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Journal : Metalurgi

Daur Ulang Refraktori Bekas Kiln dan Fly Ash Batubara dengan Variasi Tekanan Greenbody [Recycling of Used Refractory of Kiln and Coal Fly Ash by Various of Greenbody Presure] Septriana, Ayu; Azhar, Azhar; Astuti, Widi
Metalurgi Vol 32, No 3 (2017): Metalurgi Vol. 32 No. 3 Desember 2017
Publisher : Pusat Penelitian Metalurgi dan Material - LIPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (312.227 KB) | DOI: 10.14203/metalurgi.v32i3.339

Abstract

Refractory is one type of ceramic material which is thermostable (high temperature resistant) and has the ability to maintain a good physical and chemical condition at high temperature. Manufacture of refractory in this study using used kiln refractory from cement industry and 15% coal fly ash as additional. This research analyzed the effect of green body pressure produced by physical properties of refractory which made from mixture of used refractory and coal fly ash. Used refractory crushed into large aggregate size -40 +80 mesh and small aggregate size -80 mesh, while fly ash -100 mesh. Then, the two of material mixed. Raw material pressed by press hydrauliuc, with a cube-shaped mold in 5 x 5 x 5 cm size. The pressure of green body varied in 8, 9, 10, 12, and 13 tons. The product tested by archimedes methode to getting apparent porosity and bulk density, and guarded hot plate methode standard use ASTM (C 177-04) to getting the cold crushing strengh and thermal conductivity. Higher pressure molding green body product was obtained with higher compressive strength and bulk density, with lower value of the apparent thermal conductivity and porosity. The highest value for the compressive strength and bulk density was 4.48 MPa; 1.119 g / cm3; the lowest value of thermal conductivity and apparent porosity is 11.60 W / m.K; 22.034%. Those values obtained from green pressure body 13 tons.AbstrakRefraktori merupakan salah satu jenis bahan keramik yang tahan terhadap panas (temperatur tinggi) dan memiliki kemampuan untuk mempertahankan kondisinya baik secara fisik maupun kimia pada temperatur tinggi tersebut. Pembuatan refraktori pada penelitian ini menggunakan bahan baku refraktori bekas pakai kiln pabrik semen dengan tambahan 15% fly ash batu bara. Penelitian ini menganalisis pengaruh tekanan green body dari campuran refraktori bekas pakai dan fly ash batu bara yang dihasilkan terhadap sifat fisik refraktori tersebut. Bahan baku refraktori bekas pakai dihaluskan dengan distribusi ukuran agregat besar -40+80 mesh dan ukuran agregat kecil -80 mesh, sedangkan fly ash batu bara berukuran -100 mesh. Pemadatan bahan baku dilakukan dengan menggunakan alat press hydraulic, dengan cetakan berbentuk kubus dengan ukuran 5 x 5 x 5 cm. Dilakukan variasi tekanan campuran green body sebesar 8, 9, 10, 11, 12, dan 13 ton. Pengujian produk dilakukan dengan uji porositas (apparent porosity) dan densitas (bulk density) dengan metode archimedes, kuat tekan (cold crushing strenght), dan uji konduktivitas termal bahan dilakukan dengan metode guarded hot plate menggunakan standarASTM (C 177-04). Pengaruh tekanan green body dari campuran fly ash batu bara dan refraktori bekas pakai kiln terhadap sifat fisik refraktori adalah semakin tinggi tekanan pencetakan green body, maka semakin tinggi nilai kuat tekan dan densitasnya, sedangkan nilai konduktivitas termal dan porositas akan semakin rendah. Nilai tertinggi untuk kuat tekan dan densitas adalah 4,48MPa; 1,119 gr/cm3; nilai terendah konduktivitas termal dan porositas adalah 11,60 W/m.K; 22,034 %. Nilai-nilai tersebut didapatkan dari tekanan green body 13 ton.  
Lanthanum and Nickel Recovery from Spent Catalyst using Citric Acid: Quantitative Performance Assessment using Response Surface Method Petrus, Himawan Tri Bayu Murti; Wijaya, Ardyanto; Iskandar, Yusuf; Bratakusuma, Danu; Setiawan, Hendrik; Wiratni, Wiratni; Astuti, Widi
Metalurgi Vol 33, No 2 (2018): Metalurgi Vol. 33 No. 2 Agustus 2018
Publisher : Pusat Penelitian Metalurgi dan Material - LIPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (523.642 KB) | DOI: 10.14203/metalurgi.v33i2.437

Abstract

Heavy metals and Rare earth elements (REEs) are nowadays being used widely in many industries from electronics to petroleum industries as catalysts. However, their disposal caused serious problems to the environment. With the sharp growth in its usage, there is a better way to use and utilize valuable metals from secondary sources such as their disposal rather than using new raw materials. The aim of this work is to study the potential of citric acid as a leaching agent to extract lanthanum and nickel in various acid concentration and leaching temperature. The raw material used in this work is spent catalyst from Pertamina Refinery Unit VI, Balongan, Indonesia. The spent catalyst is decarbonized with a heat treatment at 725°C for 10 minutes before the leaching process. The leaching process used 0.1; 1; and 2 M of citric acid with a varied temperature of 30, 60, and 80°C. The lanthanum recovery was calculated by comparing the mass percentage of lanthanum before leaching process and after leaching process using Energy Dispersive X-Ray Spectroscopy (EDX). The results were analyzed by response surface methodology (RSM) and are proved to be a reliable method to depict and analyze the leaching characteristics. The molarity of the citric acid is the most significant independent variables used in the research for lanthanum recovery response. However, based on the Pareto analysis result there are no significant variables that affect the recovery of nickel. The second order polynomial fitting model is also proved to be compatible with the response of lanthanum recovery but is less compatible with nickel recovery.
KARAKTERISTIK STRUKTUR MIKRO DAN SIFAT MEKANIK BESI TUANG PUTIH PADUAN KROM TINGGI HASIL THERMAL HARDENING UNTUK APLIKASI GRINDING BALL[Microstructure Characteristic and Mechanical Properties of Thermal Hardened of High Chromium White Cast Iron for Grinding Ball Application] Sofi, Achmad; Astuti, Widi; Nurjaman, Fajar
Metalurgi Vol 28, No 3 (2013): Metalurgi Vol.28 No.3 Desember 2013
Publisher : Pusat Penelitian Metalurgi dan Material - LIPI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (570.606 KB) | DOI: 10.14203/metalurgi.v28i3.261

Abstract

KARAKTERISTIK STRUKTUR MIKRO DAN SIFAT MEKANIK BESI TUANG PUTIH PADUANKROM TINGGI HASIL THERMAL HARDENING UNTUK APLIKASI GRINDING BALL. ASTM A532Type II-A adalah jenis material besi tuang putih paduan krom tinggi (high chromium white cast iron), dengankandungan karbon 2,3% dan krom lebih dari 13,3%. Umumnya ASTM A532 Type II-A banyak digunakansebagai grinding ball. Pada studi penelitian ini, proses perlakuan panas berupa thermal hardening dilakukanterhadap material ASTM A532 Type II-A untuk meningkatkan nilai kekerasannya. Proses quenchingmenggunakan dua buah media quenching yang berbeda, yaitu oli dan udara paksa (udara ditiupkan secaralangsung dari fan), sedangkan proses tempering dilakukan pada temperatur yang bervariasi yaitu 250 °C, 300 °C,dan 350 °C. Hasil proses thermal hardening kemudian diuji keras, metalografi dengan OM (optical microscopy),SEM (scanning electron microscopy) dan XRD (X-ray diffraction). Harga kekerasan optimum dari besi tuangputih paduan krom tinggi (ASTM A532 Type II-A) adalah sebesar 723 BHN, yang dihasilkan dari prosesthermal hardening dengan media quenching oli pada temperatur tempering 300 °C. Tingginya harga kekerasanyang dihasilkan dari proses tersebut adalah akibat terbentuknya fasa martensit temper dan tersebarnya karbidakrom dalam jumlah besar (volume fraksi tinggi). AbstractASTM A532 Type II-A is a high chromium white cast iron with carbon content 2.3% and chromium morethan 13.3%. This material is widely used as a grinding ball. In this study, heat treatment process which isthermal hardened, was conducted to increase the hardness of this material. Quenching process used two kindof quench media, such as oil and forced air (which was blown directly from fan), while the tempering processwas conducted with various temperatures, 250 °C, 300 °C, and 350 °C. After thermal hardening process,material was characterized by hardness testing, metallography by OM (optical microscopy) and SEM(scanning electron microscopy), and XRD (X-ray diffraction). The optimum hardness value is 723 BHNresulted from thermal hardening process at 300 °C. Higher hardness value was obtained due to form oftempered martensite and numerous of chrom carbide disperse in this material.
Co-Authors . Aprolita, . Adil Jamali, Adil Adiwijaya, Adiwijaya Agus Haerudin, Agus Agus Prasetya Agustin, Niyar Candra Anggara, Ferian Anief Rufiyanto Aprimal Aprimal, Aprimal Apriyanti, Eny Arsyad Lubis, Arsyad Astrilia Damayanti Azhar Azhar Bambang Suharno Bayu Kurniawan Bratakusuma, D Bratakusuma, Danu Catur Rini Widyastuti, Catur Rini Dewi Kurniati Dewi Purnama Sari Diah Ayu Wulandari, Diah Ayu Djoko Adi Widodo Djuanda, Dagus Resmana Dwi Handayani, Anggelita Dwi Wiji Lestari, Dwi Wiji Eka Ayu Agustina, Himmah Sekar Endang Tri Wahyuni Fajar Nurjaman Gemilar, Gelar Panji Hendrik Setiawan, Hendrik Heni Kusumayani Heny Kusumayanti Herlina, Ulin Herlina, Ulin Himawan Tri Bayu Murti Petrus, Himawan Tri Bayu Murti I Made Bendiyasa Indah Nurul Izzati, Indah Nurul Indra Perdana Iqbal, Mubaroq Iskandar, Y Iskandar, Yusuf Isnugroho, Kusno Isnugroho, Kusno Istihanah Nurul Eskani, Istihanah Nurul Joni Setiawan Kasman Kasman Kristian, Lian Kristian, Stefanus Lian Kusuma, Alam Budi Kusumawardani, Yustika Kusumawardani, Yustika Kusumawardani, Yustika Lanjar, Lanjar Manurung, Hotden Maswadi Maswadi Moch. Arif Bijaksana, Moch. Arif Mufakhir, Fika Rofiek Mufakhir, Fika Rofiek Mufakir, Fika Rofiek Muhammad Amin Munirsyah, Munirsyah Naufal, Shidqi Aqil Nova Susilowati, Nova Novira, Dinda Tri Novita, Sinta Nur Nalindra Putra, Nur Nalindra Nurjanah, Isti Nurjanah, Isti Petrus, Himawan TBM Petrus, Himawan TBM Putra, Federick Dwi R.TD Wisnu Broto Radenrara Dewi Artanti Putri, Radenrara Dewi Artanti Ratna Dewi Kusumaningtyas Ratna Frida Susanti Ria Wulansarie, Ria Riayanti, Fatma Indah RTD Wisnu Broto RTD. Wisnu Broto Septriana, Ayu Setyawan, Cahya Edi shinta virdhian, shinta Shofi, Achmad Sinaga, J M Sinaga, J M Soesaptri Oediyani, Soesaptri Sofi, Achmad Sugeng Santoso Suka, Ediman Ginting Tanujaya, Felisha Hapsari Tanujaya, Felisha Hapsari Tawfiequrahman, Ahmad Tri Yuda, Aulia Pertiwi Triastuti Sulistyaningsih Vidhian, Shinta Wanta, Kevin Cleary Wanta, Kevin Cleary Widhi Maharani Widya Rosita Wijaya, Ardyanto Wiratni Wiratni, Wiratni Yustika Kusumawardani, Yustika Kusumawardani Zulaechah, Luluk Siti Zulaechah, Luluk Siti