Phosphoric Acid
Phosphoric acid is the “source” of such different products as fertilizers and cola drinks. It is manufactured on a large industrial scale primarily by breaking down phosphate rock with sulphuric acid in a wet chemical process. Calcium sulphate is precipitated and removed by centrifuges.
However, calcium sulphate is a solid that becomes very compact making it one of the most difficult products to discharge. At the external periphery of the bowl, gypsum simply becomes “concrete”. It cannot be reliably discharged with a self-cleaning bowl.
This is the reason why GEA Westfalia Separator for many decades has been using special nozzle-type separators that discharge the solids continuously as a concentrated suspension while the liquid is clarified with highest efficiency and discharged under pressure by means of a centripetal pump. If the customer wishes to dewater the gypsum to a greater DS content to use it profitably, it makes sense to install a decanter (e.g. of the type TCE 535) right after the nozzle separator. The same is applicable if there are comparable high concentrations of solids in the feed.
It is frequently the case that decanters and separators are used in two different stages. GEA Westfalia Separator machines have demonstrated their ability in the field to meet all specified requirements in the phosphoric acid process.
Machines for recovering phosphoric acid have all product-contacting parts made from special materials that resist its corrosive properties. Especially the high speed nozzle machines (e. g. type TDC 130) need to be designed correctly taking the erosion into consideration. If desired the nozzle machine can be supplied with a complete recycling loop package unit.
Production of phosphoric acid