Per: Francois Dumortier (CMI Industry Metals), Johan PEERS (CMI INDUSTRY METALS), Michel BOYER (CMI INDUSTRY METALS)
Abstract:
TOday, there are good solutions extensively described by various OEMs & steel makers to optimize CAPEX & OPEX for small capacity Cold Rolling Mills (CRM) as well as for high capacity CRM.
A good solution for small capacity CRM is to start with a single stand reversing mill (up to 400 ktpy, depending on product mix), which can be expanded in the future into a twin stand mill (up to 900 ktpy, depending on product mix). The main drawbacks in conventional practice are the off-gauge length in single stand configuration and the stoppage time of the mill, which is quite long for erection of the second stand. For higher productions CRM, it is recommended to go directly for a new PLTCM, with a high CAPEX which is common practice.
But…. what is in between? How to start with limited output and limited CAPEX but without jeopardizing final ultimate expansion goal (1.2 to 2 mtpy) for which PLTCM is the best technico-economical choice?
Today there are no solution, and CMI has therefore developed an integrated solution which will limit the CAPEX in the first phase, without penalizing the future by an easy and economically viable expansion up to a PLTCM, without a long production stoppage.
The solution consists to install first a twin stand mill, which can be expanded into a tandem mill by a smart layout of the line. Therefore it’s possible to have a first project phase up to 900 ktpy (for which single stand can be installed first, then second stand later), and an second phase with a conversion into PLTCM for a production from 1.2 to 2mtpy, depending on the market evolution and financial capacities.
Therefore CMI has developed a smart new layout in reversing phase combined with totally new rolling strategy to optimize productivity and limit off-gauge compared to conventional solutions (patents pending).
In addition the layout enables an easy conversion to tandem mill without high over investment compared to conventional purchase of PLTCM from the beginning. Long stoppage times for capacity extension which could be detrimental to this approach phase by phase is also avoided.
Technical and process description of the new layouts and rolling strategies together with CAPEX & OPEX description of the phasing are described in the paper.
