Turning geothermal waste into glasses and glass ceramics

Researchers investigating the waste on the pipes at the Cerro Prieto geothermal plant in Mexico found that it contained high amounts of silica. Initial tests showed that this waste silica had a high specific surface area, contained salts that could easily be eliminated, and resisted high temperatures effectively. Further research was done to see if this waste material could be used as silica sand in the production of glass. Testing of the waste material included the following: X-ray diffraction with nickel filters; EDX spectroscopy with ultrathin window; Differential thermal analysis; IR spectroscopy analysis; Electron microscope analysis. The tests were done on the raw material itself and on four sets of glass formulated from the raw material. Two sets of glass were formulated from untreated waste material, and two sets were formulated from treated waste material. The raw material was tested for purity, and the glass was tested for hardness, toughness, and transparency. As the tests show, the silica material from the Cerro Prieto plant steam pipes is not merely useless industrial waste. It is a reproducible source of silica sand that producers can use in ceramic and glass production. The initial tests show that the properties of the raw material,more » and those of the glass formulated from the raw material, will meet industry requirements.« less