Metals

What are metals?

dense, lustrous malleable and good conductors of heat and electricity

The historical development of metals?

• early civilisation used naturally available metals e.g. gold

• over time found that most metals were found as oxides or sulphides

• first metals extracted were the easiest to get, copper

  • major advancement was iron

What is the metallic structure?

• giant metallic structure

• positive metal ions surrounded by a sea of delocalised electrons

  • atoms packed in slip planes which can slide over each other allowing for plastic deformation

What is the metal economy?

• iron and aluminium are the most important, quality, wildly used and easily accessable

  • metals become expensive when they are rare and have specialised properties

The localisation of gold?

• found in rocks by hydrothermal action where it dissolves and recrystallises in quartz veins

• weathering releases small particles into rivers which you can pan out, dense metals stays in the pan

  • low grade ores are chemically extracted

How are low grade gold ores chemically extracted?

• dissolves in potassium cyanide forming soluble ions

  • zinc is used to displace solid gold

What are properties of platinum gold metals

good conductors

catalysts

malleable

corrosion resistant

What are uses of platinum group metals?

• decorative jewellery

  • exhaust and industrial catalysts

What does carbon monoxide do in exhaust gases?

Prevent oxygen from reaching tissues - poison

What do hydrocarbons do in exhaust gases?

carcinogenic

photochemical smog

greenhouse gases

What do oxides in nitrogen do in exhaust gases?

acid rain

photochemical smog

What does oxides of sulpher do in exhaust gases?

acid rain

photochemical smog

What do particulates do in exhaust gas?

lung disease

What are catalytic converters?

• reduce harmful emissions of car exhausts

• have a ceramic block with small holes coated with alumina and barium oxde, trace amounts of platinum rhodium and cerium

• 7000 fold area increase

what are the three ways to catalyticly convert?

Nitrogen oxide - N2 +O2

carbon monoxide - co2

hydrocarbonds - co2+h2o

doesnt work until high temperatures reach

What is better engine management?

• increase efficiency - optimise fuel consumption reducing emissions

• lighter cars- less energy increasing efficiency and range

  • bio fuels, electric vehicles, fuel cells

What is the importance of copper?

• Vivian family of swansea

• electronics

• plumbing

  • catalysts

The natural occurance of copper?

• native copper - 100% red

• culrpite - Cu2O- 88.8% red

  • chalcocite - Cu2S - 79.9% grey

    • chalcopyrite - CuFes2 - 34.6% yellow

What are the economics of copper exploitation?

• only when there is significant demand

• as demand increases and technology improces, grade of ore which can be used decreases

• copper consumption exceeds production becase of recycling efforts

  • now competition of aluminium

What is the mining process of extracting copper?

• ore is extracted and transported from open pits, only high grade order 5-10%

• froth flotation and grinders explot poor grades

  • ore decomposes with heat forming blister copper, SO2 bubbles

What is the process of purifying copper by electrolysis?

• blister copper is the anode, electrode potential is applied to the cell and the blister copper dissolves as copper ions

• ions travel through the electrolyte and are reduced at the cathods as pure metallic copper

  • impurities arent charged so dont move to the cathods, accumulate and pile up beneath the anode

What is the equation for the electrolysis of copper at the anode?

Cu → Cu2+ +2e-

What is the equation for the electrolysis of copper at the cathode?

Cu2+ +2e- →Cu

What is the process for the recovery of copper from leach water?

scrap ion is used to recover copper from lagoons

copper plates out the iron in a displacement reactin at the expense of the iron dissolving

What is the equation for the recovery of copper from leach water?

Cu2+ +Fe → Cu + Fe2+

Why is copper good for electronics?

high electrical conductivity

Why is copper good for plumbing?

malleable and corrosion resistant

Why is copper good for industrial catalysts?

catalytic efficiency

Why is copper good for alloys?

enhances strength and durability

What is bronze?

• allot of copper and tin

• hard

• durable

• corrosion resistant

  • lower mp

What are the stages of extracting tin?

ore producton

reduction

purification

What happens in the ore preperation stage of making tin?

• extracted from cassiterite using carbon in a low oxygen enviroment

  • its crushed to increase the surface area

What happens in the reduction stage of making tin?

• carbon is a reducing agent in a high temperature furnace

• SnO2 + 2C → Sn + 2CO

  • produces molten tin

What happens in the purification stage of making tin?

• distillation - seperates tin as it has a low melting point

  • electrolysis removes any further impurities

What are chemical equation for making bronze?

2Sn + 2Cu → Sn2Cu2

Why is tin a suitable material for solder?

Low melting point

high conductivity

Why is tin used for cans?

• corrosion resistance

  • protects iron and steel from rusting

Why is tin used in alloys?

enhances hardness and durability

Why is tin good for coatings?

prevent corrosion

What is the importance of iron?

• use 1.1 billion tonnes of new iron and 1.6 million tonnes of steel used

  • wide uses low cost

How is iron found?

• abundance in the crust - 34.6% of earth 6.2% of the crust

• commonly found as oxides, haematites and magnetites, ore doesnt exceed 75% iron

• oftern mixed with limestone

What is the historical iron extracting process?

• heat iron with charcoal 1150

• control air flow to maintain temperature

• reduction - Fe2O3 +3C → 2Fe +3CO

  • removal of slag and impurities

What is a blast furnace?

30-40m high steel tower lined with refractory bricks

What is the modern iron extraction process - setting up the blast furnace?

• blast furnace is lined with refractory bricks

• coke is made by the partial coal burning which increases carbon content

• coke limestone and iron ore is added at the top

How is iron extracted using the blast furnace?

• air is blasted into the base

• coke burns releasing CO2 and CO

• CO reduces ore into pig iron

• limestone burns to lime which reacts with impurities to make slag

  • slag is less dense, floats to the top and is tapped off

What are the iron extraction equations?

C + O2 → CO2

CO2 + C → 2CO

Fe2O3 + 3CO → 2Fe + 3CO2

What are the slag formation equations?

CaCO2 → CaO + CO2

CaO + SiO2 → CaSiO3

What are the impurities within pig iron?

• brittle and weak as has 5% C

  • carbon causes weakness, it locks the slip planes preventing bending

How do you lower impurities within pig iron?

beating to produce wrought iron

open hearth/ BOS to make steel

What is wrought iron?

• malleable and high tensile strength

• puddle to remove impurities

  • lowering carbon content increases mechanical malleability but reduces hardness

• removing slag becomes fibrous - improving strength

  • used for shaped metals which require strength

What are properties of cast iron?

good compressive strength

low tensile strength

What are properties of wrought iron?

high tensile strength and ductility

cant be moulded

What is the open hearth process?

• molten iron kept in vaults

• stirred and oxygen removes impurities forming waste and slag

  • slow batch process so isnt economically viiable

What is the basic oxygen process?

• scrap placed into brick lined converter

• pig iron is placed into a converter

• oxygen blown into the melt using a water cooled lance

  • oxygen rapidly converts impurities into gases and more slag by reacting it with lime

What are the equations for the basic oxygen process?

Mn+O2 → 2MO

Si + O2 → siO2

4p + 5O2 → P4O10

Why is the basic oxygen process viable?

Produces 500-900 tonnes per year

What is the process of steel production?

• blast furnace converts raw materials into pig iron

• basic oxygen furnace refines pig iron

• continuous caster/ ladle produces semi finished shapes

  • shapes are rolled and processed

What are the enviromental issues of steel making?

• sulphur emissions

• particulate and smoke emissions

• water pollutionn

• slag - now a aggregate

• steel is easy to recycle

  • CO2

What are the economics of steel making?

• drastic rationalisation

• modern works are integrated

• work sites near harbours for import

  • most goes to automobile and construction

Why are emmisions bad in steel making?

• high CO2 and sulphur

  • use recycled steel, carbon capture technology

Why is pollution bad in steel making?

• water and air from particulates

  • water and air treatment

corrosion and steel?

• rust and enviromental degradation

  • alloy e.g. chromium to prevent direct exposure

Weight and steel?

• heavy

  • high strength low alloy steels

Cost and steel making?

• extensive processing and large scale facilities

  • efficient manufacturing processes and recycling programmes

What are the next steps in the evolution of metals?

• new alloys

• enhance extraction and production processes

  • circular economies