Developed by:2008-2009 TESSE Graduate Student Fellows

Penn State University

Introduction to Coal

What is coal?

The 3 P’s of coal formation: Plants Preservation Pressure (& temperature)

http://cleantechnica.comhttp://cleantechnica.comhttp://cleantechnica.comhttp://cleantechnica.com

Large amounts of plant material accumulate over thousands of years, usually in a swamp. (Peat)

www.fieldmuseum.org

1. PLANTS1. PLANTS

Smithsonian National Natural History Museum’s recreation of coal swamp 300 million years ago

http://confluence.org/us/la/n30w090v3/pic8.jpg

Modern-day swamp of the Mississippi River Delta

Dead plant material is very fragile and decays easily in the presence of oxygen.

Swamp waters are ideal for preservation stagnant and low in oxygen Organisms that might eat the plants can not live in

those conditions

Rivers overflow into swamps Bury plant material in sand and mud

Sea level rises and floods the swamps Covers plant material with marine mud

2. PRESERVATIONPRESERVATION

Plants & Preservation It takes about 10 ft. of dead plant material to

produce 1 ft. of coal. The conditions of the water and plants must be

just right for enough organic material to accumulate

West Virginia Geological & Economic Survey

Dead plant material is compressed from above by thick, heavy layers of sediment, slowly turning the deposits to solid rock

As it is buried deeper below the earth’s surface, pressure and temperature increase, removing moisture and gases, and changing the proportions of the 3 main elements: CARBON, OXYGEN, and HYDROGEN

Changes are gradual and occur over millions of years

3. PRESSURE & temperature3. PRESSURE & temperature

Coalification: How peat becomes coal

Coal Classification

Coal is classified into 4 main ranks based on chemical composition and which stage of development it is in.

Peat (precursor to coal) Lignite Sub-bituminous Bituminous Anthracite

Kentucky Geological Survey (2006)http://www.uky.edu/KGS/coal/coalkinds.htm

Coal’s Components

Carbon, Hydrogen, & Oxygen content are important for determining rank

Coal also contains varying amounts of Nitrogen, Sulfur, and mineral particles of clay, quartz and calcite (ash)

Coal in Pennsylvania ( 2002)

Distinguishing among ranks of coal

How do %C and heating value change with rank?

AnthraciteBituminous

Data compiled from: Penn State Coal Database and Argonne Premium Coal Sample Program

A

AB

B

How does oxygen and hydrogen content vary with rank?

Data compiled from:Penn State Coal Database andArgonne Premium Coal Sample Program

Description & Ranks of Coal

Peat Lignite Subbituminous Bituminous Anthracite

<55% Carbon 55-61.5% Carbon 61.5-64% Carbon 64-86% Carbon >86% Carbon

4500 BTU/lb 7000 BTU/lb 9,300 BTU/lb11,250 to

14,350 BTU/lb13,600 BTU/lb

A brownish-black organic matter that

looks very much like decayed wood. It is commonly used for

peat moss or garden mulch.

Peat is not coal.

A brownish-black coal with generally high moisture and ash

content and the lowest carbon content and

energy value.

A dull black coal. It has a littler higher energy value than

lignite when it burns.

A soft, intermediate grade of coal with carbon content and moisture between that of lignite and anthracite. It is the most common and widely used coal in the

United States.

The hardest type of coal, consisting of

nearly pure carbon. It has the highest

heating value and the lowest moisture and

ash content.

Pre-Cursor to CoalNo Rank

Lowest Rank Low-Middle Rank High-Middle Rank Highest Rank

What are the distinguishing characteristics or properties of coal? Which rank(s) of coal would be best for energy production?

Which rank(s) of coal has the most stored energy?

Adapted from American Coal Foundation (2010) and Coal in Pennsylvania (2002)

What tests could we perform to identify the

different ranks of coal in hand sample?

More than a black rock!

Coal Through a Microscope (2010)http://geology.com/articles/coal-

through-a-microscope.shtml1 mm

Now, you will identify and compare different types of coal. You will examine four unidentified types of coal( #1 – 4)

Document your visual observations about each sample Document your observations about the burning

behavior of each sample Identify each sample based on your observations

Consult the Descriptions and Ranks of Coal and Peat sheet