1. What are the types and distinctive features of the mill? Answer: According to the different media of the mill , the medium is steel ball, it is called ball mill ; the medium is steel rod, it is called rod mill; the medium is gravel, it is called gravel mill; the one with its own ore is called self-grinding machine . Adding the right amount of steel balls to the mill to form a so-called semi-autogenous grinding machine. According to the shape of the casing and the method of discharging the ball; the ball mill is divided into a short cylindrical, tubular, conical overflow drainage and lattice discharge, and the rod mill is divided into a cylindrical overflow discharge and an open low level discharge. The self-grinding or semi-autogenous grinding machine is mainly short cylindrical. 2. What is the representation of the mill specifications? A: The method of representation is: diameter × length, symbolized as D × L, such as 2700 × 2100mm ball mill, its diameter is 2700mm, length is 2100mm. 3. What is the grinding process of the ore grinding machine? Answer: When the mill is rotated at a certain speed, centrifugal force is generated to generate friction between the medium and the cylinder, and it is rotated together with the cylinder. When it reaches a certain height and its gravity is vigorously centrifugally, it is thrown away from the cylinder. Crush the ore. At the same time, due to the sliding phenomenon inside the medium, the ore also has a grinding effect. Under the action of the impact force and the grinding force of the medium, the ore is crushed. 4. How many kinds of motion trajectories are there in the mill? Answer: There are three kinds of movement trajectory: 1. sloping type (during low speed operation); 2. throwing type (at normal speed); 3. centrifugal operation (consistent medium and cylinder movement trajectory). 5. What is the law of movement of the medium in the mill? Answer: There are four main points as follows: 1. When the mill is running under a certain speed, the medium has a regular cyclic motion under the action of centrifugal force and gravity; 2. The movement track of the grinding medium in the cylinder is determined by The upward movement of the circular path and the downward movement of the parabolic trajectory are formed; 3. The rise height of the medium of each layer is different. The height of the outermost layer to the innermost layer medium is sequentially decreased; 4. The rotation period of each layer medium is different, and the closer to the inner layer, the shorter the rotation period. 6. What is the critical speed and how is it calculated? Answer: The speed at which the "outer centrifugation" is usually started in the outermost grinding medium in production is called the "critical speed" of the mill. The calculation method is as follows: critical speed Where: D—the effective diameter of the mill barrel, ie the diameter of the barrel gauge minus the average thickness (meters) of the liner. 7. What is the type and characteristics of the ball mill? Answer: The ball mills commonly used in the selection plant have two types of grid type and overflow type. The difference between them is that there is no fan-shaped grid plate device in the overflow type of ore discharge part, and the slurry of the overflow type ball mill is automatically discharged through the discharge port. Since the grid type is equipped with a grid plate, it has a forced discharge effect, thereby increasing the throughput and reducing the over-grinding of the ore. 8. What are the components of the ball mill? A: It is mainly composed of six parts: the cylinder part, the ore department, the mine discharge department, the transmission part, the bearing part and the lubrication system. 9. What are the components of the mine part? Answer: The ore part is composed of the end cap of the hollow journal and the ore feeder and the journal inner sleeve. 10. What are the types of mine feeders? A: The beneficiation plant used to mill ore unit types are: drum, scroll to the mine and the joint is three. 11. What are the components of the mine discharge section? (Grid type) Answer: The mining part consists of the end caps of the hollow journal, the sector lattice plate, the center lining plate and the journal inner sleeve. 12. What is the working characteristic of the rod mill? A: Its working characteristics are: it crushes the ore by crushing and grinding caused by the "line contact" of the steel rod. Therefore, the selective crushing effect reduces the over-grinding of the ore and the product has a uniform particle size. 13. What are the technical indicators of the grinding and grading unit? A: The main technical indicators are: grinding fineness, grinding machine production capacity and operating rate, classification efficiency, grinding efficiency. The former is the quality indicator and the latter is the quantity indicator. 14. What is the representation of grinding fineness? A: The fineness of the grinding product is usually sieved with a 200 mesh sieve of “standard sieve†and expressed as a percentage of the total amount of the sieve (the “mesh†is within the layer of each inch of the screen. The number of sieve holes, and used to name the sieve). 15. What is the definition and calculation method of the mill utilization coefficient? Answer: The mill utilization factor is the amount of raw ore that can be processed per cubic meter of effective volume per cubic meter per unit time, expressed in tons per meter. That is, the mill utilization coefficient q = Q / V (ton / m 3 · hour). 16. What is the definition and representation of the production capacity of the mill? Answer: The production capacity of the grinding machine, that is, the amount of raw ore that can be processed by the mill per unit time (hours) under the condition of certain ore and product particle size, expressed in tons/set·hour. 17. What are the operational factors that affect the operation of the grinding-classification unit? A: It can be roughly summarized as the following three categories: 1. The nature of ore. Including hardness, mud content, ore size and required fineness of grinding products. 2. The structure of the mill. Including mill type, specifications, speed and so on. 3. Operating conditions. There are mainly grinding media, pulp, concentration, sand return ratio and classification efficiency. 18. How to choose the shape of the grinding medium? Answer: According to the purpose and experiment of grinding, the spherical and P2 rod-shaped medium has the best grinding effect; the spherical medium collides with point contact during grinding, so the grinding efficiency is high, suitable for fine grinding, but with rod grinding Compared with the phenomenon of excessive pulverization, generally when the ore particle size is below 30mm and the product particle size is not less than 1mm, the efficiency of using rod grinding is higher. 19. What is the selection principle of the grinding media material? Answer: When selecting the material of the medium, it should be considered comprehensively from the specific gravity, hardness, wear resistance, price, processing and manufacturing conditions of the material. The general use of steel or iron material. In production, the large ball is usually made of steel, the small ball is usually made of iron, the coarse grinding is made of steel, and the fine is made of iron. In recent years, rare earth medium manganese ductile iron balls have been successfully replaced by steel balls. 20. What is the size system for grinding media? A: The size of the ore is determined according to the nature of the ore. The coarser the ore size, the larger the medium should be added to produce a larger impact grinding effect. Conversely, a smaller size medium can be used to enhance the grinding effect. 21. What is the definition of the media filling coefficient and the relationship with the mill rotation rate? (one of the media principles). Answer: The filling rate, which refers to the percentage of grinding media to the volume of the mill, and its relationship with the mill rotation rate is as follows: Media Filling Rate % Suitable Milling Rate % 32～35 76～80 38～40 78～82 42～45 80～84 22. What is the grinding efficiency? What kinds of representations does it have? A: It refers to the amount of minerals that can be processed for every kilowatt-hour (one degree) of electricity consumed. The methods are as follows: 1. The tonnage of raw ore processed per kilowatt hour of electricity consumption, ie tons/degree. 2. Calculate the tonnage of grinding products at a specified level (usually -200 mesh) for every kilowatt hour consumed. 3. Calculated by surface area ton/kWh. 23. What is the technical efficiency of the grinding machine? Answer: It refers to the ratio between the percentage of qualified fractions in the product obtained after grinding and the percentage of the original fraction contained in the ore. 24, what is the qualified size? Answer: The so-called qualified grain size is that the upper limit of the particle size should be less than the specified maximum particle size, and the lower limit of the particle size should be subtracted from the excessively crushed part. 25. How to improve the technical efficiency of the mill? What should be paid attention to in the operation of the mill? A: To improve the efficiency of the mill technology, consider the following aspects: 1. Adopt closed circuit grinding process. 2. In the selection of equipment, coarse grinding should use the rod mill with peripheral discharge, and fine grinding should use lattice type ball mill. Pay attention to the following aspects in the operation of the mill. 1. Appropriate cyclic load should be used in closed-circuit grinding; 2. The speed of the mill should be controlled properly; 3. The ball loading system should be reasonable; 4. The concentration of grinding should be appropriate. 26. What is the passing ability of the mill? How to calculate? Answer: The passing capacity of the mill refers to the total amount of minerals that can be passed in a unit of time. The calculation method is: In the formula: q - the ability of the grinding machine to pass, ton / m 3 · hour. Q—— Calculate the productivity of the mill according to the ore, t/h. C - returning sand ratio, in multiples. V——The effective volume of the grinding machine, m3. 27. What are the phenomena when the grinding machine “swellsâ€? A: The following phenomena generally occur: 1. The main motor ammeter indicates that the current is decreasing; 2. The grinding machine discharges a large amount of ore and the slurry is poured out; 3. The coarsening phenomenon of the overflowing machine of the classifier is serious, and the returning sand is obviously increased; 4, the grinding machine is running dull, unable to hear the impact of the steel ball. 28. What are the methods for loading the grinding media size of the ball mill? A: There are two main methods: 1. According to the total grain size of the mill, the principle is: the ball diameter is compatible with the grain size of the ore, and the ball volume is compatible with the grain size of the ore. 2, simple method: the proportion of various balls is proportional to the diameter of the ball mill. 29. What should be done in the operation when the grinding machine is inflated? Answer: First of all, it is necessary to analyze the change of ore properties, whether the amount of ore, water supply, sand return, and overflow particle size are normal. The following measures can generally be taken in operation: 1. Reduce the amount of ore fed to the mine or stop feeding to the mine in a short time; 2. Adjust the water consumption, that is, strictly control the grinding concentration; 3. Reasonably add grinding media. 30. Why does the current of the main motor drop when the grinding machine “swellsâ€? A: The operation of the grinding machine and the grinding of the ore need to consume energy, and most of the energy is consumed in the grinding process of the ore. Due to the “bloatâ€, the grinding effect is greatly reduced. Thus, convert electrical energy to the grinding action of mechanical energy is greatly reduced, showing the main motor current drops; from the moving condition of grinding media, due to "bloating", the material is increased, increasing the concentration of copper ball is lifted height reduction The grinding force is small, so the kinetic energy is reduced and the current is decreased. 31. How much does the ball mill load have on the grinding process? How much is the filling rate qualified? Answer: The amount of ball loading has a certain impact on the grinding efficiency. The ball is loaded less, the mill efficiency is low, and the ball is loaded too much. During operation, the inner ball is easy to interfere and destroy the normal circulation of the ball. Grinding (crushing) ore efficiency is also reduced. Practice has proved that the amount of ball loading is related to the rotation rate of the mill. When the mill's running speed is low, you can install more balls, and when the speed is high, you can install less. For lattice type ball mill: filling rate φ=40-45% For overflow ball mill: filling rate φ=35-40% 32. Why should the steel ball be loaded into the mill in a certain proportion according to the size? Answer: The size and size of the steel ball are mainly determined by the physical and mechanical properties of the ore and the granularity of the ore. For the treatment of ore with large hardness and coarse grain size, it is necessary to have a large impact force. It is necessary to add a steel ball with a larger size. The soft ore of the ore is less (less) than the soft ore. If the product size is fine, the grinding should be Mainly, it can be loaded into steel balls of smaller size. The production site ball mill is loaded with balls of various ball diameters. According to a certain proportion, to deal with materials composed of different sizes of ore particles. In theory, only by ensuring that a certain proportion of the balls can be adapted to the particle size composition of the material to be ground can a good grinding effect be obtained. 33. What happens if the big ball or small ball in the mill is too small? Answer: When the material size is large or the hardness is large, the proportion of the large ball will be rough, and the fineness of the grinding product will not be achieved. Moreover, the throughput is also limited, affecting the grinding efficiency. When processing materials with small ore size and low hardness, if the ratio of small balls is small, the product size will be coarse. The ball should be added as appropriate, and the proportion of the ball should be increased to suit the nature of the ore to obtain better product fineness. Therefore, the proportion of the ball must be strictly proportional, to prevent the imbalance. 34. What is the type of lubricant and the type of lubricant? What is the cycle? Answer: 1. Size gear: 40-50# mechanical oil, add twice per shift, change oil once every six months. 2. Hollow bearing: One-half of 50# mechanical oil is mixed with one-half of 24# or 28# mechanical oil, added once per shift, and oil changed for 3 months. 3, small gear rolling bearing: calcium-based grease drop T = 90 ° C, added every shift, half a year oil change. 4, reducer gears and bearings: 40-50# mechanical oil, added to each shift, 3 months for oil. 5, the motor: calcium-based grease drip, T = 120 ° C, half a year to change the oil. SMT Special Splice Tape, black anti-static splice tape with diagonal triangle design, pass the feeder easily. 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Grinding operations 34 questions and answers