Siegwerk Druckfarben AG & Co. KGaA, Siegburg, tested the Ecobulk with impeller (disposable stirrer) from Schütz Co. KGaA, Selters, with a highly viscous medium. The solution, which eliminates the risk of contamination, impressed with top performance and the best stirring results with minimum stirring time.
Highly viscous products such as Paints and varnishes place special demands on packaging across the entire supply chain that go far beyond good residual emptying. In order to enable removal and optimum processability, these products must be frequently stirred be made. This process harbours an enormous risk with conventional procedures. Contamination risk: The packaging may have to be opened several times and agitators inserted and removed again. External contamination of the packaging can hardly be avoided. Even more serious is the fact that foreign particles are often introduced into the product. In addition, using the same agitator for different products is extremely risky. Insufficient cleaning or overlooked product adhesions can quickly lead to considerable damage in the subsequent application.
Impeller on board
In autumn 2015, Schütz presented the FachPack presents a revolutionary packaging concept for high-viscosity fillers that offers decisive process advantages: Ecobulks with disposable stirrer can remain closed throughout the entire supply chain from filling to removal and still enable convenient and effective stirring of the filling products. This eliminates the need for conventional stirrers and significantly reduces the risk of contamination. The system is available for all 1,000-litre and 1,250-litre Ecobulk types with DN 150 and DN 225 filling openings. A long-standing Schütz customer has now subjected the impeller to an intensive practical test: Siegwerk Druckfarben has been using various IBC models for transport and storage for over ten years.
Dream team for structured viscous materials
Siegwerk was looking for more efficient solutions, especially with regard to the processing of viscous products. „At a trade fair, we became aware of the special design of the Ecobulk HX and the new impeller also developed by Schütz,“ explains Jörg Kortholt, Production Supervisor in the Packaging Inks division at Siegwerk. The Disposable stirrer is connected to the screw cap of the IBC and is inserted into the filling opening at the factory.
Only for filling is the system either briefly removed or remains permanently installed, depending on the filling process and container configuration. A conventional drive system can be connected for stirring without any major modifications or conversions. To do this, the drive is placed over the screw cap and fixed to the grid cage with a frame. The drive shaft engages positively through the opening of the stopper into the hub of the impeller, which transmits the rotation to the inside of the container. „The combination of both products should simplify the handling of this structurally viscous medium,“ surmises Jörg Kortholt. In order to determine the advantages of this closed packaging system in practice, the two companies jointly initiated a stirring test with a product from Siegburg that was critical in this respect.
Highly structured viscous filling material tested
The experts first filled out a HX-Container of Schütz with a total of 650 kg of highly viscous intermediate product. The approximately two-day storage (resting phase) led to a significant change in the consistency of the material with a considerable increase in the Viscosity. The viscosity was over 10,000 mPas, which makes it impossible to remove through the outlet fitting. However, if such a product starts to move, its viscosity can drop to around 2,000 mPas. This behaviour is referred to as thixotropic.
The contactor impeller was now used to stir the medium: it rotated 140 times per minute. After ten minutes of stirring, the experimenter opened the valve of the container again. Within 30 seconds, around 60 kg was already flowing out of the opening. After a stirring time of 30 minutes, the filling material ran out in a thin liquid at 186 kg per minute. However, the surface of the medium in the container was still very viscous at this point.
Further removal caused the fill level in the container to drop to such an extent that after a short time the surface could also be stirred and also liquefied. When the fill level had dropped to the upper edge of the impeller blades, the speed was reduced. This allows the position of the moving blades to be adjusted to the remaining volume in the container in order to continue to achieve an optimum stirring result.
„Continuing the mixing process with a residual quantity of 80 kg or more until it was almost completely emptied also produced convincing results. After the last drops had flowed out, a residue of five kilograms collected on the floor a short time later. „This residue resulted from the trailing wall adhesions. As the conical shape of the HX inner container supports this process, further emptying could also be carried out quickly,“ explains Heinz-Peter Martin, Sales Manager IBC at Schütz.
Down to the last drop
According to the industry association (VdL), the total annual production of the medium-sized paint and printing ink industry in Germany is 2.5 million tonnes. Looking at this volume, it immediately becomes clear that unused quantities in packaging inevitably lead to economic losses, as the high-quality product components remaining in the container can no longer be reused. In addition, the Ecobulk HX The stainless steel IBCs offer numerous advantages in direct comparison to stainless steel systems, which were previously used almost exclusively in this area of application: In addition to lower acquisition costs, there are no further expenses, for example for cleaning, repairs, logistics for recirculation and the legally required interim inspections for stainless steel IBCs. Another cost factor is the time saved when using the impeller: the faster the product is liquefied by stirring, the faster it can be processed. [infotext]
Test result
Also a Highly thixotropic, structurally viscous product like the test material can therefore be liquefied after a short stirring time with the contactor impeller in the lower area and thus enables free discharge via the container tap with optimum residual emptying.
For the entire quantity of 650 kg, the impeller required a total of around 35 minutes with an energy input of 1.8 kilowatts at 200 revolutions per minute. When stirring in the Ecobulk HX, its geometry with an inclined base, closed, dimensionally stable support cushion, optimised outlet and low-lying fitting ensures optimum residual emptying of the viscous test medium.
Contamination-free stirring
IBCs with impellers form a closed packaging system. After filling, the IBC can remain permanently closed and sealed throughout the entire supply chain until the product is used, even during the stirring process.
By using the impeller as a disposable system, the risk of contamination from residual filling material adhering to the agitator is completely eliminated, thus minimising the risk of contamination. Process reliability increased many times over. Time-consuming cleaning and the associated costs are also eliminated. The entire component is made entirely of HDPE - This means that the contents do not come into contact with steel later on, another plus point in terms of product purity. Empty IBCs, including the impeller, are collected by the Schütz Ticket Service, and the bladder and impeller are processed into HDPE recyclate as part of the reconditioning process. The recovered material is reused in Schütz products in an environmentally friendly way, for example in the form of plastic pallets.
