• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.208-215
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• 2010

EAF dust which is contained around 30% of zinc, 15% of iron and 3% of lead individually, is chemically treated by ammonium chloride, ammonia water, ammonia gas and carbon dioxide, and also tested and identified the ratios of the recovery of In by applied the variations of particle size, pH and heating temperature as well, in order to getting optimized recovery of the In metal after performing all of those processes. Experimental results showed that the rate of Zn recovery is 97% when the mixture of 1.3 of $NH_4Cl$/EAF is heated to the temperature of $400^{\circ}C$ and leached by water, and 95% recovery of In when ammonia gas and carbon dioxide is added simultaneously and adjust the 9.5 of pH to the same mixture above. For the purpose of remove the impurities in the mixed sample, which is prepared by the two samples, indicated above showing as the ratio of 95% and 97% recovery, in case of applied the cementation process to it, and also by electrolytic process, produced the In plate of 95~97%, and acquired 99-99.5% of In metal ingot finally by applied the heating process at $470{\sim}500^{\circ}C$.

• Resources Recycling
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• v.12 no.2
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• pp.36-44
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• 2003

The present work relates to the recovery of dissolved Mo from spent mandrel dissolving acid solution by injecting ammonia gas. In order to optimize the process parameters for high yield and high purity of recovered Mo products, a bench scale and a pilot scale experiments were carried out. As a result, more than 99.5% of Mo in spent acid was recovered in the form of ammonium molybdate(4MoO$_3$.$2NH_3$.$H_2$O). The purity of Mo products recovered was higher than 99.5%. In addition, the mother liquor, residual solution after precipitation and filtration of ammonium molybdate solid particles, could be utilized as fertilizers.

• Journal of the Korean Institute of Gas
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• v.21 no.1
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• pp.43-51
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• 2017

Recently, ammonia leak occurred frequently in the domestic refrigeration manufacturing facilities. Ammonia caused great damage to the environment and human health in the event of an accident as combustible gases and toxic gases. After considering the types of ammonia accidents of domestic refrigeration manufacturing facilities and selected accident scenarios and to analyze the risk analysis through Impact range estimates and frequency analysis and there was a need to establish measures to minimize accident damage. In this study, depending on the method of analysis quantitative risk assessment we analyzed the risk of the receiver tank of ammonia system. Scenario analysis conditions were set according to the 'Technical guidelines for the selection of accident scenario' under the chemicals control act and 'Guidelines for chemical process quantitative risk analysis' of center for chemical process safety. The risk estimates were utilized for consequence analysis and frequency analysis by SAFETI program of DNV, event tree analysis methodology and part count methodology. The individual risk of ammonia system was derived as 7.71E-04 / yr, social risk were derived as 1.17E-03 / yr. The derived risk was confirmed to apply as low as reasonably practicable of the national fire protection association and through risk calculation, it can be used as a way to minimize accidents ammonia leakage accident damage.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.163-172
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• 2024

In this study, two different scenarios for ammonia liquefaction in the green ammonia manufacturing process were proposed, and the economic-feasibility and environmental impact of each scenario were analyzed. The two liquefaction processes involved gas-liquid separation before cooling at high pressure (high pressure cooling process) or after decompression without the gas-liquid separation (low pressure cooling process). The high-pressure cooling process requires higher capital costs due to the required installation of separation units and heat exchangers, but it offers relatively lower total utility costs of 91.03 $/hr and a reduced duty of 2.81 Gcal/hr. In contrast, although the low-pressure cooling process is simpler and cost-effective, it may encounter operational instability due to rapid pressure drops in the system. Environmental impact assessment revealed that the high-pressure cooling process is more environmentally friendly than the low-pressure cooling process, with an emission factor of 0.83 tCO₂eq less than the low-pressure cooling process, calculated based on power usage. Consequently, the outcomes of this study provide relevant scenario and a database for green ammonia synthesis process adaptable to various process conditions.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.235-236
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• 2014

An experimental study has been carried out to investigate a thermal decomposition of urea solution at relative low temperature with a lab-scaled exhaust pipe. The conversion efficiency of reductant considered with both ammonia and HNCO related with the urea injection quantity, inflow gas velocity and temperature. The conversion efficiency of ammonia was larger than that of HNCO under all experimental conditions unlike the theoretical thermolysis reaction.

• Korean Journal of Organic Agriculture
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• v.23 no.2
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• pp.335-346
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• 2015

The objective of this study was to evaluate the effect of dietary rosemary on performance, microflora population in cecum and noxious gas emission from litter of broiler. A total of 216 broiler chicks at 7 days old were fed the commercial diet (control), added 0.5% level of dried rosemary leaves (5 g/kg diet, T1) and 1.0% level of dried rosemary leaves (10 g/kg diet, T2) for 4 weeks. The body weight gain and feed conversion ratio were improved by feeding rosemary at 7 to 35 days of age (P<0.05), but there was no difference between T1 and T2. Amount of feed intake and mortality were not different among the three group. There was an increase in the microflora population of Lactobacillus (P<0.05) and decreased in E. coli and salmonella (P<0.05) in the cecum contents at 21 and 35 days of age. Emission of ammonia gas from litter was significantly decreased by supplementary rosemary at 21 to 35 days of age (P<0.05), but there was no difference between T1 and T2. These results indicated that feeding 0.5 to 1.0% level of dried rosemary leaves during broiler production improved in the body weight gain and feed conversion ratio because of increasing nutrient digestibility from feed, also increase in intestinal beneficial bacteria and decrease in harmful bacteria in the cecum contents, and decreasing emission of ammonia gas from litter.

• Korean Journal of Agricultural Science
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• v.37 no.1
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• pp.53-60
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• 2010

Two experiments were conducted to investigate the effect of probiotics on the malodor removal. In experiment 1, dietary effects (several malodorous gas concentration of excreta, dry matter metabolizability, and blood profiles) were determined using laying hens. A total of 30 Hy-line brown layers, 68-wk of age, were randomly allocated into 5 groups with 3 replicates of 2 birds each. The treatments were probiotics free, 0.2% and 0.4 % addition of mixed probiotics (Bacillus subtilis PNG-4 +Lactobacillus acidophilus LAS), and 0.2 and 0.4 % addition of single probiotics (Bacillus subtilis PNG-4). In experiment 2, the effects of mixing of probiotics into the excreta on the malodorous gas removal was investigated. There were three treatments (probiotics free, Bacillus subtilis PNG-4 +Lactobacillus acidophilus LAS, and Bacillus subtilis PNG-4) with three replicates. The malodorous gas concentrations were detected at 0, 3, 7 and 14 day of incubation. In experiment 1, ammonia concentration was significantly decreased by feeding mixed probiotics at 14th day of incubation. However, amines, hydrogen sulfide, ethylmercapthan, and methylmercapthan were not significantly affected by mixed probiotics. Dry matter metabolizability was significantly increased by feeding probiotics, but no significant differences between single and mixed probiotics. There was no significant differences in blood profiles. In experiment 2, mixing of probiotics into the excreta did not affect the concentration of ammonia, amines, hydrogen sulfide, ethylmercapthan, and methylmercapthan. Therefore, these experiments suggested that Bacillus subtilis PNG-4 + Lactobacillus acidophilus LAS supplementations could improve ammonia gas removal, and dry matter metabolizability in layers. Also, decrease of ammonia concentration was higher in mixed probiotics group compare to the single probiotics group. On the other hand, mixing of probiotics into the excreta appeared not to be a useful method.

• Clean Technology
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• v.18 no.2
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• pp.209-215
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• 2012

The performance and removal efficiencies of a pilot scale biofilter were estimated by using ammonia and hydrogen sulfide as the odorous gases. Expanded polyurethane foam coated with powdered activated carbon and zeolite was used as a biofilm supporting medium in the biofilter. Odorous gases from the sludge thickener of a municipal wastewater treatment plant were treated in the biofilter for 10 months and the inlet ammonia and hydrogen sulfide concentrations were 0.1-1.5 and 2-20 ppmv, respectively. The removal efficiencies reached about 100% at the empty bed retention time (EBRT) of 3.6-5 seconds except for the adaptation periods. The pressure drop of the biofilter caused by the gas flow was also low that the maximum attained was 31 mm $H_2O$ during the operation. Its stability was confirmed in the long term due to the fact that the biofilter and the polyurethane medium had a minimum plugging and compression. The microbial community on the medium is critical for the performance of the biofilter especially the distribution of ammonia oxidizing bacteria (AOB) and sulfur oxidizing bacteria (SOB). The distribution of Nitrosomonas sp. (AOB) and Thiobacillus ferroxidans (SOB) was confirmed by FISH (fluorescence in situ hybridization) analysis. The longer the operation time, the more microbial population observed. Also, the medium close to the gas inlet had more microbial population than the medium at the gas outlet of the biofilter.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.287-291
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• 2009

The heterogeneous decomposition of ammonia on a quartz surface in an inverted, stagnation-point flow reactor was investigated using a measurement reactor and a numerical model of the reactor. In the experiments, 8 mole% of ammonia in nitrogen was used and the temperature of an electric heater was set in the range $300{\sim}900^{\circ}C$ to heat the quartz surface where the decomposition took place. Gas temperatures and ammonia concentrations in the reactor obtained using in situ Raman spectroscopy were analyzed with the numerical model and it was revealed that, depending on the heater temperature, the temperature of the quartz surface was estimated to be in the range $235{\sim}619^{\circ}C$ and the activation energy of the decomposition on the surface was in the range 10.9~15.8 kcal/mol.

• Journal of Environmental Health Sciences
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• v.35 no.5
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• pp.393-401
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• 2009

We isolated and identified a microorganism which was excellent for ammonia oxidation in the biological control of ammonia gas in odor producing materials from organic composting. The isolated strain was tested for growth characteristics and ammonia elimination efficiency under various conditions of temperature, pH, carbon concentration and ammonia concentration. The strain was isolated from a culture broth used in a $NO_2$ producing test with Griess-Ilosvay reagent. The results of 16S rRNA sequence from the isolated strain by using BLANST (Basic Local Alignment Search Tool) and confirming RDP (Ribosomal Database Project II) and ERRD (The European Ribosomal RNA Database) indicate that the strain is related to Delftia sp. UV-Spectrophotometer (Shimadzu, UVmini-1240) was used as a microbial growth test by measuring turbidity on OD660nm and ammonia concentration was measured by Spectrophotometer (HACH, DR-4000). The optimum growth culture conditions of the ammonia oxidizer Delftia sp. were $30^{\circ}C$, pH 7, glucose concentration 1.00% and $(NH_4)_2SO_4$ 0.5 g/l. Ammonia elimination efficiency was over 94% under the same conditions.