The Effect of Roasting Prior to The Leaching Process of Alkalinized Ferronickel Slag Followed by Precipitation Process

Terak feronikel dihasilkan sebagai produk samping dari produksi feronikel. terak feronikel mempunyai potensi sebagai bahan baku beberapa komponen berharga karena komposisinya melalui proses bertahap. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh dari proses pemanggangan campuran terak feronikel dan Na2CO3 sebelum leaching air panas dan presipitasi untuk menghasilkan endapan silika. Proses pemanggangan terak feronikel dengan penambahan Na2CO3 telah dilakukan untuk pembentukan natrium silikat. Kemudian dilarutkan melalui proses pelindian menggunakan air panas 90 ° C selama 120 menit. Endapan silika didapatkan dengan proses presipitasi sodium silikat terlarut diikuti dengan pemeraman selama tiga hari. Berdasarkan hasilnya, pemanggangan menyebabkan perubahan komposisi yang mempengaruhi persen pelindian dan perolehan silika. Reaksi terjadi dari permukaan ke inti yang dibuktikan dengan pengecilan ukuran residu pelindian dari RAF nya. Natrium silikat dalam bentuk Na4SiO4 diketahui terlarut Ketika pelindian air dilakukan. Pengendapan dan pemeraman larutan natrium silikat telah menghasilkan endapan silika dengan ukuran partikel lebih dari 100 mm. pemanggangan pada 1000 ° C selama 240 menit menghasilkan perolehan silika tertinggi.

THE ROLE OF N-DOPING TO THE PORE CHARACTERISTICS OF ACTIVATED CARBON FROM VETIVER ROOT DISTILLATION WASTE

This work studied the effect of nitrogen functional group modification on activated carbon synthesized from vetiver root waste on pores development. Synthesis of activated carbon was carried out by hydrothermal carbonization of vetiver root waste at a temperature of 225 ⁰C for 18 hours followed by chemical activation using K2FeO4as activated agent in a furnace at temperature of 800 ⁰C for 2 hours with nitrogen atmosphere flowed at a rate of 100 mL/minute. Urea was used as a nitrogen source. The variation of urea concentration was 1:0 (AC0–800), 1:3 (AC3–800) and 1:5 (AC5–800). The results showed that these activated carbons have mesoporous characteristics with the largest Brunauer Emmett Teller (SBET) surface area of 552.90 m2g-1 and average pore width 3,43 nm. The presence of nitrogen functional group was observed in the Fourier Transform Infrared Spectrometer analysis. Synthesis of activated carbon from vetiver root waste with an addition of urea is the newest method to produce mesoporous activated carbon for electrode and support catalyst purposes.

THE EFFECT OF ECAP PROCESSING TO HARDNESS, SURFACE MORPHOLOGI, AND CORROSION RESISTANCE OF 6061 ALUMINIUM ALLOYS

Al-Mg-Si alloys (6xxx) has been widely used as structural materials in building and vehicles because of its excellent strength and corrosion resistance. The improvement of fine grain microstructure which can increase mechanical and physical properties become an interesting field in recent research.. Equal channel angular press is the most promising method to apply severe plastic deformation (SPD) which can produce ultra-fine grain in the bulk material without residual porosity. This study presents some experiments results on the effect of ECAP number of passes variation to the hardness, microstructure, and corrosion behaviour of Al 6061 alloys. The samples were annealed in the furnace with argon gas environment at 530°C for 4 hours and then immersed in liquid nitrogen for 5 minutes before ECAP process. The ECAP process was done with Bc route using dies with 120° of internal channel angle and pass variation of 1, 2, 3, and 4. The optimum hardness is 107.58 HRB in Al 6061 samples with 3 passes of ECAP. The increasing ECAP number of passes leads to a significant grain size reduction from 0 way pass, the grain size is around 10 µm, while for a 4 way pass, the grain size is around 2.5 µm. The corrosion resistance of Al 6061 alloys increased with the increasing number of passes in ECAP process.

INCREASING OF METAL RECOVERY IN LEACHING PROCESS OF SPENT CATALYST AT LOW TEMPERATURE: THE ADDITION OF HYDROGEN PEROXIDE AND SODIUM CHLORIDE

One of the factors that affect the leaching process of a mineral source is the mineral characteristics of the raw materials. Not all mineral phases can be leached directly and completely. Thus, some minerals require special treatment so that the leaching process can take place optimally. This study will focus on studying the effect of additive compounds addition, i.e. hydrogen peroxide and sodium chloride, in the leaching process of spent catalyst using a sulfuric acid solution. The leaching process was carried out at a concentration of 1 M sulfuric acid solution for 240 minutes at room temperature. The hydrogen peroxide concentration was varied at 0–9%v/v, while the sodium chloride concentration was varied at 0–0.8 mol/L. The experimental results showed that the two additive compounds were able to increase nickel recovery significantly. The highest nickel recovery of 95.08% was achieved when hydrogen peroxide was used at 9%v/v. The nickel recovery is 3.5 times higher than without the addition of hydrogen peroxide. Meanwhile, sodium chloride concentration of 0.8 mol/L was able to provide the highest nickel recovery of 50.38% or an increase of 1.9 times compared to without the addition of sodium chloride.

The Effect of Variations in Electrolyte Temperature and Current Strength on the Synthesis of Manganese Dioxide from Manganese Sulfate Precursors by Electrolysis Method

The development of science and technology today in the field of electronics, especially energy storage increases the demand for the use of lithium secondary batteries. The development of lithium batteries is focused on energy storage capacity by using manganese dioxide (MnO2) as a lithium battery cathode material. Manganese dioxide was chosen as the cathode material for lithium batteries because it has a high storage capacity of about 615 mAh/g compared to other materials such as graphite which has a storage capacity of 372 mAh/g and has a low toxicity of 0.14 mg/kg. MnO2 was synthesized by electrolysis method from manganese sulfate (MnSO4) precursor which was obtained from Trenggalek manganese ore leaching process. The electrolysis process was carried out for 5 hours using variations in electrolyte temperature of 30, 40, 50 and 60oC as well as variations in current strength of 2, 3, 4 and 5 A to determine the effect of electrolyte temperature and current strength on mass gain, structural polymorphy and morphology of MnO2 formed. The highest mass gain was obtained at the use of an electrolyte temperature of 60oC and a current of 5 A, which was 11.4 grams with the polymorphy structure of the MnO2 compound formed was α-MnO2 polymorphy. SEM image shows that the MnO2 particles have a spiny round shape and tend to agglomerate with particle diameter values ranging from 50 nm - 170 nm. Keywords: Electrolysis, MnO2, MnSO4, Electrolyte temperature, Current strength

Lapisan Plasma Spray Ni-Al dan Al-Si Pada Tabung Baja Tahan Karat Austenitik Dengan Jarak Semprot Terbatas (Atmospheric Plasma Spray Coating of Ni-Al and Al-Si on Austenitic Stainless-Steel Tube with Limited Short Spray Distance)

Atmospheric Plasma Spray (APS) coating is a widely used thermal spray coating process in industrial applications. High density and high bond strength coating are the main features of this process that is required in almost coating properties for specific applications. The geometrical condition of the workpiece substrate dictates the parameter needed to achieve a certain quality of the coating. Changes in the geometry require modification on the parameter of the process to maintain the quality of the coating. Aluminum Silicon and Nickel Aluminum coating were applied on Stainless Steel substrate casing. Due to the limitation of spray distance between nozzle gun and substrate surface of the casing, modified several parameters of the process were taken. Several parameters were investigated to find out the optimum result of coating and verified with tensile bond strength test, hardness test, and microscopic analysis examination. These activities that involved modification of parameters, mechanical testing, and visual inspection informed that power as a function of voltage and ampere, powder feed rate, the surface speed of substrate (the particular amount of workpiece rotation per minute), and traverse speed of gun, contribute to the result of the optimum coating.

PELINDIAN ZIRKONIUM DARI TAILING MAGNETIK PASIR ZIRKON HASIL ROASTING MENGGUNAKAN NAOH

Tailing pertambangan adalah penyebab sebagian besar pencemaran lingkungan yang terkait dengan industri ekstraktif. Peningkatan risiko pencemaran lingkungan telah diamati di seluruh dunia karena sejumlah besar pengolahan bijih kadar rendah. Dalam penelitian ini, pemulihan zirkonium dari tailing magnetik pasir zirkon telah diselidiki. Tujuan dari studi ini adalah untuk mengetahui pengaruh kondisi operasi pencucian terhadap pemulihan zirkonium dari tailing magnetik pasir zirkon. Tailing magnetik pasir zirkon yang digunakan dalam penelitian ini diperoleh dari PT Monokem Surya. Awalnya, tailing magnetik pasir zirkon dipanggang dengan tujuan memisahkan senyawa zirkonium dan silikat sebagai pengotor. Proses pemanggangan telah dilakukan dengan mereaksikan tailing magnetik zirkon pasir dan NaOH dengan perbandingan 1: 1 pada 450 °C selama 3 jam. Produk tersebut kemudian dicuci, dikeringkan dan dilindi menggunakan larutan HCl dan H2SO4. Untuk mengetahui kinerja pelindian, kondisi operasi bervariasi termasuk suhu (30 °C-110 °C), konsentrasi asam (0,125M-2M) dan rasio padat terhadap cair (0,05 g/mL-0,25 g/mL). Ditemukan bahwa pemulihan zirkonium mencapai optimal ketika proses pelindian menggunakan 0,5 M HCl dan H2SO4. Menggunakan kondisi ini, pemulihan 88% dan 26% diperoleh untuk zirkonium menggunakan HCl dan H2SO4, masing-masing.

SYNTHESIS AND CHARACTERIZATION OF NICKEL HYDROXIDE FROM EXTRACTION SOLUTION OF SPENT CATALYST

Nickel is an essential metal element and is applied in various sectors. One of the useful nickel–based derivatives products is nickel hydroxide [Ni(OH)2]. This compound is widely applied as raw material for electrodes of rechargeable batteries, capacitors, electrolyzers, and catalysts. This study focuses on the synthesis of Ni(OH)2 using the hydroxide precipitation method. A solution from the extraction process of spent catalysts was used as a precursor solution. After the precursor solution was obtained, the precipitation process was carried out at pH 10, where the operating temperature was varied at 30–60oC. NaOH, KOH, and MgO solutions were used as precipitating agents. The experimental results show that the Ni(OH)2 compounds were produced optimally at low temperatures, 30oC. It could be indicated from the lowest concentration of Ni2+ ions in the liquid phase that reached that temperature. The three precipitation agents also gave good results in the precipitation of Ni2+ ions, where almost all of the Ni2+ ions were precipitated from the liquid phase. The precipitated products were characterized using SEM, XRD, and XRF. The analysis results showed that the product was agglomerated and formless. The purity of the precipitates formed were 24.1 and 29% for the precipitating agents MgO and NaOH, respectively.