Regarding mill load and slurry concentration parameters
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Ladies and gentlemen, the basic operating parameters for each grinder in our plant are as follows: The grinders are rod mills; their size is 4.3*6 meters. The aperture size of the roller screens is 4*40 mm. The coal feed rate per grinder is 90 T/h. There is no ultra-fine grinding process in use. Currently, the pulp concentration is 60.2% with a viscosity of 330 Cp. If both grinders operate simultaneously, the coal feed rate is distributed evenly, allowing the concentration to be increased to 62% and the viscosity to 800. However, the management requires that only one grinder be used at a time. I would like to ask: Is there any manufacturer that has mills of a similar size, capable of handling a feed rate of around 90 T/h, and that can achieve a slurry concentration of over 61%? . Want to learn* let’s discuss it. . .
With a large feed rate, the particle size may be larger
It’s exactly the same as ours, but our coal slurry concentration remains at 61-63%, allowing for stable operation; its viscosity is between 600-1000. Is it because you increased the concentration that there’s constant slurry leakage, which is why you’re hesitant to raise the concentration?
Do not raise the coal slurry concentration too high; it depends on your gas production volume and process parameters. To achieve stable, optimal, high-performance operation over extended periods, the coal slurry concentration should be within an appropriate range. . . . . . . . . . . .
I think the starting point for considering this issue is incorrect; the quality of coal slurry does not depend on the coal grinder, but rather on the coal itself. The coal grinder is large, so the amount of steel rods added is also large. A comprehensive analysis should be conducted taking into account both the concentration of the coal slurry and its particle size. Refer to the engineering design specifications for coal slurry systems when you have time
Top notch, experts, please give some advice……
Which company’s? Is it 90 tons per mill? What size is the mill?
My company used to have mills similar to yours, but the concentration level was not as high as yours. Have you carried out any technical upgrades?； :)
This post was last edited by wlq1970 on 2015-8-25 at 13:44. This issue can also be resolved easily: if a coal grinding rate of 90 T/h is not the maximum load and the grindability index of the coal is high, it is possible to adjust the proportion of steel rods – increasing the proportion of the finest rods by about 5% and raising the proportion of the medium-sized rods by about 3% for grinding. Observe any changes in the particle size of the coal slurry; at this point, the proportions of particles with sizes of 200 mesh and 325 mesh should increase. The viscosity of the coal slurry should also rise as a result. Adjust the amount of additives added, and after running the system for some time, analyze the concentration of the coal slurry – it should increase as well. The concentration of the coal slurry is closely related to its particle size distribution. Based on the results you described, it seems that there is a problem with the particle size of the coal slurry. It’s best to check whether there are any broken steel rods before conducting experiments, and to check again after running the system for a while, as too many fine rods may cause them to break.
I agree with what was said above; based on the data you provided, 90T seems to be the maximum processing capacity of the mill. The rod ratio recommended to you by the mill manufacturer is based on the mill operating under its rated load conditions, not under maximum load. To produce high-quality coal slurry even under maximum load conditions, several factors need to be taken into account: 1. As mentioned above, your steel rod ratio needs to be adjusted; under high load, the particle size of the coal slurry produced by the mill will deviate from the optimal range, with an increase in particle size, which in turn leads to a decrease in both the concentration and viscosity of the slurry ； 2. Check the type of coal you are using; once the coal type is fixed, the maximum concentration at which that coal can be ground into slurry is also fixed. Additionally, the moisture content of the coal (including internal and external moisture) has a significant impact on the slurry concentration ； 3. Based on the data you provided, the coal slurry concentration is low and its viscosity is also low; under high load conditions, this is usually caused by larger particle sizes. Check your mill steel rods to see if any are bent or short; remove them and replace them with new rods. Also, add more rods as suggested above.
A single 4.3*6 miller cannot handle such a high load; it’s impossible to shut down one unit and use another in its place. Our company also has a load of 90; it operates two grinders, and the concentration is 4.3*6. Depending on the degree of coalification and the proportion of different coal types used, it is possible to produce coal slurry with varying concentrations.