What is the difference between a dry ball mill and a wet ball mill in production?

Product introduction :https://www.cementepc.net/grinding/Cement-ball-mill.html

Jiangsu LVSSN company core cement epc

Ball mill is a common equipment in grinding equipment, but also the material after the crushing and screening operation, the key equipment for grinding.According to the classification of grinding, the ball mill can be divided into dry ball mill and wet ball mill.What are the differences between a dry ball mill and a wet ball mill?

1. How it works

When the dry ball mill is running, the material enters the first bin of the mill uniformly through the feeding device through the feeding hollow shaft screw, and the bin is equipped with stepped lining board or corrugated lining board, which is equipped with steel balls of different specifications.The centrifugal force generated by the rotation of the ball mill barrel will bring the steel ball to a certain height and then it will fall down.

After the material is roughened in the first warehouse, it enters the second warehouse through the single layer compartment plate, which is equipped with flat lining plate and steel balls of different specifications to further grind the material.Finally, qualified materials are discharged through the discharge grates to complete the grinding operation.

The working principle of wet ball mill is similar to that of dry ball mill, but different.Wet ball mill needs to add appropriate amount of water or anhydrous ethanol in the grinding process, which means that the grinding concentration has certain requirements.The amount of water is determined by the nature of the material.Qualified materials are discharged out of the cylinder through the discharge part, and the unqualified materials are returned to the wet ball mill for further grinding.
 

2. Structural construction

Dry ball mill and wet ball mill both include feeding part, feeding part, rotating part, transmission part (reducer, small transmission gear, motor, electric control) and other major parts.

The difference is that the structure structure of the dry ball mill is relatively more complicated than the wet ball mill, and its discharge mouth is straight cylinder shape, and it is equipped with air device, dust pipe and dust collector, which is determined by its working principle.The structure of wet ball mill is simple, no need to add too many auxiliary accessories, discharge mouth is like a horn, built-in screw device to facilitate discharging.

3. Scope of application of ball mill

In general, the dry ball mill is suitable for all kinds of metal ore, non-metal ore, including water will react with materials, such as cement, marble and other building stone, or require powder form to store and sell products.In addition, if the plant is located in a dry area, water resources are scarce, for the sake of water conservation, can use dry ball mill.

Wet ball mill is applicable to a wide range of metal ore, non-metal ore, including gold ore, silver ore, copper ore, iron ore, molybdenum ore, phosphate ore, feldspar, fluorite and so on.Wet ball mills can be used as long as the material meets water and does not affect the quality of the final product.

It should be noted that when wet ball mill is used, the proportion of steel ball, material and water should be determined through ore dressing test to ensure the ideal grinding effect.As for the choice of what kind of grinding equipment, or depends on the ball mill follow-up operations, product nature and production costs.

Only by finding out the suitable grinding mode of the material, can the ball mill run efficiently and well, the two grinding equipment have their own advantages, we are still in the nature of the material, characteristics and the requirements of the product, working environment and other aspects of the rational choice.

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Causes and treatment measures of several typical vibration of rotary kiln

Product introduction:https://www.lvssn.com/bruning/Rotary-kiln.html

Jiangsu LVSSN company core cement epc

Customers who have used the cement rotary kiln have basically encountered the vibration of the rotary kiln's large tooth ring.Generally, there are three major reasons for mechanical, technological and electrical reasons.Causes and treatment measures of several typical vibration of rotary kiln

 

1. Vibration caused by mechanical reasons and treatment

 

1.1 the closing bolt is loose or broken

After the closure bolt of large gear ring becomes loose or broken, the pitch of gear increases. When meshing with the pinion, the rotary kiln will vibrate due to the different pitch.Closure pin fracture, will make the closure surface dislocation, will have the same result.If this is found, the pin should be replaced, tighten or replace the bolt can be restored to the closed surface tooth size can be.
 

1.2 deformation of large gear ring

When the large gear ring loses its ring deformation, the local pitch changes and the local center distance also changes, which directly affects the meshing accuracy of the gear.When the ring is convex, the gap between the top of the tooth is reduced, giving out a dull root biting sound and causing vibration.In this case, only by lowering the top height or the center height of the rotary kiln, that is, reducing or expanding the center distance of the rotary kiln size gears, can the meshing precision of the gears be adjusted to a tolerable state, so as to reduce the vibration.To achieve the ideal condition, it is best to replace the large gear ring, because it is very difficult to correct the gear.
 

1.3 improper kiln adjustment

Sometimes, in order to adjust the stress state of the supporting wheel or belt, the contact between the gears is not taken into account. For example, if the rotary kiln is pushed to the side of the pinion, the top clearance will be reduced and root biting vibration will be generated.If pushed to the outside of the pinion, also because the top gap is too large, overlap cannot keep up with and cause vibration.The treatment method is, rotary kiln adjustment to take into account the gear meshing, through adjusting the size of gear meshing precision can be restored.
 

1.4 gear cracking or broken teeth

The pitch of gear teeth changes after gear cracks or cracks or even broken teeth, which affects gear meshing accuracy and causes vibration.At this time, the cracks and broken teeth must be processed, and restore the geometric size, if necessary to replace the large ring teeth.
 

1.5 insufficient installation accuracy

Insufficient installation accuracy of rotary kiln will not only affect the contact length and width of the gear, but also affect the top clearance and side clearance of the gear, causing vibration.This time need to check carefully, for the identified problems, one by one adjustment (through the wheel adjustment), so that it can achieve good contact accuracy.

 

2.Vibration caused by process

Process causes the vibration of the rotary kiln, is mainly refers to abnormal caving of the skin of the kiln, barrel temperature change after everywhere would create a warp in the cylinder, make big gear ring, the rotary center of deviation from the normal size when the center distance of gear when small, produces vibration, the need to adjust process parameters, the rotary kiln shell temperature returned to normal, avoid cold and hot half a circle is not normal, kiln will slowly unbend, big ring gear rotary center will gradually returned to normal, vibration will disappear.

There is also a case to draw attention to, that is, the barrel temperature at the big gear ring can not be too high, it will seriously affect the temperature of the big gear ring, once the expansion of the big gear ring because the temperature is too high more than the expansion of the belt, the gap between the tooth tip will be reduced, making it possible to bite the root, vibration may occur.At this time, it is necessary to keep the cooling of the gear ring or the top rotary kiln to ensure the normal engagement of the gear.

 

3. Electrical influence

The influence of electrical equipment mainly refers to the vibration caused by the unsteady rotating speed of rotary kiln due to signal fault.After the kiln speed distortion caused by the fault of the tachometer generator, the rotary kiln is fast and slow, with high frequency and great difference in speed and slow. The gear has constant impact and great vibration. After the contact with the slip-ring and the line of the tachometer generator, the kiln runs steadily and the vibration disappears.

This paper is only a description of several kinds of vibration of rotary kiln gear ring, which is not comprehensive. If you have better opinions, please leave a message to me for communication.

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The reasons and solutions of grate gap clogging in grate cooler

Product introduction:https://www.cementepc.net/burning/Grate-cooler.html

Jiangsu LVSSN company core cement epc

Grate cooler is an important equipment in the rotary kiln system. On the one hand, it cools the hot clinker out of the kiln to a suitable temperature. During the cooling process, it displaces the heat energy in the clinker and contains it in the hot air.On the other hand, through the grate bed advance, the clinker will be transported to the appropriate location, broken into storage.Therefore, the role of grate cooler can be for cooling clinker, convenient transportation, convenient storage;Replacement of heat energy, effective saving of coal.

Grate for grate cooler is very critical, is the passage of the wind, the size of its section area is related to the wind resistance and through the amount, but this has been determined in the design and manufacturing, the use of units is to find a way to maintain this parameter, prevent the grate plug.The reasons and solutions of grate gap clogging in grate cooler

1. Reasons for grate blockage

 

1.1 improper material cushion of pu before kiln opening

For example, the cushion powder has more particles and less, the cushion clinker is moist, small particles and powder will be trapped in the grate, at this time the fan of the grate cooler cannot be opened, but the temperature rises with the temperature of the kiln, clinker condensation will occur, so when the fan is opened, in fact, part of the grate has been blocked.
 

1.2 wet bottom of grate bed

Some enterprises in order to reduce the temperature of the residual air, often in the grate cooler to add atomized water, once the wind temperature low atomized water, will cause wet bottom, sometimes even stop the water, the result of the grate is firmly paste.
 

1.3 the clinker with liquid phase enters the grate cooler

For example, due to improper ingredients, adjustment on the kiln did not follow up, viscous belt liquid clinker into the grate cooler, if the adjustment is improper at this time, not only cause a snowman, but also cause grate plug.In addition, improper operation of the burner causes pulverized coal to fall into the grate cooler for combustion, and the clinker becomes sticky and blocks the grate cooler.
 

1.4 improper operation

Mainly refers to the operation does not adapt to or do not follow the grate bed of the wind change, such as the material layer changed, the wind pressure did not increase, sometimes even shut down the press;For example, improper shutdown, improper shutdown sequence, belt material stop wind, and so on, easy to cause plug grate.

2. Solution to plug the grate

 

2.1 block prevention before starting up

Before starting up the system, it is generally necessary to lay the clinker cushion at the hot end of the grate bed to prevent the burning of the hot clinker and the damage of the grate plate by the impact of large clinker.In the early stage of kiln ignition, the grate bed does not operate and the fan does not open. If the clinker cushion is moist and pink, it is easy to plug the grate seam of the grate cooler. Therefore, the clinker cushion should choose dry granular clinker.
 

2.2 during maintenance, the grate shall be cleaned carefully

During maintenance must be based on the usual situation, to the grate carefully cleaned, one by one inspection, cleaning, if not clear, must be replaced, otherwise inevitably affect the cooling effect.
 

2.3 strictly control atomized water

If some enterprises set atomized water on the top of the grate bed of the grate cooler, the atomized water amount and atomization effect should be strictly controlled to ensure that atomized water droplets vaporize before falling on the clinker. Meanwhile, the operation must match with the system, otherwise the wet bottom may occur at any time, and water should be stopped before the shutdown.
 

2.4 timely adjustment and reasonable operation

No matter from the aspect of technology, or from the aspect of equipment, reasonable operation and timely adjustment are needed. However, there are too many contents involved, and only a few items can be highlighted. For example, if there are multiple layers of incoming materials, the grate speed should be accelerated, and the wind pressure and air volume should be adjusted.The material layer is thin to drop the grate speed, reduce the air volume and stop the machine.If the fan fails, it should be opened in time. If the shutdown time is long, it must stop the grate cooler or other corresponding measures.Otherwise it is easy to plug the grate.And so on.

For the cold machine, the grate is very important, if you encounter other reasons for congestion or have a better solution can leave a message with us.

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Rotary kiln with refractory materials most afraid of what?

Product introduction:https://www.lvssn.com/bruning/Rotary-kiln.html

One of the main features of the rotary kiln is that the refractory materials masonry in the kiln rotate with the shell at high temperature.Refractory bricks not only have to be subjected to thermal shock, erosion and wear of kiln gas and materials, but also have to bear the pressure of squeezing each other and the shell during vibration and rotation.Rotary kiln with refractory materials most afraid of what?
 

1. For refractory materials used in rotary kiln, the most feared is the frequent stopping and opening of kiln.

The service life of rotary kiln is directly affected by the number of kilns stopping.In the production of rotary kiln, the frequent opening and stopping of kiln will cause the hot surface of firebrick to cool down quickly and shrink too fast. The structure inside firebrick will be seriously damaged.When the kiln is opened again, the hot surface layer of refractory brick often falls off with the kiln skin, which also distorts the brick position inside the kiln lining and reduces the service life of the kiln lining.

 

2. Control the opening and stopping times of rotary kiln

Firstly, the stable operation of rotary kiln equipment should be ensured. Secondly, the stable quality of all fuels should be ensured. Meanwhile, the stable quantity of coal and materials should be controlled.
 

Each kiln opening time should be carefully considered and deployed for the best:

1. 2 hours before the rotary kiln is scheduled to turn off, the decomposition furnace shall gradually reduce fuel, and then gradually reduce raw material, so that the temperature of the preheater system cannot be super high.

2. Open the cold air valve slowly so that the inlet temperature of the high-temperature fan does not exceed 400℃.

3. When the temperature at the outlet of the decomposition furnace drops to 600 ~ 650℃, the material is completely stopped and the kiln speed is reduced to 0.5r/min to control the fuel

4, reduce high temperature fan draft.

 

5, with the reduction of wind, reduce the rotary kiln kiln head feeding fuel, do not make the raw material out of the kiln.

6. Stop spraying water on the humidifier, and then continue to reduce wind.

7. When the tail temperature drops below 800℃, stop the kiln head to feed fuel, then stop the high-temperature fan, open the cold air valve, and control the air volume with the inlet valve of the kiln tail exhaust fan.Note that after the fuel is stopped at the kiln head, maintain the necessary primary air volume to prevent deformation of the coal injection pipe.

8. Stop the cylinder cooling air unit and kiln mouth sealing ring cooling fan according to the situation.

9. Stop the big cloth bag at the end of the kiln, return to the conveying system and the raw material feeding system.

10. When the temperature of rotary kiln barrel reaches below 250℃, the auxiliary transfer kiln shall be changed.

11. After the kiln head is turned off, pay attention to the negative pressure control of the kiln head, reduce the gas flow of the grate cooler and let the kiln head exhaust fan exhaust the air.

12, in the kiln discharge is not much, the grate cooler stopped for a period of time, from six to one room each fan stop.

13. Stop kiln head electric dust collector, clinker conveying, primary fan, kiln head electric dust collector exhaust fan, control kiln negative pressure with kiln tail dust collector and exhaust fan.

14. Stop feeding the raw material fan according to the situation and gradually pull out the coal jet pipe.

The above ten strict control words, will be able to reduce the number of kilns, kilns, so that the rotary kiln refractory brick service life increased.

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Characteristics of cooperative disposal of solid waste by cement kilns

Product introduction:https://www.cementepc.net/burning/Cement-rotary-kiln.html

Cement kiln collaborative disposal of solid waste is also the use of high temperature treatment of waste.But different from waste incineration, the collaborative disposal of cement kiln directly utilizes the high temperature of cement production line kiln, and the temperature is much higher than that of waste incineration plant.Characteristics of cooperative disposal of solid waste by cement kilns.
 

(1) high incineration temperature.

The temperature of materials in cement kilns is generally higher than 1450℃, and the temperature of gas is higher than 1750℃ or so, even higher than 1500℃ and 2200℃.Under this high temperature, the organic matter in waste will produce thorough decomposition, general incineration removal rate of 99.99% above, for the waste of toxic and harmful components will be thoroughly "destroyed" and "detoxification".

(2) long stay.

Cement rotary kiln tube body long, waste in the cement kiln high temperature state for a long time.According to the general

According to the statistical data, the total residence time of materials from kiln head to kiln tail is about 4omin.The residence time of the gas above 950℃ is more than 8s, and the residence time above 1300℃ is more than 38, which can make the waste under high temperature for a long time

Good for waste combustion and thorough decomposition.
 

(3) stable burning state.

The rotary kiln of cement industry has a very stable combustion system with high thermal inertia.It is composed of rotating dense metal cylinder, brick masonry in kiln, crust formed in the firing zone and materials to be fired. It not only has a huge mass, but also increases the thermal inertia of the system due to the thermal insulation performance of refractory materials, and will not cause large temperature fluctuation due to the change of waste input and nature.
 

(4) good turbulence.

The flow direction of high-temperature gas and material in cement kiln is opposite, and the turbulence is strong, which is conducive to the mixing, heat transfer, mass transfer, decomposition, combination and diffusion of gas-solid phase

(5) alkaline environmental atmosphere.

The raw material composition used in the production of cement determines that there is an alkaline atmosphere inside the rotating density. The alkaline material inside the cement density can be neutralized with the acidic material in the waste as stable salts, which can effectively inhibit the discharge of acidic material and facilitate the purification of its tail gas. Moreover, it can be carried out together with the cement process.
 

(6) no waste residue is discharged.

In the process of cement production, there are only raw materials and clinker produced by calcining process, and there is no problem of slag produced by incineration in general incinerator
 

(7) solidify heavy metal ions.

The most heavy metal ions in the waste can be solidified in the clinker and finally into the cement product, avoiding the re-diffusion
 

(8) reduce overall emissions.

The substitution of combustible wastes for mineral fuels reduces the demand of the cement industry for mineral fuels (coal, natural gas, heavy oil, etc.).Overall, the emission of waste gas (CO2, SO2, CI, etc.) from cement production and incineration alone is greatly reduced.

(9) chu burning disposal points, strong adaptability.

The firing system of different process in cement industry, no matter it is wet kiln, semi-dry kiln, preheating kiln and cyclone preheating kiln with decomposition furnace, the whole system has different high temperature feeding points, which can adapt to different kinds of wastes of different properties and forms.
 

(10) good waste gas treatment effect.

Cement industry firing system and waste gas treatment system make the waste gas after combustion go through a long path and good cooling and dust collecting equipment, and have a high adsorption, sedimentation and dust collecting effect. The collected dust can be reused through the conveying system and returned to the raw material preparation system.
 

(11) the construction investment is small and the operation cost is low.

The use of cement compact-cement for waste disposal, despite the need for necessary modifications in process equipment and feeding facilities, and the need for new waste storage and treatment facilities, has greatly reduced investment compared with the construction of new dedicated incinerators.In terms of operating cost, although the depreciation of equipment, consumption of electricity and raw materials, labor costs and other costs increase, burning combustible waste can save fuel and reduce fuel costs. The higher the proportion of fuel replacement, the more obvious the economic benefits.

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