DESIGN AND SPECIFICATIONS
Suspension of Conveyor system underground:
- The conveyor system is suspended from the hanging wall by means of pigtail eyebolts
- The conveyor stringers are suspended to the eye bolts in the hanging wall by means of 1Omm chain links, attached to the stringers by means of fish plates with adjusting turn buckles for alignment
- The chains are 3m apart on either side of the conveyor stringer
- Idler brackets and idlers are installed 1m apart on top of the stringer
- return brackets and idlers are installed at the bottom of the stringer 2m apart
Hold back or anti -slip devices:
All incline belts to be fitted with holdback and anti-slip device to prevent backward movement when stopped or broken to prevent the conveyor from running backwards
- Anti-slip devices are installed on all belts
- Gear box designed to prevent roll back (Sprag)
Environmental conditions that could affect the integrity of the conveyor belt installation:
Underground-
- Conveyor belt structures underground are exposed to various environmental conditions including hot, humid and high air velocity conditions.
- Conveyor belt structures must therefore be protected with a rust protecting paint.
- Galvanised steel work need not be painted.
Surface-
- Conveyor belt structures on surface are exposed to various environmental conditions including sun, rain, hot, humid and high air velocity conditions.
- Conveyor belt structures must therefore be protected with a rust protecting paint.
- Galvanised steel work need not be painted
- The design engineer must take into account the foundations, the presence of water, wind, safe ventilation design as well as access and exit points and final approval must be obtained from the responsible engineer
An appropriate drainage system along the conveyor belt installation to ensure efficient draining of water used for cleaning, dust suppression and prevent water seepage onto the conveyor belt installation;
Underground-
- The conveyor belt system is installed in the decline which allows water to run freely to the decline barrel where it is pumped to the pump stations.
- Conveyors installed in areas where water accumulates, a pumping system is in place to pump water to the pump stations
Surface-
- The conveyor belt system is installed at an incline which allows water to run freely to be pumped away
- On horizontal conveyor belts the excess water are contained in a sump and pumped away.
Appropriate power supply and braking systems
Power supply:
- The electrical power of 525 volts is supplied to a motor which drives a gearbox
- The gear box is designed with an anti-roll back and can only travel in one direction
- When the power source is cut the drive unit stops and the gear box prevents the conveyor belt from rolling back
- The power supply of a stationary conveyor belt installation is locked -out during repairs, maintenance, routine cleaning and cleaning of spillage;
- The drive unit of the conveyor belt installation can be stopped by any person from any point, along its length where access to the belt is possible by means of pull switches installed along the full length of the conveyor belt system;
- The drive unit of the conveyor belt installation is stopped should the belt break, jam or slip excessively.
Emergency Stop
Every conveyor belt must have an emergency stop switch (pull switch) within reach of any person, which must be capable of working effectively at all times. Under no circumstances must these interlock and safety devices be ineffective. Every belt conveyor system shall be equipped with the following:
- Tripwires along the full length of the belt. The tripwire must be so positioned that it will at all times be accessible to a person facing possible injury by a conveyor belt
- An effective alarm or warning device that can be heard along the full length of the belt and sounded for at least 10 seconds before start-up of the belt, to warn all persons that the belt is about to be started.
- Where two or belts discharge onto one another, sequence interlocking of the belts must be provided which will automatically stop all other conveyors feeding a conveyor that has stopped and also to prevent a conveyor starting until the conveyor onto which it feeds has been started
- Equipped with a lock-out device that will prevent the main drive motor being started whilst persons are working on the belt. Provision must be made for more than one lock to be attached.
- All other equipment or a combination of equipment used for generation, developing, receiving, storing, converting, transforming, transiting or distributing any form of power or energy must be equipped with a lock-out device that will prevent it being put into action inadvertently
Conveyor belt extensions:
Material of which the conveyor belt is made of
- The conveyor belt must have fire resistant properties in order to minimize the risk of fire propagation and igniting gas and dust.
Adequate lightning protection
- Conveyors that are exposed to the weather must be adequately earthed.
Cross over walkways
- In order to prevent persons from being injured while crossing over or under any conveyor belt installation by means of a bridge, the following must apply.
Clearance requirement
- The belt structure must be designed and erected in such a way that the top and bottom clearance between persons and vehicles and the conveyor belt or any other rotating parts are well spaced so that no inadvertent contact can be made. Where it is impractical, effective guards or protection must be provided.
Requirements for handrails and kickboards are as follows: Kick boards
- Kick boards are fitted to elevated walkways and platforms.
- Kick boards are provided to prevent material from falling over the edges of elevated walkways and platforms.
Handrails
- In general handrails are fitted to areas which pose a danger of persons falling over edges. Handrail pipes, stanchions and bend are purchased as standard pre-fabricated equipment from the manufacturers or own mine designed.
- Staircases with two steps are provided with a single handrail and staircases with more than three steps are provided with handrails on either side. In some areas for slipping, non-slipping material are placed at intervals.
- All work elevated areas or platforms above floor level are to be equipped with handrails which will be at least 900mm and not more than 1OOOmm above floor/platform level.
- Vertical supports are provided at intervals of not exceeding 2500mm.
Precautionary measures such as demarcated walkways and guarding around moving parts has been installed to prevent persons from slipping, sliding or falling into conveyor belts.
Cross over walkways has been erected to ensure that persons do not climb over the conveyor belts in order to get to the other side.
All cross over areas are adequately illuminated by means of electrical lights.
Visibility is adequate as all areas where people are working.
In order to prevent persons from being injured whilst doing inspections, maintenance or repairs, the following has been implemented:
- Walkways along and next to the conveyor structures has been demarcated to ensure a safe clearing distance from the belt.
- Staircases with two steps are provided with a single handrail and staircases with more than three steps are provided with handrails on either side. In some areas for slipping, a non-slipping material is placed at intervals. Standard operating procedures has been developed and implemented to make people aware of the dangers involved and the correct methods to use when doing inspections, repairs and maintenance. Training is provided by the mine’s Training Department on all relevant standard operating procedures, which are incorporated in training lesson plans.
Measures implemented to prevent slipping, sliding or falling around and adjacent to conveyor belt installations are:
- Solid and level walkway surfaces (underground and surface)
- Guards preventing persons from falling into drives
- Trip wire switches alongside and around conveyor belt installations
- Emergency stops at drive sections
- Mentis grating floors installed on walkways (non-slip)
INSTALLATION, EXTENSION, DISMANTLING, TRANSPORT AND RE-INSTALLATION
Conveyor belt structure extensions/installation is only done by an approved service provider/contractors. Where applicable the following minimum standards shall be adhered to:
Means of installing the conveyor belt safely
- There are a number of different types of conveyor belt installations on the mine, these will be divided and addressed in two main categories, Standard Installations and Inclined Installations
Standard Installations
Place reels in position
- Place the reel of new belt on suitable trestles and in the desired position.
- Place an empty reel, to reel in the old belt, on suitable trestles and in the desired position, where practically possible. Where it is not possible to roll the old belt, it will have to be cut into manageable pieces.
- Have ready all the tools and equipment required to perform the task.
Lock the feed chute
- Stop the feed to the conveyor and lock the feed chute in such a position so as to prevent any further loading of the belt.
- Allow the conveyor to run until the belt is empty.
- Stop the conveyor and lock out the conveyor.
Link new and old belts
- Release the tension on the old belt by lifting and locking the tensioning device.
- Cut the old belt at the lowest point of the conveyor.
- Join the end of the new belt to the top end of the old belt using clips.
Link new and old belts
Ensure everyone is clear of the belt.
- Unlock and “stop-start” the conveyor drives to pull in the new belt and run out the old belt (in the case of an inclined belt). For a horizontal belt, the old belt will have to be pulled off using the pneumatic winch.
- Stop the conveyor and lock out the drive.
- Cut the old belt loose from the new belt.
Join new belt
- Cut the new belt slightly longer than the correct length.
- Fit belt joining clamps to the two ends of the new belt.
- Pull the new belt ends together using two lever hoists.
- Join the belt according to procedure
- Test the belt according to procedure
Inclined Installations
- Lock out the feed chute and run the conveyor until the belt is empty.
- Run the belt until the section of belt that is to be replaced is at the desired position.
- Lock out the conveyor belt.
- Securely anchor the belt directly above and below the area by means of belt clamps, chain blocks and slings.
- Cut the tail end of the old/damage belt.
- Attach the appropriate size sling about 10 meters below the area where you plan to cut the top end.
- Attach the free end of the sling to a piece of lashing of about 20 meters long.
- Make the cut at the top end of the belt to be removed.
- Attach a piece of lashing longer than the belt length to the new belt by means of a sling as before. Pull this lashing through a snatch block positioned above the top cut of the conveyor belt and attach the free end to the Front end loader which is now facing down the slope.
- Make sure that no person is to take up opposition in the death triangle.
- When the new belt is in the right position secure it at the top by means of clamps
Means of cutting, joining and extending any belt safely
Cutting
- Find the centre line of the belt.
- Draw a perpendicular line to the centre line, where the belt is to be cut.
- Wear appropriate PPE.
- Cut the belt with a Stanley carpet knife using a straight edge rule as a guide.
- Take caution when cutting; position yourself out of line of the cutting stroke.
Joining
- Joining can be done using two methods, mechanical clips or splicing.
Mechanical Clip method
- Cut both ends of the new belt square to the centre line of the conveyor belt
- Fit template on the joint.
- Punch holes in belt ends, with a gum plank positioned below for support.
- Remove template.
- Install clips.
- Tighten belt clips.
- Slack chain lever hoists and remove
- Remove belt jointing clamps
Cold splicing method
- Splicing must be done as per procedure attached. See Splicing Procedure Page 34 “EMS Belting”
- Extending Conveyor Belts
- All the conveyor belts at BML are fixed structures and therefor it is not required to extend any belts.
Means of clamping any belt safely
- Ensure the belt is correctly locked out.
- Release all stored energy where possible.
- Remove the idler brackets where clamping is to be done.
- Place the belt clamp set on top and below the belt, with the ends extending equal lengths on either side of the belt.
- Fasten the ends together with the appropriate size bolts.
- Secure the clamp to the stringer by means of chain blocks, taking up any slack.
Means of pulling any belt safely
- Ensure the Conveyor drive is correctly locked out.
- Clamp the end of the new belt with two clamp plates on the top and bottom of the belt, by means of two 12mm bolts through the clamps.
- Ensure that the chain block is securely mounted in the correct position.
- Attach the chain block to the front end of the clamp plate by means of a sling/shackle.
- The chain block can now be used to pull in the belt in a controlled manner to the desired position.
Chemicals used and associated hazards
- The materials of the belt and any chemicals used during operations and maintenance must be approved by the Environmental Coordinator. A Material Safety Data Sheet must be provided by the supplier as per attached document. Workmen are requested to make use of the correct PPE e.g. clear safety glasses, respirators, gloves, overalls, safety boots etc. when working with hazardous substances.
Means of transporting belts
Conveyor belts must be transported safely and damage to the belt must be prevented. When transporting a belt the following must be considered:
- Avoid rolling the roll of belting where ever possible.
- Make use of the Mobi-lift, belt trailer, trucks or cranes on surface. The belt must also be transported at a slow rate.
- Securely fasten down the roll of conveyor belt when transporting it.
- The end of the belt must be secured to prevent it unrolling during transportation. Underground, transporting of conveyor belts and structures are done by means of material
- cars, utility vehicles and/or a load haul dumper.
Means of testing the conveyor belt installation after installation or extension
- Carefully release the tensioning device used to hold the belt in the desired position to perform the required work or tension the tensioning device on the case where work was performed on a belt where the tension was completely released. Replace all idlers that were removed in order to perform the work. Make sure that all guards that were removed have been replaced!
- Remove all tools, equipment and inform the people that you are about to start the conveyor belt.
- Remove the lock on the lock-out point and cautiously start the conveyor.
- Test run the empty conveyor belt to check alignment.
- Retrain the belt if necessary.
- Unlock the feed chute and slowly feed material onto the new running belt while checking for malfunctioning.
- Retrain the belt if necessary and slowly increase the feed to the belt until full loading condition.
- When satisfied that the new belt is running true, officially release it for operation.
Means of supporting the roll of belting on trestles
When supporting a roll of belting on trestles, ensure the following:
- Use only a round bar/pipe for the axle, which is adequate to take the load of the roll of belting.
- The hole in the center of the roll of conveyor belt must be round. If required, end plates are to be made up and welded onto the roll by a boilermaker. These plates must have circular holes cut in them for the axle.
- The axle bar must be located at one or both ends to prevent the axle from moving sideways off the support.
- The trestle must be correctly and solidly positioned and before the roll is placed on it to.
- The belt must be unreeled in a controlled manner to prevent the roll and trestle from falling over.
- The trestle must hold the roll securely and prevent it from jumping off.
Maintenance And Repairs
The responsible Supervisor will appoint competent persons to carry out maintenance, inspections and over inspections on conveyor belt systems.
Daily inspections done by the operator include components such as:
- Visually inspect all belt drives and pulleys.
- Check scrapers and belt cleaners for correct operation
- Check conveyor belt for spillage of material onto the return belt where it can lodge between the belt and the pulleys.
- Check that the illumination alongside the belt is adequate
- Every conveyor belt system shall be provided with lights of sufficient intensity, to enable the operator to identify any dangerous conditions and to stop the belt in time to correct the situation.
- Ensure the conveyor belt alignment is correct.
Daily inspections done by the operator include components such as:
- Check for damage or worn spots on the belt
- Inspect the take-up pulley
- Ensure that all safety guards and nip guards are secured and in position
- Ensure that stop switches and trip wires are in place
- Ensure that the pre-start alarm is functional.
- Check for idlers not turning.
- Check condition of decking plates where applicable. Material build-up on decking plate must be removed by operating staff. Worn decking plates must be reported to the responsible Artisan.
- Check condition of rubber skirting
Daily inspections done by the operator include components such as:
A competent person (conveyor belt attendant or operator), should patrol the entire length of the conveyor belt installation at least once per shift to examine the following: (No Belt attendants on the plant, the belt get started by the plant operator operating the crushing plant, Ball Mill. His task is not just focused on the belt, the belt gets inspected on the daily checklist by the dayshift plant operator and defects are reported to the Artisan, the log sheet gets signed on a daily basis.) Artisans inspect all plant machines on a daily basis no extra checklists for these inspections.
- Check the alignment of the conveyor belt.
- Ensure that there are no jammed pulleys.
- Ensure that there is no accumulation of fines (dirt) on rollers.
- Ensure that there is no accumulation offines (dirt) underneath the conveyor belt.
- Check that drive motors are not overheating.
- Visually check the effectiveness of all safety devices such as emergency stops, pull wires, guards and nip guards etc.
Monthly inspections include the following:
- Check condition of all pulleys and belt drive assemblies.
- Check condition of belt scrapers and belt cleaning devices.
- Lubricate bearings and gearboxes.
- Check condition and placement of guards, angle of nip guards and handrails.
- Check illumination along the entire belt.
- Check the take-up pulley and limit where applicable
- Ensure that emergency stop buttons are working.
- Ensure that trip wire systems are in place and working.
- Ensure that the start-up alarm is functioning and the timing is not less than 10 sec
- Ensure that electrical interlocking circuits are working.
- Ensure that all lockout facilities are functioning.
- Check condition of belt tensioners.
- Check that the belt alignment and tension is correct.
- Ensure that all fire fighting equipment is available and ready for use.
Guarding
- All conveyor guarding shall be as per the “Memorandum on the guarding of Belt conveyors” (Annexure “A”) issued by the Department of Minerals and Resources a copy of which shall be kept by the responsible Engineer.
- Nip guards comply with the standards.
- The dust at Barberton Mines has been classified as a nuisance and dust can be harmful to the health and safety of personnel. Periodic dust samples are taken and analysed to ensure that Employees are not exposed and at risk to dust. Record can be obtained from the Environmental Department.
- Suitable symbolic signs are visible in areas where dust is a concern and any person working in or entering such a dusty environment must wear a suitable dust mask or respirator.
Noise
- Any person working in or entering an environment that has a noise level above 85 decibels must wear hearing protection.
- Appropriate symbolic signs are installed in areas where the noise level is above 85 decibels to warn employees of the hazard.
Stored Energy
- The safe working procedure for Stored Energy “Standard Operating Procedure” must be adhered to when a conveyor belt is under tension. See figures 1 and 2 below for a conveyor belt with stored energy and one where stored energy has been released to remove an object.
Overriding of Safety Systems
- Emergency stop switches (pull wire switches) along the entire length of the conveyor belt, around the tail and head pulleys and at the take up.
- Start-up warning alarms to be heard at any place along the conveyor belt.
- Slip protection devices. (where applicable) Sequence interlocking devices. (where applicable)
- Guards and nip point guards.
Lockable facility.
Training
- People may not operate conveyor belts unless they have been trained, tested and found competent to do so. Operators must be appointed in writing by the relevant Supervisor.
- Conveyor belt systems shall comply with the following general requirements before being put into operation:
–Access platforms – All permanent conveyor belts elevated or inclined locations are to be provided with access platforms or walkways on one or both sides. Small conveyors at screening plants are excluded. These platforms are to have handrails and non-slip flooring particularly on inclines.
–Side clearing – Conveyors must have adequate side clearance for travelling and space for maintenance and repair purposes.
–Scrapers – Need to be installed to clean return belts.
–Tensioning system – All belts need to have a tensioning system. Incline conveyors are to have gravity or winch tensioning systems. All tensioning devices will not move when repairs, routine cleaning, cleaning of spillage, maintenance at belt tensioning devise or belt splicing is carried out.
Operation
- The belt must not be overloaded.
- The whole conveyor belt system must be cleaned as it becomes necessary.
FIRE PREVENTION
Measures to prevent fires
1. Damaged idler pulleys.
- Inspection and over inspection are done and damaged pulleys are replaced
2. Belt slipping at head pulley.
- Anti-slip device installed on all belts (Please verify)
3. Poor belt tracking or misalignment resulting in belts rubbing against framework.
- Misaligned switches on new installations
- Belt operator must stop and report belt misalignment
4. Collapsed bearing in pulleys.
- Daily and weekly maintenance and inspection are done
5. Excessive spillage interfering with free movement of belts.
- Belt operators to report spillage
- Scrapers are installed to reduce spillage
6. Poorly adjusted or worn scrapers
- Daily and weekly Inspection and maintenance are done.
Belt Selection.
- The design and the selection criteria for the conveyor belt installations is in accordance with fire-retardant belts which comply with “SANS 971-2003. Addition 3”.
- Such conveyor belt systems are installed in well ventilated areas. No combustible materials are to be stored near any conveyor belt.
Measures to Detect Fires
- CO monitors are installed at strategic positions to detect fires underground. Belt operators on surface and underground, must contact control room as soon as a fire is detected.
Measure to Combat Fires. Underground
- Suitable and adequate means for extinguishing fires shall be available for immediate use along every conveyor belt and at every driving head, tail ends and drives of every conveyor belt, as well as at the intake air side of the conveyor belt where it is installed in a confined space, i,e Underground or in buildings.
- Fire extinguishers to be installed at intervals not more than 50m along the length of the conveyor belt system.
- Life sustaining Refuge Bay must be strategically placed in consultation with the Occupational Hygienist
- If the installation of a water spray system is warranted by a risk assessment the minimum size of the supply column shall be 25 mm.
- Approved 9kg fire extinguishers are placed every 50m along the belt and 9kg fire extinguishers at the head and tail pulleys.
- Life sustaining Refuge bays must be strategically placed in consultation with the Occupational Hygienist, to prevent persons from being exposed to chemicals released when a conveyor belt installation is ignited
Measure to Combat Fires. Surface
- Fire hydrants or
- Water sprays or
- Approved 9kg fire extinguishers at the head and tail pulleys.
Measures to be taken in case of a fire
Underground
- Stop the belt
- Don self-contained self-rescue pack if exposed to smoke or fumes.
- Contact the control room.
- Open fire suppression valves.
- Warn other operators on the return air side of the fire.
- Extinguish fire where possible.
- Evacuate to the nearest refuge bay.
- Refuge bay procedure to be followed.
Surface.
- Evacuate to the nearest assembly point.