PU-07

Workshop & Seminar Nasional Geomekanika III WSNG III 16-17 Februari 2015, Jakarta

Aplikasi geomekanika dalam rancangan peledakan untuk menunjang

effisiensi penggunaan dozer di Pit Bendili Prima, Hatari department,

PT Kaltim Prima Coal

(Application of geomechanic in blasting design to support efficiency in

utility of dozer at Bendili Prima Pit, Hatari department,

PT Kaltim Prima Coal)

Wahyu Asmoro Nursandi1, Rinaldo Kurniawan2, dan Wiwin Junita Ningrum3

1Short Term Plan Coordinator-HATARI Department, PT. Kaltim Prima Coal, Kutai Timur, 75611, Indonesia 2 Senior Specialist-Business Analysts Department, PT. Kaltim Prima Coal, Kutai Timur, 75611, Indonesia

3Geotechnical Pit-Geotechnical Department, PT. Kaltim Prima Coal, Kutai Timur, 75611, Indonesia

Sari Perkembangan kondisi harga batubara yang sedang menurun diperlukan operasional tambang yang effisien. Dalam rangka menunjang program effisiensi pengalokasian dozer, HATARI department bekerja sama dengan Drill and Blast department dan Geology department me-review rancangan peledakan top on coal (TOC) di Pit Bendili Prima. Pada awal pembukaan

Pit Bendili Prima penerapan rancangan peledakan TOC yaitu lubang paling dangkal dari batubara adalah 3 meter, sedangkan lubang terdalam yaitu 10 meter. Permasalahan mulai muncul di RL200, saat exposed batubara biasanya hanya dialokasikan 1 dozer untuk membantu feeding material blasting TOC diperlukan tambahan 1 dozer sebagai alat bantu untuk melakukan penggaruan material overburden TOC yang diatas 3 meter. Penggunaan 2 dozer untuk membantu kegiatan exposed batubara sangat tidak effisien. Berdasarkan data dari Geotechnical section untuk UCS material overburden 2 seam batubara di Pit Bendili Prima (B2SR dan BNSR) adalah 11,90 Mpa untuk B2SR dan 15.78 Mpa untuk BNSR. Sedangkan densitas material overburden B2SR 2,44 t/m3 dan 2,46 t/m3 material overburden BNSR. Kemudian Geotechnical section dan HATARI department melakukan analisa terhadap material overburden di Pit Bendili Prima menggunakan data hasil pengeboran explorasi. Setelah

melakukan analisa geotechnical disimpulkan setiap massa batuan memiliki tingkat kemampugaruan (rippability) tertentu. Kemampuan (rippability) merupakan suatu ukuran apakah massa batuan mudah digaru, sulit digaru atau bahkan tidak dapat digaru. Sehingga direkomendasikan untuk memaksimalkan blasting TOC agar pengalokasian dozer lebih optimal. Selanjutnya HATARI department dengan Drill and Blast department mencoba melakukan praktek pengeboran 16 meter TOC. Tujuannya agar saat kegiatan pengupasan overburden untuk exposed batubara di level selanjutnya tidak diperlukan tambahan dozer untuk ripping exposed batubara. Praktek pengeboran TOC 16 meter terbukti efektif menghasilkan broken material yang tidak keras dan fragmentasi tidak berbongkah di area TOC diatas 3 meter, sehingga tidak diperlukan tambahan 1 dozer untuk ripping material TOC diatas 3 meter.

Kata-kata kunci: Rippability, Top of Coal

Abstract The trend of dwindling coal price condition needs an efficient mining operation. In order to support efficiency program of

dozer allocation, Hatari department in collaboration with Drill & Blast department and Geology department to review the blasting design of top of coal (TOC) at Bendili Prima pit. At the beginning of opening Bendili Prima pit, the most shallow hole depth applied is 3 meters, while the deepest hole is 10 meters. The problems has started to emerge in RL200, when exposing coal which used to allocate only 1 dozer to assist feeding TOC blasting material, now is required additional 1 dozer to perform ripping of TOC overburden material above 3 meters. The using of 2 dozers to assist exposing coal is very inefficient. Based on geotechnical data for UCS of overburden material at 2 coal seams at Bendili Prima (B2SR and BNSR) is 11.90 MPa for 11.90 MPa and 15.78 MPa for BNSR, while the material density is 2.44 t/m3 and 2.46 t/m3 respectively. Then,

Geotechnical section and Hatari department have performed an analysis of the overburden material at Bendili Prima using data from exploration drilling. After doing geotechnical analysis, it has been concluded that every rock mass has each own rippability. Rippability is a measure of whether the rock mass can be easily raked, difficult to be raked or even can not be raked. It is recommended to maximize TOC blasting so that there can be more optimum dozer allocation. Furthermore, Hatari with Drill & Blast department have tried to practice TOC drilling of 16 meters deep, so there will be additional dozer to assist the exposing of coal in the next elevation below the current level. Top of coal drilling of 16 meters has been proven to be effective and results good broken material and fragmentation for particular TOC area above 3 meters, so it does not need additional dozer.

Keywords:rippability, top of coal *Penulis untuk korespondensi (corresponding author): E-mail: [email protected] atau [email protected] Tel: +62-549-525411 atau +628 132 653 043 8, Faksimil: +62-549-2509998


I. PENDAHULUAN / INTRODUCTION Bendili Prima merupakan salah satu pit yang

dioperasikan Hatari department. Karak teristik pit

Bendili Prima mempunyai UCS yang sangat tinggi.

UCS material overburden 2 seam batubara di Pit

Bendili Prima (B2SR dan BNSR) adalah 11,90

Mpa untuk B2SR dan 15.78 Mpa untuk BNSR. Hal ini mengharuskan hasil fragmentasi peledakan tidak

keras, agar mengurangi alokasi dozer untuk

membantu ripping material blasting. Praktek

operasional dengan mengalokasikan dozer untuk

ripping membantu exposed batubara tidak effisien.

Dalam era harga batubara yang menurun,

perusahaan harus menerapkan praktek operasional

yang effisien. Dengan mengevaluasi rancangan

peledakan top on coal diharapkan saat exposed

batubara tidak membutuhkan kegiatan ripping.

Sehingga dozer bisa dialokasikan untuk pekerjaan lain.

Bendili Prima is one of the pits operated by Hatari

departement which has a very high UCS of rock

mass. UCS of overburden material in 2 coal seams

are 11.90 Mpa for B2SR dan 15.78 Mpa for BNSR.

This fact requires good fragmentation as a blasting

result in order to avoid additional dozer for ripping

blasted material. The practice to add more dozers to

assist exposing coal is inefficient. Moreover, the

trend in dwindling coal price has forced industries

to implement efficient operational practices. By

evaluating blasting design on top of coal, it is expected that ripping activities is less needed while

exposing coal, so that dozer can be allocated to

other works.

II. KAJIAN PUSTAKA / STUDY OF LITERATURE

Daerah penelitian termasuk Formasi Balikpapan

Beds bagian tengah tersusun atas batu lempung,

batu lanau, batu pasir, dan batubara dengan

ketebalan 1-20 meter. (Departemen Geologi PT Kaltim Prima Coal, 2005). Area of this study is included in the central part of

Balikpapan Beds Formation which is formed by

claystone, siltstone, sandstone, and coal with

thickness of 1-20 meters. (Geology Department PT

Kaltim Prima Coal, 2005).

KEMAMPUGARUAN

Kemampugaruan (rippability) merupakan suatu

ukuran apakah massa batuan mudah digaru, sulit

digaru atau bahkan tidak dapat digaru . Pengamatan

dan penguukuran kedalaman ripper serta produksi

ripper per jam selama pekerjaan ripping. Dalam penelitian menggunakan CAT D8, diyakini hasil

penelitian juga berlaku bagi jenis dan dozer dengan

kapasitas yang sama dari produsen lain( H. Basarir.

2008). Untuk menentukan volume produksi rippinh

dipengaruhi oleh panjang ripper dan metode yang

digunakan saat riiping. Selama kegiatan ripping

effisiensi operator (E), waktu ripping (Tr), waktu

manuver dozer (Tm), jarak/panjang area yang

di-ripping(L), lebar penggaruan/hasil ripping (W)

dan kedalaman saat ripping (D). Pengamatan

perubahan kedalaman ripper menunjukkan

kemudahan dan effisiensi ripping. Produksi dalam

satu putaran(cycle) dapat dihitung dengan rumus: qr = Car L

Keterangan:

qr : produksi dalam satu putaran/cycle (m3)

Car : luas penampang penggaruan/ripping(m2)

L : panjang area yang di-ripping (m)

Luas penmpang penggaruan/ripping adalah luas

segitiga hasil ripping. Hal ini bisa dilihat dari

gambar dan dihitung dengan persamaan di bawah:

Gambar 1. Luas penampang penggaruan

Car = DW

2

Keterangan:

Car : luas penampang penggaruan/ripping(m2) D : kedalaman saat ripping(m)

W : lebar penggaruan (m)

Produksi ripper perjam dapat dihitung dengan

persamaan sebagai berikut:

Qr = qr 60 E

2

Keterangan:

Qr : produksi per jam (m3/h)

qr : cycle time saat ripping(minute)

E : effisiensi saat ripping

Dari data UCS batuan yang di-ripping dapat

didapatkan berapa spesifik energi setiap batuan.

Tabel 1. Perhitungan hugungan properti batuan dengan

spesifik energi


Hasil perhitungan digunakan untuk

mengklasifikasikan rippability menggunakan tabel

dan grefik klasifikasi rippability.

Tabel 2. Klasifikasi kemampugaruan terhadap batuan

untuk dozer CAT D8

Grafik 2. Grafik klasifikasi penggaruan berdasarkan hubungan produksi dan spesifik energi

RIPPABILITY

Rippability is a measure of whether the rock mass

can be easily raked, difficult to be raked or even

cannot be raked. Observation and measurement of

depth of ripping and hourly ripper production have

been done during ripping activity. The result of study using dozer D8 has been believed that can

also be applied to the same type and capacity of

dozer from other manufacturers (H.Basarir, 2008).

Determination of ripping volume is influenced by

length of the ripper and method used while ripping.

During ripping activity, operator efficiency (E),

time of ripping (Tr), time of maneuvering dozer

(Tm), length/distance of ripped area (L), width of

ripped area (W), and depth of ripping (D) have

contributed to determine volume of ripping.

Observation at change of ripping depth has shown ease and ripping efficiency. Production of ripping

in one cycle can be calculated as below formula:

qr = Car L

qr : volume of ripping in one cycle (m3)

Car : cross-sectional area of ripping (m2)

L : lenght of ripped area (m)

Ripping cross-sectional area is the area of triangle

as a result of ripping. This is shown and calculated

as below equation:

Picture1. Cross-sectional area of ripping

Car = DW

2 Car : cross-sectional area of ripping (m2)

D : depth of ripping(m)

W : width of ripping (m)

The hourly production of ripper can be calculated

as below formula:

Qr = qr 60 E

2

Qr : production per hour (m3/h)

qr : ripping cycle time (minute)

E : ripping efficiency

From UCS data of ripped rock, it can obtain the

specific energy of each rock mass.

Table 1. The relationships between rock properties and

specific energy

The result of the calculation can be used to classify

rippability using table and graph of rippability

classes.

Tabel 2. Rippability classes of rock for D8 dozer


Graph 2. Rippability classes based on the relationships between production and specific energy

GEOMETRI PELEDAKAN

Geometri peledakan merupakan suatu hal yang

sangat menentukan hasil peledakan dari segi

fragmentasi yang dihasilkan , rekahan yang

diharapkan maupun dari segi jenjang yang terbentuk. Dalam kegiatan peledakan yang

termasuk geometri peledakan adalah burden, spasi,

stemming, sub drilling, kedalaman lubang ledak,

panjang kolom isian, diameter lubang ledak dan

tinggi jenjang.

Burden dapat didefinisikan sebagai jarak dari

lubang bor terhadap bidang bebas(free face) yang

terdekat pada saat terjadi peledakan.

Spacing adalah jarak antara lubang tembak dalam

satu baris (row) dan diukur sejajar

terhadap pit wall. Subdrilling adalah tambahan kedalaman daripada lubang bor dibawah

rencanalantai jenjang. Subdrilling perlu untuk

menghindari problem tonjolan pada lantai

(toe),karena dibagian ini adalah tempat yang paling

sukar diledakkan.

Stemming adalah panjang isian lubang ledak yang

tidak diisi dengan bahan peledak tetapi diisi dengan

material seperti tanah liat atau material hasil

pemboran (cutting) dimana stemming berfungsi

untuk mengurung gas yang timbul sehingga air

blast dan flyrock dapat terkontrol.

Gambar 3. Geometri peledakan

BLASTING GEOMETRY Blasting geometry is very crucial to determine blast

result in terms of fragmentation, the expected

fracture and formed bench level. In the blasting

activities, there are several things which included as

blasting geometry such as burden, spacing,

stemming, sub drilling, blast hole depth, length of

the explosive charge, hole diameter and height of

bench level.

Burden can be defined as the distance from the

borehole to nearest free face at the time of

detonation. Spacing is distance between blast holes in one row and measured parallel towards pit wall.

Sub-drilling is an additional depth of hole below

the base of the bench that will be blasted.

Sub-drilling is needed to avoid bulge at the base of

blasted bench since it is the most difficult place to

be blasted.

Stemming is part of blast hole which is not charged

with explosive, instead it is filled with materials

such as clay or cutting drilled material. Stemming is

used to confine emerged gas so that air blast and

flyrock can be controlled.

Picture 3.Blasting geometry

III. METODOLOGI / METHODOLOGY Pengumpulan data melalui percobaan langsung

menggunakan dozer CAT D10 dengan number id

E426. Sedangkan geomekanik melalui data

sekunder dari data laboratorium Geology

Department meliputi data UCS dan density untuk

memperoleh gambaran awal mengenai kondisi

massa batuan.

Data collection through direct experiment using

dozer CAT D10T with ID number of E426. Geomechanics data collection through secondary

data from laboratory includes Geology Department

UCS and density to obtain a preliminary picture of

the condition of the rock mass.

IV. HASIL DAN PEMBAHASAN / RESULT AND ANALYSIS

Hasil penelitian menggunakan dozer CAT D10

dengan nomor ID E426 didapatkan

pengklasifikasian rippability untuk BNSR dalam

kategori easy rippability dan B2SR dalam kategori moderate rippability.


Gambar 4. Penelitian menggunakan dozer CAT D10

Gambar 5. Pengambilan data kedalaman ripper

Tabel 3. Hasil pengolahan data penelitian

Gambar 6. Grafik klasifikasi kemampugaruan

berdasarkan data penelitian

Dari hasil klasifikasi rippability digunakan untuk

merancang geometri peledakan top on coal(toc) di

Pit Bendili Prima. Meskipun dari klasifikasi

rippability termasuk dalam kategori easy dan

moderate, info dari operation Hatari bahwa area toc

dengan kedalaman 3 meter untuk batubara BNSR

dan B2SR sangat keras jika dilakukan kegiatan

ripping. Hasil diskusi antara Hatari department dengan Drill and Blast department mencoba

menerapkan praktek blasting toc 16 meter,

tujuannya untuk mengantisipasi agar toc 3 meter di

level selanjutnya.

Gambar 7. Cross section blasting top on coal 16 meter

The study using dozer CAT D10T with ID number

of E426 has resulted in category of rippability for

both seams at Bendili Prima. According to the table

of rippability classes, BNSR is categorized as easy

rippability, while B2SR is categorized as moderate

rippability.

Picture 4. Study using dozer CAT D10

Picture 5. Collecting data of ripping depth

Lebar penggaruan (W) 0.5 m

Kedalaman ripping (D) 0.3 m

Luas penampang penggaruan (Car) 0.075 m2

Produksi per jam (Qr) 297 (m3/h)

Cycle time saat ripping (qr) 0.33 minute

Effisiensi saat ripping (E) 30 %

UCS BNSR 11.9 Mpa

UCS B2SR 15.8 Mpa

Spesifik energi (SE) BNSR 4.79 MJ/m3

Spesifik energi (SE) B2SR 5.57 MJ/m3


Table 3. Result of processing data

Picture 6. Graph of rippability classes based on data

From the result of classification, rippability is used to design blasting geometry on top of coal (TOC) at

Bendili Prima pit. Although the study results in

easy and moderate category, it is actually a very

hard to be ripped in the direct pit operation,

especially in area of 3 meters deep for BNSR and

B2SR. The discussion between Hatari and Drill &

Blast has decided to try 16 meters TOC blasting

practical, in order to anticipate 3 meters TOC in the

next below level.

Picture 7. Cross sectional 16 meters drilling on top of coal

V. KESIMPULAN DAN SARAN Rancangan peledakan top on coal 16 meter dapat

mencegah hasil blasting yang keras di area top on

coal di atas 3 meter, sehingga mengurangi alokasi

dozer untuk membantu ripping di area top on coal 3

meter. Penelitian tentang rippability untuk Pit

Bendili Prima hanya menggunakan 1 sample tentu

perlu data tambahan kembali. Hal ini disebabkan keterbatasan dozer yang harus digunakan untuk

kegiatan produksi. Untuk penelitian selanjutnya

diharapkan ada pengambilan data yang lebih

banyak.

Blasting design of 16 meters on top of coal can

avoid hard blasted material in TOC area above 3

meters, so that additional of dozer to help rippingis

not necessarily needed. Study of rippability at

Bendili Prima pit only used 1 sample, it surely

needs more data. Lack of dozer availability because

they were used to operational activity was the main cause. It is highly expected of more data in the next

studies.

VI. UCAPAN TERIMA KASIH Penulis mengucapkan terima kasih kepada pihak

yang telah membantu selama proses penelitian,

khususnya kepada manajemen HATARI

Department Bapak Richard Sitohang, Didik

Mardiono, ST. ,dan Hindradmoko, ST. Yang

memberikan kepercayaan penulis untuk

melaksanakan penelitian rippability di Pit Bendili

Prima. Selain itu penulis juga mengucapkan terima kasih kepada Shift Superintendent Operational

HATARI Department, yang mengizinkan

pejnggunaan dozerr untuk penelitian.

The writers want to thank all related parties who

have helped throughout the process, especially to

management of Hatari department, Bapak Richard

Sitohang, Bapak Didik Mardiono, ST. , and Bapak

Hindradmoko, ST. The writers feel grateful for all

the trusts that have been given to carry out this at

Bendili Prima pit. Besides, the writers also want to

thank all Shift Superintendent of Hatari Operation who had shown willingness to assign the dozer for

the benefit of this study.

DAFTAR PUSTAKA/REFERENCES

1. Basarir H. Specific energy based rippability classification system for coal measure rock.

Journal of Terramechanics 45; 2008.

2. Basarir H. Development of a new rippability assessment method based on specific energy

concept and numerical modelling. PhD thesis.

Middle East Technical University, Ankara,

Turkey; 2002. 3. Anon. Caterpillar performance handbook. 19th

ed. Peoria, Illinois, USA: Caterpillar Inc.; 1988.

4. Bailey AD. Rock types and seismic velocity versus rippability. In: Highway geology

symposium proceedings, vol. 26. p. 13542.

Lebar penggaruan (W) 0.5 m

Kedalaman ripping (D) 0.3 m

Luas penampang penggaruan (Car) 0.075 m2

Produksi per jam (Qr) 297 (m3/h)

Cycle time saat ripping (qr) 0.33 minute

Effisiensi saat ripping (E) 30 %

UCS BNSR 11.9 Mpa

UCS B2SR 15.8 Mpa

Spesifik energi (SE) BNSR 4.79 MJ/m3

Spesifik energi (SE) B2SR 5.57 MJ/m3

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