PRECIA MOLEN innovation optimises aggregate process for LAFARGE
LAFARGE Group’s latest investment at Signes Quarry in France demonstrates the company’s strong commitment to an innovative strategy of plant automation and includes a fully automated loading and weighing system designed to meet the diverse needs of the quarry.
From the outset of this high profile project LAFARGE appointed their build partners with care commissioning leading weighing specialist PRECIA MOLEN to design and install a fully automated loading and weighing system including interfacing with LAFARGE Group’s Quartz back office business system.
A unique site within the Lafarge Group Situated south east of the Sainte Baume mountains, 47km from Marseille, Signes Quarry occupies a total area of 73 hectares, of which 33 hectares are exclusively dedicated to the extraction of limestone deposit which is processed to produce sand for either concrete batching plants or road products.
Prior to the installation of the new loading system the trucks were loaded manually using loading shovels and were required to return to the out weighbridge to collect their documentation, however, at peak times this created traffic congestion resulting in long queues and reduced truck throughput.
Key Criteria The new weighing and driver self-loading system had to meet four key criteria for LAFARGE:-
Minimal staffing levels for vehicle control, weighing and loading operations.
Full integration with the LAFARGE Quartz business system.
A robust and resilient system designed to ensure 24/7 operation.
Replace the normal out-loading procedures using a loading shovel.
A continuous automatic weighing/loading station Drivers arrive at the incoming weighbridge PRECIA MOLEN BI400 driver console and via a dialogue display they are asked to present their RFID card. The system validates whether the vehicle is an authorized user of the site, confirms the product to be loaded, directs the driver to one of the seven loading points and calculates the correct net weight to load from measured tare and authorised maximum gross weight (PTAC).
When the truck arrives at the self-loading driver console the driver is prompted to present the RFID card to confirm that the truck is at the correct loading point. Once loading commences real time integration is initiated between the PRECIA MOLEN BT conveyor scale and the plant PLC control to ensure safety interlocks are observed. The truck must drive slowly forward as the target weight is reached as indicated on the remote weight display. Once the loading cycle is complete and the truck has reached the target net weight final documentation is printed and the driver is directed to exit the site without the need to return to the exit weighbridge.
An original solution designed for bulk management The installation of the BT weighing conveyors within the site has provided significant benefits for LAFARGE as the loading stations represent a substantial saving on labour costs eliminating the need for seven weighbridges in excess of 24m in length.
The BT weighing conveyor comprises a fully weighed conveyor connected to the chassis by two articulations placed along the centre line supported at the opposite end by one or two load cells. These instruments are for accuracy class 0.5 +/- 0.25% commercial use and perform the same bulk management functions as a weighbridge or hopper scale. The BT is available with a 400mm wide belt, 1200mm in length up to a 1800mm wide belt, 5000mm in length and with a flow range up to 1,000tph.
Huge time savings and improved productivity By using the automatic system the whole cycle is completed in only 10 minutes compared to more than 40 minutes with manual loading. Since commissioning, nearly 90% of drivers now choose this mode of loading which reduces time on-site and improves productivity.
Another important benefit in terms of quality of service is that the certified weighing also delivers the expected quantity, avoiding the risk of over-loading or under-loading. Thierry Marchand – Project Leader at LAFARGE Aggregates South, commented, “This major project has required a comprehensive approach and could not have been successful without the technical expertise within LAFARGE and PRECIA MOLEN. It is easy for all to grasp the technical aspects of this type of loading and the significant benefits of streamlining operations on our site.”