Screens

The plant on the pit bank where run-of-mine coal was graded dry, by size, before sale — Gresley's 1883 glossary calls it 'a mechanical apparatus (a sort of gridiron) for separating small from large coals'. Bars set a fixed distance apart, or steel plates punched with holes, let the small through and carried the large on, and what passed over and what fell through were sold as different products at different prices.

Historical usage

Screens were the most conspicuous thing on a colliery surface after the headgear, and the Lists of Mines and the National Coal Board's own reports count them like plant: this archive's Riddochhill record has two screens and a Baum washer in 1948, and its Glentaggart record one screen for dry coal and no washing at all. Where a colliery had no washery the screens were the whole of its coal preparation. They also shaped the working day above ground. The screen picking belts were where women, boys and injured or elderly men worked, sorting stone and dirt out of the coal by hand as it went past, and the sidings and shunting around them killed people regularly: this archive's Carronhall record has Robert Galloway, a shunter, fatally crushed between waggons on his way to the screens in 1909, and its Riddochhill record has Peter Aitken junior, aged fourteen, crushed in 1904 in a dross waggon moving from one screen to another with four inches of clearance above him.

How it worked

Coal came up the shaft in tubs, was tipped, and ran over a screen: a grid of iron bars or a punched steel plate, often shaken or inclined, sometimes several in sequence with the openings getting larger. Everything that fell through one screen and stayed on top of the next was one size of coal. Gresley records the bars of a screen varying between a quarter of an inch and two and a half inches apart, and names the products by where they ended up — dross and slack passing through the finest, and 'lumps' being the largest coal that did pass over. Picking belts alongside took out the stone and pyrites by hand. Screening is dry work and stops at grading. Washing is a separate and later stage that uses water to separate coal from stone by density, and a colliery could have screens and no washery, which many did.

Why it was used

Because coal was not one product. House coal, steam coal, manufacturing coal, gas coal and coking coal were sold in different sizes to different buyers at different prices, and a colliery that tipped its output into one heap threw money away. Screening was the cheapest way to turn a shaft's worth of mixed coal into a saleable range of sizes, and it needed no water, no chemicals and very little power.

Risks & limitations

Screening sorts by size and nothing else: it cannot separate coal from stone of the same size, which is what washing is for, so a dirty seam screened but not washed went out dirty. The screens themselves were noisy, dusty and dangerous — the surface accident reports in this archive are full of the sidings that fed them — and the dust raised at the picking belts is part of the reason colliery surface work was not the safe alternative to going underground that it looks like.

Regional variation

General British usage. Gresley notes a second and unrelated sense, still current in the North East in the twentieth century, of a screen as a cloth brattice or curtain hung across an underground road to direct the ventilation, which the North Staffordshire glossary records as also being called traps. That sense has nothing to do with the pit bank and is the reason this record is titled in the plural: on a colliery, 'the screens' is the place.

Related terminology

Baum Washer

Mines associated with this term

5 examples chosen from 8 linked records — the term page is not an index.

• Cocking Quarry — West Sussex (well documented example)
  Named twice in this record, first in the current condition: “…are not open to the public. The south battery of lime kilns and the screening plant survive, and the works are a well-known subject for industrial…”
• Grove Colliery — Staffordshire (well documented example)
  Named twice in this record, first in the summary: “…which it continued for two more decades purely as a washing and screening plant for a neighbouring colliery.”
• McLaren Colliery — Caerphilly (well documented example)
  Named twice in this record, first in the history: “…collection shows the works as part of that company, with the screen plant, a bank of coke ovens and rows of 'Tredegar' wagons lined up…”
• Newstead Colliery — Nottinghamshire (well documented example)
  Named twice in this record, first in the history: “…was generated to light the pit bottom, the pithead and the screens. Success brought demand for more men, and the owners built new…”
• Nostell Colliery — West Yorkshire (well documented example)
  The colliery of 1860 was built with a coal screening plant as well as winding and pumping engines and a mechanical ventilating fan.

Sources

1. (primary) A Glossary of Terms Used in Coal Mining, by William S. Gresley, 1883 — Internet Archive
2. (secondary) Glossary of mining terms — North Staffordshire Miners' Group, Apedale Heritage Centre — North Staffordshire Miners' Group

Record created: 10 September 2026 · Last researched: 10 September 2026