Process engineering of demineralisation of moderate to high ash Indian coals through NaOH‑HCl leaching and HF leaching

Chemical leaching of coals would be required to produce cleaner coals for some special applications where physical benefi-ciation may not be effective enough.This would also help in recovering Li and rare earth metals besides in the sequestration of CO_(2).About 20 Indian coals having complexly distributed moderate to high ash contents were sequentially treated with various alkali–acid such as NaOH-HCl,HF,HCl,HCl-HF,and NaOH-HCl-HF leaching.This aimed to establish and design the best stepwise sequential process for the highest degree of demineralisation through a chemical leaching process.Kinetics and process intensification studies were carried out.More than 80%demineralisation of Madhaipur and Neemcha coals was observed using the best sequential treatment designed presently.The repeated stepwise treatment of the alkali and the acid was also studied,which was found to significantly enhance the degree of demineralisation of coals.The integrated process of alkali–acid leaching followed by solvent extraction(Organo-refining)and vice versa of the treated coal was also studied for producing cleaner coals.

Vibration analysis of axisymmetric functionally graded viscothermoelastic spheres

The present study focuses on the analysis of free vibrations of axisymmetric functionally graded hollow spheres. The material is assumed to be graded in radial di- rection with a simple power law. Matrix Frrbenious method of extended power series is employed to derive the analytical solutions for displacement, temperature, and stresses. The dispersion relations for the existence of various types of pos- sible modes of vibrations in the considered hollow sphere are derived in a compact form. In order to explore the character- istics of vibrations, the secular equations are further solved by using fixed point iteration numerical technique with the help of MATLAB software. The numerical results have been presented graphically for polymethyl methecrylate materials in respect of natural frequencies, frequency shift, inverse quality factor, displacement, temperature change, and radial stress.

Bio-amelioration of alkali soils through agroforestry systems in central Indo-Gangetic plains of India

A long-term field study was initiated during 1995 at Central Soil Salinity Research Institute, Regional Research Station, Lucknow （26047＇58＂ N and 80°46＇24＂ E） to analyze the effect of agroforestry systems on amelioration of alkali soils. Three agroforestry systems （pas- toral, silvipastoral and silvicultural） were compared with the control where no agroforestry system was introduced. Tree-based silvicultural and silvipastoral systems were characterized by tree species Prosopis juliflora and Acacia nilotica along with grass species Leptochloafusca, Panicum maximum, Trifolium alexandrium and Chloris gayana. Growth of ten-year-old Prosopis juliflora and Acacia nilotica planted in combi- nation with grasses was significantly higher over the silviculture system with the same species. Tree biomass yields of P. juliflora （77.20 t·ha-1） and A. nilotica （63.20 t·ha-1） planted under silvipastoral system were significantly higher than the sole plantation of （64.50 t·ha-1 and 52.75 t·ha-1）. Fodder yield under the pastoral system was significantly higher than the silvipastoral system during initial years but it was at par with that of silvipastoral systems after eight years of plantation. The microbial biomass carbon in the soils of silvipastoral systems was significantly higher than in soils under sole plantation of trees and control systems. The Prosopis-based silvipastoral system proved more effective in reduc- ing soil pH, displacing Na＋ from the exchange complex, increasing or- ganic carbon and available N, P and K. Improvement in soil physical properties such as bulk density, porosity, soil moisture and infiltration rate was higher in the Prosopis-based silvipastoral system than in the silviculture system or control On the basis of biomass production and improvement in soil health due to tree ＋ grass systems, silvipastoral agroforestry system could be adopted for sustainable reclamation ofhighly alkali soils.

Design of experiments to optimize the extraction parameters of a power grade Indian coal

Low grade high ash coals with difficult physical washability characteristics require chemical cleaning techniques such as solvent extractio n to obtain super clean coal with lower ash conte nts.Kedla,an In di an low grade coal has ash con tent around 44%-50%and there is a need to maximize its solvent extraction yield so as to make this power grade coal industrially useful.This paper highlights the use of definitive screening design and response surface methodology to extract the maximum organic matter from Kedla coal using ethylenediannnine(EDA)and N-methyl pyrollidone(NMP)as solvents under mild atmospheric pressure conditions.The coal was pre-treated with acetic acid before extractions were carried out.The parameters such as the acid pre-treatment time,acid concenmion,particle size,the co-solvent concentratio n and the solvent concentration were optimized in this paper.With this design of experimenls technique about 40%of the organic matter with minimal ash(less than 2%)content was「endered extractable unlike the already postulated designer solvent system—e,N system(i.e.NMP containing small amount of EDA)that uses coal to solve nt ratio as 1:17(wt/vol)and coal to co-solvent ratio as 1:l(wt/vol)thus only giving 19%extraction yield.Therefore,the present design of experimetechnique helps in conserving the number of experimems for process intensification.

Fractionation of coal through organo-separative refining for enhancing its potential for the CO2-gasification

Coal gasification has already been extensively studied earlier under varying conditions of steam,CO2,O2,inert conditions.Belbaid coal and its e,N and NMP-DETA SCC products recovered through organo-refining under milder ambient pressure conditions were subjected to CO2-gasification in a fixed bed reactor under varying conditions.CO2 being an inert gas becomes the most challenging to be utilized during the gasification process.The SCCs showed better CO2-gasification reactivity than the raw Belbaid coal at 900°C.The use of the catalyst K2CO3 tremendously increased the gasification reactivity for both raw coal and the SCCs.The use of sugarcane bagasse for CO2-gasification along with raw coal as well as with residual coal was also studied.Gasification under CO2 atmosphere conditions was used to structurally understand the coals as the coal structure gets loosened after extraction.

Biomass and bio-energy production of ten multipurpose tree species planted in sodic soils of indo-gangetic plains

Ten multipurpose tree species, Terminalia arjuna, Azadirechta indica, Prosopis juliflora, Pongamia pinnata, Casuarina equisetifolia, Prosopis alba, Acacia nilotica, Eucalyptus tereticornis, Pithecellobium dulce and Cassia siamea, were raised in a monoculture tree cropping system on the sodic soil of Gangetic alluvium in north India （26° 47° N： 80°46′ E） for 10 years to evaluate the biomass and bio-energy production. The soil was compact, sodic and impervious to water associated with nutrient deficiency or toxicity. Maximum plant height was recorded with E. tereticornis followed by C.equisetifolia and P. juliflora. A. nilotica performed better than the other species in terms of diameter at breast height （DBH） with a basal area of 13.04 m^2·ha^-1, followed by P. juliflora and C. equisetifolia. P. juliflora and A. nilotica produced nearly similar biomass of 56.50 and 50.75 Mg·ha^-1, respectively, at 10 years; whereas, A. indica, P. pinnata, C. siamea and P. alba did not perform well. P. juliflora scored maximum in net biomass production and nutrient demand. Nutrient （N, P, K, Ca, and Mg） concentrations were higher in leaf component of P. juliflora. However, in woody components, there was little variation between the species. N removal for production of one ton of wood was lowest in Acacia nilotica, P in T. arjuna, K in P. dulce and Ca and Mg in P. juliflora. P. juliflora gave the highest energy production of 1267.75 GJ.ha^-1 followed by A. nilotica with 1206 GJ.ha^-1 and the lowest ofA. indica （520.66 GJ.ha^-1）.

芒果育种

目前栽培的芒果品种均来源于古代优良的机遇实生苗。因此,很多品种虽然在采一方面较好,但常缺乏诸如早熟、矮化、丰产、稳产等优良性状。至今通过育种方法培育新品种的努力成就甚微。其原因主要有:(1)在芒果这个具有高度杂合性的作物上进行品种间杂交时没有很好地选择亲本;(2)杂交技术效率低,不能提供充足的杂种群体供选择;(3)缺乏有关芒果遗传模式的知识;(4)没有早期选择的指标,以致不能及早鉴定那些有希望的杂种苗;(5)最主要的是缺乏连续的育种工作。近25年来,通过有计划的杂交育种,解决了不少这类问题,加速了品种选育进程。此外,诱变育种也取得了一定的经验。这些成就将有助于培育果实品质很好而矮生型的品种,这样就可通过密植而能更有效地利用日益减少的土地资源。