Coal and Coal Products

Chronology

Coal is material made up of hydrocarbons and other elements, such as sulfur, that is used mainly as a fuel for industries and homes.   Coal is classified by the amount of carbon, volatile matter and heat content contained in it.   Anthracite coal has the highest amount of carbon, lowest volatiles and heat content greater than 14,000 Btu / lb, bituminous coal has high carbon content, low volatiles and heat content between 10,500 and 14,000 Btu / lb, subbituminous coal has carbon and volatile contents between those of bituminous and lignite coals, and a heat content between 10,500 and 8,300 Btus / lb, lignite coal has the lowest carbon content, the highest volatiles, and heat content lower than 8,300 Btus / lb. ^{EERC n.p.}   See map of U.S. coal fields

Bituminous coal provides important byproducts, such as coal gas, coal tar, and various derivative chemicals.   Coal byproducts include coke, road, roofing, and insulation materials, wallboard, and mineral fillers for plastics, paints, carpet backings, etc.   Coke is the most important coal byproduct.   When coal is burned with reduced amounts of oxygen at about 2370°F, its organic matter is burned off and the residue, coke, is almost pure carbon.   Coke burns at a higher temperature than coal, which is essential to melt iron ore to extract iron in a blast furnace.   When coal with reduced amounts of oxygen is heated to about 1650°F, the coke gives off a gas that was once used for domestic lighting.   In both case, in addition to the fuel coke and coal gas, byproducts include ammonia, tar and water vapor, which are distilled and collected. ^{How 549}

Coal gas is obtained from bituminous coal or wood by distilling it in the absence of air.   The gas is then cooled and washed of tars and sulphur.   It was then piped to cities ("town gas") and burned as an illuminant with a bright yellow color.   Coal gas is about 35% hydrogren and 45% methane and is low in carbon monoxide (about 3% to 6%), with a heating value of 500 to 600 Btu/cu. ft., about ½ of natural gas.   In early times, this heating value would have been highly desirable in the manufacture of engines.   A useful byproduct was coke used in iron smelting.   When the demand for coke increased along with the growing iron and steel manufacturing, coke became the primary product and coal gas was a byproduct.   Philippe Lebon in France and William Murdock and Boulton and Watt in England were the first to begin the gas lighting industry.   In England, the gas was tested satisfactorily in 1792 and the first Boulton & Watt commercial lighting plant with a 50-lamp capacity went into operation in 1806.   Other coal gas manufacturers eventually outstripped Boulton and Watt who preferred to concentrate on steam engine manufacture.   In the U.S. a part of Baltimore was lighted with coal gas in 1816 and in New York City in 1823. ^{Cummins 56-58}

One ton of coal yields about 9.5 gallons of coal tar, which condenses on cooling to a thick, black viscous oil containing a mixture of about 200 chemicals, the most important of which are separated by distillation.   Distillation provides benzole, napthalene, anthracene, creosote, and coal tar pitch.   Benzole produces benzene, toluene and xylene.   The coal tar pitch is used to make road tar, fuel briquettes, graphite electrodes, and refractory materials.   The chemicals are used to make dyes, pesticides, plasticizers, inks, tires, wood preservatives, pharmaceuticals, and cosmetics. ^{Petro n.p.}

Aniline [C₆H₇N] is prepared commercially by the reduction of nitrobenzene, a product of coal tar, or by heating chlorobenzene with ammonia in the presence of a copper catalyst.   It is of great importance in the dye and pigment industries, being used as the starting substance in the manufacture of many dyes, e.g., indigo, and pigments.   For this reason, many dyes have the word aniline in their names, such as aniline black, one of the best black dyes known, aniline red, yellow, blue, purple, orange, green, and others.   Today these synthetic dyes have largely replaced the natural ones. ^{Ency n.p.}   Aniline also is used in the manufacturing of resins, varnishes, perfumes, printing inks, cloth marking inks, paint removers, photographic chemicals, explosives, herbicides, fungicides, rigid polyurethanes, optical whitening agents, and shoe blacks.   It is used as a solvent, a chemical intermediate for rubber processing, corrosion inhibitors, resins, cyclohexylamine, hydroquinine, pesticides such as alachlor, pharmaceuticals such as sulfonamides, 4-anilinophenol, and methylenediisocyanate.   Aniline is a component of lacquers, wood stains, and skin stains.   It is an analytical reagent in paper chemistry, and an azeotropic agent in the manufacture of anhydrous hydrazine.   It is used in the synthesis of intermediates for artificial sweeteners and isocyanate, and it is also a catalyst and stabilizer in the synthesis of hydrogen peroxide and cellulose. ^{NSC n.p.}

To 1790

Coal was discovered in Virginia in 1701.

Stephen Hales (1677-1761) reported on the making of coal gas in 1727.   The process was then known as the "destructive distillation of coal". ^{Cummins 56}

The first coal was dug in Virginia in 1748.

The first commercial U.S. coal shipment was made in 1758.   The large bituminous deposit was near Richmond, which had access to the Atlantic Ocean via the James River.   Therefore, coal was transported by ship to ports along the eastern seaboard.

1790-1799

1800-1809

Anthracite coal was burnt as an experiment for the first time by Judge Jesse Fell of Wilkes-Barre, PA, on Feb. 11, 1808. ^{Carruth 137}

1810-1819

1820-1829

The first commercial distillation of coal tar was made by Drs. Longstaff and Dalton near Leith, Scotland, in 1822.   They sold the light distillated to Charles MacIntosh as a solvent for rubber proofing, which he patented in 1823. ^{How 549}

1830-1839

On January, 1839, anthracite coal was used to smelt iron in Mauch Chunk, PA, for the first time. ^{Carruth 238}

1840-1849

In 1843, Hoffmann discovered aniline in coal tar. ^{How 549}

1850-1859

1860-1869

The first surface mining of coal begins near Danville, IL, in 1866.

1870-1879

Coal is mined with a steam-powered shovel in 1877.

1880-1889

In the 1880s, coal mining machines came into general use.

1890-1899

In the 1890s, machines were developed to undercut coalbeds.

1900-1909

1910-1919

In 1918, the first pulverized coal was used as fuel in electric power plants.

1920-1929

1930-1939

1940-1949

In 1940, auger surface mining was introduced.

1950-1959

In 1956, railroads began converting from coal to diesel fuel.

1960-1969

1970-1979

1980-1989

1990-1999