Question

Question

Below is the manufacturing line for cement industry. Determine at which steps, sample quality tests should be placed. State your reason.

quarrying limestone crushing limestone raw mill mining iron ore sand storage and prehomogenization of raw material cement process-technology filter preheating pulverized coal clinker storage pulverized coal raw meal homogenization kiln secondary additives W calcination-burning raw meal to clinker cooling cement storage cement mills cement dispatch bags bulk bulk bulk/bags

Answer 1

Raw Materials Necessary for Portland Cement Manufacture Must Provide the Following

Calcium,Silica,Alumina,Iron

Calcium Iron Sulfate Anhydrite Calcium sulfate Gypsum Alkali waste Aragonite Calcite Cement-kiln dust Cement rock Chalk Clay Fuller's earth Limestone Marble Marl Seashells Shale Slag Blast-furnace flue dust Clay Iron ore Mill scale Ore washings Pyrite cinders Shale Silica Calcium silicate Cement rock Clay Fly ash Fuller's earth Limestone Loess Marl Ore washings Quartzite Rice-hull ash Sand Sandstone Shale Slag Traprock Alumina Aluminum-ore refuse Bauxite Cement rock Clay Copper slag Fly ash Fuller's earth Granodiorite Limestone Loess Ore washings Shale Slag Staurolite

PRODUCTION STEPS

1)Raw materials are crushed, screemed & stockpiled.

2)Raw materials are mixed with definite proportions to

obtain “raw mix”. They are mixed either dry (dry mixing)

or by water (wet mixing).

3)Prepared raw mix is fed into the rotary kiln.

4)As the materials pass through the kiln their temperature is rised upto 1300-1600°

C. The process of heating is

named as “burning”. The output is known as “clinker”

which is 0.15-5 cm in diameter.

5)Clinker is cooled & stored.

6)Clinker is ground with gypsum (3-6%) to adjust setting time.

7)Packing & marketing.

38% W Slurry Wet process Chain System Dry process "Dry" Feed 0-5% W Chain Heat system exchanger "Dry" Feed 0-5% W Dry process with preheating tower

THE CEMENT MANUFACTURING PROCESS:

Quarry

Grinding

Burning

Storage

Packing

Dispatch
38% W Slurry Wet process Chain System Dry process "Dry" Feed 0-5% W Chain Heat system exchanger "Dry" Feed 0-5% W Dry process with preheating tower

THE CEMENT MANUFACTURING PROCESS dumper loader Ô Quarryface 1. BLASTING 2. TRANSPORT crushing storage at the plant conveyor 3. CRUSHING & TRANSPORTATION 1. BLASTING : The raw materials that are used to manufacture cement (mainly limestone and clay) are blasted from the quarry. 2. TRANSPORT : The raw materials are loaded into a dumper. 3. CRUSHING AND TRANSPORTATION : The raw materials, after crushing, are transported to the plant by conveyor. The plant stores the materials before they are homogenized.

THE CEMENT MANUFACTURING PROCESS Raw mill storage at the plant conveyor Raw mix 0 000000 OOOOOO 1. RAW GRINDING preheating < kiln cooling clinker 2. BURNING 1. RAW GRINDING: The raw materials are very finely ground in order to produce the raw mix. 2. BURNING : The raw mix is preheated before it goes into the kiln, which is heated by a flame that can be as hot as 2000 °C. The raw mix burns at 1500 ºC producing clinker which, when it leaves the kiln, is rapidly cooled with air fans. So, the raw mix is burnt to produce clinker : the basic material needed to make cement.

THE CEMENT MANUFACTURING PROCESS Do Gypsum and the secondary additives are added to the clinker. clinker storage Finish grinding 000 OOoooo 000000 000000 1. GRINDING silos DDD dispatch bags LAPARCE RANDEME I IZ 2. STORAGE, PACKING, DISPATCH 1. GRINDING: The clinker and the gypsum are very finely ground giving a “pure cement". Other secondary additives and cementitious materials can also be added to make a blended cement. 2. STORAGE, PACKING, DISPATCH : The cement is stored in silos before being dispatched either in bulk or in bags to its final destination.

Quarry Drilling nig Overturden To Crusher Shale Each raw materia is stored separately To vibrating screen Limestone Raw materials consist of combinations of limestone, cement rock, and shale,clay, sand, or iron ore Primary crusher Secondary crusher Raw materials conveyed to grinding mills 1. Stone is first reduced to 125 mm (5 in.) size, then to 20 mm (3/4 in.), and stored.

Raw mill 4 materials_225tph limestone 88%, sandstone 5%, kaolin/clay 5%, mill scale 2%

2. Raw materials are ground to powder and blended. To air separator 00 TL Limestone Sand Iron orem. lep Oversize Raw mix Kiln Fines Dry Process Dust collector Hot air furnace Raw materials Grinding mill To pneumatic pump are proportioned Dry mixing and Ground raw Or 2. Raw materials are ground, mixed with water to form slurry, and blended. Wet Process Vibrating Screen Oversize Limestone Sand Clay alouoll Water added here Slurry Fines 7 OI Grinding mill Raw materials are proportioned Slurry pumps Slurry is mixed and blended. Slurry Storage basins pump

Το Kiln Dust collector Materials are stored separately Clinker Raw mixis kin burned to partial fusion Coal, oil, gas or other fuel Gypsum Fan Dust bin Rotating kin Clinker cooler linkerar minimal 3. Burning changes raw mix chemically into cement clinker. Rao Materials free water clay decomposes Ist decompona romotion of initial compounds mutial formation of dicacion silicate Tomation or tricalciu silicate den Nation son calcination zone heat clinkering Cooling som sa temp 450 800 1 200 1350 1550 clinar

REACTIONS IN THE KILN . -100°C free water evaporates. . ~150-350C°loosely bound water is lost from clay. ~350-650°C-decomposition of clay-SiO&A1,03 -600°C-decomposition of MgCO3MgO&CO, (evaporates) -900°C-decomposition of CaCO3-CaO&Co, (evaporates) -1250-1280°C-liquid formation & start of compound formation. . -1280°C-clinkering begins. -1400-1500°C-clinkering -100°C-clinker leaves the kiln & falls into a cooler. Sometimes the burning process of raw materials is performed in two stages: preheating upto 900°C & rotary Kiln

4. Clinker is ground with gypsum into portland cement and shipped. Air separator Dust collector Cinker Gypsum T Oversize Fines 1 Materials are proportioned Grinding mill Cement pump Bulk storage Bulk truck Bulk car Box car Packaging machine Truck

Clinker Gypsum " de 2 Thank

Chemical composition of Ordinary Portland cement Portland cement is composed of four major oxides (CaO, SiO2, Al2O3, Fe2O3 >90%) & some minor oxides. Minor refers to the quantity not importance.

CHEMICAL COMPOSITION OF OP.C. Oxide Common Name Abbreviation Approx. Amount (%) Cao Lime C 60-67 Silica S 17-25 Alumina A 3-8 Iron-oxide F 0.5-6 SiO2 Al2O3 Fe2O3 Mgo Na20 KO M 0.1-4 Magnesia Soda N 0.2-1.3 Potassa K SO3 Sulfuric Anhydride 5 1-3 . . Ca0–>limestone SiO2-Al2O3 --Clay Fe2O3 ->Impurity in Clays SO3->from gypsum—not from the clinker .

Microscopic Images of Clinker Alite Belite Ferrite Aluminate

Types of Portland Cement ASTM C 150 (AASHTO M 85) Normal II Moderate sulfate resistance III High early strength IV Low heat of hydration V High sulfate resistance

ASTM Type & Name of P.C. Average Compound Composition Czs ces C3A CAAF 49 25 12 8 Type 1 - O.P.C. General Purpose Type || - Modified For Moderate Heat of Hydration 46 29 co 12 CzS&CzA increased, CS decreased 56 15 12 8 Type III - High Early Strength Type IV - Low Heat P.C. 30 46 5 13 C S increased Type V - Sulfate Resistant P.C. Limit on C3A55%, 2C3A+C4AF<25% 43 36 4 12