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KOVOHUTY a.s. Krompachy, SR

Modernization of copper anodes production - capacity 250 t Cu/melt
Implementation: 2007-2008

The company Kovohuty, a.s. purchased the anode technology equipment from the company Simar Societá Metali Marghera S.p.A., which was disassembled by the company ILD SK, it was transported from Italy to disassembled, the company designed its location at the company’s premises and re-assembled it.

The technology is located in a new hall and is complemented by new equipment that was not suitable for disassembly and transportation.

Scope of supplies:

  • Overall design solution.
  • Construction part – complete new two-part hall, including the foundations, foundations under the technology – foundations under the furnace 30×30 m at the level of -8 m (ground water at the level of -2 m).
  • Disassembly, reprocessing and assembly of the anode furnace MAERZ and casting carousel OUTOKUMP.
  • Supply of cooling towers and cooling circuits.
  • Supply of hydraulic stations.
  • Supply of a compressor station.
  • Supply of an after-burning chamber, utilization boiler 10 t/h (steam), recuperator, steam turbine condensation circuit.
  • Filtration unit ALFA-JET – 3000 m2, including the heated hopper and insulation.
  • Fan , Q = 55.5 m3/s, tmax =130°C, 500 kW, air-conditioning pipeline.
  • Sources and distribution of technical gases.
  • HV connection, transformer station, LV sub-station, complete control system.
  • Scales, cranes, mobile machines.

The general contractor was the company ILD SK, spol. s r.o. Košice

The main production equipment is a melting refining furnace MAERZ – tilting with flame heating, and a casting carousel.
The aim of the operations is to refine the material until it is enriched to the level of 99.5% copper content. In the furnace, that is kept under slight vacuum, the following operations are gradually performed:

a) Loading and melting
b) Oxidation
c) Draining the slag
d) Reduction
e) Casting

The melting furnace with a capacity of 250 tons of Cu/melt was purchased in Italy, it was disassembled, reprocessed and newly installed at the company Kovohuty Krompachy,a.s. 

1. The basic media are the flue gases leaving the furnace MAERZ at different operating modes of the furnace.
Flue gas flow from the furnace – maximum 30,000 Nm3/h
Flue gas flow, effective – maximum 140,000 m3/hFlue gas flow – loading 27,000 Nm3/h

– oxidation 15,800 Nm3/h
– reduction 7,500 Nm3/h
– casting 9,300 Nm3/h

Flue gas temperature at the furnace outlet 1,150 – 1,200°C
Flue gas temperature at the boiler outlet about 450°C
Flue gas temperature at the exchanger outlet about 250°C
Temperature at the outlet of the mixing chamber about 160°C

2. The second main medium is air exhausted from various sources of dust, from the furnace itself as well as from the related technological equipment. The temperature of the air exhausted from the particular dust sources is in the interval of about 20-90°C, the air enters the mixing chamber in which it mixes with the flue gases from the furnace, which have a temperature of about 250°C at the outlet of the recuperator. At the outlet of the mixing chamber (at the inlet to the filter unit) the air temperature is about 160°C.

3. Another carrier medium is the combustion air for the main burners of the furnace MAERZ. The combustion air is preheated in the heat exchanger and transported to the furnace burners using a fan.

The after-burring equipment is used to burn CO and CH4 (especially during the reduction phase of the furnace), which could cause an explosion at the furnace outlet. The after-burning equipment is connected to the furnace outlet flange via refractory lining. The combustion chambers are fitted with air burners that burn natural gas. Under both chambers of the after-burning furnace, there are collecting containers for collecting dust from the flue gases. The containers are balanced from the area below the chambers by a forklift truck 

Basic technical data:
– Dimensions of the after-burning equipment 9×4 m 
– Height 12 m 
– Number of chambers – 2 
– Number of containers – 3
– Number of burners – 2

The boiler is used for cooling flue gases from the temperature of about 1,100-1,200°C to the temperature of about 450°C at the boiler outlet flange. The heat extracted from the flue gases is used for the production of saturated steam of 1.2 MPa. 
The boiler consists of diaphragm walls made of refractory tubes, the walls are mounted in a supporting structure and from the outside they are covered with thermal insulation with profiled sheet metal. 
The boiler is equipped with inspection holes at different height levels, which are used to check the inside of the refractory pipes. Under the boiler chambers, there are hoppers for catching the dust from flue gases as well as from the boiler cleaning. The dust from the from hoppers are discharged into mobile containers. 
The boiler is supplied with water from the existing water treatment plant, which consists of a raw water storage tank, dosing pumps and mixing tanks. The softened water is pumped from the storage tank to the degassing unit. The degassed water is transported to the boiler drum via a pair of feed pumps (100% reserve).

Basic technical data:

Type

high-pressure flue gas boiler

Rated output

7.5 t/h

Maximum output

9.6 t/h

Peak output

10.5 t/h – with dust-free boiler

Minimum output

1-2 t/h – in casting mode

Output steam over-pressure

22.5 bar

Maximum steam pressure

29.5 bar

Testing pressure

48 bar

Output steam temperature

460 +/- 10°C – at rated output

Maximum steam temperature

490°C

Supply water temperature

105°C

Dimensions (l x h x w)

10.8 x 4 x 17.3

Dimensions, including the structure

13.8 x 9.2 x 17.3

Weight, including the cartridges

125 t

Operating flue gas inlet temperature

1,000°C

Maximum flue gas inlet temperature

1,100°C

Output flue gas temperature

380-480°C – at rated output

Output flue gas temperature

245 +/- 30°C – in casting mode

 

The flue gas-air exchanger, which is installed at the outlet of the utilization boiler allows heat to be transferred between the flue gases exiting the boiler and the combustion air intended for the main burners of the furnace MAERZ. The exchanger consists of four chambers, two of which are parallel. To prevent condensation at the fresh air inlet to the exchanger, there is a recirculation unit at the inlet at which the hot air from the outlet pipeline is mixed using a flap. 
In each chamber, there are 96 steel tubes DN 219 mm through which the flue gases pass. The tubes are equipped with a cleaning device controlled from the exchanger ceiling. The primary air flows perpendicularly to the tube set. The dust from the tubes falls into the hoppers below which there are the collection containers. 

Basic technical data
– Dimensions of the exchanger 8.2 x 7.5 m 
– Height 13 m 
– Number of chambers 4 
– Flue gases flow – maximum 30,000 Nm3/h 
– Flue gas temperature, inlet – maximum 500
– Flue gas temperature, outlet 220-250°C 
– Air flow 20,000 Nm3/h 
– Air temperature, inlet, ambient 
– Air temperature, outlet 400°C 

The flue gases exiting the heat exchanger at a temperature of 220-250°C are mixed with air exhausted from various sources of dust (e.g loading door, slag discharge door, pan, outlet flange from the furnace, tap hole, etc.) at a temperature of about 70-90°C. The required flue gas temperature at the outlet of the mixing chamber is about 150-160°C. If this temperature is exceeded, the ambient air is sucked into the air using a suction flap. 

Basic technical data
– Dimensions of the mixing chamber 5,000 x 5,000 mm 
– Chamber height, including OK 14,650 mm 
– Dust removal, rotary feeder RP 250 
– Suction flap Ø 710 mm 

The flue gases leaving the exchanger are mixed with air exhausted from the lines and then enter the two parallel filter units ILD. The filtration units are already located outside the hall. These are textile hose filters with hose regeneration with treated compressed air. 
The polluted air enters the channel into the filter housing, part of the dust falls directly into the hoppers. The air is then transferred to the outside of the filtration hoses where the solid particles are separated from the air stream. The clean air flows from the filtration hoses to the clean side of the unit. 
The dust falls into two channel hoppers of each filter unit. From the hopper, the dust is transferred through a screw conveyor and a rotary feeder into a big-bag. 
The hoppers of the filters and the housing parts are heated by self-regulating heating cables, the entire filter unit is thermally insulated. 

Basic technical data

– Filter type ALFA-JET 3000
– Filtration surface 3,000 m2
– Filtration speed about 14-20 mm/s
– Pressure loss 500-1,500
– Layout dimensions of the filter 2x(7,900 x 7,000) mm
– Filter height 15,000 mm
– Hopper model 4 x with a channel.

Basic technical data
– Fan type RSAS-1400, radial to the clutch
– Flue gas flow amount 55.5 m3/s 
– Flue gas temperature 110°C 
– Flue gas temperature – maximum 130°C 
– Total pressure 7,000 Pa 
– Electric motor power input 500 kW 
– Frequency converter control 
– Accessories – vibration isolators, compensators, discharge silencer, 
noise insulation of the spiral housing.

The casting carousel with a diameter of 9,500 mm consists of 16 moulds. Due to the high humidity of the exhaust air, the carousel suction is performed in a separate route, including the exhaust fan. Above the carousel, there is a shaped line from which the suction pipeline is led through a water curtain into the fan. The water curtain is used to capture barium sulphate. The water with barium sulphate is connected to the cooling circuit of the casting machine. The cleaned air passes through the chimney into the ambient air. 

Basic technical data of the fan
– Fan type RSA-400, radial to the clutch
– Flue gas flow amount 5.5 m3/s 
– Flue gas temperature 60 °C 
– Flue gas temperature – maximum 80°C 
– Total pressure 2,000 Pa 
– Electric motor power input 22 kW 
– With control – without control
– Accessories – vibration isolators, compensators, noise insulation of the spiral housing.

The control system was designed and implemented by the company ENETEX-TEP, s.r.o. from Brno. 

The technology control system is divided into three separate automatic machines S7-300 according to the following technological units: 
– Furnace and casting equipment control 
– Melting of copper in the furnace and subsequent removal and cleaning of flue gases 
– Furnace cooling 

Each control system must meet the requirements of extensive technology control as well as the safety requirements. These requirements are met by the processors CPU315F-2 PN/DP that incorporate both a technology control program and a safety application control program – together with used digital I/O and analogue input cards. 
These processors are equipped with two communication interfaces. Profibus DP (double line) is used for communication with the peripherals ET200M, actuators and local control panel of the furnace TP277 . The other communication interface is used for the interconnection of all three systems and their connection to the process visualization stations located in the control room.