The first project, undertaken by Metallurgica Abruzzese, allowed to demonstrate the feasibility of a new environmentally friendly system for the treatment of rods and their derivatives, which lowers the environmental impact of the stages of drawing, cleaning and heat treatment before the galvanizing phase.
More in detail, the working cycle was transformed through the introduction of the following innovations:
- mechanical treatment of dry descaling with zero environmental impact;
- drawing system in polycrystalline diamond, lubricated by recoverable soaps;
- heat treatment in a controlled atmosphere with low energy consumption, capable of eliminating the pickling in acid step.
Environmentally friendly drawing process of metallic rods. The new environmentally friendly drawing system for the treatment of the wire rods and their derivatives, which allows to reduce the environmental impact of the drawing and cleaning phases prior to the galvanizing of the metal wires.
LIFE is the instrument through which European Union contributes to finance projects directed to environmental respect in countries of the Union and in other Countries of Mediterranean, Baltic, Middle and Eastern Europe, that agree to the programme. Through LIFE Programme, European Union Commission directs to provide incentives for sustainable development politics, based on efficient, safe and eco-compatible use of resources. Therefore, with LIFE, the Union supports the realization of innovative actions which give an effective and innovative answer to the main environmental problems such as considered in the whole Europe, The General Environmental Direction, a specific structure of the Commission, examines advanced proposals and approves those considered mostly valid, watches over the correct use of resources and controls the realization of the programme and of actions scheduled in the project.
For further information about LIFE 04 ENV/IT/000598 it is possible to consult Life Programme web site
Among thematic sectors determined by LIFE – Nature, Third Countries and Environment – the last is the one which produces the greatest impact on concerns system. Specific aim of LIFE – Environment is to foster implementation, on a large scale, of results reached by R&S (technological research and development) supporting, through the co financing of demonstrative projects, the development of techniques and innovative methods finalised to environmental respect. Spreading and transferability of experiences are some of the most indispensable requirements for the approval and realization of LIFE – Environment projects.
LIFE rules determine five fields of intervention:
- Territorial planning and improvement;
- Management of waters;
- Reduction of environmental impact caused by business activities;
- Management of waste;
- Reduction of environmental impact of products through an integrated production policy.
CAVATORTA “E.S.D.” PROJECT
The project set up by CAVATORTA Group and approved by E.U. Commission (LIFE 04 ENV/IT/000598) draws premises from Directive 96/61/CE dated 24.09.96 which regulates control and prevention of pollution in industrial sector. It was conceived in CAVATORTA Group’s laboratory and aims to a complete revisitation of present production cycles, and is strongly tuned to environmental respect, it should be fulfilled over three years.
At the heart of the new projectual solution, CAVATORTA sets the new Eco Sustainable Drawing called “E.S.D.” for metal wire rods and by-products treatment, which consists in reduction of waste coming from the present chemical pickling phase which comes before metal wires galvanizing process, and in gradual replacement of traditional drawing lubricants with new and less polluting substances.
To reduce environmental impact of metal wire rods during transformation cycle.
Planning and implementation of a new dry mechanical descaling process, with a low environmental impact, which will limit the present chemical pickling processes, emission and consequent production of waste.
Planning and implementation of a new metal wire rod drawing system.
Planning and implementation of a new metal wire heat treatment that implements the present heating process in line furnace.
1. ACTIVITY: NEW WIRE ROD DESCALING AND CLEANING SYSTEM EXPECTATION
The activity consists of the set up of a new cleaning process for preventive treatment of wire rod suited to remove any surface oxidation.
Aim of the activity is the realization of an innovative system, based on a dry physical treatment process, for deoxidization, cleaning and purification of wire rod surface.
Expected products of the activity: the realization of prototype equipment to be inserted in the company production line.
Expected results of the activity: wire rod, continuously produced, should be absolutely free from oxidation (maximum admitted tolerance 3%).
STATUS: ended with success.
WHAT HAS BEEN DONE
With this activity, initially, a first prototype of descaler in full-size scale has been realized and, in a experimental way, it applies studied principles which is the heart of the present project. Indeed, the first part of activity has been dedicated to a projected set up of three descaling actions to apply simultaneously, so as to achieve wire rod cleaning within foreseen terms. It concerns:
- First action of coarse crumbling realized by a block of opposed rollers;
- Second action of fine cleaning realized through a in-line transition press;
- Third action of finishing realized by a subassembly of rollers provided with compressed-air
Successfully concluded experimental phase of prototype, suitable parameters of dimensioning for the realization of the overall pilot equipment has been obtained. Compared to the first prototype, the descaler has implemented regulation system of the three groups of rollers through a touch-screen terminal. Besides, they can rotate on wire axis of 360Â°, independently one from the other, depending on the different carbon content in processing wire. Moreover, a wire cleaning system with compressed air has been set up.
This important testing phase gave the possibility to finish the task with excellent results, pointing out better results than expectations.
New wire rod descaling and cleaning system has been realized, object of the present task.
Tests carried out on final descaling equipment gave excellent results, pointing out even better results than expectations:
- superior working order compared to traditional systems (+60-65% ca.);
- less quantity of residual surface oxides on steel wire at exit of the plant (< 1% compared to awaited < 3%);
Respect of production capacity (1.000 kg/hr, that is 5.400 m/h of original wire rod diam. 5,5 mm).
on the left: cross-section, surface scale particular (500x)
on the right: test with first prototype – residual surface scale particular (1000x)
on the left: wire rod cross-section before descaling process (1000x)
on the right: test with traditional method – residual surface scale particular (1000x)
on the left: test with descaler residual surface scale particular (1000x)
on the right: general view of new descaling system
on the left: single rollers bench view, with relevant graduated scale of regulation
on the right: particular of action extent of middle roller which defines deformation
on the left: overall view of press and of bellow after descaling rollers
on the right: particular view of press after descaling rollers
on the left: particular view of bellow after descaling rollers
2. ACTIVITY: NEW SYSTEM FOR COLD DRAWING OF WIRE ROD PLAN
The activity consists in the creation of a new system for cold drawing of wire rod.
The objective of this activity is to create a new system for cold drawing, which can operate using raw material treated with the new de-flaking machine (see above) and which returns the product drawn in the dimensions required, using an environmentally friendly process.
Planned products for the activity: creation of a preliminary prototype and the new system for cold drawing of wire rod.
Planned results of the activity: creation of a drawing cycle; wire drawn in the dimensions requested, without oxidation or superficial defects.
STATUS: ended with success.
WHAT HAS BEEN DONE
Preliminary studies and the planning regarding the geometry of the polycrystalline diamond threading dies to be used in the various steps of the drawing process and the operations to be undertaken on the draw bench machine have been completed to adapt them to the new drawing system;
Crystalline diamond threading dies have been installed on a traditional machine drawing bench and the necessary tests have been made for development of the cold drawing system; Further modifications have been made to the draw bench machine in order to further decrease the use of lubricants.
RESULTS OF THE ACTIVITY
The development of the experimentation has involved the creation and implementation of a new threading die box, on the last step of drawing, able to house the new system. Currently, the draw bench machine is equipped with:
- a new system of de-flaking;
- a new system with crystalline diamond threading dies;
- a new threading die box on the last step.
Analysis undertaken on samples of wire gathered during testing have highlighted the presence of a residual lubrication value of ~ 0.3 g/m2, over 90% less than that found in the traditional drawing system. The objective defined in the drastic decrease in use of lubrication can be said to have substantially been reached without any compromise for the superficial finishing of the intermediate material. We were able to use the wire thus obtained in the development of the following activity.
on the left: die box detail of first block of drawing machine
on the right: die/lubricant detail of first block of drawing machine
on the left: inside of drawing machine
on the right: laser system for thickness control
on the left: new double-die box, applied on last drawing block
on the right: new double-die box detail
on the left: cooling plant for drawing line
on the right: wire coil produced with new process (brighter, on the left) and wire coil produced with
traditional system (duller, on the right)
3. ACTIVITY: CHANGES TO THE FIRING SYSTEMS FOR INTERMEDIATE MATERIAL PLAN
The activity consists in the perfection of a new process for firing intermediate material in a controlled atmosphere in order to eliminate the possibility of oxidation of the wire rod in transit.
The objective of the activity is to modify firing systems for intermediate material in order to arrive at a process in three consecutive stages (heating, cooling, expulsion) in a controlled atmosphere.
Products expected from the activity: creation of prototypes of changes to be made; modified firing system;
Results expected from the activity: elimination of the pickling stage; filament fired in the dimensions required, without superficial defects.
STATUS: ended with success
WHAT HAS BEEN DONE
Preliminary studies have been activated (systematic analysis of materials and products in manufacture, studies and research on the machinery and technology available) prior to commencement of the actual activity;
In a subsequent stage, the Firm created an internal prototype controlled atmosphere room, which has allowed creation of comparative experimental tests, the results of which have been encouraging. In any event, the prototype created did not allow the creation of profound experimental tests, in particular for the low production rhythm. Therefore, it became necessary to commission the planning of modifications to be made to the firing systems for intermediate material;
Thus, it has been possible to create a new prototype room which, in various industrial tests, has allowed the filament to be kept in an inert nitrogen atmosphere during all thermal treatments, such as re-firing and cooling.
The following activities required the creation of a second prototype, still not yet finalised.
Various industrial tests were performed in different operational and functional conditions and samples were subjected to a metallographic microscopic analysis.
The results of the performed tests showed that:
- the products treated with the second prototype are almost free of surface oxidations (reduced by 95-98%);
- the detected oxidations can be seen only through metallographic microscope; this allows to skip the pickling phase for these products and certifies the positive results of the studies and tests carried out.
The performed galvanization tests were successful: the galvanization appears to be uniform and smooth on the entire surface of the wire, free of areas with no adherence of the zinc onto the steel sub-layer.
The analyses at the electronic microscope were also successful; through the tests carried out, it was possible to obtain the necessary data and parameters to configure the new curing system in a definitive manner.
Currently, the final design of the new curing system has been completed.
The tests and experiments carried out with the new prototype confirmed the total elimination of oxidation, beyond the project’s objectives (which were foreseeing 80-95% reduction); this allowed
also to perform galvanization tests on the wire drawn with the second prototype, without subjecting
it to the prior pickling phase in hydrochloric acid, and results were obtained in line with ordinary
RESULTS OF THE ACTIVITIES
The results of the activity confirmed the attainment of objectives, since a drawn wire was obtained, free of surface oxides that – once subjected to the galvanization phase – supplied a product in line with corporate standards, with no need to resort to the prior pickling phase.
on the left: detail of wire coming out from prototype of annealing furnace in controlled atmosphere
on the right: prototype of annealing furnace in controlled atmosphere – superior part
on the left: prototype of heat treatment system (general view of the covering)
on the right: prototype of heat treatment system (general view of the covering)
on the left: prototype of heat treatment system (general view of the structure)
on the right: prototype of heat treatment system (wire entrance detail)
on the left: prototype of heat treatment system (wire exit detail)
on the left: pay-off system of new prototype
4. ASSEMBLING OF THE NEW PRODUCTION LINE
The activity consists in the assembling of the new manufacturing and treatment line of metallic rods for the production of drawn wires, for the curing of the wire in a controlled environment and following galvanization.
STATUS: ended with success.
on the left: cooling system of drawing machine
on the left: cooling tank of drawing line
on the right: cooling tank of drawing line
on the left: assembly of production plant of new galvanized wire
on the left: assembly of production plant of new galvanized wire
on the right: assembly of production plant of new galvanized wire
Steel treatment consisting in the elimination of oxides formed on wire substratum during annealing process. It is of chemical type. Steel is dipped in a bath of acid which detaches and melts oxides formed during previous working processes. It contributes to a better cleaning of steel wire substratum and, therefore, it is ideal for a perfect application of a surface, protective coating (ex.: zinc).
Descaling (or decalaminization)
A process consisting in the elimination of rolling scales present on wire rod surface.
Instrument used to reduce wire rod section to obtain steel wire with required diameter. Dies can be used with metallic carbides or with polycrystalline diamond (=PCD).
Substance added to eliminate die wear through reduction of friction produced between die and mwire. A good wire lubrication assures a better quality of product, a higher drawing speed and, with equal working speed, a reduction of engine power necessary to draw.
Particular heat treatment for steel wire obtained from wire rod drawing. It has the function to restore hardened structure of drawn wire.
It consists in the reduction of wire rod section to obtain steel wire with a required diameter, ready for further working processes (annealing, galvanizing, etc.).
Semi finished product, steel rod with circular section, hot rolled, used for production of drawn wire, nails, etc.
Process which coats basic steel wire with a surface protective coating of zinc.