Metallurgy

• Minerals


  Solid element or compound which occurs naturally in the Earth's crust
• Ore


  A mineral from which metals can be extracted profitably
• All ores are minerals but not all minerals are ores
• Alloy


  Mixture of metals
• Native Metals


  Metals found as the element in nature
• Slag


  By-product created during metallurgical and combustion processes due to impurities present in the metals or ores being treated
• Metallurgy


  The science and technology of metals and alloys
• Branches of Metallurgy

  • Extractive Metallurgy
  • Physical Metallurgy
  • Chemical Metallurgy
  • Mechanical Metallurgy
  • Welding Metallurgy
  • Corrosion Metallurgy
  • Metallurgical Engineering
• Metallurgy


  The art and science of extracting metals from their ores and modifying the metals for use
• No substance has been as important as metal in the story of man's control of his environment
• Gold


  Pure gold has the quality of softness, it can be easily shaped by hammering, but this malleability makes it useless for practical purposes
• Copper Age


  Cu exists in nature in a pure form, and which can also be bashed into new shapes - with less ease than gold, for it is much harder, but with more practical results
• Chalcolithic Period


  Intermediate period between the Stone Age and the first confident metal technology (the Bronze Age), from the Greek chalcos 'copper' and lithos 'stone'
• Bronze Age


  Ores of copper and tin are found together, and the casting of metal from such natural alloys may have provided the accident for the next step forward in metallurgy. Bronze is harder than either copper or tin on its own
• Iron Age


  Iron is the most abundant metal in the earth's surface, but much more difficult to work than copper or tin. Primitive furnaces could not extract it in pure form from its ore, so it had to be turned into a useful metal by repeated heating and hammering
• Steel


  Discovered that if iron is reheated in a furnace with charcoal (containing carbon), some of the carbon is transferred to the iron, hardening the metal. Quenching the hot metal in water further improves the effect
• Mineral Processing


  1. Sampling and Analysis

  2. Comminution

  3. Concentration

  4. Dewatering
• Mineral Processing


  The art of treating crude ores and mineral products to separate the valuable minerals from the waste rock, or gangue
• Sampling and Analysis


  1. Sampling

  2. Chemical Analysis

  3. Mineralogical Analysis

  4. Size Analysis
• Sampling


  Removal from a given lot of material a portion that is representative of the whole yet of convenient size for analysis
• Chemical Analysis


  Assaying of ores, modern methods include emission spectroscopy and X-ray fluorescence spectroscopy
• Mineralogical Analysis


  Heavy-liquid testing to determine successful separation of a valuable mineral from its ore
• Size Analysis


  Classifying coarsely ground minerals according to size using sieves or screens
• Comminution


  1. Crushing

  2. Grinding
• Comminution


  Necessary to liberate the minerals from their interlocked state physically, typically involves crushing the ore to a certain size and grinding it into powder
• Crushing


  Done in stages to produce material suitable for use as mill feed, using jaw crushers and cone crushers
• Grinding


  Further breaking down the crushed material in a cylinder mill with grinding bodies such as flint stones or metal balls
• Concentration


  1. Optical Sorting

  2. Gravity Separation

  3. Magnetic Separation

  4. Electrostatic Separation

  5. Flotation Separation
• Concentration


  The process of separating valuable minerals from other materials after grinding, using different properties of the minerals
• Optical Sorting


  Concentrating particles that have different colors, using the naked eye or electro-optic detectors
• Gravity Separation


  Concentrating minerals by taking advantage of the differences in their densities, using heavy-media separation, jigging, spirals, and shaking tables
• Magnetic Separation


  Separating minerals based on their different levels of attraction to magnetic fields, using low-intensity and high-intensity magnetic separators
• Electrostatic Separation


  Separating particles based on their electrical charges and sizes, by exposing them to an electrical field
• Flotation Separation


  Concentrating fine-grained minerals by altering the hydrophobic or hydrophilic conditions of their surfaces to induce them to adhere to air bubbles or remain in the pulp
• Dewatering


  1. Filtration

  2. Thickening

  3. Drying
• Dewatering


  Converting the pulps produced by concentration methods to a transportable state, and recycling the water back into the processing plant
• Filtration


  Separating a suspension into a solid filter cake and a liquid filtrate using a permeable filtering material
• Thickening


  Settling solids in a suspension by gravity in a tank to form a thick pulp, which can be continuously or intermittently removed along with clear liquid at the top of the tank
• Drying


  Removing water from solid materials using thermal drying methods such as convection dryers
• Uses gamma radiation

  Radiometric Separation