Facts & Figures
|Application||Heavy metal removal|
|Location||Berre l'Etang, France|
|Average capacity||504 m3/day|
About the Crystactor for metal removal at Kraton (formerly Shell) in Berre, France
Shell Chimie (now Kraton Polymers) produces different elastomers. For a new product plant using a new technology, Shell was looking for a reliable technology to treat an aqueous diluted sulphuric acid stream high in nickel and aluminium. This stream originates from a product wash with concentrated sulphuric acid to remove spent catalyst. Based upon a system selection executed by Billiton, Shell selected the Crystalactor as most attractive treatment technology.
Important aspects in the decision process were:
- A high on-stream availability, since the treatment plant is fully integrated with the production plant without use of installed spares for critical equipment!
- Easy continuous operation with a minimum of supervision and operator input.
- Minimum total cost of operation and waste generation.
Pilot tests and design
To start with, Royal HaskoningDHV assessed the reliability and optimal design parameters in a pilot test in the company's own Technological Research Centre using synthetic wastewater. For a part of the tests, synthetic wastewater spiked with extremely high levels of various organics, inorganic and elastomer components was used to establish process robustness at none-normal operation conditions. Based on the outcome of the pilot tests, the process design, basic engineering were prepared. Also the turn-key construction (detail design, construction, commissioning & start-up) of the plant was performed.
The Crystalactor® is fully integrated with the production plant and reduces the nickel and aluminium level prior to biological treatment and discharge in lake Berre. For minimal footprint, the unit is constructed at multistage platforms. The design of the unit is based on maximum 21 m3/h. The waste water is warm (80 °C) and is an aqueous solution of sulphuric acid, saturated with various solvents and aromatics and 50-400 ppm Ni and 50-400 ppm Al.
The unit encompass primarily a pressure pellet reactor with a diameter of 3 m, reagent dosing equipment, two parallel anthracite filters (Ø 3000 mm), pellet & seed storage and filter backwash facilities. The filter washout is acidified and recycled to the pellet reactor.
Design of the unit and material selection is fully inline with the tough quality demands set by chemical environment in EXD classification area and the aggressive wastewater characteristics.The operation of the unit is fully automated and integrated in the site's process control system.
An effluent quality is obtained showing typical remaining nickel levels of around 0.1 ppm and 10 ppm aluminium. Both remaining levels are factors lower than the discharge limit at the end of the elastomer plant.Compact and dry NiAl(OH)3SO4-pellets are obtained as by-product which are transported to an external company for recuperation.