Proportion Of Pellets Research Articles

Influence of iron ore concentrate quality on metallurgical properties of pellet

One of the important factors for improving the technical and economic performance of blast furnaces is the iron content in the iron ore part of the charge. At the same time, there is evidence that when using iron ore concentrate with an iron content of more than 66‒67% for the production of pellets, their strength decreases, and adjustments to the heating modes are required. In recent years, Russian mining enterprises have been implementing technological measures to increase the mass fraction of iron in the concentrate to 68‒70%. The results of a study of the influence of concentrate quality indicators (mass fraction of iron, specific surface value) on the pelletizing technology and metallur-gical properties of pellets are presented. Concentrates with a mass fraction of iron of 66.6, 68.0, 69.2% and a specific surface of 1576, 1999, 2015 cm2/g, respectively, were used as an object of study. It was found that increasing the iron content and specific surface area in the concentrate leads to an improvement in the raw pelletizing technology ‒ plasticity and the proportion of pellets with a size of 5‒16 mm increase. Roasting of laboratory pellets in baskets on a roasting machine showed a multidirectional change in the metallurgical properties of the pellets. The compressive strength index decreased, the hot strength changed little, the softening-melting temperature range (SMTR) decreased from 308 to 200‒290 °C. Mineralogical studies have established that the decrease in these indicators (strength and SMTR) was influenced by a decrease in the amount of silicate binder and the uneven distribution.

Повышение эффективности энергетического использования биотоплива

The share of thermal power plants that consume renewable energy resources is growing worldwide. Wood and bio-coal pellets become more and more common as fuels. The technological cycle of pulp and paper production produces a large amount of wood waste, which must be used efficiently. However, bark-wood waste is hard-burning fuel, which causes the need to “light” the flare with high-calorie non-renewable fuel, is followed by the formation of carbon dioxide emitted into the atmosphere. Boilers KM-75-40, taken out of production in 1985, are still used at Russian enterprises for the use of bark-wood fuel as an energy source. Energy examination of the boiler KM-75-40 during its operation with bark-wood fuel (coniferous and deciduous wood bark, substandard chips and sawdust) showed that the design and technical condition of the boiler does not provide the required combustion rate of fuel components and environmental parameters that meet the requirements of the state standard, GOST. The present work aims at analyzing the possibilities of comprehensive improvement of efficiency of bark-wood fuel combustion in boilers KM-75-40. Highriority measures to improve the efficiency of these boilers were developed based on the research results. Boilers KM-75-40 have been in operation for more than 50 years and require replacement with modern low-emission heat generating systems. Prior to replacement, however, upgrading the boilers is recommended: their transition to the layer-vortex combustion technology and the use of biocoal pellets, as an additive to the bark-wood fuel, in order to adjust the thermal characteristics of the combusted biofuel and steam capacity of the boilers. Bio-coal pellets produced from hydrolysis lignin, which has undergone soft pyrolysis, are promising for this purpose. Thermal and aerodynamic calculations of the boiler KM-75-40 with different proportion of pellets by heat release, as well as thermogravimetric studies were carried out to assess the effectiveness of co-combustion of bark-wood fuel and bio-coal pellets. The thermal calculation included: the circulation rate of fuel particles in the vortex zone, the granulometric composition of the combusted fuel mixture, the location features of combustion equipment, reducing the contamination of the heating surface. The transition to the combustion of this fuel mixture using the layer-vortex technology will allow to refuse from using non-renewable fuels in the boiler KM-75-40 when combusting high-moisture bark-wood fuel, will significantly increase the boiler efficiency and reduce the negative impact on the environment.

Influence of Type and Consumption of Pellets on Indicators of Blast-Furnace Smelting in the JSC Ural Steel

The article presents the results of the analysis of production data on the operation of the blast furnace No. 1 of Ural Steel JSC for the period from 2013 to 2018. During this period, the Mikhailovsky GOK pellets with different basicities were used. It has been established, that the effectiveness of the use of pellets of different basicities is determined by their behavior in a blast furnace and depends on the proportion of pellets in the iron ore part of the charge. The gas-dynamic conditions of melting deteriorate with an increase in the proportion of pellets in the charge, which is accompanied by an increase in the specific pressure drop and forces the blast rate, to be adjusted. It is necessary to work on 40-45% of fluxed pellets and 20-25% acid pellets in a charge at a blast rate of 2000-2100 m3/min, to minimize coke rate and increase rate of work of blast furnace No. 1 of Ural Steel JSC. An increase in pellet consumption is possible while maintaining the efficiency of blast-furnace smelting only if their high-temperature properties are improved, as a result of optimization of basicity and increase in MgO content, which affects the structure and properties of the silicate binder.

Influence of the consumption of pellets with different basicity on indicators of blast-furnace smelting

The results of the analysis of production data on the operation of blast furnace No. 1 (useful volume 1007 m3) of Ural Steel JSC for the period from 2013 to 2018 are presented. During this period, pellets from the Mikhailovsky GOK were used with varying degrees of fluxing: pellets of natural basicity in the ratio of CaO/SiO2 equal to 0.08 ± 0.02 units. (2013-2015) and partially fluxed pellets with a basicity of 0.52 ± 0.05 units. (from 2016 to the present). It has been established that the effectiveness of the use of pellets of various basicities is determined by their behavior in the blast furnace and depends on the proportion of pellets in the iron ore part of the charge. The gas-dynamic conditions of the smelting worsen with an increase in the proportion of pellets in the charge, which is accompanied by an increase in the specific pressure drop and forces the flow rate to be adjusted. There is an optimal level of specific pressure drop (53–55 Pa per 1 m3 of blast per minute) for the operating conditions of blast furnace No. 1 of Ural Steel, which ensures the optimum combination of the melting characteristics. Deviation from the optimal level of pressure drop leads to an increase in coke rate and a decrease in the degree of CO use, which is associated with gas distribution disturbance. Due to the increase in high-temperature properties, the replacement of non-fluxed pellets with off-fluxed pellets improves the gas-dynamic conditions in the lower part of the mine (in the cohesive zone). This leads to a decrease in the total pressure drop and specific pressure drop at a constant flow rate of the blast, and is a reserve for melting intensification. To minimize coke rate and maintain the high-performance operation of blast furnaces of Ural Steel JSC, it is necessary to work on 40–45 % of fluxed or 20–25 % acid pellets in a charge. An increase in pellet consumption while maintaining the efficiency of blast-furnace smelting is possible only if their high-temperature properties are improved. The improvement of these properties is possible as a result of optimizing the basicity and increasing the MgO content, which affects the structure and properties of the silicate bond. This work is carried out within a framework of the government order (No. FZRU-2020-0011) of the Ministry of Science and Higher Education of the Russian Federation.

Fine-scale changes in spatial habitat use by a low-density koala population in an isolated periurban forest remnant

Koala (Phascolarctos cinereus) populations in south-east Queensland are in decline. Although various studies have looked at broad-scale tree preference and habitat quality, there has been little attempt to quantify fine-scale activity shifts from one year to the next or examination of activity at the mesoscale. This study quantified koala activity levels in a 909-ha forest patch at Karawatha Forest Park, in south Brisbane. The Spot Assessment Technique was used to quantify activity and tree selection on 33 long-term monitoring plots in 2009 and 2010. In total, 843 trees were searched and koala pellets were found underneath 34 and 47 trees in 2009 and 2010, respectively. A higher proportion of pellets was found underneath Eucalyptus tindaliae and E. fibrosa and there was weak selection for larger trees. A low occurrence of revisits and a minor shift in activity distribution from 2009 to 2010 indicate that the koala population exists at a low density. Rapid declines in koala populations are occurring in primary habitats. Hence, stable low-density koala populations are important for maintaining genetic diversity and connectivity in fragmented urban landscapes.

Effect of Converter Slag Consumption on Blast Furnace Operating Indices

Results are provided for calculation of the predicted blast furnace operating regime using converter slag in the iron-ore part of the charge without implementing additional measures with the aim of evaluating its effect on process indices. Introduction into a blast furnace charge of fractionated converter slag may be performed in order to increase slag magnesia content and to use it as a basic for flux for increasing the proportion of pellets in a charge of an individual furnace without changing the prescribed sinter basicity for the whole workshop. An increase is provided in gas permeability of the dry part of a charge for a furnace with a limited upper zone in the case of distortion of its profile. Charging converter slag into a blast furnace gives rise to an increase in iron phosphorus content. Prolonged use of converter slag in all blast furnaces gives rise to accumulation of phosphorus in metal, and consequently to resolution of the problem of removing phosphorous during converter treatment. The choice of the ratio of charge components may be made by maintaining the iron content in a fluxed charge at a level relating to specifications of the technology and the task of providing an economic furnace regime. Solution of the question of the expediency of using converter slag in blast furnaces is possible with comprehensive analysis of the problem: evaluation of the economic expediency of its use as a fluxing additive; economic development of this question for a blast furnace – converter production complex; choice of a furnace operating regime in accordance with its operating conditions; analysis of the ecological problems of the operation of an enterprise and a region.

MMK Blast Furnace Operation with a High Proportion of Pellets in a Charge. Part 2*

Results are given for calculation of blast furnace operation with a high proportion of Sokolovo-Sarbaiskii Metallurgical Production Association unfluxed pellets with a different content of local agglomerate. It is shown that with an increase in the proportion of unfluxed pellets (up to 60%) in a loading charge in order to achieve the required blast furnace slag basicity charging limestone into the furnace is necessary. In order to reduce the weight of loaded “raw” limestone, it is necessary to produce agglomerate with high basicity. As the proportion of pellets increases in a loaded charge, there is a reduction in blast furnace slag magnesia content. In order to increase slag magnesium oxide concentration, it is expedient during agglomerate preparation to use a combined basic flux consisting of 70% normal and 30% dolomitized limestone.

Diet of the Great Cormorant (Phalacrocorax carbo sinensis) at two areas in the Bay L vstabukten, South Bothnian Sea, Sweden, based on otolith size-correction factors

The diet of cormorants roosting at Malause on the Garonne River (South- West France) was studied by analyzing pellets collected during the winter 2001- 2002. This roost held a mean of 550 cormorants between October 2001 and March 2002, making it one of the most important winter roosts in France. The diet contained 14 fish species, including 10 cyprinids. Cyprinids were the most abundant prey, representing 90 % of individual fish. Bream Abramis brama between 100 and 150 mm in length were the most abundant food items, while large bream ( >300mm total length) were also consumed. The proportion of pellets containing bream increased from 26 % in October- November to 69% in February- March. There was no significant change in the size of the bream over time. The next most abundant species was pikeperch Sander lucioperca present in 15.4% of the pellets from December- January but only 2.6% in February- March.

Evidence against the use of fecal pellet size for age determination in European wild rabbits

Techniques for estimating the age of wild animals are crucial to many aspects of the study of population biology. Accurate estimates of the proportion of different age classes in wild rabbit populations would be very useful, and the possibility that it could be obtained from the pellet size holds great appeal. However, this suggestion has created controversy in the literature as this technique has not been validated. This study involved assessment of whether threshold fecal pellet diameters could be used to differentiate adult and juvenile rabbits. The proportion of adults in four wild rabbit populations living in semi-natural conditions was compared with the proportion of animal pellets greater than threshold diameters of 6 mm and 4 mm. Our results suggest that inferring a relationship between the proportion of pellets >6 mm diameter and the proportion of adults in a population is not applicable to European wild rabbits, and that the use of this method could produce erroneous interpretations. The use of a 4 mm pellet diameter threshold appeared to produce even more inaccurate results. Studies that use this technique should include validation, as the results can vary greatly among individuals and populations.

Seasonal and annual dietary changes in Lesser Kestrels Falco naumanni wintering in Lesotho

The diet of Lesser Kestrels Falco naumanni wintering in an agriculturally-transformed area in Lesotho was studied by means of pellet analysis. Orthopterans, beetles and solifugids (sun spiders) comprised the staple food of the wintering Lesser Kestrels. Small vertebrates, termite alates, earwigs and scolopendrans supplemented the diet. The proportion of pellets containing scarabaeid and carabid beetles, as well as those containing locusts and crickets, increased as the wintering season progressed, while the proportion of pellets containing solifugids decreased during the same period. Significant differences in diet composition were recorded between the 1998/1999 and 1999/2000 wintering seasons.

Effect of Feed Fines Level on Broilers Fed Two Concentrations of Dietary Lysine from 14 to 30 Days of Age

A study was conducted to determine if increasing dietary lysine would improve body weight gain and feed efficiency (FE) of male broilers from 14 to 30 d when fed diets containing high proportion of feed fines. A 2x5 factorial treatment arrangement was achieved by feeding diets containing two concentrations of total lysine (1.00 and 1.15% of the diet) with five levels of feed fines (20, 30, 40, 50 and 60% of the diet). Feed fines represented a blend of fines created and scalped during manufacturing, and intact pellets ground with a hammermill. Subsequently, proportions of pellets and fines were blended to obtain desired levels of feed fines. Eight grower cages of 5 male broiler chicks were fed each dietary treatment from 14 to 30 d. Body weight gain was depressed for birds fed 1.00% lysine when the diet contained in excess of 20% fines. Birds fed 1.15% lysine diets containing 20% fines did not significantly differ in weight gain from birds fed the same lysine concentration regardless of fines level. At fines levels greater than 20%, feeding 1.15% lysine resulted in a significant improvement (P=0.0324) in FE at each level of fines. Birds fed 1.00% lysine at the lowest level of fines displayed a significantly greater average feed intake (P=0.05) than any other treatment. Lack of a feed intake response at increasing levels of fines suggests that birds received a growth benefit independent of feed intake. Results demonstrated that increasing dietary lysine concentrations may compensate for inferior performance obtained with diets of poor pellet quality.

Diet of great cormorants Phalacrocorax carbo sinensis wintering in Malause (South-West France)

The diet of cormorants roosting at Malause on the Garonne River (South- West France) was studied by analyzing pellets collected during the winter 2001- 2002. This roost held a mean of 550 cormorants between October 2001 and March 2002, making it one of the most important winter roosts in France. The diet contained 14 fish species, including 10 cyprinids. Cyprinids were the most abundant prey, representing 90 % of individual fish. Bream Abramis brama between 100 and 150 mm in length were the most abundant food items, while large bream ( >300mm total length) were also consumed. The proportion of pellets containing bream increased from 26 % in October- November to 69% in February- March. There was no significant change in the size of the bream over time. The next most abundant species was pikeperch Sander lucioperca present in 15.4% of the pellets from December- January but only 2.6% in February- March.

Rainbow bee‐eaters (Merops ornatus) as a monitoring tool for honeybees (Apis mellifera L.; Hymenoptera: Apidae)

Abstract Regurgitated pellets were collected from underneath roosts of rainbow bee‐eaters in suburban Darwin, Australia, and examined for the presence of wings of honeybees. The proportion of pellets containing wings was compared prior to and after placement or removal of honeybee hives in the vicinity of four roosts. On each occasion, the addition or removal of hives was reflected in proportions of pellets containing wings. The results suggest that examination of pellets beneath bee‐eater roosts would be a useful technique for monitoring the occurrence of feral honeybees. Potential uses for this technique in eradication of unwanted bees are discussed.

Investigations of tablets prepared from pellets produced by extrusion and spheronisation Part I: The application of canonical analysis to correlate the properties of the tablets to the factors studied in combination with principal component analysis to select the most relevant factors

Three different types of pellets prepared by extrusion and spheronisation were mixed and tabletted by a mechanical press and by a tabletting machine. The objective was to prepare tablets of drug containing pellets which would disintegrate into the pellets from which they were made on adding to fluid. Several factors involved in the production of the tablets were analysed by canonical analysis, which identified relationships between the drug loading in the pellets, the proportion of pellets without the drug, the compression pressure used to prepare the tablets, the size of the pellets, the diameter of the die, the concavity of the punch and the density, the porosity, the crushing force to break the tablets, the tensile strength, the friability, the disintegration time of the tablets and the mean dissolution time of the drug. On one hand, the results have shown that the glyceryl monostearate within the pellets interacted with the barium sulphate pellets regarding the disintegration times of the tablets. The glyceryl monostearate was important as a lubricant, whereas the barium sulphate was important for the disintegration of the tablets. The pressure applied and the size of the pellets were not major factors to be considered. However, the shape of the tip of the punch and the diameter of the punches were very important for the properties of the tablets. By combining the Principal Component Analysis with the Canonical Analysis, it was possible to select the variables which had a greater effect on the properties of the tablets.

Factors affecting the intake and digestion of roughage by sheep fed maize straw supplemented with maize grain

SummaryAfter a preliminary period in which they were all fed maize straw plus a proteinmineral supplement, 18 Merino wethers were divided into six groups and fed straw, proteins and minerals as before, plug pellets containing maize grain so that these constituted 0, 78, 156, 235, 313 and 393 g/kg of the total daily intake.The diets provided sufficient protein so that NH3and branched-chain volatile fatty acids were not limiting for growth of the fibre-digesting bacteria in the rumen.The intake of straw, the digestibility of cellulose and hemicellulose, and the mass of cellulose and hemicellulose digested per day declined linearly as the proportion of pellets in the diet increased above 78 g/kg. This decline was not related to the pH of the ruminal contents which was unaffected by the feeding of up to and including 235g pellets/kg diet, and which, with one exception, was only 2–6 pH-hours below pH 6 when more grain was fed.As the proportion of pellets in the diet increased the number of cellulolytic bacteria in the rumen declined to an extent which correlated well with the decrease in mass of cellulose digested per day. There was no change in the relative proportions of the predominant genera.There was no decrease in the number of xylanolytic bacteria in the rumen as more pellets were fed, but there was an indication of a change in the predominant genera producing diffusible xylanases.It is concluded that some factor, in addition to nutrient limitation and pH, may play a role in the decrease in intake and digestion of roughage when starch is fed. It is suggested that starch or sugars derived from it mayper seinhibit the synthesis and/or activity of the rumen cellulases and hemicellulases.

The influence of pellet size and density on the intake by calves of dried grass pellets given as supplements to hay

ABSTRACTHigh (1·31 kg/1) or medium-density (1·17 kg/1) dried grass pellets of 9, 12 or 18 mm diameter were given to British Friesian male calves of 7 to 14 weeks of age as supplements to chopped hay (Experiment 1). Pellets were given ad libitum but with access limited to two periods of 1½ h per day, and hay was given ad libitum for the remaining 21 h. In Experiment 2, high (1·34 kg/1) or medium-density (1·14 kg/1) dried grass pellets of 18 mm diameter were given to British Friesian male calves of 26 to 30 weeks of age. Pellets were given as supplements to chopped hay as in Experiment 1.There was no effect of pellet size or density on total intake of organic matter or live-weight gain by calves in either experiment. With the exception of animals given pellets of 12 mm diameter in Experiment 1, animals in both experiments consumed less pellets of high density than of medium density, but they were able to compensate for low pellet intake by eating more hay.The coefficients of variation for intake were higher in Experiment 1 than in Experiment 2, and higher for the intake of pellets than for total intake. There was a progressive increase in the intake (g organic matter/kg M0·75 per day) by calves in Experiment 1, whereas in Experiment 2 intake increased for the first 10 days and then remained constant. On average the proportion of pellets and hay consumed did not change in Experiment 1, but in Experiment 2 the proportion of pellets in the feed consumed increased from 53·5 to 60·6%.

The effect of density on the intake of dried forage pellets by young ruminants

SUMMARYDried grass pellets of high density (1·3 g/ml) were fed ad libitum to British Friesian male calves 5 to 7 mo old (Experiment 1) or 2 to 5 mo old (Experiment 2). All eight animals in Experiment 1 and eight out of 12 in Experiment 2 were fitted with rumen fistulae. In some subperiods of both experiments, pellets were broken down in water and administered as a slurry directly into the rumen at a level equivalent to approximately one-third that of voluntary intake. Intake per os was significantly reduced by this treatment but total intake (per os+per rumen) was not affected.In Experiment 3 pellets of high (1·24 g/ml) or medium (1·14 g/ml) density were fed ad libitum to 40 9-mo-old Suffolk × Scottish Halfbred wether sheep, either alone or with access limited to 3 hr a day, in which case chopped hay was always available. Pellet density did not affect total intake, but when offered as supplements to hay the consumption of medium-density pellets was higher than that of high-density pellets. In all three experiments animals required 2 or 3 weeks to reach maximum intake of pellets. Over the 42 days of Experiment 3 the proportion of pellets in the feed consumed by animals given pellets as supplements to hay increased from 60 to 80%.