Miner liner
Publish: 2021-03-23 23:16:34
1. Ball mill is the key equipment to crush the material after it is crushed. Ball mill is divided into grid type ball mill and overflow type ball mill according to different ore discharge mode, which is the most common mill used in concentrator at present. Rubber liner of ball mill is a necessary equipment used in the mill, which is used to protect the cylinder from grinding. Ball mill rubber liner is widely used in cement, silicate procts, new building materials, refractories, chemical fertilizer, black and non-ferrous metal mineral processing, glass ceramics and other proction instries, dry or wet grinding of various ores and other grindable materials
according to different ore discharge methods, it can be divided into grid type and overflow type. The rubber lining board of the mill is mainly composed of the rubber lifting strip of the cylinder, the lining board of the cylinder and the lining board of the feed and discharge end. The rubber lining board with high wear resistance is mainly used to achieve the functions of wear resistance, anti-corrosion, impact resistance and noise rection. After years of practice and investigation by authoritative departments, Hebei Jiheng mine summed up the main reasons that affect the rubber liner of mill:
(1) rubber quality
the quality of rubber liner is directly determined by the quality of rubber material. The rubber materials used for ball mill rubber lining processing should not only have high wear resistance, but also have high elasticity
(2) instrial and mining conditions of the mill
different ball mill rubber lining should be selected according to different grinding conditions, such as wear resistance, corrosion resistance, high temperature resistance, etc. Poor selection of rubber lining of ball mill will directly affect the service life of ball mill and bring unnecessary trouble to your enterprise. Therefore, the reasonable selection of rubber's anti-wear ability, elasticity, impact absorption ability and anti cutting ability has a great influence on the service life of rubber lining. The form and working environment of rubber lining are complex and diverse. Hebei Jiheng has professional technicians to carry out on-site measurement, measure and customize the machine, and design the rubber lining in line with the ball mill. Maximum guarantee the correctness of proct selection
(3) fixation method
the consolidation method of rubber liner lifting strip of ball mill has a great influence on the use of liner. Hebei Jiheng will have professionals for on-site installation and after-sales service
(4) medium size and feed particle size
the diameter of steel ball and feed particle directly affect the service life of rubber liner of ball mill. The main parameters that affect the service life of rubber liner and mill effect are: feed particle size, steel ball diameter, ore hardness and particle shape, mill speed and pulp concentration, etc. It is difficult to use rubber liner in the first stage ball mill of metal mines in China. The main reason is that the feeding particle size of the first stage ball mill is very large, generally 18-26mm. The diameter of the steel ball is very large. The diameter of the ball in the magnetic separation plant is generally 125-127mm, and that in the flotation plant is generally 100mm;. The rotational speed of the mill is too high, up to 85% of the critical speed, which increases the new difficulty for the successful application of the rubber liner of the first stage ball mill. In the successful application of rubber liner in the first stage ball mill of metal mine, the most important and key is the service life of rubber strip liner
(5) temperature
when the temperature exceeds the service temperature of rubber itself,
according to different ore discharge methods, it can be divided into grid type and overflow type. The rubber lining board of the mill is mainly composed of the rubber lifting strip of the cylinder, the lining board of the cylinder and the lining board of the feed and discharge end. The rubber lining board with high wear resistance is mainly used to achieve the functions of wear resistance, anti-corrosion, impact resistance and noise rection. After years of practice and investigation by authoritative departments, Hebei Jiheng mine summed up the main reasons that affect the rubber liner of mill:
(1) rubber quality
the quality of rubber liner is directly determined by the quality of rubber material. The rubber materials used for ball mill rubber lining processing should not only have high wear resistance, but also have high elasticity
(2) instrial and mining conditions of the mill
different ball mill rubber lining should be selected according to different grinding conditions, such as wear resistance, corrosion resistance, high temperature resistance, etc. Poor selection of rubber lining of ball mill will directly affect the service life of ball mill and bring unnecessary trouble to your enterprise. Therefore, the reasonable selection of rubber's anti-wear ability, elasticity, impact absorption ability and anti cutting ability has a great influence on the service life of rubber lining. The form and working environment of rubber lining are complex and diverse. Hebei Jiheng has professional technicians to carry out on-site measurement, measure and customize the machine, and design the rubber lining in line with the ball mill. Maximum guarantee the correctness of proct selection
(3) fixation method
the consolidation method of rubber liner lifting strip of ball mill has a great influence on the use of liner. Hebei Jiheng will have professionals for on-site installation and after-sales service
(4) medium size and feed particle size
the diameter of steel ball and feed particle directly affect the service life of rubber liner of ball mill. The main parameters that affect the service life of rubber liner and mill effect are: feed particle size, steel ball diameter, ore hardness and particle shape, mill speed and pulp concentration, etc. It is difficult to use rubber liner in the first stage ball mill of metal mines in China. The main reason is that the feeding particle size of the first stage ball mill is very large, generally 18-26mm. The diameter of the steel ball is very large. The diameter of the ball in the magnetic separation plant is generally 125-127mm, and that in the flotation plant is generally 100mm;. The rotational speed of the mill is too high, up to 85% of the critical speed, which increases the new difficulty for the successful application of the rubber liner of the first stage ball mill. In the successful application of rubber liner in the first stage ball mill of metal mine, the most important and key is the service life of rubber strip liner
(5) temperature
when the temperature exceeds the service temperature of rubber itself,
2. It's better to use ladder lining board in one warehouse, it's used for a long time, and the price is cheap. Corrugated lining plate for the second bin. It's better to load steel balls in one warehouse, steel sections in two warehouses or 25, 30 steel balls!
3. Common faults and troubleshooting of ball mill
pitting corrosion or melting phenomenon of main bearing e to high temperature may be caused by one of the following reasons:
interruption of lubricating oil or insufficient oil quantity. In case of oil interruption, stop feeding water supply immediately, open the observation hole cover on the bearing, try to approach the hollow journal by hand (pay attention to prevent handle scalding) and check the bearing temperature. If the bearing is not overheated, it can be stopped to deal with the oil circuit fault; If the temperature of the bearing is quite high and the hand is close to the hollow journal and feels hot and smoking, do not stop the machine. Manually pour oil on the bearing to cool it until the temperature of the bearing returns to normal. If the engine is stopped without cooling measures, not only the bearing will not be burned out, but also the hollow shaft and big bearing will lock up
if the lubricating oil is too thick or too thin, it can be eliminated by re selecting the type of lubricating oil; Stop using cooling water or resistance heating
if the oil deteriorates, clean the bearing and oil passing parts and replace the lubricating oil
if the grinding and scraping of the big tile does not meet the requirements, the big tile should be re grinded and scraped to make it meet the technical requirements
impurities such as mineral sand and iron chips fall into the bearing surface, causing damage to the bearing surface and causing marks and grooves on the bearing surface
elimination method: clean the bearing, repair the bearing and journal, if the melting area is large, weld the bearing with welding gun or cast Babbitt alloy again, and change the lubricating oil
there is water in the lubricating oil, which can prevent the formation of oil film and proce cracks and pitting corrosion at local points without oil film
elimination method: clean the bearing and change the lubricating oil
it is difficult to start the mill, the starting current of the motor is large, and there is overload.
causes and elimination methods:
the medium in the mill agglomerates with the ore, and the center of gravity deviates from one side of the cylinder seriously. In this case, when driving the mill, the motor is not enough to overcome the eccentric moment, and cannot drive the mill, resulting in overload
elimination method: open the hole cover, enter the cylinder, turn the medium with a crowbar, and unload part of the medium
the unbalanced three-phase load of motor mainly refers to the unbalanced three-phase current of motor. The rotor of the motor is driven by the electromagnetic torque (i.e. rotating magnetic field) generated by the three-phase power supply passing through the stator winding. When the three-phase current through the stator winding is balanced, the electromagnetic torque generated is also balanced. If a certain phase current is caused by poor contact of conctor joint or leakage, poor winding insulation, etc., the current will be weakened, and the electromagnetic torque generated by this phase current passing through the stator winding will also be reced, so it is difficult for the mill to start and the motor will be overloaded
elimination method: disconnect the motor from the gearbox, start the motor under no load, check the current of each phase with a clamp ammeter, and check the winding of the motor when the current is abnormal, such as checking the insulation with a megger, find out the cause, and then start the motor after treatment
there are ore or steel balls in the feeding box. For closed-circuit grinding, if the ore and steel balls from the bulging belly of the grinding machine are not removed from the feeding box, or after the grinding is stopped, the classifier is not stopped in time, so that the returned sand can be accumulated in the feeding box. When the mill is started, the feeding scoop is blocked, resulting in a large eccentric torque, which causes the motor overload
Troubleshooting: open the treatment hole at the bottom of the feeder box and clean up the ore and steel balls
there is slurry leakage from the connecting bolt of cylinder liner plate
causes: the nut fixing the liner plate is loose, the sealing gasket is damaged, the screw is broken, the liner plate is broken or falls off, etc
Troubleshooting: tighten or replace the bolts, add sealing washer, and replace the liner if necessary
the sound inside the grinding machine is weakened or enhanced
the main reason for the weakening of the sound inside the grinding machine is that the feeding amount is too much, the block is too large, the feeding amount is greater than the discharge amount, and the grinding machine begins to swell
the exclusion method was treated as the exclusion method
the increased sound in the mill may be e to too little feeding, resulting in empty grinding, and the medium directly strikes the liner or the medium strikes each other. When the feeding is normal and the sudden sound intensifies, it is caused by the lining plate or grid plate falling off
elimination method: increase the feeding amount. If the liner falls off, stop the machine immediately to replace or reassemble the liner
the grinding machine suddenly proces strong vibration and impact sound. One of the following reasons will cause the above phenomenon:
iron impurities are mixed in the gear clearance. The elimination method: stop the machine immediately and trim the tooth surface
the pinions move in series in the axial direction and collide with the gearbox. The elimination method: stop immediately, replace the gearbox and fix the gears along the axial direction again
if the gear is damaged, the elimination method is to stop immediately and replace the gear
if the bearing or anchor bolt is loose, the elimination method: first adjust the gear to make the big and small gears mesh correctly, and then tighten the bolt.
pitting corrosion or melting phenomenon of main bearing e to high temperature may be caused by one of the following reasons:
interruption of lubricating oil or insufficient oil quantity. In case of oil interruption, stop feeding water supply immediately, open the observation hole cover on the bearing, try to approach the hollow journal by hand (pay attention to prevent handle scalding) and check the bearing temperature. If the bearing is not overheated, it can be stopped to deal with the oil circuit fault; If the temperature of the bearing is quite high and the hand is close to the hollow journal and feels hot and smoking, do not stop the machine. Manually pour oil on the bearing to cool it until the temperature of the bearing returns to normal. If the engine is stopped without cooling measures, not only the bearing will not be burned out, but also the hollow shaft and big bearing will lock up
if the lubricating oil is too thick or too thin, it can be eliminated by re selecting the type of lubricating oil; Stop using cooling water or resistance heating
if the oil deteriorates, clean the bearing and oil passing parts and replace the lubricating oil
if the grinding and scraping of the big tile does not meet the requirements, the big tile should be re grinded and scraped to make it meet the technical requirements
impurities such as mineral sand and iron chips fall into the bearing surface, causing damage to the bearing surface and causing marks and grooves on the bearing surface
elimination method: clean the bearing, repair the bearing and journal, if the melting area is large, weld the bearing with welding gun or cast Babbitt alloy again, and change the lubricating oil
there is water in the lubricating oil, which can prevent the formation of oil film and proce cracks and pitting corrosion at local points without oil film
elimination method: clean the bearing and change the lubricating oil
it is difficult to start the mill, the starting current of the motor is large, and there is overload.
causes and elimination methods:
the medium in the mill agglomerates with the ore, and the center of gravity deviates from one side of the cylinder seriously. In this case, when driving the mill, the motor is not enough to overcome the eccentric moment, and cannot drive the mill, resulting in overload
elimination method: open the hole cover, enter the cylinder, turn the medium with a crowbar, and unload part of the medium
the unbalanced three-phase load of motor mainly refers to the unbalanced three-phase current of motor. The rotor of the motor is driven by the electromagnetic torque (i.e. rotating magnetic field) generated by the three-phase power supply passing through the stator winding. When the three-phase current through the stator winding is balanced, the electromagnetic torque generated is also balanced. If a certain phase current is caused by poor contact of conctor joint or leakage, poor winding insulation, etc., the current will be weakened, and the electromagnetic torque generated by this phase current passing through the stator winding will also be reced, so it is difficult for the mill to start and the motor will be overloaded
elimination method: disconnect the motor from the gearbox, start the motor under no load, check the current of each phase with a clamp ammeter, and check the winding of the motor when the current is abnormal, such as checking the insulation with a megger, find out the cause, and then start the motor after treatment
there are ore or steel balls in the feeding box. For closed-circuit grinding, if the ore and steel balls from the bulging belly of the grinding machine are not removed from the feeding box, or after the grinding is stopped, the classifier is not stopped in time, so that the returned sand can be accumulated in the feeding box. When the mill is started, the feeding scoop is blocked, resulting in a large eccentric torque, which causes the motor overload
Troubleshooting: open the treatment hole at the bottom of the feeder box and clean up the ore and steel balls
there is slurry leakage from the connecting bolt of cylinder liner plate
causes: the nut fixing the liner plate is loose, the sealing gasket is damaged, the screw is broken, the liner plate is broken or falls off, etc
Troubleshooting: tighten or replace the bolts, add sealing washer, and replace the liner if necessary
the sound inside the grinding machine is weakened or enhanced
the main reason for the weakening of the sound inside the grinding machine is that the feeding amount is too much, the block is too large, the feeding amount is greater than the discharge amount, and the grinding machine begins to swell
the exclusion method was treated as the exclusion method
the increased sound in the mill may be e to too little feeding, resulting in empty grinding, and the medium directly strikes the liner or the medium strikes each other. When the feeding is normal and the sudden sound intensifies, it is caused by the lining plate or grid plate falling off
elimination method: increase the feeding amount. If the liner falls off, stop the machine immediately to replace or reassemble the liner
the grinding machine suddenly proces strong vibration and impact sound. One of the following reasons will cause the above phenomenon:
iron impurities are mixed in the gear clearance. The elimination method: stop the machine immediately and trim the tooth surface
the pinions move in series in the axial direction and collide with the gearbox. The elimination method: stop immediately, replace the gearbox and fix the gears along the axial direction again
if the gear is damaged, the elimination method is to stop immediately and replace the gear
if the bearing or anchor bolt is loose, the elimination method: first adjust the gear to make the big and small gears mesh correctly, and then tighten the bolt.
4. It can be summarized into three aspects: ore properties, mill structure and operating conditions
(1) the influence of ore properties, feed particle size and proct particle size
a the influence of ore properties on the operation of the mill can be compared and measured by the grindability of ore (that is, the difficulty of grinding ore from a certain particle size to a specified particle size). Different ores have different grindability, which is mainly related to their mineral composition, mechanical strength, dissemination characteristics and grinding ratio. The ore with compact structure, small crystal and high hardness has low grindability, which needs more energy consumption and low proctivity; On the contrary, the coarse crystalline, loose, soft and brittle ore has high grindability, high proctivity of grinding machine and low energy consumption per unit
b feed particle size
the feed particle size of grinding machine has a great influence on the grinding process. The smaller the feed size is, the shorter the grinding time to the specified fineness is, the higher the processing capacity of the mill is, and the lower the unit grinding energy consumption is< However, the appropriate feed size of the mill can only be determined after considering the total cost of crushing and grinding
C proct size
when the feed size and other conditions are the same, the finer the grinding proct, the lower the proctivity of the mill and the higher the unit energy consumption
(2) the influence of mill structure
grinding is carried out in the mill, and the structure of the mill (including its type, diameter, length and liner shape, etc.) has a great influence on the grinding effect< Under the same conditions, the proction capacity of lattice ball mill is 10% ～ 25% higher than overflow ball mill of the same specification
b the diameter and length of the mill
the diameter of the mill directly determines the ball load pressure on the ground material and the impact force of the steel ball falling. The larger the diameter, the greater the pressure and impact of grinding medium on the ore particles, and the higher the working efficiency of the grinding machine
the length and diameter of the mill together determine the volume of the mill, so it also determines its proction capacity. If the length of ball mill with the same diameter increases, its proctivity will increase proportionally
the length of grinding machine also affects the fineness of grinding procts. When the ore quantity is fixed, the longer the mill length is, the longer the ore stays in the cylinder, and the finer the grinding proct size is
C lining plate of grinding machine
because the external energy is transferred to the grinding medium through the cylinder lining plate, which makes it proce the motion state meeting the grinding requirements, the shape and material of the lining plate have a great influence on the working effect, energy consumption and steel consumption of the grinding machine
(3) the influence of grinding operation conditions
the operation factors that affect the grinding process include: grinding medium loading system, grinding concentration, feeding speed, grinding machine speed, return sand ratio, classification efficiency and the addition of grinding aids, etc.
a the influence of grinding medium loading system
grinding medium and its loading system are the prerequisite for obtaining good grinding indexes, Therefore, each concentrator must find out the most suitable medium loading system through instrial proction test according to the characteristics of the ore and the quality requirements of the grinding procts
(a) the shape and material of the grinding medium, as the grinding medium that directly grinds the material, should meet and take into account two requirements: one is to have as large a surface area as possible to provide an appropriate surface in contact with the material to be grinded; The second is to have as much mass as possible to have the necessary energy for grinding materials. It is self-evident that these two requirements must be related to the shape of the medium and the material used
(b) the size and proportion of grinding media are related to the strength of their impact, extrusion and grinding effect on the material in the grinding machine, which directly affects the grinding effect. When determining the medium size, the main consideration is the properties and particle size composition of the ground ore. Taking the ball mill as an example, when dealing with the ore with large hardness and coarse particle size, it needs a larger impact force, so it should be loaded with larger steel balls; When the ore is soft, the feed particle size is small, and the required grinding proct particle size is fine, the smaller steel ball should be loaded to increase the contact surface between the steel ball and the ground material and enhance the grinding effect. The diameter and speed of the mill should also be considered when selecting the medium size. The grinding machine with large diameter and high speed can transfer more energy to the medium, so the medium with smaller size can be used to increase its number and improve the grinding efficiency
the feed of instrial proction grinding machine is composed of different particle sizes, so the grinding medium loaded into the grinding machine should also have different sizes. Only by keeping the quality proportion of medium of various sizes of the mill in line with the particle size composition of the material to be grinded, can good grinding effect be achieved. The experience summed up from long-term grinding practice is that coarse ore particles should be broken with large steel balls, and fine ore particles should be ground with small steel balls. When the quality of steel balls loaded into the mill is fixed, the number of steel balls with small diameter is more, the number of times of each batch of steel balls falling and hitting is more, the grinding area is also large, but the hitting force of each ball is small; The number of balls with large diameter is less, the number of times of each batch of steel balls falling and hitting is less, the grinding area is also small, but the hitting force of each ball is large. The proportioning of steel balls with various diameters loaded into the grinding machine should not only have enough impact force to just break the coarse ore particles in the feed, but also have more striking times and stronger grinding effect to fine the finer ore particles
(c) loading capacity of grinding medium
when the diameter, length and rotation rate of the grinding machine are fixed, the useful power of the grinding machine increases with the increase of the ball loading rate and the proction capacity increases within the range of ball loading rate not exceeding 50%. However, different speeds have different limit ball loading rate. When the ball mill is operated within the critical speed, the ball loading rate is usually 40% - 50%
(d) reasonable addition of grinding medium
the grinding medium itself is constantly worn in the process of grinding materials, and the larger ones graally become smaller ones, and finally are completely worn out or become fragments and discharged from the grinding machine. In order to keep a proper proportion of media with different sizes in the grinding process and keep the media filling rate unchanged, a certain size and quantity of new media must be added to the grinding machine every day to compensate the worn media quality
practice has proved that the grinding effect can be improved by adding several sizes of steel balls in proper proportion
in order to reasonably add steel balls, the total ball load and its particle size composition of the ball mill should be checked regularly on site to understand the wear of steel balls of various sizes, so as to continuously correct the quality and proportion of steel balls added in proction, and graally make the particle size composition of steel balls in the mill keep close to that of the original ball loading. If there are too many broken balls with irregular shape left in the ball mill after wear, the grinding effect will be affected and they should be removed regularly. The cleaning period varies with the material of the ball. Iron balls are usually cleaned once every 2-4 months, while steel balls are cleaned once every 6-10 months< When other conditions remain unchanged, the movement state of grinding medium in the cylinder depends on the rotation speed of the mill. The grinding effect is not the same with different media movement state. When the rotation speed of the mill is low, the medium is mainly in the form of falling motion, and the impact is small. The grinding function is mainly grinding, and the proction capacity of the mill is low, so it is suitable for fine grinding; When the rotation speed is high, the proportion of medium throwing motion is large, and the impact effect is strong. The grinding effect is mainly impact, followed by grinding stripping, which is concive to crushing coarse-grained materials, and the mill has high proction capacity
the suitable working speed of the mill is 76% and 88% of the critical speed respectively. The speed rate of most ball mills manufactured in China is between 75% and 80%, which is slightly lower than the theoretical calculation value. In the actual proction, the appropriate speed of the grinding machine should be determined by long-term proction comparison test. In the comparison, not only the proction capacity of the grinding machine, but also the power consumption, steel consumption and economic benefits
of course, if the proction capacity of the grinding machine can not reach the design output quota, appropriately increasing the speed of the grinding machine is still one of the effective measures to improve the processing capacity of the concentrator. However, with the increase of grinding speed, the vibration and wear of the mill become more and more serious, so it is necessary to strengthen the management and maintenance. On the contrary, if the mill has surplus proction capacity, its speed should be appropriately reced to rece energy consumption, steel consumption and grinding cost
C influence of grinding concentration
grinding concentration refers to the concentration of pulp in the grinding machine ring normal operation, which can be expressed by either the percentage of solid content (by mass) in pulp or the ratio of liquid mass to solid mass in pulp (referred to as liquid-solid ratio concentration). The discharge concentration of the mill is its grinding concentration
the pulp concentration in the mill has a direct impact on the grinding effect of the medium, the flow performance of the pulp itself and the settling speed of the ore particles. When the grinding concentration is high, the buoyancy of the medium in the slurry is large, the effective density is reced, the impact of the falling is weakened, and the striking effect is poor. When the content of solid ore particles in the slurry is high, the slurry viscosity is high, and there are more ore particles adhered around the medium, the probability of medium hitting and grinding ore particles increases, and the grinding efficiency increases. This is because the fine grinding effect of the grinding machine mainly depends on the grinding vibration crack effect when the grinding medium is in circular motion. However, the grinding concentration should not be too high, otherwise the impact force and grinding activity of the medium will be greatly reced, and the grinding efficiency will be reced; In addition, the slurry is too thick, the slurry fluidity is poor, the coarse material sinks slowly, the overflow ball mill is easy to run out of coarse sand, and the lattice ball mill may be blocked, resulting in "bulge". When the pulp concentration is low, the effective density of the medium in the pulp is large, and the impact force is strong when it falls, but the pulp viscosity is low, the ore particles adhering to the surface of the medium are less, the grinding effect is reced, and the wear of the medium and lining plate is increased. At the same time, when the slurry is too thin, the fine ore particles are easy to sink in the overflow ball mill, resulting in more over crushing. Therefore, it is not good if the pulp concentration is too high or too low, and the appropriate grinding concentration should be determined according to the ore properties, feed and proct particle size and medium characteristics. Generally speaking, the grinding concentration should be higher when dealing with ores with coarse feed size, high hardness and high density; When the ore with fine feed size, low hardness and low density is treated, the grinding concentration is lower
d influence of return sand ratio and classification efficiency in grinding cycle
the classification efficiency and return sand ratio in closed-circuit grinding cycle have a great influence on the proction capacity of grinding machine and the quality of grinding procts: that is, the higher the classification efficiency or return sand ratio is, the greater the proction capacity of grinding machine is, and the less the over crushed particles are. At present, the classification efficiency of concentrator is generally 40% ～ 60%, and the return sand ratio of closed circuit grinding is 200% ～ 350%
e influence of feeding speed
feeding speed refers to the amount of ore fed into the mill per unit time. When the feeding speed is too low and the ore quantity is insufficient, the lining plate will be broken by empty medium in the mill, the wear will be intensified, and the proct will be over crushed seriously; When the feeding speed is too fast and the amount of ore is too much, the mill will be overloaded, and there will be the discharge of steel balls, the discharge of large ore blocks and the gushing of pulp, and the grinding process will be damaged
F effect of grinding aids
(1) the influence of ore properties, feed particle size and proct particle size
a the influence of ore properties on the operation of the mill can be compared and measured by the grindability of ore (that is, the difficulty of grinding ore from a certain particle size to a specified particle size). Different ores have different grindability, which is mainly related to their mineral composition, mechanical strength, dissemination characteristics and grinding ratio. The ore with compact structure, small crystal and high hardness has low grindability, which needs more energy consumption and low proctivity; On the contrary, the coarse crystalline, loose, soft and brittle ore has high grindability, high proctivity of grinding machine and low energy consumption per unit
b feed particle size
the feed particle size of grinding machine has a great influence on the grinding process. The smaller the feed size is, the shorter the grinding time to the specified fineness is, the higher the processing capacity of the mill is, and the lower the unit grinding energy consumption is< However, the appropriate feed size of the mill can only be determined after considering the total cost of crushing and grinding
C proct size
when the feed size and other conditions are the same, the finer the grinding proct, the lower the proctivity of the mill and the higher the unit energy consumption
(2) the influence of mill structure
grinding is carried out in the mill, and the structure of the mill (including its type, diameter, length and liner shape, etc.) has a great influence on the grinding effect< Under the same conditions, the proction capacity of lattice ball mill is 10% ～ 25% higher than overflow ball mill of the same specification
b the diameter and length of the mill
the diameter of the mill directly determines the ball load pressure on the ground material and the impact force of the steel ball falling. The larger the diameter, the greater the pressure and impact of grinding medium on the ore particles, and the higher the working efficiency of the grinding machine
the length and diameter of the mill together determine the volume of the mill, so it also determines its proction capacity. If the length of ball mill with the same diameter increases, its proctivity will increase proportionally
the length of grinding machine also affects the fineness of grinding procts. When the ore quantity is fixed, the longer the mill length is, the longer the ore stays in the cylinder, and the finer the grinding proct size is
C lining plate of grinding machine
because the external energy is transferred to the grinding medium through the cylinder lining plate, which makes it proce the motion state meeting the grinding requirements, the shape and material of the lining plate have a great influence on the working effect, energy consumption and steel consumption of the grinding machine
(3) the influence of grinding operation conditions
the operation factors that affect the grinding process include: grinding medium loading system, grinding concentration, feeding speed, grinding machine speed, return sand ratio, classification efficiency and the addition of grinding aids, etc.
a the influence of grinding medium loading system
grinding medium and its loading system are the prerequisite for obtaining good grinding indexes, Therefore, each concentrator must find out the most suitable medium loading system through instrial proction test according to the characteristics of the ore and the quality requirements of the grinding procts
(a) the shape and material of the grinding medium, as the grinding medium that directly grinds the material, should meet and take into account two requirements: one is to have as large a surface area as possible to provide an appropriate surface in contact with the material to be grinded; The second is to have as much mass as possible to have the necessary energy for grinding materials. It is self-evident that these two requirements must be related to the shape of the medium and the material used
(b) the size and proportion of grinding media are related to the strength of their impact, extrusion and grinding effect on the material in the grinding machine, which directly affects the grinding effect. When determining the medium size, the main consideration is the properties and particle size composition of the ground ore. Taking the ball mill as an example, when dealing with the ore with large hardness and coarse particle size, it needs a larger impact force, so it should be loaded with larger steel balls; When the ore is soft, the feed particle size is small, and the required grinding proct particle size is fine, the smaller steel ball should be loaded to increase the contact surface between the steel ball and the ground material and enhance the grinding effect. The diameter and speed of the mill should also be considered when selecting the medium size. The grinding machine with large diameter and high speed can transfer more energy to the medium, so the medium with smaller size can be used to increase its number and improve the grinding efficiency
the feed of instrial proction grinding machine is composed of different particle sizes, so the grinding medium loaded into the grinding machine should also have different sizes. Only by keeping the quality proportion of medium of various sizes of the mill in line with the particle size composition of the material to be grinded, can good grinding effect be achieved. The experience summed up from long-term grinding practice is that coarse ore particles should be broken with large steel balls, and fine ore particles should be ground with small steel balls. When the quality of steel balls loaded into the mill is fixed, the number of steel balls with small diameter is more, the number of times of each batch of steel balls falling and hitting is more, the grinding area is also large, but the hitting force of each ball is small; The number of balls with large diameter is less, the number of times of each batch of steel balls falling and hitting is less, the grinding area is also small, but the hitting force of each ball is large. The proportioning of steel balls with various diameters loaded into the grinding machine should not only have enough impact force to just break the coarse ore particles in the feed, but also have more striking times and stronger grinding effect to fine the finer ore particles
(c) loading capacity of grinding medium
when the diameter, length and rotation rate of the grinding machine are fixed, the useful power of the grinding machine increases with the increase of the ball loading rate and the proction capacity increases within the range of ball loading rate not exceeding 50%. However, different speeds have different limit ball loading rate. When the ball mill is operated within the critical speed, the ball loading rate is usually 40% - 50%
(d) reasonable addition of grinding medium
the grinding medium itself is constantly worn in the process of grinding materials, and the larger ones graally become smaller ones, and finally are completely worn out or become fragments and discharged from the grinding machine. In order to keep a proper proportion of media with different sizes in the grinding process and keep the media filling rate unchanged, a certain size and quantity of new media must be added to the grinding machine every day to compensate the worn media quality
practice has proved that the grinding effect can be improved by adding several sizes of steel balls in proper proportion
in order to reasonably add steel balls, the total ball load and its particle size composition of the ball mill should be checked regularly on site to understand the wear of steel balls of various sizes, so as to continuously correct the quality and proportion of steel balls added in proction, and graally make the particle size composition of steel balls in the mill keep close to that of the original ball loading. If there are too many broken balls with irregular shape left in the ball mill after wear, the grinding effect will be affected and they should be removed regularly. The cleaning period varies with the material of the ball. Iron balls are usually cleaned once every 2-4 months, while steel balls are cleaned once every 6-10 months< When other conditions remain unchanged, the movement state of grinding medium in the cylinder depends on the rotation speed of the mill. The grinding effect is not the same with different media movement state. When the rotation speed of the mill is low, the medium is mainly in the form of falling motion, and the impact is small. The grinding function is mainly grinding, and the proction capacity of the mill is low, so it is suitable for fine grinding; When the rotation speed is high, the proportion of medium throwing motion is large, and the impact effect is strong. The grinding effect is mainly impact, followed by grinding stripping, which is concive to crushing coarse-grained materials, and the mill has high proction capacity
the suitable working speed of the mill is 76% and 88% of the critical speed respectively. The speed rate of most ball mills manufactured in China is between 75% and 80%, which is slightly lower than the theoretical calculation value. In the actual proction, the appropriate speed of the grinding machine should be determined by long-term proction comparison test. In the comparison, not only the proction capacity of the grinding machine, but also the power consumption, steel consumption and economic benefits
of course, if the proction capacity of the grinding machine can not reach the design output quota, appropriately increasing the speed of the grinding machine is still one of the effective measures to improve the processing capacity of the concentrator. However, with the increase of grinding speed, the vibration and wear of the mill become more and more serious, so it is necessary to strengthen the management and maintenance. On the contrary, if the mill has surplus proction capacity, its speed should be appropriately reced to rece energy consumption, steel consumption and grinding cost
C influence of grinding concentration
grinding concentration refers to the concentration of pulp in the grinding machine ring normal operation, which can be expressed by either the percentage of solid content (by mass) in pulp or the ratio of liquid mass to solid mass in pulp (referred to as liquid-solid ratio concentration). The discharge concentration of the mill is its grinding concentration
the pulp concentration in the mill has a direct impact on the grinding effect of the medium, the flow performance of the pulp itself and the settling speed of the ore particles. When the grinding concentration is high, the buoyancy of the medium in the slurry is large, the effective density is reced, the impact of the falling is weakened, and the striking effect is poor. When the content of solid ore particles in the slurry is high, the slurry viscosity is high, and there are more ore particles adhered around the medium, the probability of medium hitting and grinding ore particles increases, and the grinding efficiency increases. This is because the fine grinding effect of the grinding machine mainly depends on the grinding vibration crack effect when the grinding medium is in circular motion. However, the grinding concentration should not be too high, otherwise the impact force and grinding activity of the medium will be greatly reced, and the grinding efficiency will be reced; In addition, the slurry is too thick, the slurry fluidity is poor, the coarse material sinks slowly, the overflow ball mill is easy to run out of coarse sand, and the lattice ball mill may be blocked, resulting in "bulge". When the pulp concentration is low, the effective density of the medium in the pulp is large, and the impact force is strong when it falls, but the pulp viscosity is low, the ore particles adhering to the surface of the medium are less, the grinding effect is reced, and the wear of the medium and lining plate is increased. At the same time, when the slurry is too thin, the fine ore particles are easy to sink in the overflow ball mill, resulting in more over crushing. Therefore, it is not good if the pulp concentration is too high or too low, and the appropriate grinding concentration should be determined according to the ore properties, feed and proct particle size and medium characteristics. Generally speaking, the grinding concentration should be higher when dealing with ores with coarse feed size, high hardness and high density; When the ore with fine feed size, low hardness and low density is treated, the grinding concentration is lower
d influence of return sand ratio and classification efficiency in grinding cycle
the classification efficiency and return sand ratio in closed-circuit grinding cycle have a great influence on the proction capacity of grinding machine and the quality of grinding procts: that is, the higher the classification efficiency or return sand ratio is, the greater the proction capacity of grinding machine is, and the less the over crushed particles are. At present, the classification efficiency of concentrator is generally 40% ～ 60%, and the return sand ratio of closed circuit grinding is 200% ～ 350%
e influence of feeding speed
feeding speed refers to the amount of ore fed into the mill per unit time. When the feeding speed is too low and the ore quantity is insufficient, the lining plate will be broken by empty medium in the mill, the wear will be intensified, and the proct will be over crushed seriously; When the feeding speed is too fast and the amount of ore is too much, the mill will be overloaded, and there will be the discharge of steel balls, the discharge of large ore blocks and the gushing of pulp, and the grinding process will be damaged
F effect of grinding aids
5. Spiral concentrator is mainly the development of its materials, the first is made of metal spiral groove, the current use is more plexiglass. The theory is basically the same as before.
6.
Ball mill is the necessary grinding equipment in concentrator. It is mainly used as grinding operation before separation. It is equipped with classification equipment for grinding and classification to complete the grinding of other minerals. There are many kinds of ball mill equipment, and the working principle of each type of ball mill equipment is roughly the same, but there are also some subtle differences. The following mainly introces several classic working principles of ball mill
1. Working principle of overflow ball mill
5. Working principle of planetary ball mill
planetary ball mill is equipped with four ball milling tanks on the same rotary table. When the rotary table rotates, the ball milling tanks will rotate around the rotary table, and at the same time, they will rotate around their own axis, making a star motion, and the balls in the tank collide with each other in high-speed motion, Grind and mix materials
the above is the working principle of these different types of ball mills. I believe you also have some understanding of the running track of these ball mills. When selecting, it is suggested that the buyer can select the appropriate ball mill equipment according to the thickness of the grinding materials, so as to achieve reasonable grindability of the ball mill
7. There are many factors that affect the proction efficiency of ball mill, but they can be summarized as the following three points:
I. material properties, feed particle size and proct fineness
1. Material properties
grindability coefficient has been mentioned in the previous section. It can be seen that the grindability coefficient is related to the mechanical strength, dissemination characteristics and grinding ratio of ore. The harder the ore is, the smaller the grindability is, the more energy it consumes to grind it fine, and the lower the processing capacity of the ball mill. In addition, the properties of various minerals in the ore are also different, there are easy to grind and difficult to grind, so there will be the phenomenon of selective grinding, that is, one part has not been ground, but the other part has been crushed. For the tungsten and tin ore that is afraid of being crushed, we should pay special attention to the timely separation of the ground. The finer the ore is, the more difficult it is to grind. With the increase of grinding ratio, the grindability coefficient will change. Generally, grindability of ores can not be changed. However, recent research results show that in some special cases, the grindability of ores can be significantly changed by preheating, electrothermal irradiation or using surfactant. Some of them have been applied in proction practice, which not only reces the number of grinding and magnetic separation sections, but also improves the concentrate index
2. Feed size
the coarser the feed of ball mill, the longer the grinding time is needed, the more work is needed to grind it to the specified fineness, and the lower the proctivity. The influence of feed particle size on the proctivity of ball mill is related to the properties of ore and the fineness of proct. Therefore, when it is required to improve the proction capacity of the ball mill, it is important to rece the feed particle size within a certain range
3. Proct fineness
the grinding proct size of ball mill directly affects the separation index. If the grinding proct is too coarse, the useful minerals and gangues are not fully dissociated, and if it is too fine, it will cause serious over crushing, which will rece the separation index. If the grinding particle size is changed to finer, the energy consumption and steel consumption will increase, the proctivity will decrease, and the cost of grinding a ton of ore will be higher than that of grinding coarse ore. Therefore, the determination of grinding particle size must be based on the technical and economic conditions< 2. Structure and rotation speed of ball mill
1. Type of mill 2. Diameter and length of mill 3. Rotation speed of mill 4. Type of liner
the proctivity of smooth liner for ball mill is usually smaller than that of non smooth liner mill. The use of too thick liner will rece the effective volume of the ball mill and the proctivity. After the liner is worn, the inner diameter of the mill will increase. At this time, the ball loading rate will be low, which will rece the proctivity. Therefore, the ball loading amount should be increased appropriately< Third, operation conditions, including ball loading system, grinding concentration and feeding speed
if you have any questions, please contact Shanghai Tongli www.tonglizhongji.com Our technical engineers will answer for you!
I. material properties, feed particle size and proct fineness
1. Material properties
grindability coefficient has been mentioned in the previous section. It can be seen that the grindability coefficient is related to the mechanical strength, dissemination characteristics and grinding ratio of ore. The harder the ore is, the smaller the grindability is, the more energy it consumes to grind it fine, and the lower the processing capacity of the ball mill. In addition, the properties of various minerals in the ore are also different, there are easy to grind and difficult to grind, so there will be the phenomenon of selective grinding, that is, one part has not been ground, but the other part has been crushed. For the tungsten and tin ore that is afraid of being crushed, we should pay special attention to the timely separation of the ground. The finer the ore is, the more difficult it is to grind. With the increase of grinding ratio, the grindability coefficient will change. Generally, grindability of ores can not be changed. However, recent research results show that in some special cases, the grindability of ores can be significantly changed by preheating, electrothermal irradiation or using surfactant. Some of them have been applied in proction practice, which not only reces the number of grinding and magnetic separation sections, but also improves the concentrate index
2. Feed size
the coarser the feed of ball mill, the longer the grinding time is needed, the more work is needed to grind it to the specified fineness, and the lower the proctivity. The influence of feed particle size on the proctivity of ball mill is related to the properties of ore and the fineness of proct. Therefore, when it is required to improve the proction capacity of the ball mill, it is important to rece the feed particle size within a certain range
3. Proct fineness
the grinding proct size of ball mill directly affects the separation index. If the grinding proct is too coarse, the useful minerals and gangues are not fully dissociated, and if it is too fine, it will cause serious over crushing, which will rece the separation index. If the grinding particle size is changed to finer, the energy consumption and steel consumption will increase, the proctivity will decrease, and the cost of grinding a ton of ore will be higher than that of grinding coarse ore. Therefore, the determination of grinding particle size must be based on the technical and economic conditions< 2. Structure and rotation speed of ball mill
1. Type of mill 2. Diameter and length of mill 3. Rotation speed of mill 4. Type of liner
the proctivity of smooth liner for ball mill is usually smaller than that of non smooth liner mill. The use of too thick liner will rece the effective volume of the ball mill and the proctivity. After the liner is worn, the inner diameter of the mill will increase. At this time, the ball loading rate will be low, which will rece the proctivity. Therefore, the ball loading amount should be increased appropriately< Third, operation conditions, including ball loading system, grinding concentration and feeding speed
if you have any questions, please contact Shanghai Tongli www.tonglizhongji.com Our technical engineers will answer for you!
8.
Horizontal centrifugal mill has high grinding efficiency when it is used for fine grinding and ultra-fine grinding. According to the test of the former Soviet Union, the centrifugal mill with a volume of 2 m3 can replace the ball mill with a volume of 20 m3. Using a centrifugal mill instead of a ball mill can save 40000 rubles only in terms of recing metal consumption. In recent years, the Soviet Union adopted Φ eight hundred × 1000 mm centrifugal mill instead of concentrator Φ two thousand and seven hundred × 3600 mm ball mill is used for regrinding middlings and concentrates. Instrial tests show that better economic benefits can be obtained. Developed by Lurgi and South Africa Φ one × The 1.2m, 1400kW centrifugal mill was put into operation in South Africa gold mine in 1979. Centrifugal mill can be used in wet open circuit process and closed circuit process with hydrocyclone
9. The unit volume yield of grinding machine is the ratio of ore processing capacity to the average root of grinding machine diameter. The grinding machine diameter directly determines the impact of load pressure on grinding materials. The more the grinding machine diameter is, the more the ore is impacted by pressure steel ball, and the higher the ore processing capacity is. At present, the development and utilization characteristics of new designed and manufactured grinding machines at home and abroad are
grinding process and factors are summarized as follows: grinding machine design Preparation structure, ore properties and operation conditions are three aspects in the proction site. The basic fixation of equipment should depend on the ore properties. The operation conditions have a decisive impact on the quantity and quality of grinding procts. To ensure the quality of grinding procts, the operator must be based on the ore properties (particle size, particle size, particle size, etc.) With the adjustment of feed rate, all kinds of operation conditions are stable and suitable level
liner type material affects the grinding output and quality, liner type selection reces the processing capacity, grinding fineness meets the requirements
liner material affects the ore processing capacity, proct fineness liner material has less manganese content, soft anti-wear degree affects the impact force of steel ball ore, and grinding stripping effect information is provided by
grinding process and factors are summarized as follows: grinding machine design Preparation structure, ore properties and operation conditions are three aspects in the proction site. The basic fixation of equipment should depend on the ore properties. The operation conditions have a decisive impact on the quantity and quality of grinding procts. To ensure the quality of grinding procts, the operator must be based on the ore properties (particle size, particle size, particle size, etc.) With the adjustment of feed rate, all kinds of operation conditions are stable and suitable level
liner type material affects the grinding output and quality, liner type selection reces the processing capacity, grinding fineness meets the requirements
liner material affects the ore processing capacity, proct fineness liner material has less manganese content, soft anti-wear degree affects the impact force of steel ball ore, and grinding stripping effect information is provided by
10.
the particle size of the material to be grinded is large
if the particle size of the material is large, it is difficult to adapt to the impact and grinding effect of the grinding body, and the first bin of the ball mill is forced to load more steel balls to enhance the ability of impact grinding materials. One bin is responsible for crushing, which makes the crushing process unreasonable. The function utilization rate of crusher is high. Increasing the grinding head crushing and recing the grinding particle size can not only rece the energy consumption, but also increase the output
the moisture content of the feed material is too high
when the moisture content of the feed material is too high, the grinding body and lining plate will be adhered to form a "cushion", and the grate plate will be blocked, causing "full grinding". But the lower the water content, the better. It should be kept in a certain range
fineness requirement of the material to be grinded
the finer the fineness requirement of the material to be grinded, the lower the output, on the contrary, the higher the output
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