Titanium Dioxide Production – Reliable pump operation by propper material selection
When pumping sulfuric acid, material selection is crucial. Important is to select a reliable but also an economic material. Corrosiveness of sulfuric acid is driven by concentration and also temperature and beyond extraordinary. A selected metal grade is usually only resistant within a small window of the concentration range from 0 -100%.
The most critical area is the middle of this concentration range. As a result, metal pumps suffer under corrosion if process parameters are changing or if they are evaluated wrong. In comparison plastic pumps can cover a much bigger range of concentration which is a clear advantage in many applications.
An international chemical group was operating pumps made from hasteloy to run its hydrolyze plant to produce titanium dioxide (TiO2). In the hydrolyze process titanium oxide sulfate is transformed in a chemical reaction to titanium dioxid (TiO2) and sulfuric acid (H2SO4). The pumps in the process have to run continuous at a temperature of 110°C and at a concentration of the sulfuric acid up to 30%. The initially installed pumps from hasteloy have been frequently failing because the selected material was not durable and corrosion and erosion occurred. High spare part costs for the hasteloy spares have been only one issue but also the downtimes in the production process were a major issue. Conclusion of this was that a better technical alternative must be found.
MUNSCH plastic pumps type NP are available in the material Polypropylene (PP), Polyethylene (PE) and Polyvenyidenfluorid (PVDF). With these different materials they can be adapted to work reliable with the specified process liquid not losing economic aspects out of the sight. For the given application the material Polyvenyidenfluorid (PVDF) was selected driven by the high process temperature of 110°C. After a first trial period the customer decided to install next to the initial pump further identical units. In the meantime all these pumps are running over several years without any sign of corrosion or erosion. The satisfaction of the plant operator regarding this outstanding performance is expressed by a reference letter given in favor of the company MUNSCH.