Coal and coke

Look for black outcrops on hillsides and in stream cuts, dark shale sequences, and old workings. Measure the seam thickness — seams down to about half a metre were worked by hand historically — and its dip.

Test a sample before investing:

• Ash: weigh a sample, burn it completely, weigh the ash. Under about 10–15% ash is good fuel.
• Sulphur: a strong sulphurous smell when burning means iron made with it will be brittle.
• Coking: heat a crushed sample in a covered crucible. Coal that swells and fuses into a hard, coherent cake will make coke; coal that stays as loose powder will not.

Open-cut and drift mines — tunnels driven into a hillside along the seam — come long before shafts, which are a much bigger undertaking.

In a drift, support the roof with timber props and bars at close, regular spacing — around a metre apart — set as the face advances. Nobody works beyond the last prop. Sound the roof by tapping with a bar: a dull, drummy sound means loose rock, which is brought down deliberately or propped before work continues. In open cuts, bench the sides back so they cannot slump.

Every mine floods. Measure the inflow — how fast water rises in a sump with pumping stopped — and install pumping capacity of at least twice that, since inflow jumps after rain.

The cheapest drainage is free drainage: a tunnel — an adit or sough — driven from a lower valley up to the workings, so water runs out by gravity. Until steam is available, pump with horse gins and water power. Never mine below the water table without reliable pumping.

Every deep mine suffocates without forced air. Give every mine two separate openings — air down one, out the other — driven by a furnace at the foot of the upcast shaft or a fan, and route the air past every working face.

Firedamp — methane — explodes when it makes up about 5–15% of the air. The safety lamp — a flame enclosed in fine wire gauze that cools the flame below ignition — is also a detector: a pale blue cap growing above the flame means methane; a flame that dims or dies means blackdamp, air short of oxygen.

Keep coal dust down with water or spread stone dust — a firedamp flash can raise coal dust and turn a small explosion into one that runs through the whole mine.

Heat coal in the absence of air — as with charcoal — to drive off sulphur, water and volatiles. Raw coal ruins iron: its sulphur makes the metal brittle and unforgeable. Coke does not.

In a beehive oven, a domed brick chamber, charge crushed coking coal, fire it, control the air, and let it burn for two to three days. Quench and draw. Good coke is hard, silvery-grey, porous, and rings when struck. Expect roughly 60% of the coal's weight as coke.

A beehive oven burns off tar, ammonia and coal gas — the feedstock of the synthetic chemical industry. By-product ovens close the chamber and pipe the gases away:

• Coal gas — lighting and heating, decades before electricity.
• Ammonia liquor — ammonium sulphate fertiliser.
• Tar — distilled into benzene, toluene, phenol (carbolic acid, the first surgical antiseptic), dyes and pitch.

Coal gas contains carbon monoxide and kills in a closed room from a leak; benzene causes leukaemia with long exposure. Pipework is pressure-tested and rooms ventilated.

Coal dust and rock dust cause pneumoconiosis — black lung — and silicosis: permanent, progressive scarring of the lungs, appearing after years.

• Wet cutting and water sprays at the face and on roadways.
• Ventilation that carries dust away from people, not past them.
• Limited shift length and no children underground — both were won by law in the nineteenth century after enormous harm.
• A register of accidents and illnesses, reviewed and published.

This is the step that starts the carbon problem. It is not a reason to skip it — no society has industrialised without concentrated fuel — but it is a reason to know, from the beginning, that this is a bridge and not a destination.

Record tonnes of coal burned per year from the first tonne, and set, in writing, the share of the surplus that goes to the energy that replaces it — see energy without the carbon bill and Futures.