大连市科学技能局 辽阳市知识产权局

A new-type building material Xinke mortar is put into production in
Zhuanghe, a county-level city under Dalian. As the developer Liu Zhenguo
explained, the new – type mortar with coal fly ash as main raw material
is a new generation of all conventional mortars , lime, coal fly ash and
calcium carbide powder. The new product, making full use of industrial
slag is toxin-free ,odour-free ,environmental friendly and
energy-saving, thus reducing pollution.(Dalian Daily p.B2.May 24,2002.)

Because significant volumes of earth must be displaced to mine coal,
coalmines and the resulting rock waste [2] can harm the environment.
Furthermore, burning coal releases environmentally harmful chemical
compounds into the air.

报告题目:The potential of microwave curing for manufacturing low-carbon
concrete报 告
人:伦敦大学学院白云教授报告时间:2018年11月9日14:30报告地点:材料科学与工程学院14号楼205会议室欢迎广大师生踊跃参加!材料科学与工程学院2018年11月7日报告人简介:Professor
Yun Bai is Chair in Construction Materials in the Department of Civil,
Environmental & Geomatic Engineering (CEGE) at University College London
(UCL). He is also Head of the Advanced and Innovative Materials (AIM)
Group, Deputy Head of Civil Engineering Section and Co-Director of
UCL-UDM Advanced Infrastructure Research Centre (UUAIR). With over £8
Million funding and some 150 journal and conference publications,
Professor Bai has developed a research center in central London to
promote industry-driven and interdisciplinary research in material
science and engineering in order to provide leading edge sustainable
solutions to the challenges facing engineers in todays changing society
and environment. The current research themes covered by his research
group include: novel low-carbon cementitious materials, advanced
composite materials, rheology of novel cement and concrete, durability
of concrete structures, structural health monitoring and nuclear waste
immobilisation. In addition, with more than £1.5 Million funding
received over the past 10 years from EPSRC, The Royal Academy of
Engineering, Royal Society and British Council (including the most
prestigious £1.09 Million EPSRC UK-China Bridge in Sustainable Energy
and Built Environment EP/G042594/1), Professor Bai has established
extensive collaborations with both leading academia and industry in
China. Professor Bai is a Fellow of The Higher Education Academy (FHEA),
Fellow of The Institute of Concrete Technology (FICT) and Fellow of The
Institute of Materials, Minerals and Mining (FIMMM). 报告摘要:Steam
curing is widely adopted by construction industry to facilitate the
development of early strength of concrete. Although it can shorten the
curing duration and provide economic benefits, it may lead to thermal
stress inside the large or thick concrete products due to non-uniform
heating. Moreover, it is not environmentally friendly due to its high
energy consumption. Different from steam curing which is dependent on
thermal conduction, microwave heating relies on energy conversion, which
can result in fast volumetric heating. All the components of concrete
are dielectric materials, particularly water. They can absorb microwave
effectively and electromagnetic energy can thus be converted into
thermal energy. Hence, attempts have been made to apply microwave curing
in the manufacture of cement and concrete products since 1980s. Although
some pilot studies have proved that microwave curing could be a
promising alternative accelerated curing method for the production of
precast concrete with shorter curing duration and lower energy
consumption, neither curing temperature nor relative humidity was well
controlled during microwave curing process in these previous works,
which may cause long-term strength loss and durability issues. In this
paper, ongoing research on developing a smart microwave system for
manufacturing concrete products is introduced. The key features of this
microwave system include using optical fibre Bragg grating (FBG) sensors
to control the temperature and the humidity inside concrete and
microwave oven cavity, respectively. Using this tailored-made microwave
system, research is ongoing in the Advanced and Innovative Materials
(AIM) Group at University College London to explore the potential of
curing two types of low-carbon cementitious systems, namely high-volume
fly ash (HVFA) and alkali-activated fly ash (AAFA). In both systems,
thermal curing is essential for the strength development, in particular,
early-age strength development. The results indicated that even with 55%
of Portland cement (PC) replaced by fly ash, the compressive strength of
HVFA concrete can achieve 20MPa after only 8-hours microwave curing. In
the case of AAFA system where 100% fly ash is activated by NaOH without
using PC, a 42MPa compressive strength can be reached within 6 hours
microwave curing, which compared to the similar compressive strength
achieved after 24 hours thermal oven curing at 85oC, representing an
18-hour reduction of curing duration and 73% saving of energy
consumption. Based on the results obtained so far, the potential of this
innovative microwave curing technique for future precast concrete
manufacture is then discussed. 附件:无

15-1 Mining and Mining Waste

Surface mining has resulted in a great deal of damage to the landscape
[3]. Many surface mines have removed acres of vegetation and altered
topographic features [4], such as hills and valleys, leaving soil
exposed for erosion. Longwall mining, which allows the mine to collapse,
results in widespread land subsidence [5], or sinking. Coal and rock
waste, often dumped indiscriminately [6] during surface and
underground mining processes, weathers rapidly, producing acid drainage
[7]. Acid drainage contains sulfur-bearing compounds [8] that
combine with oxygen in water vapor to form sulfuric acid. In addition,
weathering of coalmine waste can produce alkaline compounds [8], heavy
metals [9], and sediments. Acid drainage, alkaline compounds, heavy
metals, and sediment leached from mine waste into groundwater [10] or
washed away by rainwater can pollute [11] streams, rivers, and lakes.

Today, enterprises in many countries must secure government permits
before mining for coal. In the United States, mining companies must
submit plans detailing proposed methods for blasting, road construction,
land reclamation [12], and waste disposal [13]. New land reclamation
methods, driven by stringent [14] laws and regulations, require coal
mining companies to restore strip-mined landscapes to nearly premined
conditions.

15-2 Burning Coal

The burning of coal produces environmentally harmful emissions. Some
gases produced from burning coal, such as carbon dioxide, are known as
greenhouse gases [15] because they trap the Earth’s heat like the roof
of a greenhouse and may contribute to global warming [16]. Other
emissions from coal combustion [17] can lead to air and water
pollution.

A. Greenhouse Effect [18]

Earth absorbs much of the heat energy radiated from the Sun. The planet
then reradiates this heat back into the atmosphere. Carbon dioxide and
some other gases that are naturally present in the atmosphere prevent
much of the heat from escaping back into space, maintaining Earth at a
temperature that can support life. These gases are known as greenhouse
gases because they trap the Sun’s heat in much the same way as the glass
roof of a botanical greenhouse [19]. However, the immense quantity of
fossil fuels burned during the world’s rapid industrialization [20]
over the last 200 years has raised levels of carbon dioxide in the
atmosphere by about 28 percent. This dramatic increase in atmospheric
carbon dioxide, coupled with continuing depletion [21] of the world’s
forests, which absorb carbon dioxide, has led many scientists to predict
a heating of the atmosphere on a global scale. Such a global warming
could disrupt [22] weather patterns, cause

the polar ice caps [23] to melt, and possibly lead to other
environmental problems.

Today, many industrial countries are working to reduce emissions of
greenhouse gases. One proposal is to establish a system requiring
companies that create greenhouse gases to pay to emit carbon dioxide
above a specified level. This payment could take several forms,
including purchasing the rights to pollute from a company with carbon
dioxide emissions below the specified level; purchasing forests, which
absorb carbon dioxide, and keeping them from being developed; or paying
to upgrade a plant in a developing country, thus lowering that plant’s
carbon dioxide emissions.

B. Acid Rain [24]

Another environmental problem is acid rain, which forms from sulfur
contained in coal. As coal burns, the sulfur combines with oxygen in the
air to form sulfur dioxide. As sulfur dioxide is released into the
atmosphere, this compound reacts with atmospheric moisture [25],
forming sulfuric acid. This acidic moisture eventually falls back to
Earth in the form of precipitation [26] known as acid rain.
Environmental studies indicate that acid rain damages crops and forests
as well as streams, lakes, and rivers.

The U.S. Clean Air Act, implemented in 1970 and revised in 1970 and
1990, is the federal law regulating air pollution in the United States.
This legislation has significantly reduced emissions of sulfur oxides,
known as acid gases. For example, the Clean Air Act requires facilities
such as coal-burning power plants to burn low-sulfur coal. High-grade
coals (coals with a higher heating value) generally contain more sulfur
than low-grade coals such as lignite and subbituminous coal. Therefore,
certain processes have been developed to remove sulfur-bearing compounds
from high-grade coal prior to burning. The Clean Air Act also requires
use of pollution-trapping equipment such as air scrubbers [27]
(devices installed inside plant smokestacks [28] to remove sulfur
dioxide from coal emissions). In addition, revisions to the Clean Air
Act in 1990 established a system that allows coal-burning power plants
to buy and sell sulfur emission permits with one another. This system
tries to establish a financial incentive [29] to lower sulfur
emissions by rewarding [30] power plants that reduce emissions below
federal levels. Power plants that cut their sulfur emissions below the
permitted levels can sell permits to burn coal to companies that exceed
federal levels. Companies that reduce emissions reap financial rewards
while polluters must pay an extra cost to pollute.

C. Fly Ash [31]

The burning of coal releases ashes known as fly ash into the atmosphere.
Fly ash contains toxic metals [32] such as arsenic [33] and cadmium
[34]. In the United States the Clean Air Act requires that fly ash be
removed from coal emissions. As a result, antipollution devices such as
air scrubbers, baghouses [35], and electrostatic precipitators are use

d to trap these pollutants. Baghouses work like giant vacuum cleaners,
drawing coal emissions through giant fabric bags that trap the fly ash
inside. Electrostatic precipitators [36] use discharge electrodes
[37] (electrically charged parts of an electric circuit) to trap ash
particles. In an electrostatic precipitator the electrodes are located
between long, positively charged collection plates. As the fly ash
passes between these collection plates, the discharge electrodes give
each particle a negative charge. These negatively charged particles are
then attracted to and held by the positively charged collection plates.

15-3 Clean Coal Technology [38]

Since 1986 the United States government and private industry have been
working together to develop cleaner and more efficient ways to harness
the energy in coal. This joint effort, known as the Clean Coal
Technology Demonstration Program, includes several technologies, such as
fluidized bed coal combustion [39], furnace sorbent injection [40],
and advanced flue-gas desulfurization [41].

Fluidized bed coal combustion burns coal in a limestone bed that
transfers heat to water, generating steam. This steam is pressurized and
used to turn a turbine shaft, which subsequently drives an electric
generator. The limestone absorbs sulfur dioxide emitted by the coal,
thus reducing the amount of acid gases released during combustion.

A process called furnace sorbent injection removes acid gas from coal
emissions at less cost than expensive scrubbers. A sorbent is a highly
absorbent material, such as powdered limestone [42]. It is injected
into furnaces, where the powdered limestone reacts with the acid gases
emitted by the burning coal. The used powder is siphoned away through
the furnace outtake and is captured (with fly ash) in a baghouse or
electrostatic precipitator.

A process called advanced flue-gas desulfurization also removes acid gas
from burning coal without expensive scrubbers. Emissions from burning
coal are piped into a container called an absorber, where the acid gases
react with an absorbing solution (such as a mixture of lime, water, and
oxygen). This reaction forms gypsum, a soft white mineral valuable as an
ingredient [42] in cement.

NOTES TO THE TEXT

[1] environmental issues:环境问题

相关文章