In addition, the kishi graphite extract includes having a quality containing at least 75% by weight of carbon when the Kishi graphite extract is 100% by weight.

In addition, the magnetic material includes an iron extract, and the non-magnetic material includes selecting a calcium extract.

In addition, the iron extract includes those having a grade containing 60% by weight or more of iron when the iron extract is 100% by weight.

In addition, the calcium extract includes having a quality containing 44% by weight or more of calcium when the calcium extract is 100% by weight.

The by-product treatment method according to the embodiment of the present invention can recycle dust, particularly among by-products generated in the steelmaking process. In particular, by applying a physical beneficiation process that can be mass-produced and simple in process, it can be extended to recycle various kinds of dust generated in steelworks as well as steelmaking processes.

Further, raw materials containing Kish graphite (C), iron (Fe) and calcium (Ca) can be selectively separated from the dust.

In addition, it can be used as a pretreatment step to improve the quality of the raw material extracted from the dust.

In addition, the by-product treatment method according to an embodiment of the present invention, by using a dry treatment method can reduce the environmental pollution and the cost of the dust treatment process, it is possible to reduce the cost of purchasing raw materials. And a high quality raw material can be extracted from dust, and the quality of the product using this can also be improved.

1 is a flow chart showing a process of by-products according to an embodiment of the present invention.
Figure 2 is a schematic diagram showing a change in by-products by the by-product treatment method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know.

By-product treatment method according to the present invention can obtain a raw material of improved quality than the technology to recycle the dust itself is removed unnecessary components, and in the dust treatment process unlike the conventional wet beneficiation method and flotation screening method using a dry treatment method Does not generate pollutants.

By-product treatment methods include dry pulverization, dry sifting, dry classification, and dry magnetic screening to separate the particles of dust. Through this series of processes, it is possible to selectively separate the raw materials containing Kish graphite (C), iron (Fe), calcium (Ca) from the dust generated in the steelmaking process.

Hereinafter, a by-product treatment method according to the present invention will be described with reference to experimental examples.

Next, dust generated in the steelmaking process used in the present invention will be described with reference to Tables 1 and 2 below.

Provide dust generated in the steelmaking process. Dust is collected by a dust collector, and is prepared after the drying process, which is a pretreatment process. The steelmaking dust provided has a composition as shown in Table 1 below.

ingredient Content (% by weight) T.Fe 20.93 M. Fe 1.98 Ca 30.99 C 7.27 Remainder 38.83

  The major constituent minerals of steelmaking dust are hematite, small lime, limestone and graphite. Looking at the composition of such steelmaking dust it contains 20% by weight or more of the iron (Fe) component used as a raw material of the steelmaking process, and also contains 7% by weight or more of the carbon (C) component.

As a result of performing a particle size test on steelmaking dust, the particle size distribution shown in Table 2 was derived.

Who passes Particle size (㎛) D 10 7.5 D 50 50.9 D 90 310.3

Looking at Table 2, the particle size range of the steelmaking dust composition was relatively wide. Therefore, it is difficult to physically directly select the active substances (iron, kin graphite, calcium) using steelmaking dust having a wide particle size range.

Steelmaking dust has a wide particle size range, and when dry classification is applied as it is, the screening effect due to the difference in specific gravity between components is inferior. This is because the dust particles are extremely finely divided due to the high surface energy, and the screening efficiency is low, steelmaking dust is introduced into the crusher before the dry sifting process so that the dust is uniformly dispersed in the solvent. At this time, the crusher used is a crusher is a facility for performing a dry crushing process using a scrubber or a high-speed stirring mixer equipped with an impeller to perform the pulverization process of steelmaking dust. The impeller is rotated at a speed of about 1000 to 1200 rpm to perform a disintegration process of stirring for 10 minutes. Here, disintegration means a process in which the aggregated dust particles are separated from each other and uniformly dispersed in a solvent. Steelmaking dust subjected to the pulverization process can select the effective substance by applying the screening effect by the difference in specific gravity between the constituent materials.

When the disintegration process is completed, the steelmaking dust which has undergone the disintegration process is put into a dry sieve to perform a process of separating by particle size. For example, the dry sieve process may use an electric sieve device having a plurality of sieves capable of vertical movement or left and right movement. Here, the plurality of sieves have various mesh sizes for selecting effective substances from the constituent materials of steelmaking dust. For example, a dry sifting process can be carried out using an electric sifting device consisting of five sieves with 0.06mm, 0.075mm, 0.1mm, 0.15mm and 0.2mm mesh sizes for steel mill dust which has been crushed. Component analysis results of the particle size separation product by the sieve as shown in Table 3 below.

Size
% Yield Chemical composition (wt%) T.Fe M. Fe Ca C LOI Greater than 0.2mm 3.17 20.62 10.27 9.60 53.62 16.16 0.2mm or less ~ 0.15mm or more 3.88 11.90 3.56 24.72 30.38 33 0.15mm or less
More than 0.1mm 6.25 14.42 3.92 31.87 12.71 41 0.1 mm or less
Greater than 0.075 mm 7.20 14.30 3.01 34.18 9.45 42.07 0.075mm or less
Greater than 0.06 mm 16.71 13.23 2.21 37.29 5.67 43.81 Less than 0.06mm 62.79 24.96 1.09 30.33 3.14 41.57

After the pulverization process is completed, the steelmaking dust passes through a sieve having a mesh size of 0.2 mm and then passes through sieves having a mesh size of 0.15 mm, 0.1 mm, 0.075 mm, and 0.06 mm in order. As shown in Table 3, steelmaking dust is separated into six kinds of particle size treatments. The yield of each treatment was taken as the reference value of 100 wt%, and each chemical component was analyzed by wt%. Here the total weight of each treatment is the sum of T.Fe wt%, Ca wt% and Cwt% and LOI (loss loss on weight) wt%. In this case, T.Fe wt% means total Fe wt%, M.Fe wt% means Metal Fe wt%, and F.Fe wt% includes M.Fe wt% and iron oxide components. In addition, Ca oxide is included in the wt%, and C oxide is also included in the wt%. LOI is the weight percent reduced by heat during chemical analysis.

Dry classification is performed using an air classifier for steelmaking dusts of 0.06mm or more with the applicable particle size among the steelmaking dusts classified into the particle size range. The dry classification process classifies steelmaking dust separated into each particle size range under the following flow rate conditions. 4 to 6 L / min for steelmaking dust exceeding 0.2 mm, 2 to 3 L / min for steelmaking dust exceeding 0.2 mm or less, 1 to 2 L / min for steelmaking dust exceeding 0.15 mm or less and 0.1 mm, For steelmaking dust of 0.1 mm or less and more than 0.075 mm and 0.075 mm or less and more than 0.06 mm, dry classification is performed under the flow rate conditions of 0.5 to 1.5 L / min. Here, the air classifier may be used to separate steelmaking dust of each particle size range into O / F and U / F using at least one of a zigzag air classifier, a cyclone classifier, and an air aspirator as the flow rate conditions. Can be. In addition, when dry classification progresses below the reference range of each flow rate condition, the recovery rate decreases, and when the reference range is exceeded, the quality of the effective substance recovered is lowered. Through the dry classification process using the force of air under the flow rate conditions, steelmaking dust classified into each particle size range was each O / F (over flow) product, which is a product of classification, and iron (Fe) and calcium ( The Ca component can be separated into concentrated under flow (U / F) products. O / F and U / F are classified according to the difference in the size and mass of the powder in the classifier. Since the size of the powder is classified in the sifting process, it is classified according to the difference in the mass of the powder in the dry classification process. Kish graphite extracts containing carbon can be obtained from the classified O / F.

When the dry classification process is completed, a dry magnetic screening process is performed in which iron / dust products having a particle size of less than 0.06 mm and steelmaking dust having a particle size of less than 0.06 mm are input to the magnetic screening device. . The magnetic screening process may be performed using a dry magnetic screener that does not use mineral liquid. In the dry magnetic screening process, the magnetic screening process was performed in the first stage in order to improve the quality of the active material, that is, the quality of the iron (Fe) component. At this time, the magnetic screening process may be carried out in a multi-step, and if performed over more orders may be added in a number of times that the recovery rate of the iron, which is an effective material does not decrease.

Next, a description will be given of a method of applying dry magnetic screening to each U / F product having a dry classification process for each particle size range used in the present invention and steelmaking dust having a particle size of 0.6 mm or less.

Figure 2 is a schematic diagram showing a change in by-products by the by-product treatment method according to an embodiment of the present invention.

The following magnetic screening process selects magnetic materials (concentrate 1) and non-magnetic materials (tailings 1) from steelmaking dust with a particle size of 0.6 mm or less and each U / F product that has been subjected to the dry classification process by particle size range. At this time, the magnetic screening process may be performed using a magnetic force of more than 3,000 to 10,000 Gauss strength. For example, after completion of the dry classification process, dry magnetic screening is performed on U / F products of each particle size range and products of 0.06 mm or less, respectively, and selected / contained by the active substance concentrate (iron) (Fe) and tailings calcium (Ca). Separate. The magnetic separator used for the dry magnetic separator may use at least one of a rolled or belt type magnetic separator having a magnetic flux density of 3,000 or more to 10,000 or less Gauss. Here, when the magnetic flux density is less than 3,000 Gauss, the recovery rate of the effective substance decreases, and if the magnetic flux density exceeds 10,000 Gauss, the quality of the effective substance recovered falls. Under the above conditions, through the dry magnetic screening, the extract containing the active substance, namely iron (Fe), and the tailings calcium (Ca), for the U / F products of each particle size range and the products of 0.06 mm or less through dry magnetic screening One extract can be selected / separated.

Table 4 below shows the results of analyzing the components of the selected material through the by-product treatment process according to an embodiment of the present invention.

product
Yield (wt%)
Chemical composition wt% Recovery%
T.Fe M. Fe Ca C LOI Ore 100.0 20.93 1.98 30.99 7.27 40.81 - Kish Graphite (Concentrate 1) 3.8 4.28 0.45 7.95 75.37 12.4 C 39.39 Fe magnetic screening (concentrate 2) 28.3 60.1 6.31 2.6 6.2 31.1 Fe 81.26 Ca magnetic screening (tailings) 67.9 5.6 0.27 44.1 3.9 46.4 Ca 96.62

Looking at the effective material and the raw material selected in this way, that is, the recovery rate of the effective material from ore is as follows. The recovery rate (%) can be calculated by the following equation (1).

Referring to Table 4, the recovery rate of each product is calculated by Equation 1 above, and the grade of each product is a numerical value containing the chemical component in each product based on the yield rate of each product (wt%) It is decided by).

Kish Graphite (Concentrate 1) Extract The yield of Kish graphite extract, which can replace natural graphite from steelmaking dust, is 3.8%, and the content of carbon (C) and carbon oxides is 100. Kish graphite extract having a weight% of grade was obtained by the equation (1) with a 39.39% recovery. Therefore, a high-quality kishi graphite extract containing a large amount of carbon and carbon oxides compared to steelmaking dust (ore) can be obtained with a recovery rate of 39% or more.

The yield of iron (Fe) extract (concentrate 2), which can be recycled by replacing iron ore raw materials, is 28.3%, and the iron extract having a grade of 60.1% of iron and iron oxide when the total amount of iron extract is 100% by weight. It can be stroked with 81.26% recovery by the above equation (1). Therefore, a high-quality iron extract containing a large amount of iron and iron oxide compared to steelmaking dust (ore) can be obtained with a recovery rate of 81% or more.

The yield of calcium (Ca) extract that can be recycled in place of the secondary raw material is 67.9%, the calcium extract having a quality of 44.1% by weight of calcium and calcium oxide when the total amount of calcium extract 100% by weight 1 could be obtained with a recovery rate of 96.62%. Therefore, a high-quality calcium extract containing a large amount of calcium and calcium oxide can be obtained with a recovery rate of 96% or more compared with steelmaking dust (ore).

Kishi graphite extract, iron extract, calcium extract prepared by the by-product treatment process according to an embodiment of the present invention shows a higher content than the raw material, that is, C, Fe, Ca content contained in steelmaking dust. Therefore, it can be seen that the grade of the active substance selected by the present invention is relatively high compared to steelmaking dust.

The following describes a by-product process according to an embodiment of the present invention.

1 is a flow chart showing a process of by-products according to an embodiment of the present invention.

First, a by-product, that is, steelmaking dust is prepared (S100). Here, the steelmaking dust is prepared by completing a drying process for removing moisture from the steelmaking dust collected by the dust collecting facility.

Thereafter, a dry pulverization process is performed on the provided steelmaking dust (S200). Since the disintegration process has been described in detail above, it is omitted.

Thereafter, the sample is separated by particle size through a dry sieve process for the sample in which the disintegration process is completed (S300). As described above, the sample that has been disintegrated through a dry sieve equipped with a plurality of sieves is separated into treatments having respective particle size ranges. In the embodiment of the present invention, the samples of which the disintegration process is completed were separated into treatments having six particle size ranges using sieves having five different sieve sizes. Herein, the sizes of the sieves may be changed, and the number of sieves used may be changed.

After that, sorting / separating into high mass and relatively low mass through the dry classification process for the treatments except the one with the lowest particle size among the treatments separated by each particle size range (S400). Concentrate 1 can be produced here.

Thereafter, concentrates 1 and tailings are separated through a dry magnetic screening process on the U / F products for each particle size range where the dry classification process is completed and the products having the lowest particle size range among the products separated by the dry sifting process ( S500). Here, concentrate 1 and tailings can be produced by dry magnetic screening.

Although the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

Claims (14)

As a by-product treatment method,
Preparing by-products generated from the steelmaking process;
A dry crushing process of crushing the by-products;
Separating the pulverized by-products into a plurality of processed materials having respective particle size ranges according to differences in particle diameters;
Dry classifying the treatments other than the treatment having the lowest particle size range among the plurality of treatments into a high mass treatment and a relatively low mass treatment according to a difference in mass;
A dry magnetic screening process for sorting the high-mass processed materials and the processed materials having the lowest particle size range into magnetic materials and non-magnetic materials;
By-product treatment method comprising a. The method according to claim 1,
The by-product is a dust by-product treatment method generated in the steelmaking process. The method of claim 2,
The process of preparing the dust by-product processing method comprising a drying step of removing moisture. The method according to any one of claims 1 to 3,
Dry crushing process of crushing the by-products,
A by-product treatment method of disintegrating under dry conditions using either a scrubber equipped with an impeller or a high speed stirring mixer. The method according to any one of claims 1 to 3,
The process of separating the pulverized by-products into a plurality of treatments having respective particle size ranges according to the difference in particle diameters includes a plurality of sieves having different mesh sizes, and uses an electric sieve device capable of vertical movement or horizontal movement. By-product treatment method. The method of claim 5,
The plurality of sieves are each by-product method having a mesh size of 0.06mm, 0.075mm, 0.1mm, 0.15mm, 0.2mm. The method according to claim 1,
The plurality of treatments each have a particle size range of greater than 0.2 mm, less than 0.2 mm to more than 0.15 mm, less than 0.15 mm to more than 0.1 mm, less than 0.1 mm to more than 0.075 mm, less than 0.075 mm to more than 0.06 mm, less than 0.06 mm. Process by-products having. The method of claim 7,
The dry classification process,
The product of more than 0.2mm is 4 to 6L / min, the product of more than 2mm to 0.15mm is 2 to 3L / min, the product of more than 0.15mm to 0.1mm is 1 to 2L / min, the 0.1mm or less By-products of more than 0.075mm and products of less than 0.075mm to more than 0.06mm are selected by the flow rate conditions in the range of 0.5 to 1.5L / min. The method according to any one of claims 1 to 3 and 9,
The dry classification process, by-product treatment method using at least one of a zigzag air classifier, a cyclone classifier, an air pressure filtration device using the force of the air. The method according to any one of claims 1 to 3,
The low mass treated product is a Kish graphite extract, and the relatively high mass processed product is an iron and calcium mixed extract. The method of claim 10,
The kishi graphite extract is a by-product treatment method having a grade containing at least 75% by weight of carbon when the Kishi graphite extract to 100% by weight. The method of claim 10,
The by-product treatment method for selecting the iron extract as the magnetic material, calcium extract as the non-magnetic material. The method of claim 12,
The iron extract is a by-product treatment method having a grade containing more than 60% by weight of iron when the iron extract to 100% by weight. The method of claim 12,
The calcium extract is a by-product treatment method having a quality containing at least 44% by weight of calcium when the calcium extract to 100% by weight.

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