Objective:
- Restore the pug mill to original operational capacity by replacing worn and heavily
corroded components with new components that are resistant to corrosion in
abusive environments. - Improve the efficiency of the system by eliminating carryback material that causes
accelerated wear and requires excessive downtime to clean up.
Challenge:
Salt processing is one of the most abusive applications a material handling system has to endure, and without
proper design or components, a pug mill can experience rapid failure due to salt buildup and component corrosion.
Although this pug mill was only 5 years old when it was brought to us, almost all of the conveyor components
were either seized, or rusted through, rendering it useless to the operator. The guards were broken or missing,
the take-ups were inoperable, all pulley and pug mill bearings were in need of replacement, as well as all pulleys
and idlers. The conveyor supports were rusted away, both conveyor belts were mechanically spliced, and the
belts were shredded and heavily worn due to a poor chute discharge design. The feed hopper experienced constant
build up in the corners, leading to serious abrasion damage to the belt.
In addition, we found that the entire hydraulic system had to be replaced due to the corrosion of the fittings,
valves, and hydraulic cylinders, hydraulic pump, motor, hoses, and tank. The entire system was in need
of major overhaul and improvement, and the clients needed it to be fully operational in 30 days.
Solution:
In order to meet the tight deadline, the pug mill was transported to ASGCO®’s headquarters, where a team
of engineers and technicians performed a thorough head to tail inspection of the system, and outlined every
step to be taken to restore the system and ensure that the abusive salt environment does not cripple the
operation moving forward.
All guards were removed so that they could be repaired or be replaced. The conveyor take-ups were replaced
with stainless steel telescopic take-ups. All pug mill and conveyor bearings were replaced and equipped
with new, individual grease lines. The conveyor’s wing tail pulleys were replaced with Clean Flight pulleys
to eliminate the salt build-up that was occurring, and to evacuate any material that may find its way onto the
return side of the belt. To resist corrosion, all conveyor idlers were replaced with poly-coated rollers with
hot-dipped galvanized frames. New conveyor supports were custom fabricated to properly support the conveyor
frame in the load zone. New belts were installed with hot vulcanized splices instead of the problematic
mechanical splices.
The exit of the feed hopper was modified so that the salt will not build up in the corners, which had previously
resulted in severe abrasion to the belt covers. The adjustable gate was repaired so that it could be adjusted to
properly trim the flow from the feed hopper. ASGCO® Skalper® primary belt cleaners were installed on each
conveyor to eliminate the carry back issues that were present. The chute wall was trimmed to provide the
proper gap from the belt and to have a continuous relief angle so that material would not become gouged into
the belt cover. ASGCO® Dura-Seal® skirting was installed to eliminate spillage in the load zones. Protective
curtains were fabricated and installed to prevent corrosive material from being spilled onto the conveyor,
hydraulic system, and framework of the system when the feed hopper is filled with a loader. These curtains were
designed to be easily installed and removed for inspection and maintenance.
Results:
Every aspect of this pug mill will now be far better equipped to handle the incredibly harsh environment in
which it operates. The system was retrofitted to resist corrosion of key components and more, importantly,
reduce harmful spillage and carryback that caused major problems. With effective belt cleaners,
vulcanized splices, corrosion resistant idlers and take-ups, adequate guarding, a completely refurbished
hydraulic system, and protective curtains, this pug mill is ready to be put back into service well within the
30-day deadline.
The customer was very satisfied with the refurbishment of this key piece of their operation and has scheduled
repairs and service to additional pug mills in the near future.
