Estimasi Sumberdaya Bauksit Menggunaan Geostatistik Dengan Metode Ordinary kriging Di PT Sandai Inti Jaya Tambang ( SIJT ) Desa Sandai Kiri, Kecamatan Sandai, Kabupaten Ketapang, Provinsi Kalimantan Barat

Abstract

Abstract. Calculation of resources  an important role in reducing the risk of determining the amount and facilitating commercial exploitation of a deposit of minerals. Good resource calculation can help determine the investment to be invested. In this case the method used to calculate resources is the geostatistical method with the ordinary kriging approach. The choice of this method is because the geostatistical method can predict the value of the surrounding area that does not have real data. So that predictions can be made that are close to the actual spread value. There are 335 test well points in an area of 8.3 ha with an average distance between the test well points, which is 50m. Sampling of bauxite is carried out at 1m interval and stopped when it has reached the clay.For bauxite with a high grade, which contains Al2O3 content> 45%; SiO2 <10%, medium grade content of Al2O3> 45%; SiO2 <15%, and low grade Al2O3 content <45%; SiO2 <15%.Unwashed bauxite (UBX) total tonnage in block 7 area is 5,877,446 tons. Where after multiplied by the concretion factor, the total tonnage washed bauxite (WBX) was 3,044,517 tons. Resources in block 7 are included in the category of measured resources, with a Relative Kriging Standard Deviation of 27%.

Keyword : Bauxite, Ordinary kriging, Resource

Abstrak. Kegiatan penambangan bauksit di PT SIJT pada blok 6 hampir selesai ditambang, sehingga perlu direncanakan kegiatan penambangan yang baru. Untuk dapat melakukan perencanaan pada area blok 7, maka perusahaan perlu mengestimasi nilai sumberdaya di blok tersebut.Terdapat 335 titik sumur uji pada luasan area 8,3 Ha dengan jarak rata-rata antara titik sumur uji yaitu 50m. Pengambilan contoh bauksit dilakukan dengan interval 1m dan dihentikan apabila telah mencapai lempung. Berdasarkan klasifikasi dari perusahaan, bauksit dengan klasifikasi high quality apabila kadar Al₂O₃ > 45% dan SiO₂ < 15%. Sebaliknya untuk bauksit low quality apabila kadarAl₂O₃ <  45% dan SiO₂ > 15%.  Dari data komposit hasil sumur uji diarea blok 7 PT Sandai Inti Jaya Tambang (SIJT) arah sebaran bauksit dengan kadar Al₂O₃ > 45% dan SiO₂ < 15% cenderung kearah tenggara. Sedangkan untuk sebaran kadar Al₂O₃ dengan kadar < 45% dan SiO₂ > 15% cenderung kearah barat laut.Total tonase unwashed bauxite (UBX) diarea blok 7 yaitu sebesar 6.269.276 ton dan total tonase washed bauxite (WBX ) sebesar 3.247.485 ton. Sumberdaya di area blok 7 termasuk kedalam kategori sumberdaya terukur, dengan nilai RKSD (Relative Kriging Standar Deviation) sebesar 27%.

Kata kunci : Bauksit, Ordinary kriging, Sumberdaya.