I. Drying and cooling systems
The process of drying and cooling the wet sand requires a large amount of heat and power, which has become one of the key system affecting the cost and quality of dry mix mortar production line. In present, there are three types of wet sand drying equipment: tower type, drum type, and vibration fluidized bed dryer.
Tower type: Tower is also known as vertical drying equipment. This equipment only has drying area without cooling zone, and the temperature is generally above 80 degrees when the sand pass from the drying equipment, so additional cooling equipment is required. it is depend on the drop height to make the material flows by its own weight, therefore, the residence time of material in the machine is not easy to control. Trommel type: It can be divided into single roller and multiple return roller depending on the layer of the roller. The wet sand is slowly rotation by using the trommel and moves from the higher to the lower under the action of gravity. Finally, the dry sand is discharged from the right of the trommel screen. Due to the lack of special cooling measures, the drying sand temperature is generally above 70 degrees.
Vibrated fluidized bed: It is improved by applying vibration on the common fluidized bed. Compare with other drying equipment, the vibrated fluidized bed has the advantage of the fast of drying and cooling, small size, etc. The blast temperature of vibrated fluidized can be controlled within 500 degrees, the temperature of drying sand is around 55 degree.
II. Screening system
Due to the size of the sand is very small(less than 1mm), therefore, it is extremely difficult to separate according to the different size of the sand. The traditional screen equipment has the disadvantage of low separating accuracy, the service life of mesh is short, not easy to change the mesh, and low screening capacity. Linear vibrating screen and trommel screen is the commonly used equipment.
Linear vibrating screen is a widely used machine in dry mix mortar production line, which has the feature of the mesh in each layer are arranged in parallel, and large capacity, high screening accuracy.
Circular vibrating screen is especially suitable for fine screening of fine powder, with small capacity and high screening accuracy.
III The storage system of raw material
The main raw materials of dry mix mortar production line are sand, cement, coal powder, mineral powder and various functional additives.
Sand is the largest amount of raw material in dry mix mortar production line, considering the aquosity of river sand, the sand yard should be large and the river sand should be piled according different time periods, and rainproof cover should be set in the sand yard which come from the last periods. In addition, reducing the aquosity of the sand by natural leaching can reduce energy consumption, and reduce cost.
Bulk material is generally stored in the powder silo by air-supported conveying. The volume of the powder silo can be determined according to the local raw material supply.
IV. Mixing System
The mixer is the core of the whole production system. It is a significant thing to choose a mixer with high efficiency and quality. The core of mixer is to be able to mix a variety of different mixtures in one batch, in particular, materials such as pigments and fibers need to be dispersed evenly, which has a high requirements for mixing technology. In percent, the types of the commonly used mixer are: Zero gravity double shaft paddle mixer and single shaft paddle mixer
Zero gravity double shaft paddle mixer: There is a dead zone in the mixing area, which is easy to cause the unevenness of the mixing materials and the mixing cycle time is long.
Single shaft paddle mixer:
Since it is a single shaft, there is no dead zone in screening, and then choose the optimal blade contact area and angle. Mixing cycle is greatly improved, the host can be reasonable to set up 2~4 pull mixing device, high spindle speed, high efficiency.