In Wonder Land
Part of the RK Marble Group, Wonder Cement is a greenfield project, a fully automated plant with world-class technology, anchored by a group of experienced entrepreneurs from the house of the Patnis, better known as the marble family in the country. Built with a cutting - edge technology, this state-of-the-art project has made its footprint in the burgeoning market of cement industry in the country within a short span of three years. It is the only plant in North India and among the few in India which is fully automated with the latest world-class technology from ThyssenKrupp and Pfeiffer, a German technology major.
The project was commissioned in April 2012 with an installed capacity of 3.25 million tonne per annum (mtpa) of cement. "This plant was conceptualised in 2010 and built in record time of 18 months, whereas normal period to construct similar plant, according to consultants and major companies, is 28-32 months. We completed the project in 18 months for clinkerisation and 21 months for cement production," says SM Joshi, President - Works, Wonder Cement.
A futuristic plant
Wonder Cement is a plant of 21st century, fully automated with the latest German technology and quality control by Automated Po-Lab (Robotic Lab) with AQCNET Software. The plant is centrally controlled and there are various technological features which are hallmarks of the latest technical developments.
There are various other features which are the hallmarks of the latest technology in the international market. Raw material acquisition and refining, considered to be the most important stages in cement production, are carried out by VRM technology, supplied and installed by Pfeiffer while equipment for processing and clinker grinding has been done by ThyssenKrukpp. Latest packaging technology has been also installed at the plant. Other auxiliary equipment have been sourced from the best vendors in the industry.
"When the plant was being coneptualised, our Chairman wanted to give the best product out of the facility. Therefore we selected machinery from ThyssenKrupp and Pfeiffer, Germany," Joshi explains.
Vivek Patni, Director, Wonder Cement, says, "When we were conceptualising this plant, we kept all provisions for modernisation and future expansions. Our infrastructure is suitable for supporting additional capacity. While planning the infrastructure, we were having consultants for architecture and landscaping. You can see the results here. We have very well planned buildings, roads, and landscaping which is difficult to find in other cement manufacturing facilities.
Raw materials mining
Wonder Cement has an installed capacity of 3.25 mtpa of cement, for which 3.75 mtpa ROM (Run-Of-Mine) limestone is required. The company has two mining leases known as Bhatkotari lime stone mines. The total area of mines is 7.4093 sq km. In the mines, there are more than 506 million tonne proved reserves and more than 25 million tonne probable reserves. The total mineable reserves are more than 477 million tonne. Open cast mining is done in both the mines. Chittorgarh area in Rajasthan is known for its superior quality lime stone deposits, possessing high lime content that gives high early strength and ultimate long term strength. Another characteristic feature of this lime stone is low alkali, low magnesia and low chloride contents which are highly desirable parameters for concrete durability.
Crushing and screening
ROM up to maximum feed size of 1.1x1.0x1.0 cu m 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 1,600 tph. Impactor reduces the size to 75 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 the world´s best Combi CBA having CNA technology also, which is introduced in India for the first time. Approximately 93-95 per cent of materials, limestone and marl, is used from captive mines for the preparation of raw mix for manufacturing the desired quality of clinker. The other additives (5-7 per cent) used after pre-blending by stacker and reclaimer to control the moduli values in the mix. To get consistent quality of in process material, pre-blending equipment are installed for each raw material.
Raw material grinding
The state-of-the-art technology adopted at the plant consists of vertical roller mill of Pfeiffer, Germany, for grinding 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. After the complete process, the finely ground raw material is collected 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 multiclones is de-dusted in the bag house.
For grinding of petcoke/coal, again there is a vertical roller mill having capacity of 35 tph. The operation of this mill is same as in the raw mill. The only difference is to have a constant watch over the mill outlet temperature to avoid any explosion and dust laden gases are de-dusted in bag house.
Wonder Cement plant has a 75 m long kiln having diameter of 5 m for manufacturing OPC clinker supplied by Polysius ThyssenKrupp. The clinker is produced by burning the finely ground raw meal known as kiln feed in a rotary kiln. The temperature in the burning zone is usually 1,400-1,450oC and the residence time in the kiln is 15 minute. 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 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). The clinker formed in kiln is cooled inside the polytrack cooler from 1,450oC to around 110oC and then it is stored in clinker silo having a storage capacity of 45,000 tonne.
The final manufacturing stage at a cement plant is the grinding of cement clinker from the kiln, mixed with 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 WCL, cement grinding circuit is having roll press with closed circuit single chamber ball mill.
At the outlet of the grinding 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 micron fraction is more in comparison to open circuit mill, resulting in higher late strength. The mill ventilation air carries a small portion of the fine material, which is de-dusted in a highly efficient bag-house. Finished product with separator air is passed through multi-clones 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.
Wonder Cement produces three grades of cement: OPC 43, 53 and PPC. Joshi claims, "We produce much higher strength cement than what is required by BIS. Our 53 grade cement is giving a strength of 68-70 Mpa against a requirement of 53 Mpa. The 53 Mpa strength is required after 28 days of setting time. Our cement crosses 53 Mpa in eight days and reaches 68-70 Mpa in 28 days. This type of performance is not available in any other cement in India. This is achieved due to very narrow and uniform particle size distribution of our cement and exceptionally good quality control system."
The present capacity of the plant is 3.25 million tonne per annum (1,80,000 bags per day). The company has a wide network of 2,500 dealers who keep and maintain the supply chain in Rajasthan, Gujarat, Madhya Pradesh, Haryana, Uttar Pradesh, Delhi and Punjab. The company has a team of over 500 dedicated professionals. "We sell 50 per cent of our production in Rajasthan itself. Remaining 50 per cent is sold in the other states adjoining Rajasthan. Right now we are focusing on in and around Rajasthan because the best realisation is available at shortest distance. If you start sending cement to longer distances the realisation will be less," observes Patni.
To ensure uninterrupted power supply to its plant in Nimbahera, the company has installed a captive power plan of 40 MW. The power plant uses petcoke as fuel sourced from IOC´s Baroda plant and Jamnagar refineries of Essar and Reliance. "We always use petcock as fuel for our power plant which is economical. In this area it is almost 25-30 per cent cheaper compared to other fuels," Joshi informs.
Keen on Green
The plant has complied with the norms of the environment ministry. The entire design of the plant is based on the latest environment norms, with the help of reverse air bag house and ESP and a number of nuisance bag filters installed having emission of much below the permissible unit. That enables the plant to be clean and dust free. An ecological balance has been maintained through massive plantation and development of ornamental gardens in the areas around the plant site. A fair measure of company´s concern on environmental issue is seen in the plantation of 55,000 tree saplings in 50 hectare in two years against a target of 75 hectare in 20 years.
Wonder Cement has drawn up an ambitious expansion plan to double the production capacity in the next two years. The company has plans to expand its current capacity to 10 million tonne in due course by setting up a second and third production lines, for which land and layouts are ready. "Our second line is under execution with an expenditure of about Rs 1,200-1,400 crore. It will be ready by end of 2015," Joshi sums it up.