I. Production process of mobile crushing machine sand making equipment
1. Fully dry method
The typical dry sand making production process mainly requires that the particle size of the crushed stone be controlled within the range of 5-40mm, and provided to the sand making machine as raw material. Through the full utilization of screening and grading equipment, the fine crushed stone with a particle size of 2-5mm and the crushed stone with a particle size greater than 5mm are returned to the sand making machine for reprocessing.
In addition, the raw materials with a particle size less than 2.5mm are subdivided into two grades of less than 0.6mm and 0.6-2.5mm. The fine sand material with a particle size less than 0.6mm is removed by the air flow classifier to remove excess stone powder, and then the three materials of 2.5-5mm, 0.6-2.5mm and less than 0.6mm are evenly mixed by the mixing equipment. This method can ensure that all qualities meet the product specifications required by artificial sand.
This process technology does not require water to be added to the overall treatment system of the system. Rain protection measures need to be taken in the sand making related links. An alloy rubber sweeper needs to be installed at the head of the belt conveyor to promote the improvement of stone powder recovery rate.
2. Semi-dry method
During the production process of this sand making technology, there are three main types of raw materials entering the silo for sand making: coarse aggregate with a particle size of 5-40mm after crushing and grading; aggregate with a particle size of 2.5-40mm returned from the sand screening building; slag after dehydration of the finished coarse aggregate with a particle size of 2.5-5mm after grading.
From the process level, this process can effectively control the mud content of the sand making raw materials. The finished sand entering the sand storage is mainly divided into the following three types: coarse aggregate sand with a particle size of less than 5mm after grading and screening; finished fine sand with a particle size of less than 2.5mm obtained by grading coarse aggregate recovered from sewage; fine sand with a particle size of less than 2.5mm.
The semi-dry production process can effectively solve the problems of high mud content and weak rock. According to the quality of the raw materials, it can be divided into a semi-dry production process based on dry method and a semi-dry production process based on wet method. The semi-dry method of producing sand and gravel aggregates can not only improve the quality stability, but also does not produce dust pollution, and is very suitable for various raw materials. However, since this process method requires the treatment of a large amount of sewage, which is a major defect and deficiency, sewage treatment will incur certain treatment costs and the cost is high.
3. Wet method
At present, many hydropower projects in my country adopt wet production, and special purification equipment is required to effectively treat mud and sewage. The wet sand making process mainly has the following process characteristics: the inspection screening and the vertical shaft impact crusher form a closed loop, and two sieves of 5mm and 3mm are set on the inspection screen. The rod mill products and particles with a particle size of less than 3mm are directly entered into the finished sand bin after dehydration and classification. Particles with a particle size of 3-5mm need to enter the rod mill again, and particles larger than 5mm need to be crushed again.
II. Measures to improve the quality of mobile crushing and sand making equipment
1. Coating of coarse aggregates
The processing system is equipped with a corresponding flushing process, which can effectively remove the powder on the aggregates, but the mud on some aggregates needs to be treated with special equipment.
The use of a long spiral classifier to grade and clean stones with a particle size of no more than 5mm can effectively remove clay and mud, and the effect is remarkable. If the source contains some difficult-to-remove rocks such as tuff interlayers, it is easy to produce extremely serious pulverization after secondary crushing, resulting in excessive mud content in the finished material.
Therefore, no matter what form of screening is used, it is necessary not only to use earthwork processing equipment, but also to configure related washing processes.
2. Particle grading
The application of high-grade sand in construction can achieve a significant saving of cement on the one hand, and on the other hand, it can also promote the effective improvement of concrete strength. If the ratio remains unchanged, but the sand is too coarse, it will lead to poor cohesion of concrete, which will cause the concrete to separate easily.
If the sand is too fine, even if the concrete has strong cohesion, its fluidity will be greatly weakened, thereby increasing the amount of cement, resulting in increased construction costs, and also increasing the strength of concrete.
