Report of Cement Industry
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The internship report outlines a 15-day experience at Lucky Cement, a major Pakistani cement producer, detailing its operations from quarrying to cement production. Key processes discussed include blasting and mining for raw materials, crushing, grinding, pyro-processing, and packaging. The report also highlights areas for safety improvements and operational efficiency within the production process.
Report of Cement Industry
- 1. Internship Report Internship Duration (15 days, 14-29th Dec 2018) Noman Zia Batch-17 Chemical Engineering D-17-CH-05
- 2. Introduction: Lucky Cement is a part of one of the largest business groups in Pakistan, the Yunus Brothers Group. Lucky Cement Limited was founded in 1993 by Abdur Razzak Tabba. The company started with factories in the Pezu located in Lakki Marwat District, district of the Khyber PakhtoonKhwa (KPK). It now, also, owns a factory in Karachi. Lucky Cement Limited (LCL) is one of the largest producers and leading exporter of quality cement in Pakistan with the production capacity of 7.75 million tons per annum. The company is listed on Karachi, Lahore, Islamabad, and London Stock Exchanges.
- 3. Table of Contents Quarry Crusher Stacker & Reclaimer VRM (Vertical Raw Mill) Pyro-Process (Pre-heater, Kiln & WHR section) Mixing of Gypsum & Final Grinding Packaging
- 4. Quarry Total Area: 11KM2 Number of Phases: 7 Most limestone enriched phase: #5 Factors affecting the composition of raw material w.r.t area is regarded as Budge Formation. Quarry operation consist of 2 parts, • Blasting • Mining Blasting: For blasting bores are drilled in the desired place using a diamond rotary driller deeper than the bench height in order to avoid TOW, this is called sub-drilling, once the holes are drilled explosives are dosed into the bores. Bores are drilled with spacing of 4.5m and burden of 4m. The following types of explosives are used, 1. Blaster 2. Super Blaster Both consist of a set of proportions of these 2 materials, • Aculite (High Explosives) • Ammonium Nitrate (Low Explosives) Most commonly for blaster 20% Low Explosives and 80% high explosives and vise versa for Super blaster. 3 types of cords are used to control the explosions • Explosive cord: Burning rate 4000m/h approx. Is attached with the explosives. • Black Cord or ignition cord: Burning rate 110sec/m. used for ignition. • Delay Relay: used to make delay between the explosions of about 50-80ms. Connected between explosive cord connecting two bores of explosives. Mining: After blasting the material is transported to crushing section using Loader and Dumper trucks.
- 5. Crusher: Type of crushers: Hammer Crusher Number of Crushers: 5 • 2 Limestone Crushers • 2 Coal & Clay Crusher • 1 Gypsum crusher Working: Dumper feeds the large rocks into the feed hopper which transfers the feed to the apron conveyer, which dumps the feed into the crusher, first the feed falls on the feed roller which decreases the size of any bulk having a greater size to approximately 1m2, which then passes the feed to the hammer crusher, material is crushed by the hammer roller rotating consisting of 45 total hammers in 5 shafts (each hammer weighing about 120KG) into size of about 70-80mm, which then falls into a chute connecting to delivery tunnel consisting of a delivery conveyer, this conveyer transport the crushed material to long belt. Any material (relatively fine particles) falling off the apron is collected by a discharge belt is dropped into a chute also connecting to delivery tunnel, this dust in delivery tunnel is then picked up by bag filter which is again mixed with the crushed material in delivery belt. There is also a magnet separator to remove any metal fillings present in the crushed feed. All the crushers work generally on the same method and 3 principle laws of crushing (Rittinger’s Law, Bond’s Law and Kick’s Law) Whole Crushing operation is consisting of the following: • Feed Roller • Rotary Hammer (1000KW Motor) • Apron Conveyer (37 KW Motor) • Discharge conveyer (45 KW Motor) • Magnet Separator • Bag Filter
- 6. Stacker & Reclaimer: Delivery tunnel transports the crushed material to long belt, this belt transports the material to piling area, the stacker takes feed from long belt and make piles of the material ready to be transported by the reclaimer, reclaimer consists of a bucket conveyer which picks up material from the piles and transports as per requested amount to the way feeder, Vertical Raw Mill (VRM): Each plant has 2 VRMS one for raw crushed material grinding and one for Clinker and Gypsum grinding, each plant also has a pair of ball mills for optional use. As the 3 Way-feeders drops raw material (Limestone, Clay and Laterite) on long belt in a fixed proportion, it is transported to the feed hopper of the VRM, this then falls onto a rotary feeder which acts as an airlock for the VRM system, as the material enters the VRM it falls through a duct onto a rotating table, grinding is done by 4 220 tons rollers supported and controlled by hydraulic shafts which grinds the material as the material forces its way from under the bottom of roller, fine grinded particles are then fluidized by the hot Flue Gas (around 320 degC) coming from Kiln which increases the temperature of material in VRM and also fluidizes and carries the fine material to classifier connected on the top of VRM, any large particles are declined by the classifier and falls on the rotating table, any uncrushed particles are fallen though damper ring and is called rejected material which is then then picked up by rejected elevator buckets and mixed with hopper feed. The fine material accepted by the classifier is then transported to a set of 4 High efficiency Cyclone separators which separates about 90-95% of fine particles from flue gas, the fine material is then fallen into an air slide which transfer the material to silo elevator and is stored in Raw material Silo, while the flue gas leaving cyclone enters the bag house where 5% of the remaining ultra-fine material is separated and is mixed with the air slide material going to the Raw material Silo while the flue gas is removed to the atmosphere from stack.
- 7. VRM is comprised of the followings: • Damper ring • Rotating table • Center Doming plate • Clamping rings • Table liners • Dam ring • Scatter Ring (Curved ring) • Louvre Ring (Flue Gas Intake) • Armored Ring • 4 Rollers (220 Tons Each) with hydraulic arms • Reject bucket elevator • 4 high eff. separator cyclones • Air slide (with blowers) • Bag house filter • Raw material storage silo
- 8. Pyro-Process: Following process takes place in Pre-heater, kiln & cooling section, • @100 degC free moisture evaporates. • @500 degC chemically combined water decomposes & evaporates. • @900 degC Calcination of CaCO3 starts • @950-1400 degC material starts to melt and causes formation of Alite (Tri-calcium Silicate), Balite (Bi-Calcium Silicate), Tri Calcium Aluminate & Tetra Calcium Alumino ferrate. • Quenching of product to avoid reverse reaction of Tri- Calcium Silicate to Bi-Calcium Silicate. • Hot flue gas is passed to Pre-heater section and heat exchanger, after heat exchanger to WHR plant and bag house.
- 9. Preheater & Pre-Calciner Section: Material from Raw material silo is taken to preheater section in a delivery elevator, the preheater section is composed of 4 single preheater cyclones named (C2-C5) and a two-in-one pre-heater cyclone named (C1), the raw feed enters C1A and C1B mixing with flue gas leaving C2 which then passes on to VRM section. The product from C1A and C1B is then taken to C2 by flue gas leaving form C3, product from C2 is taken to C3 by flue gas from C4 and product from C3 is then transferred to C4 by flue gas leaving C5, product from C4 then enters Pre-Calciner @ about 700- 800 degC while the cyclone C5 only traps any Kiln dust and returns it to Kiln. 90% of process of making clinker completes in pre-heater rest is carried in Kiln at over 1400 degC. Feed from C4 enters pre-Calciner which heats up the feed using TDF and RDF fuels to about 900 degC and then transfers the material to Kiln
- 10. Kiln & Cooling Section: Coal from coal VRM is stored in a fin bin and mixed with the feed in Pre-Calciner and then enters the Kiln which is then heated to around 1400 degC which makes a melt of the feed in which all the desired reaction takes place and following compounds are formed with the emission of CO2 • Alite (Tri-calcium Silicate) • Balite (Bi-Calcium Silicate) • Tri Calcium Aluminate • Tetra Calcium Alumino ferrate. Kiln is supported by 2 hoods, feeding end is connected to pre-calciner and the product end is connected with a cooler & burner, The inclined kiln as it rotates drags the clinker melt to the product end, there the clinker is quenched using fresh air in order to avoid any reverse reaction of product in cooler consisting of perforated plates, fresh air is taken into the system using 5 blowers. The clinker is then taken to clinker silo, while the hot gas is passed in 2 parts one to pre-heater and other to WHR heat-exchanger which is then taken to bag house to remove any dust and then removed to atmosphere using stack. Mixing of Gypsum & Grinding: Gypsum is a very important additive as it controls the setting time of cement, Gypsum is mixed with clinker and then grinded in the final VRM which is then transferred to final storage silo. Products: Following are the products of Lucky Cement Industries: • OPC (Ordinary Portland Cement) • SRC (Sulphate Resistant Cement)
- 11. Suggestion & Margin of Improvements: Overall the process is well optimized but following are the margin of improvement that can be performed • Providing of PPEs to all the workers: Workers weren’t provided with the required personal protection equipment like helmets and we saw many workers working barehand and without any helmet or facemask dosing the explosives in mining area & under conveyer transporting large rocks. Even we weren’t provided with a helmet for about 10 days in our 15 days internship. • Mining & explosion procedure is pretty dangerous as the methods for detonating is very unreliable, as we noticed the engineer fires the detonation cord and rans away on the dumper with worker squad. This can pose harmful results as there’s only time limit of around 110sec for them to get away from the explosion site, and any margin of error can cause casualty, so this procedure can be made safer and better by providing mining engineers with Remote/Wireless detonators. • In crusher one the bag filter inlet should be placed with the discharge belt as majority of the fine dust falling is collected there, this can cause less dust to enter the delivery tunnel. • In VRM cyclone sections there were several spots from where gas was leaking. • In Pre-heater section the elevators were very insecure and on top there were no railing and the base was very frightening just to set footings on. • The Clinker silo was way too open to allow clinker dust to fly-off to the atmosphere which can cause both environmental health and economical losses.