The present status and the history of chlor alkali industry using mercury as cathode in China has been studied. Quantitative mercury emission has been estimated. At present, 17.5%—20% of the consumed mercury is re...The present status and the history of chlor alkali industry using mercury as cathode in China has been studied. Quantitative mercury emission has been estimated. At present, 17.5%—20% of the consumed mercury is released into water, 49.1%—53.3% of the Hg is discharged to the brine system outside the plants. 10%—14% of the Hg is emitted directly to the atmosphere, 5 3%—6 7% enters waste materials. The chlor alkali industry in China discharged about 17 tons every year. The total amount of mercury released by the chlor alkali industry in China is estimated to be 1400—2700 tons since 50's. With the result of improved technology and more strict environmental regulations started in late 1970's, chlorine plants reduced their mercury loss factor from 0 5? ? 4 kg/t NaOH before 1977 to 0.16—0.18 kg/t NaOH in 1997. The number of mercury cells in alkali plants was also reduced. In 1998, China is planning to finish the history of producing chlorine and caustic soda using the mercury cell process in the near future. How to deal with the emitted mercury will remain a main problem.展开更多
The dielectric performance of alkali activated slag （AAS） cement paste was investigated in the frequency range of 1 to 1000 MHz. The experimental results showed the unstable dielectric properties of harden paste wer...The dielectric performance of alkali activated slag （AAS） cement paste was investigated in the frequency range of 1 to 1000 MHz. The experimental results showed the unstable dielectric properties of harden paste were mostly influenced by the fraction of free water in paste or absorbed water from ambient, but not including hydration water and microstructure. The free water was completely eliminated by heat treatment at 105 ℃ about 4 hours, and then its dielectric loss was depressed; but with the exposure time in air increasing, the free water adsorption in ambient air made the dielectric property of harden cement paste to be bad. The temperature and relative humidity of environment was the key factors of free water adsorption; hence, if the influence of free water on dielectric constant was measured or eliminated, the cement-based materials may be applied in humidity sensitive materials or dielectric materials domains.展开更多
A new glass system （Bi2O3）50（Fe2O3）10（Li2O）x（K2O）40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect （MAE） phenomen...A new glass system （Bi2O3）50（Fe2O3）10（Li2O）x（K2O）40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect （MAE） phenomena. Measurements of ac conductivity σac, dielectric permittivity ε′ and loss factor tanδ in the frequency range of 0.12～10^2 kHz and in the temperature range of 300～650 K were carried out. The temperature dependence of the ac conductivity shows a slow increasing rate at low temperature and high frequency and a rapid increase at high temperature and low frequency. At constant temperature, the ac conductivity is found to be proportional to ω^8, where s is the frequency exponent, which is less than 1. Analysis of the conductivity data and the frequency exponent shows that the overlapping large polaron tunnelling （OLPT） model of ions is the most favorable mechanism for the ac conduction in the present glass system. The ac response, the dc conductivity and dielectric relaxation have the same activation energy and they originate from the same basic transport mechanism. The results of the dielectric permittivity show no maximum peak in the temperature and frequency range studied. This absence of maximum peak is an indication of non-ferroelectric behavior of all the studied samples. The MAE has been detected in the ac conductivity, which is the same as the classical MAE in the dc conductivity. The electrical parameters such as dielectric permittivity ε′ and real dielectric modulus M′ show a typical minimum deviation from linearity by about two orders of magnitude. The loss factor tanδ and the imaginary dielectric modulus M″ are insignificantly dependent on composition even at the same transition temperature Tg.展开更多
文摘The present status and the history of chlor alkali industry using mercury as cathode in China has been studied. Quantitative mercury emission has been estimated. At present, 17.5%—20% of the consumed mercury is released into water, 49.1%—53.3% of the Hg is discharged to the brine system outside the plants. 10%—14% of the Hg is emitted directly to the atmosphere, 5 3%—6 7% enters waste materials. The chlor alkali industry in China discharged about 17 tons every year. The total amount of mercury released by the chlor alkali industry in China is estimated to be 1400—2700 tons since 50's. With the result of improved technology and more strict environmental regulations started in late 1970's, chlorine plants reduced their mercury loss factor from 0 5? ? 4 kg/t NaOH before 1977 to 0.16—0.18 kg/t NaOH in 1997. The number of mercury cells in alkali plants was also reduced. In 1998, China is planning to finish the history of producing chlorine and caustic soda using the mercury cell process in the near future. How to deal with the emitted mercury will remain a main problem.
文摘The dielectric performance of alkali activated slag （AAS） cement paste was investigated in the frequency range of 1 to 1000 MHz. The experimental results showed the unstable dielectric properties of harden paste were mostly influenced by the fraction of free water in paste or absorbed water from ambient, but not including hydration water and microstructure. The free water was completely eliminated by heat treatment at 105 ℃ about 4 hours, and then its dielectric loss was depressed; but with the exposure time in air increasing, the free water adsorption in ambient air made the dielectric property of harden cement paste to be bad. The temperature and relative humidity of environment was the key factors of free water adsorption; hence, if the influence of free water on dielectric constant was measured or eliminated, the cement-based materials may be applied in humidity sensitive materials or dielectric materials domains.
文摘A new glass system （Bi2O3）50（Fe2O3）10（Li2O）x（K2O）40-x, where x changes in steps of 5 mole fraction between 0 and 40, was selected to study the electrical relaxation and the mixed alkali effect （MAE） phenomena. Measurements of ac conductivity σac, dielectric permittivity ε′ and loss factor tanδ in the frequency range of 0.12～10^2 kHz and in the temperature range of 300～650 K were carried out. The temperature dependence of the ac conductivity shows a slow increasing rate at low temperature and high frequency and a rapid increase at high temperature and low frequency. At constant temperature, the ac conductivity is found to be proportional to ω^8, where s is the frequency exponent, which is less than 1. Analysis of the conductivity data and the frequency exponent shows that the overlapping large polaron tunnelling （OLPT） model of ions is the most favorable mechanism for the ac conduction in the present glass system. The ac response, the dc conductivity and dielectric relaxation have the same activation energy and they originate from the same basic transport mechanism. The results of the dielectric permittivity show no maximum peak in the temperature and frequency range studied. This absence of maximum peak is an indication of non-ferroelectric behavior of all the studied samples. The MAE has been detected in the ac conductivity, which is the same as the classical MAE in the dc conductivity. The electrical parameters such as dielectric permittivity ε′ and real dielectric modulus M′ show a typical minimum deviation from linearity by about two orders of magnitude. The loss factor tanδ and the imaginary dielectric modulus M″ are insignificantly dependent on composition even at the same transition temperature Tg.
