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Studi pemisahan Mineral Berat pada Circuit Pemroresan Bijih Emas Dalam Usaha peningkatan Recovery Mineral Au (Ag) di pabrik Pengolahan Bijih Emas PT. Aneka Tambang Pongkor Jawa Barat
Get PDFthe attempt to seperate heavy minerals in the circui
Studi Pengolahan Pasir Besi Kutoarjo Jawa Tengah untuk Bahan Baku Industri Besi dan Baja
Get PDFthe development activities in indonesia especially in the industrial fiel
MAGNETIZING ROASTING OF IRON LATERITE ORE BY SUB-BITUMINOUS COAL AS REDUCTANT
No full textThe overburden of Pomalaa’s laterite ore is characterized by its high content of iron with average Fe content of 41.8 % and can be classified as iron cap deposit. As a significant iron ore resource to be used as raw material for iron and steel industry, upgrading of laterite ore is necessary to meet the requirement for iron making. The ore was treated by magnetized roasting technique followed by mag- netic separation to produce high iron content of magnetic concentrate. The ore were dominated by limonite iron minerals and has low magnetic property. However, roasting reduction treatment increased the magnetic properties of the ore due to transformation of magnetite
SEPARATION OF WARINGIN HEAVY MINERAL SANDS FROM CENTRAL KALIMANTAN
No full textCentral Kalimantan has grown rapidly as a heavy mineral producer. Zircon is the main mineral concentrate, but other valuable heavy minerals are present. With particular interest in the upgrading of zircon and its recovery, tekMIRA’s laboratory has developed benefi ciation steps of heavy minerals to produce marketable zircon con- centrate. Using a series of concentration equipments that includes spiral concentrator, shaking table, magnetic separator and electrostatic separator; the content of zircon in the end concentrate reaches up to 65% ZrO2
STRUCTURAL CHANGES OF POMALAA LATERITIC ORE DUE TO COAL-BASED MAGNETIZING ROASTING
No full textOverburden of Indonesia’s laterite ore at Pomalaa is considered as an iron cap. It performs low iron grade (41.88%) and high silica and aluminum oxide contents (18.47% and 9.46%, respectively). Around 54.74% of size distribution belong to -325 mesh fraction. Limonite iron mineral dominates in the ore in the range of 80-90% with water content of about 40%. Proven deposits of laterite iron ore are about 222 million tons. As a significant resources iron ore to be used as raw material for iron and steel industries, the iron content must be upgraded to meet the requirement of iron making industry. Magnetizing roasting technique can be conducted to change the paramagnetic iron mineral (such as hema- tite, goethite, limonite or siderite) into magnetite one that has high magnetic intensity. Therefore, the changed iron mineral can be concentrated using low-intensity, magnetic separator. Coal, mixed in ore composite may also enhance the development of coal-based magnetizing roasting processes in order to reach the desired temperature. Recently, reduced iron products from many different processes have been used as the main feed mixed with steel scrap. On the other hand, iron ore resources is getting dominated by low grade lateritic iron ore with specific content of water crystal. The abundant deposits of low grade lateritic iron ore and low rank coal in Indonesia can be used as suitable resources for raw materials in the iron and steel- making industry. Iron structural changes during magnetizing roasting process using coal as reductant agent was observed. The result showed that the non-magnetic limonite ore has been changed in to metallic iron and the iron recovery in the magnetic product depended on the coal ratio in the pellet composite. The magnetic product can be used for the development of lateritic iron ore as one of the alternatives to metallized iron feed for iron making industry
Perubahan Struktur Kristal dan Index Kerja Bijih Emas Cimanggu, Jawa Barat akibat Pemanasan Gelombang Mikro
No full textSari. Energi yang dibutuhkan pada proses kominusi dapat mencapai 50-70% dari keseluruhan energi yang digunakan pada pengolahan mineral. Karena itu, diperlukan usaha untuk menurunkan pemakaian energi kominusi dengan mengubah sifat fisik bijih agar murah hancur. Pemanasan gelombang mikro pada bijih sebelum kominusi merupakan salah satu alternatif yang dapat diterapkan. Pada penelitian ini telah diamati besarnya energi penggerusan bijih emas dari Cimanggu, Jawa Barat sebelum dan sesudah diperlakukan dengan pemanasan gelombang mikro. Hasil penelitian menunjukkan bahsa pemanasan gelombang mikro dapat mengubah struktur fisik mineral. Perubahan struktur fisik mineral pembentuk batuan menyebabkan batuan tersebut menjadi lebih getas, dan adanya "interal stress" mengakibatkan kecepatan pemanasan yang tinggi menyebabkan timbulnya retakan sehingga dapat memperpendek waktu gerus dan menurunkan energi penggerusan. Dengan pemanasan gelombang mikro selama 5, 15, 30, 60, 120 dan 300 detik sebelum pengggerusan, indeks kinerja penggerusan dapat turun sekitar 20 sampai 35%. The Influence of Microwave Heating on the Crystal Structure and Work Index of Cimanggu (West Java) Gold OreAbstract. The energy consumed in the comminution can reach up to 50- 70% of the whole energy consumed in the mineral processing. It is necessary to reduce the consumption of the comminution energy changing the physical characteristic of the ore. The microwave energy heating used on the ore before comminution is one of the applicable alternatives. In this research the grinding energy of the Cimanggu gold ore, West Java, has been observed before and after the microwave heating treatment. The result indicates that the microwave treatment can cause physical structural changes on certain minerals, and the rock become more brittle. It can shorten and reduce the grinding time and energy. By microwave energy induced for 5, 15, 30, 60, 120, and 300 seconds prior to grinding, the work index was reduced by about 20 to 35%
PEMBUATAN ZIRKONIA SEMI STABIL DARI PASIR ZIRKON KALIMANTAN TENGAH DENGAN MENGGUNAKAN BAHAN PENSTABIL CAMPURAN CaO DAN MgO
No full textPembuatan zirkonia semi stabil (PSZ) dari pasir zirkon Kalimantan Tengah telah dilakukan dengan metode disosiasi termal pada skala laboratorium. Pasir zirkon Kalimantan Tengah yang digunakan mempunyai kadar 58,95% ZrO2 dengan pengotor terbanyak SiO2 28,21%, Fe2O3 1,30%, dan TiO2 6,68%. Kadar zirkon sebesar ini belum ekonomis apabila digunakan untuk pembuatan zirkonia semi stabil, oleh karena itu perlu dilakukan peningkatan kadar sehingga mencapai kadar >65% ZrO2. Peningkatan kadar pasir zirkon dilakukan melalui pemisahan mineral pengotornya dengan menggunakan kombinasi serangkaian peralatan yang terdiri dari meja goyang, pemisah magnetik, dan high tension separator (HTS). Dari hasil percobaan peningkatan kadar diperoleh konsentrat pasir zirkon berkadar 66,15% ZrO2, dengan perolehan sebesar 88,95%. Untuk memperoleh zirkonia semi stabil, bahan penstabil berupa campuran CaO dengan MgO ditambahkan ke dalam zirkonia berkadar 93,81% yang dibuat dari pasir zirkon dengan cara mixing dan sintering. Untuk mendapatkan kondisi pembuatan zirkonia semi stabil (PSZ) yang baik, perlu dilakukan percobaan dengan memvariasikan suhu sintering dan jumlah bahan penstabil. Kemudian produk yang diproleh dianalisis kadar ZrO2nya dan diuji bentuk struktur kristalnya dengan difraksi sinar-x. Hasil difraksi sinar-x terhadap zirkonia semi stabil (PSZ) yang diperoleh menunjukkan hanya puncak ZrO2 dengan bentuk struktur kristal tetragonal terjadi pada suhu sintering 1100oC dengan jumlah bahan penstabil 11% mol (5%berat) CaO dan 11% mol (3,6%berat) MgO
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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