Use excavation slag to make sand and gravel aggregate

2021-11-16

In the construction of large hydropower projects, a large amount of engineering excavation materials will be produced, of which only a small amount of high-quality stone materials are suitable for processing concrete aggregates, and the rest are basically treated as waste slag. The insufficient concrete sand and gravel aggregates required by the project require additional sources. Increase mines as a supplement.

Regardless of whether it is a new mining yard or a large amount of discarded slag, it will inevitably cause disturbance, destruction and pollution to the ecological environment, which will not only be difficult and costly, but will also increase the cost of project construction. If all the existing excavation slag is used, it will be a huge improvement in the machine-made sand and gravel industry.

If mechanical screening is used in the stockyard, the successful screening rate of useful materials is low, resulting in insufficient material sources. Therefore, the useful materials mixed in the useless materials are sorted out for the production of sand and gravel aggregates to ensure the supply of materials. Therefore, it is necessary to adjust the production process parameters of the system for classification processing according to the quality of different raw materials.

Through the production test of complex material sources, the corresponding production process is worked out, and the construction process is improved according to the results, and finally three characteristics are formed.

1. Through the refined and balanced planning and utilization of excavation materials, the precedent of not setting up mining material yards in large-scale hydropower projects on the Qinghai-Tibet Plateau has been realized, effectively protecting the natural environment in the ecologically fragile areas of the plateau.

2. Successfully developed a complete set of technologies for preparing sand and gravel aggregates from complex sources, developed a dynamic adjustment technology for operating parameters of a sand and gravel system based on a database of complex sources, “three-and-a-half” crushing and shaping and grading adjustment technology, and stone powder content The two-way dynamic adjustment technology increases the utilization rate of excavated materials to more than 80%.

3. The proposed two-stage recovery and settling tank group freely combined sewage treatment method, the single-point control energy saving and environmental protection integrated dust reduction technology of the gravel system, and the improved utilization technology of the by-product “desludge” of the gravel system, ensuring “zero” discharge of tail water. On the basis of this, the fine sand recovery rate has been improved, the targeted dust reduction of different dust sources has been realized, and the waste storage and dust pollution have been reduced.