Zirconia had been made through smelting the zircon sand along with NaOH as a flux. The zircon sand as the smelter feed was taken from CV. Kurnia Alam Sejati mine at Palangkaraya, Middle Kalimantan. Major content of the zircon sand was 28.04% ZrO2 and SiO2 51.22% with several minor oxides such as 0.54% HfO2, 2.53% Fe2O3, 10.53% TiO2, 3.27% Al2O3 and less than 1% of alkali, alkaline earth and rare earth elements. In order to economizing the process, zircon sand upgrading was conducted prior to zirconia production. The upgrading process was conducted using several comprehensive equipments, consist of shaking table, magnetic separator and high tension separator (HTS).The upgraded sand contained 65.35% of ZrO2+HfO2 with 73.25% recovery, which was then used for smelting process at 650°C for 2 hours using NaOH as a flux. The product was then leached with water and sulphuric acid then crystallized to get precipitated zirconium hydroxide. The precipitated product was calcined at 900°C for 1 hour to get the zirconia and analyzed for its content. The zirconia content was 97.27% of ZrO2+HfO2 with 65.13% recovery.

ABSTRAKSodium aluminat (NaAlO2) merupakan bahan kimia anorganik penting yang digunakan sebagai bahan baku untuk pembuatan berbagai macam produk kimia antara lain polialuminum chloride (PAC), alum, dan zeolit sintetik. Dalam penelitian ini, NaAlO2 dihasilkan melalui proses Bayer yaitu pelarutan (digestion) bauksit asal Tayan, Kalimantan Barat, dengan soda kaustik (NaOH) pada skala pilot berkapasitas 100 kg umpan/batch dengan menggunakan uap secara kontak langsung pada suhu sekitar 140 o C dan tekanan 4 atm. Variabel yang diteliti meliputi : lama reaksi (1; 1,5; 2 jam), ukuran butir -0,177 mm (-80 mesh); -0,149 mm (-100 mesh); -0,0965 mm (-150 mesh), dan NaOH berlebih di atas kebutuhan stoikhiometrinya (1,37% sampai dengan 35,25%). Hasil penelitian menunjukkan bahwa waktu reaksi semakin lama, ukuran butir semakin halus, dan NaOH berlebih semakin tinggi sampai batas tertentu, memberikan perolehan alumina (Al2O3) yang semakin tinggi. Kondisi proses terbaik yang diperoleh adalah NaOH berlebih 28,83% , lama reaksi 2 jam dan ukuran butir -150 mesh (-0,105 mm) dengan perolehan alumina tertinggi 93,98%.Kata kunci : digestion, bauksit, proses Bayer, NaOH berlebih, sodium aluminat. ABSTRACT Sodium aluminate (NaAlO2) is an important commercial anorganic chemical material that can be used as raw material for various chemical products such as polialuminum chloride (PAC), alum, and synthetic zeolite. In this research, NaAlO2 was sinthesized through digestion process using bauxite from

Purification of pregnant solution from sphalerite concentrate extraction using sulfate acid to produce zinc oxide was meant to prepare zinc oxide production technology utilizing existing internal sphalerite mineral raw material. The pregnant solution used to produce zinc oxide contains 29.84% zinc (Zn), with the biggest impurities iron (Fe) 11.68%. In order to obtain high purity zinc oxide, the pregnant solution should be recovered. It was done through a solvent extraction method, in two process steps: extraction and stripping. The extraction was applying ligan bis di2ethylhexyle phosphate acid (D2EHPA) in toluene solvent, through ligan concentrate variation, pH and comparison of aqueous volume with organic volume (VA:Vo) and its excess. Stripping was carried out using sulfate acid through variation of concentration, pH and Vo:VA. To obtain optimum recovery, thus extraction and stripping should be carried out in many steps. The extractions and the strippings were calculated using McCabe Thiele diagram. Furthermore, zinc oxide was resulted from deposition and calcination of pure pregnant solution at temperature 500°C. Purification results show that the best extraction occurred at concentration D2EHPA 1 M, pH 3 and Vo:Va 2:1, through 4 step processes obtained recovery 97.50% with distribution coefficient 77.9; while the best stripping was obtained at H2SO4 concentration 2 M, VO:VA 2:1 through 3 step processes which obtained stripping percent 98.22% with stripping coefficient 1.51. On the other hand, zinc oxide solution resulted from purification was obtained Zn 93.31% in the form of hexagonal crystals (wurtzite).