Experimental Study on the Influence of Ion Components in Geothermal Water on Scaling Behavior

Understanding the scaling behavior of geothermal water is essential for optimizing geothermal plant performance and ensuring sustainable energy use. However, research on the effects of common ionic components in geothermal environments on scaling is still insufficient, and there is a lack of in-depth exploration of the quantitative control of ion concentrations. This study selected common ionic components based on the ionic composition of geothermal water samples and simulated a realistic geothermal environment by setting concentration gradients. Static aeration immersion experiments, combined with XRD and SEM analysis, were conducted to systematically investigate the effects of various ionic components on scaling behavior. The results indicate that CaCO3 is the primary scaling substance in the simulated geothermal water. Ca2+, HCO3−, and SiO32− significantly influence scaling. Specifically, the scaling amount increases with higher Ca2+ concentration. HCO3− exhibits a nonlinear trend, with scaling initially increasing and then decreasing once its concentration exceeds approximately 1000 mg/L. This inhibition is likely due to HCO3−’s pH-buffering effect, restricting its conversion to CO32− and limiting CaCO3 precipitation. SiO32− significantly inhibits scaling, reducing the scaling amount by about 88.91% when its concentration increases from 0 to 200 mg/L. The effect of Mg2+ is relatively minor, with a 13.21% reduction in scaling as its concentration increases from 0 to 50 mg/L. However, Mg2+ notably alters the crystal phase of CaCO3, promoting aragonite formation. Without Mg2+, CaCO3 predominantly forms as calcite. These findings emphasize the crucial role of ionic components and their concentration gradients in scaling, providing theoretical support for effective scaling prevention and control strategies.