Presentation on theme: "Extractive Metallurgy"— Presentation transcript:
1 Extractive Metallurgy Metallurgy for the Non-Metallurgists
2 Learning ObjectivesUpon Completion of this lesson, you will be able to:List several methods for concentration of ores and the methods and techniques for mineral processingDefine hydro-, pyro-, and electrometallurgy the techniques to provide the energy necessary for extraction of metals from metallic oresDescribe the processes of oxidation and reduction and understand that oxidation of metals is a naturally occurring processOutline the steps in production of pig iron and steel
3 Mineral ProcessingEarth’s crust contains oxygen containing minerals and sulfur containing mineralsAn ore general is part of the crust that contains valuable minerals and metalsMineral Processing extracts the valuable minerals from the rocks without changing them
4 Processing Techniques Crushing—breaks down the ore rock to 4-6 inch piecesGrinding—breaks up the crushed oreComminution—the process of crushing and grinding the oreClassification—the separation of particles according to their settling rates in a fluid
6 Three basic types of crushing and grinding circuits: (a) conventional, (b) autogenous, and (c) autogenous with separate fine grinding
7 ConcentrationGravity Devices—minerals are usually denser than the waste rock of the oreMagnetic Devices—Iron minerals are magneticElectrostatic Devices—crushed ore is exposed to an ionizing electrodeFlotation—separates wettable from non-wettable particals
8 Spiral (mechanical) classifier. Courtesy of Mine and Smelter Corp., division of Kennedy Van Saun Corp.
9 Denver flotation cell mechanism. Courtesy of Joy Manufacturing Co.
10 Dewatering of Concentrate First the concentrate is thickenedThickened concentrate is sent to vacuum filter to reduce moistureThe ‘cake’ then goes to a smelterConcentrated ore goes through a chemical process to extract the metalEnergy is used to extract the metalPyrometallurgy-heatHydrometallurgy-wet chemicalsElectrometallurgy-electrical energy
11 Cutaway view of thickener. Courtesy of Environmental Equipment Div., FMC Corp.
12 Cutaway view of drum filter with scraper discharge. Courtesy of Filters Vernay.
15 Flow diagram for production of 900 kg (one ton, 2000 lb) of pig iron (when molten, “hot metal”) and further processing to steel
16 Oxidation and Reduction Chemical processes involve reactions between mineral constituents and the environment that surrounds the mineralOxidation involves the reaction between the metallic elements and oxygen (ex. Rusting of steel)Oxidation reactions release heatOxidation refers to a loss of electrons from the metalOxidation is an increase in valence because of the loss of electronsMetal oxide is reduced to a metal when it regains its electrons
18 Preparation for Pyrometallurgical Reduction Drying—heating or vacuum systemCalcination—high temperature operationRoasting—heating to just below the melting point of the oresSintering—variations of roasting
19 Pyrometallurgical Reduction Pyrometallurgical equation: MX + R + heat = M + RxReverberatory Furnaces—rectangular with an arched roof (figure 11)Blast Furnaces—good for oxides that are not highly reactiveIron Blast Furnace (figure 12)
20 Schematic views of copper matte smelting reverberatory furnace
21 Schematic illustration of an iron blast furnace, showing temperatures and chemical reactions
22 Iron and SteelmakingConcentrated ore, coke, limestone and other solid materials are loaded in the top of the furnaceThese materials are called the “burden”Burden meets air as it moved down furnaceCarbon burns, producing heat and COBurden becomes molten as it reaches the hearthSlag is removed and the metal hardensSteel is Iron combined with less than 2% carbonPig iron is normally the product of the blast furnace—pig iron is iron with greater than 2% carbonAn Electric Arc furnace is also used to make steel (figure 14)
30 Vertical Zinc RetortVertical (New Jersey) continuous zinc retort
31 Pyrometallurgical Refining Trying to remove impuritiesRefining with Gaseous Reagents (oxygen is an example of a gaseous reagent)Passing oxygen through molten pig iron removes some of the carbonChlorine is a gaseous reagent for refining
32 Hydrometallurgical Processes Leaching—a separation process using liquidsGoal of Leaching:Production of a pure compoundProduction of a metal from impure metal or metal compoundsDirect production of a metal from an oreMethods of LeachingSitu LeachingHeap LeachingAgitation Leaching
34 Pahuca Tank AirflowSchematic of airflow in a Pachuca tank
35 Purification Chemical and Physical Treatment Solvent Extraction PrecipitationResults in physical changeSolvent ExtractionUse an aqueous and organic solutionSolvent removes metal ions from the aqueous solutionIon ExchangeExchanges ions between the aqueous solution and a solid
36 The Leaching/Electrowinning Process Simplified block diagram showing the cyclical nature of the leaching/electrowinning process
37 Hall-Heroult Aluminum Cell Hall-Héroult aluminum production cell with self-baking anodes