Indonesia is one of the largest Ni ore producers in the world and is also expected to be an important potential source of some critical metals (e.g., Co, Sc, rare-earth elements, and platinum-group elements). However, few studies have examined Ni laterite deposits in this country. In this study, we investigate Ni enrichment and the potential accumulation of critical metals in four laterite profiles with varying degrees of serpentinization and weathering intensity in the Soroako and Pomalaa mining areas of Sulawesi, Indonesia. We integrate geochemical evaluation with a mass-balance approach and mineralogical analysis to better constrain the geochemical factors influencing the mobilization of Ni during lateritization. Nickel contents in the saprolite horizon of the profiles that are strongly weathered and developed over serpentinized peridotite are higher than those that are weakly weathered and developed over unserpentinized harzburgite. The bulk Ni contents of saprolite horizons are related to Ni contents of Ni-bearing Mg-phyllosilicates, which suggests that Ni remobilization is the main control on Ni enrichment in the profiles. Massbalance calculations reveal that the amounts of gained Fe and Ni in the profiles are positively correlated. This relationship indicates that the redistribution of Ni is likely controlled by the aging of Ni-bearing goethite (dissolution/ recrystallization) involving ligand-promoted dissolution by organic matter and/or reductive dissolution by microbial activity near the surface. Critical metals show enrichment in specific horizons. Enrichments in Co and rareearth elements are strongly influenced by the formation of Mn-oxyhydroxides in the oxide zone of the profiles. In contrast, Sc, Pt, and Pd show residual enrichment patterns, with grades influenced mainly by their initial contents in bedrock. The profiles show a positive correlation between Sc and Fe, as reported for other Ni laterite deposits. Among the critical metals, Sc, Pt, and Pd contents in the studied profiles are comparable with values reported from other Ni laterite deposits worldwide.

Scandium (Sc) and its compounds are used in many modern-technology applications such as in optical, electronic, aeronautical, and fuel-cell industries. However, Sc occurrence were only limited in a very specific area with limited deposit and little attention has been paid to the genesis of Sc-bearing deposits in the world. 6 (six) bedrock samples and 15 (fifteen) lateritic samples (saprolite to limonite) were collected and studied to investigate the distribution of Sc grades in lateritic Ni deposits and identify Sc-bearing minerals in laterites from ultramafic rocks in West Blok, East Block and Petea prospect in Soroako, South Sulawesi, Indonesia. The study suggests that scandium is enriched in limonite layer in weathering profile. In general, pyroxene bearing rich bedrock (harzburgite in composition) will contain higher Sc content in their weathering product. It is suggested that the Sc are associated with the occurrence of iron oxide from pyroxene. However, as the occurrence of Sc is very limited, the most promising result was shown by East Block profile in which the enrichment of Sc is also supported by enrichment of NiO content. Sc will be viable as by-product of nickel laterite.

Scandium is one of the rare earth elements which is currently widely used for various needs such as the aerospace industry, solid oxide fuel cells, electronics industry and in metallurgical applications. Generally, Scandium appears in small amounts so its structural role in the host minerals cannot be readily identified. Some studies reported the scandium extraction from lateritic nickel deposit where may contain considerable amount of scandium in addition to nickel and cobalt. Preliminary research of scandium enrichment has been investigated from the ultramafik rock indicates that an enrichment of scandium concentration was found in the red limonite. The aim of this study was to investigate the potentially enrichment of scandium mineral from nickel laterite in Lapaopao Area. There are a total of 38 samples from 1 (one) diamond drill holes which represent the limonite, saprolite and bedrock profiles have been collected and studied to investigate the distribution pattern of Sc grades within the lateritic profile. These samples are being analized by XRF for major and minor element and ICP-OES method for rare earth element assaying. The study has confirmed that scandium is enriched in limonite layer of weathered ultramafic laterite profile. The scandium content from the ultramafic bedrock is 15 ppm and has enriched until 81 ppm of scandium in the limonite layer.

Coal deposits in Banti Village, Enrekang Regency, South Sulawesi Province, Indonesia are geographically located at coordinates: 03°27‘59.72” south latitude and 119°51‘34.35” east longitude and are categorized as medium coal quality. This is evidenced by the results of several analysis that have been carried out. Microscopic analysis showed that there were three dominant minerals such as quartz, pyrite and clay. While the results of mineralogical analysis using X-ray diffraction (XRD) coal in Banti Village show the contents of minerals such as quartz, illite, kaolinite, pyrite, and hematite. Proximate and total sulfur analysis of Banti coal was carried out in 3 samples, namely; sample ENRE-1A, ENRE-1C, ENRE-1D. Banti coal samples shows the average value of total moisture 2.29%, 13.79% ash content, 28.77% volatile matter, 55.83% fixed carbon, and 1.16% total sulfur content. ENRE-1A coal sample shows total moisture 3.20%, ash content 13.72%, volatile matter 27.57%, fixed carbon 55.52%, and total sulfur content 1.84%. ENRE-1C coal sample contains the lowest total moisture which is 1.68%, the highest ash content is 16.9%, volatile matter is 27.79%, fixed carbon is 53.76%, and total sulfur content is 0.92%. ENRE-1D coal sample showed total moisture content of 1.98%, ash content of 10.76%, volatile matter of 31.06%, fixed carbon of 65.2%, and total sulfur content of 0.70%. Analysis of calorific value of Banti coal samples respectively shows 6,785 kcal/kg for sample ENRE-1A, 6,794 kcal/kg for sample ENRE-1C, and 7,229 kcal/kg for sample ENRE-1D. Analyses of the three coal samples were carried out based on ASTM 1981. The presence of quartz, illite, kaolinite, pyrite, and hematite minerals in the coal samples affects the hight ash content in Banti coal. The sulfur content present on Banti coal is mainly due to the presence of pyrite. In general, the ash and sulfur content of Banti coal is classified as medium coal category. Banti coal has good quality for further study, especially coal seam ENRE-1D (coal seam containt hight calorific value and low total sulfur content).

The increasing demand of sponge iron as raw materials in steel industry nowdays has led to increase the effort in obtaining such materials from various sources. This study aims to characterize and beneficiate of a lateritic iron ore sample from Malili area of South Sulawesi. Mineralogy of the ore was investigated by means of X-ray diffractometry (XRD) and microscopy techniques; whereas chemical composition of the sample was determined by using X-ray fluorescence (XRF) spectroscopy. Result of mineralogical analysis indicated that ore sample consists of goethite, magnetite and chromite. The ore shows fine grained size with accicular texture. Chemical analysis reveals that sample is composed of Fe2O3 32.8%, Al2O3 35.5%, SiO2 21.0%, Cr2O3 7.2%, MnO 1.5%, and NiO 1.2%. Sieving of 20 kg iron ore sample was carried out to separate into five size fractions: (+212)μm, (-212+180)μm, (-180+150)μm, (-150+90)μm and (-90)μm with mass distribution of 12.0kg; 2.8kg; 0.9kg; 1.8kg and 1.6kg respectively. Each feed fraction was further treated by using dry low-intensity drum magnetic separator to produce concentrate. Result of each fraction having the mass percentage of 15.5%; 31.7%; 30.7%; 32.0% and 40.0% with the respective iron content (Fe2O3) of 45.0%; 47.9%; 43.9%; 46.7% and 47.2%. The Fe2O3 grade of concentrate in all fractions have narrow range values, but the mass percentage of concentrate increase significantly with finer grain size fraction. The highest Fe2O3 recovery was found to be 89.82% with -90 μm size fraction.