Gypsum scale formation control in pipe flow systems: A systematic study on the effects of process parameters and additives

Gypsum is widely known as one of the major components of scale in many industrial processes and domestic applications. The scale formation of gypsum is a persistent problem encountered by several hydrometallurgical processes in Australia. It is a complicated phenomenon which causes a series of operational problems such as a reduction in production capacity, an increase in energy requirement, and an increase in downtime for maintenance and replacement of parts. Ultimately, these technical difficulties lead to substantial economic consequences.Early researchers on gypsum scaling mainly focused on the kinetics of scale formation, while later studies put the emphasis on the effects of external factors such as hydrodynamics. To date, very little work has been done to investigate gypsum scale formation pertinent to hydrometallurgical processes such as those found in Australia, namely gypsum scaling on pipes, vessel walls and cooling systems.This paper presents a thorough and systematic investigation on the effects of various process parameters and the efficacy of both inorganic and organic additives in controlling the formation of gypsum scale in pipe flow systems. These process parameters included flow rate, temperature, supersaturation and surface materials. The effects of three inorganic and twelve organic additives, mainly the derivatives of carboxylic and phosphonic acids, on the scale formation were also investigated. © 2011 by Nova Science Publishers, Inc. All rights reserved