Abstract Precipitation of amorphous silica (SiO2) in geothermal power plants has been shown to occur via homogeneous nucleation in the separated water as well as heterogeneous nucleation on pre-existing surfaces. While the factors facilitating homogeneous nucleation are well known, the effect of surface properties on the heterogeneous pathway are less well understood. We investigated the precipitation of amorphous silica onto different surfaces by placing coupons of opal (= mirroring previously deposited silica), volcanic glass (= common reservoir rocks) and corrosion-resistant carbon steel (= geothermal pipelines) inside the pipelines of the Hellisheiði power plant (SW-Iceland) where they were in contact with a silica-supersaturated geothermal liquid (800 ppm SiO2, 60–120 °C) for up to 10 weeks. Our results showed that the similarities in chemical composition and structure of opal and volcanic glass to the amorphous silica were less important in facilitating nucleation than the rough surface of the carbon steel. However, once the nuclei had formed, their growth was independent of the surface material and only controlled by deployment length, temperature and the concentration of monomeric silica in the separated water. Thus, over time a continuous, botryoidal silica layer formed on all coupons. This suggests that surface properties are not crucial in developing better mitigation strategies against amorphous silica scaling.

中文翻译：

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表面粗糙度对二氧化硅氧化皮形成的早期影响比基材的化学和结构特性更强烈

摘要 地热发电厂中无定形二氧化硅 (SiO2) 的沉淀已被证明是通过分离水中的同质成核以及预先存在的表面上的异质成核而发生的。虽然促进均匀成核的因素是众所周知的，但表面特性对异质途径的影响却不太清楚。我们通过在 Hellisheiði 发电厂的管道内放置蛋白石（= 反映先前沉积的二氧化硅）、火山玻璃（= 普通储层岩石）和耐腐蚀碳钢（= 地热管道）的试样，研究了无定形二氧化硅在不同表面的沉淀（SW-Iceland），他们与二氧化硅过饱和的地热液体（800 ppm SiO2，60–120 °C）接触长达 10 周。我们的结果表明，蛋白石和火山玻璃的化学成分和结构与无定形二氧化硅的相似性在促进成核方面不如碳钢的粗糙表面重要。然而，一旦形成核，它们的生长就与表面材料无关，仅受展开长度、温度和分离水中单体二氧化硅的浓度的控制。因此，随着时间的推移，在所有试样上形成连续的葡萄状二氧化硅层。这表明表面特性对于开发针对无定形二氧化硅结垢的更好缓解策略并不重要。它们的生长与表面材料无关，仅受展开长度、温度和分离水中单体二氧化硅浓度的控制。因此，随着时间的推移，在所有试样上形成连续的葡萄状二氧化硅层。这表明表面特性对于开发针对无定形二氧化硅结垢的更好缓解策略并不重要。它们的生长与表面材料无关，仅受展开长度、温度和分离水中单体二氧化硅浓度的控制。因此，随着时间的推移，在所有试样上形成连续的葡萄状二氧化硅层。这表明表面特性对于开发针对无定形二氧化硅结垢的更好缓解策略并不重要。