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| Asker: | Mr. V. P. Kamath |
| Ask Date: | 1/25/2008 3:11:28 AM |
| Question: | Wet Grinding |
| Detail: | We are in the process of upgrading our wet grinding mills which are used to grind aqueous slurries containing 25-45% solids from an initial particle size of 35-50 microns to < 1 micron (99%). The questions confronting us are - 1. How does one choose between a vertical and a horizontal mill ? The existing mills are all vertical. 2. How does the disc profile and/or the presence/absence and profile of the slots in the disc affect the performance of the mill. 3. Is there any guideline for the size of the media to be used ? |
| Reply: | 1) A vertical mill is normally used for mass productions (i.e. limestone) and has often a simpler design than a high tec horizontal mill. The advantage of a vertical mill is that it produces a steeper particle size distribution than a horizontal mill when both systems are run as a single passage grinding. For circuit processes our horizontal mill is easier to handle and therefore used. Normally one chooses between a vertical and horizontal system by checking all parameters, such as: throughput rate, viscosity of the end product, psd's, etc. Our horizontal mills are cheaper for products with smaller through put rates, so that is an important figure as well. 2)There are many theories in tha market about the advantages of disk profiles. We think that a cheap solution that can be easily lined with ceramic or polyurethan is the best solution. 3)There is a guideline for the size of the grinding media: the media should be at least 5 times bigger than the feed product. This has to be optimised for the process (type of mill, volume flow, etc.) |