• 청정기술
• /
• 제29권2호
• /
• pp.87-94
• /
• 2023

폐리튬계 이차전지로부터 유가금속을 회수하는 것은 한정된 지구자원의 활용 측면에서 매우 중요하다. 최근 자동차의 전지로 많이 사용하고 있는 LiFePO₄ 전지 양극재 성분에는 리튬이 약 5.2% 함유되어 있으며, 사용 후 전지에서 리튬 재활용을 통하여 다시 전지의 원료로써 사용할 수 있다. 본 연구에서는 폐LiFePO₄ 양극재 분말에 함유된 리튬을 선택적으로 침출하기 위하여 일반적으로 많이 사용하고 있는 무기산의 일종인 저농도 황산을 이용하였다. 그리고 각 성분의 침출율 및 분리효율을 비교·분석을 위하여 침출 시 광액농도를 변수로 2 스텝 침출 공정을 적용하여 최적의 침출조건을 도출하고자 하였다. 광액농도를 변수로 침출 시 철 및 인 성분이 거의 침출되지 않는 200 g/L의 광액농도 조건에서는 타 조건과 분리 효율이 약 200배 이상 높은 것으로 확인되었다. 이에 리튬의 선택적 침출 및 회수에 있어서 침출조건을 최적화하였다.

• 펄프종이기술
• /
• 제31권3호
• /
• pp.10-18
• /
• 1999

The influence of simple electrolyte or anionic trashes on cationic starch adsorption was examined using deinked pulp and bleached thermomechniical pulp. Adsorbed amounts of cationic starches increased slightly , then decreased abruptly as the concentration of simple electrolyte increased. This phenomenon was discussed based on the compression of electrical double layer and conformation change of starch molecules. Also, the effect of the type of simple electrolytes on starch adsorption was examined and discussed. Addition of sodium slilicate increased starch adsorption since it increased surface charge density of fibers. On the other hand, addition of kraft lignin decreased cationic demand of the pulp slurries and adsorbed amounts of cationic starches. Nonionic surfactant did not show any significant effect on the cationic demand of pulp slurries. When simple electrolytes were added to the stock , grater adsorption or cationic starches was obtained with starches of lower degree of substitution . On t도 other hand, amount of adsorbed starches decreased for lower DS starches when the concentration of anionic trashes increased.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
• /
• pp.153-159
• /
• 2006

Red algae were used to make bleached pulp, from which paper handsheet samples were made. Red algae consists of rhizoidal filaments, epidermal tissues whose color were reddish, mucous carbohydrates, and other minor elements. Rhizoidal filaments of high brightness were obtained after extracting out mucous carbohydrates, and bleaching the remainder by using bleaching chemicals. The sizes and shapes of several rhizoidal filaments (or red algae pulp) from different red algae species were examined, and their handsheet properties were compared. Transparent and transluscent high density paper samples were made without applying refining process from the red algae pulp. White paper samples with good printability and excellent formation were made. We are developing pilot scale pulping and papermaking facilities at this time.

• 자원리싸이클링
• /
• 제23권1호
• /
• pp.64-69
• /
• 2014

코발트 정광으로부터 코발트와 구리의 회수를 위한 기초 연구로 Aspergillus균주를 사용하여 당밀 배지에서 Co, Cu, Fe, Mg, Al 등의 미생물 침출 거동을 조사하였다. 실험의 주요 변수로는 균주 종류 및 당밀의 당도, 고액농도(pulp density), 반응시간 등의 영향에 대해 고찰하였다. 실험결과 당밀의 농도가 증가할수록 코발트 및 구리의 침출율이 증가하는 경향을 보였으며 적정 당도는 4%이었다. 한편, Aspergillus niger KCTC 6985의 경우 당도 4%, 고액농도가 10 g/L인 조건에서 21일 경과 후 코발트는 최대 90 %, 구리의 경우는 최대 70%의 침출율을 나타내었고, Aspergillus niger KCTC 6144의 경우는 당도 4%, 고액농도가 5 g/L에서 코발트 및 구리가 각각 90%의 최대 침출율을 나타내었다.

• Journal of Microbiology and Biotechnology
• /
• 제26권11호
• /
• pp.1871-1880
• /
• 2016

Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

• 펄프종이기술
• /
• 제30권4호
• /
• pp.69-78
• /
• 1998

Papers loaded with 10-40% $TiO_2$ by dry weight were calendered under the various combinations of calendering conditions such as calender type, linear pressure, and roll temperature. After being calendered, light scattering coefficient, surface roughness, density, and tensile strength of the papers were measured and the results were summerized as follows: 1. To increase the light scattering coefficient of $TiO_2$-highly-loaded paper further by calendering, the calender roll pressure and temperature should be kept low. Under these conditions, the physical strength of the paper was not significantly affected. 2. At low roll temperature, soft nip calender and machine calender type showed the same relationship between paper density and its roughness. At high roll temperature, soft nip calender type gave much lower roughness than machine calender type at the same density. 3. At high roll temperature of both calenders, the density as well as the tensile strength of the TiO$_2$-loaded paper was increased significantly.

• 펄프종이기술
• /
• 제32권1호
• /
• pp.26-32
• /
• 2000

The impact of major surface chemical properties of silica sols on the retention and drainage performance of the silica based micrparticle system, Compozil was investigated using four different silica sols. And the effect of silica properties on the interactions with cationic starch and cationic plyacrylamide has also been identified. The surface charge density and the stability over pH of silica sols were increased by introducing aluminosilicate anions at surface. It was found that the charge density of silica sols determined the addition level necessary to attain the maximum retention and drainage. When silica sols were combined with cationic starch, the change density of the product was the critical properties and the degree of microagregation was of minor importance. In the cationic polyacrylamide system the degree of colloid structure appeared to be a more critcial property than the charge density of silica sols.

• 펄프종이기술
• /
• 제38권5호
• /
• pp.66-73
• /
• 2006

The effects of active packaging on the surface stiffness, mass, volume, density and weight changes of fresh as well as stored eggplant were studied at 11 and $25^{\circ}C$ for 10 days with active packaging material Type 1 and 2 and control. Mass, volume, and surface stiffness of eggplant decreased linearly throughout the storage period regardless of storage conditions; while the mass density showed a reverse trend in the ease of $11^{\circ}C$ storage. Reduction rate of mass, mass density and weight was observed minimum at $25^{\circ}C$ storage temperature with active packaging Type 1. The weight of eggplant decreased at a higher rate in the initial 4 days compared to that in the later period of storage regardless of storage temperature and type of packaging.

• 펄프종이기술
• /
• 제33권1호
• /
• pp.38-44
• /
• 2001

The effects of refining load on the paper properties were investigated. HwBKP, SwBKP and SwUKP were refined with PFI mill at the load of 3.33 N/mm and 6.00 N/mm. Higher Scott bond was obtained at the higher refining load for three pulp used in this study. However any changes in the light scattering coefficient with the change of refining load were not observed. Although the effect of refining load on the formation index for SwUKP was not observed, higher refining load gave the better formation for HwBKP and SwBKP. The fiber mass and fiber crowding factor were not affected by the refining load. Higher apparent density and tensile index were obtained with the higher refining load. However, the higher refining load did not improve the tensile index at the same apparent density. The tear index was decreased with the increase of refining load.

• 펄프종이기술
• /
• 제35권3호
• /
• pp.79-84
• /
• 2003

Oriental painting paper (Hwaseonji) was prepared from various kinds of plant fibers and its physical properties were investigated. The fibers used were classified into three different length of fibers; long fiber (<1.8 mm), medium fiber (1.4-1.8 mm) and short fiber (>1.4 mm). The fibers were mixed in the ratio of 15% long fiber, 25% medium fiber and 60% short fiber. The Hwaseonji prepared from mixing of the bamboo or rice straw pulp as a short fiber with the long and medium fibers showed excellent physical properties with a high smoothness and uniformity of Chinese ink blot. Mixing with LBKP as a short fiber was resulted in low physical properties, smoothness and wide ink blot. The properties of Hwaseonji, such as ink absorption, roughness and smoothness, may be predicted from the correlation of density with Chinese ink blot and smoothness.