Dry separation process and system for electric furnace steel slag

Abstract

The invention provides an electric furnace steel slag dry separation process and system, and the process comprises the following steps: magnetic separation iron removal: carrying out screening, crushing and magnetic separation iron removal on steel slag to obtain tailings; the tailings are ground, specifically, the tailings are ground into micron-sized powder; the micron-sized powder is subjected to wind separation, coarse powder and fine powder are obtained, and the cutting particle size of wind separation ranges from 40 micrometers to 50 micrometers; magnetic separation of the coarse powder: carrying out magnetic separation on the coarse powder to obtain fine iron powder and a non-magnetic material, and returning the non-magnetic material for grinding; and fine powder magnetic separation is conducted, specifically, the fine powder is subjected to magnetic separation, and inert minerals and active steel slag micro powder are obtained. According to the method, inert minerals in the steel slag can be recycled, so that the hydration activity and the utilization rate of the tailings are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical solid waste treatment, and in particular to a dry separation process and system for electric furnace steel slag. Background Art

[0002] Steel slag is a solid waste discharged from steelmaking. The current secondary treatment technology of steel slag mainly adopts crushing, screening and magnetic separation processes to recover the metallic iron in the steel slag and return it to the steelmaking and ironmaking process for reuse. Compared with ordinary carbon steel slag from converter, the steel slag from electric furnace smelting special steel has higher hardness and density, and the content of metallic iron and iron oxide in the slag is high. At the same time, other valuable metal elements such as Mn, Cr, V, Ti, Ni, etc. are also present.

[0003] The existing dry secondary treatment process for treating electric furnace slag has high energy consumption and low magnetic separation recovery rate. It can only recover the strongly magnetic metals Fe and Fe3O4, and cannot separate and recover the weakly magnetic metal oxides (inert minerals) such as FeO, Fe2O3, Cr2O3, V2O5, TiO2, etc. in the tailings. Such metal components are stored in large quantities in the tailings, resulting in a waste of resources. In addition, since they do not have hydration activity, it is difficult to use the tailings powder for building materials due to unfavorable reasons such as low activity and excessive heavy metals. Summary of the invention

[0004] In order to realize the recovery of inert minerals in steel slag and improve the hydration activity and utilization rate of tailings, the present invention provides an electric furnace steel slag dry separation process and system.

[0005] In a first aspect, the present invention provides a dry separation process for electric furnace slag, comprising the following steps:

[0006] Magnetic separation and iron removal: After the steel slag is screened, crushed, and magnetically separated to remove iron, tailings are obtained;

[0007] Tailings grinding: grinding the tailings into micron-sized powder;

[0008] Wind sorting: The micron-sized powder is wind sorted to obtain coarse powder and fine powder, wherein the cutting particle size of the wind sorting is 40-50 μm;

[0009] Coarse powder magnetic separation: the coarse powder is subjected to magnetic separation to obtain iron ore concentrate and non-magnetic material, and the non-magnetic material is returned to the powder grinding.

[0010] Fine powder magnetic separation: The fine powder is subjected to magnetic separation to obtain inert minerals and active steel slag powder.

[0011] Optionally, the fine powder magnetic separation further comprises: using wind force to disperse the fine powder before performing magnetic separation.

[0012] Optionally, the magnetic separation intensity of the coarse powder magnetic separation is 150-200 mT, and the magnetic separation intensity of the fine powder magnetic separation is 800-1200 mT.

[0013] Optionally, the magnetic separation and iron removal specifically includes: subjecting the steel slag to three-time screening, two-stage crushing, and magnetic separation and iron removal to obtain tailings.

[0014] Optionally, the steel slag is subjected to three-stage screening, two-stage crushing, and magnetic separation to remove iron to obtain tailings, comprising:

[0015] The steel slag is subjected to primary screening to obtain primary coarse material on the screen and primary fine material under the screen, the primary coarse material on the screen is subjected to primary crushing and secondary screening in sequence to obtain secondary coarse material on the screen and secondary fine material under the screen, the secondary coarse material on the screen is subjected to magnetic separation, and the secondary coarse material on the screen after magnetic separation is returned to the primary crushing;

[0016] The first-stage undersize fine material and the second-stage undersize fine material are subjected to magnetic separation to obtain a first magnetic material and a first non-magnetic material;

[0017] The first magnetic material is subjected to secondary crushing and tertiary screening to obtain tertiary coarse material on the sieve and tertiary fine material under the sieve, the tertiary coarse material on the sieve is subjected to magnetic separation, and the tertiary coarse material on the sieve after magnetic separation is returned to be subjected to secondary crushing;

[0018] The fine material under the third-stage sieve is subjected to magnetic separation to obtain a second non-magnetic material, and the first non-magnetic material and the second non-magnetic material are ground as tailings.

[0019] Optionally, both the primary crushing and the secondary crushing adopt rod mill process.

[0020] Optionally, the sieve apertures of the primary sieve and the secondary sieve are 10-20 mm.

[0021] Optionally, the sieve aperture of the three-stage sieve is 5-10 mm.

[0022] Optionally, the magnetic separation intensity of the secondary coarse material on the sieve and the tertiary coarse material on the sieve is 70-150 mT, and the magnetic separation intensity of the primary undersize fine material, the secondary undersize fine material and the tertiary undersize fine material is 150-200 mT.

[0023] In a second aspect, the present invention further provides an electric furnace steel slag dry separation system, the system is used to implement the above-mentioned electric furnace steel slag dry separation process, the electric furnace steel slag dry separation system comprises a magnetic separation and iron removal equipment, a grinding mill, a powder separator, a three-stage magnetic separator, a four-stage magnetic separator and a circulating fan;

[0024] The grinding mill is arranged at the outlet of the magnetic separation and iron removal equipment, the discharge port of the grinding mill is communicated with the feed port of the powder separator, and the coarse material outlet of the powder separator is communicated with the three-stage magnetic separator;

[0025] The circulating fan, the powder separator and the four-stage magnetic separator are connected in sequence.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention uses crushing, screening, and magnetic separation processes to recover strongly magnetic metallic iron and iron oxides in steel slag. After obtaining tailings, the tailings are further ground into micron-sized powders for sorting. In the wind sorting process, the present invention further sets the wind cutting particle size to 40-50 μm, concentrates weakly magnetic metal oxides (inert minerals) in fine powders, and then selects the inert minerals in the fine powders through a magnetic separation process, and the remainder is the steel slag active micro-powder product. Thereby, the recovery of inert minerals in tailings is achieved, the waste of this part of mineral resources is reduced, and the hydration activity and utilization rate of tailings are improved. Compared with the conventional method of concentrating inert minerals in coarse powders, the present invention enriches inert minerals in fine powders, and the fine powders are further magnetically separated to obtain higher-grade active steel slag micro-powders and inert minerals, without the need for re-grinding, thereby reducing the energy consumption of grinding. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of dry separation of electric furnace slag according to an embodiment of the present invention.

[0029] Explanation of the reference numerals: 1. primary screening machine; 2. primary rod mill; 3. secondary screening machine; 4. primary electromagnetic iron remover; 5. primary magnetic separator; 6. secondary rod mill; 7. tertiary screening machine; 8. secondary electromagnetic iron remover; 9. secondary magnetic separator; 10. grinding mill; 11. powder separator; 12. tertiary magnetic separator; 13. quaternary magnetic separator; 14. dust collector; 15. circulating fan; a. coarse material on the primary sieve; b. fine material under the primary sieve; c. coarse material on the secondary sieve; d. fine material under the secondary sieve; e. first magnetic material; f. first non-magnetic material; g. coarse material on the tertiary sieve; h. fine material under the tertiary sieve; i. second non-magnetic material; j. micron-sized powder; k. coarse powder; m. fine powder; n. lump steel; o. granular steel; p. iron concentrate; q. inert minerals; r. active steel slag powder. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be interpreted as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0031] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application;

[0032] The term "including" and its variations used in this article are open inclusions, that is, "including but not limited to"; the term "based on" is "based at least in part on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, the meaning of "multiple" is two or more.

[0033] Steel slag contains more than 30% hydrated inert minerals, which are difficult to utilize due to their low hydration activity. The inert minerals in steel slag powder refer to weakly magnetic metal oxides in steel slag, which are mainly complete solid solutions composed of MgO, FeO, MnO and f-CaO. Weakly magnetic metal oxides are minerals with high density and hardness in steel slag, and their particle size is generally 30-50μm. At present, the conventional technology for separating weakly magnetic metal oxides is to enrich them in the heavy fraction by using the characteristics of weakly magnetic metal oxides in the coarse particle size and then separate them by magnetic separation. However, on the one hand, since the particle size of weakly magnetic metal oxides is at the micron level, in order to enrich weakly magnetic metal oxides in the coarse powder, the fineness of steel slag grinding needs to be increased, which makes the power consumption of the grinding process too high. On the other hand, since the heavy fraction contains weakly magnetic metal oxides with a particle size between 30-50μm, there will be other components with larger particle sizes. Therefore, in order to recover higher-grade weakly magnetic metal oxides, the heavy fraction must be processed secondary. During secondary processing, some related technologies use wet gravity separation or wet magnetic separation to recover weakly magnetic metal oxides in the heavy components of steel slag. However, this process will cause the gelling activity of the remaining tailings after magnetic separation to be lost, and it consumes a lot of water. The discharged wastewater contains a lot of alkaline substances and heavy metal elements, causing environmental pollution, and is not suitable for water-scarce areas and severe winter weather in the north.

[0034] Based on the above problems, the embodiments of the present invention provide a dry separation process and system for electric furnace steel slag, which is suitable for steel slag after heat treatment, and the overall particle size of the steel slag is less than 150mm. Figure 1 As shown, the electric furnace slag dry separation process of the present invention comprises the following steps:

[0035] S1: Magnetic separation and iron removal: The steel slag is screened, crushed and magnetically separated to remove iron to obtain tailings.

[0036] Optionally, in this step, the steel slag is subjected to two-stage crushing and magnetic separation to remove iron, thereby obtaining tailings. Specifically, the two-stage crushing and magnetic separation to remove iron may include the following steps:

[0037] S101: The steel slag is subjected to primary screening to obtain primary coarse material a on the screen and primary fine material b under the screen. The primary coarse material a is subjected to primary crushing and secondary screening in sequence to obtain secondary coarse material c on the screen and secondary fine material d under the screen. The secondary coarse material c is subjected to magnetic separation to select lump steel n, and the secondary coarse material c is returned to the primary crushing.

[0038] The primary crushing adopts the rod mill process to crush most of the coarse material a on the primary screen to less than 10mm. The screening apertures of the primary and secondary screening are both 10-20mm. The magnetic separation intensity of the coarse material c on the secondary screen is 70-150mT, and an electromagnetic iron remover can be used for magnetic separation.

[0039] S102: Magnetic separation is performed on the first-stage undersize fine material b and the second-stage undersize fine material d to obtain a first magnetic material e and a first non-magnetic material f. The magnetic separation intensity of the first-stage undersize fine material b and the second-stage undersize fine material d is 150-200 mT, and a double-roll magnetic separator can be used for magnetic separation.

[0040] S103: The first magnetic material e is subjected to secondary crushing and tertiary screening in sequence to obtain tertiary screen coarse material g and tertiary screen fine material h. The tertiary screen coarse material g is subjected to magnetic separation to select particle steel o, and then the tertiary screen coarse material g is returned for secondary crushing.

[0041] Among them, the secondary crushing also adopts the rod mill process, and the sieve aperture of the tertiary screening is 5-10mm. The magnetic separation intensity of the coarse material g on the tertiary screen is also 70-150mT, and the electromagnetic iron remover can also be used for magnetic separation.

[0042] S104: The fine material h under the third-level sieve is subjected to magnetic separation to select the iron concentrate p to obtain the second non-magnetic material i, and the first non-magnetic material f and the second non-magnetic material i are ground as tailings. The magnetic separation intensity of the fine material h under the third-level sieve is 150-200 mT, and a double-roll magnetic separator can also be used for magnetic separation.

[0043] S2: grinding tailings: grinding tailings into micron-sized powder j. Specifically, the tailings are derived from the first non-magnetic material f in the above step S102 and the second non-magnetic material i in step S104. It should be noted that the size of the micron-sized powder j is less than 1 mm, specifically distributed in the range of 0-10, 10-100, 100-1000 μm. The tailings grinding equipment can be selected from equipment such as a horizontal roller mill, a roller press or a ball mill, preferably a horizontal roller mill.

[0044] S3: Wind sorting: The micron-sized powder j is wind sorted to obtain coarse powder k and fine powder m, wherein the cutting particle size of the wind sorting is 40-50 μm.

[0045] S4: Coarse powder magnetic separation: The coarse powder k is subjected to magnetic separation to obtain iron ore concentrate p and non-magnetic materials. The non-magnetic materials obtained by magnetic separation are returned to the grinding mill. Among them, most of the coarse powder k has a particle size of more than 50μm, and the magnetic separation intensity of the coarse powder k is 150-200mT. Specifically, a single-roll magnetic separator can be used for magnetic separation.

[0046] S5: Fine powder magnetic separation: The fine powder m is subjected to magnetic separation to obtain magnetic inert minerals q and non-magnetic active steel slag powder r. Most of the fine powder m has a particle size below 40μm, and the magnetic separation intensity of the fine powder m is 800-1200mT. Specifically, a dry high-gradient magnetic separator can be used for magnetic separation. In the actual magnetic separation process, the fine powder m can be blown away by wind before magnetic separation. Dispersing the fine powder m by wind is conducive to suppressing the agglomeration of magnetic and non-magnetic materials and improving the magnetic separation effect.

[0047] The present invention adopts crushing, screening and magnetic separation process to recover the strong magnetic metal iron and iron oxide in the steel slag, and after obtaining the tailings, the tailings are further ground into micron-sized powder j. According to the mineral phase analysis, the average particle size of the weak magnetic metal oxides formed by metals such as Mn, Cr, V, and Ti in the steel slag is 40-50 μm. The present invention sets the wind cutting particle size to 40-50 μm to concentrate the weak magnetic metal oxides in the fine powder m, and then selects the weak magnetic metal oxides (inert minerals q) in the fine powder m through a strong magnetic separation process, and the remainder is the active micro powder product of the steel slag. Thereby, the recovery of valuable metals in the tailings is achieved, the waste of this part of mineral resources is reduced, and the hydration activity and utilization rate of the tailings are improved. Compared with the conventional method of concentrating the weak magnetic metal oxides in the coarse powder k, the present invention enriches the weak magnetic metal oxides in the fine powder, so that the fineness requirement of the tailings grinding is relatively low, and the energy consumption of the grinding is reduced. The fine powder m in the present invention can further be used to select weakly magnetic metal oxides through magnetic separation to obtain high-grade active steel slag powder r, without the need for re-grinding, which simplifies the grinding process. In addition, the present invention adopts dry grinding and magnetic separation throughout the process, so that the steel slag powder after magnetic separation can maintain a high adhesive activity. The dry process is more environmentally friendly and suitable for water-scarce areas.

[0048] In the actual wind separation process, the coarse powder k mainly contains larger iron particles, iron concentrate p, undissociated weak magnetic metal oxides, etc. After the coarse powder k is subjected to ordinary magnetic separation to select iron particles and iron concentrate p with strong magnetism and difficult to grind, the undissociated weak magnetic metal oxides are returned to the tailings grinding for recycling grinding again until they are dissociated and the particle size becomes smaller, and then enter the fine powder through the next wind separation. After the magnetic material in the coarse powder k is recovered, the present invention gradually concentrates a small part of the undissociated weak magnetic metal oxides in the coarse powder k in the fine powder m for recycling by recycling the coarse powder k, which is beneficial to improve the recovery rate of valuable metals in steel slag and avoid waste of metal element resources.

[0049] In addition, the magnetic separation intensity of the coarse powder k is 150-200mT, and the magnetic separation intensity of the fine powder m is 800-1200mT. Since the main components of the coarse powder are strong magnetic substances such as iron particles and iron concentrate p, and the main components of the fine powder are solid solution minerals formed by weak magnetic metals or metal oxides, the present invention adopts weak magnetic and strong magnetic separation equipment in different processes according to the magnetic properties of metal minerals in steel slag, and the strong magnetic metal adopts weak magnetic separation to ensure the grade of the recovered metal; the weak magnetic metal and its oxide adopt strong magnetic separation, which can improve the separation efficiency and ensure the magnetic separation effect.

[0050] In the traditional slag crushing and iron selection process, jaw crushers, cone crushers and other equipment are generally used for the rough crushing of large pieces of slag to save energy. However, when this process is used to crush the steel slag and then perform magnetic separation, the surface of the selected large pieces of slag steel has many impurities, and the slag steel product quality is poor, only about 70%. The present invention adopts the rod grinding process instead of the jaw crusher for the rough crushing of the steel slag, and cancels the iron selection process before the rough crushing, so as to avoid the large pieces of slag steel selected at this time with a large amount of impurities on the surface, realize the separation of slag and iron, and improve the grade of slag steel. The grade of the selected slag steel can reach more than 90%, which can be directly used for steelmaking.

[0051] Furthermore, the present invention adopts a two-stage rod mill process for crushing, wherein the first-stage rod mill is used for crushing large-size steel slag, and the second-stage rod mill is used for removing impurities and purifying magnetic materials. Vibrating screens are respectively set before and after the rod mill for particle size screening, so that fine materials can directly enter the subsequent process, and only part of the large pieces of steel slag after screening enters the rod mill process, reducing the feed amount of the rod mill equipment, thereby reducing the equipment specifications and effectively reducing energy consumption.

[0052] Second, refer to Figure 1As shown, an embodiment of the present invention also provides an electric furnace steel slag dry sorting system, which is used to implement the above-mentioned electric furnace steel slag dry sorting process. Specifically, the electric furnace steel slag dry sorting system of the present invention includes a magnetic separation and iron removal device, which is used to screen, crush, and magnetically separate the steel slag to obtain tailings. Specifically, the magnetic separation and iron removal equipment includes a first-level screening machine 1, a first-level rod mill 2, a second-level screening machine 3, a first-level electromagnetic iron remover 4, a first-level magnetic separator 5, a second-level rod mill 6, a third-level screening machine 7, a second-level electromagnetic iron remover 8 and a second-level magnetic separator 9. Among them, the coarse material outlet of the first-level screening machine 1 is connected to the inlet of the first-level rod mill 2, and the outlet of the first-level rod mill 2 is connected to the inlet of the second-level screening machine 3. The coarse material outlet of the second-level screening machine 3 is connected to the inlet of the first-level electromagnetic iron remover 4, and the non-magnetic material outlet of the first-level electromagnetic iron remover 4 is connected to the inlet of the first-level rod mill 2. The fine material outlet of the primary screening machine 1 and the fine material outlet of the secondary screening machine 3 are both connected to the inlet of the primary magnetic separator 5. The magnetic material outlet of the primary magnetic separator 5 is connected to the inlet of the secondary rod mill 6, and the outlet of the secondary rod mill 6 is connected to the inlet of the tertiary screening machine 7. The coarse material outlet of the tertiary screening machine 7 is connected to the inlet of the secondary electromagnetic iron remover 8, the fine material outlet of the tertiary screening machine 7 is connected to the inlet of the secondary magnetic separator 9, and the non-magnetic material outlet of the secondary electromagnetic iron remover 8 is connected to the inlet of the secondary rod mill 6.

[0053] The electric furnace slag dry separation system also includes a grinding mill 10, a powder separator 11, a circulating fan 15, a dust collector 14, a three-stage magnetic separator 12 and a four-stage magnetic separator 13. The non-magnetic material outlets of the first-stage magnetic separator 5 and the second-stage magnetic separator 9 are connected to the feed port of the grinding mill 10. The discharge port of the grinding mill 10 is connected to the feed port of the powder separator 11, and the circulating fan 15 and the air inlet of the powder separator 11 are connected in sequence. The air outlet of the powder separator 11 is connected to the inlet of the four-stage magnetic separator 13, and the outlet of the four-stage magnetic separator 13 is connected to the inlet of the dust collector 14, and the air outlet of the dust collector 14 is connected to the air inlet of the circulating fan 15. The coarse material outlet of the powder separator 11 is connected to the feed port of the three-stage magnetic separator 12, and the non-magnetic discharge port of the three-stage magnetic separator 12 is connected to the feed port of the grinding mill 10. The grinding mill 10 is used to grind the tailings into micron-sized powder j, the powder separator 11 is used to perform wind separation on the micron-sized powder j to obtain coarse powder k and fine powder m, the three-stage magnetic separator 12 is used to perform magnetic separation on the coarse powder k, and the four-stage magnetic separator 13 is used to perform magnetic separation on the fine powder m. The wind circulation path is the circulating fan 15, the powder separator 11, the four-stage magnetic separator 13 and the dust collector 14. After the supplementary air intake, the circulating wind enters the powder separator 11, the four-stage magnetic separator 13 and the dust collector 14 in sequence. The fine powder m is taken out to the four-stage magnetic separator 13 under the action of the wind, and the active steel slag powder r is obtained after magnetic separation and dust removal.

[0054] The present invention is described in detail below through specific embodiments:

[0055] This embodiment specifically adopts the following steps to dry-separate electric furnace slag:

[0056] After the steel slag is subjected to conventional hot stewing treatment, it is subjected to primary screening at a screening aperture of 15 mm, and the coarse material a on the primary screen enters the primary rod mill 2, and the rotation speed of the primary rod mill 2 is adjusted to 19 rpm. The rod-milled material is subjected to secondary screening at a screening aperture of 15 mm, and the coarse material c on the secondary screen enters the primary electromagnetic iron remover 4 for magnetic separation, and the magnetic separation intensity is adjusted to 100 mT. After the lump steel n is selected, the coarse material c on the secondary screen continues to return to the primary rod mill 2 for crushing.

[0057] The first-stage undersize fine material b and the second-stage undersize fine material d are sent to the first-stage magnetic separator 5 for magnetic separation to obtain the first magnetic material e and the first non-magnetic material f. The first-stage magnetic separator 5 uses a double-roller magnetic separator, and the magnetic separation intensity is adjusted to 170mT. The first magnetic material e is sent to the second-stage rod mill 6, and the rotation speed of the second-stage rod mill 6 is adjusted to 21 rpm. The material after the rod mill is subjected to three-stage screening at a screening aperture of 5mm, and the coarse material g on the third-stage screen is magnetically separated by the second-stage electromagnetic iron remover 8 at a magnetic field strength of 120mT. After the particle steel o is selected, the coarse material g on the third-stage screen continues to return to the second-stage rod mill 6 for crushing. The third-stage undersize fine material h is magnetically separated by the second-stage magnetic separator 9 at a magnetic field strength of 200mT to obtain the second magnetic material and the second non-magnetic material i, and the second magnetic material is the iron concentrate p.

[0058] The first non-magnetic material f and the second non-magnetic material i are used as tailings and ground by a horizontal roller mill. The micron-sized powder j obtained after grinding is further sent to a powder selector 11 for powder selection. The cutting particle size of the powder selector 11 is set to 45 μm. The selected fine powder m has a specific surface area of ​​450 m 2 / kg or more. The selected coarse powder k is subjected to magnetic separation at a magnetic field strength of 200mT to select iron concentrate p, and the fine powder m is subjected to magnetic separation at a magnetic field strength of 1000mT to select weak magnetic metal oxide phases. The non-magnetic material enters the dust collector 14 for dust removal to obtain active steel slag powder r.

[0059] After inspection, in this embodiment, the total iron grade of lump steel n and particle steel o is 93.6% and 90.4% respectively, the total iron grade of iron concentrate p is 56.2%, and the iron grade in the weak magnetic metal oxide phase is 40.3%. Compared with the grade of magnetic separation products specified in the standard (GB / T30897~30899-2014), it is increased by 5-10%. The proportion of inert minerals in active steel slag micropowder r is 9.2%. The proportion of inert minerals in active steel slag micropowder r is reduced from 20% to less than 10%, which improves the gelling activity index of steel slag micropowder.

[0060] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A dry separation process for electric furnace slag, characterized in that: The steps include: Magnetic separation and iron removal: After the steel slag is screened, crushed, and magnetically separated to remove iron, tailings are obtained; Grinding the tailings: Grinding the tailings into micron-sized powder (j); Wind sorting: The micron-sized powder (j) is subjected to wind sorting to obtain coarse powder (k) and fine powder (m), wherein the cutting particle size of the wind sorting is 40-50 μm; Coarse powder magnetic separation: the coarse powder (k) is subjected to magnetic separation to obtain iron ore concentrate (p) and non-magnetic material, and the non-magnetic material is returned to the grinding mill; Fine powder magnetic separation: The fine powder (m) is subjected to magnetic separation to obtain inert minerals (q) and active steel slag powder (r).

2. The dry separation process of electric furnace slag according to claim 1, characterized in that: The fine powder magnetic separation also includes: using wind power to blow the fine powder (m) away and then performing magnetic separation.

3. The dry separation process of electric furnace slag according to claim 1, characterized in that: The magnetic separation intensity of the coarse powder magnetic separation is 150-200 mT, and the magnetic separation intensity of the fine powder magnetic separation is 800-1200 mT.

4. The dry separation process of electric furnace slag according to claim 1, characterized in that: The magnetic separation and iron removal specifically comprises: subjecting the steel slag to three-time screening, two-stage crushing, and magnetic separation and iron removal to obtain tailings.

5. The dry separation process of electric furnace slag according to claim 4, characterized in that: The steel slag is subjected to three-stage screening, two-stage crushing, and magnetic separation to remove iron to obtain tailings, including: The steel slag is subjected to primary screening to obtain primary coarse material (a) on the screen and primary fine material (b) under the screen, the primary coarse material (a) on the screen is subjected to primary crushing and secondary screening in sequence to obtain secondary coarse material (c) on the screen and secondary fine material (d) under the screen, the secondary coarse material (c) on the screen is subjected to magnetic separation, and the secondary coarse material (c) on the screen after magnetic separation is returned to the primary crushing; The first-stage undersize fine material (b) and the second-stage undersize fine material (d) are subjected to magnetic separation to obtain a first magnetic material (e) and a first non-magnetic material (f); The first magnetic material (e) is subjected to secondary crushing and tertiary screening to obtain tertiary coarse material (g) on ​​the sieve and tertiary fine material (h) under the sieve, the tertiary coarse material (g) on ​​the sieve is subjected to magnetic separation, and the tertiary coarse material (g) on ​​the sieve after magnetic separation is returned to be subjected to secondary crushing; The third-stage undersize fine material (h) is subjected to magnetic separation to obtain a second non-magnetic material (i), and the first non-magnetic material (f) and the second non-magnetic material (i) are ground as tailings.

6. The dry separation process of electric furnace slag according to claim 5, characterized in that: The primary crushing and the secondary crushing both adopt rod mill technology.

7. The dry separation process of electric furnace slag according to claim 5, characterized in that: The sieve apertures of the primary sieve and the secondary sieve are 10-20 mm.

8. The dry separation process of electric furnace slag according to claim 5, characterized in that: The screening aperture of the three-stage screening is 5-10 mm.

9. The dry separation process of electric furnace slag according to claim 5, characterized in that: The magnetic separation intensity of the secondary coarse material (c) and the tertiary coarse material (g) is 70-150 mT, and the magnetic separation intensity of the primary undersize fine material (b), the secondary undersize fine material (d) and the tertiary undersize fine material (h) is 150-200 mT.

10. An electric furnace slag dry separation system, characterized in that: The system is used to implement the electric furnace steel slag dry separation process as described in any one of claims 1 to 9, and the electric furnace steel slag dry separation system comprises a magnetic separation and iron removal device, a grinding mill (10), a powder separator (11), a three-stage magnetic separator (12), a four-stage magnetic separator (13) and a circulating fan (15); The grinding mill (10) is arranged at the outlet of the magnetic separation and iron removal equipment, the discharge port of the grinding mill (10) is connected to the feed port of the powder separator (11), and the coarse material outlet of the powder separator (11) is connected to the three-stage magnetic separator (12); The circulating fan (15), the powder separator (11) and the four-stage magnetic separator (13) are connected in sequence.

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