The Influence of Minerals on Equipment Corrosion in Geothermal Brines

Abstract

Industrial minerals, extracted from geothermal brines, play an important role in the economy of many countries, which own and operate geothermal fields and geothermoelectric plants. These minerals are the raw materials for the chemical, fertilizer, metal, ceramic and building industries.

Corrosion affects the different types of equipment, machinery and structures, made from two basic engineering materials: steel and concrete, used in geothermal plants and installations. Minerals undergo ionic dissociation in the brines, contribute to their salinity, chlorinity, and electrical conductivity; alter their pH and increase their corrosivity. Other corrosive substances are present in the brines such as dissolved gases: Oxygen (O2) carbon dioxide (CO2), ammonia (NH3) and hydrogen sulfide (H2S). Some minerals, depending on their chemical nature and solubility, deposit on metallic surfaces as a hard scale and corrosion appears underneath.

Corrosion control engineering applies methods and techniques of prevention and protection, to avoid the interaction of the equipment and structures with the corrosive constituents of the geothermal brines. Typical cases of corrosion in geothermal brines in USA, Mexico and Israel will be presented, illustrated and discussed.