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From Wikipedia

Coal assay

Coal Analysis techniques are specific analytical methods designed to measure the particular physical and chemical properties of coals. These methods are used primarily to determine the suitability of coal for coking, power generation or for iron oresmelting in the manufacture of steel.

Chemical properties of coal

Coal comes in four main types or ranks: lignite or brown coal, bituminous coal or black coal, anthracite and graphite. Each type of coal has a certain set of physical parameters which are mostly controlled by moisture, volatile content (in terms of aliphatic or aromatic hydrocarbons) and carbon content.


Moisture is an important property of coal, as all coals are mined wet. Groundwater and other extraneous moisture is known as adventitious moisture and is readily evaporated. Moisture held within the coal itself is known as inherent moisture and is analysed quantitatively. Moisture may occur in four possible forms within coal:

  • Surface moisture: water held on the surface of coal particles or macerals
  • Hydroscopic moisture: water held by capillary action within the microfractures of the coal
  • Decomposition moisture: water held within the coal's decomposed organic compounds
  • Mineral moisture: water which comprises part of the crystal structure of hydrous silicates such as clays

Total moisture is analysed by loss of mass between an untreated sample and the sample once analysed. This is achieved by any of the following methods;

  1. Heating the coal with toluene
  2. Drying in a minimum free-space oven at 150|°C|°F|abbr=on within a nitrogen atmosphere
  3. Drying in air at 100|to|105|C|F and relative loss of mass determined

Methods 1 and 2 are suitable with low-rank coals but method 3 is only suitable for high-rank coals as free air drying low-rank coals may promote oxidation. Inherent moisture is analysed similarly, though it may be done in a vacuum.

Volatile matter

Volatile matter in coal refers to the components of coal, except for moisture, which are liberated at high temperature in the absence of air. This is usually a mixture of short and long chain hydrocarbons, aromatic hydrocarbons and some sulfur. The volatile matter of coal is determined under rigidly controlled standards. In Australian and British laboratories this involves heating the coal sample to 900 ± 5 °C (1650 ±10 °F) for 10 min.


Ash content of coal is the non-combustible residue left after coal is burnt. It represents the bulk mineral matter after carbon, oxygen, sulfur and water (including from clays) has been driven off during combustion. Analysis is fairly straightforward, with the coal thoroughly burnt and the ash material expressed as a percentage of the original weight.

Fixed carbon

The fixed carbon content of the coal is the carbon found in the material which is left after volatile materials are driven off. This differs from the ultimate carbon content of the coal because some carbon is lost in hydrocarbons with the volatiles. Fixed carbon is used as an estimate of the amount of coke that will be yielded from a sample of coal. Fixed carbon is determined by removing the mass of volatiles determined by the volatility test, above, from the original mass of the coal sample.

Chemical analysis

Coal is also assayed for oxygen content, hydrogen content and sulfur. Sulfur is also analysed to determine whether it is a sulfide mineral or in a sulfate form. Sulfide content is determined by measurement of iron content, as this will determine the amount of sulfur present as iron pyrite or dissolution of the sulfates in hydrochloric acid with precipitation as barium sulfate.

Carbonate minerals are analysed similarly, by measurement of the amount of carbon dioxide emitted when the coal is treated with hydrochloric acid. Calcium is ana he carbonate content is necessary to determine the combustible carbon content and incombustible (carbonate carbon) content.

Chlorine, phosphorus and iron are also determined to characterise the coal's suitability for steel manufacture.

An analysis of coal ash may also be carried out to determine not only the composition of coal ash, but also to determine the levels at which trace elements occur in ash.

Physical and mechanical properties

Relative density

Relative density or specific gravity of the coal depends on the rank of the coal and degree of mineral impurity. Knowledge of the density of each coal ply is necessary to determine the properties of composites and blends. The density of the coal seam is necessary for conversion of resources into reserves.

Relative density is normally determined by the loss of a sample's weight in water. This is best achieved using finely ground coal, as bulk samples are quite porous. To determine in-place coal tonnages however, it is important to preserve the void space when measuring the specific gravity.

Particle size distribution

The particle size distribution of milled coal depends partly on the rank of the coal, which determines its brittleness, and on the handling, crushing and milling it has undergone. Generally coal is utilised in furnaces and coking ovens at a certain size, so the crushability of the coal must be determined and its behaviour quantified. It is necessary to know these data before coal is mined, so that suitable crushing machinery can be designed to optimise the particle size for transport and use.

Float-sink test

Coal plies and particles have different relative densities, determined by vitrinite content, rank, ash and mineral content and porosity. Coal is usually washed by passing it over a bath of liquid of known density. This removes high-ash content particles and increases the saleability of the coal as well as its energy content per unit volume. Thus, coals must be subjected to a float-sink test in the laboratory, which will determine the optimum particle size for washing, the density of the wash liquid required to remove the maximum ash content with the minimum work.

Floatsink testing is achieved on crushed and pulverised coal in a process similar to metallurgical testing

Coal tar

Coal tar is a brown or black liquid of high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal is carbonized to make coke or gasified to make coal gas. Coal tars are complex and variable mixtures of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds, about 200 substances in all.



Being flammable, coal tar is sometimes used for heating or to fire boilers. Like most heavy oils, it must be heated before it will flow easily.

Tar was a vital component of the first sealed, or "tarmac", roads. The streets of Baghdad were the first to be paved with tar from the 8th century AD. Coal tar was formerly used as one of the primary ingredients of Tarmacadam pavements, when mixed with ironworks slag. Today, petroleum derived binders and sealers are more commonly used. These sealers are used to extend the life and lower maintenance cost associated with asphalt pavements, primarily in asphalt road paving, car parks and walkways.


Like pine tar, it can be used in medicated shampoo, soap and ointment, as a treatment for dandruff and psoriasis, as well as being used to kill and repel head lice. When used as a medication in the U.S., coal tar preparations are considered an OTC (over-the-counter drug) pharmaceutical and are subject to regulation by the United States Food and Drug Administration. Name brands include Denorex, Balnetar, Psoriasin, Tegrin, T-Gel, and Neutar. When used in the extemporaneous preparation of topical medications, it is supplied in the form of Coal Tar Topical Solution USP, which consists of a 20% w/v solution of coal tar in alcohol, with an additional 5% w/v of polysorbate 80; this must then be diluted in an ointment base such as petrolatum. Coal tar is also used to synthesize paracetamol (acetaminophen). It is also used to manufacture paints,synthetic dyes and photographic materials.


According to the International Agency for Research on Cancer, preparations that include more than 5 percent of crude coal tar are Group 1carcinogen.

According to the National Psoriasis Foundation and the FDA, coal tar is a valuable, safe and inexpensive treatment option for millions of people with psoriasis and other scalp or skin conditions. Coal tar concentrations between 0.5% and 5% are safe and effective for psoriasis, and no scientific evidence suggests that the coal tar in the concentrations seen in non-prescription treatments is carcinogenic. The NPF states that coal tar contains approximately 10,000 chemicals, of which only about 50% have been identified , and the composition of coal tar varies with its origin and type of coal (eg: lignite, bituminous or anthracite) used to make it.

Coal tar causes increased sensitivity to sunlight, so skin treated with topical coal tar preparations should be protected from sunlight.

The residue from the distillation of high-temperature coal tar, primarily a complex mixture of three or more membered condensed ring aromatic hydrocarbons, was listed on 28 October 2008 as a substance of very high concern by the European Chemicals Agency.

Bergius process

The Bergius Process is a method of production of liquid hydrocarbons for use as synthetic fuel by hydrogenation of high-volatile bituminous coal at high temperature and pressure. It was first developed by Friedrich Bergius in 1913, in 1931 Bergius was awarded the Nobel Prize in Chemistry for his development of high pressure chemistry.


The coal is finely ground and dried in a stream of hot gas. The dry product is mixed with heavy oil recycled from the process. Catalyst is typically added to the mixture. A number of catalysts have been developed over the years, including tungsten or molybdenumsulfides, tin or nickeloleate, and others. Alternatively, iron sulphides present in the coal may have sufficient catalytic activity for the process, which was the original Bergius process.

The mixture is pumped into a reactor. The reaction occurs at between 400 to 500 °C and 20 to 70 MPahydrogen pressure. The reaction produces heavy oils, middle oils, gasoline, and gases. The overall reaction can be summarized as follows:

n{\rm C} + (n+1){\rm H}_2 \rarr {\rm C}_n{\rm H}_{2n+2}

The immediate product from the reactor must be stabilized by passing it over a conventional hydrotreating catalyst. The product stream is high in naphthenes and aromatics, low in paraffins and very low in olefins. The different fractions can be passed to further processing (cracking, reforming) to output synthetic fuel of desirable quality. If passed through a process such as Platforming, most of the naphthenes are converted to aromatics and the recovered hydrogen recycled to the process. The liquid product from Platforming will contain over 75% aromatics and has a RON of over 105.

Overall, about 97% of input carbon fed directly to the process can be converted into synthetic fuel. However, any carbon used in generating hydrogen will be lost as carbon dioxide, so reducing the overall carbon efficiency of the process.

There is a residue of unreactive tarry compounds mixed with ash from the coal and catalyst. To minimise the loss of carbon in the residue stream, it is necessary to have a low-ash feed. Typically the coal should be <10% ash by weight. The hydrogen required for the process can be also produced from coal or the residue by steam reforming. A typical hydrogen demand is ~8&nbsp;kg hydrogen per ton of dry, ash-free coal.


Friedrich Bergius developed the process during his habilitation. A techniques for the high-pressure and high-temperature chemistry of carbon-containing substrates yielded in a patent in 1913. In this process liquid hydrocarbons used as synthetic fuel are produced by hydrogenation of lignite (brown coal). He developed the process well before the commonly-known Fischer-Tropsch process. Karl Goldschmidt invited him to build an industrial plant at his factory the Th. Goldschmidt AG (now known as Evonik Industries) in 1914. The production began only in 1919, after the World War I ended, when the need for fuel was already declining. The technical problems, inflation and the constant criticism of Franz Joseph Emil Fischer, which changed to support after a personal demonstration of the process, made the progress slow and Bergius sold his patent to BASF, where Carl Bosch worked on it. Before World War II several plants where built with an annual capacity of 4 million tons of synthetic fuel. These plants were extensively used during World War II to supply Germany with fuel and lubricants.


The Bergius process was extensively used by Nazi Germany and targeted for bombing during the Oil Campaign of World War II. At present there are no plants operating the Bergius Process or its derivatives commercially. The largest demonstration plant was the 200 ton per day plant at Bottrop, Germany, operated by Ruhrkohle, which ceased operation in 1993. There are reports of the Chinese company constructing a plant with a capacity of 4 000 ton per day. It was expected to become operational in 2007 , but there has been no confirmation that this was achieved.

During WWII the United States conducted secret research in converting coal to gasoline at a facility in Louisiana, Missouri. Located along the Mississippi river, this plant was producing gasoline in commercial quantities by 1948. The Louisiana process method produced automobile gasoline comparable in price with petroleum based gasoline but of a higher quality. The facility was shut down in 1953 by the Eisenhower administration after intense lobbying by the oil industry . Declassified documents detailing the experiments and the production process were systematically destroyed. In the 1980s 16mm microfilm of these documents were discovered in a few Federal Depository Libraries. Within three months researcher requests to view this microfilm were told the canisters were missing. In one case a physical search turned up only the rusty pattern of a 16mm film canister on a steel shelf. Apparently The National Petroleum Council continues to suppress this information.

From Yahoo Answers

Question:What's the difference between oil, coal, dirt, and limestone? Obviously I'm talking about how they're formed.

Answers:The other answer is excellent and informative, but doesn't really address how these materials are formed. Oil is formed from buried organic material. In most examples oil forms from the remains of phytoplankton (microscopic plants) and zooplankton (microscopic animals) which sink to the ocean floor and are buried by mud, clay, and silt, which later forms shale. As the shale is buried deeper and deeper (often several miles) it warms up and when the temperature exceeds about 140 F. the organic material begins to form oil. This process can take millions of years for the burial stage, and thousands of years for the chemical alteration of the organics to become oil. This process is known as catagenesis. Coal is formed from the remains of larger plants and trees which have been preserved by falling into swamps in which there was not enough dissolved oxygen in the water to allow the plant material to rot or decompose. These accumulated in thick deposits in some places in the world. As these accumulations of plant material were covered by other deposition of shale they were compressed and heated, undergoing a process called coalification that made them into coal. Dirt is formed primarily from weathered rock material, with some organic content contributed by plants and animals. There are many types of soil but they are generally divided into twelve soil orders. This website has good illustrations and explanations of all of the soil orders, along with maps: http://soils.ag.uidaho.edu/soilorders/orders.htm Limestone, as you can guess, is my specialty. Limestone is formed by living organisms in almost all cases. In rare examples limestone can form by direct precipitation of calcium carbonate from sea water or even fresh water, but in most cases it is the remains of living organisms. The organisms that form limestone include microbes, bacteria, algae, foraminifera, plankton, sponges, molluscs, corals, bryozoans, brachipods, echinoderms, arthropods, and many more organisms that all secrete calcium carbonate as either part of their body or as a shell. As the bodies of all of these organisms accumulate in a marine or fresh water environment they gradually become cemented together by a process known as diagenesis. Some organisms form deposits of calcium carbonate that remain in place within the eventual limestone bed. Corals can be seen in their original growth position in some outcrops of limestone (Barbados for example). Again, some degree of burial and pressure helps with the process of cementation and diagenesis. However, it has been proven that some limestone can be formed in only a few decades, as pop-tops from 1960's cans (which are no longer in existence) have been found within some deposits of limestone along tropical beaches. The texture of limestone is highly variable based on what type of organism made up the bulk of the calcium carbonate. Some very fine-grained smooth limestone is formed from the remains of green-algae that create sort of a lime mud before it forms limestone. Accumulations of oysters and clams can form very porous rough limestones in what is commonly known as coquina. Travertine is a form of limestone that is formed by both evaporation of hot spring water and the action of microbes that help precipitate the limestone. Here is a website that has some information on both the formation of limestone and coal: http://gpc.edu/~pgore/geology/historical_lab/sedrockslab.php

Question:Which of the following substances are pure substances and which are mixtures? 1.sea water 2.cooking oil 3.coal 4.steel 5.chili sauce 6.bronze 7.sand 8.Gold 9. orange squash 10.Salt 11.Milk 10.Oxygen 12.Air 13.Oranger juice 14.Coke 15.Soil Plz tell me how did u find out that which substances were pure and which were mixtures. (If u help me i will be thankful to u all) thanx to all and special thanx to professor beatz and quiepe

Answers:Here's a hint: mixtures can always be broken down into other things. 1. Sea water is a mixture because it has a ton of different things in it, like salt and water and various microorganisms. 2. Cooking oil is a mixture. It is a blend of various kinds of oils. 3. Coal is a pure substance. It is made up of nothing but carbon atoms, pure to the atomic level. 4. Steel is a mixture. It is an alloy of different other metals, especially iron. It also uses carbon. 5. Chili sauce has all sorts of ingredients. I don't know what they are exactly, but there has to be stuff like different peppers and condiment bases. It's definitely a mixture. 6. Bronze is a mixture. It's another metal alloy made with tin, copper, and some other metals. 7. Sand is a mixture. I live by the beach, and you can see variations in the grains' colors. They're not all the same, so it's a mixture of different kinds of sand. 8. Gold is an element. At 24 k, it's as pure as you need to be for practical purposes. Pure substance. 9. Orange squash: well, it's all orange squash, but squash has the stem, the skin, the flesh, and all these different parts. The components themselves range from DNA to proteins to sugars and carbohydrates and other organic molecules. Mixture. 10. Salt is pure. Just NaCl, baby. 11. Milk has fats and proteins and carbs and water and vitamins. Mixture. 10. Oxygen is just oxygen, an element. Pure substance. 12. Air is a mixture of nitrogen, oxygen, carbon dioxide, water vapor, noble gases, and hydrogen. 13. "Oranger" juice: same as milk, for the most part. Mixture. 14. Coke: caffeine, carbonic acid, sugars... mixture 15. Soil has all sorts of stuff in it. Mixture.

Question:Did you see the commercial by BP advertising ''clean'' coal and its advantages? What is clean about burning''clean'' coal other than simply coal? Coal contains a lot more than carbon. When you burn coal, you also burn all the impurities in the coal - things like uranium, thorium, sulfur and ash producing rock particles. A coal fired power plant produces more gamma radiation than a nuclear power plant. "clean" coal has however a low sulfur content, and dirty coal has lots of sulfur. But there is really no difference between coal and ''clean" coal.. Why are BP and other oil companies trying to give misleading information? Coal isn't the same everywhere you go. Some places has coal with a lot of sulfur, but others don't have much sulfur at all. American woman, what are you about? What happened in the past?! They don't remove anything, you genius. they need to burn it in order to get rid of the ''crap.'' that crap is emitted into the air we breathe!!!!1Coal releases 65% of sulfur in the US, which is millions of tons.

Answers:remember when tobacco smoking was supposed to be "healthy" the golden rule He who has the gold makes the rules


Answers:An allotrope is a structurally different form of an element; "Carbon has the most number of allotropes. Scientists have already found eight of them, including amorphous carbon allotrope (manifestations include coal and soot), carbon nanofoam, carbon nanotube, the diamond allotrope, fullerene allotrope, graphite, lonsdaleite, and ceraphite allotrope." It is the ability of an element to exist in more than one physical state. Many elements can appear naturally in more than one form at room temperature. The allotropes are usually different due to different crystal shape, a lack of crystal shape, or through the attachments of more than one atom of an element. An isotope is an element that has different numbers of neutrons in its nucleus. Examples are hydrogen-1, hydrogen-2 and hydrogen-3, known as protium, deuterium, and tritium respectively. protium or hydrogen-1 has a nucleus with 1 proton and no neutrons. Deuterium has 1 proton and 1 neutron in its nucleus, while tritium has 1 proton and 2 neutrons in its nucleus.

From Youtube

Black Coal (anthracite) Brown Coal (lignite) Peat and Coke :This is a teaching resource video used to demonstrate the difference in depth and moisture content of fossil fuels; especially the different forms of coal including coke with is tried to add to iron to make steel. I also mention that coal is the predominant fossil fuel mined (often in open cut mines) in Australia with the exception of crude oil (petroleum) in bass straight near Tasmania. This specifically addresses outcomes taught to year 9 high school science students as part of the Core Science 3 text book. I also mention the difference between renewable and non renewable resources.