production of materials

• Production of Materials


  1. New materials need to be extracted from a raw material source

  2. Processed into a useful form
• Paper and Board


  Made from Cellulose Fibres
• Process to make paper or board from trees

  1. Trees are felled and taken by lorry to a paper mill

  2. The bark is stripped

  3. The wood is cut into small pieces by a chipper

  4. The small bits of wood undergo chemical or mechanical pulping to turn them into a mushy brown pulp

  5. The pulp is washed and bleached to make it white

  6. The pulp is pressed flat between rollers, dried and cut to size
• Pulping


  A very important stage - it converts the wood into individual cellulose fibres
• Mechanical pulping


  Involves grinding down the wood to separate out the fibres
• Chemical pulping


  Involves heating the wood with chemicals - this removes other parts of the wood leaving just the cellulose behind
• Some types of paper and board aren't bleached and remain a brown colour
• Cellulose fibres used for paper and board can also come from other plants like grasses
• Process to make paper and board from other plants

  Similar to the conversion of wood, although no debarking or chipping is required
• Production of corrugated cardboard

  Has an extra stage where the fluted middle layer is stuck to the outer layers to form a laminate
• Process to make timber from trees

  1. Trees are felled and cut down

  2. The bark is removed

  3. The trunk is sawn up in different ways which affects the look and warping of the planks

  4. The wood is seasoned by air-drying or kiln-drying
• Air-drying


  Involves stacking wood up outside or in sheds and allowing air to circulate around it
• Kiln-drying


  Similar to air-drying but done in a heated chamber with fans to circulate the air - makes it faster but requires careful control to avoid damage
• Seasoning makes the wood stronger and less likely to rot
• Conversion of seasoned wood


  Can be made into lots of different useful forms like planed square edge wood, mouldings, etc.
• Medium Density Fibreboard (MDF)

  Uses wood that has been processed to cellulose fibres in a similar way to paper and board production
• Chipboard


  Uses a mixture of dried wood chips, shavings and sawdust - often from waste material
• Production of manufactured boards

  1. The wood mixtures are heated, pressed into sheets and left to dry

  2. Glue (e.g. urea formaldehyde) is added between the layers
• Production of Plywood


  1. Wood is softened, either through soaking in hot water or steaming

  2. Thin sheets are peeled from the softened wood, cut to size and dried

  3. The cut wood is arranged into stacks of 3 or more layers with the grain direction at 90 degrees to the layer above and below

  4. Glue is added between each layer and the sheets are heated and pressed
• Once manufactured boards are dry, they can be trimmed and sanded to give a smooth finish
• Metal


  A rock with enough metal locked up in it to make a profit for the metal to be extracted (separated from the rest of the ore)
• Extraction of metals


  1. Heating the ore in a furnace

  2. Electrolysis
• Extraction of metals from ores

  1. Crushing and heating in a furnace with other materials such as charcoal

  2. Heating under pressure with chemicals to separate aluminium oxide from the mixture, then electrolysis
• Impurities in extracted metals

  Small amounts of other substances that need to be removed before the metal can be used
• Refining of metals


  Several ways to remove impurities
• Casting of refined, molten metal

  Pouring the metal into a mould and allowing it to cool and solidify into the required shape
• Iron


  • Common ore is haematite, main impurity is sand removed by adding limestone during extraction
• Aluminium


  • Common ore is bauxite, gases can be pumped through molten aluminium to cause impurities to rise to the surface
• Zinc


  • Common ore is sphalerite, heated and then cooled to separate it from impurities with different boiling points
• Copper


  • Common ore is chalcopyrite, electrolysis can be used to separate the copper from any impurities
• Tin


  • Common ore is cassiterite, heating the tin can cause some impurities to react and form a substance that can easily be removed, electrolysis can be used to refine the tin
• Crude oil


  Extracted from the ground and taken to a refinery
• Fractional distillation of crude oil


  Heating to separate it into different chemicals called "fractions"
• Monomers


  Chemicals that get joined together to make polymers (plastics)
• Polymerisation


  Monomers join up to make chains called polymers
• Cracking


  Breaking down larger fractions into smaller molecules
• Most plastics are made from crude oil, although some can be made from substances found in plants
• The plastics can then be used, for example cut up into small pieces and moulded into the right shape