Comparing with usual rocks like limestone , granite needs higher requirements for crushing processes and machines. Due to the hardness and wear-resistance, granite can be applied in construction aggregate, road construction, manufactured sand production and other industries. But in practical operations, operators often face many difficulties including rapid wear, low output, bad particle shape and high cost. The main cause is misunderstanding of granite crushing properties, resulting in wrong equipment selection and process design.In order to make your granite crushing project efficient and economic, this article provides you with some professional tips to select granite crushing machines. This solution is suitable for large and small quarries, fixed crushing production line and mobile construction projects, which also meets Google Chinese search engine index requirement.
Difficulties in granite crushing
Before crushing granite, you need to know the difference between granite and usual rocks first. The Mohs hardness of granite is 6-7, which has excellent compressive strength, dense structure and good abrasiveness, belonging to hard and wear-resistant rock.Because of above-mentioned properties, ordinary soft rock crushing machines can't satisfy the requirements of granite processing. If you apply usual crushing machines directly to granite crushing, there will be such problems as quick wear of parts, material jamming, high downtime, too many needle-like and flaky particles and low capacity. That is to say, granite can't be processed into finished product with a single machine. Usually, granite processing adopts multi-stage crushing method.
Proper granite crushing methods and flow chart
There are currently two common granite crushing methods in industry, fixed granite crushing production line and mobile crushing production line. They have different application scenarios but follow the same principle of multi-stage crushing and balance production efficiency with equipment wear.
Fixed granite crushing production line
Fixed crushing plant is suitable for large-scale quarries and long-term production projects, which can ensure good product quality and capacity, and is preferred for large-scale aggregate production.The process is simple but effective. Firstly, raw granite blocks will be reduced by primary crushing machines to become medium-sized stones. After that, secondary and tertiary crushing machines will reduce particle size. In case that you require high-quality aggregates and manufactured sand, an additional shaping and sand-making process can be adopted. Finally, vibrating screen will classify the crushed materials and return oversize material to crushing, becoming a closed loop production process.This multi-stage crushing process is totally matched with hardness characteristic of granite, not only reducing the equipment wear but improving the finished aggregate shape, obtaining more round and uniform particles, meeting the requirements of highway and bridge project.
Mobile granite crushing process
Mobile crushing plant is ideal choice for outdoor construction projects, temporary aggregate processing place, backfilling project and any project requiring relocation frequently. The whole plant is the combination of feeding, crushing and screening, avoiding complicated infrastructure construction and realizing operation immediately after arriving at the place.Though mobile crushing plant adopts highly integrated design, it still adopts the crushing principle of primary crushing + secondary and fine crushing, which can completely meet granite crushing requirements for small and medium-sized engineering projects.
Key tips to select granite crushing machine
The selection of equipment is the key factor determining the success of granite crushing operation. Correct machine can reduce the maintenance cost greatly and increase the production capacity, while improper machine may cause continuous loss in operation. According to the granite property, every crushing process has corresponding machine, and users shouldn't choose machine blindly according to the market trend.
Jaw crusher as preferred primary crushing machine
Jaw crusher is the specific machine of granite primary crushing and regarded as the best choice of hard rock crushing. Strong structure, good impact resistance and high-strength manganese steel liner make the jaw crusher resistant to the serious wear caused by granite and are suitable for processing large raw stones.While choosing jaw crusher, users should consider the equipment material, maximum feeding size and motor power, selecting right type according to the size of raw granite to avoid overloading operation or waste. The hammer crusher and impact crusher shouldn't be adopted as primary crushing machine for granite, whose wear rate is too high and practicality is weak.
Cone crusher as preferred secondary and fine crushing machine
After primary crushing, the secondary and fine crushing for granite should adopt cone crusher rather than impact crusher. Because of the difference of principle, impact crusher relies on impact force while cone crusher uses compression crushing principle, which is specially designed for hard and abrasive rock, having low wear rate, high production capacity and good operation stability.Single cylinder hydraulic cone crusher is suitable for small and medium-sized production line due to its good cost performance and maintenance convenience. Multi-cylinder hydraulic cone crusher is suggested for large production plant owing to its good automation, overload protection and high capacity production ability.
Vertical shaft impact crusher for manufactured sand production
If the production target is to produce premium manufactured sand and high-quality aggregate, the vertical shaft impact crusher should be added to the process. The machine uses rock on rock impact crushing principle to improve the particle shape, reducing sharp edges and excessive needle-like particle, producing well-shaped aggregates with reasonable grading.While selecting sand-making machine, users should pay attention to wear-resistant materials of impeller and dust removing system configuration.
Important Features for Choosing Mobile Crushing Plant
According to the nature of the granite crushing equipment, it mainly includes the tire-mounted and crawler-mounted mobile crushers. In ordinary construction projects with relatively flat ground and general relocation requirements, the tire-mounted mobile crushers have advantages in terms of cost performance. In rugged terrain conditions, the crawler-mounted mobile crushers are more adaptable.The important feature is that the selection should be of the complete crushing system rather than individual mobile crushers. The use of a jaw crusher combined with a cone crusher is recommended to avoid difficulties such as low-quality products and insufficient production capacity in using only one crusher.
Equipment Configuration for Different Working Conditions
Granite crushing project with different working conditions requires different equipment configuration. Appropriate equipment configuration can ensure a good balance between the cost of investment and production capacity.For small capacity production lines with the production capability of 50–100 t/h, a simple configuration including a feeder, small jaw crusher, single cylinder cone crusher, and vibrating screen is adequate. This solution is more economical in investment cost and faster in return, applicable to small construction projects and local engineering.
For medium capacity production lines with the capacity of 100–300 t/h, a more advanced crushing equipment along with sand-making equipment can be selected to produce not only aggregates but also manufactured sand, to satisfy diversified requirements of medium capacity quarries.For large scale production lines with the capacity of more than 300 t/h, big jaw crushers, multi cylinder cone crushers, and auxiliary systems such as sand washer and dust removing equipment are needed. High level of automation ensures reliable production capacity and meets the environmental protection requirement, applicable to the enterprises running the long term projects.
Common Mistakes in Buying Equipment
There is a common mistake that many buyers consider only the price of granite crushing equipment while ignoring the wear-resistant material and equipment matching. With the extremely abrasive characteristic of granite, inferior wear-resistant material will cause more frequently replacements and result in higher operating cost than the initial price difference.In addition, do not believe in the claims of completing the whole granite crushing work by the single machine. As the characteristics of hard rock, multi-stage crushing is required. A single machine can never reach the requirement of large production capacity, high product quality, and long equipment life span.Moreover, the choice of equipment should depend on the actual demand of production capacity. The use of the undersized equipment under the overload condition will speed up the wear, and the oversized equipment under the light load will consume unnecessary energy and raise the costs. Priority should be given to equipment equipped with intelligent protecting function and self-cleaning of cavity, reducing labor cost and minimizing downtime.
Frequently Asked Questions
Q1: Can granite be crushed with an impact crusher?
Impact crushers are not recommended to crush granite, which are more suitable for the soft rocks such as limestone. Using an impact crusher to crush granite can easily result in rapid wear of blow bars, low efficiency and frequent maintenance. Impact crushers are able to do the shaping work but not suitable as the main crushing equipment.
Q2: What combination of equipment is the most durable for crushing granite?
The most durable and most commonly used combination in the industry is the combination of jaw crusher for primary crushing and cone crusher for secondary and fine crushing. This combination has been specially designed for hard rock and has the advantage of low wear, great stability, and less failure, making it the standard solution for granite crushing.
Q3: How should granite crushing equipment be configured in temporary construction projects?
It is recommended to choose a mobile crushing plant with jaw crushing and cone crushing unit for the temporary construction projects. It does not require complicated foundation construction, is flexible in relocation and easy to operate, satisfying all material requirements of small scale projects.The key to granite crushing lies in the adoption of staged crushing process that conforms to the characteristics of hard rock, instead of the single machine crushing process that is often used in soft rocks. No matter whether it is the fixed type or the mobile type production solution, the combination of jaw crusher and cone crusher is the most fundamental equipment configuration that guarantees the production capacity and reduces the equipment wear. Sand making equipment can be added according to the demand to produce aggregates and manufactured sand.When buying granite crushing equipment, buyers shall not only consider about price comparison. Pay attention to the material of equipment, the application of equipment, the automation level and after-sales service. Scientific process design and appropriate equipment choice are the key factors for ensuring the stable operation, continuous production and profit in granite aggregate project.
