Caking Capacity Research Articles

Physicochemical properties of microcomponents of the Kuznetsk Basin coals

Coals are heterogeneous in nature, and they most often combine different amounts of three macerals-vitrinite, liptinite and inerinite. Vitrinite, which is responsible for the caking capacity of coal, solubility in organic solvents, mechanical properties, etc., is of decisive importance for the technological properties of coal raw materials. This paper presents the results of a study of vitrinite concentrates isolated from coal of the Kuznetsk coal basin. Using chemical and physicochemical methods of analysis (technical and elemental analyses, IR and 13C NMR spectroscopy, etc.), analytical data were obtained reflecting the change in the composition of their organic mass from the degree of coalification. It was found that with an increase in the stage of metamorphism in vitrinite concentrates, the yield of volatile substances (Vdaf) decreases, the carbon content increases from 82.2 to 88.5% and, accordingly, the content of oxygen and heteroatoms in the organic mass decreases from 11.8 to 6.2%.

Enhancing Bioactive Compound and Antioxidant Activity of Cake by Using Pumpkin Powder

Background: Pumpkin is a rich source of dietary nutrients utilized for its leaves, pulp, and seeds to add value to the food product. Objectives: The study was designed to assess the effects of pumpkin powder as a partial replacement of wheat flour on proximate analysis, bioactive component, physical, and sensory properties of cake. Methods: The cakes were prepared by replacing 5%, 10%, and 15% of wheat flour with pumpkin powder and compared with control cake where no pumpkin powder was added. Results: Water and oil holding capacity of pumpkin powder were found significantly higher (P<0.05) than wheat flour but there was no significant (P>0.05) difference found in emulsion activity and emulsion stability. Protein and ash content of cake also increased with increasing substitution of pumpkin powder in wheat flour. Pumpkin powder increased the bioactive compound of cake and increased with increasing incorporation on wheat flour. Highest β-carotene content was observed in 15% pumpkin cake (1.12 mg/100g) followed by 10% cake (0.91 mg/100g). Total phenolic content also increased in pumpkin cake than control cake and the highest concentration was found in 15% pumpkin cake. Increasing proportions of pumpkin powder results in increasing antioxidant capacity of cake and found 11.24% to 19.76% for control to 15% pumpkin cake. In texture profile analysis, the hardness of samples increased slightly and vice versa for chewiness in pumpkin powder cake. Conclusion: The addition of 10% pumpkin powder significantly improved the nutritional as well as sensory attributes of cake.

The role of digital simulation in assessing and reassessing the potential of complex coal deposits

The article addresses the increasing complexity of mined or prospective coal deposits. The paper analyses the role of digital simulation in operation assessment and reassessment of the potential of complex in structure coal deposits for more accurate understanding their investment attractiveness, reliability of knowledge on quantity and quality of the reserves. The article stresses the objective need to take into account the realities of the VUKA-world, when companies have to react rapidly to changing of external conditions by adapting organizational and technological measures as much as possible to the constantly overestimated potential of the raw material base. It is of note that reserves should be assessed in accordance with international requirements in the light of the increasing number of parameters for management. The complexity of the structure, the geomechanical heterogeneity of the rock mass, the mineral content of the impurities in the coal, its caking capacity, oxidation and enrichment are taken into account in the estimation. The paper presents the measures to increase the level of utilization of geological potential through the application of selective mining and the control of different quality coal streams in preparation for enrichment and during primary processing.

Elaboration of New Types, Environmentally Safe Fire- Extinguishing Powders and Establish the Conditions of Extinguish Optimum and Effective Use of Such Powders

The aim of the presented investigation is the development of technology for production of novel, halogen-free, environmentally safe, highly efficient fire-extinguishing powders based on local mineral raw materials, which does not require modification with expensive, halogen-inclusive, hydrofobizing additives, providing low-cost production of fire-extinguishing powders in comparison with imported analogues. The optimal dispersity was selected in such way, that caking capacity be minimal and a homogeneous action of combustion products on the flame as well as a heterogeneous inhibition of combustion process must take place. The evaluation of powder efficiency is carried out with consideration of the both effects. Experimental data confirm that the developed fire-extinguishing powders are characterized with high performance characteristics, as well as high fire-extinguishing capacity. At the same time, it should be noted, that the efficiency of the obtained powders is practically the same as of standard imported powders, but do not contain any halogens, is environmentally safe and 1.5-2 times cheaper than the imported analogues. For obtained powders, the conditions of extinguish optimum and effective use of powder are stated. Optimum extinguishing condition means the selection of optimum intensity of powder supply into seat of fire when minimum consumption of powder provides fire extinguishing in minimum time. Thus, in order to determine optimum conditions of extinguishing it is necessary to study the dependence of powder specific consumption and extinguishing time to supply intensity. For our powders optimum condition of extinguish is: powder supply intensity I-0.6-1.0 kg/m2sec to fire center when powder specific consumption does not exceed G=0.8-1.2 kg/m2. Therefore, we can assume that the use of fire-extinguishing powders of our preparation is possible at extinguishing all types of fires over ground, as well as, underground constructions and does not need additional antiseptic measures.

Microstructure peculiarities of carbon materials based on coal-tar pitch hardened on the surface of thermally expanded graphite flakes

The structure of self-caking artificial graphite based on coal-tar pitch hardened at 225, 275, and 450°C by oxidation with atmospheric oxygen on the surface of thermally expanded graphite (TEG) flakes was studied by scanning electron microscopy. In the course of the preparation of the material after hardening, the flakes covered with pitch were tightly compressed on grinding to molding powder in a ball mill and during the extrusion of laboratory workpieces in a rigid matrix to result in a laminar structure of the test materials. It was found that the caking capacity of TEG flakes and pitch layers decreased as the temperature of oxidation was increased. The thicknesses of pitch layers and TEG flakes were estimated based on the distance between the layers of the material.

Caking capacity and modification of carbon filler-binding agent composites

Data on the caking capacity of composites containing cokes of various origins and coal-tar pitches are summarized. It was demonstrated that the yield of coke from pitch can serve as a value characterizing the caking capacity of the composites. The effect of the porosity of a filling agent on the caking capacity was found.

Effects of the time of combined vibration grinding and the compacting pressure on the density and shrinkage of graphite MPG-7 workpieces

A technique for the manufacturing of graphite MPG-7 was developed on a laboratory scale with the use of the following new raw materials: uncalcined isotropic shale tar coke and three high-temperature pitches. The caking capacity and density of the test samples of MPG-7 after molding, burning, and graphitizing were determined. It was found that the optimum concentration of a binding agent determined from the caking capacity decreased from 40 to 28% as the volatile matter content of coke increased from 4.5 to 9.5% and the softening temperature of pitch decreased from 148 to 135°C. In this case, the total shrinkages of the test samples decreased from 60 to 54%, and their densities decreased from 1.98 to 1.76 g/cm3. The optimum time of combined vibration grinding was determined, and the range of compacting pressures was chosen. The relationships between the densities of the test samples burned under laboratory and production conditions, as well as between the densities of burned and graphitized samples, were obtained. These relationships make it possible to predict the density level of MPG-7 material reached under plant conditions.

05/02396 Some aspects of structural transformations taking place in organic mass of Ukrainian coals during heating. Part 1. Study of structural transformations when heating coals of different caking capacity

05/02396 Some aspects of structural transformations taking place in organic mass of Ukrainian coals during heating. Part 1. Study of structural transformations when heating coals of different caking capacity

Some aspects of structural transformations taking place in organic mass of Ukrainian coals during heating. Part 1. Study of structural transformations when heating coals of different caking capacity

The structure of the plastic layer in coals of different caking capacity was studied using the X-ray method and the influence of the plastic layer structure on the mechanism of coke formation was determined. It is shown that the transportation of the plastic mass in the gas-saturated zone of the plastic layer has a decisive influence on the decrease in volume of the coal charge and on obtaining a denser residue during carbonization. When heating poorly caking and non-caking coals an increase in the charge volume takes place. Using the quantitative X-ray phase analysis an ordered phase amount ( C cryst) was found in solid residues of carbonization and the parameters d 002, L c and L a were determined. It is shown that the gas-saturated zone is generated in the plastic layer only when structural transformations in coals take place at the pre-plastic stage without changing the ratio between the number of carbon atoms in the ordered and non-ordered phases. The transition of well caking coal into the plastic state is accompanied by the activation of segmental and conformal movement of side chains and separate macromolecular fragments of the coal organic mass. In the course of grain swelling of non-caking coal its crystallites degrade. The conclusions drawn on the basis of X-ray studies were confirmed by the EPR-spectroscopy of residues corresponding to plastic zones in coals of different caking capacity.

Some peculiarities of formation mechanism of metallurgical coke from polish coals

The carbonisation of two Polish coals of different caking capacity was studied in a laboratory unit using X-rays. Based on the X-ray pictures of a coal charge being heated with some markers a dynamic pattern was constructed for a coking process of well caking coals. It is shown that a displacement of the non-volatile mass of the coal charge takes place causing a change in the charge volume and forming porosity in the solid residues. On the basis of the marker trajectory during heating it is shown that on coking good caking coals the volume change of the charge proceeds stepwise. A relationship was established between a compaction of the foamy mass in the plastic layer of good caking coals and the thickness of the gas-saturated zone in it. The X-ray data have been confirmed by experimental data using scanning electron microscopy.

Effect of hydrothermal treatment on caking propensity of coal

The development of caking propensity in a non-caking coal under hydrothermal conditions has been studied, using water up to 400°C under autogenous pressure. Although it was not possible to obtain uniform development of caking propensity or to isolate a product with upgraded caking capacity without in situ agglomeration, hydrothermal treatment promoted the formation of a coke-like mass. The role of water near its critical temperature in incipient hydrogenation was observed. Comparison with the normal coalification track provided apparent reasons for the observed limited development of caking propensity in the coal used. The overall effect appears to be the resultant of deoxygenation or dehydroxylation, hydrogenation and polymerization reactions that may be coal-specific.

The significance of coal properties for acetylene formation in a hydrogen plasma

Beside the influence of power input, temperature, flow rates, and retention time, the yield of acetylene by direct conversion of coal in a plasma arc is essentially determined by chemical coal quality. It is shown which coal properties are significant for the product distribution acetylene, char and side products, i.e. volatile matter-content, calorific value and caking capacity of the feed coal.

Studies on Production of Petroleum Pitch from Vacuum Residue by Heat-Treatment (Part 2)

The chemical structure and the caking capacity of fractions in the pitches prepared from Murban vacuum residue were investigated. The pitch was fractionated by n-pentane, benzene and quinoline into four fractions of PS, PI•BS, BI•QS and QI. The NMR spectra, molecular weight and elementary analysis were measured on the fractions, and the structural parameters were estimated. The caking capacity for each fraction was measured by means of the Roga test.The following results were obtained.(1) The structural parameters, molecular weight and the Roga index of each fraction were changing in the early stage of heat-treatment when the decomposition reaction mainly occurred, however these values became nearly constant in the latter stage when the polymerization-condensation reaction became predominant.(2) The degree of condensation was considered to have a tendency to increase in the order of PS, PI•BS, BI•QS, QI. An average number of condensed aromatic rings of each fraction was estimated to be PS: 2-3, PI•BS: 6-7 and BI•QS: 11 and over, respectively. The Roga index of each fraction was PS: 11-22, PI•BS: 60-80, BI•QS: 74-90 and QI: 0, respectively. These results suggest that to obtain the pitch of high caking capacity, vacuum residue must be converted at least into the PI•BS fraction having 6-7 condensed aromatic rings and the aromaticity above 0.7.(3) QI which has no caking capacity by itself showed a high caking capacity when coexisting with the fraction of high fluidity such as PS, PI•BS and BI•QS.