Quality of Some Nigerian Coals as Blending Stock in Metallurgical Coke Production

Two Nigerian coals, Lafia-Obi and Chikila were blended in the mass ratio of 70:30 with imported American and Polish coking coals. Proximate analysis, free swelling index, Ruhr dilatometer and Gieseler plastometer were used in assessing the coking qualities of both the single coals and the blends. The results show that the blends are lower in moisture and ash contents;higher in volatile matter and fixed carbon than the single Nigerian coals. The rheological parameters revealed superiority in thermo-plastic properties of the blends over the unblended local coals. Lafia-Obi/Foreign coals blends possess lower ash and better rheological properties compared to Chikila/Foreign coal composites which have high ash and poor rheological properties. These together suggest that amongst the two Nigerian coals, Lafia-Obi is superior for blending with the foreign ones in metallurgical coke production.

Characterization of bio-coal briquettes blended from low quality coal and biomass waste treated by Garant■bio-activator and its application for fuel combustion

Experimental research was carried out on the manufacturing of bio-coal briquettes from a blend of two different types of low-quality coal and biomass waste in the absence of coal carbonization,where the third blend of the material was fermented by adding a bio-activator solution before pressurizing the components into briquettes.The coal samples from Caringin-Garut Regency(BB-Garut)had a low calorific value and a high sulfur content(6.57 wt%),whereas the coal samples from Bayah-Lebak Regency(BB-Bayah)had a higher calorific value and a lower sulfur content(0.51 wt%).The biomass added to the coal blend is in the form of fermented cow dung(Bio-Kohe),and it had a calorific value of 4192 kcal/kg and a total sulfur content of 1.56 wt%.The main objective of this study is to determine the total decrease in the sulfur content in a blend of coal and biomass in which a fennentation process was carried out using a bio-activator for 24 h.The used bio-activator was made from Garant■(1:40)+molasses 1 wt%/vol,and its used amount was 0.2 L/kg.Also,the total sulfur content in the blend was 1.00 wt%-1.14 wt%,which fulfills the necessary quality requirements for non-carbonized bio-coal briquettes.The pyritic and sulfate content in the raw coal was dominant,and the organic sulfur,when fermented with Garant■,was found to be less in the produced bio-coal briquettes by 38%-58%.

Guidance method to use mixed coal in blending for coking

Based on the principle that the adaptation can be reflected by the overlap of reflectance distribution peaks,the effect of various types mixed coal for coking is analyzed.Based on the action of the vitrinite of different reflectance range and the adaptation,a new method for guidance blending coal is established.Through simulation,blending coal using the software of HD automatic microscope photometer,makes the synthetic blending coal reflectance distribution map to nothing notch wide single peak flat-shaped symmetrical distribution,blending coal random reflectance meets 1.1 - 1.2,the standard deviation meets 0.35 - 0.4.It is based on the conditions that active component in the blending is excessive.Using this method,the mixed coal can be used as much as possible and play a positive role.The problem about implementation process is discussed.

Research progress and prospects of coal petrology and coal quality in China

Clean utilization of coal depends on the quality of raw coal,which depends on the coal-forming parent materials(petrology and chemical composition of coal),the multiple media of the coal-forming environment,and some epigenetic conditions,such as thermal evolution(coalification),magmatic hydrothermal fluid,groundwater.Based on the research results of predecessors and prediction studies of coal resources since the founding of China,the present status of research on coal petrology,coal quality,coal metamorphism,and coal geochemistry in China is discussed in detail,with emphasis on research progress and the general situation of highly efficient and clean utilization of coal in the technical fields of coking,pyrolysis,combustion,gasification,and liquefaction,and the development prospects of coal petrology and coal quality in China are prospected.

Speciation and thermal transformation of sulfur forms in high-sulfur coal and its utilization in coal-blending coking process:A review

The utilization of high-sulfur coal is becoming more urgent due to the excessive utilization of low-sulfur,high-quality coal resources,and sulfur removal from high-sulfur coal is the most important issue.This paper reviews the speciation,forms and distribution of sulfur in coal,the sulfur removal from raw coal,the thermal transformation of sulfur during coal pyrolysis,and the sulfur regulation during coal-blending coking of high organic-sulfur coals.It was suggested that the proper characterization of sulfur in coal cannot be obtained only by either chemical method or instrumental characterization,which raises the need of a combination of current or newly adopted characterization methods.Different from the removal of inorganic sulfur from coal,the organic sulfur can only be partly removed by chemical technologies;and the coal structure and property,particularly high-sulfur coking coals which have caking ability,may be altered and affected by the pretreatment processes.Based on the interactions among the sulfur radicals,sulfur-containing and hydrogen-containing fragments during coal pyrolysis and the reactions with minerals or nascent char,regulating the sulfur transformation behavior in the process of thermal conversion is the most effective way to utilize high organic-sulfur coals in the coke-making industry.An in-situ regulation approach of sulfur transformation during coal-blending coking has been suggested.That is,the high volatile coals with an appropriate releasing temperature range of CH4 overlapping well with that of H2 S from high organic-sulfur coals is blended with high organic-sulfur coals,and the C–S/C–C bonds in some sulfur forms are catalytically broken and immediately hydrogenated by the hydrogencontaining radicals generated from high volatile coals.Wherein,the effect of mass transfer on sulfur regulation during the coking process should be considered for the larger-scale coking tests through optimizing the ratios of different coals in the coal blend.

Influence of coal blending on mineral transformation at high temperatures

Transformation of mineral matter is important for coal utilization at high temperatures.This is especially true for blended coal.XRD and FTIR were employed together to study the transformation of mineral matter at high temperature in blended coals.It was found that the concentration of catalytic minerals, namely iron oxides, increases with an increasing ratio of Shenfu coal, which could improve coal gasification.The transformation characteristics of the minerals in blended coals are not exactly predictable from the blend ratio.This was proved by comparing the iron oxide content to the blending ratio.The results from FTIR are comparable with those from XRD.FTIR is an effective method for examining variation in mineral matter.

Effect of coal moisture content on coke’s quality and yields of products during coal carbonization

The coal with low moisture during carbonization could not only increase the yield of coke,but also promote the coke quality and reduce the energy consumption.In this paper,the influence of the moisture in the blend coal(1.8%10.13%)on the product yields and coke quality during coal carbonization were investigated.The results show that the coke yield is increased from 75.90%to 77.16%,and the coke qualities such as coke strength after reaction with CO2(CSR),coke reactivity index(CRI),fragmentation index(M25)and abrasion index(M10))are also improved when the moisture of the blend coal decreases from 10.13%to 1.80%in a bench scale reactor.Due to the secondary reaction,tar become lighter when the moisture is decreased.In order to further prove the above results,the blend coal with 1.8%and 9%10%(common moisture used in coke plant)moisture is carbonized in a coke oven with 6 m height,the results show that CRI are 23.4%and 27.3%,CRS are 67.1%and 62.2%under 1.8%and 9%10%moisture of blend coal.Moreover,the variation of the moisture in blend coal has a limited influence on dust emission at the ascension pipe and the charging car.

Progress in Researches on Evaluation of Quality of Cultivated Land Consolidated from Coal Mining Subsided Land

The evaluation of consolidated cultivated land quality can provide basic information for how to perfect the program of land consolidation,as well as a reference for the dynamic monitoring of farmland quality in mining area. Based on the consultation and analysis of related literature,we can conclude that: firstly,most scholars focus on soil consolidation,while consider little about land use and economic condition. Secondly,foreign scholars usually use crop yields to judge the success of land consolidation,while domestic scholars have been evaluated the quality of consolidated cultivated land synthetically from several aspects,such as soil fertility,soil environmental quality,and farmland infrastructure conditions. Specifically,most of the evaluations are static,and indicators are different. Besides,the quality of consolidated cultivated land is generally low,and it lacks systematic research on technologies for improving quality of cultivated land consolidated from coal mining subsided land. It is concluded that future researches should focus on establishing scientific and feasible evaluation system to realize comparison of quality change in the dynamic course of " undisturbed-subsided-consolidated" cultivated land in coal mining areas,as well as technologies for improving quality of cultivated land consolidated from coal mining subsided land.

Study on Generation Cost Prediction Based on Coal Quality and Generating Unit Performance

燃料变化条件下发电成本的预测是火电厂普遍关心的重要课题。分析了影响机组性能及发电电量成本的各种煤质指标，重点研究了基于结构参数及燃烧传热机理的锅炉稳态热力性能分析计算方法，讨论了制粉系统、风机、脱硫和脱硝装置性能随燃料等运行条件的变化关系，最终提出了基于煤质和机组性能分析计算的发电电量成本预测模型并研发了“煤炭选配与机组发电成本预测系统”。该系统在我国某600MW火电厂的实际应用经验表明：提出的电量成本分析预测模型合理，研发的软件系统有助于辅助火电厂的选煤和购煤决策，优化动力配煤方案，从而提高火电厂的运行经济性。

Prediction on adsorption ratio of carbon dioxide to methane on coals with multiple linear regression

The multiple linear regression equations for adsorption ratio of CO2/CH4 and its coal quality indexes were built with SPSS software on basis of existing coal quality data and its adsorption amount of CO2 and OH4. The regression equations built were tested with data collected from some s, and the influences of coal quality indexes on adsorption ratio of CO2/CH4 were studied with investigation of regression equations. The study results show that the regression equation for adsorption ratio of CO2/CH4 and volatile matter, ash and moisture in coal can be obtained with multiple linear regression analysis, that the influence of same coal quality index with the degree of metamorphosis or influence of coal quality indexes for same coal rank on adsorption ratio is not consistent.

Improve power quality of coal mine power network based on gray system theory

Unified Power Quality Controller（UPQC） was proposed to comprehensively improve power quality of coal mine power network and its basic structure and operation principle was introduced. In order to overcome time lag of Active Power Filter（APF） in compensating harmonic and reactive current, a novel method based on gray system theory was proposed to predict harmonic current and other distortion component. The mathematical model of component to be compensated was constructed by data sequence of distortion component, which could exactly forecast compensation signal of next period. The optimal control strategy was selected according to the principle of output signal approaching component to be compensated as near as possible. Before predicating each time the oldest data was eliminated while the latest data was added to data sequence. Then new predication model was established once again. The results show that the method can always construct mathematical model with variation of system parameters, reflect the latest state of system and not increase calculation quantity. The feasible and effective control strategy can improve power quality of coal mine power network.

The Technical Analysis on Upgrade and Coupling of Low-Quality Coal

Experimental study was conducted with regard to upgrading low-quality coal by low temperature pyrolysis technology and fluidization classification technology, which laid the theoretical foundation for research and development of low-quality coal upgrading process. Firstly, a pyrolysis pilot experiment of long-flame coal was performed and the optimum pyrolysis conditions were found. When the final pyrolysis temperature was 450?C and the residence time was 10 minutes, the content of semicoke volatile dry ash-free was about 22.89% and the content of semicoke ash was about 16.1%. More than 5% of the ash needs to be removed before entering the pyrolysis fluidized bed. Thus, classification tests were carried out to pick out the coal particles with the target size of 500 μm, using a gas-solid fluidized bed coal picker. It was found that the separating effect of coal particles was the most satisfactory when the inlet velocity at the bottom was 3.27 m/s. The percentage of particles with diameters less than 500 μm was as low as 28.7% in the coarse samples. Based on the test results, a novel process of low-quality coal upgrade and coupling was proposed, which realized the sorting, grading, drying and pyrolysis of low-quality coal through the multi-stage fluidized bed integrated process.

Practice of the application of lean coal to coal injection in large-scale blast furnaces

This study mainly introduces the technical properties of a kind of lean coal mined from Lu＇ an, a prefecture of Shanxi Province and its application to coal injection in large-scale blast furnaces（BFs） in Baosteel. China is rich in lean coal resources. The technical properties of lean coal, including ash content, sulfur content and caloricity, etc., are similar to those of anthracite coal used in Baosteel, except the fact that the volatile of lean coal is higher. Besides, the explosive property and the coking property of lean coal are suitable for the BF coal injection. In this study, lean coal was tested in the pulverized coal injection （PCI） of a BF. In the test, the blending proportion of lean coal in the coal blend was increased gradually, and the consequential production indexes were traced. All the operational indexes show that the results of the BF coal injection are good, demonstrating that lean coal can be substituted for anthracite coal in the PCI in BFs. With an abundant amount and specific utilization,lean coal is found to be of a high economic value.

A New Distinguish Method of Blending Coals Slagging Characteristic

The slagging characteristic of coal effects the safe operation of boiler unit directly, the study on coal slagging is paid more and more attention by scholars of the world. Because of the complexity of coal characteristic, the blending coals slagging characteristic is more complex than single coal. The study method of blending coals characteristic is the same as the single coal method, but the simple method can’t distinguish the blending coals slagging characteristic well and truly. This paper gives the new distinguish method of blending coals slagging characteristic based on experimentation condition, it is the rate of slag and furnace refuse. The rate of slagging on furnace wall and the refuse on furnace bottom has utilized to distinguish the slagging characteristic of coal. The result shows that the rate of slag and furnace refuse method has better veracity.

COMPARING STUDY OF BLENDING PREHEATING MODIFIED COAL COKING AND STAMPING COKING FOR DONGSHEN COAL

The compaison of the properties of coke of three coking methods is introduced. The mechanical properties and high temperature reactivity of coke bleding preheating modified Dongshen coal are improved obviously than those of normal coke, and achieve or exceed that of stamping coke. This method shows more ability of expending coking coal resources.

Study on mathematical model of steam coal blending

It is necessary to set up a new mathematical model of steam coal blending instead of the old model. Indexes such as moisture content, ash content, volatile matter, sulfur content and heating value in the new mathematical model have linear relation. The new mathematical model can also predict ash-fusion temperature precisely by considering coal ash ratio in steam coal blending, therefore it is possible to obtain linear relation of ash-fusion temperature between single coal and steam coal blending. The new mathematical model can improve precision of steam coal blending and perfect the old mathematical model of steam coal blending.

Effects of Vetiveria zizanioides Planting on Water Quality in Areas Surrounding Coal Gangue Mountain

In order to investigate the correlation between the variations in the environmental water quality indexes and the distance of water bodies from the planting region of vetiver, samples of surface water were gathered from the water bodies surrounding an abandoned coal gangue mountain of Dahead coal mine (Dahe, Liupanshui, Guizhou Province) based on the method of field survey and typical analysis. According to the results, the planting of vetiver could effectively purify the water bodies surrounding the coal gangue mountain. Detailed findings include three aspects:(1) The main pollutants detected in water bodies around the coal gangue mountain were SO4 2-, NO3 -, Fe and Cu, with a concentration of 869.45, 35.16, 26.06, and 40.85 mg/L respectively in wet season and all exceeded the national environmental standards for surface water.(2) The pH values of water bodies 150~200 m away from the vetiver planting region stayed within the limits of national environmental standards for surface water and presented a homogeneous feature, revealing that vetiver has the capacity to adjust the pH of the surrounding water body.(3) The contents of Fe, Mn, Cu, SO4 2-, and NO3 - under all treatments, tended to increase with the increasing distance of water bodies from the vetiver planting region;it means the shorter the distance between the water body and the vetiver planting region is, the higher the adsorption rate and purification effects will be;the optimal concentrations of Fe, Mn, and Cu were 0 mg/L, much lower than the national environmental standards for surface water.

THE OPTIMUM MODEL AND ITS DECISION SUPPORT SYSTEM OF COAL QUALITY BALANCE

The meaning and significance of coal quality balance are summaized in this paper.Practical steps concerning constructing the synthetic tech-economic model and its decision support system of coal quality balance using the optimization techology of inverse recurrence of established initializing parameters are also introduced. The principles and methods as being applied in the model system development and procedure construction are discussed accordingly.

COAL QUALITY CONTROL

Coal storing and loading have much more influence on coal quality. In the paper, a goal programming model has been constructed to determine the ideal quantity extracting from stockpile and silos and a quality control model is inferred under the guidance of maximum theory of dispersed number and practice methods are given to meet production demand, with which a coal mine has achieved a better tech-economic result.