Beneficiation and Bauxite Mineralogy - Ketapang Kalbar [PDF]

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Beneficiation and Mineralogical Study of Bauxite Deposits in Ketapang, West Kalimantan for Optimum Bayer Alumina Refinery Process



Robby I. Rafianto1, Henry A. Cahyono2, Abimanyu Yudhaswita2, Alan Matano3, Yusni Marta2 1



PT. CITA MINERAL INVESTINDO Tbk. PT. HARITA PRIMA ABADI MINERAL 3 HARITA EXPLORATION



2



Abstract Bauxite is the principal raw material for the production of alumina and aluminium metal. The exploration and mining activities for Bauxite deposits are known in Indonesia since pre-World War II. A smelter grade alumina (SGA) refinery is built in Ketapang Regency, West Kalimantan by PT. Well Harvest Winning (WHW) as a purpose of increasing the value-added to bauxite mineral through domestic Bayer alumina processing. The specification of certain bauxite quality is required by WHW and a beneficiation and mineralogical study is required to meet metallurgical criteria that support economic Bayer refinery processing. The bauxite deposits in Ketapang are a lateritic blanket of weathering product from Early to Late Cretaceous of granite–monzonite-diorite plutonic and volcanic series which are rich in alumino-silicate minerals. The combination of PSD, XRF, wet chemistry and semi quantitative XRD mineralogical data is effective to assess grain sizes and mineralogical behaviors during screening and washing process. At screen size +1 mm boundary the values of total Al 2O3, available Al2O3, LOI and Tal2O3/TSiO2 ratio are significantly increased while TSiO2, RSiO2 and Fe2O3 values are decreased. The identified minerals by XRD in each fraction size are gibbsite, goethite, magnetite, hematite, anatase, quartz, kaolinite, illite and paragonite. The principal bauxite mineral found is only gibbsite while boehmite and diaspore are not identified. The 2014 and 2016 beneficiations studies shown that the washing and screening processes are still not optimum in separating fine grained gibbsite and interlocked kaolinite minerals. For long-term economic benefits, mapping of bauxite ore types are quite important, then the beneficiation plant at mine fronts can be optimized and impacting for low cost Bayer processing.



1. Introduction Bauxite was first discovered by French geologist Pierre Berthier in 1821, near the village Les Baux-deProvences in the French Alpilles (Gendron et al, 2013). It is a principal raw material for the production of alumina and aluminium metal. In Indonesia, the initial discovery of bauxite in Southeast Bintan was made in 1924 (Bemmelen, 1940 in Rodenburg, 1984). Bauxite production in Indonesia was started in 1935 by the Netherlandsch Indische Bauxite Exploitatie Maatschappij (Rodenburg, 1984) and continue by several companies until now. The major bauxite deposits in Indonesia are reported from Riau Archipelago and West Kalimantan. The geology and genesis of Indonesian bauxite deposits were described by Bemmelen (1949), Rodenburg (1984), Surata et al (2010) and Toreno et al (2012).



From an industrial perspective, bauxite is a raw material that can be economically processed to high purity alumina (>98% Al2O3) in the Bayer process. A mandatory domestic minerals processing is required under Law No. 4 of 2009 in Indonesia. Under this obligation, a smelter grade alumina (SGA) refinery is built in Ketapang Regency, West Kalimantan by PT. Well Harvest Winning (PT. WHW) as a purpose of increasing the value-added to bauxite mineral through domestic processing. PT. WHW requires consistent bauxite supply from several mines in Ketapang under agreement with PT. Cita Mineral Investindo Tbk. (CITA) as a bauxite miner. Currently CITA is mining and beneficiates the bauxite ore through the washing plant to produce metallurgical grade bauxite (MGB). A certain number bauxite deposits have been found to meet the stringent physical and chemical specifications expected of smelter grade alumina in CITA Air Upas and Sandai mine concessions. A preliminary beneficiation study was made in 2014 (LAPI ITB) with samples taken from mine faces, mine washed bauxites and tailings. The 2016 study is covering more representative areas based on drillhole samples. The specification of certain bauxite quality is required by WHW and a beneficiation and mineralogical study is required to meet metallurgical criteria that can support economic Bayer refinery processing. This paper is a compilation and more focus on beneficiation and mineralogical assessment in Air Upas Sandai areas by CITA geologists to investigate bauxite specifications required for Bayer process under PT. WHW operation. 2. The Bayer Process Production of aluminium metal from bauxite is a two stage process. The first stage involves the refining of bauxite ore through the Bayer process and resulting in the production of alumina. The second stage involves the electric reduction of alumina to aluminium metal through the Hall-Heroult Process. This paper is focus only on the alumina production through the Bayer Process. The Bayer process is the principal method for production of alumina from bauxite worldwide. The Bayer process, patented in Germany by Karl Joseph Bayer in 1888, exploits the relatively high solubility of aluminium oxide minerals in hot caustic soda solution. Separation of the insoluble phases, followed by gibbsite precipitation and calcination of the gibbsite to alumina (Smith, 2008). Operations with a red background represent those involving either the bauxite or mud, and thus represent the socalled “red side” of the Bayer Process (Fig. 1). Operations with white background relate to processes in the absence of these solid materials, and represent the so-called “white side” operations (Smith,2008). The actual processing conditions, such as the leach temperature, digestion and soda caustic consumption are greatly influenced by the type of bauxite to be processed (Hill and Sehnke, 2006). The ideal bauxite characteristics (MGB) for Bayer plant feed are listed in Table 1. Certain features of bauxite deposits control the efficacy of the Bayer Process. The most important are the relative amounts of the alumina-bearing minerals and the presence of deleterious minerals which also react with caustic soda (Gow and Lozej, 1993). The principal aluminium hydroxide minerals found in varying proportions within bauxite are gibbsite Al(OH) 3 and the polymorphs boehmite and diaspore, both ALO(OH) (Hill and Sehnke, 2006). The trihydrate gibbsite is most easily soluble in caustic soda requiring a digestion temperature of no more than 140 o C. On the other hand, the satisfactory solubility of boehmite is normally obtained above 200 o C, while diaspore is even more intractable, requiring temperatures of the order of 300 o C (Andrews, 1984). Other minerals in the ore which react with the caustic soda such as kaolinite clays and fine-grained quartz, cause caustic soda losses in the Bayer



Process. Two to three tonnes of bauxite, depending on its composition, are required to produce one tonne of alumina (Fig. 2). The cost of bauxite is a multiple of the Bauxite Consumption Factor and the unit cost of bauxite, and is a major cost item at most alumina plants. Bauxite consumption factor can be reduced by increasing alumina recovery during processing (Chin, 1984). The typical major cost items at most alumina plants is shown in Fig. 3. The definition of terms used in bauxite and alumina industry listed in table 2 3. Geological Settings 3.1 Regional Geology The island of Borneo (or Kalimantan of Indonesian part) presently lies upon the southeastern margin of the greater Eurasian plate. It is bounded to the north by the South China Sea marginal oceanic basin, to the east by the Philippine Mobile Belt and the Philippine Sea Plate and to the south by the Banda and Sunda arc systems. It is bounded to the west by the Sunda Shelf and ultimately by Paleozoic and Mesozoic continental crust of the Malay Peninsula. The Greater Kalimantan Block is surrounded to the north, east, and south by plate boundaries and arc systems which are presently active or which have been active during the Tertiary and it is bounded to the west by an underexplored shelf region which possibly conceals a terrane boundary (Darman & Sidi, 2000). Kalimantan can be divided into several roughly E-W trending tectonic provinces (Fig. 4). The northern portion of the island is dominated by the Cretaceous and Eocene to Miocene Crocker-Rajang-Embaluh accretionary complex. This consists primarily of turbidites which were being shed northeastward (present day coordinates) off of the Schwaner and younger volcanic arcs into a paralic to deep marine trench basin. These sediments were imbricated, deformed, and weakly metamorphosed during Cretaceous and Tertiary subduction and finally were intruded by late stage and post subduction intrusions of the Oligo-Miocene Sintang Group. A core of Paleozoic or older continental crust metamorphic rocks in the SW part of the island. The metamorphic rocks are intruded by biotite granite which yields K-Ar ages from Permian to Late Triassic. Many of the granitic rocks contain a strong foliation, and the Late Triassic ages are obtained from biotites from deformed rock The Permian dates come from hornblende crystals from undeformed regions of the granites or from amphibolite en-claves. The older ages are interpreted as minimum intrusive ages and the Middle to Late Triassic ages as the deformation age of the suite (Darman & Sidi, 2000). According to geological maps of Kendawangan (Sudana et al., 1994), Ketapang (Rustandi & Keyser, 1993) and Pontianak/Nangataman (Sanyoto and Pieters, 1993) sheets made by Geological Research and Development Centre of Indonesia, the concession area has a several formations consist of Laur Granite, Sukadana Granite, Kempari Sandstone, Kerabai Volcanics, Sintang Intrusives and Alluvial Deposits which classified as follows (Fig. 5): Laur Granite (Kll): hornblende–biotite monzogranite, rare biotite syenogranite and biotite–hornblende granodiorite Sukadana Granite (Kus): monzogranite, syenogranite, quartz monzonite, quartz syenite, alkali feldsfar granite, and rare granodiorite, tonalite, quartz diorite. Rocks contain variable amounts of biotite and hornblende and occasionally clinopyroxene and alkali amphibole



Kempari Sandstone (Kuke): quartz arenite and lithic arenite Kerabai Volcanics (Kuk): andesite, dacite and basalt lava, lava breccia, pyroclastic and small intrusives Sintang Intrusives (Toms): porphyritic andesite Alluvial (Qa): mud, sand, gravel and plant matters During the Early Permian - Late Triassic, the oldest rock in the region, metamorphic rocks were formed from regional metamorphism in shallow marine sedimentary rocks with varying degrees of metamorphic. At the Jurassic - Cretaceous, sedimentation process occurs within the shallow sea near the coast and paralic environment. At the Late Jurassic, two intrusions were occurred namely Belaban granite and Sukadana granite that cut the metamorphic rocks. Furthermore during the Cretaceous – Paleocene, there were 2 magmatism events have been taken place in the Early Cretaceous, as follows: Laur and Sukadana granites, and Sangiang granite. Kerabai volcanic rocks are co-magmatic with those granites, Bunga basalt as well as mafic and felsic dikes are widespread cut the granites. The whole process magmatism reflects the transition between tectonic compressions with stretching process. In the process there is an intrusion granite tectonic compression associated with subduction in the Lower Cretaceous, is the stretching process is still ongoing process late magmatism, where the rocks appear intrusion Sintang and volcanic plugs during the Oligocene - Miocene. The occurrence of intrusion Sukadana Granite conjunction with the appointment process, where the sedimentary rocks also come up so that in some sedimentary rocks are folded with a slope of between 300 to 700.



3.2 Local geology of bauxite occurences The bauxite deposits in all of the prospects are lateritic blanket of weathering products from granitemonzonite-diorite series of plutonic petrogenesis in West Kalimantan. These rocks are acidic igneous rocks that rich in alumino-silicate minerals. Mineralised areas are prominent along the marshy flanks of these igneous suites at the west and south east of the island. Based on petrographic analysis, the bauxite laterites host rocks in CITA mine concessions are consist of quartz-monzonite, quartz-monzodiorite, biotite monzonite, granodiorite, diorite and breccia with intermediate composition (NickelPhil, 2012). Bauxites mainly occur in tropical zones that are subjected to intense weathering conditions where oxidations and water saturation is high. Such conditions enable the dissolution of the kaolinite and the precipitation of hydrous alumina silicate in the weathering process. One of the main factors in forming good bauxite laterite is geomorphology aspects. The slope of the landform plays an important part in bauxite laterite formation intensity. Flatter slope will facilitate the surface water to infiltrate easier, thus makes the weathering process work intensively. Weathering process is the main process to form a bauxite laterite enrichment. On the contrary, the high slope will facilitate the run-off water, means less water infiltrate the soil or the rock. In turn, does not facilitate the weathering process to form the bauxite laterite. The triangular variation diagrams of Al2O3-SiO2-Fe2O3 are showing the degree of lateritization, mineral control and bauxite classifications. Fig. 6 from Air Upas area indicates that Al 2O3-rich composition is



indicative of a higher degree of lateritization while SiO 2-rich samples experienced weak lateritization (Meyer et al. 2002 in Gu et al., 2013). Based on mineralogical classification by Aleva, (1994 in Gu et al., 2013). The moderate to strong lateritization samples in Fig. 5 have correlations with classification of high grade bauxite – bauxite – kaolinitic bauxite and ferritic bauxite (Fig. 7) and their distributions in Air Upas are shown in Fig. 8.



4. Sampling and analytical methods For this mineralogical study, a test work package is conducted on bauxite resources from 31 twinhole drilling samples accros the project areas of Air Upas and Sandai. The test work includes: a. Particle Size Distribution (PSD) at 8 screen sizes at the wet stage and dry weight. The wet stage is relatively equal with bauxite washing process. b. Assaying in each fraction using: - XRF for TAl2O3, TSiO2, Fe2O3, TiO2 - Wet Chemistry + Bomb digest calorimeter for RSiO2, Av Al 2O3 - Gravimetry for LOI c. Mineralogy Study at composite fraction size by semi quantitative XRD analyses In 2014 CITA made a preliminary beneficiation study (LAPI ITB, 2014), the samples were taken from unwashed mine front, washed bauxite product and tailing. All data from 2014 and 2016 studies were compiled and analyzed by Kadarusman (2016) as CITA principal consultant for Bauxite exploration. 5. Test Work Results 5.1. Particle Size Distribution Analyses Bauxite drillhole samples were collected in each meter. Every samples was weight in wet stage and dry stage at 105°C to get moisture content (MC). Samples within one hole were composited and homogenized to get significant weight for Particle Size Distribution (PSD) testwork. Each composited sample is about 10 – 15 kg of dry sample from representative bauxite horizon of each drill hole. The PSD testwork conducted in wet stage, and reducing from initial of 18 screens to 8 screens for effectiveness of the testwork. The screen sizes are various from 50 mm to 0.3 mm. Based on PSD analyses, it is very clear that the bauxite size from Air Upas and Sandai areas are divided into two major populations with boundary of 1mm screen size. The individual fraction retained weight (%) analyses are supporting this evidence. If fine grained removed with boundary of 1 mm, the retained weight (%) recovery is about 60% (Fig. 9 and Fig. 10). This figure can be identical with the Concretion Factor (CF) of washed bauxite. 5.2. XRF and Wet Chemistry This testwork is combining XRF, wet chemistry and PSD data. Each fraction of PSD data was analyzed by XRF and wet chemistry for Total TAl2O3, available Al2O3, Total TSiO2, Reactive RSiO2, Fe2O3, MgO, P2O5, TiO2 and Loss on Ignition (LOI).



The combined data for average Air Upas and Sandai are shown in Fig. 11 and Fig. 12. From both Air Upas and Sandai Figues, there are connections between PSD, XRF and wet chemistry. At screen size +1 mm boundary the values of Total Al2O 3 (Tal2O3), available Al2O3 (AA), LOI and Tal2O3/TSiO2 ratio are significantly increased while TSiO2, RSiO2 and Fe2O3 values are decreased. This data evidence is a very important information for the purpose of bauxite beneficiation plant design prior feed to the Bayer refinery plant. The estimated % of available alumina (AA) from total alumina (Tal 2O3) are estimated based on wet chemistry and stoichiometric calculation. For this exercise the washed and unwashed samples were compared. The AA value is quite important information for Bayer process as it is indicates the real amount of alumina can be extract in caustic soda solution. As expected, the washed samples relatively have higher AA values than unwashed samples. It is shown that Air Upas area is relatively higher in AA than Sandai area (Fig. 13). This is assumed that the bedrock of laterite profile has controlling the alumina content during lateritization process. Unfortunately, almost of the previous test pit and drillholes were not deeply enough to sampling the bedrock. The further study is required to investigate this hypothesis. 5.3. Semiquantitative XRD Mineralogy Analyses Four representative drillhole samples from Air Upas and Sandai are selected for Semiquantitative XRD analyses. The objective is to assess the mineralogy distribution of each fraction from -0.3 mm to +50 mm of composited samples. The identified minerals in each fraction size are gibbsite, goethite, magnetite, hematite, anatase, quartz, kaolinite and paragonite. The principal bauxite mineral found is only gibbsite while boehmite and diaspore are not identified. This data is encouraging as gibbsite is the most expected bauxite mineral because it is easily soluble in Bayer Process (lower temperature process). The abundance of kaolinite occurrences are not expected due to identical with reactive silica that can increase caustic soda usage and higher processing cost. Comparing with the existing washing plant in CITA mine operations, It is normally expected that after washing and screening process, gibbsite is concentrated in coarse fraction of + 2mm while kaolinite is concentrated in finer fraction of -2 mm. However, surprisingly the data shows that fine-grained gibbsite minerals are still exists in finer – 2 mm fractions while kaolinite minerals are also exists in +2 mm coarse fractions (Fig. 14, 15, 16 and 17). It is possible that the existing screening – washing process both in laboratory and mines are not optimum to separate fine-grained gibbsite and kaolinite. 6. Discussion The main objectives of this beneficiation study are assessing the optimum methods to reduce silica, increase alumina content effectively and get optimum tonnage recovery. Additionally, the study results can support washing plant improvements at mine fronts. The bauxite beneficiation is a quite challenging process as the types of bauxites are various, depending on bedrock chemistries and lateritization processes. The combination of PSD, XRF, wet chemistry and semi quantitative XRD mineralogical data is effective to assess grain sizes and mineralogical behaviors during screening and washing process. The data from 2014 and 2016 studies show that the existing beneficiation methods both at lab scale and washing plant are not optimum to recover fine-grained gibbsite and potentially loss to tailing (Fig. 18). On the other side,



some kaolinites are also locked in coarse-grained bauxite and potentially include in bauxite feed for Bayer process. The kaolinite clays are identical with reactive silica and can cause caustic soda losses in the Bayer Process, this situation can impact to higher processing cost. This study is strongly support for beneficiation improvement at mine sites with main objectives to increase alumina content and lowering deleterious elements such as silica. For further study, crushing, scrubbing and washing methods are need to be considered to remove kaolinite with more efficient. For long-term economic benefits, mapping of bauxite ore types are quite important. It is interpreted that certain bauxite type is naturally clean without kaolinite and the other type is interlocked with kaolinite. By support from Geology Department, the mine plan can be optimized to support “crush – no crush” and “wash – no wash” decisions during mine operations. Then, the bauxite mine tonnage can be optimized and minimized fine-grained bauxite loss to the tailing dams. 7. Conclusion The major conclusions from this study are summarized below. 1. The moderate to strong bauxite lateritizations in Ketapang have correlations with the classification of high grade bauxite – bauxite – kaolinitic bauxite and ferritic bauxite. 2. Based on PSD analyses, it is very clear that the bauxite size from Air Upas and Sandai areas are divided into two major populations with boundary of 1mm screen size. If fine grained removed with boundary of 1 mm, the retained weight (%) recovery is about 60%. 3. At screen size +1 mm boundary the values of total Al 2O3, available Al2O3, LOI and Tal2O3/TSiO2 ratio are significantly increased while TSiO2, RSiO2 and Fe2O3 values are decreased. This data evidence is a very important information for the purpose of bauxite beneficiation plant design prior feed to the Bayer refinery plant. 4. As expected, the washed samples relatively have higher AA values than unwashed samples. It is shown that Air Upas area is relatively higher in AA than Sandai area. This is assumed that the bedrock of laterite profile has controlling the alumina content during lateritization process. 5. The identified minerals by XRD in each fraction size are gibbsite, goethite, magnetite, hematite, anatase, quartz, kaolinite, illite and paragonite. The principal bauxite mineral found is only gibbsite while boehmite and diaspore are not identified. This data is encouraging as gibbsite is the most expected bauxite mineral because it is easily soluble in Bayer Process (lower temperature process). 6. Surprisingly the data shows that fine-grained gibbsite minerals are still exists in fine fractions of – 2 mm while kaolinite and illite minerals are also exists in +2 mm coarse fractions. It is possible that the existing screening – washing process both in laboratory and at mine fronts are not optimum to separate fine-grained gibbsite and kaolinite. For further study, crushing, scrubbing and better washing methods are need to be considered to remove kaolinite-ilite with more efficient. 7. This study is strongly support for beneficiation improvement at mine sites with main objectives to increase alumina content and lowering deleterious elements such as silica 8. For long-term economic benefits, mapping of bauxite ore types are quite important. It is interpreted that certain bauxite type is naturally clean without kaolinite and the other type is interlocked with kaolinite. Based on this bauxite type map, the beneficiation plant at mine fronts can be optimized and impacting for low cost Bayer processing.



REFERENCES Andrews, W. H., 1984, Uses and Specifications of Bauxite, in Bauxite: Proceedings of the 1984 Bauxite Symposium, Edited by L. Jacob Jr. New York: SME – AIME, p. 49 – 66. Chin, L. A. D., 1984, Research Directions to Increase Alumina Recovery from Bauxites, in Bauxite: Proceedings of the 1984 Bauxite Symposium, Edited by L. Jacob Jr. New York: SME – AIME, p. 641 – 650. Darman, H. and Sidi, F.H., 2000, An Outline of the Geology of Indonesia, Indonesian Association of Geologists (IAGI), Jakarta, 192 p. Gendron R. S., Ingulstad M., Storli E., 2013, Aluminum Ore: The Political Economy of the Global Bauxite Industry, Sample Material, UBC Press Vancouver Toronto, 24 p. Gow, N. N., Lozej, G. P., 1993, Bauxite, Geoscience Canada Volume 20 Number 1, p. 9 – 16. Gu, J., Huang, Z., Fan, H., Jin, Z., Yan, Z., Zhang, J., 2013, Mineralogy, geochemistry, and genesis of lateritic bauxite deposits in the Wuchuan-Zheng’an-Daozhen area, Northern Guizhou Province, China, Journal of Geochemical Exploration 130, p. 44 – 59. Hill, V. G., Sehnke, E., 2006, Bauxite, in Industrial Minerals and Rocks: Commodities, Markets and Uses, Edited by J. Kogel, N. Trivedi, J. Barker, S. Krokowski, Littleton, CO: Society for Mining, Metallurgy and Exploration, p. 227 – 261. Kadarusman, A., 2016, Particle Size Distribution and Beneficiation Study for Bauxite, Internal Presentation for PT. Cita Mineral Investindo Tbk. 47 p. LAPI ITB, 2014, Laporan Akhir: Kajian Analisis Benefisiasi Bauksit, Internal report for PT. Labai Tambang Pertiwi, 38 p. Nickel Phil, 2012, Mineral Resource Report Based on JORC Code, North, Central and South-2 Bauxite Regions, West Kalimantan Indonesia for PT. Cita Mineral Investindo Tbk., Part 1 of 2 Parts, 64 p. Rodenburg, J. K., 1984, Geology, Genesis and Bauxite Reserves of West Kalimantan, Indonesia, in Bauxite: Proceedings of the 1984 Bauxite Symposium, Edited by L. Jacob Jr. New York: SME – AIME, p. 603 – 618. Rustandi, E., De Keyser, F., 1993, Geological Map of the Ketapang Sheet, Kalimantan scale 1 : 250,000. Geological Research and Development Centre, Bandung. Sanyoto, P and Pieters, P.E., 1993, Geological Map of the Pontianak / Nangataman Sheet, Kalimantan scale 1 : 250,000. Geological Research and Development Centre, Bandung. Smith, P., 2008, High Silica Processing: Economic Processing of High Silica Bauxites – Existing and Potential Processes, Parker Centre, CSIRO Light Metals Flagship, 42 p.



Sudana, D., Djamal, B., Sukido, 1994, Geological Map of the Kendawangan Sheet, Kalimantan scale 1 : 250,000. Geological Research and Development Centre, Bandung. Surata, M., Suksiano, O., Pratomo, M., Supriyadi, 2010, Discovery and Its Genetic Relationship of Bauxite Deposit in Mempawah and Landak Regency West Kalimantan Province, in Kalimantan Coal and Mineral Resources 2010 Proceedings, MGEI – IAGI, p. 107 – 116. Toreno, E. Y., Moe’tamar, 20112, Karakteristik Cebakan Bauksit Laterit di Daerah Sepiluk-Senaning, Kabupaten Sintang, Kalimantan Barat, in Bulletin Sumber Daya Geologi Volume 7 No. 2, 2012, p. 1 - 22. Van Bemmelen R. W., 1949, The Geology of Indonesia Volume II, Economic Geology, Government Printing Office, The Hague, 265 p.



(Hill and Sehnke, 2006)



(Modified from Gow and Lozej, 1993)



Figure 1: Simplified schematic of the basic Bayer Process (Modified from Smith, 2008).



Figure 2. Process flow and the typical recovery of material during processing from bauxite to aluminium.



Figure 3. Typical major structure cost items at most alumina plants.



Figure 4. Tectonic setting of Borneo (Darman & Sidi, 2000).



Figure 5. Regional geology of Kendawangan, Ketapang and Pontianak with CITA mine concessions (Modified from Sudana et al., 1994, Rustandi et al., 1993 and Sanyoto at al., 1993).



Figure 6. Triangular diagram of bauxite lateritization degree in Air Upas area (Modified from Meyer et al. 2002 in Gu et al., 2013).



Figure 7. Triangular diagram of bauxite mineralogical classification in Air Upas area (Modified from from Aleva, (1994 in Gu et al., 2013).



Figure 8. Bauxite type map based on mineralogical classification in Air Upas area.



Figure 9. PSD distributions from Air Upas and Sandai drillhole samples. There are two major populations: fine-grained – 1mm size and coarse-grained +1mm size.



Figure 10. Average recovery vs each screen size for Air Upas (left) and Sandai (right).



Figure 11. Average chemistries vs individual screen size of Air Upas area



Figure 12. Average chemistries vs individual screen size of Sandai area



Figure 13. Available Alumina(AA) composition against Total Alumina(TA) from



washed and unwashed samples.



Figure 14. XRD mineralogy and chemistries compositions for each fraction size from Air Upas area



Figure 15. Air Upas: fine-grained gibbsite minerals are still exists in finer – 2 mm fractions after washing – screening while kaolinite minerals are also exists in +2 mm coarse fractions.



Figure 16. XRD Mineralogy and chemistries compositions for each fraction size from Sandai area.



Figure 17. Sandai: fine-grained gibbsite minerals are still exists in finer – 2 mm fractions after washing – screening while kaolinite minerals are also exists in +2 mm coarse fractions.



Figure 18. Washing plant performances and major chemistries at mine sites of Sandai, Labai and Air Upas. Front = insitu mine bauxite samples, Olahan = washed bauxite samples (LAPI ITB, 2014).