Spesiasi Limbah Merkuri pada Tailing Tambang Emas Rakyat dari Kecamatan Kokap, Kabupaten Kulon Progo dan Stabilisasi Merkuri dengan Penambahan Sulfur dan Sulfida

Latif, Rezki Amalia (2018) Spesiasi Limbah Merkuri pada Tailing Tambang Emas Rakyat dari Kecamatan Kokap, Kabupaten Kulon Progo dan Stabilisasi Merkuri dengan Penambahan Sulfur dan Sulfida. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Proses amalgamasi untuk ekstraksi emas dalam kegiatan pertambangan menghasilkan tailing mengandung merkuri yang berpotensi mencemari lingkungan. Penelitian ini bertujuan untuk: (1) menentukan komposisi merkuri dalam bentuk unsur dan ionik pada tailing tambang emas dari Kabupaten Kulon Progo berdasarkan metode kimiawi, (2) menentukan spesies merkuri ionik pada tailing dengan metode pemodelan Visual MINTEQ, (3) menentukan efisiensi stabilisasi merkuri dalam tailing dengan metode presipitasi penambahan sulfur dan sulfida. Penelitian ini menggunakan komposit dari 3 titik pengambilan sampel tailing pada tiga kedalaman berbeda, yaitu 30 cm, 60 cm, dan 90 cm. Spesiasi merkuri dengan metode kimiawi dilakukan dengan metode volatilisasi menggunakan gas nitrogen dan penangkapan gas merkuri (Hg°) dengan larutan KMnO4. Adapun spesiasi merkuri ionik (Hg2+) dengan pemodelan Visual MINTEQ menggunakan data konsentrasi merkuri ionik, pH, kekuatan ionik, dan suhu tailing. Konsentrasi merkuri ionik diukur dengan mercury analyzer, nilai pH diukur dengan pH meter, kekuatan ionik dihitung dengan total konsentrasi ion dalam tailing, dan suhu diukur dengan termometer. Proses penambahan sulfur pada penelitian presipitasi merkuri dilakukan dengan penambahan bubuk sulfur dengan dosis 1:100 (massa sulfur: massa tailing). Kemudian dilakukan pengocokan pada tailing yang telah bercampur bubuk sulfur selama 10 menit. Sementara pada proses penambahan sulfida, ditambahkan larutan Na2S 0,67% pada tailing. Kemudian dilakukan pengocokan selama 5 menit dan dibiarkan selama 1 hari. Hasil spesiasi merkuri menunjukkan bahwa tailing mengandung merkuri dalam bentuk Hg0 dan Hg2+. Persentase Hg0 pada tailing di kedalaman 30 cm, 60 cm, dan 90 cm berturut-turut adalah 74,7%, 71,6%, dan 76,5% dan konsentrasi Hg2+ sebesar 25,3%, 28,4%, dan 23,5%. Hal ini menunjukkan bahwa tailing mengandung Hg0 yang lebih dominan dari Hg2+. Berdasarkan hasil pemodelan Visual MINTEQ 3.0, Hg2+ membentuk senyawa merkuri kompleks, seperti kompleks kloro, hidroksida, sulfat, dan lain-lain. Senyawa merkuri kompleks yang paling dominan pada ketiga sampel tailing adalah HgCl_4^(2-). Hasil TCLP untuk penambahan bubuk sulfur pada kedalaman 30, 60, dan 90 cm masing-masing adalah 6,1 x10-4 mg/L, 1,8 x10-4 mg/L, dan 4,6 x10-4 mg/L, dengan efisiensi pengikatan merkuri-sulfida sebesar 99,97-99,99%. Adapun hasil TCLP untuk penambahan natrium sulfida pada masing-masing kedalaman adalah 1,7 x10-4 mg/L, 2,5 x10-4 mg/L, dan 1,1 x10-3 mg/L dengan efisiensi pengikatan merkuri-sulfida sebesar 99,97-99,99%. Hasil ini menunjukkan bahwa penambahan sulfur dan natrium sulfida menghasilkan endapan merkuri sulfida dengan kelarutan sangat rendah. =================================================================================================== Amalgamation process in public gold mining activities generates tailings, which contain high amount of mercury. This cause environmental pollution because mercury elemental has easily volatilized at environmental temperature and highly toxic. This research aimed to: (1) determine elemental and ionic composition of mercury waste from a public gold mine tailing, (2) determined the species of ionic mercury in tailing based on Visual MINTEQ modeling method, and (3) determine efficiency of the mercury waste stabilization using sulfur and sulfide addition methods. This research used samples from three tailing piles in public gold mining site in Kokap District, Kulonprogo Regency, Indonesia. The samples were collected from 30, 60, and 90 cm depths. Samples of similar depths were composited. Mercury speciation was carried out using chemical method. Elemental mercury (Hg0) in the samples was volatilized using nitrogen gas, and the Hg0 gas was absorbed in KMnO4 solution. The ionic mercury (Hg2+) was trapped in KCl solution, or remained in the sample. Mercury concentrations were measured using mercury analyzer. Ionic mercury speciation with Visual MINTEQ modeling used data of total ionic mercury concentration, pH, ionic strength, and tailing temperature. The ionic mercury concentration measured by mercury analyzer, the pH value measured by the pH meter, the ionoc strength measured by total ions concentration in tailing, and the temperature measured by a thermometer. Mercury stabilization effectiveness was evaluated using the Toxicity Characteristic Leaching Procedure (TCLP). The addition of sulfur powder using 1:100 (w/w) ratio of sulfur and tailing. The addition of sodium sulfide using sodium sulfide 0.67%. Results of mercury speciation showed that the tailings were dominated by Hg0. The percentages of elemental Hg0 in the tailings at 30, 60, and 90 cm depth were 74.7%, 71.6%, and 76.5% respectively, whereas the percentages of Hg2+ were 25.3%, 28.4%, and 23.5%, respectively. From Visual MINTEQ modeling 3.0 showed that Hg2+ was forming complex mercury compounds, as chloro, hydroxide, sulphate complexs, etc. The most dominant of complex mercury compound on three samples of tailings was Hg〖Cl〗_4^-. The mercury was precipitated using sulfur powder and sodium sulfide solution to produce black-colored compounds. The TCLP results for sulfur powder addition in 30, 60, and 90 cm depth of samples were 6.1 x10-4 mg/L, 1.8 x10-4 mg/L, 4.6 x10-4 mg/L, respectively, with mercury-sulfide binding efficiencies of 99.97-99.99%. On the other hand, the TCLP results for sodium sulfide addition in the corresponding depths were 1.7 x10-4 mg/L, 2.5 x10-4 mg/L, 1.1 x10-3 mg/L, respectively, with mercury-sulfide binding efficiencies of 99.97-99.99%. These results show that both additions of sulfur and sodium sulfide produced mercury sulfide precipitate with very low solubility.

Item Type: Thesis (Masters)
Additional Information: RTL 363.738 4 Lat s-1
Uncontrolled Keywords: Mercury, Precipitation, Speciation, Sulfide, Sulfur, Tailing
Subjects: T Technology > TA Engineering (General). Civil engineering (General) > TA749 Soil stabilization
T Technology > TD Environmental technology. Sanitary engineering > TD878.47 Soil remediation
Divisions: Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Environmental Engineering > 25101-(S2) Master Thesis
Depositing User: Rezki Amalia Latif
Date Deposited: 27 Mar 2018 03:22
Last Modified: 23 Sep 2020 04:50
URI: http://repository.its.ac.id/id/eprint/50217

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