A method for recycling coarse-grained elemental iron particles

Abstract

The present invention provides a method for recycling coarse-grained elemental iron particles. The method for recycling coarse-grained elemental iron particles of the present invention comprises the following steps: S1: feeding the coarse-grained elemental iron particles into a first ball mill for grinding, and sieving after grinding to obtain an oversize portion and an undersize portion; S2: returning the oversize portion to the first ball mill for cyclic grinding, feeding the undersize portion into a second ball mill for fine grinding, and washing and drying after fine grinding to obtain iron powder. The method for recycling coarse-grained elemental iron particles of the present invention can reasonably recycle coarse-grained elemental iron particles, and the recycling rate of coarse-grained elemental iron particles is high.

Description

Technical Field

[0001] The invention relates to the technical field of waste resource utilization, and in particular to a method for recycling coarse-grained elemental iron particles. Background Art

[0002] According to the content of metallic iron and particle size, iron-containing materials have formed a large number of product series, and most of the iron-containing materials have been well utilized. However, iron-containing materials with a metallic iron content of about 90% and a particle size of 40 mesh to 10 mm have not been well utilized, especially fine-particle iron-containing materials in the range of 40 mesh to 2 mm.

[0003] At present, the material feeding into a small blast furnace or cupola is required to be ≥10mm. The material with an iron content of 90% will produce 86-88% molten iron through smelting; however, the fine-grained material with a particle size ranging from 40 mesh to 2mm is relatively fine, and is directly burned by the hot air flow during the feeding process. After smelting, only 75-78% molten iron can be produced, and the remaining metallic iron is oxidized and burned into the dust, resulting in waste and loss of metallic iron.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recycling coarse-grained elemental iron particles, which can reasonably recycle the coarse-grained elemental iron particles and has a high recycling rate of the coarse-grained elemental iron particles.

[0006] The present invention provides a method for recycling coarse-grained elemental iron particles, comprising the following steps:

[0007] S1: feeding the coarse-grained elemental iron particles into the first ball mill (i.e., the large ball mill) for grinding, and sieving after grinding to obtain an oversize fraction and an undersize fraction;

[0008] S2: The part above the sieve is returned to the first ball mill for cyclic grinding, and the part below the sieve is sent to the second ball mill (i.e., a small ball mill) for fine grinding. After fine grinding, it is washed, selected, and dried to obtain iron powder.

[0009] In step S1, the coarse-grained elemental iron particles have a metallic iron content of 90-92%, a particle size of 40 mesh to 2 mm, and a moisture content of <1.0%.

[0010] In step S1, the diameter of the first ball mill is 1500-2100 mm and the length is 3000-5700 mm. There is no strict restriction on the specifications of the first ball mill, for example, Etc. In addition, the first ball mill uses large steel balls with a diameter of 110-130 mm and a ball filling rate of 80-85%.

[0011] In step S1, the moisture content of the coarse-grained elemental iron particles is controlled to be 20-30%, preferably 22-28%; this moisture content can facilitate the coarse-grained elemental iron particles to enter the first ball mill smoothly, and the moisture content should not be too high, otherwise it will cause the coarse-grained elemental iron particles to flow quickly to the tail end in the first ball mill, resulting in insufficient grinding time and failure to achieve the crushing effect.

[0012] In step S1, a chute can be used to control the feeding rate of the coarse-grained elemental iron particles; specifically, the feeding rate of the coarse-grained elemental iron particles is 1-6 tons / hour, preferably 1.8-5.7 tons / hour, and the feeding rate is 30-50% of the normal feeding rate of the first ball mill; in addition, the rotation speed of the first ball mill is 22-27 rpm, preferably 25-27 rpm. Properly increasing the rotation speed of the first ball mill is conducive to allowing the large steel balls in the first ball mill to fall naturally before rising to the critical point, and then utilizing the falling process to smash and crush the coarse-grained elemental iron particles, so that the coarse-grained elemental iron particles are crushed to the particle size required for the iron powder product.

[0013] In step S1, screening includes: using a 36-40 mesh square hole screen for screening.

[0014] In step S2, the feeding rate of the oversize portion is controlled to be 1.2-5.5 tons / hour, preferably 1.2-3.6 tons / hour; when the oversize portion is returned to the first ball mill for cyclic grinding, the feeding rate of the oversize portion can be reduced to ensure that the oversize portion has sufficient grinding time in the first ball mill, thereby ensuring the grinding effect.

[0015] In step S2, the diameter of the second ball mill is 900-1200 mm and the length is 1800-3000 mm. There is no strict restriction on the specifications of the second ball mill, for example, In addition, the ball milling media used in the second ball mill are small steel balls with a diameter of 50-70 mm, and the ball filling amount is 95-100%, and further 95-98%.

[0016] In step S2, the feeding rate of the under-sieve part is controlled to be 0.7-2.5 tons / hour, and the rotation speed of the second ball mill is 22-28 rpm, preferably 26-28 rpm; the rotation speed of the second ball mill is appropriately reduced so that the small steel balls in the second ball mill are leaked in a peristaltic state, and the small steel balls rub against each other during the falling process to dissociate the surface layer of the material, and the oxide layer is finely ground and peeled off.

[0017] In step S2, washing equipment is used to perform washing to remove impurities; in addition, the drying temperature is 75-110° C. and the drying time is 45-100 minutes.

[0018] In step S2, the iron powder has a metallic iron content of 88-92%, a proportion of the portion below the 40-mesh sieve>95%, and a moisture content<1.0%.

[0019] The method for recycling coarse-grained elemental iron particles of the present invention first utilizes a first ball mill to crush the coarse-grained elemental iron particles, and then utilizes a second ball mill to finely grind and peel off the oxide layer, thereby crushing the elemental iron particles to the particle size required for iron powder. This method can reasonably recycle the coarse-grained elemental iron particles, and the recycling rate of the coarse-grained elemental iron particles is high. DETAILED DESCRIPTION

[0020] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form also includes the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this description, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] The coarse-grained elemental iron particles of this embodiment have a metallic iron content of 90.76%, a particle size between 40 mesh and 2 mm, and a moisture content of 0.18%. The recycling method of the coarse-grained elemental iron particles is as follows:

[0025] 1) Add a proper amount of water to the coarse-grained elemental iron particles so that the moisture content of the coarse-grained elemental iron particles is 27.62%.

[0026] 2) Then, the coarse-grained elemental iron particles were fed into the The grinding is carried out in the first ball mill of the specification, and the ball milling medium in the first ball mill is The large steel balls have a ball loading of 80% and a rotation speed of the first ball mill of 25.31 rpm. After grinding, the product is sieved through a 36-mesh square hole sieve to obtain an oversize portion and an undersize portion.

[0027] 3) The part above the sieve is fed into the first ball mill at a feeding rate of 3.52 tons / hour for cyclic grinding; the part below the sieve is fed into Fine grinding is carried out in the second ball mill of the specification, and the ball milling medium in the second ball mill is The small steel balls have a ball loading of 95% and a second ball mill with a rotation speed of 26.71 rpm. After fine grinding, the impurities are removed by washing and then dried at 85-90° C. for 55-60 minutes to obtain iron powder.

[0028] After testing, the metallic iron content of the iron powder was 89.76%, the proportion of the part under the 40-mesh sieve was 96.02%, and the moisture content was 0.16%.

[0029] Example 2

[0030] The coarse-grained elemental iron particles of this embodiment have a metallic iron content of 91.51%, a particle size between 40 mesh and 2 mm, and a moisture content of 0.15%. The recycling method of the coarse-grained elemental iron particles is as follows:

[0031] 1) Add a proper amount of water to the coarse-grained elemental iron particles so that the moisture content of the coarse-grained elemental iron particles is 22.51%.

[0032] 2) Then, the coarse-grained elemental iron particles were fed into the The grinding is carried out in the first ball mill of the specification, and the ball milling medium in the first ball mill is The large steel balls have a ball loading of 85% and a rotation speed of the first ball mill of 25.81 / min. After grinding, the product is sieved through a 36-mesh square hole sieve to obtain an oversize portion and an undersize portion.

[0033] 3) The part above the sieve is fed into the first ball mill at a feeding rate of 3.09 tons / hour for cyclic grinding; the part below the sieve is fed into Fine grinding is carried out in the second ball mill of the specification, and the ball milling medium in the second ball mill is The small steel balls have a ball loading of 98% and a second ball mill with a rotation speed of 26.42 rpm. After fine grinding, the impurities are removed by washing and then dried at 75-80°C for 65-70 minutes to obtain iron powder.

[0034] After testing, the metallic iron content of the iron powder was 91.11%, the proportion of the part under the 40-mesh sieve was 95.83%, and the moisture content was 0.12%.

[0035] Example 3

[0036] The coarse-grained elemental iron particles of this embodiment have a metallic iron content of 90.24%, a particle size between 40 mesh and 2 mm, and a moisture content of 0.16%. The recycling method of the coarse-grained elemental iron particles is as follows:

[0037] 1) Add a proper amount of water to the coarse-grained elemental iron particles so that the moisture content of the coarse-grained elemental iron particles is 25.31%.

[0038] 2) Then, the coarse-grained elemental iron particles were fed into the The grinding is carried out in the first ball mill of the specification, and the ball milling medium in the first ball mill is The large steel balls have a ball loading of 80% and a rotation speed of the first ball mill of 26.92 rpm. After grinding, the product is sieved through a 40-mesh square hole sieve to obtain an oversize portion and an undersize portion.

[0039] 3) The part above the sieve is fed into the first ball mill at a feeding rate of 1.21 tons / hour for cyclic grinding; the part below the sieve is fed into Fine grinding is carried out in the second ball mill of the specification, and the ball milling medium in the second ball mill is The small steel balls have a ball loading of 96% and a second ball mill with a rotation speed of 27.21 rpm. After fine grinding, the impurities are removed by washing and then dried at 80-85°C for 45-50 minutes to obtain iron powder.

[0040] After testing, the metallic iron content of the iron powder was 88.91%, the proportion of the part under the 40-mesh sieve was 99.83%, and the moisture content was 0.12%.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recycling coarse-grained elemental iron particles, characterized in that: The steps include: S1: feeding the coarse-grained elemental iron particles into the first ball mill for grinding, and sieving them after grinding to obtain an oversize fraction and an undersize fraction; S2: returning the part above the sieve to the first ball mill for cyclic grinding, and sending the part below the sieve to the second ball mill for fine grinding, washing and drying after fine grinding to obtain iron powder; In step S1, the metallic iron content of the coarse-grained elemental iron particles is 90-92%, the particle size is 40 mesh to 2 mm, and the moisture content is <1.0%; an appropriate amount of water is added to the coarse-grained elemental iron particles to control the moisture content of the coarse-grained elemental iron particles to 20-30%, the feeding rate of the coarse-grained elemental iron particles is 1-6 tons / hour, the diameter of the first ball mill is 1500-2100 mm, the length is 3000-5700 mm, the ball milling medium is a large steel ball with a diameter of 110-130 mm, the ball loading is 80-85%, and the rotation speed of the first ball mill is 22-27 rpm; In step S2, the feeding rate of the undersize part is controlled to be 0.7-2.5 tons / hour, the diameter of the second ball mill is 900-1200 mm, the length is 1800-3000 mm, the ball milling medium is small steel balls with a diameter of 50-70 mm, the ball loading is 95-100%, and the rotation speed of the second ball mill is 22-28 rpm.

2. The method for recycling coarse-grained elemental iron particles according to claim 1, characterized in that: In step S1, screening includes: using a 36-40 mesh square hole screen for screening.

3. The method for recycling coarse-grained elemental iron particles according to claim 1, characterized in that: In step S2, the feeding rate of the above-screen portion is controlled to be 1.3-5.5 tons / hour.

4. The method for recycling coarse-grained elemental iron particles according to claim 1, characterized in that: In step S2, the drying temperature is 75-110° C., and the drying time is 45-100 minutes.

5. The method for recycling coarse-grained elemental iron particles according to claim 1, characterized in that: In step S2, the metallic iron content of the iron powder is 88-92%, the proportion of the part under the 40-mesh sieve is >95%, and the moisture content is <1.0%.