A research on the usefulness of silica extracted from lahar for semiconductor purposes

• Main Authors: Hingada, Leonardo R., Javier, Jonathan G., Olivan, Oliver F. Jouel A.
• Format: text
• Language: English
• Published: Animo Repository 1993
• Subjects: Silica; Lahars; Semiconductors; Volcanic ash, tuff, etc; Engineering research; Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8871
• Institution: De La Salle University

A large portion of the lahar that abounds in Central Luzon is silicon dioxide (Si02) or silica. The same compound is utilized as raw material for silicon used in the manufacture of integrated circuits. However, it is best kept in mind that a purity level of at least 98.99 percent must be obtained in order for the silica to become useful for the semiconductor industry.Lahar from Mount Pinatubo were gathered from different areas such as Porac, San Fernando, Angeles, Bamban, San Narciso and Botolan. These are the surrounding municipalities of Central Luzon. Samples were taken from unmoved deposits by shovelling and placing them into plastic containers. The samples were subjected to test and analysis in order to determine their chemical components and physical properties. Thus, it was proven that even the samples had a majority of silica content. The samples that had the most silica content was selected to undergo the extraction processes. Using the sand testing sieves, the desired sample size was obtained. Tabling or gravity concentrating process was used to separate the heavy components (concentrate materials) from the lighter components (tailing materials). The concentrates are the unwanted magnetic particles like ferric oxide (Fe203). The tailings are the feldspatic sand. The latter was then made to pass through a dry magnetic separator to remove the loose magnetic particles. The tailing were then wet grinded to further pulverize the powder-like samples. These allowed the depletion of the magnetic particles in the tailings after letting the sample pass through a wet magnetic separator. Chemical analysis showed a considerable decrease in the amount of ferric oxide. The sample was then subjected to chemical reactions to further reduce the impurities. Finally, the sample underwent fusion in order to produce a crystallized slag. Reducing the lahar to high grade silica is not impossible. However, eliminating or at least reducing the ferric oxide and alumina content was very difficult. Due to the tremendous heat during the eruption, many particles of iron and manganese were embedded in the relatively larger particles of silica and the other compounds.