DISTRIBUTION OF SULFATE WATER IN GRASBERG BLOCK CAVE (GBC) MINE, PAPUA, INDONESIA

Jaka Satria Budiman; I Gde Basten; Hendri Silaen; Rahardian Ryan Ruthman; Fari Fathiardi Putra; Kinkin Sulaeman

doi:10.14203/risetgeotam2017.v27.440

DISTRIBUTION OF SULFATE WATER IN GRASBERG BLOCK CAVE (GBC) MINE, PAPUA, INDONESIA

Jaka Satria Budiman, I Gde Basten, Hendri Silaen, Rahardian Ryan Ruthman, Fari Fathiardi Putra, Kinkin Sulaeman

Abstract

Grasberg Block Cave (GBC) underground mine, which is operated by PT Freeport Indonesia, located at High Land of Papua which has intensity of rainfall (average 4000 mm/year) and causing water inflow through the fractured rock, and flowing inside the underground mine. The water occurrence inside the underground mine could be in seepage form and water flow from diamond drilling hole. Water seepage inside underground mine contain many chemical compounds such as sulfate (SO42-). Sulfate has ability to cause acid water and sulfate attack, which can be a problem for ground support existing. Water from seepages of existing drift during development were collected and sent to laboratory to obtain detail chemical information. By correlating with geological data (formation and its content), distribution of water sulfate can be known. In the ore body of GBC, sulfate water content is higher than other lithologies. These data can be used for long term ground support planning in the future.

Abstrak

Tambang bawah tanah Grasberg Block Cave (GBC) yang dioperasikan oleh PT Freeport Indonesia, berlokasi di dataran tinggi Papua mempunyai curah hujan yang tinggi (rata-rata 4000 mm/tahun) dan menyebabkan adanya aliran air melewati rekahan batuan dan mengalir menuju ke dalam tambang bawah tanah. Keberadaan air di dalam tambang bawah tanah dapat berupa rembesan dan aliran air yang mengalir dari dalam lubang pengeboran. Rembesan air di dalam tambang bawah tanah mengandung banyak senyawa kimia seperti senyawa yang memiliki sulfat (SO₄^2-). Sulfat mempunyai kemampuan untuk menyebabkan air asam dan sulfate attack, yang notabene bisa menjadi masalah terhadap ground support yang ada. Air yang terdapat di terowongan tambang bawah tanah, diambil dan dikirim menuju laboratorium untuk mendapatkan informasi kimia secara rinci. Dengan melakukan korelasi terhadap data geologi (formasi dan kandungan mineralnya), distribusi dari air sulfat bisa diketahui. Di dalam tubuh bijih utama GBC, air mengandung sulfat lebih tinggi dibandingkan dengan di area litologi lainnya. Data-data ini bisa digunakan untuk perencanaan pemasangan penyangga batuan di masa yang akan datang.

Keywords

Grasberg Block Cave, Sulfate Water, Underground Mine

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DOI: http://dx.doi.org/10.14203/risetgeotam2017.v27.440