First, first understand the properties of sand and gravel powder
1. Free powder
Stone powder particles do not bond with each other, do not adsorb on the surface of the sand, and can move freely under the action of wind and gravity.
2. Clump powder
The stone powder particles are tightly agglomerated to form stone powder clumps with larger particle sizes. Conventional powder separators are difficult to remove.
3. Adhesion powder
Attached to the sand surface, when the sand surface is relatively smooth, the stone powder particles are easily removed under mechanical force. When the surface of the sand is uneven, the stone powder particles are closely connected with the sand, and it is difficult to separate them by general mechanical methods.
4. Crevice powder
Some manufactured sand particles are not round and will have gaps, and these gaps are often filled with a large number of stone powder particles.
Second, the way to solve the dust problem
1. High-frequency vibrating screening pretreatment
Basic principle: Machine-made sand is dispersed by high-frequency vibration, silt separation, coarse subdivision and grade pretreatment, and then stone powder is removed by wind.
Specific method: After the material is crushed by the sand making machine, when it enters the screening module, it can first pass through the bulk material or screw lever to bulk the material, which has a preliminary dispersion effect on the agglomerated and adhered stone powder, and improves the uniformity of material distribution. At this point, the stone powder can be primarily sorted by the winnowing unit. After the primary selection, the high-frequency vibrating screen with a vibration frequency of 60-80HZ and an amplitude of 0.15-2.4mm was screened. The vibration intensity of the equipment is 3.5-5 times that of ordinary equipment, which can produce large mechanical force and has a good dispersion effect on the agglomerated stone powder and the stone powder adhered to the surface. At the same time, the coarse subdivision grade of machine-made sand is effectively realized.
Compared with ordinary vibrating screens, the powder removal efficiency of machine-made sand is significantly increased by about 40% after screening by high-frequency vibrating screens, and the required air volume is reduced by 45%.
2. Use a blower + dust collector
The aggregate of a certain specification of the screening machine enters the aggregate blanking slide after screening, and the entire detachable diffusion air distribution chamber is arranged in a suitable place, and the blower is connected to it. In this way, when the free dust on the aggregate surface passes through the slideway, it will be blown up by the blower and collected into the dust collector under the suction action of the dust collector.
In addition, the suction volume of the dust collector can be controlled by adjusting the duct regulating valve. In the case of frequency conversion of the blower, by adjusting the frequency conversion control of the blower and the adjustment of the regulating valve, the ratio of blowing and suction can be adjusted, and the continuous control of the finished powder content of sand and gravel aggregate within a certain range can be realized.
3. Use a powder separator
The separator is used in the
https://www.shdingbo.com/equipment/sand-maker/vsi-vertical-shaft-impact-crusher.html, and its main function is to separate excess stone powder and useful particles, and recycle them separately.
It works by mixing gas and powder to form a gas-solid two-phase flow. The rotating cloth plate and high-speed air flow make the powder gas flow obtain centrifugal force during the rotation process, and the centrifugal force of different particle sizes is different, so as to achieve the separation of coarse and fine powder particles. At the same time, the corresponding method is used to recover coarse and fine powder particles. The useful particles are finished sand, and the useless fine powder is waste.
From the point of view of the location of the separator installed in the building station, it is divided into raw material powder selection and finished product powder selection process. The separator has strict requirements for water content. When the water content of the feed is higher than 5%, the dedusting efficiency of the separator will be seriously reduced. When the water content of the feed is 2%, the separator can give full play to its efficiency, and the sand formation rate is between 60%-70%.
4. Spray dust removal
The spray humidification and dust removal device is installed in the dust removal device to effectively reduce dust. For the dust generated during the transportation of finished products, due to the incomplete separation of stone powder and aggregate in the production process, part of the stone powder will adhere to the surface of the aggregate, resulting in dust pollution during transportation. In order to avoid this situation, the finished aggregate can be washed by wet screening, which can not only solve the dust pollution during transportation, but also remove the stone powder and mud powder on the surface of the finished product and improve the product quality.
