Coal Surface Mining

8 min read

Coal Surface Mining

Coal has 50-100% more energy per kilogram than wood and burns at higher temperatures, making it essential for metalworking, brick and pottery firing, and intensive heating. In regions where coal seams reach the surface — common in the Appalachians, British Isles, central Europe, eastern Australia, and parts of China — coal can be extracted with hand tools and no tunneling. Surface coal mining requires minimal technology and has been practiced since the Bronze Age.

Finding Coal Deposits

Geological Indicators

Coal forms in sedimentary rock layers, typically:

  • Sandstone and shale sequences — coal seams often sit between layers of these rocks
  • Stream banks and river cuts — erosion exposes coal seams as dark bands in cliff faces
  • Hillsides after landslides — freshly exposed rock may reveal coal
  • Black soil in specific areas — eroded coal fragments darken the surface soil
  • Pre-collapse coal mines — old mine sites are the easiest way to find coal. Look for slag heaps, old rail lines, pit head structures

Outcrop Identification

A coal outcrop is where a seam reaches the surface:

  • Look for a black or dark brown band in exposed rock faces (road cuts, quarries, river banks, eroded hillsides)
  • Test suspected coal: it is lighter than stone of similar size, breaks with a conchoidal or layered fracture, leaves a black streak when scraped on unglazed pottery, and burns when placed in a hot fire
  • Trace the seam along the surface to determine its extent and direction

Coal Types & Quality

TypeCarbon %Energy (GJ/tonne)Characteristics
Lignite (brown coal)25-35%10-15Crumbly, high moisture, smoky. Worst coal but still better than wet wood
Sub-bituminous35-45%15-20Moderate quality. Common in surface deposits
Bituminous45-86%24-30Good coal. Burns hot with moderate smoke. Most common fuel coal
Anthracite86-97%30-35Best coal. Burns very hot, almost smokeless. Rare in surface deposits

Most surface-accessible coal is lignite or sub-bituminous. Bituminous coal is occasionally found at the surface where seams have been uplifted by geological forces.

Extraction Methods

Outcrop / Open-Cut Mining

The simplest and safest method — mining from the surface without going underground:

  1. Clear overburden: Remove soil and rock covering the coal seam using picks, shovels, and wheelbarrows. For thin overburden (less than 2 meters), this is practical by hand
  2. Work the seam: Break coal from the exposed face using a pick, mattock, or wedges. Coal is softer than most rock and fractures readily
  3. Follow the seam: As you extract coal, the working face advances into the hillside or deeper into the ground
  4. Backfill: As you advance, use the overburden and waste rock to fill the area behind you. This prevents a growing pit and reduces land disruption

Practical limits: Open-cut mining is viable when the overburden-to-coal ratio is less than about 5:1 by hand. If you must move 5 tonnes of rock for every tonne of coal, it stops being worthwhile.

Drift Mining (Hillside Entry)

If a coal seam outcrops on a hillside, you can follow it into the hill:

  1. Enter horizontally where the seam meets the surface
  2. Cut a tunnel just tall and wide enough to work in (1.5m x 1.5m minimum)
  3. Timber the roof with strong wooden beams (pit props) as you advance
  4. Follow the seam — the coal itself is your guide
  5. Maximum safe depth without ventilation engineering: 30-50 meters from the entrance

This is significantly more dangerous than surface mining. See safety section below.

Tools & Equipment

  • Pick or mattock: Primary coal-breaking tool
  • Shovel: Loading and moving coal
  • Wedges and sledgehammer: Splitting large coal blocks along natural fractures
  • Wheelbarrow or sled: Hauling coal from the face to storage
  • Buckets: Hauling from deeper cuts
  • Timber saw and axe: Cutting pit props for any underground work

Safety

Roof Collapse

The primary killer in coal mining throughout history:

  • Always timber any underground working. No exceptions, no “it looks stable”
  • Use hardwood pit props (oak, ash) at maximum 1.5-meter spacing
  • Cap each pair of props with a horizontal beam
  • Listen for creaking, popping, or falling dust — these precede collapse
  • Never work alone underground. Always have someone at the entrance
  • Do not undercut the roof — leave coal pillars if the seam is thicker than your tunnel height

Gas Hazards

  • Methane (CH₄): Trapped in coal seams. Explosive at 5-15% concentration in air. Odorless. Test with a candle on a long pole held at the tunnel ceiling (methane rises) — a elongated, bluish flame indicates methane presence. If detected, ventilate immediately before any further work
  • Carbon monoxide (CO): Produced if coal spontaneously combusts underground. Odorless. Lethal. Use a caged canary or small animal as a gas detector (historical method) — they are more sensitive to CO than humans
  • Carbon dioxide (CO₂): Heavier than air, collects in low spots. A candle placed at floor level that dims or extinguishes indicates CO₂ accumulation

Respiratory Protection

Coal dust causes black lung disease (pneumoconiosis) with prolonged exposure:

  • Wet the coal face before working (reduces airborne dust)
  • Wear a cloth mask (wet bandana is better than nothing)
  • Work in short shifts with breaks in fresh air
  • Surface mining has much lower dust exposure than underground work

Processing & Storage

Sorting & Grading

  • Remove rock: Hand-pick obvious stone inclusions from the coal
  • Grade by size: Lump coal (fist-size and larger) burns best in stoves. Fines (small pieces) are better for forge work or briquetting
  • Reject high-ash coal: Coal that is heavy for its size or has visible stone layers will produce excessive ash and poor heat

Washing

Coal can be “washed” to remove rock and clay:

  1. Place crushed coal in a trough of water
  2. Agitate — coal floats or stays near the surface (density ~1.3), rock sinks (density ~2.5)
  3. Skim the clean coal from the surface
  4. Dry before storage

Storage

  • Store coal dry and under cover. Wet coal is harder to light and produces more smoke
  • Do not store large quantities of fine coal in an enclosed space — it can spontaneously combust through slow oxidation
  • Good ventilation prevents heat buildup in the coal pile
  • Small quantities for household use: a covered bin or shed is fine

Burning Coal Effectively

Coal Stove Requirements

Coal burns differently than wood:

  • Needs a grate: Coal requires air from below (unlike wood, which burns well on a solid hearth)
  • Needs draft control: Too much air = coal burns too fast and hot; too little = smoke and CO
  • Ash removal: Coal produces 5-15% ash by weight. The grate must allow ash to fall into an ash pan
  • Higher temperatures: Coal burns hotter than wood — the stove/hearth must withstand this (cast iron or firebrick lined)

Clinker Management

At high temperatures, coal ash fuses into hard lumps called clinker:

  • Clinker blocks airflow through the grate, smothering the fire
  • Shake the grate periodically to break up and drop clinker into the ash pan
  • Some coals produce more clinker than others — trial and error with your local supply

Coking for Metalwork

Some bituminous coals can be “coked” — heated in the absence of air to drive off volatile gases:

  • The result is coke: nearly pure carbon, burns very hot with almost no smoke
  • Coke is the ideal fuel for a blacksmith’s forge and for smelting iron (see iron-smelting)
  • Simple coking method: build a large mound of coal, cover with earth leaving air holes at the base and a chimney at the top, light from the bottom. Similar to charcoal production but with coal
  • The process takes 24-72 hours depending on mound size

How Much Coal Do You Need

Annual coal requirements (temperate climate):

UseBituminous Coal (tonnes)Lignite (tonnes)
Household cooking (with efficient stove)0.5-1.01.0-2.0
Household heating (small home)2-44-8
Blacksmith forge (part-time)1-2Not suitable
Brick/pottery kiln (10 firings/year)0.5-1.01.0-2.0
Total per household4-86-12

A single exposed coal seam 2 meters thick and 10 meters wide contains roughly 50-80 tonnes per meter of advance — enough for 10 households for a year from just 1 meter of mining progress.

Historical Context

Surface coal mining has been practiced since at least 200 BC in China and Roman Britain. Medieval English “sea coal” (collected from coastal outcrops where seams met the sea) heated London for centuries. The technology requires no industrial infrastructure — a strong back, a pick, and knowledge of where to dig.

In a post-collapse scenario, coal deposits that were uneconomical for industrial extraction (too small, too remote, too thin) become perfectly viable for village-scale needs. A seam that a mining company would ignore can sustain a community for generations.

See Also