Innovations from Venti Oelde“From Waste to Profitable Material“

Recovery of cellulose fibers and superabsorbents improve profitability

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During the manufacture ofhygienic products, such asbaby diapers, feminine hy-giene products, incontinenceproducts, etc. there is a rejectpercentage of about 2 - 4which represents waste to be disposed of.

Reuse of this valuable mate-rial was not possible in eco-nomically relevant amountsuntil now because the sepa-ration of the cellulose fibersand the superabsorbent poly-mers (SAP), which form ahomogeneous compound inthe rejects and filter residue, proved extremely difficult. The available solutions withgrinding and tearing machi-nes, followed by screeningdid not prove particularly successful.

Hygienic product manufactu-rers had to content themsel-ves with an unsatisfactoryseparating and reclaiming efficiency of below 50 % so as at least to be able to usepart of the rejects. A parti-cularly promising concept,developed and successfullytested by the plant con-structor, Venti Oelde, for awell-know hygienic product manufacturer, has now en-tered the field.

Objectives

Liberating the cellulose fluff/fiber from the compact, wadding-type mass presen-ted the main problem. The profitability of the processmentioned in the introductionis without doubt questionable.Even worldwide researchaimed at optimizing a specialsystem with a high separationefficiency did not get past theinitial stages. The aim of aneffective solution must be the achievement of a definiteseparation of cellulose fluff/

From Waste to Profitable MaterialRecovery of cellulose fibers and superabsorbents improve profitability

Overall view of plant layout

Process flow diagram

SAP fluff blend

Legend:1 – Dosing unit2 – Dispersing station3 – VibroSAP4 – Fine screen for SAP5 – Separator for SAP

Exhaust air filter

Fluff toproduction

SAP to production

fibers and SAP with goodcleaning, so that the compo-nents can be returned in precisely metered amounts tothe process without impairingproduct quality.

Starting point

The first requirement for goodseparation is a complete libe-ration of the compacted rejectproduct, after mechanicalremoval of the plastic filmlining. Contrary to methodsused until now, liberation iseffected in the Vibro-SAPsystem (patent applied for)with air. After dry mechanicalseparation and pneumaticremoval from the dispersingstation, the cellulose fibersare separated in a vibrating-separating unit, using control-led airstreams, while thematerial is moved via vibra-ting decks arranged in stages. The reclaimed fibers passthrough a rotary airlock backinto the production process.The fine particles of thesuperabsorbent material

and any residual cellulosefibers, where superabsorbentsare possibly present, passthrough the perforated platesinto the collecting tanks of the decks. They are thenpneumatically conveyed via a further separating stage, the vibrating troughs, to anintermediate store. From here they reach a screeningprocess and then the counter-flow separator (process flowdiagram).

Finally after additional cleaning and separating thesuperabsorbent, freed from all residual cellulose fluff, is in a re-useable state and isstored until required for theproduction process.

The actual amount of wasteand reject product when using the Vibro-SAP system is extremely low. Efficient filters clean the dust-ladenprocess air and remove thedust produced during therecycling process.

Part of a production line

The process is controllableand can be used for inputmaterials with a high SAPconcentration (up to about 30 %) particularly effectivelyand, as a result of the goodseparation efficiency, veryprofitably.

Here are preliminary figuresas an aid to comprehension:● Material input volume

200 kg (consisting of cellulose fluff/fibers and superabsorbents as a compacted product)

● This contains weight percentages of fluff/fibers of 70 to 75 %; super-absorbents of 30 to 35 %.

● Recovered fluff volume with a purity of 93 to 95 % weight percentage

● Recovered SAP amount with a purity of more than 98 %

Planning criteria

Planning was based on thefollowing criteria:● Composition of the material,

with cellulose fluff/fiber and superabsorbent content

● Material input and feed● Throughput volume● Bulk weight● Ambient plant conditions

(temperature, relative air humidity)

● Further handling of the separated fluff/fibers

● Further handling of the SAP● Location (area, sound re-

quirements, air-conditioning)● Can any existing filter plants

be used? (The calculation basis is a flow volume of about 10,000 m3/h at a throughput of 200 kg/h).

● Information about integrationof the separating system [independent operation/in-tegration]

If these planning criteria areknown, the plant can be relatively easily integrated into existing production lines.

Ventilatorenfabrik Oelde GmbHP.O. Box 37 09D-59286 OeldeRobert-Schuman-Ring 21D-59302 OeldePhone: + 49 25 22 75-0Fax: + 49 25 22 75-2 50info@venti-oelde.dewww.venti-oelde.de

Vibrosap

Since there is a determinationto conserve raw materials andto minimize waste, this innova-tive project is being supportedby a Eurolife grant from theEuropean Union.

Advantages of the System

Reclaiming the reject productwhere it is produced, withdirect integration into the process, ensures maximumefficiency. The excellent se-paration of the components“fluff and superabsorbents”,means that there can be precise metering back to process with a high reclaimefficiency. Because the com-pacted material is liberated by using air dispersing tech-nology, the problematicalseparation using mechanicaltearing can be replaced by an economical and efficientmethod. Good operatingsafety and the elimination of fire hazards, caused byoverheating of tearing units,are further positive aspects of the new design. Individualadjusting of the various

stages to existing productionparameters permit a wide pro-duct range to be processedwithout problem. The multi-stage configuration meansthat there is direct optimiza-tion of cleaning efficiency. The compact plant (8 x 6 x 6 m = L x W x H) can be easily integrated into existing production lines. The enclosed system in-cludes noise reduction measures and, if required,can even be air-conditioned.

Vibro-SAP needs little main-tenance and is userfriendly as it does away with compli-cated tearing elements. Lowoperating costs as a result of high availability, the pro-ductivity of the plant and also low energy and maintenancecosts make the pay-backtime, when using the plant tofull capacity, about two years.

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