Raw coal screened and graded by size prior to washing, small unwashed material removed to store.
|Taff Merthyr Colliery preliminary coal grading|
Coal is received into the preliminary coal grading plant on AA209, drops onto AA210 through a hopper and passes through the raw coal screen. Here, material 38-125mm is separated and chuted to AA21 1 near its terminus. Material under 38mm is fed along AFC203 into two rotating probability (ro-pro) screens AS201 and AS202 (plate 5) or overflows by chute onto the beginning of AA21 1. The ro-pro screens sort material by size through radial bars according to their speed of rotation. Two sizes are output: 6-38mm, which passes by chute to AA21 1, and the 'dry fines', under 6mm, which fall to AA212, AA313 and thence into the raw coal blender for storage. AA212 has a sampler installed which enables small quantities of coal to be removed periodically for analysis. All material on AA211 is tipped into a hopper from where it is conveyed by AA301, via a transfer house and AA303 to the washbox in the raw coal treatment plant.
|Taff Merthyr Colliery preliminary coal grading diagram|
1. Raising coal and stone extraction
2. Preliminary coal grading
3. Raw coal treatment (washing)
4. Fines separation
5. Preparation of treated coal for market
6. Shale disposal and reclamation of surface water
7. Identification of principal surface features
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