Types and materials of ball mill steel balls
The ball mill is the key equipment for grinding after the materials are crushed. It is the core machine in many industries such as cement and chemical industry. The steel ball components occupies an important position in the ball mill equipment, which drives the operation of the whole machine and affects the production volume.
Types of ball mill steel balls
1. Forged steel balls: use better wear-resistant materials, such as 60Mn, 65Mn, which have the characteristics of good quality, good impact resistance, strong toughness, and good wear resistance.
2. Cast steel balls: The production of cast steel balls is relatively simple, and the production investment is small. It has the characteristics of low energy consumption, high impact toughness, flexibility, etc., and because the operation is easy to master, it has won the favor of the majority of users.
3. Hot-rolled ball-milled steel ball: It has the characteristics of good forming, small geometric tolerance and stable quality. The wear rate is low, the service life is 2 to 5 times that of the existing cast iron balls and forged steel balls, and the price is moderate.
Ball mill steel ball material
1. High manganese steel: This material has good toughness, good manufacturability, and low price. Its main feature is that under the action of greater impact or contact stress, the surface layer will quickly produce work hardening, and its work hardening index is higher than other materials 5-7 times, the wear resistance is greatly improved.
2. Low-carbon alloy steel ball: The steel ball made of low-carbon alloy has good toughness and low price. Under the same conditions, its service life is more than twice as long as that of low-chromium cast balls.
3. High chromium cast iron: a wear-resistant material with excellent abrasion resistance, but low toughness, brittle fracture, and expensive.
4. High-carbon and high-manganese alloy steel: The material is mainly alloy structural steel containing chromium, molybdenum and other elements, with high hardness and good toughness. Under the same working conditions, its service life is more than twice that of high manganese steel balls.
Daily maintenance and dust removal of bag pulse dust collector
During the trial operation of the new bag filter, special attention should be paid to check the following points:
1) The direction of rotation, speed, bearing vibration and temperature of the fan.
2) Whether the disposal air volume and the pressure and temperature of each test point are consistent with the design.
3) The device status of the filter bag, whether there is any occurrence of bag drop, loose mouth, abrasion, etc. after use, can be judged by visual inspection of the discharge status of the chimney after it is put into operation.
4) Pay attention to whether there is condensation in the bag room and whether the ash discharge system is unblocked. Avoid infarction and corrosion attacks. When the fouling is serious, it will affect the efficiency of the host.
5) Adjustment of the cleaning cycle and cleaning time. This work is an important factor affecting the performance and operation of dust collection.
6) If the cleaning time is too long, the attached dust layer will be removed, which will be the cause of leakage and damage of the filter bag. If the dust removal time is too short and the dust on the filter bag has not yet been removed, the filter operation will be resumed. The resistance will quickly recover and gradually increase, which will ultimately affect the application effect. At the beginning of the operation, some unexpected conditions are often present, for example, abnormal temperature, pressure, moisture, etc. will cause damage to the new installation.
The test operation of the equipment directly affects whether it can be put into normal operation. If it is not handled properly, the bag filter may quickly lose its efficacy. Therefore, it is necessary to be careful and cautious to do a good job in the test operation of the equipment.
- Frequently check the operation status of control valves, pulse valves and timers, etc.
The failure of the impulse valve rubber diaphragm is a common phenomenon, which directly affects the cleaning effect. This equipment belongs to the external filter type, and the bag is equipped with a skeleton. It is necessary to check whether the parts fixing the filter bag are loose, whether the tension of the filter bag is appropriate, and whether the supporting frame is smooth to avoid abrasion of the filter bag. Compressed air is used for dust removal, so oil mist and water droplets need to be removed, and the oil-water separator must be cleaned frequently.
- Avoid condensation
During use, it is necessary to prevent the gas from cooling below the dew point in the bag chamber, especially when using the bag filter under negative pressure. Because the shell often leaks air, the air temperature in the bag room is lower than the dew point, and the filter bag will be damp, causing dust to adhere to the filter bag, blocking the fabric holes, resulting in a cleaning failure, and causing a pressure drop in the dust collector If it is too large, it cannot continue to operate, and some generate paste bags and cannot remove dust.
To avoid condensation, the temperature of the gas in the dust collector and its system must be 25～35℃ higher than the dew point (such as the dew point temperature of the kiln-grinding integrated machine is 58℃, and the operating temperature should be above 90℃) to ensure Good use effect of filter bag.
Maintenance measures of ball mill
The maintenance of the ball mill is a must for the operator. The formulation of reasonable maintenance measures is the key method to prolong the service life of the ball mill, increase the production capacity and reduce the failure rate, and it is also a direct method.
- Keep the equipment clean
Cleaning work is a must for the ball mill. Only by removing all the impurities inside and outside the machine can the normal operation of the equipment be ensured. If there are too many impurities, not only will it be difficult to start the equipment, but also the phenomenon of grinding and poor output will occur. The key is to cause damage to the equipment to a certain extent. It is recommended to clean the ball mill regularly, such as the base. When there are too many impurities in the base, it is easy to rust. Therefore, the impurities should be removed first, and the base should be cleaned.
- Reasonable lubrication
After the ball mill is used for the first time and continuously operated for one month, the lubricating oil must be replaced once (select the correct lubricating oil). When replacing, all lubricating oil must be removed, and the ball mill should be cleaned, and then replaced with new lubricating oil. In the subsequent use of the ball mill, the lubricating oil must be replaced every six months of operation. When it is found that there is too much oil shortage, the cause should be analyzed in time. At the same time, the lubrication of each lubrication point should be strengthened. It is recommended to add grease to the lubrication point every week during the running-in period, except for special requirements.
- Periodic inspection
Regularly check and repair all parts of the ball mill, so that not only the abnormalities and problems of the machine can be found in time, but also the occurrence of failures can be prevented. At the same time, the ball mill will be maintained. For example, check whether there is oil leakage on the joint surface, whether there is water leakage and whether there is a leakage phenomenon, and determine the use state of the fastener. Especially for some vulnerable parts, the frequency of inspection and timely maintenance and repair should be strengthened to extend the service life of the parts and increase the service life of the ball mill.
Factors affecting the output of ball mill
Ball mill is a commonly used grinding equipment, and the output is an important indicator to measure the quality of the ball mill. So what are the factors that affect the output of the ball mill?
1. The volume of the mill. Under normal circumstances, the larger the volume of the mill, the greater the processing capacity.
2. What is the water content of the material? If the water content of the material is too high, it will affect the uniformity of the feeding and make the feeding time too long. Secondly, if the wet material is fed too much, it may cause the phenomenon of "sticky grinding". Therefore, the moisture of the feed is usually required.
3. Loading capacity of grinding body. After the mill runs for a period of time, the output will become lower and lower. This is because with the impact and grinding of the grinding body in the cylinder, the grinding body will wear out, so the grinding body must be refilled in time. But it is not that the more abrasives, the better. If the steel balls accumulate too high, the impact of the steel balls on the material will be slowed down, and on the contrary, the grinding output will be reduced.
4. Grinding time. If the grinding time is too short, it will cause insufficient grinding of the material. In addition, starting the mill frequently will shorten the service life of the equipment. If the grinding time is too long, the temperature in the cylinder will increase, which will affect the grinding efficiency.
5. The ball mill is "full grinding". After the ball mill has been running for a period of time, due to the excessive feed of the ball mill or the increase in the particle size of the material, or the excessive moisture of the material entering the mill, the grate gap of the grate plate will be blocked, which will cause the material in the mill to be unable to be discharged out of the mill in time, and "saturated grinding" "The phenomenon affects the output of ball mills. In this case, it is necessary to adjust the materials, clean the grate seams, and increase the ventilation in the mill.
6. Adding ratio of grinding aid. Grinding aids can promote the grinding of materials, but most of the grinding aids are substances with strong surface activity and are not suitable for all materials, so the amount of grinding aids added should meet a certain proportion.
When the output of the ball mill is found to be lower and lower during the production process, it should be investigated in turn to find out the problem and resume production as soon as possible.
Why should talcum powder be surface modified
Talc has a wide range of applications in various industries. As an inorganic filler, it can improve the rigidity, strength, hardness, and lubricity of products. With the development and needs of modern industry, higher and higher requirements are put forward for the performance of talc, especially the demand for ultra-fine talc in the domestic and foreign markets.
Why should talcum powder be surface modified?
Like other non-metallic mineral powder materials, the surface organic treatment of talc is very necessary. This is because the surface of talc powder contains hydrophilic groups and has high surface energy. As inorganic fillers and organic polymer molecular materials, there are great differences in chemical structure and physical form, lack of affinity, and need Surface treatment of talc particles is carried out to improve the interfacial bonding force between the talc powder and the polymer, and to improve the uniform dispersion and compatibility of the talc powder particles and the polymer.
In addition, when ultrafine talc is applied to coatings, due to its large surface area, more wetting dispersions are needed, which is difficult to disperse and affects the performance of coatings. Nowadays, some talcum powders with high oil absorption in latex paints are not processed by many manufacturers or only simple surface treatments, so its application is greatly restricted.
Surface modification method of talcum powder
The mechanism of talc modification is to use some small molecules or polymer compounds with amphoteric groups to modify the surface of one or two of the materials to be composited, with the purpose of better combining the two materials.
Product features of talc modifier
Talc modifier is a low molecular weight polymer, which integrates the functions of grinding aid, modification, lubrication, coupling, dispersion, etc. Each molecule has multiple amphiphilic groups, and its adsorption on the surface of inorganic powder is Part of the amphiphilic group faces the surface of the inorganic powder, and the other part faces the oily solution, and associates with the solution through intermolecular force or hydrogen bond, thereby forming a three-dimensional barrier to prevent particle contact and agglomeration, and play a role in inter-particle dispersion.
Talc modifier has excellent modification, grinding aid, dispersion and coupling effects, which can greatly reduce the oil absorption of the powder, and make the powder have hydrophilic and lipophilic characteristics, and improve the compatibility with the resin system, so as to achieve Low-viscosity processing requirements in plastic and rubber production.
(1) Surface coverage modification method
The surface coating modification method is to cover the surface of the particles with a surfactant or talc modifier, so that the surfactant or talc modifier is combined with the particle surface by adsorption or chemical bond, giving the particles new properties and making the particles The compatibility with the polymer is improved.
(2) Mechanochemical method
This method uses grinding, friction and other methods to make relatively large particles smaller, so that the surface activity of the particles becomes larger, that is, the surface adsorption capacity is enhanced, the process is simplified, the cost can be reduced, and the quality of the product is easier to control.
Why should calcium carbonate be surface modified
Surface modification is an important means necessary to improve the application performance of calcium carbonate, improve applicability, expand the market and consumption. In the future, functionalization and specialization will become the main trend of calcium carbonate development, and the market demand for various surface modification special calcium carbonate The amount will get bigger and bigger.
Why should calcium carbonate undergo surface modification?
- Improve the dispersibility of calcium carbonate
Ultra-fineness is an important way to improve the quality of calcium carbonate, but the smaller the particle size of calcium carbonate, the higher the surface energy, the stronger the adsorption, and the more serious the agglomeration phenomenon.
Through surface modification, the modifier can be oriented to adsorb on the surface of calcium carbonate, so that the surface has charge characteristics. Due to the repulsion of the same kind of charge, calcium carbonate is not easy to agglomerate, thereby achieving good dispersion in the matrix.
- Improve the compatibility of calcium carbonate
Through surface modification, the interface compatibility and affinity between calcium carbonate and organisms can be increased, thereby improving its product performance with rubber or plastic composite materials.
- Reduce the oil absorption value of calcium carbonate
Surface modification is an important means to reduce the oil absorption value of powder. After the surface modification of calcium carbonate, the aggregated particles are reduced, the degree of dispersion is improved, and the gap between the particles is reduced. At the same time, the coverage of the surface of the calcium carbonate by the modified molecules reduces the voids in the particles, and this coverage also changes the calcium carbonate. Its surface properties weaken its surface polarity, the friction between particles becomes smaller, and the lubricity becomes better, so the packing becomes tighter, the packing density increases, and the oil absorption value decreases.
- Broaden the high-end application market of calcium carbonate
Calcium carbonate without surface modification has poor compatibility, is easy to agglomerate, and has poor application effects, and these shortcomings become more obvious as the dosage increases.
Through surface modification, calcium carbonate has good interface affinity and reduced oil absorption. It can be better applied to high-end fields such as plastics, coatings, rubber, paper making, sealants, and breathable membranes to improve product quality and further reduce application companies’ Cost of production.
- Give calcium carbonate more functional properties
Calcium carbonate without surface modification can only be used as a traditional filling material, and its application field and dosage will be subject to certain restrictions. Through surface modification, calcium carbonate becomes a multifunctional modifier.
Calcium carbonate coated with silica on the surface can partially replace white carbon black and supplement the shortcomings of white carbon black in certain properties; light calcium carbonate coated with metal on the surface can improve certain special properties of rubber products; The calcium carbonate composite material coated with titanium dioxide can replace titanium dioxide to a certain extent; it can be treated with phosphate, aluminate, silicate or barium salt to prepare acid-resistant calcium carbonate.
- Increase the added value of calcium carbonate products
At present, my country's ordinary calcium carbonate has overcapacity, and competition for low-price products is fierce. After surface modification of calcium carbonate, the use effect is significantly improved, the user experience is good, and the product price naturally increases.
The operation points of the air classifier
In the ultra-fine classification equipment, the main product is the air flow classifier. It is necessary to understand the basic operation of the air flow classifier.
1. Before starting the equipment, check the connection parts, seals and wiring, etc., and start operation only after all checks are correct.
2. The power-on operation should be performed in accordance with the power-on sequence. 3 minutes before shutting down, stop feeding, and then shut down again, the order is opposite to the order of starting up.
3. The feed volume should be determined according to the load of the main engine to ensure that the main engine is under the rated load.
4. The fineness of the separated particles can be adjusted to meet the classification requirements.
5. If it is to separate heat sensitive materials, the power of the main motor should be slightly lower than the rated power.
6. The size of the air volume in the conveying pipeline can be realized by adjusting the air door of the fan.
7. The tension of the belt should be checked to prevent belt slippage.
Correct use of jet mill
The application of the jet mill is very wide, and some matters need to be paid attention to when using it, including the preparation work and operation process before starting the machine, maintenance work and so on.
1. Preparation before starting
Check whether the host, connecting machine, pipes and valves are in good condition and can work normally.
2. Turn on
(1) Turn on the compressor power supply, dust collector pressure valve and main air valve, turn on the power switch of the airflow grinder, and turn on the power switch.
(2) Start from zero and gradually adjust it to the specified speed.
(3) Turn on the power of the fan, cyclone separator, dust collector, and charging motor, turn on the total power box number, set the frequency of the inverter, and then start charging.
(4) The particle size of the finished product can be adjusted according to the frequency and loading capacity of the grading wheel.
3. The sequence of stopping is: frequency converter-feeder-main air valve-compressor-grading impeller motor-cyclone material, dust removal switch-fan-general power supply-air compressor.
4. Maintenance
(1) The motor should be lubricated regularly, but the lubricating oil should not be excessive to avoid excessive bearing temperature.
(2) It is important to check the wear of the impeller, screw conveyor and grinding nozzle.
(3) After the material is ground, the rubber powder in the machine should be cleaned to avoid clogging, thereby affecting the grinding effect.
(4) After a period of use, the filter bag should be cleaned or replaced.
5. Matters needing attention
(1) When the unloading equipment is in operation, the unloading outlet cannot be reached to avoid accidents.
(2) The speed of the impeller should not exceed the regulation, otherwise the temperature will be too high and the impeller and motor will be damaged.
(3) The safety valve should be checked regularly to ensure safety.
The details that need to be paid attention to when using the superfine grinder
The ultra-fine pulverizer adopts a unique design scheme. After improvement, the blade is no longer used, and the cutter head and liner are specially installed according to the design structure of the fuselage. In order to improve the grinding efficiency and effect, the ultra-fine pulverizer uses high-speed impact force and shear force to make the material in the grinding cylinder subject to the squeezing, kneading and tearing of the medium, which greatly shortens the grinding time and improves the grinding efficiency; At the same time, because the material is fluidized and each particle has the same stress state, its self-viscous effect can make the finished product form a uniformly dispersed and precise composite particle group, increase the density and increase the bioavailability, and improve the micro-grinding effect and technology.
When the ultra-micro grinder is working, the material to be grinded is fed into the machine from the feeding hopper on the side of the machine casing. It relies on the grinding roller device suspended on the plum frame of the main machine to revolve around the vertical axis. At the same time, it rotates on its own. The centrifugal force causes the grinding roller to swing outwards and press tightly on the grinding ring, so that the shovel blade scoops up the material to be sent between the grinding roller and the grinding ring, and the grinding roller achieves the purpose of grinding the material due to the rolling and rolling of the grinding roller.
Wind separation process: After the material is ground, the fan blows the wind into the main frame to blow up the powder, which is sorted by the classification device placed above the grinding chamber. The products that meet the specifications enter the cyclone collector with the wind flow, and are discharged through the powder outlet after being collected, which is the finished product. The wind flows back into the fan from the return duct at the upper end of the large cyclone collector. The wind path is circular and flows under negative pressure. The increased air volume of the circulating air path is discharged through the exhaust pipe between the fan and the main engine and enters the small cyclone collection. Refrigerator for purification treatment.
The ultra-micro grinding machine is composed of three parts: main machine, auxiliary machine, and electric control box. It has various properties such as winnowing type, no screen, no net, uniform particle size, etc. The production process is continuous. The ultrafine pulverizer has reached the international advanced level and is widely used in the pulverization of materials in the pharmaceutical, chemical, and food industries. The ultra-micro grinding machine is a horizontal tilting structure, composed of a base, a motor, a crushing chamber, a cover, and a feeding hopper. The feeding hopper and cover can be tilted to a certain angle, which is convenient for cleaning and repairing the material in the grinding chamber. For processing hard and difficult-to-grind materials, it can also be used as a supporting equipment for the previous process of micro-grinding. It is not restricted by the viscosity, hardness, softness and fiber of the material, and it can have a good grinding effect on any material. .
Precautions for ultra-micro grinding machine:
1. General medicinal materials do not need to be screened by the ultra-micro grinder, but for pearls and stalactites that require precise particle size, please pass the screen.
2. The ground material should be dried, especially the viscous material needs to be dried, so that the ultrafine grinder will have a better crushing effect. The volume should not be too large, about the size of a little finger nail.
3. Do not clean the grinding tank.
4. After using the superfine grinding machine, please unplug the power plug to avoid any danger caused by touching the switch.
5. When the speed slows down, please check whether the aggregate cloth tube of the superfine grinder is well ventilated, or there is too much material in the collecting cylinder. Turn off the power switch).
What factors are related to the surface modification effect of ultra-fine powder?
The surface modification of powder is mainly to reduce the energy of ultrafine powder through the powder modifier to achieve the effect of uniform dispersion. The effect of the surface modification of the powder is related to the powder processing technology, the processing technology of the back-end products，the system compatibility，material formula and others.
1. The nature of powder raw materials
The specific surface area, particle size, particle size distribution, specific surface energy, surface physical and chemical properties, and agglomeration of the powder raw materials all have an impact on the modification effect, and are important factors for selecting powder modifier formulations, process methods and equipment. one.
For example, the surface physical and chemical properties of the powder, such as surface electrical properties, wettability, functional groups or groups, dissolution or hydrolysis characteristics, directly affect its interaction with the powder modifier molecules, thereby affecting the effect of its surface modification . At the same time, the physical and chemical properties of the surface are also one of the important considerations when choosing a surface modification process.
2. Powder modifier formula
The surface modification of the powder is to a large extent achieved by the action of the powder modifier on the surface of the powder. Therefore, the formula (variety, dosage and usage) of the powder modifier has an important influence on the modification effect of the powder surface and the application performance of the modified product. The powder modifier formula is highly targeted, that is, it has the characteristics of "a key to open a lock". The formula of the powder modifier includes selection of varieties, determination of dosage and usage, etc.
When selecting a powder modifier, the properties of the powder raw materials, the use or application field of the product, as well as factors such as process, price, and environmental protection should be considered comprehensively, and based on the structure and properties of the powder modifier and its relationship with the powder. Mechanism of action, targeted selection.
3. Ultra-fine surface modification process
After the powder modifier formula is determined, the surface modification process is one of the most important factors that determine the surface modification effect. The surface modification process should meet the application requirements or application conditions of the powder modifier, have good dispersibility to the powder modifier, and be able to realize the uniform and firm coating of the powder modifier on the powder surface; at the same time, the process is required Simple, good parameter controllability, stable product quality, low energy consumption and low pollution.
Therefore, at least the following factors should be considered when choosing a surface modification process:
①The characteristics of the powder modifier, such as water solubility, hydrolysis, boiling point or decomposition temperature, etc.;
②Whether the front-stage grinding or powder preparation operation is wet or dry. If it is a wet process, consider adopting a wet modification process;
③Surface modification method. The method determines the process. For example, for surface chemical coating, either dry or wet process can be used; but for precipitation coating of inorganic powder modifier, only wet process can be used.
At present, the commonly used surface modification processes mainly include dry process, wet process, pulverization and surface modification combined into one process, drying and powder modifier use methods combined into one process, etc.