Insulation scrap recycled into value-added product secures new customers...
Stone wool was first produced commercially from slag in the 1800s but it took a collaboration between an insulation manufacturer and PremierTech Chronos to figure out how to make this material from discarded scrap.
Finding cost-effective ways to produce stone wool is a strategic way to profit from the growing market for this and other types of organic insulation. As reported in 2012 at the 7th Global Insulation Conference & Exhibiton, organic insulation commands a 68% market share of the Korean market. In the EU, the insulation industry is predicted to increase in size by approximately 30% over the next eight years. In addition, the stone wool market in Russia is expected to double by 2016.
One of the world's leading producers of mineral wool is Knauf Insulation, which has a manufacturing facility in Škofja Loka, Slovenia. It is part of the Knauf Group, a multinational manufacturer of building materials and construction systems that was founded in 1932 to process gypsum and is headquartered in Germany. Knauf Insulation is the fastest growing producer of insulation worldwide, with annual sales that exceed US$1.5bn and manufacturing facilities in the US, UK, Russia and Europe, including the plant at Škofja Loka.
The goal
"Knauf wanted to launch a new product on the market," recalls Patrice Maltais, Operations Director at PremierTech Chronos. The product was to be an additive for concrete used in high-temperature applications such as coating for the interior of a chimney.
Finding a way to access the lucrative and growing chimney liner industry, valued in the EU in 2011 at US$1.06bn/yr, according to information presented at the 2011 International Conference on Advanced Materials Engineering, is driven by the fact that modern fuel heating equipment operates more efficiently than in previous generations and generates flue temperatures that can reach 600°C. Such temperatures cannot be handled safely by conventional chimney liners and have the potential to cause fires. There is hence a need for an additive to increase cement chimney liners' heat tolerance.
Base material for the new additive could have come from stone wool that the plant was already producing. Instead, Knauf decided to create base material by recycling scrap material left over from a different process at the plant thereby saving money, reducing waste and upholding the company's commitment to sustainability. PremierTech Chronos was chosen as the partner in this undertaking based on "positive experiences with their equipment at other Knauf Insulation plants," explains Igor Jelenc, Project Engineer at the plant.
Equipment
In order to determine the equipment that would be best suited to this undertaking, preliminary tests were conducted on material under the scrutiny of Knauf Insulation representatives, Jonathan Leroux (PremierTech Chronos' Project Manager) and Marc Péray (PremierTech Chronos' Sales Director). Testing included fabricating and assessing different sizes of grates for the mill that was needed to degrade scrap material before it re-entered production.
The equipment that was selected comprises a line that is fully automated from mill infeed conveyor to stretch wrapper. Specifically this consists of a pre-shredder, mill infeed conveyor, a HML 1500 mill, baler infeed conveyor, a HVS-140-E Baler, a HAT-150-E Bag placer/sealer, a bale conveyor, a model AR-200 robotic palletising unit and a model RA13-11 rotary arm stretch wrapper.
The pre-shredder, which is equipped with a hydraulic lifting system to avoid the risk of employee injury, reduces the scrap material to a size that allows it to enter the mill. Pre-shredded scrap proceeds to the mill inlet along a 1500mm-wide mill infeed conveyor, which is completely enclosed to prevent fugitive dust.
The HML Series mill, often used by bulk handling operations that need to shred insulation that is loose or in the form of batting, is used in Knauf's application to further reduce the size of the pre-shredded scrap material. Material is cut by a set of highly wear-resistant Hardox 450 rotary knives that push it through a stationary grate. The design of the grate and knives, combined with a relatively slow rotating speed, cuts the material instead of crushing it.
This is important in order to preserve the structure of the air spaces within stone wool's intertwined fibres, since those spaces contribute to the base material's thermal insulating properties. "Crushing can cause the material to become too compact," explains Jelenc.
The correctly-sized base material is then conveyed to the baler and packaged in bags made of tubular film. The model HAT-150-E bag placer/sealer automatically places bags made from tubular film onto a radial baler that has its spout's larger face along the vertical axis.
Tubular film allows Knauf to significantly reduce packaging costs because this film costs less than the corresponding packaging volume of pre-made bags. Additional savings accrue because tubular film decreases downtime and labour created by pre-made bags' inherent risks of sticking together or inaccurate loading in the bag magazine. Uptime is further enhanced because the system permits a replacement roll of film to be loaded during operation, which supports the line's ability to produce up to three bales per minute (bpm).
The model HVS-140-E radial baler, which can handle ceramic fibre, fibreglass and other types of insulation in addition to stone wool, is designed to compress the bale along its width. This produces bales that are easier to palletise because they have a flat face. Because Knauf Insulation's new material is very abrasive, the baler was customised with an interior surface that is highly wear resistant and can be replaced.
Bales are transferred by the model AR-200 series robotic palletiser, the compact size of which is well-suited to the constrained space at the Knauf facility. Pallets are then secured by a model RA13-11 rotary arm stretch wrapper that is designed to handle lightweight loads and high production rates.
Challenges
Two challenges were detected during the start-up phase of this project, but PremierTech Chronos designed and fabricated customised equipment to overcome them. "In the first case the challenge was the small amount of available space in the plant. The second challenge was the packing unit," recalls Maltais. "In each case, the challenge was solved."
Due to constrained plant space, "We had to design a special low-profile weighing hopper on the baler in order to get the equipment to fit under their roof," explains Maltais. "The plant space was quite small in square footage and in height. In order to fit in the space, we had to design a special mill infeed conveyor that had a greater degree of incline."
Because the mill infeed conveyor was steeply inclined, PremierTech Chronos engineers fitted it with a conveyor belt that had a special surface which provided extra grip. This helped material to 'climb the conveyor.' Maltais explains that, "By doing that the belt became more difficult to clean because material had a tendency to accumulate at the base of the conveyor. So, we designed a special scraper on the belt and integrated some extra de-dusting ports."
"The PT equipment is completely closed and doesn't cause any dust for the surroundings," adds Jelenc.
One challenge was solved but one remained. The problem with the packing unit arose because of the material's very low weight, which had been determined by preliminary testing to be optimal for its intended use. However, its low weight meant that the bales that were produced were too soft to be securely held by the transfer robot during the packing process. As a result, says Maltais, "The gripper ... would sometimes drop a bale. We had to redesign the gripper to include a clamping mechanism to make it 100% reliable."
In addition, he adds, to compensate for the bales' softness and compressibility, "We had to over-compress the bale a little bit along its longest side to make the face of the bale more stable and less likely to fall. In order to achieve that, we had to make some hydraulic and software modifications."
Fast start-up
Despite the inevitable start-up challenges, the new line was installed within its planned four-week time frame and was operating at full capacity as soon as installation was complete in June 2012. The Knauf employee assigned responsibility for the line had accompanied the Premier Tech Chronos representative during installation, enabling a very smooth transfer. "He was able to operate the line as soon as the installation was finished," says Jelenc.
Payoff
"By entering the new market we were able to gain new clients," continues Jelenc, who estimates it will take five years to recover the cost of the new equipment."There is the possibility to install an additional bagger at our location. We have opened new areas where (PremierTech Chronos) equipment can be used, so additional applications may appear."
