Batch separation of silica slurry from Botong geothermal field

• Main Authors: Carasus, Eric D., Javier, Jimmy M., Vidallon, Liza P.
• Format: text
• Language: English
• Published: Animo Repository 1995
• Subjects: Silica; Slurry; Sewage > Purification; Separation (Technology); Geothermal power plants; Geothermal brines; Waste disposal; Chemical Engineering
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/8872
• Institution: De La Salle University

The highly concentrated amorphous silica (approx. 1400 ppm) in Botong geothermal brine, a major concern in the Cold Injection Scheme (CTS) of the Fluid Collection and Disposal System (FCDS) of the Philippine National Oil Company-Energy Development Corporation (PNOC-EDC), was collected by dropping the fluid's temperature and precipitating colloidal silica in a huge baffled thermal pond (TP-1). The collected silica slurry samples from 20 lanes of the TP-1 were characterized physically and chemically. Physical characteristics of the slurry have similarities to pure water. The slurry contains amorphous silica of about 98.7 pure in terms of silica.Chemical properties such as pH and total silica content of the surface water were also determined and both exhibited their dependence on temperature lowering.Several techniques (i.e., sedimentation, decantation, filtration, centrifugation and air/oven drying) have been tested to reduce silica slurry concentration prior to reinjection. Thus, the result of this project will help in developing an alternative method for the proper handling and disposal of geothermal fluid. Analysis was made based on the results of total silica and moisture content determination. The results showed that the basket-type centrifuge filter was quite an effective equipment in the solid liquid separation. Best results were obtained when speed (in rpm) was varied at different time intervals with an operating time of 10 minutes (2 mins for 1165 rpm, 3 mins. for 1555 rpm, and 5 mins for 2425 rpm).