Environmental Impact of Production of Sulphuric Acid through Metallurgical - Essay Example

Title: ENVIRONMENTAL IMPACT OF PRODUCTION OF SULPHURIC ACID THROUGH METALLURGICAL (Name) (Institution) (11/3/2008) Introduction Metallurgical is a domain of material sciences that studies the physical and chemical behavior of metallic elements, inter metallic compounds and their own compounds, which are called alloys. It is also the technology of metals that refers to the way in which science is applied to their practical use. In general metallurgy is commonly used in the craft of metal working. Metallurgical is a process whereby metals are used as raw materials in a process called extractive metallurgical. In this process a mixture of copper and iron sulfides which are normally referred to as matte are treated in converters so as to oxidize iron in the first stage and then the second stage is to oxidize copper. In this process oxygen is blown into metal sulfide solution so as to convert metal sulfides to oxides. The resulting product which is water is highly acidic and is called Acid Mine Drainage. (Meyer, 1983) This is shown by the following equations. 2FeS2(s) + 7O2(g) + 2H2O(l) → 2Fe2+(aq) + 4SO42-(aq) + 4H+(aq) The subsequent oxidation of sulfide to sulfate forms the ferrous iron which is the oxidized to ferric iron; 4Fe2+(aq) + O2(g) + 4H+(aq) → 4Fe3+(aq) + 2H2O(l) Additional oxidation will result to FeS2(s) + 14Fe3+(aq) + 8H2O(l) → 15Fe2+(aq) + 2SO42-(aq) + 16H+(aq) The net effect of these reactions is to release H+, which lowers the pH and maintains the solubility of the ferric ion. But, there is also SO42-(aq) which can easily be turned into sulphuric acid through the addition of water in a controlled way. (Meyer, 1983) Potential Environmental Impacts In Case Of Accident Sulphuric acid is very corrosive. It is found in the atmosphere as droplets or normally is attached to other particles. When sulphuric acid get mixed with water it produces a lot of heat because of its exothermic nature. This shows that it has high affinity for water. When concentrated sulphuric acid comes into contact with other metals it can explode or catch fire. Sulphuric acid reacts with metals to produce hydrogen which is explosive. Some of these materials are alcohols, metals and acetone. The sulphuric acid when heated produces sulfur trioxide which is very toxic. Its solubility to water and ethyl ethanol is dangerous to aquatic environments. It is also incompatible or reactive with organic materials such as chlorate's, carbides, fulminates, water and powdered metals. Sulphuric acid is very corrosive and irritating and it usually causes direct effects on the eyes, skin, respiratory and gastrointestinal tracts, this normally occurs if there are small amounts of it in the atmosphere. It can get to an extent that makes a person involved to be blind if thrown or poured into the eyes. The breathing of sulphuric acid mist results in tooth erosion and respiratory tract irritation. Its presence in human beings can cause the following diseases; bronchitis, pulmonary edema, conjunctivities, emphysema, stomatis, dermatitis and tracheobronchitis. Sulphuric acid is a constituent of acidic rain which is formed by atmospheric oxidation of sulphur dioxide in the presence of water like the oxidation of sulfurous acid. Sulphur dioxide is the main byproduct produced when sulphur-containing fuels such as coal or oil are burned. (Igram, 2002) Sulphuric acid is formed naturally by the oxidation of sulphide minerals, such as iron sulfide. The resulting water can be highly acidic and is called (ARD) Acid Rock Drainage. This acidic water is capable of dissolving metals present in sulfide ores, which results in brightly-colored, toxic streams. The oxidation of iron sulfide pyrite by molecular oxygen produces iron (II), or Fe2+: FeS2 + 7/2 O2 + H2O → Fe2+ + 2 SO42− + 2 H+. The Fe2+ can be further oxidized to Fe3+, according to: Fe2+ + ¼ O2 + H+ → Fe3+ + 1/2 H2O, and the Fe3+ produced can be precipitated as the hydroxide or hydrous oxide. The equation for the formation of the hydroxide is Fe3+ + 3 H2O → Fe(OH)3 + 3 H+. The iron (III) ion can also oxidize pyrite. When iron (III) oxidation of pyrite occurs, the process can become rapid. pH values below zero have been measured in ARD produced by this process. ARD can also produce sulphuric acid at a slower rate, so that the Acid Neutralization Capacity (ANC) of the aquifer can neutralize the produced acid. In such cases, the Total Dissolved solids (TDS) concentration of the water can be increased from the dissolution of minerals from the acid-neutralization reaction with the minerals. (Igram, 2002) Impact of the Process on the Environment Iron oxide is not toxic, although some dangers are present when the fumes or dust of iron oxide are inhaled. Inhalation of any metallic fumes or dust can cause irritation to the throat and nasal area. They can also irritate the eyes. Iron oxide in high concentrations in the form of dust or fumes can cause metal fume fever. Metal fume fever is not extremely critical to health, causing a fever, sore/irritated/dry throat and mouth, and a metallic taste. This fever usually lasts only from 12 to 48 hours. Extended inhalation of iron oxide in high concentrations in the form of dust or fumes can cause pulmonary effects, eventually resulting in siderosis (inflammation of the lungs). Iron oxide released or even emitted can be dangerous when released and if there is presence of other chemicals or compounds in the environment. It can act as a catalyst such as when exposed in the presence of carbon monoxide it will catalyze it to carbon dioxide and also during the synthesis of ammonia. When it is exposed to aluminum it usually releases great amounts of heat. It also produces a lot of heat when iron and oxygen combines to produce rust. During the production of sulphuric acid there is production of sulfur dioxide. Sulfur dioxide acts as an acid. Inhalation results in labored breathing, coughing, and/or a sore throat and may cause permanent pulmonary damage. When mixed with water and contacted by skin, frostbite may occur. When it makes contact with eyes, redness and pain will occur. The long term exposure of copper can cause irritation of the nose, mouth, eyes and headaches. It may also cause liver and kidney damage and even death. It even can affect the intelligence of young adolescents. Its industrial exposure can cause metal fume fever with atrophic changes in nasal mucous membranes. Its chronic quantities cause Wilson's disease characterized by brain damage, hepatic cirrhosis, demyelination, renal disease and copper deposition in the cornea. (James, 1995) Generating and Transporting Of Raw Materials Copper does not break down easily and hence can accumulate in plants and animals when found in soils. This makes few plants to survive in such conditions. Due to the effects upon plants copper is a serious threat to the productions of farmlands. Copper can seriously influence the proceedings of certain farmlands, depending upon the acidity of the soil and the presence of organic matter. This is so because when organic matter reacts with copper it forms a complex compound which is insoluble. Copper can interrupt the activity in soils, as it negatively influences the activity of micro organisms and earthworms. The decomposition of organic matter may seriously slow down because of this. When the soils of farmland are polluted with copper, animals will absorb concentrations that are damaging to their health. Mainly sheep suffer a great deal from copper poisoning, because the effects of copper are manifesting at fairly low concentrations. (James, 1995) Iron (III)-O-arsenite, pentahydrate may be hazardous to the environment; special attention should be given to plants, air and water. It is strongly advised not to release the chemical enter into the environment because it thrives in the environment. Transporting of raw materials In the manufacture of sulphuric acid through this process a large amount of water is needed and also the raw materials are sometimes bulk. The raw materials should be transported in an enclosed space to prevent contamination to the environment. The kind of energy used whether its coal or fuel should be careful transported to prevent spillage. (Greenwood, 1997) When these raw materials are spilled into water it will affect the aquatic animals and plants. The metallic raw materials will spoil the soil resulting to spoilage of plants life cycle. Waste Generated and Disposal Iron sulphides are usually used to treat soils that have heavy metals in high concentration; the waste thus treated has a high level of water content and is hence difficult to handle thereafter, although this problem is not aroused in the treatment of waste waters and the like. (Wycliffe, 1999) Because, of its acidity nature, waste generated should be first be treated before they are disposed. Some of the waste generated can be recycled to produce copper by products and iron by products. Water can easily be recycled. The sulphuric acid can be used to purify the quality of Greenwood, N. (1997) the iron and copper produced. References Greenwood, N. (1997). Chemistry of the Elements, 2nd Edition, (Oxford: Butterworth-Heinemann) Igram, W. (2002). Chemistry of Compounds and its Groups, (London: Cambridge Publishers) James, K. (1995). Manufacture of Sulphuric Acid, (London: Oxford Publishers) Meyer, B. (1983). Second dissociation constant of hydrogen sulfide, (New York: New York Publishers) Philip J. (1987). Survey of Industrial Chemistry, (New York: John Wiley & Sons) Wycliffe, R. (1999). Polymers and its Products, (New York: New York Publishers) Read More