Taking advantage of thermoelectric power plant’s ash to produce construction materials is a solution to dispose ash emitted from coal-fired thermoelectric power plants, reducing impacts on the environment and bring economic benefits to the businesses. Therefore, Vietnamese businesses are encouraged to make use of this waste for the production of construction materials.
Statistics showed that in 2013, the amount of ash emitted annually in five coal-fired thermoelectric power plants of Vietnam National Coal – Mineral Industries Group when releasing the maximum capacity estimated at 2.8 million tons/ year (including approximately 1.7 million tons of bottom ash). It is forecasted that by 2030, when the total coal-fired capacity of the country increased by about 77.000 MW, accompanied by the increase of 176 million tons in coal consumption, the ash emission will have reached 35 million tons/year. If it is not thoroughly handled, this amount of ash will cause great impacts on the environment.
The ash of thermoelectric power plant can be used as additives in the manufacture of cement and concrete. In addition, ash is also used as the binder to reinforce the cohesion of traffic, produce unfired brick, lightweight concrete, ceiling, plastered wall, ceramic, etc.. In the world, developed countries always encourage reuse of coal ash from thermoelectric power plants. For example, in France, 99 % of coal ash is reused; the figure is 80 % in Japan, 85 % in South Korea.
In Vietnam, utilizing ash from cement factories to produce construction materials nowadays, some plants collect and process ash produced fly ash and unfired brick from ash are put into operation near a number of thermoelectric power plants. For example, Pha Lai plant producing fly ash with 8 selecting chains of fly ash according to flotation technology with a capacity of 40,000 tons/month; Cao Tuong fly ash processing plant with a capacity of 80,000 tons/ year (using ash sources of Pha Lai Power Plant); The workshop to select fly ash of Management Board of Son La Hydroelectricity Project Workshop has a capacity of 10,000 tons/ month (using ash source of Pha Lai II Power Plant); etc.. Also use ash as the main material for the production of construction materials, Song Da Cao Cuong Joint Stock Company has invested in installing AAC brick production line with capacity 200,000m3/year and production line to premix dry mortar with a capacity of 60,000m3/year.
In Thai Binh , Mr. Pham Cong Thanh , Director of Thai Binh Construction Department said , when the plants of Thai Binh Power Center go into operation, it is expected to annually emit more than 2 million m3 of ash – it is the major material to produce unfired construction materials of all kinds. Therefore, the province is encouraging the construction of manufacturing facilities of unfired bricks by advanced technology, striving that by 2015, production of unfired construction materials will have accounted for about 20 % and by 2020, it will have accounted for over 30 % of the total production of construction materials of the province.
According to forecast, by 2020, with construction demand as currently, the country will have consumed approximately 42 billion pieces of brick. To produce the number of bricks (by fired method) to meet the consumption demand from now to 2020, 60 million tons of coal will be consumed, especially 6.3 million tons of coal will be consumed in 2020. The production of fired bricks from vertical shaft kiln also emits toxic CO2, SO2 and causes negative impacts on the environment, human health, reducing crop yields, etc. In order to minimize the impacts on environment caused by the production of fired bricks, the Government has focused on the development of unfired construction materials from the materials such as ash of thermoelectric power, cement, grit, sand, etc. Besides, Ministry of Construction has proposed Government to issue incentive policies in order to compel investors of coal-fired thermoelectric power plant desulfurization by wet limestone, it is vital to fully install standard plaster processing lines to ensure the recovery of construction materials. It opens up the opportunity to thoroughly treat the ash emitted from thermoelectric power plants, not only solve environmental problems, but also bring economic benefits to the businesses.