Concrete Industry General diagram from the extraction to the Despatch The presentation below are recommendation to improve safety processes based on current installations. The list is non-exhaustive and is designed to help you bringing new ideas into your company specific process.
QUARRY After extraction, raw materials (limestone, marls, granits‌) are first crushed and then moved onto an initial blending stage. We have to make sure that, while maintenance done at this stage, all moving machines are stopped and secured. Due to a very dusty environment, we would suggest a NSOP15 with dust cover on the motor control and SOL85 (or CK for chain) with dust cover and hermetic keys.
NSOP15
KEY
SOL85
SAND COMPARTMENTS
When a truck comes to unload sand, the machine has to be locked off to avoid any risks of accidents by controlling all access gates and switching off the electrical circuit to the machine thanks to a rotary lock 2O/2C. Because of the dusty environment and being implemented outside, the rotary shall be in an enclosure.
RTK
As for the access gate locks, we shall attach the cable strechers of the area directly to the latch of the lock. To release the strecher, insert the key and lock it into the lock, you can now open the latch, hence the strecher.
S0L85
CONVEYERS & ELEVATORS When raw materials are ready to be processed, they are moved onto the production area through conveyors and elevators. In case of maintenance in those “moving� equipmnent, a safety process shall be implemented to avoid injuries. We recommend to link the whole power supply to the access gates. A first bolt lock shall be installed on the power circuit with a key normally trapped. Switching it off will free that key. It is now possible to enter the dangerous area of the lower gate of bucket elevator through a access lock with personal key. Should you you have several access gates, an exchange box is recommended:
SKIPS In the skip areas, access must be granted once and only when : - Operator has turned off the switch thanks to a bolt lock locking the switch in off position. - Operator has locked the skip’s anti-fall protection. This can be locked with a standard bolt lock NX0P15 Both conditions are fulfilled, opertor retains 2 keys to open the skip doors where a 3-entry lock is in place (2 keys of conditions above are inserted in and one key is taken out as a personal key that operator must take with him to go inside to avoid trapping himself into the skip.
CRUSHERS Crushers are used to break large stones extracted from the quarry into smaller pieces.
The main risk here is to enter the machine (for example, a rock is blocking a blade) while in operation. This can be lifethreatening. Our safety recommendation is simply enough, easy to implement, avoid any cabling all and around the crusher and links it to the power feeder: A bolt lock (ref NS0P15) is normally trapped in lock while crusher is in operation. Turning the key and extending the bolt will lock the switch in off position. Alternatively, you can use an electro-mechanical lock with tempo and in an enclosure (PERTK), That key free is transferred to a chain key or latch access lock (S0LCK or S0L85) to open the door without any sense of danger.
NS0P15
or
PERTK
S0LCK
MIXERS NX0P15
Accessing the mixers in a batching plant for cleaning or maintenance operations, will follow more or less the same safety process as crushers (see previous page): Controlling the power supply of the mixer making sure it is unconditionnally off before going into the door or manhole gate. Cutting off the power through a bolt lock (NX0P15) to release a key and transfer it to the access lock. In case of multiple access doors, the key from the NX0P15 will first go to an exchange box (TMEC) to release a certain amount of keys.
TMEC
NX0LCK
Electrostatic Precipitator
‌.will usually have the typical safety logic as described in the following pages:
Unit 1
AND
Unit 2
SILOS
Silos are a storage place for aggregates, cements, mixtures‌etc‌ There is more a risk of damaging the goods stored due to an error in unloading a truck into the wrong silo. For example, a truck coming in with sand will go to unload it in silo for marls. An operator can also get injured while accessing an empty silo from a upper door and fall all the way through (rare but plausible). To secure and and offer a 0-error in unloading into silos, we recommend the connection hose (RGV) fitted with a bolt lock. That RGVis installed at the tuve end of the silos and can only be connected to the truck fitting with the key consigned for that silo. The consigned is usually given when the truck arrived at warehouse. It is either managed manually by the warehouse supervisor or through the SKM (Smart Key Manager) in case of large amount of silos and raw materials. The SKM works through a web interface and RfiD.
Or