Pyrolysis and co-pyrolysis of lignite and plastic

The study firstly discusses the pyrolysis characteristics and kinetics by thermogravimetric analysis （TGA）, and then investigates the pyrolysis of lignite and co-pyrolysis with plastic （polyethylene or polypropyl- ene） in tube furnace. Meanwhile, the research focuses on the co-pyrolysis products under different mix- ing ratios as well as pyrolysis products at different testing temperatures and heating rates. The results show that higher final testing temperature and lower heating rate contribute to bond fission in lignite pyrolysis, resulting in less char product. In co-pyrolysis, lignite acts as hydrogen donor, and the yields of char and water rise with increasing amount of plastic in the mixture, while the yields of gas and tar decrease; and a little admixture of plastic will promote the production of gas and tar. Kinetic studies indi- cate that in temperature range of 530-600℃, activation energies of lignite are higher than those of lig- nite/plastic blends, and as plastic mass ratio increases from 0% to 10%, samples need less energy to be decomposed during co-pyrolysis.

Optimization of transport passage with dragline system in thick overburden open pit mine

According to the characteristics of opencast coal resources and dragline technology system application in China,the structure and shifting step of transport passage are optimized in this paper.Typical coal transport passage is analyzed in aspects such as the internal dump occupation,dragline operation efficiency,coal transport distance,upper stripping distance and shifting quantities.The middle passage should be given priority in thick overburden open pit mine because the dragline system is only responsible for part stripping task.According to characteristics of middle passage,the transport passage is divided into parallel climbing,vertical climbing and horizontal transport.In addition,the transport passage structure optimization model and shifting distance optimization model are established in this paper.The case study in Heidaigou open pit mine shows that,the parallel climbing height is accounted for about 60%of the total height,and reasonable shifting distances of the first mining area and the second mining area are 240 and 320 m.Sensitivity analysis shows that,the total passage height has important influence on the shifting step,so it is with the stripping height and passage construction cost to the passage structure.

Characteristics of atmospheric volatile organic compounds in urban area of Beijing: Variations, photochemical reactivity and source apportionment

Atmospheric volatile organic compounds(VOCs)were observed by an on-line gas chromatography-flame ionization detector monitoring system from November 2016 to August 2017 in Beijing.The average concentrations were winter(40.27±25.25μg/m3)>autumn(34.25±19.90μg/m3)>summer(32.53±17.39μg/m3)>spring(24.72±17.22μg/m3).Although benzene(15.70%),propane(11.02%),ethane(9.32%)and n-butane(6.77%)were the most abundant species,ethylene(14.07%)and propene(11.20%)were the key reactive species to ozone formation potential(OFP),and benzene,toluene,ethylbenzene,mxylene+p-xylene and o-xylene(54.13%)were the most reactive species to secondary organic aerosol formation potential(SOAFP).The diurnal and seasonal variations indicated that diesel vehicle emission during early morning,gasoline vehicle emission at the traffic rush hours and coal burning during the heating period might be important sources.Five major sources were further identified by positive matrix factorization(PMF).The vehicle exhaust(gasoline exhaust and diesel exhaust)was found to be contributed most to atmospheric VOCs,with 43.59%,41.91%,50.45%and 43.91%,respectively in spring,summer,autumn and winter;while solvent usage contributed least,with 11.10%,7.13%,14.00%and 19.87%,respectively.Biogenic emission sources(13.11%)were only identified in summer.However,both vehicle exhaust and solvent usage were identified to be the key sources considering contributions to the OFP and SOAFP.Besides,the contributions of combustion during heating period and gasoline evaporation source during warm seasons to OFP and SOAFP should not be overlooked.