Solids and sulfate ions removal from mine water by dissolved air flotation
Sánchez Ortega, Cristina (2019)
Diplomityö
2019
School of Engineering Science, Kemiantekniikka
Kaikki oikeudet pidätetään.
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2019101532699
https://urn.fi/URN:NBN:fi-fe2019101532699
Tiivistelmä
Environmental and acceptance risks related to water discharge together with raw water scarcity at mineral processing plants and their surroundings demand the implementation of correct measurements to reduce water consumption. However, recycling mine water by closing water loops in the plant may result in efficiency and selectivity problems in other parts of the process, particularly in froth flotation.
Some of the parameters present in mine waters that can affect the efficiency of the process are colloids, ions, residual reagents, microorganism, pH, redox potential and temperature. In this work, the focus has been set to remove colloidal matter and sulfate ions. Colloids, measured as suspended solids, is one of the main parameters to determine water quality. Moreover, sulfates, mainly produced by the treatment of sulfide ores, can cause environmental discharge problems such as acid mine drainage apart from imperiling flotation.
Therefore, this master’s thesis focuses on study of laboratory scale Dissolved Air Flotation (DAF) for water clarification of two different mine waters. In addition, sulfate removal via ettringite precipitation prior to DAF is tested. The results show that DAF can reduce water turbidity to under 10 NTU for all cases. Ettringite precipitation followed by DAF can effectively decrease the content of SO42-, along with Mg, Ca, V, Mn, As, Sb, and U in the water.
Some of the parameters present in mine waters that can affect the efficiency of the process are colloids, ions, residual reagents, microorganism, pH, redox potential and temperature. In this work, the focus has been set to remove colloidal matter and sulfate ions. Colloids, measured as suspended solids, is one of the main parameters to determine water quality. Moreover, sulfates, mainly produced by the treatment of sulfide ores, can cause environmental discharge problems such as acid mine drainage apart from imperiling flotation.
Therefore, this master’s thesis focuses on study of laboratory scale Dissolved Air Flotation (DAF) for water clarification of two different mine waters. In addition, sulfate removal via ettringite precipitation prior to DAF is tested. The results show that DAF can reduce water turbidity to under 10 NTU for all cases. Ettringite precipitation followed by DAF can effectively decrease the content of SO42-, along with Mg, Ca, V, Mn, As, Sb, and U in the water.