Wonder Cement started off as one of the projects of cement In India, which is a part of R.K.Marble Group. The project was commissioned in April 2012 with installed capacity of 3.25 MTPA of cement. Wonder Cement is truly a plant of 21st Century, The plant is fully automated with latesest world best Germen technology and Quality Control by Automated Po- Lab (Robotic Lab) with AQCNET Software. Plant is centrally controlled and there are various technological features which are hallmarks of the latest technical development.
Schematic Diagram for Cement Manufacturing
CEMENT MANUFACTURING PROCESS
Ordinary Portland Cement (OPC) is a binding agent mainly consisting of calcium oxide (CaO), silicon oxide (SiO2), aluminium oxide (Al2O3) and ferric oxide (Fe2O3). Limestone is the main raw material for manufacturing of cement. The whole process of manufacturing of cement can be divided in the following sections
- Raw Material Grinding
- Coal Grinding
- Cement Grinding
- Cement Packing
The core equipment supplies include
- Stacker reclaimer for limestone ,Raw mix additives, coal and Gypsum
- Pfeifer MPS 5600B raw mill
- Pfeifer 3070BK coal mill
- CF silo
- 6-stage two-string ILC preheater kiln (5.0 x 75 metres) designed for firing low volatile fuels
- Swirlex burner
- Polytrack cooler
- Two Combi circuit cement mills
Wonder Cement Limited at R.K.Nagar Nimbahera has the installed capacity of 3.25 million tons/annum cement, for which 3.75 million tons/annum ROM (Run-Of-Mine) limestone is required. Wonder Cement has two mining leases known as Bhatkotari lime stone mines. The total area of mines is 7.40 Km2.
In the mines, there are more than 330 million tons proved reserves and more than 25 million tons probable reserves. The total mineable reserves are more than 355 million tons. Open cast mining is done in both the mines. Mines ROM is fed to the crusher with the help of dumpers and shovels.
Limestone deposits are mainly extracted by bench mining in which holes are charged with ammonium nitrate and fuel oil explosive and blasted.The rock is excavated with front end loaders (10 m3 capacity) and loaded into55 to 60 tons and then transported to the crusher.Clay and shale normally extracted using front end loaders and loaded into haul trucks. When they occur as overburden the clays and shales not used are stored and often reused for reclamation in the mined out areas of the quarry.
ROM upto max. feed size of 1.1x1.0x1.0 m3 is dumped in crusher dump hopper. Speed regulated apron conveyor below the dump hopper feed this material to grizzly feeder. The -80 mm material goes to the screening plant and +80 mm material is fed to impactor having the capacity of 1600 tph. Impactor reduces the size to 90 mm. In screening plant, -10 mm material (mainly containing clay) is separated and rejected. Rest +10 mm material is again mixed with crusher main product. This mixed material is stored in surge bin. From surge bin, this material is fed to limestone stacker through apron conveyor and belt conveyors. For better blending, the material is stacked in layers in yard with the help of stacker. Pile formation takes place in Chevron method. And online quality control by Cross belt Analyser which is worlds best Combi CBA having CNA technology also.Which is first time introduce in India.
CROSS BELT ANALYSER
- Chittorgarh Area in Rajasthan is known for its superior quality lime stone deposits , possessing high lime contentthat gives high early strength and ultimate long term strength. Another characteristic feature ofthis lime stone is low alkali,Low magnesia and low chloride contents which are highly desirable parameters for concrete durability.
- Approximately 93-95% of materials i.e. limestone & marl is used from captive mines for the preparation of raw mix for manufacturing desired quality of clinker. The other additives (5-7%) used after preblending by Staker and Reclimer to control the moduli values in the mix include Red Ochre, laterite, bauxite etc which are purchased from the outside agencies.
Raw Material Grinding
Vertical Roller Mill :
The state of the art technology adopted at the plant consists of Vertical Roller mill of Pfeiffer , Germany for grinding of Raw Material to achieve the optimum fineness, and controlled particle size distribution of Raw material particles.The capacity of the Raw mill is 550 tph. This mill is supplied by M/s GEER Pfeiffer SE Kaiserslautern Germany, global competitior in cement technology. In the mill, the feed is ground between a horizontal grinding table and three vertical rollers, which are pressed against the grinding table. The grinding table rotates at a speed of 21 rpm. The mill is air swept, this means that the process is depending on a gas flow for material transportation and separation of the material. The retention time of the material inside the roller mill is typically less than one minute. During the movement of the grinding table, the new feed is subject to a centrifugal field. The material on the table will thus be in a constant movement towards the periphery of the grinding table. The material at the periphery of the grinding table will meet the upwards flow of hot gases entering underneath the table. The material is partly dried by the hot gases and at the same time, it is also lifted into the mill compartment. Some of the material is retained by a dam ring placed at the outer periphery of the grinding table. The external re-circulation provided in the system transports the coarser material, dropped from air nozzle ring, by an elevator to the table for further grinding. The smaller particles are on the other hand lifted up to an air separator placed at the top of the mill compartment. In the air separator, the sufficiently fine material is allowed to pass through the separator as finished product. The coarse particles rejected from the separator are transported back to the grinding table for further grinding together with new feed. The finished product is deposited in a set of cyclones installed after the mill. Through air slides below multicones, the product is transported to silo with the help of elevator. The dust-laden air after multicones is dedusted in the bag house.
For grinding of coal, we again have a vertical roller mill having capacity of 35 tph. The operation of this mill is same as narrated for the raw mill. The only difference is to have a constant watch over the mill outlet temperature to avoid any explosions and dust laden gases are dedusted in Bag- House.
Wonder Cement plant has a 75 mtrs long kiln having diameter of 5.0 mtrs for manufacturing OPC clinker supplied by M/s polysiusThyssenkrupp Germany. The clinker is produced by burning the finely ground raw meal (Mixture of Limestone+ Additives like Bauxite & Laterite) known as kiln feed in a rotary kiln. The temperature in the burning zone is usually 1400-1450 deg.C and the residence time in the kiln is 25 minutes. The process taking place in the kiln system consist of a temperature dependent decomposition of the raw material minerals according to the nature, followed by a recombination of the liberated free reactive oxides forming clinker minerals, the most important being C3S(Alite - Tricalcium Silicate), C2S (Belite - Dicalcium Silicate), C3A (Tricalcium Aluminate)and C4AF (TetracalciumAlumino Ferrite). The clinker formation sequence as a function of the temperature can briefly be characterised as follows:
||Description of Process
||Type of Reaction
||Drying & evaporation of free water
||Elimination of absorbed water
||Decomposition of clay minerals
||Kaolinite - Metakaolinite
||Decomposition of Metakaolinite to reactive oxides
||Decomposition of carbonates to free reactive oxides
||Combination of reactive oxides to form intermediate clinker minerals
||Formation of aluminates & ferrites
||Formation of Alite (C3S)
The process takes place in an oxidising environment. Among the chemical process described above, the reaction rate of the first five groups of reaction comprises the decomposition of the minerals in the raw meal and the liberation of reactive oxides is determined by the rate of the heat transfer to the solid material in 6-stage ILC preheater. The reaction rate of the two last groups of clinker forming reactions is determined in the rotary kiln by the contact rate of the mutual chemical reactive compounds present in different solid phases and later in the burning zone by the diffusion of the reactive compounds in the clinker melt. The overall chemical reactions transforming the mixture of raw material minerals in the raw meal to the mixture of the clinker minerals in the clinker is endothermic (heat consuming). Clinker formed in kiln is cooled inside the Polytrack cooler from 1450 deg.C to around 110 oC and then it is stored in clinker silo having a storage capacity of 45000 tons.
The final manufacturing stage at a cement plant is the grinding of cement clinker from the kiln, mixed with some 4-6% gypsum, into a fine powder. It is important to obtain a certain specific surface for the finished cement so that hydration can take place and concrete strength develops within a reasonable time. In addition to the specific surface, also the particle size distribution influences the strength properties especially the late strength.
At Wonder Cement, we have two combi circuit grinding ball mills with roller press having capacity of 200 tph each. Two dosimat feeders feed the material, clinker & gypsum. Gypsum is mixed with clinker during grinding operation for retarding setting time and to increase the workability of cement. Clinker and gypsum in required proportions are fed to roller press the output of the roller press pass through V-separator and product of V-separator feed to the single chamber ball mill through the inlet chute of the mill. The mill inlet consists of a chute for material and a pipe for sucking in ventilation air. The air intake is provided with a throttle valve so as to ensure a suitable negative pressure at the inlet and to avoid dust nuisance around the surrounding area. The grinding is affected by grinding media.. A charge consisting of 25, 20 and 15 mm steel balls is used in chamber for fine grinding. Total approximately 155 MT grinding media is loaded in each mill.
At the outlet of the mill, the ground material flows through an outlet grate to dynamic separator by mechanical conveyors, for fine separation as grinding system is closed circuit mill. Grinding in close circuit makes it possible to obtain a very finely ground cement. Another advantage is that it is easy to change from one grade of cement to another grade by adjustment of the separator speed . Cement produced in closed circuit mill has narrow particle size range and the quantity of 3 to 30 microns fraction is more in comparison to open circuit mill, resulting in to more late strength. The mill ventilation air carries a small portion of the fine material, which is dedusted in highly efficient Bag-House.
Finished product with separator air is passed through multiclones where finished product is separated and stored in cement silos with the help of mechanical conveyors.
Cement is stored in four cement silos, extracted, bagged by three electronic roto packers of capacity 240 TPH each with an accuracy of +50 gm and -0 gm, and transported by trucks. We are having loading facility for loose cement .
To control consistency in compressive strength performance of Cement Latest PGNAA+PFTNAA (On Line Analyzer Gamma Matrix) is installed and control the incoming raw material quality, Fully automatic Quality Control Lab Polab equipped with XRF & XRD (X Ray Florescence & X-ray Diffraction ) ARL and Particle size analyzer (Malvern) for better control constancy in raw mix is installed and SQC implemented First time in India.
Insure 100% Confirm material, Before grinding Finish Product (Cement) by strict checking in process material at different stages. To control early setting time – Raw Mix with three Modulus Control is used .
AQCNET/POLAB configuration consists of a standard industrial robot placed in the center of a circular arrangement of sample preparation and analytical equipment. Samples normally arrive automatically from the connected automatic sample transport system, but may also be entered via operator sample conveyors or special input/output magazines.
AQCNET/POLAB offers a very high flexibility in terms of the number and types of equipment handled by the robot. Supported, fully automated preparation & analysis disciplines relevant to the cement industry include powder or fused bead preparation for X-ray analysis, particle sizing by laser or by conventional sieving, analysis, Sulphur/Moisture combustion analysis, physical testing and collection of shift/daily composites. For the typical cement lab project a through put capacity of 10-20 samples will apply; but higher numbers in one robot cell are achievable (240 Nos Samples/Day).The POLAB computer integrates the system components. It identifies incoming samples, downloads the relevant sample-handling specification and controls all intelligent devices in the configuration. Sequence control includes priority handling, intelligent handling of equipment failure situations and much more . AQCNET/POLAB provides high quality in sample preparation and analysis .Quality not only meets the performance of the very competent lab Scientist, but is highly consistent over time. Thus, there are no fluctuations from shift to shift in analytical levels due to small differences in the practical procedures undertaken by human operators. Sr.No Sampling SamplingNo.of samples per material Frequency day 2 Raw Mill Every Hour 1 Kiln Feed Every Hour, 1 Clinker sample Every Hour,2Cement(Grinding) Every Hour ,2 Cement(Packing) Every Hour 1 Coal Every 2 Hours AQCNET/POLAB. Sample receipt Identification & registration Sample splitting & dosing Individual sample preparation recipes Priority management Alternative routing in failure situations Integrated control & dynamic supervision of Sample transport PLC,Robot,Prepequipment,Analysis instrumentsPOLYCIUS experiences with robot automation : mature technology; industrial robots have very high availability client dedication proper & detailed design is mandatory robotics equipment prices fall too high expectations for labor cost savings pay-back time : o 3 to 5 years achievable o Can be difficult to justify solely on manpower savings Difficult to put value on higher & consistent quality unbalanced technologies : often too high client emphasis on sublime technology in the laboratory, while sampling quality is neglected
AQCNET/POLAB : Sampling is done at different stages like Raw Mill sample C.F.silo sample Kiln feed sample Clinker sample Ground cement sample Despatch cement sampleTime Required for one sample analysis - Just 18 Min.General Quality Assurance measures: Nimbahera Lime Stone Known for their excellent compressive strength Thorough Checking of all incoming raw materials as per the set standards and rejection of sub standard material if any Modern Cement plant with Proven German Technology Worlds best combi circuit mill for cement grinding AQCNET/POLAB for automatic sampling and accurate testing Tamper proof packing
AMT (Advance Module Technology)
Automated Sample collection and preparation for XRF analysis.
POLAB® AMT (Advanced Module Technology) optimally integrates and harmonises allrequired sample preparation and analysis components – and still has an extremely small footprint.
The AMT configuration is designed to ensure the highest standard of efficiency and provides impressively high sample throughput rates, easy operation and consistent modularity.The sample reception and preparation units (such as pneumatic tube, fine grinding,tablet pressing and cleaning modules) as well as the analyser units (such as fluorescence spectrometer, diffractometer,laser granulometer and colour difference analyser) are all placed within reach of the robot.The 6-joint robot supplies all the analyser units with prepared samples and thus supports simultaneous analyses.
Pneumatic tube module
The samples of all initial, intermediate and finished products that are automatically taken at short intervals from the individual sections of the production process are sent in capsules to the pneumatic tube module.The subsequent volumetric dosing process takes place without contamination and is totally dust-free. The module permits manual loading and removal of pneumatic dispatch capsules, as well as the storage of reserve samples (e.g. for physical investigations).
Optimum process control / regulation
The aim of optimum process control is to provide comprehensive knowledge about the material compositions and properties before and during the production process.On the basis of the spectrometer analysis the x raw meal mixtures are optimally calculated and set x alkali cycles inside the kiln system are controlled and x sulphate phases are determined and the cement quality chemically controlled.The particle size fractions determined in the laser granulometer are the basis for controlling the separator speed or for operation of a higherranking,intelligent mill regulation system, such as POLEXPERT® MCE.Through the application of Rietveld software, the latestgeneration diffractometers generate a complete diffractogram and enable exact identification of all clinker phases in a matter of minutes. This opens up totally new perspectives for regulating the material quality, operating the kilnunder consideration of substitutefuels and optimising the cement manufacturing process.