As a common grinding equipment, ball mills are widely used in power, chemical, mining, cement and other processing sectors. At present, the popular ball mills on the market are diverse in variety, versatility and price.
1 ball mill classification
1.1 Classification by the shape of the cylinder (by length to diameter)
1 short tube ball mill: the length L of the cylinder is less than 2 times the diameter D of the cylinder, that is, the ball mill with L≤2D is a short barrel mill, which is usually a single-story structure, mainly used for rough grinding or first-level grinding operations. The efficiency is high, and 2-3 billiard mills can be used in series at the same time, which has a wide range of use. 2 medium and long ball mill: medium and long ball mill when the length of the cylinder is L=3D. 3 long ball mill: Long ball mill when the length of the cylinder is L≥4D. It is generally divided into 2-4 positions.
1.2 Classification of grinding media by mill
1 The grinding medium loaded in the steel ball mill is mainly steel segment or steel ball. The grinding machine has a large grinding force, and the structure is light and the rotation speed is stable. 2 rod mill is mainly used for grinding steel rod media. The diameter of steel rod is between 50-100mm and the grinding time is longer. The number of bins in a bar mill is generally two to four, and there is a certain difference in the grinding media loaded in each bin. To ensure the final result of the grinding, the staff placed the cylindrical steel bar in the first bin and the steel ball or steel segment in several other bins. 3 The grinding medium in the gravel mill mainly includes pebbles, gravel, sand, porcelain balls and the like. Gravel mills use porcelain or granite as the lining, and are widely used in the production of colored cement, white cement and ceramics.
1.3 Classification by unloading method
1 tail discharge mill: The tail discharge mill uses its first and last tails as the inlet and outlet of its abrasive. When the mill is in operation, the worker feeds the abrasive from the inlet end and discharges it from the other end. 2 medium-discharge mill: the inlet of the medium-discharge mill is at both ends, and the outlet is in the middle of the mill. The worker usually feeds the abrasive from both ends and then discharges it from the middle of the cylinder.
1.4 Classification by mining method
1 Overflow type: discharge through the hollow shaft. 2 lattice type: discharge through the grid plate. 3 Peripheral type: discharge through the periphery of the cylinder.
1.5 Classification by transmission mode
1 Center drive ball mill: The drive power end of this type of mill is in the center of the fuselage, and the motor realizes the operation of the ball mill through the reducer. During operation, the hollow shaft in the center of the ball mill drives the grinding body to rotate under the drive of the power system. 2 edge drive ball mill: The motor drives the gear at the edge of the cylinder through the reducer to drive the cylinder movement.
1.6 Classification by job characteristics
1 Wet mill: Water is added at the same time as the feed, discharged into a certain concentration of slurry, and closed in the closed circuit system with the hydraulic grading equipment . 2 Dry mill: Some discharge materials are extracted by wind flow, and the mill and the wind classification device form a closed circuit. For example, the cement mill adopts self-flow discharge.
2The working principle of the ball mill 2.1 The structure of the ball mill
Schematic diagram of the ball mill
The internal structure of the ball mill is more complicated and has more components. In recent years, with the deepening of the concept of energy saving and emission reduction, the ball mill has gradually developed towards energy saving. The main components of the ball mill include the mill barrel, end caps, bearings, and transmission components. Among them, the transmission parts of the ball mill have a V-belt, a motor, a reducer, and a pulley. In order to ensure the grinding efficiency of the cylinder, workers often put steel rods or steel balls with a diameter of 25-150mm in the cylinder to increase the grinding rate. The loading amount usually accounts for 25%-50% of the cylinder volume. In addition, an inner liner is also embedded in the cylinder. The end caps are located at the two ends of the cylinder, and are connected with the flanges at the bottom of the cylinder by screws, and have small holes in the middle to ensure the smooth discharge of the exhaust gas. The bearing supports the hollow shaft diameter, which effectively reduces the friction between the cylinders and prolongs the service life of the cylinder. Large gear ring: fixed on the cylinder.
2.2 Introduction to the abrasive process
The abrasive work is carried out in the barrel of the ball mill, and the motor drives the rotation of the cylinder and the gear ring through the coupling, the reducer and the pinion. The material enters the feeding device through the inlet end of the mill and enters the first chamber of the mill at a constant speed with the movement of the hollow spiral. The chamber is provided with a corrugated lining plate, which can effectively reduce the friction between materials. At the same time, the lining plate is also equipped with grinding balls of different specifications and sizes, which are selected by the staff according to actual work needs. When the cylinder rotates, the steel ball will make a uniform linear motion under the influence of the rotating force and the reverse force of the mill, and will slide down all the time. In addition, under the influence of the above two kinds of forces, the steel ball will generate a certain frictional force with the cylinder body, and the steel ball will revolve with the axis of the cylinder body, so that it is carried away by the cylinder body near the cylinder liner. When it rises to a certain height, the medium falls parabolically or falls down due to its own weight to grind the material in the cylinder. After the coarse grinding is completed, the material is transferred from the first bin to the second bin. The friction of the bin is smaller than that of the first bin, and the material can be ground more finely and finely. The second chamber is provided with a flat lining plate, and when the grinding is finished, the powder material is discharged from the discharge raft.
2.3 Ball mill classification
Overflow type ball mill: This type of mill sprinkles the ground material on the right side of the machine body under the rotation of the cylinder, and finally causes the finished product to overflow from the empty journal. The abrasive processing process is relatively compact, and the classification operation is realized, which effectively reduces the grinding cycle load. Lattice type ball mill: This ball mill has a special grid plate at the discharge end, which is composed of a plurality of fan-shaped orifice plates, and the widths of the upper and lower ends are slightly different. Among them, the upper end has a large width, generally 7mm-20mm. In the actual processing process, the worker puts the processing material through the gap between the grid plates, and then lifts the material into the air by the lifting force of the material, and then passes the cone to the right to the hollow journal discharge machine. outer.
Wind-discharge ball mill: After the material is fed into the ball mill from the inlet, it will enter the first bin with the mill's rotary motion. After a series of impacts and frictions, it will move to the right to other bins where the material is worn for further deep processing. The pipeline system mainly includes a dust collector, a fan inlet, a classifier, and the like. When the wind system is in working condition, the internal pressure of the ball mill body also drops, and finally reaches a low negative pressure state. When the milled material becomes loose with the rotation of the mill, and the wind enters the pipeline system from the discharge port, the coarse particles are separated by the powder separator and then sent to the ball mill inlet, and the fine powder is separated and recovered by the separator. It is discharged into the atmosphere by a fan.
2.4 Grinding movement state
When the filling rate of the steel ball reaches 40%-50%, the rotation speed of the ball mill will also change accordingly. At the same time, the following three basic motion states will occur in the grinding medium, which will achieve more grinding and less grinding, and reduce the grinding force. , greatly improving production efficiency and reducing power consumption. The first type of motion has a higher rotational speed. Under the action of the centrifugal force of the fuselage, the steel ball will rotate together with the barrel body, that is, a uniform circular motion. At this time, the grinding medium cannot effectively exert its grinding and impact effects, and the grinding effect is better. difference. In the second operating state, the rotation speed is too low, the friction between the material and the grinding medium is small, the grinding effect is not obvious, and the grinding effect is also limited. In the third grinding state, the rotation speed of the mill is relatively stable. After the grinding machine rises to a certain height with the cylinder, it will fall back into the cylinder at a constant falling state, and the grinding effect is sufficient, which effectively reduces the particle size of the product. High processing capacity.
3 ball mill development prospects
At present, most of the ball mills in China are still in manual manual control, which causes large changes in materials, low grinding efficiency, large unit power consumption, and large loss of steel balls and linings. Moreover, since the grinding state changes greatly, it is difficult to ensure the uniformity of the fineness of the material. Planetary ball mills are designed for crushing, grinding, and dispersing powders and are widely used in laboratory research. The working principle is to grind the material by the high-speed running force in the mill grinding tank. During the turning process, the material is finally subjected to a series of shearing, impacting, rolling, dispersing, etc. to complete the grinding operation. Planetary ball mills have four grinding balls on one turntable. They work with the grinding shaft to rotate, that is, planetary motion. During the movement, the four tanks grind the material by frictional collisions. The mill can select the corresponding friction method according to the size of the abrasive grains of the material, and the final abrasive diameter can be up to 0.1 micron. It can well realize various process parameters and is the first choice for grinding process, new materials and coating research.
Good Quality Cummins Natural Gas Generator Set,
Applied gas:
Natural Gas, Biogas, LPG, Landfill gas, Oil gas, Syngas, Coal mine gas
Acceptable fuel gas pressure: 5~12 kPa CH4 content: for natural gas ≥85% CH4 content:for biogas ≥55%
Gas heat value ≥5500 kcal/Nm3 (23MJ/Nm3 ). Genset output power will increase as the gas heat value increase, if use low heat value gas for fuel (Heat value< 5500 kcal/Nm3, it will lower the power efficiency.
Gas doesn`t include free water or free materials (the size of impurities should be less than 5μm.)
H2S content ≤200 mg/Nm3,NH3 content ≤20 mg/Nm3, Impurities content ≤30 mg/Nm3;size ≤5 μm,Water content ≤40 g/Nm3, no free water.
Standard Scope of Supply:
1. Brand new gas Engine, 90% parts include engine body , crank shaft, cam shaft, piston, cylinder head, etc made by Cummins with best quality
2. Brand new brushless France Leroy Somer alternator
3. Rating: 3 phases 4 lines. 400/230V, 50 HZ , 1500rpm, 0.8PF, IP22-23, Insulation class H
4. Radiator for 40°C/50°C ambient temperature
5. Ignition system adopted USA ALTRONIC
6. Emergency stop mounted
7. Battery,Battery cable and Battery charger
8. Standard tool box
9. Standard Accessory for installation (include bellows,silencer,flange,asbestos pad,Anti-rust water,screw )
10. Gas Train include Regulator valve,Electromagnetic Valve, Fire arrestor,Ball Valve (Chinese brand)
Accessories list
1. Maintenance Operation manual
2. Quality certificate, Gen-sets ex-factory testing report
Optional:
1. Sound-proof canopy 2. CHP system 3. Grid parallel system 4. Remote radiator 5. Auto oil filling system 6. Water heater 7. Oil heater 8. Gas leaking detector 9. Flame detector 10. Gas scrubber
Natural Gas Generator
Natural Gas Power Generator, Portable Natural Gas Generator, Natural Gas Home Generators, Natural Gas Backup Generator
Weifang Huatian Diesel Engine Co., Ltd , https://www.enginepart.nl