EP1690597A1

EP1690597A1 - Connection system between in-series, continuous mills of a milling plant

Info

Publication number: EP1690597A1
Application number: EP06075032A
Authority: EP
Inventors: Simone c/o SACMI Coop. Mecc. Imola S.C. Casadio; Piero c/o SACMI Coop. Mecc. Imola S.C. Poli
Original assignee: Sacmi Imola SC
Current assignee: Sacmi Imola SC
Priority date: 2005-02-11
Filing date: 2006-01-10
Publication date: 2006-08-16
Anticipated expiration: 2026-01-10
Also published as: CN1817600A; PL1690597T3; RU2006101762A; PT1690597E; CN1817600B; ATE442906T1; EP1690597B1; DE602006009161D1; ES2331586T3; RU2394650C2; ITRE20050011A1

Abstract

A milling plant (1) comprising a plurality of continuous mills (2) provided with a loading mouth (6) of the material and a discharge mouth (8) of the casting slip, which are placed in series by means of a connection element (19) which, associated with an input device (20, 21), connects the discharge mouth (8) of a mill with the loading mouth (6) of the contiguous mill; said connection element (19) being associated with advancement means (23) adapted to advance the material which flows inside the connector (19) itself towards the loading mouth (6).

Description

The present invention generally refers to a milling plant particularly even if not exclusively intended to be employed in the preparation of ceramic mixtures. Such mixtures, indeed, are generally prepared by means of the moist pulverisation of the raw materials (silica, feldspar, clay) and the addition of specific additives, until a homogenous casting slip having the desired granulometry of the powders in suspension.
As is known, one such plant normally comprises at least one grinding mill, which is provided with a rotating cylinder, at whose interior the pulverisation operation of the raw materials is carried out by the collisions, and in any case mutual actions, between the raw materials themselves and a set of generally spherical grinding bodies.
The known grinding mills are subdivided into continuous and discontinuous mills, according to which the steps of loading the material inside the rotating cylinder and discharging of the casting slip occur in a continuous manner during the operation of the mill, or in discontinuous manner, requiring the temporary interruption of the productive process and the stopping of the rotating cylinder.
The present invention refers in particular to a milling plant comprising mills of continuous type.
According to the prior art in the ceramics field, the process of pulverisation of the raw materials foresees a set of successive steps, beginning with a crushing step and ending with a refining step. For the different steps, the grinding bodies must have different and decreasing sizes passing from the crushing to the refining and, consequently, for each of said steps there exists a rotation speed of the rotating cylinder which optimises the processing effectiveness, the execution time and the energy consumption of the grinding mill.
For these reasons, plants are known comprising a plurality of continuous grinding mills placed in series between each other, in which the rotating cylinder of each mill contains the grinding bodies, and is adapted to rotate at a speed independent from the others in order to be able to execute in optimal manner one of the aforementioned steps of the pulverisation process.
A similar plant is described in detail in the Italian patent application RE2003A000013 by the same applicant, to whose text one may refer for additional details.
In particular, each rotating cylinder of the aforementioned plant is provided with a loading mouth of the material to be processed and a discharging mouth of the casting slip which, fixed on opposite parts of the cylinder and arranged along the rotation axis of the same, are adapted to rotate integral with it, facilitating the continuous advancement of the input material and output casting slip.
Furthermore, the discharge mouth of an intermediate rotating cylinder is connected to the loading mouth of the successive cylinder by means of a tubular connection element, which is in turn associated with an input device adapted to introduce grinding bodies and appropriate additives (for example colorants) directly inside the downstream cylinder.
One drawback of these known plants lies in the fact that said tubular connection element, unlike the discharge and loading conduits which rotate integral with the respective rotating cylinders, must be integral with the input device and, consequently, fixed.
For this reason, the material which advances between one rotating cylinder and the next, when crossing the connection element, tends to stop, blocking the connector itself and thus compromising the operation of the entire plant.
Object of the present invention is that of overcoming the mentioned drawback, within the scope of a simple, rational solution with limited cost.
Such object is realised by means of a continuous milling plant comprising a plurality of continuous mills placed in series, in which the discharge mouth of one mill and the loading mouth of the subsequent mill are connected by means of a connection element comprising means adapted to make the material which crosses it continuously advance.
According to a preferred embodiment of the invention, said advancement means comprise a helical body fixed at the free end of one of the discharge mouths of the upstream mill and the loading mouth of the downstream mill, so that said helical body is inserted within the connection element, realising a screw device with the latter which permits the advancement of the material.
Further characteristics and advantages of the invention will be evident from the reading of the following description provided as exemplifying and not limiting, with the aid of the figures illustrated in the attached tables, in which:

figure 1 shows a schematic view of the continuous milling plant according to the invention;
figure 2 shows a detail of figure 1 in longitudinal section.

With reference to the attached figures, the milling plant, object of the present invention, indicated in its entirety with 1, comprises a plurality of continuous mills 2 placed in series. Each mill 2 comprises a rotating cylinder 3, which is formed by a horizontal axis cylindrical body 4, closed at one end by a first bottom 5 provided with an axial mouth 6 for the loading of the material, and closed at the opposite end by a bottom 7 provided with an axial mouth 8 for the discharging of the casting slip.
The cylindrical body 3 is supported at each of the ends by a suitable structure 9, and is operated by an appropriate control system 10 through a belt system 11.
Inside the cylindrical body 3, a grinding chamber is defined, at whose interior both the grinding bodies and the raw materials which compose the casting slip are fed, or rather essentially water, silica, feldspar and clay. The grinding bodies are typically in silica or aluminium and during the operation of the plan are worn until they are mixed with the casting slip being processed.
In figure 1 it is seen that the first upstream continuous mill 2 is provided with a per se known normal loading system 18 of the raw materials, and that the loading mouth 6 of the second mill, and possible subsequent mills, is connected to the discharge mouth 8 of the preceding mill by means of a tubular connection element 19. Connected to said tubular connector 19 is an additional input conduit 20 which, associated with a normal loading device 21, is adapted to feed both grinding bodies and other additives.
Advantageously, said input conduit 20 permits both separately reintegrating the grinding bodies for each of the continuous mills 2 and separately introducing materials, or water, constantly permitting mixture correction and thus guaranteeing an optimal composition.
Each of the continuous mills 2 of the milling plant 1, being operatively independent from the others, is sized and optimised in geometric terms, in the dimensions of the grinding bodies as well as in the rotation speed, for the specific pulverisation step to which it is assigned, and the processing casting slip continuously passes from one rotating cylinder 3 to the next without interrupting the process, until the desired granulometry of the powders in suspension is obtained.
In detail, as illustrated in figure 2, the release of the refined casting slip from the operative chamber of a rotating cylinder 3 is assigned to normal per se known means 13 which, therefore, are not described further. Nevertheless, it should be underlined that, despite the fact that said release means 13 are adapted to advance the casting slip towards the rotating cylinder 3 placed downstream, such advancement is also permitted, and therefore made effective, by the rotation of the discharge mouth 8 and the loading mouth 6, which are integral with respective rotating cylinders 3.
As previously mentioned, between said discharge mouth 8 and loading mouth 9 the connector 19 is interposed, which is composed of a tube fixed to the support structure 9 by means of two rigid supports 25, to which the discharge mouth 8 is rotatably associated on one side, while on the other side the loading mouth 6 is rotatably associated. In detail, the free end of the discharge mouth 8 is axially inserted for a section inside the tubular connector 19, which in turn is inserted for a section inside the free end of the loading mouth 6.
Possibly, between said discharge 8 and loading 6 mouths and the tubular connector 19, sealing means may be interposed which are adapted to advantageously avoid that there are losses of material from the plant 1.
In particular, as is visible in figure 2, at the free end of the discharge conduit 8 a helical body 23 is cantilevered, which, extending coaxially within the tubular connector, realises a screw device with the latter.
During the operation of the plant 1, the rotating cylinders 3 rotate independently from each other and, consequently, drive in rotation the discharge 8 and loading 6 mouths, while the tubular connector 19 remains fixed. In this manner, the helical body 23, which is united to the discharge mouth 8, rotates inside said connector 19, and pushes the material coming from the upstream rotating cylinder 3 and from the input conduit 20 to advance towards the loading mouth 6 of the downstream rotating cylinder 3.
Obviously, to the plant thus described there may be brought modifications or suggested improvements, without leaving the context of the invention as claimed below.

Claims

Milling plant (1) comprising a plurality of continuous mills provided with a loading mouth (6) of the material and a discharge mouth (8) of the casting slip, which are placed in series by means of a connection element (19) which, associated with an input device (20, 21), connects the discharge mouth (8) of one mill with the loading mouth (6) of the contiguous mill, characterised in that said connection element (19) is associated with advancement means (23) adapted to advance the material which flows within the connector (19) itself towards the loading mouth (6).
Plant (1) according to claim 1, characterised in that the advancement means comprise a helical body (23) positioned within the connection element (19), and operated to rotate so to realise with the latter a screw device which permits the advancement of the material.
Plant (1) according to claim 2, characterised in that the helical body (23) is cantilevered at the discharge mouth (8), so to be moved by the rotation of the continuous mill (2), to which said mouth is associated.
Plant (1) according to claim 2, characterised in that the helical body (23) is cantilevered at the loading mouth (6), so to be moved by the rotation of the continuous mill (2), to which said mouth is associated.
Plant (1) according to claim 1, characterised in that the input device comprises a loading device (21) of the material, and an input conduit (20) which connects said loading device (21) to the connection element (19).
Plant (1) according to claim 1, characterised in that between each of the discharge mouths (8) and loading mouths (6), and the connection element (19), sealing means are interposed.