Thunder Basin
- Owner: Arch Coal (Formerly Thunder Basin Coal Company)
- Project: Coal Plant Expansion
- Location: Black Thunder Mine, Wright, Wyoming
- Scope: Engineering, Procurement and Construction Management
Project Background
Complete project management, detailed engineering, procurement, and construction management services were provided by Roberts & Schaefer Company to add two ROM, semi–mobile near pit crushing stations and an overland conveying system to existing Black Thunder Mine.
The Black Thunder Mine is the largest surface coal mining operation in North America, producing 30 million tons per year. The facility includes two semi–mobile near–pit crushing units, each arranged with 500 ton capacity dump hoppers fitted with passive dust control systems to accommodate 340 ton haul trucks. Drag chain type feeders are fitted to the dump hoppers and reclaim the coal, each feeding a crusher unit designed to crush 2,600 TPH of –60” x 0 ROM coal, producing a 2” x 0 product.
Coal is conveyed from each crushing unit to a permanent 72” wide overland conveyor that conveys 5,200 TPH of crushed coal at 1,000 FPM, a distance of 11,700 and 140 lift to an existing slot and silo storage area. The overland conveyor is powered by four 1,100 HP drives, arranged with three drives at a forward location and one drive at a tail location. Control systems allow equal drive sharing of the load during all starting, running and stopping conditions. An intricate static and dynamic design analysis of the overland conveyor was completed to provide for all the design considerations over the operating range and conditions of the conveyor. A three stage sample station is included to sample crush coal to ASTM standards.
Ancillary equipment includes: dust collection at the crushers, conveyor transfer points and sample station with provision to add dust collection at the primary dump station; modifications to existing facilities and conveyors to accommodate the new system; and all electrical work including programmable logic control with interfaces into an existing control network, and power distribution starting from a remote 69 kV grid.
The passive dust hood design innovation created by Roberts & Schaefer Company, prevents coal dust from ”belching” during dumping. The design eliminates the need for conventional dust collection and its associated capital and operating costs. The hood is designed large enough to channel the displaced air through a labyrinth of hanging conveyor belting which causes impingement of the dust particles. The state of Wyoming has accepted this design, and encourages its use.