Specific Gravity Separation Research Articles

Characteristics and environmental significance of organic carbon in sediments from Taihu Lake, China

The rapid economic development in the Yangtze River Delta has affected the carbon (C) pool in lake sediments, which has become a serious environmental management issue. To explore the characteristics of composition, spatial distribution and burial of organic C (OC) in lacustrine sediments, a typical shallow lake was targeted to compare the heavy fraction OC (HFOC), light fraction OC (LFOC), and dissolved OC (DOC) in the surface sediments of different lake areas using the specific gravity separation approach. The effects of environmental factors on the form of OC present were identified by a redundancy analysis. The results showed a regional difference of DOC, LFOC, and HFOC concentrations in Taihu Lake, and HFOC was dominant in the OC buried in lake sediments. The deposition rate of OC in Taihu Lake sediments varied in a ranged of 31.91–114.47 g C m−2 a-1. The LFOC levels in the sediments were lower than those in other lakes. Both sedimentary LFOC and HFOC were significantly correlated with the nitrogen (N) content, indicating that the C sink was enhanced by an increase in N in the sediments. The grass-type lake zone stimulated C accumulation in Taihu Lake sediments.

Effect of specific gravity separation on seed quality improvement of coriander var. CO3

An attempt was made to study the effect of specific gravity separation on seed germination and biochemical properties of coriander var. CO3 seed at Agricultural Engineering College and Research Institute, TNAU, Kumulur, Tiruchirappalli District, Tamil Nadu. The seeds were graded in a specific gravity separator <i>viz.,</i> horizontal height (cm), vertical height (cm) and air blow rate (m³/hr) adjustments of 0.5, 1.0 and 3.5, respectively at 485 rpm. Coriander seeds were classified into five grades, numbered one through five, and labeled A, B, C, D, and E (grade A represents light weight seeds and grade E represents heavy weight seeds). The seeds were graded and then tested for seed recovery percentage, 100 seed weight, seed filling percentage, germination percentage, speed of germination, seedling length (cm), dry matter production (g/10 seedlings), vigour index, field emergence (%), and biochemical analysis. The results revealed that higher germination per cent was recorded in the E grade (74 per cent) than A, B, C and D grades as well as F-ungraded bulk seeds. Estimation of storage reserves revealed that variation existed among the grades separated by the specific gravity separator. E grade seeds recorded higher protein, oil and carbohydrate contents, which would have substantiated the higher germination, vigour and field emergence.

Effect of specific gravity separation on seed quality improvement of coriander var. CO3

An attempt was made to study the effect of specific gravity separation on seed germination and biochemical properties of coriander var. CO3 seed at Agricultural Engineering College and Research Institute, TNAU, Kumulur, Tiruchirappalli District, Tamil Nadu. The seeds were graded in a specific gravity separator <i>viz.,</i> horizontal height (cm), vertical height (cm) and air blow rate (m³/hr) adjustments of 0.5, 1.0 and 3.5, respectively at 485 rpm. Coriander seeds were classified into five grades, numbered one through five, and labeled A, B, C, D, and E (grade A represents light weight seeds and grade E represents heavy weight seeds). The seeds were graded and then tested for seed recovery percentage, 100 seed weight, seed filling percentage, germination percentage, speed of germination, seedling length (cm), dry matter production (g/10 seedlings), vigour index, field emergence (%), and biochemical analysis. The results revealed that higher germination per cent was recorded in the E grade (74 per cent) than A, B, C and D grades as well as F-ungraded bulk seeds. Estimation of storage reserves revealed that variation existed among the grades separated by the specific gravity separator. E grade seeds recorded higher protein, oil and carbohydrate contents, which would have substantiated the higher germination, vigour and field emergence.

Separation of Flame and Nonflame-retardant Plastics Utilizing Magneto-Archimedes Method

In physical recycling process, the quality of recycled plastics becomes usually poor in case various kinds of plastic materials are mixed. In order to solve the problem, we tried to separate flame and nonflame-retardant plastics used for toner cartridges as one example of mixed plastics by using magneto-Archimedes method. By using this method, we can control levitation and settlement of the particles in the medium by controlling the density and magnetic susceptibility of the medium and the magnetic field. In this study, we introduced the separation system of plastics by the combination of wet type specific gravity separation and magneto-Archimedes separation. In addition, we examined continuous and massive separation by introducing the system which can separate the plastics continuously in the flowing fluid.

Micro-flotation removal of coal contaminants from archaeological radiocarbon samples from Chaco Canyon, New Mexico, USA

Micro-flotation, a specific gravity separation technique, was successfully used to remove coal contaminants from radiocarbon samples obtained from profiles, unit excavations, and solid sediment cores in Chaco Canyon, New Mexico, USA. Coal from the Cretaceous Menefee Formation occurs throughout Chaco Canyon in aeolian, alluvial, colluvial, and anthropogenic sediments. The Menefee Formation contains carbonized broadleaf angiosperm and gymnosperm plants and, as such, paleobotanical analysis was not effective in the identification and removal of coal contaminants. The effectiveness of micro-flotation as a pretreatment procedure was evaluated by: i) comparing AMS radiocarbon ages on processed and unprocessed samples from the same archaeological contexts; ii) comparing a processed sample of carbonized hardwood charcoal with a sample of uncarbonized hardwood from the same archaeological context; and iii) comparing radiocarbon ages on a split sample of processed bulk carbon. The comparisons confirmed the effectiveness of micro-flotation in processing samples for radiocarbon dating in Chaco Canyon and would be applicable for similar locations elsewhere in the world.

Flotation techniques to improve viability of Juniperus polycarpos seed lots

The germination of freshly collected Juniperus polycarpos (K. Koch) seeds is very low and attributed to the large proportion of nonviable seeds in the seed lots. Thus, the aim of this study was to improve seed lot quality by removing nonviable seeds using two flotation techniques: incubation-drying-separation (IDS) and modified specific gravity (MSG) separation. We examined different IDS conditions (the specific incubation time, subsequent drying time and sorting media) for effectively sorting out nonviable seeds; and tested the feasibility of modified SG separation, which involved soaking seeds in water for a certain period before sorting in different concentrations of sucrose solution. Viable seeds were expected to absorb and metabolically bind more water during soaking than dead seeds could, and hence be sorted effectively depending on the viscosity of the sucrose solution. The viability of the seeds that floated or sank was determined in a topographical tetrazolium chloride (TTC) test. For the IDS trial, 7 days incubation followed by 9 h of drying and sedimentation in pure water or 200 g·L−1 sucrose solution identified, respectively, 75 and 82 % of the seeds as viable (sunken) seeds. For the MSG trail, 77 % viable seeds were recovered in the sunken fraction when seeds were soaked for 48 h then immediately sorted in 600 g·L−1 sucrose solution. In both cases, the loss of viable seeds in the discarded floating fraction was only 4 %. The results demonstrate that both IDS and MSG separation techniques substantially improved seed lot viability, but MSG separation is simple and needs no modern seed handling facility, and its efficacy relies on seed mass (due to the initial soaking) and the specific density and viscosity of the flotation medium.

Standardization of Solid Recovered Fuels through Gravity Separation and Chemical Based Imaging Techniques

The European politics is addressed, in their last years, more and more towards the abolition of landfills and oriented to verify the possibility to improve their recovery through actions of recycling, composting and energy production. Currently the European Directive 2008/98/EC, through the principle of End of Waste (EoW), is driving the utilization of new methods of waste processing in order to transform them it into a new “renewable” product. The post-consumer plastics resulting from packaging account for about 60% of total plastics waste (i.e. 23 million tons) produced in Europe. The high quality Solid Recovered Fuel (SRF) is a partial solution to the problem of waste and landfill management, becoming integral and essential in the closure of the waste cycle, representing one of virtuous processes for the treatment and recovery of waste. The application of recycling strategies, finalised to polymers recovery, can thus represent an important opportunity to reduce: i) not renewable raw materials utilization (i.e. oil), ii) carbon dioxide emissions and iii) the amount of plastic waste disposed-off. Aim of this work is to study the possibility offered by the integrated utilization of Chemical Imaging (CI) based techniques in order to obtain a good quality SRF characterized by a low content of PVC derived packaging to be used for the production of thermal energy. Packaging “final waste”, in fact, is usually characterized by the presence of PolyVinyl Chloride (PVC). Therefore the association of a specific gravity separation architecture with the CI based sensing units, could strongly improve the quality of “final waste” fraction as resulting from classical recycling processes based on milling, classification and density separation. The presence of PVC, in fact, has a negative influence on the combustion and heat recovery of these products due to the production of dioxins and furans. The utilization of the proposed combined approach (i.e. gravity and CI based) could contribute to obtain a SRF characterized by a very low PVC content, thus allowing to certify SRF according to UNI EN 15359:2011 and to correctly utilise it for thermal energy production.

Recent literature review of soil processing methods for recovery of Bacillus anthracis spores

Identifying virulent Bacillus anthracis within soil is a difficult task due to the number and diversity of other organisms and impeding chemical constituents within soil. Regardless of the detection assay, the initial sample must be processed efficiently to ensure that debris, chemical components, and biological impurities do not obstruct downstream analysis. Soil sample processing protocols can be divided into two general types: indirect and direct. There are two requirements for successful indirect isolation of B. anthracis from soil samples: dissociate the spores from the soil particles and physically separate the free spores from the soil particles. Adding an aqueous carrier medium to a soil sample creates a sample slurry for easier manipulation. Centrifugation, high specific gravity separation, immunomagnetic separation, filtration, and settling have been used to physically separate spores from soil. Direct processing utilizes a soil sample without first separating the spores from the bulk sample and falls under two principal types: culturing on B. anthracis selective agar and bulk DNA extraction. Direct and indirect processing steps each have associated advantages and disadvantages. The objective of this review was to consolidate information acquired from previous research, focusing primarily on data gleaned in the last decade, on the processing of soils contaminated with B. anthracis. As shown in this review, an optimized soil-processing protocol with a known recovery rate and associated confidence intervals is needed. A reliable processing protocol would allow for multiple investigators and laboratories to produce high-quality, uniform results in the event of a B. anthracis release.

Development and Demonstration of an Automation and Control System for Coal Spirals

Coal spirals are widely used in coal preparation plants in Illinois and around the world to clean fine coal, typically in the 1 × 0.15 mm size range. Despite their popularity and the trend toward increased automation in modern coal preparation plants, adjustments to the critical process variable for coal spirals, that is, product splitter position, continue to be done manually. Since spiral feed in a plant tends to fluctuate on a regular basis, suitable manual adjustment of splitter position in tens or hundreds of spirals operating in a plant is nearly impossible. As a result, the clean coal yield from a spiral and also the overall plant suffers on a regular basis. This article describes the development of a suitable sensor and control system to adjust the product splitter position of a full-scale spiral. A thorough investigation was made to make use of a basic property of coal slurry that can be measured on-line to correlate it to the constituent solid density and thus to monitor the change in the density gradient across the spiral trough at the discharge end resulting from the usual fluctuation in feed characteristics. An electrical conductivity-based sensing technique was preferred over a capacitive sensor to measure the density gradient using two sensor tubes placed at the critical separation zone of the spiral trough. A PIC24 microcontroller was programmed to send a signal to a DC gear motor based on the new density gradient measured in real time to turn clockwise, counterclockwise or to stay at the same position based on the difference between the conductivity measurement of the present cycle and that of the previous cycle. The automation system was validated by examining the performance of a full-scale spiral while deliberately changing factors like feed solid content, feed washability characteristics, and feed slurry ionic concentration. With a full-scale compound spiral programmed to achieve a specific gravity separation at 1.65, actual D 50 values achieved for two separate tests were 1.64 and 1.73, respectively.

폐금속광산 지역의 비소오염토양 처리를 위한 선별 기술 적용

After the law has been enacted for the prevention and recovery of mining damage in 2005, efforts of remediation have been started to recover heavy metal contaminated soils in agricultural land near mining sites. As part of an effort, the upper part of cultivation layer has been treated through covering up with clean soil, but the heavy metal contamination could be still spreaded to the surrounding areas because heavy metals may be remained in the lower part of cultivation layers. In this study, the most frequently occurring arsenic (As) contamination was selected to study in agricultural land nearby an abandoned metal mining site. We applied separation technologies considering the differences in the physical characteristics of soil particles (particle size, density, magnetic properties, hydrophobicity, etc.). Based on physical and chemical properties of arsenic (As) containing particles in agricultural lands nearby mining sites, we applied sieve separation, specific gravity separation, magnetic separation, and flotation separation to remove arsenic (As)-containing particles in the contaminated soil. Results of this study show that the removal efficiency of arsenic (As) were higher in the order of the magnetic separation, flotation separation, specific gravity separation and sieve separation.

Economic Feasibility of a Mechanical Separation Process for Recycling Alkaline Batteries

Spent primary alkaline batteries present an unused source of secondary metals in Europe and the US, with at least 300,000 metric tons of batteries being landfilled each year. While battery recycling programs exist, current hydrometallurgical and pyrometallurgical processes are not profitable when used for dedicated alkaline battery recycling, so industry growth is difficult. A novel mechanical separation process consisting of shredding, baking, magnetic separation, and specific gravity separation was developed to recycle one metric ton per hour of alkaline batteries at lower cost than current methods, while being environmentally beneficial. Financial analysis was conducted using a Process-Based Cost Model to address the challenges of modeling a recycling process. At full capacity, the cost to recycle alkaline batteries via the developed process is $529 per metric ton, +/- 25%, not including transportation, with revenue of $383 per metric ton. This cost is lower than that of other reported processes, but is still not economically feasible. With supplemental revenue of $0.3 per kg, which could come from various sources, the return on investment can occur in just under 3 years. The low value of alkaline battery recovery material is identified as the most significant economic barrier for the recycling.

Seed Quality Improvement in Okra through Specific Gravity Separation

A study was conducted to assess the efficiency of specific gravity separator in removing partially filled/chaffy seeds of okra during 2007 and 2008. Bulk seed, after extraction, was first subjected to an air screen cleaner with three screens. Then, the good seed fraction obtained was subjected to specific gravity separation. Three fractions were obtained, viz., heavy, medium and light and they were assessed for quality, along with ungraded seed. Test weight, germination percentage, first count, seedling vigour indices I&amp;II and field emergence were significantly higher in the heavy seed fraction than in ungraded seed. Black seed content in heavy seed fraction was significantly low, thereby improving seed quality. Rejection percentage in terms of light and medium seed fractions put together was 3.5% and 12% in 2007 and 2008, respectively. By removal of these fractions, percentage of field emergence improved from 63% to 82% in 2007, and 62.8 to 76.4% in 2008, respectively.

固体ＮＭＲによる石炭中ホウ素の化学形態に関する研究

The aim of this paper is to investigate boron species in coals in order to research partitioning of boron in pulverized coal-fired process. Some extracted coal samples using specific gravity separation and these LTA (Low Temperature Ash) samples were treated with leaching of pure water. Solid-state MAS 11B-NMR spectra of these coals and LTA samples were obtained. Chemical shift of boron species in coal was observed both trigonal and tetrahedral coordinated boron and existent ratio was different with kinds of coal. It was estimated that a part of boron in coal was existed as water-soluble compounds and its chemical form was boric acid and its anhydride, borate of alkaline and alkaline earth metals, and then these compounds minutely dispersed in organic matter of coal.

Basic Study on Mineral Removal from Coal-The Influence of Mineral Distribution and Size of Pulverized Coal on Characteristics of Mineral Removal

The influences of mineral content, mineral distribution, and the size of pulverized coal on the characteristics of mineral removal from coal were investigated in order to develop an efficient mineral removal method. The influence of these factors on the characteristics of mineral removal from coal was evaluated using a specific gravity separation method. The influence of mineral content on the characteristics of mineral removal was found to be considerable at a mineral content lower than 10% by weight, while conversely became weak at a mineral content exceeding 10%. The mineral removal ratio decreased as the particle size of minerals in coal became small. On the other hand, the shape of the minerals was found to have no effect on removal. In addition, the mineral removal ratio increased with the decreasing particle size of pulverized coal. However, it was difficult to separate between mineral matter and organic matter in coal containing fine mineral particles with sizes under 20 µm. These results showed that the characteristics of mineral removal from coal were influenced by the mineral content, the particle size of the minerals, and that of the pulverized coal. Thus, it was found that the choice of a suitable pulverization method for mineral distribution in coal is quite important when developing an effective method of removing mineral matter.

石炭資源の開発・利用に係わる環境技術と安全のアジアネットワーク 石炭中ホウ素の分布と化学形態に関する研究

To clear chemical forms of boron in coals and its origin, specific gravity separation tests for 4 coal samples were performed, and the boron concentration in each sample was measured. The boron concentration in coal has a high positive correlation with the vitrinite content in coal. Other maceral, exinite containing a large amount of resinite, indicates extremely low boron concentration. It is found that the boron concentration in coal decreases with increase of resinite content. In minerals such as quartz, kaolinite, montmollironite, illite, dolomite, and calcite, illite contains the highest concentration of boron. However, the boron concentration of illite does not affect on that of coal, because illite content in coals is very little (bellow about 1%). Since the boron concentration in minerals is low, consequently, it is difficult to remove boron in coal by the deashing operation. The origin and the chemical form of boron are discussed. It is seemed that boron in coal is consisted by water-soluble compounds and water-insoluble compounds. As the water-soluble compound, it is estimated some compounds such as boric acid and borate originated from immersion of seawater or ground water and biogenic fixation by plants. The water-insoluble compounds will probably borosilicate originated from flowing into sedimentary layer with ground water or seawater.

건식비중분리법에 의한 고품질 재생잔골재 제조생산 시스템의 적용성 평가

In this study, the high qualify recycled fine aggregate manufacturing system by the drying specific gravity separation method was evaluated. For the evaluation of the performance of the recycled aggregate, the engineering properties and durability of recycled aggregate has been tested. From the test results, the quality of recycled fing aggregates was improved by high quality recycled fine aggregate manufacturing system and satisfied with the quality standards of KS and JASS 5. Also, compressive and tensile strengths of recycled concrete show no critical difference caused by recycled fine aggregate replacement ratio. However, durability such as carbonation depth chloride ion penetration depth and drying shrinkage shows more deterioration than the concrete without recycled fine aggregate

The effect of specific gravity separation on germination and enzyme activity of Casuarina equisetifolia seeds

An attempt was made to separate the seeds based on the weight of the individual seed by using the specific gravity separator. Seed germinaton recorded by A grade seeds was significantly higher than B, C grades and ungraded bulk seeds. D and E grades did not germinate at all. The superiority of A grade seeds was also observed in enzyme activity viz. amylase, catalase, peroxidase and superoxide dismutase explained the increased seed and seedling vigour in the A grade seeds.

簡易脱灰技術の基礎検討―石炭中灰分の分布状態と浮沈分離法による灰分除去特性の評価―

Increasing the coal demand in the future, the industry has to utilize kinds of unused coals such as highash type of coals. Therefore, the mineral removal technology from raw coal is important to improve trans-portability, and to decrease the cost of ash treatments. In this study, the mineral distribution in the raw coal was investigated to develop an effective removal method of mineral matter. The influence of the mineral distribution on removal ratio of mineral matter from coal was evaluated by specific gravity separation. It was found that the removal of small minerals with line shape or cloudy shape minerals from coal were difficult. And also the effect on elimination of inorganic trace elements with mineral removal was examined. The content of the inorganic trace elements decreased with increasing mineral removal ratio. These results showed that mineral removal from raw coal could eliminate inorganic trace elements at the same time.

Enhancing germinability of Schinus molle L. seed lot from Ethiopia with specific gravity and IDS techniques

The IDS (Incubation, Drying and Separation) method was tested on Schinus molle L. seeds collected from Ethiopia in an attempt to sort non-viable from viable seeds. Seeds were incubated for 24 h followed by one, three, four, five, six, nine and twelve hours of drying and then separated in water. All IDS treatments gave 80.5–93.5% germination in the sunken fraction compared with 61% for untreated seeds. The mean germination time of sunken seeds reduced from 11.2 (control) to 8.9–9.2 days (IDS-treated). Specific gravity separation in water of untreated seeds was also tested, and the germination capacity of sunken fraction was 83.5% with a mean germination time of 9.3 days. IDS method can, therefore, be used to enhance both percentage and rate of germination of a seed lot of Schinus molle, which is desirable to produce uniform and vigorous seedlings in the nursery or out in the field.

Standardisation of seed processing methods for hybrid rice

Standardisation of seed processing methods for hybrid rice was carried out at Department of Seed Science and Technology, TNAU Coimbatore. Considering, the high seed recovery and seed quality, 1.7 mm sieve can be used for size grading of TNRH-16 and TNRH-17 rice hybrids and 1.6 mm sieve for CORH-1 hybrid. Specific gravity separation of size graded seeds into four density grades showed the superiority of heavy, medium and light seeds over very light seeds in terms of seed quality parameters. Among the hybrids, CORH-1 showed its superiority in respect to seed quality over TNRH-16 and TNRH-17.