RU2347622C2 - Method of processing final disintegrating slag - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to processing of final disintegrating slag and can be implemented for utilising of wastes of metallurgical production, notably of final disintegrating slag of blast, steel and ferroalloy production. The method of processing final disintegrating slag consists in its extraction from a slag-heap, in size grading, in destroying set slag agglomerates in a tumbling drum prior to crumbling and screen sizing, in extraction of metal and other valuable components, and in de-dusting in a pneumatic classifier. At the output end of the tumbling drum there is installed a sizing trommel - a sieving surface for simultaneous destroying and sizing. After separation of ferromagnetic inclusions with a guard magnet the obtained coarse product is subject to crumbling. Underflow and product after crumbling are directed to screening with production of finished fraction sent to the operation of extracting metal inclusions by means of the guard magnet; also underflow is directed to de-dusting into the pneumatic classifier, de-dusted product of which of 0.3-10 mm size is supplied into the magnet separator for extraction of metal ferromagnetic inclusions; while dust-like particles of 0-0.3 mm size are subject to extraction of ferromagnetic inclusions into a system of dust collection which is performed at dust-air flow rate of 12-20 m/s, dust concentration of 1.5-3.0 kg/m³ and magnet field induction at separator rods of 0.1-0.3 T(tesla).

EFFECT: upgraded quality of product processing and reduced dust emission at all stages of final slag processing.

1 dwg, 3 tbl

Description

The invention relates to the field of ferrous metallurgy, in particular for the processing of decaying waste slag.

Known methods for processing dump decaying slag, including excavation, sorting by size, crushing, screening, extraction of metal inclusions and dust collection [1, 2]. Signs that match the features of the claimed invention are:

- the presence in the technology of basic operations: sorting slag by size on the receiving grate, crushing, screening, extraction of metal inclusions, etc .;

- the presence in the processing technology of the dust collection operation, which is carried out in pneumatic separators and pneumatic classifiers.

Reasons that impede the achievement of the expected technical result:

- Intense dust formation in all technological operations;

- low quality of processed products;

- loss of metal inclusions with slag.

These factors are related to the fact that dump decaying slag during storage in dumps under the influence of atmospheric phenomena, physicochemical transformations, and interaction with the environment changes its initial properties. Slag is caked, compacted, partially hydrated, part of the minerals is washed out, eroded, etc. As a result, the object of processing is a material with heterogeneous specific properties in the form of separate dense plates and pieces of seized slag particles, powder material, metal particles, refractory scrap, crystallized slag of various sizes and shapes.

The closest technical solution adopted for the prototype is a method of processing waste slag [3], including the extraction of slag from the dump, preliminary sampling of large metal scrap from the waste slag, multi-stage crushing of slag, vibration separation of slag on a roller grill into fractions, magnetic separation and air classification in the fluidized bed mode. Signs that match the features of the claimed invention are:

- excavation of dump slag and its submission for processing;

- sorting of waste slag by size;

- crushing dump slag to a given size;

- extraction of ferromagnetic inclusions from the slag by magnetic separation and air separation in the fluidized bed mode.

Reasons that impede the achievement of the expected technical result:

- low efficiency of separation by size and screening of waste slag;

- intense dust formation at all stages of the process;

- high dust content of processed products;

- high slagging of metal inclusions extracted from slag.

The technical problem solved by the invention is to reduce dust emissions at all stages of processing waste slag and to improve the quality of processed products.

The problem is solved due to the fact that in the method of processing dump decaying slag, including its removal from the dump, sorting by size, destruction of the caked slag agglomerates in the tumbling drum before crushing and screening, removing metal and other valuable components, dust removal in the pneumatic classifier, a difference is made consisting in the fact that at the output end of the tumbling drum, a butam is installed - a screening surface for simultaneous destruction and sorting by size in this case, the large product obtained after separation of the ferromagnetic inclusions by the iron separator is sent to crushing, and the small product and obtained after crushing is sent to screening to obtain a commercial fraction directed to the operation of extracting metal inclusions using the iron separator, and a small product sent to dust removal in the pneumatic classifier, dust-free product with a particle size of 0.3-10 mm is fed into a magnetic separator for the extraction of metallic ferromagnetic inclusions, and dust-like hours particles with a particle size of 0-0.3 mm are sent to extract ferromagnetic inclusions into the dust collection system with a magnetic-air separator located in it, and the extraction is carried out at dust-air flow velocities of 12-20 m / s, dust concentration of 1.5-3.0 kg / m ³ and magnetic field induction on the rods of the separator 0.1-0.3 T.

The solution to the problem is possible because a butamer is installed at the output end of the tumbling drum, here the agglomerated particles of slag are simultaneously destroyed and sorted by size together with the general stream of dump slag. As a result of sorting, all weak, broken and dusty particles fall into a small product, while strong and large particles go to crushing. Thus, the problem of freeing the total flow of dump slag from weak disintegrating into dust at all stages of the processing of seized agglomerated particles of slag is solved. In addition, in the process of passing through the tumbling drum, the metal inclusions are opened and cleaned of slag. In the subsequent stages of processing, they are easier to detect and extract, because they are devoid of a slag shell.

It is important that the bulk of the decaying waste slag consists of relatively fine dust particles, about 65-80% finer than 0.3 mm, while dust removal of the entire waste slag stream, including large lump material, is a difficult technical task. Its solution is possible by preliminary destroying weak grains, separating them by sorting in a buter with the separation of a fraction of 0-10 mm on the screen and subsequent dedusting along the ± 0.3 mm border of this narrow fraction of 0-10 mm in a pneumatic classifier. Removing ferromagnetic inclusions from a fraction of 0-10 mm, 80-90% of which consists of dust-like classes of slag, is also difficult, but after dust removal along the ± 0.3 mm boundary, the process of extracting metal inclusions from slag of a fraction of 0.3-10 mm can be successfully implemented by magnetic separation. The extraction of ferromagnetic inclusions from a fraction of 0-0.3 mm by magnetic separation methods according to the above analogues and prototype is not performed, which leads to the loss of valuable metal inclusions with slag and a deterioration in the quality of slag products, which is associated with the presence of metal inclusions in it. The solution to this problem is carried out by extracting ferromagnetic inclusions from slag with a grain size of less than 0.3 mm, sent to a dust collection system with a magnetic-air separator placed in it, and the extraction is carried out at dust-air flow velocities of 12-20 m / s, dust concentration 1.5 -3.0 kg / m ³ and magnetic induction on the separator rods of 0.1-0.3 T.

An embodiment of a method for processing waste decaying slag is shown in the drawing.

A method of processing waste decaying slag is as follows. The dump mass from dump 1 is fed by a forklift 2 to the receiving rack 3 for loading into the hopper 4, from the hopper by the feeder 5 the slag is loaded into the tumbling drum 6. In the tumbling drum, the entrained agglomerated pieces of slag are destroyed, the metal component is cleaned of slag, and at the output at the end of the tumbling drum, a butar is mounted - a screening surface on which at the same time the waste slag is destroyed and sorted by size. Mostly weak slag grains fall into the fine fraction, and strong pieces of slag, including large metal inclusions, fall into the large fraction. Ferromagnetic inclusions are extracted from a large product stream using an iron separator 7. Valuable components are removed at the manual sampling station 8. Then, large waste slag is fed through the conveyor 9 to the crusher 10. The crushing products from the crusher 10 along the conveyor 11 and small screening products from the tumbling drum are fed to the screen 12. Here, the slag is screened for commercial fractions of slag crushed stone which are fed through conveyors 13 and 14 to the operation of extracting metal inclusions using iron separators 15 and 16, and then to stacks 17 and 18. A small screening product with a fraction of 0-10 mm using an elevator 19 is loaded on dust removal e at the boundary of ± 0.3 mm to the pneumatic classifier 20. The exhaust air is cleaned in the dust collector 21, the group cyclone 22, and then with the help of the fan 23 the air is fed for fine cleaning into the bag filter 24 and into the exhaust pipe 25. Dust-free product with a particle size of 0.3 -10 mm along the conveyor 26 serves for separation in a magnetic separator 27, in which metal ferromagnetic inclusions are removed. A non-magnetic product is conveyed by conveyor 28 to a warehouse 29, and a magnetic product is sent to a special container 30. To extract ferromagnetic inclusions from dust particles with a particle size of 0-0.3 mm, a magnetic air separator 37 is placed in the dust collection system, through which the ferromagnetic particles are fixed to screens of the magnetic rods of the separator, and slag in the air stream is sent for cleaning to the dust collector, cyclone, bag filter, etc. The screens of the magnetic rods are periodically cleaned of adhering ferromagnetic particles, the latter is sent to the hopper for a small magnetic product 37.

The cleaning of magnetic products extracted at all stages of the processing of slag is carried out by breaking the bonds holding the inclusions of slag on the metal product in an impact crusher followed by magnetic separation.

The parameters for the extraction of metal inclusions from slag with a particle size of 0-0.3 mm were selected empirically. For this, a special installation was mounted in which various modes of air flow were created, the concentration of dust-like particles of slag in the air flow and the magnetic field were varied by selecting the appropriate permanent magnets. The results of selecting the parameters for the extraction of ferromagnetic particles from the slag fraction 0-0.3 mm are shown in tables 1-3.

Thus, the speed of the dusty air flow is 12-20 m / s; dust concentration equal to 1.5-3.0 kg / m ³ and magnetic field induction on the separator rods of 0.1-0.3 T during magnetic separation of ferromagnetic inclusions from slag fraction 0-0.3 mm provide the best degree extraction of the magnetic product, its slagging and loss of the magnetic product with slag.

The proposed method for processing waste decaying slag can be used for disposal of waste from metallurgical industries, in particular dump decaying slag of blast furnace, steelmaking and ferroalloy production.

Table 1 The results of selecting the air flow rate during the separation of the slag fraction 0-0.3 mm Parameter Name Air speed, m / s 8 10 12 fifteen twenty 22 25 The output of the magnetic product,% abs. 2.0 3,5 4.2 4.3 4.2 3,7 2.0 Slagging of the magnetic product,% 38.3 26.6 18.7 16.3 15.9 22.8 24.2 Loss of magnetic product with slag,% abs. 2.6 1,1 0.4 0.3 0.4 0.9 2.6

Note. The experiments used dump decaying slag from the production of refined ferrochrome. The concentration of slag in the air flow of 2.0 kg / m ³ . Induction of the magnetic field on the rods of the separator 0.2 T.

table 2 The results of the selection of the concentration of slag in the air stream during the separation of the slag fraction 0-0.3 mm Parameter Name The concentration of slag in the air stream, kg / m ³ 0.8 1.3 1,5 2.0 3.0 3,5 4.0 The output of the magnetic product,% abs. 2.5 3.3 4.1 4.2 3.9 2.6 2.2 Slagging of the magnetic product,% 21.6 19,4 18.5 18.7 17.9 24.4 37.6 Loss of magnetic product with slag,% abs. 2.0 1,1 0.3 0.4 0.3 1.8 1.9 The duration of the experiment, min 10.0 6.2 5,4 4.0 2.7 2.2 2.0

Note. The experiments used dump decaying slag from the production of refined ferrochrome. Airflow speed 15 m / s. Induction of the magnetic field on the rods of the separator 0.2 T.

Table 3 The results of the selection of the magnetic field induction on the rods of the separator during the separation of slag fraction 0-0.3 mm Parameter Name Magnetic field induction on the separator rods, T 0.05 0.08 0.1 0.2 0.3 0.4 0.5 The output of the magnetic product,% abs. 0.8 2.2 3.9 4.4 5.2 5.8 7.1 Slagging of the magnetic product,% 15.9 16.6 18,4 19.0 22.8 36.9 46,4 Loss of magnetic product with slag,% abs. 3.9 2.7 0.6 0.6 0.5 0.5 0.5 The duration of the experiment, min 10.0 6.2 5,4 4.0 2.7 2.2 2.0

Note. The experiments used dump decaying slag from the production of refined ferrochrome. Air velocity 15 m / s ³ . The concentration of slag in the air flow of 2.0 kg / m ³ .

References

1. B.I. Bayramov, V.P. Zaiko, M.A. Ryss and others. Processing of slag from ferroalloy production. South Ural Book Publishing House, 1971. 64 p.

2. V.N.Karnoukhov, Yu.I. Voronov, V.P. Zaiko, V.I. Zhuchkov. Low-carbon ferrochrome technology. Ekaterinburg: Ural Branch of the Russian Academy of Sciences, 2001. ISBN5-7691-1122-4.

3. RF patent RU2145361 C1, 02/10/2000, C22B 7/4, Method for processing waste slag.

Claims (1)

A method of processing waste decaying slag, including its removal from the dump, sorting by size, destruction of set slag agglomerates in a tumbling drum before crushing and screening, removing metal and other valuable components, dust removal in a pneumatic classifier, characterized in that a butyram is installed at the output end of the tumbling drum - screening surface for simultaneous destruction and sorting by size, while the resulting large product after separation of iron the ferromagnetic inclusions are directed to crushing, and the small product and obtained after crushing are sent to screening to obtain a marketable fraction directed to the operation of extracting metal inclusions using an iron separator, and a small product sent for dedusting into a pneumatic classifier, dust-free product with a particle size of 0.3- 10 mm is fed into a magnetic separator to extract metallic ferromagnetic inclusions, and dust particles with a particle size of 0-0.3 mm are sent to extract ferromagnetic inclusions of the dust collecting system with a magneto-air separator located in it, the extraction being carried out at a dust-air flow rate of 12-20 m / s, dust concentration of 1.5-3.0 kg / m ³ and magnetic field induction on the separator rods 0.1-0 , 3 T.