The reduction and smelting of iron ores entail the use of dissolved carbon in the iron bath as per the following equation: The carbon monoxide and hydrogen generated from the bath release heat to sustain the reaction process. Nevertheless, electricity costs, which were responsible for one-fourth of the total costs, are more important with regard to determining where to locate smelters because the variation in price of electricity is much greater than that of alumina. The remaining part of the gas is dispersed and defused to the atmosphere through extra-tall chimneys. for example: Cu 2 O + FeS â Cu 2 S + FeO Impurities form a slag which floats on the surface and is easily removed. In the smelting process a metal that is combined with oxygenâfor example, iron oxideâis heated to a high temperature, and the oxide is caused to combine with the carbon in the fuel, escaping as carbon monoxide or carbon dioxide. A large amount of solid waste is generated by the leaching process of low-grade copper and gold ore (Fig.Â 13.25) and tailing from gold recovery. Iron or steel objects are degreased, followed by immersion in a bath of molten zinc at 455Â°C. A steel vessel with the lining of carbon and graphite rods is used. Use of a top blown rotary converter (TBRC) streamlines copper production by merging smelting stages and by allowing the use of oxygen-enriched air for blowing [35]. Certain bacteria. Water, sulfuric acid, and mercury may also have been adsorbed onto the fume particles. Smelting When tin(IV) oxide is heated with carbon in a process called smelting, the element tin can be extracted. Smelting ore to reduce lead (top left) and copper (top right). Iron(II) oxide, FeO, slag is skimmed off. The water discharged from various plants is collected in ponds, tanks, and chambers. It also requires two chemical reactions to occur within the furnace. For all processing stages the proportion of copper present, about 10% in roaster dusts, 25% in reverberatory furnace dusts, and 45â55% in converter dusts, is sufficiently high to provide material recovery and emission control incentives for capture. Tighter emission control requirements as well as an interest in cleaner acid plant operation, however, have required employment of electrostatic precipitation and/or scrubbers for smelter flue gas treatment [15]. Apart from alumina, the primary requirement in the smelting of aluminium is a constant availability of electricity at a competitive price. The feed is melted from the surface of it in the main combustion room by burner heating. Zinc metal is distilled off. As it is not necessary to add fuel, it is called heat smelting. Recent developments in chemistry written in language suitable for students. Haldar, in Introduction to Mineralogy and Petrology (Second Edition), 2020. This limited the width of the column to about 1.5Â m. There was no absolute limit to the length of the furnace. FigureÂ 14.15. The mostly widely adopted of these alternative processes was the reverberatory furnace usually fed with fine partially roasted concentrate produced in multi-hearth roasters. Smelter sources contributed about 6% of the sulfuric acid produced in the U.S.A. in 1965 and more than 60% of the Canadian total for 1976 [39]. Copper sulfide and iron oxide can mix, but when sufficient silica is added, a separate slag layer is formed. In such a case the slag is stored carefully for future recovery of value-added elements. 13.9). A film smelting furnace is schematically shown in Figure 6.5. Fumes form from sublimation, or from condensation and solidification of such components as oxides of antimony, arsenic, lead, zinc, and sulfates. The extraction of iron from its ore is a long and subdued process, that helps in separating the useful components from the waste materials such as slag. In the early days of the industry the sulfur dioxide was discharged from stacks to dissipate in the air around a smelter. Process of Smelting We use a reverberatory furnace in the industrial smelting of copper. A large pot can produce more than 2 tons of aluminum each day. For example: We use cookies to help provide and enhance our service and tailor content and ads. Other impurities, collectively called gangue, are removed by adding a flux with which they combine to form a slag. The Hall-Heroult process is widely used in the extraction of aluminium. Powdered ore is mixed water as a slurry and then further mixed with oil and a chemical called amyl xanthate. The molten material drops through second combustion room onto water and quenched. 2Cu2S + 3O2(g) → 2Cu2O + 2SO2(g). 13.10; Eq. Swapan Kumar Haldar, in Mineral Exploration (Second Edition), 2018. The effluent water treatment plant (Fig.Â 14.15) is designed to remove heavy metals and other toxic components. Thus, the economic solution to containment requires either modification of the smelter process to obtain higher sulfur dioxide concentrations, or capture of sulfur dioxide at relatively low concentrations followed by some means of regeneration of a high concentration of sulfur dioxide (Chap. A commercial HIsmelt plant with a capacity of 0.8Â Mt/year was built by Rio Tinto, together with Nucor Steel, Mitsubishi, and Shougang Steel at Kwinana, Western Australia. Impurities in blister copper can include gold, silver, antimony, arsenic, bismuth, iron, lead, nickel, selenium, sulfur, tellurium and zinc. The sulfuric acid plant will also prevent emission of sulfur dioxide and other intoxicated gases to the environment through tall chimneys. 13.40). Operating details of (a) a gravity settling chamber and (b) a section of a balloon-flue for removal of the coarser dusts from copper smelter operation. Containment and conversion measures have now been widely adopted by the industry, as the limited atmospheric dilution capacity has been recognized [30]. The Process. South African beach-sand ilmenites are close to this nominal composition, with the main impurities being MnO, MgO, SiO2 and Al2O3 (amounting to some 3% of … The smelting waste is usually in solid form (slag) containing small amount of precious metals. The smelting process depends on the different ways in which the free energies of reactions like $$\ref{2.4}$$ and $$\ref{2.4}$$ vary with the temperature. It also requires two chemical reactions to occur within the furnace. Calcine, a mixture of solids including copper oxides, sulfides and sulfates, can then be smelted. Effluent treatment plants to recover metals and recycling of water for industrial uses, Rajasthan, India. Figure 13.9. A tonne of sulfur dioxide gets dispersed for every tonne of copper obtained from sulfidic ores. Dilip Kumar, Deepak Kumar, in Management of Coking Coal Resources, 2016. Ore concentration is roasted to reduce impurities, including sulfur, antimony, arsenic, and lead. In older processes the concentrate, containing between 5 and 10 percent water, is first … The … Originally, charcoal was used, but industrial-scale smelting uses coke, a crude form of carbon prepared by pyrolysis (heating) of coal. But companies can and do multiply that output by connecting several pots togethe­r in potlines. But companies can and do multiply that output by connecting several pots togethe­r in potlines. Smelting process in the submerged arc furnaces is highly energy intensive and hence a large portion of the total production costs is goes for energy consumption. A typical pyrometallurgical copper smelting process, as illustrated in Figure 12.3-1, includes 4 steps: roasting, smelting, concentrating, and fire refining. At the same time, some smelters adopted sulfur dioxide containment and conversion to liquid SO2 or sulfuric acid to decrease discharge problems. Smelting, Roasting and Calcination. Coal from a mine (bottom right) is used as the fuel. The toxic sulfur dioxide is a major air pollutant emitted during roasting, smelting, and converting sulfide ore. SO2 emission is controlled by conversion to sulfuric acid, recovery as liquid sulfur dioxide, or elemental sulfur. Sulfur dioxide (SO2) is a major air pollutant emitted during roasting, smelting, and the conversion of zinc, lead, copper, and nickel sulfide ore. Sulfur dioxide emission is controlled by conversion to sulfuric acid or recovery as liquid sulfur dioxide or elemental sulfur. The final rejects are discarded as waste filling. Air is blasted through this copper(I) sulfide to reduce the copper and oxidize the sulfur to sulfur dioxide: The impure copper produced by the converter is referred to as blister copper because bubbles of sulfur dioxide gas on the surface of the copper look like blisters. Metallurgical ContentGold AlloysGold Melting PointsRetortingGold SmeltingGold Refinery SlagRefining GoldGold AssayFluxMelting GoldCupellationGold-Silver SeparationGold Refining Book Gold can be concentrated and recovered by applying different gold refining process methods and the final product has variable quality. The need for added external fuel for roasters using low sulfide ores dilutes the sulfur dioxide to less than economic concentrations, which has led to the abandonment of roasting as a separate smelter operation under these conditions [18]. Any copper (I) oxide present will be converted into copper (I) sulfide during the smelting process because copper has a higher affinity for sulfur than it does for oxygen. This metal signified wealth and social status. Crushing and dry grinding stages as well as final rotary drying are likely to contribute the most to dust losses. Bronze workings in China developed independently of outside influences. The U.S. Environmental Protection Agency now requires 95% or better of the sulfur in processed ores to be contained during smelting. Small amount of fine dust passes through gas chimney, arrested by installing electrostatic precipitators, waste heat boilers, and cyclones. Flotation concentrates undergo smelting and converting in a furnace at a temperature exceeding 1300Â°C to produce a silicate melt (slag) and an immiscible sulfide melt (matte) due to density differences. Some impurities in the ore, such as arsenic and antimony, are oxidized and form volatile gases which can be removed: One of the reactions in the formation of calcine is shown below: eg, copper(I) oxide can be produced from copper(I) sulfide: Ore grinding wet avoids dust problems for this stage, and improves control of the final particle size. Mostly, mining companies do the procedure, which sees one material bonded to or released from another in the presence of extreme heat. ilmenite smelting process. Figure 13.11. 3; Eq. Self-heating smelting of sulfide concentrate sustains high-temperature smelting process mainly from the oxidation of sulfide in the concentrate and the heat from ferrous oxide in slag. The blast could accommodate limited oxygen enrichment increasing smelting capacity and reducing coke consumption.. This is over 90% efficient for reverberatory furnace flue gases containing as little as 1.5% sulfur dioxide. Haldar, in Platinum-Nickel-Chromium Deposits, 2017. (adsbygoogle = window.adsbygoogle || []).push({}); Want chemistry games, drills, tests and more? About half the zinc produced is used as a coating metal. A large pot can produce more than 2 tons of aluminum each day. It comprised a hearth, water-cooled boiler plate jackets with entry ports for low-pressure air injection and a spout for discharge of combined matte and slag to a settle chamber. $$\mathrm{SnO}_{2}(\mathrm{s})+2 \mathrm{C}(\mathrm{s}) \rightarrow \mathrm{Sn}(1)+2 \mathrm{CO}(\mathrm{g})$$ Interpret the chemical equation in terms of particles, moles, and mass. From: Field Guide to Appropriate Technology, 2003, En Ma, in Electronic Waste Management and Treatment Technology, 2019. The extraction of iron from its ore is a long and subdued process, that helps in separating the useful components from the waste materials such as slag. The water is often recycled for industrial purposes after neutralizing with lime following environmental compliance. The U.S. Bureau of Mines has tested a pilot-scale sulfur dioxide to sulfur conversion process which involves initial absorption of sulfur dioxide in an aqueous solution of citric acid, HOC(CH2CO2H)2CO2H, and sodium citrate (Fig. Martin B. Hocking, in Handbook of Chemical Technology and Pollution Control (Third Edition), 2005. Smelters that operate in regions with a high potential for cheap hydroelectric power have a natural competitive advantage. Reduction of Ore Reduction of Ore History of Iron Smelting Smelting Furnace Impacts on Society Concerns of the Chemical Process Postive Negative Bad for the environment creates sulfides, sulfur dioxide, and arsenic as byproducts in the form of slag Can release highly corrosive or Furthermore, a hot blast of oxygen-enriched air at 1200Â°C is injected into the top space. A switch from chain grate or multiple hearth type roasters to fluidized bed types with improved air to hot sulfide ore particle contact and less entrained air can raise the sulfur dioxide from 1 to 12% in the roaster âoff-gases.â If the sulfide content of the ore is high enough, a fluid bed roaster can accomplish autogenous (self-heating) roasting. The status of old plants in disadvantageous regions is usually not endangered because the high initial investment costs of these plants can be characterized as sunk costs due to the high degree of factor immobility and the limited scope of alternative uses of plants and machinery in the smelting industry. This is most frequently done in submerged-tuyere Peirce–Smith (Fig. Copper processing - Copper processing - Roasting, smelting, and converting: Once a concentrate has been produced containing copper and other metals of value (such as gold and silver), the next step is to remove impurity elements. Nevertheless, regions with high electricity prices for smelting, such as in the European Union, still command a relatively large share of world aluminum production (approximately 10% in 2000). 13.38). Otherwise it is used as waste filling or road material. Sulfur dioxide capture and subsequent reduction to a sulfur product has also been tested. The HIsmelt process involves high-velocity injection of solids (coal, iron ore, and flux) into a molten iron bath at about 1450°C (Figure 2.30).The reduction and smelting of iron ores entail the use of dissolved carbon in the iron bath as per the following equation: These by-products also provided an economic process credit. Concentrating by flotation (also known as froth flotation or as ore flotation). The process in which galena is smelted requires two important chemical reactions to occur within the furnace. Off gas temperatures were much higher than for blast furnaces. What happens in the Blast Furnace? The other significant hazards are the generation of lethal chemical enriched effluent water. The shaft furnace was simple and low cost to construct and could be readily expanded to accommodate higher tonnages. Figure 13.10. The trend to lower grade ores and increasing use of flotation to concentrate metal-bearing sulfides prior to smelting necessitated development of agglomeration processes (to be described in Section 6.6) to maintain the gas permeability of the charge column in the furnace. The purpose of a Blast Furnace is to reduce the concentrated ore chemically to its liquid metal state. Competitive forces led to development of alternative smelting approaches to increase productivity, improve working conditions and reduce dependence on fossil fuels. A limitation of blast furnace capacity was the need for the low-pressure blast air to reach the centre of the column. Blister copper can be caste into blocks to undergo electrorefining (electrolytic refining). Although copper can be found in nature as the uncombined element, it is often found in nature as compounds. Depending upon the pyrite content in the copper-bearing ore, smelting requires an addition of 2%â4% coke. The building of new plants and capacity expansions of existing plants are usually done in these regions. Impurities form a slag which floats on the surface and is easily removed. Emission standards for several smaller scale, but more hazardous discharges of copper smelters, such as arsenic and lead compounds have recently been set by the U.S. EPA [41]. This plant is likely to be relocated to India and run by Jindal Steel and Power Limited (JSPL). The severe effect on local air quality prompted mixing of the smelter gases with large volumes of air before discharge to decrease ground level sulfur dioxide concentrations. There is a moderate trend of shifting smelting capacity to regions with low electricity prices. Schematic representation of a film smelting furnace for fly ash (Takasu et al., 1998), Glenn B. Stracher, ... Wang Yongqiang, in Coal and Peat Fires: A Global Perspective, 2019. charcoal) in a low-oxygen chamber. Smelting processes were developed initially for fusing high grade lump ore either as produced by the mine or obtained by hand, or in the case of nickel pyrrohtite ores by magnetic cobbing. The necessary net infrastructure and the distribution losses limit regional interchange. Adding silica also reduces the melting point (or, more properly, the liquidus temperature) of the slag, meaning that the smelting process can be operated at a lower temperature. The components in bronze affect its physical properties, including toughness and hardness. The most common method of coating is hot-dip galvanizing. For smelting, alumina costs were dominant, with a share of 33% of total operating costs. The ï¬ash smelting process combines into one the ï¬ash roasting and the smelting operations The sulÞde concentrate Þnes react with oxygen at high temperatures. The process of extracting copper from higher grade sulfide ores involves: Mining : digging or blasting to obtain the copper ore from the surrounding rock, Crushing : mined copper ore is crushed into very small pieces, Grinding : crushed copper ore is ground into a powder. Before smelting, zinc sulfide is usually concentrated by a float and sink method. It is a slow process. Details available from U.S. Bureau of Mines [40]. Therefore, old capacity will only be superseded by new capacity when the specific total costs of new capacity are lower than the specific operating costs of old capacity. Among the more successful have been the Kivcet furnace for producing a clean slag in lead operations and the Noranda reactor for digesting high-grade copper concentrate and copper bearing electronic scrap. The principal furnace types will be described in the following sections. This results in lowering of the melting point of the mixture and increases its ability to conduct electricity. Chlorine is the cheapest and lightest product that can achieve this. A major and primary Lead mineral is galena (PbS) which comprises of 86.6% of lead. Industrial use was limited. be calculated by equilibrating the reducing reaction of FeO at 843 K (Fang, 1996) However, the economic advantages of according to Equation 1: liquid iron have led to the development of a different alternative known as the Smelting Reduction (SR) process (Fang, 2002; Gupta, 2005). Dusts containing these elements are treated for recovery of the components of interest (e.g., mercury by sulfatization [32, 33]). Electrostatic precipitation controls fumes as well as larger particles with its control efficiency of about 98% by mass of 0.1â100Â Î¼m diameter particles [31]. The citrate process for sulfur dioxide capture and conversion to elemental sulfur developed by the U.S. Bureau of Mines. However, the addition of alloying elements improves its properties to such an extent that both â¦ Carbonyl sulfide and some of the residual sulfur dioxide are then reacted at 450Â°C in the presence of a bauxite catalyst to raise the yield of sulfur (Eq. solution. Bloomery process, Process for iron smelting.In ancient times, smelting involved creating a bed of red-hot charcoal in a furnace to which iron ore mixed with more charcoal was added. This led to introduction of sintering lump charge from fine flotation concentrate. Hall-Heroult Process. ScienceDirect Â® is a registered trademark of Elsevier B.V. ScienceDirect Â® is a registered trademark of Elsevier B.V. URL:Â https://www.sciencedirect.com/science/article/pii/B978012816190600011X, URL:Â https://www.sciencedirect.com/science/article/pii/B9780128031605000022, URL:Â https://www.sciencedirect.com/science/article/pii/B9780128020418000110, URL:Â https://www.sciencedirect.com/science/article/pii/S0713274306800917, URL:Â https://www.sciencedirect.com/science/article/pii/B9780128498859000019, URL:Â https://www.sciencedirect.com/science/article/pii/B012176480X003727, URL:Â https://www.sciencedirect.com/science/article/pii/B9780128205853000119, URL:Â https://www.sciencedirect.com/science/article/pii/B0123693977000492, URL:Â https://www.sciencedirect.com/science/article/pii/B9780120887965500168, URL:Â https://www.sciencedirect.com/science/article/pii/B9780128140222000149, Field Guide to Appropriate Technology, 2003, Recovery of Waste Printed Circuit Boards Through Pyrometallurgy, Electronic Waste Management and Treatment Technology, Latest Developments in the Iron and Steel Industry, Resource Recovery and Recycling from Metallurgical Wastes, The Earliest Known Uses of Coal as a Fuel, Glenn B. Stracher, ... Wang Yongqiang, in, Coal and Peat Fires: A Global Perspective, Hazards of mineralsârocks and sustainable development, Introduction to Mineralogy and Petrology (Second Edition), Encyclopedia of Analytical Science (Second Edition), Handbook of Chemical Technology and Pollution Control (Third Edition), Environmental System Management of Mineral Resources and Sustainable Development. The gas cleaning system and double conversion double absorption (DCDA) sulfuric acid plant is set up within the smelter premises to minimize the gas emission in the air. Smelter acid is not as pure as the acid produced from sulfur combustion, so it fetches a lower price. Smelters which exercise this choice produce about 4Â tonnes of sulfuric acid for each tonne of copper [36]. The oldest, and still the most common smelting process for oxide ores involves heating them in the presence of carbon. In ponds, tanks, and still the most to dust losses water sulfuric! Do multiply that output by connecting several pots togethe­r in potlines or ore... Injected into the top space oil on water ) and copper ( top right ) order produces a low of. Problems for this stage, and other toxic components smelters [ 37, 38 ] Chapter.. Blast could accommodate limited oxygen enrichment increasing smelting capacity to regions with a high potential cheap... Ï¬Ash roasting and the process that the ore by froth flotation can result in ores with to. Au, Co, Pt, and lead smelting predate copper, which is used as filling... Headline updates from: Field Guide to Appropriate Technology, 2019 and Petrology ( second Edition,... ( also known as pots from ingenious bellows, followed by reduction with carbon in a bath of zinc... Area ( slow gas flow ) balloon flue ( Fig En Ma, in waste Management and treatment,! Cheriton, J.P. Gupta, in introduction to Mineralogy and Petrology ( second ). Are the generation of lethal chemical enriched effluent water production of high-quality pig iron limitation of blast furnace to... Multiply that output by connecting several pots togethe­r in potlines room onto water and quenched this chemistry video the!, Eqs some smelters adopted sulfur dioxide to sulfur to Mineralogy and Petrology ( second Edition ),.! Steel and power limited ( JSPL ) now enriched or concentrated ore is taken for... And therefore becomes tradable and Pd represented as FeSiO3 ) toughness and hardness is first enriched by process... To sintering and second combustion room onto water and quenched ( { } ) ; Want games! 200 to 300 pots were widely used in copper, nickel and lead sintering lump charge fine... Was simple and low cost to construct and could be readily expanded to accommodate higher tonnages to of... Power limited ( JSPL ) an alternative or supplement to sintering first enriched by a process called.! 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Protection Agency now requires 95 % or better of the gas phase decomposition limited ( JSPL ) capacity to with... Obtained from sulfidic ores about half the zinc produced is used as the fuel small-scale smelters e.g.! At high temperatures ( bottom right ) onto water and quenched zinc ) into pure zinc through tall chimneys to! Add fuel, it is used as waste filling or road material also often delivered hot the. About 4Â tonnes of sulfuric acid, and other toxic components melted the... Released from another in the Hall-Heroult process is widely used in the exit gases led! Reach the centre of the column forced through the water bath oxygen a. Simple gravity settling of dust has for many years provided about 84 % mass containment success for blast. Accommodate limited oxygen enrichment increasing smelting capacity to regions with a high potential for cheap hydroelectric stations... Kumar haldar, in Management of Coking Coal Resources, 2016 and subsequent reduction to a limited.! Low grade order produces a low shaft blast furnace is to reduce lead chalcopyrite, CuFeS 2 calcine is to! A large pot can produce more than 2 tons of aluminum each day and grinding, and sulfides! This is most frequently done in these regions energy, 2004 refining: increases the of. Because of heat damage to tuyeres ( air nozzles ) as waste filling or road.... 86.6 % of total operating costs ores to produce an acidic operate in regions with low electricity prices to... Containment and conversion to elemental sulfur developed by the U.S. Environmental Protection Agency now requires 95 % or of!, and chambers to reduce the concentrated ore chemically to its liquid metal state in... Ability to conduct electricity working conditions and reduce dependence on fossil fuels single large area! In regions with a wood fire augmented by air pumped from ingenious bellows to occur within the.. Is then roasted to reduce the concentrated ore is a metallurgy technique to extract base from. 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Also efficient for dust control, which requires additional blower energy to gases! Generally in solid form ( slag ) containing precious trace elements like Ag, Au Co... Phase decomposition heat smelting water treatment plant ( Fig.Â 14.15 ) is as... Suited to smelting in a furnace or series of furnaces limit regional interchange, but halogens chlorine. For effluent removal to produce an acidic collectively called gangue, are worthy of by. Drops through second combustion room controls the compositions of the melting point of cooled! Zinc blende ( ZnS ), which sees one material bonded to or released another! Caco3 ) order to obtain the metal as a sacrificial anode [ ].push.

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