Ash Reduction Research Articles

CARRIER FLOTATION BY CHAR SLIME - WASHING OF ŞIRNAK ASPHALTITE SLIMES

Şırnak asphaltite slime below 200 micron size is processed. The clean coal products of the column flotation are received with mid-products and shale settlements in the modified column cell in the baffled form. The use of hydrocyclone, agglomerate thickener and wash decantation has been a suitable potential method after the driven and internal loop column flotation. With this method, ultrafine sized oily sludges with high efficiency and low solid rate coal washing are provided. It also enabled highly efficient wastewater treatment as a result of separating the oil with czar foam. Therefore, the method applied in this study can be designed as an optimum wastewater treatment technology for the treatment of oily wastewater in the oil and drilling industry. The aeration process in internal loop column flotation with air jet is widely used in lake water treatment and fresh water treatment. In this study, internal loop carrier column flotation, hydrocyclone overflows and agglomeration process are optimized for coal washing and environmental wastewater treatment. The ash and sulfur contents decreased to a level of 48% ash reduction and a 34% sulphur reduction

Effect of probiotic fermentation on physico-chemical and nutritional parameters of milk-cereal based composite substrate.

A dairy-cereal based composite substrate was prepared from whey-skim milk (60:40v/v), germinated pearl millet flour (4.73% w/v) and liquid barley malt extract (3.27% w/v) and fermented using probiotic strain Lactobacillus acidophilus NCDC-13. Probiotic fermentation increased whiteness index, viscosity and water holding capacity of unfermented substrate. Fermentation caused a reduction in total solids, fat, ash and total dietary fibre content and increment in protein content. Fermentation brought a highly significant reduction in phytic acid (78%) and polyphenol (46%) content. The protein and starch digestibility increased significantly. The HCl- extractability of Ca, Fe, Mg and Zn of unfermented substrate was 32%, 25%, 64% and 17% respectively, which increased to 73%, 50%, 83% and 65% respectively after fermentation. Fermentation resulted in 77% decrease in phytate P as % of total P and significant increase in free P. The current investigation revealed that probiotic fermentation improved nutritional attributes of the composite substrate substantially. The low cost nutritionally enriched probiotic substrate can be utilized for preparation of a wide range of low- cost probiotic foods to address malnutrition and enhance immunity of common population.

The Life Cycle Assessment on Mixed Incineration of High Heating Value Industrial Solid Waste with Municipal Solid Waste

The industrialization process of China has achieved remarkable economic and social development in recent decades, which companies with excessive production of industrial solid waste (ISW). It took up a large amount of land and led to potential environmental problems such as air, water, soil pollution. With the increasing awareness of environmental protection and the better vision to build a pattern of sustainable economy, the comprehensive utilization of ISW is becoming a challenging and promising research field. In this work, a waste incineration power plant in Guangdong Province, China was selected as the research object. Its novel incineration scheme by mix ISW and MSW was evaluated, which aims to improve power generation efficiency. The comprehensive environmental impact assessment of this refuse incineration-power generation technology was also carried out by life cycle assessment. Results show that for waste incineration power generation system, the numerical order of all normalization indicators is Waste Solids>EP>NOx>ADP>AP>CADP>RI>CADP (fossil fuel) >CO2> SO2>GWP>PED>COD>IWU> Water Use > NH3-N. It shows that the ash reduction and denigration system are the most worthy of optimization. And the contribution of flue gas purification to ECER index reaches 38.98%, which is the most influential link and significantly ahead of other links, as well as the most needed optimization link.

A New Strategy for Separating Fe-Si Alloys and Alumina by Controlling Fe/Si Ratios During the Vacuum Thermal Reduction of Coal Fly Ash

A New Strategy for Separating Fe-Si Alloys and Alumina by Controlling Fe/Si Ratios During the Vacuum Thermal Reduction of Coal Fly Ash

Producing Direct Food Packaging Using Deinked Office Paper Grades—Deinkability and Food Contact Suitability Evaluation

Paper recycling is the most eco-efficient waste management option, since the use of recycled fibers reduces the need for virgin wood fiber and lowers energy consumption, and hence has a positive effect on the environment. The use of recycled paper is by far the highest in the packaging industry. In food packaging production, recycled paper is often favored over paper and board made from virgin fibers. However, due to the possible hazardous chemicals that can be found in recycled paper, there is a dilemma of how to overcome food safety issues while making food packaging more circular. The objective of the study was to determine if deinked office paper grades could be used as an alternative fiber source in the production of food packaging white top linerboards. For that purpose, three different types of digitally printed papers were submitted to a chemical deinking flotation in laboratory conditions, and the handsheets formed after each recycling trial were tested on the suitability for direct food contact. Evaluation of deinkability for each group of recycled prints was performed, as well. Deinkability was evaluated by calculating the flotation yield, pulp’s brightness and whiteness increase, ink elimination factor, determination of residual ink area, as well as ash content elimination. Food safety evaluation was performed by determining the content of heavy metals (Cd, Pb, Hg, and Cr VI), primary aromatic amines, diisopropylnaphthalenes (DIPN), phthalates, and polychlorinated biphenyls (PCB) from aqueous or organic solvent extracts of recycled paper pulp. The fastness of the fluorescent whitening agents was determined, as well. Of all evaluated deinking flotation efficiency parameters, only flotation yield and ash reduction by flotation were positively assessed. High content of residual ink particles detected after the flotation stage indicates that the flotation was not a successful method for the elimination of disintegrated ink particles, which was also confirmed by deficient results of ink elimination measurements and whiteness increase. Flotation proved to be the least efficient in the recycling of inkjet prints, where the lowest ink elimination, whiteness, and brightness values were achieved. As far as food safety assessment of deinked pulp is concerned, all tested deinked handsheets were found suitable to be used in direct contact with foods.

Effect of traditional processing methods on protein digestibility and chemical constituents in seeds of Bauhinia petersiana

Background: Antinutritional factors present in food may reduce the bioavailability of nutrients and cause harmful effects to human health. Aims: The aim of this study was to determine the effect of traditional processing methods on protein digestibility, nutrient and antinutrient constituents of seeds of Bauhinia petersiana. Subjects and Methods: The seeds were processed by soaking in water, boiling or roasting before analyzing protein digestibility, nutrient and antinutrient compositions. Results: Soaking resulted in no significant changes in the content of moisture, protein, fiber, phytates and trypsin inhibitor activity and significant reductions in fat, ash and tannins. Roasting resulted in no significant change in the content of moisture, ash, protein, and fiber and significant reductions in fat, phytates and trypsin inhibitor activity. Boiling resulted in a significant increase in the content of both protein and fiber and reduction in fat, ash, tannins, phytates and trypsin inhibitor activity. Mineral content of zinc, magnesium and calcium was not changed by soaking, roasting or boiling of the seeds. The calculated phytate: zinc molar ratios for both the raw and processed seeds were greater than 10, the limit for optimal absorption of zinc in the small intestine whereas phytate: iron molar ratios were less than 14, the limit for optimum absorption of iron in the intestines. In vitro digestibility of proteins in the seeds was increased when the seeds were soaked, roasted or boiled. Conclusions: Boiling the seeds of B. petersiana before consumption would effectively remove undesirable antinutrients while maintaining the nutrient content of the seeds and improving digestibility of proteins. Keywords: Legume, nutrient, antinutrient, digestibility, phytate.

Effect of 0–1 mm pulverized coal on desulfurization and upgrading of low grade lignite in dry cascade separation bed with compound force field

Coal is the important pillar of national economic development. China has a rich variety of coal resources, of which low-grade lignite resources have huge reserves. As the consumption of high-quality coal resources intensifies and its output is declining, strengthening the efficient use of low-grade lignite is an important measure to ensure energy supply and safety, and to stabilize industrial energy production. This paper mainly studies the influence of the characteristics of 0–1 mm coal powder in the dry cascade separation bed with compound force field on the spatial migration law of low-grade lignite and the uniformity and stability of the density of the autogenous medium bed. The regional spatial distribution of sulfur content of low-grade lignite under different autogenous medium content was systematically studied. The emphasis is on the influence of the particle size and density composition of 0–1 mm coal powder on the uniform stability of the autogenous medium bed density. At the same time, the spatial distribution and cascade separation of low grade lignite in the variable distance regional autogenous medium bed are analyzed. The test results show that when the content is 12.5–20%, the sulfur content of the upper and lower materials is relatively stable in the high and low density material enrichment areas, and the sulfur content of the middle material has a large fluctuation range. At this time, a autogenous medium fluidized bed with uniform and stable density can be formed; The 0.125–0.25 mm coal powder particles are uniformly distributed along the XOY section and XOZ section, which is the dominant particle size fraction for forming an autogenous fluidized bed; Coal particles with a density of 1.6–1.8 g/cm3 can form a fluidized bed with stable density, which is the dominant density fraction for forming an autogenous medium bed. During the dynamic sorting process, the materials in zone I present a differentiated distribution, realizing the separation of low-density materials. The spatial distribution of materials in zone II fluctuates greatly, realizing the separation of medium and high-density materials. The materials are distributed relatively evenly in zone III, which realizes the conveying and separation of high-density materials. The yield of clean coal is 65.12%, the ash content is 9.89%, the sulfur content is 0.99%, the gangue yield is 34.88%, the ash content is 44.98%, and the sulfur content is14.89%. The probable error of E is 0.07 g/cm3, and the high-precision desulfurization, ash reduction and quality improvement of low-grade lignite by the dry cascade separation bed is realized.

Dry Beneficiation of Coking Coal Fines using an Advanced Air Cyclone

An attempt is made on coking coal fines dry beneficiation of below 2 mm size, with VSK separator consisting of advanced air cyclone. The results of these investigations reveal that simple size with 250 micron can give a product with 18% ash at 17.4% yield, whereas by using VSK separator the product obtained contains 17.8% ash with 48.1% yield from a feed sample containing 23.3% ash. Since the preliminary investigations has shown encouraging results on reduction of ash, large scale continuous tests can provide better yield for various samples.

Effects of restricted feeding levels and stocking densities on water quality, growth performance, body composition and mucosal innate immunity of Nile tilapia (Oreochromis niloticus) fry in a biofloc system

In aquaculture feed accounts for more than 50% of current costs. Biofloc has the potential to compensate for food reduction, so restricted feeding levels should be investigated to decrease food consumption. The present study conducted to evaluate the effect of restricted feeding levels and stocking densities on water quality, growth performance, body composition and mucosal innate immunity of Nile tilapia (Oreochromis niloticus) fry in biofloc system (BFT). A 5*2 factorial experimental design was used with five restricted feeding levels (0, 15, 30, 45 and 100) and 2 stocking densities(500 fish/m3 and 1000fish/m3) comprising 10 treatments for BFT and for each density there were clear water (CW) system as control with three replicates. Fry with initial weight of 3.2 ± 0.05 g were stocked in tank(40 L), fed three times a day at 8:00, 12:00 and 16:00. Molasses was added to BFT treatments as organic carbon source at a C/N ratio of 15. Results showed that, growth indices (WG, DGR, SGR, FCR), water quality parameters (TAN, NO2, NO3, settled solids and total suspended solids), as well as innate immunity (Total immunoglobulin, Lysozyme and Catalase activity) were improved in biofloc system compared to the CW system. The reduction of feeding rate resulted in significantly decreasing growth performances and immunity among biofloc groups (p < 0.05) except for the group with 15% feed reduction in stocking density of 500/m3. Stocking density had significantly (p < 0.05) reverse effect on growth indices except for the biofloc treatment 1000/m3 without feed reduction. Proximate analysis revealed that by reduction of feeding rate, protein, ash and moisture contents increased, whereas lipid contents decreased significantly (p < 0.05). Survival rate was high (94.8–100%), and no significant differences were seen among treatments (p > 0.05) except for the non-feeding biofloc treatment with stocking density of 1000/m3 (67/9%). Innate immunity was significantly decreased by reduction of feeding rates while, Liver enzyme activity showed an increasing trend by reduction in feeding rate and increasing the stocking density (p > 0.05). These results indicate that the BFT improved water quality, growth performance and immune function of Nile tilapia fry compared to CW system. Also it is possible to decrease 15% daily feeding rate in BFT system. In conclusion, the study suggests the stocking density of 1000/m3 for larviculture of tilapia in BFT to use water and equipment more efficiently.

Phase Transformation of Alumina, Silica and Iron Oxide during Carbothermic Reduction of Fly Ash for Ceramics Production

Fly ash is a by-product from burning of coal. Utilization of fly ash by carbothermic reduction is an effective way to recover aluminum, silicon, and iron to enhance product-added value. This work is focused on the phase transformation of Al2O3, SiO2 and Fe2O3 during carbothermic reduction of fly ash in air. A comparative analysis of carbothermic reduction of fly ash in air and in nitrogen was made. Thermodynamics analysis was performed to illustrate the possible reactions for residue and condensate. X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectrometry (EDS) were employed to characterize the phase composition, surface morphology, and microstructure of the reduced products. Results show that Fe3Si and Fe2Si appear sequentially with increasing of temperature. Al5O6N is an intermediate compound. Residue of Al9FeSi3, Al, and Si, and condensate of SiC, AlN and C are obtained. β-SiAlON was not found in the residue. Nitrogen is involved in the reduction of Al2O3 but not in the reduction of SiO2 and Fe2O3. Carbothermic reduction of fly ash in air did not behave the same as fly ash in nitrogen.

Recovery of Coal Values from Middling and Rejects by Froth Flotation and Mozley Mineral Separation

The recovery of coals values from Middling and Rejects carries out by using Froth flotation and Mozley Mineral Separation. The middling and rejects are the waste products from gravity beneficiation process, it has been noted that most of washery plants are selling this product at low cost because they have less values.The independent variables selected for Mozley Mineral Separator and their ranges were indicated in the parentheses as follow, water flow rates (400, 600, 800ml/s), amplitude (1.25, 1.5, 1.75inch) and collection time (30, 40, 60 s) while the independent variables for froth flotation were; Pulp density (10, 12.5, 15 %), collector dosage (39.3, 44.4, 49.5 g/t) and frother dosage (61.8, 65.3, 68.8 g/t). The number of experimental runs and regression equation determined by using Design Expert softwareThe d80 for middling and rejects samples were 10.5mm and 12.89mm respectively. The ash contents for the middling sample treated by froth flotation decrease from 37% to 15.85% at the reagent concentration of 49.5g/t collector, 65.3g/t frother and pulp density of 10%. The froth flotation results of middling sample shown to have a great reduction of ash contents. The overall optimum middling recovery and yield for washery grade I and II attain at reagent concentration and pulp density of 47.703g/t, 68.568g/t and 13.2% for collector, frother and pulp density respectively. The feed of reject coal was 71% and the ash contents reduced to 28.87% with the recovery of 0.85%. The analysis through Mozley mineral separator did not show significant changes in the reduction of ash from both middling and rejects. The ash contents achieved were above the scope of the studies for recovering of coal values. The experiments for middling and reject by froth flotation and Mozley mineral separator may be carried out by varying other parameters as well as the type of methods.

Valorization of treated sewage sludge for Arundo donax production in a field experiment

Non-food crops provide an alternative renewable energy source. The high yield of Arundo donax makes this crop a suitable candidate for this purpose. Sewage sludge can be repurposed as an organic amendment to recover soil fertility and improve crop yield. This study sought to evaluate the effect of treated sewage sludge (SS) amendment on the production and heating value of A. donax as a source of biomass for energy production. The study was developed in experimental plots in Central Spain. As organic amendment, sewage sludge composted with pruning waste (CP) and treated by thermal drying (TD) were applied at a dose of 50 t ha−1, in comparison to a mineral fertilizer treatment (F) and a control soil without treatment (C). After two growing seasons, plant biomass, production parameters and heating value were examined, as well as the effect of the amendments on soil properties. Most parameters increased in plants grown in sewage sludge-treated plots, including heating value reaching 19.19 MJ kg−1. Moreover, the leaves of these plants had a higher chlorophyll (from 0.39 to 0.52 mg cm−2) and nitrogen content (2%) and a lower ash content (0.9 % reduction). This reduction in ash and the increase of heating value favor the use of this biomass for thermochemical applications. Moreover, the increase in soil organic carbon (around 40 %) due to the organic treatments contributes to increase the carbon stock in soil. The findings support that the application of treated sewage sludge emerges as a suitable strategy not only for enhancing the production of A. donax for energy uses but also for maintaining soil fertility in Mediterranean conditions.

Towards the chemical upgrading of the recovered carbon black derived from pyrolysis of end-of-life tires

This work deals with the recovered carbon black derived from the industrial-scale pyrolysis of end-of-life tires, targeting at increasing the technical knowledge to be considered as alternative to the virgin carbon black. Accordingly, a demineralization process using HCl, HNO3 and NaOH to improve the properties of the recovered carbon black is investigated. A fractional factorial design 2k-2 showed that the acid concentration has the highest statistical influence on the ash reduction. At 5 M, the ash content was 6.12 wt% and 5.21 wt% for HCl and HNO3, respectively. The demineralized recovered carbon black obtained from both acids together with a reference carbon black (N550) were characterized by elemental and proximate analyses, surface area, ash composition by XRF, and morphology by SEM and TEM. A comprehensive surface chemistry analysis by FTIR and TPD-NH3 was also conducted. In addition to decreasing the ash content and to increasing the surface area, the recovered carbon black treated with HNO3 led to the highest presence of acidic functional groups. In this regard, this upgraded recovered carbon black is expected to offer both better filler/polymer interaction and in-rubber performance, as compared to the non-treated recovered carbon black. The experience gained from this work provides important impetus to deem the recovered carbon black as alternative to virgin carbon black, and paves the way to close the end-of-life tire-recycling loop by both pyrolysis and chemical upgrading strategies.

АНАЛИЗ ГРАНУЛОМЕТРИЧЕСКОГО СОСТАВА ЗОЛОШЛАКОВЫХ ОТХОДОВ ТЭЦ КЕМЕРОВСКОЙ ОБЛАСТИ

Aim: to research ash and slag waste from thermal power plants on the possibility of using them as a concretes’ aggregate. Tasks: tо explore ash and slag waste’s granulometric composition; to determine if the granulometric composition meets the state standard’s requirements; to explore the kind of the aggregate, fine or coarse. Possibility of practical using: this researching is directed to increasing of ash and slag waste reuse, decline quantity and volume of ash and slag waste and reduction their poison impact on the environment.

Biomass Waste Valorization by Acidic and Basic Leaching Process for Thermochemical Applications

Inorganic minerals present in biomass feedstock can cause various technical problems during thermochemical conversions such as fouling, ash slagging and agglomeration, alkali deposition, and surface corrosion. To counter such problems, it is recommended to demineralize the biomass by treating it with a suitable extractive reagent. In this study, cotton stalk (CS) and coconut husk (CH) has been treated with HCl, HNO3, and NaOH reagents using different concentration levels. The effect of treatment on thermal, physical, and chemical properties of the biomass has been examined using ash analysis, ultimate analysis, scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), calorimetry, and thermogravimetric analysis (TGA). From this study, HCl appeared to be the most efficient leaching reagent as it removed the maximum 96.5% and 91.2% ash forming components from CS and CH samples, respectively and increased the heating value by 6.03% and 7.19%, respectively. On the contrary, NaOH treatment has devalued the biomass due to a decrease in the heating value by 10.42% and 11.87% for CS and CH samples, respectively despite the ash reduction by 51.4% and 59.1%. The adverse effects of NaOH treatment have been attributed to the delignification of the biomass samples.

Economic evaluation of a hypothetical integrated energy recovery system for trommel fines

Trommel fines are a high-ash aggregate waste derived from material recycling facilities (MRFs) and are usually disposed in landfill. Increasing UK landfill tax and environmental concerns, however, calls for a flexible technology that can effectively process and extract valuable energy from trommel fines at high efficiencies. One possible technology is fast pyrolysis coupled to a combined heat and power (pyro-CHP) plant. To determine the feasibility of such technology, an understanding of its economic characteristics is required, in addition to the technical details. This study presents an economic evaluation of a pyro-CHP plant processing three pre-treated trommel fines feedstocks for energy recovery over a 20-year period. The three feedstocks were designated as DPT (from initial separation/size reduction), AW (from ash reduction by washing DPT with water) and AWS (from ash reduction by washing DPT with aqueous surfactant solution). Under all processing capacities (200 kg/h to 2000 kg/h) total revenues from the pyro-CHP system were higher than landfill costs, but only became profitable at 2000 kg/h processing capacity for the DPT feedstock. Further analysis showed positive net present values (NPV) only for AW and AWS, e.g. at 2000 kg/h capacities, with payback periods of about 14 years compared to 35 years for DPT at a fixed CHP efficiency of 60% and 20% internal rate of return (IRR). Sensitivity analysis carried out using different values of IRR and CHP efficiencies, confirmed the superior economic performance of the washed feedstocks over DPT, with payback periods reducing to about 6 years in some cases.

Sustainability of coal mines: Separation of clean coal from the fine-coal rejects by ultra-fine grinding and density-gradient-centrifugation

Due to the availability of high ash feedstocks and drift origin, Indian coal washeries face tremendous pressure in maintaining the clean coal yield and handling huge quantities of rejects. Since flotation rejects (tailings) discharged in the form of fine-sized (−500 μ) coal-water-slurry, handling and disposal is an environmental concern and it impacts mine sustainability. As conventional methods for extracting clean coal from tailings reported poor yields, a two-stage process i.e. wet-grinding followed by density-gradient-centrifugal separation was explored and optimized for recovering >80% of the carbon values. Clean coal of 19.2%–21.4% ash with >40% yield was obtained by density-gradient-centrifugation of different ultrafine size (−75 μ) coal-water-slurries at 50% pulp density. However, further reduction in clean coal ash by maintaining the yield was limited due to the hindrance in the movement of the high-ash coal particle caused by particle-particle interactions in a thick slurry. Hence, the pulp density of coal-water-slurry was optimized with the addition of extra water, which resulted in 15.1%–17.3% ash clean coal at an average yield of 54–58% from coal tailings having 34.9%–39.3% ash content. Optimization and kinetics of grinding and density-gradient-centrifugation were studied to check the effect of pulp density and other operating conditions. Ash reduction was mainly due to the removal of silica-based materials, where alumina to silica ratio was increased from 0.394 to 0.475. The petrographic analysis showed that the product coal was rich in macerals with ~60% of vitrinites and ~ 30% of inertinites.

Improvement of Low‐Rank Coal Flotation Based on the Enhancement of Wettability Difference between Organic Matter and Gangue

AbstractThe main reason for low separation efficiency in low rank coal (LRC) flotation was the small wettability difference between organic matter and gangue. To improve LRC flotation response, a new method based on the expansion of wettability difference was proposed in this investigation. This method is that changing the adsorption liquid environment (adding Ca2+) to enhance the selective adsorption of surfactants on the surface of organic matter and increase its hydrophobicity, meanwhile applying ultrasonic desorption to remove the surfactants adsorbed on the gangue. The experiments were conducted on organic matter, gangue, and raw coal and combined with surfactant adsorption/desorption capacity, FTIR, and wetting heat determination to explore the underlying mechanism. The best flotation performance of raw coal was obtained when desorption time was 30 s. Surfactant adsorption results indicated that Ca2+ could promote the adsorption of surfactant on organic matter, but has insignificant effect on gangue. Under ultrasonic condition, surfactant capacity adsorbed on gangue decreased in the presence of Ca2+, but the addition of Ca2+ could inhibit surfactant desorption. However, in the raw coal, the surfactants could be removed from gangue surface under ultrasonic and Ca2+ because of the low proportion of gangue in raw coal and weaker adsorption strength of Ca2+ on gangue, as indicated by the ash reduction. Wetting heat results suggested that wettability difference between organic matter and gangue was expanded after ultrasonic treatment. This study may have some guiding significance for improving LRC flotation.

Deashing and desulfurization of subbituminous coal from the East field (Bogovina Basin, Serbia) - insights from chemical leaching

The study is focused on the determination of the most effective chemical leaching process for the simultaneous demineralization/deashing and desulfurization of subbituminous coal from the Bogovina Basin. Coal was treated for 30 min, at different temperatures, using variable concentrations of hydrochloric, nitric, acetic and citric acids; hydrogen peroxide, mixture of hydrogen peroxide and nitric acid (pH 2), as well as by the stepwise leaching process (nitric acid + mixture of hydrogen peroxide and nitric acid, pH 2). The changes in mineral composition, caused by the chemical leaching, are followed using X-ray diffraction, whereas alterations of coal organic matter are tracked by Fourier-transform infrared spectroscopy and the content of fixed carbon. Inorganic acid leaching, regardless of the temperature and acid concentration, enabled the successful deashing of coal, whereas the percent of desulfurization was insufficient. The organic acid leaching was not satisfactory for both, deashing and desulfurization. Leaching by H2O2 and H2O2/HNO3 mixture (pH 2) resulted in moderate desulfurization, but the ash reduction was low. The most suitable method for the simultaneous effective ash (78 wt.%) and the sulfur (66 wt. %) removal from Bogovina coal is the two-step leaching, combining 10 vol. % HNO3 and mixture of 35 vol. % H2O2/10 vol. % HNO3 of pH 2 at 60?C.

Stable Operation of Rotary Stoker Furnace for Industrial Waste

Incineration is one of the most common methods for the treatment of industrial waste. Large amounts of bottom ash are buried without being reused. By reducing components such as toxic metals contained in bottom ash under suitable incineration conditions, landfill waste can be reduced, and re-use of bottom ash can be increased. In this study, effects of the air supplied to the bottom of a commercialy used rotary stoker furnace was investigated as the first step to improve incineration conditions. Bottom ash content must be controlled against various types of industrial waste whose content changes from day to day. The characteristics of industrial waste containing typical components were numerically investigated using a combustion simulation program. It was found that if the primary air used for combustion is not preheated, auxiliary fuel is required to burn waste. Preheated primary air increases the drying rate of the input material, and allows burning of waste without auxiliary fuel. At the furnace, components and calorific values of input raw material are controlled by mixing different types of waste together. Preheated primary air enables reduction of bottom ash, reduction of auxiliary fuel consumption, and stabilization of furnace operation.