Chemical removal of calcium sulfate deposits from irrigation water transmission pipelines (Case study: Sedimentation of water transmission line from Sarcheshmeh copper complex tailing dam for agricultural use in downstream areas)

Abstract

Clogging and blockage of water transmission pipelines is one of the problems that reduce discharge downstream by creating various sediments. The aim of this study was to identify and remove the constraints caused by sediment in the water transmission lines of Sarcheshmeh copper complex to agricultural lands of downstream areas. First, the formed sediment was identified through XRF and XRD experiments and then optimized by using different concentrations of 30, 35, 40, 45 and 50% sodium hydroxide to remove the sediment. The results of sediment analysis showed that the predominant hardened sediment around the inner wall of the pipelines is calcium sulfate. The results of titration of the remaining solution from laboratory reactions also showed that 10 to 21% of sodium hydroxide with a concentration of 30 to 50% is used to separate more than 80% of the sediment adhering to the pipelines, which is 50% in real conditions. Also, the optimal amount of sodium hydroxide in this study was about 35% in 72 hours for complete separation of sediment from pipelines. However, due to the availability of sodium hydroxide with a concentration of 31% in the market and the no need to dilute its higher concentrations in the operating conditions, the proposed amount of sodium hydroxide for the removal of Sarcheshmeh copper pipeline to downstream 31% with an efficiency of more than 87% estimated.

Keywords

• sediment removal
• calcium sulfate
• titration
• sodium hydroxide
• water transmission lines summary