What Is a Rod Mill?

The rod mill ^[1] is a mill in which the grinding body loaded in the cylinder is a steel rod. Rod mills are generally of the wet overflow type and can be used as first-grade open-circuit grinding. They are widely used in the first-grade grinding of artificial stone, ore dressing plants, and power plants of chemical plants. The mill is mainly composed of a motor, a main reducer, a transmission part, a barrel part, a main bearing, a slow transmission part, a feeding part, a discharging part, a ring seal, a thin oil lubrication station, a large and small gear jet lubrication, a base part, etc. . The main reducer is a parallel shaft with a hard tooth surface. The rod mill is an asynchronous motor that is connected to the small gear through a reducer, which directly drives the surrounding large gears to reduce speed and drive the rotary part to rotate. The cylinder is equipped with a suitable grinding medium-steel rod. The grinding medium is under centrifugal and frictional forces. Under the action of the material, the material to be ground continuously enters the inside of the cylinder from the feeding section, and is pulverized by the moving grinding medium, and the product is discharged out of the machine by the power of overflow and continuous feeding to carry out the next process deal with. The working principle, structure, type, grinding medium, use, installation and installation precautions are introduced in detail.

The rod mill is driven by a motor through a reducer and surrounding large gears, or a low-speed synchronous motor directly through the surrounding large gears to drive the cylinder to rotate. A suitable grinding medium-steel rod is installed in the cylinder. The grinding medium is lifted to a certain height under the action of centrifugal force and friction force, and falls in a state of being dropped or leaked. The milled material enters the inside of the cylinder continuously from the feeding port, and is crushed by the moving grinding medium, and the product is discharged out of the machine through the power of overflow and continuous feeding to carry out the next stage of operation ^[2]

The rod mill is an asynchronous motor that is connected to the pinion through a reducer, which directly drives the surrounding large gears to reduce speed and drive the rotary part to rotate. The cylinder is equipped with a suitable grinding medium-steel rod. The grinding medium is under the centrifugal and frictional forces. Does the material to be ground continuously enter the inside of the cylinder from the feeding section, is crushed by the moving grinding medium, and the product is discharged out of the machine by the power of overflow and continuous feeding for the next stage Process processing.

The mill is mainly composed of a motor, a main reducer, a transmission part, a barrel part, a main bearing, a slow transmission part, a feeding part, a discharging part, a ring seal, a thin oil lubrication station, a large and small gear jet lubrication, a base part, etc. . The main reducer is a parallel shaft with a hard tooth surface ^[3]

There are three types of universal rod mills ^[3]

The grinding medium of a rod mill is a grinding rod. It is generally believed that the length of the grinding rod should not exceed 7 meters, because an excessively long grinding rod is likely to cause entanglement. Therefore, the rod mill used is not too long. 75 ~ 150 mm in diameter ^[4]

Save power

Compared with the old equipment, it can save more than 40% power. The particle size of the product is more uniform, with less coarse particles and slime. The particle size characteristics of rod mill products and ball mill products are compared.

There are roughly three uses of rod mills ^[3]

The technical performance of domestic rod mills is listed in the table:

Types of	Specifications	effective Volume m	Cylinder speed r / min	Maximum loading capacity (t)	Transmission motor	Component weight / t	Mass / t
model	Power / kw	Voltage / v
Overflow rod mill	900 × 1800	0.9	35.4	2.5		twenty two	380	2.04	5.37
900 × 2400	1.2	35.4	3.55		30	380	2.55	5.88
1500 × 3000	5	26	8		95	380	6.92	18
1500 × 3000 (Middle drainage)	4.4	26	13		95	380	7.36	17.29
2100 × 3000	9	20.9	25		210	380	13.77	42.18
2100 × 3000 (Middle drainage)	9	20.9	25		210	380	17.5	57
2700 × 3600	18.5	18	46	TDMK400-32	400	6000	24.7	68
2700 × 4000	20.6	18	46	TDMK400-32	400	6000	28.9	73.3
3200 × 4500	32.8	16	82	TDMK400-36	630	6000	39.5	108
3600 × 4500	43	14.7	110	TDMK1250-40	1250	6000	46.84	159.9
3600 × 5400	50	15.1	124	TDMK1000-36 / 2600	1000	6000	60.7	150

(I) Performance of Rod Mill

The particle size characteristics of the rod mill products are related to the condition of the rod mill. When the rod hits the ore, it first hits the coarse grains, and then grinds the smaller grains, thereby reducing the risk of over crushing. When the rod rotates along the lining, the coarse particles are sandwiched between them, like a rod sieve, allowing the fine particles to pass through the gap between the rods. This is also beneficial for crushing the coarse particles and concentrating the coarse particles in the grinding medium. The place to hit. Therefore, the product of the rod mill is more uniform, and the over crushing is lighter.

(II) Comparison of the uses of rod mills and ball mills ^[4]

Rod mill

1. The mill must be installed on a solid reinforced concrete foundation (the concrete number is not less than 150). If the mill installation position is higher from the ground, the concrete number increases the low area and volume of the foundation accordingly. The allowable bearing capacity of the foundation soil is designed by the relevant professional. The foundation gap of the mill is filled with slate to avoid the vibration generated by the mill during operation to affect the foundation of the building. The contour dimensions of the foundation surface of the installation equipment, if there are no special requirements, Generally, it should be more than 100mm larger than the outline size of the equipment base. After the foundation is completed, it must be specially checked and accepted ^[5]

1. The installation position of the rod mill has a great relationship with the crusher. Depending on the crushing site, the location of the rod mill is also different. Generally, it is installed in the workshop or in the open air.

2. Before installing the rod mill, check the packing list according to the packing list, and check whether the various parts are damaged during transportation, and whether the parts and spare parts are complete.

3. Adjustment of the machine Before the crusher leaves the factory, the manufacturer has already operated in the factory for hours, and all parts are normal. However, after the rod mill is installed on site, a comprehensive inspection should be performed to check whether the oil pipe is connected. Reliably, re-fill the oil before trial operation, and add Mobil special grade for automotive lubrication.

4. Check the connection of each component, it should be firm and reliable, carefully check whether there is any foreign matter on the impeller, and remove it in time if there is any. Check whether the motor wiring is correct and the voltage is normal.

5. Before installing the belt, start the motor first. The direction of rotation should be the same as the direction of the label of the sand making machine, that is, from the feeding port. The direction is the same. For the two-motor driven spindle assembly and the motors on both sides, the same amount of triangle tape is used to connect the spindle assembly with the spindle assembly.

Reasonably and correctly installing the rod mill can not only improve its working efficiency, but also effectively protect the expensive rod mill, extend its service life, and create more value for the enterprise.

The main grinding medium in a rod mill is a steel rod, which is the origin of its name. The machine includes five major components: a barrel, a feed, a discharge, a main bearing and a drive ^[5] .

So how should the rod mill be maintained?
Generally, a rod mill is a kind of milling equipment that operates 24 hours. After the power is turned on, the material feeder continuously feeds. The motor drives the barrel to rotate under the action of the reduction gear. The steel rod and the material in the barrel will move together under the action of centrifugal and frictional forces. Drop by gravity. The final crushed mineral removal and maintenance is a method to effectively extend the life of the machine, so in order to create long-term economic value, the rod mill should pay attention to maintenance during use. We recommend that when the mill is continuously operated for one month, all the lubricating oil in it must be discharged, the machine should be thoroughly and thoroughly cleaned, then new oil should be poured in, and this habit should be maintained regularly. In addition, check the lubrication and oil level of each part according to the operating specifications. During the long-term operation of the mill, the transmission bearings are very hot, but the temperature must not be higher than 55 ° C, so as not to burn the parts and cause a strike.
Regardless of whether it is a rod mill or a ball mill, maintenance is a regular and regular job. The working attitude directly affects the extremely long life and work efficiency. It is recommended that relevant personnel keep records, summarize the rules, and reasonably arrange overhaul and intermediate repair.