CA2418020C - Steel slag processing jig system - Google Patents
Steel slag processing jig system Download PDFInfo
- Publication number
- CA2418020C CA2418020C CA 2418020 CA2418020A CA2418020C CA 2418020 C CA2418020 C CA 2418020C CA 2418020 CA2418020 CA 2418020 CA 2418020 A CA2418020 A CA 2418020A CA 2418020 C CA2418020 C CA 2418020C
- Authority
- CA
- Canada
- Prior art keywords
- fraction
- slag
- middlings
- metal
- aggregate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/04—General arrangement of separating plant, e.g. flow sheets specially adapted for furnace residues, smeltings, or foundry slags
Landscapes
- Manufacture And Refinement Of Metals (AREA)
- Furnace Details (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The present invention relates to a method for separating steel slag into a metal concentrate fraction and an aggregate fraction by (i) crushing the slag and screening to recover slag having a diameter of less than about 20 mm and (ii) further separating the recovered slag in a first fraction of more than about 2 mm and a second fraction of less than about 2 mm. The first fraction is separated into a metal concentrate fraction, an aggregate fraction a coarse middlings fraction and a fine middlings fraction.
The second fraction is separated into a metal concentrate fraction, an aggregate fraction, and a middlings fraction. The coarse middlings of the first fraction are recrushed and fed into step ii), whereas the middlings from the second fraction and the fine middlings from the first fraction are ground and separated into a metal concentrate fraction and an aggregate fraction.
The second fraction is separated into a metal concentrate fraction, an aggregate fraction, and a middlings fraction. The coarse middlings of the first fraction are recrushed and fed into step ii), whereas the middlings from the second fraction and the fine middlings from the first fraction are ground and separated into a metal concentrate fraction and an aggregate fraction.
Description
STEEL SLAG PROCESSING JIG SYSTEM
FIELD OF THE INVENTION
The present invention concerns the processing of steel slag through a jigging system to recover the metallic fraction without changing the physical properties of both the metallic concentrate and the residual aggregate.
BACKGROUND OF THE INVENTION
Steel production generates a residue called slag. This by-product is formed.
by the additives added during melting such as lime, flux, etc, impurities from the raw material and a limited quantity of metal entrenched in the slag.
Processing of steel production residues is requested to avoid stockpiling and further environmental problems. The feasibility of treating the slag depends on the metal content In the slag, the cost of recovering as much metal as possible and on capacity to dispose the residual aggregate in a profitable way.
As more and more steel is produced from scrap, metal recovered from slag becomes a valuable source of raw material for the steel producers. Existing technologies for recovery involve screening and magnetic separation or fine grinding and recovery through physical separation.
Recovery through magnetic means is a simple and inexpensive process which also allows for use of the residual product as an aggregate in civil works.
However, the rate of recovery is low: the metal content in the recovered concentrate (<20mm) averages 50% and the aggregate's quality is not according to established standards.
The wet grinding process allows an higher rate of recovery (almost 99.5%) of the metal in the slag. The metallic concentrate yield is generally around 90 to 92%. But it produces a very fine wet aggregate. It is an expensive process because 100% of the slag needs to be crushed to a diameter of less than 6mm. Secondly the disposal of the final aggregate is limited because it is wet and also because it is a very fine product.
Therefore, there exists a need in slag processing to recover as much metal as possible by keeping the physical characteristics of the aggregate, which allows for easy disposal and commercialisation.
Jigging systems are well known to separate higher density from lower density material.
Coal preparation, ore beneficiation and sometimes recycling of valuable material do often have a jigging process as a separation step in their flow sheet. Furthermore, the jigging system can be combined with a wide range of other separation processes for this special application.
The main object of this invention is to maximize metal recovery and to produce an easily marketable aggregate, at a competitive cost per ton of product treated.
SUMMARY OF THE INVENTION
The invention is based on crushing the slag to size corresponding to general use for civil works (less than 20 mm). Then the slag is split into two fractions: less than 2 mm and 2 to 20 mm.
The fraction 2 to 20 mm is fed to a jigging system. The system is designed with one discharge gate for metallic concentrate removal and one for removal of the middlings. The residual aggregate is evacuated at the end of the jig as the light product.
The fraction of less than 2 mm is fed to a fines leaning stage which includes a concentrating step, a ball-mill and two dewatering screws.
This concentration step can be a gravity and/or a magnetic separation process.
Up-current separators, spiral separators, conventional fine or centrifugal fine jigging, shaking tables, low and high grade magnets can be used.
The result of the process is a clean metal (more than 95% metal content in the fraction of <20 mm), a clean aggregate with a very low metallic content in the fraction 1,5 to 20 mm and a sand <2 mm. The metal is returned to steel production and the aggregate can be marketed as a road stone for civil works.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a process flow chart outlining the process of the invention;
Figure 2 is a process flow chart of the dry separation steps of the process of the invention; and Figure 3 is a process flow chart of the wet separation steps of the process of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The following detailed description, given by way of example and not Intended to limit the present invention solely thereto, is best understood in conjunction with the accompanying drawings.
The preferred embodiment of the present invention is similar to the process described In figures 1, 2 and 3, which includes five different stages:
Pre-screening and classifying The raw slag is crushed in several stages in a product having a diameter of less than 20 mm. Depending on the intergrowth of the slag and metal, the raw slag must be crushed to a diameter of less than 10 mm. Various known techniques like selective impact crushing, screening, magnetic separation, eddy current and inductive separation as well as air jigging can prepare the feed for the wet separation process by separating pre-concentrates or even free metal (figure 2) The slag Is classified into two fractions: diameter of less than 2 mm and diameter of 2 to 20 mm.
The slag is fed in a feed bin and transported by conveyor to a wet preparation screen.
Separation of the + 2 mm fraction The 2 to 20 mm fraction is fed into the jig where it will be separated in three products, a metal concentrate, the middlings and the aggregate. The metal concentrate represents the final product. The middlings are returned to the crusher to liberate the metal. The aggregate is a marketable product for civil works.
Separation of the -2 mm fraction The fines fraction is forwarded to a cyclone and from the cyclone it either goes to the grinding step directly or it will enter the gravity process for the sand fraction of the slag. Up-current separators, spiral separators, fine jigging, shaking tables, and/or low and high grade magnets are alternatively used for the further enrichment of the metal and the middlings. A light product is separated as a clean slag and can be used as a sand aggregate. The fine metal product is combined with the concentrate from the coarse jig. By this additional gravity process only the middlings will go to the grinding process to get the remaining metal liberated. Figure 3 shows an alternative for the processing of the sand fraction in two separate density processes, one for the coarse and the other for the fine sand. This process can be necessary, if the material is very finely intergrown and the crushing must go down to e.g. 10 mm for the wet process.
Grinding and separation of fines and middlings The middlings produced in the gravity section for fines or alternatively all fines are forwarded to a screw classifier and then to a ball-mill for a selective grinding step. The product from the ball-mill is then washed and dewatered by two screw classifiers.
Thickening, dewatering, and water recycling All the non-metallic fines of a diameter of less than 2 mm are sent to the fines treatment and water recovery circuit. The slimes are clarified in a thickener. The thickener undertow with all the slimes with high solid contents is dewatered in a vacuum filter. The thickener overflow feeds a process water tank. Loss of water in the plant is equalized by fresh water.
Although the invention has been described above with respect to specific embodiments, it will be evident to a person skilled in the art that it may be modified and refined in various ways. It is therefore wished to have it understood that the present invention should not be limited in scope, except by the terms of the following claims.
FIELD OF THE INVENTION
The present invention concerns the processing of steel slag through a jigging system to recover the metallic fraction without changing the physical properties of both the metallic concentrate and the residual aggregate.
BACKGROUND OF THE INVENTION
Steel production generates a residue called slag. This by-product is formed.
by the additives added during melting such as lime, flux, etc, impurities from the raw material and a limited quantity of metal entrenched in the slag.
Processing of steel production residues is requested to avoid stockpiling and further environmental problems. The feasibility of treating the slag depends on the metal content In the slag, the cost of recovering as much metal as possible and on capacity to dispose the residual aggregate in a profitable way.
As more and more steel is produced from scrap, metal recovered from slag becomes a valuable source of raw material for the steel producers. Existing technologies for recovery involve screening and magnetic separation or fine grinding and recovery through physical separation.
Recovery through magnetic means is a simple and inexpensive process which also allows for use of the residual product as an aggregate in civil works.
However, the rate of recovery is low: the metal content in the recovered concentrate (<20mm) averages 50% and the aggregate's quality is not according to established standards.
The wet grinding process allows an higher rate of recovery (almost 99.5%) of the metal in the slag. The metallic concentrate yield is generally around 90 to 92%. But it produces a very fine wet aggregate. It is an expensive process because 100% of the slag needs to be crushed to a diameter of less than 6mm. Secondly the disposal of the final aggregate is limited because it is wet and also because it is a very fine product.
Therefore, there exists a need in slag processing to recover as much metal as possible by keeping the physical characteristics of the aggregate, which allows for easy disposal and commercialisation.
Jigging systems are well known to separate higher density from lower density material.
Coal preparation, ore beneficiation and sometimes recycling of valuable material do often have a jigging process as a separation step in their flow sheet. Furthermore, the jigging system can be combined with a wide range of other separation processes for this special application.
The main object of this invention is to maximize metal recovery and to produce an easily marketable aggregate, at a competitive cost per ton of product treated.
SUMMARY OF THE INVENTION
The invention is based on crushing the slag to size corresponding to general use for civil works (less than 20 mm). Then the slag is split into two fractions: less than 2 mm and 2 to 20 mm.
The fraction 2 to 20 mm is fed to a jigging system. The system is designed with one discharge gate for metallic concentrate removal and one for removal of the middlings. The residual aggregate is evacuated at the end of the jig as the light product.
The fraction of less than 2 mm is fed to a fines leaning stage which includes a concentrating step, a ball-mill and two dewatering screws.
This concentration step can be a gravity and/or a magnetic separation process.
Up-current separators, spiral separators, conventional fine or centrifugal fine jigging, shaking tables, low and high grade magnets can be used.
The result of the process is a clean metal (more than 95% metal content in the fraction of <20 mm), a clean aggregate with a very low metallic content in the fraction 1,5 to 20 mm and a sand <2 mm. The metal is returned to steel production and the aggregate can be marketed as a road stone for civil works.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a process flow chart outlining the process of the invention;
Figure 2 is a process flow chart of the dry separation steps of the process of the invention; and Figure 3 is a process flow chart of the wet separation steps of the process of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
The following detailed description, given by way of example and not Intended to limit the present invention solely thereto, is best understood in conjunction with the accompanying drawings.
The preferred embodiment of the present invention is similar to the process described In figures 1, 2 and 3, which includes five different stages:
Pre-screening and classifying The raw slag is crushed in several stages in a product having a diameter of less than 20 mm. Depending on the intergrowth of the slag and metal, the raw slag must be crushed to a diameter of less than 10 mm. Various known techniques like selective impact crushing, screening, magnetic separation, eddy current and inductive separation as well as air jigging can prepare the feed for the wet separation process by separating pre-concentrates or even free metal (figure 2) The slag Is classified into two fractions: diameter of less than 2 mm and diameter of 2 to 20 mm.
The slag is fed in a feed bin and transported by conveyor to a wet preparation screen.
Separation of the + 2 mm fraction The 2 to 20 mm fraction is fed into the jig where it will be separated in three products, a metal concentrate, the middlings and the aggregate. The metal concentrate represents the final product. The middlings are returned to the crusher to liberate the metal. The aggregate is a marketable product for civil works.
Separation of the -2 mm fraction The fines fraction is forwarded to a cyclone and from the cyclone it either goes to the grinding step directly or it will enter the gravity process for the sand fraction of the slag. Up-current separators, spiral separators, fine jigging, shaking tables, and/or low and high grade magnets are alternatively used for the further enrichment of the metal and the middlings. A light product is separated as a clean slag and can be used as a sand aggregate. The fine metal product is combined with the concentrate from the coarse jig. By this additional gravity process only the middlings will go to the grinding process to get the remaining metal liberated. Figure 3 shows an alternative for the processing of the sand fraction in two separate density processes, one for the coarse and the other for the fine sand. This process can be necessary, if the material is very finely intergrown and the crushing must go down to e.g. 10 mm for the wet process.
Grinding and separation of fines and middlings The middlings produced in the gravity section for fines or alternatively all fines are forwarded to a screw classifier and then to a ball-mill for a selective grinding step. The product from the ball-mill is then washed and dewatered by two screw classifiers.
Thickening, dewatering, and water recycling All the non-metallic fines of a diameter of less than 2 mm are sent to the fines treatment and water recovery circuit. The slimes are clarified in a thickener. The thickener undertow with all the slimes with high solid contents is dewatered in a vacuum filter. The thickener overflow feeds a process water tank. Loss of water in the plant is equalized by fresh water.
Although the invention has been described above with respect to specific embodiments, it will be evident to a person skilled in the art that it may be modified and refined in various ways. It is therefore wished to have it understood that the present invention should not be limited in scope, except by the terms of the following claims.
Claims (10)
1. A method of separating steel slag into a metal fraction and an aggregate fraction comprising the steps of:
i) crushing said slag and subjecting it to screening and recovering slag having a diameter of less than about 20 mm;
ii) separating said recovered slag into a first fraction having a diameter of more than about 2 mm and a-second fraction having a diameter of less than about 2 mm;
iii) feeding the said first fraction into a jig, wherein said jig separates the said first fraction into a metal concentrate fraction, a middlings fraction and an aggregate fraction;
iv) separating the middlings fraction into a coarse middlings fraction and a fine middlings fraction;
v) separating said second fraction into a metal concentrate fraction, a middlings fraction and an aggregate fraction; and vi) recrushing the coarse middlings from the first fraction and feeding into step ii);
wherein the middlings from the second fraction and the fine middlings from the first fraction are ground and separated into a metal concentrate fraction and an aggregate fraction.
i) crushing said slag and subjecting it to screening and recovering slag having a diameter of less than about 20 mm;
ii) separating said recovered slag into a first fraction having a diameter of more than about 2 mm and a-second fraction having a diameter of less than about 2 mm;
iii) feeding the said first fraction into a jig, wherein said jig separates the said first fraction into a metal concentrate fraction, a middlings fraction and an aggregate fraction;
iv) separating the middlings fraction into a coarse middlings fraction and a fine middlings fraction;
v) separating said second fraction into a metal concentrate fraction, a middlings fraction and an aggregate fraction; and vi) recrushing the coarse middlings from the first fraction and feeding into step ii);
wherein the middlings from the second fraction and the fine middlings from the first fraction are ground and separated into a metal concentrate fraction and an aggregate fraction.
2. The method of claim 1 wherein the steel slag is carbon steel slag or stainless steel slag.
3. The method of claim 1 wherein in step (i), the slag is sized by means of one or more screens and separated by magnetic separators, eddy current separators, inductive separators or air jigging
4. The method of claim 3 wherein the magnetic separator is low intensity.
5. The method of claim 3 wherein the magnetic separator is high intensity.
6. The method of claim 1 wherein the separation of the second fraction is carried out using one or more of an up-current separator, spiral separator, fine jigging, shaking table or magnets.
7. The method of claim 1 wherein more than 95% of the metal in the slag is recovered.
8. The method of claim 7 wherein more than 97% of the metal in the slag is recovered.
9. The method of claim 1 wherein the aggregate fraction comprises less than about 0.3%
metal.
metal.
10. The method of claim 1 wherein the aggregate fraction comprises less than about 0.3%
metal.
metal.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2418020 CA2418020C (en) | 2003-02-04 | 2003-02-04 | Steel slag processing jig system |
| DE200410005535 DE102004005535A1 (en) | 2003-02-04 | 2004-02-04 | Process for separating slag into a metal fraction, an intermediate material fraction and a granular mixed fraction comprises crushing the slag and sieving, separating into two fractions, and injecting one fraction into a shaking device |
| BE2004/0059A BE1015890A6 (en) | 2003-02-04 | 2004-02-04 | Jig system for treatment of steel plant slag. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2418020 CA2418020C (en) | 2003-02-04 | 2003-02-04 | Steel slag processing jig system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2418020A1 CA2418020A1 (en) | 2004-08-04 |
| CA2418020C true CA2418020C (en) | 2011-09-13 |
Family
ID=32660951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2418020 Expired - Fee Related CA2418020C (en) | 2003-02-04 | 2003-02-04 | Steel slag processing jig system |
Country Status (3)
| Country | Link |
|---|---|
| BE (1) | BE1015890A6 (en) |
| CA (1) | CA2418020C (en) |
| DE (1) | DE102004005535A1 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| UA106113C2 (en) | 2010-03-05 | 2014-07-25 | Лоеше Гмбх | METHOD for processing stainless steel slags and steelmaking slags for recovering metal |
| EP2906365B1 (en) | 2012-10-12 | 2021-06-09 | Blue Sky Mines Ltd. | Method of and system for treating incinerated waste |
| CN112007752B (en) * | 2020-08-17 | 2023-11-28 | 广西冶固科技发展有限公司 | Method and system for echelon recycling separation of stainless steel refining furnace tailings |
| CN112642580B (en) * | 2020-12-01 | 2023-10-13 | 湖北理工学院 | Disposal method for gradient utilization of steel slag |
| DE102021108322A1 (en) * | 2021-04-01 | 2022-10-06 | EEW Energy from Waste GmbH | Binding agents for building materials, manufacturing process therefor and installation for carrying out this process |
| CN114392828B (en) * | 2022-01-25 | 2023-04-11 | 郑州绿清环保科技有限公司 | Comprehensive recycling treatment method for waste incineration power plant slag |
-
2003
- 2003-02-04 CA CA 2418020 patent/CA2418020C/en not_active Expired - Fee Related
-
2004
- 2004-02-04 BE BE2004/0059A patent/BE1015890A6/en not_active IP Right Cessation
- 2004-02-04 DE DE200410005535 patent/DE102004005535A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| BE1015890A6 (en) | 2005-11-08 |
| CA2418020A1 (en) | 2004-08-04 |
| DE102004005535A1 (en) | 2004-08-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20200204 |