RU2166358C2 - Device for grinding and suspending powders - Google Patents

Abstract

FIELD: pharmaceutical, chemical and food-processing industries; devices and units used for preparation of suspensions and ointments. SUBSTANCE: proposed device includes drive and working member for grinding and dispersing crystalline powders; working member includes system of engaged spiral gears: one drive gear and two or more driven gears. Drive gear is thrown into engagement with three driven gears of similar diameter. Rather hard crystal are grounded between teeth due to considerable force of engagement. Degree of grinding is not practically impaired by wear or change in static backlash due to constant teeth pressure. Grinding may be performed in liquid and elastoplastic media. EFFECT: simplified construction. 3 cl, 3 dwg

Description

 The invention relates to the pharmaceutical, chemical, food industry and relates to devices and mechanisms used for grinding medicinal powders and to obtain suspensions and suspension ointments.

 In the arsenal of medicines, suspension systems are widely used: suspension ointments, pastes, oral suspensions. The bioavailability and effectiveness of the finished suspension drug usually increases with increasing free active surface, surface energy of the solid phase.

 A number of devices for grinding and dispersing medicinal powders are known: ball mill (CMM); drum maser (VM); colloid mill (KM) [1]. These devices are widely known and used in industry. They have certain disadvantages - low productivity (CM), inconvenience of service and loss (CMM); insufficiently fine degree of grinding (VM).

 A homogenizer (a.s. N 1465101) [2], used to obtain finely divided homogeneous suspensions, emulsions and solutions in liquid-liquid, liquid-gas and liquid-solid systems in the pharmaceutical, chemical, food and other industries. The device includes a rotor with discharge channels and a stator in the form of a disk with holes, a working annular chamber with a multifaceted surface, located in the cavity of the rotor. There are no abrasive elements in the device; homogenization is achieved by vortex processing of the material, therefore, the efficiency of grinding of solids is insufficient.

 Dispersant (a.s. N 1710111) [3], intended for use in the chemical, pharmaceutical, food industries of the national economy with the aim of carrying out the processes of grinding, mixing, dissolving, emulsifying, suspending and homogenizing in liquid-liquid, liquid-solid systems . The device includes a housing with inlet and outlet nozzles, in which a rotor is arranged concentrically with through channels and inserts mounted with the possibility of radial movement, and a stator in the form of a ring with slots. The disadvantages include: the lack of grinding effect and, as a result, the insufficient degree of grinding of solid crystalline powders; relative complexity and high requirements for the accuracy of the manufacture of the structure, high wear of the working bodies, especially for liquid-solid systems, accompanied by an increase in the gap between the working bodies (slotted coaxial cylinders) and a decrease in grinding efficiency; the impossibility of using viscoelastic systems (petroleum jelly, lanolin, etc.) as a dispersion medium.

 A device for dispersing and homogenizing dispersed systems (a.s. N 1095977) [4], used in the pharmaceutical industry to obtain dispersed liquid-solid systems. It is a set of roller bearings placed in coaxial pipes, while the inner tube rotates and the outer one is stationary.

 The disadvantages of this apparatus include: the need to use an additional device for pumping the processed medium through the apparatus; the complexity of manufacturing and energy consumption of the device.

 As a prototype, the closest analogue was chosen - a submersible rotary roller dispersing apparatus, which relates to equipment for fine grinding, activation and homogenization of viscous materials in chemical, pharmaceutical, cosmetic and other industries (a.s. N 1586762) [5]. It contains a housing with inlet and outlet openings, a leading rotor with radial grooves and a stator installed therein with a gap relative to each other; working bodies are rolling elements (rollers) placed in the radial grooves of the rotor.

The disadvantages of the prototype include:
- the complexity of the device and high requirements for precision manufacturing;
- a large total surface of the working bodies, the rotor and the stator, which is accompanied by significant losses of dispersible material;
- in the case of processing systems with high viscosity or structured mass is not absorbed into the stator cavity, circulation and grinding cease. Therefore, the grinding and dispersion modes are limited by relatively low concentrations of powder in a liquid medium;
- rolling elements (rollers) are freely placed in the radial grooves of the driven rotor, therefore, the rubbing force between the rollers and the stator surface is relatively small and insufficient for grinding solid crystalline powders.

 The objective of the invention is to develop a device for grinding and dispersing medicinal crystalline powders, which would provide a high degree of dispersion and uniformity of suspensions for powders with different sizes and strength of crystals, ease of manufacture and design, minimal technological losses of the processed material.

 The task is implemented by the proposed device, including the drive and the working body.

 The working body is a system of conjugate helical gears, one of which is the lead, and two or more - driven. Moreover, in engagement with the drive gear are three driven gears of the same diameter.

 The invention is illustrated by drawings.

In FIG. 1 - device for grinding and suspension of powders;
In FIG. 2 - arrangement of gear axles;
In FIG. 3 is a diagram of a dispersion process in a device for grinding and suspending powders.

A device for grinding and suspending powders is a system of mating helical gears, one of which is the leading 1 and two or more driven 8 (Fig. 1). Helical gears provide the vertical and horizontal components of the movement of the medium flow and, as a result, the absence of stagnant zones. The drive gear 1 is mounted by a shaft in the sleeve 4 (Fig. 1), which is pressed into the upper disk 7 on one side and is limited by the boss of the lower disk 9 in order to avoid axial displacement. The upper 7 and lower 9 disks are attached to each other by three uprights 3 located at an angle 120 ^o relative to each other at the edges of the disks. Thrust bushings 10 provide the required distance between the upper 7 and lower 9 discs. The axis of the driven gears 5 are fixed using prisms 6 and 6 ', allowing you to adjust the engagement and to ensure the coupling of the leading 1 and driven 8 gears. Driven gears are located at an angle of 120 ^o relative to each other (Fig. 2).

 The operation of the device for grinding and suspending powders is as follows.

A liquid or elastoplastic medium (oil, petroleum jelly, lanolin, polyethylene oxides, etc.) is introduced into the reactor vessel 2 and the working member of the homogenizer — conjugate gears — is immersed. The drive is turned on and the initial crystalline powder is introduced with rotating gears. Dispersion is thus performed in a liquid medium. Powder particles are between the surfaces of the teeth of the gears and are crushed by the abrasive forces F and F ₁ (Fig. 3) that occur at the moment the teeth enter the mesh. The milled particles under the influence of the teeth coming into engagement are squeezed out together with the liquid phase in the axial and tangential directions, which ensures intensive mixing of the mass.

 Examples.

 1. Ointment streptocid 10%.

540 g petroleum jelly was loaded into a jacketed apparatus into which hot water was supplied. Then, a device for grinding and suspending powders was immersed in the medium. When the drive was turned on, streptocide was added in an amount of 60 g. Dispersion was carried out for 70 min at a gear speed of 1500 rpm and a medium temperature of 60 ^o C. Samples were taken 5, 10, 15, 20, 60, 70 minutes after the start process. Samples were analyzed by microscopic analysis. The data of microscopic analysis are shown in the table.

 2. Suspension griseofulvin 5% in polyethylene oxide 400.

Polyethylene oxide 400 in an amount of 540 g was loaded into a jacketed apparatus into which hot water was supplied. Then, a device for grinding and suspending powders was immersed in the medium. With the drive turned on, griseofulvin was added in an amount of 60 g. Dispersion was carried out for 70 min at a gear speed of 1500 rpm and a temperature of the medium being treated at 25 ^o C. Samples were taken 5, 10, 15, 20, 60, 70 minutes after the start process. Samples were analyzed by microscopic analysis. The data of microscopic analysis are shown in the table. Then, polyethylene oxide 400 was added in an amount of 600 g and dispersion was continued for 10 min in order to bring the solid content of the suspension to the desired value.

 3. Suspension of sulfadimesin 2.5% in liquid paraffin.

540 g liquid paraffin was loaded into a jacketed apparatus, into which hot water was supplied. Then, a device for grinding and suspending powders was immersed in the medium. With the drive turned on, sulphadimesin was added in an amount of 60 g. Dispersion was carried out for 70 min at a gear speed of 1500 rpm and a temperature of the medium being treated at 40 ^o C. Samples were taken 5, 10, 15, 20, 60, 70 minutes after the start process. Samples were analyzed by microscopic analysis. The data of microscopic analysis are shown in the table. Then the drive was turned off and vaseline oil was added in an amount of 1800 g. Then, the drive was turned on and the suspension was homogenized for 10 minutes at a gear speed of 2500 rpm in order to bring the suspension's solid phase content to the required value.

 As can be seen from the table, the dispersion of substances in suspensions, regardless of the type of medium, initial size, nature and strength of the crystal, decreases rapidly and after about the same time period (about 20 minutes) reaches a size of 20-25 microns (the largest fraction).

An experimental model of a device for grinding and suspending powders of size 133 X 133 X 270 was made. Diameter of the working zone d = 90 mm. The height of the working area h = 54 mm. Number of gears - 4 pcs. Gear Parameters:
Gear height - 30 mm
The diameter of the initial circle - 26.75 mm
Module - 3
The number of teeth is 9.

 The presence in the device of 3 or more conjugate gears provides a greater number of working grinding zones; the inclination of the teeth at an angle from a vertical position gives the vertical component to the movement of the suspension and provides mixing of the mass.

The proposed device has the following advantages:
- grinding between the teeth due to the great effort in the engagement of the gears allows you to grind quite hard crystals of most substances used in pharmaceutical practice;
- the design is simple to manufacture and operate, it is possible to use both standard and specially manufactured gears and drives;
- during operation, relatively low wear of the surfaces occurs, similar to the wear of gears in gear pumps, which are among the most durable structures;
- the degree of grinding is practically not affected by the degree of wear or change in the static gap between the teeth, since when the gears rotate, the surfaces of the teeth are pressed against each other with constant force;
- grinding can be carried out both in a liquid and in an elastoplastic highly viscous medium, and the possibility of carrying out the process is limited only by a very high structuring of the medium, in which it becomes impossible to get the processed system into the active zones of the gear homogenizer;
- losses of the processed material are relatively small due to the small total surface of the working body.

List of references:
1. Kasatkin A.G. Basic processes and apparatuses of chemical technology. - M. Chemistry, 1971, 784 p.

 2. Sergeev G.A., Grushina T.A., Garipova 3.S. Homogenizer, IPC B 01 F 7/28, 03/15/89, BI. N 10, a.s. N 1465101 USSR.

 3. Kovrizhikov G.A., Scheblenov P.A., Dokuchaev A.N., Sergeev G.A. Dispersant, IPC B 01 F 7/00, 02/07/92, BI. N 5, a.s. N 1710111 of the USSR.

 4. Plyushkin S. A., Klimov V. A., Podshivalina G. N. A device for dispersing and homogenizing dispersed systems, IPC B 01 F 7/16, 06/07/84, BI. N 21, a.s. N 1095977 USSR.

 5. Kurochkin A.K., Sergeev G.A. Rotary roller dispersing apparatus, IPC B 01 F 7/28, 08/23/90, B.I. N 31, a.s. N 1586762 USSR.

Claims (3)

 1. A device for dispersing, homogenizing and mixing dispersed systems for medicinal, cosmetic or food purposes, including a drive and a working body that can be freely immersed in a liquid or elastoplastic medium to be treated, characterized in that the working body is made in the form of a system of conjugate gears, one of which is leading, and two or more are slaves.  2. The device according to claim 1, characterized in that helical gears are used as mating gears.  3. The device according to claim 1, characterized in that in engagement with the drive gear are three driven gears of the same diameter.

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