Influence of the batch’s ash content on coke quality (CRI and CSR)

To permit more precise assessment of Russia’s coal reserves, the influence of the batch’s ash content on the reactivity (CRI) and postreactive strength (CSR) of the coke produced is analyzed.     

Repair of coke-furnace linings by ceramic surfacing in the EvrazKokSibir’ coke shop

Defective sections of furnace-chamber linings must be cleaned by air-powder abrasion prior to ceramic surfacing. Devices for smoothing the walls may be used for this purpose. Data regarding the scorching of linings in coke batteries at OAO EVRAZ ZSMK are presented, along with the results of repairs by ceramic surfacing.     

Determination of the ash content of solid fuel using annihilation γ-rays

The possibility of the instrumental determination of the ash content of solid fuel using annihilation γ-rays was demonstrated. Analytical expressions for the evaluation of sensitivities were obtained. The method was recommended for the analysis of high-ash coals in large masses without special sample preparation.     

Measuring the Young’s modulus of polystyrene-based composites by tensile test and pulse-echo method

In this study, the pure polystyrenes (PS) with different molecular weights (3.5 × 10⁵ and 5.0 × 10⁵) have been modified by the chemical modification with succinic anhydride (SA), maleic anhydride (MA), and phthalic anhydride (PhA). The modified polystyrenes (MPS) have been mixed with the pure PS with the molecular weight of 2.3 × 10⁵ in weight % ratio 90:10, 80:20, and 70:30. Young’s modulus of obtained composites has been measured mechanically by the tensile test and ultrasonic method at frequency of 5 MHz. Further, the values of Young’s modulus measured by both methods have been compared with each other. From the results, a significant difference has not been found between the values of Young’s modulus of both methods. As a result it can be stated that measuring the Young’s modulus of these materials by the ultrasonic methods is more sensitive and economical than the mechanical methods.     

Influence of the blast furnace’s operating conditions and coke quality on the life of air tuyeres

The influence of the coke characteristics and blast-furnace conditions on the durability of air tuyeres is considered.     

Influence of the coke filler on the carcinogenicity of pitch–coke mixtures on carbonization

The emissions of benzo[a]pyrene at different temperatures and its concentration in the exhaust gases are measured in laboratory experiments on the carbonization (at temperatures up to 850°C) of coalpitch and petroleum-pitch binders and their mixtures with roasted petroleum and pitch coke. These pitch–coke mixtures are similar in composition to the anode mass used in aluminum production. The experiments confirm that the total benzo[a]pyrene emissions are much greater in the carbonization of petroleum pitch produced by cracking (T _so = 100°C) than for electrode pitch (T _so = 89°C) and other coal pitch. In most experiments, the benzo[a]pyrene emissions in the carbonization of pitch–coke mixtures is markedly less than for individual binder pitches. It is found that the benzo[a]pyrene emissions in the carbonization of a mixture based on pitch coke are much less than for a mixture based on petroleum coke in the high-temperature region that presents the greatest environmental hazard.     

Effect of boron trioxide on coke’s inner carbon solution loss reaction

Boron Trioxide (B₂O₃) was adsorbed on coke through boric acid (H₃BO₃) solution, of which the concentration was 0.1%, 0.5%, 1.0%, 2.0% respectively. The existence form and distribution of boron (B) adsorbed on coke were characterized by X-Ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Inductive coupled plasma (ICP), effect of B₂O₃ adsorbed on coke was investigated by carbon solution loss reaction (CSLR) under the condition of the same weight loss. Results show that: H₃BO₃ changes into B₂O₃ after adsorption treatment, and is adsorbed on coke success-fully; B₂O₃ exhibits negative effect on coke CSLR; with the solution concentration increases, the negative effect is strengthened, and coke’s inner reactivity becomes severer, which is not beneficial for coke strength.     

the determination of rig

per or not. For many years, scientists in the world have done a lot of research work in this field. As opinions vary, no unanimous conclusion can be drawn.In this paper, the physical concept of each items in rigidity is analysed first, an     

APS-silane modification of silica nanoparticles: effect of treatment’s variables on the grafting content and colloidal stability of the nanoparticles

Silica nanoparticles, Aerosil 200, with an average primary particle size of 12 nm were chemically modified by γ-aminopropyltriethoxy silane (APS) via a two-step sol–gel process. Effects of the treatment variables including reaction temperature, water content, and silane concentration on the colloidal stability and the amount of APS grafting on the surface of nanoparticles were studied using thermal gravimetric analysis, diffuse reflectance infrared spectroscopy, and by monitoring the sedimentation behavior of the dispersion of nanoparticles in distilled water as a polar media. Furthermore, the effect of surface modification on the dispersibility of silica nanoparticles in an epoxy novolac coating was evaluated by means of scanning electron microscopy. The results showed chemical interactions between APS and SiO₂ nanoparticles. Also, parameters including treatment at ambient temperature, low level of water, and moderate concentration of silane compound, have a considerable effect on the APS grafting content due to the increase of silane hydrolysis and higher silylation coverage of the nanoparticles.     

Chemical Analysis of Magnesia and Magnesia-Alumina Refractory Materials ——Flame atomic absorption spectrometric method for determination of calcium oxide content

GB/T 5069.10-2001 1 Scope This standard specifies the determination of calcium oxide content by flame atomic absorption spectrometric method. This standard applies to the determination of calcium oxide content in magnesia and magnesia-alumina refrac…     

Effects of diazenedicarboxamide additive on the content of α-Si3N4 synthesized by combustion method

Combustion synthesis (CS) of high content of α-Si₃N₄ powders was carried out using Si and Si₃N₄ powders as reactants with the addition of diazenedicarboxamide (AC) at a relatively low N₂ pressure of 3 MPa. Effects of diazenedicarboxamide contents on the phase compositions and Si₃N₄ particle morphologies were studied. In addition, the reaction mechanisms were discussed. The results indicated that the additive diazenedicarboxamide promoted the nitridation of Si. The α-Si₃N₄ content in the combustion-synthesized products showed great dependence on the additive contents, which reached 85.21 wt% with 24 wt% diazenedicarboxamide added. N₂, CO and NH₃ produced by the decomposition of diazenedicarboxamide leaded to a change of compact porosity and the formation of micro-pores in the reactive area, which was responsible for the increasing contents of α-Si₃N₄ and the discrepancy morphology of the products.     

Oxidation kinetics of MgO–C in air with varying ash content

Abstract

MgO–C refractories are extensively used in metallurgical vessels in the steel industry. The graphite plays a vital role owing to its non-wettability with slag. Though quality is very important for graphite, little published data is available on the effect of varying ash content on oxidation. Since MgO–C bricks manufactured from graphite with different ash contents are regularly used for lining converters and steel ladles at SAIL plants, a study has been conducted to select an optimum graphite with low cost. Graphites with 2·8, 4·4, 12 and 20% ash content were used to make MgO–C samples in the laboratory, and oxidation properties were evaluated using an electrically heated tube furnace. Kinetic analysis shows that a chemical reaction mechanism operates in the earlier part of oxidation, followed by a diffusion mechanism in the latter part. MgO–C manufactured from graphite with 4·4% ash content was observed to have the best oxidation resistance, with an activation energy of 43·4 kJ mol^?1 during the earlier stage followed by 34·2 kJ mol^?1 in the latter.     

Photocatalytic degradation of dye by Ag/ZnO prepared by reduction of Tollen’s reagent and the ecotoxicity of degraded products

A heterostructure of Ag/ZnO powder was prepared by a reduction of Ag(NH₃) ₂ ⁺ ions in a basic solution or Tollen’s reagent. From this method, the existence of a metallic Ag coating on the ZnO surface was confirmed by transmission electron microscope and x-ray photoelectron spectroscopy. The photocatalytic activity of the Ag/ZnO powders was investigated by analyzing the degradation of an aqueous methylene blue solution under a blacklight irradiation. Furthermore, the parameters, including Ag content, catalyst loading, initial dye concentration and pH, were also studied. After the methylene blue solution was irradiated for 30min under a blacklight illumination, total mineralization was not observed as the presence of some carbon compound species was indicated in a mass spectrum. Furthermore, the toxicity of the treated methylene blue solution produced by the Ag/ZnO powders was also investigated by a test for the inhibition of the growth of Chlorella vulgaris.     

Simultaneous spectrophotometric determination of manganese,zinc and cobalt by kernel partial least–squares method

Simultaneous spectrophotometric determination of Mn, Zn and Co was studied by two methods, classical partial least-squares (PLS) and kernel partial least-squares (KPLS), with 2-(5-bromo-2- pyridylazo)-5-diethylaminephenol (5-Br-PADAP) and cetyl pyridinium bromide (CPB). Two programs, SPGRPLS and SPGRKPLS, were designed to perform the calculations. Eight error functions were calculated for deducing the number of factors. Data reductions were performed using principle component analysis. The KPLS method was applied for the rapid determination from a data matrix with many wavelengths and fewer numbers of samples. The relative standard errors of prediction (RSEP) for all components with KPLS and PLS methods were the same (0.0247). Experimental results showed both methods to be successful even where there was severe overlap of spectra.     

Quantitative determination of fly ash in the hydrated fly ash - CaSO4·2H2OCa(OH)2 system

For the quantitative determination of fly ash in hydrated fly ash - CaSO₄·2H₂OCa(OH)₂ system, various kinds of selective dissolution were evaluated using pastes made from a single representative fly ash. Selective dissolution using picric acid-methanol solution was found to be adequate. Selective dissolution using picric acid - methanol + water can also be used, when it is necessary to save time, although rather bigger corrections are needed. Reproducibility of the determination by both methods was found to be satisfactory, as the standard deviation of the measurement was within 0.23 – 0.55%. Several dissolution experiments were also carried out to obtain the basic information related to this technique.     

Synthesis of geopolymers from volcanic ash via the alkaline fusion method: Effect of Al2O3/Na2O molar ratio of soda–volcanic ash

The alkaline fusion method was used to enhance the reactivity of volcanic ash for geopolymer synthesis. To that end, different mixtures of fused soda–volcanic ash (fused volcanic ash) were used to assess reactivity for geopolymer synthesis. The amount of amorphous phase was determined both in the volcanic ash and the fused volcanic ash and X-ray diffraction analysis was used to evaluate effect of the alkaline fusion method. Different geopolymer mortars were prepared by alkaline activation of mixtures of powders of fused volcanic ash and metakaolin and river sand using sodium silicate as activator. Metakaolin was considered as consumer of excess of alkali contained in the fused volcanic ash. The geopolymer mortars were characterized by determination of setting time, linear shrinkage, compressive strength and scanning electron microscopy. The amount of amorphous phase and excess of fused soda content of the fused volcanic ash depended on molar ratio of Al₂O₃/Na₂O and played a key role for geopolymer synthesis. The most convenient Al₂O₃/Na₂O molar ratio of fused volcanic ash to produce effective geopolymer mortars ranged between 0.13 and 0.18. This study showed that volcanic ash can be used successfully as an alternative raw material for production of geopolymers via alkaline activation of fused volcanic ash.     

Increasing the burning velocity of a low-pressure hydrogen-oxygen flame by the addition of trimethyl phosphate in terms of Zel’dovich’s chain mechanism of flame propagation

The chain reaction mechanism and theoretical approach proposed by Zel’dovich for hydrogen flame propagation are used to describe the effect of increasing the burning velocity of a low-pressure hydrogen-oxygen flame by the addition of trimethyl phosphate (TMP), which induce a catalytic recombination of hydrogen atoms. The promotion of a stoichiometric hydrogen-oxygen flame at subatmospheric pressure by the addition of TMP at a low concentration (0.1–0.5%) is described using a model of the catalytic recombination of hydrogen atoms. The results of calculation using Zel’dovich’s theory with the proposed simplified kinetic model are in good agreement with simulation results for the complete kinetic mechanism. It is shown that increasing the recombination rate of hydrogen atoms in a catalytic reaction involving phosphorus-containing species increases the heat release rate and, hence, the flame burning velocity. A kinetic analysis was performed of the dependence of the ratio of the recombination and branching rates, the temperature at the maximum reaction rate, and the maximum mole fraction of hydrogen atoms on the pressure and additive concentration. The study confirmed Zel’dovich’s prediction that the recombination not only has the harmful effect of terminating chains, but it also has the beneficial effect of releasing heat.     

Available nitrogen in soils and its determination by the ‘Nmin-method’ and by electroultrafiltration (EUF)

Excess nitrogen fertilizer rates are an environmental hazard. To avoid excess rates, the level of available nitrogen in the soil must be known and considered for assessing the nitrogen fertilizer rate. In arable soils nitrate and exchangeable ammonium in the rooting depth of a crop are directly available to plant roots. These two nitrogen forms are recovered with the Nmin method and they are considered in assessing the nitrogen fertilizer rate for arable crops.Besides nitrate and ammonium recovered by the Nmin method from soil samples taken in early spring, a considerable amount of organic soil nitrogen may be mineralized during the growth period and contribute to crop nutrition. The nitrogen mineralization potential can be determined in incubation tests. The absolute quantities of mineralized nitrogen thus obtained, however, are much higher than the mineralization rates under field conditions. It is for this reason that incubation tests have not obtained a major importance for assessing nitrogen fertilizer rates.With the electro-ultrafiltration (EUF) method nitrate, ammonium, and a minor portion of organic soil nitrogen are extracted from a soil suspension. There is experimental evidence that this organic nitrogen (=Norg) is easily mineralizable. Based on field experiments with cereals and maize formulae were established by which the nitrogen fertilizer rate can be calculated. In these formulae nitrate, ammonium and organic nitrogen extracted by EUF are considered.Advantages and drawbacks of the Nmin method and EUF method are discussed.