Technology
STEEL PRODUCTION
Steel Plant (annual output approximately 950,000 tons).
Submerged Lance
beside chemical homogenisation with top-blown or porous brick bottom-blown Argon, the equipment enables deep desulphuring by blowing CaSi pulver through the
melt. Alternatively, CaO or C pulver can be used. Beside major reduction in Sulphur, the process reshapes sulphite inclusions improving the mechanical quality of the melt. The equipment enables
modifications to chemical composition of the hot metal by adding lump or powder modifiers or AL wire or filled bars. Operations are currently being fully taken on by Integrated Secondary Metallurgy
System (ISSM).
Ladle Furnace
equipment which improves steel quality by adjusting temperature so as to reach levels required for continuous casting. At the same time it allows adding
synthetic refining slag or synthetic slag modifiers (CaO, Al2O3), which leads to further reduction in Sulphur, while applying the CaSi bar improves plate quality. The ladle furnace allows more
operations to control melt chemistry by using different additions in the form of lumps, Aluminium wire or filled bar. LF treatment also includes Argon homogenisation by blowing the gas in through a
porous brick at the bottom or through a nozzle placed on the top. In correspondence with new metallurgic provisions, ISSM will completly and entirely ensure the achievment of top-quality steel
parameters (desulferization, high steel purity).
Continuous Casting Machine
The one-strand caster has an adjustable curved crystalliser with starting radius of 8 m, water and air cooling and slight reduction of the strand. The process is computer controlled. The casting
process uses a 17 t tundish and the melt surface is protected by strewn material. The strand is protected against re-oxidising by screening pipes and Argon sealed sheath tubes. Samples for chemical
composition control are taken from the tundish after 15, 35, and 45 tons have been cast and the average of the three samples is calculated for final analysis. The adjustable crystalliser allows
switching slab thickness between 145, 180 and 250 mm and slab widths from 1000 mm to 1.500 mm. The slabs are first cut in multiples of order lengths while the maximum total length of slab is 8.8 m.
The continuous caster has a descrapper to remove scraps from the first gas cutting of slabs.
Next in line is slab stamping (identification), cooling, surface inspection of both sides incl. scrap removal check after the first parting, surface defect remediation by burning, and cutting to
order length. Slab casting predictive quality system accuracy is being constantly improved to suit the downstream plate rolling quality requirements.
Integrated Secondary Metallurgy System (ISSM)
This dual-post ISSM enables vacuum degassing, chemical reaction reheating, desulphurisation, removal of non-metallic inclusions,
chemical composition treatment of liquid steel and inclusion modifications, all done simultaneously in two casting ladles.
PLATE ROLLING
3.5 Four-High Rolling Mill
| Production Capacity | 755 thousand t/year |
|---|---|
| Length of rolls | 3 500 mm |
| Working roll diameter | 940-1005 mm |
| Back-up roll diameter | 1750-1 900 mm |
| Minimum thickness of plate | 5 mm |
| Maximum thickness of plate | 80 mm |
| Plate width | 3 300 mm (coated plates) |
| Maximum length of plate | 16 000 mm |
| Maximum rolling force | 62 000 kN |
| Input material heating | Two push furnaces, capacity 75 t/h, 90 t/h; double line furnaces with top and bottom heating fuelled with natural gas and mixed gas; car-hearth furnace for heating of special steels |
The rolling mill include power shear lines to divide plates up to 50 mm thick. Flame cutting is applied to thicker plates.
Heat Treatment
| Continuous annealing furnace | |
|---|---|
| Length | 70 000 mm |
| Capacity | 190 kt/year |
| Two annealing pits | |
| Capacity of charge | 200 t; 300 t |
| Max. plate width | 4 000 mm |
| Max. plate length | 14 000 mm |
| Three annealing furnaces | |
| Capacity | 3 x 30 t |
| Furnace useful width | max 4 500 mm |
| Plate length | 16 000 mm. |
SECTION AND BAR STEEL
| Production Capacity | 170 thousand t/year |
|---|
The section and bar production equipment consists of the heavy-section mill with stand no. 5. The stand is a two-high billet mill incorporated in the heavy-section mill and sharing the heating
pusher-type furnace and operator team with the heavy section train. However, the two lines have separate handling and finishing equipment.
Available machinery is as follows:
Heavy Section Mill
| Product assortment | Round bar, square bar, beam, angle, sheet pile, crane rails, sleeper, rims, special sections |
|---|---|
| Section weight | 18 through 140 kg/m |
| Number of stands | 4 reversing two-highs, stand no. 4 convertible to universal stand with idle vertical rolls, one edge-rolling mill for beams |
| Maximum roll diameter | 940 mm |
| Roll body length | 2 300 mm |
| Universal stand roll diameter | 940 mm |
| Minimum roll diameter | horizontal 1 250 mm, vertical 750 mm |
| Input material heating | Gas fired push furnace 60 t/h |
| Section parting | 3 hot saws |
| Straightening | 7-roll straightener |
| Maximum dispatch length | 21 000 mm |
5. Heavy Section Mill Stand
| Assortment | Rectangular & square billets |
|---|---|
| Width range | 120 - 300 mm |
| No. of stands | 1 reversing two-high stand |
| Maximum roll diameter | 920 mm |
| Minimum roll diameter | 750 mm |
| Roll body length | 2 200 mm |
| Rolling mill drive | one 3 800 kW electric motor |
| Input material heating | heavy-section mill heating furnace |
| Section parting | 2 hot saws, hot power shears 4 000 kN, max. area 4 000 m2 |
| Straightening | 7-roll straightener |
| Maximum piece length | 12 000 mm |
Heavy Section Mill Finishing Shop Equipment:
- 7-roll section straightener for round and square bar
- lateral straightening press for bars
- hyperbolic straightener for round bar
- torque straightener for crane rails and oblong bar
- 2 cold saws
- walking-beam cooling furnace for controlled cooling, anti-flake annealing and soft annealing of rolled bar
- billet & slab grinder
- round bar surface scalping machine
- round bar grinder
- magnetic defectoscopic tester of round billet surface
- ultrasound inspection (outsourced if required)
- sheet piles matching line, lock pressing, lock strength press testing machine
Flame-Cut Plate Shapes
The plate rolling mills have flame cutting equipment to manufacture semi-finished products from the plates. The flame cutting machines have oxygen and natural gas burners and are computer controlled. Surface of the cuttings has scale on it and slag must be removed from the edges after cutting. Flame cutting contours are based on provided drawings.
| Max. piece width | 4 000 mm |
|---|---|
| Max. piece length | through 14 000 mm |
| Material thickness | 5 through 80 mm * |
* higher thickness upon agreement
