We invite your offer for modernization of an existing salt handling system. We give here below the details of the existing system and suggest a modernized system which you may refine/modify and send us your offer.

Existing system:

Salt is a raw material in the manufacturing process of caustic soda. GRASIM CHEMICAL DIVISION, Nagda, India has two Caustic Soda Plants adjacent to each other in same location.

Salt is mostly received in railway wagons (either open type or closed type). Around 58/40 wagons come in a rake. Salt is packed in 75 kgs HDPE bags. Each wagon is 58 MT capacity holding 780 bags approximately and from this one rake capacity is 3300 MT and holding 44000 bags approximately.

Railways provided single rake consignment consisting of 58 wagons/40 wagons. There are two railway sidings inside the plant. Whenever a consignment of one rake is received they are split into two and placed on both the tracks with an interval of one hour to one and half hour. Railways allow 9 hours for unloading the bags from wagons of one full rake and demurrage is applicable in the event the unloading time is more than 9 hours from the time of placement of rake.

Approximately 100 to 120 workmen, depending upon the size of rake, are employed to unload the rake. Bags are removed by opening the door and slitting 2 or 3 bags at the entrance for entry of people into the wagons. The salt from the slit bags is to be collected manually at the bottom of each wagon. Even in the open wagon, this procedure has to be adopted since people are not allowed to stand on the top due to traction line above.

Bags are unloaded manually from the wagon and stacked on platform (I, II & III) adjacent to tracks. Once the bags are unloaded on the platform, the empty rake is taken out. Presently there are two-belt conveyors one of 50 TPH and other is 100 TPH. Hoppers are located over the belt conveyor; bags are manually taken to nearest hopper and slit open, and emptied to the hopper manually. From the hopper, salt flows to respective conveyor & then to storage godown or consuming point.

A small portion of salt (about 10%) is received as loose salt in trucks and trucks are unloaded manually over grating fixed on top of conveyor. This salt goes to storage or consuming point.

From godown, salt is sent to consuming point through pay loader and bucket elevator. Some time salt bags from the end of platform are transferred to fixed grating at truck unloader point via tractor trolley. And slitting of bags done manually.

Presently our consumption of salt is 800 MT per day average. And for that 110 workers are employed daily.

Proposed system (which can be refined or modified):

Common salt is received in 75 kgs bags in rail wagons. The wagons either open type or closed type each total 780 bags approximately. One rake contains either 58 wagons or 40 wagons. The railway rake is split into two and placed on each rake along the platform.

Bags are unloaded manually from the wagon on to an inclined roller conveyor (Mechanical), which by its self-weight and slope discharge to new belt conveyors (BC 101A& B). The rake of 58 wagons need is be emptied in 7 Hrs. The no of roller conveyor required would be 12 no. Which can be moved to any wagon by pushing (the conveyor are kept on rail). The capacity of BC101 A/B each shall be 225 TPH.

The bags from this conveyor are sent to delumpers (3 delumpers to each conveyor) with automatic arrangement of diverting by to each delumper. The purpose of delumpers is to break any lump in the salt to crystal and the design of delumpers is such that it enters this requirement.

Bags from delumpers are then sent to a slitting machine where bags are slit through BC 101 A1, A2, A3, B1, B2 & B3 and than salt is taken out. The empty bags (torn) are automatically discharged. The system should include baling of empty bags from disposal. The slitting machine should be suitably designed so that the bag is fully emptied and no bag particles go with the salt.

The loose salt from slitting machines (6 nos.) is discharged on to a 425 TPH belt conveyor (BC102) and then through lump rotary crusher it convey to a inclined belt conveyor (BC 103 & interconnecting silo belt +BC 104) to any one of two silos of 1100MT capacity each and once these silos are filled through conveyor BC 105 to open salt godown. The entire above conveyor will have capacity of 425 TPH.

Chutes provided at different points of conveyor BC 105 discharge uniformly the salt in the open godown.

Material from silos is then conveyed through conveyors BC 106 & BC 107 through a salt feeder at the desired flow rate, which is controllable & variable between 30 TPH to 100 TPH to the existing conveyor BC 501.

Material from open salt godown is to be handled through pay loaders and to be discharged to the conveyor BC 102 or BC 103 through a hopper and salt crusher. Salt crusher is required to break any lumps that formed due to storage of salt in the open godown.

Some quantity of salt is received in truck (around 10 truck per day), which needs to be discharged on conveyor BC 102 or BC 103 by installing a truck tripper and suitable conveyor. The capacity shall be designed suitably.

The scope shall include the design of silos preferably in RCC with suitable coating inside for corrosion / erosion protection as well as arrangement for delumping / removal of choking.

The main thrust area for the design of the system is minimizing the manpower requirement and dependability on unskilled labors.

There are huge no of bags (44000) are received in a rake and time for unloading is only 8 hours, so that system will be capable to synchronize between unloading, diverting, slitting process throughout the unloading time. The system should include interlocks, personal protection and tripping device for mal operation.

We expect the performance of machines are proven and prefer demonstration of critical equipments like delumpers, slitter machine and salt crusher. As well as reliability of silo structure.



It is suggested that you may visit us with prior intimation so that you can understand the present system as well as our proposed system to enable you to submit a system, which is proven and feasible.

Ms. Disha Nasit

GRASIM CHEMICAL DIVISION

ADITYA BIRLA GROUP

+91-9826795893 ■