DE1028859B - Process for the fine comminution of solid materials, especially pigments - Google Patents

Description

GERMAN

With many industrial. Procedure and with many commercially available products are materials in Fine powder form required. There are already many Processes and mills have become known which are used to convert a substance into finely divided form. All known methods and mills generally have a low throughput and discharge speed on. Efforts have already been made to reduce the throughput and discharge speed of the known Increase mills; But these attempts always resulted in a disproportionate increase in the Required power consumption result, so that an effective increase in the output of the known Mills have so far been associated with disproportionately high expenses, wair.

The mills used for comminution come in different designs *; shapes as such known. So-called jet mills have often been used, these are mills in which the material to be comminuted Material is subjected to endless circulation, the crushing by mutual Wear of the particles is caused. For this purpose, steam, air or something else is used suitable gas from a closed loop of the mill under pressure from any source forwarded here. The material to be crushed is in any case fed to the ring line of the mill and here from. entrained in the propellant gas flow. Usually a nozzle or the like is provided at dier entry point into the ring line, which exerts a suction effect, so that the material to be crushed is drawn into the propellant gas flow.

The invention enables substances to be transferred into powder form at a high throughput speed and thereby a substantial increase in the performance of such known mills without at Increase in the throughput speed has an adverse effect on the grain size or a Increase in material losses · occurs. To achieve this substantial increase in the operation of the known mills is only a small increase the power requirement required; This is erfmduugsgeniäü achieved in that the discharge of the trailing gas stream loaded with the comminuted material from the mill is under the action of a suction generated behind the mill. Through this measure of the Application of a relatively small suction the entire facility is beneficially affected and there are unexpected improvements in the control of the working method and the work result achieved without increasing the Gas or steam consumption occurs.

The arrangement of the suction at the gas outlet of the cyclone separator is useful because the Process for the fine comminution of solid materials, especially pigments

Applicant:
Titangesellschaft mbH, Leverkusen 1

Claimed priority:
V, St. v. America June 22, 1961

Alfred William Meyer and Peter Coral Firing,

Matawan, NJ (V. St. A.),
have been named as inventors

The effect of a suction device on the jet mill and one on the cyclone separator is not the same is. The suction could also be arranged, for example, exclusively on the jet mill by in the Line between the jet mill and the cyclone separator a steam nozzle is arranged. Through this the way the mill works would probably be an improvement I regret it, but not that of the cyclone separator.

A particular advantage is achieved when according to the invention the suction strength is such that at the gas outlet point of the separator, below the pressure lying below the atmospheric pressure is generated.

The drawing shows, for example, an embodiment of the method according to the invention.

1 shows schematically a system for carrying out the method according to the invention;

Fig. 2 shows the side view of a jet mill for the system according to FIG. 1.

The method according to the invention can be used for comminution of substances, to be used in powder form, for example for crushing the Grauualien or the crystal · of metal salts or metal oxides in powder form for pigments for production of colors. For this purpose, the material to be shredded is taken from a silo or hopper

10 fed to a jet mill 11. The jet mill

11 steam, air or another suitable gas under pressure is supplied to line 13 while the material to be comminuted from the same line 13 from the separatory funnel 10 via the line 14 is supplied and entrained by the propellant gas stream. Appropriately, in line 13 is on the entry point of the line 14 od a nozzle crushing material into the propellant gas flow

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pulls. Only part of the propellant gas flow gets through the line 13 given, while the remaining propellant ■ gas flow directly through lines 15 into the annular chamber 12 is introduced. The lines 15 can protrude a short distance into the chamber 12. The ratio between that supplied through line 13 and through line 15 Propellant gas flow can fluctuate, but in general it is expedient to use the larger part of the propellant gas flow through line 15 to be introduced. A befrkdigen.de and economical way of working will reached when a third of the propellant gas flow through line 13, the remaining two thirds through the Line 15 are fed. The material to be shredded is during its circulation in the chamber 12 rubbed by mutual wear and leaves the chamber 12 in powder form through one at the Line 16 arranged inside the chamber. Mills in the embodiment described above are known per se.

From the mill 11, the comminuted material arrives with the propellant gas flow through the line 17 to a Cyclone separator 18, in which the powdery Material is deposited from the propellant gas stream. The powdery material falls in a per se known Way through a line 19 and is collected, while the propellant gas flow is discharged through the line 20 will. The propellant gas stream is expediently condensed in a chamber 21, the entrained matter not separated in the cyclone separator particles on the bottom of the chamber 21 are deposited.

In order to significantly increase the throughput speed of such devices, the discharge to improve significantly and achieve a consistent grain size and classification is at the outlet of the propellant gas stream of the cyclone separator 18 generates a suction or a vacuum. How yourself results from Fig. 1, this suction or this vacuum can be generated by a pump 22 which is connected to the Outlet of the chamber 21 is arranged and is driven by the electric motor 23. Of course Other devices such as fans, blowers, fans or the like can also be used. At the end of the line 19 is a drum-shaped, circumferential, airtight ZellenscMeuse in a manner known per se 24 which is actuated by a motor 25 is provided. This lock 24 leaves the separated comminuted Drain well through opening 26 into a suitable collecting container. The arrangement of the Lock 24 prevents air from entering the cyclone separator through line 19.

As a result of the reduction in pressure at the outlet of the jet mill by the suction, the pressure energy becomes of the propellant gas flow entering the mill through line 13 in a perfectly kinetic manner Energy converted so that a quick and effective comminution of the material is achieved.

The lowering of the pressure at the gas outlet of the cyclone separator 19 by the suction causes a more even and more effective separation of the grist particles from the propellant gas stream. aside from that is the throughput and discharge speed of the material from entry through line 14 to Exit through opening 16 is significantly increased. For example, the material discharge increased in one plant from approximately 29 t per day to approximately 37.8 t per day by the method according to the invention, d. H. by arranging a slight suction without reducing the pressure of the propellant gas flow at the inlet 13 the jet mill 11 was changed. This slight suction increases the pressure at the jet mill outlet for example from 100 mm to 12 mm of mercury Overpressure lowered and the pressure at the gas outlet of the cyclone separator 18 of 75 mm of mercury Overpressure reduced to 12 mm underpressure of mercury.

The use of the method according to the invention also leads to a substantial saving in steam or gas for the propellant gas flow. Without suction, the propellant gas stream is generally introduced ^{into line 13 at a pressure of 7 kg / cm 2} and into line 15 at a pressure of 6.3 to 6.7 kg / cm ^2; However, if the pressure at the outlet of the jet mill is reduced from 100 mm to 12 mm of mercury overpressure, the inlet pressure in line 15 can be reduced to 4.9 to 5.3 kg / cm ² with the same material flow. The resulting savings in propellant gas are significantly greater than the costs associated with generating the suction.

The suction can be adjusted in any way, for example by changing the speed of the motor 23 will. In this way, the throughput and discharge speed can be controlled, since a stronger one Suction required a higher speed. A change in suction also leads to a change the particle speed in the jet mill, which in turn increases the grinding speed and the The grinding time of the jet mill can be influenced. Increased suction leads to increased particle speed and to a smaller and more uniform grain size.

Claims (3)

Patent claims: 1. Process for the very fine size reduction of solid substances, especially pigments, in one Jet mill and separation of the solid substances in a cyclone separator connected downstream of the mill, characterized in that the discharge of the propellant gas stream loaded with the comminuted material from the mill (12) under the action a suction generated behind the mill takes place. 2. The method according to claim 1, characterized in that the generation of suction on dean Steam or gas outlet pipe of the cyclone separator (18) takes place. 3. The method according to claim 2, characterized in that that the suction strength is such that in the gas outlet pipe of the cyclone separator (18) a pressure below atmospheric pressure is generated. Documents considered: German Patent No. 627 006; Swiss Patent No. 119 282; French Patent No. 941 41.9; British Patent No. 533 015. 1 sheet of drawings © 809 507/217 4.