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Minggu, 02 April 2017

PT. RIYANTA JAYA Kapuas coal project

INTRODUCTION


Sesuai dengan Surat Keputusan Bupati Kapuas yang dimiliki oleh PT. RIYANTA JAYA, lahan konsesi PT. RIYANTA JAYA secara Administratif terletak di wilayah Desa Barunang dan Sekitarnya, Kabupaten Kapuas, Propinsi Kalimantan Tengah yang berada ± 120 km ke arah utara Kota Palangkaraya
Konsesi PT. Riyanta Jaya ini bertepatan di bagian Timur sungai Kapuas yang berbatasan langsung dengan Kabupaten Barito Utara. Luas konsesi ini ± 5.000 Hektar.

2.1 Geologi Regional
Secara regional daerah eksplorasi terpetakan dalam Peta  geologi Regional lembar Muara Teweh skala 1 : 250.000 (Supriatna dan Adjat Sudrajat, tahun 1992) dan Lembar Buntok skala 1 :250.000 (supriatna dkk, tahun 1994 dan 1995)
Stratigrafi di Lokasi Penyelidikan termasuk ke dalam 2 (dua) Formasi saja, yaitu Formasi Tanjung, Formasi Purukcahu, dan batuan sediman & vulkanik tak terpisahkan. Formasi Tanjung yang terdiri dari Batupasir Kuarsa berbutir halus sampai sedang, mengandung lapisan tipis mineral karbonan, rombakan batubara vitrinit dan muskovit, bersisipan batulempung karbonan berwarna kelabu dan batulanau menyerpih berwarna kelabu tua. Batupasir Kuarsa putih berstruktur silang siur, sebagian gampingan, bersisipan batulanau/serpih dan batubara.









2.1 Geology Database
Database geologi yang ada adalah berupa data pemboran dan data singkapan yang telah dilakukan oleh tim ekplorasi PT. Riyanta Jaya terdahulu dalam kegiatan pemboran dan  pemetaan singkapan batubara.
Data pemboran yang tersedia saat ini sebanyak 9 titik bore dan data singkapan sebanyak 11 singkapan batubara. Dari data singkapan batubara tersebut, tidak semuanya masuk kedalam database yang akan diproses kedalam pemodelan geologi. 



Tabel 1. Data Pemboran PT. Riyanta Jaya
NO.
BOREHOLE
KOORDINAT UTM
TOTAL DEPTH
COAL INTERVAL
THICK
SEAM NAME
EASTING
NORTHING
ELEVASI
FROM
TO
1
DH-01
214544
9895456
118.402
80
-
-
-

2
DH-02
214535
9895471
117.235
10
4
5.7
1.7
C
3


DH-03


214411


9895508


112.25


90


2.4
3
0.6
D1
3.5
5.3
1.8
D2
7.2
8.6
1.4
D3
4
DH-05
215379
9895801
113.755
90
7
10
3
D
5
DH-05A
215274
9895650
105.095
90
23.8
25.3
1.5
C
6
DH-06
215113
9895724
105.003
90
5
8.4
3.4
D
7
DH-07
214928
9895533
125.45
90
-
-
-

8
DH-08
214760
9895545
125.685
90
12
13.2
1.2
C
9
DH-09
214556
9895606
104.337
70
-
-
-


Tabel 2. Data Pemboran PT. Riyanta Jaya
                COAL OUTCROP
KOORDINAT UTM
THICK
SEAM NAME
EASTING
NORTHING
ELEVASI
OC-07
214398
9895316
125.453
1.5
B
OC-08
214414
9895308
126.206
1
A
OC-10
214735
9895832
104.248
1.8
F
OC-11
214217
9895495
113.021
1
E




2.1 Geological Model
Metodologi yang digunakan untuk pemodelan ini serta validasi lebih lanjut dari data drillhole menggunakan sistem komputerisasi dengan Mincom MineScape Sofware, yaitu sebagai berikut:
·         Data drillhole tersimpan dalam format spread sheet dan kemudian dimasukan kedalam file ASCI serta disimpan dalam format Minescape user defined (data format available in Mincom-Stratmodel ) menjadi dasar informasi  pemodelan.
·         Permukaan pemodelan menggunakan topografi dari SRTM
·         Setelah model Pertama selesai, kemudian dilakukan validasi lebih lanjut dari database dan korelasi lapisan batubara.
·         Interpretasi korelasi lapisan batubara dibantu dengan penampang dari model pertama yang telah dilakukan.
·         Coal intersection yang belum dikorelasi akan di beri kode lithologi  “CO” agar mudah diidentifikasi saat tahap korelasi selanjutnya.

Pemodelan yang dilakukan pada lokasi PT. Riyanta Jaya ini digunakan hanya untuk mendapatkan pola penyebaran umum lapisan batubara dengan data yang minimum. Dengan menggunakan interpretasi geologi dari data beberapa titik bor dan sebagian singkapan batubara mendapatkan gambaran pola penyebaran lapisan batubara dan dapat dilihat pada gambar peta.
Jumlah lapisan batubara dari hasil korelasi pada proses geomodeling ini sebanyak 6 lapisan batubara yaitu :
1.      Seam A (average thick 1 m)
2.      Seam B (average thick 1,5 m)
3.      Seam C (average thick 1,7 m)
4.      Seam D (average thick 3,4 m)
5.      Seam E (average thick 1 m)
6.      Seam F (average thick 1,8 m)
Seam A, seam B, seam E dan seam F merupakan hasil dari korelasi singkapan batubara yang dimasukkan kedalam database geologi.





Dari hasil korelasi yang dilakukan pada proses geomodel ini, tipycal struktur lapisan batubara mempunyai kemiringan berkisar antara 58 – 70° dan jurus perlapisan berarah dari Barat – Timur atau Barat Daya – Timur Laut. Sangat terlihat jelas pada gambar 5, kemiringan lapisan batubara semua lapisan/seam yang ada hampir tegak. Trench tipycal struktur yang berkembang pada lokasi PT. Riyanta Jaya, khususnya pada area yang telah dilakukan pemboran berdasarkan hasil pengukuran jurus dan kemiringan singkapan yang ditemukan.
Untuk memastikan hasil interpretasi dalam geomodel batubara PT. Riyanta Jaya ini perlu dilakukan pemboran rinci (detail) untuk memastikan kembali pola penyebaran lapisan tersebut sehingga mendapatkan nilai ekonomis dalam perhitungan cadangan batubara yang di lokasi PT. Riyanta Jaya.





2.4  Test Pit
In 2014, Riyanta excavated one test pit at RJ-OC05 outcrop with purpose to
investigate the coal seam thickness and orientation from the outcrop and to obtain un-
oxidised bulk sample for coal quality analysis.
The following observation and measurement from the test pit:
The coal is black, bright lustre, hard, and breaks with conchoidal fracture.
The coal is solid and non-coal partings is not observed in the pit.
The coal shows a rare presence of pyrite.
Strike and dip measurement on the coal roof measures N 50° E / 25° with an
apparent thickness of 4 m. Steep dip of the coal seam and space limitation of the
test pit do not permit an accurate thickness of the seam in the pit.
Face and butt cleat develops in the seam.
Riyanta obtained a 100 kg bulk sample from the test pit under the supervision of
Handiko personnel. The sample was carefully packed and sealed, then submitted to,
and analysed at Geoservices Facility, a certified coal laboratory in Balikpapan. The
sample was subjected to a full range of tests that includes proximate analysis,
ultimate analysis, ash fusion temperature, ash analysis and trace element and
petrography.


a.  Ash
The acceptable limit of ash content for coke manufacture is averagely 12% (air-dry
basis) whereas the reported ash content of Riyanta ranges between 5.2% and 7.4%
(air-dry basis), and therefore well below the limit. The low ash content indicates that
the coal recovery during mining could be achieved without washing process.
The projected ash content for the Riyanta product will be restricted due to data
limitation. However, the coal product should have good market acceptance with low
ash content that could be maintained at a level of <10.0%.
b.  Sulphur
Total sulphur ranges between 0.55% and 0.56% (air-dry basis). The sulphur level is
considered low for metallurgical or thermal coal use and should have good market
acceptance. The sulphur content appears to be similar to other coal projects in the
vicinity of the Riyanta concession.
c.  Volatile Matter
The volatile matters content of the coal is relatively high, ranging between 42.28%
and 42.5% on air-dry basis.
d.  CSN
The coal shows relatively moderate level of CSN (Crucible Swelling number) of 3. On
this basis, the coal could be evaluated, at least, semi-soft coking coal classification.
The CSN value of the coal appears to be deteriorated and lower than expected due to
coal weathering.
e.  Phosphorus
The coal has a low phosphorus content of 0.005% (air-dry basis). This level is
considered low and will be desirable for many buyers. In this instance, the average
level of 0.052% is commonly achieved by many Australian operations.
f.  Chlorine
Chlorine in coal ranges between 0.01% and 0.02% and considered low. Most power
plants require a low chlorine of less than 0.1 and the chlorine content of Riyanta coal
is well below the restriction value.
g.  Maceral Count
The coal sample shows a high vitrinite content of 93%. The value is similar to
Indonesian coking coals in Kalimantan Tengah. These coals are highly rated by coke
makers around the world. The high vitrinite content allows a small proportion of these
coals to be used to improve the coking properties of a coke oven blend and allow the
effective use of a poor quality coal.
h.  Mean Maximum Reflectance
The mean maximum reflectance of the coal is 0.63 with a maximum reflectance of
0.75. This value falls within bituminous coal classification that ranges between 0.6
and 1.7. However, Ro Max value of the coal sample appears low for the reported
vitrinite content (93.9%). The lower Ro Max might be due to the weathered coal as
the sample being near surface.
i.  Coking Properties
The 100-kg coal sample was tested for Gieseler Plastometer Fluidity test. The results
exhibit a maximum fluidity of 1,148 ddpm with a plastic range of 81°C that falls into
high-volatile coal classification.
j.  Ash Composition
The ash composition of the coal is excellent. The ash is generally high silica (SiO2 in
ash of 57.48%) and relatively low alumina (Al2O3 in ash of 35.20%). This will provide
a positive effect on the slag viscosity in a blast furnace. The ash is relatively low in
iron (Fe2O3 in ash of 2.85%), which will result in a positive impact on coke strength
after reaction, and the alkalis are relatively low.
k.  Hardgrove Grindability Index
The Hardgrove Grindability Index (HGI) of the coal is 46. This value is relatively
moderate due to the high vitrinite content and the moderate reflectance of the coal.
This indicates that the coal will be handled with ease and less potential to be friable.