First, the maintenance of the mill
Whether the mill is operating normally, in addition to the quality of the equipment and installation, daily correct maintenance plays an important role. Strict adherence to the safe operation and maintenance procedures of the mill is a prerequisite for ensuring the normal operation of the mill.
Before starting the mill, carefully check whether the connecting bolts are tightened, the keys of the gears, couplings (or pulleys, sprockets), etc., as well as the tightening condition of the mud head or other consolidation bolts of the ore feeder, and the sand tank. Whether there is any foreign matter, whether the oil level in the fuel tank reaches the upper marking position of the indicator (the oil level should not be lower than the lower marking line of the oil level indicator when the mill is running); in the case of a centralized lubrication station, Check that the oil pump and tubing are good (start the oil pump). Indicates whether the meter and safety device are good. There are no debris around the grinding and grading unit that hinders the operation of the equipment and the operation of the workers. When parking for more than 8 hours, when driving again, first use the crane disc to rotate the machine for one week, loosen the load inside the motor and check the meshing condition between the pinion and the large ring gear, and whether there is abnormal noise. When lubricating with an oil ring, check that the cooling water supply is normal.
Mill start: Before starting, contact the production section that is related to the work of the grinding unit, and then start the lubricating oil pump of the grinding machine. The oil pressure is 49~196.13 kPa (0.5~2 engineering atmospheric pressure). The cooling water pressure is normally lower than the oil pressure of 24.5~49 kPa (0.25~0.52 engineering atmospheric pressure). It is believed that the oil flow is normal and has flowed to each lubrication point before the mill can be started, and then the classifier or sand pump is started (there is hydraulic power). When the cyclone is). The mill is idling for 2~3 minutes, and the feeding unit of the mill can be started after the standby group is running normally. The running time of the mill in the case of no feeding is not allowed to be too long, generally not more than 10~15 minutes, so as not to damage the lining and the steel ball.
During the operation of the mill, always pay attention to observation and inspection. The temperature of the main bearing should not exceed 50~65°C. The oil supply of the bearing and the reducer must be paid attention to at all times to ensure the normal oil flow at each lubrication point. The oil temperature in the fuel tank should not exceed 30. ~40 °C; bearings with cooling water should ensure smooth flow of cooling water; often check the lubrication of transmission parts such as large and small gears, main bearings, classifier reducer. When manual lubrication is used, it is necessary to install oil into the bearing and the oil cup in time; pay attention to whether the front and rear end caps, cylinders, discharge bins, classifier overflow tanks and return sand tanks of the mill are leaking or blocked; according to the nature of the ore The condition of the mill is adjusted in time.
Mill parking: Adjacent production sections should be notified before parking is planned. After the ore in the mill is finished (usually within 10 to 12 minutes), the water supply is stopped. When the room temperature is below zero, the cooling water in the bearing sleeve (oil ring lubrication) should be released to prevent freezing and damage the bearing; the screw of the spiral classifier is lifted beyond the sand surface in the classifier to stop the classifier (or sand pump). Prevent the mill feeder from being blocked by sand return. The motor of the mill can be stopped after the parking preparation is completed, after which the oil pump is stopped.
In the event of a sudden power outage, the mine and water supply must be stopped immediately, and the power supply must be turned off to shut down other equipment. In order to prevent difficulty in starting later, it is preferable to rinse the inside of the mill with water.
Strengthening routine inspection of apricots is an important measure to reduce mill accidents. Check the tightening of all the connecting bolts of the grinding unit every time you transfer the shift. If it is found to be loose, it must be stopped and tightened. If the cylinder liner screw is broken, it should be replaced in time to prevent the cylinder from being scratched or the slurry leaking. Regularly check the wear of the lining, and the grinding should be replaced to a certain extent. When using the oil cup lubrication, the oil in the transmission bearing should be replaced at least once every time: the filter of the oil filter should not be stained, and should be cleaned every 2~3 weeks. The reducer is checked once every 6 months. The amount of media loaded cannot exceed the specified value. If the equipment is found to be abnormal during operation, it should be stopped immediately. Regularly wipe the oil on the surface of the machine to achieve civilized production.
Maintenance of the mill: Reasonable maintenance is an important condition to ensure a high operating rate and a long service life of the mill. The maintenance work of the mill should be combined with operation and maintenance and carried out frequently. In addition to routine maintenance inspections, the maintenance of the mill is carried out on a regular basis with minor repairs, intermediate repairs and overhauls.
Minor repair: once in 1~3 months, the main overhaul project is to inspect, repair or replace worn parts, such as mill liners, clay heads, pinions, couplings and pads. Inlet, discharge chute, motor bearing, etc.; check each fastener; inspection, cleaning and oil change of oil pump and lubrication system; temporary accident repair and minor adjustment, small change and trapping of worn parts.
Medium repair: Usually 6~12 months. In addition to all the minor repairs, the work content of the equipment must be cleaned and adjusted, such as repairing the transmission gears, and replacing a large number of easy-to-grind parts.
Overhaul: The cycle is generally about 5 years. In addition to all the items included in the repair, the maintenance project also replaces the main bearing and the large gear, inspects, repairs or replaces the cylinder and end cover, and adjusts, repairs, and aligns the foundation. .
Our beneficiation plant material mill production practice of wearing parts, equipment service life and the amount included in Table 1. See Table 2 for common faults, causes, and troubleshooting.
Part Name | General material | Service life, month | Minimum spare amount per mill |
Liner Cylinder liner End cap liner Inlet and discharge pipe Grid plate Feeder spoon Feeder housing Main bearing bushing Drive bearing bushing gear Ring gear Liner bolt | High Manganese Steel High manganese steel Cast iron Manganese steel High manganese steel Carbon steel or cast iron Pap alloy Babbitt alloy alloy steel Cast steel Carbon steel | 6~12 8~10 24~36 6~8 2 48 48~60 18 6~12 48~96 6~8 | 2 sets 2 sets 1 set 2 sets 2 1 1 set 2 sets 1 1 0.5 sets |
malfunction | the reason | Method of exclusion |
The main bearing temperature is too high, the journal wears the main bearing to smoke or melt, the bearing jumps or the motor trips | (1) The amount of lubricant in the main bearing is too small or interrupted, and the slurry or powder falls into the bearing and the journal; (2) The main bearing is not properly installed, the cylinder or drive shaft is bent, and the journal and the bearing bush are in poor contact; (3) The lubricating oil is not pure or the viscosity is unqualified (4) The main bearing has less cooling water or too high water temperature | (1) Immediately stop cleaning the bearings and replace the lubricating oil; (2) Repair the main bearing, cylinder, journal and drive shaft, adjust the position of the main bearing, scrape the bearing bush and repair the journal; (3) Replace the new oil or adjust the consistency of the oil; (4) Increase the amount of cooling water or reduce the temperature of the water supply |
Lubricating oil pressure is too high or too low | (1) the tubing is blocked; (2) The viscosity of the oil is unqualified, dirty, and the oil filter is clogged | Eliminate the factors that cause oil pressure changes |
The mill vibrates, the gear drive has a crash or sudden strong vibration and impact | (1) Poor gear meshing or excessive wear; (2) The anchor screw or bearing screw is loose; (3) The large gear coupling screw is loosened by the split nut; (4) The drive bearing wears too much; (5) The gear is broken; the pinion shaft is moving | Adjust the tooth gap and tighten the loose nut; trim or replace bush. Stop and eliminate interdental debris; check and eliminate hidden dangers |
Grinding machine discharge amount is reduced, production is too low | (1) Blocking or breaking the miner; (2) insufficient supply; (3) The grain size of the ore is increased or the ore grindability is deteriorated; (4) Insufficient medium or excessive wear; (5) When the dry grinding, the feed water is large, the gas flow in the mill is poorly circulated or the boring hole is blocked. | (1) Inspection and repair of the ore feeder; (2) Adjust the amount of minerals to eliminate hidden dangers; (3) Adjusting the media ratio; adjusting the discharge point of the mine bin to change the particle size composition of the ore; (4) supplementing the grinding medium; (5) reduce the temperature or moisture into the abrasive; clean the ventilation pipe and the pupil |
The foundation damage causes the bolt to break; the drive shaft is broken, and the transmission and the reducer vibrate; The bearing housing leaks oil and causes damage to the foundation; the drive shaft breaks at the pinion fit | (1) The large ring gear and the pinion gear mesh poorly; the tooth wear is too much; the bearing is installed and the fitting is poor; (2) The basic nut is loose; the coupling is faulty; the shaft center is poorly positioned, and the connection pin load is uneven; (3) The gasket is in poor condition; (4) Fixed chain looseness and poor fit | (1) Check the cleaning ring gear and pinion gear, repair or replace if necessary; adjust the bearing and shaft mounting relationship; (2) tighten the foundation nut; repair the coupling; (3) Replace the bearing seal; (4) tighten the gear keys to adjust the fit |
The grinding machine in the tube grinding machine is weak and boring when working | (1) too much feed or sudden increase in particle size; (2) When dry grinding, the moisture of the material is too much adhered to the working surface of the medium and the liner, blocking the pupil | (1) reduce the amount of feed; (2) Reduce moisture, strengthen ventilation, stop grinding and clean up the pupil |
The motor current is unstable or too high; the motor overload is too large when starting the mill, or the overload time is too long | (1) Mud head activity, loosening the miner; (2) There is debris in the returning sand; the concentration of ore discharge is too high; (3) poor lubrication of the hollow shaft; excessive wear of the gear; (4) The simplified lining plate is unevenly worn and the motor line is faulty; (5) The wet material in the machine will accumulate for a long time, and the ball load will lose the ability to throw or fall off, so that the motor load will increase; | (1) fastening the head of the mud or the ore feeder; (2) Remove debris and adjust operation; (3) Replace or repair the gear to improve lubrication; (4) Replace the lining to eliminate electrical faults; (5) Unloading some steel balls in the mill; mixing and loosening the steel balls retained in the machine; adjusting the amount of ore |
Mill working overload; ammeter reading is unstable | (1) Excessive load in the machine; insufficient bearing lubricant; (2) The drive system is excessively worn or faulty | (1) Adjust the load and increase the oil supply; (2) Inspection and repair of the transmission system (shaft, bearing, shaft, gear) |
Leaking slurry or powder at the bolt of the mill barrel | (1) The lining screw is loose; (2) the gasket is worn; (3) The liner screw is interrupted | (1) tighten or replace the village board; (2) adding a sealing gasket; (3) Replace the liner screws |
The temperature inside the dry mill is too high | (1) The grinding machine has poor ventilation and low grinding efficiency; (2) poor cooling of the cylinder; (3) The temperature of the grinding material is too high; (4) Improper media ratio or thickening of the ore particle size composition or unreasonable allocation of the length of the chamber | (1) cleaning the ventilation pipe and the bore; (2) Strengthening the cooling of the cylinder; (3) reducing the temperature of the material to be ground; (4) Adjust and increase the media ratio of the first and second chambers and the length of each chamber |
In the concentrator with a large amount of processing and a large number of mills, the repair work of the mill is generally carried out on site. Small and medium-sized concentrators usually also set up lifting equipment for maintenance. When the lifting tonnage of the crane is small, two electric or hydraulic jacks can be used to assist the lifting, so that the grinding machine can be inspected on site; large parts are usually sent to the repair shop for repair. When repairing on site, it takes a while to park, but it is more economical. Regardless of which repair method is used, the equipment defect schedule should be prepared according to the records in the unit repair notebook, the accident report form, the grinding machine handover shift and the equipment inspection record before the shutdown repair, and then the equipment repair schedule should be prepared; It also stipulates the repair sequence of each component or machine and the repair work that may be performed in parallel.
Before the machine is shut down, the idling of the mill should be carefully checked to record all parts and parts where noise, impact and vibration occur. Parts with vibration and parts can be measured with a vibrating meter. During the preparation process and when disassembling the mill, the condition of the parts and parts and the clearance values ​​of the friction parts should be recorded in the repair book. After the parts or machines have been repaired, their condition (gap, tolerance, wear that has not been eliminated during repair, accuracy of centering, etc.) should also be recorded in the repair book for reference during use or next repair.
Second, the installation of the mill
Good installation ensures that the mill runs normally, has a long service life and a high operating rate.
The installation methods and sequence of various mills are approximately the same.
Basic requirements: In order for the mill to operate smoothly and safely, the foundation must extend to a stable, solid foundation. The foundation shall be able to withstand the static load and the vibration load generated during the operation of the mill; the foundation shall have a sufficiently large chassis and volume, and the base chassis shall be separated from the chassis of the plant column by at least 50 mm. The weight of the foundation should be 1.5 to 2 times larger than the weight of the mill.
Before installing the mill, it is necessary to check whether the configuration relationship between the foundation and the building and adjacent units is correct. The basic elevation and the size of each main part are in accordance with the dimensions specified in the unit installation drawing. At the same time, the basic construction should be carefully checked. quality.
If the foundation meets the design requirements, the foundation surface can be cleaned, and the loose top of the foundation top surface can be removed with a wind shovel or a hand tool, and the basic centerline and elevation of the installation site are marked. If the base surface is left with grease, it should be treated with caustic soda and neutralizer, or the depth should be removed to avoid affecting the bond between the mortar and the foundation.
After the equipment and foundation are inspected and prepared, the foundation bolts, main bearing chassis and bearing housings can be installed. The horizontal tolerance of the main bearing chassis is 0.10/1000; the relative elevation of the two chassis should generally be measured by the liquid connecting device. It should not be 0.5 mm larger and the feed end is higher than the discharge end. The main bearing housing should be in uniform contact with the chassis, and the local clearance should be no more than 0.1 mm. The spherical surface of the main bearing should be in good contact with the spherical surface of the bearing housing, and the rotation must be flexible. There should be a wedge-shaped gap around the two spherical surfaces, the oblique depth is 25~50 mm, the edge clearance is 0.2~1.5 mm, and the number of contact points on the contact surface should not be less than one in every 50 × 50 mm 2 area. point. When assembling the main bearing shell and the bearing housing, the lubricating oil doped with graphite should be evenly coated on the mating spherical surface. The distance deviation between the centerlines of the two main bearing chassis shall comply with the relevant provisions of the construction and acceptance specifications for metallurgical machinery installation engineering.
When assembling the main bearing shell and the hollow shaft, the contact arc surface should be 70°~90°, and the contact points on the contact surface should not be less than 2 points per 25 × 25 mm 2 area. The sum of the gaps on both sides should be 0.15~0.20% of the journal diameter.
The cylinder and the end cover shall be inspected before assembly. The surface of the cylinder shall be straight. The bending along the axial direction shall not be greater than 0.1% of the total length of the cylinder. The difference between the maximum diameter and the minimum diameter of the end face shall not be the difference between the diameters of the large cylinders. Should be 0.15% of the diameter of the big cylinder, the coaxiality and parallelism tolerance of the flanges at both ends shall be in accordance with the values ​​allowed by the metallurgical installation specifications issued by the Ministry of Metallurgy. When assembling the cylinder and the end cover, the burr flash and paint on the joint surface should be cleaned and coated with lead oil. The joint surface should be in close contact, and no adjustment gasket should be added. Assemble by the mark, the positioning pin must be fully loaded, and the bolt should be evenly tightened immediately after passing the test.
When the cylinder and the end cover are mounted on the main bearing, the axial clearance between the shoulder of the two hollow shafts and the main bearing shall comply with the provisions of the technical documents of the equipment; the busbars on the two hollow shafts shall be on the same horizontal plane, and the height difference shall be It should not exceed 1 mm and the feed end is higher than the discharge end. The center line of the two hollow shafts should be on the same straight line, and the circular runout of the end face of the main shaft should meet the requirements of the installation regulations. During the installation, check the contact between the two hollow shafts and the bearing bush, and the installation rules should be met.
The overall ring gear should be mounted on the cylinder before the cylinder is mounted on the main bearing. The split ring gear should generally be mounted on the cylinder after the cylinder is mounted on the main bearing; the burrs, rust-proof paint and dirt should be removed before assembly. The end face of the ring gear and the flange of the cylinder should be tightly fitted, and the gap should not be greater than 0.15 mm. The pitch of the teeth at the butt joint of the split ring gear shall comply with the provisions of the equipment technical documents, and the deviation shall not exceed ±0.005 modulus. The radial circle of the ring gear beats and should not exceed 0.35 mm per meter. The end face of the circle is rounded and the pitch diameter per meter should not exceed 0.35 mm.
The arrangement of the liner within the barrel should not constitute an annular gap. When assembling a directional liner, its orientation and position should be in accordance with the equipment technical documentation. The annular gap formed between the end liner and the cylinder liner and the hollow shaft bushing is blocked by wooden wedges (wet work), iron wedges or cement (dry work); the gap between the liner and the liner is not Should be greater than 15 mm. Bolts for fixing the lining should be padded with gaskets and gaskets to prevent leakage of slurry and mineral powder. The large opening of the pupil of the compartment plate faces the discharge end.
The center line of the journal and barrel should be checked and adjusted after the main unit is installed. The common heart error shall not exceed 0.25 mm per meter length, the longitudinal and lateral centerline deviation of the mill shall not exceed ±3 mm; the elevation deviation shall not exceed ±5 mm, and the horizontal tolerance of the non-self-aligning spherical bearing mill Not more than 0.1/1000. Finally install the transmission. The parallelism tolerance of the axis of the drive shaft to the axis of the mill should not exceed 0.15/1000. The contact spots of the large and small gears mesh should not be less than 40% along the tooth height, should not be less than 50% along the tooth length, and should tend to the middle of the tooth flanks. The meshing of the large and small gears shall comply with the relevant requirements of the above-mentioned large gear installation. The side clearance of the meshing shall comply with the installation procedures of the ore dressing equipment.
When the feed funnel of the dry mill or the feed pipe of the wind sweep mill is assembled, the contact should be well sealed and no dust is leaked; when using rotary contact, the rotation should be flexible.
After the mill is installed, it should be empty (no medium and material) for 8 hours, during which the transmission gear should not have abnormal sound; the lining plate must not have a knocking sound; the amplitude of the reducer should not exceed 0.05 mm; the amplitude of the transmission shaft should not exceed 0.08 Millimeter; main bearing amplitude does not exceed 0.1 mm. The circular runout of the main bearing end face shall comply with the above requirements for installation. After the idling is passed, the load is tested. Before starting, 20~30% grinding medium should be loaded into the cylinder. After starting, the material should be added. Add 10~25% medium for 2 hours to full load and continue to run for 24 hours. If everything is ok, you can put it into formal use. The commissioning of the tube mill shall be carried out in accordance with the provisions of the equipment technical documents.
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