Crushers for stone and sand
Sand and stone crushing equipment can crush large size stones into stones or sand with different particle sizes to meet the different requirements of sand and stone materials for construction, railway, highway, and other projects.
Crusher is the common equipment of sand and stone industry that is often used to break large stones, and it has a lot of different types and specifications with different discharge sizes. Understanding the specifications of finished materials can provide necessary reference for users to select equipment.
How to control the particle size?
The main objectives of particle size control are: firstly, to make the configuration and operation of the crushing machinery layer reasonable, secondly, to reduce the proportion of needle-like and flake aggregate in finished products, thirdly, to adjust the proportion of each particle size of the finished aggregate.
In the case of smooth operation of the crusher, the particle size of the sand and stone should be controlled and the acicular and flaky particles should be reduced. The acicular particles are those whose length of the stone particles is larger than 2.4 times the average particle size of the grade to which the particles belong.
And flaky particles are those whose thickness is less than 0.4 times of the average particle size (mean particle size refers to the average particle size of the upper and lower limit of the particle size). Well, how can we control the discharge sizes to produce the high-quality stones with different particle sizes of 5-10 mm gravel, 10-20 mm (1/4 to 1/2 inch) gravel, and 15-25 mm (1/2 to 3/4 inch) gravel that we need? This article explains it in detail.
The initial control by adjusting the discharge sizes of different crushers
According to the crusher discharging particle size for preliminary control, there are many different types of crushers, each type of working principle is different, and the discharging control mode is also different.
The following is a detailed description of the discharge control modes of jaw crusher, impact crusher, cone crusher, hammer crusher and roller crusher.
- It is a common coarse crusher. The size of the discharge port determines the size of the crushed stone and the production capacity of the equipment. Due to the change of wear and particle size requirements of finished products, the size of the discharge port needs to be adjusted from time to time.
- Generally, the size of the discharge material can be controlled by adjusting the crusher plate and wedge block. The adjusting plate is generally located behind the toggle seat inside the adjusting seat.
- When the discharge port needs to be adjusted, the number of plates can be increased or decreased, and the total thickness of plates can be changed, so that the front and rear position of the toggle can be changed, and the front and rear position of the lower swing jaw can be moved, so that the size of the discharge port can be changed.
- Or you need to adjust the wedge block, which is located in the back of the adjustment seat, and the bevels of the two wedge blocks relatively fit together. By changing the relative position of two wedge blocks, the total thickness of the wedge blocks can be changed. And then the toggle plate position changes back and forth.
- At the same time, the lower part of the movable jaw plate moves back and forth so as to change the size of the discharging port, thus realizing the control of discharging granularity.
- It is the crushing equipment for medium and fine sized stones, which can crush medium hardness stones of various materials, and the finished product particle size is better, therefore.
- It is generally used for the second stage of the material crushing and shaping. According to its working principle, the discharge size can be controlled in a variety of ways, such as adjusting the exclusive rotor, adjusting the clearance of the impact plate and the grinding chamber.
- It is often used to adjust the grate clearance between the hammer and the impact plate to control the output size. When the grate clearance is larger, the output size increases. And the discharge size decreases when the clearance is small.
- It is very good at dealing with hard rocks, and is mostly used for secondary crushing with high production capacity. It is mainly equipped with its own hydraulic station device to achieve the adjustment and locking of the discharge port, so as to achieve the purpose of controlling the size of the discharge.
- In addition, the sizes can be controlled by adjusting the motor power to reduce the number of rotor bearing rotation so as to adjust the fine granular discharged by the cone crusher. Or users can check whether the voltage in the workplaces is stable or not, if the voltage value is not within the normal range, it should be adjusted to the normal voltage.
- Besides, users can tighten the belt to prevent the coarse granularity caused by belt slack.
- It is a crusher that can shape the products once, with the output from 5 tons to 150 tons per hour so it is a very cost-effective investment.
- The traditional hammer crusher mostly changes the sieve plate to control the discharging particle size, while the modern hammer crusher controls the discharging particle size by adjusting the lining plate outlet with the spring device.
- Adjusting the clearance between the lining plate and the grinding chamber is also a way of adjusting the discharging size. Since the rotor of the hammer crusher is fixed, users can only adjust the position of the impact plate respectively to get the reasonable discharge clearance of the lining plate and the grinding chamber.
- The clearance of hammer crusher can be adjusted by mechanical or hydraulic means. The hydraulic adjustment system can be conveniently completed by local operation buttons or control system.
- The particle size is generally controlled through the wedge between the two rollers or shim adjustment device. When the wedge is pulled up, the gap between the two rollers becomes larger, and the grain size of the discharge becomes larger.
- When the wedge is downward, the size of the discharge becomes smaller. The shim adjustment device increases or decreases the number of shims to make the gap between rollers larger or smaller, so as to control the discharge size.
Further control by vibrating screen
The finished product of sand and stone production line includes not only the stone with smaller particle size, but also the stone with larger one. Sand and stone production is divided into crushing, screening, sand-making and other chains.
Sandstone aggregate quality control is mainly based on sandstone aggregate particle size and gradation requirements, and adopts the advanced and mature crushing equipment and vibrating screen, to ensure that the production of sand and stone aggregate is in line with the standards and regulations of grading quality.
In the sand and stone aggregate market, stones or sand the customers need to have a certain standard particle size, for example: gravel is divided into 5-10 mm, 10-20 mm, 16-31.5 mm, sand is divided into coarse sand (average particle size of 0.5 mm or more), medium sand (average particle size of 0.35-0.5 mm), fine sand (average particle size of 0.25-0.35 mm).
However, the materials are mixed with particles in various sizes, which cannot meet the demand. Therefore, most of the crushing process is equipped with a vibrating screen, which is used to classify the discharge materials and screen out the stones or sand of various specifications that they need. If the requirements are not met, they can return to the crusher to continue crushing.
The classification of the particles
Those materials whose size are less than the 3/4 size of the sieve hole of the particles can easily cross the sieve hole, known as easy-to-sieve particles. Particles larger than 3/4 of the sieve hole are difficult to pass through the sieve hole, known as difficult-to-sieve particles. Particles whose particle size is 1-1.5 times of the size of the sieve hole are called stoppers.
Therefore, the screening containing a large number of fine grade materials can increase the method of auxiliary screening of larger size in sieve hole to discharge the coarse size products in advance.
In general, single layer vibrating screen can screen out two kinds of materials, double-layers vibrating screen can screen out three kinds of materials, three-layers vibrating screen can screen out four kinds of materials, and five-layers vibrating screen can screen out six kinds. Users can make reasonable choices according to their needs for finished stones and sand and suggestions from equipment manufacturers.
Usually the circular vibrating screen is used to assist the crusher in the crushing production line. In the whole process, customers can adjust each device according to their own needs to adjust the material size. Through our analysis, do you have a general understanding of how to control the particle size in your sand and stone production?
We hope to help you to buy a suitable crusher and to operate your machines smoothly. Now many equipment manufacturers are designing production lines for customers. If you are new to this industry, you can listen to the suggestions of equipment manufacturers because they have professional knowledge and rich experience to help you solve problems.