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Photomicrograph made with a scanning electron microscope and back-scatter detector: cross section of fly ash particles. Fly ash, flue ash, coal ash, or pulverised fuel ash (in the UK)—plurale tantum: coal combustion residuals (CCRs)—is a coal combustion product that is composed of the particulates that are driven out of coal-fired boilers together with the flue gases.
The first breakthrough in the detection of arsenic poisoning was in 1775 when Carl Wilhelm Scheele discovered a way to change arsenic trioxide to garlic-smelling arsine gas (AsH 3), by treating it with nitric acid (HNO 3) and combining it with zinc. [3] As 2 O 3 + 6 Zn + 12 HNO 3 → 2 AsH 3 + 6 Zn(NO 3) 2 + 3 H 2 O
A coal-fired power plant with ash ponds. Coal ash, also known as coal combustion residuals (CCRs), is the mineral residue that remains from burning coal. Exposure to coal ash and to the toxic substances it contains may pose a health risk to workers in coal-fired power plants and residents living near coal ash disposal sites.
In the Gutzeit test, AsH 3 is generated by reduction of aqueous arsenic compounds, typically arsenites, with Zn in the presence of H 2 SO 4. The evolved gaseous AsH 3 is then exposed to AgNO 3 either as powder or as a solution. With solid AgNO 3, AsH 3 reacts to produce yellow Ag 4 AsNO 3, whereas AsH 3 reacts with a solution of AgNO 3 to give ...
Arsinides react with water to yield arsine AsH 3: KAsH 2 + H 2 O → KOH + AsH 3 [ 6 ] Potassium dihydrogen arsinide KAsH 2 reacts with halobenzenes C 6 H 5 X , where X = Cl, Br, I ( chlorobenzene C 6 H 5 Cl , bromobenzene C 6 H 5 Br , iodobenzene C 6 H 5 I ) to produce benzene C 6 H 6 , tetraphenyldiarsine (C 6 H 5 ) 2 As−As(C 6 H 5 ) 2 and ...
The behaviour of the coal's ash residue at high temperature is a critical factor in selecting coals for steam power generation. Most furnaces are designed to remove ash as a powdery residue. Coal which has ash that fuses into a hard glassy slag known as clinker is usually unsatisfactory in furnaces as it requires cleaning. However, furnaces can ...
These include moisture content, ash content, sulphur content, volatile content, tar, and plasticity. The goal is to achieve a blend of coal that when processed will produce a coke of appropriate strength (generally measured by coke strength after reaction), while losing an appropriate amount of mass. Other blending considerations include ...
The combustion of coal releases diverse chemicals into the air. The main products are water and carbon dioxide, just like the combustion of petroleum. Also released are sulfur dioxide and nitrogen oxides, as well as some mercury. The residue remaining after combustion, coal ash often contains arsenic, mercury