AN ARRANGEMENT IN A MIXING MACHINE

Abstract: The invention relates to an arrangement in a mixing machine for mixing particulate materials in order to add liquid, especially adhesive, substances to the particles during the mixing operation. Said arrangement er characterized by a rotatable throwing roller (12) which can be arranged in such a manner in contact with said particles (F) during the mixing operation that it throws a fog or curtain of particles (14) upwards.

Description: The present invention relates to an arrangement in a mixing machine for mixing particulate materials in order to add liquid, especially adhesive, substances to the material that is mixed. When liquid, especially adhesive, substances are added to par­ ticles during a mixing operation it is essential to avoid that the added medium impinges directly on the walls of the machine or on the mixing means, respectively. In order to avoid this, it is known, e.g. from mixing machines comprising two horizon­ tal vane aggregates rotating in opposite directions, to const­ ruct the vanes in such a manner and to rotate them with such peripheral velocity that the mixed material is thrown upwards to form a floating fog or curtain, to which the liquid addition agent is added, being ejected from a nozzle. As regards the intended mixture of particles, however, the high peripheral velocity necessary to achieve said floating curtain effect will be opposed to the requirements as regards intimate mixing which is achieved with lower peripheral velocities. In mixing machin­ es of this kind it is deemed advantageous that the peripheral velocity of the vanes be in a range causing a floating mixing zone above and between the vane aggregates rotating in opposite directions, i.e. an approximately weightless zone where the particles may move freely in relation to each other during the mixing operation. The peripheral velocity necessary to achieve said suitable mixing effect is necessarily lower than the peri­ pheral velocity required to achieve free throwing of particles to form a floating fog or curtain into which the addition agent can be injected. There is, thus, a demand for a mixing machine, wherein said desired floating mixing zone may be achieved at the same time as the liquid addition agent may be added in a suitable manner, i.e. by utilizing the above mentioned floating curtain technique. According to the invention an arrangement is, thus, proposed in a mixing machine for mixing particulate materials in order to add liquid, especially adhesive substances, to said particles during the mixing operation, said arrangement being characterized by a rotatable throwing roller that may be pro­ vided in contact with the particles in such a manner during the mixing operation that it throws a particle fog upwards. The invention is especially suited for a mixing machine comprising two horizontal vane aggregates rotating in opposite directions, and in such a mixing machine it is advantageous according to the present invention to arrange said rotatable throwing roller above said vane aggregates and between their axes of rotation. By the present invention the advantage is achieved that the mixing machine can operate under conditions resulting in the intended intimate mixture at the same time as the desired particle fog is achieved into which the addition agent may be injected. Examples of mixing machines where the vanes rotate so rapidly that a floating fog of particles is thrown upwards are known from the German Auslegeschriften Nos. 10 97 411, 11 12 968, and 11 16 196. An example of a mixing machine by the aid of which a desired very intimate mixture is achieved by provid­ ing a floating mixing zone is known from NO-PS No. 149 684. The invention is disclosed in more detail below with reference to the drawing, where Figure 1 is a diagrammatical cross section of a mixing machine comprising two parallel vane aggregates, and Figure 2 is a side elevation of the machine according to Figure 1. The mixing machine diagrammatically shown in the figures comprises a mixing chamber 1, that is mounted on a basis 2. In mixing chamber 1 two parallel vane aggregates 3, 4 are provided. Each vane aggregate in a known manner comprises a horizontal shaft 5 and 6, respectively, that is rotatably mounted on bearings (not shown) in the end walls of said mixing chamber. Each shaft 5, 6 carried a number of vanes 7. As shown in Figure 2, both shafts 5,6 project on one end of the mixing chamber 1 and are at that end connected to driving wheels 8, 9, respectively. Said drive wheels are driven by a chain 10 which is, in turn, driven by a motor 11. The vane aggregates 3 and 4 can, thus, by the aid of motor 11 be driven in opposite direct­ ions, as indicated by the arrows in Figure 1. Said vane aggregates rotate with a velocity resulting in a floating mixing zone F in the area above and between the rotat­ ing shafts 5, 6, as shown in Figure 1. In said mixing machine a throwing roller 12 is rotatably mounted in both end walls of said mixing chamber. It is rotatably mounted in said end walls in a manner not shown and is connect­ ed with a suitable drive motor 13. Said throwing roller 12 can be shaped in many different ways, but the roller diagrammatic­ ally shown is shaped like a shaft having four radially project­ ing impellers extending along the entire length of said shaft inside said mixing chamber 1. By the aid of motor 13 said throwing roller 12 can rotate as indicated by the arrow. Said throwing roller 12 is provided so as to achieve contact with the particles during mixing operations in zone F. Due to the rotation of throwing roller it will throw a particle fog 14 upwards. Into said particle fog the desired addition agent is injected through the indicated nozzles 15. Said throwing roller 12 can in a manner not shown be mounted in the end walls of the mixing chamber so as to be adjustable upwards and down as desired. This is not shown, since this is a structural detail easily accomplished by those skilled in the art. The suitable peripheral velocity of vanes 7 in a typical mixing machine of the shown kind will be in the range of 1,2-1,7 m/sec., whereas said throwing roller rotates with a rpm of approximately 1500 rpm/min., dependent on the roller diameter. The particle fog formed will be a fog or a curtain where the injected liquid particles will penetrate and be covered, so that adhesion on machine members is avoided. By the aid of the present invention, the above mentioned object is, thus, achieved, and the invention can be implement­ ed for mixing machines of various kinds.

Claims: 1. An arrangement in a mixing machine for mixing particu­ late materials in order to add liquid, especially adhesive, substances to the particles during the mixing operation, characterised ina rotatable throwing roller (12) that may be arranged in such a manner in contact with said particles (F) during the mixing operation that it throws a fog or curtain of particles (14) upwards. 2. An arrangement in a mixing machine as defined in claim 1, characterised inthat said rotatable throwing roller (12) is arranged above said vane aggregates (3,4) and between their axes of rotation.

Inventors: FORBERG, HALVOR
Applicants: FORBERG, HALVOR
Application year: 1986
Main classification: B01F7
IPC codes: B01F15, B01F7, B01F3