Rockwood specifies Profibus compatible valves

Burkert Fluid Control Systems has supplied Profibus compatible valves for a new batching system at Rockwood Electronic Materials, ultrapure chemicals plant at Riddings in Derbyshire.

Burkert Fluid Control Systems has supplied Profibus compatible valves for a new batching system at Rockwood Electronic Materials, ultrapure chemicals plant at Riddings in Derbyshire.

Rockwood Electronic Materials is part of Rockwood Specialties, a speciality chemicals producer with sales exceeding GBP 1 billion and operations in 25 countries worldwide.

At its Riddings site in Derbyshire, Rockwood Electronic Materials produces ultrapure processing chemicals and mixtures for use in the manufacture of silicon wafers and semiconductor devices.

Following a strategic business decision, a new and comprehensively upgraded, state-of-the-art, automated mixtures production plant has now been completed and commissioned this spring.

The new plant features algorithm-controlled processing to enable the fast and accurate introduction of new and existing generations of etchants and cleaners.

A Wonderware in-batch system was chosen as the control base for the project, for its ability to provide both flexibility and integration between highly critical recipe manufacturing, packaging and clean-room sample analysis.

It also allows simple integration with the Protean system already operating at the Riddings site.

The variable fill rate elements of the Wonderware in-batch system operate via a series of Burkert process valves that are fitted with integrated Profibus DP control heads.

The valve inventory comprises Burkert 2712 stainless steel globe valves, 2731 stainless steel diaphragm valves and 2730 PVDF diaphragm valves.

The process produces some 300 different chemical mixtures for use in semiconductor manufacturing.

Bulk raw materials are delivered to environmentally controlled holding tanks.

Under the operator's command, the control system operates from recipe algorithms to bring measured quantities of chemicals, via the Burkert Profibus valves, through the appropriate purification, distillation and filtration matrices to automatically cleaned and prepared mixing tanks where ultrapure water is added as required.

The mixture is then either held in a storage tank until required or routed directly to the packaging cleanlines where customer-specific containers are filled under strictly controlled conditions.

To produce a new mixture the operator enters the product code, quantity required, exact strengths of the raw materials to be used and the algorithm code for the mixture.

After validation, the in-batch system automatically opens the delivery valve from the first raw material tank indicated for the recipe and starts the transfer pump.

It continuously monitors the weight of the raw material tank's contents and shuts the valve and stops the pump when the required amount has been delivered to the mixing tank.

The operations are repeated for other constituents of the mix.

The extensive reconstruction, refurbishment and expansion of the production and packaging facilities is now fully commissioned with the new pure acid and mixtures production facilities operating under a fully integrated Windows 2000-based control system.

Andrew Hutchison, Facilities Manager of Rockwood's plant at Riddings, has been pleased with the competence of the Burkert valves and the company's technical support during the new plant's construction.

"Integrity of cleanliness in the handling of sometimes aggressive chemicals was an additional criterion in selection of these control valves", explains Hutchison.

"We selected Burkert process valves because of their robust construction in appropriate materials and their integrated Profibus DP control heads which are easily incorporated into our control system".

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