Second, improve the ball mill output research
2.1 Grinding process
After research, regardless of the fine crush before grinding, there are two kinds of grinding process: open flow and circulation. Under the same conditions, the circulation production is about 20-35% higher than the open flow. For the circulating products, the particle distribution is relatively uniform, and it is convenient to adjust the cement grade; while the open-flow grinding out the grinding material is the finished product, the product particle composition distribution is more dispersed, and the grinding phenomenon is stored, which affects the cement quality output. The uniformity coefficient of the open-flow grinding cement particles is generally 0.8-0.9, even lower, only 0.7, the particle distribution is wide, the cement 3d strength may be higher, but the late strength hydration rate is lower, changing the uniformity coefficient The quality of cement is also difficult. The fine powder needs a large amount of water to increase hydration quickly; and more than 65 μm particles do not hydrate, which does not contribute to concrete strength. Therefore, we suggest that conditional cement plants are best produced by a loop process. The uniform distribution coefficient of the circulating milled cement particles can reach 1.0, which is relatively narrow and the concrete quality is better. This will not only greatly reduce the cost, but also significantly improve the quality of cement.
2.2 Grinding material granularity
Due to the energy utilization rate of the mill during dry grinding, the energy utilization rate is only 2~3%. After years of scientific research and production practice, domestic and foreign engineers and technicians put forward the pre-grinding process of “breaking more and grinding less, grinding and grinding†to make the mill The output has been greatly improved, the power consumption of grinding has also been significantly reduced, and the energy-saving effect of increasing production is very good. The so-called "pre-crushing process" will reduce the particle size of the grinding material from the original 20-25mm to 3-5mm, and transfer the work content of the ball mill I warehouse to the crusher to achieve the goal of improving the ball mill output. According to the product particle size, the crusher is generally called a fine crusher (referred to as a fine crusher). Commonly used fine crushers include jaw crushers, hammer crushers, roller crushers, composite crushers, impact crushers, dryers, and drum dryers.
2.3 Ingredient material moisture and temperature
First of all, it needs to be explained that the moisture of the material to be milled is not as wet as possible. The finer the fineness of the cement, the more sensitive it is to moisture, and the paste is ground when the moisture is not satisfactory. It is generally believed that for every 1% increase in the combined moisture content of the milled material, the mill output will be reduced by 10%. When the moisture is more than 5%, the mill is basically "stopped" from grinding.
2.4 Ball mill barrel ventilation
The internal ventilation of the ball mill is good or bad, which directly affects the grinding efficiency. This open flow mill and the adoption of a natural wind mill are more common problems. Ventilation function will discharge the fine powder in the grinding in time, so as not to affect the grinding efficiency; secondly, reduce the temperature inside the grinding machine to avoid the gypsum dehydration tail silo ball blocking. When the material moisture is too large and the mill is poorly ventilated, the steam in the mill is difficult to discharge, and not only the wet fine powder adheres to the quilting, but also reduces the throughput and flow rate of the material per unit time. At the same time, when the abrasive body grinds the material, the working surface of the lining plate adheres to form a "cushion layer" due to static electricity, thereby causing the grinding body to greatly reduce the impact of the material impact and breakage. When the thickness of the surface layer of the lining board is up to 1 mm, the impact force of the grinding body on the material can be reduced to one-third of the material, which leads to a decrease in the output of the mill and an increase in the power consumption of the grinding. The simpler solution is to add an axial flow fan to the upper part of the grinding cylinder, and at the same time, the sealing rotary screen and the discharge chute of the mill are sealed to prevent leakage of the mill due to air leakage. In this way, the internal ventilation of the mill is smooth, and the problem of ashing of the grinding head is completely solved. Similarly, the air lock system must also be done well. Otherwise, the fan wind is directly removed from the discharge port, forming a short circuit in the ventilation, and there is not much wind in the mill. At present, many factory outlets are equipped with flap valves, and the actual effect is not satisfactory. The air lock device must be remade.
2.5 ball mill liner
The inner structure of the mill refers to the inner liner of the mill barrel, the raft plate, the partition plate inlet and discharge device, and the like. The mill liner is mainly used to protect the cylinder, avoiding the direct impact friction of the abrasive material on the cylinder. Secondly, different types of liner can be used to adjust the movement state of the grinding body in each bin. The production liner of our company is mainly provided by Luoyang Wear Research Institute, and its products have a considerable proportion in the international market and the design is delicate.
2.6 Reasonable adjustment of the grinding body loading (ball mill filling rate) and grading
2.61 ball mill power consumption ratio
It is possible to roughly determine how much power motor should be equipped according to the tonnage of the grinding body load. That is, 1 ton of grinding volume requires about 10-12 kW of motor power. Of course, the actual situation should be determined based on the results of the research department.
2.62 ball mill filling rate
The volume of the grinding body loaded into the grinding mill accounts for the effective volume percentage of the mill, which is called the ball mill filling factor, also known as the filling rate. After a long period of research, it is concluded that the value of the ball mill is related to the structure of the mill, the rotational speed, the grinding form, the coarse or fine grinding, and the material of the grinding body. The filling rate of the ball mill is generally 0.4 or less.
2.1 Grinding process
After research, regardless of the fine crush before grinding, there are two kinds of grinding process: open flow and circulation. Under the same conditions, the circulation production is about 20-35% higher than the open flow. For the circulating products, the particle distribution is relatively uniform, and it is convenient to adjust the cement grade; while the open-flow grinding out the grinding material is the finished product, the product particle composition distribution is more dispersed, and the grinding phenomenon is stored, which affects the cement quality output. The uniformity coefficient of the open-flow grinding cement particles is generally 0.8-0.9, even lower, only 0.7, the particle distribution is wide, the cement 3d strength may be higher, but the late strength hydration rate is lower, changing the uniformity coefficient The quality of cement is also difficult. The fine powder needs a large amount of water to increase hydration quickly; and more than 65 μm particles do not hydrate, which does not contribute to concrete strength. Therefore, we suggest that conditional cement plants are best produced by a loop process. The uniform distribution coefficient of the circulating milled cement particles can reach 1.0, which is relatively narrow and the concrete quality is better. This will not only greatly reduce the cost, but also significantly improve the quality of cement.
2.2 Grinding material granularity
Due to the energy utilization rate of the mill during dry grinding, the energy utilization rate is only 2~3%. After years of scientific research and production practice, domestic and foreign engineers and technicians put forward the pre-grinding process of “breaking more and grinding less, grinding and grinding†to make the mill The output has been greatly improved, the power consumption of grinding has also been significantly reduced, and the energy-saving effect of increasing production is very good. The so-called "pre-crushing process" will reduce the particle size of the grinding material from the original 20-25mm to 3-5mm, and transfer the work content of the ball mill I warehouse to the crusher to achieve the goal of improving the ball mill output. According to the product particle size, the crusher is generally called a fine crusher (referred to as a fine crusher). Commonly used fine crushers include jaw crushers, hammer crushers, roller crushers, composite crushers, impact crushers, dryers, and drum dryers.
2.3 Ingredient material moisture and temperature
First of all, it needs to be explained that the moisture of the material to be milled is not as wet as possible. The finer the fineness of the cement, the more sensitive it is to moisture, and the paste is ground when the moisture is not satisfactory. It is generally believed that for every 1% increase in the combined moisture content of the milled material, the mill output will be reduced by 10%. When the moisture is more than 5%, the mill is basically "stopped" from grinding.
2.4 Ball mill barrel ventilation
The internal ventilation of the ball mill is good or bad, which directly affects the grinding efficiency. This open flow mill and the adoption of a natural wind mill are more common problems. Ventilation function will discharge the fine powder in the grinding in time, so as not to affect the grinding efficiency; secondly, reduce the temperature inside the grinding machine to avoid the gypsum dehydration tail silo ball blocking. When the material moisture is too large and the mill is poorly ventilated, the steam in the mill is difficult to discharge, and not only the wet fine powder adheres to the quilting, but also reduces the throughput and flow rate of the material per unit time. At the same time, when the abrasive body grinds the material, the working surface of the lining plate adheres to form a "cushion layer" due to static electricity, thereby causing the grinding body to greatly reduce the impact of the material impact and breakage. When the thickness of the surface layer of the lining board is up to 1 mm, the impact force of the grinding body on the material can be reduced to one-third of the material, which leads to a decrease in the output of the mill and an increase in the power consumption of the grinding. The simpler solution is to add an axial flow fan to the upper part of the grinding cylinder, and at the same time, the sealing rotary screen and the discharge chute of the mill are sealed to prevent leakage of the mill due to air leakage. In this way, the internal ventilation of the mill is smooth, and the problem of ashing of the grinding head is completely solved. Similarly, the air lock system must also be done well. Otherwise, the fan wind is directly removed from the discharge port, forming a short circuit in the ventilation, and there is not much wind in the mill. At present, many factory outlets are equipped with flap valves, and the actual effect is not satisfactory. The air lock device must be remade.
2.5 ball mill liner
The inner structure of the mill refers to the inner liner of the mill barrel, the raft plate, the partition plate inlet and discharge device, and the like. The mill liner is mainly used to protect the cylinder, avoiding the direct impact friction of the abrasive material on the cylinder. Secondly, different types of liner can be used to adjust the movement state of the grinding body in each bin. The production liner of our company is mainly provided by Luoyang Wear Research Institute, and its products have a considerable proportion in the international market and the design is delicate.
2.6 Reasonable adjustment of the grinding body loading (ball mill filling rate) and grading
2.61 ball mill power consumption ratio
It is possible to roughly determine how much power motor should be equipped according to the tonnage of the grinding body load. That is, 1 ton of grinding volume requires about 10-12 kW of motor power. Of course, the actual situation should be determined based on the results of the research department.
2.62 ball mill filling rate
The volume of the grinding body loaded into the grinding mill accounts for the effective volume percentage of the mill, which is called the ball mill filling factor, also known as the filling rate. After a long period of research, it is concluded that the value of the ball mill is related to the structure of the mill, the rotational speed, the grinding form, the coarse or fine grinding, and the material of the grinding body. The filling rate of the ball mill is generally 0.4 or less.
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