Penelitian mengenai kadar mineral atau unsur lain dalam endapan nikel seperti MgO dan SiO2 pada bijih nikel kadar rendah saat ini masih sangat jarang dilakukan, sehingga diperlukan penelitian untuk menganalisis persentase kadar MgO dan SiO2 pada endapan nikel kadar rendah khususnya nikel kadar rendah yang berasal dari Kabupaten Kolaka dan Kabupaten Kolaka Utara. Penelitian ini bertujuan untuk menganalisis dan membandingkan hasil pengujian XRF pada sampel nikel Kabupaten Kolaka dan sampel nikel Kabupaten Kolaka Utara. Selain itu, penelitian dilakukan dengan observasi langsung di lapangan, tepatnya di Stockpile yang terdapat di salah satu perusahaan tambang nikel yang berada di Kabupaten Kolaka dan Kabupaten Kolaka Utara. Hasil penelitian ini dapat disimpulkan bahwa kandungan MgO sampel nikel dari Kabupaten Kolaka menunjukkan nilai persentase yang lebih kecil yaitu 11,22%, dibandingkan sampel nikel dari Kabupaten Kolaka Utara yang mencapai 18,49%. Sedangkan kadar SiO2 sampel nikel yang berasal dari Kabupaten Kolaka menunjukkan nilai persentase yang lebih tinggi yaitu sebesar 44,00%, dibandingkan kadar SiO2 pada sampel nikel yang berasal dari Kabupaten Kolaka Utara yang berkisar 36,74%.Ditinjau dari tipe endapan untuk pembentukan laterit, Kolaka terindikasi sebagai tipe Oxides Deposit dan Kolaka Utara terindikasi sebagai tipe Hydrous Silicate Deposit.

The effects of reinforcement system on pillars were tested in laboratory, using three types of pillars with different strengths. The tests were performed using the UCS machine, to test pillar without reinforcement, pillar with rock bolt reinforcement, pillar with shotcrete reinforcement and pillar with the combination of both rock bolt and shotcrete reinforcement. Uniaxial compressive strength (UCS) testing aims to determine the effects of the reinforcement system on pillar strength. The results of this study indicate that the reinforcement system on high strength pillars causes a strength increase of 14.93% on pillar with rock bolt reinforcement, 21.45% on pillar with shotcrete reinforcement and 34.67% on pillar with combination of rock bolt and shotcrete reinforcement. On medium strength pillars, reinforcement installation shows a strength increase of 16.27% on pillar with reinforced rock bolt, 19.83% on pillar with reinforced shotcrete and 44.40% on pillar with combination of rock bolt and shotcrete reinforcement. Likewise, on low strength pillars, reinforcement installation causes a strength increase of 13.13% on pillar with reinforced rock bolt, 36.21% on pillar with reinforced shotcrete and 53.85% on pillar with combination of rock bolt and shotcrete reinforcement. The results of laboratory testing and numerical modeling indicate that the increase in strength occurs because the horizontal displacement on the surface of the pillar wall is detained by shotcrete and faceplate on rock bolt, so that the pillar seems to have confining pressure throughout the pillar wall surface, which is called as equivalent confining pressure.

No abstract