DE2818175B1 - Process for crushing mineral raw materials - Google Patents

Description

The flow diagram is clearly laid out and does not require any special Explanation. It is easy to see that by merging and mixing the individual Material flows the mineral grain mixture 0.09 to 3 mm with minimal oversize and Undersize fraction is obtained. Furthermore, there was a cost saving through avoidance the pre-drying and the drying achieved during the comminution. The moisture levels of leading material are like this.

that under the previously known processing conditions the production a certain small grain size with minimal oversized and undersized grains without Drying is not possible.

Claims (4)

Claims: 1. Method for comminuting mineral raw materials to produce a mineral grain mixture with a given grain size range smaller Grain sizes while largely avoiding oversized and undersized grains, d a d u raw g e - indicates that one of the moist, especially washed, mineral Raw materials first the grain fraction of the desired grain size range together with the undersized grain, then the remaining oversized grains into at least two Grain fractions broken down, these fractions crushed and processed separately. 2. The method according to claim 1, characterized in that the oversize fraction with the smaller grain sizes after the crushing first of the desired Grain fraction is freed, while the residue is further crushing operation is subjected, in which the desired grain fraction is sieved off and the sieve residue is fed to the comminution. 3. The method according to claim 1, characterized in that one or several of the grain fractions of the oversized grain with the larger grain sizes after separated Crushing freed from the desired grain fraction and the undersized grain by sieving is, while the sieve residue is being ground, in a subsequent sieving stage the desired fraction and the undersize is sieved and the residue is crushed again will. 4. The method according to claim 3, characterized in that the desired Grain fraction together with the undersized grain in a single or multi-stage classifying system are supplied with separation of the undersize and recovery of the desired fraction. Mineral raw materials are becoming smaller for various areas of application Grain sizes, for example with grain sizes <5 mm or <3 mm, are required. Since these mostly do not exist in nature in this form, but rather in particular wherever there are mineral raw materials of this type from limestone, dolomite or magnesite they have to be of the desired fineness by crushing them more coarsely Available grain sizes, for example 0 to 60 mm or 0 to 90 mm, through targeted processing can be obtained. Since the tolerance limits for oversize and undersize, for example undersize <than 0.09 mm, often set tightly, it depends on the size reduction operations in the context of processing so that there is little oversized grain, which is proportionate can easily be achieved, but also that at the same time as little undersize as possible arises, which are usually not used elsewhere in the resulting quantities can and has also consumed disproportionately high grinding energy, whereby the salable desired grain more expensive. In addition, the raw material used has to be washed beforehand must be cleaned refer- or because of the fully exposed to the weather Degradation process with more or less moisture occurs. According to common methods, therefore the raw material is first dried to a low moisture content, or a drying carried out with simultaneous comminution. the Drying is particularly necessary because otherwise the undersize fraction will be can only be separated incompletely from the desired grain fraction. The object was therefore to provide a method for comminuting mineral Raw materials for the production of a mineral grain mixture of small grain sizes and with a given To develop grain size range, which largely emerges in its implementation of oversized and undersized grains, with special consideration of the grain size ranges <than 5 mm and especially <than 3 mm. The avoidance of undersize is thereby the more difficult, the smaller the maximum grain size may be. The solution to this Task is made even more difficult by the additional task that the mineral Raw material without prior drying, or practically without drying during of the preparation process is to be processed. Surprisingly, it has been found that the task thereby can be coped with that one of the damp, especially washed, mineral Raw materials first the grain fraction of the desired grain size range together with the undersized grain, then the remaining oversized grains into at least two Grain fractions broken down, these fractions crushed and processed separately. According to an advantageous embodiment of the present invention the oversize fraction with the smaller grain sizes is initially after the comminution freed from the desired grain fraction, while the residue of a further crushing operation is subjected, in which the desired grain fraction is sieved off and the sieve residue is fed to the comminution. Furthermore, a further advantageous embodiment consists in that one or more of the grain fractions of the oversized grain with the larger grain sizes Separate crushing by sieving the desired grain fraction and the undersized grain is freed while the sieve residue is ground up, with a subsequent one Sieve stage the desired fraction and the undersize and sieve off the residue is crushed again. Finally, it can prove to be advantageous that the desired Grain fraction together with the undersized grain of a single or multi-stage classifying plant are supplied with separation of the undersize and recovery of the desired fraction. The present invention is intended to be based on the flow sheet according to FIG Drawing will be explained by way of example. The example uses a mineral raw material in the grain size range 0 to 60 mm assumed. the desired mineral grain mixture grain sizes between 0.09 and should have 3 mm.