Synthesis of Metals

Synthesis of MetalsGroup 1Trnh Vn Binh Vn CngLng Vit CngNguyn Minh HongV Xun HngL Vit HngABSTRACTSynthesis of Metals has become more and more essential in both Materials Science and Heavy Industry. Different ways of synthesis could result in different properties of Materials. So, lets take a look on this field.

OUTLINESReduction by chemical means:Magnesium (Nguyn Minh Hong) slide 1-13Iron (Trnh Vn B) slide 14-24

ThermaldepositionIron (inh Vn Cng) slide 25-34

Electrolysis of meltsNatri (Lng Vit Cng) slide 35-44

DisplacementTitanium (V Xun Hng) slide 45-52

I. Metals synthesis (Nguyn Minh Hong)Common steps for metals synthesis:

4 main types of metals synthesis:

I. Metals synthesis1. Reduction by chemical means:Taking out the oxygen atom in oxides to form free metallic atoms

Oxide is taken from heating sulfide ores.Reduction agents:

I. Metals synthesisReduction by chemical means:Case study: Magnesium production by Pidgeon processThePidgeon processis one of the methods ofmagnesiummetal production, via asilicothermicreduction.Silicothermic reactionsarethermicchemical reactionsusingsiliconas thereducing agentat high temperature (800-1400C).The basic chemical equation of this process is: Si(s) + 2 MgO(s) SiO2(s) + 2 Mg(g) (high temperature, distillation boiling zone)

I. Metals synthesisReduction by chemical means:Case study: Magnesium production by Pidgeon process

I. Metals synthesis1st step: Mining and crushing of the dolomite:The dolomite is mined and crushed by the supplier at the quarry, and delivered to the Magnesium Plant in 15-25mm granules.Dolomiteis an anhydrouscarbonate mineralcomposed ofcalciummagnesiumcarbonate:CaMg(CO3)2.

I. Metals synthesis2nd step: Calcination of the dolomiteThe chemical formula of the calcination is as follows:

MgCO3.CaCO3 (solid) MgO.CaO (solid) +2CO2 (gas)[+Q]Highly Endothermic Reaction. CO2 Released both from the Reaction, and from Fuel Burned for Process Heat

The dolomite is calcinated by roasting it at 1,100-1,200C to remove the carbon from the magnesium carbonate compound in the form of carbon dioxide.The heat energy required is supplied by gas generated from on-site coal-to-gas converters.The calcined dolomite is then delivered to a store house for cooling.

Calcined dolomiteI. Metals synthesis3rd step: Preparation of Ferrosilicon alloy The chemical formula is as follows:

Fe2O3 + 4SiO2 + 11C 2(Fe)Si2 + 11COFerrosiliconis aferroalloy, analloyofironandsiliconwith an average silicon content between 15 and 90 weight percent. It contains a high proportion of ironsilicides. Ferrosilicon is produced by reduction ofsilicaorsandwithcokein presence of iron. Typical sources of iron arescrap iron,millscale.Ferrosilicons with silicon content up to about 15% are made inblast furnaceslined with acidfire bricks. Ferrosilicons with higher silicon content are made inelectric arc furnaces.

I. Metals synthesis4th step: Making briquettesThe reducing agent, ferrosilicon, is crushed to below 10mm and is mixed with the calcined dolomite and fluorite powder to certain ratios controlled by a microcomputer.The mixed material is then milled by a ball miller to form powder of granules below 120[mm] and is delivered to airproof storage by conveyer belt.The mixed powder is compressed into a briquette and is delivered to reduction workshop for deoxidisation.

I. Metals synthesis5th step: Silicothermic Reduction of MgO by Ferrosilicon

The chemical formula of the deoxidisation is as follows:

2MgO + 2CaO + (Fe)Si = 2Mg(g) + Ca2SiO4(s) + FeHighly Endothermic Reaction

The briquettes are loaded into retorts (46 for each reduction chamber) and deoxidization takes place (under a vacuum) at temperatures of between 1,200-1,250C.

The process is performed under a vacuum to reduce the necessary reaction temperature and to avoid re-oxidisation of the magnesium. The heat energy required is supplied by gas generated from on-site coal-to-gas converters.

The magnesium gas, once cooled, forms solid crowns of crude magnesium crystals at the top of the retort. The deoxidization process takes about 10 hours. When finished, the raw magnesium is removed and is delivered to the refinery workshop for purification.

11I. Metals synthesis6th step: Refining and CastingAfter cleaning, the magnesium crowns are melted at a temperature controlled at between 670-700C, burning coal gas as the heat source.Once purified, the temperature is briefly raised to 720C and then allowed to drop to 710C, at which time casting commences, using a transfusion pump, pouring machine and continuous casting machines to form solid magnesium ingots.The magnesium ingot is cleaned, finished, inspected, measured and packed while it is hot, and then delivered to the finished product storeroom for sale.

Magnesium die casting machine12Strong Revival of the Pidgeon Process since about 20 Years. About 73% of World Primary Magnesium Production now in China13Reduction By Chemical means (Trnh Vn B)Case study : Iron.Raw material: Ore,Coke, fluxPreparation raw material:Ore : Contain high iron oxides (Fe2O , Fe3O4 ,FeOOH) and oxides metal (SiO2, Mno, Al2O3, P2O 5 , CaO, FeS, Ti,C) - If iron rich ore can be charged directly into a blast furnacewithout any further processing - If lower iron content must be processing : beneficiated, concentration processdifferences.Reduction By Chemical means Beneficiated: is processes extractedorefromminingisseparatedintomineralandgangue -Ore was crushed and grind into a powder .Since ore contain oxides is soft so it have smaller size than rock. So we can separate by screening, hydraulic, classifiers

Concentration: Flotation and electrostatic concentration utilize physicochemical -Based on principles of solid particles of different sedimentation rate. due to the specific gravity of iron minerals higher than gangue minerals ,

Reduction By Chemiscal meansCoke : produced from a mixture of coals, It is crushed and ground into a powder and then heat into an oven, The oven in condition absence of air and temperate reached 1000 C . so most of the volatile matter such as oil and tar are remove after 18 to 14 hourAfter that, coke is cooled and screened into pieces (1.0 to 4.0 inch) contain 90-93% carbon Coke with a high energy value provide permeability, heat and gases which are required to reduce and melt the iron ore, Reduction By Chemical meansFlux : limestone (CaCO3). The limestone is removed from the earth by blasting with explosives.After that,it was crushed and screened to a size that ranges from 0.5 inch to 1.5 inchThe Flux is melted to become the slag which removes sulfur and other impuritiesReduction By Chemical meansBlast furnaceThe purpose of a blast furnace is to chemically reduce and physically convert iron oxides into liquid iron The height is typically 20-30 metres.Iron ore, coke and limestone are charge into the topThe final product require 6 to 8 hoursThe hot air was blown into the bottom to the top in 6 to 8 s after going through numerous chemical reactions

Reduction By Chemical meansProcessFomation of reducing agent.C + O2= CO2+ Heat about 1700 CCO2+ C = 2CO about 1000 CThe product CO is necessary to reduction the iron ore

Reduction of Iron oxides:3 Fe2O3+ CO = CO2+ 2 Fe3O4 about 400 CFe3O4+ CO = CO2+ 3 FeOabour 700 CFeO + CO = CO2+ FeFeO + C = CO + Fe about 900C

Reduction By Chemical meansImpurities source: Purpose: Reduction apart oxides in Iron, purpose is decrease content of impurity in IronMno + C = Mn + CO about 1200 CSiO2 +2C = Si + 2COP3O4 +4C = 3P +4Co

Some Oxide cant reduction as Al2O3 ,CaO . It was form lag in next step. ProcessReduction By Chemical means ProcessFomation of slag:CaCO3= CaO + CO2 about 700 C

The CaO formed from this reaction is used to remove impurities from the iron forming Slag.

FeS + CaO + C = CaS + FeO + CO about 1600 CP2O 5 + 3CaO = Ca3(PO4)2SiO2 + CaO = CaSiO3Al2O3 +CaO

Motel slag foat on top of motel iron so we can saparate Iron and slag21Reduction By Chemical meansIron (Fe)= 93.5 - 95.0%Silicon (Si)= 0.30 - 0.90%Sulfur (S)= 0.025 - 0.050%Manganese (Mn)= 0.55 - 0.75%Phosphorus (P)= 0.03 - 0.09%Titanium (Ti)= 0.02 - 0.06%Carbon (C)= 4.1 - 4.4%Final productReduction By Chemical meansPropertiesPhysical propertiesPhasesolidDensity7.874 gcm3Meltingpoint1811K,1538C,2800FBoilingpoint3134K,2862C,5182FHeatoffusion13.81kJmol1Heat of vaporization340 kJmol1Molar heat capacity25.10 Jmol1K1Phase : SolidMedium reactive elemrnt so it exist in naturalCan be change properties by the methods. -Deformation plastic -Solution hardening (Carbon..) -Heat treament -Grain refinement

Many Application23Reduction By Chemical meansApplication of IronIron is one the most useful metals

Carbon steels applicationsLow Carbon Steels : Ductile-Building steelsMedium Carbon: High strength-Machine steels: (gears, structural fixtures)-High Carbon : high hardness-Tool steels: :(drills ,saws, knife blades and bearings)

Carbonyl iron (inh Vn Cng)Carbonyl iron is a higly pure (97-99%) iron, prepare by decomposition of purified iron pentacarbonylgrey powder, spherical microparticlesmost of the impurities are C, O, N

Raw materialSponge iron (direct-reduced iron): fines (90-94%)

Direct reduction method Natural gas is partially oxidized (with heat and a catalyst):2 CH4 + O2 2 CO + 4 H2These gases are then treated with iron ore in a furnace, producing solid sponge iron:Fe2O3 + CO + 2 H2 2 Fe + CO2 + 2 H2OSilica is removed by adding a flux, i.e. limestone, later.

Iron ores ore pellets

Sponge iron

DRM(800-1050oC Iron pentacarbonyl synthesis and purificationIn the reactor, iron powder reacts with excessive flow of CO (at the pressure from 5 to 30 MPa, typically 20 MPa) to form iron pentacarbonyl

Fe(powder) + CO(g) -> Fe(CO)5(liquid)(20MPa,150-200oC)

Ni, Cr, Mo impurities also react with CONi + CO -> Ni(CO)4Cr + CO -> Cr(CO)6

Iron pentacarbonyl synthesis and purificationMultiple distillation seperate iron pentacarbonyl from the other volatile carbonyls, and also other impurities such as lubricant oil, sulfur or waterBy different boiling points: 43oC(Ni(CO)4), 103oC(Fe(CO)5), 210oC(Cr(CO)6), lower the temperature of the mixture gas to extract Fe(CO)5(liquid)

Carbonyl powder synthesisFe(CO)5 is evaporation, then decomposition to form pure Fe powder

Fe(CO)5(g,pure)-> Fe(powder) + 5CO(g)(200oC,keep heating)

CO is collected and reused in the carbonyl preparation process.

ProcessingFinishing iron powder needs:MillingClassifyingHydrogen annealing: a heat treatment to eliminate hydrogen. Fe is kept in an hydrogen annealing oven several hours at 200-300oC. Hydrogen is removed by effusionCoating: coat carbonyl iron powder with mica or glass ball for stability and insulation

Production schematic

AdvantagesThe purity of carbonyl iron is (97-99%) much higher than conventional iron (include C, S, Mg, Mn, Ni, Mo, W) which is produced by blast furnacePowder form of carbonyl iron is very applicable for advance materials, carbonyl process is the only way to produce itCan be combined with carbonyl nickel production processes

DisadvantagesPentacarbonyl iron is very toxic, reactive, volatile and flammableThe process need high technology, high-cost equipments and environment safety procedureThe raw material is iron powder which is relatively expensiveElectrolysis of melts (Lng Vit Cng)Concept:process redox occur in surfaces when has direct current go past substance dissociative melts Melted compounds salts, base, oxides of most reactive metal ( Na, Ka, Al)Down's process: molten electrolysis NaCl35Raw material & propertiesNaCl: common salt-dry salt; anhydrous form; Melting point: 801CRaw material: pure NaCl(s) a mixture containing sodium chloride, (NaCl + KCl + KF or NaCl + CaCl2) is employedto reduce the temperature required to keep the electrolyte liquid. the mixture can be kept liquid at temperatures around 600 C.Modern Downs cells operate at 25 to 40 kA and at potentials of 7 to 8 volts

The reasons for lowering the temperature are:It is difficult to maintain a high temperature of 1085K.Sodium is volatile at this temperature and so a part of the metal formed may vaporize.At this high temperature chlorine produced as a by product corrodes the vessel.Metal at this temperature will be in a colloidal state and its separation will be difficult

Processesit willconduct electricity.Electrolysisseparates themolten ioniccompoundinto itselements.Cathode ( )is steel; Anode ( + ) graphiteElectric require 40000 amps

Sodiumchloridemust beheateduntil it ismolten, because sodiumchlorideisdissolvedinwater.38

cathodeThe electrode of an electrochemical cell at which reduction occurs.anodeThe electrode of an electrochemical cell at which oxidation occurs.Reaction at 600 CProcesses 2| Na++ e Na 2Cl- Cl2+ 2eProduces after reactionThe calcium does not enter into the reaction because its reduction potential of 2.87 volts is higher than that of sodium. produces chlorine as a byproductSodium, having low density than its salt, floats and can be easily collected over keroseneDisadvantage & Advantages Disadvantage :lots of electrical energy input Advantage of Down's processlargely and pure metal, Sodium metal obtained has high degree of purity (99.5%).The starting material, sodium chloride is very cheap.

Bars Sodium & spices Sodium

Properties of sodiumPhase: solidmore reactive element so it does not exist in naturalsoft metal that can be readily cut with a knifereact water at room temperature

Sodium-vapor lamp is agas-discharge lampthat usessodiumin an excited state to producelight. App of sodium

Displacement Reaction (V Xun Hng)Case Study: Titanium

Overview + Single - Displacement Reaction is a type of redox chemical reaction when an element is replaced by another in a compound.A + B - C A - C + B (A is more reactive than B) + Reactivity Series:

K Na Ca Mg Al C Zn Fe Sn Pb H Cu Ag Au Pt

More reactive Less reactiveExample

+ Place the iron nail in a test tube and add copper sulfate solution so that one half of the nail is covered. + The solution turns green and copper is formed.

Fe + CuSO4 Cu +FeSO4

Case Study: TitaniumTitanium is corrosion resistant, very strong and has a high melting point (1668C). Low density (about 60% that of ion). It is also the tenth most commonly occurring element in the Earth's crust. That means titanium should be a really important metal for all sorts of engineering applications. Titanium is very expensive and only used for rather specialized purposes.

PreparationOre: Rutile (TiO2)

Reducing Agents:

Sodium (Na)

or Magnesium (Mg)

49Titanium extraction

Conversion of titanium(IV) oxide, TiO2, into titanium(IV) chloride, TiCl4The ore rutile (impure titanium(IV) oxide) is heated with chlorine and coke at a temperature of about 900C.TiO2 + 2Cl2 + 2C TiCl4 + 2CO

Reduction of the titanium(IV) chloride+ Reduction by sodium : The titanium(IV) chloride is added to a reactor in which very pure sodium has been heated to about 550C - everything being under an inert argon atmosphere. During the reaction, the temperature increases to about 1000C.TiCl4 + 4Na Ti + 4NaCl

+ Reduction by magnesium : The method is similar to using sodium, but this time the reaction is TiCl4 + 2Mg Ti + 2MgCl2

Products+ For Sodium:- Everything has cooled (several days in total an obvious inefficiency of the batch process) The mixture is crushed and washed with dilute hydrochloric acid (HCl) to remove the sodium chloride.+ For Magnesium:The magnesium chloride is removed from the titanium by distillation under very low pressure at a high temperature.ApplicationsTitanium is used, for example:- in the aerospace industry - for example in aircraft engines and air frames;- for replacement hip joints;- for pipes, etc, in the nuclear, oil and chemical industries where corrosion is likely to occur.