RU2368422C2 - Two-sieve sizing trommel of drum mill - Google Patents

Abstract

FIELD: machine building, food industry.

SUBSTANCE: two-sieve sizing trommel of drum mill comprises two coupled concentric rotary drums with the orifices. Note here that those of inner drum are larger than outer drum orifices. Note also that the mill outlet communicates with the inner drum. Drum inner surfaces have blades arranged along helical line. Distance between of inner drum blades makes 0.8 to 1.5 of the inner drum orifice rating. Distance between outer drum blades makes 3 to 5 of the outer drum orifice ratings. For both drums, blade length-to-blades interspacing ratio makes 3 to 7.

EFFECT: higher quality of sizing.

3 dwg

Description

The present invention relates to techniques for the separation and unloading of wet self-grinding materials of ore-grinding mills.

In the current state of the art, an analogue is known - a buter for ore grinding mills according to a.s. USSR No. 582830, В02С 17/18, dated June 16, 75. This buter has a rotating drum with holes in which the outlet of the mill is brought. These features of the analogue coincide with the essential features of the invention. In addition, an analogue has an auger installed on the inner surface of the rotating drum, and the analogue also has a device for returning the middle class of material to the mill. The disadvantage of the analogue is the small number of classes at the exit of butary. Also, the disadvantage of this butary is that the screw prevents the mixing of material in the drum due to the pressure of the pulp from the mill. This reduces the quality of the classification.

The prototype of the invention is a double-screen buta drum mill according to SU 1782657 A1, 12/23/1992, B02C 17/18. This butare contains two rotating concentric drums that are fastened and have holes, the holes of the inner drum being larger than the holes of the outer drum, and the outlet of the mill brought into the inner drum. These features of the prototype are common with the essential features of the invention.

This butare provides pulp mixing with pressure from the mill, but does not provide efficient screw transportation of pulp along the butary. This reduces the quality of the classification and is a disadvantage.

The basis of the invention is the task to improve the quality of the classification of the material by improving the transportation of pulp along the butary with screw oscillations while maintaining the mixing of the pulp with the pressure of the mill.

The problem is solved in that in a two-mesh butyram of the drum mill, which contains two rotating concentric drums that are fastened and have holes, the holes of the inner drum are larger than the holes of the outer drum, and the outlet of the mill is brought into the inner drum, according to the invention, along the length of the helical lines are installed blades, while the distance between the blades of the inner drum is 0.8-1.5 of the nominal size of the holes of the inner drum, the distance between the blades of the outer 3-4 drum nominal size of apertures of the outer drum, and both reels ratio of the lengths of the blades along helical lines and the distance between them is 3-7.

This, while maintaining the mixing of the pulp with the pressure from the mill, improved the transportation of pulp along the butary with oscillations along the helical path. The latter increased the overall mixing of the pulp, which increased the quality of the classification.

Figure 1 shows a General view of the butara in longitudinal section; figure 2 shows a section along aa of figure 1; on Fig 3 shows a portion of the cross section of the drums on an enlarged scale.

The two-mesh butar of the drum mill contains two concentric rotary drums - the inner drum 1 and the outer drum 2. The drums are fastened with the help of the metal structure 3. The inner drum has holes 4 that are larger than the holes 5 of the outer drum 2. The output 6 of the mill 7 is brought into the inner drum 1. On blades 8 are made on the inner surface of the inner drum 1, blades 9 are made on the inner surface of the outer drum 2. The blades 8 and 9 are located between the holes 4 and 5 along the helical lines 10 and 11 and the distances between them along the length. The blades 8 and 9 are made on elastic cards 12 and 13, docked one to one. Distance

l ₁ between the blades 8 of the inner drum 1 is 0.8-1.5 nominal size b ₁ holes 4 of the inner drum 1. The distance l ₂ between the blades 9 of the outer drum 2 is 3-5 nominal size b ₁ holes 5 of the outer drum 2. For the inner drum 1, the ratio of the length L _{1 of the} blades 8 along the helix 10 to the distance l ₁ between them is 3-7. For the outer drum 2, the ratio of the length L _{2 of the} blades 9 along the helix 11 to the distance l ₂ between them is also 3-7.

So, as an example, in the technological chain of wet self-grinding of iron ores at the mill MMC 70 × 23 a double-mesh buter is installed with the following parameters: - the inner drum has a screening surface with holes 20 × 20 mm in size with blades installed at a distance of 18 mm from each other with a blade length of 60 mm; - the outer drum has a screening surface with holes of size 2.8 × 2.8 mm with blades mounted at a distance of 9 mm from each other, with a blade length of 35 mm.

In the process, the butar drive (not shown in the drawings) rotates the metal structure 3. The latter rotates the inner drum 1 with cards 12 and the outer drum 2 with cards 13. Mill 7 from its outlet 6 feeds the pulp into the inner drum 1. In it, the pulp is partially captured by the blades 8, which, due to their installation along the helical line 10, transport the pulp along the inner drum 1. Partially, the pulp moves due to the pulp pressure from the mill 7 between the blades 8. The fact that the pulp movement is set from two sources provides more and intensity of her agitation. A larger class of pulp material, which is classified, is shipped from the end of the inner drum 1. A smaller class of material, which is medium for butara, passes through the holes 4 of the inner drum 1 with pulp onto the inner surface of the outer drum 2. Here, the pulp is partially captured by the vanes 9 which, due to their installation along the helix 11, transport the pulp along the outer drum 2. Partially, the pulp moves between the blades 9 due to the pressure that is formed when the pulp falls through the hole Only the inner pulp 4 is mixed. This also leads to more intensive mixing of the pulp in the outer drum 2. The middle class of material from the pulp is transported to the end of the outer drum 2 butar, where it is unloaded, and the small class passes through the openings 5 of the outer drum 2 into the undergrating. Separated classes of material from butar go to further processing.

If on the drums 1 and 2 the blades 8 are located at distances l ₁ less than 0.8 of the nominal size b _{1 of the} holes 4, and the blades 9 are located at distances l ₂ that are less than 3.0 of the nominal size b _{1 of the} holes 5, mixing can be reduced pulp due to the longitudinal pressure of the pulp. If on the drums 1 and 2 the blades 8 are located at distances l ₁ that are greater than 1.5 of the nominal size b _{1 of the} holes 4, and the blades 9 are located at distances l ₂ that are greater than 5.0 of the nominal size b _{2 of the} holes 5, reduction is possible the movement of the pulp due to the blades 8 and 9. If for the drums 1 and 2 the ratio of the length L _{1 of the} blades 8 of the inner drum 1 to the distance l ₁ and the ratio of the length L _{2 of the} blades 9 of the outer drum 2 to the distance l ₂ between them is less than 3.0 - it is possible reduction of pulp mixing due to its transportation by blades 8 and 9. If for b rabanit 1 and 2, the ratio of length L ₁ of the blades 8 of the interior of the drum 1 and the distance l ₁ between them and the ratio of the length L ₂ of the blades 9 of the outer drum 2 to the distance l ₂ between them is greater than 7.0 - mixing may decrease the pulp from the pulp flow pressure.

The intensification of pulp mixing during the operation of butar leads to an increase in the quality of classification of the material.

Claims (1)

A two-mesh buter of a drum mill containing two rotating concentric drums that are fastened and have holes, the holes of the inner drum being larger than the holes of the outer drum, and the outlet of the mill brought into the inner drum, characterized in that the blades are installed along the helical lines, while the distance between the blades of the inner drum is 0.8-1.5 of the nominal size of the holes of the inner drum, the distance between the blades of the outer drum is 3-5 nominal size the holes of the outer drum, and for both drums, the ratio of the length of the blades along helical lines to the distance between them is 3-7.

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