Iron-containing material recycled from iron powder sludge as well as recycling method and application of iron-containing material

Abstract

The invention discloses an iron-containing material recovered from iron powder sludge and a recovery method and application thereof, and belongs to the technical field of comprehensive utilization and recovery of industrial solid waste resources. The method comprises the steps that firstly, the iron powder sludge is subjected to dehydration-baking treatment, then the baked dry iron powder sludge is subjected to crushing, screening and magnetic separation, concentrate and magnetic separation remaining materials are obtained, then the magnetic separation remaining materials are separated through a powder concentrator, coarse materials and powder are obtained, the powder is collected in a negative pressure mode, and micro powder is obtained; according to the method, high-efficiency separation and resource utilization of different grades of iron components in the iron powder sludge are realized, the process is energy-saving and environment-friendly, and the recovery rate is high; the recovered concentrate, coarse material and micro powder can be respectively applied to preparation of sintered ore, drying agent and concrete.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of comprehensive utilization and recycling of industrial solid waste resources, and particularly relates to a kind of iron-containing material recovered from iron powder sludge and its recycling method and application. BACKGROUND

[0002] Iron powder is often used as a reducing agent in the process of producing titanium dioxide by sulfuric acid method. In the process of producing iron powder, during the washing and sorting stage, non-iron-containing materials with fine particle size enter the circulating water in the form of sludge to form a slurry. After the slurry is settled in a settling tank, it is pumped to a concentration tank, where a flocculating agent is added to promote the agglomeration of the material. After concentration, the slurry is pressed to a filter press to remove excess water. The amount of iron powder sludge pressed out is equal to the amount of iron powder produced, and the water content is maintained at 25-30%, the metallic iron content is maintained at 5-8%, and the total iron content is maintained at 40-45%. The total iron content of the sludge cannot directly meet the total iron requirement of sintering materials, so other high-iron-containing materials need to be added. However, the sludge contains a certain amount of water and a small amount of flocculating agent, so it is difficult to mix and mix unevenly when the sludge is mixed with other high-iron-containing materials, resulting in large composition segregation. Therefore, the sludge and other iron-containing materials need to be mixed and ground by a small ball mill after being mixed in a certain proportion, and then dried. Or the sludge is dried on a cement floor, and then mixed and turned by a loader until it is evenly mixed, which is labor-intensive and has large composition segregation.

[0003] Therefore, it is necessary to develop a method for efficiently and selectively recovering iron-containing materials from iron powder sludge to improve resource utilization and economic efficiency. SUMMARY

[0004] To solve the above technical problems, the present application discloses a kind of iron-containing material recovered from iron powder sludge and its recycling method and application to solve the technical problem of low resource utilization rate of iron powder sludge in the prior art.

[0005] To solve the technical problem, a method for recovering iron-containing material from iron powder sludge is provided, which includes the following steps: S1: spread and turn the iron powder sludge for dehydration until the water content of the iron powder sludge is 5-8wt%; S2: bake the dehydrated iron powder sludge to a water content of <1wt% to obtain dry iron powder sludge; S3: crush and sieve the dry iron powder sludge to obtain a sieved material and a powder A, and magnetically separate the sieved material to obtain a concentrate and a magnetic separation residue; the TFe content of the concentrate is ≥50wt%; S4: separating the magnetic separation residual material through a powder separator to obtain coarse material and powder B, and collecting the powder A and the powder B through a negative pressure mode in a closed environment to obtain a micro powder; the TFe content of the coarse material is 10-15wt%, and the TFe content of the micro powder is less than 10wt% and the proportion of the material under the 200 mesh screen is greater than or equal to 98%.

[0006] Based on the technical scheme, the application can be further improved as follows.

[0007] Further, the iron powder sludge composition in step S1 includes 5-15wt% MFe, 30-45wt% TFe, 10-20wt% H2O, 5-15wt% SiO2, 10-20wt% CaO, 5-15wt% MgO, 1-5wt% Al2O3, 0-1.0wt% P and 0-1.0wt% S.

[0008] Further, the iron powder sludge particle size distribution is that the material content above the 40 mesh screen is less than 5wt%, the material content in the 40-100 mesh screen interval is 10-15wt%, the material content in the 100-150 mesh screen interval is 30-35wt%, the material content in the 150-200 mesh screen interval is 25-30wt%, and the material content under the 200 mesh screen is 20-25wt%.

[0009] Further, the paving thickness in step S1 is less than or equal to 80mm, and the turning mode is to turn once every 8-10h.

[0010] Further, the baking temperature in step S2 is 100-150℃, and the iron powder sludge paving thickness during baking is 30-50mm.

[0011] Further, the screen mesh size of the screening in step S3 is 1-3mm, and the magnetic field strength of the magnetic separation is 1000-3000GS.

[0012] The application further discloses an iron-containing material recovered by the above recovery method, which includes a concentrate with a TFe content of more than or equal to 50wt%, coarse material with a TFe content of 10-15wt%, and micro powder with a TFe content of less than 10wt%.

[0013] The application further discloses an application of the concentrate in preparing sintered ore.

[0014] The application further discloses an application of the coarse material in preparing a drying agent.

[0015] The application further discloses an application of the micro powder in preparing concrete.

[0016] The application has the following beneficial effects: 1、The present application realizes the efficient separation of different grade iron components in the iron powder sludge through a series of process steps such as dehydration-baking-crushing-screening-magnetic separation and powder separator separation, which not only improves the recovery rate of iron resources, but also enables the recovered iron-containing materials to be resource utilization according to their grade and characteristics. The recovered concentrate can be used to prepare sintered ore; the coarse material can be used to prepare drying agent, which can be used in industrial production, such as shoes, luggage, handbags, toys, hardware and other industries, drying and moisture-proof, delaying the storage period of goods; the micro powder can be used to prepare concrete. DETAILED DESCRIPTION

[0017] The above method for classifying and recovering iron-containing materials from iron powder sludge is further described in detail through the following examples.

[0018] Example 1 The components included in the iron powder sludge in this example are shown in Table 1; the particle size distribution of the iron powder sludge is shown in Table 2.

[0019] Table 1

[0020] Table 2

[0021] A method for recovering iron-containing materials from iron powder sludge, the method comprising the following steps: S1: The iron powder sludge is spread on a clean cement floor, the thickness of the spread is 60-80mm, after the spreading is completed, the material is turned over for dehydration at time intervals of 9h20min, 8h55min, 9h30min, 9h25min, 8h40min, 9h45min, 8h50min and 9h30min respectively, when turning over, the loader is used to crush the blocks larger than 100mm, after the last turning, the moisture content of the iron powder sludge is detected to be 7.34%; S2: The dehydrated iron powder sludge is transferred to the baking room for constant temperature baking, the baking temperature is 120℃, the iron powder sludge is spread in the baking system with a thickness of 30-40mm, the moisture content of the iron powder sludge is baked to 0.28wt%, and the dry iron powder sludge is obtained; S3: The dry iron powder sludge is crushed by a roll crusher, and then the crushed iron powder sludge is screened through a 2 mm square hole screen in a closed environment to obtain undersize material, oversize material and powder A (powder A is the dust generated in the screening process), the oversize material is crushed and screened again until all the material passes through a 1 mm square hole screen; then, in a closed environment, the screened material is dry-magnetic separated by a magnetic separator, the magnetic field strength of the magnetic separator is 2000 GS, and the concentrate and the magnetic separation residue are separated after magnetic separation, the TFe content of the concentrate is 53.64%, and the MFe content is 8.67%; S4: The magnetic separation residue is separated by a powder separator to obtain coarse material and powder B, the TFe content of the coarse material is 12.84%, the powder A and the powder B are collected by a dust removal system through negative pressure to obtain micro powder, the micro powder is collected by 8 dust removal bags, and the TFe content of the micro powder is 8.69wt%; the concentrate accounts for 72.87wt%, the coarse material accounts for 17.49wt%, and the micro powder accounts for 9.64wt%.

[0022] Example 2 The components of the iron powder sludge in this example are shown in Table 3; the particle size distribution of the iron powder sludge is shown in Table 4.

[0023] Table 3

[0024] Table 4

[0025] A method for recovering iron-containing material from iron powder sludge, the method comprising the following steps: S1: The iron powder sludge is spread on a clean cement floor with a thickness of 50-70 mm, after spreading, the material is turned over at time intervals of 9h20min, 9h55min, 9h30min, 9h25min, 8h40min, 9h45min, 9h50min and 9h30min for dehydration, when turning over, a loader is used to crush the blocks larger than 100 mm, and the moisture content of the iron powder sludge is 5.14% after the last turning over; S2: The dehydrated iron powder sludge is transferred to an oven for constant temperature baking, the baking temperature is 150℃, the iron powder sludge is spread in the baking system with a thickness of 40-50mm, and the moisture content of the iron powder sludge is 0.32wt% after baking to obtain dry iron powder sludge; S3: The dry iron powder sludge is crushed by a roll crusher, and then the crushed iron powder sludge is screened through a 3 mm square hole screen in a closed environment to obtain undersize material, oversize material and powder A (powder A is the dust generated in the screening process), the oversize material is crushed and screened again until all the material passes through the 3 mm square hole screen; then, in a closed environment, the screened material is dry-magnetic separated by a magnetic separator, the magnetic field strength of the magnetic separator is 1000 GS, and the concentrate and the magnetic separation residue are separated after magnetic separation, the TFe content of the concentrate is 54.57%, and the MFe content is 9.87%; S4: The magnetic separation residue is separated by a powder separator to obtain coarse material and powder B, the TFe content of the coarse material is 10.04%, the powder A and the powder B are collected by a dust removal system through negative pressure to obtain micro powder, the micro powder is collected by 8 dust removal bags, and the TFe content of the micro powder is 9.76wt%; the concentrate accounts for 75.25wt%, the coarse material accounts for 15.24wt%, and the micro powder accounts for 9.51wt%.

[0026] Example 3 The components of the iron powder sludge in this example are shown in Table 5, and the particle size distribution of the iron powder sludge is shown in Table 6.

[0027] Table 5

[0028] Table 6

[0029] A method for recovering iron-containing material from iron powder sludge, the method comprising the following steps: S1: The iron powder sludge is spread on a clean cement floor with a thickness of 60-80 mm, and after spreading, the material is turned over for dehydration at time intervals of 9h20min, 8h55min, 9h30min, 9h25min, 8h40min, 9h45min, 8h50min and 9h30min, respectively, and when turning over, the loader is used to crush the blocks larger than 100 mm, and the moisture content of the iron powder sludge is 7.74% after the last turning over; S2: The dehydrated iron powder sludge is transferred to an oven for constant temperature baking, the baking temperature is 100℃, and the iron powder sludge is spread in the baking system with a thickness of 40-50 mm, and the moisture content of the iron powder sludge is 0.98wt% after baking to obtain dry iron powder sludge; S3: The dry iron powder sludge is crushed by a roll crusher, and then the crushed iron powder sludge is screened through a 1 mm square hole screen in a closed environment to obtain undersize material, oversize material and powder A (powder A is the dust generated in the screening process), the oversize material is crushed and screened again until all the material passes through the 1 mm square hole screen; then, in a closed environment, the screened material is dry-magnetic separated by a magnetic separator, the magnetic field strength of the magnetic separator is 3000 GS, and the concentrate and the magnetic separation residue are separated after magnetic separation, the TFe content of the concentrate is 55.44%, and the MFe content is 7.37%; S4: The magnetic separation residue is separated by a powder separator to obtain coarse material and powder B, the TFe content of the coarse material is 14.84%, and the powder A and the powder B are collected by a dust removal system through negative pressure to obtain micro powder, the micro powder is collected by 8 dust removal bags, and the TFe content of the micro powder is 7.99wt%; the concentrate accounts for 70.00wt%, the coarse material accounts for 18.39wt%, and the micro powder accounts for 11.61wt%.

[0030] Test Example ①The composition of the recovered concentrate in Example 3 is compared with that of the iron concentrate, as shown in Table 7, and the sintering of the mixture of the iron concentrate and the sludge recovered concentrate is as shown in Table 8, and the main technical indexes of the sinter are shown in Table 9.

[0031] Table 7

[0032] Table 8

[0033] Note: The reference concentrate is the iron concentrate, and the compared concentrate is the sludge recovered concentrate.

[0034] Table 9

[0035] As can be seen from Table 9, the total iron content and other components of the prepared sinter change little, and since the particle size of the sludge is finer than that of the iron concentrate, the return rate increases slightly, which is relatively controlled.

[0036] ②The micro powder recovered in Example 3 is applied to prepare C40 concrete (C40 concrete requires 7d compressive strength of 28 MPa and 28d compressive strength of 40 MPa), and the components are shown in Table 10; the performance test results of the prepared concrete are shown in Table 11, from which it can be seen that the key performance indicators of the four groups of samples all meet or exceed the requirements, and the workability is good, and the batch stability is good, which shows that the recovered micro powder can be successfully applied to the production of C40 concrete as a concrete admixture.

[0037] Table 10

[0038] Table 11

[0039] Although the present application has been described in detail with particular reference to certain embodiments thereof, it should be understood that modifications and alterations can be made thereto without departing from the scope and spirit of the application.

Claims

1. A method for the classified recovery of iron-containing material from iron powder sludge, characterized in that The method comprises the following steps: S1: spreading and turning the iron powder sludge for dehydration, until the moisture content of the iron powder sludge is 5-8 wt %; S2: baking the dehydrated iron powder sludge until the moisture content of the iron powder sludge is <1 wt %, to obtain dry iron powder sludge; S3: crushing and screening the dry iron powder sludge to obtain screened material and powder A, and magnetically separating the screened material to obtain concentrate and magnetic separation residual material; the TFe content of the concentrate is ≥50 wt %; S4: separating the magnetic separation residual material by a powder separator to obtain coarse material and powder B, and collecting the powder A and the powder B by a negative pressure method in a closed environment to obtain micro powder; the TFe content of the coarse material is 10-15 wt %; and the TFe content of the micro powder is <10 wt %.

2. The process for beneficiating iron-containing material from iron powder sludge according to claim 1, characterized in that: The composition of the iron powder sludge in step S1 comprises 5-15 wt % MFe, 30-45 wt % TFe, 10-20 wt % H2O, 5-15 wt % SiO2, 10-20 wt % CaO, 5-15 wt % MgO, 1-5 wt % Al2O3, 0-1.0 wt % P, and 0-1.0 wt % S.

3. The process for beneficiating iron-containing material from iron powder sludge according to claim 1, wherein: The particle size distribution of the iron powder sludge in step S1 is that the content of the material above the 40-mesh screen is <5 wt %, the content of the material in the 40-100-mesh screen interval is 10-15 wt %, the content of the material in the 100-150-mesh screen interval is 30-35 wt %, the content of the material in the 150-200-mesh screen interval is 25-30 wt %, and the content of the material below the 200-mesh screen is 20-25 wt %.

4. The process for beneficiating iron-containing material from iron powder sludge of claim 1, wherein: The spreading thickness in step S1 is ≤80 mm, and the turning mode is to turn once every 8-10 h.

5. The process of claim 1, wherein: The baking temperature in step S2 is 100-150 ℃, and the spreading thickness of the iron powder sludge during baking is 30-50 mm.

6. The process for beneficiating iron-containing material from iron powder sludge of claim 1, wherein: The screen mesh size for screening in step S3 is 1-3 mm; and the magnetic field strength for magnetic separation is 1000-3000 GS.

7. An iron-containing material, characterized by: The iron-containing material is obtained by the method for classifying and recovering iron-containing material from iron powder sludge according to any one of claims 1-6; the iron-containing material comprises concentrate with a TFe content of ≥50 wt %, coarse material with a TFe content of 10-15 wt %, and micro powder with a TFe content of <10 wt %.

8. Use of the iron-containing material according to claim 7, characterized in that, The concentrate is applied to prepare sintered ore.

9. Use of the iron-containing material according to claim 7, characterised in that, The coarse material is applied to prepare a desiccant.

10. Use of the iron-containing material according to claim 7, characterized in that, The micro powder is applied to prepare concrete.

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