HU187610B - Internal armouring for ball mills - Google Patents

Description

This invention relates to internal armor of any type ball mills, ball csőmalmokhoz mainly composed armor örlőlapokból or őrlőgerendákból and these őrlőfelületei are provided running along the entire circumference őrlődob _five grooves.

The purpose of modern internal armor of ball mills is not only to protect the grinding drum against wear, but also to contribute to the efficiency of grinding.

In the state of the art, various inner armor consisting of grinding sheets or grinding beams are known which have either milled or stepped profiles or grinding beams. The purpose of this design of the grinding surface is to raise the grinding bodies in the grinding space of the mill so that they fall as high as possible on the material to be milled and thus are shredded with high energy, that is, the cataract effect.

Őrlőtestmozgatási this method has the consequence that the grinding bodies potential energy of the fall is only a fraction can be used for chopping, while increasing the őrlőlapok and őrlőtes- ⁵ tek wear and promote agglomeration of the milled material.

Also known from U.S. Pat. Based German patent specification an inner armor ball mills, which are őrlölapjai kialakít- va ³⁰ to form a frusto-őrlőfelületek palástfelületeket more one behind the other, facing the őrlőtérbemenet grounded. The characteristic formation of this armor leads to the self-grading of the grinding bodies such that their size ^{decreases from the} input of ^{3u to} the outlet of the grinding chamber, so that along the grinding path the grinding body size corresponding to the change in fineness of the ground material is always present.

However, the desired grinding body grading is only available in ⁴⁰ long grinding chambers, subject to certain framework conditions. This armor most significant disadvantage of the milled material is relatively short residence time in the chamber is too small and at the same take-up duration, va- lamina ⁴⁵ with low level of milled material. Coarser particles can thus leave the grinding chamber without crushing.

A further disadvantage of the solution is that, in particular, for fine grinding areas ⁵⁰ to achieve high grinding fineness, a relatively wide range of grinding body sizes must be used. Such grinding body charges are expensive because the cost increases significantly with the reduction in diameter of the extremely abrasion resistant grinding balls used today. 55

It is also disadvantageous that such armor cannot prevent the agglomeration of the ground material, which also leads to a reduction in milling efficiency or requires additional expenditure.

Several solutions are known from various literature sites, patents 60 (e.g., U.S. Patent No. 323,529) and publication documents (e.g., U.S. Patent No. 20,383,223), which allow the use of screening armor and other internal armor. the disadvantages (unfavorable result of crushing, intensive wear) of the presence of ground material in a relatively short space of 65 mills can in principle be eliminated. All solutions recommend placing brackets in or at the outlet of the mill to increase the degree of filling of the milled material. The extended exposure time should improve the grinding result. A disadvantage of these solutions, however, is that the congestion of the ground material in the grinding space also facilitates the re-mixing of the ground material which adversely affects the grinding result.

No. 28 30 92 From the Austrian patent, an armor for ball mills is known with grinding plates having grinding surfaces with grooves of the same depth running along the entire circumference of the grinding drum. The circumference of the groove, which is perpendicular to the circumference, is circular in shape, the radius of the arc of the groove being equal to the radius of the balls used in the mill or of the largest size used. Due to the alignment of the radii of the grooves and the grinding balls, this solution should provide the same degree of retention of the grinding bodies as the mandrel or milling mill due to the better frictional relationship between the balls and the groove and the greater abutment of

No. 309,963. Further, an Austrian patent discloses a ball mill armor with grinding plates having grinding surfaces also having grooves of circular cross-section running along the entire circumference of the grinding drum, but at least a portion of the grooves being inclined at an angle of 3 to 10 °.

In addition to the drawbacks mentioned above, the disadvantage of the known grooved armor is that due to the approximation of the diameter of the largest bullet to the radius of the groove segment, the particles of ground material have only a minimal chance of entering the most stressed area between the mill Extraction conditions are extremely unfavorable. At all smaller bullet sizes, only point-to-point contact between the ball and the mill wall, particularly in the groove region, can be achieved, which means that no significantly altered stress conditions are expected compared to conventional internal armor except for a reduced cataract effect.

No. 309,963. The arrangement described in Austrian Patent No. 4,198,012 is directed to the return of the grinding balls in the opposite direction of the movement of the ground material. However, this directly provokes the phenomenon of backtracking. This results in a very wide range of particle size distribution for the milled material within the range, which is further refined to a much higher specific workload than the narrow particle size range, to summarize that the major disadvantage of this known armor is the strong due to the force of cataract-21

187,610 yen, which, however, cannot be used well enough for shredding, but at the same time leads to intense wear. In addition, the ground material passes too quickly through the grinding area of the ball mill, which results in inadequate lead time and low filling level. Although the latter defect can be eliminated by means of a barrier element, the inevitable increase in back mixing which adversely affects the grinding result cannot be eliminated. In addition, the above design of the grinding track and the selected grinding body fillings do not sufficiently influence the passage of the coarser particles and the agglomeration, thereby further deteriorating the grinding result. Contrary to the object of the invention, the known grooved armor reduces the proportion of cataract effect, which adversely affects the crushing result, since the reduced racket stress is not replaced by other stresses. In addition, the last-mentioned type of armor does not eliminate the disadvantages of transportation (high transport speed, low level of ground material).

It should be added that grinding sheets and grinding beams produce cataract effects with a specific geometry, the proportion of which is determined by U.S. Patent No. 154,425. The solution in the GDR patent reduces it to a minimum. However, in this embodiment, directed control of the cataract effect in the displaced grinding body charge is not possible as a function of the grinding resistance or ad _{80 at a} given speed, even if the originally built armor is replaced by armor of altered geometry or higher lifting capacity. The special particle distributions of the material to be milled, such as high d ₈₀ values and, where appropriate, high grinding resistances, require special measures for known mill armor crushing and for optimum armor formation, especially for coarse mill armor.

It is an object of the present invention to achieve high shredding efficiency for ball mills, especially in their coarse grinding areas, at low shredding energy and low energy consumption of d ₈₀ , whereby the use of grinding balls and grinding plates is limited to the level required by the ground material.

SUMMARY OF THE INVENTION The object of the present invention is to provide ball mills, especially coarse mills thereof, in accordance with U.S. Patent No. 154,425. Armor according to Patent PDR further developed in such a way that taking place in the őrlőtesttöltetben relative movement stepwise influencing enable or to improve indentation conditions of the material to be ground between the balls and profiled in the grooves őrlőpálya, such as rapid d material to be ground ₈₀ values as well.

The ^{object of} the present invention has been solved by providing, in a row, a _n = aq ^n_1 , where q - 2, is a grooved stepped grinding wheel whose geometric axes are preferably parallel to each other and alternately circumferentially grooved grinding boards. The profiling of the furrows is described in ref. According to the GDR patent, it is used to maintain the proper use of the ground material, which is provided both by the force of form and by the controlled movement of the grinding balls.

The value of "a" may be 2 and / or 3, depending on the diameter of the mill. Each grooved step mill is followed by a constant "j" of normal grooved mill.

The amount of grinding sheets required for a ring is given by the relation _n + i _n , where _{n is} the number of grooved step mills, i _{n is} the number of normal grooved grinding sheets.

The numbers above are usually chosen such that i _n = ". The number of rows "a _n " is determined iteratively. The number of grinding sheets required for an interval is calculated from the relation 1 + j, where j 'is the quotient of _n .

With the presently known method of effecting blending, the present invention, without modifying the blades and replacing the entire armor, according to the requirements of the present invention, allows the use of only two blade types to influence the shredding result and throughput at a given speed. Each replaced grinding sheet can be used later in the mill as a wear part.

Figures 1 and 2 show two possible exemplary embodiments for a mill diameter of 3.2 meters with rows 4 and 8, respectively.

Here the following relationships apply:

a „= a · q ^r_l ;

a = q = 2; ^a "+ i" = 32.

If j = 2 it follows that i, = 30 and j = 15, a ₂ = 4, it follows that i ₂ = 28 and j = 7, ₃ to 8, it follows that i ₃ = 24 and j = 3, ₄ = 16, so i ₄ = 16 and j = 1.

As can be seen from the drawing, the smallest height of the grooved step mill corresponds to the height of the standard grooved grinding board, while its maximum height is 1.9 to 2.2 s.

The _n rows of grooved step mills are preferably arranged helically in the cylindrical space of the ball mill. Optionally, the entire armor may be made of such step mills.

The armor of the present invention is used with poly and monodisperse grinding body charges.

Claims (5)

1. Inner armor for coarse and fine grinding fields, having grinding surfaces with radially extending grooves such that the grooves are spaced from the circular planes3; -3,187 610 RO cross-section is formed between the grinding ball and the barázdafenék an approximately sickle őrlőrést stet shape, wherein abutting the őrlölapon each grinding balls affects more than one point or a short section of the groove cross section, characterized in that the "= q ¹ based on the relation q = 2 and = 2 and / or 3, the line "" is a grooved stepped grinding plate alternating with a normal grooved grinding plate, preferably parallel to each other, arranged along the grinding path. Internal armor according to claim 1, characterized in that the minimum height (S) of the notched step mill is equal to the height (S) of the normal notched grinding plate and its maximum height is 1.9 ... 2.2 S. Internal armor according to Claim 1, characterized in that the rows "a _n " are helically arranged in the cylindrical space of the ball mill. Inner armor according to claim 1, characterized in that, in the extreme case, the entire armor is formed of grooved step mills. The inner armor of claim 1, characterized in that it is filled with poly- and monodisperse grinding body charges. 2 pieces of figure