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The Washplant Feed Conveyor discharges to a swge bin, with water added at the transfer point. Feeders draw from
<br />the swge bin to feed the coal to a series of screens, heavy-media cyclones (using a slurry of magnetite and water to
<br />• separate the coal from the heavier refuse material), classifying cyclones, wash screens, and centrifuges, producing
<br />both a coarse and fine coal product, which aze combined and discharge to the Overland Conveyor. Coal refuse is
<br />sepazated from the coal stream in the cyclones, with the coarse refuse passing over screens to drain and then to the
<br />Coal Refuse Conveyor, and the fine refuse being transferred to the Thickener to reduce water content. The
<br />Washplant will require approximately 350 gpm of make-up water, with approximately 100 gpm coming from water
<br />recycled from the process, and losses of approximately 190 gpm to the coal product stream, 35 gpm to the coarse
<br />refuse stream, and 25 gpm lost to the fine refuse stream (the remainder of the water from the fine refuse stream is
<br />recovered and recycled to the Mine water supply system. The coal prepazation circuit also includes, the magnetite
<br />recovery and recycling system, and a water filtration and recycle system, to minimize water use requirements. The
<br />coal preparation equipment, along with associated chute-work, and control and monitoring systems, aze housed in
<br />the Washplant Building, a steel frame building with steel siding and roof (55 x 125 x 80 feet high), which sets
<br />directly over the Overland Conveyor. The building sets on a reinforced concrete slab (58 x 128 x 1 foot thick).
<br />The Coal Refuse Conveyor (48-inch belt w/500 tph capacity), transfers coazse coal refuse from the Washplant to a
<br />Refuse Bin. The Refuse Bin is used to load trucks, which haul the coal refuse material to the existing pemtitted
<br />Coal Refuse Disposal azea. The Coal Refuse Conveyor is designed to handle current requirements of 500 tph, as
<br />well as possible futwe system expansion. The Refuse Conveyor is supported by two steel support bents, and
<br />utilizes the typical conveyor construction. The conveyor bents set on reinforced concrete caissons, as previously
<br />described. The Refuse Bin is a steel frame building (30 x 30 x 50 feet high) with steel siding and roof which
<br />supports a 200-ton pre-fabricated steel swge bin and contains minor chute-work and a dust collection system. The
<br />Refuse Bin sets on a reinforced concrete slab floor.
<br />The Washplant II Thickener, which is used to partially dewater the fine coal refuse, is a reinforced concrete tank
<br />approximately 50 feet in diameter, and 12 feet high. A flocculating agent is introduced into the tank, and a high-
<br />efficiency underflow system mixes the flocculant with the fine refuse stream, causing the refuse particles to
<br />• agglomerate and settle from suspension. The decant water dischazges through a filter and is recycled to the
<br />Washplant. The fine refuse slurry discharges through an 1,800-foot, 6-inch diameter dischazge line connecting to
<br />an 8-inch drop-borehole and underground piping system, which carries the slurry to an area of sealed underground
<br />mine workings. Underground, water decants from the fine refuse slurry and flows downgradient to a sump where a
<br />pumping system is used to recover and recycle the water.
<br />When the new Washplant and Thickener were installed, a new Thickener Overflow Sump was constructed to
<br />contain minor amounts of washdown water and to serve as a temporary catch basin for the contents of the
<br />Thickener, if required for maintenance or under upset conditions. The Thickener Overflow Sump is located
<br />between the Refuse Conveyor and Sedimentation Pond D. The Thickener Sump is partially incised, incorporates a
<br />compacted clay liner to minimize seepage, and is sized to fully contain the contents of the Washplant II Thickener
<br />(150,000 gallons) plus minor amounts of washdown water and incident precipitation for the design event.
<br />Impoundment design, operation, and maintenance information for the Thickener is provided in Exhibit 8X. Given
<br />that the potential for both the Washplant I and Washplant II Thickeners to experience an upset or require
<br />maintenance at the same time is negligible, with completion of the Washplant II Thickener Overflow Sump, the
<br />Washplant I Thickener Overflow Sump was decommissioned, filled-in and replaced by a dischazge pipe from the
<br />Washplant I Thickener to the new Washplant II Thickener Overflow Sump. As an incised and closed basin (ie: no
<br />outlet) the only potential inputs to the Sump are thickener overflow, washdown water, or minor incident
<br />precipitation, which are subsequently pumped back into the system by a portable floating pump installation. The fl-
<br />inch thickener overflow line has been extended to the new Thickener Overflow Sump (4,800 feet), allowing
<br />overflow from either thickener to be controlled by valves and routed to the Sump. Water level in the Sump is
<br />monitored and managed as part of the ongoing Washplant operations.
<br />Given the power and system control requirements for the Washplant, an associated Motor Control Center
<br />•(MCC)/Office Building was constructed immediately adjacent to the Washplant. The MCC/Office Building houses
<br />electrical, control, and monitoring equipment for the Washplant and includes office space for Mine Surface
<br />TR07-60 2.05-32.3 05/01/07
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