• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.4
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• pp.27-33
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• 2000

A new technique for fractionating pulp stock into a long fiber portion and fines fraction was developed by KRICT in order to enhance the drainage and strength properties of recycled OCC pulp. In order to investigate the effect of fines contents in stock and stages of flotation on fractionation efficiency, flotations were performed at varied fines contents and flotation stages. Based on the result of multi-stage flotation fractionation it could be said that fines smaller than 15${\mu}{\textrm}{m}$ stabilize flotation froth of OCC. Although the amounts and the fines contents of flotation reject could be increased by multi-stage flotation fractionation of OCC, flotation stages more than 3 times were found to be inefficient in terms of fines concentrating degree. In order to satisfy the both conditions of reducing long fiber loss and of increasing flotation reject, several kinds of fractionating promoters were searched and investigated. And high molecular weight cationic polyacrylamide was chosen as a long fiber flocculating and flotation froth-stabilizing agent.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.4
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• pp.501-507
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• 2006

Dissolved air flotation (DAF) has been well known for the gravity separation process. The solids to be separated are transferred from the water body to the water surface using micro-air bubbles. DAF has also been used for enhancing solids-liquid separation of industrial and municipal wastewater by adding a its unit parallel to a sedimentation unit to reduce the hydraulic loading in the sedimentation clarifier. This study was to investigate flotation characteristics of activated sludge by the recent DAF technique without chemical agents. In addition, the effect on temperature in flotation of activated sludge and the thickening degree of activated sludge were studied.

• Journal of Environmental Science International
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• v.15 no.1
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• pp.77-84
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• 2006

An effective technique of sludge separation is required for excess sludge of sewage or wastewater plant. The separation of bulking sludge of paper manufacturing plant was studied using DAF(Dissolved Air Flotation) system. The effects of parameters such as nozzle type, A/S(air/solid) ratio. pressure, injection time of pressured water and saturation time were examined. The results showed that the best nozzle type was flat which had small orifice hole, The optimum A/S ratio and pressure were $7.070\times10^{-3}$(recycle ratio of pressured water $20\%$) and 5atm, respectively. Injection times of pressurized water around 20-25 sesc and flotation time of 30 min appeared to be optimal for the DAF operation. The order of performance of packing was 18 mm > 22 mm > 32 mm.

• Journal of Soil and Groundwater Environment
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• v.18 no.7
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• pp.41-53
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• 2013

The study is to propose the optimal separation technique of heavy metals (Pb and Zn) contaminated in soil for improving the removal efficiency by various applicable techniques. The heavy metal contaminated soil samples near abandoned mine X-1 and X-2 were used for the study. Firstly, the wet classification process was shown more than 80% of removal efficiency for lead and zinc. Meanwhile, the magnetic separation process was shown low removal efficiency for lead and zincs because those heavy metals were non-magnetic materials. For the next step, the flotation separation process was shown approximately 24.4% of removal efficiency for zinc, while the gravity concentration process was shown approximately 57% of removal efficiency for lead, and 19.9% of removal efficiency for zinc, respectively. Therefore, zinc contaminated in soil would be effectively treated by the combination technique of the wet classification and the flotation technique. Meanwhile, lead contaminated in soil would be effectively treated by the combination technique of the wet classification process and the flotation process. Furthermore, the extraction of organic matter was shown more effective with aeration, 3% of hydrogen peroxide and 3% of lime such as calcium hydroxide.

• Environmental Engineering Research
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• v.14 no.4
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• pp.220-225
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• 2009

The water quality in eutrophic lakes is affected by serious problems, such as abnormal increasing of Cyanobacteria. The purpose of this study was to investigate the possibility of a modified flotation system using a hybrid technique formed by chemical compounds and an electrostatic bridge. Therefore, experiments using the hybrid technique were performed to measure the zeta potential value on the phytoplankton surface and the removal efficiencies of phytoplankton, ammonia nitrogen, nitrate nitrogen and phosphoric acid. The results were as follows: Firstly, the zeta potential of M.aeruginosa was observed to approach charge neutralization due to adhesion of magnesium hydroxide precipitate on the phytoplankton surface in the pH range 10.5 to 11. Secondly, the concentration of chlorophyll-a decreased from about 150 to 20${\mu}g$g/L, with a maximum removal efficiency of 84% due to coagulation with pH values higher than 10. Thirdly, the N$H_4$-N concentration was observed to decrease from 0.62 to 0.54mg-N/L (13%), and the P$O_4$-P concentration, which is a limiting factor to the formation of algae blooms, decreased from 0.27 to 0.02mg-P/L (92%). These findings suggest that the modified flotation system can be applied for the purification of the raw water of numerous lakes containing high phytoplankton populations and elevated pH.

• Bulletin of the Korean Chemical Society
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• v.20 no.4
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• pp.431-435
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• 1999

An organic precipitate flotation of Cd(Ⅱ) and Pb(Ⅱ) was investigated by the coprecipitation with lanthanum 8-hydroxyquinolinate. Trace amounts of Cd(Ⅱ) and Pb(Ⅱ) with a significantly large amount of La(Ⅲ) were simultaneously precipitated in a 1,000 mL sample solution with the ethanolic 8-hydroxyquinoline solution. The pH was adjusted to 9.0 with 2 M ammonia solution. The precipitates were floated with the aid of tiny nitrogen bubbles and supported by the stable foam layer of sodium lauryl sulfate. The floats were collected on the fritted glass filter by a suction. The material collected was dissolved with 5.0 mL of ethanol and 1.5 mL of concentrated nitric acid, and then diluted to 25.0 mL with a deionized water. The analytes were determined by a flame atomic absorption spectrophotometry. The recoveries of the analytes spiked in the sample were 94.8% for Pb(Ⅱ) and 92.0% for Cd(Ⅱ). This flotation technique is simple and rapid, and also applicable to the determination of trace Cd(Ⅱ) and Pb(Ⅱ) at lew ppb levels.

• Resources Recycling
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• v.7 no.5
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• pp.26-32
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• 1998

Recycline of used plastics is rather restricted due to their variety and difficulties in their separation. In this study, a reliable and economical method for the separation of PVC which utilizes an appropriate control of surface chemistry of pariticles was suggested. this method consists of modification of PET surface from hydrophobic to hydrophilic by NaOH solution and subsequent separation by a froth flotation technique. Flotation results were in terms of NaOH concentration, digestion temperature and time, temperature and pH of solution, PVC concentration. They could be separated up to 95~100% by this method.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.15-24
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• 1999

A new technique for recycling of white water was developed in order to reduce the calcium hardness in a closed OCC recycling system. Calcium ions present in the white water were precipitated as calcium carbonate by reacting with sodium carbonate, and the precipitated $CaCO_3$ was removed from the system using a flotation fractionation method, which has been commonly used in deinking process. In the flotation stage, a mixed gas of $CO_2$-air was purged into the flotation cell because the pH of $Na_2CO_3$-treated white water was reduced to neutral by $CO_2$ gas. Since $CaCO_3$ precipitate tends to stick onto fine fiber surface and then selectively removed from the white water, a proper amount of suspended solid in white water acts as an important factor for deciding the removal efficiency. By the application of $Na_2CO_3$ addition-$CO_2$ flotation to the short circulated white water, the calcium hardness was significantly reduced by 87% and more. Removal of calcium ions with fine fibers led to a drainage improvement, reduction of fresh water consumption, and enhanced efficiency of wet-end chemicals.

• Resources Recycling
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• v.21 no.4
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• pp.44-52
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• 2012

The purpose of this study is to confirm the possibility of obtaining high grade coal from fixed carbon 20.68% coal. Also, the mineralogical, physical/chemical and liberation characteristics was found with the aim of decrease in ash amount, during the pre-processing of clean coal technology. In this study, batch flotation and microbubble column flotation that was appropriate for the processing of fine particles was used with the variation in kinds and quantity of frother, collector and depressant. Also grinding time, air flow rate and feeding rates were examined. As a result of batch flotation, using pulp density 20%, collector DMU-101+dodecyl amine(100 mL/ton), frother pine oil (200 mL/ton), depressant sodium silicate(1 kg/ton), obtained the result of ash rejection 81.55% and combustible recovery 70.23%. In result of microbubble column flotation, the result was ash rejection 83.85% and combustible recovery 70.42% under the condition of pulp density 5%, grinding time 5 min. collector DMU-101+DDA(100 mL/ton), frother AF65(5.4 L/ton), depressant SMP(3.5 kg/ton), wash water(360 mL/min.) and air flow rate(1,197 mL/min.).

• Bulletin of the Korean Chemical Society
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• v.24 no.12
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• pp.1775-1780
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• 2003

A continuous flow system has been developed to determine trace Cu(II), Mn(II), Ni(II) and Zn(II) in a large volume of water samples by a solvent sublation technique. The mixed solution of 1,10-phenanthroline(phen) and thiocyanate ion was used as ligands for the formation of their ternary complexes. The continuous system was constructed in this laboratory with a peristaltic pump, a mini shaker, three mixing bottles and a flotation cell by connecting each part with a polyethylene tube. The flotation conditions such as the flow rate of sample solution and the injection rates of ligand, buffer and surfactant solutions have been investigated to obtain the best sublation efficiencies. Each solution flowed into the flotation cell through each polyethylene tube by the peristaltic pumps. The ternary complexes were floated and extracted into MIBK in a flotation cell of 2 L by bubbling a nitrogen gas. The absorbances of extracted analytes in MIBK were directly measured by graphite furnace-AAS. The concentrations of 1,10-phenanthroline and thiocyanate ion were $2.6\;{\times}\;10^{-3}$ M and $2.3\;{\times}\;10^{-2}$ M in the mixed solution, respectively. The pH of sample solution was adjusted to 5.0 with a buffer solution and 1%(m/v) sodium lauryl sulphate solution was added as a surfactant to support the effective flotation of the complexes. The $N_2$ gas was bubbled at 30 mL/min for 90 minutes for 20 L of sample. Reproducible results of less than 10% RSD and recoveries of 80-120% could be obtained in real samples.