All mines go through shutdowns for maintenance, repairs and upgrades. The shorter the shutdown period, the sooner the plant can get back online and into full productivity. Months of careful planning are essential to ensure that the right people, tools, parts and time are properly scheduled and available. The goal is always to bring the shutdown project to a smooth, safe and quick completion.
In April 2016, the FLSmidth services team played a crucial role during a major scheduled shutdown of the Peñasquito plant in Zacatecas, Mexico.
Owned and operated by Goldcorp—one of FLSmidth’s key strategic customers—Peñasquito is the largest open-pit gold operation in the Americas and is considered the second largest in the world, employing more than 3,000 people onsite. The plant treats 140,000 tons of hauled ore per day and, besides processing gold, also produces silver and zinc.
With nearby offices in Monterrey, Mexico, the local FLSmidth team has often been called upon for its technical experience, capacity and ability to organize turnkey services for the Peñasquito site.
For this recent major shutdown—carried out from April 12 through April 23, 2016—FLSmidth staff were entrusted with two service contracts, considered as critical items within the whole shutdown program: overhaul of the 60x113” gyratory crusher with a 90-degree turn of the top shell; and replacement of the gear and two pinions of the 24x37.5’ ball mill.
All services were developed under the management and supervision of FLSmidth customer services personnel located in Mexico, with support from field works and service engineers, and technical assistance coming from FLSmidth’s Chile office. Altogether, FLSmidth supplied 100 field staff adding up more than 1,800 man/hours and achieving an excellent safety record with no accidents recorded. Additionally, FLSmidth subcontracted two local companies to provide labor services—one for each of the two projects.
The projects were successfully and simultaneously carried out and involved months of advance planning, methodical analysis of risks and procedures, a number of site visits, frequent communication, and fine-tuned and thorough coordination with the customer.
Overhaul of the crusher
This project included the disassembly of the gyratory crusher (FLSmidth’s Traylor® model NT 60x113”) so the crusher’s main parts could be replaced. The top shell was turned 90 degrees to guide ore load and obtain a more suitable spider wear.
Timing for the overhaul and crusher parts replacement was estimated at two days for preliminary tasks and 10 days for work execution with 26 people participating as subcontracted direct labor. The efforts were developed in two 12-hour shifts to cover the full 24 hours per day.
- Top shell turn
- Concaves replacement
- Replacement of eccentric assembly and countershaft
- Outer bushing replacement
- Hydroset replacement
- Bottom piston replacement
- Eccentric wearing ring replacement
- Main shaft replacement
Gear and pinion replacement
This maintenance project had originally been assigned a year ago, but due to several operational situations in the plant, the decision was postponed until April 2016.
The specific reason for the decision to replace the gear and pinions on the ball mill was based on observing three broken teeth and subsequent peeling of material. During the year, careful monitoring was conducted of the gear and pinion’s damaged components and their performance. If any sudden decision had been made to execute the replacement service under turnkey modality, the FLSmidth service team was prepared well in advance to quickly take action.
For the shutdown, a 56-person work team was brought in for subcontracted direct labor. FLSmidth service engineers specialized in mechanical transmission replacement; service engineers specialized in critical fasteners; and skilled labor oversaw scaffold assembly and disassembly. In total, 64 FLSmidth personnel worked on this ball mill project.
Specifically, this project included:
- Replacement of gear supplied by Hoffman (structural gear)
- Replacement of two pinion/clutch gears
- Alignment of two drive trains
- Startup and 48-hour startup technical assistance
Due to the 88-ton weight of the Hoffman gear, precise calculations had to be made and careful lifting maneuvers were designed several months ahead of the project's undertaking. The FLSmidth field service team decided to separate the gear into four segments of 22 tons each which became more manageable to move, lift and place.
FLSmidth supplied all lifting maneuvers up to five tons. For heavier items, the lifting maneuvers were undertaken by the customer with assistance from FLSmidth to purchase the suitable and correct elements accordingly. A 600-ton-capacity crane was provided and operated by the customer for the gear and pinions assembly.
The project timing was set at 10 days for preparation which included transportation of segments, tools and lifting elements. Another 12 days were scheduled for work execution and two days were allotted for supervision after the equipment started up.
To our customer’s satisfaction, the execution part of the project was completed in only 10 days—two days earlier than previously planned. Even more significantly, no incidents, accidents or any contingencies occurred during the replacement activities, which was gratifying for all parties.
With both projects being performed simultaneously, a significant amount of coordination took place to ensure on-time delivery of parts and service—and with safety always being at the forefront. Everything was completed 48 hours ahead of the planned deadline, which was originally committed to in the plant shutdown program, with no accidents or deviations from pre-established processes.
"The key to the success of both projects stems largely from the efforts made during the coordination stages, with all activities prepared carefully prior to work execution," said Per Bech Badstue, FLSmidth Customer Services Sales Manager, Mexico and Central America. "We learned a lot of positive lessons in regard to collaboration, quality work, safety and efficiency in the handling of contracted labor, intercompany resources and working closely with Peñasquito site management."
CONTACT: Per Bech Badstu