How to design the silo in the aggregate production plant?

What is silo?

Silo is the storage equipment in the bulk material handling mechanized system, which mainly plays the role of intermediate storage, system buffering and balancing operations. The silo device is composed of feed inlet, silo top, silo body, cone bottom, reinforcing ribs, lifting lugs, manholes, discharge ports, control, metering, distribution, mixing and dust removal.

Function of silo in aggregate production plant

In aggregate production plant, silo is a very important part, which plays the role of transfer, buffer and adjustment. In the production process, to ensure the continuous, uniform, and smooth feeding of raw materials, and to ensure the maximum volume, to prevent the accumulation of raw materials at dead corners, the design of silo must be reasonable.

Classification of silo

In stone crushing plant, silo can be classified into raw material silo, adjustment silo and product silo.

Raw material silo is generally square cone-shaped, enclosed on all sides, and welded by steel plates. It is generally used before the vibrating feeder. The size of the raw material silo is designed according to the processing capacity of the primary crusher and the viscosity and humidity of raw material. Generally, raw material silo is located on the ground.

Adjustment silo

The adjustment silo is generally made of steel frame structure or reinforced concrete pouring. It is located after the primary crusher and before the secondary or fine crusher. The main function of adjustment silo is to transfer and adjust the crushed raw material from primary crusher, can achieve the purpose of uniform and stable feeding, can also improve the production efficiency of the crushing production line, and increase the service life of the crushing production line.

Product silo

The style of product silo is more rectangular workshop; the partition wall is used to separate different products, to achieve the purpose of grading products.

How to design the silo? What kind of silo is reasonable?

Design of raw material silo

For feeding module, we should select the platform feeding or the silo feeding according to the site conditions and the ratio of raw materials. The platform feeding uses the height difference to provide gravitational potential energy to the raw materials, which facilitates the entry of large stones and the advance separation of natural sand, but it is necessary to use the terrain to form a high platform to facilitate the entry of raw materials; the silo feeding needs the construction of the pit. Raw materials poured into the pit are transported to the production workshop by the conveyor belt. Compared with the platform feeding, this form needs less investment cost and is convenient for construction. However, it cannot handle too large stones. If there are too large scaled stones or too sharp stones, it may cause damage to the raw material transportation belt and affect the production schedule of the entire production plant.

Design of adjustment silo

For production lines with large changes in raw material composition, such as river pebbles, it is very necessary to set up adjustment silo before medium crushing stage. The size of the silo should generally be able to stack the aggregates for the crushing equipment to operate for 2 to 3 hours. Due to the large change in the composition ratio of the river pebble, the transfer buffer silo is set up in the process to buffer the sudden increase of load or sudden idling of the crushing equipment caused by the excessive sand or excessive pebble content of a certain batch of raw materials, so as to ensure the stable operation of the equipment.

Design of product silo

The style of product silo is more rectangular workshop, the partition wall is used to separate different products. High concrete retaining wall is recommended for partition. The crushed products are transferred to corresponding space by belt conveyor and the products can be piled directly against the wall, greatly increasing the storage capacity of finished products in the silo, and making full use of the space under the condition of relatively saving investment cost. At the same time, the hardening space of the product silo for loading should be enlarged as much as possible to facilitate the loading operation, and also leave enough buffer area for stacking.

Common problems and solutions in silo design

Feeding silo for coarse crushing

The common problem of feeding silo for coarse crushing is that the side discharge port of the silo is designed with a rectangular structure, causing that there are dead corners between the silo and the discharge port. The raw materials cannot be fed smoothly and large sized rocks are easy to accumulate here, affecting the normal feeding.

There is a simple solution to solve this problem: place an excavator next to the feeding port to clean up the accumulated material at any time.

Buffer silo for medium-fine crushing and sand making

The common problem of buffer silo for medium-fine crushing and sand making is that the bottom of the silo is designed as a flat-bottomed steel silo structure. Because the overall material pressure at the bottom of the silo is relatively high, severe deformation and sinking of the bottom of the steel silo will occur during the operation of the production line, which will cause safety risks.

To solve this problem, we can reinforce the bottom structure of the silo. While designing the silo, try to avoid the use of flat-bottomed steel silo structure. When it is unavoidable to choose a flat-bottomed silo structure, try to choose a concrete structure at the bottom of the silo.

Product storage silo

Product silo generally adopts concrete silo, which has large storage and is safe and stable. However, some companies choose steel silo to store sand and gravel aggregates. These companies should regularly check the wear of steel silo and conduct wear-resistant treatment.

Stone powder storage silo

The common problem of stone powder storage silo is that the stone powder is wet in rainy days and the powder will adhere to the silo and be difficult to discharge. To solve this problem, operators can install several air cannons under the silo and use compressed air to loosen the stone powder in the storage silo. The design unit should try to control the stone powder storage to not be too large and add flow aiding plate, inflatable box or air cannon in the cone part when designing.

In production, under the premise of satisfying the continuity of crushing production, the silo design should maximize the use of space location and use some new methods such as double control of the angle between the inclined plane and the horizontal plane and the angle between the edge and the horizontal plane to eliminate the accumulation of material at the dead corners.