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selection and purchasing guide of hammer crusher 

Hammer crushers are widely used in the cement industry. They are used for size reduction of hard to medium hard limestone, and sometimes for marl crushing. Hammer mills work with reduction ratios as high as 1 : 60; depending on the crusher feed, this ratio can increase to 1 : 80. Sometimes the high reduc­tion ratio of hammer crushers does away with the need for the installation of multi-stage crushing plants.

You will get efficient and thoughtful service from Shanbao.

. These crushers work with the impact effect of the hammers according to the formula for the kinetic energy or impact (P):

P= (m. V2)/ 2

Starting from this point the mass of the hammers in hammer mills was reduced to a minimum while at the same time increasing the velocity v as far as possible. The result was greater impact force combined with reduced wear.

In both types of crushers the crusher feed first passes through to upper or primary grid; this follows preli­ minary size reduction of the material by the impact hammers. The final crushing then occurs on the bars of the lower grid. Because of the two grids with differ­ent spacings, the hammer mills can be considered two-stage crushers. An adjustment of the grid spacing controls the final particle size; the final particle size is approximately equal to one half of the grid spacing. The grid spacing of the lower grid is generally 25- 30 mm. Higher moisture content of the crusher feed requires larger spacings up to 60 mm. Depending on the requirements, a spacing of 200 mm can also be applied. Moist and sticky crusher feed requires trian­gular grate bars; otherwise trapezoidal bars are in use.Since the primary grid sometimes caused operational disturbances, new models of hammer crushers are build without this grid.

The impact of the hammers upon the crusher feed is not even; this means the load upon  the  crusher  and the drive motor is not continuous. Massive flywheels are used to stabilize the operation. The double rotor crusher has separate drive motors for each shaft.

The weight of the replacable impact hammers  is in the range of 20 to 200 kg each, depending upon the crusher size. The chemical composition of the ham­mer steel is:

c     =   1.0-  1.4   %

Si    =    0.4-  1.0  %

Mn = 12.0-14.0  %

p      =    0.06%

Depending upon the hardness of the crusher feed, the specific wear of the impact hammers is 1.5 to 3.0 grams per ton of crushed material. The wear rate of Cr-Va-steel is 3 grams and that of Cr-Si-Va-steel was estimated to 2 grams per ton of crushed material [47].

The rim speed of the hammers is in the range of 25 to 50 m/s.

The number of revolutions of both the single and double rotor crushers is in the range of 250- 400 rpm, depending upon the crusher size.

The power demand of single rotor crushers  is between 1.3-2.8 HPh/t; double rotor crushers have an energy demand of 1.8-2.5 HPh/t of crushed material.

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the figure shows six different design modifications of impact hammers for hammer mills [47a].

To estimate the throughput capacity of a hammer breaker for limestone, the following empirical for­mula was developed:

Q = (40) · D · L

Q                Throughput of hammer breaker, m3/h

D                Rotor diameter of rotating hammers, meter

L            Useful length  of rotor, meter

Example 

Estimate the capacity of  a hammer breaker; D = 1.7 meter, L = 1.3 meter.

Q = 40 · 1.7 · 1.3 = 88 m3/h

Assuming  a bulk density of the crushed limestone of 1.6 t/m3, the capacity expressed in tons is

88 . 1.6 = 140 t/h

The required power input can be calculated using the following formula:

N = (0.1 – 0.15) x i x Q

N            Motor size, kW

i               Ratio of reduction

Q            Hammer mill capacity, tph

Another, more precise formula for the derivation of the required power input reads:

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Example :

Estimate the required power input for a double rotor hammer crusher with 2 x 16 hammers; weight of one hammer is 30 kg; speed of rotors is 250 rpm, rotor diameter is 1.0 meter, and power transmission factor is 0.85

Solution:

The rim speed for determining the £-factor is

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From  the  preceding  table  the  £-factor  for  26 m/s  is

0.008. Thus the required drive energy for both motors

is

Hence, two motors with 88 HP or 65 kW each should be provided; the next higher available motor size should be selected.

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Fig. 3.29. shows the cross-section and the operating diagram of a double rotor hammer crusher in stan­dard design

The following table  contains  technical  data for  the 0 + K double rotor hammer crusher “Titan” for crush­

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when to use Hammer Crusher ?

Hammer crusher used with material that have moisture content less than 12% , with compressive strength less than 120MPA , such as limestone, oil shale, slag, coal and so on.

Hammer crusher crushing concept

is very simple : the ore is crushed by the impact force of the hammer plus the impact force of the ore and the lining of grates and the impact force of the ore itself , the ore crush each others.

Hammer Crusher classifications :

hammer crusher can be classified into four types:

first classification: according to the number of rotors ( single rotor and double rotor )

second classification : according to the rotation direction ( reversible and nonreversible types )

third classification : according to the arrangement of hammers  ( into single row and multi-row types )

fourth classification : according to the different uses ( divided into two types of general purpose and special purpose)

1.1 Advantages and disadvantages of hammer crusher

Advantages of Hammer Crusher

1-simple structure

2-compact size

3-small weight

4-small power consumption

5- high productivity

6-Large crushing ratio

7-small and uniform size product

8-Less over crusher material

9- continuous and reliable work

10-easy maintenance and repair

11- consumable parts can be replaced easily

The disadvantage hammer crusher

1-The main working parts, such as: hammerhead, grate, linings, rotors, discs and other consumables  wear faster, especially when working on Materials have high hardness.

2- frequent material blockage occurs.

3- when Moisture exceed 15% or the ore mixed with clay materials productivity decrease and energy consumption increase

Hammer crusher specifications and models:

Hammer crusher are differentiated by  rotor diameter D and length L

Example :  фmm × mm hammer crusher.

it represents the diameter of the rotor D = mm, the rotor length L = mm.

Common models are:

Irreversible type: ф800mm × 600mm, фmm × 800mm, фmm × mm, фmm × mm, фmm × mm.

The reversible: фmm × mm, фmm × mm.

Hammer Crusher Purpose :

In metallurgy, mining, chemical, cement and other industrial sectors, every year a large number of raw materials and waste recycling need crusher processing,  to reach the required size for the next step in the mineral benification process. such as in cement industry the Limestone must be crushed then it’s introduced to the Raw mill with clay and iron ore then we take the output of the raw mill and introduce it to the kiln for firing and baking process to produce clinker , which go to the cement mill and we add Gypsum as additive to produce cement.

selection of the best Hammer Crusher depends on the Required Ore properties :

the physical composition  , the Mechanical  properties vary alot from ore to ore , so the key of success in choosing the  best Hammer crusher depends on the ore properties, when it addept the nature of the ore you will have the best crushing effect.

Common soft ore are: coal, galena, anthracitetheir compressive strength is between  2 ~ 4Mpa, Maximum don’t exceed 40Mpa. hardness coefficient is generally 2 to 4

another example, some of the hard minerals: granite, pure limonite, marble, etc., compressive strength is 120 ~ 150Mpa,  hardness factor is generally 12 to 15,

According to physical and mechanical properties of minerals, ore block shape and product size you can select the desired model perfectly.

Working principle and structure analysis of single – rotor hammer crusher:

the working principle of single rotor hammer crusher :

the main Axle is driven by Drive belt which is driven by the crusher motor , the main Axle move the kinetic energy to the Hammers , which impact the ore, and the main structure is lined with grate liners and at the  bottom of the crusher there is a sieve , if the size of the crusher ore is smaller than the mesh of the sieve the ore will go to the output of the crusher , if the size still bigger than the mesh of the iron sieve the ore will be crusher again by the impact hammers and by the grate liners and by the ore each others until it qualify the size of the sieve mesh

please watch the 4 seconds video to try to understand the working principles

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The overall structure of  schematic hammer crusher

1- 2- sieve  frame for  hammer Crusher 3- 4- 5- pin and main axle and adjusting device 6- 7- sieve frame access door

It mainly consists of housing, rotor, grate, pads, hammer, linings and other components.

the main component of Hammer Crusher:

1- Housing :

the housing of the Crusher is Opened from above and it’s lined with High manganese steel liners to be replaced based on wear and tear and it must be changed periodically to avoid the material leakage so a seal also must be installed. there are more than one manhole to facilitate the Maintenance and to easily change liners and Hammers.

2- Rotor :

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as shown in the above figure the rotor consist of shaft , Disk , Hammer Holder , Hammer Pins , and 6 Hanging Hammers on the Shaft . inorder to prevent the axial displacement and vibration both ends of the pin are locked with a locking Nut. the Rotor is supported by two self-aligning bearing. and inorder to store the kinetic energy there are two flywheels installed.

3- the Main Axle ( shaft )

the rotor shaft is the main part, it bear all the impact force . Therefore, the requirements of the material having a high strength and toughness, so 45 quenched and tempered steel  its circular cross section, and has flat keys and other parts of the connection. As shown in below figure

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4- Liners ( Hammer Crusher plates )

the Role of the Liners to absorb the Crusher Materials hits , to protect the crusher housing. after the collision with the liners if the material haven’t been crushed properly it will bound back to the Hammers to be crushed. Therefore the shape and structure of the Liners greatly influence the crushing process.

Two or three Breaker plates of Mn Steel casting are positioned to form an arc of the circle centered to the point of impact. The first plate is normally fixed in initial crushing zone. The second and the last plates are suspended from the frame through hinged connections. These are adjustable by heavy duty coil spring.

source : http://www.trf.co.in/pdf/Products/Impact%20Crusher.pdf 

you can see example of the Liners here https://www.williamscrusher.com/hammer-mills/traveling-breaker-plate-mills

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Want more information on single stage hammer crusher? Feel free to contact us.

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(5) hammers

Hammer is the main working parts. Its mass, shape, and material has a great influence on the production capacity of the crusher.

Thus, depending on the feed size to select the appropriate quality hammer. Hammer is wearing parts, often need to be replaced, in order to reduce the time required for replacement and labor intensity, I used modular hammer. 2.2 hammer can be used

Hammer with high-carbon steel casting or forging, can also be high manganese steel casting. In order to improve the wear resistance, and some hammer surface coated cemented carbide, and some high-chrome cast iron.

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(6) grate:

Grate arranged in the form of a direction of movement perpendicular to the hammer. And radius of gyration of the rotor have a certain gap arcuate qualified products through the discharge grate seam. Its cross-sectional shape of a trapezoid, a common cast manganese steel. Grate more as a set of steel bars of equal size, and the cross-sectional shape of the trapezoid.

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Rotor hammer crusher parameters calculation

Rotor diameter

The maximum diameter of the rotor can be calculated according to the Material block size with the below formula

D=(1.2 – 5 ) D(max) 

D: Diameter of the Rotor

D(max ) : The maximum feed size

as an Example if you will crush Limestone and the Maximum block size = 300 mm , Calculate the Hammer crsuher rotor Diameter ?

For medium-sized hammer crusher  , optional factor of 2.7, to take the middle value.

Therefore, D = 300 × 2.7 = 820mm

Rotor speed

Hammer crusher rotor speed according to the circumferential speed of the design, according to the formula

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v– rotor circumferential speed, m / s;

D– rotor diameter, m

Rotor circumferential speed is generally between 18 ~ 70m / s . For small and medium crusher, taking v = 25 ~ 70m / s, and the speed at 750 ~ r / min. Large crusher v = 18 ~ 25m / s, while the speed of 200 ~ 300r / min.

the higher the speed, the smaller the particle size, hammer, liner wear  is  faster, power consumption also increases, machining machine parts, installation accuracy requirements also will be increased to meet the particle size so the case The rotor circumferential speed should be selected low.

Take speed v 40m / s, then n = 931r / min.

Length of the rotor

Productivity and hammer crusher size, speed, discharge   gap width, feed size, feed conditions and material properties and other factors. according to formula

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Where Q– productivity, t / h;

D– rotor diameter, m;

P– density material, 1.6t /M3.

Taking K = 38;

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Calculation of mass hammer

Because it hinged to the rotor, so that the right choice has a significant impact on the quality of the hammer crushing efficiency and energy consumption, if the hammer have low quality , it may not meet the  material crushing requirements. If you choose too large, useless power consumption is too large, the centrifugal force is large, there will be an impact on other parts and make them easily damaged.

According to the Momentum theory to Calculate the Mass of the Hammer, when the Hammer Hit the Required Material to be crushed , there will be speed Loss. if this speed loss Exceeded Certain Level the Hammer will not Rotate around it’s axis and the hammer will stop revolving,

Summary：Stone crusher is an indispensable part of crushing, sand making, grinding and other processes. This article will tell you how to select the right crusher for your stone crusher business.

What's a stone crusher?

A stone crusher is a type of pulverizer that uses mechanical energy to break blocks of stone, concrete, or other building materials into smaller blocks of a specific grain size.

From very hard stones to soft minerals, crushers can be used for a very wide range of materials，they can be utilized in a variety of applications in industries such as mining industry to reduce the size of ore blocks and facilitate their processing，crushed stones previously used as building materials and demolition, crushing the debris left after the demolition of buildings, roads, bridges, canals and various other structures.

How to choose a right stone crusher?

Choosing the appropriate stone crusher is important for every operation, but how to choose a right stone crusher? There are several characteristics to consider:

1. Type and Hardness of Materials

The type and hardness of materials are the first factors to be considered in the selection of crushing equipment. Different types of materials will have different hardness and structure, which will have the primary limit on the selection of stone crusher. Generally, the greater the hardness, the higher the crushing difficulty coefficient.

2. Material Specification

If the material size is large, jaw crusher can be selected as primary crushing; When the size of stone is small and needs to be composed of stone with certain gradation, combined crushing and screening equipment shall be selected.

3. Humidity of Materials

The water content of the material will also affect the selection of the stone crusher. When the water content is too large, the fine materials will agglomerate or stick to the coarse materials due to the increase of humidity, so as to increase the viscosity of the materials, reduce the ore discharge speed and reduce the productivity. When it is serious, it will even block the ore discharge outlet and affect the normal production.

4. Granulometric Requirement

The incoming and outgoing particle size is used to judge the model and crushing level of the required crushing equipment.

5. Output Requirements

The output requirement is an important index to determine the crushing equipment. The higher the output requirement, the larger the required crushing equipment specification, and the corresponding input and output will increase.

6. Construction Site

The specific situation of the construction site is the most direct factor affecting the selection of crusher equipment, such as the site size of the construction site, the specific placement position of crushing equipment, etc.

7 Types of Stone Crusher

Understanding the application scope, technical advantages, and limitations of each stone crusher design enables operators can implement the best crushing solutions to maximize productivity and meet production targets.

These are the main stone crushers on the market:

• ➤ Jaw Crusher
• ➤ Cone Crusher
• ➤ Impact Crusher
• ➤ Mobile Crusher
• ➤ Sand Making Machine
• ➤ Hammer Crusher
• ➤ Roller Crusher

1. Jaw Crusher

The working mode of the jaw crusher is intermittent, and the rock material is crushed by squeezing the rock by the fixed jaw and the movable jaw. Some time ago, a friend left a message to consult the single pendulum jaw crusher. In fact, it is rarely used now, and the compound pendulum jaw crusher is mainly used.

Application: It is suitable for a wide range of materials, both soft and hard, especially the coarse and medium crushing of hard stones.

Advantages: simple structure, reliable work, lighter weight, cheap price, small size, low configuration height, large feed opening size, easy adjustment of the discharge opening opening, simple maintenance, and economical operating costs.

Disadvantages: The liner is easy to wear, and the content of needle flakes in the product is high, and feeding equipment is generally required.

2. Cone Crusher

The work of the cone crusher is continuous, using the eccentric movement of the moving cone to crush the stone. At the same time, due to the tangential movement of the moving cone and the fixed cone, the stone will also be subjected to shearing and grinding. Therefore, its working mechanism It is a combination of extrusion, shearing, and milling methods.

Application: Mainly used for medium or fine crushing of various stone materials. At the same time, according to its different structure (suspended shaft type and supporting shaft type), it can also be used for coarse stone crushing (suspended shaft type is used less).

Advantages: large crushing ratio, high efficiency, low energy consumption, less dust, uniform product size, stable operation, low failure rate, and not easy to be crushed.

Disadvantages: The structure and maintenance are more complicated, the body is high, and the price is expensive.

3. Impact Crusher

Impact crusher is a machine that uses impact energy to crush materials. Adjusting the gap between the counterattack frame and the rotor can achieve the purpose of changing the size and shape of the material discharged.

Application: Mainly used for medium crushing and fine crushing of stones below medium hardness, and the shape of the crushed stones is better.

Advantages: small size, simple structure, uniform product size, selective stone crushing, and high output.

Disadvantages: The blow hammer and the counterattack plate are particularly easy to wear, especially for crushing hard rocks, which are more severely worn and need to be replaced frequently; it is not suitable to crush plastic and viscous materials.

4. Mobile Crusher

Mobile crusher is a new type of equipment. It has been optimized and innovated in structural design, equipment configuration and combined application. The combination is more flexible, which greatly widens the application field of tire mobile crushing station and truly realizes the proximity treatment of materials.

Mobile crushers can be further subdivided into tire type mobile crushers and crawler type mobile crushers. Although they have certain differences in specific structure and operation performance, they both have the characteristics of convenience, flexibility, walking and stopping and local operation:

1. Integrated design of the whole machine. The structure is compact, integrating crushing, sand making, screening and transportation, and the carrying equipment is flexible and diverse.

2. Additional power traction and drive. The locomotive traction or diesel power shall be used for walking, and the operation site shall be transferred at any time according to the demand.

3. Wireless remote control operation. Compared with the traditional fixed crusher, one person can operate it remotely, which saves manpower and worry.

Understanding the crushing stage and the type of crusher best suited for each stage can simplify equipment selection. According to our practical application, the most suitable stone crusher is selected for our quarrying operations.

5. Sand Making Machine

The work of the impact sand making machine is continuous. It uses high-speed moving materials to strike iron, strike each other and friction between the materials to break. There are two crushing methods: "stone-on-rock" and "stone-on-iron".

Application: "Stone-on-Stone" is suitable for abrasive materials with medium-hardness and above. The finished product has a better grain shape and a little more powder content; "Stone-on-Iron" is suitable for materials with low abrasiveness and lower than medium-hardness, with high crushing efficiency. The wear cost of the guard plate is higher, and the finished grain is slightly worse.

Advantages: low energy consumption, high output, large crushing ratio, small size of the equipment, easy operation, convenient installation and maintenance, with shaping function, cubic product, high bulk density, and the machine's counterattack plate wears very much during operation Less.

Disadvantages: The maintenance is complicated and the cost is high. Generally, the maximum feed size does not exceed 60mm, which is suitable for fine crushing and sand making.

6. Hammer Crusher

The hammer crusher operates on a continuous crushing principle. As the high-speed rotor spins, the attached hammer heads deliver repeated blows to the feed material, effectively breaking down the stones and rocks.

Application: it is suitable for medium and fine crushing of medium and low hardness and non abrasive stones (compressive strength less than 100MPa). It can also be used for sand making when there are grate bars, but it has been rarely used.

Advantages: large crushing ratio, high output and more fine materials.

Disadvantages: the hammer head wears fast, needs to be replaced frequently, raises dust during work, and viscous materials with raw material moisture content greater than 12% cannot pass through effectively.

7. Roller Crusher

The work of the roller crusher is continuous. The stone is located between two parallel cylindrical rollers that move toward each other. The friction force between the stone and the roller bites the stone into the roller, facing the stone of the smooth roller. After being squeezed, the stones on the toothed roller are split and squeezed and broken.

Application: Mainly used for medium crushing and fine crushing of medium hardness stones (compressive strength below 100MPa) such as coal and limestone. Roll crusher is not used in road gravel processing.

Advantages: simple, compact structure, low investment, convenient adjustment, and can be used to crush viscous materials.

Disadvantages: low production efficiency, unable to crush hard materials.

What Is Primary, Secondary, and Tertiary Crushing?

If you want to buy a suitable rock crusher, you also need to know the multi-stage crushing stages is in a complete crushing production line. Stone crushers are classified according to the fineness with which they fragment the starting material. There are primary crushing, secondary (intermediate) crushing and tertiary crushing. Some production lines may include a single crushing stages，the most common production lines involve at least two or three crushing stages.

what is the crushing method?

Rock stone crusher is an indispensable part of crushing, sand making, grinding and other processes. However, there are many types of stone crushers on the market. How to choose suitable and satisfactory products?

Understanding the crushing method is very helpful for you to choose the right stone crusher. The crushing method refers to how rock particles are fractured during the crushing process. It is an important factor to consider when selecting the appropriate type of stone crusher.

Before understanding the stone crusher, it is necessary for us to have a simple understanding of the crushing method:

The stone crushing method is divided into compression, splitting, breaking, shearing, impact or blow, etc. Generally, multiple action modes are mixed, and there is no single action mode.

Compression crushing: The working face of the crushing machine exerts pressure on the material sandwiched between it, and the material is crushed when the compressive stress on the material reaches the limit of its compressive strength.

Splitting and shearing crushing: The edges of the crushing working surface are wedged into the material to generate tensile stress inside. When the value exceeds the tensile strength limit of the material, the material splits and locally produces powder at the point of contact between the sharp edge and the material.

Bending and breaking crushing: The materials clamped between the working surfaces, such as simply supported beams or multi-supported beams subjected to concentrated forces, are mainly subjected to bending stress, but are subject to splitting at the contact point of the working surface.

Compression and shearing: This combines both compression and shearing forces to fracture the material.

Impact crushing: Impact crushing involves high-speed movement of the crusher or material that strikes the material to be crushed. It includes:

• The high-speed impact of the moving crusher on the material.
• The impact of the material against a fixed surface.
• The mutual impact between moving materials.

This article introduces the key points of selecting a suitable stone crusher, multi-stage crushing and crushing methods. A multi-stage crushing process may be necessary, depending on the material's hardness and the desired output. By considering the crushing method, you can choose the equipment that best suits your operational requirements and performance goals.

We hope this guide helps you make a more informed decision when selecting your stone crusher!

For more information, please visit PV Jaw Crusher.