Cone crushers are continuous devices for grinding rock, as well as ores of different levels of hardness (medium, small). Their main difference from the jaw ones is that they do not have idling. After pieces of material of various fractions fall into the crusher, they are crushed between two movable semi-cones and a stationary bowl. This design is rational for grinding ore for ferrous and non-ferrous metallurgy, therefore , it was in this industry that such aggregates were most widely used. Let's talk about the device, the principle of operation and features of cone crushers.
Device classification
Currently, cone crushers are usually divided into devices of large (KKD), medium (KSD) and fine crushing (KMD).
QCD are characterized by the fact that they are able to accept pieces of rock from 400 to 1,200 mm with an exit slit of 75-300 mm. The productivity of such a unit is from 150 to 2,300 m 3 / h. Sometimes only cone crushers can cope with the tasks. Why so, you will learn a little later.
KSD have a cone size of 600-900 millimeters and can process pieces of ore from 60 to 300 mm, and at the output give a fraction of 12-60 mm. The productivity of such units is not less than 12 and not more than 580 m 3 / hour.
If we talk about CMD, then the receiver is designed for pieces of 35-100 mm, and at the output you can get elements of 3-15 mm. The productivity of such crushers is 12-220 m 3 / hour. If we consider the principle of operation of the unit in a few words, then we have approximately the following. The cone rotates. Clinging to one side of the fixed bowl, he crushes the ore, and when it moves to the other side, the fraction enters the exit slit. Then the cycle repeats.
Roller crusher
From the name it can be understood that a cylindrical roll acts as a working body. Material for crushing is fed from the loading device from above, then it falls between the rollers and is subjected to grinding.
Such crushers are classified according to the number of rolls. There are 1, 2 and 4-roller units. It is worth noting that in the latter case two two-roll crushers are mounted, which are located one above the other. The surface of the working body can be corrugated, smooth or jagged. In some cases, various combinations are used. For example, one roll is smooth, and the second is serrated or grooved. This is done to improve crushing and obtain the ore of the desired fraction.
An industrial roller crusher has a working body diameter of 400-500 millimeters with a length of 0.4-1.0 of the diameter. Currently, such aggregates are used to grind medium-sized rocks of small size.
Two-roll crushers, which are ideal for grinding wet and viscous materials, are widespread. In the process of work on the rolls a plaque is formed, which is removed by special scrapers. The gap between the rolls is set depending on the diameter of the fraction to be obtained. Well, now back to the cone crushers and consider them in more detail.
DIY crusher - it's easy and simple
As noted above, it is unrealistic to make a grinding device for an industrial scale with your own hands. But for exploitation in everyday life you can make something. Various improvised tools will be used.
Let's look at the simplest crusher option. This is the container in which the shaft is mounted on the bearings. The latter is equipped with several working bodies, for example, knives. We also need a low-power electric motor - let it be a 1 kW device, with which the shaft will be driven. The connection of the shaft and the motor is best realized by a belt drive with several wheels of different diameters. So it will be possible to adjust the rotation speed of the crusher knives.
What is this unit suitable for, you ask? Of course, it will not work to grind ore and other rocks, and we, in fact, do not need it. But such a hand-made crusher is quite suitable for processing cereals, grass, etc. In principle, in agriculture, the thing is necessary, especially since it is easy to craft it. But sometimes the simplest crushers can find their application in construction for grinding crushed stone or gravel.
As you can see, there is nothing complicated, you just need to find the right tools and parts for the future unit. You can increase the power of the crusher by installing another engine, say, by 5 or even 10 kW, but in this case it is better to replace the belt drive with gearing through a simple gearbox.
Crushed stone grinding equipment
Currently, crushed stone crusher may have some design features. What is a jaw crusher? The essence of her work is that the material gets between two cheeks (swinging plates) and is crushed. By adjusting the gap, crushed stone of various fractions can be obtained. When material of medium and small cubic shape is needed, cone crushers (CMD) are used for crushed stone. It is such a solution that is most common in construction. Do not forget about roll crushers. With their help, it is possible to obtain crushed stone of a small fraction.
I would like to dwell in more detail on cone crushers. The fact is that with their help you can get cube-shaped crushed stone, which is used for strewing roads and in construction for concrete.
It is worth noting that the cone crusher for gravel is good because it uses the technology of "stone on stone". It consists in the fact that constrained conditions are created under which approximately 30% of the gravel is crushed by friction against each other. But to implement this method, the work of the crusher is carried out under the rubble. The mobile cone with this approach is completely covered by rubble (“blockage”). There is a slight drawback in the form of coarsening of the fraction at the exit. For this, the discharge gap is slightly larger than the recyclable material.
On the advantages and disadvantages of cone crushers
There are many advantages and disadvantages that must be mentioned. Since the shape of the crushing surface does not form a regular cone, the crushing force can differ significantly at different stages and sections. But this is a forced action, which was achieved by changing the tilt angle of the cone along its height, which technology requires.
It is worth paying your attention to the fact that the main drawback of the cone crusher (CD) is its increased energy intensity. A little earlier it was said about how they achieve some savings during the operation of the device. In addition, the design itself is quite capacious and bulky, which in some cases complicates its operation.
Previously, they often encountered such a problem as jamming of the crusher due to the ingress of hard rock. Today, this drawback was eliminated by installing a spring suspension of the bowl to the frame. If necessary, the outlet gap increases in size, and a solid piece of rock falls down.
In recent years, the cone crusher has been slightly improved. The innovators' drawings had one distinctive feature - vibrators of an unbalanced type. The latter provide the movable cone with additional vibration, which makes crushing better. In addition, the advantages of CD include high performance. An important role is played by the continuity of the process, and the ability to start “with blockage,” that is, with a filled moving cone.
CD with hydraulic gap adjustment
We have said that unbalancers are considered innovative solutions. Despite the fact that the design of the crusher has become somewhat more complicated, it was possible to reduce the vibration of the unit during operation, and there is no need to erect large foundations, since there are practically no dynamic loads. All this improved the quality of crushing and productivity, however, the issue of energy consumption remained unchanged.
As for hydraulics in the design of the CD, this innovation has already taken root. This approach helped to achieve easier adjustment of the size of the slit at the exit.
The hydraulic device can also be used as a compensator, that is, a fuse. This is necessary when a solid piece of rock enters the working body. Hydraulic locks have also found their application, protecting bushings and drive units from dust and dirt, and, as a result, from increased wear. But today, not every company is capable of manufacturing such a unit. The most widespread cone crusher (KSD) with hydraulics "Ash-Werke", "Vedag" and other leaders in the production of such equipment. Well, now let's look at some more interesting nuances.
Cone Jaw Crusher
A few separate words should be said about the development of designers at Ash-Werke. The fact is that during the operation of the CDs, they encountered a problem - it is impossible to load large pieces of rock. To do this did not allow insufficient diameter of the hopper. The design solution was to create a unique form of a movable cone and a fixed bowl of CD. So, the upper part of the installation turned out to be gentle, which allowed loading large-scale rock there.
In the first section, the device works like a classic jaw crusher. In the middle and lower part of the unit, a gradual narrowing of the gap can be seen. As a result, it is a standard cone crusher (KSD) 600.
From the foregoing, we can conclude that this approach allows the use of large pieces of rock, as in jaw crushers, and at the output to obtain cube-shaped crushed stone, which is inherent only to CD.
Jaw crusher: principle of operation and advantages
The essence of crushing in such an aggregate is that the rock or ore is compressed between the cheeks, that is, the working bodies. One cheek is fixed and rigidly fixed, the second makes a swinging motion with the help of a connecting rod. Such crushers are classified in the same way as cone crushers, and there are large, medium and small crushing. The size of the fraction at the outlet depends on the size of the slit at the outlet, which can be controlled by a mechanical or hydraulic drive.
The working chamber has a wedge-shaped shape, here the ore is crushed. The material is loaded, crushed, and under gravity falls to the discharge hole.
Currently, several types of jaw crushers are used, which differ from each other by the trajectory of rocking the cheeks. They are divided into simple and complex. The latter are distinguished by more efficient crushing of rock and ore. But it is worth paying attention to the fact that it is extremely important to observe the optimum moisture content of the material. So, the SMD crusher can work with ore, the amount of moisture in which is no more than 6-8%. If this indicator increases by at least several percent, then productivity worsens several times.
Inertial CDs and their scope
We already talked a bit about such crushers in this article.
They are also called unbalanced and incorporate a vibration device. These units play an important role in the construction of roads (both automobile and railway). From this we can conclude that such a solution in construction organizations is extremely relevant.
Throughout the world, CDs with an eccentric drive are used, which makes it possible to simplify the adjustment and limit itself to changing only the discharge gap. This approach allows you to get crushed stone, which is 85% of the total output is cuboid, which is considered a very good result.
The main problem is the low oscillation frequency of the moving cone. If the frequency is increased, then dynamic oscillations increase, which leads to the destruction of the foundation. Designers are constantly striving to increase the cube shape of crushed stone, as this directly affects the quality and durability of roads.
Conclusion
So we talked about what CDs are, what are their structural differences, etc. You already know how to make a crusher, so if there is an urgent need, you can make a unit that, although it is not suitable for an industrial scale, will be quite suitable for consumer needs.
Alternative solutions exist, such as a jaw-cone crusher, which will be ideal when a conventional CD is not suitable. A separate issue is the price of the crusher. It is difficult to name specific numbers. The fact is that the more complex the unit, the greater the cost. Naturally, an aggregate of lower productivity, for example, KMD 600, will cost less than the KMD 1200. On average, you will have to pay about five thousand euros for the crusher.
Well, that’s all that can be said about cone crushers, which are indispensable for producing cube-shaped crushed stone, crushing rocks and ores of various sizes and hardness.