Jurnal Puslitbang tekMira (Teknologi Mineral dan Batubara)
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MODELS FOR PHYSICAL AND NUMERICAL SLOPE FAILURE OF LOOSE SAND UNDER DYNAMIC LOADING
No full textExcessive vibration that causes damage to model the medium such as mine slope can physically and numeri- cally be modelled. The slope of this study simply represents the actual view of the slopes that has a smaller size than the actual one, while the numerical model is relates to a mathematical form of slope condition that based on physical and mechanical data of the medium. The slope failure has experimentally been built several variations. Effect of vibration is echieved by connecting the models into the vibration instrument with bearing that can horizontally move free in line within the determined track. The instrument is attached to a spring that can pull the model to side out. The spring is placed in an iron frame. Proviously, the slope has been formed in critical condition one (angle of 30°). Physical model and laboratory test results were used as an input for numerical modelling of the slope failure. Based on the numerical analysis, the SRF was 0.47 for D equal to 2 cm g around 0.0025. If the g’s were around 0.0057 and 0.0088, the obtained SRF for both g’s were 0.44 and0.41 respectively. While the D of 4 cm and g of 0.0024 came the SRF of 0.54, the g of 0.0064 derived the SRF of 0.48, and the g of 0.0106 obtained the SRF of 0.44. For D equal to 2 cm and g 0.0024, 0.0106; the obtained SRF was 0.54, 0.48 and 0.44 respectively. Increasing the D to 6 cm within variation of g from 0.0025, 0.0062 and 0.0106, the SRF was 0.51, 0.48 and 0.44 respectively. It is assumed that there is a correlation between the thickness of quartz sand layer and the decrease of SRF value. The correlation also occurs between the increase in vibration (g value) and the SRF
SEPARATION OF WARINGIN HEAVY MINERAL SANDS FROM CENTRAL KALIMANTAN
No full textCentral Kalimantan has grown rapidly as a heavy mineral producer. Zircon is the main mineral concentrate, but other valuable heavy minerals are present. With particular interest in the upgrading of zircon and its recovery, tekMIRA’s laboratory has developed benefi ciation steps of heavy minerals to produce marketable zircon con- centrate. Using a series of concentration equipments that includes spiral concentrator, shaking table, magnetic separator and electrostatic separator; the content of zircon in the end concentrate reaches up to 65% ZrO2
THE USE OF SUB-BITUMINOUS COAL IN COMBINATION FIRING FOR TILE, BRICK AND LIMESTONE BURNING
No full textCombination fi ring of fi rewood and bituminous coal was recommended to reduce fi rewood consumption and to increase energy effi ciency. However, bituminous coal deposit in Indonesia has been depleted, therefore the use of sub-bituminous coal for combination fi ring should be promoted. In this work the use of sub-bituminous coal for combination fi ring was investigated in tile, brick and limestone burning. The calorifi c value of the sub-bituminous coal was only 4.6% lower than the value of bituminous coal. The increase in energy effi ciencies using sub- bituminous coal were lower than that of using bituminous coal. Compared with the use of fi rewood alone the increase in energy effi ciencies using combination fi ring of fi rewood and sub-bituminous coal in tile, brick and limestone burning were 45.7, 53.6 and 28.3% respectively. While, in the use of bituminous coal, the increase were 70.8, 75.1 and 91.9% respectively. In the combination fi ring, the fi rewood substituted by coal using sub-bituminous coal were smaller than the use of bituminous coal, i.e. for tile, brick and limestone burning, using sub- bituminous coal the substituted fi rewood were 47.7, 44.6 and 45.0% respectively while using bituminous coal there were 54.5, 50.0 and 66.0% respectively. It was revealed that the superiority of bituminous coal come from its higher content of high hydrocarbon volatiles which produced higher radiative fl ame resulting more effi cient burning processes
EXTRACTION OF POTASSIUM FROM FELDSPAR AND LEUCITE BY TWO DIFFERENT ACTIVATION METH- ODS: MECHANICAL ACTIVATION (MILLING) AND HIGH TEMPERATURE ACTIVATION (ROASTING)
No full textOne of the most important elements in fertilizers is potassium that can be devided from felsdpar and leucite minerals. Both are composed of various minerals and need to be separated from its impurities to get the desired minerals. In this research, test of mineral activation was performed using two different methods, namely mechanical activation (milling) and activation that used high temperature (roasting). The results were followed by potassium extraction process through leaching using sulfuric acid 6 N, 20% solids for 2 hours without heating. The best result was obtained from a 60-hour mechanically, activated leucite in leaching condition and conducted without heating. To evaluate potassium dissolution with soil when applied as fertilizer, the test of solubility in citric acid-the analogy of acid humus within soil-was conducted. The product with the best solubility was obtained from a 60-hour milling process. The results show that leucite, activated by milling process, was more easily extracted its potassium. However, further research is still needed to optimize the leachability of potassium extraction
PREDIKSI NILAI KUAT TEKAN UNIAKSIAL BATUAN PENGAPIT BATUBARA MENGGUNAKAN DATA ULTRASONIK DI KABUPATEN MUSI BANYUASIN SUMATERA SELATAN
No full textDukungan data geomekanika sangat dibutuhkan dalam merancang gasifier, analisis dan pemodelan pada gasifikasi batubara bawah tanah (underground coal gasification-UCG), baik yang berasal dari uji langsung (in-situ) maupun uji laboratorium. Salah satu data pengujian laboratorium yang cukup penting untuk mengevaluasi kondisi batuan di lokasi UCG adalah uji kuat tekan uniaksial (uniaxial compressive strength test-UCS). Uji ini membutuhkan dimensi percontoh spesifik yang tidak digunakan untuk uji laboratorium lain seperti uji geser langsung, triaksial atau brazzilian. Karena itu, untuk optimalisasi pengujian percontoh harus dipilih secara selektif karena untuk mendapatkan percontoh dari pemboran inti sangat sulit, memakan waktu dan sangat mahal. Salah satu cara untuk mengoptimalkan pemanfaatan percontoh adalah dengan melakukan korelasi dengan hasil uji lain yang memiliki output yang sama. Pada penelitian ini telah dilakukan korelasi antara uji UCS yang bersifat merusak (destructive) dengan uji ultrasonik yang bersifat tidak merusak (non-destructive), relatif murah, cepat, mudah dan percontoh dapat digunakan lagi untuk uji yang lain. Sebanyak 89 uji UCS dan ultrasonik telah dilakukan untuk memperoleh tiga korelasi empiris nilai UCS dan ultrasonik yang berasal dari percontoh batuan pengapit batubara (batu lempung, batu lanau dan batu pasir). Korelasi ini dapat digunakan untuk memprediksi nilai UCS secara empiris di lokasi telitian yaitu di desa Macang Sakti, Kecamatan Sangadesa, Kabupaten Musi Banyuasin, Propoinsi Sumatera Selatan. Korelasi tersebut dihasilkan dari persamaan polinomial orde 2 dan 3. Untuk batu lempung nilai sc dapat diperoleh dari UCScls = (2 x 10-10)Vp3-(5 x 10-6)Vp2+ 0,0404Vp - 20,986 dengan nilai R2 =0,9087. Untuk batu lanau nilai sc dapat diperoleh UCSsis = (3 x 10-6)Vp2+ 0,0051Vp + 9,8665 dengan nilai R2 = 0,8953 dan nilai sc batu pasir dapat diperoleh dari UCSsas = -(7 x 10-7)Vp2 + 0,0467Vp - 41,484 dengan nilai R2 = 0,8864.
