French term (edited): "extracteur à cadre"

L'extracteur à cadre tire le produit à une extrémité de la trémie et est repris par une vis et un convoyeur à bande
http://www.lessinesindustries.be/fr/news/nouveaux-produits/

Silo de boue avec extracteur à cadre et vis suivant descriptif client.
http://www.franceenvironnement.com/produit/silos_1.html

La technique de silos PM
La technique de silos avec le « principe des cadres coulissants » est conçue particulièrement pour des boues d’épuration déshydratées. [ ... ]
Une caractéristique essentielle de la conception est la construction peu encombrante, la tige de piston du cadre coulissant étant logée dans le tunnel au fondu du silo [ ... ]
Systèmes d’extracteur à cadre rectangulaire/circulaire
Selon l’application, les installations peuvent être livrées soit en système PDL (EXTRACTEUR À CADRE RECTANGULAIRE), soit en système PDF (EXTRACTEUR À CADRE CIRCULAIRE). Le système PDL avec plusieurs CADRES COULISSANTS parallèles convient particulièrement en cas de silos de réception larges et longs. Ceci garantit un transfert favorable de la puissance et augmente la disponibilité du système grâce à la redondance.
http://www.pumax.be/pompe_industrielle_fr-34.pdf

The Putzmeister silo has been designed and engineered especially for highly dewatered and highly viscous sludges. The discharge of the material from the silo bottom is accomplished by a reciprocating sliding frame, which directs the sludge to a twin-screw auger which doubles as the charging screw for a Putzmeister high density solids pump or
to other discharging arrangments for truck loading. [ ... ]
Additional space is saved by locating the sliding frame piston rod in the silo floor tunnel. [ ... ]
The application-specific sliding frames can be supplied as LADDER SYSTEM (PDL) and as CYLINDRICAL SILO DISCHARGE SYSTEM (PDF). The LADDER SYSTEM with several parallel SLIDING FRAMES is ideal for wide and long receiving bunkers. This guarantees maximum efficiency and increases system availability
http://www.putzmeister.de/pm_online/data/IP_2123_GB.pdf

for storage and dispensing on non-free flowing materials such as biomass and sludge cake using Saxlund SLIDING FRAME Technology. Flat Bottomed Silos ...
www.saxlund.co.uk/index.php/sliding-frames.html

The SLIDING FRAME is an "original"discharger design by Saxlund for flat bottom circular silos. It is designed to function with non free flowing and difficult materials such as dewatered sludge cakes. The flat silo floor concept gives many advantages such as the maximum possible sized discharge openings. The SLIDING FRAME DISCHARGER creates "mass flow" within the silo even with these difficult materials. The client can be sure of achieving accurate discharge and metering of the stored material on demand no matter what application.


Function

The Sliding Frame is driven by a hydraulic system that makes the Frame reciprocate slowly across the silo flat floor. As it does so it digs the material from storage and at the same time delivers it in to a screw or screws situated beneath the silo floor. The screw or screws are thus maintained completely full and are therefore able to meter the material at the desired rate into the process etc.
[there's even a video, complete with charming corporate-video musical background and commentary in British-accented English from a Swedish-accented Swede]
http://www.saxlund.se/eng/glid.html