Mining Ore Crushing Equipment Expert

Henan Province, China

Zhengzhou West Industrial Zone,451200

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Overflow ball mill

MoleDive One-Stop Overflow ball millSolution - Production Capacity Ranging from 5 to 500 Tons Per Hour

Overflow ball mill is mainly composed of cylinder, end cover, main bearing, hollow journal, transmission gear and feeder. The ball mill is divided into grid type ball mill and overflow type ball mill according to different ore discharge methods, which is the most common mill used in the concentrator. The conical ball mill has been eliminated because of its low productivity, many types of liner and difficult maintenance, and it is still used in some old concentrator.

The overflow ball mill barrel is welded with a steel plate with a thickness of 15-36mm. Flanges made of cast steel are welded at both ends of the barrel, and the end caps 2 and 3 are connected with the flanges with bolts. The two must be precisely machined and matched, because the hollow journal bearing the mass of the mill is welded on the end cap. The cylinder body is provided with 1-2 individual holes for maintenance and replacement of lining plates. Lining plates are laid inside the cylinder body and the end cap. A hollow journal on the end cover is supported on main bearing 4. The main bearing is commonly used plain bearing, which has a large diameter but a short length. The bearing bush is cast with babbitt alloy, which is different from ordinary plain bearings in that only the lower half has the bearing bush. The whole bearing is made of cast iron except for the bearing shell cast with babbitt gold. Due to the large span and load of the ball mill, a certain degree of deflection will occur, and the manufacturing and assembly errors are difficult to ensure accurate concentricity, so the main bearing is made of automatic aligning plain bearings, in order to prevent the bearing bush from being too large and sliding out of the bearing seat, a cylindrical pin is placed in the center of the spherical surface of the bearing seat and the bearing bush

Raw Materials

MoleDive Overflow ball millGuide

1. What is the difference between overflow type ball mill and lattice type ball mill?

The drainage side of the grate type ball mill is equipped with a grate plate, hence the name. There are many 7-20mm discharge holes on the grid plate. After grinding through the ball mill, the material passes through the grid plate, and the side of the grid plate near the discharge end is equipped with the pulp lifting device, which is a radial edge bar, which divides the grid plate and the end cover into a number of fan chambers leading to the hollow journal. When the ball mill rotates, the radial edge plays a role in lifting the pulp, lifting the pulp discharged from the hole on the lattice plate to the discharge hollow journal, and discharging from the ball mill through the hollow journal.

The structure of overflow type ball mill is basically the same as that of grid type ball mill, the difference is that there is no grid plate at the discharge end of overflow type ball mill. In addition, the inner surface of the hollow journal bushing of the overflow ball mill is equipped with an anti-spiral blade, which can return the small steel ball and large coarse particles spilled in the pulp to the ball mill. Overflow ball mill discharge mainly depends on the pulp itself higher than the lower edge of the hollow journal bushing and self-flow overflow, overflow ball mill is also named for this.

2. The difference between the working principle of overflow type ball mill and lattice type ball mill?

The overflow type ball mill is driven by a low speed synchronous motor, connected with the pinion device through the air clutch, which drives the surrounding large wheel to decelerate and drive the rotary part to rotate; The cylinder body is equipped with appropriate grinding media (steel ball) and materials, grinding media and materials under the action of centrifugal force and friction, along with the rotation of the cylinder is raised to a certain height, and then according to a certain linear speed is thrown down, the material to be ground from the feeding part into the cylinder continuously, by the moving ore and steel ball impact. And the grinding and grinding between the ball and the ball and the liner plate of the cylinder. And through the power of continuous feeding the product is discharged from the machine to complete the grinding process to carry out the next process.

The working principle of the grid type ball mill is mainly to rotate slowly through the transmission device, and the material is fed from the barrel to the feeding end, and the material is crushed in the barrel due to the throwing impact and self-grinding of the steel ball and the ore itself. Due to the continuous feeding of material, its pressure causes the material in the cylinder to move from the feeding end to the discharging end. The material reaching the finished particle size is discharged from the discharge end of the cylinder. When wet grinding, the material is carried out by the water flow; During dry grinding, the material is carried out by air flow. The mill has a discharge grid at the discharge end, the mill relies on the grid plate to force ore discharge, and the pulp surface in the cylinder is low, which reduces the ore grinding and prevents the steel ball from being discharged.

3..The difference between the performance of overflow type ball mill and lattice type ball mill?

Compared to overflow type ball mills, grid type ball mills have low-level forced discharge, lower pulp surface at the discharge port, and can timely discharge finely ground ore particles. Minerals with higher density are not concentrated in the ball mill, greatly reducing material overgrinding. In addition, the grid type ball mill has a large ball loading capacity, and both large and small steel balls can be loaded without being discharged. Under the same conditions, the grid type ball mill has higher grinding efficiency and production capacity, but its structure is complex, the quality is large, and the price is relatively high.
The overflow type ball mill has a simple structure, which is easy to manage and maintain. However, its discharge liquid level is high, and the material stays in the mill for a long time. Its production capacity is lower than that of grid type ball mills of the same specifications, which can easily cause overgrinding.
Usually, the productivity of a grid type mill is 10% -25% higher than that of an overflow type mill, and the power consumed is 10% -20% higher than that of an overflow type ball mill. The grid type mill consumes a large amount of power, but its production efficiency is high. If calculated based on “ton/kilowatt x hour”, its efficiency index may be higher.