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.     

影响焦炭热态性质的因素探讨

对皖北17种煤样进行了性质分析及40kg小焦炉炼焦试验,结果表明,灰分中的碱性氧化物对焦炭的溶损反应起着正催化作用,其含量越大,焦炭的反应性越大;挥发分含量在20%～24%、镜质组反射率在1.3～1.8之间的煤,焦炭的反应性和反应后强度较好;硫的存在能抑制焦炭的CO2反应性,随着硫含量的增高,焦炭的反应后强度有所提高.建立的预测模型具有一定的可靠性与稳定性.     

炼焦煤中灰分对焦炭热性能的影响

研究了炼焦煤的灰分和催化指数,通过小焦炉实验进行了焦炭的反应性和反应后强度的测定。结果表明,灰分催化指数对焦炭的反应性和反应后强度的影响显著。焦炭的反应性与灰分碱性催化指数呈正线性相关,焦炭的反应后强度与灰分碱性催化指数呈负线性相关。     

An experimental study on strength development of concrete containing fly ash and optimum usage of fly ash in concrete

This paper presents a laboratory study on the strength development of concrete containing fly ash and optimum use of fly ash in concrete. Fly ash was added according to the partial replacement method in mixtures. A total of 28 mixtures with different mix designs were prepared. 4 of them were prepared as control mixtures with 250, 300, 350, and 400 kg/m³ cement content in order to calculate the Bolomey and Feret coefficients (K_B, K_F). Four groups of mixtures were prepared, each group containing six mix designs and using the cement content of one of the control mixture as the base for the mix design. In each group 20% of the cement content of the control mixture was removed, resulting in starting mixtures with 200, 240, 280, and 320 kg/m³ cement content. Fly ash in the amount of approximately 15%, 25%, 33%, 42%, 50%, and 58% of the rest of the cement content was added as partial cement replacement. All specimens were moist cured for 28 and 180 days before compressive strength testing. The efficiency and the maximum content of fly ash that gives the maximum compressive strength were obtained by using Bolomey and Feret strength equations. Hence, the maximum amount of usable fly ash amount with the optimum efficiency was determined.This study showed that strength increases with increasing amount of fly ash up to an optimum value, beyond which strength starts to decrease with further addition of fly ash. The optimum value of fly ash for the four test groups is about 40% of cement. Fly ash/cement ratio is an important factor determining the efficiency of fly ash.     

Studies of relationship between petrography and elemental analysis with grindability for Kentucky coals

The effects of macerals, ash, elemental analysis and moisture of wide range of Kentucky coal samples from calorific value of 23.65-34.68 MJ/kg (10,170-14,910 (BTU/lb)) on Hardgrove Grindability Index (HGI) have been investigated by multivariable regression method. Two sets of input: (a) macerals, ash and moisture (b) macerals, elemental analysis and moisture, were used for the estimation of HGI. The least square mathematical method shows that increase of the TiO₂ and Al₂O₃ contents in coal can decrease HGI. The higher Fe₂O₃ content in coal can result in higher HGI. With the increase of micrinite and exinite contents in coal, the HGI has been decreased and higher vitrinite content in coal results in higher HGI. The multivariable studies have shown that input set of macerals, elemental analysis and moisture in non-linear condition can be achieved an acceptable correlation, R = 90.38%, versus R = 87.34% for the input set of macerals, ash and moisture. It is predicted that elemental analysis of coal can be a better representative of mineral matters for the prediction of HGI than ash.     

Pozzolanic properties of reject fly ash in blended cement pastes

Low-grade fly ash (reject fly ash, r-FA), a significant portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process, has remained unused due to its high carbon content and large particle size. But it may be used in certain areas, such as in solidification and stabilization processes of hazardous waste and materials for road base or subbase construction, which require relatively lower strength and reactivity. It is therefore necessary to extend research on the properties of r-FA and explore its possible applications. This paper presents experimental results of a study on the mechanical and hydration properties of cementitious materials prepared by blending r-FA with ordinary Portland cement (OPC). Parallel mixes were also prepared with the good ash [i.e., classified fine fly ash (f-FA)] for comparison. Selective chemical activators were added to the mix to study the effects of the activators on the properties of the blend system. The results show that r-FA generally has a lower rate of hydration than f-FA particularly at the early stage of hydration. Adding Ca(OH)₂ alone almost had no effect on accelerating the hydration of r-FA. But adding a small quantity of Na₂SO₄ or K₂SO₄ together with Ca(OH)₂ significantly accelerated the hydration reaction. The results of the compressive strength measurement correlated nicely with the degree of hydration results. It was also found that water-to-binder ratio (w/b) was an important factor in affecting the strength development and the hydration degree of r-FA pastes.     

Metamorphism and mineral composition of coal

The influence of ash content on the chemical composition of the ash is considered, along with the dependence of the Fe₂O₃, CaO, MgO, and SiO₂ content in the ash of Kuznetsk and Donetsk coal on the yield of volatiles V ^daf , which characterizes the degree of metamorphism. Correlation analysis shows that this dependence is described by second-order polynomial equations within the ranges considered. Within the interval V ^daf = 20–28% (from the overall range 8 ≤ V ^daf ≤ 45% considered), the content of most oxides in the ash passes through an extremum. The idea that high contents of ore components (Fe₂O₃, CaO, and MgO) in the ash are useful should be revised, since they impair the CSR and CRI values of the coke.     

Effects of flue gas desulphurization sludge on the pozzolanic reaction of reject-fly-ash-blended cement pastes

Reject fly ash (rFA), a coarse portion of the pulverized fuel ash (PFA) produced from coal-fired power plants and rejected from the ash classifying process, has remained unused due to its high carbon content and large particle size (>45 μm). However, the reject ash may have potential uses in chemical stabilization/solidification (S/S) processes that require relatively low strength and low chemical reactivity. Flue gas desulphurization (FGD) sludge is a by-product of the air pollution control process in coal-fired power plants. Its chemical composition is mainly gypsum. As there is no effective usage of both of these materials, it was of interest to conduct research on the possible activation of rFA using FGD. This paper presents experimental results of the effect of FGD on the pozzolanic reaction of rFA-blended cement pastes with or without Ca(OH)₂ and chemical activators. The results show that FGD take effect as an activator only at late curing ages. Adding Ca(OH)₂ activates the hydration of rFA. Chemical activator, such as alkali sulphate, is more effective in enhancing the strength development and degree of hydration of rFA than CaCl₂ in the rFA-Ca(OH)₂-cement system. But CaCl₂ is more effective in the rFA-Ca(OH)₂-FGD-cement system. The chemical activators speed up the reaction of the rFA through the formation new hydration products and elevating the pH value.     

Preparation and properties of rigid polyimide foams derived from dianhydride and isocyanate

A series of rigid polyimide (PI) foams were synthesized via the reaction of a first solution with a second solution. The first solution was isocyanate‐terminated polyimide prepolymers; the second solution contained deionized water and surfactant. The effect of different water contents and isocyanate index on the structures and properties of rigid PI foams were investigated. The apparent density, hardness, compressive strength, and the 5% weight loss temperatures (T_5%) decreased with the increase of water content. With the increase of isocyanate index, the apparent density and the T_5% values decreased, whereas the glass transition temperatures (T_g) increased and the hardness, compressive strength first increased and then decreased. The rigid PI foams composed of closed‐cells were confirmed by scanning electron microscopy. The maximum compressive strength of rigid PI foams prepared was up to 1.31 MPa. Moreover, excellent thermal stability was presented with the T_5% values were all above 360°C and the residual weights of the foams (R_w) were more than 50% at 800°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The variation of structural characteristics of macerals during pyrolysis

Vitrinite and inertinite were separated by DGC from Chinese Shenmu bituminous coal and the structural characteristics of the macerals, before and after pyrolysis, were analyzed by ultimate analysis, FTIR and ¹³C NMR. The results showed that vitrinite chars always had higher H and lower C content than inertinite char at the same pyrolysis temperature. The FTIR and ¹³C NMR indicated that vitrinite had more aliphatic C-H, hydrogen bonding and lower aromaticity. With increasing temperature, the aliphatic C-H decreased, aromatic C-H, aromaticity and H_ar/H_al ratio increased. At the same temperature, inertinite always had higher H_ar/H_al ratio than vitrinite, which is consistent with that inertinite had higher aromaticity than vitrinite. And the H_ar/H_al ratio was also related to the remainder volatile matter. With increasing H_ar/H_al ratio, the remainder volatile matter in vitrinite and inertinite decreased. The higher aromaticity and H_ar/H_al ratio and lower H content of the inertinite in all temperature range were correlated with its higher thermal stability and lower volatile yield than vitrinite.     

Comparative study of the mechanical and flame‐retarding properties of polybutadiene rubber filled with nanoparticles and fly ash

A comparative study was performed of fly ash and nano‐CaCO₃ as fillers in polybutadiene rubber with 0, 4, 8 and 12% fly ash and nano‐CaCO₃. Uniform sheets were prepared of well‐compounded rubber. Nano‐CaCO₃ was synthesized by in situ deposition. The CaCO₃ nanoparticles as reinforcing agents improved the tensile strength more than 50% than fly ash, and the toughness and hardness also increased significantly. Up to a 75% reduction in flammability and a 100% improvement in the tear strength were observed with nano‐CaCO₃.© 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 6–9, 2005     

Influence of coal characteristics on CO2 gasification

The rate of CO₂ gasification of a coke is one of the most important qualities of metallurgical coke. Many workers are trying to estimate the rate of CO₂ gasification of coke by studying properties of coal, such as the reflectance of vitrinite and the amounts of inertinite and ash in coal. The specific-gravity separation method is used to prepare coals which possess almost the same reflectance, but contain different amounts of inertinite and ash. The relation between the rate of gasification and the properties of coal is quantitatively explained.     

Study on the pozzolanic properties of rice husk ash by hydrochloric acid pretreatment

The pozzolanic properties of rice husk ash by hydrochloric acid pretreatment are reported in the paper. Three methods have been used to estimate the pozzolanic activity of rice husk ash. The heat evolution and the hydration heat of cement, the Ca(OH)₂ content in the mortar and the pore size distribution of mortar are determined. It is shown that compare with the rice husk ash heated untreated rice husk, the sensitivity of pozzolanic activity of the rice husk ash heated hydrochloric acid pretreatment rice husk to burning conditions is reduced. The pozzolanic activity of rice husk ash by pretreatment is not only stabilized but also enhanced obviously. The kinetics of reaction of rice husk ash with lime is consistent with diffusion control and can be represented by the Jander diffusion equation. A significant increase in the strength of the rice husk ash (pretreated) specimen is observed. The results of heat evolution indicate that the rice husk ash by pretreatment shows the behavior in the increase of hydration of cement. The cement mortar added with the rice husk ash by pretreatment has lower Ca(OH)₂ content after 7 days and the pore size distribution of the mortar with the rice husk ash with pretreatment shows a tendency to shift towards the smaller pore size.     

Synthesis and characterization of terpolymer of N‐cyclohexylmaleimide,methyl methacrylate,and acrylonitrile

Terpolymers of N‐cyclohexylmaleimide, methylmethacrylate, and acrylonitrile (AN) at different AN feed content were synthesized by suspension polymerization. The thermal properties of the terpolymers such as glass transition temperature (T_g) and Vicat softening temperature (T_Vicat) were determined by torsion braid analysis and Vicat softening temperature tester, respectively. The value of T_g and T_Vicat decreased with increasing AN feed content. Thermogravimetric analyses were carried out with the results that the incorporated AN units enhanced the thermal stability of the resulting polymers and a second degradation step appeared with the addition of AN. The mechanical properties (tensile strength and impact strength) of the terpolymers were also detected and the results show that the tensile strength and impact strength of terpolymers increase with increasing AN feed content. The rheological results illustrated that the terpolymers showed rheological behavior similar to that of pseudoplastic liquid. The apparent shear viscosity decreased with the increasing of AN feed content. The flow power index n increased with increasing AN feed content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 792–796, 2007     

Styrene–butyl acrylate–N,N-dimethyl N-butyl N-methacrylamidino propyl ammonium bromide emulsifier–free emulsion copolymerization

Emulsifier-free emulsion copolymerization of styrene (St) and butyl acrylate (BA) in the presence of cationic functional comonomer N,N-dimethyl N-butyl N-methacrylamidino propyl ammonium bromide (DBMPAB) was carried out using azobis(isobutylamidine hydrochloride) (AIBA) as initiator. The surface properties of particles were studied by testing the actual value of -N⁺ and -C⁺(NH₂)₂ (Publisher's note: for graphical representations please see printed journal or the Acrobat PDF version on this website.) on the surface of particles and the surface charge density. The copolymer particles were characterized by transmission electron microscopy (TEM). The effects of reaction temperature, DBMPAB content, AIBA content, and ionic strength on conversion of monomer, average diameter D _w) and number (N_p) of copolymer particles were investigated. Under constant ionic strength the average diameter of copolymer particles (D_w) decreased with increasing AIBA and DBMPAB concentration, and decreased with rising reaction temperature. At constant concentration of comonomer and initiator and constant monomer composition, D_w showed an increase–decrease–increase with ionic strength plot. The polymerization rate increased with increasing DBMPAB content, AIBA content and rising temperature. The surface charge properties of particles were mainly decided by DBMPAB content, AIBA content, and ionic strength. ©1997 SCI     

70kg模拟焦炉炼焦焦炭转鼓强度分析

简述了70kg模拟焦炉试验情况,通过对焦炭转鼓强度(DI11550)影响因素的分析,得出单种煤的变质程度指标(干燥无灰基挥发分Vdaf或镜质组随机平均反射率Rran)、煤的惰性物含量及黏结指数是影响DI11550的主要因素。通过多参数回归分析,得出了单种煤炼焦焦炭转鼓强度的预测模型。     

Measuring the change in ultrasonic p-wave energy transmitted in fresh mortar with additives to monitor the setting

Research on ultrasonic methods to monitor the setting of concrete has mainly focussed on the wave velocity as a useful quantity. To investigate the application of also the wave energy as a parameter, an experimental program was set up to apply the ultrasonic wave transmission technique on several mortar samples containing air entrainer, blast-furnace slag or fly ash causing clearly different setting behaviour.The increase of the relative energy E/E_ref during setting is generally retarded if ordinary Portland cement is replaced by blast-furnace slag or fly ash. The mixtures with cement of a lower strength class or with large air content were difficult to test with the energy measurements since they were more sensitive to poor sensor contact due to shrinkage. For the other samples, the thresholds E/E_ref = 0.02 and 0.13 are proposed to easily determine respectively initial and final setting based on the ultrasonic energy measurements.     

High Ash Char Gasification in Thermo-Gravimetric Analyzer and Prediction of Gasification Performance Parameters Using Computational Intelligence Formalisms

The coal gasification is a cleaner and more efficient process than the coal combustion. Although high ash coals are commonly utilized in the energy generation, systematic gasification kinetic studies using chars derived from these coals are scarce. Accordingly, this paper reports the development of the data-driven models for the gasification of chars derived from the high ash coals. Specifically, the models predict two important gasification performance parameters, viz. gasification rate constant and reactivity index. These models have been constructed using three computational intelligence (CI) methods, namely genetic programming (GP), multilayer perceptron (MLP) neural network (NN), and support vector regression (SVR). The inputs to the CI-based models consist of seven parameters representing the gasification reaction conditions and properties of high ash coals and chars. The data used in the modeling were collected by performing extensive gasification experiments in the CO₂ atmosphere in a thermo-gravimetric analyzer (TGA) using char samples derived from the Indian coals containing high ash content. Values of the two gasification performance parameters were obtained by fitting the experimental data to the shrinking unreacted core (SUC) model. It has been observed that all the CI-based models possess an excellent prediction accuracy and generalization capability. Accordingly, these models can be gainfully employed in the design and operation of the fixed and fluidized bed gasifiers using high ash coals.     

Improve the strength of concrete-filled steel tubular columns by the use of fly ash

Concrete-filled steel tubular columns (CFTs) are becoming widely used in engineering. In the present paper, the addition of fly ash and an expansive agent to the concrete of CFTs or a thin layer of fly ash to the interface between steel tube and concrete (CFTFCs) to improve the compressive strength and the bond strength of CFTs was experimentally investigated. The results show that the expansive concrete-filled steel tubular columns (CFETs) have the highest bond strength and compressive strength at the age of 7 days, and CFTFCs have higher bond strength and compressive strength than fly ash concrete-filled steel tubular columns (CFFTs), which in turn are higher than CFTs. However, both bond strength and compressive strength of CFTFCs become the highest at the age of 28 days. The morphology (size and shape) of mineralogy and microstructure of the interface at the age of 28 days were also investigated by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). It is shown that the strength improvement of CFTFCs mainly depends on the content of SiO₂ and CaO in the interface, and higher content of SiO₂ and/or lower content of CaO are preferred.     

Geology, geochemistry and biomarker evaluation of Lafia-Obi coal, Benue Trough, Nigeria

Lafia-Obi coals from four boreholes were investigated in this study to ascertain their sedimentological and geochemical characteristics. This data enables the proper evaluation of their oil source rock potential and industrial utilization. The Lafia-Obi area is underlain by rhythmic sequences of shale, sandstone and limestone with varying thicknesses of interbedded coal, inferring deposition under shallow marine conditions. The ash and moisture contents of the coal are high suggesting good potential for use in the steel industry. The relatively low volatiles and high vitrinite/inertinite contents indicate that the coal has an appreciable coking quality. Although the total organic carbon content exceeds the kerogen threshold of 0.5 wt% for generation of crude oil, the high vitrinite reflectance values (R₀>1.0%) and several geochemical maturity indices indicate mature to overmature facies. The bitumen compositions also reflect full maturity. The geological and geochemical characteristics of the Lafia-Obi coals are compared and contrasted with those of Enugu coals, with emphasis on the possible economic applications of the former.