Taking granite as an example, we would like to introduce 6 aspects of site planning, process design and equipment allocation of a machine-made sand production line with an annual output of 3 million tons.
1. Raw material of artificial sand
There are many types suitable raw materials for processing artificial sand. Such as mountainous-type: granite and limestone; river-type: pebbles; tailings-type: various industrial waste residues.
Usually, in line with the principle of comprehensive utilization of resources and local policies, the selected raw materials for sand production vary from place to place.
In this case, granite is selected as raw material to process machine-made sand. The requirements of selecting mine are shallow overburden of raw materials, conformance of physical and chemical indexes, stable quality, large mineral reserves and convenient transportation.
2. Scale of Production
Because the newly-built mine has a capital construction period of about one year, the stone that can be mined is limited the first 2 years; After 2 years, mining scale becomes larger gradually.
Therefore, the annual production are controlled in 1 million tons sand and 1 million tons gravel in the first 2 years, and adjusted to 2 million tons sand and 1 million tons gravel after two years.
3. Product Classification
Products are mainly positioned as building stones and building sand.
Building stones specifications are 0-5mm, 5-10mm, 10-31.5mm, 31.5-60mm.
Building sand specifications are classes I and II of 0-4.5mm.
According to the market demand, we can also provide stone with particle size less than 800 mm and stone powder with particle size less than 0.075 mm.
4. Mode of Production
At present, sand-making technology mainly consists of dry and wet production methods, and there is also a semi-dry method. Considering the local environmental requirements, this project chooses the dry process sand making method.
5. Sand Making Process Design
According to the characteristics of the granite, the process is designed to be four-stage crushing, that is, primary crushing, medium crushing, fine crushing, and sand making. The primary crushing is highway development and reserving desliming facilities. Medium crushing, fine crushing, sand making form a closed-circuit recycling production process to meet the needs of aggregates for concrete with various gradations with suitable screening workshop.
(1) Mining and Highway Development
According to the actual situation of the mine, the highway is about 1800m long, and the ore is transported to the unloading platform of the crushing workshop.
(2) Primary Crushing
Raw materials < 800mm are transported by automobile into unloading pit and conveyed by vibration feeder that with screening device.
Material < 150 mm does not need to be broken and falls directly onto the belt to enter the primary field.
Material > 150 mm is crushed by jaw crusher (discharge port 150 mm), and the crushed material enters the primary field.
(3) Medium Crushing and Screening
This crushing system consists of one HP500 thick cavity cone crusher and one HP500 thin cavity cone crusher in series. The material can be pre-screened(<31.5mm) by heavy screens before entering the medium crushing, which can increase the output and reduce the power consumption. Medium crushing system and vibration screen system have dust removal device.
The mixture materials crushed by two cone crushers enters two 3-layer circular vibrating screens, and the materials < 31.5mm are divided into three specifications: 0-5 mm, 5-13 mm, and 13-31.5 mm.
(4) Storage of Gravel
After crushing and screening, three kinds of materials were conveyed into three 2500t circular storehouses by belt.
(5) Distribution of Gravel
The gravel is discharged from the bottom of the gravel storage through an arc valve and is conveyed to two 300t gravel distribution depots by belt.
(6) Sand Making Screening and Stone Powder Separation
Sand making raw materials are mainly 0-5mm, 5-13mm and some mixtures of 13-31.5mm. After entering the sand making machine, they are transported to 3-layer vibrating screen by transdermal belt. Material > 5mm is returned to the sand making machine for further crushing (which can also be sold as refined stone). The remaining materials are divided into 3-5mm and < 3mm materials. Material < 3mm is transported into the stone power separator by a belt conveyor. Stone powder and sand are separated.
(7) Sand Storage and Distribution
The finished sand is transported into two product storehouses by transdermal belt, and the stone powder is transported into a 2500t powder storehouse by hoist.
(8) Electrical Control
The total capacity is 6500 kW, which is 0.4 kv/unit. The equipment is of three types of electric load.
(9) Monitoring and Automation Control
The remote video monitoring and automatic centralized control of production line can effectively guarantee the continuous operation of production line, reduce operators, achieve the purpose of energy saving and cost saving.