Regarding examination of ash and slag treatment in Duyen Hai 1 Thermal Power Plant, Associate Professor - Doctor Phung Chi Sy, General Secretary in charge of the southern region of the Vietnam Environment and Nature Protection Association said, Duyen Hai 1 Thermal Power Plant has strictly followed the regulations of the environmental protection. According to the monitoring results in the surrounding areas, currently there has been no phenomenon of dust dispersal from the ash-slag dumps.
According to Mr. Au Nguyen Dinh Thao-Deputy Director of Duyen Hai Thermal Power Company, in order to prevent the ash and slag from dispersing into the environment, the fly ash is collected inside the plant, then taken into three silos by a closed pipeline system. Later, ash and slag is transported from the silos to the slag dumps by the covered specialized trucks. Before being discharged to the trucks and transported to the dumps, ash and slag is sprayed with water to create humidity (15-20%) and covered for not dispersing dust into the environment. Besides, the ash dumps are compressed and sprayed with water in order that ash and slag shall not be dispersed in case of tornadoes. When ash and slag is compressed to the permissible height, the surface will be sprayed with cement mortar to have entire coverage.
Using ash and slag of the thermal power plant to produce slag blocks is a long-term solution
Long-term solutions
According to Associate Professor - Doctor Phung Chi Sy, if no measure to use ash and slag is taken, after a period of time, over high dumps of ash and slag may causing difficult-to-control dust pollution because of wind blowing. Therefore, it is crucial to for a technology using ash and slag as materials for construction.
Many countries around the world have used ash and slag in many areas such as: dikes construction, road foundations, additives for cement, concrete and slag blocks, fillers for polymers, PE, etc. Up to 75-90% of the ash and slag in the world have been processed and reused.
In Vietnam, following the direction of the Prime Minister, the coal thermal power plants under EVN have signed contracts with companies using ash and slag to build hydroelectric roller compacted concrete (RCC) dams at Son La and Trung Son hydropower plants and to make additives in producing construction materials such as concrete and slag block.
Specifically, Pha Lai thermal power plant has sold over 400,000 tons of ash and slag per year, accounting for about 65-70% of the total volume of ash and slag discharged; Hai Phong 1 and Hai Phong 2 thermal power plants have sold about 15% of the amount of ash and slag per year; Ninh Binh thermal power plant has supplied the entire ash and slag to an enterprise producing construction materials, etc. Recently, Duyen Hai thermal power company has signed contracts with 3 enterprises to supply ash and slag for making brick with the total volume of about 1,260,000 tons per year; Vinh Tan thermal power plant company has signed a contract with Ever Green investment joint stock company to cover the entire amount of ash and slag of Vinh Tan 2 thermal power plant throughout the lifecycle of the plant for the production of construction materials, slag blocks and coastal protection concrete structures.
Despite great efforts to promote ash and slag utilization, compared to the amount of ash, slag discharged every year from the thermal power plants, the volume in use is still modest. The Ministry of Construction therefore has drawn up and proposed the Government to speed up the treatment and using of ash, slag, and plaster of the thermal power plants and the fertilizer chemical plants to make raw materials and building materials used in public construction works in the 2016-2020 period. The draft set out the targets that up to 2020, the use of ash, slag and plaster reaches 60% of the discharge volume to make construction materials, filling materials and road construction materials; up to 2030, this number should be 90%; the factory producing materials for construction located near the source of the qualified ash and slag should take use of them to produce raw materials and additives as substitutes for natural raw materials.
As forecasted, by 2020, the volume of ash, slag discharged from the coal power plants shall reach about 30 million tons. Meanwhile, the ash dumps of the power plants are limited in storage capacity and unqualified. Therefore, the study of the solutions of using ash and slag in the thermal power plants is really needed.
Now EVN in collaboration with the Institute of Building Science and Technology have conducted studies to use ash and slag from the power plants of the Duyen Hai Power Center to make reinforced materials for foundations and works. It is planned that pilot deployment will be conducted in 2017 and it will be rolled out for application in all the thermal power plants of EVN.
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Associate Professor, Dr. Truong Duy Nghia: "to make ash and slag as the raw materials for producing building materials, it is necessary to have the Government involvement, because this is a coordination process amongst stakeholders, the power industry or building material industry alone is not adequate.
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