(1) It is mainly dust caused by sand and gravel transportation, loading and unloading trucks and natural stacking wind;
(2) Mainly caused by leakage and rolling during the forklift loading process;
(3) The cause is that the aggregate silo leaks to the aggregate scale, and then discharges the material to the flat belt through the inclined belt to lift a large amount of unorganized and non-directional dust;
(4) It is all kinds of dust generated on the top of the tank caused by the movement of powder in the tank caused by pumping various types of powder or feeding by other methods and discharging of the powder tank.
(5) It is a large amount of dust mixture generated during the process of various powders entering the mixer after weighing and the aggregate being lifted by the inclined belt into the pre-feeding bucket and then into the mixer.
2. Waste water, waste residue
There are two main sources of wastewater:
(1) Waste water from cleaning concrete tankers and mixers, this part of the waste water is large in volume and high in concentration, usually contains insoluble substances such as sand, powder mixture, admixtures, etc., and the solid content is unstable;
(2) Waste water from washing the factory area and large vehicles entering and leaving the factory area, this part of the wastewater is relatively simple and stable in composition. The source of the waste residue is mainly the mixture produced by the separation of the mixture after cleaning the concrete tanker and the mixer, and the composition is mainly sand and gravel. Measures to reduce the hidden dangers of dust and waste water.
3. waste residue
Since dust pollution accompanies the entire process of concrete production, the impact on the environment is the most intuitive and rapid, so we should start from the entire process and link with each other to reduce or eliminate the hidden danger of dust generation.
(1) Automatic car washing machine installed in the factory area: the incoming and outgoing concrete tankers, powder material transport vehicles, and sand and gravel trucks should all pass through the automatic car washing machine to achieve automatic cleaning and prevent dust from being brought out of the factory.
(2) Fully enclosed stock yard with automatic spraying system: The sand and gravel stock yard is the place where the mixing plant generates a lot of dust, and the sand and gravel material unloading process can generate a lot of dust. The dust content of crushed stone is high, and it is easy to generate dust during storage and transportation. The content of stone powder in sand (especially machine-made sand) is higher. The wall adopts a new type of building material hollow brick, which not only prevents the dust from being discharged into the surrounding environment when the aggregate is unloaded, but also effectively reduces the noise pollution of construction vehicles. Once again, automatic sprinkler systems should be installed at the entrance and exit of the material yard and the aggregate bin to prevent the vehicles entering and leaving the material yard from bringing in and out of dust and the dust generated during the unloading process, and further reducing the dust concentration. The upper part of the silo should also be equipped with spray facilities to prevent dust generated during production and feeding.
5. Fully enclosed mixing building: Aggregate should be conveyed in a fully enclosed manner. Special dust removal equipment should be set up for a large amount of dust at the interface between the pre-feeding bucket and the inclined belt, which will be collected and sent to the mixer for reuse. The powder silo should also be a fully enclosed structure. For the dust formed by the movement of the powder inside the tank caused by different feeding and unloading methods of the silo, different dust removal equipment and methods are used to recycle it.
6. Research on feeding process: Carry out experimental research on the feeding sequence and cross feeding method of sand, stone, cement, water and other materials, and obtain a set of optimal feeding process plan to effectively reduce dust emissions.
In addition, strengthen the management and control of waste water and residues. We should strengthen the management and control of waste water and residues. The plans for the recycling of waste water and residues are as follows:
(1) The concrete batching plant should be equipped with a sand and gravel separator and a matching filter press.
First, the remaining concrete is separated by a sand and gravel separator, and the sand and stones can be directly reused. Secondly, the separated powder slurry can be directly pressed into a block through a filter press. Finally, the precipitated wastewater passes through the water circulation device and can be used for recycling without any waste water and waste residue pollution.
(2) The car wash pump extracts the clarified recycled water and injects it into the mixer truck through the car wash water injection pipe for car wash water. After washing, the sewage and residues are discharged into the discharge tank, and the high-speed flowing water formed by the sewage in the mixing tank is extracted by the tank flushing pump and enters the sand and gravel sewage recycling and classification machine. The sand and stone are separated from the sewage by the classifier and can be used as raw materials for mixing concrete, and the sewage returns to the mixing tank through the drainage tank.
(3) The agitator of the mixing tank rotates periodically to keep the sewage uniform and not sedimented, and pumped into the temporary storage tank above the mixing floor through the mud pump. The solenoid valve of the water outlet of the temporary storage tank closes or opens according to the signal sent by the host to inject water into the water metering scale, and return it to the concrete as the material for mixing concrete.