Aplikasi Teknis Stabilitsasi/Solidifikasi Untuk Remediasi Timbunan Tailin Penambangan Emas Rakyat Menggunakan Fly Ash

Penambangan emas rakyat di Kulon Progo menghasilkan tailing yang mengandung merkuri. Pada penelitian terdahulu diperoleh data kadar merkuri tailing penambangan emas Kulon Progo sebesar 164-384 mg/kg. Di lokasi tambang emas tersebut terdapat tempat penimbunan tailing aktif (TPTA) dan Tempat penimbunan tidak aktif (TPTTA). TPTA adalah tempat penimbunan untuk tailing yang dihasilkan oleh penambangan emas rakyat yang masih aktif beroperasi. Tempat penimbunan tidak aktif (TPTTA) adalah lokasi penimbunan tailing penambangan emas rakyat yang sudah tidak beroperasi. Salah satu upaya remediasi timbunan tailing adalah teknik stabilisasi/solidifikasi (S/S). Penelitian bertujuan menentukan karakteristik tailing TPTA dan TPTTA serta menentukan komposisi optimum S/S tailing TPTA dan TPTTA menggunakan fly ash. Pengambilan sampel tailing dilakukan di lima TPTA dan di lima TPTTA, serta di satu lokasi kontrol yang tidak tercemar. Sampel diambil pada kedalaman 30, 60, dan 90 cm pada setiap lokasi. Karakteristik tailing yang dianalisis adalah total konsentrasi logam berat, pH, dan kadar air. Sampel tailing yang digunakan untuk pembuatan benda uji S/S dicampur secara homogen terlebih dahulu. Pembuatan benda uji menggunakan cetakan berbentuk kubus dengan panjang sisi 5 cm. Variasi rasio berat sampel dari TPTA : fly ash adalah 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80,10:90, 0:100. Sedangkan variasi rasio berat sampel dari TPTTA : fly ash (%) adalah 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, 0:100. Uji kuat tekan terhadap benda uji S/S dilakukan dengan Toorse Universal Testing Machine. Uji Toxicity Characteristic Leaching Procedure (TCLP) dilakukan terhadap benda uji S/S dengan metode US EPA 1311. ii Hasil penelitian menunjukkan bahwa kadar merkuri pada sampel TPTA sebesar 160-318 mg/kg dan pada sampel TPTTA sebesar 94-99 mg/kg. Total konsentrasi merkuri melebihi baku mutu PP No.101 Tahun 2014 yaitu sebesar 75 mg/kg. Nilai pH sampel TPTA sebesar 6,58 dan nilai pH sampel TPTTA sebesar 7,3. Kadar air pada sampel tailing sekitar 19,16-34,41%. Jenis tanah setempat merupakan campuran lempung dan lanau, yang juga salah satu bahan pozzolan yang baik untuk proses S/S. Hasil penelitian menunjukkan bahwa merkuri mampu terstabilisasi dan tersolidifikasi dengan baik. Nilai kuat tekan produk S/S TPTA dan TPTTA masingmasing sebesar 53 ton/m2 dan 107 ton/m2. Nilai kuat tekan tersebut memenuhi baku mutu menurut Keputusan Kepala Bappedal No.3 Tahun 1995 sebesar 10 ton/m2. Kadar merkuri dari kedua hasil uji TCLP produk S/S TPTA dan TPTTA adalah < 0,0005 mg/L. Nilai tersebut memenuhi baku mutu berdasarkan PP No.101 Tahun 2014, yaitu sebesar 0,05 mg/L. ========== Artisanal gold mining generates tailing residue which contains mercury. Results of the preliminary research showed that the tailing residue in artisanal gold mine in Kulon Progo contained mercury concentration of 164-384 mg/kg. There are two kinds of tailing dump sites in the public gold mine. These ares active tailing piling site (ATPS) and inactive tailing piling site (ITPS). ATPS is the tailing residue piling site of the public gold mine, which is still operated, whereas ITPS is tailing dumpsite which is not any longer use for tailing disposal. One of the efforts to minimize the impact of mercury in the tailing dump is by stabilization/solidification method. This research aimed to determine the characteristics of tailing residue in the ATPS and ITPS. Besides, this research will determine optimum composition of samples from the ATPS and ITPS using fly ash. Tailing samples were collected from five ATPS’s, five ITPS’s, and from a control location which was not contaminated by tailing residue. The samples were taken from 30, 60, and 90 cm depths. Heavy metal concentrations, pH, and moisture cotent of each sample were measured. Samples from each location were mixed thoroughly prior to S/S process. The S/S specimens were prepared using 5 cm cubic shaped mould cast. Composition variations between ATPS and ITPS tailing samples and fly ash were adjusted to 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, 10:90, and 0:100 w/w. The quality of S/S specimens was analyzed using compressive strength and Toxicity Characteristic Leaching Procedure (TCLP) tests. iv Compressive strength tes was performed usig Toorse Universal Testing Machine, whereas the TCLP test was conducted following US EPA 1311. Mercury concentrations in samples from the ATDS ranged from 160 to 318 mg/kg, whereas those from the ITDS were 94-99 mg/kg. These values exceeded the quality standards of the Government Regulation No.101/2014 of 75 mg/kg. The pH values of samples from ATPS and ITPS were 6.58 and 7.3 respectivey. The moisture contents of the tailing residue varied from 19.16% to 34.41%. The soil in the study area was classified as silty clay, which might support the binding mechanism during the S/S process. The compressive strength values of the S/S products of the ATDS and ITDS samples were 53 ton/m2 and 107 ton/m2 respectively. These values met the quality standards of the Head of Environmental Impact Control Agency (BAPEDAL) No. 3/1995 of 10 ton/m2. The result of TCLP test for mercury of the S/S products of ATDS and ITDS samples were below 0.0005 mg/L. This value met the quality standards of Government Regulation No.101/2014 of 0.05 mg/L