Using ash and slag as construction materials to limit environmental pollution

Recently, the Government has issued a number of mechanisms and policies as a basis to promote the handling and use of ash and slag in thermal power plants (NMNs) to produce construction materials, reduce pollution. The environment is caused by these two waste materials.

Ash, slag from thermal power plants (NMNs) is considered suitable for production of construction materials and used for construction, again solving the problem of waste treatment into the environment.

In Vietnam's power system, the role of coal-fired thermal power plays an important role. In 2017, the total electricity output of coal thermal power plants is 67.56 billion kilowatt hours, accounting for 34.1% of the total national output. It is expected that by 2020, coal output will account for 42.7% and increase to 49.3% in 2025.

Production of unburnt materials from ash, slag of thermal power plants, Photos: internet

Accordingly, the amount of ash and slag generated by coal companies will be 15 million tons by 2020, 20 million tons by 2025. Vietnam Electricity Group (EVN) owns and operates 12 coal thermal power plants. , with an average volume of coal used about 34 million tons / year. The total volume of ash and slag of EVN's thermal power plants arises an average of 8.1 million tons / year.

Currently, in addition to the ash, slag is received and reused by the units, the rest is transported and stored in slag dumps. These dumps are designed to prevent leakage into the environment. Total volume of ash and slag is stored at the slag dump of thermal power plants across the country is nearly 15 million tons.

Scientists in the country and around the world have proved that ash and slag of NMNs are valuable materials to produce construction materials. Ash, slag emitted from coal processing factories all contain the same mineral composition as the components in cement kiln production, especially for advanced coal-fired (boiler) technology. burning very coal, the composition of fly ash can be from 1% to 2%.

In this case, fly ash of the power plants can be used directly as high grade finished cement, which can be used for coastal embankment works. In Vietnam, in the past years, ash and slag of coal-fired power plants of EVN have been used in the production of construction materials, such as concrete, cement, unburnt bricks, construction components. ... Two large hydropower projects, Son La and Lai Chau, used roller-compacted concrete technology, in which the mass of fly ash is relatively large, selected from fly ash of Pha Lai NM.

While coal mining companies in the North have found and signed contracts with their partners to consume the majority of their ash and slag which is relatively stable, in the Southern coal mines, it is still in process. working with units capable of consuming ash and slag for units to take samples, give consumption plans.

On April 12, 2017, the Prime Minister issued Decision No. 452 / QD-TTg approving the scheme to promote the treatment and use of ash, slag and gypsum of thermal power plants, chemical and fertilizer plants. to produce raw materials for construction materials, with the goal to 2020 is:

For ash and slag thermal power as mineral additives for cement production is about 14 million tons; replacing part of clay to produce clinker about eight million tons; replacing a part of clay to produce baked clay bricks about 7 million tons; making two million tons of mineral additives for the production of concrete and unburnt bricks; making construction leveling materials, completing mines and making roads around

According to energy and environment experts, in order to well implement the set targets, the Government should continue to direct the Ministry of Construction and the Ministry of Industry and Trade to coordinate with the concerned ministries and branches to review and issue legal regulations requiring compulsory construction materials market to use products made from ash, slag, plaster, concrete, unburnt bricks; guide factories to generate ash and slag and units to receive and use ash and slag to fully comply with environmental protection requirements.

Research on support mechanisms, create conditions for application investors, participate in business cooperation with water plants in handling and consuming ash, slag and gypsum. Modify Decree 38/2015 / ND-CP in the direction that if thermal ash, slag meets standards, technical standards as raw materials for production of construction materials, it is considered a commodity product and not subject to adjusted according to the regulations on ordinary industrial waste. Encouraging construction material production establishments to use ash, slag and gypsum as production materials. Promote propaganda and mobilization to raise the awareness of people and enterprises on the use of products from the application of ash and slag to replace construction materials.

The NMs should continue to find, select and create conditions for qualified partners and the ability to process ash, slag, and require partners to meet environmental protection during the declaration process. waterfall, transportation, handling. At the same time, support partners to ensure the quality of ash and slag of thermal power plants, arrange premises for units to install and operate systems of equipment to collect and transport ash and slag effectively.