CA2305481A1 - Self-fastened ball mill liner - Google Patents

Abstract

The invention provides an improved liner for ball mill. Self fastened liner consists of Main Plates and Wedging Plates. Different from traditional liner, self fastened liner has four special features:
1. Based on arch theory, Main Plates are fastened by Wedging Plates inside of ball mill cylinder. No bolt type fastener is required for installation.
2. When the ball mill is rotating, balls inside of the mill cylinder shall impact Wedging Plates continually, therefor all these Plates become firmer and firmer.
3. There is no any hole on both Main Plates and Wedging Plates.
4. Main Plates are made of glass-hard steel or porcelain, so the self fastened liner has excellent anti-wear surface.

Description

Self fastened Ball Mill Liner BACKGROUND OF THE INVENTION
Ball mills are widely used in the cement industry, coal-fired power plants, mines and chemical industry. Ball mill liners using durable metal are installed inside the cylinder, usually using numerous bolts. These bolts go through holes that are on the liners and fasten the liners to the mill's cylinder. During operation, with the rotation and vibration of the cylinder, bolts break frequently. Also, liner breakage occurs along the liner's hole. Research shows that most of the broken liners are due to casting stresses and annealing fractures concentrated around the bolt holes of the liners, and in the same time, holes on the liners have to bear all the impacting and banding forces. It is known that the harder the metal material is, the more casting stresses will occur and the easier break. Traditionally, to avoid breakage, ball mill liners are usually made of middle hardness metal such as high manganese steel. The HRC value of the high manganese steel is only about 30, and as a result, these liners are not really durable. A mufti-cast technology to produce liners has been attempted, but the production process is complex and the quality of mufti-cast liners is not stable. Moreover, this kind of liner still needs bolts to fasten them on the cylinder. In fact, using mufti-cast liners could not solve the problem of bolt breakage and liners breakage. The goal of this invention is try to completely improve liner for ball mills; that is, use really hard material to build liners, prevent liners from breaking, solve the problem of bolt breakage, and make the installation easier.
DESCRIPTION OF PRIOR ART
It is known in the prior act to provide improved liner, US patent Number 4,580,734, which issued to Richard E. Erosdey on July 2, 1984, discloses a sectional liner.
DETAILED DESCRIPTION AND SUMMARY OF THE INVENTION
The self fastened liner pertains to new structure and new material liner for ball mills. This kind of liner consists of Main Plates 1 and Wedging Plates 2 (see Figure 1 and Figure 2).
All these Plates are designed as no hole Plates. Based on arch geometry theory, Main Plates 1 are fastened by Wedging Plates 2 inside of ball mill cylinder. When the ball mill is rotating, balls inside of the mill cylinder shall impact these Wedging Plates continually, therefor all these Plates become firmer and firmer.
Experiments show that following long periods of operation using self fastened liner, all Plates nearly formed one integral unit, without any liner breakage. Because there is no hole on these Plates, this design can eliminate casting stress and annealing fracture. Therefor, Main Plates can be made of glass-hard steel or even porcelain. When using glass-hard steel to build Main Plates and with the absence of any bolt fasteners, it is clear that self fastened liner can last a long time and eliminate bolt breakage which commonly occurs with traditional ball mill liners.
Main Plates of self fastened liner are made of glass-hard steel, such as high and middle chromium steel, martensitic iron or porcelain. The function of the Main Plates is resisting attrition. Size of the Main Plates is _I_ based on the demands of ball mills, but the geometrical form of the Main Plates is as illustrated as Figure 1 and Figure 2. Top surface of the Main Plates could be designed as curved surface.
The Wedging Plates are made of mild steel, such as normal lower carbon steel or even hard rubber. The function of the Wedging Plates is fastening. Width of the Wedging Plates is from 3mm to 140mm according to the diameter of mill cylinder. External form of the Wedging Plates is perspective of axial section and radial section of the Main Plates. During the installation, Main Plates and Wedging Plates are simply combined together.
The self fastened liner has already been used for several 3.80 meter diameter ball mills and several rotary pulverizers in different coal-fired power plants and some cement plants. The results in actual production are excellent; the lifetime of the invented liner is at least three times as long as that of traditional liners, no liner breakage occurs and maintenance work is decreased greatly.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a radial section view of the liner of the present invention.
Figure 2 is a cross-section of the line I I of Figure 1.
BRIEF DESCTIPTION OF THE PICTURES
Picture lshows that the self fastened liner has just been installed.
Picture 2 shows that the self fastened liner is still in good condition after 28,080 hours operation.

Claims (6)

1. A sort of liner for ball mill with Main Plates and Wedging Plates.

2. The liner recited in claim 1, based on arch geometrical theory, using Wedging Plates to fasten Main Plates and the Wedging Plates themselves, forming a resisting attrition circle inside of the ball mill cylinder.

3. Both Main Plates and Wedging Plates recited in claim 1, are designed as no hole plates

4. The liner recited in claim 1 does not need any bolts for installation.

5. The Main Plates recited in claim 1 are made of high, middle and lower chromium steel, high, middle and lower chromium cast iron, martensitic iron, spheroidal cast iron, white iron or porcelain.

6. The Wedging Plates recited in claim 1 are made of low carbon steel, wrought iron, or hard rubber.