Ho-Seok Jeon

Influence of Metal Cations on Cassiterite Flotation

ABSTRACT Rotation of cassiterite has been studied on pure minerals in a microflotation cell with sulphosuccinamate as a collector in the presence of some metal ions. The results indicate that sulphosuccinamate demonstrates strong collection, good selectivity on cassiterite, especially in the weak acidity region of pH 6.0, and that lead ions have certain activation whereas other metal ions such as ferric, aluminum, manganese, ferrous, and calcium cause strong depression on cassiterite flotation. In addition, X-ray photoelectron spectroscopy (XPS) has been applied to study the flotation mechanism of cassiterite-sulphosuccinamate in the presence or absence of metal cation. A chemisorption mechanism through chemical bonding between stannum species on the cassiterite surface and oxygens from carboxylic and sulphonic acid groups of sulphosuccinamate is considered. The chemical environment of stannum species would be changed in the presence of lead ions in the flotation systems and improve the activity of the st...

Separation of PVC and Rubber from Covering Plastics in Communication Cable Scrap by Tribo-Charging

Abstract Triboelectrostatic separation of PVC and rubber from covering plastics in communication cable scrap has been performed. In this work, particles charged as positive (+) and negative (−) according to the difference of work function of each material after tribo-charging can be separated through an opposite electric field. In charger material selection tests using a vertical-reciprocation charger, PVC and rubber particles in the covering plastics were charged with the opposite polarity in the charger material made of PP, HDPE, or PET. The difference of charge density (charge to mass ratio, nC/g) of the PVC and rubber was higher in the tribo-charger made of HDPE. Furthermore, in lab-scale triboelectrostatic experiments for separating the PVC and rubber, the charging efficiency of the mixed PVC and rubber increased when the air velocity was adjusted to over 8.2 m/s. The charge density, the electrode potential, and splitter position needed for the separation of the PVC were determined to be 25 nC/g, 30 kV and +2 cm, respectively. In the optimum conditions, we developed a separation technique that can separate up to 99.8% PVC grade with 95.0% of recovery from the covering plastics.

Dry and Wet Grinding Effect on Kaolinite and Its Zeolite Formation in NaOH Solution

ABSTRACT Dry and wet grinding effects of kaolinite on the formation of zeolite Na-A and Na-X in NaOH solution are fundamentally investigated. Intensive dry grinding causes the structural deformation of kaolinite into an amorphous state with enhanced chemical reactivity. The degree of the activated state of kaolinite particles is mainly dependent on the grinding time and the activated particles easily react with NaOH to form zeolite Na-A and Na-X according to the degree of activation. The further wet grinding of the activated particles and NaOH can promote the formation of zeolite Na-X and it can be deduced that wet grinding alters the Si/Al ratio of kaolinite particles by a mechanochemical effect during prolonged wet grinding.

MODIFICATION OF CALCINED CLAY AND ITS PHYSICAL PROPERTIES FOR USE AS A SUBSIDIARY MATERIAL FOR GROWING MEDIA

Calcined clay is a granular agglomerate of clay. It has a large surface area and myriad small pores, but also has a low easily available water (EAW) and water-buffering capacity (WBC). In this research, calcined clay was modified to enhance its low EAW and WBC and to allow it to substitute for subsidiary materials like perlite and vermiculite in growing media. To determine the proper size of the unit particles constituting the agglomerates for the matric potential of 1–10 kPa, several sizes of feldspar were agglomerated, and water suction tests were conducted. Based on the proper size, calcined clay was modified and made with kaolin through two steps. The first step consisted in consolidating kaolin by mixing it with water and drying it. It was then crushed and classified into the proper size. The second step consisted in agglomerating the kaolin spherically using a pan-type pelletizer. The fabrication of the modified calcined clay (MCC) was completed by heating it at 900°C for 2 hrs. The granule of MCC was found to have bimodal pores: small pores with diameters of about 1 μm, and pores larger than 10 μm. Through the water suction tests of MCC and its mixture with Canadian sphagnum that were conducted, it was verified that MCC has higher EAW and WBC values compared to the typical calcined clay in growing media.

Cassiterite Flotation with Sulphosuccinamate Collector

ABSTRACT Sulphosuccinamate is one of the best collectors used for flotation of cassiterite. The flotation results show that sulphosuccinamate displays strong collection and selectivity for cassiterite at lower dosage. The influence of other factors, such as depressants and metal cations on the cassiterite flotation has also been investigated. Studies on the mechanism of flotation with sulphosuccinamate, through zeta potential, infrared spectrometer, XPS and molecular orbital theory indicate that multi-ring chelates are formed on the cassiterite surface through chemical bonding between active stannum sites and oxygens in carboxylic and sulphonic acid groups of sulphosuccinamate.

Development of Triboelectrostaic Separation Technique for Recycling of Final Waste Plastic

ABSTRACT In Korea, plastic use increases by 10% every years, because of its good material characteristics such as high function, hygienic, convenient and economic. Especially, Korea ranks 4th in the world in the plastic production and about 4 million tons of waste plastics are generated annually. But, at present, over 80% of waste plastic is disposed by reclamation and incineration and only 20% of waste plastic is recycled, causing problems such as loss of valuable material and environmental pollution by disposal of waste plastics. Among various methods for recycling of waste plastic, the material recycling is the one of the best methods. Therefore, a good separation technique for material recycling has to be developed prior to other techniques. In this study, we carried out the research on development of material separation technique by triboelectrosatic separation. At optimum test conditions, we were able to remove PVC up to 99% from PET.

Application of Jig Separation for Pre-Concentration of Low-Grade Scheelite Ore

Jig separation, one of the oldest methods of gravity separation, is commonly used to reduce the costs of subsequent processes by pre-concentrating the valuable minerals from the product following coarse particle crushing. In this study, jig separation was used to preconcentrate scheelite prior to grinding for the next process. Experiments were carried out using 0.21 to 5 mm samples, in order to determine and evaluate optimal conditions by varying factors, including the thickness of the bed, the water ow rate and the number of scavenging. The results of the experiments show that when pre-concentration of low-grade scheelite ore (0.75% WO3) using jig separation is conducted, a concentrate with a mass percentage of about 22.0%, a WO3 grade of about 3.1% and WO3 recovery of about 90.0% can be obtained. It is therefore expected that when this concentrate is supplied to the next separation process, the grade, economic feasibility, and separation ef ciency will be improved compared with separations that do not involve a pre-concentration. [doi:10.2320/matertrans.M2017150]

Physical separation using an autogenous medium on coal

ABSTRACT The dry beneficiation for 1–5 and 5–10-mm-size coal using an air table was investigated. Separation was conducted using autogenously formed media in the feed coal. The separation density was around 1.8–2.0 g/cm3 and the average Ep (Ecart Probability) value ranged from 0.08–0.1 for the 5–10-mm fraction, to around 0.1–0.12 for the 1–5-mm fraction. For the 5–10-mm fraction, the feed ash decreased from 44% to 8.4% in the clean coal product, with 89.5% ash rejection rate in the rejects. For the 1–5-mm fraction, the feed ash decreased from 33.7% to 9.4%, and the reject ash was 88.7%.

Recovery of Roasting-Molybdenite Concentrate by Froth Flotation

Froth flotation has been carried out in order to produce roasting-molybdenite concentrate from molybdenite ore in the Shin-yeomi mine. In our study, roasting-molybdenite (Mo 0.43%) from Shin-yeomi mine was recovered by varying the conditions of regrinding time, dosage of collector and alkalinity. Liberation and flotation efficiency more were effective at regrinding time of six minutes than at single grinding. Mo recovery curves increased considerably as dosage of kerosene increased, whereas Mo grade curves decreased gradually. The separation efficiency of molybdenite was effective when the dosage of collector (kerosene) was adjusted to 300 g/t. The molybdenite concentrate was agglomerated in the range of pH 5-7 and its separation efficiency increased to pH 9-10. The concentrate of 49.5% Mo grade (MoS2, 82.6%) with 81.5% recovery from Shin-yeomi molybdenite ores was obtained under conditions of 20% pulp concentration, 300 g/t kerosene 325 g/t frother (AF65), 2.5 kg/t depressant (Na2SiO3), pH 9-10 and four cleaning times. In the future, a trial run that can separate up to 50% Mo grade from Shin-yeomi molybdenite ores will be performed.