SU1502092A1 - Method and apparatus for dry desintegrating of material - Google Patents

Abstract

The invention relates to grinding methods implemented in drum mills, and can be used in the manufacture of mineral fertilizers. The aim of the invention is to reduce overgrinding by withdrawing a product of the specified size. For this, a hole 2 in the form of a truncated ring with a central angle of 100-120 °, offset from the horizontal by 13 ° -15 ° downward with an outer and an inner radius of 0.7 and 0.5, respectively, of the cross-section radius of the drum 3, at a speed of 0.7-1.1 m / s, air calculated for the full cross section of the mill, then water through holes 6 placed in a ring with a radius corresponding to hole 2 enters the rotating drum, for example, at a speed of 0.78-0 , 89 from the critical value, and, the passage in the cavity between the ascending and descending By firing eyes, the particles of a given size are removed from the grinding volume through the holes 10 made in the grid 9 outside the circle with a radius equal to 0.8 of the cross-section radius of the drum 3, then the crushed product is blown out through the holes 8 in the top of the grid 9 discharged in the lower part of the grid 9. As a result, the uniformity of the particle size distribution increases and the energy intensity of the grinding process is reduced. 2 hp ff, 3 ill. 1 tab.

Description

315

The invention relates to those technologies and techniques for the processing of solid dispersed materials and can be used in the construction, chemical and other industries.

The aim of the invention is to reduce overgrinding by outputting a product of a given size,

The essence of the method of dry grinding of materials consists in supplying air at a speed of 0.7-1.1 m / s in terms of the total cross section of the mill drum between the ascending and descending streams of the charmer loading, while the rotation speed of the mill can be 0.78 -0.89 from the critical value.

FIG. I shows a device for dry grinding of a material, longitudinal section; in fig. 2 is a view A in FIG. in fig. 3 is a section bB in figure 1,

The device contains a fixed spring I with a hole 2 in the form of a truncated ring with a central angle of 100-120 °, displaced from the horizontal by an angle of 13-15 ° downward, with hole 2 placed in the left or right half of cover 1 depending on the rotation, respectively clockwise or counterclockwise, and the outer and inner radii are respectively 0.7 and 0.5 of the cross-section radius of the drum 3 with grinding bodies consisting of a front cover 4 with a loading pin 5 and holes 6 placed along the perimeter of the ring with the outer and internal - with radii equal to the corresponding radii of the truncated ring of hole 2, shell 7 with discharge ports 8, grid 9 with holes 10, made outside the circle with a radius equal to 0.8 of the cross-section radius of the drum 3, rear cover 1I with a trunnion, drive 12 ,

The grinding bodies and the material to be ground during the rotation of the drum 3 form a geometrical figure consisting of three parts: the upward flow 13, the downward flow 14 and the inner cavity 15,

The device works as follows.

Grinding bodies are loaded into the drum mill, rotation starts with the aid of actuator 12 and through pin 5

submit the source material. Simultaneously with the feed of material through the opening 2 of the fixed cover I, air is fed through the holes 6 of the front cover 4, the flow rate of which is selected based on the speed of 0.7-1.1 m / s in terms of the full cross section of the mill. Air is fed into the cavity 15 between the upstream 13 nose and the downward 14 flows of the mixture of grinding media and the material to be ground. Next, the air passes through the falling stream 14, the holes 10 in the upper part of the discharge grid 9 and the discharge ports 8 of the shell 7, and the crushed material is discharged through the lower holes of the discharge grid 9 and shell 7. The smallest part of the crushed material is removed from the mill air .

When the mill's rotational speed is 0.75 PNR and the minimum speed of the supplied air, counting on a total cross-section of 0.7 m / s, from the descending stream 14 the portions 1C4 with a diameter of 0.078 mm or less are removed, and particles with a diameter of 0.035 mm and less are carried by air from the mill without subsequent contact with the balls. The ratio of their diameters is 0.45. With an increase in the velocity of the supplied air to a maximum of 1.1 m / s, particles with a diameter of 0.1 mm or less are removed from the falling layer, and particles with a diameter of 0.0456 mm or less are removed from the mill without subsequent contact with the balls. The ratio of their diameters is 0.416,

As the number of revolutions of the mill increases to 0.89, the cross-sectional area of the internal cavity between ascending 13 and descending 14 flows increases and the cross-section area decreases by downward flow 14, the largest diameter of particles carried by the flow from the falling layer at air velocities 0.7-1.1 m / s does not change (0.078 and 0.1 mm, respectively), and the largest diameter of particles carried from the mill increases and is 0.0745 and 0.0958 mm, respectively. The ratio of their diameters is 0.955 and 0.958, t, e, the crushed end product is close to monodisperse.

With a further increase in the number of revolutions of the mill, the effect decreases.

since the height of the falling is the creativity,

the ditch when 89 decreases. When the critical speed is reached, the balls rotate along with the drum mill, without falling, and the grinding of the material does not occur.

Example. The grinding of defluorinated phosphate is carried out in a drum mill with balls according to the following initial data: outer diameter 2.6 m; inner diameter 2.5 m; load factor 0.235; drum length 13 m; the degree of loading material - 1.15 volume of voids; The apparent density of the de-fluorinated phosphate is 3200 kg / m, the free area of the incident flow is 0.198 mVM. Air is supplied at a temperature of 2 ° C.

The calculation is carried out for the largest and smallest limits of the restrictive features of the proposed method.

Option 1: the number of revolutions of the mill, 5 rpm 0.764; the diameter of the crushed product 0,078 mm

2. variant: the number of revolutions of the mills, 5 rpm, 0.764 air flow rate, including a full cross-section 1, I m / s; diameter of the crushed product 0,100 mm.

3 option: the number of revolutions of the mill, 8 rpm. 0.887 air flow rate, calculated on a full cross section of 0.7 m / s; diameter of the crushed product 0,078 mm.

4th option: the number of revolutions of the mill, 8 rpm 0,887 p.; air flow rate, calculated on the full section, 1.1 m / s; diameter of the crushed product 0,100 mm.

The calculation results for the proposed method are presented in the table.

Options

Flow rate of air supplied, Deposition rate of particles, m / s Diameter of particles carried away from the incident flow, mm Deposition rate of particles carried away from the mill, m / s Diameter of particles carried away from the mill, Ratio of diameter of particles carried away from the mill to the diameter of particles carried away from the falling stream

Option

5.29

3.43

5.29

0.709

0.460

0.709

0.100.

0.078

Oh, 100

0.194

0.430

0.661

0.0456

0.0745

0.0958

0.446

0.993

0.958

It follows from the table that material re-extinction is significantly reduced, and consequently, the energy consumption for grinding is reduced, besides, the quality of the final material is improved and its output increases, since the polydispersity of the crushed material decreases, while the polydispersity of the final crushed material can be set within certain limits. mill speed or supply air flow.

invention formula

Claims (2)

I, a method of dry grinding of a material, including loading it into a rotating drum mill with simultaneous supply of air, grinding the material during joint movement with grinding bodies in the ascending and descending flows, and outputting the crushed product, characterized in that in order to reduce overmilling by output given by the size of the product, air is supplied between the ascending and descending flows at a speed of 0. 7–1.1 m / s over the entire cross section of mill 1, Budfi 0ue.Z Editor V. Petrash Phie. J Compose B. Mol Vka Tehred M. Didyk Proofreader M. Vasiliev Order A998 / 9 Circulation 543 VNIIPI State Committee for Inventions and Discoveries, State Science and Technology Committee of the USSR 113035, Moscow, Zh-35, Raushsk nab., A / 5 0 five five 0 30 2. (The method according to p. I, of tl and h aus, and 11 with the fact that the mill rotates at a speed of 0.78-0.89 from the critical OY. 3, A device for dry grinding of a material including a drum with grinding bodies, containing a front cover with a loading pin, a shell with discharge windows, a discharge grid, a back cover, an actuator, characterized in that, with a pulp, an increase in the yield of the target fraction due to a decrease in overgrinding of the material while saving. energy consumption, the device contains a fixed lid with an air inlet, placed in front of the front lid, which are located around the ring, the outer radius of the fixed and front lid openings is 0.7 of the drum radius, and the inner radius is 0.5 of the drum radius, and The fixed frame is located in the left or right part of it when the drum rotates clockwise or counterclockwise, respectively, with the angle of inclination of the BC and 13-15 openings to the horizontal and its central angle 100-120, and the opening uz9chnoy .raspolozheny grating area is a circle with a radius of 0.8 the radius of the drum, Bb Subscription