With the upgrading and adjustment of the national industrial structure, the production of machine-made aggregate has entered the industrial era, and the corresponding design, production and quality control standards have gradually improved. As an industrial product, machine-made aggregate not only promotes the change of market consumption concept, but also promotes the development of diversification of concrete performance. However, due to the diversity of raw materials and market demand, the technical level of engineering design units and other reasons, the sand production line can not achieve the desired results after putting into operation.

The environmental pollution of machine-made aggregate production line is mainly dust, noise and sewage produced in the production process. The treated wastewater and noise can meet the national standard. This paper mainly introduces the dust control measures from three points: dust reduction, dust reduction and dust collection.
The optimum design of machine-made sand aggregate production line includes the following aspects:

1. Optimum Design of Environmental Protection for Machined Sandstone Aggregate Line

By optimizing the design, the dust in the production process can be reduced.

1) Controlling the cutting angle of the silo and making cushioning design at the lower part of the silo can not only reduce the impact of material flow on the feeder, but also reduce the dust raised during feeding.
2) Equipment sealing design, flange connection between chutes, ladder chute for unloading, etc.
3) To minimize the material transfer point and drop.

2. Optimum Design of Environmental Protection for Machined Sandstone Aggregate Line

Mainly through efficient spray device to reduce the suspended dust as soon as possible, reduce pollution:
1) the top of the material unloading bin is equipped with a spray device to remove dust when discharging.
2) a spray device is installed above the blanking point of intermediate storage yard and finished product yard to realize dust suppression.

3. Optimum Design of Environmental Protection for Machined Sandstone Aggregate Line

1) Designing the dust collection system by reasonable arrangement and balanced calculation. For aggregate line, the angle of dust collecting duct is generally controlled at not less than 55 degrees in the upwind duct and 40 degrees in the downstream duct; the wind speed of dust-containing duct is controlled at about 15 m/s and the wind speed of clean duct is controlled at about 12 m/s; the number of dust collecting points of the same collector is as small as possible, not more than 8; the number of elbows of dust collecting duct should be minimized; the design should achieve the balance of air volume and pressure of dust collecting system. 2.
2) Dust collection system has balanced calculation, reasonable layout, avoid waste caused by random selection. For example, the sand and gravel production line system of an enterprise: the dust lifting points of the production line such as crushing and screening are all one-to-one dust collection, the air handling capacity of the selected dust collector is about 40,000 m3/h (actually not needed), and the configuration of dust collector and fan is large, resulting in waste of investment and increased operation cost. Therefore, the balance calculation and reasonable arrangement of dust collection system should be paid attention to in design.

As an important index of Engineering construction, project investment has been attached great importance by more and more enterprises. It is found that the investment of the machine-made sand aggregate production line varies greatly. The total investment of a 1500 TPH sand aggregate production line is about 250 million yuan, that of a 2-1000 TPH sand aggregate production line is about 130 million yuan, and that of an 800 TPH sand aggregate production line is about 35 million yuan. Although there are many differences in raw materials, equipment, technology and so on, there is no absolute comparability in investment. But similar conditions, the same size of the project, or comparable. Using the experience of scale investment in cement industry for reference, the sand and stone industry can optimize engineering design and control construction investment to prevent waste of investment due to inadequate pre-project work, unreasonable site selection and production line allocation.

In recent years, Luoyang Building Material Architectural Design and Research Institute has designed and completed nearly 80 production lines of machine-made sand aggregate of various scales, and accumulated a lot of engineering design experience. The designed sand and gravel production lines of various scales have the following characteristics: reasonable matching of crushing equipment, compact space layout, small area, high investment and economic benefits, good quality of gravel and low output rate of stone powder. At the same time, the production line adopts the computer DCS control operating system to achieve accurate production control, automatic operation, ensure product quality and reduce labor intensity.

The production line designed by Luoyang Building Materials Architectural Design Research Institute has the following characteristics:
1. The production line is flexible: suitable for large-scale production with capacity of 500-3000 tons/hour;
2. The production cost of finished sandstone is only 3/5 of that of conventional production line.
3. Production automation is high, energy consumption is low and crushing ratio is high.
4. The payback period is short and the investment can be recovered in 4-5 months.
5. It has plastic function and the product is cuboid.
6. The finished product has good granularity and meets the national standard. Quartz sand production technology in sand and gravel production line (stone production line).