Posted: February 7th, 2017
Starting Information: Suppose you are the designer for an underground conveyor installation that is to transport raw coal in lumped and crushed forms and all debris from a coal cutting area over a distance of more than 1000 metres to a large receiving bin. The conveyor is to be installed in a tunnel that has an adjacent walkway for persons to access the coal face. The tunnel section has a 1 in 10 gradient from the input up to the receiving bin. The conveyor will be run at a height of 1.0 meters above ground with the returning belt being at 0.3 meters above ground. Crossover bridges or underpasses will be provided where necessary for persons. No vehicle crossovers are needed. There will be an elevated section at the delivery end of the conveyor to discharge into receiving bin for the elevator. The conveyor will be constructed as a woven steel mesh with rubber covering and will be tensioned by a hydraulic tensioning unit under automatic control. Conveyor has an indirect drive with a fluid coupling. The drive will be interlocked with the receiving hopper to avoid delivery when the hopper is full. Operations will be supervised from the area remote control panel. Assume normal occupancy of the conveyor area is 4 persons close enough for harm once per hour. In the general area assume up to 10 persons may be present once per hour.
You are required to do a risk assessment involving hazard identification with risk estimates combined with risk reduction suggestions
You will find a risk assessment spreadsheet tool and reporting table blank in the supplied file: RA Blank.xls. Save your own copy with your initials and submit your RA results on this file.
The risk estimates will use the PILZ scales for likelihood, consequence, exposure and number of persons. The tables of values are shown in the “risk parameters” sheet.
Marks will be awarded for methodology and consistency. Make your best estimates of risk parameters, but the values will not be critical for marking. Expect to find at least 10 entry items but several more may be found. Maximum marks can be achieved with 10 good entries. Risk assessment on an underground conveyor in a coal mine
Step 1: Begin by describing the limits of the machine and its application environment that you are going to assume. Basically this can be limited to the conveyor and its drives. Then by using the checklist in the RA sheet identify as many hazards as possible and briefly describe them in the appropriate entry row in the spreadsheet. See entry line for hazard 1.1 as an example.
Step 2: For each hazard that you believe may exist state the possible causes and consequences on the record sheet. Now estimate the likelihood and consequence values of the event to obtain the “initial assessment” that will apply if no risk reduction measures are applied. Enter “N/A” for any hazard that is not applicable in your view. In addition to the human consequences please also add in a value from 0-5 for your estimate of any asset loss due to the event. 0 = no loss and 5 = complete loss of the equipment and extended production losses.
Step 3: Now consider the possibilities of applying the risk reduction steps shown in figure 3.9 to each hazard in turn and enter your suggestions in the table.
Step 4: Update the risk score values in the “revised assessment” columns to obtain the revised risk score. Now enter your required actions for the design team including the production of notices or operating instructions. Add any point you feel relevant into the comments column.
Step 5: Update the RA Summary sheet by copying across those hazard entries that require any action.
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