Blasting Design Without Subdrilling on Jointed Limestone to Optimize Fragmentation and Blasting Cost

Abstract

Bench blasting operation on limestone opencast mining at PT. Semen Padang (Persero), Indonesia performed by electric blasting using coloumn loading system. Limestone deposit consist of three type of rock characteritics that are hard limestone, sugary limestone, and jointed limestone. In general, a good blasting design should implementing subdrilling to avoid toe. In this case of study the subdrilling is not need due to the present of many cracks caused by basalt intrusion. Blasting geometry that applied to blast the jointed limestone resulting blasting fragmentation that commonly relatively small in size (<60 cm) but still has some boulders (>60 cm) that caused by coloumn loading system where energy was concentrated in the bottom. Based on field observation of limestone blasting operation and productivity of excavator being used that is Excavator Hitachi EX 1100 with 5.4 m 3 bucket capacity, can be optimized. Especially from the view of drilling and blasting efficiency by modifying blasting geometry and explosive usage to optimize fragmentation to the productivity of excavator being used. Modification that performed is eliminate the sub drilling and change the explosives loading system from coloumn loading to deck loading (include amount of explosives and detonator being used). Based on result of modification, achieve decreasing of boulder percentage as much as 50.25% that is from 9.71% to 4.83% and increasing of excavator productivity up to 36.10% from 1,479 ton/hour to 2,013 ton/hour as well as decreasing blasting cost up to 17.18% from Rp 3,456/ton to Rp 2,862/ton.

Optimalisasi pemberaian overburden dengan metode ripping dan peledakan di Banko Barat PT Bukit Asam Tbk

“…Dalam rangka meningkatkan efisiensi penggalian overburden dan mengatasi getaran tanah akibat peledakan serta meningkatkan kestabilan lereng, maka harus dirancang geometri peledakan, penggunaan bahan peledak, dan sistem delay (Ilahi, Ibrahim dan Swardi, 2014). Ukuran fragmentasi yang dihasilkan dengan menggunakan desain geometri peledakan tertentu diharapkan sesuai dengan kapasitas bucket excavator (Toha, Bochori dan Waluyo, 2017).…”

“…Sistem peledakan overburden di Pit 1 Utara Banko Barat menerapkan non-electric detonator (nonel) yang dikombinasikan dengan sistem inisiasi menggunakan dayadet electric detonator yang dihubungkan ke blasting machine menggunakan lead wire. Diameter bit yang digunakan adalah 200 mm, dan tujuan peledakan pada material very soft strength rock Bienawski 2 -20 Mpa (Toha, Bochori dan Fajar, 2020), hanya untuk meretakkan material (Toha, Bochori dan Waluyo, 2017). Pola pengeboran lubang handak adalah sistem zig-zag dengan geometri peledakan seperti tertera pada Tabel 2.…”

Technical Blasting and Ripping of Overburden to Reduce the Effect of Ground Vibration on Slope Stability and Residence around Coal Mine

“…2). In order to increase the efficiency of overburden excavation, overcome ground vibrations due to blasting, and increase slope stability, it is necessary to design blasting geometry, use of explosives, and delay systems [9]- [11].…”