How can ability judge ball mill load

Product introduction :https://www.lvssn.com/mill/Cement-ball-mill.html

Jiangsu LVSSN company core cement epc

Ball mill load is the sum of ball load, material load and water amount in the mill.What are the methods of measuring ball mill load?
 

1. The sound method

Industrial production practice shows that the sound of the ball mill has a certain relationship with the material load. The essence of this method is to determine the material load in the ball mill according to the difference in the noise produced by the ball mill.When the material load in the ball mill increases, the noise intensity of the ball mill decreases.On the contrary, the noise intensity of the ball mill increases, that is, there is a relationship between the noise intensity of the ball mill and the material load in the ball mill.Therefore, the noise intensity of the ball mill can be used to evaluate the material load in the ball mill.

 

2. Active power method

The working characteristics of a wet ball mill can be directly described by the useful power consumed.When the mill and its rotating speed are fixed, the theoretical calculation and actual test results show that there is a certain relationship between the active power of the ball mill motor and the load of the ball mill.With the increase of the ball mill load, the active power of the ball mill motor rises obviously at the beginning, and after reaching a certain extreme value, the active power decreases instead with the increase of the ball mill load. This extreme value can be considered as the optimal point of the ball mill load.Therefore, the useful power is directly related to the load of the ball mill.
 

3. The vibration method

When the ball mill is running, the grinding body and the material are on the side of the mill, and the grinding material and the rotating part of the mill are in a serious unbalance state, which causes the unbalance centrifugal force and makes the mill system vibrate.When the speed of the mill is unchanged, the vibration intensity of the mill is related to the amount of the grinded material.
 

4. Pressure sensor method

A load sensor is installed under the bearing of the feeding end and discharging end of the ball mill to continuously weigh the mill, so as to determine the total amount of ball medium, ore and water in the ball mill and determine the load of the mill.Its advantage is simple, the disadvantage is the detection accuracy is not high, can not accurately detect the ball mill medium, ore and water in the respective amount.In addition, the wear of ball mill lining plate, the change of ore property, the change of steel ball weight before and after adding will have a great impact on the test results.

 

5. Differential electromagnetic sensor method

It only measures the useful part of the vibration signal of the mill shell and eliminates the general interference signal.The sensor can be mounted at a distance of 71 ~ 80mm from the shell of the ball mill.The sensor has high reliability and sensitivity and low signal transmission delay.But this kind of detection system can't detect the concrete value of the ball mill's medium filling rate, material ball ratio and grinding concentration.
 

6.Hall power transmitter method

In the closed circuit grinding system of a ball mill with a double screw classifier, the load of the ball mill is indirectly reflected by measuring the amount of sand returned by the classifier.In the grinding production process, when the load of the ball mill exceeds the normal value, the coarse particle composition of the ball mill will increase, which will definitely increase the amount of returned sand; otherwise, the amount of returned sand will decrease.Therefore, it is feasible to measure the load of the ball mill indirectly by measuring the amount of returned sand. The hall power transmitter is used to measure the electric power of the classifier.At the same time, the absolute value of power is not required to be measured in this measurement, so only the single-phase power variation value of the three-phase motor with internal rotation of the double helix classifier is measured, so as to reflect the relative change of the returned sand amount and realize the automatic control of the ball mill load.

The single factor detection method introduced above is unable to judge the medium filling rate, material ball ratio and grinding concentration of the ball mill, so it is more important to choose the appropriate method according to the actual situation of the site.

The page source: https://www.lvssn.com/company/What-are-the-methods-of-measuring-ball-mill-load.html

How much do you know about the inspection and maintenance of the Vertical mill?

Product introduction:https://www.lvssn.com/mill/Raw-material-vertical-mill.html

Jiangsu LVSSN company core cement epc

Vertical mill as the main machine equipment of cement enterprise, the operation of the good or bad directly affects the benefits of the enterprise, its inspection and maintenance is very important, how much do you know about the inspection and maintenance of the opposite Vertical mill?
 

1. Inspection parts and methods of vertical mill

 

The vertical mill is composed of its power, transmission, lubrication, powder selection, feeding pipe, inlet and outlet air pipe, sealing, discharging mechanism and main machine, etc. The system is huge and complex, and the patrol inspection and maintenance task is heavy.The brief is as follows:
 

1.1 power part inspection

The power mainly refers to the main and secondary motors of the vertical mill.Check whether the motor grounding is loose and tighten it in time if any problem is found.Whether the position switch of the auxiliary motor is normal;Whether the various types of cover loose friction;Motor vibration, sound, temperature rise, current, voltage and other normal;Whether the motor lubrication is normal, whether the oil supply pressure, oil supply temperature, cooling water, inlet and outlet temperature of the oil station are normal, whether the oil level and filter pressure difference of the oil station are normal.If there are problems in the vertical mill, the causes should be analyzed and symptomatic treatment should be conducted.
 

1.2 inspection and maintenance of transmission parts

The transmission part includes a coupling, a reducer, and a service station.The inspection of the vertical mill oil station includes whether the oil level is deficient, whether the pressure is normal, whether the oil return, oil supply and temperature of the oil tank are normal, whether there is oil leakage or not, whether there is oil passing through through the tubing temperature, and whether the filter oil pressure difference is normal.Vertical grinding reducer is the focus of the inspection, to listen to the internal bearing, gear meshing sound is uniform, to test whether the vibration of each part is abnormal, the temperature of each detection point is normal, whether the foot is loose.If any abnormality is found, it must be analyzed and handled. Here, the position of the fault can be determined by comparing the rotation speed of each shaft with the sound and vibration frequency.Check oil supply pipeline and airframe for oil leakage, etc.
 

1.3 part of grinding mill inspection

The grinding part includes pressure station, grinding roller, grinding disc and its support.The patrol inspection of this part shall first check whether the pressurization station and its pipelines are normal, whether the accumulator is normal, whether the hydraulic cylinder is leaking oil, whether the hinge connection above and below the hydraulic cylinder is abnormal, whether there is abnormal sound or impact.Check whether the support rotation of the grinding roller is abnormal, whether the fastening bolts and the gland are loose and exit, whether the lubrication of each joint bearing is in place, whether the hydraulic rod seal and the connecting parts of the hydraulic rod are abnormal, whether the back of the grinding body is damaged, whether the casing is worn through and other abnormal conditions.Listen to the sound and vibration in the vertical mill.
 

1.4 inspect the wind material connecting pipe of the mill

The pipe around the vertical mill mainly refers to the inlet and outlet air pipes, feeding and slag discharging pipes.It mainly checks whether the connecting bolt of the inlet and outlet air duct is loose and whether the soft connection is damaged or leakage.Whether the feeding and discharging pipe is worn through, whether the feeding and discharging mechanism is flexible and effective.
 

1.5 inspection of powder separator

The concentrator is located on the top of the vertical mill. It mainly checks whether the motor, reducer and coupling work normally, whether there is any abnormality, whether the sound, vibration and temperature rise are normal.Listen to the selection machine internal sound is normal, whether there is friction block phenomenon.
 

2. Maintenance of vertical mill

 

The maintenance of vertical mill mainly refers to the treatment of common faults that can be seen and heard in the inspection.Mainly include:

Adjust the pressure and temperature of each oil station;Adjust cooling water flow and temperature;Tighten oil, water and air pipe fittings to eliminate drip leakage;When the oil level of the vertical mill oil station is insufficient, timely supplement;When the platform and support are loose, reliability treatment shall be carried out;In case of oil pollution or other pollution, clean up the equipment in time to ensure the sanitation of the equipment;For the equipment air leakage should be blocked in time to reduce reactive power consumption;When it is found that there are dangerous equipment and unstable material of personal safety around the vertical mill equipment, it should be removed in time.Dredge the lubrication pipes of the joint bearing and hinge joints in time to ensure lubrication.When foundation bolts or other connections are found loose, they should be tightened in a timely manner.And so on.

As for the problems that must be solved by shutdown in the patrol inspection, the reasons should be analyzed, the fault location should be determined, the solution should be made and reported to the relevant management personnel or management department, waiting for the shutdown to be arranged.

The page source:https://www.lvssn.com/Product/How-much-do-you-know-about-the-inspection-and-maintenance-of-the-Vertical-mill.html

What are the basic parameters that the roller press can adjust?

Product introduction:https://www.lvssn.com/mill/Roller-Press.html

Jiangsu LVSSN company core cement epc

The roll press is like the roll crusher, but its function is different, there are essential differences.Roller mill in cement powder has occupied a dominant position, what are the basic parameters of roller mill can be adjusted?
 

1. Working principle of roller press

 

The roller press consists of two rollers (namely moving roller and fixed roller), frame, reducer, torque support, motor, pressure system and feeding device.When the two rollers run in opposite directions under the power, the material from the upper part is pulled into the gap between the two rollers. Then the hydraulic cylinder installed on the back side of the moving roller starts to pressurize, driving the piston forward and pushing the moving roller to put pressure on the material.With the two rollers continue to pull the material into the gap of the roller and compacted and crushed, into the cake unloading, the cake after the finished products into the mill or storage, unqualified products return to continue rolling, until the final complete grinding.
 

2. Parameters of roller press

 

2.1 pressure of roller press

The pressure of the roller press is a key parameter of work efficiency.The yield of ground powder is almost determined by pressure.When the pressure is 60MPa, the passing rate of 32 micron fine powder is about 20%. If the content of fine powder increases to 30%, the pressure should reach 100-300mpa.At the same time, the experiment shows that when the pressure is very high, the increase of fine powder production rate is not obvious, but the power consumption is doubled. At the same time, because of the pressure increase, the material cake is not easy to break, the power consumption of tube mill will also increase.The conclusion of the experiment on a small roller press is that when the passage rate of 45 microns is 36.1%, the required working pressure is 205MPa, from which it can be seen that the passage rate of 80 microns will be higher.Domestic data show that the average roll pressure in 120- 150MPa, 0.08 fine powder production rate can reach 50%.

Combined with the actual situation, the average roller pressure should be more than 60MPa, if it can reach more than 100MPa is the best, so not only the fine powder production rate is high, high work efficiency of the roller press, but also reduce the cycle load, transmission equipment energy consumption will be reduced, is conducive to reducing the system power consumption.
 

2.2 control of feed size

The feed particle size of the roller press, can be determined by 3.5% of the roller diameter, under the appropriate pressure, stable operation, should not be too large, the data shows that when the diameter of 7.0% of the roller diameter, the current fluctuation of the roller press will increase several times, not conducive to stable operation.
 

2.3 selection of roller seam

Roller gap is also one of the important parameters of roller press, generally 2.0% of roller diameter.The original roller gap is generally about 10mm. It needs to be reminded that, before setting the original roller gap, the radial runout of the roller should be tested radial, the most prominent position of the two rollers should be transferred to the horizontal position of the opposite direction, and then the limit block should be fixed so that the gap is about 10mm, and the two axes should be parallel.

 

2.4 installed power of roller press

When the average roll pressure is at 60MPa, the power consumption of tons of materials is 2.4kw, but the actual pressure at ordinary times will be about 1.5 standby. A large number of experimental data show that rolling a ton of clinker requires 3.5kwh, a ton of limestone requires 3.0kwh, and a ton of slag requires 6.0kwh, so the installed power should be greater than this value.
 

2.5 selection of roll seam displacement

Roller press roll gap to stabilize the best, but in actual operation, due to the change of particle size, the influence of oil compressibility, vibration, etc, is bound to change, but I did not allow unlimited expansion, roll gap must set a reasonable displacement, if the displacement is too large, will surpass the self-aligning bearing Angle, bearing damage, so must limit, generally offset control in 3 to 5 mm, but the best through the allowed Angle calculated bearing, both to ensure the safety of bearing, also ensure the extrusion effect.
 

2.6 roller linear speed

The linear velocity of roller is closely related to the production, but the experiment shows that the linear velocity is linearly related to the production when the linear velocity is 0.2-1.5 m/s.When the linear velocity is 1.5-1.8m /s, the relationship between output and velocity decreases, indicating that the ability of roller to bite the material is decreasing.Therefore, the linear speed of the roller press should be below 1.8m/s.
 

2.7 output of roller press

The output of the roller press is measured by the passing quantity, which is related to the speed of the roller, the volume and weight of the cake, the thickness of the cake and the width of the roller.namely

G = 3600 BVSP (t/h)

Where: t/h for table G, width meter for B roller, linear velocity meter/S for V roller, thickness meter for S cake, about 2.25% of the straight diameter of the roller., the bulk weight of p cake is about 2.4 tons/m3.

In fact, after the installation and use of the roller press, the structure parameters can not be changed, only the size of the pressure, the size of the roller gap offset, the size of the size of the material size and the number of recycling materials.Pressure is the most critical data, which directly affects the work efficiency, fine powder production rate;The difference of roller gap not only affects the bearing installation, but also affects the roller pressure effect.Granularity involves operational stability;The amount of circulation also involves the density of incoming materials, too much fine powder or granular material too much will cause the entry of excess air, not conducive to stability and so on.

The page source:https://www.lvssn.com/Product/What-are-the-basic-parameters-that-the-roller-press-can-adjust.html

A new method of wind lock for vertical mill feed

Product introduction:https://www.lvssn.com/mill/Raw-material-vertical-mill.html

The vertical mill, as a windswept mill, must work under the condition of negative pressure.The system air leakage must be reduced as much as possible to realize the function of air lock while ensuring the normal feeding amount of the vertical mill.A new method of wind lock for vertical mill feed
 

 

As shown in the photo, the wind lock function is completed by the variable diameter screw conveyor, that is, in the process of conveying incoming materials, the screw conveyor compacts the materials and fills the housing by changing the diameter to realize the wind lock.
 

1. The principle of wind lock is

The incoming material will be sent to the diameter change through the front spiral blade to become densified and fill the shell into the storage area, forming a tight seal area. Through the continuous push of the screw and extrusion of the material, the material will continuously enter the discharge pipe of the vertical mill center.

 

This type of air lock has obvious advantages over other types of seal.Because the design capacity of rotary feeder is far greater than the capacity of the vertical mill, more cold air is fed into the feed at the same time, and the surrounding clearance will also enter a lot of cold air under the high negative pressure of the vertical mill, the main reason is that the shape is not reliable seal.Compared with the current improved feeding air lock system of silo + positive displacement feeder + weighing scale, this new type of air lock has the characteristics of simple equipment, easy arrangement and few fault points.
 

2. Advantages of screw conveyor for vertical mill feeding

 

Screw feeding has obvious advantages.

Theoretically speaking, it can be considered that the material seal completely isolates the contact between the mill and the outside world and can completely block the cold air from entering the mill.

 

(1) variable screw conveying can pass the gradual compaction and hoarding of materials, which can eliminate the leakage of materials into the vertical mill.

(2) compared with more precise volumetric feeding, the failure rate and clogging probability are reduced, and the maintenance is relatively simple.Variable screw conveyor, one machine more, convenient layout, simple transformation.

(3) compared with the bin + volume feeder + scale, the failure rate is low, the investment is small and the control is simple.

(4) compared with other forms of feeder, central feeding can be realized and local impact wear of feeding tube in the opposite grinding center can be avoided.

(5) good air lock is achieved, which effectively improves the utilization rate of hot air, reduces the load of the system dust collector, and provides favorable conditions for extending the life of the filter bag and realizing ultra-low discharge.

(6) even if the vertical mill is shut down, there is always material seal at the end of the conveyor, which still plays a good sealing role.

This new method can meet the requirement of water content less than 20%.The machine head and tail are equipped with external support devices and grease pipelines, which can be directly transferred to the grease lubrication station during the transformation to ensure the bearing life.At the same time, the blade has high - quality wear - resistant material, greatly increased the use cycle of the product.

The page source:https://www.lvssn.com/company/A-new-method-of-wind-lock-for-vertical-mill-feed.html

Several key components of vertical mill

Product introduction:https://www.cementepc.net/grinding/LVRM-Vertical-Mill.html

Vertical mill is an ideal large-scale pulverizing equipment, widely used in cement, electric power, metallurgy, chemical industry, non-metallic ore and other industries.It sets crushing, drying, grinding, grading conveying in one, high production efficiency, can be block, particle and powder raw materials into the required powder material.You know, the key components of the vertical mill.

Vertical mill has high efficiency in production, energy conservation, environmental protection, material drying ability strong, stable product quality inspection, wear small, high efficiency, etc. But in the actual production typically has the production and safety issues such as excessive vibration, let's learn about the simple vertical mill's several big functions and maintenance of key parts, in order to better to protect the security of vertical mill production.
 

1, the roller

For the vertical mill, the roller is the heart of the vertical mill. The roller of the vertical mill is inclined in design, which has two main functions: one is to increase the contact area and improve the grinding efficiency;The second is to prevent large pieces of material from falling off the edge, blocking the air inlet.In addition, with the increase of the grinding time, the grinding roller is gradually worn, which can be used to turn the surface of the grinding roller, extending the service life and saving the cost.

Vertical mill and vibration due to long-term wear, each connection gap get bigger, easy to cause the center of the roller location deviation, can form to pull rod and twisted, on the pull rod torque, intensifying mill vibration, destructive damage to the hydraulic cylinder and the chassis base, and pull rod and pull rod bolt fracture easily.In daily maintenance, we should arrange at least one to two times of planned maintenance according to the production status every year, mainly to test the radial system of the mill and replace worn and aged spare parts.
 

2. Hydraulic tension system

The hydraulic tension system is one of the most important equipment systems in the vertical mill. It plays a key role in the stable operation of the vertical mill and is also a link prone to failure. The huge grinding pressure exerted by the roller on the material is provided by the hydraulic system.
 

Generally, the reasons for the failure of the hydraulic system mainly include the damaged fault of the accumulator nitrogen air bag and the frequent start-up fault of the high-pressure oil pump in the hydraulic station. In order to ensure the normal operation of the hydraulic system, the following points should be achieved in production:

(1) the hydraulic fluid in the hydraulic system is required to have a higher degree of cleanliness.In case of small particles into the hydraulic oil, resulting in cylinder scratches, nitrogen balloon damage;

(2) during the use of the hydraulic oil, the oil quality should be tested and checked regularly every half a year, and the hydraulic oil should be replaced in time if the oil is emulsified;

(3) a reasonable grinding pressure should be set according to the characteristics of the material. In normal production, the actual operating pressure should be set between 70% and 90% of the maximum pressure limit.
 

3. Other key components

In addition to grinding roller and hydraulic tension system, the safe and efficient production of vertical mill also depends on the following key components!

(1) the powder separator can timely select the particles of a certain size in the grinding materials, avoid the occurrence of material aggregation, adhesion to the grinding body and bin, and reduce the over-grinding of the grinding materials;Improve grinding efficiency.Generally, cone concentrator is mainly used for coarse powder selection (conventional powder selection);The movement direction of the impeller of the cage separator is opposite to the direction of the blade tilt, which increases the difficulty of powder selection and improves the accuracy of powder selection. It is mainly used for fine powder selection.

(2) reducer is the heart of the safe operation of the vertical mill. No matter the vertical mill reducer supplied by domestic and foreign manufacturers, it is necessary to detect the meshing of the spiral bevel gear pair by coloring before installation and operation.It is necessary to stop the machine after half a year's operation.In order to ensure the safe operation of the reducer, it is necessary to know the running condition of the gear and bearing of the reducer by checking the oil filter net impurity regularly and cooperating with the endoscopic examination.

(3) the functions of the hot blast furnace are mainly as follows: 1. Reduce the oxygen content of the air in the mill system to prevent explosion; 2.2. Drying materials;3. Pressurize to handle materials with certain humidity.

(4) explosion-proof valve (plastic sheet) is located on the top of the separator. When the pressure in the grinder is too high, the plastic sheet will explode automatically, thus preventing the explosion of inflammable and explosive materials when grinding.

(5) the limiter is a device used for fine-tuning the distance between the grinding roller and the grinding disc, so that there is no contact between the two, to avoid damage caused by contact between the grinding roller and the grinding disc due to uneven cloth vibration during work.

The page source:https://www.cementepc.net/productknowledge/Several-key-components-of-vertical-mill.html