Area: Minning Maintenance Realibility
COMMISSIONING
After the usual pre-commissioning checks and dry runs, hot commissioning of the filter started on 19 August 2000. The filter exceeded its rated capacity after one month of operation. The current operational parameters are as follows:
Average Cycle Time: 11 minutes.
Average Number of Cycles: 120 per day.
Average Capacity: 518 dmt/day.
The filter is consistently exceeding its rated capacity of 470 dmt and we are very satisfied with its performance.

The press has three operational modes.
1. Manual Mode (Maintenance Mode).
2. Semi Auto Mode.
3. Auto Mode (Operation Mode).

5.1 Manual Mode
All functions are manually controlled. This mode is also called the maintenance mode and is required during maintenance.
5.2 Semi Auto Mode
The press operates and stops at the end of each phase of operation and requires restarting after each phase. This mode is used to optimise the operating conditions, especially during commissioning.
5.3 Auto Mode
The filter is started by simply pressing the start button and it completes a full cycle automatically. It does not need restarting at the end of each cycle. It stops only when the "feed tank empty" alarm is activated.

Performance Comparison
6.1.1. Capacity (Number of Cycles)
R&B filters: The rated capacities are 390 dmt/day for copper and 330 dmt/day for the zinc filters. The average cycle time is 20-25 minutes This is highly dependent on cake discharge. The 
Filling
 Membrane squeezing 
Cake blow cycles take 12-15 minutes.
Cake discharging takes about half of die time required for the rest of tie steps. The plate-shifting mechanism is a problem and the operator is required to complete the cake discharge and clean the plates.
The plate-shifting mechanism chain and connection pieces, shifting hook, and locking hook (pawl) stick and plates often do not move. Sometimes, due to these difficulties, it is only possible to average 40-50 cycles per day. In actual operation, only about 280 dmt/day is obtained, based on availability due to operational problems which are explained below.
6.1.2 Labour Requirements
R&B filters: ÇBI employs 2 operators per shift to operate these filters due to frequent cloth changes (average 2200 cycles for one set of cloth) and platemoving problems. The seal surfaces on the sides of the plates and around the feed opening require continuous cleaning after each cycle due to the lack of an auto cloth wash provision. An auto cloth wash after each cycle is not possible with the existing design. This is explained in more detail ?n the maintenance comparison section.

6.1.3 Difficulties in Plate Shifting
R&B filters: The plates are hung on a rail with carriages. The carriages are equipped with hooks. There is a continuous running chain mechanism with shifter hooks attached. These shifter hooks catch the locking hooks (pawls) on the plate carriages and move the plates. This complex system causes frequent plate-shifting problems. This reduces the performance of the press. When plate-shifting problems start, the operator needs to climb on top of the filter to release the plates and maintenance assistance is required to change the damaged connection pieces.

6.1.4 Vibration Bars for Cake Removal
R&B filters: No vibration bars ?n design. MC LASTA filter: When cake sticks to the cloth, the cloth support bar ?s depressed due to the weight of the sticky material and blocks the photo beam. This activates a vibration cycle and shakes all the plates from both sides. The vibration cycle is also an indication of possible cloth problems, i.e., holes, blinding, etc.

6.1.5 Cake Discharge System
R&B filters: The cake falls with its own weight by gravity, and there are no additional features to help discharge the cake.
MC LASTA filter: The weight of the cake on the cloth rapidly compresses the springs which support the cloth support bars. The bars come to a sudden stop, which creates a shear effect between the cake and the filter cloth. This helps removal of the cake from the filter cloth.