Dust-free Pastillation of Nickel Catalyst Has Brought Technical, Commercial, And Safety Benefits

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Quality Benefits of Rotoform Pastillation

For Monarch, the initial appeal of Rotoform pastillation lay in the lower friability of this product form; a pastille is inherently more stable than a flake and its uniform, hemispherical shape has no corners or edges to break off. The shape of the pastilles also means easier product flow for bagging, transportation, storage, metering, and blending.

The solidification system itself is based around a heated, cylindrical stator and a perforated shell that rotates concentrically around the stator. This mechanism — the Rotoform — deposits droplets of molten catalyst material, at a temperature of 80–90°C, across the full width of a continuously-running steel belt. The circumferential speed of the Rotoform is synchronized with the speed of the belt, ensuring that the drops are deposited in a consistent shape and size.

Cold water sprayed onto the underside of the steel belt provides the cooling needed to convert the molten droplets into solid pastilles. This indirect heat transfer ensures that there is no risk of contamination in either direction: the quality of the catalyst is maintained since there is no contact with the cooling water, while the water can be reused within the system without any need for purification.

While the performance of the Rotoform and the quality of the formed pastilles were key factors in Monarch’s decision, equally important was Sandvik’s shared belief in the value of partnership.

“The expertise, support and advice of our local team was critical in reassuring them that we were there for the long term,” explains Sandvik’s Kumar Swamy. “You establish the foundations of a relationship in these early days but you only earn complete trust and confidence over a period of years.”

Stage two of Monarch’s expansion plans gave Sandvik the opportunity to do just that.

Major Expansion Program

In 2005, the company embarked on a two-year program to build one of the world’s largest catalyst plants, with the goal of increasing capacity by around 250 percent. Another key objective was to be able to handle a wider range of catalyst grades, with melt viscosities ranging from 20 to 1,000 mPa·s.

With the decision already taken that the new facility would be based around a second Rotoform pastillation line, Monarch and Sandvik started work on a series of pilot plant trials to see how the system could be adjusted to meet the specific process needs of silica-supported nickel catalyst.

Hitesh Vadalia takes up the story again: “We wanted to see whether we could achieve certain benefits by modifying the size of our pastilles — making them smaller.”

“Working closely with the Sandvik team, we found that reducing the size to around 5–6 mm diameter resulted in faster cooling with a lower exotherm. This is important from the end customer’s perspective as it significantly reduces the possibility of lumping due to softening during storage and transportation, even in the summer heat of India.”

“This ability to provide our customers with a more uniform and consistent product, one that performs as they expect it to, is a direct benefit of the close relationship we have with Sandvik.”

Having finalized and agreed the specification of the new line, Sandvik made similar modifications to the first line, enabling Monarch to offer enhanced quality from both Rotoform systems. The original system handles up to 3 t/d of catalyst, while the newer line provides double this capacity.

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