We have supplied our highest accuracy ever ‘Spirofil’ Bulk Bag Filler to the world’s first industrial scale Nanotube manufacturing facility in Sambreville, Belgium.

Nanocyl S.A. was established in 2002 with the goal of becoming the leading global manufacturer of specialty and industrial Carbon Nanotubes. Nanocyl is one of the key players in its industry with a production capacity of over 40 tonnes/year. Further capacity increase is planned to meet the ever growing customer demand. Nanocyl employs 40 people at its production facility in Sambreville, Belgium and at offices in the United States.

Customer requirements

Nanocyl produces the full field of Carbon Nanotubes, ranging from single-walled nanotubes, to double-walled and multi-walled versions. The preferred manufacturing technology is catalytic carbon vapour deposition (CCVD), which is currently best adapted to large-scale production. Nanocyl commercialises its products in the form of powders, pellets, liquid dispersions and films.

Nanotubes are an emerging technology. They are costly to manufacture and therefore command a high price in the market place. Whether sold by the Bulk Bag full or in 2kg packs, the high accuracy filling of the containers in which they are sold is essential. Nanocyl required an extremely high accuracy filling machine for their bulk bags.

Spiroflow solutions

Traditionally, for most industrial applications, Spiroflow offer Bulk Bag Fillers with weighing platforms using weigh-scales or load-cells, typically achieving accuracies of +/- 1 kg. To meet the Nanocyl weighing accuracy requirement of +/- 20 grammes, Spiroflow engineers decided to adopt the ‘hang-weighing’ principle on this occasion and with total success. This meant that the highly sensitive load cells could be mounted high up in the structure of the filler out of harm’s way.

Not only does the ‘Spirofil’ Bulk Bag Filler accurately weigh the contents into the Bulk Bags - it is so accurate that it also used to fill 2 kg bags too!

Bulk bag filling takes place under a nitrogen blanket. A folded, flat bag is rigged onto the Bulk Bag Filler and then the bag is inflated with nitrogen. Given that ambient air is 78% nitrogen (by volume), the nitrogen displaced as bulk bags are filled is vented harmlessly, through a special filter unit, into the atmosphere.

During filling, the base of the Bulk Bag Filler intermittently rises to vibrate the bag - it then lowers to allow weighing to continue. The bag is given a final vibration once the target weight has been achieved and recorded. This vibration is critical to ensure that the contents of each bag are consolidated to render the bags in a stable and safe condition for handling and storage.

The controls were designed and manufactured by Spiroflow who have a dedicated team of electrical engineers and technicians. The heart of the control box is a high accuracy weighing instrument that receives signals from the high-sensitivity, high-accuracy load cells. These support the bag hanging frame complete with its quick release bag loop hooks. The weighing instrument is connected to a printer so that batch records can be made and kept.

The ‘Spirofil’ Bulk Bag Filler has been in operation since May 2007 and according to Nanocyl, “It is an excellent machine, tailor-made for us to our exact specification by Spiroflow and it has performed to our entire satisfaction. Indeed, we are very pleased with it.”

What is a Carbon Nanotube?

A “Carbon Nanotube" is a tube-shaped material, made of carbon, that has a diameter measuring on the nanometre scale. A nanometre is one one-billionth of a metre, or about one ten-thousandth of the thickness of a human hair. The graphite layer appears somewhat like a rolled-up chicken wire with a continuous unbroken hexagonal mesh and carbon molecules at the apexes of the hexagons. Carbon Nanotubes have many structures, differing in length, thickness, type of helicity, and number of layers. Although they are formed from essentially the same graphite sheet, their electrical characteristics differ depending on these variations, acting either as metals or semiconductors. Carbon Nanotubes typically have a diameter ranging from below 1 nm up to 50 nm. Their length is typically several microns but recent progresses have made them much longer in the centimetre range.

What are the properties of a Carbon Nanotube?

The measurement on individual tubes of their intrinsic mechanical and transport properties position them as ultimate carbon fibres. The best Carbon Nanotubes show a unique combination of stiffness, strength and tenacity compared to other fibre materials which usually lack of one of these properties. Intrinsic thermal and electrical conductivity is also very high and comparable to other conductive materials.