Portland cement mfg. process for finance, subsidy & project related support contact - 9861458008
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This document provides an overview of cement and the cement manufacturing process. It discusses that cement is produced by heating limestone and clay at high temperatures to form clinker, which is then ground with gypsum. The cement manufacturing process involves grinding raw materials, preheating them in a preheater tower, calcining in a rotary kiln at over 2700°F, and cooling the clinker before finishing grinding it into cement powder. The cement powder is then mixed with water, sand, and rock to form concrete. The cement industry is a large user of energy and emits CO2, but cement kilns can also beneficially reuse hazardous wastes by destroying them at high temperatures as a means of energy recovery and
Portland cement mfg. process for finance, subsidy & project related support contact - 9861458008
- 1. • What is Cement? • History • Overview of the Cement Manufacturing Process • Brief Overview of Kiln Operations • Why Burn Wastes?
- 2. • A hydraulic cement made by finely pulverizing the clinker produced by calcining to incipient fusion a mixture of argillaceous and calcareous materials • Portland cement is the fine gray powder that is the active ingredient in concrete
- 3. • One Shovel Powder......................Portland Cement • Two Shovels Sand.....................Mineral Aggregate • Three Shovels Rock..................Mineral Aggregate • Add water & mix • Binds & sets to a solid mass
- 5. • Mixture of ingredients into a paste & triggers a chemical reaction - hydration • Reaction forms a gel which coats & fills spaces between the stone/sand; • Hardens into a solid mass that gets stronger & stronger
- 6. • The world’s most widely used building material • Global production is 5 billion cubic yards per year (using approximately 1.25 billion tons of cement)
- 7. Concrete owes its strength and durability to one essential ingredient - Portland Cement Concrete owes its strength and durability to one essential ingredient - Portland Cement
- 8. • Limestone + Shale/Clay + Heat = Clinker + CKD + Exit Gas • Material Temperatures Exceed 2700 o F • Pulverized Clinker + Gypsum = Portland Cement • Cement is powder so fine that one pound contains 150 billion grains
- 9. (cont’d)(cont’d)(cont’d) • Basic Chemical Components of Portland Cement: – Calcium (Ca) – Silicon (Si) – Aluminum (Al) – Iron (Fe) • Typical Raw Materials: – Limestone (CaCO3) – Sand (SiO2) – Shale, Clay (SiO2, Al2O3, Fe2O3) – Iron Ore/Mill Scale (Fe2O3)
- 10. (cont’d)(cont’d)(cont’d) • Calcareous Component (providing Lime - CaO) – limestone – marly limestone – chalk – coral limestone – marble – lime-sand – shell deposits – lime sludge • Argillaceous Component (SiO2, Al2O3, and Fe2O3) – clay – shale – calcareous marl – marl – marly clay – tuff, ash – phyllite, slate – glass
- 11. (cont’d)(cont’d)(cont’d) • Clinker Chemistry – Tricalcium silicate (3CaO.SiO2), (50-70%) – Dicalcium silicate (2CaO.SiO2), (15-30%) – Tricalcium aluminate (3CaO.Al2O3), (5-10%) – Tetracalcium aluminoferrite (4CaO.Al2O3.Fe2O3), (5-15%)
- 12. Tricalcium Silicate Tricalcium Aluminate CaO CaO CaO SiO2 CaO CaO CaO Al2O3
- 14. • First cements produced by early Greeks and Romans from volcanic ash mixed with slaked lime • This art was lost during the Middle Ages • Portland cement developed in England by bricklayer Joseph Aspdin in early 1800’s • Called “Portland” because concrete made with it resembled natural stone from the Isle of Portland
- 15. • First rotary kiln designed to produce Portland cement patented in 1885 by Frederick Ransome • First economical U.S. kilns developed by Atlas Cement Company in 1895 • Thomas A. Edison first developed long kilns (150 feet compared to 60 to 80 feet)
- 16. • Requires 80 separate & continuous operations • 1990 - 6th in the nation for energy usage • 18,700,000 tons of coal burned in the U.S. (value of $748,000,000) • 1,398,400,000 kW of power used (value of $700,000,000) • A one million ton plant requires approximately $175 million in capital
- 17. • Wet Process • Dry Process - 74% of cement produced • Preheater/Precalciner Process
- 18. • Wet process easiest to control chemistry & better for moist raw materials • Wet process high fuel requirements - fuel needed to evaporate 30+% slurry water • Dry process kilns less fuel requirements • Preheater/precalciners further enhance fuel efficiency & allow for high production rates
- 19. gas flow 2,000 °F 3,200 °F F ( gas temperatures( gas temperatures °F )) x The kiln is a continuous stream process vessel in which feed and fuel are held in dynamic balance x 5 distinct process functions are performed in the kiln: xDry xPreheat xCalcine xSinter xCool 1900°F 550°F material flow
- 20. Preheater Precalciner Kiln •There are still five jobs to be done •Drying •Preheating •Calcining •Sintering •Cooling Dry Process Preheater/Precalciner System 60% Fuel Split 40%
- 22. xx Typically shale provides the argillaceous components:Typically shale provides the argillaceous components: xx Silica (Silica (SiO2, Aluminum(, Aluminum(Al2O3) & Iron () & Iron (Fe2O3)) xx Limestone provides the calcareous component:Limestone provides the calcareous component: x Calcium Carbonate (CaCO3 )) xx Raw materials may vary in both composition andRaw materials may vary in both composition and morphology.morphology. limestone shale
- 24. kiln feedkiln feed pumppump limestone shaleshale 30%30%70%70% 32% water32% water slurry millslurry mill Kiln Feed PreparationKiln Feed Preparation basinsbasins xx Proportioning of feed stock.Proportioning of feed stock. xx Size reduction to < 125µ.Size reduction to < 125µ. xx Control of moisture.Control of moisture. xx Blending to reduce standard deviation.Blending to reduce standard deviation. xx Uniform delivery rate of feed to the Kiln.Uniform delivery rate of feed to the Kiln.
- 25. Figure 4 : Vertical Roller Mill Product Hot Gas from Pre-heater Hot Gas Generator C L A Y L I M E I R O N F L Y A S H Rejects Water Spray Fresh Feed Mill Fan Recirculation Kiln Feed •Proportioning •Drying •Grinding
- 28. cement mill clinker gypsumgypsum 5%5%95%95% additive up toup to 15%15% Separator Fines Finish Grinding System Rejects ••Clinker, gypsum, and optional additives are weighedClinker, gypsum, and optional additives are weighed to proper proportions and ground in the cement mills.to proper proportions and ground in the cement mills. ••Additives may include: Fly-ash, Limestone…..Additives may include: Fly-ash, Limestone…..
- 29. Cement Kiln the Largest Moving Equipment in any Manufacturing Operation Cement Kiln the Largest Moving Equipment in any Manufacturing Operation And the Hottest
- 30. • High temperature • Long residence time • Natural alkaline environment • CKD is only by-product of the process • Thermal stability
- 31. Kiln Process ControlKiln Process ControlKiln Process Control • Critical Parameters: Fuel, Feed, Kiln Speed, Gas Flow • Kiln Temperatures - Burning Zone • Kiln Stability • Chemistry • Instrumentation
- 32. gas flow 2,000 °F 3,200 °F F ( gas temperatures( gas temperatures °F )) 1900°F 550°F material flow Critical Parameters: Fuel, Feed, Kiln Speed, Gas Flow Kiln Temperatures
- 33. Wet Kiln Process Material and Gas Temperatures Wet Kiln Process Material andWet Kiln Process Material and Gas TemperaturesGas Temperatures
- 34. Preheater Precalciner Kiln Dry Process Preheater/Precalciner System 60% Fuel Split 40%
- 35. Dry Kiln Process Material and Gas Temperatures Dry Kiln Process Material andDry Kiln Process Material and Gas TemperaturesGas Temperatures
- 36. T.D.F. A typical wet kiln burns about 400# of fuel to make a ton of clinker (5.0 mmBtu/ton of clinker) Fuels can be any combustible hydrocarbon such as: x coal, coke, natural gas, used motor oil, wood, tires, cellulose others. Coal & Pet Coke
- 37. A cement kiln is a proven technology for recycling by beneficial REUSE of solid and hazardous wastes The benefits are: – energy recovery – material recovery – economics – environmental preservation
- 38. Federal & State Established Priorities for Industrial Waste Disposal Federal & State Established PrioritiesFederal & State Established Priorities for Industrial Waste Disposalfor Industrial Waste Disposal • Reduction at the source • Recycling • Energy recovery • Incineration • Stabilization • Landfill
- 39. • Allows for reuse of waste materials • Conserves virgin fuels & raw materials • Regulated stringently for environmental protection
- 40. • Waste fuels are destroyed, releasing heat, water and carbon dioxide • Solid materials are physically and chemically combined in the clinker product
- 41. Cement Kilns - Excellent Environment for Destroying & Recycling Wastes Cement Kilns - Excellent EnvironmentCement Kilns - Excellent Environment for Destroying & Recycling Wastesfor Destroying & Recycling Wastes A Cement Kiln Provides: • 3,000oF + Flame • Long retention times of gasses and materials • Stability of a large dependable industrial process • Many inherent safeguards
- 42. A Cement Kiln Is A Proven Technology For Beneficial REUSE of Otherwise Waste Materials A Cement Kiln Is A ProvenA Cement Kiln Is A Proven Technology For Beneficial REUSE ofTechnology For Beneficial REUSE of Otherwise Waste MaterialsOtherwise Waste Materials The Benefits are: • Energy Recovery • Material Recovery
- 43. Energy Replacement for Coal/Coke • Liquid fuels • Solid fuels Material Replacement for Raw Materials (Limestone, Shale and Sand) • Solids/sludge slightly contaminated with metals • Solids/sludge slightly contaminated with organics
- 44. From Quarry…to Kiln…to Construction SiteFrom Quarry…to Kiln…to Construction SiteFrom Quarry…to Kiln…to Construction Site Thank You !Thank You !