Optimizing the preparation of coal batch for coking at ChAO Makeevkoks

The expediency of introducing up-to-date systems in the preparation of coal batch for coking at ChAO Makeevkoks is evident if the quality of the coal concentrates employed is assessed in terms of technical, plastometric, petrographic, and granulometric characteristics. Coking trials indicate that separating out the small coal classes prior to final crushing significantly improves the technological characteristics (M ₂₅, M ₁₀) and structural parameters (the Ginzburg abrasive hardness and Gryaznov structural strength) of the blastfurnace coke produced. Introducing hydrocarbon briquets in the coal batch permits the utilization of coking waste without impairing the coke strength.     

Coke Quality and Blast-Furnace Performance

On the basis of six-year operational data for a 5000-m³ blast furnace, the dependence of the coke consumption on its strength M₂₅ and M₁₀ and the content of the >80 mm fraction is calculated by different methods. The quality of the coke has a clear influence on coke consumption and blast-furnace economics. As an illustration, for some of the equations derived, means are established for predicting the economic benefit associated with improving coke quality and reducing its consumption, in specific blast-furnace conditions.     

Improving the Preparation of Coking Batch

Currently, the most promising blast-furnace technology involves pulverized-coal injection, and the most promising blast-furnace technology for coke production involves ramming the coal batch before delivery to the coke ovens, so as to ensure high packing density. In classic bed coking, the packing density of the coal batch is also of great importance. In the absence of mechanical methods (such as ramming or partial briquetting), the packing density mainly depends on the ash and moisture content and the degree of crushing of the batch. It follows from industrial tests in the coke plant at PAO ArcelorMittal Krivoy Rog and analysis of the multifactorial correlation of the strength M₂₅ and wear resistance M₁₀ with the packing density of the batch that, with decrease in packing density, the coke strength and wear resistance decline. That increases coke consumption and considerably complicates blast-furnace operation. Since improvement in coke quality entails decreasing the moisture content of the coal batch, a method has been developed for decreasing the moisture content directly in the silo, on the basis of osmosis and vacuum, that permits decrease in the coal’s moisture content to the optimal value, thereby boosting coke quality and improving blast-furnace performance. For example, it has been established that, in the blast-furnace shops at PAO ArcelorMittal Krivoy Rog, 1% decrease in M₁₀ lowers the mean coke consumption by 5.5%. With increase in M₂₅ by 1%, the mean coke consumption falls by 2.1%, on average.     

Production and Use of Lignite-Based Coke Briquets with High Hot Strength

A production technology has been developed for strong briquets (with high CSR and M₂₅) based on coke derived from Kansko-Achinsk lignite. A mixture consisting of lignite coke and binder (Zh and KZh coal) is crushed (to particle size less than 0.2 mm) and mixed with strengthening additive. This blend (57.7% lignite coke + 19.2% binder + 23.1% additive) is shaped into briquets, which are roasted at 1000°C and cooled in the absence of air. For the briquets, CSR = 58.8% and M₂₅ = 97.4%. The strength in drop tests is 99.1%, and the wear resistance is 99.2%. Technical analysis of the briquets shows that W = 1–2%, A^d = 8–10%, V^daf = 3–7%, S^d = 0.2–0.4%, P^d = 0.014%, and C_fix = 85–88%. The briquets are characterized by distinctive physicochemical properties, such as high activity with respect to CO₂ (\(K_{CO_2}\) = 4.6 cm³/g s; CRI = 66.1%). Its electrical resistivity ρ = 8 Ω cm for the 3–6 mm size class; and its developed porosity is 50–56%. Applications of the briquets are outlined.     

Evaluating ukrainian coal batch in terms of optimal rank composition

The overall decline in the optimality coefficient K _opt of the rank composition of coking batch at Ukrainian plants in 2004 (77.4%), 2005 (73.0%), and 2006 (66.9%) may be attributed primarily to the growing shortage of clinkering coal. For Russian and Ukrainian coke, the dependence of M ₂₅ on K _opt is described by regression equations with similar coefficients.     

Influence of Neryungrinskaya concentrate on the coke quality and the coke-discharge force

Neryungrinskaya concentrate has distinctive coking properties, on account of its high vitrinite reflection coefficient and high Audibert-Arnu expansion index b. The mechanical strength M ₂₅ of the coke and the load on the coke-discharge drive are determined as a function of the content of Neryungrinskaya concentrate in the batch.     

Assessing the technological value of coal in coking

Coking coal of the same rank from different countries and fields may be distinguished in terms of use value by rating on the basis of seven technological and petrographic characteristics that determine the coke yield and properties: the ash content A^d; the total sulfur content S_t^d; the yield of volatiles V^daf; the plastic-layer thickness y; the vitrinite reflection coefficient R_o; the content of vitrinite-group macerals Vt; and the basicity index B_b. A range of values and a rating (on a scale from 1 to 10) are established for each of these parameters. Each rating corresponds to a particular score (from 0.1 to 1.0). Ranges of A^d, S_t^d, Vt, and B_b are established for the whole metamorphic series, while ranges of V^daf, y, and R_o are established for individual ranks and groups of ranks. Altogether, 105 coking coals from Ukraine, Russia, the United States, Australia, and Canada that are used at Ukrainian coke plants are investigated. The range of rating scores and their mean values are determined for individual coal ranks and groups. As an example, three bituminous coals from Ukraine, the United States, and Australia are compared by the proposed method. This method permits objective assessment of the technological value of coal within a single rank and the selection of the best purchase option.     

Preparation and Characteristics of Polyphenylsilsesquioxane-<Emphasis Type="Italic">b</Emphasis>-Polyurethane Copolymer as a Dielectric Material

Polyphenylsilsesquioxane-b-polyurethane copolymers were prepared in the presence of dibutyltin dilaurate catalyst by copolymerization of polyphenylsilsesquioxane (PPSQ) with a α,ω-diisocyanate group terminated polyurethane (DPU) prepolymer of various molecular weights. Additionally, DPU prepolymers were prepared by the reaction of isophorone diisocyanate and various polycaprolactones (PCL, M _w : 400, 830, 1250). The introduction of air-filled pores in the copolymer matrix was accomplished by removing the DPU segment in an electric furnace equipped with a N₂ gas injection port. The thermogravimetric properties of the products were measured in order to identify the thermal decomposition temperature of the DPU prepolymer and to ascertain the thermal stability of the copolymer matrix. Furthermore, the atomic force microscopy (AFM) and scanning electron microscopy (SEM) were measured to obtain more detailed information on the surface of copolymer film. With the results of the AFM analysis of the materials prepared with the DPU prepolymers of lower molecular weight, it was possible to identify well-dispersed air-filled pores in the copolymer matrix film. In particular, the dielectric constant drastically decreased with the introduction of the air-filled pores.     

Optimization of controlled ring-opening polymerization of <Emphasis Type="SmallCaps">l</Emphasis>-lactide to hydroxyl terminated polylactides using zinc acetate catalyst

Hydroxyl terminated polylactide polymers with number of average molecular weights (M _n ) varying from 1625 to 3459 g mol^?1 were synthesized by ring opening bulk polymerization of lactide in the presence of zinc acetate being a potent catalyst. The use of 1,4 butanediol (BDO) initiator leads to hydroxyl terminated polylactides, thus excellent precursors for shape-memory biodegradable polyurethanes. Different reaction conditions employed for the synthesis of hydroxyl terminated polylactide polymers via activated monomer mechanism may result in differences in M _n , percentage mass conversion and percentage degree of crystallinity (%χ _c ) of the product. Influence of process parameters, i.e. catalyst concentration, initiator concentration, reaction temperature and time on characteristics of hydroxyl terminated polylactides was studied. These polymers were characterized by Nuclear Magnetic Resonance (¹H-NMR) spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and X-ray diffraction (XRD) techniques. FTIR and ¹H-NMR confirmed the formation of hydroxyl terminated polylactides. M _n was determined by ¹H-NMR, GPC and end group analysis. %χ _c was calculated from XRD spectra. Maximum mass conversion, M _n and %χ _c were observed at 5 mol% SnOct₂ and 5 mol% BDO concentration. At optimum temperature of 145 °C, these characteristics improved linearly with polymerization time up to 6 h and declined thereafter.     

Fuzzy-based nonlinear PID controller and its application to CSTR

This study presents a new design method for a nonlinear variable-gain PID controller, the gains of which are described by a set of fuzzy rules. User-defined parameters are tuned using a genetic algorithm by minimizing the integral of absolute error and the weighted control input deviation index. It was observed in the experimental results on a continuous stirred tank reactor (CSTR) that the proposed controller provided performances: overshoot M _p ≤1.25%, 2% settling time t _s ≤1.71 s and IAE≤1.26 for set-point tracking, perturbance peak M _peak ≤0.05%, 2% recovery time t _rcy ≤3.97 s and IAE≤0.10 for disturbance rejection, and M _peak ≤0.04%, t _rcy ≤2.74 s and IAE≤0.04 for parameter changes. Comparison with those of two other methods revealed that the proposed controller not only led to less overshoot and shorter settling time for set-point tracking and less perturbance peak and shorter recovery time for disturbance rejection, but also showed less sensitivity to parameter changes.     

Specific features of halogen binding in binary alkali silicate glasses

This paper reports on the results of the chemical synthesis of halogen-containing alkali silicate glasses M ₂O-MHal-SiO₂(M= Li, Na, K; Hal = Cl, F). From analyzing the obtained results, a conclusion is drawn regarding the specific features revealed in the incorporation of halogens into the silicate matrix. A model explaining the considerable losses of chlorides upon their introduction into binary melts is proposed.     

Novel Phospholium-Type Cationic Surfactants: Synthesis,Aggregation Properties and Antimicrobial Activity

A series of novel phospholium amphiphilic compounds with straight alkyl chains with different numbers of carbon atoms (12, 14, 15, 16, 17, 18) were synthesized. The quaternary phosphorus, phosphonium cation, is incorporated into a five-membered heterocyclic ring. Their physicochemical properties were investigated by measurements of surface tension, conductivity and dynamic light scattering. The critical micelle concentration (c _M), the surface tension value at the c _M (γ _cmc), the surface area at the surface saturation per head group (A _cmc), the ionization degree of micelle (α), the free energy of micellization (ΔG° _mic), and hydrodynamic diameter (d _h) were determined. Antimicrobial activity was tested against bacteria and yeast. The structure–activity relationship was determined.     

Influence of batch composition and clinkering properties on the hot strength of coke and blast-furnace operation

The relation of the basic characteristics of coking batch to the hot strength CSR and reactivity CRI of coke is established. The plastic layer of the batch components influences CRI and CSR. The relation of the batch composition to CSR and CRI is determined. When using enrichment batch that contains ～50.4% cokeforming coal, the best results are obtained: CSR = 61.8–62.3% and CRI = 26.4–26.7%.     

Structure and mechanical destruction of coal

Parameters characterizing the structural strength K _st and physical strength K _ms of coal are proposed. These parameters are suitable for estimating the change in state of the coal under the mechanical action of external forces. Their ratio permits ongoing determination of the mechanical destruction K _md of genetically inhomogeneous coals characterized by different degrees of oxidation.     

Effect of nitrogen to niobium atomic ratio on superconducting transition temperature of δ-NbN<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> powders

Powders of cubic niobium nitride δ-NbN _x with a particle size of below 20 μm were prepared by reactive diffusion at T = 1455?1475°C under nitrogen pressures of P ₁(N₂) = 0.1?3 MPa and P ₂(N₂) = 25 MPa. For these powders, the values of the stoichiometric coefficient x, lattice parameter a, and the superconducting transition temperature Tc were measured and the a(x), T _c(x) and T _c(a) functions were analyzed. The T _c values were found to linearly grow with increasing a (decreasing structure imperfection). A maximum value of T _c (15.8 K) corresponded to a maximum value of a (4.3934 Å). Maximain the a(x) and T _c(x) curves were found to correspond to a slightly substoichiometric nitride with x = 0.98. Having synthesized cubic niobium nitrides with 0.892 < x < 1.062, we managed to measure the dependences of a and T _c on x all over the almost entire homogeneity range for δ-NbN _x . Our a(x) and T _c(a) functions were found to reasonably agree with those previously reported for SHS-produced δ-NbN _x powders.     

Catalytic Cu(II)–polymer complexes as recyclable catalysts for the synthesis of poly(2,6-dimethyl-1,4-phenylene oxide)s in water

Water-soluble polymers comprising itaconic amide acid with acrylic acid or acrylamide, which contain carboxylic acid and amide groups capable of coordinating to the copper catalyst, were synthesized by radical polymerization using an azobisisobutyronitrile initiator. These polymers were used as polymer ligands to prepare copper complexes, which were subsequently analyzed by UV–Vis spectroscopy. The complexes were then used as catalysts for the oxidative polymerization of 2,6-dimethylphenol (DMP) to synthesize poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) under oxygen and in the presence of a surfactant in alkaline water. The polymerization conditions were optimized by varying the amounts of polymer ligands and copper precursors, the concentrations of surfactant and hydrogen chloride, and the temperature, resulting in PPO with a maximum yield of 93%, a number-average molecular weight (M _n) of 3700, and a molecular weight distribution (M _w/M _n) of 2.12. This yield is higher than that previously achieved using arginine ligand in water (72%). Furthermore, the optimum conditions were applied in the copolymerization of DMP and 2-allyl-6-methylphenol to obtain a thermally crosslinkable copolymer in 95% yield (M _n = 3000, M _w/M _n = 2.5). In addition, the catalyst complex of the copper–polymer ligand was recovered and reused after the polymerization of DMP. The catalyst maintained its activity even after being recycled five times, without the addition of copper precursor or polymer ligand, thereby demonstrating an environmentally friendly process wherein environmental emissions and production costs can be substantially reduced.     

Partition of <Emphasis Type="Italic">n</Emphasis>-Butanol Among Phases and Solubilization Ability of Winsor type III Microemulsions

The partition of n-butanol in Winsor type III (W-III) microemulsions was investigated in this work. Three kinds of anionic surfactants (sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (DSS), and sodium dodecyl benzene sulfonate (SDBS)) and two kinds of anionic/cationic surfactant mixtures (SDS/octadecyl trimethyl ammonium chloride (OTAC) mixtures and DSS/OTAC mixtures) were studied. Internal standard gas chromatography was employed in n-butanol content analysis. The results showed that no water exists in the excess oil (EO) phase and no oil exists in the excess water (EW) phase. For the W-III microemulsions obtained by salinity scanning, relatively constant n-butanol content in the EO (11–12 v%) and EW (1–4 v%) was found under different salinities. Accurate measurement of n-butanol content in each phase is important for those systems having low solubilization ability. For the W-III microemulsions prepared using SDS/OTAC surfactant mixture, the percentage of n-butanol distributed into the interfacial layer decreased while the fraction of n-butanol in the interfacial layer first increased sharply and then tended to be stable with the addition of n-butanol. For the different optimum W-III microemulsion systems tested, most of the surfactant-to-alcohol molar ratio data are near 1:3, but obvious deviation could be observed for some data. On the basis of the accurate measurement of n-butanol content in the EO and EW phases, the standard free energy, ΔG _o→in ^* (T = 298.15 K) of n-butanol transferring from the EO phase to the interfacial region was calculated. The results show negative ΔG _o→in ^* values. For microemulsions with the same components, n-butanol content is an important factor influencing the ΔG _o→in ^* value, and a high absolute value of ΔG _o→in ^* leads to high solubilization ability.     

Photomediated atom transfer radical polymerization of MMA under long-wavelength light irradiation

In this study, a novel photocatalyst, pentarylenebis(dicarboximide) dye: (1,6,13,18-tetra(4-(2,3,3-trimethylbut-2-yl)phenoxy)-N,N’-(2,6-diisopropylphenyl)-pentarylene-3,4,15,16-tetracarboxidiimide) (TTPDPT), was first used in metal-free photoinduced atom transfer radical polymerization (ATRP) of methyl methacrylates (MMA). The initiator was methyl α-bromoisobutyrate (MBI) and the light source was mild near-infrared (NIR) light irradiation (λ_max?≈?870 nm). The TTPDPT-mediated ATRP relies on in situ photoreduction of a MBI through an electron transfer process to generate the desired alkyl radical, which could induce polymerization of the monomer. The photoinduced metal-free ATRP of MMA shows typical characteristics of controlled free radical polymerization, showing the linear evolution of number-average molecular weight (M_n,GPC) with monomer conversion, where polymers with predetermined degree of polymerization have well-controlled molecular weights and narrow molecular weight distribution (M_w/M_n). The photoinduced metal-free ATRP of MMA can be carried out with just ppm level of TTPDPT. The polymerization initiation and propagation can be operated by the aid of pulsed light sequences while NIR light source was used to promote carbon–carbon bond formation and to produce poly(methyl methacrylate) (PMMA) with M_w/M_n as low as 1.5. The synthesized PMMA was characterized by ¹H nuclear magnetic resonance (¹H NMR). The resultant PMMA contained a bromide end group that can be employed to reinitiate styrene polymerization to produce block copolymers through chain extension experiments.