OA18048A - A method for operating a ball mill and a milling system. - Google Patents

Abstract

The present invention relates to a method for treating a viscous mass comprising solid components in a grinding system, especially a fatty mass with solid components, said grinding system comprising a mixer and a grinding device, said method comprising the steps of : feeding into a mixer the mass to be treated; repeatedly circulating the mass to be treated by means of a displacement device from the mixer through a supply pipe to the grinding device and through a return pipe back to the mixer for reducing the size of said solid components in said grinding device; and further comprising the step of: removing from the system at least part of the treated mass through a branch-off provided in the return line when a predetermined grinding fineness has been obtained; and feeding into the mixer a new mass to be treated and at least partly displacing the new mass to be treated in said grinding device by means of said displacement device and as a consequence removing at least another part of said treated mass from said system.

Description

A METHOD FOR OPERATING A BALL MILL AND A MILLING SYSTEM

The présent invention relates to a method according to the preamble of clam 1. The invention further relates to a grinding system for performing the method according to claim Ί.

Such a method is known in the art. For example, when producing fatty masses that comprise solid components and the like products (such as chocolaté and cocoa mass; wherein the fatty mass comprises at least one of the following components: sugar, milk powder, whey powder, lecithin, flavor and cocoa powder), hereinafter generally referred to as fatty mass, a certain amount of a mass to be ground is fed into a mixer after which the said mass is displaced towards a grinding device by means of a displacement device. Said displacement device usually is a pump. When processing a fatty mass, like chocolaté and the like, the pump must be suitable for yielding a relatively large delivery head due to the highly viscous character of the said mass. The mass to be treated is circulated several times, such that the said mass passes through said grinding device several times. As a conséquence, the paruicle size of said solid components is reduced in said grinding device. The grinding device may advantageously be a bail mill, as marketed by the firm Caotech B.V. from Wormerveer/NL, for example the types CA01000, CA02000, CA03000 and CA04000, ail of these being sccalled attrition bail mills. After a required particle size distribution is obtained, said grinding method is ended and the treated mass is removed from said sysrem. Such is obtained by removing said treated mass through a branch off tha~ is provided in the supply pipe by using said pump. The branch of usually is provided somewhere before or after said bail mill; for example, as a branch off in a pipe between the pump and the bail mill, or as a branch off in a pipe between the bail mill and the mixer. However, part of said treated mass that is présent in said grinding device will substantially not be removed from the system, since a main part thereof will stick to the grinding facilities. Such especially is obtained when using bail mills. The amount of treated mass remaining in the system may be up to 40% of the total amount of treated mass in said system.

A disadvantage of said known method therefore is comprised of the fact that a large amount of treated mass remains in the System.

In the art, there is no practical or economical solution for a bail mill, as far as' it regards coca, chocolaté and chocolatelike products. The so-called 5~roll refiner that is used for processing chocolaté and chocolate-like products is no économie match for a bail mill.

The présent invention aims at providing an improved method of the kind indicated in the preamble.

The invention especially aims at providing a method of the kind mentioned in the preamble that yields a larger output than the Systems presently available.

The invention also aims at providing an improved method with which an improved product is obtained.

So as to obtain at least one of the above mentioned advantages, according to a first embodiment the présent invention provides a method comprising the features of claim 1. Such method has the advantage that a faster production and a larger output for every batch are obtained.

It has also shown that in the method according to the présent invention a considerably smaller particle size distribution is obtained than with the methods according to the state of the art. This may be due to the act that in the known method the subséquent batch is mixed with a large amount of the préviens batch and is subjected to the grinding processed again. As a conséquence, part of said mass is ground too fine. Such yields a still higher viscositv, especially when grinding fatty masses. Ir. its turn, a higher viscosity leads te a larger amount that remair.s in said grinding device due to its sticky behavior, especially in a bail mill. Therefore, the présent invention provides a huge advantage with respect to the method according to the state cf the art because the particle size distribution is much smaller. Such synergetic resuit was completely unexpected.

It has also shown that température control is much beuter with the présent novel method. The température of the mass to be treated increases when processing same. With the known method, the starting température is larger than with the présent method, due to the large amount of treated mass remaining in the System. The lower starting température in the présent method provides a lower end température of the treated mass, even if the mass is cooled intérim. This synergetic effect is completely unexpected as well.

As mentioned above, it is especially preferred for the grinding device to be a bail mil. This allows to obtain an accurate grinding, while obtaining a relatively accurate displacement of the mass to be treated within said grinding System as well, yielding an accurate grinding of said mass.

As mentioned above, it is preferred that the viscous fatty mass is a fatty mass that comprises solid components that comprises at least one of the following components: sugar, milk powder, whey powder, lecithin, flavor and cocoa powder as solid components. An example thereof is a mass comprising cocoa butter. The fatty mass may for example be mixed with sugar, milk powder and flavors and be ground in said grinding device until a required particle size distribution is obtained. Regarding production of chocolaté or chocolaté like products, cocoa mass or cocoa powder, respectively, may be added. Other substances may be added as desired to the recipe.

Preference is especially given to a method wherein the volume of the new mass to be treated is larger than the mixer's volume. This renders it possible that when replacing the treated mass with a new mass to be treated, the mixer and a further part of the grinding system is filled with the new mass to be treated. This is contradictory to the state of the art, where only the mixer can be filled with the new mass to be treated.

Therefore, it is preferred that the system comprises a storage vessel, the volume of which is larger than the mixer's volume. In said storage vessel, a stock of mass to be treated may be ccmposed that can be fed into said mixer when a treated mass is to be removed from the system.

It is especially preferred that the volume of the new mass to be treated is smaller than the combined volume of the mixer and the grinding device. Due to the mixer's volume, the amount of new mass to be treated will be added incrementally to said mixer. When removing the treated mass from the .system, no idéal plug flow behavior will be obtained in the grinding device. As a conséquence, part of the new mass to be treated will reach at the branch off in said return pipe whereas a small part of said treated mass still remains in the system. Although according to the présent invention a small part only remains in the system, such amount is very small, maximally 10% and preferably even less than 5%.

According to a further aspect, the invention relates to a grinding system for performing a method according to the présent invention as mentioned above, said grinding system comprising a mixer and a grinding device, said mixer on the one hand being connected to the grinding device by means of a supply pipe and a displacement device being provided for displacing said mass from said mixer to the grinding device, and on the other hand said grinding device being connected to said mixer by means of a return pipe, said grinding system being characterized in that a branch off is provided in said return pipe for removing treated mass from said System. In such System, the several embodiments of the method according to the invention can easily be implemented, such that the advantages as stated above are accomplished.

In the system according to the présent invention, it is especially preferred that the storage vessel has a larger volume than the mixer.

It is especially preferred that the grinding device comprises a bail mill, with the remark that the grinding system is net limited to such bail mill.

SO as to be able to displace the mass through said system, it is preferred that the displacement device comprises a pump.

The invention also relates to a treated mass, obtair.ed with the method according to the présent invention or with a grinding system according to the invention. The particle size distribution of such mass is substantially smaller than the particle size distribution of a mass according to the state of the art.

The invention also relates to a fatty mass that comprises ground solid components, obtained with a method according to the présent invention or with a grinding system according to the invention. The particle size distribution of such mass is considerably smaller than the particle size distribution of a mass obtained according to the state of the art.

Hereafter, the invention will be further described by means of a drawing. The drawing shows in Fig. 1 a schematic view of a grinding system according to the présent invention.

For sake of simplicity, not ail parts that are required for a practical embodiment of the invention are shown in the drawing.

Fig. 1 shows a schematic view of a grinding system 1 according to the invention. Said grinding system 1 comprises a storage vessel 2, being connected to a mixer 4 through a connection pipe

3. Said mixer 4 is connected to a bail mill 6 through a supply pipe 5. A mass to be treated (not visible) is fed through the supply pipe 5 to the bottom 8 of said bail mill 6 by means of a pump 7 from said mixer 4. In the embodiment shown in the Figure, said mass to be treated runs through said bail mill 6 from the bottom up. At the top 9 of said bail mill 6 the treated mass leaves said bail mill 6 and is returned through a return pipe 10 to the mixer

4. In said mixer, the treated mass is mixed with other content. Subsequently, said mass is fed from said mixer 4 ûo the bail mill 6 again through supply pipe 5. This treatment is performed for a predetermined time period or as long as necessary until a required particle size distribution of the particles that are présent ir. the mast to be treated is obtained.

üpon finishing the treatment, pump 7 displaces treated mass from mixer 4 through bail mill 6 and removes same at brar.ch off 11 through drain pipe 12. After said mixer is emptied, a new mass to be treated is fed from storage vessel 2 into said mixer 4 and, in synchronism with pumping of said treated mass, pumped into bail mill 6 through supply pipe 5. The amount of new mass to be treated that is added to the mixer 4 is such, that no new, unground mass to be treated reaches drain pipe 12. Right before that moment, branch off 11 is closed and the grinding process according to the présent invention is continued. Due to the fact that the volume of the mixer is smaller than the volume of new mass to be treated that was added, the new mass to be treated cannot be added in one step to the mixer. As a conséquence, after closing branch off 11 the remaining part of the new mass to be treated can be fed into said mixer and the treatment cycle can be performed on said new mass to be treated.

The method according to the présent invention is extremely suitable for grinding fatty masses, such as mentioned before. A practical application of a fatty mass according to the présent invention for example consists of production of chocolaté products for stuffing and the like.

The invention is not limited to the embodiments as mentioned above and as shown in the drawing. The invention is limited only by the appending daims.

The invention also embodies al combinations of features and steps that hâve been described herein independently from each oth15 er.

Claims (10)

1. A method·for treating a viscous mass that comprises solid components in a grinding system, especially a fatty mass with solid components, said grinding system comprising a mixer and a grinding device, said method comprising the steps of:

- feeding into a mixer the mass to be treated,

- repeatedly circulating the mass to be treated by means of a displacement device from the mixer through a supply pipe to the grinding device and through a return pipe back to the mixer for reducing the size of said solid components in said grinding device, characterized in that the method also comprises the step of:

- removing from the system at least part of the treated mass through a branch-off provided in the return line when a predetermined grinding fineness has been obtained, and

- feeding into the mixer a new mass to be treated and at least partly displacing the new mass to be treated in said grinding device by means of said displacement device and as a conséquence removing at least another part of said treated mass from said System.

2. A method according to claim 1, wherein said grinding device is a bail mill.

3. A method according to claim 1 or 2, wherein said far.ry mass is a mass comprising at least one of the following components: cocoa mass, milk powder, whey powder, lecithin, flavor, and sugar.

4. A method according te claims 1, 2 or 3, wherein a volume of rhe new mass to be treated is larger than the mixer' s volume.

5. A method according to claim 4, wherein the volume of the new mass to be treated is smaller than the combined volume of the mixer and the grinding device.

6. A method according to any of the preceding daims, wherein the system comprises a storage vessel the volume of which is larger than the mixer's volume.

7. A grinding system for performing a method according to any of the preceding daims, wherein the grinding system comprises a mixer and a grinding device, said mixer on the one hand being connected to the grinding device by means of a supply pipe and a displacement device being provided for displacing said mass from said mixer to the grinding device, and on the other hand said grinding device being connected to said mixer by means of a return pipe, characterized in that a branch off is provided in said return pipe for removing treated mass from said system.

8. A grinding system according to claim 7, said grinding device comprising a bail mill.

9. A grinding system according to any of daims 7-8, said displacement device comprising a pump.

10. A grinding device according to any of daims 7-9, comprising a storage vessel, the volume of said storage vessel being larger than the mixer's volume.