GB2101493A

GB2101493A - Mixer for producing colloidal cement mortar or concrete

Info

Publication number: GB2101493A
Application number: GB08212920A
Authority: GB
Inventors: Gunter Peters
Original assignee: Colcrete Bau Co KG GmbH
Current assignee: Colcrete Bau Co KG GmbH
Priority date: 1981-05-05
Filing date: 1982-05-05
Publication date: 1983-01-19
Also published as: DE3117648A1; DE3117648C2; GB2101493B

Abstract

Forcible swirling in the container 1 is attained by tangential supply of the mixture sucked out of the container by a pump 7. In order to avoid precipitation, the container 1 is frustoconical and a cone 3 rising from the bottom of the container is disposed in the centre of the container. <IMAGE>

Description

SPECIFICATION Mixer for producing colloidal cement mortar or concrete The invention relates to a mixer for producing colloidal cement mortar or concrete, comprising a container for receiving the mixture components and a mixing pump which sucks out of the lowest point of the container and conveys back into the receiving container.

Mixers of this type are known and are used in the production of the so-called "Colcrete mortar".

The mixing process consists of two stages. First of all water and binder, for example cement, are mixed together. The cement is thoroughly wetted, since the surface area of the cement coming into contact with the water is increased inside the mixing pump. The particles of cement are thus very finely distributed in the water, as a result of which flocculation of the cement and the occurrence of precipitation caused thereby are substantially avoided. By subsequently adding sand to this water-cement mixture, a thoroughly mixed homogeneous mortar of good flowability and particular disintegration is formed after further thorough mixing in the mixing pump.

Forcible swirling of the mixing components in the receiving container is essential for the troublefree operation of the known mixers. If the swirling stops in the container, mixing no longer takes place in such areas of no flow. Relatively thin mortars are produced with the known mixers, in which it is ensured that the swirling is not interrupted. If mixtures of thicker consistency are produced, the forcible swirling inside the receiving container may easily come to a stop, in particular where the forcible swirling is weaker. As a result the mixing of the components is adversely affected. What is desired is an improvement of the mixer in such a way that it operates reliably even in the production of thicker mixtures.

The present invention provides a mixture that the receiving container is shaped like a truncated cone, and a pointed cone rising from the bottom of the receiving container is disposed in the centre of the receiving container.

We have observed that, in the case of known mixers, forcible swirling provided by tangential supply of the mixture sucked out of the container results in an area of no flow being formed in the centre of the container on account of the circular swirling. According to the invention, the cone, which rises from the bottom of the receiving container and which fills this area, is used to avoid precipitation in this area. The forcible swirling of the mixture in the container is thus carried out in areas which are immediately adjacent to the walls of the container and in which the flow velocity of the mixture in the container is at a maximum on account of the tangential supply.

The frustoconical form of the container, which therefore widens downwards, has the advantage that the local volume of the container at each point along the height of the cone remains virtually constant, as the downwardly spreading cone faces the wall of the container which likewise spreads downwards. In this way the through-flow of the container from the inlet connected to the delivery side of the mixing pump to the suction opening on the suction side of the mixing pump cannot come to a stop and reliable mixing inside the container is ensured even in the production of thick mixtures.

Preferably, the angle of inclination of the cone and that of the wall of the receiving container are approximately equal, i.e. the wall of the frustoconical container extends approximately parallel to the surface of the cone disposed in the receiving container.

When treating thick mixtures the operation of the mixer can be further improved by the receiving container being provided with a stirring apparatus.

The stirring apparatus may, for example, be in the form of revolving paddles mounted on stirrers projecting into the container through an upper opening. The stirring paddles are advantageous, particularly in the case of treating extremely thick mixtures, compensating for the retardation of the flow through the container caused, in the case of such thick mixtures, by internal friction.

In one advantageous embodiment a drivable rotating ring, to which stirrers projecting into the container are secured, is mounted on the edge of the upper opening. This has the advantage that structural measures for leading drive shafts for the paddles through the walls of the receiving container may be dispensed with and problems of sealing and storage associated therewith do not arise.

The invention will be described further, by way of example, with reference to the accompanying drawing, whose sole Figure shows a diagrammatic side view of a mixer, partly in section.

The mixer illustrated comprises an open-topped receiving container 1 in the form of a truncated cone. A cone 3, which extends more or less near to the edge of the upper opening 4 of the frustoconical container 1, is disposed centrally on the bottom 2 of the container. The bottom 2 of the container is provided at its periphery with a suction opening 5 to which the suction connection 6 of a mixing pump 7 is connected.

The mixing pump 7 sucks the mixture from the container and feeds it back into the container by way of a line 9 joined to its delivery connection 8.

The line 9 opens tangentially into the container through a supply opening 10. A feed line 11 with a shut-off valve 12 branches off the line 9, so that when the mixture is ready the mixing pump 7 can pump the prepared mixture to the place of use when the valve 12 is open.

A rotating ring 13 with external teeth arranged on the outside is rotatably mounted on the upper edge of the opening 4 of the container. A pinion 14 on the shaft of an electric motor 1 5 engages in the teeth. The rotating ring carries stirrers 1 6 projecting into the interior of the receiving container 1 and provided with paddies 17 on the outside.

Claims

1. A mixer for producing colloidal cement mortar or concrete, comprising a container for the mixture components and a mixing pump which sucks the mixture out of the lowest level of the container and conveys it back into the container, the container being in the form of a truncated cone and containing a cone which rises from the bottom of the container and is disposed in the centre of the container.

2. A mixer as claimed in claim 1, in which the container is provided with stirring means.

3. A mixer as claimed in claim 2, in which the stirring means comprises revolving paddles carried by stirrers projecting into the container through an upper opening.

4. A mixer as claimed in claim 3, in which the stirrers are connected to a drivable rotating ring mounted on the edge of the upper opening.

5. A mixer substantially as described with reference to, and as shown in, the accompanying drawings.