Aluminium. Thermal Process Engineering

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1 Aluminium Thermal Process Engineering TENOVA is a world-wide supplier of advanced technologies, products and services for the metal and mining industries.

2 A L U M I N I U M Aluminium Light and Easy to Recycle The outstanding material properties and easy recycling of aluminium are the reasons why it has become one of the most important materials in the automobile, building, machinery and aerospace industries. In terms of quality and effciency, the melting, heat treatment and recycling of aluminium pose severe challenges for plant suppliers and operators. Material properties low density corrosion resistance high thermal and electrical conductivity excellent reflection of light high strength good forming properties unlimited recyclability with no loss of quality a wide range of possibilities of surface treatment Plant technology The companies of the LOI Italimpianti Group are the leading suppliers of thermal process technology. That also applies to technology and equipment for the aluminium industry. The process expertise available includes melting and recycling furnaces for charge weights up to 120 t, continuous casters, ingot casters and downstream plants such as ageing furnaces for structural, semifinished and finished aluminium products. These exceptional properties have boosted annual growth in aluminium use to as much as 7 % over recent decades. 2

3 C O N T E N T S Contents Melting and casting plants 4 Melting and casting furnaces 5 Heating systems 6 Remelting plants for aluminium recycling 7 Environmental aspects 8 Continuous casters for extrusion billets and rolling slabs 9 Automatic ingot casting lines Heat treatment plants 10 Age hardening furnaces batch and continuous 12 Heat treatment plants for wheels 14 Age hardening furnaces for extruded sections 16 Annealing plants for aluminium coils and foils 18 Special solutions for the aerospace industry Process electronics 19 Fully automated control systems 3

4 M E L T I N G A N D C A S T I N G F U R N A C E S T U R N - K E Y P L A N T S Melting and Casting Furnaces Turn-key Plants Hearth-type melting furnaces Casting furnaces LOI Italimpianti hearth-type melting furnaces are used for melting block metal, production scrap etc. or for mixing aluminium from the electrolytic cell with block metal and recycled material, which are melted in the furnace. Specific benefits: plant design tailored to client's requirements extremely easy to use low specific energy requirements high heat recovery efficiency low burn-off losses minimal pollutant emissions convenient control long service life high melting capacity large bath volume low maintenance requirements 4 Alloying elements can be added to the casting furnace and melted. The burners are controlled as a function of the bath temperature. The casting furnace is equipped with a hydraulic tilting system which feeds liquid metal to the casting machine in a controlled way. Specific benefits: precise temperature control low energy consumption low maintenance requirements precise level control very smooth metal flow From individual components to turnkey aluminium casting plants, the comprehen sive service portfolio of LOI Italimpianti includes design, engineering, supply, assembly and commissioning. The company has already supplied all types of casting and melting furnaces and its range includes tilting and stationary, circular and rectangular furnaces, furnaces with inductive heating or gas firing systems, furnaces designed for top or side charging with solid or liquid metal, using automatic charging systems, hearth-type and circular melting furnaces, vacuum or atmosphere types, single and multi-chamber furnaces. Furnaces supplied by LOI Italimpianti with bath capacity of up to 120 t and melting rates of up to 36 t/h are in service with leading aluminium producers and processors.

5 H E A T I N G S Y S T E M S 1. Tilting hearth-type furnace for melting aluminium block metal and thick-walled scrap, 50 t, natural gas firing system, with regenerative air preheating system. 2. Tilting casting furnace for molten aluminium, for alloying element addition and charging casting machines, bath capacity 35 t, natural gas firing system. 3. Melting/casting furnace, bath capacity 110 t, on a casting machine with 9,200 mm casting length 4. Circular melting furnaces with lid removal machine 5. Regenerative heat recovery system Heating Systems Furnaces may be equipped with oil or natural gas burners with electric ignition systems and automatic flame monitoring systems. For optimum radiant and convective heat transfer, burners with large flame volumes are used. Mathematical heat distribution models ensure that the ideal burner configuration is selected for each furnace. LOI Italimpianti is also experienced in the design and production of plants with electromagnetic agitation, porous plugs, electromagnetic recirculation, energy-saving regenerative burners or central regenerators. Advantages of regenerative compared with recuperative air-preheating: higher air preheat temperature lower burner rating required more effective heat recovery possibility of heat storage no steel parts in hot area compact design Advantages of centrally arranged regenerator compared with conventional regenerative burner pairs: no switchover cycle constant flue gas or air preheat temperature no flue gas bypass all the flue gas flows through the system and is available for waste heat recovery lower number of burners for lower cost and space requirements smoother control of furnace without switchover cycles the ideal basis for meeting future emission standards 5

6 R E M E L T I N G P L A N T S F O R A L U M I N I U M R E C Y C L I N G Twin-Chamber Melting Furnace TCF for the remelting of contaminated aluminium scrap without salt Bath size: t Melting capacity: 7 t/ h 2. Aluminium recycling plant: two melting furnaces operated in parallel one casting furnace two continuous vertical casting machines one fume purification plant Remelting Plants for Aluminium Recycling Rising energy prices and the rapid depletion of natural resources make the recycling of aluminium scrap increasingly attractive from an environmental point of view. The Twin-Chamber Melting Furnace TCF developed by LOI Italimpianti, which has been continuously optimized, is ideal for the recycling of "dirty" scrap contaminated by oil, grease, paint or thermal insulation layers. The TCF was especially designed for remelting contaminated thin-wall scrap. Together with a fume purification plant, a TCF represents a cost-effective environmentally compatible solution for aluminium recycling. Twin-Chamber Melting Furnace (TCF) for aluminium scrap no salt required pre-treatment of scrap not necessary low energy consumption high metal yield safe operation with forced convection of molten aluminium The two furnace chambers are separated by a partition. The heating chamber is heated directly; the scrap chamber is mainly heated indirectly. Flue gas flow through the opening in the partition is controlled by a damper to obtain the temperatures required for preheating, partial combustion of the contaminants and melting. Gas recirculation to the scrap chamber ensures optimum heating of the scrap. 6

7 E N V I R O N M E N T A L A S P E C T S 3. Regenerator CCR The melting furnaces feature regenerative air preheating systems for the optimum use of energy. 4. Scrap shavings and small scrap items can be added to melt flowing between the two chambers by inductive circulation. This approach reduces metal loss by oxidation. 5. Automatic charging machine for a Twin- Chamber Melting Furnace. 6. Fume purification plant for a Twin-Chamber Melting Furnace The pyrolysis gas evaporating from the contaminants is fed to the burners of the heating chamber by a recirculation fan. Here, additional air is injected and the gas is incinerated in an environmentally compatible way. The technology of the Twin-Chamber Melting Furnace allows efficient melting of chips with high metal yield. The same applies to can scrap and other light and small-sized scrap. Environmental Aspects The fume purification plant removes dust and toxic components such as HCl and HF from the flue gas, ensuring an environ - mentally compatible production process. Automatic charging machines prevent flue gas from escaping during charging and allow automated operation. TCFprocess avoids scrap treatment or additional handling. 7

8 C O N T I N U O U S C A S T E R S Caster for multiple casting of extrusion billets comprising: the casting pit with a casting table operated by a hydraulic cylinder two sump pumps, installed in the casting pit, for controlling the water level a safety grid a water frame installed above the pit a mould table running on rails, designed for lateral movement 2. Vertical continuous casters for aluminium rolling slabs Capacity: up to 120 t/batch and lengths up to 10,500 mm Vertical Continuous Casters for Extrusion Billets During the casting operation, molten metal is fed to the caster from the casting furnace in a controlled way. The casting of the strands proceeds, by precisely controlled lowering the casting table and controlled feeding of cooling water to the system. The casting cylinder is self-guided. 8

9 S T A C K I N G L I N E S Highly automated casting line for producing aluminium ingots 4. Casting 5. Stack storage section Vertical Continuous Casters for Rolling Slabs Billets and slabs with lengths of up to 10 m are casted using LOI Italimpianti plants. All the casters are fully automated and are equipped with laser systems for mould level control. Ingot Casting Lines LOI Italimpianti atmospheric or watercooled ingot casting lines are designed for casting high-quality ingots at high production rates. They are equipped with automated ingot handling (stacking and strapping) systems. 9

10 A G E H A R D E N I N G F U R N A C E S Age hardening plant (continuous furnaces) with media and air quenching for repetition parts 2. Age hardening plant (overhead furnaces) with media quenching for loads with different shapes 3. Age hardening plant (continuous furnaces) with air quenching chamber for structural parts 4. Age hardening plant (continuous furnaces) with air quenching for structural parts of the automotive industry 2. Age Hardening Furnaces - Batch and Continuous The paramount objective of LOI Italimpianti is fully automated operation where possible. Nowadays, all systems must be fully integrated into the material flow process to avoid unnecessary handling operations. This applies equally to batch-type and continuous furnaces. For large production runs, continuous furnaces with different handling systems specially designed for the parts concerned are available. When producing individual parts for special applications, flexible charging arrangements and the ability to handle small batches cost-effectively are essential requirements. Points to be considered by customers when opting for batch-type or continuous plants include: energy consumption, reproducibility of results, plant handling and flexibility, batch sizes required for customer orders and the duration of customer orders. A decision can only be taken on the basis of a precise analysis of the individual application. 10

11 A G E H A R D E N I N G F U R N A C E S Overhead furnace with moveable quench baths considerable flexibility with respect to batch selection and changeover time high temperature homogeneity for solution annealing and age hardening short quench delay easy change of the quench media easy handling excellent economics fully automated charging and handling Age hardening furnaces with chain or roller conveyors handling of individual or stacked charge trays of highly variable geometry transport with and without trays fully automated stacking and storage fully automated charge tray loading and unloading highly reproducible heat treatment media and air quenching with high reproducibility 11

12 H E A T T R E A T M E N T P L A N T S F O R W H E E L S Age hardening plant (overhead furnaces) with quench for mass-produced parts 2. Age hardening plant (continuous furnaces) for wheels, with automatic charging and discharging 3. Age hardening plant (continuous furnaces) with media quenching for wheels of various sizes (solution furnace below, ageing furnace above) Heat Treatment Plants for Wheels Aluminium alloys call for special heat treatment combining solution annealing, quenching and age hardening. Plants for the heat treatment of cast and forged aluminium wheels for cars and trucks are one of the specialities of LOI Italimpianti. Depending on the requirements of the individual application, the following types of furnace are used: overhead monorail furnaces chain conveyor furnaces roller hearth furnaces overhead furnaces Overhead monorail furnaces The parts are arranged on different levels, allowing an extremely compact design at the same time as high throughput combined with long soaking times. The overhead monorail system guarantees smooth material handling. Homogeneous heating and the horizontal positioning of the wheels prevent distortion. The standard equipment of this type of furnace includes handling systems for automatic charging and discharging. 12

13 H E A T T R E A T M E N T P L A N T S F O R W H E E L S Multi-row chain conveyor furnace for wheels 5. Charging of chain conveyor furnaces 6. Single wheel charging of the solution furnace 7. Automatic part feeding 7. Chain conveyor furnaces The chain conveyor system ensures defined, steady material handling through the heat treatment furnace without using containers or trays. The furnace hearth is charged in a number of rows and is suitable for heat-treating wheels and components. Automatic charging and discharging systems mean that this type of furnace can be integrated into any fully automated production line. Roller hearth furnaces In the roller hearth furnace the goods will be transported lying on rollers. The goods suitable to this transport and the heat treatment have to be chosen accordingly. The rollers can be driven all together, in groups or separate. Bearings and drives usually will be installed outside the furnace. Roller hearth furnaces easily can be integrated in a fully automatic production line. Overhead furnaces Overhead furnaces are versatile plants that are ideal for the heat treatment of wheels in small batches. The wheels are positioned on a rack and then heattreated automatically. Special features: heat treatment plant tailor-made for each production process fully automated heat treatment, including charging, quenching and discharging no trays or boxes needed for chain conveyor or roller hearth transports random charging of wheels multi-layer and/or multi-row placement of wheels flexible heat treatment programming continuous furnaces, solution annealing and ageing furnaces can be installed upon each other, reducing space requirements suitable for heavy wheels 13

14 A G E I N G F U R N A C E S Stationary Ageing furnace 2. Moveable Ageing furnace 2. Ageing Furnaces for Extruded Sections These automatic ageing furnaces for aluminium can be programmed for any type of heat treatment (temperatures and times) and handling operations required without needing operator intervention. Furnaces are available either with electric heating or direct or indirect gas firing systems and air recirculation to meet all requirements. Longitudinal or transverse recircu - lation can be selected depending on the individual application. LOI Italimpianti offers the following furnace types for the Ageing of extruded sections: moveable chamber furnace stationary chamber furnace pit type furnaces overhead furnace stepper furnace Moveable chamber furnace The moveable chamber furnace is positioned on a rail system by electric motors and drives mounted on the ends of the furnace. Charging boxes filled with extruded sections are loaded onto a vacant stacking station using the lifting and conveyor systems installed. No complex charging equipment is needed. This furnace also requires less space than other types. When the heat treatment program has been completed, the doors 14

15 A G E I N G F U R N A C E S 3. Stationary Ageing furnace 4. Moveable Ageing furnace at the ends of the furnace is opened and the furnace is simply moved along the track to a stacking station with another charge. Stepper furnace with automatic charging system The concept of the stepper furnace bases on the idea to separate heating and holding section. A high-power heating section will heat the charge. After reaching the target temperature the charge will be moved into the first holding section and will clear the heating section for the following charge. This area of the furnace does not require high heating power, but only a reduced power for holding. Several holding sections can be arranged acc. to the requested throughput. Chamber furnace with automatic charging system The automatically loaded charging racks are charged into the furnace on one or more tracks via a roller table system. When the heat treatment of a charge has been completed, the door at the end of the furnace are opened and the charging racks are transferred to the discharging station by the roller table system. The new charge is transferred to the furnace. When the charging racks have been unloaded, they are returned to the stacker by a rack conveyor system, closing the transportation loop. 15

16 A N N E A L I N G F U R N A C E S F O R A L U M I N I U M C O I L S Heating phase Cooling phase Circulation fan Nozzle system Radiant tube Cooling Protective gas 1. Annealing furnace for aluminium coils 2. Principle of the Single-Coil Lifting Hearth Furnace Annealing Furnaces for Aluminium Coils Single-Coil Lifting Hearth Furnace the flexible annealing concept The plant configuration designed by LOI Italimpianti consists of several furnace units that operate independently or large chamber furnaces for multiple coils, with a common charging system. The Single- Coil Lifting Hearth Furnaces are installed in a line and the charging machine moves under the furnaces. Coils are transferred to the individual chambers from a central charging and discharging station. 16 The benefits: short heating and cooling times no overheating less space requirement each coil is individually heat treated combining of batches is not needed on time annealing integrated fully automatic charging combination with warehouse system individual recording of the processing extendable line arrangement higher availability of the capacity Multi-Coil Furnace The configuration with Multi-Coil Furnaces combines several furnaces, which each consists of several of the same recirculation system as the Single- Coil furnace. Multiple coils can be heat treated at once. A charging machine serves charging and discharging of several furnaces and preparation stands. The benefits: short heating and cooling times no overheating of edges homogeneous annealing temperature

17 A N N E A L I N G F U R N A C E S F O R A L U M I N I U M F O I L Charging system of annealing furnace for aluminium foil 4. Multi-Chamber Furnace for aluminium foil 5. Cooling chamber Annealing Furnaces for Aluminium Foil Multi-Chamber Furnace Multi-Chamber Furnaces are used for heat treatment at aluminium foil production plants. These furnaces consist of up to five individual chambers, each of which is operated independently. Several coils are made up into a batch and positioned on a charging rack. This configuration is extremely versatile. The prepared batches from the rolling mill are stored on storage stations and then charged into the furnace chambers by a charging machine which runs transversely to the chambers. Otherwise, the operation of the furnace is fully automated. Each individual heat treatment operation is recorded and documented. 17

18 S P E C I A L S O L U T I O N S F O R T H E A E R O S P A C E I N D U S T R Y Special Solutions for the Aerospace Industry Approved quality The aerospace industry is the pioneer of technical development and there is no high-tech sector of industry that poses more stringent requirements in terms of safety, reproducibility and efficiency. Manufacturers and component suppliers are called upon to meet the highest possible quality standards. A process of steady innovation means that all the components and materials used must be continuously optimized. Aluminium is one of the most important materials for aircraft and spacecraft. LOI Italimpianti covers the entire range of melting, casting, heat treatment and recycling processes for aluminium and has a number of references in the aerospace industry. The advanced design of our furnaces, the highly reproducible material properties obtainable and the continuous documentation provided by our plants are among the features that have helped our customers meet the stringent approval requirements of manufacturers such as Boeing or Airbus. Overhead Furnace with mobile quench bath Aluminium components for the aerospace industry are generally artificially aged in an overhead furnace with underpinned mobile quenching bath. Using this design quench delay times of 7 sec. are achieved. Likewise a temperature accuracy of <± 3 K has to be run inside the packing space. The control system complies with the latest standards, e.g. AMS 2750D. 18

19 P R O C E S S E L E C T R O N I C S Fully Automated Control Systems Control systems allowing the fully automated operation of plants have become essential to ensure constant high product quality, ideal operation and maintenance conditions and efficient operation. LOI Italimpianti develops tailor-made control systems in-house to improve product quality and plant reliability and economics. The control systems developed include all the hardware and software required from switchgear to supervisory control systems. The LOI Italimpianti mechanical and electrical design and software development teams all work on the same site, ensuring efficient project handling and implementation. PLC systems Programmable logic controllers are used for the control of the central thermal process at a plant. Special attention is paid to modular design and to program documentation to ensure ease of service. Systems are supplemented by specially developed software packages. PLC applications human/machine interface open and closed-loop control signal processing alarm processing optimization of furnace use measured data acquisition Supervisory control systems Vertical integration of production data is an essential prerequisite for efficient production. Process visualization and SCADA (supervisory control and data acquisition) are therefore crucial aspects of our control systems. High-performance supervisory control systems based on standard PCs are recommended in order to optimize the control of a furnace system from economic and technical points of view. The supervisory control system is precisely tailored to the requirements of the furnace plant concerned, ensuring optimum user convenience and highly efficient operation. Systems perform the following functions: human/machine interface alarm and status signal reporting archiving in standard databases quality assurance process documentation batch logging link to server Electrical assembly work LOI Italimpianti designs and supplies switchgear assemblies to international standards as central components of turnkey electronic control and instrumentation systems. Projects are designed and engineered on advanced CAD workstations. Systems include: conventional, wired switchgear assemblies modular, rack-type motor control centres special designs to customers' requirements. Switchgear assemblies are produced in electrical workshops to the applicable DIN and EU standards as well as customers specifications. 19

20 LOI Thermprocess GmbH Tenova Iron & Steel Division Am Lichtbogen Essen Germany Phone Fax info@loi-italimpianti.de TECHINT GROUP Metacom 01/2013