Cement Grinding - Mill

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Cement Manufacturing Process : 

Cement Manufacturing Process GIRISH KUMAR

Slide 2: 

To improve productivity and power consumption through Optimisation of mill which includes ball charge, ventilation and mill internals and separators performance. To set the targets based upon grindability of feed materials. To implement the Best Practices. To determine good practice levels and methods employed including Lucie implementation to achieve maximum efficiency of grinding system.



Ball charge conditions in C1 and C2 : 

Purpose Evaluating ball charge wear Detecting a mechanical problem (breakage of a diaphragm sector) Criteria Clean charge (no scrap) Round balls (not deformed) and of suitable size Corrective measures Ball charge sorting in case of contamination C1 ball sorting (every 5000 - 7000 h) C2 ball sorting (every 10000 - 14000 h) Ball charge conditions in C1 and C2

Conditions of the lifting liners : 

Conditions of the lifting liners Purpose Insuring proper cascading of the balls and hence crushing of material General condition of liners Plate conditions (breaks, chips, attachments) Criterion Performance should be checked when step < 40%of initial step (wear=60%) Corrective measure Replacement Step rotation

Ball Charge Classification : 

Ball Charge Classification Purpose Adapts the charge granulometry to that of the material Criterion Progressive decrease of the ball size in C2 Corrective measures Sorting and optimization of the ball charge Replacing liners Checking the size of slots 6mm intermediate diaphragm 8mm outlet diaphragm

Material level in C1 and C2 : 

Material level in C1 and C2 Criterion Material level = ball level over the entire compt. Corrective measures Change in the number of small balls 60 mm or 50 mm in C1 and 20 mm or 17 mm in C2 Scoop adjustments Control of the circulating load

Diaphragm Slots : 

Diaphragm Slots Criteria C1 slots from 6 to 8 mm C2 outlet slots larger by at least 2 mm than those of C1 outlet Corrective measures Filing and cleaning Diaphragm replacement

Compartment Samples : 

Compartment Samples Purpose Grinding assessment(C1 and C2) Determining spitzer locations Quick evaluation Samples taken at the discharge end of the compartment COMPARTMENT N°2 COMPARTMENT N°1 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X C1 1 2 3 4 5 6 C2 1 2 3 4 5 Samples Direction of rotation Charge 0.5m

Slide 15: 

Equal positioning for sample collection and media grading (measure 40 media balls at each position).

Slide 16: 

Second chamber sample collection using sieve.

Slide 17: 

Measuring media diameter using vernier caliper

Slide 18: 

Typical velocities through the mill

Slide 19: 

conventional material transport effect of the material flow control Controlling material level in C1 and C2

Compartment Samples : 

Fineness evolution in the mill Sample Number % Cumulated rejects 40 µm 63 µm 100 µm 200 µm 500 µm 1 mm 2,5 mm 5 mm Diaphragm Diaphragm Compartment Samples Criteria <5% retained on 2 .3 mm sieve at the diaphragm Progressive decrease all along the mill Corrective measure Adapting the charge granulometry Changing the length Inadequate grinding Presence of grains

Summary : 

Summary Conditions of lifting liners Performance has to be looked at if step < 40% of initial step (wear=60%) Volume loading : 28% to 34% Ball charge conditions : Clean, round shape and suitable size for the compartment C1 has to be sorted every 5000 to 7000 h C2 has to be sorted every 10 000 to 14 000 h

Summary : 

Summary Material level Material level = ball level over the entire compartment Ball charge classification : progressive decrease of the ball size in C2 Diaphragm slots : first compartment slots: 6mm to 8mm second compartment outlet slots larger by at least 2mm than those of first compartment Ventilation screens they have to have the maximum permeability to let the maximum gas flow through the mill while retaining the balls

General description : 

General description Circulation load (C.L.) amount of separator rejects expressed as a percentage of the mill’s finished product rate control of this parameter is essential to ensure good functioning of the mill shop Mill-throughput (MT) sum of fresh feed rate and rejects flow-rate.

Operating : 

Operating The sequence used to run the ball mill shop Control with the sensors Optimize according to the strategy Adjust with the actuators

Operating : 

Operating Which actuators are used to control the milling operation ? on the mill on the separator

Operating : 

Operating Some parameters will limit the production rate any equipment which has reached its nominal value elevator, fan, feeders, material transport volume loading of the mill info will be given by the electrical ear and the mill power characteristics of the feed particles size and grindability if the material is moist, the drying capacity will limit the feed rate achievement of the required quality

Operating : 

Operating how to produce a cement to a given fineness in a closed circuit , the basic rules? Air circuit Mill ventilation Fresh feed Mill throughput Sep. rejects Sep. fines

Operating : 

Operating the basic rules, Air circuit Mill ventilation Fresh feed Constant Mill throughput Sep. fines Sep. rejects constant

Operating : 

Operating feed the mill ventilate the mill to optimize particles transport and temperature control feed the mill after having reached an equilibrium of the shop control the fineness of the cement by adjusting the speed of the separator. correct the fresh feed to the mill in order to keep mill throughput constant control the temperature of the material at the mill outlet

Operating : 

Operating when starting a cold mill some more steps are required for the start-up no material with high moisture should be fed to the mill close the fresh air flaps start according to the previous procedure operate the mill until the material temperature has reached 70°C at the mill outlet feed the moist materials and adjust the shop to reach the targeted fineness when mill is warm adjust the fresh air flaps according to the temperatures

Operating : 

Operating mill throughput plugging at the mill inlet elevator power electrical ear (control of the material level in the mill) mill power pressure drop in the mill

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