Introduction to MetE.pdf

LECTURE 1 Metals TERMINOLOGIES AND BASIC PROCESSES Can be an element or an alloy Minerals Good conductors of heat and electricity...

LECTURE 1 Metals TERMINOLOGIES AND BASIC PROCESSES Can be an element or an alloy Minerals Good conductors of heat and electricity Naturally occurring Malleable and ductile Inorganic Vital in society Homogeneous solids o Currency Definite composition o Construction Ordered structures (crystalline properties) o Technology Ore History of Metals Stone Age (7,000 BC) A mineral deposit with sufficient utility and value to be mined at a profit or economically exploited Wood and stone to become a source or supply of a particular Tools are made of Au, Ag, and Cu for hunting, material plowing, farming and decorative artifacts Run-of-Mine Bronze Age (4,500 BC) As mined ore which consists of valuable minerals Copper and bronze (first alloy) and gangue For tools, ornaments, jewelry and weapons Concentrate Iron Age (1,400 BC) Valuable minerals obtained from the recovery Iron (wrought) cast processes Iron and steel Gangue Seven Metals of Antiquity Minerals of no value Gold Tailings Copper Silver Predominantly the gangue material Lead May contain very small amount of the valuable Iron mineral Mercury Ore Dressing / Beneficiation Tin Preparation required for ores before the extraction Documentary Evidences process 1. De Re Metallica (“On the nature of metals”) Extraction Contains a comprehensive description of the mining industry during the early Renaissance Recovery of valuable metal from concentrates or 2. De la Pirotechnia ore One of the earliest printed books on metallurgy Recovery / Winning Metallurgy Process involving the production or recovery of pure metal The art and science of extracting and refining Grade / Assay metals from primary and secondary sources to characterize, process and fabricate for Metal content or measure of the concentration of application and use at a profit with utmost metal consideration of the environment.  Used to ascertain the content of valuable metal in ore Cut-off Grade Gold Production Processes Lowest grade of mineralized material considered Miller Process economic Wohlwill Process 3 Types of Ores CIP / CIL / CIC Direct Smelting Native Ore Merrill-Crowe Process Metal is present in elementary form MacArthur-Forrest Process o Gold Nickel Production Processes o Silver o Copper HPAL Moa Bay Process Sulfide Ore Sherritt-Gordon Process Contain metals as sulfides Direct Smelting o Chalcopyrite – CuFeS2 o Chalcocite – Cu2S Iron Production Processes o Pyrite – FeS2 Blast Furnace Smelting Oxidized Ore Midrex Process Corex Process o Valuable mineral may be present as oxide, sulfides, Basic Oxygen Furnace Smelting sulfates, silicates, carbonates Copper Production Processes Unit Operations Heap Leaching Individual sequential steps in producing metal Mitsubishi Process from the ore involving purely physical changes Flash Smelting Can use chemicals as long as it will not alter the Electrorefining ore chemically LECTURE 2 Unit Processes Mineral Processing Individual sequential steps in producing metal from the ore involving chemical changes and/or Mechanical separation of valuable materials from changes in the state of aggregation the gangue of an ore. Objective of Mineral Processing - Reduce ore quantity - Bring the valuable mineral into suitable technical. Benefits of Mineral Processing - Efficient and low cost - Waste rock minimization leads to improved metal purity - Effective material reduction leads to reduced treatment charges Unit Operation in MP 𝑥1 𝐸𝑘 = 𝐾 (𝐼𝑛 ) 𝑥2 1. Comminution 3. Bond’s Energy Law 2. Sizing 1 1 3. Concentration/Separation 𝐸𝐵 = 𝐾 ( − ) 4. Dewatering √𝑥2 √𝑥1 5. Auxiliary Operations General Stages of Comminution - Crushing Comminution (or size reduction by particle breakage. - Grinding o Creates particle in certain size and shape. Reduction Ratio – ration of the feed opening o Increases surface area available for next process 𝑑𝑓𝑒𝑒𝑑 𝐹80 𝑅𝑟 = = o Involve crushing and grinding 𝑑𝑝𝑟𝑜𝑑𝑢𝑐𝑡 𝑃80 Fracture Mechanism – depends on nature by particles Primary Crusher Abrasion (nakakaskas) Jaw Crusher – 2 crushing - localized stresses at the surface - Blake Type (pivot up) – movable jaw - Occurs when insufficient energy is applied. - Dodge Type (pivot down) – fixed at bottom Cleavages Higher capacity and prone to choking - Slow compression Gyratory – crushes on full cycle Shatter Secondary Crusher - Rapid loading obtained in high velocity impact Cone Crusher Comminution Theory - Standard – higher reduction ratio - Shorthead - Accounts for more than 40 % – 50% of total Role Crusher - 2 horizontal power used in MP Impactors - Only 3% - 5% of the energy input is used to Grinding – size reduction with impact and abrasion comminute - mechanically wasteful process - Done whether wet or dry - most energy is lost and absorbed by the equipment Motion of charge in Tumbling Mills Energy Size Reduction Relationship Cascading 𝑑𝐸0 = −𝐾 𝑑𝑥 Cataracting 𝑥𝑛 Centrifuging 𝐸0 – specific energy Rod Mill – uses cast iron rods as grinding k – material constant x – particle size Ball Mill – steel ball (length 1-1.5x the diameter) n – geometry factor Autogenous/SAG Mill - Tower Mill – (still ball) 1. Rittinger's Energy Law Closed circuit reduction – energy Amount of new surfaces produced 1 1 𝐸𝑟 = 𝐾𝑟 ( − ) 𝐷1 𝐷2 2. Kick’s Energy Law Sizing  - Control of quality equipment - Measure of degree of liberation - Method in sizing (screening) Industrial Screening (big equipment) - Screen movements - Frequency horizontal - Stroke vertical Objective of Screening Filters of big to small sizes Ensure feed to succeeding process does not exceed size limitation of receiving area 3 different types of screening surfaces ✓ Parallel Rod ✓ Punched Plates ✓ Woven-wire Types of Screening - Stationary 1. Grizzly 2. Sleve bend - Moving Screen 1. Moving bar grizzlies 2. Tromel Screen 3. Vibrating Screen