The resource utilization of solid waste such as construction waste has become a new direction for manufactured sand
Solid waste is not a useless waste, but a useful resource, a valuable asset. The ultimate way out of solid waste treatment lies in "waste resourceization", a philosophy that has become a basic policy of waste management system in countries around the world. Solid waste resourceization can not only create social benefits, make the best use of the material, and achieve certain economic benefits, but also effective environmental protection.
Solid waste, if properly treated, has the following uses:
1. crushed as building foundation or road base is the simplest method of utilization, and is also the most commonly used method of recycling;
2. crushed to produce concrete block bricks, paving bricks, recycled permeable bricks and other brick products;
3. replace part of the natural sand and gravel aggregate to make recycled aggregate concrete - this is the most valuable treatment method for waste concrete, recycled concrete made from recycled aggregate is green concrete.
Construction Waste
Construction waste is the solid waste generated in the process of building demolition, construction and renovation, including slag, concrete block, rubble block, brick and tile block, waste mortar, mud, asphalt block, waste plastic, waste metal, waste bamboo and wood, etc.
Processing Status
At present, most of the construction waste is transported to the suburbs or countryside by construction units without any treatment, and piled up in the open or landfilled, which consumes a lot of construction expenses such as land acquisition fees and waste removal fees, and at the same time, the scattering and dust in the process of removal and piling, and the flying of ash and sand have caused serious environmental pollution. (The fine powder and soluble phenolic alkali components of waste concrete diffuse into the ground by wind and rain, which can deteriorate soil and groundwater quality).
Existing utilization rate
Tunnel Slag
Tunnel slag is the stone waste material excavated during the tunnel boring process. With the development of China's highways and the importance of environmental protection, the proportion of tunnels in mountain highways is increasing, and the proportion of some mountain highway tunnels in the total length of the route has exceeded 40%. These tunnels excavation process, inevitably produce a large number of cave slag, due to the construction process, construction organization and other factors, a large number of tunnel cave slag can not be reasonably used, often need to build a special dumping ground to abandon. The abandonment of cave slag not only occupies land resources, but also affects the environment, and sometimes forms a safety hazard due to improper disposal.
In 2016, the Ministry of Transport issued a guideline on the implementation of green road construction, requiring road construction to "zero disposal, less borrowing", to save and use the traditional practice of disposal, solid waste resources into a treasure.
Tailings
Recycling: It can be used for road construction, sand and gravel aggregate, concrete mixing plant, earthwork, housing construction, environmental protection brick, etc.
The part of the product of the sorting operation in tailings beneficiation that has a low content of useful target components and cannot be used for production is called tailings. Tailings are a treasure to be mined. Experts believe that the current task of China's mining circular economy is to develop and utilize the large amount of tailings that have been put aside for a long time.
Recycling: there are certain useful components can be purified and recycled, other components of tailings can be used as construction raw materials after treatment, through reprocessing can be made into cement, sand bricks, tiles, refractory glass and foam and other materials; available tailings made of raw materials for building roads or anti-skid materials for road surfaces; can also be mulched on the tailings dumps to create fields, plant crops or plant trees.
Coal Gangue
Coal gangue is the solid waste discharged in the process of coal mining and coal washing, is a kind of black and gray rock with low carbon content and harder than coal in the process of coal formation with coal seam. It includes digging gangue in the process of roadway digging, gangue extracted from the top plate, bottom plate and interlayer in the process of mining, and washed gangue picked out in the process of coal washing.
Recycling, recycling purposes: coal, chemical materials (pyrite), power generation, manufacturing construction materials, production of low calorific value gas, manufacturing ceramics, making soil improver, or for paving, underground filling, ground filling land. In the gangue mountain after spontaneous combustion can also be planted grass forestation, landscaping.
The main process of solid waste resource utilization
- Sorting: Removal of large pieces of debris from raw materials by tracked heavy-duty screen or manually;
- Iron removal: remove small and medium-sized steel bars, iron wires and other debris;
- Crushing: Crushing large aggregates into granules that meet the regeneration requirements;
- Sieving: Sieving and sorting according to the regeneration requirements;
- Wind sorting: removing light debris from the aggregates again;
- The whole process is combined with dust removal technology: spraying, fog gun, nano-film dust suppression, etc.
Solid waste resource utilization main equipment
Crushing and screening is an important process of solid waste recycling, and the equipment used in solid waste treatment is tracked mobile crushing and screening equipment,like tracked jaw crusher, tracked impact crusher, tracked cone crusher and tracked screen etc.
Track mounted mobile crusher has the following advantages.
- No foundation and supporting construction needs, can be processed in situ at the demolition site, very convenient;
- The ability to move stations quickly, eliminating the process of dumping and reducing recycling costs;
- Flexible combination of different working conditions, reducing investment costs;
- Simple operation and maintenance of the equipment, reducing personnel investment costs;
- The equipment is equipped with sound insulation equipment and dust removal equipment for dust and noise reduction, which has reached the national environmental protection testing standards for workshops.
