At the 7th China International Sand and Gravel Aggregate Conference, Hu Youyi, President of China Sand and Gravel Association, believes that in response to the current global epidemic prevention and control situation, the central government proposed to accelerate the formation of a domestic large cycle as the main body and a domestic and international double cycle that promotes each other. The new development pattern, as well as the promotion of coordinated regional development and new urbanization during the "14th Five-Year Plan" period, and vigorously promoting the construction of new infrastructure, transportation, water conservancy and other major projects, etc., provide a new round of opportunities for sand and gravel and equipment companies to expand the domestic market opportunities and broad development space.
The development of the gravel crushing production industry to this day is no longer a simple process of breaking big stones into small stones and making sand from small stones. Nowadays, environmental protection requirements are becoming stricter, more and more sand and gravel production lines, and the sand and gravel industry is fiercely competitive. If you want to stand out among much sand and gravel production lines, you must follow the process design guidelines and equipment selection of an environmentally friendly and high-quality gravel production line type purchase principle!
1. Initially broken unit
At present, the primary crusher mainly uses jaw crushers and gyratory crushers, which are mainly used in super large mines and quarrying projects. Large-size jaw crusher allows the maximum side length of the feed to be up to 1500mm, which has become the most used type of primary crusher. The choice of jaw crusher depends on two things: the first is whether the maximum allowable feed size meets the requirements; the second is whether the processing capacity of the discharge port size under the determined discharge size meets the system requirements. The vibrating feeder needs to be installed before the initial breaking machine depends on the scale of the production line. The reasons are as follows:
① Since jaw breaks are not allowed to start in full cavity, the feeder can be started with load, and the feeder controls the feeding in the previous process. Once it stops abnormally, it can reduce the storage of jaw breaks and is easy to recover;
② The feeder changes the feeding of intermittent dump trucks and loaders into continuous feeding to the jaw crusher, reducing the fluctuation of the jaw crusher load and prolonging the service life of the machine;
③ Often the size of the truck feed is uneven, sometimes large and sometimes small. When there are more large pieces of feed, the jaw crusher has a large load and a slow crushing speed. Otherwise, the feeder can adjust the feeding speed to make the jaw crusher. The crusher feeds less material when the load is large, and feeds more material when the crushing speed is fast, which is also conducive to the improvement of the average processing capacity.
2. Second breaking unit
There are two main types of secondary crushing equipment: cone crusher (single-cylinder hydraulic cone crusher and multi-cylinder hydraulic cone crusher) and impact crusher
Cone crusher is secondary crushing equipment that is widely used in domestic and foreign sand and gravel fields. Its different specifications and different cavity shapes of the same specification can meet the requirements of various processing conditions and better meet the requirements of the process flow. It runs smoothly and has long service life for wearing parts, commonly used to crush stones with medium hardness and above.
Due to the large crushing ratio and fewer needle-like particles in the discharge, impact crushing has been widely used in sand and gravel yards, especially highway pavement quarries in recent years. The impact crusher has two significant weaknesses: First, under the same processing capacity and similar conditions of incoming and outgoing material size, its installed capacity will be greater than cone crusher and jaw crusher, because it mainly uses impact crushing. When rotating at high speed, the blast effect causes a large loss of ineffective energy; the second is that the wearing parts wear faster, which are often more than 3 times shorter than the cone crusher under the same processing conditions, and the operating cost is high.
3. Three-breaking unit
The commonly used three-crushing units include vertical shaft impact crusher (sand making machine), and complex crusher (sand making machine).
① The vertical impact crusher uses two crushing principles of "stone beat stone" and "stone beat iron" to crush materials. The finished product has good grain shape, low cost, strong adaptability, large throughput, excellent quality of finished products, and wide application. With its characteristics and unparalleled competitive advantages, it is widely used in the fine crushing and shaping of coarse sand in the aggregate processing industry, thereby optimizing and adjusting the particle size gradation of the finished sand, so that the fineness modulus of the sand can be smaller.
② The vertical shaft impact crusher (sand making machine) has developed rapidly and has become a common equipment for sand making, shaping and three crushing. The discharging particle size can be controlled by adjusting the rotor structure, rotation speed and motor power. The rock flow is particularly smooth, the processing capacity is large, the operation method is simple, efficient and energy-saving, and the product has a good particle shape.
③ The vertical composite crusher has both impact and grinding mechanism. Our company presided over the drafting of the national industry standard for this product. This series of products can achieve more crushing and less grinding. It is an ideal fine crushing equipment for energy saving and consumption reduction. It is also suitable for the fine crushing of various solvent raw materials in the iron and steel metallurgical industry and the crushing of various medium-hard rock minerals in other fields such as construction, building materials, and chemical industries. It has the characteristics of simple structure, large throughput, large crushing ratio, high yield, and low energy consumption.
4. Screening system
The screening system of the sand aggregate production line runs through the whole production line. The screening (pre-screening) that needs to be carried out before crushing. Pre-screening can avoid ineffective crushing of materials, thereby increasing the production capacity of crushing equipment and reducing power consumption; screening of the final finished sand and gravel aggregate. The aggregate processed by a production line is more than a finished product of one particle size, and different users have different requirements for the particle size of sand and gravel aggregates. Therefore, they are screened into products of various sizes and supplied to various users; if the sand and gravel production line if the water content of the material is too large, it can be dehydrated and screened. On the one hand, the product quality is improved, which is convenient for storage and transportation, and reduces the transportation volume. On the other hand, the water can be recovered for recycling.