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.
|