Analysis of cone cavity selection and particle size matching technology for secondary and tertiary crushing stages of sand and gravel aggregates

In the secondary (medium crushing) and tertiary (fine crushing) crushing stages of the sand and gravel aggregate production system, the core task of the cone crusher is to further crush the material (usually 100-300mm) after the primary crushing to the target particle size that meets the specifications for concrete or asphalt aggregates. The selection of crushing chamber type is one of the key technical decisions that affect the particle size distribution, production capacity, and operational economy of the final product. The short head type, standard type, and intermediate type cavities have different geometric characteristics and are suitable for different particle size requirements.

1、 Differences in core geometric features and fragmentation principles among three cavity types

The cavity type of the cone crusher is mainly determined by parameters such as the width of the feed inlet, the length of the parallel zone, the diameter and angle of the moving cone bottom, etc., and their differences directly affect the crushing behavior and product characteristics.

Type of cavity: Standard, Short Head, Intermediate

The core geometric features have the shortest parallel zone, a slower cone angle, and the widest feed inlet width. The parallel zone is the longest, the cone angle is steeper, and the feed inlet width is the smallest. The geometric parameters are between the standard type and the short head type.

The crushing behavior tends to be mainly laminated extrusion crushing, with a high impact component. The material passes through quickly and has a relatively large processing capacity. Mainly through grinding and multiple squeezes. The material undergoes longer repeated squeezing and grinding processes in the parallel zone, resulting in a higher crushing ratio. Balancing a certain processing capacity with finer crushing ability compared to standard models.

Typical fragmentation ratio is low (about 3-5), high (about 4-6), and moderate

The particle size distribution characteristics of the product are that the particle size is relatively coarse, the content of fine powder is relatively small, and the particle shape (cubic degree) may be slightly inferior. The product has finer particle size, and the content of fine powder and needle like particles may increase, but a finer top size can be obtained. The particle size distribution of the product is between the two.

2、 Logic of cavity selection based on target product granularity distribution

The core logic of selection is to match the cavity crushing behavior based on the required dominant product particle size range, and balance the processing capacity with the product particle size requirements.

1. In occasions where the target product is dominated by 5-10mm (or similar specifications)

Requirement analysis: This specification usually belongs to the medium particle size aggregate (such as "Guami Stone"), and it is required that the fine materials of 0-5mm and the oversized materials of 10mm or more in the product be controlled.

Suggestions for cavity selection:

Standard or intermediate cavities are common choices.

Reason: The standard cavity can efficiently crush materials with medium particle size to the target range, and its shorter parallel zone reduces the phenomenon of over crushing, which helps to control the generation rate of fine powder (0-2.36mm or 0-5mm), and has advantages in processing capacity. If the feeding particle size is relatively uniform, the intermediate cavity can provide a more concentrated product particle size distribution.

Application tip: It is necessary to strictly control the proportion of oversized particles in the feed by adjusting the discharge port and possible upstream pre screening to ensure that the top size of the product meets the standard.

2. In situations where the target product is dominated by 0-5mm (or similar specifications)

Requirement analysis: This specification belongs to fine aggregate (coarse particle part of machine-made sand or small stones), requiring the crusher to produce sufficient fine particles and have certain requirements for particle shape to reduce needle like content.

Suggestions for cavity selection:

Short head cavities are usually a more suitable technical solution.

Reason: Its long parallel zone can achieve sufficient "multiple crushing" of materials, ensuring a higher proportion of fine material output. This is necessary for the coarse grading of production mechanism sand or meeting strict requirements for fine aggregate grading.

Application Tip:

Attention has been paid to crushing: Short head shapes are prone to producing more stone powder (<0.075mm). If the content of stone powder needs to be strictly controlled, it should be combined with wet or dry dust removal processes, or the crushing parameters should be optimized.

Pay attention to particle shape: Long grinding processes may increase needle like particles. Choosing modern cavity designs with laminated crushing optimization, such as asymmetric curve designs, can help improve particle shape.

Capacity matching: Under the same power, the throughput of the short head cavity is usually lower than that of the standard type. When selecting, it is necessary to ensure that its processing capacity meets the production line requirements.

3、 Systematic selection decision-making process

The selection of cavity type should not be carried out in isolation, but should be considered as part of the entire crushing and screening system. It is recommended to follow the following process:

4、 Key Practice Tips and Balancing Factors

Pre control of feed particle size distribution: Regardless of the selected cavity type, a stable and consistent feed particle size within the equipment design range is the basis for maximizing its performance. It is recommended to set up pre screening before secondary crushing to remove qualified fine materials and oversized particles.

Linkage adjustment of "cavity type discharge port": The final product particle size is determined by the cavity type and discharge port settings. The particle size curves of products under different discharge ports are different for the same cavity type. The precise setting should refer to the Gradation Charts provided by the equipment manufacturer.

The continuous impact of wear on wear-resistant parts: With the wear of the lining plate, the discharge port will increase, and the actual length and shape of the parallel zone will also change, resulting in a gradual increase in product particle size. Choosing a hydraulic cone breaker with automatic cavity compensation (such as ASRi system) or developing a strict liner wear monitoring and replacement plan can help stabilize product quality.

Economic trade-off: Standard cavities typically have lower metal consumption rates for lining plates and may have advantages in unit energy consumption; Short head cavities have high efficiency in obtaining fine products, but may come at the cost of higher liner wear rates and stone powder rates. It is necessary to comprehensively calculate the energy consumption cost per ton of product and the consumption cost of wear-resistant parts.

Conclusion

In the secondary and tertiary crushing stages of sand and gravel aggregate production, the selection of cone crusher chamber type is a key process matching task. The short head cavity, with its long parallel zone structure, is an effective technical solution for producing 0-5mm fine-grained products; The standard or intermediate cavity is more suitable for producing 5-10mm medium particle size products, and exhibits its characteristics in controlling fine powder rate and maintaining high processing capacity.

In practical decision-making, it is necessary to incorporate target granularity, upstream feeding, expected production capacity, specific equipment performance curves, and long-term operating costs into a unified framework for analysis. Collaborating with experienced equipment suppliers, referencing their successful application data in similar projects, and conducting production validation where possible, is an effective way to reduce selection risks and achieve long-term stable and economic operation of production lines.