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Baskaran S.,Tamil Nadu Newsprint and Paper Ltd. | Palanisamy C.,Tamil Nadu Newsprint and Paper Ltd. | Chinnaraj S.,Tamil Nadu Newsprint and Paper Ltd.
IPPTA: Quarterly Journal of Indian Pulp and Paper Technical Association | Year: 2013

Rotary Lime kiln is an integral part of modem Soda Recovery plant in large scale pulp and paper mills. When the lime sludge is recycled, the non process element built up in the lime sludge will increase. The Silica is one of the major non process elements in the lime sludge which adversely affect the operation of limekiln. The Silica buildup in the recovery cycle is more predominant in the mills using agricultural residue like Bagasse and Wheat Straw etc. Two stage causticizing is an apt method to control the Silica level in the system for optimizing the operation of Rotary Limekiln. TNPL is producing 500 TPD of bleached Bagasse pulp and 300 TPD of bleached hardwood pulp. Two stage causticizing has been operated successfully for more than a decade in the mill. In this paper, operation of two stage causticizing system in TNPL and its benefits are discussed along with material balance of causticizing plant and Silica.


Chinnaraj S.,Tamil Nadu Newsprint and Paper Ltd. | Rajesh K.S.,Tamil Nadu Newsprint and Paper Ltd. | Karunanithi P.,Tamil Nadu Newsprint and Paper Ltd. | Baskaran N.,Tamil Nadu Newsprint and Paper Ltd. | Subrahmanyam S.V.,Tamil Nadu Newsprint and Paper Ltd.
IPPTA: Quarterly Journal of Indian Pulp and Paper Technical Association | Year: 2010

Tamilnadu Newsprint and Papers Limited (TNPL) is India's largest bagasse based Integrated Pulp and Paper mill, having an installed capacity of 245,000 TPY Printing & Writing paper and poised to enhance its capacity to 4,00, 000 TPY by middle of Year 2010. It used to consume about 70,000 m3/day water and discharging 55,000 m3/day wastewater where 15,000 m 3/day being accounted for evaporation losses. The mill has decided to go for major water saving program along with pollution load reduction. Mill has implemented Superbatch™ pulping in 300 TPD Hardwood Street and modern ECF bleach operations capacities of 300 TPD hardwood and 550 TPD of bagasse pulp streets. TNPL has implemented recycling of Paper Machine Effluent after clarification, close looping Eop filtrate in hardwood fiberline operations, recycling pump sealing water and gland cooling water etc. All the above measures resulted in conserving the fresh water by 30, 000 m3/Day and brought the specific water consumption to 51 m3/Ton of Paper during December 2009 with concomitant reduction of 40% pollution load (Phase I). TNPL has drawn ambitious ZLD program to be implemented in 3 phases by 2012. Phase II includes brown loop closure in bagasse pulping operations, close looping the water circuits in gland cooling and pump sealing waters, and implementing ZLD for SRP and Energy islands. The Phase III targets at treating the acidic bleach filtrate using physico-chemical-biological pretreatment followed by membrane separation and recovering 90% of water. The sludge generated in this operation will enter appropriate stage in lime sludge cycle and filtrate to be treated with membrane process to segregate the sulphates and chlorides. The sulphates will be sent to chemical recovery and dilute brine water to be concentrated to marketable level. The evaporator condensate is proposed to be segregated into higher and lower contaminated streams and less contaminated stream to be used as DM water after desirable treatment and highly contaminated stream to be used in SRP operations. After Phase III, it is envisaged to control the treated effluent discharge level to less than 15,000 m3/day having inorganic TDS less than 1200 ppm, hence can be reused appropriately.

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