Some problems in the operation of the ball mill

The ball mill is the key equipment for crushing the material after it has been crushed.

The ball mill is one of the high-fine grinding machines widely used in industrial production.

There are many types, such as hand ball mill, horizontal ball mill, ceramic ball mill, ball mill bush, energy-saving ball mill, ball mill enamel ball mill.

1. How to properly operate the ball mill by the ball miller This is an important issue in the beneficiation process. At present, mining development is relatively hot, and skilled workers are relatively scarce. Many of them have not been formally trained and have been employed, which has caused huge economic losses to mining enterprises. In addition, the operation of grinding is a practical experience in production, and many engineers and technicians are not very clear, and the technical experience in this area cannot be found in various books. To this end, according to the author's years of experience in production and commissioning guidance and the combination of theoretical and technical, the operation of the grinding machine is elaborated.

As a ball miller operation, the factors that need to be adjusted without relative adjustment are: raw ore hardness, crushing particle size, grid sieve hole, ball mill model, steel ball mass, steel ball addition amount, steel ball size ratio, ball mill speed, classifier speed The distance between the impeller of the classifier, the height of the spindle of the classifier, the wear of the classifier blade, the overflow of the classifier, the height of the opening under the classifier, the opening size under the classifier, the opening height on the classifier, and the opening size on the classifier. This part of the factors is the early stage of design and process. Of course, many concentrators now have problems with unreasonable design, equipment installation or equipment quality. This part of the factors are now explained.

Ball mill model selection: Different ball mill models can meet different process technology requirements. This factor must be reasonably selected during design. See the selection and calculation of the ball mill.

The ball mill is equipped with different cores, and the gears of the large and small gears have deviations.

The gear of the gear reducer of the ball mill has sand holes, and the equipment is installed, and there are still several classes, gear wear and other problems.

The following focuses on the important parameters of the daily adjustment of the ball mill, which is also an important content that directly reflects the level of ball mill operation and the utilization rate of grinding. Mainly: the size of the water supply of the ball mill, the size of the flushing at the discharge port of the ball mill, and the size of the ore.

There are several aspects that can be noticed for the aura of the ball mill. One is to see if the ball mill gives the mine mouth, and the other is to listen to the ball mill sound. If the ball mill is swollen, the sound becomes small and stuffy. The third is to watch the ball mill current. The control cabinet, in particular, emphasizes that if the ball mill is swollen, its current value becomes smaller, and many operators and engineers think that it is just the opposite. They think that the ball mill is swollen because the amount of mineral in the ball mill is large, and its current value is changed. Big, this is the wrong view. The principle is: the ball mill is swollen, because the amount of minerals in the ball mill is more, and when the ball mill has more ore, the steel ball and ore are operated together with the barrel of the ball mill, and the ore size of the ball mill discharge port becomes thicker. At this time, the ball mill does less work, and the electric energy is converted into kinetic energy, and the electric energy is correspondingly smaller. When the voltage is constant, the electric energy becomes smaller, and the change is caused by the current value becoming smaller.

2. How to effectively improve the grinding fineness is one of the important links in the beneficiation operation, because the cost of grinding operation is a higher part of the ore dressing plant. How to effectively and reasonably control the grinding fineness is directly reduce the ore dressing cost. To improve the economic factors of the plant selection. Grinding fineness is one of the many factors affecting the beneficiation index. The size of grinding fineness directly affects the level of concentrate and the recovery rate of the product. Therefore, the technical operation of the ball miller is important.

First of all, we must fully understand the influencing factors of grinding fineness. In summary, the factors affecting the fineness of grinding are: raw ore hardness, crushing particle size, sieve mesh, feed amount, ball mill model, number of steel balls, steel ball size ratio, ball mill liner wear, ball mill speed, grading Machine speed, grader spindle lift height, classifier blade wear, grader overflow height, classifier lower opening height, classifier lower opening size, classifier upper opening height, classifier upper opening size, return sand flow size, ball mill The size of the water supply, the size of the water at the discharge port of the ball mill, etc.

Understand all of these influencing factors, we need to find one by one in the production operation to find the best adjustment factor.

Raw ore hardness: different ores, the hardness is not the same, this factor is fixed relative to the same ore, and can not be adjusted. However, in the production, under the premise of the mineral processing technology requirements, reasonable ore distribution can be carried out, the ore size can be made as uniform as possible, and the block and powder mineral ratio is reasonable and stable. In addition, in the belt of the ball mill belt, the belt may leak due to long-term wear, and most of the leakage is powder ore. This part of the mine must be added to the ball mill as soon as possible. If it is stacked for a long time, it will be concentrated. Adding will cause uneven grinding of the ball mill and cause unstable production. Especially difficult to mine, often the properties of powder minerals and block minerals are not the same.

The height of the grader's main shaft is also an important factor affecting the amount of sand return and the fineness of grinding. Normal normal production requires the grader spindle to be in place. Some ore dressing mills have not cleaned the ore in the classifier after the equipment has been overhauled. Under the long-term sinking, the mud sinks more. When the grader spindle is lowered, the spindle is not completely lowered because it is not careful. , resulting in less sand than normal. In addition, if the spindle is not lowered, it may be because the spindle has not been cleaned and oiled for a long time, so pay attention to it during the operation.

The size of the crushed grain and the adjustment of the sieve mesh are closed. The ball miller must supervise the crushing system. If the particle size of the ball mill changes during production, it must be reflected to the crushing workshop immediately. The final requirement is that the finer the particle size, the finer the better.

Blade wear of the classifier: After the blade is worn, the amount of sand return is reduced, resulting in coarser grinding fineness. In addition, if the blade is worn out, it will affect the life of the classifier. Therefore, the blade wear condition should be checked in time and replaced in time. Wear the blade. Ball mill speed, classifier speed, classifier impeller spacing: fixed at the time of purchase of the ball mill, pay attention to the consultation at the time of purchase.

The level of the overflow of the classifier affects the size of the sedimentation area of ​​the ore. In the production, we can adjust the level of the overflow of the classifier according to the requirements of the fineness of the grinding. If the fineness of the grinding is required to be fine, grader welding two edges of a certain height angle iron, wooden pull plug method to adjust the level of the classifier overflow weir, sometimes after long-term accumulation of sludge, can naturally raise the height of the overflow weir.

The height of the opening under the classifier, the size of the opening under the classifier, the height of the opening on the classifier, and the size of the opening on the classifier are on-site during the installation of the equipment. In many factories, because the size of the opening of the classifier is not adjusted during the installation of the equipment, The workers did not pay much attention to the operation process, and the invisible also affected the grinding operation. The lower opening of the classifier is relatively large, so the sedimentation area of ​​the ore is larger, so the amount of sand returned will be larger, the fineness of the grinding is relatively fine, and the opening under the classifier is large. The sedimentation area of ​​the ore is larger, the water flow is more gentle, so the amount of sand returned. It will be large, the grinding fineness is relatively thin, the opening on the classifier is low, the amount of sand returned is relatively large, the fineness of grinding is relatively thin, the opening on the classifier is large, the relative amount of sand returned is relatively large, and the fineness of grinding is relatively thin. Otherwise the opposite.

First of all, we have to assume that all other influencing factors are normal. The principle is: in the case of a certain fineness of grinding, we must maximize the amount of processing, which can effectively improve production efficiency. (Except for most of ores, minerals specific) In contrast, the finer grinding fineness, solutions useful minerals and gangue minerals from the more fully advantageous to improve the recovery of metals, so a certain amount of ore processing conditions Under, as much as possible to improve the fineness of grinding. In addition, grinding is the first step in the beneficiation process. In order to ensure the stability of production, the grinding should be as stable as possible.

In the case of a certain amount of ore, the size of the flushing at the discharge port and the size of the ore directly affect the fineness of the grinding. In many domestic mines, the grinding automation is not realized, and the amount of water is directly carried out by the ball miller. Manual adjustment, because the water flow in these two places is large, it is difficult to see the increase and decrease, so careful observation and fine adjustment must be required. First of all, we understand that the ball mill water supply increases, the grinding concentration becomes thinner, and the grinding fineness becomes coarser. On the contrary, the ball mill water supply decreases, the grinding concentration becomes larger, and the grinding fineness becomes finer. The flushing water at the discharge port of the ball mill becomes larger, the overflow becomes thinner, and the overflow fineness becomes finer. On the contrary, the flushing water at the discharge port of the ball mill becomes smaller, the overflow becomes thicker, and the overflow fineness becomes thicker. Therefore, in other conditions, including the same amount of minerals, to improve the fineness of grinding, the ball mill water supply can be reduced, and the flushing water at the ball mill discharge port is increased. It is best to adjust these two conditions at the same time to ensure The fluctuation of the flotation is caused by the change in the amount of the ore caused by the adjustment of the fineness of the grinding. In many factories, due to the operation of the ball miller, the amount of ore is greatly changed, resulting in instability of the flotation liquid level. If the flotation worker does not process it in time, the metal recovery rate and grade change are caused. The opposite is true if the fineness of the grinding is coarsened.

Under the premise of grinding fineness guarantee, the amount of ore given by the ball mill can be increased. The size of the ore is given to meet the grinding fineness requirements, while the ball mill does not swell. The entire process must be carried out in detail in all aspects.

3. In addition to the above-mentioned various aspects, the fineness of grinding is also related to the proportion of steel balls added. How to add steel balls according to the size of the steel ball depends on the diameter of the ball mill, the hardness of the ore, the ore particle size of the goal mill, the hardness of the steel ball (mass), the speed of the ball mill, and other factors.

When the model of the ball mill is determined, the speed of the ball mill is also fixed. The hardness of the ore is measurable. The ore particle size of the goal mill is determined by changing the size of the sieve. How to add steel balls to the ball mill according to the size of the steel ball? Now the authors put the perennial practice and theoretical experience as follows:

Usually, the newly installed ball mill has a running-in process. During the running-in process, the amount of steel balls is added for the first time, accounting for 80% of the maximum ball loading of the ball mill. The proportion of steel balls added can be according to the size of the steel ball (Φ120mm, Φ100mm , Φ80mm, Φ60mm, Φ40mm) size added.

Steel ball addition: Different ball mill models have different total ball loading. For example, the MQG1500×3000 ball mill (processing capacity 100-150 tons) has a maximum ball loading of 9.5-10 tons. The first addition of steel ball (Ø120mm and Ø100mm) accounted for 30% to 40%, the medium ball 80mm accounted for 40% to 30%, and the small ball (Ø60 and Ø40mm) accounted for 30%. Why is the ball volume only 80% added during the ball mill running-in process? After the ball mill is installed, the size of the ball mill needs to be meshed, and the amount of processing (the amount of ore) is gradually increased. After the ball mill runs normally for two or three days, the ball mill is stopped. Check the meshing of the large and small gears, wait until everything is normal, open the ball mill manhole cover and add the remaining 20% ​​steel balls for the second time.

After the ball mill is turned on and running normally, the addition of each class of steel balls is added by 3:4:3 (Ø120mm is 3, Ø100mm is 4, Ø80mm is 3). Note: The addition of small steel balls is only the first time with the addition of the ball. Because, when the ball mill is in normal operation, the reasonable grinding between the steel ball and the steel ball, the steel ball and the ore, the steel ball and the ball mill lining will increase the wear, make the big ball grind small (grinding into the middle ball), the middle ball grinding For small balls. Therefore, under normal circumstances, there is no need to add a small ball. In the case of adding a small ball, there is no monomer dissociation at the useful mineral particle size, and when the fineness of the mill is not up to the flotation requirement, an appropriate amount of small balls can be added.

In the ball mill, the steel ball wears continuously during the operation. In order to maintain the ball filling rate and the reasonable ratio of the ball and maintain the stable operation of the ball mill, it is necessary to carry out reasonable ball filling and low compensation.

The weight added by the steel ball is determined according to the quality of the steel ball and the quality of the steel ball. It is best to use a new wear-resistant steel ball. The best (good quality) steel ball addition is calculated according to the amount of ore processed per ton (ie 0.8kg per ton of ore). A typical steel ball needs to process one ton of ore (1kg to 1.2kg).

Steel ball size ratio: different ball mill models have different ratios. The diameter of the ball mill is below 2500mm, and the size of the added steel ball is Ø100mm, Ø80mm, Ø60mm. The diameter of the ball mill is more than 2500mm, and the size of the added steel ball is Ø120mm, Ø100mm, Ø80mm.

In addition, different equipment and different minerals have different operations on the equipment.

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