• Journal of Powder Materials
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• v.2 no.2
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• pp.135-141
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• 1995

As the first step of study on fabrication of ceramic powders from phytoliths in rice, especially in rice husks, pulverization method of rice husks and the properties of milled rice husks were investigated. Impact methods, such as ball milling, were not meaningful for pulverizing elastic and thin fabric structure of rice husks. The most effective one was cutting method. In the present work, a rotating knife cutting method was applied to pulverizing rice husks. A 40-mesh screen was inserted under the rotating knives. The most portion of the milled powder was found in -50/+100 mesh section. Morphology of the milled rice husks revealed that the husks larger than 70 mesh were flake-like shape, at -70/+100 mesh section relatively equi-axed shape, at -170/+325 mesh section rod-like shape, and below 325 mesh section dust-like shape. Tap density of raw rice husks was about 0.1 $g/cm^3$, while those of milled rice husks were over $0.4 g/cm^3$. This meant that, for a given volume of reactor, raw material charge can be increased more that 4 times when using milled rice husks than unmilled one. True densities of unmilled and milled rice husks were higher than $1.4 g/cm^3$, and increased with decreasing milled sizes.

• Journal of Biosystems Engineering
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• v.23 no.1
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• pp.13-20
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• 1998

Carbonized rice husk(char from rice husk) can be used to improve soils for planting, seedlings, horiculture, pomiculture and truck gardening. Although it is not a fertilizer in nature, it stimulates the growth of plants. Carbonized rice husk is highly recommended for raising soil/water temperature, keeping moisture and aerating roots of plants. The objective of this study was to develop the effective production method of carbonized rice husks by a non-slagging vertical cyclone combustor. A cyclone combustor w vortex collecor Pocket in addition to central collector pocket was selected and tested. Isothermal tests and mixed firing with LPG and rice husk were performed in order to characterize the system. hut rice husk was used during the isothermal test to find the mass collected of rice husk. It was impossible to ignite rice husk itself over the experimental conditions considered in this experiment. The composition of original and carbonized rice husks was analyzed by the ultimate analysis. With the air flow rate of 20 ㎥/h, LPG flow rate of 0.45 1/min, the required carbonized rice husk could be obtained.

• Journal of Biosystems Engineering
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• v.33 no.4
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• pp.248-252
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• 2008

An experiment was conducted in order to investigate gasification characteristics of rice husks in a fixed bed, which was a pre-step to design a continuous gasification system. Two air supply levels for gasification were chosen and their effects on the producer gas amount and producer gas composition were discussed. The main components of the producer gas were CO, $CO_2$, $O_2$, $H_2$ and THC (Total HydroCarbon). As airflow rate decreased, more producer gas was produced. The peak amount of CO, $H_2$ and THC were 28%, 7.5% and 0.68% in volume when constant airflow rate of $3.36\;m^3/s$ was used in the batch operation. About 4.5 kg of ash (9%) and condensed water including tars of 6 kg (11%) were produced from 50 kg rice husks in the gasification. Excluding the byproducts, all rice husks seemed to be transformed into producer gas. This gasification study was conducted prior to developing a continuous gasification system for biomass including agricultural byproducts.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.511-518
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• 2017

In recent years, many interests and researches on the insulations required the multiple performances other than insulation performance. The purpose of this paper is to find the optimal ratio between wood fiber and rice-husks charcoal to develop a structural board with carbonized rice-husks. Based on these rice-husks charcoals, basic research was carried out to develop thermal insulation materials with structural performance, and the following conclusions were obtained. The MC of the board using the carbonized rice-husks was 3.2-4.1% and the density was 0.58-0.68, indicating the possibility of excellent structural material. The bending strength was 9.1-32.6 MPa in the length direction and 9.2-34.1 MPa in the width direction. It is possible to obtain the bending strength of the normally used MDF level and to find the possibility of development of the thermal insulation material having the structural performances.

• Journal of Animal Science and Technology
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• v.65 no.2
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• pp.377-386
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• 2023

The effect of different commercially available bedding materials on the growth performance and carcass characteristics of ducks for 42 days was investigated. 336 one-day-old White-Pekin ducklings (60.48 ± 0.16 g) were randomly allocated into 24-floor pens with one of the three beddings namely i) coco peat, ii) rice husks, or iii) sawdust. 14 ducklings per pen and 8 replicate pens per bedding material were used. Birds were fed a starter diet from days 1-21 and a grower diet from days 22-42. Weekly growth performance evaluation was conducted for the average body weight, weight gains, daily feed intake, and feed conversion efficiency. One bird per pen was sacrificed on day 42 for the evaluation of carcass characteristics including the carcass, breast, and leg muscle percentages. Breast and leg muscle samples were then collected and analyzed for their proximate and pH values. Higher body weights (p < 0.05) were noticed with rice husks on day 42 only. Improved daily gains (p < 0.05) were also noticed for birds raised with rice husks over the entire period (days 1-42). Concerning feed intake, higher values (p < 0.05) were similarly noted with rice husks for the grower phase (days 22-42), and the entire experimental period (days 1-42). Marginally improved feed intake values were also noted with the use of rice husks as the bedding materials on day 42 (p = 0.092). Improved feed efficiency (p < 0.05) was noticed with rice husks on day 35, the grower period, and the entire 42-day period. However, no significant differences were noticed for most of the carcass characteristics that were evaluated. Nevertheless, higher (p < 0.05) pH values for the breast muscle were noticed with the use of coco peat and sawdust as the bedding. Conclusively, the bedding type could have a significant impact on the growth performance of ducks without adverse effects on carcass characteristics. The use of rice husks as bedding might be advantageous and is therefore recommended.

• Preventive Nutrition and Food Science
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• v.16 no.2
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• pp.179-183
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• 2011

This study was conducted to determine the biological activities of 70% ethanol extracts from rice husks of nine rice cultivars in Korea. The relative antioxidant activities of rice husk extracts were evaluated by determining DPPH, ABTS radical scavenging activity and reducing power. The contents of total polyphenol, flavonoid and r-oryzanol were measured by spectrophotometric methods. Among the extracts of rice husks, Nokmi rice husks tended to have the most effective antioxidant activities compared to other rice husk varieties. Seolgaeng rice husk extract showed anti-proliferative activity against cancer cell lines (MCF7 and NCI-H460), and Hongjinju rice husk extract significantly exhibited mitogenic activity.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.226-226
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• 2017

This study was to evaluate methods to high quality food ramie rice cake, thereby increasing farm income. This study investigated the effects of different covering material on stable winter survival management with edible leaf in Ramie(Boehmeria nivea L.). The method of winter survival with covering material were conducted under three condition compose to Non covering, Rice straw cutting covered with 500kg.10a-1, Rice husks covered with 1,000kg.10a-1(covered 4~5 cm thickness in the soil surface). Method of application were standard application(N-P-K-Compost applied at 27-9-27-600kg.10a-1. Compost and fused phosphate applied at 100% of basal fertilizer in March 25. 20% of top dressing were four times application in March 25 - October 5. Planting year were March 15, 2011. Plants were spaced 60 cm apart in rows 25 cm apart with open cultivation. According to non covering < Rice husks covered with 1,000kg.10a-1 < Rice straw cutting covered with 500kg.10a-1 cultivation this order, aerial part as a result were plenty amount of growth. Sprout time and winter survival rates was uncovering control plot compared to 2 - 5 days quickly, 45-57% highly by rice husks and rice straw covering. Green leaf yields is untreated control plot (12,44 kg.10a-1) compared to rice husks covering 7% higher, and rice straw covering increased to 18% of the most.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.5
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• pp.188-192
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• 2016

In this work, the SiC powders were synthesized through the carbonized matter from the mixture of silica powder and rice husks. The SiC powders, obtained from the carbothermal reduction reaction of silica and carbonized rice husks, were investigated by XRD patterns, XPS, FE-SEM and FE-TEM. In the XRD patterns, the specimens showed clearly very high strong peak of (111) plane near $35^{\circ}$ as well as weak (220) and (311) peak respectively at approximately $60^{\circ}$ and $72^{\circ}$. Under Ar atmosphere, the power synthesized from the mixture (in case of mixing ratio, 6 : 4) of carbonized rice husks and silica showed mainly cubic SiC crystalline phase showing relatively lower ratio of hexagonal phase without residual carbon in XRD pattern. In the TEM analysis, the specimen, synthesized from carbonized rice husks and silica with mixing ratio of 6 : 4 under Ar atmosphere, showed relatively fine particles under $5{\mu}m$ and a crystalline SiC phase of (100) diffraction pattern.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.2
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• pp.45-49
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• 2019

Relatively fine silicon carbide (SiC) crystalline aggregates have been synthesized with the carbonized rice husks, paper sludge, coffee grounds as the carbon sources and the silica powder. The main reaction source to obtain silicon carbide (SiC) aggregates from the mixture of carbon sources and silica was inferred as the gaseous silicon monoxide (SiO) phase, being created from this mixture through the carbothermal reduction reaction. The silicon carbide (SiC) crystalline aggregates, fabricated from the carbonized rice husks and paper sludge, coffee grounds and silica ($SiO_2$) powder, were investigated by XRD patterns, FE-SEM and FE-TEM images. In these specimens, obtained from the carbonized rice husks, paper sludge and silica, XRD patterns showed rather high strong peak of (111) plane near $35^{\circ}$. The FE-TEM images and patterns of specimens, synthesized from carbonized rice husks, paper sludge, coffee grounds and silica under Ar atmosphere, showed relatively fine particles under $1{\mu}m$ and crystalline peak (110) of silicon carbide (SiC) diffraction pattern.

• Journal of Powder Materials
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• v.3 no.2
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• pp.112-119
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• 1996

Using rice husks pulverized by rotating knife cutter, the raw rice husk powder was solution treated by nitric and hydrochloric acids in order to separate phytolith from organic constituents. Because of the strong resistance of organic components of rice husk to acids, the raw powder had to be boiled in concentrated acids up to 300 min. By boiling in nitric acid for 60~120 min, all organic components were resolved while amorphous silica Powder of about 20 nm in size and of higher than 99.8% in purity was left behind. Inferior to the nitric acid, hydrochloric acid was not able to resolve organic component completely leaving unresolved matter of about 40% by weight even after 300 min of boiling. From the acid treatments and impurity analyses, it is considered that most of metallic elements in rice husks are combined to organic components that are easily soluble to acids.