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CHE2119 - Chemical Process Industries Disadvantages Releases toxic HCl in...

CHE2119 - Chemical Process Industries Disadvantages Releases toxic HCl in the atmosphere Lecture 1 - Chemical Engineers Behind the CaS waste releases H2S Scenes Definitions of Chemical Engineering Alkali Act - the first modern air pollution AIChE Constitution, Art. III: Definition of the Profession legislation “Profession in which knowledge of mathematics, Solvay Process - a new method formulated by chemistry, and other natural sciences gained by study, Ernest Solvay in 1863 experience, and practice is applied with judgment to develop economic ways of using materials and energy for Chemical Engineers that Shaped the World the benefit of mankind” George Davis - alkali inspector ○ “Father of Chemical Engineering” American Heritage Dictionary of the English Language, ○ Organized 12 lectures at the Manchester 5th Edition Technical School in 1887 “Branch of engineering that deals with the technology of ○ Founded the “Society of Chemical large-scale chemical production and the manufacture of Engineers” in 1880 but was denied products through chemical processes” Arthur D. Little ○ Coined the term “unit operations” to Columbia Encyclopedia, 6th Edition distinguish ChemEng from others “Deals with the design, construction, and operation of ○ “American Father of Chemical plants and machinery for making such products as acids, Engineering” dyes, drugs, plastics, and synthetic rubber by adapting the Lewis Mills Norton chemical reactions discovered by the laboratory chemist ○ Chemistry Prof. at the Massachusetts to large-scale production. The chemical engineer must be Institute of Technology (MIT) made the familiar with both chemistry and mechanical engineering” 1st 4-year bachelor program in chemical engineering called “Course X” History of Chemical Engineering ○ Course X - combination of mechanical Before 1880’s engineering and industrial chemistry ○ MechEng with some knowledge of William Page Bryant - first of the 7 students to chemical process equipment graduate from “Course X” ○ Applied Chemist with knowledge of ○ First formal chemical engineer large-scale industrial chemical reactions Carl Bosch - “Haber-Bosch Process” ○ Chemical Plant Foreman with a lifetime ○ Haber-Bosch Process - allows the of experience but little education economical mass synthesis of Industrial Revolution (18th to 19th Century) ammonia, NH3, from nitrogen, N2, and ○ First Industrial Chemicals hydrogen, H2 Sodium carbonate The first industrial chemical Sulfuric acid (oil of vitriol) process to make use of Sodium Carbonate (Soda Ash) - a vital chemical extremely high pressures in the glass, soap, textile, and paper industries (200-400 atm) and high ○ Traditionally sourced from wood ashes, temperatures (400-650 oC) causing massive deforestation Provided a solution to the ○ Nicholas Leblanc - patented a method shortage of fixed nitrogen for the production of Na2CO3 from sea Replaced Chilean saltpeter as a brine, NaCl (Leblanc Process) source of nitrates 1  Margaret Hutchinson Rousseau - designed the Lecture 2 - Chemical Process Industries: An 1st commercial penicillin plant Overview ○ First woman with, a doctorate degree in ChemEng from MIT Chemical Process Industry - includes those Dermot Manning - full-scale production of manufacturing facilities whose products result from: polyethylene using a high-pressure reactor a. Chemical reactions between organic materials, John H. Perry - author of the Perry’s Chemical or inorganic materials, or both Engineers’ Handbook b. Extraction, separation, or purification of a natural ○ He edited the first edition in 1934 product, with or without the aid of chemical reactions Fundamental Areas of Chemical Engineering c. The preparation of specifically formulated 1. Material and energy balances mixtures of materials, either natural or synthetic 2. Chemical reaction and kinetics 3. Phase equilibria Classification of Chemical Process Industries 4. Transport phenomena and processes 1. Quantity of Production and Consumption a. Heavy Chemicals - large quantities, Roles of Chemical Engineers crude (e.g. mineral acid, NaOH, Na2CO3) 1. Process design b. Fine Chemicals - completely purified 2. Plant design substances and produced in limited 3. Pilot plant operation quantity (e.g. specialty solvents, 4. Process engineering/plant operation perfumes, medicines) 5. R & D / product development 2. Chemical Composition 6. Academe a. Organic Compounds - nucleic acids, 7. Technical sales/services fats, sugars, proteins, enzymes, and 8. Management/administration hydrocarbon fuels (e.g. hydrocarbons, phenols, carboxylic acid) Interdisciplinary Fields b. Inorganic Compounds - salts, metals, 1. Energy Engineering and other elemental compounds (e.g. 2. Biological-related Fields Na2CO3, K2Cr2O7, MgCl2) a. Biochemical Engineering 3. Availability b. Biotechnology a. Natural Compounds - available in nature c. Biomedical Applications or produced or extracted from plants d. Bioremediation and animals (e.g, coal, petroleum) 3. Environmental Engineering b. Synthetic Products - synthesized using 4. Polymer Chemistry/Engineering natural products, or they are synthesized 5. Food Processing/Engineering completely using other types of 6. Materials Engineering synthetic materials (e.g., polystyrene, polyvinyl chloride) 4. Application a. Catalyst - increases or decreases the rate of a reaction without being consumed in the process (e.g., AlCl3, MnO2, Pt) b. Bulk Drug - becomes an active ingredient of the finished dosage form of the drug, but the term does not include intermediates used in the synthesis of such substances (e.g., pantoprazole, bisacodyl) 2  c. Resin - a natural or synthetic compound 2. The marine and oceanic environment that begins in a highly viscous state and (hydrosphere) hardens with treatment (e.g. urea a. Ocean water formaldehyde, epoxy, polyester) i. 1.5 x 1021L contains about 3.5% d. Dyes and Pigments mass-dissolved material i. Pigments - DOES NOT dissolve b. Sea water ii. Dyes - Soluble i. Good source of sodium chloride, e. Solvent - liquid that dissolves solute magnesium, and bromine (e.g. benzene, THF, DMF, DMSO) 3. The air (atmosphere) f. Miscellaneous - all other compounds a. Air which do not cover in the above class i. N2, O2, Ne, Ar, Kr, and Xe are called miscellaneous (e.g., fertilizer, b. Earth’s atmosphere glass) i. 5 x 1015 tons; unlimited 4. The plants (biosphere) Chemical Process Industries in the Philippines a. Vegetation and animals Chemical Industries Association of the i. Agro-based industries Philippines (Samahan sa Pilipinas ng mga b. Natural products Industriyang Kimika) i. Oils, fats, waxes, resins, sugar, Sectors natural fibers, and leathers Chemical Process - consists of a combination of chemical reactions and operations based on physical phenomena Chemical Reaction - a process that always results in the interconversion of chemical substances Process Engineering - often the synonym for chemical engineering and focuses on the design, operation, and maintenance of chemical and material manufacturing processes Product Engineering - refers to the process of designing Raw Materials, Manufacturing, and Engineering and developing a device, assembly, or system such that Chemical process industries procure raw it can be produced as an item for sale through some materials from natural environments to convert production manufacturing process them into intermediates, which subsequently Usually entails activities dealing with issues of serve as base materials for every other kind of cost, producibility, quality, performance, industry reliability, serviceability, and user features Sources of Natural Environment Basic Modes of Manufacturing Operation 1. The earth’s crust (lithosphere) Batch Processing - involves the processing of a. Elements bulk material in batches through each step of i. Earth’s crust: mineral ores, the desired process. carbon, hydrocarbons ○ Generally used for small-scale b. Coal, natural gas, and petroleum production; easier to operate, maintain, i. Energy sources and repair ii. Converted to thousands of chemicals 3  Continuous Processing - involves moving one work unit at a time between each step of the process with no breaks in time, sequence, substance, or extent ○ Volume remains constant Piping and Instrumentation Diagram (P&ID) Unit Processes Chemical Changes - commercialization of a chemical reaction under such conditions as to be economically profitable ○ Are chemical transformations or conversions that are performed in a process Physical Changes - based on the fundamental laws and physicochemical principles ○ Are the physical treatment steps which are required to: Symbols for P&ID Put the raw materials in a form in which they can be reacted chemically Put the product in a form that is suitable for the market Flow Diagrams Block Diagram Process Flow Diagram (PFD) 4  Lecture 3 - Chemical Engineering: Fundamental Concepts Mass and Energy Balances Balloon Symbols/Instrument Tags 1st letter - parameter measured 2nd letter - type of control device being used Numbers (logical numerator) - loop it represents Mechanical Equilibrium - no physical changes occur (no change in motion) Net force is zero Thermal Equilibrium - same temperature Chemical Equilibrium - both the forward and reverse reactions are occurring at the same rate Phase Equilibria - At equilibrium, temperature, pressure and chemical potential of constituent component molecules in the system must be the same throughout all the phases Occurs when there is no net transfer of matter or heat energy from one phase to another phase 5 Applications Momentum Transfer Production of different allotropes of carbon Lowering of freezing point of water by dissolving salt (brine) Purification of components by distillation Usage of emulsions in food production, pharmaceutical industry Used in metallurgy to make alloys of different physical and chemical properties Two Assumptions in Mass Balances Newtonian Fluid - constant dynamic viscosity under any There is no transfer of mass to energy shear rate Mass is conserved for each element or Linear relationship between shear stress and compound on either molar or weight basis shear rate Notes Non-Newtonian Fluid Mass and atoms are conserved Pseudoplastic Fluid - ↓ dynamic viscosity at ↑ Moles are conserved only when there is NO shear rate REACTION Dilatant Fluid - ↑ dynamic viscosity at ↑ shear Volume is NOT conserved rate Bingham Plastic - linear shear-stress, shear-rate behavior after an initial shear-stress threshold has been reached Transport Phenomena Molecular Transport Processes - concerned with the transfer or movement of a certain property by molecular movement through a medium, which can be a fluid (gas or liquid) or a solid Properties that can be transferred Time-dependent Non-Newtonian Fluids Mass transport –mass Rheopectic Fluid - viscosity increases Heat transport –thermal energy (heat) Thixotropic Fluid - viscosity decreases Momentum transport –momentum General Molecular Transport Equation 6 Heat Transfer Unit Processes - its characteristics as applied to the manufacture of chemicals may be summarized as follows: 1. Each unit process points out the unitary or like aspects in a group of numerous individual reactions. 2. Frequently there is a factory segregation by unit processes wherein a building or section of a building may be devoted to the making of many chemicals under a given unit process. 3. There frequently is a close relationship in the equipment used for making many examples under a unit process. 4. Equipment may be conveniently transferred from the making of one chemical to that of another within the same unit process 5. Needs chiefly to remember principles rather than specific performances. 6. This places stress upon the chemical reaction. Hence the unit process emphasis - exhaustive Mass Transfer study of the basic chemical change. 7. The inorganic and the organic procedures do not need to be set apart industrially. 8. The design of equipment is greatly aided by the generalizations arising from the unit process arrangement rather than by considering each Comparison between Momentum, Heat, and Mass reaction separately. Transfer Types of Unit Processes 1. Combustion a. Burning of fuels b. Oxygen source can either free-form as in O2 or in combination with other elements or compounds like HNO3, H2O2 c. The heat of reaction is a common source of energy i. Industries - fuel and power ii. Equipment - boilers (steel, firebrick) 2. Neutralization a. Reaction of acids and bases i. Industries - water treatment, sodium salts, ammonium sulfates, ammonium nitrates, urea, arsenites, arsenates, soap from fatty acids ii. Equipment - reactors, treaters, Dimensionless Groups adsorbers, tanks, kettles 7 3. Oxidation (controlled) superphosphate, hydrochloric, a. Uses oxygen as the oxidizing agent hydrofluoric, pigments b. In liquid-phase reactions: ii. Equipment - reactors, brine permanganates, dichromates, chloric treaters, stills, kilns anhydrides, hypochlorites, chlorates, 7. Causticization lead peroxide, and hydrogen peroxides a. Alkaline carbonate → lime c. The reaction is basically exothermic i. Industries - caustic soda d. Heat transfer systems are carefully ii. Equipment - causticizers, lime designed to prevent controlled oxidation kiln from turning to combustion 8. Calcination i. Industries - water and wastes, a. Heating below melting point to remove water gas, industrial gasses moisture and other volatile compounds (CO2, H2), phosphoric acid (from b. Materials undergoing such process will P), sulfuric acid, nitric acid (from be oxidized or reduced NH3), paints and pigments, i. Industries - lime, gypsum, soda linoleum, perfumes, ash formaldehyde ii. Equipment - kilns, calciners ii. Equipment - tanks, generators, 9. Esterification boilers, oxidizers, burners, a. A chemical process in which an ester reactors and water are formed when an organic 4. Reduction radical is substituted for in a molecule a. The reaction is basically endothermic by an ionizable hydrogen of an acid. b. Reducing agents: lithium, sodium, i. Industries - rayon: xanthate, magnesium, iron, zinc, aluminum, NaBH4 acetate, ethyl and vinyl acetate and LiAlH4, and hydrogen gas (H2) with a ii. Equipment - acetylators, palladium, platinum, or nickel catalyst reactors, agers i. Industries - phosphorus, sulfur 10. Nitration from SO2, aniline from a. Treatment with nitric acid to produce nitro-benzene either nitrates or nitro compounds ii. Equipment - furnaces, reactors, b. Hastened with sulfuric acid reducers i. Industries - explosives, 5. Electrolysis intermediates for dyes, a. Reactions are carried out in solutions of nitro-benzene, etc electrolytes or molten salts by passage ii. Equipment - nitrators, reactors of electricity 11. Sulfonation b. Electrodes are dipped in the solution a. Involves the introduction of sulfonic acid and direct current is passed through it group (SO2OH) or its corresponding salt c. Oxidation: positive electrode or anode or sulfonyl halide (=SO2Cl) into an d. Reduction: negative electrode or organic molecule cathode b. Sulphonatic agents: sulphuric acid, i. Industries - industrial gases (H2, Sulphur trioxide in water (oleum) and O2), caustic soda and chlorine, fuming sulphuric acid aluminum, magnesium, sodium i. Industries - explosives, sulfite ii. Equipment - electrolytic cells paper, intermediates for dyes, 6. Double Decomposition benzene-sulfonate for phenols a. Also known as exchange reaction ii. Equipment - sulfonators, i. Industries - water softening, Ca burners and Mg salts, potassium salts, sodium salts, soda ash, phosphoric acid, 8 12. Hydration and Hydrolysis fats, detergents, petroleum, a. Reaction with water done in the methanol from CO presence of a catalyst ii. Equipment - catalyst chambers, b. If reactants are not miscible, emulsifying reactors hydrogenator, agents are added. hydrogenating autoclaves i. Industries - slaked lime, 17. Condensation phosphoric acid from a. Combination reaction of two smaller phosphorus pentoxide, molecules to form a larger molecule, glycerine, soap, corn sugar, producing a small molecule such as H2O dextrin, sucrose to glucose and as a by-product fructose, phenol i. Industries - resinification, ii. Equipment - hydrators, soap benzoyl-benzoic acid for kettles, autoclaves, fermenters, anthraquinone phenolphthalein fusion pots, hydrolyzers ii. Equipment - reactors 13. Halogenation 18. Polymerization a. Introduction of halogens a. Simple molecules (monomer) react to b. Most widely used: chlorination form large molecules c. Seldom used: iodination b. Classified as i. Industries - chemical for i. Condensation reactions occur warfare, insecticides, between two groups to form a intermediate for dyes, new group not present in the chlorobenzene, benzyl chloride, reactant with a small compound carbon tetrachloride split out like water; usually, the ii. Equipment - reactors, elimination of water or alcohol halogenators, chlorinators from bi-functional molecules 14. Amination by Ammonolysis ii. Addition by reopening of a a. Introduction of amine group multiple bond without i. Industries - aniline from elimination of any part of a chloro-benzene, molecule B-naphthylamine, c. Can be carried out in bulk, solution, ethanolamines emulsion or suspension ii. Equipment - autoclaves i. Industries - rubber, petroleum 15. Alkylation industry a. Introduction of alkyl group ii. Equipment - polymerizers, b. In petroleum industries, polymerization reactors low-molecular-weight fractions are 19. Pyrolysis or Cracking reacted to form higher molecular-weight a. Process where heat is employed to compounds decompose compounds i. Industries - photography, b. Some reactions take place at low styrene, petroleum, temperature in the presence of solvents intermediates, medicines i. Industries - distillation of coal, ii. Equipment - autoclaves, fuel (coal) gasses, oil gas for reactors, alkylators carbureted water gas, carbon 16. Hydrogenation and Hydrogenolysis black, lampblack, distillation of a. A chemical reaction of molecular wood, petroleum industry hydrogen with another substance in the ii. Equipment - retorts, carburetors, presence of a catalyst distillation chambers, reaction i. Industries - ammonia from chambers nitrogen, hydrochloric acid from chlorine, hydrogenated oils and 9 20. Fermentation Types of Unit Operations a. Substance conversion using 1. Fluid Flow or Fluid Dynamics microorganisms like yeasts and bacteria a. Deals with the transportation of fluid b. Involves complex processes like i. Industries - water and wastes, oxidation, reduction, hydrolysis, oils and fats, petroleum esterification, etc. ii. Equipment - pumps, tanks c. Parameters being monitored are 2. Heat Transfers temperature, concentration, pH, and, to a a. Fundamental modes of heat transfer: certain extent, pressure conduction, convection, and radiation i. Industries - industrial gasses i. Industries - fuels and power, (CO2), alcohol and CO2 from distillation of coal, fuel gasses, monosaccharides, alcohol, industrial gasses, phosphorus, acetone, and butanol from sulfuric acid, ammonia, carbohydrates, wines, beers, petroleum industry liquors, lactic acid, penicillin ii. Equipment - boilers, heat ii. Equipment - fermenters exchangers, generators, coolers 21. Isomerization 3. Evaporation a. Transformation of a compound into any a. Removal of valueless component from a of its isomeric forms mixture through vaporization i. Industries - petroleum b. The mixture is usually a non-volatile ii. Equipment - isomerizers solid or liquid and a volatile liquid 22. Aromatization i. Industries - potassium salts, a. Conversion of aliphatic or alicyclic salt caustic soda, phosphoric compounds to aromatic hydrocarbons acid, glycerine, sugar, oils and i. Industries - petroleum fats, petroleum ii. Equipment - reaction chambers ii. Equipment - evaporators 23. Ion Exchange 4. Humidification a. Refers to the interchange of ions that a. Process in which the moisture or water takes place when an ionic solid is vapor or humidity is added to air without contracted with electrolytic solutions changing its dry bulb (DB) temperature b. Can be used for b. Usually accompanied by cooling or i. Transformation of electrolytes heating of the air like in water softening where i. Industries - textile fibers calcium and magnesium ions ii. Equipment - humidifiers are exchanged for sodium 5. Gas Absorption/Stripping ii. Removal of ionic constituents a. Gas Absorption - transfer of a soluble like deionization of water component of a gas mixture to a liquid iii. Separation of ionic substances b. Desorption/Stripping - transfer of a like amino acids volatile component from a liquid to a iv. Concentration of ionic solutions gas v. Industries - wastewater, acids, i. Industry - distillation of coal, bases, salts fuel gasses, industrial gasses, vi. Equipment - ion exchange bleach, nitric acid, hydrochloric column, ion exchangers acid, leather ii. Equipment - absorbing tower 10 6. Solvent Extraction 11. Classification or Sedimentation a. Separation of compounds based on a. A physical water treatment process relative solubilities in two different using gravity to remove suspended immiscible liquids solids from water i. Industry - coal gas, insecticides, i. Industry - cement rock, perfumes, oils, acetic acid, phosphate rock, potassium lubricating oils salts, caustic soda, wastewater ii. Equipment - percolator, tower, treatment extractor ii. Equipment - beneficiation, 7. Adsorption thickeners, clarifiers, a. Adhesion of atoms, ions, or molecules sedimentation tank to a surface of a liquid or solid 12. Filtration b. Due to residual forces at the surface of a. Removal of solid from a liquid/solid or liquid or solid phase gas/solid mixture i. Industry - water and wastes b. Use this if there is SEDIMENT purification, artificial leather i. Industry - ceramics, Ca and Mg solvent recovery salts, potassium salts, sodium ii. Equipment - tanks salts, sugar, rayon, paraffin, 8. Distillation intermediates and dyes, organic a. Extraction by vaporization and chemicals, wastewater condensation ii. Equipment - plate and frame b. Depends on different boiling points of filter press, rotary drum filter components 13. Screening i. Industries - distillation of coal, a. Separation of materials based on industrial gasses (O2, N2), particle size perfumes, glycerine, alcohol, b. Screens are classified based on Mesh acetone, petroleum, number, the number of openings across intermediates one linear inch of screen ii. Equipment - still, distilling i. Industries - cement, soda ash, column, rectifier silicon carbide, sugar, minerals 9. Drying ii. Equipment - screen a. Removal of water or volatile solvent 14. Crystallization i. Industries - ceramics, sodium a. Separation of solid particles from their salts, pigments, soap, sugar, saturated solutions pulp and paper, rubber i. Industries - Ca and Mg salts, ii. Equipment - spray drier, tray potassium salts, sodium salts, drier, rotary drier, pan drier, sugar, pharmaceuticals steam-heated cylinder ii. Equipment - crystallizer 10. Mixing 15. Centrifugation a. Make it more homogeneous a. Uses the action of centrifugal force to i. Industries - fertilizers, dynamite, promote accelerated settling of particles paints, lacquers, dyes in a solid-liquid mixture ii. Equipment - mixers, mixing vats i. Industries - NH4 sulfate, Ca and Mg salts, potassium salts ii. Equipment - centrifuge 11  16. Size Reduction Mineral Ores - mineral deposit; profitably exploited. a. An operation carried out for reducing the May contain three groups of minerals size of bigger particles into smaller ones ○ Valuable minerals of the metal which is of the desired size and shape with the being sought help of external forces ○ Compounds of associated metals which i. Industries - ceramics, cement, may be of secondary value glass raw materials, rock wool, ○ Gangue minerals of minimum value paints, resins, minerals ii. Equipment - ball/cylinder/disk Ore Dressing - physical pre-treatment before ores are mills, gyratory crushers subjected to the main chemical treatment 17. Leaching Meant to affect the concentration of the valuable a. Extraction of a soluble solid from its minerals and to render the enriched material into mixture with an inert solid by use of a the most suitable physical condition for liquid solvent in which it is soluble subsequent operations i. Industries - sugar, fats and oils, Comminution - reduction of the size of the ore minerals by crushing, grinding, cutting, and vibrating to ii. Equipment - extractors such a size that will release or expose all 18. Materials Handling valuable minerals a. Includes consideration of the protection, ○ Followed by screening storage, transportation, and control of materials throughout their manufacturing, warehousing, distribution, consumption, and disposal i. Industries - fuels, fuel gasses, ceramics, cement, glass, soda ash, wood, rubber ii. Equipment - belt conveyor, screw conveyor, pumps and pipes, trucks Lecture 4 - Extractive Metallurgy Extractive Metallurgy - deals with the extraction and refining of metals from its naturally existing ore or minerals Source of Minerals ○ Earth’s crust: 8.1% aluminum, 5.1% iron, 3.6% calcium, 2.8%, sodium, 2.6% potassium, 2.1% magnesium, 2.1% titanium, 0.10% manganese ○ Ocean water: 10,500 g/ton Na, 1270 g/ton Mg, 400 g/ton Ca, 380 g/ton K; Sorting - performed to separate particles of ore ocean nodules: 23.86% Mn, 1.166% Mg, minerals from gangue (non-valuable) minerals or 2.86% Al, 13.80% Fe different ores from one another ○ Recycled scrap: at the end of metals’ ○ Classification Process - based on the life following factors Types of Metallurgy Smaller = fall slower in fluids ○ Pyrometallurgy than larger ones ○ Hydrometallurgy Larger = more centrifugal force ○ Electrometallurgy 12  Small particles having less Extraction Processes inertia tend to behave like the 1. Calcination suspending medium or fluid a. Thermal treatment of an ore to affect its Larger needs higher velocity for decomposition and the elimination of a separation volatile product, usually CO2 or H2O ○ Froth Flotation - uses differences in 2. Roasting surface properties of the individual a. Process of heating of concentrated ore minerals to selectively adsorb material to a high temperature in excess air on the air bubbles b. Involves chemical changes other than decomposition, usually with furnace atmosphere ○ Magnetic Separation - uses differences in magnetic properties of materials Ferromagnetic - magnetic materials 3. Smelting Paramagnetic - weakly attracted a. Ore (usually mixed with purifying and/or into a magnetic field heat-generating substances such as Diamagnetic - weakly repelled limestone and coke) is heated at high by a magnetic field temperatures in an enclosed furnace ○ Electrostatic Separation - selective b. It is opposite to roasting (oxidizing sorting of solid species by means of reaction) as it has reducing reactions utilizing forces acting on charged and c. The components of the charge in the polarized bodies in an electric field molten state separate into two or more layers which may be: i. Matte ii. Slag iii. Speiss Agglomeration - formation of lumps of appropriate size and strength when ore or concentrate is too small for use in a latter stage of treatment ○ Done by any of the following methods Pelletizing Briquetting Sintering 13 Extractive Metallurgy of Iron Bayer Process - the process of refining alumina from Iron Ores bauxite by selective extraction of pure aluminum oxide ○ haematite (Fe2O3) dissolved in sodium hydroxide ○ limonite (FeO(OH).nH2O) Digestion - extraction of the alumina through ○ magnetite (FeO.Fe2O3) digestion with hot NaOH solution which ○ Pyrite, (FeS2) dissolves the aluminum hydroxide, forming a Iron Forms solution of sodium aluminate ○ White cast iron ○ Grey pig iron ○ Steel Clarification - removal of undissolved solid ○ Alloy impurities (calcium oxide, iron oxide, titanium Raw Materials oxide) that form the “red mud”, which settles ○ Iron Ore down at the bottom of mud thickeners Abundant, makes up 5% of Precipitation - recovery of crystals of aluminum earth’s crust hydroxide (Al(OH)3) Main impurities: silica and ○ Precipitation is promoted by seeding the alumina liquor with pure alumina crystals acting ○ Limestone or Dolomite as nuclei for the precipitation process. Calcium carbonate ○ Crystals of aluminum hydroxide/ Used to remove impurities alumina trihydrate (Al2O3.3H2O) grow ○ Coke and aggregate Produced at the bottom of the blast furnace by carbonization of coal Calcination - the aluminum hydroxide, after Used to heat the furnace and separation from the sodium hydroxide, is produce CO which acts as the converted to pure aluminum oxide by heating to reducing agent 1800oF (1000oC) in rotary kilns or fluidized bed calciners Extractive Metallurgy of Aluminum Hall-Heroult Process - production of aluminum by Most abundant metallic element the electrolytic reduction of the aluminum oxide Bauxite ores - a mixture of hydrous aluminum It involves the dissolution of aluminum oxide in oxides, aluminum hydroxides, clay minerals, and molten cryolite (a mineral containing sodium insoluble materials aluminum fluoride, Na3AlF6) and electrolysis of the molten salt bath Three Stages of Aluminum Extraction from Bauxite 1. Ore Dressing - cleaning ore by means of separation of the metal-containing mineral from the waste (gangue) 2. Chemical Treatment of Bauxite - conversion of hydrated to pure aluminum oxide 3. Reduction of Aluminum from Aluminum Oxide - by the electrolytic process 14 Extractive Metallurgy of Copper Lecture 5 - Alkali Industry Concentration - separation of the copper mineral from the gangue ○ In froth flotation cell, the ore particles are lifted by air bubble while the gangue remain in the cell Roasting - removal of excess sulfur ○ The dry pulp is fed into the roaster at 600 to 700oC ○ The burning of the sulfide ores supplies the heat to maintain the temperature at which roasting takes place Matte Smelting - concentrate is smelted in a History of the Alkali Industry furnace to produce a mixture of copper Leblanc Process (1773) - Nicholas Leblanc Blister Copper Production - conversion of matte into molten blister copper containing 96 to 98% copper and remove the iron-rich slag Solvay Process (1869) - Ernest Solvay Electrolytic Refining - cathodes produced as a ○ Ammonia-soda process result of the electrolytic refining process contain ○ Reduced the price of soda ash to 1/3 99.9% copper Chlor-Alkali Process (1890) ○ Caustic soda and chlorine ○ Cheap electricity, a ready source of salt, and proximity to markets Uses and Economics Soda Ash - a lightweight solid, readily soluble in water, contains 99.2% Na2CO3 Application: used in the manufacture of caustic soda, sodium bicarbonate, sal soda, glass, detergents, soaps, pulp and paper, textiles, water softeners, and a desulfurizing agent in ferrous metallurgy Caustic Soda - brittle white solid which readily absorbs moisture and carbon dioxide from the air, 98% NaOH Application: manufacture of rayon, explosives, soap, paper, and in many others 15  The NH3 helps to buffer the solution to stop the Chlorine - used for the direct treatment of a given absorption of CO2 making the solution acidic, thus product (i.e. pulp, paper, textile bleaching, water arresting the precipitation of NaHCO3 treatment, and sewage purification) Used in insecticides, fungicides, bactericides, Rotary Suction Filter - Thick milky liquid from and herbicides the base of the carbonating tower is filtered Manufacture of Soda Ash (Solvay Process) Raw Materials ○ Sodium Chloride or Salt (NaCl) ○ Limestone (CaCO3) - burned in kilns to furnish both the CO2 for the soda ash and the lime for the recovery of NH3 ○ Ammonia Gas (NH3) - recovered from ○ Calcination of NaHCO3 and Production ammonium bicarbonate and ammonium of Na2CO3 - the most difficult step due to chloride produced in the process the formation of lumps and non-conducting scales on the steel shell Process Flow Diagram of the Solvay Process of the calciner Lime Kiln - limestone is burnt to produce CO2 and lime. ○ CO2 → carbonating tower Ammonia Absorber - NH3 gas mixed with CO2 ○ Lime → lime slaker gas is bubbled through a 20% sodium chloride solution (brine) ○ Impurities of calcium and magnesium Lime Slaker - lime is slaked in a large quantity of salts in the brine precipitate as water to form milk of lime pumped to the middle carbonates and hydroxides of the ammonia recovery tower Filter - after saturation, the ammoniacal brine is pumped through the filter to remove the Ammonia Recovery Tower precipitated carbonates and hydroxides. Carbonating Tower - site for the carbonation of ammoniacal brine ○ Operates with a counter-current flow ○ Ammonium chloride and sodium bicarbonate crystals are formed 16 Unit Processes and Operations in detail Preparation and Purification of the Salt Brine ○ Mining and solution of salt, or pumping of water to salt beds and of brine from these deposits (op.) ○ Purification of brine (pr. and op.) Ammoniation of Brine ○ Solution of NH3 in the purified brine (op. and pr.) ○ Solution of weak CO2 in the purified brine (op. and pr.) Calcination of Sodium Bicarbonate ○ Conveying and charging of moist sodium bicarbonate to the calciner (op.) ○ Calcination of sodium bicarbonate (pr. Carbonation of Ammoniated Brine and op.) ○ Formation of ammonium carbonate (pr.) ○ Cooling, screening, and bagging of soda ○ Formation of ammonium bicarbonate ash (for sale) (op.) (pr.) ○ Cooling, purifying, and compressing; ○ Formation and controlled precipitation piping of rich CO2 gas to carbonator of sodium bicarbonate (pr.) (op.) ○ Filtration and washing of the sodium bicarbonate (op.) ○ Burning of limestone with coke to form CO2 and CaO (pr.) ○ Compressing and cooling of lime kiln or lean CO2 ○ Piping to carbonator (op.) 17  Recovery of Ammonia Dorr Agitators ○ Slaking of quicklime (pr.) ○ Causticization of Soda Ash ○ Treatment of sodium bicarbonate mother liquors with steam and Ca(OH)2 in strong NH3 liquor still to recover NH3 (pr.) Dorr Central Drive Thickener ○ Feed ○ Discharge ○ Overflow Manufacture of Sodium Bicarbonate Why Solvay Process is not Employed in Sodium Bicarbonate Difficulty in complete drying The value of the ammonia would be lost Even a small amount of ammonia gives the bicarbonate an odor It contains many other impurities Manufacture of Electrolytic Caustic Soda and Chlorine Raw Materials ○ Salt - brine from rock salt, natural or artificial brine, or sea salt Reactions and Energy Changes ○ Theoretical/Minimum Voltage: Gibbs-Helmholtz equation ○ Voltage Efficiency - ratio of theoretical voltage to the actual voltage used Manufacture of Caustic Soda: Lime-Soda Process (usually 45 – 65%) ○ Recall Faraday’s Law - 96,500 C of electricity = 1 gram-equivalent of chemical reaction at each electrode ○ Current Efficiency - ratio of the theoretical to the actual current consumed (cathode current efficiencies: usually 95 – 97%) ○ Energy Efficiency of the Cell - voltage efficiency X current efficiency ○ Decomposition Efficiency - ratio of Lime Slaking equivalents produced in the cell to equivalents charges (usually 50 %) 18  Chlorine Compression and Liquefaction - compression to 35-80 lb gage ○ Liquefaction by refrigeration to – 20oF ○ Cooling to – 50oF once all chlorine has liquefied Purification of Caustic via Mercury cells ○ Cathode: a thin layer of mercury ○ Anode: graphite or titanium Hydrogen Disposal - conversion to hydrochloric acid or ammonia or use for hydrogenation of organic compounds Electrolytic Cells Unit Processes and Operations Diaphragm cells - asbestos allows ions to pass Brine Purification - purification of NaCl solution by electrical migration but limit the diffusion of from Ca, Fe, and Mg impurities using soda ash products with some caustic soda ○ Cathode: cast iron ○ Performed to lessen clogging of cell ○ Anode: graphite diaphragm with consequent voltage ○ Chlorine gas report to the anode increase ○ Hydrogen ions report to the cathode → ○ Brine Filters - removes the suspended NaOH solids overflowing with the brine from Mercury cells the settler ○ Cathode: moving pool of mercury Brine Electrolysis (via Diaphgram cells) - the ○ Anode: graphite / modified titanium cathode is surrounded by a porous diagram of ○ Chlorine reports to the anode asbestos since H2(g) and Cl2(g) are explosive ○ Sodium reports to the cathode: upon contact ○ Amalgam (mercury + sodium alloy) Evaporation and Salt Separation - about 10 – Membrane cells - plastic sheets porous and 15% NaOH solution is evaporated to 50% NaOH chemically active to allow sodium ions to pass in a double or triple-effect evaporator with salt through but reject hydroxyl ions separators, followed by a washing filter ○ Uses more concentrated brine solutions Final Evaporation - concentration of 50% NaOH and produce purer and more to 70-75% NaOH in a single-effect final or high concentrated sodium hydroxide evaporator ○ Cathode: steel ○ Alternative method: precipitation of ○ Anode: graphite sodium hydroxide monohydrate by the addition of ammonia to the 50% NaOH Lecture 6 - Sulfur and Sulfuric Acid solution Special purification of caustic soda Properties of Sulfur ○ Chlorine drying - treatment with CaCO3 Commonly appears as yellow crystals or powder and filtering the resulting mixture at room temperature ○ Removal of Chloride and Chlorate - Essential to all living things (taken up as sulfates dropping of 50% NaOH through a by plants and animals; makes up essential column of 50% NH3 (aq) solution amino acids) ○ Salt Content Reduction - cooling to 20oC Widely found in many minerals like iron pyrites, Chlorine Drying - hot chlorine from the anode is galena, gypsum, and Epsom salts cooled to condense most of its vapor Abundant and occurs throughout the universe, ○ Chlorine temperature should be kept in a but is rarely found in pure, uncombined form at range of 15-20oC. the Earth’s surface ○ After cooling, chlorine gas is dried in a sulfuric acid scrubber 19  Sulfur from Smelter Gases - sulfur recovery from SO2 and H2S (controlled by air pollution regulations) Sources ○ Roasting of sulfide ores ○ Coal combustion ○ Burning of acid sludge from petroleum refining Products ○ Elemental sulfur ○ Sulfuric acid Sources of Elemental Sulfur ○ Liquid sulfur dioxide Pyrite Sulfur mining (Frasch) Sulfur from Industrial Gases Hydrogen sulfide (from natural gases and Removal of Hydrogen Sulfide, H2S refineries) ○ Purification of natural and manufactured Smelter gases gas Calcium sulfate ○ Petroleum refining Coal Sulfur from Pyrites Low-grade sulfur deposits ○ Flash roasting of sulfide ores Sulfur Dioxide from By-products Mining and Extraction of Sulfur ○ Liquid Waste from Steel Industry Frasch Process (1890) - by Herman Frasch (Pickling of Metals) Sulfur-bearing limestones (90% elemental sulfur) 2-15% sulfuric acid and 10-15% as a source of elemental sulfur ferrous sulfate Involves the burrowing of three concentric pipes ○ Sludge and Alkylation Acids to a depth of 150 to 750 m to reach the bottom Recovered by decomposing to of the sulfur-bearing strata SO2 (processed to H2SO4) Properties of Sulfuric Acid Colorless to yellowish in color Highly corrosive Highly oxidizing Miscible in water Dehydrating agent ○ Important in nitrification, esterification, and sulfonation Forms ○ Sulfuric Acid - H2SO4 in water ○ Oleum - SO3 in H2SO4 Steps in the Frasch Process 1. Superheated water is forced down the Common Sulfuric Acid Concentrations outermost of 3 concentric pipes to the underground deposit. 2. The hot water melts the sulfur. 3. The innermost pipe conducts compressed air into the liquid sulfur. 4. The air forces the liquid sulfur, mixed with air, to flow up through the outlet pipe. 20 History of Sulfuric Acid Manufacturing Glover Tower - made of acid-resistant bricks 15th century - burning of saltpeter with sulfur packed with stone pieces (Valentinus) ○ Liquid Phase - H2SO4 is concentrated to 1746 - Lead Chamber Process (Dr. Roebuck of 62-68% due to H2O evaporation Birmingham) Some SO2 is oxidized to H2SO4 ○ Ignition of brimstone and saltpeter in a (further concentrates H2SO4) room lined with lead foil NO∙HSO4 is hydrolyzed to H2 SO4 ○ Sulfur trioxide reacted with water to produce sulfuric acid ○ Gaseous Phase (SO2 + air + NOX) - gas is cooled 1835 - Joseph Gay-Lussac invented a process to NOX from the liquid phase recover nitrogen reports to the gaseous phase ○ Replaced expensive saltpeter as a source of nitrogen ○ Sharply reduced NO emissions Lead Chamber Process Manufacturing Procedure Combustion Chamber - either sulfur or pyrite is burned Gay-Lussac’s Tower - unreacted gases from the lead chamber are passed upwards into Nitre Pots - oxide of nitrogen is obtained by Gay-Lussac’s tower. heating NaNO3 and concentrated H2 SO4 ○ H2SO4 is sprayed from the top. 21 Contact Process (1831, Phillips) - yields strong acid: 98 Vanadium Catalysts – 100% H2SO4 Carriers: zeolite or other base Decomposition of chamber acid Advantages: Passing a mixture of sulfur dioxide over a ○ higher conversion efficiency maintained catalyst for a longer period Absorption of sulfur trioxide in water ○ immunity to poisoning ○ mass is less troublesome during Reactions and Thermodynamics operation; easier to handle Generation of Sulfur Dioxide from Elemental ○ lower initial cost Sulfur Disadvantages: ○ handle lower SO2 content gas Catalytic Oxidation of Sulfur Dioxide ○ no salvage value when worn out Contact Process Absorption of Sulfur Trioxide in Water Combustion Chamber - brick-lined ○ Dried air and atomized molten sulfur are introduced to the chamber. ○ Atomizing and good mixing are key factors in producing efficient combustion. Waste Heat Boiler - reduces gas temperature ○ Produces high-pressure steam Catalytic Reactor - successive cooling through the heat exchangers Ideal Conditions ○ Most of the SO3 produced is absorbed in As temperature increases, the conversion of SO2 a circulating stream of sulfuric acid. to SO3 decreases. ○ Overall conversion of > 99.7% is At 600K, the rate of reaction is slow achieved after the fourth catalyst bed. 680-751 K (shaded area) is the range of practical operating temperature The successive lowering of temperature Absorption Towers - removes SO3 from the gas between the beds ensures an overall conversion stream before release to the atmosphere of 98-99% ○ SO3 is absorbed in water to produce H2SO4 Platinum Catalysts ○ Have demisters installed to prevent Carriers: silica gel, calcined magnesium sulfate, corrosion and process stack emission and asbestos due to sulfuric acid mist Advantages ○ 90% recovery of metal ○ Lower operating cost ○ Lower initial capital cost; higher proportions of SO2 may be used Disadvantages ○ Suffers a decline of activity with use ○ Shorter life; subject to poisoning under some conditions ○ Difficulty to handle; fragile 22  Lecture 7 - Nitrogen Industry Ammonification ○ The process of converting organic Nitrogen - comprises 78% of the atmosphere nitrogen into ammonia when plants and Cannot be utilized by plants in atmospheric form animals die Essential for the synthesis of amino acids, ○ Carried out by saprophytes like fungi proteins, enzymes and bacteria A limiting nutrient ○ Ammonia is also produced from volcanic eruptions and the excretory Nitrogen Cycle - the circulation or cyclic movement of products of animals. nitrogen from the atmosphere to soil back into the Denitrification atmosphere ○ Nitrates are converted into molecular nitrogen through nitric oxide. ○ Carried out by denitrifying bacteria (e.g. thiobacillus denitrificans) Synthetic Ammonia: History Sources of Fixed Nitrogen Manures Ammonium sulfates (by-product from coking of coal) Ammonia (recovered from coke) Chile Saltpeter (sodium nitrate) Dry distillation of nitrogenous biomaterial waste Nitrogen falls from the atmosphere to the earth by Decomposition of ammonium salts precipitation (e.g. rain or snow). Nitrogen Fixation Haber (Haber-Bosch) process - Fritz Haber and Carl ○ Conversion of atmospheric nitrogen into Bosch, 20th century ammonia Practical and large-scale synthetic ammonia ○ Carried out by leguminous plants and process some bacteria (e.g. azotobacter, Use of abundant and inexpensive elemental H2 clostridium, rhizobium) and N2 gas Nitrification ○ Carried out by nitrifying bacteria (e.g. Synthetic Ammonia: Uses and Economics nitrococcus, nitrosomonas) Fertilizers (ammonium sulfate, DAP, urea) ○ Ammonia is first converted to nitrites Nitric acid then nitrites are converted to nitrates (by Explosives nitrobacter) Fibers, synthetic rubbers, plastics (nylons and other polyamides) Refrigerants Nitrogen Assimilation Pharmaceuticals (sulfonamide, vitamins, etc.) ○ The process of absorbing nitrates and Pulp and paper ammonia into organic nitrogen Extractive metallurgy ○ Organic nitrogen is transferred into Soda ash animals when they consume plants. Cleaning solutions 23 Synthetic Ammonia: Haber-Bosch Process Feedstock Desulfurization Raw Materials Removal of sulfur oxide and hydrogen sulfide ○ Air R-SH + H2 → H2S + RH ○ Water H2S + ZnO → ZnS + H2 ○ Hydrocarbons The sulfur is removed to < 0.1 ppm S in the gas Reactions and Equilibrium feed Zinc sulfide remains in the adsorption bed. 1. Manufacture of Hydrogen Steam-water gas process Steam-hydrogen (natural gas) process Coke-oven gas process Return to equilibrium with increase in [N2] Electrolysis of water Return to pressure upon compression Primary (Steam) Reforming Rate and Catalysis of the Reaction Hydrogen and nitrogen react very slowly Catalyst: iron → promoted by the addition of Reformer consists of nickel-based catalysts small amounts of oxides of aluminum and potassium Secondary Reforming Space velocity → cu. ft. of exit gasses in STP (0oC and 760 mmHg) that pass over 1 cu. ft. of catalyst space per hour (usually 20,000 – Only 30-40% of the hydrocarbon react 40,000) Addition of air to convert the unreacted methane 5,000 space velocity, 450oC, 100 atm, pure 3:1 molecules hydrogen-nitrogen mixture: ○ doubly promoted: 13 – 14% ammonia Shift Conversion ○ singly promoted: 8 – 9% ammonia ○ pure iron: 3 – 5% ammonia Catalyst promotion - The process gas from the secondary reformer ○ Melting iron oxide + promoter contains 12 – 15% CO. (protecting bed) The gas is passed through a bed of iron ○ Rapid cooling oxide/chromium catalyst around 400 – 500 ○ Crushing degrees Celsius ○ Poisoning of catalyst Manufacturing Procedure 2. Purification feed stock desulfurization CO2 Removal manufacture of reactant gasses Scrubbing with water, amine solutions, or hot purification potassium carbonate solutions compression CO and Further CO2 Removal (Methanation) catalytic reaction recovery of formed ammonia recirculation and ammonia removal Small amounts of CO and CO2 are removed by conversion to CH4 using Ni catalyst 24  3. Ammonia Conversion Manufacturing Procedure Evaporation of anhydrous ammonia Oxidation of ammonia gas with air (platinum gauze at 920oC) Modern NH3 plants use centrifugal compressors Cooling of nitric oxide for synthesis gas compression. Oxidation and hydration of nitric oxide The synthesis of ammonia takes place on iron Collection of 61 – 65% nitric acid using acid trap catalysts. Waste gas treatment Reaction is highly exothermic Only 20 – 30% is reacted per pass in the converter due to unfavorable equilibrium conditions 4. Ammonia Separation By mechanical refrigeration or adsorption/distillation 5. Ammonia Storage Urea (46% nitrogen) Ammonium nitrate (34% nitrogen) 1. Evaporation of Anhydrous Ammonia anhydrous ammonia is evaporated using steam Air required for all reactions are compressed and mixed with ammonia gas 2. Oxidation of Ammonia Gas with Air NH3 gas is oxidized with air to nitric oxide by passing through a platinum gauze at 920oC 3. Cooling of Nitric Oxide Nitric oxide with excess air is cooled in two heat Nitric Acid: Uses and Economics exchangers and a water cooler Used for the manufacture of ammonium nitrates 4. Oxidation and Hydration of Nitric Oxide (fertilizers) Successive oxidations and hydrations of the Intermediate in polymer industry (polyamides nitric oxide are carried out with continuous and polyurethanes) water cooling in a stainless-steel absorption Oxidizing acid for the parting of gold and silver, tower. pickling of brass, and photoengraving Nitric Acid: Production Raw Materials 5. Collection of Nitric Acid using Acid Trap ○ Anhydrous ammonia 61 – 65% nitric acid ○ Air water and nitric acid form an azeotrope ○ Water 6. Waste Gas Treatment The waste gas from the top of the absorption Reactions and Energy Changes tower is heated and expanded before being exhausted to the atmosphere 25