There are plenty of difficulties like equipment jamming, rapid wear of wear parts, poor quality of final products, inadequate crushing capacity, etc., when crushing river rock and producing qualified river rock artificial sand and construction aggregate. The main reason is that many investors still use conventional hard rock crushing solutions for river rock without taking into account special properties of river rock, thus mismatching equipment and raw materials.This article will tell you everything about river rock crushing, including challenges, mainstream processing technology, production flow, equipment choice, application fields, mistakes, etc. It is intended to help overseas aggregate investors, engineering contractors, and equipment purchasers to find a directly usable and standardized solution of river rock crushing plant.
Why Are Ordinary Crushers Poor at Crashing River Rock?
River rock, otherwise known as river pebble, is a hard rock naturally formed via erosion and polishing due to flowing water. Physical properties of river rock are very different from ordinary quarry stone and weathered rocks – it is the main reason why river rock crushing is so difficult.
First of all, river rock has a dense structure without any natural cracks and it has a high Mohs hardness of 6-7. It means that river rock has a high compressive strength and a very high wear resistance. It is very difficult for ordinary impact crushers to break such rocks efficiently. Low efficiency of crushing, fast wear of blow bars, impact plates, and other components, high costs of long-term maintenance.
Besides, river rock usually contains soil, sand, and other impurities attached to it. The content of moisture is unstable – wet and muddy materials lead to jamming of the crushing chamber. That affects the ability of the whole production line to operate continuously.Moreover, river rock consists of rocks of various sizes – from small pebbles to large oversized rocks. One small crushing machine cannot meet requirements of both large rocks reduction and production of fine aggregates. Besides, modern engineering projects, concrete production, and road building require aggregates with special shape and size gradation. The production of such aggregates is very difficult via usage of simple crushing machines.Thus, professional crushing of river rock needs a special crushing process based on the principles of staged crushing, primary-secondary crushing, and preferential compression crushing technology. The traditional one-stage crushing process needs to be substituted by systematic and efficient one.
River Rock Processing Technologies
Nowadays there are two types of processing technologies of river rock that are used in different application fields: river obstacle removal projects and commercial aggregate production. The mentioned application fields differ greatly and should not be confused – understanding the difference is the main thing to create an effective river rock crushing system.
Static Crushing Technology (Suitable Only for River Obstacle Removal Projects, Not for Commercial Applications)
The static rock breaking technology relies on usage of hydraulic splitting equipment and expansive demolition agents for cracking and breaking oversized river boulders. Such technology is characterized by such features as non-blasting, non-vibrating, and non-flying. These features make this technology highly safe and environmentally friendly.This technology is used in cases when it is necessary to remove large isolated boulders in the vicinity of rivers, residential areas, and other restricted places with blasting.However, this technology is able to split and break only large rocks and cannot control final particle size. It also lacks capabilities to standardize screening and aggregate production. That is why it is rarely used in commercial sand and aggregate processing.
Mechanical Staged Crushing Process
The mechanical staged crushing process is nowadays considered as the most efficient river rock crushing solution for commercial application. It is widely used by large-scale aggregate plants, infrastructure projects, and mining stones processing operations.This process includes sequential work of several machines optimized for high hardness and abrasiveness of river rock. That allows achieving efficient continuous production with a stable capacity, uniform aggregate size gradation, excellent shape of particles, low impurity content, and controlled machine wear.This process compares favorably to traditional crushing techniques solving main industry challenges including low efficiency of crushing, poor quality of final products, fast wear, and machine failures.
Full Production Process of the Standard River Rock Crushing Plant
The mature and stable production process of the river rock crushing plant is based on the scientific closed loop work cycle. From the preparation of raw material, primary crushing, screening, secondary crushing, fine crushing to sand making each step is optimized according to special features of river rock allowing long-term efficient and cost-effective operation.At the start of operation, vibrating feeder makes uniform and controlled feeding and uses the screening function for removing surface soil, stone powder, and impurities from raw river rock. It helps to prevent material sticking and jamming because of wet and muddy materials.Then oversized river rocks are evenly fed to the jaw crusher for primary crushing. Jaw crusher reduces large rocks having size up to hundreds of millimeters to smaller and uniform-sized materials making initial crushing of hard river rocks.Afterwards, crushed materials are sent to the circular vibrating screen for accurate sorting. Qualified sized materials move to the next stage of production, oversized materials are returned to the primary crushing machine for secondary crushing. Thus, closed loop of crushing process provides consistent input material size improving the stability of the whole production process.After the sorting procedure, qualified and clean rock materials go to the secondary and fine crushing stages. According to the requirements of production capacity and specification of final aggregates, suitable fine crushing machine is selected for the production of standardized construction aggregate.For projects requiring high-quality manufactured sand, VSI impact sand making machine is additionally installed for the shaping and sand production.For the construction projects requiring higher standards, and the use of higher quality concrete, wheel sand washers or spiral sand washers can be added to remove any remaining impurities and mud or stone powder, ensuring better aggregate cleanliness.
Core Equipment Selection for River Rock Crushing Depending on Application
The productivity, the quality of final products, the operational cost, and profitability of the river rock crushing plant depend largely on whether the chosen equipment is correct and appropriate. Due to specific properties of river rock such as high hardness and strong abrasiveness, the special equipment is required at every step of the crushing process in order to ensure the highest results.
Primary Crusher: Jaw Crusher
The jaw crusher is the key and irreplaceable device for almost any river rock crushing plant. Featuring compression crushing technology, jaw crusher is characterized by high load-bearing ability, wide feed opening, stable work, and low failure rate. This machine was developed for primary crushing of large-sized and abrasive river rocks, reducing their size to manageable ones. Whether it is small temporary construction projects or large stationary aggregate production, the jaw crushers are capable of delivering reliable work under various conditions. Depending on production requirements, the users may choose standard or energy-efficient models, making them a perfect fit for many river rock crushing projects.
Secondary and Fine Crushers: Cone Crusher vs Double Roll Crusher
The secondary and fine crushers play the major role in determining the shape, the quality of final product and the operational cost. Now, the hydraulic cone crusher and the hydraulic double roll crusher are two main types of equipment which are used in river rock fine crushing operations. Each machine is optimal for different capacities and investments.
Hydraulic Cone Crusher
The hydraulic cone crushers are the best option for large-scale aggregate plants with capacity higher than 100 tons per hour, commercial production projects and high-quality aggregate processing. They are ideal for large river rock crushing projects. Applying the latest laminated crushing technology, hydraulic cone crushers are specially designed to work with highly abrasive river rocks. They have low wear of spare parts, produce uniformly-shaped aggregates, and are characterized by high level of automation. The size of discharge can be adjusted in accordance with production needs. Combining it with the closed circuit process, the equipment can constantly increase the efficiency and decrease long-term operational cost. Thus, the hydraulic cone crushers are ideal for large-scale, standardized aggregate enterprises requiring stable and continuous production.
Hydraulic Double Roll Crusher
The hydraulic double roll crushers are the best choice for small and medium-sized construction projects, small aggregate processing plants, and projects with limited budget. Specifically designed for hard material fine crushing, this equipment utilizes the smooth compression crushing technology, minimizing wear, reducing failures and producing round-shaped final aggregates with extremely low amount of flaky particles. Final products will meet the international standards of engineering aggregates. At the same time, due to the simple design, easy operation and low maintenance requirements, the hydraulic double roll crusher ensures excellent cost-effectiveness, being a perfect choice for small and medium river rock fine crushing projects.
Aggregate Shaping and Sand Making Equipment: VSI Impact Crusher
In case of high quality manufactured sand requirements, VSI impact crushers are the professional shaping and sand making equipment which is intended for river rock sand making and shaping applications. Using the classic rock-on-rock crushing technology, this equipment uses high speed collision of rock particles, reducing the wear of metal parts and improving the shape of river rocks aggregates. The VSI impact crusher optimizes aggregate grading and produces high-quality 0-5 mm manufactured sand which is widely used in such premium constructions applications as:high-speed railway projects,asphalt pavement construction,high strength concrete production.
Due to the high quality and the stable shape of particles, the VSI sand-making technology greatly increases the added value of the river rocks resources.
Flexible Construction Equipment: Mobile Crushing Plant
In case of the scattered raw materials, the unstable location of construction, and frequent relocation, the mobile crushing plants are an excellent solution.A mobile crushing plant combines the systems of feeding, crushing, and screening into single construction. It doesn't require any complicated foundation and can be transported directly to riverbanks, remote places, and outdoor construction sites. It helps to reduce the material transportation and infrastructure cost, increasing the flexibility of the project. In case of temporary projects, the river rock dredging projects and mobile river rock crushing projects, mobile crushing plants are one of the most efficient and practical solutions.
Optimal Equipment Combination Solutions for Various River Rock Crushing Projects
Depending on production capacity, the conditions of construction, and requirements of final products, the operator should select the optimal combination of equipment in order to create the efficient and cost-effective river rock crushing plant.For large commercial aggregate production projects requiring the standard crushed stone ●products, the suggested combination is:jaw crusher + hydraulic cone crusher + vibrating screen.
This classic combination ensures stable production capacity, good quality of aggregates, and low long-term operational cost.For small and medium construction projects requiring low-cost aggregate production, the preferable solution is:
●jaw crusher + double roll crusher
Such simplified combination requires low investment, fast payback period, and has low rate of equipment failures. For projects requiring both crushed stone and high-quality manufactured sand production, some additional equipment such as VSI sand-making machines and sand washers can be installed additionally to core crushing combination. Such combination enlarges the categories of products, improves their quality and increases the market value of the project. For river rock processing projects with scattered locations of construction and requirement of relocation, mobile crushing plants are the most flexible solution providing adaptation to complex outdoor conditions. For projects requiring the removal of oversized boulders in the blasting restricted area, hydraulic splitters can be used as auxiliary equipment.
Most Common River Rock Crushing Mistakes and How Professionals Avoid Them
All problems experienced by aggregate businesses including insufficient production capacity, unqualified final products, frequent equipment breakdowns, and unprofitability result from wrong processing technologies and equipment choices.First, one needs to avoid hammer crushers in river rock crushing operations. The main feature of hammer crushers is high-impact striking. When dealing with hard river rocks, the hammer heads get quickly worn out, which leads to frequent machine downtimes for replacements and repairs. In the long run, the operating expenses will grow significantly and it will make hammer crushers inappropriate for river rock crushing operations.Second, one needs to avoid single-machine solutions for completing the whole crushing process. As was mentioned above, river rock materials feature high hardness, abrasive nature, and complex raw material properties. One machine is unable to cope with both big rocks crushing and fine aggregates production, which results in material clogging, unstable discharge size, poor quality, and limited capacity.A professional river rock crushing line should be based on staged crushing principle and use different machines for primary crushing, secondary crushing, fine crushing, and shaping procedures.At the same time, material preparation and pre-screening cannot be ignored. Feeding wet and muddy river rocks straight into the crushing equipment constantly causes material clogging in the crushing chamber leading to frequent downtimes and unstable production process.For commercial aggregate production, the proper material preparation, impurities removing, and separation of wet and dry materials are critical for stable production process.
Conclusion
In conclusion, the basis for profitable river rock crushing consists of understanding the material properties, choosing the correct crushing technology, and using appropriate equipment depending on application requirements.Since river rocks are characterized by high hardness and wear resistance, they require professional crushing equipment. Jaw crushers are needed for primary crushing and reduction of oversized rocks. In case of large-scale commercial aggregate projects, hydraulic cone crushers should be preferred for efficient secondary crushing operations, while for smaller and mid-size projects with cost control requirements it is better to use hydraulic double roll crushers.To obtain high-quality manufactured sand, VSI shaping equipment should be added. For outdoor projects where frequent moving of the equipment is required, mobile crushing units will be the best solution option.This comprehensive river rock crushing solution can solve all of the above-mentioned issues of river rock processing more than 99% of the time, including excessive wear of the equipment, poor quality, low efficiency, and high operating costs.In case you have any requirements about feed size, production capacity, specification of the final product, and site conditions, MP professional team will design an individual river rock crushing plant solution for you.
